Wireworking – Wire twisting
Utility Patent
1999-10-26
2001-01-02
Larson, Lowell A. (Department: 3725)
Wireworking
Wire twisting
Utility Patent
active
06167919
ABSTRACT:
The present invention refers to a method of twisting at least two individual conductors and to a twisting apparatus used for this purpose.
Twisted conductors are used in great number of cases and for a great variety of purposes where electromagnetic compatibility (EMC) is desired. One field of application is the use of such conductors in the field of automotive engineering, e.g. for loudspeaker conductors or airbag conductors. Up to now, conductor manufacturers have always produced twisted conductors in the form of endless twisted conductors which were wound onto drums for the purpose of selling. In the case of such endless twisting operations, the cable drums with the “endless” individual conductors are rotatably secured to the twisting head and rotate together therewith about the twisting axis. The twisted conductors are then cut to length for the respective intended use, the ends are partly untwisted and the means in question, e.g. contact terminals, attachment members, individual wire sealing means, are attached thereto. These processes require a large amount of work and are therefore expensive. In addition, the stock of twisted conductors must be comparatively large, since said conductors are produced with different diameters, twisting gradients, numbers of individual conductors, different combinations of colours of the individual conductors, etc. for the respective intended use.
It is now the object of the present invention to provide a method of twisting individual conductors, which makes the production of twisted conductors more attractive for cable manufacturers with regard to the expenditure of work, the manufacturing costs and the storage expenses.
According to the present invention, this object is achieved by a method comprising the following steps:
fixing the first conductor ends of individual conductors, which have been cut off to a suitable length, in respective separate untwisting fixation means which are rotatable essentially parallel to a twisting axis;
fixing the second conductor ends of said individual conductors in respective separate twisting fixation means which are arranged such that they are adapted to be rotated in common about said twisting axis;
arranging a twisting slide between the essentially tensioned conductors; and
rotating the twisting fixation means in common about the twisting axis and rotating the untwisting fixation means about the conductor axis of the respective conductors in the same direction.
The enormous advantage of this method is to be seen in the fact that individual conductors can be cut to a specific length, perhaps stripped and provided with various components prior to the twisting operation. The conductor ends, which may perhaps be provided with attachments, are then inserted in the respective fixation means and clamped in position, each fixation means having preferably associated therewith one conductor end. The twisting fixation means and the twisting slide then carry out the twisting of the individual conductors, whereas the untwisting fixation means can remain at a position where they are arranged essentially parallel to the twisting axis. Since, due to the common rotational movement of the twisting fixation means, the individual conductors are also rotated about their own axis in the case of each rotation about the twisting axis, the untwisting fixation means will take care that a rotational movement of each individual conductor in the same direction takes place so that said individual conductors cannot become twisted in themselves.
On the basis of the method according to the present invention, the amount of material that has to be kept in stock can be reduced, since it is no longer necessary to keep all the combinations of conductor colours and conductor cross-sections in stock. The combinations of conductors required can now be produced from standard conductors in accordance with the cable manufacturer's wishes. In contrast to the processing of conventional twisted conductors, problems will no longer arise with regard to untwisting, smoothing, unwinding from drums, cutting, cutting to length, stripping, fastening and mounting of sealing means. For subjecting conductors which have already been twisted to this kind of processing, special machines are required. The method according to the present invention permits processing on standard machines, since twisting can be carried out as the last manufacturing step. In this connection, also the reliability of the process and the quality of the twisted conductors will be improved. By means of said method, it is easily possible to process prefabricated conductors with arbitrary kinds of attachements at the conductor ends. The untwisting operation takes care that torsional loads at the ends of the individual conductors will be avoided.
The twisting slide can be arranged in the vicinity of the twisting fixation means between the conductors in an advantageous manner, and, during the twisting operation, it can be displaced in the direction of the untwisting fixation means. This permits a more precise control of the twisting operation, since, initially, said twisting operation begins as closely as possible to the twisting fixation means.
In addition, the displacement speed of the twisting slide can be controlled in dependence upon the speed with which the twisting fixation means rotate about the twisting axis.
The twisting gradient of the individual conductors can be varied in this way. This can even be done to such an extent that a twisted cable produced from individual conductors can comprise different sections with different twisting gradients. For keeping the tensile stresses which act on the individual conductors during the twisting operation essentially constant, the untwisting fixation means can be moved in the direction of the twisting fixation means in a controlled manner during the twisting operation. It is readily evident that, due to the twisting of individual conductors having a specific length, only cables having a shorter final length can be produced depending on the twisting gradient. This “shrinkage” is preferably taken into account by a controlled displacement of the twisting fixation means. It is, of course, also possible to move the untwisting fixation means relative to the twisting fixation means. It turned out that a certain amount of pretension on the individual conductors is advantageous for the twisting operation.
In accordance with a further variant, it is suggested that the cutting to length and/or fixing of the individual conductors should be carried out automatically. Accordingly, further intermediate steps can be added, when the individual conductors are subjected to additional prefabricating steps, e.g. by attaching suitable terminals to the ends etc. This measure will be particularly suitable when twisted cables in high numbers of pieces are dealt with.
In accordance with an advantageous embodiment, the untwisting fixation means can be moved, after the clamping of the first conductor ends, along the twisting axis away from the twisting fixation means so as to insert the conductors into a twisting apparatus. The untwisting fixation means are thus used as a transport device for the individual conductors.
One feature that can be provided in this connection is that the specific insertion length is smaller than the maximun distance between the untwisting and twisting fixation means at the beginning of the twisting operation, and that, after the fixing of the second ends in the twisting fixation means, the conductors are tensioned by a renewed displacement of the untwisting fixation means. on the one hand, this process will facilitate the insertion of the second ends of the individual conductors, since they can be inserted into the twisting fixation means while they are still comparatively loose and not pretensioned and, on the other hand, a pretension is purposefully applied to the individual conductors by displacing the untwisting fixation means.
According to an advantageous embodiment, the conductors can be twisted more closely in the area of their
Dr{umlaut over (a)}xlmaier Fritz
F{umlaut over (u)}chsl Klaus
Armstorng, Westerman, Hattori, McLeland & Naughton
Gluth Systemtechnik GmbH
Larson Lowell A.
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