Chain – staple – and horseshoe making – Chain making – Sprocket chain
Reexamination Certificate
2001-04-12
2002-12-10
Jones, David B. (Department: 3725)
Chain, staple, and horseshoe making
Chain making
Sprocket chain
C059S011000, C059S035100
Reexamination Certificate
active
06490853
ABSTRACT:
The present invention relates to a method for joining a plate chain link, wherein at least one plate is connected to at least one bolt by a pressing and aligning process. Furthermore, the present invention relates to a method for carrying out the method.
In the prior art very different methods for joining a plate chain link or a plate chain have established themselves. These methods are in part quite different and are adapted to the designs of the various plate chains. There are methods in which only the inner chain links are produced and a further method is subsequently performed for joining the chain by producing the outer chain links, with the already prefabricated inner chain links being interposed. This means that the methods must be suited, on the one hand, for joining solid bolts with plates and, on the other hand, for joining hollow bolts (sleeves) with plates. In the manufacture of an outer chain link for a duplex chain a plate must e.g. first be slid in central fashion onto a solid bolt. The interposition of rollers for making a roller chain should also be possible with the individual methods.
In particular in high-quality control chains, dimensional accuracy with respect to the parallelism of the bolts (solid bolts and sleeves) and plates, the distance of the plates when several plates are used, as well as the centering of the chain link elements relative to the main chain axis, are of decisive importance.
Normally, the chain links are built up from below. This means that the lower plate is first positioned and the associated bolt is supplied. In the manufacture of an inner chain link the plate and the sleeve are then centered relative to each other via a positioning mandrel projecting from the assembly plane. Subsequently the lower plate and the sleeve are pressed together. Optionally, before or after said process a roller may additionally be mounted on the sleeve. Finally, the upper plate is supplied and also centered relative to the sleeve by means of a positioning mandrel and subsequently pressed thereonto. This procedure is carried out at predetermined cycles so that a joint press block operating with a specific lift number respectively applies the pressing force. This can be carried out on a circular table or successively in series.
DE 2 457 241 A1 already discloses a method for producing chain links on successively arranged rotary mounting tables, the method employing the layered construction of the chain link from the bottom to the top, but already effecting an excellent alignment of the individual chain link elements relative to one another thanks to the skillful use of positioning mandrels. This method, however, employs many joining steps which must be simplified. Moreover, a centering relative to a main chain axis is not fully achieved. What poses, in particular, problems are the different lengths of the bolts, so that the centering operation relative to the main chain axis is not satisfactory. It is now desirable to provide a method which with a few steps can achieve an adequate centering or symmetry of the chain links to be produced relative to the main chain axis, i.e., independently of the type of chain link (by centering a single plate in the center of the bolt or by symmetrical arrangement of two plates on the end portions of a bolt).
It is therefore the object of the present invention to provide a method and a device for joining a plate chain link which exhibits improved dimensional accuracy, in particular, with respect to symmetry in relation to the main chain axis.
According to the invention this object is achieved by providing a method for joining a plate chain link of the above-mentioned type, in which the at least one bolt is centered relative to a main chain axis by the simultaneous active application of symmetrical clamping forces to the faces of the bolt, and the at least one plate is pushed by a joining lift relative to the bolt into a position symmetrical to the main chain axis on the bolt.
The method of the invention mainly differs from the methods in the prior art by the features that while the bolts are being centered there is no action against a fixed stop, but rather a central centering operation is carried out by the simultaneous application of symmetrical clamping forces. Of particular importance is here the term “active application” because in the prior art the force is actively applied only from one side, whereas the other side in this process is at a standstill and acts as a stop (passive application of force). The difference is now that in the prior art the dimensional accuracy, in particular, of the symmetry relative to the main chain axis is determined by the face of the chain bolt that rests-on the stop. In the present invention, the center of the main chain axis is always found in an exact way because the bolt is automatically aligned with said axis due to the active application of symmetrical clamping forces. The principle is similar to a pair of tongs in the case of which the press forces are also applied in symmetry with a line of symmetry extending through the pivot axis of the tongs. The advantage is that the chain bolts need not necessarily be produced with a very small range of tolerance, because the faces of a bolt always have the same distance from the main chain axis. This makes it also possible to simultaneously center the two bolts of a chain link in one operation if these are respectively acted upon with symmetrical clamping forces. It might be that a distinction has to be made in this method between joining lift and centering by the symmetrical clamping forces because an excellent dimensional accuracy (symmetry) is also achieved when the symmetrical clamping forces become only operative at the end of the joining operation and thereby ensure the final joining position of the bolts.
In most cases it is of advantage when the joining lift is carried out by pushing the at least one plate onto the at least one bolt and by moving the at least one plate by the simultaneous active application of symmetrical joining forces into a position in symmetry with the main chain axis. In this instance, too, the force may only be applied during the joining lift at one side of a plate as long as it is ensured that a symmetrical force couple is applied at the end of the joining lift to arrange the plates in symmetry or to center the one plate in the center. By analogy with the bolts, the plates are then also very exactly aligned relative to the main chain axis.
Furthermore, it is also possible for specific chain links that the joining lift is carried out by pushing the at least one bolt into the at least one plate and that at least at the end of the joining lift the at least one bolt is centered relative to the main chain axis by the simultaneous active application of the symmetrical clamping forces. This means in such a case that the plates are not pushed onto precentered bolts, but the at least one bolt is pushed into an opening of the plate and the bolt is subsequently centered. In such a process the plate can be fixedly anchored in its position. Such a procedure is mainly applied in the case of intermediate pin plates for duplex chains because in duplex chains the push-on paths of the bolt relative to the plate are bound to be long.
When two plates are simultaneously pushed onto the respectively opposite end portions of the bolt, this may be carried out via a corresponding centering stop on the force-applying elements, so that these occupy their symmetrical position relative to the main chain axis. Each of the outer surfaces of the plates will then have exactly the same distance from the main chain axis. Since the thickness of the plates can be produced at the same costs with a much smaller tolerance than the length of the bolts, the distance of the insides of the plates is also within the necessary range of tolerance.
Advantageously, a further method step may be provided in which the at least one plate and the bolt are prepositioned relative to one another so that an opening in the plate is arranged to be coaxial to the bolt.
Fink Thomas
Heinrich Dag
Winklhofer Gerhard
Joh. Winklhofer & Söhne GmbH & Co. KG.
Jones David B.
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