Title of Invention

A FALSE TWIST DEVICE FOR FALSE TWISTING A SYNTHETIC MULTIFILAMENT YARN

Abstract

A false twist device is described for false twisting a synthetic multifilament yarn, wherein a plurality of shafts are supported for rotation in a bearing block. The shafts are each arranged at a center distance between one another in the configuration of a triangle. The shafts mount in offset relationship a plurality of friction disks, which have a disk diameter of such a size that they overlap in the center of the triangle, and form a winding yarn path with their circumferential surfaces. To obtain at high production speeds a decrease in the yarn tension with a high twist effect, the overlap of the friction disks is determined in accordance with the invention by a ratio of the disk diameter to the center distance of > 1.45, with the friction disks having a disk width in a range from 9.5 mm to 11.5 mm.

Full Text

Translation SX81753PCT/TEX3136 KA/ku 030563/280754 FALSE TWIST DEVICE The invention relates to a false twist device for false twisting a synthetic multifilament yarn as defined in the preamble of claim 1. In the production of crimped textile yarns, it is known to impart to the yarn by friction a false twist, which is set in the filaments of the yarn by a thermal treatment in a texturing zone. To produce the false twist, false twist devices have been found especially successful, in which the yarn advances along the circumferential surfaces of rotating and overlapping friction disks. A false twist device of this type is disclosed, for example, in EP 0 943 022 Bl. In the known false twist device, the friction disks are arranged on three shafts, which are rotatably supported in a bearing block. The shafts are arranged with a center distance between one another in the configuration of a triangle such that the friction disks overlap in the center of the triangle. A drive unit drives the shafts in such a manner that the friction disks rotate at a substantially constant circumferential speed. To produce the false twist, the yarn advances' in the center over the circumferential surfaces of the friction disks, so that it forms a winding yarn path. In so doing, the yarn advances obliquely over the circumferential surfaces of the CLT01/4657709vl Friction disks. The friction mechanisms that are active between the yarn and the circumferential surface of the friction disks result in generating a tensile force on the yarn for advancing it, and a transverse force for twisting it. The ratio of the tensile force for advancing the yarn to the transverse force for twisting the yarn is substantially dependent on the disk geometry and the degree of overlap of the disks. As a general rule, an increasing feed effect permits texturing the yarn in a more protective manner. However, a greater feed effect is achievable only at the expense of a reduced twist impartation. It is therefore desired that the feed effect that is generated by the false twist device and the twist impartation be favorably proportionate to each other. However, as a tendency one can observe that an increasing feed effect is achievable only at the expense of a decreasing twist impartation. To this end, it is proposed in the case of a false twist device disclosed in WO 99/51804 to guide the yarn over the circumferential surfaces of the friction disks at a predetermined angle of inclination or looping angle. In comparison with the art, a flatter looping angle was found especially advantageous for achieving high production speeds. While the proposed flatter looping angle permits increasing the contact length between the yarn and the circumferential surface of the friction disk, so that the frictional conditions lead to an increase in tensile force, it has the great disadvantage that the force component for producing a twist impartation decreases. This disadvantage is further increased in that in proportion to the width of the friction disk, a profile radius is selected as CLT01/4657709vl Large as possible in a range from 6.5 mm to 8 mm,which automatically results in small looping angles. It is therefore an object of the invention to realize a false twist device for false twisting a synthetic multifilament yarn of the described type such that it enables a protective yarn treatment with a maximum twist impartation even at high production speeds. A further object of the invention is to provide a geometry of the friction disks for a false twist device of the described type, which permits an optimum between the advance of the yarn and the impartation of twists to the yarn regardless of the type of yarn. In accordance with the invention, this object is accomplished by a false twist device with the features of claim 1 and a friction disk with the features of claim 8. Advantageous further developments of the invention are defined by the features and feature combinations of the respective dependent claims. The invention takes a new approach to a solution on the basis that the friction disks have a diameter that is as large as possible. When viewed alone, an enlargement of the diameter of the friction disks would initially achieve a decrease of the circumferential speed of the friction disks and thus a reduction of the twist impartation. On the other hand, however, the enlargement of the disk diameter will change the looping of the yarn over the circumferential surface of the friction disk to an extent that the component of the feed effect increases. It has come as a surprise to find that despite the enlarged disk diameter, the loss in the twist impartation will be CLT01/4657709vl Compensated when a certain disk width and a minimum overlap of the friction disks are maintained,so that a yarn-protecting maximal impartation of twists to the yarn results despite high production speeds. The overlap of the friction disks is defined by a ratio of the disk diameter to the center distance between the shafts, which is above a value of 1.45. In this connection, the friction disks have a width ranging from 9.5 mm to 11.5 mm. The ratio formed by the disk diameter and the center distance is upwardly limited by the predetermined center distance between the shafts. Furthermore, it has shown that friction disks with a width of a range below 9.5 mm lead to an undesired twist decrease- In comparison therewith, it was possible to produce more twists than needed with friction disks that have a width greater than 11.5 mm, however, with the disadvantage of a too small feed effect. In the case of the commonly used center distances between the shafts, the aforesaid advantages can be achieved by the friction disks of the invention, with the friction disks having a geometry with a disk diameter ranging from 54 mm to 62 mm, a disk width of a range from 9.5 mm to 11.5 mm, and a profile radius on the circumferential surface of the friction disks, which forms with the disk width a ratio ranging from 1.6 to 2.0. As a function of the size of the center distance between the shafts, friction disks with identical disk diameters have been found especially successful for a center distance of at most 37.5 mm, when the disk diameter ranged from 54 mm to 56.5 mm. For greater center distances of maximally 39.5 mm, the CLT01/4657709vl Preferred diameter range of the friction disks was from 56 mm to 62 mm. To adjust the looping angles on the circumferential surfaces of the friction disks as large as possible, it is furthermore proposed to provide the friction disks with a profile radius on their circumferential surfaces, which forms with the disk width a ratio of a range from 1.6 to 2.0. In this case, the profile radius on the circumferential surface of the friction disk is made preferably symmetrical, so that the advance of the yarn to and from the circumferential surface of the friction disks is maintained equal. It has furthermore been found that a maximum performance is achievable by mounting on the shafts a total of seven friction disks in overlapping relationship. An increase of the number of friction disks has shown no improvement in efficiency. The friction disks may be made of a ceramic, an elastomer, or a plastic. Irrespective of the selection of the material, the service life is advantageously lengthened in particular in the case of all soft materials. In the following, an embodiment of the false twist device according to the invention is described in greater detail with reference to the attached drawings, in which: Figure 1 is a schematic view of the embodiment of the false twist device according to the invention; Figure 2 is a schematic top view of the embodiment of Figure 1; and Figure 3 is a schematic cross sectional view of a friction disk of the embodiment of Figure 1. CLT01/4657709vl Figures 1 and 2 schematically illustrate a first embodiment of the false twist device according to the invention. Figure 1 is a perspective view of the false twist device and Figure 2 a top view thereof. The following description will apply to both Figures, unless express reference is made to one of the Figures. The false twist device comprises a bearing block 1. The bearing block 1 rotatably supports in cantilever fashion a plurality of shafts 2.1, 2.2, and 2*3. The shafts 2.1, 2.2, and 2.3 connect with their bearing end to a drive unit not shown. Such a drive unit is disclosed, for example, in EP 0 744 480 Al. In this respect, the contents of the cited publication are herewith expressly incorporated by reference. The shafts 2.1, 2.2, and 2.3 are arranged in the configuration of a triangle. The shafts 2.1, 2.2, and 2.3 mount a plurality of friction disks 4.1-4.7 in offset relationship with one another. More specifically, in the direction of the advancing yarn, the shaft 2.1 mounts in spaced relationship an inlet disk 3 and two friction disks 4.3 and 4.6. The second shaft 2.2 comprises directly downstream of the inlet disk 3 a first friction disk 4.1 and in spaced relationship therewith additional friction disks 4.4 and 4.7. In the direction of the advancing yarn, the third shaft 2.3 supports a first friction disk 4.2, which is arranged between the friction disks 4.1 and 4.3. In spaced relationship with the friction disks 4.2, a friction disk 4.5 follows, which is arranged between the friction disks 4.4 and 4.6. At its end, the shaft 2.3- mounts an outlet disk 5. As shown, in Figure 2, the shafts 2.1, 2.2, and 2.3 are each arranged at a same center distance A to form the triangle. The friction disks (Figure 2 CLT01/4657709vl omits the inlet disk 3) have a disk diameter D of such a large size that the friction disks 4.1-4.7 overlap in the center of the triangle that is formed by the shafts 2.1-2.3. The overlap of the friction disks 4.1-4.7 is defined by the ratio of disk diameter D to center distance A as follows: D/A > 1.45. The disks 3, 4.1-4.7, and 5 are mounted for corotation on the shafts 2.1# 2.2, and 2.3, so that the drive of the shafts 2.1# 2.2, and 2.3 causes the inlet disk 3, the friction disks 4.1-4.7, and the outlet disk 5 to rotate in the same direction. As shown in Figure 1, an inlet yarn guide 7 is provided on the inlet side, and an outlet yarn guide 8 on the outlet side for advancing a yarn 6 in the region of the overlap substantially in the center region of the equilateral triangle. The yarn 6 advances along a winding, helical path over the circumferential surfaces of the inlet disk 3, the friction disks 4.1-4.7, and the outlet disk 5. In this process, friction mechanisms acting between the yarn 6 and the circumferential surfaces of the friction disks 4.1-4.7 cause on the yarn 6 a false twist to develop, which propagates back in the yarn against the direction of its advance. On the outlet side, the false twist •unravels, and the yarn leaves the unit untwisted via the outlet yarn guide 8. The inlet disk 3 has a polished circumferential surface, so that the yarn is able to slide over the circumferential surface without any significant effect. In comparison with the friction disks 4.1-4.7, the inlet disk 3 may have a small CLT01/4657709vl Diameter. With that, the friction disk 3 assumes exclusively a guidance of the yarn. On the outlet side, the stack of the overlapping disks is defined by the outlet disk 5. Preferably, the outlet disk 5 has a relatively sharp-edged limited circumferential surface, so that after advancing over it, the yarn undergoes a certain spreading, which advantageously permits reducing a residual twist on the yarn. A further description of the effect that is produced on the yarn 6 by the friction disks 4.1-4.7, will follow in greater detail with reference to an embodiment of a friction disk. Figure 3 illustrates a friction disk as is used in the embodiment of Figure 1, with Figure 3.1 showing a cross sectional view of the friction disk and Figure 3.2 a side view thereof with a yarn advancing over it. The disk geometry is best seen in the illustration of Figure 3.1. The friction disk has a diameter D. The disk diameter D is selected as a function of the center distance between the shafts of the embodiment shown in Figure 1. For the currently common center distances of the art in an area of maximally 39.5 mm, the diameter D of the friction disk ranges from 54 mm to 62 mm. In this case, the friction disk has a width B ranging from 9.5 mm to 11.5 mm. The profile radius R on a circumferential surface 9 of the friction disk, which is preferably made symmetrical, forms with the disk width B the following ratio: B/R = 1.6 to 2.0 or 1.6 £ B/R £2.0. CLT01/4657709vl This permits a looping of the yarn, as it advances over the friction disk, which largely utilizes the available circumferential surface 9. The body 10 of the friction disk can be made of a ceramic, a plastic, preferably polyurethane, or an elastomer, preferably HNBR. Figure 3.2 schematically illustrates a situation, in which the friction disk rotates and a yarn 6 contacts the circumferential surface 9. In this process, the relative movement between the circumferential surface 9 of the friction disk and the yarn 6 triggers several friction mechanisms, which are largely defined by Eytelwein's laws and Euler's rope friction. Essential, however,is that the rotation of the friction disk produce on the yarn a tensile force FF and a transverse force FD. The tensile force FF that is active in the direction of the advancing yarn constitutes the so-called feed component. The transverse force FD that is active crosswise to the direction of the advancing yarn is largely responsible for imparting the twist to the yarn. Beyond the influence of the disk geometry on the feed component, it is also possible to influence the tensile force by means of the disk speed. Normally, the feed component becomes greater as the disk speed increases. It is common practice to choose for PES yarns a yarn tension ratio of the yarn tension on the outlet side to the yarn tension on the inlet side of the false twist device, which is smaller than one. Taking into account such ratios, it is thus essential for the production of crimped yarns- that in the texturing process by the false twist device, the produced tensile forces FF and transverse forces FD be within the predetermined ranges of magnitude. CLT0I/4657709vl The disk geometry of the present invention has made it possible to achieve an improved feed effect and with that a further reduction of the yarn tension with the same or an improved twist impartation. These advantages have been found not only for higher production speeds of more than 1,000 m/min, but also in the case of lower production speeds. In this connection, the speed level of the friction disks in the false twist device of the invention is below the rotational speeds for commercially available friction disks. In particular in the case of soft disks of polyurethane or elastomer, one can expect an increase in the service life with the use of friction disks according to the invention. In the embodiment of the false twist device according to the invention as illustrated in Figures 1 and 2, the number and the arrangement of the disks on the shafts are exemplary. It is possible to arrange in overlapping relationship more than seven or less than seven friction disks for treating a yarn. Likewise, the invention is not limited to the described disk materials. It would also be possible to make the disks of the false twist device of a metal. The selection, arrangement, and configuration of an inlet disk or an outlet disk are likewise exemplary. CLT01/4657709vl NOMENCLATURE 1 Bearing block 2. 2.2, 2.3 Shafts 3 Inlet disk 4. Friction disk 5 Outlet disk 6 Yarn 7 Inlet yarn guide 8 Outlet yarn guide 9 Circumferential surface 10 Disk body A Center distance B Disk width D Disk diameter FD Transverse force FF Tensile force R Profile radius CLAIMS 1. False twist device for false twisting a synthetic multifilament yarn (6), with a plurality of shafts (2.1, 2.2, 2.3) supported for rotation in a bearing block (1), which are each arranged at a center distance from one another in the configuration of a triangle, and with a plurality of friction disks (4.1...4.7), which are mounted in offset relationship on the shafts (2.1, 2.2, 2.3), and which have a disk diameter (D) of such a size that the friction disks (4.1...4.7) overlap in the center of the triangle and form a winding yarn path with their circumferential surfaces (9) , characterized in that the overlap of the friction disks (4.1...4.7) is determined by a ratio (D/A) of > 1.45 that is formed between the disk diameter (D) and the center distance (A), with the friction disks (4.1...4.7) having a disk width (B) in a range from 9.5 mm to 11.5 mm. 2. Device of claim 1, characterized in that the friction disks (4.1...4.7) have an identical disk diameter (D), which ranges from 54 mm to 56.5 mm with a center distance (A) of at most 37.5 mm between the shafts (2.1, 2.2, 2.3). 3. Device of claims 1 or 2, characterized in that the disk diameter (D) of the friction disks (4.1...4.7) ranges from 56 mm to 62 mm with a center distance (A) of at most 39.5 mm between the shafts (2.1, 2.2, 2.3). CLT01/4657709vl 4. Device of one of claims 1-3, characterized in that on their circumferential surfaces (9) the friction disks (4.1...4.7) have a profile radius (R) , which forms with the disk width (B) a ratio B/R in a range from 1.6 to 2.0. 5. Device of claim 4, characterized in that the profile radius (R) on the circumferential surfaces (9) of the friction disks (4.1...4.7) is made symmetrical with the disk width (B). 6. Device of one of the foregoing claims, characterized in that a total of seven friction disks (4.1...4.7) are mounted in overlapping relationship on the shafts (2.1, 2.2, 2.3) . 7. Device of one of claims 1-6, characterized in that the friction disks (4.1...4.7) are formed of a ceramic, a plastic, or an elastomer. 8. Friction disk for use in a false twist device according to one of claims 1-7, wherein the disk geometry is characterized by a disk diameter (D) in a range from 54 mm to 62 mm, a disk width (B) in a range from 9.5 mm to 11.5 mm, and a profile radius (R) on the circumferential surface (9), which forms with the disk width (B) a ratio B/R in a range from 1,6 to 2.0. 9. Friction disk of claim 8, CLT01/4657709vl characterized in that the profile radius (R) on the circumferential surface (9) of the friction body (10) is made symmetrical with the disk width (B). 10. Friction disk of claim 8 or 9, characterized in that the disk body (10) is formed of a ceramic, a plastic, or an elastomer. CLAIMS 1. False twist device for false twisting a synthetic multifilament yarn (6), with a plurality of shafts (2.1, 2.2, 2.3) supported for rotation in a bearing block (1), which are each arranged at a center distance from one another in the configuration of a triangle, and with a plurality of friction disks (4.1...4.7), which are mounted in offset relationship on the shafts (2.1, 2.2, 2.3), and which have a disk diameter (D) of such a size that the friction disks (4.1...4.7) overlap in the center of the triangle and form a winding yarn path with their circumferential surfaces (9) , characterized in that the overlap of the friction disks (4.1...4.7) is determined by a ratio (D/A) of > 1.45 that is formed between the disk diameter (D) and the center distance (A), with the friction disks (4.1...4.7) having a disk width (B) in a range from 9.5 mm to 11.5 mm. 2. Device of claim 1, characterized in that the friction disks (4.1...4.7) have an identical disk diameter (D), which ranges from 54 mm to 56.5 mm with a center distance (A) of at most 37.5 mm between the shafts (2.1, 2.2, 2.3). 3. Device of claims 1 or 2, characterized in that the disk diameter (D) of the friction disks (4.1...4.7) ranges from 56 mm to 62 mm with a center distance (A) of at most 39.5 mm between the shafts (2.1, 2.2, 2.3). CLT01/4657709vl 4. Device of one of claims 1-3, characterized in that on their circumferential surfaces (9) the friction disks (4.1...4.7) have a profile radius (R) , which forms with the disk width (B) a ratio B/R in a range from 1.6 to 2.0. 5. Device of claim 4, characterized in that the profile radius (R) on the circumferential surfaces (9) of the friction disks (4.1...4.7) is made symmetrical with the disk width (B). 6. Device of one of the foregoing claims, characterized in that a total of seven friction disks (4.1...4.7) are mounted in overlapping relationship on the shafts (2.1, 2.2, 2.3) . 7. Device of one of claims 1-6, characterized in that the friction disks (4.1...4.7) are formed of a ceramic, a plastic, or an elastomer. 8. Friction disk for use in a false twist device according to one of claims 1-7, wherein the disk geometry is characterized by a disk diameter (D) in a range from 54 mm to 62 mm, a disk width (B) in a range from 9.5 mm to 11.5 mm, and a profile radius (R) on the circumferential surface (9), which forms with the disk width (B) a ratio B/R in a range from 1,6 to 2.0. 9. Friction disk of claim 8, CLT01/4657709vl characterized in that the profile radius (R) on the circumferential surface (9) of the friction body (10) is made symmetrical with the disk width (B). 10. Friction disk of claim 8 or 9, characterized in that the disk body (10) is formed of a ceramic, a plastic, or an elastomer.

Documents:

1347-CHENP-2006 ABSTRACT.pdf

1347-CHENP-2006 CLAIMS GRANTED.pdf

1347-CHENP-2006 CORRESPONDENCE OTHERS.pdf

1347-CHENP-2006 CORRESPONDENCE PO.pdf

1347-CHENP-2006 FORM-18.pdf

1347-CHENP-2006 FORM-2.pdf

1347-CHENP-2006 PCT.pdf

1347-chenp-2006-abstract.pdf

1347-chenp-2006-claims.pdf

1347-chenp-2006-correspondnece-others.pdf

1347-chenp-2006-description(complete).pdf

1347-chenp-2006-drawings.pdf

1347-chenp-2006-form 1.pdf

1347-chenp-2006-form 26.pdf

1347-chenp-2006-form 3.pdf

1347-chenp-2006-form 5.pdf

1347-chenp-2006-pct.pdf