US3805505A

US3805505A - Thread drawoff tube construction for open end spinning machines

Info

Publication number: US3805505A
Application number: US00277367A
Authority: US
Inventors: F Schuster
Original assignee: Schubert und Salzer Maschinenfabrik AG
Current assignee: Rieter Ingolstadt Spinnereimaschinenbau AG
Priority date: 1971-08-11
Filing date: 1972-08-02
Publication date: 1974-04-23
Anticipated expiration: 1991-04-23
Also published as: IT963569B; FR2148503A1; FR2148503B1; CS167995B2; GB1365206A; JPS4827032A; CH535294A; ES405561A1; DE2140157B2; DE2140157A1

Abstract

The inner end of the cylindrical passage through the thread drawoff tube flares outwardly toward the fiber collection chamber. The flared portion includes a smooth margin adjacent to the inner tube end and a grooved region spaced from the inner tube end. The grooved region includes equidistantly spaced long longitudinal grooves in the passage surface and intermediate short longitudinal grooves between the divergent end portions of the long grooves. Circumferential grooves in the passage surface intersect the radial plane grooves. In cross section, the grooves have a depth equal to at least one-half of the full diameter of the thread being drawn off. The plane of at least one groove sidewall intersects the principal passage surface at an angle between 45* and 90*.

Description

United States Patent 191 Schuster [451 Apr. 23, 1974 THREAD DRAWOFF TUBE CONSTRUCTION FOR OPEN END SPINNING MACHINES [75] Inventor: Friedrich schusterfllainmelburg,

Germany [22] Filed: Aug. 2, 1972 [2]] App]. No.: 277,367

[30] Foreign Application Priority Data Jansen 57/76 Verschragen 57/76 Primary Examiner.lohn Petrakes Attorney, Agent, or Firm-Robert W. Beach; Ms. R. M. Van Winkle [5 7] ABSTRACT The inner end of the cylindrical passage through the thread drawoff tube flares outwardly toward the fiber collection chamber. The flared portion includes a smooth margin adjacent to the inner tube end and a grooved region spaced from the inner tube end. The grooved region includes equidistantly spaced long 1ongitudinal grooves in the passage surface and intermediate short longitudinal grooves between the divergent end portions of the long grooves. Circumferential grooves in the passage surface intersect the radial plane grooves. In cross section, the grooves have a depth equal to at least one-half of the fulldiameter of the thread being drawn off. The plane of at least one groove sidewall intersects the principal passage surface at an angle between 45 and 90.

3 Claims, 4 Drawing Figures Aug. 11, 1971 Germany 2140157 g u.s. q. 57/5. 8 9 57 /l 06 [51] Int. Cl D01h 1/12 8] Field of Search 57/58.89, 58.95, 34 CP, 57/76, 106

[56] References Cited UNITED STATES PATENTS 3,481,128 12/1969 Landwehrkamp et al. 57/58.89 2,052,731 9/1936 Taylor 57/76 THREAD DRAWOFF TUBE CONSTRUCTION FOR OPEN END SPINNING MACHINES The present invention relates to a thread drawoff tube for an open end spinning device which includes a grooved portion in the drawoff passage.

It is well known to toughen the mouth of a drawoff tube passage for an open end spinning machine, such as by grooves, in order to impart a false twist to thread drawn through the tube, such as disclosed in Swiss Pat.

No. 398,395, and French Pat No. 1,468,321. Such construction permits thread to be drawn off at substantially higher speeds than when the drawoff passage has a smooth surface.

It is a principal object of the present invention to improve the formation of false twist by the drawoff tube.

Another important object is toenable the drawoff speed to be further substantially increased and thereby to increase the spinning performance of the machine.

should be of a depth equivalent to at least the radius of the thread being drawn through the tube. To prevent interference with rolling of the thread from the grooves onto the principal passage surface while attaining the optimum distribution of false twist imparted to the thread, the sidewall of each longitudinal groove over which the thread must roll to climb out of the groove is sloped so that the groove wall angle is greater than 45.

FIG. I is a vertical axial section through an open end spinning machine having a drawoff tube constructed in accordance with the present invention.

FIG. 2 is a bottom plan of the drawoff tube. 7

FIG. 3 is a cross section through a portion of the drawoff tube wall showing one configuration of a passage. groove, and

FIG. '4 isa similar view showing'a modified groove configuration.

A housing 1 closed by a cover 11 contains a spinning turbine 2 having a fiber collection trough24. Fiber is fed to such trough from'a sliver S by a fiber supply device, shown as feed rolls 5, and a supplytube 51 extending through the housingcover. The fiber is drawn as a thread F from the collection trough 24 through a drawoff tube 6 by drawoffrollers 3. The thread drawoff tube 6 includes an upper cylindrical passage 63 having a lower end portion 60 flared toward the lower. passage mouth. The internal passage surface of .the flared portion 601 has a smooth margin 600 adjacent to the lower passage mouth and a grooved portion 601 above such smooth margin. For spinning of short staple fibers, the thread F is pulled from the collection trough 24 past the smooth margin 600 to the grooved portion 60l, where the linear travel of the thread stretch engaged with passage portion 601 is momentarily stopped by frictional engagement while the trailing thread end continues to rotate so that a false twist is imparted to the thread. The smooth surface 600 damps the vibrational effect on the thread created by the change in velocity of the thread portion in the passage, so that such vibration is not translated to the thread end in the collection trough, which transmission might result in separation of the thread end from the fiber in the trough. The smooth damping surface is not necessary for spinning long staple fibers.

In prior open end spinning devices, the distribution of false twist along spun thread has been improved by providing a passage portion having longitudinal grooves in the passage surface, usually disposed in radial planes. According to the present invention, experiments have shown that the false twist distribution can be further improved by providing longitudinal grooves 7 intersected by circumferential grooves 70. The combination of intersecting longitudinal grooves 7 and circumferential grooves permits the thread drawoff speed to be increased substantially, such increase being as great as 50 per cent, depending on the type of fiber being spun and the rotational speed of the spinning turbine. It is desirable to have the longitudinal grooves approximately equally"spaced,. but, because the lower tube portion is flared, the grooves tend to diverge downwardly. Consequently, shorter longitudinal grooves 71 are provided between the divergent end portions of grooves 7, as shown in FIG. 2.

Whilethe twist is imparted by the momentary lodging of the threadin the grooves 7 and 71, such thread portions must again roll circumferentially out of the grooves, as indicated, by arrow P in FIG. 3, onto the principal surface 6l 'of the passage. Experiments have shown that thread F will roll out of the grooves before excessive tension is placed on the thread pulled in opposition to the restraint of thegrooves if the groove depth t, indicated in FIG. 3,, is at least one-half the thread diameter d and, preferably, not greater than the full diameter of the spun thread F.

While the depth -t of grooves 7 and 71 determines the ability of the thread to roll out of the grooves in the direction of arrow P onto the principal surface 61, the opposingforce tending to hold the thread in the groove is determined by the groove wall angle or, shown in FIGS. 3 and 4. The groove wall angle is the angle between the outwardly extende'dplane of that groove sidewall over which the thread F rolls out of the-groove and the portion of jsurface 61 adjacent to such wall. Such groove wall angle is the supplement of the groove corner angle over which the thread rollsout of the groove. The optimum force for holding the thread in the groove, and thereby producing a good false twist distribution, is created when the groove wall angle a is greater than 45, and, more particularly, when the angle is between 45 and The groove configuration shown in FIG. 3 is suitable for a spinning machine in which the relative rotation of the drawoff tube 6 and the spinning chamber 2 is always in the same direction, so that the circumferential movement of the thread F within tube 6 will always be in the direction of arrow P. The groove configuration shown in FIG. 4 permits the twisting force to be exerted on the thread in either direction because both groove walls form angles a greater than 45. A drawoff tube having the groove construction. of FIG. 4 can be used in a'spinning machine in which the circumferential rolling force on the thread F is either clockwise or counterclockwise.

As indicated by FIGS. 3 and 4, the grooves can have various cross-sectional shapes and depths, and the spacing between adjacent grooves may be varied, but the critical minimum depth and range of angles a must be observed to produce the most efficient machine operation. The flared tube mouth 60 may also be varied in size and configuration without disadvantageously affecting the performance of the twist-imparting zone 601. The circumferential grooves 70 also may have various cross-sectional profiles, but it is preferred that the depth of such grooves be substantially the same as the depth of the grooves 7 and 71. While the increased effectiveness of the twist zone 601 created by the particular improvements described above has been determined experimentally, it is probable that these results are produced by the increased number of thread contact points which exert a greater holding force on the thread F. Since the degree of twisting restraint is also increased by steep groove walls, it is preferred that the sidewall angle of grooves 70 be greater than 45, which also sharpens the corners formed by the intersections of grooves 70 with grooves 7 and 71.

It has also been found that a twisting zone formed in accordance with the present invention will effect good binding of the fiber ring in collection trough 24 to the trailing end of thread F even with a very small rotational speed of spinning turbine 2, so that, if desired, spinning can be accomplished at lower speeds than have heretofore been practical.

I claim:

1. A thread drawoff tube for open end spinning machines, said tube having an inner passage wall, such wall having a grooved thread-engaging surface, wherein the improvement comprises a plurality of grooves having their lengths extending longitudinally and spaced circumferentially in the passage wall, and a plurality of longitudinally spaced circumferential grooves intersecting said longitudinal grooves.

2. The drawoff tube defined in claim 1, in which the depth of each longitudinal groove is at least as great as the radius of the thread drawn through the tube.

3. The drawofi tube defined in claim 1, in which the thread is movable circumferentially of the tube passage, and the plane of the forward sidewall of each longitudinal groove in the direction of thread movement intersects the plane of the inner passage wall portion at a groove wall angle greater than 45.

Claims

3. The drawoff tube defined in claim 1, in which the thread is movable circumferentially of the tube passage, and the plane of the forward sidewall of each longitudinal groove in the direction of thread movement intersects the plane of the inner passage wall portion at a groove wall angle greater than 45*.