Chain – staple – and horseshoe making – Chain making – Roller chain
Reexamination Certificate
2000-05-22
2001-12-18
Jones, David (Department: 3725)
Chain, staple, and horseshoe making
Chain making
Roller chain
C059S005000, C059S008000, C474S231000
Reexamination Certificate
active
06330788
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to plate chains comprising outer and inner chain links which are interconnected at joint places designed as slide bearings, each of the joint places being formed by a sleeve of the inner chain link and by a pin bolt of the outer chain link which is rotatable in the sleeve substantially about its own axis.
BACKGROUND OF THE INVENTION
In the simplest form of a plate chain, the inner chain link consists of two parallel inner plates that are interconnected by two sleeves arranged in parallel with each other and in a direction perpendicular to the plate chains. The outer chain link consists of outer plates which are arranged in parallel with each other and are connected by means of two pin bolts that are arranged in parallel with each other and in a direction perpendicular to the outer plates. The chain joints are each formed by a sleeve of the inner chain link and by a pint bolt of the outer chain link which extends through the sleeve. Both the inner surface of the sleeve and the outer surface of the pin bolt are shaped in the form of a cylindrical surface so that they function in the manner of a slide bearing in that the pin bolt is pivotable about its own axis inside the sleeve. To achieve a satisfactory function of the joint places, the pin bolt and the sleeve are joined with a suitable play. However, on account of manufacturing inaccuracies and because of said play, there is an increased wear, in particular at the force-transmitting pulling sides of pin bolt and sleeve.
For the reduction of such wear, chains with roller bearings (rocker joints) have inter alia become known, for instance from DE 4235198 A1. In such chains the pin bolt rolls over a convex projection in the sleeve so that there will be no sliding movement as in the case of a slide bearing, but a rolling movement. Such roller bearings do also exist with two pin bolts rolling on one another. Such types of chains with roller bearings are, however, not the subject matter of the present invention. Rather, the intention is to improve a plate chain with simple joint places designed as slide bearings.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention to improve a plate chain of the above-mentioned type with respect to its wear characteristics.
Said object is achieved according to the invention by the features that at least one portion of the lateral surface of the pin bolt and an associated portion of the inner surface of the sleeve have a different circumferential contour at the pulling side so that the pin bolt is supported on the sleeve at at least two circumferentially spaced-apart points or lines of contact at the pulling side. Thus, Hertzian stress is reduced by such a design at the pulling side in the case of a pulling load acting on the surfaces of contact because the number of the points of contact is at least doubled in comparison with conventional plate chains. The force can be transmitted in a correspondingly distributed manner. So far there has always been a line contact in conventional plate chains in the area of the power transmission between pin bolt and sleeve, resulting in correspondingly increased wear. The term pulling side is used here to mean the respectively facing side portions of the inner surface of the sleeve and the outer surface of the associated pin bolt that upon a pulling load acting on the chain will transmit forces. The forces are transmitted in the case of a straight-pulled chain in and opposite to the running direction.
In addition it should be noted that the term “different” circumferential contour” should not be understood as the standard differences or deviations caused during production by manufacturing inaccuracies or the play existing between pin bolt and sleeve. Rather, a deliberately produced different circumferential contour is meant here.
Advantageously, such a difference can be produced in that the pin bolt has a substantially circular cross-section and the sleeve has a substantially circular inner cross-section adapted thereto, with at least one indentation being additionally provided at the pulling side in the lateral surface of the pin bolt and/or the inner surface of the sleeve. It is thereby intended to deviate as little as possible from a circular cross-section of both the inner contour of the sleeve and the outer contour of the pin bolt. As a result, at least one corresponding indentation is just provided at the place required therefor, i.e. in the area of the pulling sides. Each indentation has edges which in case of a load will then serve as support points or lines for the respective counter-element. Such indentations, however, can also be produced by a deformation of the sleeve in the area of the pulling side.
To achieve a support which is as selective as possible over a large area of the sleeve and the pin bolt, respectively, a further variant is provided for in which the inner surface of the sleeve is provided at the pulling side with an axially parallel joint trough whose substantially spaced-apart side edges define two spaced-apart lines of contact for the associated pin bolts. The forces can be transmitted in a very uniform manner thanks to the axially parallel guidance of the joint trough, whereby the contour of the side edges of the joint trough can be designed accordingly.
To achieve said effect also in the end sections which are stiffened by the inner plates of the inner chain links and pertain to the sleeves pressed thereinto, the joint trough may extend over the entire length of the sleeve.
As a variant which can be produced in a particularly simple manner the side edges of the joint trough extend in parallel with each other. This will then be a joint trough of a symmetrical construction which can extend over the entire length of the sleeve.
The joint trough may be incorporated in the axial direction of the sleeve.
To keep notch tensions as small as possible and to avoid any lasting weakening of the sleeve wall, the joint trough may further have a cross section in the form of the segment of a circle (or in the form of a sickle). Preferably, the radius of the segment of a circle is smaller than the radius of the pin bolt so that a positive effect is still observed after the edges of the joint troughs have worn to some extent.
To achieve such a positive effect produced by a joint trough, it is entirely sufficient when the trough has just a small depth. The depth may range from 5 &mgr;m to 25 &mgr;m and is 10 &mgr;m in a preferred embodiment.
To achieve a wall thickness of the sleeve that is not weakened, if possible, relatively large radii are used most of the time for the design of the joint trough; these are nevertheless smaller than the radius of the pin bolt. A variant of particular advantage is where the side edges of the joint trough are arranged relative to the axis of the sleeve at an angle of 90° to 160°, preferably 140°, with respect to each other. An excellent slide bearing effect is thereby achieved by the two points of contact, i.e. also in the area where the plate chain is deflected, e.g. on a chain gear, although in said area the forces are no longer introduced into the chain links exactly in the longitudinal extension of said links.
Preferably, the joint trough is arranged in symmetry with the main pulling direction of the chain at the pulling side. This offers an optimum transmission of the forces in the case of a straight-pulled chain, but also ensures an adequate support and good slide bearing characteristics upon deflection both in the one and the other direction.
The present invention also relates to a method for producing members of a plate chain in which a sleeve is wound by means of a rolling process from a sheet material and a joint trough is incorporated at the pulling side of the sleeve. Advantageously, the joint trough may be incorporated in a step subsequent to the rolling process, whereby a pre-orientation of the sleeve can take place. This is advantageously effected in that the joint trough is incorporated after the joining of an inner chain link
Joh. Winklhofer & Soehne GmbH und Co. KG
Jones David
Marshall Gerstein & Borun
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