Title of Invention	BRAKING BODY AND YARN FEEDER
Abstract	A braking body B of a yarn brake Y generally being a frustocone jacket 1 made of at least radially elastic homogenous thermoplastic polymeric foil material B, the inner surface 1 of which is defining a circumferentially continuous yarn braking zone 6 consists of a high-performance thermoplastic polymer such as polyketone. A yarn feeder comprising a stationary storage body 13 and a yarn brake Y including a braking body B being resiliently pressed axially against a storage body 13 as a frustoconical braking body consisting of a high-performance thermoplastic polymer such as polyketone. (Fig.1)

Title of Invention

BRAKING BODY AND YARN FEEDER

Abstract

A braking body B of a yarn brake Y generally being a frustocone jacket 1 made of at least radially elastic homogenous thermoplastic polymeric foil material B, the inner surface 1 of which is defining a circumferentially continuous yarn braking zone 6 consists of a high-performance thermoplastic polymer such as polyketone. A yarn feeder comprising a stationary storage body 13 and a yarn brake Y including a braking body B being resiliently pressed axially against a storage body 13 as a frustoconical braking body consisting of a high-performance thermoplastic polymer such as polyketone. (Fig.1)

Full Text	The invention relates to a braking body according to Vne preamble part of claim 1 and to a yarn feeder according to the preamble of claim 11. WO 2006/032376 A discloses a frustoconical braking body having a wall thickness between about 0.2 mm and 1.0 mm. The braking body consists of a thermoplastic foil material of engineering plastic andi is made by thermo-vacuum shaping. The plastic material used is either polyethelyne, polyvinylchtorkle, or polyterephthalate (PE, PVC, PET). EP 1 164 103 A discloses a braking body substrate and a weft yam feeder being equipped with a yarn brake including the frustoconical braking body substrate. The braking body substrate is made from calendered engineering thennoplastlc materials, thermoplastic resins or themiosetting plastic material and consists of an outer frustocontoal carrier body and an axially shorter frustoconical braking body inserted into the interior of the frustocontoal carrier body. One example of the engineering plastic material is epoxy resin. In the yarn feeder the braking body is axially resUiently pressed via the carrier body against the front end of the stationary storage body such that the braking zone at the inner surface of the frustoconical braking body contacts the rounded withdrawal rim. The large diameter end of the braking body protrudes outwardly in relation to the storage surface of the storage body. The small diameter end of the braking body substrate is situated in front of the front end of the storage body and is suspended in a radial star-like arrangenrtent of tenston springs the outer ends of which are anchored in a holder ring. The holder ring is snapped into a cannier ring whkih is axially adjustable in a housing bracket of the yarn feeder in order to set the contact pressure between the braking body and the storage body withdrawal rim. DE 10 2004 051 372 A disclbses a braking body for a yam brake. The braking body Is a true regular frustocone jacket made from a mesh fabrk: containing weft yarns and warp yarns of polyester. The braking body is made by deep drawing under elevated tempera¬tures. EP 1 243 542 A discloses a frustoconical braking body of a yarn brake of a yam feeder. The braking body has a discontinuous braking zone defined by a circumferential row of in¬clined slits in the fru8toconk:al jacket. The braking body is made from engineering themio- plastic polymeric material or from engineering thermosetting polymeric material or from en¬gineering polymer reinforced with carbon fibre. EP 0534263 A1 discloses a self-adjusting yarn braking device for weft-feeder units, the braking body of which is a truncated cone supported by an elastk: member coaxially and frontally with respect to a drum of the weft feeder unit. The braking body is constituted by a fabric or by a laminate of high-strength synthetic fibers, typteally carbon fibers or ffi)ers of "Kevlar". Alternatively, the braking body may be shaped from steel plate material or firom a synthetic material covered with a metallic layer in at least the braking zone. The generally frustoconical braking body of a yarn brake is a wear part which'is to be ex¬changed frequently because the braking zone contacting the withdrawal rim of the storage body wears out rapidly. The yam is withdrawn overhead of the storage body between the withdrawal rim and the braking zone. During withdrawal the yam is orbiting like the hand of a clock, causing pennanent relative movements between the radially elastic braking body and the in most cases metallk: withdrawal rim. As the yam kx»iiy lifts the braking zone from the withdrawal rim the braking body permanently is deformed and is breathhg in rela¬tion to the withdrawal rim. Abrasion caused by friction of the orbiting withdrawn yam, abra¬sion caused by friction of the withdrawal rim and heat generated by the friction causes wear in the braking zone. The wear in the braking zone does not devetop uniformly but creates successive spots which are worn out more than the interspaces between the spots. A typi¬cal appearance of the worn-out braking zone of the braking body has the image of a pearl necklace The braking body at this point has to be replaced. The wear results in undesira¬bly short sen/ice life of the braking body and a relatively high frequency of braking body ex¬changes with a lot of shut-down time of the yarn feeder because an exchange of the brak¬ing body requires switching off the yarn feeder and the weaving machine or the knitting ma¬chine. The engineering plastic materials of known braking bodies, moreover, performed such that in operation of the yarn brake the yam tension resulting from the braking effect of the yarn brake shows significant irregularities even during each single orbiting revolutton of the withdrawn yarn albng the braking zone of the braking body. The irregularities result from the co-action betWeen the yam and the surface of the plastk: material of the braking body, and, furthermore, from Increasing wear. Irregularities of the yam tension may be the reason for yarn breakages and negative interference on the insertion process in the weaving machine or the knitting machine. Both drawbacks, the irregular yarn tension and the rapkl progress of wear in the braking zone are detrimental to the performance of the braking body or the yarn feeder, respectively. It is an object of the invention to create a braking body or a yarn feeder allowing to achieve a uniform yarn tension during each revolution of the withdrawn yarn along the braking zone and an extended service life of the braking body in order to lower the frequency of shut¬downs of the yarn feeder to exchange the braking body. This object is achieved by the features of claim 1 and the features of claim 11. Mainly due to excellent resilience against nrechanical loads and heat, and a very smooth and tough surface in th braking zone working with the yarn and the withdrawal rim the high-performance thermoplastk: polyketone material of the braking body results in br extended service life and a superior yarn tension development, compared to engineering firiastk; of known braking bodies. The yarn tension as produced during each revoiutton of the orbiting yarn along the braking zone of the braking body remains very uniform over nearly the full servke life of the braking body. The polyketone for the braking body is selected from the following polyketones group: polyetheretherketone, polyaryletherketone, polyetherketoneke-tone, or a similar polyketone. Polyketones in one family of high-performance themioplastic polynrs which allows to achieve the above mentioned advantages of the braking body. The high-performance themioplastic polyketone used for manufacturing the braking body expe¬diently has a Young's modulus between about 3.0 and 4.0 Gpa and a tensile strength be¬tween about 75 and 110 Mpa. in the yarn feeder equipped with the frustoconical braking body made from a sheet or foil of a high-performance thenrtopiastic polyketone the material choice results in a markedly low¬ered frequency of shutdowns for braking body exchanges and in very few yarn breakages and almost no detrimental interferences with the yam insertkn process. Preferably, the polyketone of the braking body has Young's modulus of about 3.6 Gpa and a tensile strength of about 90 Mpa. In a preferred embodiment the braking body comprises a semi-crystalline or amorphous high-performance thermoplastic polyketone. ,i • Polyketone is a high-performance plastic material obtained from aromatic dehalides and bisphenolate salts by nucleophilic substitution. Among the high-performance thennoplastic polymers like e.g. the family of polyketones used for braking bodies of yarn brakes polyetheretherketone is one which exhibits two glass transition temperatures around 140'C and 270'C, has a melting point of about SSO'C, and is highly resistant to thermal degradation. Polyketones, furthermore, are resistant to l)oth or¬ ganic and aqueous environments and show a high strength to weight ratio, and are available either semi-crystalline or amorphous. , Until now polyketones have been used in bearings, pistons, pumps, compressor valves and cable insulations. Polyketors are compatible with uKf'ahigh vacuum applications. Poly-etherethertcetone also is an advanced bio-compatible materiai used in medical implants, and li ■ ; ii ■ is also used in structures of aerospace craft. Owing to the excellent strength to weight ratio and the high resistancy against thermal deg¬radation, the wall thickness of the polyketone frustocone jacket only needs to anfKunt to be¬tween 0.1 mm and 0.5 mm. The small wall thickness results in a very lightweight braking body showing an excellent performance even in the case of high yarn speeds, or delk:ate yarn qualities, or small diameter storage bodies. The excellent perfonnance of the braking body is achieved already with a homogenous frus¬tocone. However, for certain applications it even may be expedient to use a high-performance thermoplastic polymer like polyketone which contains reinforcing fibre material, even carbon fibres. In an expedient embodiment the uniformity of the yarn tension resulting from the co¬operation between the braking zone of the braking body and the yam may be furtfier im¬proved by providing a circumferentially continuous, outwardly extending integrally formed flange at the large diameter end of the frustoconicai jacket. The flange somewhat stiffens or reinforces the large diameter end region of the braking body, attenuates an undulation tendency there and thus brings about an even more uniform devetopment of the yam ten¬sion during each revolution of the withdrawn yarn akng the braking zone. Moreover, when mounting or exchanging the braking body in nfost cases the braking tody is gripped by hand or with the help of a tool at the large diameter end. Also when removing resits of broken yarn or lint deposits by pressurised air or by using a tool or the fingers, the large diameter end might easily become damaged, as a sharp large diameter end of a true frustocone jacket is prone to scratching or cracking during such manipulations. The flange forms a protection for the vulnerable large diameter end region of the braking body and thus contrib¬utes to a long service life.. In an expedient embodiment the flange extends substantially radially with respect to the frustocone axis. The flange fulfils a further protective function in that it hinders during awk¬ward operation conditions the yarn from moving outwardly around the and behind the large diameter end where it might wrap around protruding components of the yarn feeder. In another expedient embodiment the flange is inversely conical in relation to the conicity of the frustocone jacket. So to speak, the outer edge of the frustocone jacket is bent back¬wards. In a preferred embodintent the inversely conical polyketone flange has a rour(;ted curvature, in an axial section of the braking body, and a smooth transitton into the large aiameter end of the frustocone jacket. During operation of the braking body the polyketone flange damp¬ens a vibration tendency in the large diameter end region of the braking body. The flange may define an angle of about 90" with the outer surface of the frustocone jacket, the gen-eratrice of which, expediently, is a straight line between the small diameter end and the large diameter end. In an expedient embodiment, the braking body is made by thermoshaping a high-performance thermoplastic polyketone foil or sheet, preiferably a flat blank. A preferred process for shaping the braking body is themio-vacuum shaping or deep drawing, preferably under elevated temperatures. in another embodiment, the braking body made from the high-perfomance thermoplastic polykentone is inserted with an outer frustoconical can-ier body. The braking body defines the braking zone and constitutes - so to speak - a brake lining in the carrier body. The braking body may be attached to the inner wall of the carrier body. Embodiments of the invention will be described with reference to the drawings. In the draw¬ings is: Fig. 1 an axial section of a first embodiment of a'braking body, I ■ ■ ;'■ ■ Fig. 2 an axial section of a second and third embodiment of a braldng body, Fig. 3 an axial section of a yam feeder being equipped with a yarn brake fticluding a braking body, e.g. according to Fig. 1, and Fig, 4 an axial sectton of a braking body substrate, A braking body B as shown in Fig. 1 is a yarn braking body intended for use in a yarn brake Y of a yarn feeder F (Fig. 3). The braking body B is a wew part or spare part whteh has to be exchanged when the service life has expired, e.g. due to wear. The braking body B In Fig. 1 is a true frustocone jacket 1 having a small diameter end 3 and a large diameter end 2, a frustocone axis Z and a straight generatrlce. The frustocone jacket 1 has an inner continuous and smooth surface 4 and an outer surface 5. The Inner surface 4 defines a circumferentiaHy continuous braking zone 6 (indicated by a dotted line). The braking body comprises a high-performance thenT\|optastic polyketone selected from the following polyketone group: potyetheretherketone, polyaryletherketone, poiyjtterketoneke-tone (PEEK, PAEK, PEKK). The wall thtekness x amounts to between 0.1 mm and 0.5 mm. The braking body B is made by thermoshaping, preferably thermo-vacuum shaphig or deep drawing a sheet or a foil, most preferably a flat foil or sheet blank. The use of a liank re¬sults in the fact that the finally shaped braking body does not need further treatment like cut¬ting the edges in the small dlanieter end 3 or the large diameter end 2. The inner surface 4 of the frustocone jacket 1 may either have a polished surface quality or may be treated by polishing. The high-performance themnoplastic polymer such as a polyketone may be semi-crystalline or amorphous, and nmy even comprise reinforcing fibre material. The braking body B is elastic at least In radial direction and Is relatively stiff In axial direction along the axis Z. In the embodiment in Fig. 2 a flange 7 (or 7' in dotted lines) may be integrally formed at the large diameter end 2 of the frustocone jacket 1, The flange 7' either extends racUaliy with respect to the axis Z of the frustocone jacket 1, or the flange 7 is inversely conical in relation to the conicity of the frustocone jacket 1 (shown in full lines). When being inversely conteal the flange 7 may be rounded with a radius r as shown, and may have a smooth transition 8 into the large diameter end 2 of the frustocone jacket 1. The yarn feeder F (either a weft yam feeder for a weaving machine or a knitting yarn feeder for a knitting machine) in Fig. 3 includes a yarn brake Y being equipped with the braking body B shown in Fig. 1 or in Fig. 2 (not shown). The yarn feeder F has a housing 9 containing a not shown motor for driving a central shaft 10. The rear part of the shaft 10 is hotbw and communicates with an obliquely outwardly extending winding tube 11. A storage body 13 is rotatably supported on the shaft 10 and is hindered against co-rotation with the shaft 10 by e.g. co-acting penanent magnets ar¬ ranged in the storage body 13 and the housing 9. The storage body 13 defines a substan¬ tially cylindrical storage surface 14 for a not shown yam supply consisting of consecutively wound on yarn windings of a yarn exiting the winding tube 11. The yarn supply te formed by rotating the winding tube 11 in relation to the stationary storage body 13. From the yarn supply on the storage surface 14 the yarn is withdrawn overhead of the storage body 13 and over a rounded or conical withdrawal rim 18 and through a stattonary outlet eyelet 15 sta- tionarily supported in a bracket 12 of the housing 9. Tt\|ie yarn eyelet 15, in this case, is supported in a basket-shaped structure 17 snapped into a hokier 16 mounted in the bracket 12. The holder 16 may be adjusted along bracket 12.. 11 The basket-shaped structure 17, furthermore, holds a ring-shaped bocly 19 in turn hoMing the small diameter end 3 of the braking body B such that the braking body B Is axtally resil-iently pressed against the withdrawal rim 18 with the braking zone 6 contacting the entire circumference of the withdrawal rim 18. The large diameter end 2 of the braking body B protrudes outwardly beyond the withdrawal rim 18. The small diameter end 3 may be in¬serted loosely, or snapped-in into the body 19, or even may be fixed there. During operation of the yarn feeder F the yarn while being withdrawn from the yam supply on the storage surface 14 is pulled through between the braking zone 6 of the braking body B and the withdrawal rim 18 before it runs through the outlet eyelet 15 and further axially to the insertion means (not shown) of the weaving machine or the knitting machine. The braking body B is at least tocally radially deformed by the yam while the withdrawn yarn is orbiting around the withdrawal rim 18. The yarn is braked. The braking effect between the braking zone 6 and the withdrawal rim 18 and the frtetion of the yarn on the braking sur¬face 6 generate a certain yam tension In the running yarn, e.g. depending on the braking body contact pressure backed-up by the hokier 16. Due to the excellent surface quality and i the high resistance against abrasion by mechanical loads and heat of the high-performance thermoplastic polymer material such as polyketone plastic material as used for manufactur¬ing the braking body B, the yarn tension, depending among others on the coefficient of fric¬tion in the braking zone and the coefficient of friction in the withdrawal rim 18, remains broadly constant during each revolution of the yarn along the braking zone 6 and for the en¬tire service life. In order to replace the braking body the holder 16 is moved in the bracket 12 in F. 3 to the right side until the braking body B forms a gap with the withdrawal rim 18. Then either the structure 17 is taken out from the holder 16 or the body 19 is taken out from the structure 17, or the braking body 8 directly is taken out from the ttody 19. Then the braking body B is replaced by another braking body B, before the holder 16 Is moved back Into the original position. In order to vary the braking effect the holder 16 nrtay be moved gradually in Fig. 3 to the left skle or the right skle in order to increase or decrease the axial contact pressure of the braking body B on the withdrawal rim 18. The braking body substrate of Fig. 4 consists of an outer frustoconteal thinrwalted canrier body 20 of frustoconical shape and the braking body 6: The braking body B e.g. made of polyketone is inserted into the can'ier body 20 and maybe attached to the Infer wall of the carrier body 20 between big-diameter and small-diameter ends 21,22. The braking body B has the same conicity as the carrier body 20, and may be axially shorter than or as long as the carrier body 20. The carrier body 20 may consist of a high-performance thermoplastic polymer such as polyketone as well, or of another polymerk: ptastte material, or of sheet metal, or of a plastto impregnated fabric. The polyketone braking body B constitutes a brake lining of the braking body substrate. As indicated, the carrier body 20 may be integrally formed with an end flange 7', similar to the braking body B In Fig. 2. CLAIMS 1 Braking body (B) of a yarn brake (Y) of a yarn feeder (F), the braking body (B) generally being a frustocone Jacket (1) made of at least radially elastic thermoplastic polymeric foil material (P), the inner surface (1) of the braking body (B) defining a circumferentially continuous yarn braking zone (6) characterised in that the braking body (B) comprises a high-performance thermoplastk: polyketone from the folk)wing group of polyketones: polyetheretherketone, polyaretherketone, polyetherketoneketone (PEEK, PAEK. PEKK), and that the polyketone in the braking body (B) has a Young's modulus between about 3.0 GPa and 4.0 GPa and tensile strength between about 75 and 110 MPa. 2. Braking body according to claim 1, characterised In that the braking body (B) comprises a semi-crystalline or amorphous high-performance thermoplastic polyketone. 3. Braking body acicording to claim 1, characterised In that the polyketone in the braking body (B) has a Young's modulus of aboiit 3.6 GPa, and tensile Strength of about 90 MPa. 4. Braking body according to claim 1, characterised in that the wall thtekness (X) of the polyketone frustocone jacket (1) Is substantially constant and amounts to about between 0.1 mm and 0.5 mm. 5. Braking body according to at least one of the preceding claims, characterissd in that the frustocone jacket (1) comprises polyketone and reinforcing fibre material. 6. Braking body according to at toast one of the precedkig claims, characterised in that the braking body (B) has a circumferentially contbiuous, outwardly extending integrally formed flange (7, 7') at the large diameter end (2) of the frustocone jacket 7. Braking body according to claim 6, characterisiRd in that the flange (7') at the large diameter end (2) extends substantially radially ith respect to the frusJloone axis (Z). 8. Braking body according to claim 6, characterised In that the flange (7) is inversely conical in relation to the conicity of the frustocone jacket (1), preferably witti a rounded curvature (r) and a smooth transition (8) in the large diameter end (2), such that the polyketone flange defines a angle (a) of about 90" with the outer surface (5) of the frustocone jacket (1). 9. Braking body according to at least one of the preceding claims, characterised in that the braking body (B) is made by thermoshaping, preferably themno-vacuum shaping or deep drawing, of a foil-blank or of a sheet of polyketone 10. Braking body according to at least one of the preceding claims, characterised in that the braking body (B) is inserted into, and preferably attached to, an outer carrier body (20) being a frustocone jacket, preferably consisting of polyketone or of another polymeric material or of sheet metal or of an impregnated fabric. 11. Yarn feeder (F), in particular weft yam feeder or knitting yarn feeder, comprising a stationary storage body (13) defining a substantially cylindrical storage surfece (14) for a yarn supply, the storage body (13) having a circumferentlally continuous front end withdrawal rim (18) for overhead withdrawal of a yarn from the yarp supply and over the withdrawal rim (18), a yarn brake (Y) including a braking body (B) generally being a frustocone jacket (1) made of at least radial elastic homogenous thermoplastic polymeric foil material (P), the inner surface (1) of the braking body (B) defining a circumferentlally continuous yarn braking zone (6), the braking body (B) being resiliently pressed axially against the storage body (13) such that the braking body braking zone (6) contacts the withdrawal rim (18) from the front SKle, characterised in that the braking body (B) consists of a high-performance thermoplastic polyketone of the following group: polyetheretheritetone, polyaryletherketone, polyetherketoneketone (PEEK, PAEK, PEKK).

Full Text

The invention relates to a braking body according to Vne preamble part of claim 1 and to a yarn feeder according to the preamble of claim 11.
WO 2006/032376 A discloses a frustoconical braking body having a wall thickness between about 0.2 mm and 1.0 mm. The braking body consists of a thermoplastic foil material of engineering plastic andi is made by thermo-vacuum shaping. The plastic material used is either polyethelyne, polyvinylchtorkle, or polyterephthalate (PE, PVC, PET).
EP 1 164 103 A discloses a braking body substrate and a weft yam feeder being equipped with a yarn brake including the frustoconical braking body substrate. The braking body substrate is made from calendered engineering thennoplastlc materials, thermoplastic resins or themiosetting plastic material and consists of an outer frustocontoal carrier body and an axially shorter frustoconical braking body inserted into the interior of the frustocontoal carrier body. One example of the engineering plastic material is epoxy resin. In the yarn feeder the braking body is axially resUiently pressed via the carrier body against the front end of the stationary storage body such that the braking zone at the inner surface of the frustoconical braking body contacts the rounded withdrawal rim. The large diameter end of the braking body protrudes outwardly in relation to the storage surface of the storage body. The small diameter end of the braking body substrate is situated in front of the front end of the storage body and is suspended in a radial star-like arrangenrtent of tenston springs the outer ends of which are anchored in a holder ring. The holder ring is snapped into a cannier ring whkih is axially adjustable in a housing bracket of the yarn feeder in order to set the contact pressure between the braking body and the storage body withdrawal rim.
DE 10 2004 051 372 A disclbses a braking body for a yam brake. The braking body Is a true regular frustocone jacket made from a mesh fabrk: containing weft yarns and warp yarns of polyester. The braking body is made by deep drawing under elevated tempera¬tures.
EP 1 243 542 A discloses a frustoconical braking body of a yarn brake of a yam feeder. The braking body has a discontinuous braking zone defined by a circumferential row of in¬clined slits in the fru8toconk:al jacket. The braking body is made from engineering themio-

plastic polymeric material or from engineering thermosetting polymeric material or from en¬gineering polymer reinforced with carbon fibre.
EP 0534263 A1 discloses a self-adjusting yarn braking device for weft-feeder units, the braking body of which is a truncated cone supported by an elastk: member coaxially and frontally with respect to a drum of the weft feeder unit. The braking body is constituted by a fabric or by a laminate of high-strength synthetic fibers, typteally carbon fibers or ffi)ers of "Kevlar". Alternatively, the braking body may be shaped from steel plate material or firom a synthetic material covered with a metallic layer in at least the braking zone.
The generally frustoconical braking body of a yarn brake is a wear part which'is to be ex¬changed frequently because the braking zone contacting the withdrawal rim of the storage body wears out rapidly. The yam is withdrawn overhead of the storage body between the withdrawal rim and the braking zone. During withdrawal the yam is orbiting like the hand of a clock, causing pennanent relative movements between the radially elastic braking body and the in most cases metallk: withdrawal rim. As the yam kx»iiy lifts the braking zone from the withdrawal rim the braking body permanently is deformed and is breathhg in rela¬tion to the withdrawal rim. Abrasion caused by friction of the orbiting withdrawn yam, abra¬sion caused by friction of the withdrawal rim and heat generated by the friction causes wear in the braking zone. The wear in the braking zone does not devetop uniformly but creates successive spots which are worn out more than the interspaces between the spots. A typi¬cal appearance of the worn-out braking zone of the braking body has the image of a pearl necklace The braking body at this point has to be replaced. The wear results in undesira¬bly short sen/ice life of the braking body and a relatively high frequency of braking body ex¬changes with a lot of shut-down time of the yarn feeder because an exchange of the brak¬ing body requires switching off the yarn feeder and the weaving machine or the knitting ma¬chine. The engineering plastic materials of known braking bodies, moreover, performed such that in operation of the yarn brake the yam tension resulting from the braking effect of the yarn brake shows significant irregularities even during each single orbiting revolutton of the withdrawn yarn albng the braking zone of the braking body. The irregularities result from the co-action betWeen the yam and the surface of the plastk: material of the braking body, and, furthermore, from Increasing wear. Irregularities of the yam tension may be the reason for yarn breakages and negative interference on the insertion process in the weaving machine or the knitting machine. Both drawbacks, the irregular yarn tension and the rapkl

progress of wear in the braking zone are detrimental to the performance of the braking body or the yarn feeder, respectively.
It is an object of the invention to create a braking body or a yarn feeder allowing to achieve a uniform yarn tension during each revolution of the withdrawn yarn along the braking zone and an extended service life of the braking body in order to lower the frequency of shut¬downs of the yarn feeder to exchange the braking body.
This object is achieved by the features of claim 1 and the features of claim 11.
Mainly due to excellent resilience against nrechanical loads and heat, and a very smooth and tough surface in th braking zone working with the yarn and the withdrawal rim the high-performance thermoplastk: polyketone material of the braking body results in br extended service life and a superior yarn tension development, compared to engineering firiastk; of known braking bodies. The yarn tension as produced during each revoiutton of the orbiting yarn along the braking zone of the braking body remains very uniform over nearly the full servke life of the braking body. The polyketone for the braking body is selected from the following polyketones group: polyetheretherketone, polyaryletherketone, polyetherketoneke-tone, or a similar polyketone. Polyketones in one family of high-performance themioplastic polynrs which allows to achieve the above mentioned advantages of the braking body. The high-performance themioplastic polyketone used for manufacturing the braking body expe¬diently has a Young's modulus between about 3.0 and 4.0 Gpa and a tensile strength be¬tween about 75 and 110 Mpa.
in the yarn feeder equipped with the frustoconical braking body made from a sheet or foil of a high-performance thenrtopiastic polyketone the material choice results in a markedly low¬ered frequency of shutdowns for braking body exchanges and in very few yarn breakages and almost no detrimental interferences with the yam insertkn process.
Preferably, the polyketone of the braking body has Young's modulus of about 3.6 Gpa and a tensile strength of about 90 Mpa.
In a preferred embodiment the braking body comprises a semi-crystalline or amorphous
high-performance thermoplastic polyketone. ,i •

Polyketone is a high-performance plastic material obtained from aromatic dehalides and bisphenolate salts by nucleophilic substitution.
Among the high-performance thennoplastic polymers like e.g. the family of polyketones
used for braking bodies of yarn brakes polyetheretherketone is one which exhibits two glass
transition temperatures around 140'C and 270'C, has a melting point of about SSO'C, and is
highly resistant to thermal degradation. Polyketones, furthermore, are resistant to l)oth or¬
ganic and aqueous environments and show a high strength to weight ratio, and are available
either semi-crystalline or amorphous. ,
Until now polyketones have been used in bearings, pistons, pumps, compressor valves and cable insulations. Polyketors are compatible with uKf'ahigh vacuum applications. Poly-etherethertcetone also is an advanced bio-compatible materiai used in medical implants, and
li ■ ; ii ■
is also used in structures of aerospace craft.
Owing to the excellent strength to weight ratio and the high resistancy against thermal deg¬radation, the wall thickness of the polyketone frustocone jacket only needs to anfKunt to be¬tween 0.1 mm and 0.5 mm. The small wall thickness results in a very lightweight braking body showing an excellent performance even in the case of high yarn speeds, or delk:ate yarn qualities, or small diameter storage bodies.
The excellent perfonnance of the braking body is achieved already with a homogenous frus¬tocone. However, for certain applications it even may be expedient to use a high-performance thermoplastic polymer like polyketone which contains reinforcing fibre material, even carbon fibres.
In an expedient embodiment the uniformity of the yarn tension resulting from the co¬operation between the braking zone of the braking body and the yam may be furtfier im¬proved by providing a circumferentially continuous, outwardly extending integrally formed flange at the large diameter end of the frustoconicai jacket. The flange somewhat stiffens or reinforces the large diameter end region of the braking body, attenuates an undulation tendency there and thus brings about an even more uniform devetopment of the yam ten¬sion during each revolution of the withdrawn yarn akng the braking zone. Moreover, when mounting or exchanging the braking body in nfost cases the braking tody is gripped by hand or with the help of a tool at the large diameter end. Also when removing resits of broken yarn or lint deposits by pressurised air or by using a tool or the fingers, the large diameter

end might easily become damaged, as a sharp large diameter end of a true frustocone jacket is prone to scratching or cracking during such manipulations. The flange forms a protection for the vulnerable large diameter end region of the braking body and thus contrib¬utes to a long service life..
In an expedient embodiment the flange extends substantially radially with respect to the frustocone axis. The flange fulfils a further protective function in that it hinders during awk¬ward operation conditions the yarn from moving outwardly around the and behind the large diameter end where it might wrap around protruding components of the yarn feeder.
In another expedient embodiment the flange is inversely conical in relation to the conicity of the frustocone jacket. So to speak, the outer edge of the frustocone jacket is bent back¬wards.
In a preferred embodintent the inversely conical polyketone flange has a rour(;ted curvature, in an axial section of the braking body, and a smooth transitton into the large aiameter end of the frustocone jacket. During operation of the braking body the polyketone flange damp¬ens a vibration tendency in the large diameter end region of the braking body. The flange may define an angle of about 90" with the outer surface of the frustocone jacket, the gen-eratrice of which, expediently, is a straight line between the small diameter end and the large diameter end.
In an expedient embodiment, the braking body is made by thermoshaping a high-performance thermoplastic polyketone foil or sheet, preiferably a flat blank. A preferred process for shaping the braking body is themio-vacuum shaping or deep drawing, preferably under elevated temperatures.
in another embodiment, the braking body made from the high-perfomance thermoplastic polykentone is inserted with an outer frustoconical can-ier body. The braking body defines the braking zone and constitutes - so to speak - a brake lining in the carrier body. The braking body may be attached to the inner wall of the carrier body.
Embodiments of the invention will be described with reference to the drawings. In the draw¬ings is:
Fig. 1 an axial section of a first embodiment of a'braking body,
I ■ ■ ;'■ ■

Fig. 2 an axial section of a second and third embodiment of a braldng body,
Fig. 3 an axial section of a yam feeder being equipped with a yarn brake fticluding a
braking body, e.g. according to Fig. 1, and
Fig, 4 an axial sectton of a braking body substrate,
A braking body B as shown in Fig. 1 is a yarn braking body intended for use in a yarn brake Y of a yarn feeder F (Fig. 3). The braking body B is a wew part or spare part whteh has to be exchanged when the service life has expired, e.g. due to wear.
The braking body B In Fig. 1 is a true frustocone jacket 1 having a small diameter end 3 and a large diameter end 2, a frustocone axis Z and a straight generatrlce. The frustocone jacket 1 has an inner continuous and smooth surface 4 and an outer surface 5. The Inner surface 4 defines a circumferentiaHy continuous braking zone 6 (indicated by a dotted line). The braking body comprises a high-performance thenT|optastic polyketone selected from the following polyketone group: potyetheretherketone, polyaryletherketone, poiyjtterketoneke-tone (PEEK, PAEK, PEKK). The wall thtekness x amounts to between 0.1 mm and 0.5 mm.
The braking body B is made by thermoshaping, preferably thermo-vacuum shaphig or deep drawing a sheet or a foil, most preferably a flat foil or sheet blank. The use of a liank re¬sults in the fact that the finally shaped braking body does not need further treatment like cut¬ting the edges in the small dlanieter end 3 or the large diameter end 2. The inner surface 4 of the frustocone jacket 1 may either have a polished surface quality or may be treated by polishing. The high-performance themnoplastic polymer such as a polyketone may be semi-crystalline or amorphous, and nmy even comprise reinforcing fibre material. The braking body B is elastic at least In radial direction and Is relatively stiff In axial direction along the axis Z.
In the embodiment in Fig. 2 a flange 7 (or 7' in dotted lines) may be integrally formed at the large diameter end 2 of the frustocone jacket 1, The flange 7' either extends racUaliy with respect to the axis Z of the frustocone jacket 1, or the flange 7 is inversely conical in relation to the conicity of the frustocone jacket 1 (shown in full lines). When being inversely conteal the flange 7 may be rounded with a radius r as shown, and may have a smooth transition 8 into the large diameter end 2 of the frustocone jacket 1.

The yarn feeder F (either a weft yam feeder for a weaving machine or a knitting yarn feeder for a knitting machine) in Fig. 3 includes a yarn brake Y being equipped with the braking body B shown in Fig. 1 or in Fig. 2 (not shown).
The yarn feeder F has a housing 9 containing a not shown motor for driving a central shaft
10. The rear part of the shaft 10 is hotbw and communicates with an obliquely outwardly
extending winding tube 11. A storage body 13 is rotatably supported on the shaft 10 and is
hindered against co-rotation with the shaft 10 by e.g. co-acting penanent magnets ar¬
ranged in the storage body 13 and the housing 9. The storage body 13 defines a substan¬
tially cylindrical storage surface 14 for a not shown yam supply consisting of consecutively
wound on yarn windings of a yarn exiting the winding tube 11. The yarn supply te formed
by rotating the winding tube 11 in relation to the stationary storage body 13. From the yarn
supply on the storage surface 14 the yarn is withdrawn overhead of the storage body 13 and
over a rounded or conical withdrawal rim 18 and through a stattonary outlet eyelet 15 sta-
tionarily supported in a bracket 12 of the housing 9. Tt|ie yarn eyelet 15, in this case, is
supported in a basket-shaped structure 17 snapped into a hokier 16 mounted in the bracket
12. The holder 16 may be adjusted along bracket 12.. 11
The basket-shaped structure 17, furthermore, holds a ring-shaped bocly 19 in turn hoMing the small diameter end 3 of the braking body B such that the braking body B Is axtally resil-iently pressed against the withdrawal rim 18 with the braking zone 6 contacting the entire circumference of the withdrawal rim 18. The large diameter end 2 of the braking body B protrudes outwardly beyond the withdrawal rim 18. The small diameter end 3 may be in¬serted loosely, or snapped-in into the body 19, or even may be fixed there.
During operation of the yarn feeder F the yarn while being withdrawn from the yam supply on the storage surface 14 is pulled through between the braking zone 6 of the braking body B and the withdrawal rim 18 before it runs through the outlet eyelet 15 and further axially to the insertion means (not shown) of the weaving machine or the knitting machine.
The braking body B is at least tocally radially deformed by the yam while the withdrawn yarn is orbiting around the withdrawal rim 18. The yarn is braked. The braking effect between the braking zone 6 and the withdrawal rim 18 and the frtetion of the yarn on the braking sur¬face 6 generate a certain yam tension In the running yarn, e.g. depending on the braking body contact pressure backed-up by the hokier 16. Due to the excellent surface quality and
i

the high resistance against abrasion by mechanical loads and heat of the high-performance thermoplastic polymer material such as polyketone plastic material as used for manufactur¬ing the braking body B, the yarn tension, depending among others on the coefficient of fric¬tion in the braking zone and the coefficient of friction in the withdrawal rim 18, remains broadly constant during each revolution of the yarn along the braking zone 6 and for the en¬tire service life.
In order to replace the braking body the holder 16 is moved in the bracket 12 in F. 3 to the right side until the braking body B forms a gap with the withdrawal rim 18. Then either the structure 17 is taken out from the holder 16 or the body 19 is taken out from the structure 17, or the braking body 8 directly is taken out from the ttody 19. Then the braking body B is replaced by another braking body B, before the holder 16 Is moved back Into the original position. In order to vary the braking effect the holder 16 nrtay be moved gradually in Fig. 3 to the left skle or the right skle in order to increase or decrease the axial contact pressure of the braking body B on the withdrawal rim 18.
The braking body substrate of Fig. 4 consists of an outer frustoconteal thinrwalted canrier body 20 of frustoconical shape and the braking body 6: The braking body B e.g. made of polyketone is inserted into the can'ier body 20 and maybe attached to the Infer wall of the carrier body 20 between big-diameter and small-diameter ends 21,22. The braking body B has the same conicity as the carrier body 20, and may be axially shorter than or as long as the carrier body 20. The carrier body 20 may consist of a high-performance thermoplastic polymer such as polyketone as well, or of another polymerk: ptastte material, or of sheet metal, or of a plastto impregnated fabric. The polyketone braking body B constitutes a brake lining of the braking body substrate. As indicated, the carrier body 20 may be integrally formed with an end flange 7', similar to the braking body B In Fig. 2.

CLAIMS
1 Braking body (B) of a yarn brake (Y) of a yarn feeder (F), the braking body (B)
generally being a frustocone Jacket (1) made of at least radially elastic thermoplastic polymeric foil material (P), the inner surface (1) of the braking body (B) defining a circumferentially continuous yarn braking zone (6) characterised in that the braking body (B) comprises a high-performance thermoplastk: polyketone from the folk)wing group of polyketones: polyetheretherketone, polyaretherketone, polyetherketoneketone (PEEK, PAEK. PEKK), and that the polyketone in the braking body (B) has a Young's modulus between about 3.0 GPa and 4.0 GPa and tensile strength between about 75 and 110 MPa.
2. Braking body according to claim 1, characterised In that the braking body (B) comprises a semi-crystalline or amorphous high-performance thermoplastic polyketone.
3. Braking body acicording to claim 1, characterised In that the polyketone in the braking body (B) has a Young's modulus of aboiit 3.6 GPa, and tensile Strength of about 90 MPa.
4. Braking body according to claim 1, characterised in that the wall thtekness (X) of the polyketone frustocone jacket (1) Is substantially constant and amounts to about between 0.1 mm and 0.5 mm.
5. Braking body according to at least one of the preceding claims, characterissd in that the frustocone jacket (1) comprises polyketone and reinforcing fibre material.
6. Braking body according to at toast one of the precedkig claims, characterised in that the braking body (B) has a circumferentially contbiuous, outwardly extending integrally formed flange (7, 7') at the large diameter end (2) of the frustocone jacket

7. Braking body according to claim 6, characterisiRd in that the flange (7') at the large
diameter end (2) extends substantially radially ith respect to the frusJloone axis (Z).
8. Braking body according to claim 6, characterised In that the flange (7) is inversely conical in relation to the conicity of the frustocone jacket (1), preferably witti a rounded curvature (r) and a smooth transition (8) in the large diameter end (2), such that the polyketone flange defines a angle (a) of about 90" with the outer surface (5) of the frustocone jacket (1).
9. Braking body according to at least one of the preceding claims, characterised in that the braking body (B) is made by thermoshaping, preferably themno-vacuum shaping or deep drawing, of a foil-blank or of a sheet of polyketone
10. Braking body according to at least one of the preceding claims, characterised in
that the braking body (B) is inserted into, and preferably attached to, an outer carrier
body (20) being a frustocone jacket, preferably consisting of polyketone or of another
polymeric material or of sheet metal or of an impregnated fabric.
11. Yarn feeder (F), in particular weft yam feeder or knitting yarn feeder, comprising a
stationary storage body (13) defining a substantially cylindrical storage surfece (14)
for a yarn supply, the storage body (13) having a circumferentlally continuous front
end withdrawal rim (18) for overhead withdrawal of a yarn from the yarp supply and
over the withdrawal rim (18), a yarn brake (Y) including a braking body (B) generally
being a frustocone jacket (1) made of at least radial elastic homogenous
thermoplastic polymeric foil material (P), the inner surface (1) of the braking body (B)
defining a circumferentlally continuous yarn braking zone (6), the braking body (B)
being resiliently pressed axially against the storage body (13) such that the braking
body braking zone (6) contacts the withdrawal rim (18) from the front SKle,
characterised in that the braking body (B) consists of a high-performance
thermoplastic polyketone of the following group: polyetheretheritetone,
polyaryletherketone, polyetherketoneketone (PEEK, PAEK, PEKK).

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Patent Number

271415

Indian Patent Application Number

247/CHE/2010

PG Journal Number

09/2016

Publication Date

26-Feb-2016

Grant Date

19-Feb-2016

Date of Filing

01-Feb-2010

Name of Patentee

IRO AB

Applicant Address

PO BOX 54, 52322 ULRICEHAMN

Inventors:

#	Inventor's Name	Inventor's Address
1	BROVARONE, CESARE	VIA GARIBALDI 12/C, COSSATO, 13836 BIELLA,

PCT International Classification Number

D03D 47/36 ; D04B 15/48

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	09001467.1	2009-02-03	EUROPEAN UNION