EP1664406B1 - False-twisting device - Google Patents

Description

The invention relates to a false twist device for false twisting a synthetic thread according to the preamble of claim 1.

In the production of crimped textile threads, it is known to produce a friction-induced false twist on the threads, which is fixed in a texturing zone by thermal treatment in the filaments of the thread. To produce the false twist, in particular false twist devices have proved successful, in which the thread is guided on the circumferential surfaces of rotating and overlapping friction disks. Such a Faschdrallvorrichtung is for example from the EP 0 943 022 B1 known.

In the known false twist device, the friction discs are arranged on three shafts, which are rotatably supported on a bearing block. The shafts are arranged at a distance from each other to a triangle in such a way that the friction discs in the center of the triangle overlap. The shafts are driven by a drive such that the friction discs rotate at a substantially constant peripheral speed. To produce the false twist, the thread is guided in the center on the peripheral surfaces of the friction discs, so that forms a convoluted threadline. Here, the thread is guided in an oblique barrel over the peripheral surfaces of the friction discs. The friction mechanisms acting between the thread and the circumferential surface of the friction discs cause a pulling force to convey the thread and a transverse force to twist the thread to be produced on the thread. The ratio between the tensile force to convey the thread and the lateral force to twist the thread depends essentially on the geometry of the disc and the degree of overlap of the discs. In general, it is true that with increasing conveying effect can be textured thread-saving. A larger promotional effect can be However, often only at the expense of a reduced twisting reach. Therefore, there is a desire that the conveying action and twisting action generated by the false twisting unit are in a favorable relationship with each other.

However, it can be observed that an increasing conveying effect can only be achieved at the expense of decreasing twisting. So is one of the WO 99/51804 known false twist device proposed to guide the thread with a predetermined pitch angle or overflow angle over the peripheral surfaces of the friction discs. In particular, a flatter overflow angle compared with the prior art was found to be advantageous for achieving high production speeds. By the proposed shallower overflow angle is achieved that the contact length between the thread and the peripheral surface of the friction disc is increased, so that the friction conditions lead to an increase in the tensile force, but with the great disadvantage that the force component to produce a twisting environment is reduced. This disadvantage is exacerbated by the fact that the largest possible profile radius in the range of 6.5 to 8 mm is chosen for a ratio to the disk width of the friction disk, which inevitably results in low angles of wrap.

It is therefore an object of the invention to realize a false twist device for false twisting a synthetic thread of the generic type such that even at hollow production speeds a gentle thread treatment at maximum twisting is possible.

Another object of the invention is to provide a disc geometry of the friction discs for a generic false twist device, with which regardless of the thread type, an optimum between the promotion of the thread and the twisting of the thread is achieved.

This object is achieved by a false twist device with the features of claim 1 and by a friction disc with the features of claim 8.

Advantageous developments of the invention are defined by the features and feature combinations of the respective subclaims.

The invention proceeds to a new approach, which is based on the fact that the friction discs have the largest possible disc diameter. Considered by itself, with enlargement of the disk diameter of the friction disks, a reduction in the peripheral speed of the friction disks and thus a reduction in the twisting action would be achieved. On the other hand, however, the thread overflow on the circumferential surface of the friction disk is changed to such an extent as the disk diameter increases to increase the proportion of the conveying action. Surprisingly, it was found that despite increased disc diameter while maintaining a certain disc width and maintaining a minimum overlap of the functional discs, the loss of twisting is compensated, so that despite high production speeds sets a thread-preserving maximum twist setting on the thread. The overlap of the friction discs is determined by a ratio formed between the disc diameter and the axial distance of the shafts, which is above the value of 1.45. In this case, the friction discs have a disc width in the range of 9.5 mm to 11.5 mm The ratio formed from the disc diameter and the center distance is limited at the top by the fixed axis distance of the shafts. Furthermore, it has been found that friction discs with a disc width in the range of below 9.5 mm led to an undesired twist decrease. By contrast, with friction discs having a disc width of more than 11.5 mm, more than sufficient swirl can be generated, but with the disadvantage of a too low conveying effect.

In the case of the generally customary axle spacings of the shafts, the abovementioned advantages can be achieved by the friction disks according to the invention, wherein the friction disks have a geometry with a wheel diameter in the range from 54 mm to 62 mm, a wheel width in the range from 9.5 mm to 11.5 mm and a profile radius on the peripheral surface of the friction disk forming a ratio in the range of 1.6 to 2.0 with the disk width.

Depending on the size of the center distance between the shafts, for a center distance of max. 37.5 mm, the friction disks with disc diameters of the same size, in which the disc diameter was in the range of 54 mm to 56.5 mm, proved particularly suitable. For larger center distances of max. 39.5 mm was the preferred range of friction discs in the diameter of 56 mm to 62 mm.

To set the largest possible angle of wrap on the peripheral surfaces of the friction discs is further proposed to form the friction discs with a profile radius at the peripheral surfaces, which forms a ratio in the range of 1.6 to 2.0 with the disc width.

Here, the profile radius is preferably formed symmetrically on the peripheral surface of the friction discs, so that the inlet and the outlet of the thread is kept equal to the peripheral surface of the friction discs.

Furthermore, it has been found that a maximum power can be achieved by keeping a total of seven friction disks overlapping one another on the shafts. An increase in the number of friction discs showed no improvement in performance.

The friction discs may in this case be formed from a ceramic, an elastomer or a plastic. Regardless of the choice of material result in particular for all soft materials advantageous extension of the operating time.

An embodiment of the false twist device according to the invention is described below with reference to the accompanying drawings.

Fig. 1

schematisch eine Ansicht des Ausführungsbeispiels der erfindungsgemäßen Falschdrallvorrichtung,

Fig. 2

schematisch eine Draufsicht des Ausführungsbeispiels aus Fig. 1,

Fig. 3

schematisch eine Querschnittsansicht einer Friktionsscheibe des Ausführungsbeispiels aus Fig. 1 und

Fig. 4

schematisch eine Seitenansicht der Fig. 3.

They show:

Fig. 1

1 is a schematic view of the embodiment of the false twist device according to the invention;

Fig. 2

FIG. 2 is a schematic plan view of the embodiment of FIG. 1; FIG.

Fig. 3

schematically a cross-sectional view of a friction disk of the embodiment of Fig. 1 and

Fig. 4

schematically a side view of Fig. 3rd

In Fig. 1 and Fig. 2, a first embodiment of the false twist device according to the invention is shown schematically. Fig. 1 shows the false twist device in a perspective view and in Fig. 2, the false twist device is shown in a plan view. The following description applies to both figures, insofar as no explicit reference is made to one of the figures.

The false twist device has a bearing block 1. On the bearing block 1 several waves 2.1, 2.2 and 2.3 are supported rotatably projecting. The shafts 2.1, 2.2 and 2.3 are coupled with their bearing end with a drive, not shown here. Such a drive is for example from the EP 0 744 480 A1 known. In that regard, reference is expressly made to the contents of the cited reference at this point.

The waves 2.1, 2.2 and 2.3 are arranged in a triangle. At the shafts 2.1, 2.2 and 2.3 a plurality of friction discs 4.1 to 4.7 are arranged offset from one another. In detail, the shaft 2.1 in the thread running direction at a distance from each other an inlet disc 3 and two friction discs 4.3 and 4.6. The second shaft 2.2 has a first friction disk 4.1 disposed immediately below the intake disk 3 and the further friction disks 4.4 and 4.7 at a distance. The third shaft 2.3 has, in the direction of yarn travel, a first friction disk 4.2, which is arranged between the friction disks 4.1 and 4.3. At a distance from the friction disk 4.2 is followed by a further friction disk 4.5, which is arranged between the friction disks 4.4 and 4.6. At the end of the shaft 2.3 carries an outlet disc. 5

As shown in Fig. 2, the shafts 2.1, 2.2 and 2.3 are each arranged with a same center distance A to each other to the triangle. The friction disks (not shown in FIG. 2, the intake disk 3) have such a large disk diameter D that the friction disks 4.1 to 4.7 overlap in the center of the triangle formed by the shafts 2.1 to 2.3. The overlap of the friction disks 4.1 to 4.7 is defined here by the ratio between disk diameter D to center distance A as follows: $$\mathrm{D}\mathrm{/}\mathrm{A}\mathrm{>}\mathrm{1}\mathrm{.}\mathrm{45}$$

The discs 3, 4.1 to 4.7 and 5 are rotatably connected to the shafts 2.1, 2.2 and 2.3, so that drive the shafts 2.1, 2.2 and 2.3, the inlet disc 3, the friction discs 4.1 to 4.7 and the outlet disc 5 rotate in the same direction.

As shown in Fig. 1, on the inlet side, an inlet yarn guide 7 and on the outlet side a discharge yarn guide 8 is provided to a yarn 7 in the overlapping region substantially in the region of the center of the equilateral Triangle to lead. The thread 6 is guided in a helical helical thread run along the peripheral surfaces of the inlet disk 3, the friction disks 4.1 to 4.7 and the outlet disk 5. In this case, due to the friction mechanisms acting between the thread 6 and the circumferential surfaces of the friction discs 4.1 and 4.7, a false twist builds up on the thread 6, which replicates itself against the thread running direction in the thread 6. On the outlet side of the false twist is resolved and the thread leaves ungrodded via the outlet yarn guide 8 the unit.

The inlet disc 3 has a polished peripheral surface, so that the thread can slide over the peripheral surface without significant effect. In relation to the friction disks 4.1 to 4.7, the inlet disk 3 may have a small disk diameter. Thus, the inlet pulley 3 assumes only a thread guide.

The disk stack of the overlapping disks is limited on the outlet side by the outlet disk 5. The outlet disc 5 is preferably designed with a relatively sharp-edged limited peripheral surface, so that after overrunning the thread receives a certain spreading. This can advantageously a residual twist on the thread can be reduced.

A further description of the effect on the yarn 6 produced by the friction disks 4.1 to 4.7 will be explained below with reference to an exemplary embodiment of a friction disk.

In Fig. 3 and 4, a friction disc is shown, as used in the embodiment of FIG. 1. Here, the friction disk is shown in Fig. 3 in a cross-sectional view and in Fig. 4 in a side view with overflowing thread.

The disk geometry can be taken from the representation shown in Fig. 3 here. The friction disc has a pulley diameter D. The pulley diameter D is to be selected as a function of the axial distance between the shafts of the embodiment shown in FIG. For the currently used in the prior art center distances in the range of max. 39.5 mm, the disk diameter D of the friction disk is in the range of 54 mm to 62 mm. The friction disk has a disk width B in the range of 9.5 to 11.5 mm. The profile radius R on the peripheral surface 9 of the friction disk, which is preferably symmetrical, forms the following relationship with the disk width B: $$\mathrm{B}\mathrm{/}\mathrm{R}\mathrm{=}\mathrm{1}\mathrm{.}\mathrm{6}\mathrm{to}\mathrm{2}\mathrm{.}\mathrm{0}\mathrm{bzm}\mathrm{,}\mathrm{1}\mathrm{.}\mathrm{6}\mathrm{\le }\mathrm{B}\mathrm{/}\mathrm{R}\mathrm{\le }\mathrm{2}\mathrm{.}\mathrm{0}$$

Thus, a looping of the thread is achieved in overflow over the friction disk, which largely exploits the available peripheral surface 9.

The disk body 10 of the friction disk can in this case be formed of a ceramic, a plastic, preferably of polyurethane, or of an elastomer, preferably HNBR.

FIG. 4 schematically shows the situation in which the friction disk rotates and a yarn 6 contacts the peripheral surface 9. Here, by the relative movement between the peripheral surface 9 of the friction disk and the thread 6 several friction mechanisms are triggered, which are defined essentially by the Eytelwein laws and the Euler rope friction. However, it is essential here that a tensile force F _F and a transverse force F _{D are} generated on the yarn by rotation of the friction disk. The tensile force F _F acting in the running direction of the thread 6 represents the so-called conveying component. The transverse force F _D acting transversely to the thread running direction is decisively responsible for the twisting of the thread. Beyond the influence of the disk geometry on the conveyor component, the traction over the Slice speed can be influenced. As a rule, the delivery rate increases with increasing disc speed. In practice, it is common for PES filaments to select a thread tension ratio of thread tension outlet side to thread tension inlet side of the false twist device, which is less than one. Taking into account such conditions, it is therefore essential for the production of crimped threads that the tensile forces generated in the texturing process by the false twist device F _F and transverse forces F _{D are} within the predetermined size ranges.

Due to the disc geometry according to the invention an improved conveying effect and thus a further reduction of the thread tension could be achieved with the same or improved twisting. These advantages have not only for larger production speeds of above 1,000 m / min. but could also be detected at lower production speeds. Here, the speed level of the friction discs of the false twist device according to the invention is below the speeds for commercially available friction discs. In particular, in soft wheels of polyurethane or elastomer is to be expected when using the friction discs according to the invention with an increase in life.

In the embodiment of the false twist device according to the invention shown in FIGS. 1 and 2, the number and arrangement of the discs on the shafts are exemplary. Thus, more than seven or less than seven friction disks may be overlapped to handle a yarn. Likewise, the invention is not limited to the disc materials mentioned, so the discs of the false twist device could also be made of metal. The choice, arrangement and design of an inlet disc or an outlet disc is also exemplary.

LIST OF REFERENCE NUMBERS

1

bearing block

2.1,2.2,2.3

waves

3

inlet disc

4.1 ... 4.7

friction disc

5

outlet disc

6

thread

7

Inlet yarn guide

8th

Outlet yarn guide

9

peripheral surface

10

washer body

A

Wheelbase

B

wheel width

D

Disc diameter

F _D

lateral force

F _F

traction

R

profile radius

Claims (10)

1. False twist device for false twisting a synthetic 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 (A) 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).
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,
   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.

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