Textiles: spinning – twisting – and twining – Apparatus and processes – Receiving twist type
Reexamination Certificate
1998-06-18
2001-10-30
Stryjewski, William (Department: 3741)
Textiles: spinning, twisting, and twining
Apparatus and processes
Receiving twist type
C057S328000, C057S400000, C057S401000, C057S408000, C057S411000
Reexamination Certificate
active
06308507
ABSTRACT:
FIELD OF THE INVENTION
My present invention relates to a method of making a textile yarn and to an apparatus for that purpose. More particularly, the invention relates to a method in which, utilizing a separating or singling drum, roller or rotor, a fiber strand is separated into individual fibers and the individual fibers are drawn by suction onto a fiber collecting surface. Ultimately the collected fibers, in a continuous process, are twisted and thereby formed into a yarn in which the fibers have been rendered parallel and stretched out by virtue of the disintegration of the fiber strand and the singling of the fibers before they are collected. The term strand is here used to refer to a ribbon, band or strip of fibers which need not be fully parallel before they are subjected to individual separation from that band. The term “sliver” will be used herein to refer to a bundle of parallel and drawn out fibers prior to twisting and which may form a more or less dense yarn package or packet, densification reducing the cross section of the sliver.
BACKGROUND OF THE INVENTION
It is known from U.S. Pat. No. 5,497,609, for example, to produce a textile yarn by decomposing a bundle of fibers into individual fibers, i.e. singling the fibers, by means of a separating rotor or wheel, and then feeding the single fibers to a fiber collecting surface which is formed as a perforated trough. The perforations of the trough are connected with a suction source so that the individual fibers can be drawn into the trough. The result is a packet of parallel fibers which are consolidated by imparting a twist to them as they are drawn from the trough. As additional fibers accumulate at the end of a yarn as it is thus formed, a continuous spinning process is ensured for producing practically endless yarn.
The earlier system has been found to require the twisting of the fiber packet to enable it to be drawn from the trough. To produce the twist and to assist in drawing the yarn from the trough, counter travelling belts may be used and it has been found in practice that such systems are subject to a high degree of wear and can give rise to the variations in the twist and yarn withdrawal speeds because of difficulties in precisely establishing and controlling the belt speeds. It is also possible to provide the trough so that it feeds into the nip between two cooperating perforated rollers or drums which are driven in the same sense and which rotate about mutually parallel axes, or a system in which the trough is formed between two such perforated drums under suction.
When the fiber packet is moved over a stationary perforated surface or is displaced transversely to the fiber collecting surface and thus the fibers must be drawn over the perforations at which suction is maintained, there is a tendency for some of the fibers at least to be partially drawn into the perforations. Fibers which are trapped in such perforations can lose their parallelity and stretched out orientations, can be shifted in the yarn, can be bent into hairpin shape or can be given a corkscrew shape, all to the detriment of the yarn and the desired uniformity and reproducibility thereof.
OBJECTS OF THE INVENTION
It is the principal object of the present invention to provide an improved method of and an apparatus for making textile yarn, utilizing the principal of disintegration of a fiber strand into individual fibers, i.e. the singling of such fibers, whereby the drawbacks outlined above are obviated.
Another object of this invention is to provide a method of and an apparatus for the aforedescribed purpose which facilitates the transfer of the fiber packet from the fiber collecting surface. Another object of the invention is to provide a yarn making method and apparatus which will yield a yarn free from the corkscrew or hairpin bends hitherto encountered and, in general, a more reproducible and usable yarn.
SUMMARY OF THE INVENTION
These objects and others which will become more readily apparent hereinafter are attained, in accordance with the invention by collecting the singled fibers on the fiber collecting surface without a twist of the resulting fiber strand, transferring the resulting fiber packet from the collecting region to another region and, at the latter region, imparting a twist to the fiber packet.
As a consequence, the fiber packet and the fiber sliver are displaced from the region in which the fibers are deposited without a twist and the twist for consolidation of the fiber packet or the sliver is applied at a different location such that the fibers cannot be drawn into the perforations and thus be trapped there until hairpin or corkscrew bends are imparted to them. The separation of the twisting step from the collection step ensures that a highly uniform twist can be applied and that parallelity of the fibers will not be lost until the twisting stage is reached. The twisting can be effected in a limit of a ring spinning machine and, in practice, it is found that the ring spun yarn which is thus produced is highly uniform. Indeed, especially in the production of cross yarn with large fiber mass in cross section, with thick fiber packets and hence thick sliver, it has been found to be advantageous to subdivide the fiber collection surface into two zones, namely, an upstream zone in which the fibers are drawn with suction against the surface to form the fiber packet or sliver and a downstream zone in which the fiber sliver is reduced, i.e. the sliver is compacted without imparting a twist to the sliver at this stage.
In apparatus terms, the fiber collecting surface is provided as a closed continuously moving surface which is formed with a small strip of perforations riding over one or more suction openings of a suction duct. The surface may be formed by a belt or a rotating perforated drum and the perforations of the surface can register with the suction opening or suction openings. In either case a drive must be provided, i.e. for the belt or for the drum.
Since the fiber collection surface moves in an endless surface with the fiber packet thereon, the fibers of the packet do not shift relative to the perforations of the collecting surface and there is no danger that hairpin or corkscrew bends will be imparted to the fibers or that fiber dislocation will result because of relative movement of the collecting surface and the collected fiber packet.
The fiber packet or sliver is transported by the rotating perforated drum or endless perforated belt to the location at which the consolidating twist is to be applied and the suction retaining the sliver on the collecting surface can be reduced until the sliver is released to the twisting means, e.g. a ring spinning apparatus with spindle, traveler ring and the like. The twist is imparted to a yarn which is no longer in contact with the collecting surface and since the twist does not take place while the yarn is on the collecting surface there is no retardation of the twisting action induced by the collecting surface and an especially uniform twist can result. The use of the ring spindle for effecting the twist and winding up the yarn which results has been found to contribute to the production by the method of the invention of yarns which very closely resemble ring spinning yarns.
According to a first embodiment of the invention, the travelling surface can be the surface of an endless flexible belt which is past over at least one driven belt roll and is provided with a row of perforations. In a second embodiment the travelling surface can be formed by a driven hollow drum provided with the perforations. The driven belt roller or the drum can form with a counter roller a roller pair through the nip of which the sliver is passed. This affords the advantage that the withdrawal speed of the sliver can be precisely defined and extremely uniform, thereby ensuring a constant cross section and uniform twist per unit length of the yarn which is produced.
The device for separating the fiber strand into individual fibers, referred to herein as a separating, resolving or disintegrating u
Dubno Herbert
Stryjewski William
Zinser Textilmaschinen GmbH
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