Textiles: spinning – twisting – and twining – Apparatus and processes – Covering or wrapping
Reexamination Certificate
2000-03-13
2001-11-20
Calvert, John J. (Department: 3741)
Textiles: spinning, twisting, and twining
Apparatus and processes
Covering or wrapping
C057S075000, C057S328000, C019S244000
Reexamination Certificate
active
06318060
ABSTRACT:
The invention relates to a method for producing core yarn in which a sliver (fiber slubbing) is refined in a drafting frame before it is stabilized by twisting and then fed to a core yarn which is embedded in covering fibers. The invention relates further to a spinning machine for producing core yarns and having a drafting frame which supplies a fiber slubbing, with a device for feeding the core yarn and a device for twisting and winding up the core yarn.
The production of core yarn is characterized in that in the formation of the yarn and especially upon its drafting to a predetermined fineness and its stabilization by twisting, a core thread is laid into the fiber slubbing and has cover fibers spun around it so that the core thread in the best case is no longer visible. The core thread determines thereby substantially the strength and elongation of the generated yarn while cover fibers above all determine the hand and visual appearance of the yarn. The core threads as a rule are endless synthetic threads while the cover fibers are usually natural staple fibers like cotton and wool.
In a core yarn it is intended that the core thread be embedded as completely as possible in the cover fiber which determines the external appearance. In normal core yarn spinning, this is achieved in that the core thread is fed into the fiber slubbing as a rule in the last and thus the main drafting field while the cover fibers are laid around the core thread by the twisting of the fiber band between the output roller pair [of the drafting frame] and the element from which the twist arises, as a rule a ring spinning spindle. This embedding is effected rather incompletely at numerous locations along the yarn which results in a reduction in quality of the generated core yarn.
It is the object of the invention to improve this embedding of the core thread in the cover fiber. This is achieved by features given in the corresponding clause of the main claim. With these features, the embedding of the core yarn in the cover fibers is supported by a compaction in addition to a twisting so that, in effect, there are fewer gaps and over the length of the yarn a more uniform covering of the core thread by the cover fibers.
The arrangement can be so made that the fiber slubbing supplied by the drafting frame or in the case of a plurality of fiber slubbings supplied by the drafting frame at least one of these fiber slubbings before the output from the main drafting field or at the input to the compaction zone is met by a core thread, the core thread and fiber slubbing being compacted together, and finally subjected to twisting to form the core yarn. A plurality, especially two fiber slubbings are supplied by the drafting frame in the case of production of false twist.
An apparatus for carrying out this process has at the output of a drafting frame a compaction device maintained under suction which is formed with a perforation row, i.e. a row running in the direction of movement of the fiber slubbing of small suction orifices toward which the fibers of the fiber slubbing are sucked. Compaction devices in the form of rotating cylindrical rollers having a perforation row (DE 44 28 269 A1) or in the form of an endless flexible belt provided with a perforation row (EP 0 635 590 A2) are known.
An especially effective embedding of the core thread can be achieved when, according to the invention, the compaction zone is located as close as possible to the center of the fiber slubbing which is still wide upon its approach to the compaction zone. This is especially the case when the core thread is fed to the inlet side of the output roller pair of the drafting frame.
In a variation of this embodiment, the core thread can also be fed directly to the compaction zone. In the case of a suction belt compaction device, the core thread can be fed from above or from below to the drafting frame, from the same side as that along which the suction belt is disposed and can be guided around the deflection end of the belt at its upstream side. In other cases, the suction belt has a guide roller arranged at its upstream or inlet side around which the core thread is guided. When the compaction device has a suction roller, the core thread also can be fed to the periphery of this suction roller.
The compaction of fiber slubbing supplied by a drafting frame affords the advantage that the fiber slubbing is gathered tightly upon entry to the twisting zone upon which it is stabilized to a yarn. In this tightly gathered fiber slubbing, the twisting imparted to the yarn jumps practically to the clamping line at which the fiber slubbing with the core yarn emerges, i.e. the spinning triangle is very small. A consequence is that the losses of edge fibers which break away are minimal and that the yarn which is produced has few projecting fibers, i.e. reduced hairiness and as a consequence more effective coverage of the core thread by the fibers lying tightly thereagainst.
It has been found that this advantageous effect of compaction spinning can be further increased by carrying out the spinning in a thread-balloonless manner or with a reduced thread balloon. Thread-balloonless spinning or spinning with a reduced thread balloon, reduces the tension forces on the yarn in the yarn segment between the apex of the spindle and the output roller pair of the drafting frame and increases the twist density in this yarn segment. This effect appears to enhance the effect of compaction of the fiber slubbing.
The balloonless spinning or reduced thread balloon spinning can be achieved especially by providing an attachment on the spinning spindle of the ring spinning apparatus in the form of a spinning finger or a spinning crown. The twisting and winding up of the fiber slubbing by means of pot spinning apparatus also is effected without balloon formation and reduces the yarn tension forces in the yarn segment between the output roller pair of the drafting frame and the point at which the yarn meets the spinning pot. This system also has the advantages previously described of balloonless spinning.
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Dinkelmann Friedrich
Olbrich Andreas
Calvert John J.
Dubno Herbert
Hurley Shaun R
Zinser Textilmaschinen GmbH
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