Textiles: spinning – twisting – and twining – Apparatus and processes – False twist device
Reexamination Certificate
2000-06-19
2001-11-13
Worrell, Danny (Department: 3765)
Textiles: spinning, twisting, and twining
Apparatus and processes
False twist device
C057S333000
Reexamination Certificate
active
06314714
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a device for producing spun yarn, and more particularly to such a device having a housing, a guide for a drafted but untwisted sliver, a hollow spindle having a spindle head portion tapering toward a spindle entry opening for guiding therethrough a yarn formed from the sliver, and means for generating an airflow to turn or twist the fibers of the sliver.
BACKGROUND OF THE INVENTION
German Patent Application DE 199 26 492, not heretofore published, describes a device for producing spun yarn by means of an airflow, wherein a fiber guide is arranged in a block of nozzles. An untwisted sliver emerging from a drafting unit is drawn into the block of nozzles toward an arrangement of a spindle and a sliver guide. In the vicinity of an inlet opening of the spindle, the drafted but untwisted sliver is exposed to an airflow acting in a circumferential direction in the area between the sliver guide and the spindle, thereby is acted upon by a rotating movement. Here, the fibers of the sliver are subjected to the effects of the rotating airflow without controls. Subsequently, this fiber structure is drawn through the spindle for creating a yarn, during which free fiber ends are wrapped around a conically tapered head portion of the spindle and are placed around the fiber structure as covering fibers.
Yarn formation can take place with the spindle at rest, as well as when it is rotating. In the course of wrapping the free fiber ends around the conically tapered spindle head when the spindle is not rotating, a friction force is imposed between the fiber ends and the surface of the spindle head, which restrains their intended rotating movement and therefore can have negative effects, in particular at high yarn speeds. The free yarn ends cannot wrap themselves around the conical spindle head to a sufficient degree and subsequently are insufficiently placed around the draw-off yarn. As a result, the yarn speed during spinning must be limited to avoid deleterious effects on the yarn produced. Although a reduction of the disadvantages caused by such friction can be achieved by utilizing a rotating spindle, a reduction in the yarn strength rather than a desired increase in yarn strength can occur at increasing numbers of revolutions of the spindle in ranges above a certain number of revolutions, for example between 20000 rpm to 30000 rpm. With a completely rotating spindle, a rotating effect can be imposed on the yarn as a result of partial and occasional frictional contact of the interior surface of the spindle with the yarn being drawn off through the spindle inlet opening, which can cause an undesired false twisting of the yarn.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide an improved spun yarn producing device of the foregoing type which addresses the above-described disadvantages of the prior art and, more particularly, which effectively counteracts a reduction of the yarn strength at high, increasing numbers of revolution of the spindle.
This objective is addressed by the present invention by providing a spindle assembly with a conical spindle head portion rotatable independently of a spindle core portion which guides the formed yarn. It is thus possible to reduce or even completely avoid negative effects on the yarn strength even at high, increasing numbers of revolution of the spindle and it is possible in this manner to prevent undesired false twisting. Such devices embodying a spindle head portion, preferably of a conical configuration, to perform a rotating movement while a stationary spindle core portion guides the drawn-off yarn are distinguished by a relatively simple structure.
A particularly advantageous effect in respect to yarn strength may be achieved if the rotary movement of the conical spindle head portion takes place in the direction of the circulating airflow, and if the surface velocity of the spindle head portion is greater than the speed of movement of the airflow circulating around the spindle head portion. A permanent wrap-around action of the free fiber ends is thereby aided and a pronounced reduction occurs of the disadvantages which can arise because of frictional losses in the course of the wrapping of free fiber ends around the spindle head portion. This has advantageous results when the number of spindle revolutions and the yarn speed are increased. It is also thereby possible to improve the yarn strength and the uniformity of the yarn.
If the spindle inlet opening is formed by a flanged annular end portion of the spindle core portion or any other ring form which is fixedly connected with the spindle core portion, and if the conical spindle head portion is at least partially covered by the flange or ring, an undesired rotational effect exerted by the rotating spindle head portion on the yarn is completely prevented.
In an embodiment of the device, wherein the spindle core portion is mounted in the housing and the spindle head portion is rotatably seated by means of a bearing arranged between the spindle head and spindle core portions, a compact structure and a low-friction seating is possible. These advantages can be increased if the bearing of the spindle head portion is provided, for example, by needle bearings. In an alternative simple, stable and space-saving embodiment, the spindle head portion is rotatably seated in an easily accessible bearing supported on the outer circumference of the spindle head portion, and the spindle core portion, as well as the bearing, are mounted in the housing.
Thus, with the present invention, the rotating portion of the spindle assembly can be limited to a large degree to the area of the spindle head portion. With such an embodiment, the mass which must be moved can be kept relatively small. Small masses to be moved can also be achieved by means of a spindle head portion of lightweight construction, for example in the form of a thin-walled cone.
The device in accordance with the present invention reduces or prevents negative effects on yarn strength by frictional losses, even at high, increasing numbers of spindle revolutions. By means of improved wrap-around of the fibers, it is possible to perform the spinning process at high yarn speeds, without it being necessary to accept disadvantages because of a reduction of yarn strength. The production process of the yarn is improved.
Further details, features and advantages of the present invention will be explained and understood from the following disclosure of exemplary embodiments represented in the accompanying drawings.
REFERENCES:
patent: 5211001 (1993-05-01), Mori
patent: 5390485 (1995-02-01), Mori
patent: 5511373 (1996-04-01), Banba
patent: 5528895 (1996-06-01), Deno
patent: 5673547 (1997-10-01), Baba et al.
patent: 5927062 (1999-07-01), Deno et al.
patent: 41 31 059 C2 (1992-03-01), None
Coll-Tortosa Liberto
Feuerlohn Helmut
Munill Francesc Roig
Schulze Oliver
Tornero-Garcia Jose Antonio
Kennedy Covington Lobdell & Hickman LLP
W. Schlafhorst AG & Co.
Worrell Danny
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