Process and device to piece back to a spinning device operating

Details Process and device to piece back to a spinning device operating Process and device to piece back to a spinning device operating

1987-07-10

1989-07-11

Petrakes, John

Textiles: spinning, twisting, and twining

Apparatus and processes

Piecing up

57328, D01H 1500, D01H 528

Patent

active

048459364

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION

The instant invention relates to a process for piecing back to a spinning device operating with a pneumatic torsion element in which a yarn which is fed back to a drafting mechanism is brought together with a roving, as well as to a device to carry out the process.
In a known process of this type the pair of intake rolls of the drafting mechanism is stopped for the purpose of piecing back when a yarn breakage occurs, so that the roving or the fiber sliver is opened in the drafting zone which follows this pair of intake rolls (DE-OS 3,411,577 and 3,413,894 corresponding with U.S. Pat. Nos. 4,550,560 and 4,545,193, respectively). When the fiber sliver or the roving is fed back to the torsion element for piecing, an irregularity is produced which must be removed from the finished yarn in a further step.
It is therefore the objective of the instant invention to create a process and a device which makes it possible to produce an unobtrusive piecing joint with little expenditure.
This objective is achieved according to the invention in that the roving, after being stopped, is at first released for the piecing process and in that the forward end of the roving which is leaving the drafting mechanism is sucked away until the roving segment which has remained in the drafting mechanism during the prior stoppage of the roving has been taken away, and in that the roving is subsequently fed to the torsion element while being simultaneously brought together and combined with the yarn end. Due to the stoppage of the roving or of the fiber sliver said roving or said fiber sliver is not only discontinued, but its forward end is given an irregular shape which is unsuitable for piecing. Therefore the removal of this affected forward end of the roving or sliver ensures that in piecing a segment with unaffected fiber orientation and length is fed to the torsion element to be combined with the yarn. In this way, even and unobtrusive piecing joints are obtained.
In the sense of the instant invention, roving is understood to be any sliver-like material which can be fed to the torsion element by means of a drafting mechanism, regardless of whether it has little torsion or not. Not only flyer rovings but also card slivers etc. fall therefore into this category.
In order to coordinate the re-starting of yarn torsion in a particularly simple manner with the beginning of yarn draw-off, whereby the length of the piecing joint can be predetermined precisely, it is preferable to draw off the yarn at first through the torsion element without it exerting any twisting action upon the yarn, whereby furthermore, in function of the position of the end of the yarn previously fed-back, the removal of the roving is ended and the feeding of the roving to the torsion element is started, roving and yarn now being submitted together to the twisting effect which now begins.
It is basically sufficient if the yarn and the stretched roving are allowed to run together into the twisting nozzle. However, the longer the common conveying path of roving and yarn between drafting mechanism and torsion element, the better the piecing joint. For this reason provisions can be made in a preferred embodiment of the inventive process for the yarn to be introduced laterally into the closed clamping line of the two output rolls and to be fed necessarily to the torsion element at the speed determined by the rotational speed of the two output rolls.
To prevent the injector effect in the torsion element from provoking uncontrolled draw-off of the yarn after the feeding of compressed air is resumed provisions are made in a preferred version of the process for the yarn which is brought together with the roving to be retained pneumatically and to be furthermore braked mechanically upon resumption of yarn draw-off until part of it is brought together with the roving. The yarn is thus drawn off at a draw-off speed which is dictated mechanically by the winding device or by a pair of draw-off rolls. Beyond this, the yarn in the process of

REFERENCES:
patent: 4457130 (1984-07-01), Sakai et al.
patent: 4503662 (1985-03-01), Horiuchi et al.
patent: 4517794 (1985-05-01), Sakai et al.
patent: 4543776 (1985-10-01), Seiki et al.
patent: 4545193 (1985-10-01), Tanaka et al.
patent: 4550560 (1985-11-01), Tanaka et al.
patent: 4620413 (1986-11-01), Anahara

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