Textiles: spinning – twisting – and twining – Apparatus and processes – Elements
Reexamination Certificate
2000-04-19
2001-09-25
Worrell, Danny (Department: 3741)
Textiles: spinning, twisting, and twining
Apparatus and processes
Elements
C057S135000
Reexamination Certificate
active
06293079
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a hollow spindle, in particular for the manufacture of elastic twisted yarns, comprising a thread channel extending coaxially with respect to the axis of the spindle, through which thread channel is axially moved a yarn, in particular an elastic core yarn.
BACKGROUND OF THE INVENTION
When manufacturing elastic twisted yarns with hollow spindles, as they are known, for example, from the DE 29 19 100 C2, DE 196 26 549 A1 or CH 200 628, the troublefree processing of the yarn is important for the economic efficiency and the quality of the finished product. Critical in these processes is the running behaviour of the elastic core yarn, for example Elastan. In particular when using fine core yarns (44 dtex, 22 dtex, 11 dtex or even finer yet), utilizing Elastan, and there most of all at low drafts (less than 3 times), breakdowns of many different types occur because of the low yarn tensions, which breakdowns can result in breakage of the yarn. The yarn tension of the core yarn from the point of removal from the feed bobbin to the point at which it is twisted above the exit from the hollow spindle is therefore a very important parameter. The behaviour of the core yarn in the thread channel of the hollow spindle has a decisive influence on the yarn tension. As a rule one must assume that the core yarn rests on the inner surface of the thread channel and rotates together with the hollow spindle. Until now the thread channel in the hollow spindle is created by means of a long bore. Thus the surface of the thread channel is cylindrical. A cylindrical surface contacts the core yarn along a contact line, which in particular due to the characteristics of the elastic core yarn results in a large amount of friction. This friction reduces the tension in the core yarn, which it has prior to entering the hollow spindle, which can lead to the abovedisclosed breakdowns. In the case of many types of yarns, in particular Elastan, an adhering effect also occurs between the yarn and the smooth surfaces of the thread channel, which can clearly further increase the friction force.
SUMMARY OF THE INVENTION
The basic purpose of the invention is to provide a hollow spindle, in particular for the manufacture of elastic twisted yarns, in which the friction between the inner surface of the thread channel and the core yarn is reduced to a minimum and thus a trouble free processing of the yarn is guaranteed.
This is attained according to the invention in such a manner that the thread channel has ribs on its inner surface, which ribs extend in peripheral direction or helically, and project inwardly over the surface so that the yarn running through the thread channel contacts the ribs at a point thereon, otherwise, however, the yarn is supported at a distance from the inner surface.
Since the yarn running through the thread channel has in this embodiment only a pointlike contact with the ribs, the friction between thread channel and yarn is very significantly reduced. The friction created in the thread channel can thus no longer or only very insignificantly influence the intended yarn tension of the core yarn. The trouble free processing is thus guaranteed also in the case of very low yarn tensions.
In order to reduce the number of pointlike contact areas between the ribs and the yarn guided through the thread channel, the ribs should advantageously be arranged at large axial distances from one another.
An advantageous embodiment of the hollow spindle is that the thread channel is formed by a small tube inserted into a center bore of the hollow spindle, which small tube has the ribs on its inner surface. Such a small tube provided with ribs can namely be manufactured relatively inexpensively, and it is in addition possible to optimize the inner surface of the small tube, namely of the inwardly projecting ribs, in order to reduce the initially mentioned adhering effect.
The inner surface of the small tube should for this purpose be thread-fine. The term “thread-fine” refers to a surface which does not rough up the thread. The surface is thereby not to be smooth because this creates a sticky effect, but it is to be matted or similar to a very fine orange skin. Such a surface can be achieved during a drawing of the small tube or also its deformation, which occurs in order to create the ribs.
Further advantageous embodiments of the invention are characterized in the remaining subclaims.
REFERENCES:
patent: 3122877 (1964-03-01), Keyser
patent: 3948032 (1976-04-01), Quast
patent: 4736579 (1988-04-01), Stenmans
patent: 5404703 (1995-04-01), Frentzel-Beyme et al.
patent: 200 628 (1938-10-01), None
patent: 29 19 100 (1980-11-01), None
patent: 196 26 549 (1998-01-01), None
Dür Hansjoerg
Heinzle Norbert
Flynn ,Thiel, Boutell & Tanis, P.C.
Hamel AG
Worrell Danny
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