Title of Invention	A TYRE HAVING AT LEAST ONE REINFORCING PLY AND METHOD OF MANUFACTURING THEREOF
Abstract	The invention concerns a tyre having at least one reinforcing ply (1, 31, 32) consisting of reinforcing elements embedded in vulcanised rubber, characterised in that said ply reinforcing elements are individually coated with a rubber mixture (B, B1), said coating mixture having a composition and specific physical properties, said reinforcing elements arranged mutually parallel being coated on one surface with a first rubber mixture (A, A1), called first skim coat, of constant composition and properties, whereas said elements are coated on the opposite surface with a second rubber skim coat (C, D) of composition and properties varying according to the meridian position on the ply in the tyre.

Title of Invention

A TYRE HAVING AT LEAST ONE REINFORCING PLY AND METHOD OF MANUFACTURING THEREOF

Abstract

The invention concerns a tyre having at least one reinforcing ply (1, 31, 32) consisting of reinforcing elements embedded in vulcanised rubber, characterised in that said ply reinforcing elements are individually coated with a rubber mixture (B, B1), said coating mixture having a composition and specific physical properties, said reinforcing elements arranged mutually parallel being coated on one surface with a first rubber mixture (A, A1), called first skim coat, of constant composition and properties, whereas said elements are coated on the opposite surface with a second rubber skim coat (C, D) of composition and properties varying according to the meridian position on the ply in the tyre.

Full Text	FORM 2 THE PATENTS ACT 1970 [39 OF 1970] THE PATENTS RULES, 2003 COMPLETE SPECIFICATION [SEE SECTION 10; RULE 13] "A TYRE HAVING AT LEAST ONE REINFORCING PLY AND METHOD OF MANUFACTURING THEROF" SOCIETE DE TECHNOLOGIE MICHELIN, a French company of 23, rue Breschet, F-63000 Clermont-Ferrand, France and MICHELIN RECHERCHE ET TECHNIQUE S.A., a Swiss company of Route Louis Braille, 10 et 12, CH-1763, Granges-Paccot, Switzerland, The following specification particularly describes the invention and the manner in which it is to be performed : The present invention relates to a reinforcing ply for a tyre, and also to the tyre using such a ply as a reinforcement. It also relates to the process for manufacturing such a ply, and to the process for manufacturing the tyre which uses said ply. A reinforcing ply for a tyre is formed of reinforcement elements generally covered on either side with layers " of rubber mix referred to as calendering layers, such that said elements cannot be in contact with the outside. The rubber mix used is generally a single one, of the same composition and of the same properties. It is sometimes highly desirable for the calendering mix to be different for one and the same ply depending on the location of said ply within the tyre using it, be it a carcass reinforcement ply, a crown reinforce-, ment ply, or any other reinforcing ply. According to the teaching of.French Patent 2 351 810, a crown . ; reinforcement having a plurality of plies of reinforce¬ment elements which are parallel to each other within each ply and are crossed from one ply to the next must, in order to increase the life of the tyre, be provided with different characteristics in its central zone and its marginal zones. The tyre of said reference, comprising a carcass reinforcement and a crown reinforcement of a plurality of plies, is characterised in that the calendering rubber mix.of the crown plies has a modulis of elasticity in tension at 100.% longation of greater than 70 Kg/cm2 in. the median zone of the crown reinforcement, which zone is defined by the ratio of the width of said zone to the overall width of said reinforcement, and in that the calendering rubber mix of the same plies has a modulus of elasticity in tension at 100% elongation of less than 4 0 kg/cm2 in the remaining two marginal zones of the crown reinforcement. The teaching of French Patent 1 331 934 relates to a tyre with radial carcass reinforcement, and the invention described consists in stiffening the bottom part of the sidewalls, by imparting thereto a lesser rigidity than that permitted by the solution currently used, that is to say, the lateral superposition of crossed cables on the radial carcass reinforcement. To this end, the stiffening of the sidewalls, in the zone between the bead and substantially the mid-sidewall, is obtained by means of at least one ply of meridian reinforcement elements coated in the calendering mix of the carcass reinforcement. In one of the embodiments described, the carcass reinforcement is formed of a single ply of radial metallic cords or cables, which is turned up around the bead wire and ends in the bead, these cords or cables being coated in the zone located between the bead and substantially the mid-sidewall with calendering layers the elasticity modulus of which is at least 350 g/mm2, which modulus is a high modulus compared with the modulus of the remaining calendering mix. Document FR 2 07 5 851 recalls that, in certain tyres with radial carcass reinforcement, the selection of the rubber connecting the reinforcement elements is an essential factor in the appearance or non-appearance of certain defects after travel of the tyre. Thus the selection of a connecting rubber of low elasticity modulus promotes the separation of the carcass reinforcement cables at the end of the upturn of said reinforcement, in the beads and in the regions of the sidewall which are close to the beads, more particularly for the carcass ply which has a high upturn in the sidewalls. Furthermore, the selection of a connecting rubber of high elasticity modulus promotes the tearing of the connecting rubber between carcass reinforcement cables, along the radial lines in the top zone of the sidewalls. To obtain the best results, French Patent 2 075 851 advocates, more particularly for tyres with radial carcass reinforcement, surrounding the cables of relatively elastic material with a layer of coating rubber of relatively high elasticity modulus, said cables being separated by an interstitial rubber mix which is of relatively low elasticity modulus in the top zone of the sidewalls and of relatively high elasticity modulus in the bottom zone of the sidewalls, the coating layer and the interstitial layer having the same moduli in the bottom zone. As for the process for ensuring that in the top zone of the sidewalls the coating rubber of the cables and the interstitial rubber between cables of one and the same ply are of different qualities, while they are identical in the bottom zone, it consists, during the production of the tyre, of arranging, radially to the inside of a ply, calendered cables in a layer of rubber of a first quality, a layer of rubber of a second quality, and during the vulcanisation of the tyre, exerting a tension on the carcass reinforcement cables. Be it one or the other of the prior solutions, be it for a carcass reinforcement or for a crown reinforce¬ment, the processes used for obtaining a reinforcing ply as described do not make it possible, given the many factors affecting the quality of the semi-finished product constituted by the ply in the non-vulcanised state, to obtain the optimum structure of said ply depending on whether it is used in a carcass reinforce- ment or in a crown reinforcement, and even less the effective use thereof in the production of a tyre. The object of the invention is to overcome these disadvantages. It proposes a tyre having at least one reinforcing ply formed of reinforcement elements embedded in vulcanised rubber, characterised in that the reinforcement elements for said ply are individually coated in a rubber mix, referred to as "coating mix", having a given composition and physical properties, said reinforcement elements arranged parallel to each other being covered on one face by a first rubber layer, referred to as "first calendering layer", of constant composition and properties, whereas said elements are covered on the opposite face by a second rubber calendering layer, of composition and properties which are variable according to the meridian position on the reinforcing ply within the tyre. The composition and properties of the first calendering layer may be identical to the composition and properties of the coating mix for the reinforcement elements. Advantageously, said composition and properties of the first layer will be different from those of said coating mix. The reinforcing ply may be a carcass reinforcement ply, for example a radial ply, the reinforcement elements of which may be metallic and/or textile ones: the meridian position is then judged on the meridian length of the ply. The reinforcing ply may be a crown reinforcement ply, for example formed of reinforcement elements which are parallel to each other within said ply and form an acute angle with the circumferential direction of the tyre, or formed of circumferential elements, the meridian position being judged on the axial width of said ply. It may also be any other reinforcement ply commonly or very frequently used in a tyre, such as the bead reinforcement plies, the sidewall reinforcement plies, the meridian position then being able to be compared to a radial height. The process for manufacturing the non-vulcanised reinforcing ply necessary to obtain the ply according to the invention, as a semi-finished product, consists in firstly manufacturing an intermediate product referred to as "one-face calendered ply", obtained by individually coating a plurality of reinforcement elements with a rubber mix by means of an extruder having a plurality of spinnerets, followed by arranging, using a suitable means, said coated elements in parallel lines, maintaining a defined spacing between two adjacent elements, one of the faces of the assembly of coated elements which are obtained being provided with a first non-vulcanised calendering layer also referred to as a supporting layer, by placing said calendering layer in contact with said assembly. The contacting of said calendering layer with the assembly of the coated reinforcement elements may be effected either by simply laying the assembly on the calendering layer or by simply laying the calendering layer on the assembly of reinforcement elements, but preferably in both cases with application of slight pressure on one or both of the components, namely the assembly of elements and the calendering layer. The non-vulcanised "one-face calendered ply" may be used with reinforcement elements coated individually in a rubber mix which is either non-vulcanised or pre-vulcanised. The process relating to the latter possibility comprises an additional step consisting in pre-vulcanising the coating mix at a given temperature by means of a suitable heating means. The "one-face calendered ply", which is obtained continuously, may be wound up on itself, as is known per se, by means of a backing layer, either of fabric or of polyethylene, for example, acting as an anti-adhesion means, to form rolls of ply. Said rolls serve to feed a table for preparing the plies according to whether they are carcass plies or crown plies. As is known per se, the preparation of a carcass ply requires the reinforcement elements to be cut perpendicular to their common direction, so as to obtain the desired meridian length, whereas the preparation of a crown ply requires the reinforcement elements to be cut at a certain angle and for the portions of ply obtained to be butt-jointed to result in the desired circumferential length of the crown ply. The manufacture of the reinforcing ply intended to be used in the tyre is completed and terminated by the addition, to the second face of the "one-face calendered ply" of coated, cut reinforcement elements, of the second calendering layer, said second layer not having constant composition and properties. Said addition may be effected in several ways: either by contacting the "one-face calendered ply", after cutting, with the second calendering layer of composition and properties which are variable according to the meridian position, which layer has been prepared beforehand, for example, on an apparatus independent of the cores or drums for building and/or finishing the non-vulcanised carcass reinforcement and/or tyre blanks (for example, a ply preparation table), said contacting possibly being effected either by laying the "one-face calendered ply" on the second calendering layer, or by laying said second calendering layer on the appropriate face, on which face are visible the coated reinforcement elements of the "one-face calendered ply", said second layer possibly being in the form of bands of mixes of composition and properties which differ from one band to the axially adjacent band, or in the form of a single layer of mix in which the transition from one band composition to another band composition takes place gradually, and/or continuously; or preferably by contacting the "one-face calendered ply", after cutting, with the second calendering layer of composition and properties which are variable according to the meridian position, which layer is prepared on the apparatus used for building and/or finishing the non-vulcanised carcass reinforcement and/or tyre blanks (cylindrical building drum for the carcass reinforcement blank, finishing drum for the tyre blank in toric form), said contacting possibly being effected either by laying the "one-face calendered ply", on which face the coated reinforcement elements are visible, on the second calendering layer initially arranged on the non-vulcanised blank during manufacture, or by laying the second calendering layer on the "one-face calendered ply" predisposed on the blank during production, said second layer possibly being in the two forms referred to above. The characteristics of the invention will be better understood with reference to the following description, which refers to the drawings, illustrating in non-limitative manner several examples of embodiment, in which drawings: * Figure 1 is a diagram, viewed in meridian section, of a tyre comprising crown plies and a carcass ply which are in accordance with one variant of the invention; * Figure 2 is a diagram of a section along A-A, while * Figure 3 is a diagram of a section along B-B, * , Figure 4 is a diagram, viewed in meridian section, of a crown reinforcement composed of two plies, * Figure 5 is a diagram of the different stages of manufacture of a "one-face calendered ply". The tyre shown in Figure 1 is a tyre of the "heavy vehicle" type, of small dimensions 9.00/20 X. It is formed of a radial carcass reinforcement, formed of a single ply (1) of reinforcement elements, in this case inextensible metal cables, which is anchored within each bead to an annular bead reinforcement element, in this case a bead wire (2), to form an upturn (10). Said carcass reinforcement is surmounted radially by a crown reinforcement (3), composed firstly of two working crown plies (31, 32), formed of inextensible metal cables which are parallel to each other within each ply and are crossed from one ply (31) to the next (32), forming angles of between 10° and 45° with the circumferential direction, and in the case described equal to 26° and 18° respectively, and secondly, radially to the outside, of a ply of elastic metal cables which are oriented relative to the circumferential direction at the same angle as the angle of the cables of the radially outermost working crown ply (32) . The crown reinforcement (3) is radially joined to the carcass reinforcement (1) by a layer (8) of rubber mix which is of constant thickness in the central part, and of increasing thickness towards the edges of the crown reinforcement (3). Said crown reinforcement (3) is radially surmounted by a tread (9), which is joined on either side of the equatorial plane to a sidewall mix (7) covering, within the sidewall of the tyre, the carcass reinforcement (1) and providing the join firstly with the mixes (40, 41, 42) reinforcing the bead and, secondly, with the mix (11) protecting said bead and providing the contact with the service rim. An inner coating layer (5) of the tyre cavity and different rubber reinforcements between said layer and the carcass reinforcement complete the tyre. The carcass reinforcement ply (1), in the example described, is formed of inextensible metal cables of steel which are coated in a rubber mix B, the composition of which is such that said mix, in the vulcanised state, adheres perfectly to the brass-coated layer covering the steel of the reinforcement cables. Said cables coated with the mix B are calendered, over the entire meridian length of the outer side of the carcass ply (1), including the carcass ply upturns, by a layer of rubber mix A, the first calendering layer or supporting layer, because this is the layer on or beneath which the carcass ply cables are laid during the manufacture of the "one-face calendered ply". As for the inner calendering layer of the ply (1), which is the second calendering layer C, it is formed of a plurality of circumferential bands or layers of rubber mixes of composition and qualities which differ from one band to the adjacent band, the composition and the properties of a band being selected according to the meridian position of said band on the meridian length of the carcass: from the point T of the bead wire (2) radially closest to the axis of rotation to the point S, point of intersection S between the meridian profile of the carcass ply (1) and the line perpendicular to said profile lowered by the end of the upturn (10) of the ply (1), the zone TS being referred to as "bead zone", the layer C is formed of a first band C, of rubber mix. From said point T to the point R representing the end of the upturn (10) of the carcass ply (1), the zone TR being referred to as the "upturn zone", the layer C is formed of a second band C2 of rubber mix (Figure 2 shows the different layers in the bead zone of the tyre). Between the point S and a point of intersection V of the centre axis of the meridian profile of the carcass ply (1) with a straight line parallel to the equatorial plane and distant from said plane by a quantity which may be between 3 0% and 45% of the axial width of the tread (9), in the case described equal to 35% of said tread width, the zone SV being referred to as the "sidewall and shoulder zone", the layer C is formed of a third band C3 of rubber mix. Between the point V and the equatorial plane XX" forming the so-called crown zone, the fourth band C4 of mix forms the layer C. In the example illustrated in Figures 1 to 3, the layers or bands A, B, C1, C2 and C4 are formed of one and the same rubber mix which, in the vulcanised state, has a secant modulus of elasticity in tension, measured at a relative elongation e of 0.1 (the modulus thus defined is determined in accordance with Standard AFN0R-NF-T46-002 under normal conditions of temperature and humidity in accordance with Standard AFNOR-NF-T40-101, and will be referred to more simply as "modulus" in the rest of the description), which lies between 6 MPa and 12 MPa, whereas the mix of the calendering layer C3 of the part of the carcass ply (1) in the sidewall and shoulder zone is formed of a rubber mix, the modulus of which of the same name and measured under the same conditions is substantially lower, since it is between 3.5 MPa and 5 MPa. The first mix above, in the non-vulcanised state, has a relatively high Mooney viscosity of between 60 MU and 90 MU, whereas the mix of the layer C3 has a lower viscosity of the same name since it is between 55 MU and 75 MU (the Mooney viscosity being measured in accordance with Standard AFNOR-NF-T4 3-005). For another dimension of tyre, and according to the endurance damage encountered on such a dimension, the coating layer B will be produced with a mix of very high modulus of between 27 MPa and 45 MPa, and of very high Mooney viscosity of between 70 MU and 100 MU, whereas the supporting layer A will be formed of a mix of lower modulus than the previous one, but one which is still high, since it is between 10 MPa and 15 MPa, and having a high Mooney viscosity which itself is high and lies between 60 MU and 90 MU. The layer C, will be formed of the same mix as the layer A; on the other hand, the layer C2 will be a band of a mix having a modulus which is low, since it lies between 3.5 MPa and 5 MPa, and having a lower Mooney viscosity of between 55 MU and 75 MU, which mix will also be that of the band C3, whereas the layer C4 will be produced with a mix of intermediate modulus, of between 6 MPa and 12 MPa, and of a viscosity of between 60 MU and 90 MU. Another beneficial solution consists in selecting as rubber mix for the supporting layer A a mix of low elasticity modulus in the vulcanised state, and using said supporting layer as internal liner of the carcass ply (1), the layers C"1, C"3 and C u then forming the outer calendering layer C of the carcass ply (1). The mix of layer B will be identical to that of the previous example, the mix of layer A will be the mix forming the layer C2 of the previous example with a modulus of between 3.5 MPa and 5 MPa, and a viscosity of between 55 MU and 75 MU. From a point U on the carcass ply upturn which is located radially substantially at mid-height of said upturn (10) to the point S previously described, passing beneath the bead wire (2), the band C"1 is formed of a mix of high elasticity modulus of between 10 MPa and 15 MPa, and of high viscosity of between 60 MU and 90 MU, whereas from said point U to the point R of the end of the upturn (10) , the band C"2 will be formed of the same mix as that forming the supporting layer A. The same applies for" the layer C"3 from the point S to the point V, whereas the layer Cu will be formed of the same mix as that forming the layer C4 of the previous example. It will not constitute straying from the scope of the invention if the layer C, be it the inner or outer calendering layer, is obtained by winding a strip of rubber mix, the composition and the properties of which vary continuously, and/or the passage or transition from one composition of mix in one zone of the carcass ply to the composition of the mix in an adjacent zone is effected gradually (for example passing from the mix forming the layer C3 to the mix forming the layer C4) : the strip for forming the layer C may be obtained, as is Known per se, by kneading and/or mixing on a crusher-mixer one or two quantities of rubber granules (in the example selected, granules of the two mixes forming the layers C3 and C4), the crusher-mixer being fed from a plurality of hoppers each containing a rubber mix of given composition and properties in the form of granules, and the desired quantities being obtained by opening feed chutes, this opening being governed by feed control gates, which makes it possible to obtain a zone of transition between the layers C3 and C4 in which the mix forming C3 gradually changes composition to become the mix forming C4. Figure 4 shows a working crown reinforcement (3) formed of two plies (31) and (32). The working ply (31) radially closest to the axis of rotation is formed of a plurality of metal cables of steel which are coated individually in a rubber mix B1 which, in the example described, has a very high modulus of extension since it is between 15 MPa and 3 0 MPa, and a Mooney viscosity which is likewise high, of between 65 MU and 95 MU. Radially to the inside, there is the first calendering layer or supporting layer A1, which is formed of a single rubber mix of composition and properties which are identical to the composition and properties of the coating mix B1. Radially to the outside, there is the second calendering layer D formed of a plurality of zones of mixes of different composition and properties: a central zone D1, of axial width 1 of between 70% and 90% of the axial width Ls common to the two working plies (31) and (32), is formed of a mix of high modulus of between 15 MPa and 3 0 MPa, and of a viscosity of between 65 MU and 95 MU, which mix is therefore identical to the mixes forming the supporting layer A1 and the coating B1 of the cables; of two lateral bands D2, in the case described of identical width, formed of a rubber mix of a modulus which is relatively low since it is between 3 MPa and 9 MPa, and of a Mooney viscosity of between 50 MU and 85 MU. As for the working crown ply (32) radially farther from the axis of rotation than the ply (31), and of axial width less than said ply (31), it is of identical constitution to that of the ply (31), but the supporting layer A1 is then radially located to the outside of the ply and the three zones D1 and D2 of the layer D are radially to the inside of said layer D, such that said three zones of the ply (32) are opposite the three zones of the first ply (31), in particular the lateral zones D2 of mix of low elasticity modulus, which makes it possible substantially to reduce the thickness of the rubber wedge (12) arranged between the two ply edges and to lay it in the form of flat bands during building. The manufacture of the tyre according to the invention requires several preliminary stages before the vulcanisation of said tyre, and in particular the building or manufacture of said "one-face calendered ply". Figure 5 shows a set of reels (100) on which are wound the metal cable intended to be used in the ply to be built. A plurality of cables are sent to an extruder (200), the head of which has a plurality of spinnerets, suitable for coating said cables with the layer (B, B1) of coating mix to a predetermined thickness. Said coated cables are then sent to a tool, in this case a fluted roller (210), which makes it possible to separate each cable from the axially adjacent cable by the desired distance or pitch, and then to a calender (300) having two rollers (310) and (320). A quantity of rubber mix which is to form the supporting layer (A, A1) of the "one-face calendered ply", initially preheated to a temperature making it possible to soften said mix without, however, vulcanising or pre-vulcanising it, is introduced between the two rollers (310) and (320). The passage between the two rollers results in a flat band of mix being obtained, on which the coated cables will make contact with the radially upper part of the upper roller (320). An auxiliary roller (330), referred to as press roller, makes it possible to apply a given pressure to the cables if necessary, this pressure being automatically controlled according to the desired depth of embedding of the cables in the flat band A. A roller (340) correctly lays an anti-adhesion backing strip, generally of polyethylene, either on the face on which the coated cables are visible, or on the opposite face, so as to be able to wind, as known per se, the "one-face calendered ply" on a winding roller (350), intended to supply the cutters and the ply preparation tables, the reinforcement elements being in the direction of the length of the ply. As known per ser the "one-face calendered ply", depending on whether a web width for a carcass ply or a web width for a crown ply is being prepared, is cut either perpendicularly to the common direction of the reinforcement elements, or at a certain angle a relative to said common direction of the reinforcement elements; in the finished tyre, this angle a will be the angle of the elements relative to the circum¬ferential direction of said tyre. The web widths thus obtained are then assembled, butt-jointed, either end-to-end for metallic reinforcement elements, or with one end overlapping the other for textile reinforcement elements. In the case of end-to-end butt-jointing, this can be effected by applying a small flat layer of so-called connecting rubber, laid on the join or placed on one of the edges, then passing beneath the other edge. The web widths thus assembled form the "one-face calendered ply" ready for use, for example, on the means for manufacturing the partial non-vulcanised blank of the tyre. The carcass ply is completed, for example, by laying the "one-face calendered ply" on the different layers of rubber mixes and different bead reinforcement plies pre-arranged on the cylindrical building drum for the cylindrical carcass blank, such that the supporting layer A is arranged radially to the inside. On the visible reinforcement elements of the "one-face calendered ply" there are then laid the different [word missing?] or circumferential layers C1, C2, C3, etc. which are necessary to form the outer calendering layer C, said layers being, in the non-vulcanised state, of thicknesses selected to obtain the desired thicknesses in the vulcanised state, taking into account the shaping ratio of the carcass blank transforming said cylindrical blank into a toric carcass reinforcement blank. Since the carcass ply is finished on the cylindrical building drum, the next stages of said building are the usual steps which are known per se: laying of the anchoring bead wires for the carcass ply, laying the different rubber bead fillers, edging rubbers or others, turning up the edges of.the carcass ply around the bead wires and fillers, etc. The production of a complete crown ply (31) is also finished in the same manner, that is to say, on a building drum for a non-vulcanised tyre blank: after laying, on a non-vulcanised, toric carcass reinforce¬ment blank, the different layers (8) of rubber mixes radially separating the carcass reinforcement (l) from the crown reinforcement (3) there is laid a non-vulcanised "one-face calendered ply", formed of reinforcement elements coated individually in a rubber mix B1, having a given composition and properties, said reinforcement elements arranged parallel to each other being covered on one face by a first rubber layer A1 or supporting layer, of constant composition and properties, said "one-face calendered ply" being placed in contact with a second calendering layer D of composition and properties which are variable according to the axial width of the crown ply (31) in the tyre. As for the manufacture of a working crown reinforcement (3) with two plies (31) and (32), there can be laid on the layers (8) a first "one-face calendered ply", the supporting layer A1 of said ply being radially to the inside, then, on the visible reinforcement elements of said first "one-face calendered ply" there are laid the different layers of rubber mix D1 and D2 forming the second calendering layer of said first crown ply (31), radially closest to the carcass reinforcement. The second crown ply (32) is manufactured identically, but starting with the laying of the layers D1 and D2, which are then covered radially with a second "one-face calendered ply", presented such that the visible reinforcement elements of said second ply are radially to the inside of said ply. The finishing and vulcanisation of the toric tyre blank are then performed in the conventional, known manner. We CLAIM: 1. A tyre having at least one reinforcing ply (1, 31, 32) formed of reinforcement elements embedded in vulcanised rubber, characterised the reinforcement elements for said ply are individually coated in a rubber mix (B, B1), referred to as "coating mix", having a given composition and physical properties, said reinforcement elements arranged parallel to each other being covered on one face by a first rubber layer (A, A1), referred to as "first calendering layer", of constant composition and properties, whereas said elements are covered on the opposite face by a second rubber calendering layer (C, D) , of composition and properties which are variable according to the meridian position on the ply within the tyre. 2. A tyre as claimed in claim 1, wherein the composition and properties of the first layer (A, A1) are identical to the composition and properties of the coating mix (B, Bi) of the reinforcement elements of the ply. 3. A tyre as claimed in claim 2, wherein the reinforcing ply is a carcass reinforcement ply (1) 4. A tyre as claimed in claim 3, wherein the carcass reinforcement ply (1), in its main part on its outer face and in its upturned part on its axially inner face, is calendered with the first layer A of constant composition and properties, whereas the opposite faces are covered with the second calendering layer C of composition and properties which are variable according to the meridian length of the ply (1) within the tyre. 5. A tyre as claimed in claim 4, wherein the coating mix B has the same composition and properties as those of the mix of the first calendering layer A, the secant modulus of elasticity in tension of said mix in the vulcanised state, measured at a relative elongation of 0.1, being between 6 and 12 MPa, whereas the Mooney viscosity of said mix in the non-vulcanised state is between 60 MU and 90 MU. 6. A tyre as claimed in claim 4, wherein the second layer C is formed: * of a first band Ci of rubber mix, extending from the point T of the bead wire (2) radially closest to the axis of rotation to the point of intersection S between the centre axis of the meridian profile of the carcass ply (1) and the line perpendicular to said profile lowered by the end of the upturn (10) of the ply (1), the zone TS being referred to as the "bead zone", * of a second band C2 of rubber mix, extending from said point T to the point R representing the end of the upturn (10) of the carcass ply (1), the zone TR being referred to as the "upturn zone", * of a third band C3 of rubber mix, between the point S and a point of intersection V of the centre axis of the meridian profile of the carcass ply (1) with a straight line parallel to the equatorial plane and distant from said plane by an amount which may be between 30% and 45% of the axial width of the tread (9), the zone SV being referred to as the "sidewall and shoulder zone", of a fourth band C4 of rubber mix, between the point V and the equatorial plane XX", forming what is called the "crown zone", the bands C1, C2 and C4 being formed of the same mix, the elasticity modulus of which is between [number missing] MPa and 12 MPa and the Mooney viscosity of which is between 60 MU and 90 MU, whereas the band C3 is formed of a mix, the elasticity modulus of which is between 3.5 MPa and 5 MPa and the Mooney viscosity of which is between 55 MU and 75 MU. 7. A tyre as claimed in claim 2, wherein the reinforcing ply is a ply (31, 32) of the crown reinforcement (3), formed of reinforcement elements which are parallel to each other within said ply and form an acute angle with the circumferential direction of the tyre, the meridian position being judged on the axial width of said ply (31, 32). 8. A tyre as claimed in claim 7, wherein it comprises a crown reinforcement (3) formed of at least two working crown plies (31, 32), the ply (31) radially closest to the carcass reinforcement being calendered on its radially inner face with a first calendering layer Ai of constant composition and properties, and on its radially outer face with a second calendering layer D of composition and properties which are variable according to the axial width of said ply (31), whereas the ply (32) radially to the outside of the ply (31) is calendered on its radially outer face with the first calendering layer Ai of constant composition and properties and on its radially inner face with the second calendering layer D of composition and properties which are variable according to the axial width of said ply (32). 9. A tyre as claimed in claim 8, wherein the rubber mix forming firstly the first calendering layer A1 and secondly the coating mix Bi of the reinforcement elements of the crown ply (31, 32) has, in the non-vulcanised state, a Mooney viscosity of between 65 MU and 95 MU, and in the vulcanised state a secant modulus of elasticity in tension, measured at 10% relative elongation, of between 15 MPa and 30 MPa. 10. A tyre as claimed in claim 9, wherein the second calendering layers D are at least formed of three zones, a central zone D1, formed of a rubber mix having in the vulcanised state a high modulus of elasticity in tension of between 15 MPa and 30 MPa, and in the non-vulcanised state a Mooney viscosity of between 65 MU and 95 MU, and two lateral zones D2 formed of a rubber mix having in the vulcanised state a low modulus of elasticity in tension of between 3 MPa and 9 MPa, and in the non-vulcanised state a Mooney viscosity of between 50 and 85 MU. 11. A tyre as claimed in claim 1, wherein the composition and properties of the first layer (A, A1) are different from the composition and properties of the coating mix (B, B1) of the reinforcement elements of the ply. 12. A tyre as claimed in claim 11, wherein the reinforcing ply is a carcass reinforcement ply (1). 13. A tyre as claimed in claim 12, wherein the carcass reinforcement ply (1), in its main part on its outer face and in its upturned part on its axially inner face, is calendered with the first layer A of constant composition and properties, whereas the opposite faces are covered with the second calendering layer C of composition and properties which are variable according to the meridian length of the ply (1) within the tyre. 14. A tyre as claimed in claim 13, wherein the coating mix B in the vulcanised state has an elasticity modulus of between 27 MPa and 45 MPa and in the non-vulcanised state a Mooney viscosity of between 70 MU and 100 MU, whereas the elasticity modulus in the vulcanised state of the mix of the first calendering layer A is between 10 MPa and 15 MPa and has a Mooney viscosity in the non-vulcanised state of between 60 MU and 90 MU. 15. A tyre as claimed in claim 13, wherein the second layer C is formed: * of a first band C1 of rubber mix, extending from the point T of the bead wire (2) radially closest to the axis of rotation, to the point of intersection S between the centre axis of the meridian profile of the carcass ply (1) and the line perpendicular to said profile lowered by the end of the upturn (10) of the ply (1), the zone TS being referred to as the "bead zone", * of a second band C2 of rubber mix, extending from said point T to the point R representing the end of the Upturn (10) of the carcass ply (1), the zone TR being referred to as the "upturn it zone" of a third band C3 of rubber mix, between the point S and a point of intersection V of the centre axis of the meridian profile of the carcass ply (1) with a straight line parallel to the equatorial plane and distant from said plane by an amount which may be between 30% and 45% of the axial width of the tread (9), the zone SV being referred to as the "sidewall and shoulder zone", of a fourth band C4 of rubber mix, between the point V and the equatorial plane XX", forming what is called the "crown zone", the bands C2 and C3 being formed of the same mix, the elasticity modulus of which is between 3.5 MPa and 5 MPa and the Mooney viscosity of which is between 55 MU and 75 MU, whereas the band C1 is formed of a mix, the elasticity modulus of which is between 10 MPa and 15 MPa and the Mooney viscosity of which is between 60 MU and 90 MU, and that the band C4 is formed of a mix, the elasticity modulus of which is between 6 MPa and 12 MPa and the Mooney viscosity of which is between 60 MU and 90 MU. 16. A tyre as claimed in claim 12, wherein the carcass reinforcement ply (1) in its main part on its inner face and in its upturned part on its axially outer face, is calendered with the first layer A of constant composition and properties, whereas the opposite faces are covered with the second calendaring layer C of composition and properties which are variable according to the meridian length of the ply (1) within the tyre. 17. A tyre as claimed in claim 16, wherein the coating mix B in the vulcanised state has an elasticity modulus of between 27 MPa and 45 MPa and in the non-vulcanised state a Mooney viscosity of between 70 MU and 100 MU, whereas the elasticity modulus in the vulcanised state of the mix of the first calendering layer A is between 3.5 MPa and 5 MPa and a Mooney viscosity in the non-vulcanised state of between 55 MU and 75 MU. 18. A tyre as claimed in claim 16, wherein the second layer C is formed: * of a first band C1 of rubber mix, extending from the point U of the upturn (10) of the carcass ply (1), located substantially at mid-height of said upturn (10), to the point of intersection S between the centre axis of the meridian profile of the carcass ply (1) and the line perpendicular to said profile lowered by the end of the upturn (10) of the ply (1), * of a second band C2 of rubber mix, extending from said point U to the point R representing the end of the upturn (10) of the carcass ply (1), * of a third band C3 of rubber mix, between the point S and a point of intersection V of the centre axis of the meridian profile of the carcass ply (1) with a straight line parallel to the equatorial plane and distant from said plane by an amount which nay be between 30% and 45% of the axial width of the tread (9), the zone SV being referred to as the "sidewall and shoulder zone", of a fourth band C4 of rubber mix, between the point V and the equatorial plane XX", forming what is called the "crown zone", the bands C"2 and C"3 being formed of the same mix, the elasticity modulus of which is between 3.5 MPa and 5 MPa and the Mooney viscosity of which is between 55 MU and 75 MU, whereas the band C 1 is formed of a mix, the elasticity modulus of which is between 10 MPa and 15 MPa and the Mooney viscosity of which is between 60 MU and 90 MU, and that the band C4 is formed of a mix, the elasticity modulus of which is between 6 MPa and 12 MPa and the Mooney viscosity of which is between 60 MU a:nd 90 MU. 19. A tyre as claimed in claim 1, wherein the reinforcing ply is a crown reinforcement ply formed of circumferential elements. 20. A tyre as claimed in claim 1, wherein the reinforcing ply is a bead reinforcement ply. 21. A tyre as claimed in claim 1, wherein the reinforcing ply is a sidewall reinforcement ply. 22. A process for manufacturing a tyre as claimed in claims 3 or 12, consisting, firstly, of building on a drum a non-vulcanised cylindrical carcass reinforcement blank comprising at least one carcass ply (I) , wherein the building of the carcass ply (1) requires, after the laying on the cylindrical building drum for the cylindrical carcass reinforcement blank of the different layers of rubber mixes and different bead reinforcement plies, the laying of an intermediate product referred to as "one-face calendered ply", which is non-vulcanised and formed of reinforcement elements coated individually in a rubber mix B, referred to as "coating mix", having a given composition and physical properties, said reinforcement elements arranged parallel to one another being covered on one face with a first rubber layer A, referred to as "first calendering layer" or "supporting layer", of constant composition and properties, said "one-face calendered ply" being brought into contact with a second calendering layer C of composition and properties which are variable according to the position on the meridian length of the ply (1) within the tyre. 23. A process as claimed in claim 22, wherein the non-vulcanised "one-face calendered ply" is used with reinforcement elements coated individually in a non-vulcanised rubber mix B. 24. A process as claimed in claim 23, wherein the non-vulcanised "one-face calendered ply" is used with reinforcement elements coated individually in a rubber mix B which is pre-vulcanised at a given temperature using a suitable heating means. 25. A process as claimed in one of claims 22 to 24, wherein the contacting is effected by the laying, on the different layers of rubber mixes and the different bead reinforcement plies covering the cylindrical building drum for the cylindrical carcass reinforcement blank (1), of the "one-face calendered ply" of coated reinforcement elements, and the laying on the visible coated elements of the "one-face calendered ply" of the second calendering layer C of composition and properties which are variable according to the meridian length of the ply (1) within the tyre, 26. A process as claimed in one of claims 22 to 24, wherein the contacting is effected by the laying, on the different layers of rubber mixes and the different bead reinforcement plies covering the cylindrical building drum for the cylindrical carcass blank (1), of the second calendering layer C of composition and properties which are variable according to the meridian length of the ply (1) within the tyre and the laying on said second layer of the "one-face calendered ply" of coated reinforcement elements, said elements being laid on the second layer C. 27. A process for manufacturing a tyre as claimed in claim 7, consisting, at a given instant, of arranging on a non-vulcanised toric carcass reinforcement blank (1) a crown ply (31, 32) of reinforcement elements which are parallel to each other within the ply and form an acute angle with the circumferential direction, wherein the building of the crown ply (31, 32) requires, after the laying on the toric carcass blank of the different layers (8) of rubber mixes radially separating the carcass reinforcement (1) from the crown reinforcement (3), the laying of an intermediate ply referred to as "one-face calendered ply", which is non-vulcanised and formed of reinforcement elements coated individually in a rubber mix Bi, referred to as coating mix, having a given composition and physical properties said reinforcement elements arranged parallel to one another being covered on one face with a first rubber layer Ai or supporting layer, of constant composition and properties, said "one- face calendered ply" being brought into contact with a second calendering layer D of composition and properties which are variable according to the axial width of the crown ply (31, 32) within the tyre. . 28. A manufacturing process as claimed in claim 27 for a tyre having a crown reinforcement (3) formed of two plies (31, 32) as claimed in claim 8, wherein there is laid: a) on a non-vulcanised, toric carcass reinforcement blank (1), a "one-face calendered ply", the supporting layer A1 of said ply being radially to the inside, b) then, on the visible reinforcement elements of the "one-face calendered ply", the second rubber calendering layer D of the radially inner crown ply (31), which layer is of composition and properties which are variable according to the axial width of the ply within the tyre, the layers A1 and D forming the crown ply (31) closest to the carcass reinforcement (1) with the coated elements, c) then the second rubber calendering layer (D) of the crown ply (32) radially adjacent to the inner ply (31) , which layer is of composition and properties which are variable according to the axial width of the ply (32) within the tyre, d) then, radially to the outside, the "one-face calendered ply", presented such that the visible reinforcement elements are radially to the inside. 29. A process for manufacturing a non-vulcanised "one-face calendered ply" formed of reinforcement elements coated individually in a pre-vulcanised rubber mix (B, B1) as claimed in any of the preceding claims, wherein the reinforcement elements coming from winding reels (100) are sent to an extruder (200) the head of which comprises a plurality of spinnerets, suitable for coating said elements with the layer (B, B1) of coating mix to a predetermined thickness, then are sent to a means (210) making it possible to separate each cable from the axially adjacent cable by the desired pitch, to arrive at a calender (300) with two rollers (310) and (320), which makes it possible to obtain a flat band of supporting calendering mix (A, A1) , on which the coated elements will make contact with the radially upper part of the upper roller (310) , an auxiliary means (330), referred to as "presser means", making it possible to apply a pressure to the coated elements, which pressure is automatically controlled according to the desired depth of embedding of the elements within the supporting layer (A, A1) and a roller (340) laying an anti-adhesion backing strip on one of the faces of the ply coming from the calender (300), so as to be able to wind said ply on a winding drum (350) , and then to make the cuts at the desired angle, to form web widths which can be butt-jointed and to obtain the "one-face calendered ply". Dated this 7th day of August, 2001. (RANJNA MEHTA DUTT) OF REMFRY & SAGAR ATTORNEY FOR THE APPLICANTS

Full Text

FORM 2
THE PATENTS ACT 1970
[39 OF 1970]
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[SEE SECTION 10; RULE 13]
"A TYRE HAVING AT LEAST ONE REINFORCING PLY AND METHOD OF
MANUFACTURING THEROF"
SOCIETE DE TECHNOLOGIE MICHELIN, a French company of 23, rue Breschet, F-63000 Clermont-Ferrand, France and MICHELIN RECHERCHE ET TECHNIQUE S.A., a Swiss company of Route Louis Braille, 10 et 12, CH-1763, Granges-Paccot, Switzerland,
The following specification particularly describes the invention and the manner in which it is to be performed :

The present invention relates to a reinforcing ply for a tyre, and also to the tyre using such a ply as a reinforcement. It also relates to the process for manufacturing such a ply, and to the process for manufacturing the tyre which uses said ply.
A reinforcing ply for a tyre is formed of reinforcement elements generally covered on either side with layers " of rubber mix referred to as calendering layers, such that said elements cannot be in contact with the outside. The rubber mix used is generally a single one, of the same composition and of the same properties.
It is sometimes highly desirable for the calendering mix to be different for one and the same ply depending on the location of said ply within the tyre using it, be it a carcass reinforcement ply, a crown reinforce-, ment ply, or any other reinforcing ply. According to the teaching of.French Patent 2 351 810, a crown . ; reinforcement having a plurality of plies of reinforce¬ment elements which are parallel to each other within each ply and are crossed from one ply to the next must, in order to increase the life of the tyre, be provided with different characteristics in its central zone and its marginal zones. The tyre of said reference, comprising a carcass reinforcement and a crown reinforcement of a plurality of plies, is characterised in that the calendering rubber mix.of the crown plies has a modulis of elasticity in tension at 100.% longation of greater than 70 Kg/cm2 in. the median zone of the crown reinforcement, which zone is defined by
the ratio of the width of said zone to the overall

width of said reinforcement, and in that the calendering rubber mix of the same plies has a modulus of elasticity in tension at 100% elongation of less than 4 0 kg/cm2 in the remaining two marginal zones of the crown reinforcement.
The teaching of French Patent 1 331 934 relates to a tyre with radial carcass reinforcement, and the invention described consists in stiffening the bottom part of the sidewalls, by imparting thereto a lesser rigidity than that permitted by the solution currently used, that is to say, the lateral superposition of crossed cables on the radial carcass reinforcement. To this end, the stiffening of the sidewalls, in the zone between the bead and substantially the mid-sidewall, is obtained by means of at least one ply of meridian reinforcement elements coated in the calendering mix of the carcass reinforcement. In one of the embodiments described, the carcass reinforcement is formed of a single ply of radial metallic cords or cables, which is turned up around the bead wire and ends in the bead, these cords or cables being coated in the zone located between the bead and substantially the mid-sidewall with calendering layers the elasticity modulus of which is at least 350 g/mm2, which modulus is a high modulus compared with the modulus of the remaining calendering mix.
Document FR 2 07 5 851 recalls that, in certain tyres with radial carcass reinforcement, the selection of the rubber connecting the reinforcement elements is an essential factor in the appearance or non-appearance of certain defects after travel of the tyre. Thus the selection of a connecting rubber of low elasticity modulus promotes the separation of the carcass reinforcement cables at the end of the upturn of said reinforcement, in the beads and in the regions of the

sidewall which are close to the beads, more particularly for the carcass ply which has a high upturn in the sidewalls. Furthermore, the selection of a connecting rubber of high elasticity modulus promotes the tearing of the connecting rubber between carcass reinforcement cables, along the radial lines in the top zone of the sidewalls. To obtain the best results, French Patent 2 075 851 advocates, more particularly for tyres with radial carcass reinforcement, surrounding the cables of relatively elastic material with a layer of coating rubber of relatively high elasticity modulus, said cables being separated by an interstitial rubber mix which is of relatively low elasticity modulus in the top zone of the sidewalls and of relatively high elasticity modulus in the bottom zone of the sidewalls, the coating layer and the interstitial layer having the same moduli in the bottom zone. As for the process for ensuring that in the top zone of the sidewalls the coating rubber of the cables and the interstitial rubber between cables of one and the same ply are of different qualities, while they are identical in the bottom zone, it consists, during the production of the tyre, of arranging, radially to the inside of a ply, calendered cables in a layer of rubber of a first quality, a layer of rubber of a second quality, and during the vulcanisation of the tyre, exerting a tension on the carcass reinforcement cables.
Be it one or the other of the prior solutions, be it for a carcass reinforcement or for a crown reinforce¬ment, the processes used for obtaining a reinforcing ply as described do not make it possible, given the many factors affecting the quality of the semi-finished product constituted by the ply in the non-vulcanised state, to obtain the optimum structure of said ply depending on whether it is used in a carcass reinforce-

ment or in a crown reinforcement, and even less the effective use thereof in the production of a tyre.
The object of the invention is to overcome these disadvantages. It proposes a tyre having at least one reinforcing ply formed of reinforcement elements embedded in vulcanised rubber, characterised in that the reinforcement elements for said ply are individually coated in a rubber mix, referred to as "coating mix", having a given composition and physical properties, said reinforcement elements arranged parallel to each other being covered on one face by a first rubber layer, referred to as "first calendering layer", of constant composition and properties, whereas said elements are covered on the opposite face by a second rubber calendering layer, of composition and properties which are variable according to the meridian position on the reinforcing ply within the tyre.
The composition and properties of the first calendering layer may be identical to the composition and properties of the coating mix for the reinforcement elements. Advantageously, said composition and properties of the first layer will be different from those of said coating mix.
The reinforcing ply may be a carcass reinforcement ply, for example a radial ply, the reinforcement elements of which may be metallic and/or textile ones: the meridian position is then judged on the meridian length of the ply. The reinforcing ply may be a crown reinforcement ply, for example formed of reinforcement elements which are parallel to each other within said ply and form an acute angle with the circumferential direction of the tyre, or formed of circumferential elements, the meridian position being judged on the axial width of said ply. It may also be any other reinforcement ply

commonly or very frequently used in a tyre, such as the bead reinforcement plies, the sidewall reinforcement plies, the meridian position then being able to be compared to a radial height.
The process for manufacturing the non-vulcanised reinforcing ply necessary to obtain the ply according to the invention, as a semi-finished product, consists in firstly manufacturing an intermediate product referred to as "one-face calendered ply", obtained by individually coating a plurality of reinforcement elements with a rubber mix by means of an extruder having a plurality of spinnerets, followed by arranging, using a suitable means, said coated elements in parallel lines, maintaining a defined spacing between two adjacent elements, one of the faces of the assembly of coated elements which are obtained being provided with a first non-vulcanised calendering layer also referred to as a supporting layer, by placing said calendering layer in contact with said assembly.
The contacting of said calendering layer with the assembly of the coated reinforcement elements may be effected either by simply laying the assembly on the calendering layer or by simply laying the calendering layer on the assembly of reinforcement elements, but preferably in both cases with application of slight pressure on one or both of the components, namely the assembly of elements and the calendering layer.
The non-vulcanised "one-face calendered ply" may be used with reinforcement elements coated individually in a rubber mix which is either non-vulcanised or pre-vulcanised. The process relating to the latter possibility comprises an additional step consisting in pre-vulcanising the coating mix at a given temperature by means of a suitable heating means.

The "one-face calendered ply", which is obtained continuously, may be wound up on itself, as is known per se, by means of a backing layer, either of fabric or of polyethylene, for example, acting as an anti-adhesion means, to form rolls of ply. Said rolls serve to feed a table for preparing the plies according to whether they are carcass plies or crown plies. As is known per se, the preparation of a carcass ply requires the reinforcement elements to be cut perpendicular to their common direction, so as to obtain the desired meridian length, whereas the preparation of a crown ply requires the reinforcement elements to be cut at a certain angle and for the portions of ply obtained to be butt-jointed to result in the desired circumferential length of the crown ply.
The manufacture of the reinforcing ply intended to be used in the tyre is completed and terminated by the addition, to the second face of the "one-face calendered ply" of coated, cut reinforcement elements, of the second calendering layer, said second layer not having constant composition and properties. Said addition may be effected in several ways:
either by contacting the "one-face calendered ply", after cutting, with the second calendering layer of composition and properties which are variable according to the meridian position, which layer has been prepared beforehand, for example, on an apparatus independent of the cores or drums for building and/or finishing the non-vulcanised carcass reinforcement and/or tyre blanks (for example, a ply preparation table), said contacting possibly being effected either by laying the "one-face calendered ply" on the second calendering layer, or by laying said second calendering layer on the appropriate face, on which face are visible

the coated reinforcement elements of the "one-face calendered ply", said second layer possibly being in the form of bands of mixes of composition and properties which differ from one band to the axially adjacent band, or in the form of a single layer of mix in which the transition from one band composition to another band composition takes place gradually, and/or continuously;
or preferably by contacting the "one-face calendered ply", after cutting, with the second calendering layer of composition and properties which are variable according to the meridian position, which layer is prepared on the apparatus used for building and/or finishing the non-vulcanised carcass reinforcement and/or tyre blanks (cylindrical building drum for the carcass reinforcement blank, finishing drum for the tyre blank in toric form), said contacting possibly being effected either by laying the "one-face calendered ply", on which face the coated reinforcement elements are visible, on the second calendering layer initially arranged on the non-vulcanised blank during manufacture, or by laying the second calendering layer on the "one-face calendered ply" predisposed on the blank during production, said second layer possibly being in the two forms referred to above.
The characteristics of the invention will be better understood with reference to the following description, which refers to the drawings, illustrating in non-limitative manner several examples of embodiment, in which drawings:
* Figure 1 is a diagram, viewed in meridian section, of a tyre comprising crown plies and a carcass ply

which are in accordance with one variant of the invention;
* Figure 2 is a diagram of a section along A-A, while
* Figure 3 is a diagram of a section along B-B,
* , Figure 4 is a diagram, viewed in meridian section,
of a crown reinforcement composed of two plies,
* Figure 5 is a diagram of the different stages of
manufacture of a "one-face calendered ply".
The tyre shown in Figure 1 is a tyre of the "heavy vehicle" type, of small dimensions 9.00/20 X. It is formed of a radial carcass reinforcement, formed of a single ply (1) of reinforcement elements, in this case inextensible metal cables, which is anchored within each bead to an annular bead reinforcement element, in this case a bead wire (2), to form an upturn (10). Said carcass reinforcement is surmounted radially by a crown reinforcement (3), composed firstly of two working crown plies (31, 32), formed of inextensible metal cables which are parallel to each other within each ply and are crossed from one ply (31) to the next (32), forming angles of between 10° and 45° with the circumferential direction, and in the case described equal to 26° and 18° respectively, and secondly, radially to the outside, of a ply of elastic metal cables which are oriented relative to the circumferential direction at the same angle as the angle of the cables of the radially outermost working crown ply (32) . The crown reinforcement (3) is radially joined to the carcass reinforcement (1) by a layer (8) of rubber mix which is of constant thickness in the central part, and of increasing thickness

towards the edges of the crown reinforcement (3). Said crown reinforcement (3) is radially surmounted by a tread (9), which is joined on either side of the equatorial plane to a sidewall mix (7) covering, within the sidewall of the tyre, the carcass reinforcement (1) and providing the join firstly with the mixes (40, 41, 42) reinforcing the bead and, secondly, with the mix (11) protecting said bead and providing the contact with the service rim. An inner coating layer (5) of the tyre cavity and different rubber reinforcements between said layer and the carcass reinforcement complete the tyre.
The carcass reinforcement ply (1), in the example described, is formed of inextensible metal cables of steel which are coated in a rubber mix B, the composition of which is such that said mix, in the vulcanised state, adheres perfectly to the brass-coated layer covering the steel of the reinforcement cables. Said cables coated with the mix B are calendered, over the entire meridian length of the outer side of the carcass ply (1), including the carcass ply upturns, by a layer of rubber mix A, the first calendering layer or supporting layer, because this is the layer on or beneath which the carcass ply cables are laid during the manufacture of the "one-face calendered ply". As for the inner calendering layer of the ply (1), which is the second calendering layer C, it is formed of a plurality of circumferential bands or layers of rubber mixes of composition and qualities which differ from one band to the adjacent band, the composition and the properties of a band being selected according to the meridian position of said band on the meridian length of the carcass: from the point T of the bead wire (2) radially closest to the axis of rotation to the point S, point of intersection S between the meridian profile of the carcass ply (1) and the line

perpendicular to said profile lowered by the end of the upturn (10) of the ply (1), the zone TS being referred to as "bead zone", the layer C is formed of a first band C, of rubber mix. From said point T to the point R representing the end of the upturn (10) of the carcass ply (1), the zone TR being referred to as the "upturn zone", the layer C is formed of a second band C2 of rubber mix (Figure 2 shows the different layers in the bead zone of the tyre). Between the point S and a point of intersection V of the centre axis of the meridian profile of the carcass ply (1) with a straight line parallel to the equatorial plane and distant from said plane by a quantity which may be between 3 0% and 45% of the axial width of the tread (9), in the case described equal to 35% of said tread width, the zone SV being referred to as the "sidewall and shoulder zone", the layer C is formed of a third band C3 of rubber mix. Between the point V and the equatorial plane XX" forming the so-called crown zone, the fourth band C4 of mix forms the layer C.
In the example illustrated in Figures 1 to 3, the layers or bands A, B, C1, C2 and C4 are formed of one and the same rubber mix which, in the vulcanised state, has a secant modulus of elasticity in tension, measured at a relative elongation e of 0.1 (the modulus thus defined is determined in accordance with Standard AFN0R-NF-T46-002 under normal conditions of temperature and humidity in accordance with Standard AFNOR-NF-T40-101, and will be referred to more simply as "modulus" in the rest of the description), which lies between 6 MPa and 12 MPa, whereas the mix of the calendering layer C3 of the part of the carcass ply (1) in the sidewall and shoulder zone is formed of a rubber mix, the modulus of which of the same name and measured under the same conditions is substantially lower, since it is between 3.5 MPa and 5 MPa. The first mix above,

in the non-vulcanised state, has a relatively high Mooney viscosity of between 60 MU and 90 MU, whereas the mix of the layer C3 has a lower viscosity of the same name since it is between 55 MU and 75 MU (the Mooney viscosity being measured in accordance with Standard AFNOR-NF-T4 3-005).
For another dimension of tyre, and according to the endurance damage encountered on such a dimension, the coating layer B will be produced with a mix of very high modulus of between 27 MPa and 45 MPa, and of very high Mooney viscosity of between 70 MU and 100 MU, whereas the supporting layer A will be formed of a mix of lower modulus than the previous one, but one which is still high, since it is between 10 MPa and 15 MPa, and having a high Mooney viscosity which itself is high and lies between 60 MU and 90 MU. The layer C, will be formed of the same mix as the layer A; on the other hand, the layer C2 will be a band of a mix having a modulus which is low, since it lies between 3.5 MPa and 5 MPa, and having a lower Mooney viscosity of between 55 MU and 75 MU, which mix will also be that of the band C3, whereas the layer C4 will be produced with a mix of intermediate modulus, of between 6 MPa and 12 MPa, and of a viscosity of between 60 MU and 90 MU.
Another beneficial solution consists in selecting as rubber mix for the supporting layer A a mix of low elasticity modulus in the vulcanised state, and using said supporting layer as internal liner of the carcass ply (1), the layers C"1, C"3 and C u then forming the outer calendering layer C of the carcass ply (1). The mix of layer B will be identical to that of the previous example, the mix of layer A will be the mix forming the layer C2 of the previous example with a modulus of between 3.5 MPa and 5 MPa, and a viscosity of between 55 MU and 75 MU. From a point U on the

carcass ply upturn which is located radially substantially at mid-height of said upturn (10) to the point S previously described, passing beneath the bead wire (2), the band C"1 is formed of a mix of high elasticity modulus of between 10 MPa and 15 MPa, and of high viscosity of between 60 MU and 90 MU, whereas from said point U to the point R of the end of the upturn (10) , the band C"2 will be formed of the same mix as that forming the supporting layer A. The same applies for" the layer C"3 from the point S to the point V, whereas the layer Cu will be formed of the same mix as that forming the layer C4 of the previous example.
It will not constitute straying from the scope of the invention if the layer C, be it the inner or outer calendering layer, is obtained by winding a strip of rubber mix, the composition and the properties of which vary continuously, and/or the passage or transition from one composition of mix in one zone of the carcass ply to the composition of the mix in an adjacent zone is effected gradually (for example passing from the mix forming the layer C3 to the mix forming the layer C4) : the strip for forming the layer C may be obtained, as is Known per se, by kneading and/or mixing on a crusher-mixer one or two quantities of rubber granules (in the example selected, granules of the two mixes forming the layers C3 and C4), the crusher-mixer being fed from a plurality of hoppers each containing a rubber mix of given composition and properties in the form of granules, and the desired quantities being obtained by opening feed chutes, this opening being governed by feed control gates, which makes it possible to obtain a zone of transition between the layers C3 and C4 in which the mix forming C3 gradually changes composition to become the mix forming C4.

Figure 4 shows a working crown reinforcement (3) formed of two plies (31) and (32). The working ply (31) radially closest to the axis of rotation is formed of a plurality of metal cables of steel which are coated individually in a rubber mix B1 which, in the example described, has a very high modulus of extension since it is between 15 MPa and 3 0 MPa, and a Mooney viscosity which is likewise high, of between 65 MU and 95 MU. Radially to the inside, there is the first calendering layer or supporting layer A1, which is formed of a single rubber mix of composition and properties which are identical to the composition and properties of the coating mix B1. Radially to the outside, there is the second calendering layer D formed of a plurality of zones of mixes of different composition and properties:
a central zone D1, of axial width 1 of between 70% and 90% of the axial width Ls common to the two working plies (31) and (32), is formed of a mix of high modulus of between 15 MPa and 3 0 MPa, and of a viscosity of between 65 MU and 95 MU, which mix is therefore identical to the mixes forming the supporting layer A1 and the coating B1 of the cables;
of two lateral bands D2, in the case described of identical width, formed of a rubber mix of a modulus which is relatively low since it is between 3 MPa and 9 MPa, and of a Mooney viscosity of between 50 MU and 85 MU.
As for the working crown ply (32) radially farther from the axis of rotation than the ply (31), and of axial width less than said ply (31), it is of identical constitution to that of the ply (31), but the supporting layer A1 is then radially located to the outside of the ply and the three zones D1 and D2 of the

layer D are radially to the inside of said layer D, such that said three zones of the ply (32) are opposite the three zones of the first ply (31), in particular the lateral zones D2 of mix of low elasticity modulus, which makes it possible substantially to reduce the thickness of the rubber wedge (12) arranged between the two ply edges and to lay it in the form of flat bands during building.
The manufacture of the tyre according to the invention requires several preliminary stages before the vulcanisation of said tyre, and in particular the building or manufacture of said "one-face calendered ply". Figure 5 shows a set of reels (100) on which are wound the metal cable intended to be used in the ply to be built. A plurality of cables are sent to an extruder (200), the head of which has a plurality of spinnerets, suitable for coating said cables with the layer (B, B1) of coating mix to a predetermined thickness. Said coated cables are then sent to a tool, in this case a fluted roller (210), which makes it possible to separate each cable from the axially adjacent cable by the desired distance or pitch, and then to a calender (300) having two rollers (310) and (320). A quantity of rubber mix which is to form the supporting layer (A, A1) of the "one-face calendered ply", initially preheated to a temperature making it possible to soften said mix without, however, vulcanising or pre-vulcanising it, is introduced between the two rollers (310) and (320). The passage between the two rollers results in a flat band of mix being obtained, on which the coated cables will make contact with the radially upper part of the upper roller (320). An auxiliary roller (330), referred to as press roller, makes it possible to apply a given pressure to the cables if necessary, this pressure being automatically controlled according to the desired

depth of embedding of the cables in the flat band A. A roller (340) correctly lays an anti-adhesion backing strip, generally of polyethylene, either on the face on which the coated cables are visible, or on the opposite face, so as to be able to wind, as known per se, the "one-face calendered ply" on a winding roller (350), intended to supply the cutters and the ply preparation tables, the reinforcement elements being in the direction of the length of the ply.
As known per ser the "one-face calendered ply", depending on whether a web width for a carcass ply or a web width for a crown ply is being prepared, is cut either perpendicularly to the common direction of the reinforcement elements, or at a certain angle a relative to said common direction of the reinforcement elements; in the finished tyre, this angle a will be the angle of the elements relative to the circum¬ferential direction of said tyre. The web widths thus obtained are then assembled, butt-jointed, either end-to-end for metallic reinforcement elements, or with one end overlapping the other for textile reinforcement elements. In the case of end-to-end butt-jointing, this can be effected by applying a small flat layer of so-called connecting rubber, laid on the join or placed on one of the edges, then passing beneath the other edge.
The web widths thus assembled form the "one-face calendered ply" ready for use, for example, on the means for manufacturing the partial non-vulcanised blank of the tyre. The carcass ply is completed, for example, by laying the "one-face calendered ply" on the different layers of rubber mixes and different bead reinforcement plies pre-arranged on the cylindrical building drum for the cylindrical carcass blank, such that the supporting layer A is arranged radially to the

inside. On the visible reinforcement elements of the "one-face calendered ply" there are then laid the different [word missing?] or circumferential layers C1, C2, C3, etc. which are necessary to form the outer calendering layer C, said layers being, in the non-vulcanised state, of thicknesses selected to obtain the desired thicknesses in the vulcanised state, taking into account the shaping ratio of the carcass blank transforming said cylindrical blank into a toric carcass reinforcement blank. Since the carcass ply is finished on the cylindrical building drum, the next stages of said building are the usual steps which are known per se: laying of the anchoring bead wires for the carcass ply, laying the different rubber bead fillers, edging rubbers or others, turning up the edges of.the carcass ply around the bead wires and fillers, etc.
The production of a complete crown ply (31) is also finished in the same manner, that is to say, on a building drum for a non-vulcanised tyre blank: after laying, on a non-vulcanised, toric carcass reinforce¬ment blank, the different layers (8) of rubber mixes radially separating the carcass reinforcement (l) from the crown reinforcement (3) there is laid a non-vulcanised "one-face calendered ply", formed of reinforcement elements coated individually in a rubber mix B1, having a given composition and properties, said reinforcement elements arranged parallel to each other being covered on one face by a first rubber layer A1 or supporting layer, of constant composition and properties, said "one-face calendered ply" being placed in contact with a second calendering layer D of composition and properties which are variable according to the axial width of the crown ply (31) in the tyre. As for the manufacture of a working crown reinforcement (3) with two plies (31) and (32), there can be laid on

the layers (8) a first "one-face calendered ply", the supporting layer A1 of said ply being radially to the inside, then, on the visible reinforcement elements of said first "one-face calendered ply" there are laid the different layers of rubber mix D1 and D2 forming the second calendering layer of said first crown ply (31), radially closest to the carcass reinforcement. The second crown ply (32) is manufactured identically, but starting with the laying of the layers D1 and D2, which are then covered radially with a second "one-face calendered ply", presented such that the visible reinforcement elements of said second ply are radially to the inside of said ply.
The finishing and vulcanisation of the toric tyre blank are then performed in the conventional, known manner.

We CLAIM:
1. A tyre having at least one reinforcing ply (1, 31, 32) formed of
reinforcement elements embedded in vulcanised rubber,
characterised the reinforcement elements for said ply are individually
coated in a rubber mix (B, B1), referred to as "coating mix", having a
given composition and physical properties, said reinforcement
elements arranged parallel to each other being covered on one face
by a first rubber layer (A, A1), referred to as "first calendering layer",
of constant composition and properties, whereas said elements are
covered on the opposite face by a second rubber calendering layer (C,
D) , of composition and properties which are variable according to
the meridian position on the ply within the tyre.
2. A tyre as claimed in claim 1, wherein the composition and properties of the first layer (A, A1) are identical to the composition and properties of the coating mix (B, Bi) of the reinforcement elements of the ply.
3. A tyre as claimed in claim 2, wherein the reinforcing ply is a carcass reinforcement ply (1)
4. A tyre as claimed in claim 3, wherein the carcass reinforcement ply (1), in its main part on its outer face and in its upturned part on its axially inner face, is calendered with the first layer A of constant composition and properties, whereas the opposite faces are covered

with the second calendering layer C of composition and properties which are variable according to the meridian length of the ply (1) within the tyre.
5. A tyre as claimed in claim 4, wherein the coating mix B has the same composition and properties as those of the mix of the first calendering layer A, the secant modulus of elasticity in tension of said mix in the vulcanised state, measured at a relative elongation of 0.1, being between 6 and 12 MPa, whereas the Mooney viscosity of said mix in the non-vulcanised state is between 60 MU and 90 MU.
6. A tyre as claimed in claim 4, wherein the second layer C is formed:
* of a first band Ci of rubber mix, extending from the point T of the bead wire (2) radially closest to the axis of rotation to the point of intersection S between the centre axis of the meridian profile of the carcass ply (1) and the line perpendicular to said profile lowered by the end of the upturn (10) of the ply (1), the zone TS being referred to as the "bead zone",
* of a second band C2 of rubber mix, extending from said point T to the point R representing the end of the upturn (10) of the carcass ply (1), the zone TR being referred to as the "upturn zone",
* of a third band C3 of rubber mix, between the point S and a point of intersection V of the centre axis of the meridian profile of the carcass ply (1) with a straight line parallel to the equatorial plane and distant from said plane by an amount which may be between 30% and 45% of the axial width of the

tread (9), the zone SV being referred to as the "sidewall and shoulder zone",
of a fourth band C4 of rubber mix, between the point V and the equatorial plane XX", forming what is called the "crown zone", the bands C1, C2 and C4 being formed of the same mix, the elasticity modulus of which is between [number missing] MPa and 12 MPa and the Mooney viscosity of which is between 60 MU and 90 MU, whereas the band C3 is formed of a mix, the elasticity modulus of which is between 3.5 MPa and 5 MPa and the Mooney viscosity of which is between 55 MU and 75 MU.
7. A tyre as claimed in claim 2, wherein the reinforcing ply is a ply (31, 32) of the crown reinforcement (3), formed of reinforcement elements which are parallel to each other within said ply and form an acute angle with the circumferential direction of the tyre, the meridian position being judged on the axial width of said ply (31, 32).
8. A tyre as claimed in claim 7, wherein it comprises a crown
reinforcement (3) formed of at least two working crown plies (31,
32), the ply (31)
radially closest to the carcass reinforcement being calendered on its radially inner face with a first calendering layer Ai of constant composition and properties, and on its radially outer face with a second calendering layer D of composition and properties which are variable according to the axial width of said ply (31), whereas the ply (32) radially to the outside of the ply (31) is calendered on its radially outer face with the first calendering layer Ai of constant composition and properties and on its radially inner

face with the second calendering layer D of composition and properties which are variable according to the axial width of said ply (32).
9. A tyre as claimed in claim 8, wherein the rubber mix forming
firstly the first calendering layer A1 and secondly the coating mix Bi
of the reinforcement elements of the crown ply (31, 32) has, in the
non-vulcanised state, a Mooney viscosity of between 65 MU and 95
MU, and in the vulcanised state a secant modulus of elasticity in
tension, measured at 10% relative elongation, of between 15 MPa
and 30 MPa.
10. A tyre as claimed in claim 9, wherein the second calendering layers D are at least formed of three zones, a central zone D1, formed of a rubber mix having in the vulcanised state a high modulus of elasticity in tension of between 15 MPa and 30 MPa, and in the non-vulcanised state a Mooney viscosity of between 65 MU and 95 MU, and two lateral zones D2 formed of a rubber mix having in the vulcanised state a low modulus of elasticity in tension of between 3 MPa and 9 MPa, and in the non-vulcanised state a Mooney viscosity of between 50 and 85 MU.
11. A tyre as claimed in claim 1, wherein the composition and properties of the first layer (A, A1) are different from the composition and properties of the coating mix (B, B1) of the reinforcement elements of the ply.
12. A tyre as claimed in claim 11, wherein the reinforcing ply is a

carcass reinforcement ply (1).
13. A tyre as claimed in claim 12, wherein the carcass reinforcement ply (1), in its main part on its outer face and in its upturned part on its axially inner face, is calendered with the first layer A of constant composition and properties, whereas the opposite faces are covered with the second calendering layer C of composition and properties which are variable according to the meridian length of the ply (1) within the tyre.
14. A tyre as claimed in claim 13, wherein the coating mix B in the vulcanised state has an elasticity modulus of between 27 MPa and 45 MPa and in the non-vulcanised state a Mooney viscosity of between 70 MU and 100 MU, whereas the elasticity modulus in the vulcanised state of the mix of the first calendering layer A is between 10 MPa and 15 MPa and has a Mooney viscosity in the non-vulcanised state of between 60 MU and 90 MU.
15. A tyre as claimed in claim 13, wherein the second layer C is
formed:
* of a first band C1 of rubber mix, extending from the point T of the bead wire (2) radially closest to the axis of rotation, to the point of intersection S between the centre axis of the meridian profile of the carcass ply (1) and the line perpendicular to said profile lowered by the end of the upturn (10) of the ply (1), the zone TS being referred to as the "bead zone",
* of a second band C2 of rubber mix, extending from said point T to the point R representing the end of the Upturn (10) of the

carcass ply (1), the zone TR being referred to as the "upturn
it
zone"
of a third band C3 of rubber mix, between the point S and a point of intersection V of the centre axis of the meridian profile of the carcass ply (1) with a straight line parallel to the equatorial plane and distant from said plane by an amount which may be between 30% and 45% of the axial width of the tread (9), the zone SV being referred to as the "sidewall and shoulder zone",
of a fourth band C4 of rubber mix, between the point V and the equatorial plane XX", forming what is called the "crown zone", the bands C2 and C3 being formed of the same mix, the elasticity modulus of which is between 3.5 MPa and 5 MPa and the Mooney viscosity of which is between 55 MU and 75 MU, whereas the band C1 is formed of a mix, the elasticity modulus of which is between 10 MPa and 15 MPa and the Mooney viscosity of which is between 60 MU and 90 MU, and that the band C4 is formed of a mix, the elasticity modulus of which is between 6 MPa and 12 MPa and the Mooney viscosity of which is between 60 MU and 90 MU.
16. A tyre as claimed in claim 12, wherein the carcass reinforcement ply (1) in its main part on its inner face and in its upturned part on its axially outer face, is calendered with the first layer A of constant composition and properties, whereas the opposite faces are covered with the second calendaring layer C of composition and properties which are variable according to the meridian length of the ply (1) within the tyre.

17. A tyre as claimed in claim 16, wherein the coating mix B in the vulcanised state has an elasticity modulus of between 27 MPa and 45 MPa and in the non-vulcanised state a Mooney viscosity of between 70 MU and 100 MU, whereas the elasticity modulus in the vulcanised state of the mix of the first calendering layer A is between 3.5 MPa and 5 MPa and a Mooney viscosity in the non-vulcanised state of between 55 MU and 75 MU.
18. A tyre as claimed in claim 16, wherein the second layer C is formed:
* of a first band C1 of rubber mix, extending from the point U of the upturn (10) of the carcass ply (1), located substantially at mid-height of said upturn (10), to the point of intersection S between the centre axis of the meridian profile of the carcass ply (1) and the line perpendicular to said profile lowered by the end of the upturn (10) of the ply (1),
* of a second band C2 of rubber mix, extending from said point U to the point R representing the end of the upturn (10) of the carcass ply (1),
* of a third band C3 of rubber mix, between the point S and a point of intersection V of the centre axis of the meridian profile of the carcass ply (1) with a straight line parallel to the equatorial plane and distant from said plane by an amount which nay be between 30% and 45% of the axial width of the tread (9), the zone SV being referred to as the "sidewall and shoulder zone",

of a fourth band C4 of rubber mix, between the point V and the equatorial plane XX", forming what is called the "crown zone", the bands C"2 and C"3 being formed of the same mix, the elasticity modulus of which is between 3.5 MPa and 5 MPa and the Mooney viscosity of which is between 55 MU and 75 MU, whereas the band C 1 is formed of a mix, the elasticity modulus of which is between 10 MPa and 15 MPa and the Mooney viscosity of which is between 60 MU and 90 MU, and that the band C4 is formed of a mix, the elasticity modulus of which is between 6 MPa and 12 MPa and the Mooney viscosity of which is between 60 MU a:nd 90 MU.
19. A tyre as claimed in claim 1, wherein the reinforcing ply is a crown reinforcement ply formed of circumferential elements.
20. A tyre as claimed in claim 1, wherein the reinforcing ply is a bead reinforcement ply.
21. A tyre as claimed in claim 1, wherein the reinforcing ply is a sidewall reinforcement ply.
22. A process for manufacturing a tyre as claimed in claims 3 or 12, consisting, firstly, of building on a drum a non-vulcanised cylindrical carcass reinforcement blank comprising at least one carcass ply (I) , wherein the building of the carcass ply (1) requires,

after the laying on the cylindrical building drum for the cylindrical carcass reinforcement blank of the different layers of rubber mixes and different bead reinforcement plies, the laying of an intermediate product referred to as "one-face calendered ply", which is non-vulcanised and formed of reinforcement elements coated individually in a rubber mix B, referred to as "coating mix", having a given composition and physical properties, said reinforcement elements arranged parallel to one another being covered on one face with a first rubber layer A, referred to as "first calendering layer" or "supporting layer", of constant composition and properties, said "one-face calendered ply" being brought into contact with a second calendering layer C of composition and properties which are variable according to the position on the meridian length of the ply (1) within the tyre.
23. A process as claimed in claim 22, wherein the non-vulcanised "one-face calendered ply" is used with reinforcement elements coated individually in a non-vulcanised rubber mix B.
24. A process as claimed in claim 23, wherein the non-vulcanised "one-face calendered ply" is used with reinforcement elements coated individually in a rubber mix B which is pre-vulcanised at a given temperature using a suitable heating means.
25. A process as claimed in one of claims 22 to 24, wherein the contacting is effected by the laying, on the different layers of rubber mixes and the different bead reinforcement plies covering the
cylindrical building drum for the cylindrical carcass reinforcement blank (1), of the "one-face calendered ply" of coated reinforcement elements, and the laying on the visible coated elements of the "one-face calendered ply" of the second calendering layer C of composition

and properties which are variable according to the meridian length of the ply (1) within the tyre,
26. A process as claimed in one of claims 22 to 24, wherein the
contacting is effected by the laying, on the different layers of rubber
mixes and the different bead reinforcement plies covering the
cylindrical building drum for the cylindrical carcass blank (1), of the
second calendering layer C of composition and properties which are
variable according to the meridian length of the ply (1) within the
tyre and the laying on said second layer of the "one-face calendered
ply" of coated reinforcement elements, said elements being laid on
the second layer C.
27. A process for manufacturing a tyre as claimed in claim 7,
consisting, at a given instant, of arranging on a non-vulcanised toric
carcass reinforcement blank (1) a crown ply (31, 32) of
reinforcement elements which are parallel to each other within the
ply and form an acute angle with the circumferential direction,
wherein the building of the crown ply (31, 32) requires, after the
laying on the toric carcass blank of the different layers (8) of rubber
mixes radially separating the carcass reinforcement (1) from the
crown reinforcement (3), the laying of an intermediate ply referred to
as "one-face calendered ply", which is non-vulcanised and formed of
reinforcement elements coated individually in a rubber mix Bi,
referred to as coating mix, having a given composition and physical
properties said reinforcement elements arranged parallel to one
another being covered on one face with a first rubber layer Ai or
supporting layer, of constant composition and properties, said "one-
face calendered ply" being brought into contact with a second
calendering layer D of composition and properties which are

variable according to the axial width of the crown ply (31, 32) within the tyre. .
28. A manufacturing process as claimed in claim 27 for a tyre
having a crown reinforcement (3) formed of two plies (31, 32) as claimed in claim 8, wherein there is laid:
a) on a non-vulcanised, toric carcass reinforcement blank (1), a "one-face calendered ply", the supporting layer A1 of said ply being radially to the inside,
b) then, on the visible reinforcement elements of the "one-face calendered ply", the second rubber calendering layer D of the radially inner crown ply (31), which layer is of composition and properties which are variable according to the axial width of the ply within the tyre, the layers A1 and D forming the crown ply (31) closest to the carcass reinforcement (1) with the coated elements,
c) then the second rubber calendering layer (D) of the crown ply (32) radially adjacent to the inner ply (31) , which layer is of composition and properties which are variable according to the axial width of the ply (32) within the tyre,
d) then, radially to the outside, the "one-face calendered ply", presented such that the visible reinforcement elements are radially to the inside.

29. A process for manufacturing a non-vulcanised "one-face calendered ply" formed of reinforcement elements coated individually in a pre-vulcanised rubber mix (B, B1) as claimed in any of the preceding claims, wherein the reinforcement elements coming from winding reels (100) are sent to an extruder (200) the head of which comprises a plurality of spinnerets, suitable for coating said elements with the layer (B, B1) of coating mix to a predetermined thickness, then are sent to a means (210) making it possible to separate each cable from the axially adjacent cable by the desired pitch, to arrive at a calender (300) with two rollers (310) and (320), which makes it possible to obtain a flat band of supporting calendering mix (A, A1) , on which the coated elements will make contact with the radially upper part of the upper roller (310) , an auxiliary means (330), referred to as "presser means", making it possible to apply a pressure to the coated elements, which pressure is automatically controlled according to the desired depth of embedding of the elements within the supporting layer (A, A1) and a roller (340) laying an anti-adhesion backing strip on one of the faces of the ply coming from the calender (300), so as to be able to wind said ply on a winding drum (350) , and then to make the cuts at the desired angle, to form web widths which can be butt-jointed and to obtain the "one-face calendered ply".
Dated this 7th day of August, 2001.
(RANJNA MEHTA DUTT)
OF REMFRY & SAGAR
ATTORNEY FOR THE APPLICANTS

Documents:

abstract1.jpg

in-pct-2001-00950-mum-cancelled pages(7-8-2001).pdf

in-pct-2001-00950-mum-claims(granted)-(15-6-2005).pdf

IN-PCT-2001-00950-MUM-CORRESPONDENCE(25-9-2012).pdf

in-pct-2001-00950-mum-correspondence(6-6-2005).pdf

in-pct-2001-00950-mum-correspondence(ipo)-(8-2-2007).pdf

in-pct-2001-00950-mum-drawing(15-6-2005).pdf

IN-PCT-2001-00950-MUM-FORM 16(13-8-2012).pdf

in-pct-2001-00950-mum-form 19(19-4-2004).pdf

in-pct-2001-00950-mum-form 1a(15-6-2005).pdf

in-pct-2001-00950-mum-form 1a(7-8-2001).pdf

in-pct-2001-00950-mum-form 2(granted)-(15-6-2005).pdf

in-pct-2001-00950-mum-form 3(12-4-2004).pdf

in-pct-2001-00950-mum-form 3(15-6-2005).pdf

in-pct-2001-00950-mum-form 3(7-8-2001).pdf

in-pct-2001-00950-mum-form 5(15-6-2005).pdf

in-pct-2001-00950-mum-form 5(7-8-2001).pdf

in-pct-2001-00950-mum-form-pct-ipea-409(7-8-2001).pdf

in-pct-2001-00950-mum-form-pct-isa-210(7-8-2001).pdf

in-pct-2001-00950-mum-petition under rule 137(15-6-2005).pdf

in-pct-2001-00950-mum-petition under rule 138(15-6-2005).pdf

in-pct-2001-00950-mum-power of authorty(15-6-2005).pdf

in-pct-2001-00950-mum-power of authorty(7-8-2001).pdf

in-pct-2001-01109-mum-form 2(granted)-(22-3-2005).doc

in-pct-2001-01109-mum-we claim(granted)-(22-3-2005).doc

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Patent Number

208370

Indian Patent Application Number

IN/PCT/2001/00950/MUM

PG Journal Number

35/2007

Publication Date

31-Aug-2007

Grant Date

25-Jul-2007

Date of Filing

07-Aug-2001

Name of Patentee

SOCIETE DE TECHNOLOGIE MICHELIN

Applicant Address

23, RUE BRESCHET, F-63000 CLERMONT-FERRAND, FRANCE.

Inventors:

#	Inventor's Name	Inventor's Address
1	JEAN BILLIERES	7, RUE DU PARC DE MONTJUZET, F-63100 CLERMONT-FERRAND, FRANCE.

PCT International Classification Number

B60C 9/18, B60C 9/00, B29D 30/38

PCT International Application Number

PCT/EP00/001189

PCT International Filing date

2000-02-14

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	99 / 02145	1999-02-19	France