Title of Invention

SPINNING HEAD AND FILTER DEVICE FOR SUCH A SPINNING HEAD

Abstract

The invention relates to a spinning head which is used to melt spin a plurality of synthetic filaments, and to a filter device for said type of spinning head. A filter device is arranged between an inlet plate comprising a melt inlet and a die base comprising several die holes, said filter device comprising a cylindrically-shaped filter ring element which can be cross-flown from the outside to the inside. A separate second filter ring element is associated with the first filter ring element in order to form a sufficient filter surface with large melt through-put rates, said second ring element being arranged at a distance in relation to the outer lying first filter ring element. A first partial flow of the melt is guided through the first filter ring element from the outside to the inside and a second partial flow of the melt is guided through the second filter ring element from the inside to the outside in order to combine them together in a release chamber formed between the filter ring elements.

Full Text

Spinning Head and Filter Device for such a Spinning Head The present invention relates to a spinning head for the melt spinning of a large number of synthetic filaments according to the precharacterising part of claim 1, as well as to a filter device for a spinning head according to the precharacterising part of claim 12. A generic spinning head as well as a generic filter device are known from EP 1 093 535 Bl. In the extrusion of polymer melts the melt is filtered before its passage through a large number of die orifices of a die plate within the spinning head. To this end the known spinning head comprises a filter device that contains a cylindrical filter ring element. The filter ring element is formed by a supporting tube and a filter jacket surrounding the supporting tube, the said supporting tube and the filter jacket being combined at the supporting ends to form a sealing edge. The filter ring element is held in a self-sealing manner within the spinning head by means of a distribution piece, whereby the melt stream, distributed over the circumference of the filter ring element, flows from the outside to the inside through the filter jacket. Such spinning heads and filter devices have proved effective in spinning synthetic fibres for textile applications. However, there are natural limits as regards melt throughput and service life, which means that such heads and devices can be used only to a limited extent for the melt spinning of synthetic fibres for technical applications involving large melt throughputs. In order to make available suitably.large filter surfaces for the realisation of high melt throughputs, spinning heads with filter devices that are based on an annular -filter element are known for example from US 4,405,548 or from DE 199 15 700 Al (US 6,171,536), in which the filter elements have a U-shaped or V-shaped cross-section. Such filter devices have the disadvantage however that the filter elements cannot be held in a self-sealing manner in the spinning head, with the result that a special sealing effort and expenditure is unavoidable when using the known filter device. In contrast to this, a spinning head and a filter device are known from EP 0 178 570 Al, in which the filter device is formed by a plurality of individual filters employed in a circular arrangement. For this, a plurality of individual filter elements therefore have to be arranged ir a sealing manner between'the melt feed inlet and the die orifices, with the result that the sealing requirements are increased still further. In the known solutions, in which profiled filter elements are used, there is also the problem that, due to the shape of the filter elements, the throughflow characteristics differ over the whole surface of the filter element, so that preferred throughflow regions are formed that then lead to a non-uniform utilisation of the filter material. As a result no uniform melt flow occurs within the spinning head. The object of. the invention is now to equip a spinning head of the type mentioned in the introduction with as large a filter capacity as possible and thereby avoid the aforementioned disadvantages. A further object of the invention is to provide a filter device that is suitable in particular for high melt throughputs and for a self-sealing installation in a spinning head. For a spinning head the object according to the invention is achieved if a separate second filter ring element is provided that is arranged at a spacing with respect to the outer-lying first filter ring element and through which melt can flow from the inside to the outside, a delivery space being formed between the two filter ring elements. For a filter device the object according to the invention is achieved if a second filter ring element of smaller diameter is associated with the first filter ring element and spaced therefrom, through which second filter ring element flows a partial stream of the melt flow from the inside to the outside, if the supporting ends of the filter ring elements are designed so as to have concentric sealing edges, and if both filter ring elements have a substantially identical rigidity. The arrangement and design of the two filter ring elements according to the invention means that a uniform, homogenised melt flow for melt spinning at high melt throughput rates is achieved. Melt flows through each of the filter ring elements in a very uniform manner. The inter-fitting design of the filter ring elements leads in addition to a compact structure. Due to the substantially identical rigidity of the filter ring-elements a joint fixing within the' spinning head is possible .without any danger of localised leakages. In order to fix the filter ring elements to one another a modification of the invention has in particular proved effective, in which a distribution ring is associated with the filter ring elements. In this connection the distribution ring contains a distribution head that in each case rests against an upper supporting end of the filter ring elements, and a distribution collar that projects into the delivery space between the filter ring elements. With a self-sealing arrangement of the filter device within the spinning head, the distribution ring is movably held. The distribution ring is thus particularly suitable on the one hand to effect, between the distribution head and the upper supporting ends-of the filter ring elements, a sealing of the delivery space with respect to the melt inflow, and on the other hand to ensure a radial support so as to increase the stability of the filter ring elements. For this purpose the distribution collar has on both sides a plurality of webs distributed over its circumference, which rest against the filter ring elements. In order to ensure a centering in particular on a movably held distribution ring, according to an advantageous modification of the invention a holding plate is provided that is arranged between the inlet plate and the die plate, the said holding plate forming a support for the lower supporting end of the filter ring elements. In this connection it is particularly advantageous if the holding plate has above the support an annular distribution chamber in which the filter ring elements are held. An optimised melt feed to the individual filter ring elements can thus be effected by suitably shaping the walls of the distribution chamber. The melt feed from the melt inlet to the distribution chamber may in this connection advantageously take place through an outer annular channel and an inner annular channel that is formed between the distribution ring and the holding plate on the oppositely facing supporting end of the filter ring elements. The holding plate may also be used in order to distribute the melt, after leaving the delivery space, to the individual die orifices of the die plate.. For this purpose at least one distribution groove, is formed on the lower side of the holding plate. The distribution groove can be expanded by further partial grooves to form a groove system, so that annular as well as circular die orifice arrangements in the die plate can be supplied uniformly with a melt. It is however also possible to arrange between the holding plate and the die plate an additional distribution plate, through which the distribution of the melt is effected. In order to achieve a sufficient pressure stability combined with favourable throughflow properties, the filter ring elements are preferably formed in each case by a supporting cylinder with fluid passages on the walls and a filter jacket. In this case the outer supporting cylinder is connected to the outer-lying filter jacket and the inner supporting cylinder is connected to the inner-lying filter jacket to form in each case a unit. The desired rigidity can be influenced by the fluid passages incorporated in the wall of the supporting cylinder. Thus, the size and the number of the fluid passages in both filter ring elements may be chosen differently. The outer filter jacket and the inner filter jacket are preferably formed by a pleated filter material in order to obtain as large a filter surface as possible. The pleated filter material can in this connection advantageously be formed as a wire mesh or non-woven fabric. Further advantages of the invention are described in more detail hereinafter with the aid of some examples of implementation of the spinning head according to the invention as well as an example of implementation of the filter ring element, with regard to the accompanying drawings in which: Fig, 1 shows diagrammatically a longitudinal sectional view through a spinning head according to the invention with a filter device according to the invention, Fig. 2 Fig. 3 shows diagrammatically several views of the filter device according to the invention from the example of implementation of the spinning head according to Fig. 1, shows diagrammatically a longitudinal sectional view of a further example of implementation of the spinning head according to the invention. In Fig. 1 a first example of implementation.of the spinning head according to the invention is shown diagrammatically in a longitudinal sectional view. The spinning head has a cylindrical housing ll An inner-lying housing collar 7 is formed on the lower side of the housing 1. A die plate 5 guided within the housing 1 lies on the housing collar 7. The die plate 5 has on its lower side a plurality of die orifices 6 that are in communication, through die channels 35, with the upper side of the die plate 5. At the upper end of the housing 1 is formed an inner-lying thread 8 via which an inlet plate 2 is guided within the housing 1. The inlet plate 2 has a centrally formed melt feed inlet 3 that is connected to a melt line (not shown here). The melt feed inlet 3 is connected via feed channels 23 to the lower side of the inlet plate 2. Between the inlet plate 2 and the die plate 5 there is formed a filter device 4 within the housing 1, through which the feed channels 23 formed in the inlet plate 2 are connected to the die channels 35 of the die plate 5. In order to receive and hold the filter device 4, a holding plate 17 is arranged between the inlet plate 2 and the die plate 5. To this end the inlet plate 2 is introduced into the housing 1 in such a way that the sealing gaps between the die plate 5 and the holding plate 17 as well as between the inlet plate 2 and the holding plate 17 are sealed. An annular distribution chamber 1.8 is formed in the holding plate 17, the chamber being connected via a passage 32 to a distribution groove 19 on the lower side of the holding plate 17. The passage 32 is likewise annularly shaped. For this purpose the holding plate 17 consists of an outer half and an inner half. A first, outer filter ring element 9 and a second, inner filter ring element 10 are arranged within the distribution chamber 18 symmetrically with respect to the passage 32, The construction of the filter ring,elements 9 and 10 is described in more detail hereinafter. The outer filter ring element 9 and the inner filter ring element 10 are cylindrically shaped and are arranged spaced apart from one another. A distribution ring 12 lies against an upper supporting end 15. The distribution ring 12 is formed by the distribution head 13 provided outside the filter ring elements 9 and 10 and by the distribution collar.14 projecting between the filter ring elements 9 and 10. The distribution ring 12 is supported on the upper side of the holding plate 17 at the oppositely lying inlet plate 2 by a spring element 25. In this connection the distribution head 13 extends substantially over the whole opening cross-section of the distribution chamber 18 within the holding plate 17, an inner annular channel 21 formed between the holding plate 17 and the distribution ring 12 being arranged .on the inner circumference of the distribution head 13 and an outer annular channel 20 formed between the-distribution ring 12 and the holding plate 17 being arranged on the outer circumferential side of the distribution head 13. A feed chamber 22 in which the feed channels 23 terminate is formed above the distribution head 13 on the lower side of the inlet plate 2. The feed chamber 22 is connected by the outer annular channel 2 0 and the inner annular channel 21 to the distribution chamber 18, which is divided by the filter ring elements 9 and 10 into an outer half and an inner half. Between the filter ring elements 9 and 10 there is formed a delivery space 11, the lower supporting ends 16 of the filter ring elements 9 and 10 being supported at the lower end of the distribution chamber 18 on the holding plate 17. The distribution collar 14 of the distribution ring 12 projecting into the delivery space 11 comprises on its inner-lying and outer-lying longitudinal sides in each case a plurality of webs 24, by means of which the filter ring elements 9 and 10 are radially supported. In operation a melt of a polymer is fed under pressure through the melt feed inlet 3 to the spinning head. The melt passes through the feed channels 23 to the feed chamber 22. From the feed chamber 22 a part of the melt stream flows through the outer annular channel 2 0 into the outer half of the distribution chamber 18 and a second part of the melt stream flows through the inner annular channel 21 into the inner half of the distribution chamber 18. A resultant compressive force is thereby generated at the distribution ring 12, which forces the distribution ring 12 in the direction-of the die plate 5. As a result the lower supporting end 16 of the filter ring elements 9 and 10 is pressed against the support of the holding plate 17 and the upper supporting end 15 is pressed against the lower, side of the distribution head 13. The sealing edges formed at the supporting ends 15 and 16 thus effect a seal between the distribution chamber 18 and the delivery space 11. Melt flows uniformly through the filter ring elements 9 and 10. In this connection a partial stream flowing from the outside out of the distribution chamber 18 inwardly in the direction of the delivery space 11 acts on the outer filter ring element 9. A counteracting partial stream, flowing from the inside out of the distribution chamber 18 outwardly in the direction of the delivery space 11, acts on the other hand on the inner filter ring element 10. In the delivery space 11- the partial streams are combined via the distribution collar 14 and fed through the passage 32 into the distribution groove 19. The melt passes from the distribution groove 15 into the die channels 35, and is then extruded as a plurality of synthetic filaments through the die orifices 6. In order to be able to provide on the one hand a uniform throughflow and on the other hand as large a filter surface as possible, the filter ring elements 9 and 10 may be designed according to the following example of implementation. Fig. 2 shows diagrammatically in several views a filter device according to the invention for a spinning head. In this connection Fig. 2.1 shows diagrammatically a longitudinal section and Fig. 2.2 shows diagrammatically a transverse section. Where no specific reference is made to one of the figures, the following description applies equally to both figures. The filter device has an outer filter ring element 9 and an inner filter ring element 10 of smaller diameter. The diameters of the two filter ring elements 9 and 10 are chosen so that there is a sufficient spacing between the filter ring elements 9 and 10 to form a delivery space 11. The fixing and co-ordination of the filter ring elements 9 and 10 is preferably achieved by means of a distribution ring 12. The distribution ring 12 is shown in dotted lines in Figs. 2.1 and 2.2. The co-ordination and the fixing of the filter ring elements 9 and 10 may however also be achieved by any other equivalent means. The outer filter ring-element 9 is formed by a supporting cylinder 26 and a filter jacket 29 enclosing the supporting cylinder 26. The supporting cylinder 26 and the filter jacket 2 9 are in each case joined at the upper supporting end 15 and at the lower supporting end 16 and form in each case a circumferential sealing edge 31. The supporting cylinder 26 comprises a plurality of fluid passages 27. Such a filter ring element is known for example from EP 1 0 93 53 5, and accordingly reference may be made thereto at this point. The filter jacket 29 is.preferably formed from a pleated filter material. The inner filter ring element 10 is constructed identically to the outer filter ring element 9, the sole difference being that an inner-lying filter jacket 3 0 is arranged on the supporting cylinder 2 8. The inner filter jacket 3 0 and the supporting cylinder 28 are similarly joined at the supporting ends 15 and 16 to form in each case a sealing edge 31. Further details may be obtained from the preceding explanation, and accordingly a detailed description of the inner filter ring element 10 can be omitted. The design of the fluid passages 27 in the supporting cylinders 26 and 28 is chosen especially having regard to a substantially uniform axial rigidity of the filter ring elements 9 and 10. However, in order to achieve a uniform axial rigidity it is also possible to vary the wall thicknesses of the supporting cylinders 26 and 28, having regard to the fluid passages 27. In operation the supporting cylinders 2 6 and 2 8 are supported by the distribution ring 12. As shown by the dotted lines in Fig. 2.2, the distribution ring 12 comprises on its collar engaging between the supporting cylinders 26 and 28, on both sides a plurality of webs 24 that rest against the supporting cylinders 26 and 28. The cavity between the webs 24 forms the delivery space 11. The filter device illustrated in Fig. 2 is accordingly suitable for combining two partial melt streams after the filtration. In this connection an outer partial melt stream can be fed from the outside to the inside, and an inner partial melt stream can be fed from the inside to the outside. In this way the sealing edges 31 formed at the supporting ends 15 and 16 ensure a self-sealing insert within the spinning head. Fig. 3 shows diagrammatically in a longitudinal section a further example of implementation of.a spinning head according to the invention. Here the structural parts performing the same function have been, provided with identical reference numerals. The example of implementation according to Fig. 3 is substantially identical to the.previous example of implementation according to Fig. 1, so that at this point only the differences need be discussed. In the housing 1 a die plate 5 comprising a circular arrangement of die orifices 6 is arranged on the lower side. A holding plate 17 is arranged between the die plate 5 and the inlet plate 2, and an additional distribution plate 33 is arranged between the holding plate 17 and the die plate 5. The holding plate 17 comprises an annular distribution chamber 18, which is connected via a passage 32 to the lower side of the holding plate 17. The passage 32 is in this connection formed by a plurality of circularly arranged orifices, so that the holding plate consists of one part. The filter ring elements 9 and 10 are arranged symmetrically with respect to the passage 3 2 by means of a distribution ring 12 mounted on the upper supporting end 15. The distribution ring 12 is formed by a distribution.collar 14 and a plate-shaped distribution head 13. Above the distribution ring 12 there is formed in the inlet plate 6 a feed chamber 22 that is connected by.means of an outer annular channel 2 0 as well as by a plurality of: inlet channels 3 6 to the outer and inner halves of the distribution chamber 18. The distribution plate 33, which comprises a plurality of distribution orifices 19 and distribution bores 34, is arranged underneath the holding plate 17. The groove and orifice system within the distribution plate 33 is given by way of example. The melt discharged from the delivery space 11 through the passage 32 is uniformly distributed to the die channels 35 of the die plate 5. The function of the example of implementation of a spinning head illustrated in Fig. 3 is identical to the preceding example of implementation, and accordingly no further explanation will be given here. The examples of implementation according to Figs. 1 and 3 represent a preferred variant of the spinning head according to the invention with a self-sealing filter device. The spinning head according to the invention may however also advantageously be realised with the variants in which no self-sealing filter device is provided, but instead a sealing of the filter device is achieved by for example clamping forces. Reference Numeral List 1 Housing 2 Inlet plate 3 Melt feed inlet 4 Filter device 5 Die plate 6 Die orifices 7 Housing collar 8 Thread 9 Outer filter ring element 10 Inner filter ring element 11 Delivery space 12 Distribution ring 13 Distribution head 14 Distribution collar 15 Upper supporting end 16 Lower supporting end 17 Holding plate 18 Distribution chamber 19 Distribution -groove 2 0 Outer annular channel 21 Inner annular channel 22 Feed chamber 23 Feed channel 24 Webs 25 Spring element 2 6 Outer supporting cylinder 27 Fluid passages 2 8 Inner supporting cylinder 29 Outer filter jacket 30 Inner filter jacket 31 Sealing edge 32 Passage 33 Distribution plate 34 Distribution orifices 35 Die channel 36 Inlet channel Patent Claims 1. Spinning head for the melt spinning of a plurality of synthetic filaments with a housing (1) for receiving an inlet plate (2) with a melt feed inlet (3) and a die plate (5) with a plurality of die orifices (6) and with a filter device (4) arranged between the inlet plate (2) and the die plate (5), which filter device comprises a cylindrical filter ring element (9) through which melt flows from the outside to the inside, characterised in that a separate second filter ring element (10) is provided that is arranged spaced from the outer-lying first filter ring element (9) and through which melt can flow from the inside to the outside, wherein a delivery space (11) is formed between the two filter ring elements (9, 10). 2. Spinning head according to claim 1, characterised in that a distribution ring (12) is associated with the filter ring elements (9, 10), which rests via a distribution head (13) against in each case an upper supporting end (15) of the filter ring elements (9, 10) and which projects by means of a distribution collar (14) between the filter ring elements (9, 10). 3. Spinning head according to claim 2, characterised in that the distribution head (13) and the upper supporting ends (15) of the filter ring elements (9, 10) form a seal for the delivery space (11) with respect to the melt feed inlet (3). 4. Spinning head according to claim 2 or 3, characterised in that the distribution collar (14) comprises on the sides facing the filter ring elements (9, 10) a plurality of webs (24) for the radial support of the filter ring elements (9, 10). 5. Spinning head according to one of the preceding claims, characterised in that a holding plate (17) is arranged between the inlet plate (2) and the die plate (5), which holding plate forms a support for the lower supporting ends (16) of the filter ring elements (9, 10). 6. Spinning head according to claim 5, characterised in that the holding plate (17) above the support comprises an annular distribution chamber (18) in which the filter ring elements (9, 10) are held, wherein an outer annular channel (20) and- an inner annular channel (21) are formed between the distribution head (13) and the holding plate. (17) at the end of the distribution chamber (18), by means of which channels the distribution chamber (18) is connected to the melt feed inlet (3). 7. Spinning head according to claim 5 or 6, characterised in that the holding plate (17) underneath the support comprises a distribution groove (19) by means of which the delivery space (11) is connected to the die orifices (6) of the die plate (5). 8. Spinning head according to one of claims 5 to 7, characterised in that the holding plate (17.) is formed in two parts by an outer partial piece and an inner partial piece. 9. Spinning head according to one oft the preceding claims, characterised in that the outer filter ring element' (9) is formed by a supporting cylinder (26) with fluid passages (27) on the walls and by an outer filter jacket (29) , wherein the supporting cylinder (26) and the filter jacket (29) are joined at the supporting ends (15, 16). 10. Spinning head according to one of claims 1 to 9, characterised in that the inner filter ring element (10) is formed by a supporting cylinder (28) with fluid passages (27) on the walls and by an inner filter jacket (30), wherein the supporting cylinder (2 8) and the filter jacket (3 0) are joined at the supporting ends (15, 16). 11. Spinning head according to one of claims 1 to 10, characterised in that the filter ring elements (9, 10) are held at the supporting ends (15, 16) in a self-sealing manner between the distribution ring (12) and the holding plate (17). 12. Filter device for a spinning head, in which a melt stream is fed through a cylindrical filter ring element (9) from the outside to the inside and in which the filter ring element (9) is held with an upper supporting end (15) and with a lower supporting end (16) in a self-sealing manner within the spinning head, characterised in that a second filter ring' element (10) of smaller diameter-is associated with the filter ring element (9) and is spaced therefrom, through which second element flows a part of the melt stream from the inside to the outside, that the supporting ends (15, 16) of the filter ring elements (9, 10) are designed to form concentric sealing edges (31), and that both filter ring elements (9, 10) have substantially the same rigidity. 13. Filter device according to claim 12, characterised in that the filter ring elements (9, 10) are formed in each case by a supporting cylinder (16, 28) with fluid passages (27) on the wall and by a filter jacket (29, 30)-, wherein the outer supporting cylinder (26) is connected to the outer-lying filter jacket (.29) and the inner supporting cylinder (28) is connected to the inner-lying filter jacket (30). 14. Filter device according to claim 13, characterised in that the outer filter jacket (29) and the inner filter jacket (30) are formed in each case by a pleated filter material. 15. Filter device according to one of claims 12 to 15, characterised in that the filter ring elements (9, 10) are combined with a distribution ring (12) that comprises a distribution collar (14) for supporting the filter ring elements (9, 10). .6- Method for melt spinning a plurality of synthetic filaments from a plastics melt, in which the melt is filtered before being extruded, characterised in that before the filtration the melt is subdivided into two partial streams, that the partial streams are filtered, through two separate filter elements, and that the partial streams are combined before being extruded.

Documents:

1769-CHENP-2006 CORRESPONDENCE OTHERS 05-12-2011.pdf

1769-CHENP-2006 AMENDED CLAIMS 19-06-2012.pdf

1769-CHENP-2006 CORRESPONDENCE OTHERS 05-01-2012.pdf

1769-CHENP-2006 CORRESPONDENCE OTHERS 27-06-2012.pdf

1769-CHENP-2006 EXAMINATION REPORT REPLY RECEIVED 19-06-2012.pdf

1769-CHENP-2006 FORM-3 19-06-2012.pdf

1769-chenp-2006-abstract.pdf

1769-chenp-2006-claims.pdf

1769-chenp-2006-correspondnece-others.pdf

1769-chenp-2006-description(complete).pdf

1769-chenp-2006-drawings.pdf

1769-chenp-2006-form 1.pdf

1769-chenp-2006-form 26.pdf

1769-chenp-2006-form 3.pdf

1769-chenp-2006-form 5.pdf

1769-chenp-2006-form18.pdf

1769-chenp-2006-pct.pdf