FR2542019A1 - Friction false-twist device - Google Patents

Abstract

The invention relates to a friction false-twist device. According to the invention, two rotating spindles 5 and 6 are equipped with working discs 2, 4 having a high coefficient of friction, and a third spindle 3 is equipped with one or more yarn-guide discs 1 having a low coefficient of friction. The invention can be used for the crimping of yarns made of synthetic material.

Description

 The invention relates to a frictional false-twist device for crimping synthetic yarns, which has three pins, mounted so that they can rotate, and each provided with at least one friction disc, the thread passing between the discs. friction along a zigzag path.

 Until now, an ideal condition for false twisting of a wire was considered to be an equilateral triangle arrangement, in which the angles of passage of wire on the disc are kept as equal as possible.

In this case, the overlapping area of the three discs is always formed of working discs. To stabilize and balance the wire, wire guide discs are often available at the entry or exit of the group (see DE-AS 23 45 128 and
DE-OS 26 58 034).

 For certain threads, it is true that these thread guide discs favor the movement of the thread, but they have no influence on the overlapping area, nor therefore on the angle of entanglement of the thread at the working discs, pui-squ 'they are fixedly arranged inside the equilateral triangle. There is no setting or possible movement of a disc set.

 In another document (EP-A 00 12 625), an arrangement of the discs is indicated which, thanks to working discs of different thicknesses, allows different angles (59 to 70). The disadvantage is not only that this arrangement is only as advantageous for well-defined wires and cannot be adjusted in a variable manner; but in addition the three discs are still all located in an invariable equilateral triangle. For different wires, always choose new combinations of discs, and change the assembly, which represents a big expense.

 It has appeared in practice that, especially in the case of yarns with a large number of filaments, even using guide discs, it is not possible to balance or stabilize the yarn in the group, at withdrawal speeds greater than 600 m / min, and you can't get usable wire.

 The object of the invention is to eliminate the drawbacks indicated.

 The device according to the invention is characterized in that two spindles are fitted with working discs (friction discs with a high coefficient of friction), while the third spindle has only one or more thread guide discs (friction discs low coefficient of friction). Advantageous embodiments are described below.

 Thanks to the arrangement of the two spindles which are only equipped with working discs, the wire undergoes enough rotations. The thread guide discs which penetrate between the working discs stabilize the thread on the whole group. As the thread guide discs can be adjusted relative to the working discs according to the threads to be treated, the thread undergoes a very large, but gentle rotation and it acquires optimal resistance Since the thread is not subjected to a strong twist that by two working discs, and that it is stabilized on the thread guide discs, very high withdrawal speeds are possible. This occurs with all combinations of discs provided by the invention.

 Another advantage lies in the fact that it is possible to obtain different entanglement angles thanks to different diameters of the wire guide discs, the working discs retaining their original diameter. In this eas, again, the third spindle only carries thread guide discs.

 By way of example, several embodiments of the invention have been described below and illustrated diagrammatically in the accompanying drawing.

 Figure 1 is a bottom view of a frictional false twist apparatus according to the invention in which the wire guide disc spindle is arranged to pivot, the spindle being shown in engagement.

Figure 2 shows the device of Figure 1 in the open position where the wire can be inserted
Figure 3 shows a front view of 11 apparatus of Figures 1 and 2
FIG. 4 illustrates the possibility of sliding of the guide discs relative to the sets of working discs
FIG. 5 shows an arrangement in which the thread guide discs give, by a modification of the diameters, another value of the entanglement angle or of the passage angle on the working discs.

As can be seen in Figures 1, 2 and 3, the disc set 1 is the guide disc set it, which is fixed on the spindle 3. The disc sets 2 and 4 are working discs, which are fixed on pins 5 and 6. By means of the adjustment button 7, the thread guide discs 1 can be brought into any positions relative to the working discs 2 and 4, that is to say that one can adjust and vary the overlap and the entanglement angle depending on the wire used. The device is driven, in known manner, by a tangential belt 8 More details on this subject can be found in the patent application in the Federal Republic from Germany which the applicant has filed under No. P 31 47 088.2
In Figure 4, the spindle 3, provided with the wire guide discs 1, is shown in two positions, which ensure a different overlap of the friction discs.

 As can be seen in FIG. 5, by giving different diameters to the wire guide discs 1, a variable entanglement angle of the working discs 2 and 4 is also obtained by the wire.

 On the other hand, according to the present invention, the working discs can be formed, in their region of contact with the wire, in a soft material, for example in polyurethane, or else with a diamond coating, or even in another hard material, for example ceramic or a material deposited with a plasma gun.

 The wire guide discs may, in their region of contact with the wire, be chromed, or be made of a material having a coefficient of friction significantly lower than that of the working discs.

Claims (9)

 1. Frictional false-twist apparatus for crimping plastic threads, comprising three pins mounted so that they can rotate, and each provided with at least one friction disc, the wire passing between the friction discs along a path zigzag, device characterized in that two spindles (5 - 6) are equipped with working discs (2 4) (friction discs with high coefficient of friction), while the third spindle (3) has only one or more thread guide discs (1) (friction discs with low coefficient of friction).  2. Apparatus according to claim 1, characterized in that the third pin (3) is arranged so as to be able to pivot or slide, so that the zigzag trajectory and, consequently, the entanglement of the wire can be modified.  3. Apparatus according to claim 2, characterized in that the modification of the embracing is obtained by means of thread guide discs (1) of different diameters  4. Apparatus according to claim 3, characterized in that, in the case of several working discs (2, 4) per spindle, a thread guide disc (1) is associated with each pair of working discs (2, 4).  5. Apparatus according to claim 1, characterized in that the working discs are formed, in their region of contact with the wire, of a soft material, for example polyurethane.  6. Apparatus according to claim 1, characterized in that the working discs (2, 4) have, in their region of contact with the wire, a diamond coating  7. Apparatus according to claim 1, characterized in that the working discs (2, 4) are constituted, at least in their region of contact with the wire, by a hard material, for example in cemaric or in a deposited material with a plasma gun.  8. Apparatus according to claim 1, characterized in that the wire guide discs (1) are chrome-plated in their region of contact with the wire.  9. Apparatus according to claim 1, characterized in that the yarn guide discs (1) has, t in their region of contact with the yarn, a material having a coefficient of friction significantly lower than that of the discs work (2, 4).