Chain – staple – and horseshoe making – Chain making – Roller chain
Reexamination Certificate
2000-02-14
2001-05-01
Jones, David (Department: 3725)
Chain, staple, and horseshoe making
Chain making
Roller chain
C059S005000, C474S209000, C474S231000
Reexamination Certificate
active
06223515
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a link chain comprising chain links interconnected at respective hinge points by a hinge bolt, at least one bearing bushing arranged on a hinge bolt, at least one roller arranged on said bearing bushing such that it is rotatable about the hinge bolt, and an axial retaining means attached to the hinge bolt and used for axially securing the bearing bushing and the roller.
Such link chains provided with rollers are used as conveyor chains in most cases. In the case of known conveyor chains, the hinge bolt is extended on one side thereof for this purpose, and the hinge bolt itself or the hinge bolt with additional components attached thereto is used for transporting a great variety of objects. Especially if the objects transported have very little weight, it is extremely important to guarantee that the chain runs as smoothly as possible so that the objects can be transported without any transport accidents. Up to now, bearing bushings consisting of plastic material have been press-fitted into the rollers which were then arranged on the hinge bolts in a freely rotatable manner. For certain cases of use, the rollers were guided in rails so that the chain could be guided precisely. In most cases, the bearing bushings with the rollers press-fitted thereon were axially fixed via retaining washers which were press-fitted on said bearing bushings and which provided only such an amount of axial play that the roller was freely rotatable. Although, due to the use of a bearing bushing of plastic material, this kind of structural design proved to be a useful solution for many cases of use, transport accidents still occur especially when objects having very little weight are being transported, said transport accidents being especially due to undesired vibrations.
It is therefore the object of the present invention to provide a link chain of the type cited at the start, which operates freer from vibrations.
SUMMARY OF THE INVENTION
According to the present invention, this object is achieved by the features that the bearing bushing is implemented as an axial damping element which has, on at least one end face area thereof, a damping area formed integrally with the bearing bushing, and that the bearing bushing is arranged in such a way that the damping area rests on the axial retaining means. It goes without saying that the friction between the damping area and the axial retaining means should be small enough to guarantee that the roller continues to roll. On the basis of the structural design of the bearing bushing, the roller is arranged such that it is damped especially in the axial direction. Due to the fact that the bearing bushing and the damping area are formed integrally with one another, relative movements between these two components will be prevented, whereby an additional friction surface is avoided and wear between these components is prevented. The additional axial damping has the effect that also tilting movements about the hinge bolt axis will be damped. This is important especially in cases where the chain in question is a side bow chain which is also capable of carrying out a curve movement transversely to the hinge bolt. Such vibration damping by the bearing bushing can be relevant to a great variety of cases of use and is not limited to conveyor chains alone.
According to a preferred embodiment, the roller can be fixedly connected the bearing bushing. It proved to be advantageous when no relative movement takes place between the roller and the bearing bushing and when the bearing bushing is arranged on the hinge bolt such that it is freely rotatable thereon.
Although the components can also be joined by means of an adhesive, the roller is press-fitted onto the bearing bushing according to a preferred variant. This will avoid additional connection elements and reduce the costs.
A simple embodiment of the damping area consists of a damping area implemented as an elastic, annular support lip on the end face. Such a support lip has a comparatively small area of contact with the axial retaining means so that the friction caused is very small. In addition, a support lip can easily be constructed such that a suitable spring constant and spring force, respectively, is provided for obtaining the damping which is necessary and desired. Support lips can especially be implemented such that they permit a soft spring compression movement at the beginning and that the spring constant increases as the spring compression movement continues until, when the support lip is in full contact with the axial retaining means, the spring constant of the material will still be effective.
Preferably, the support lip can be subdivided into a plurality of ring segments which are separated from one another by respective groove areas. Due to the fact that the radial forces acting on an annular support lip during the spring compression movement are comparatively large, the best method of dealing with these radial forces is a measure of this kind, since the ring segments can expand into the groove area. This makes the support lip much more resistant to destruction by continuous loads.
For achieving an advantageous spring compression movement and for supporting the ring segments on the end face in the case of a full spring compression movement, the support lip can have a frusto-conical outer surface and a frusto-conical inner surface, the diameter of the support lip enlarging in a direction away from the end face. This also has the effect that the distance to the hinge bolt axis is enlarged so that, under the influence of tilting forces, a support on the axial retaining means is achieved by means of a much smaller spring force.
The groove areas can have a depth corresponding at least to the height of the support lip so that the relief provided by said groove areas will be effective over the whole height of the support lip.
In order to prevent a formation of cracks in the groove area, the groove areas are preferably each implemented such that they have a V-shaped cross-section and a rounded groove base.
In addition, a respective central axis of said groove areas can extend radially to the axis of the bearing bushing. This means that all groove areas are orientated radially towards the centre of the bearing bushing. This orientation is provided mainly for reasons of symmetry and for obtaining an axial load on all the ring segments which is as uniform as possible.
In order to achieve a desired spring hardness of the bearing bushing, at least the support lip is produced from an elastic material. For this purpose, a bearing bushing with a support lip is preferably produced from a plastic material, said plastic material being preferably a polyurethane. Polyurethane has sufficient strength and elasticity in combination with the smallest possible coefficient of friction. In addition, the bearing bushing will be much easier to produce when plastic material is used.
The inner and outer surfaces can be produced with a taper angle in the range from 100 to 130° C. This will have the effect that the support lip will expand comparatively widely and that the spring force will increase rapidly.
In order to augment the increase in spring force still further, the outer surface can have a smaller taper angle than the inner surface so that the thickness of the support lip continuously decreases as the distance from the end face increases. This will also have the effect that the comparatively high bending forces of the ring segments in the area of the end face of the bearing bushing are taken up more effectively.
According to one embodiment, the bearing bushing can have a circumferentially extending flange, which is provided at the bearing-bushing end face area associated with the support lip and which is accommodated in a step of a bore of the roller in an essentially precisely fitting manner. On the one hand, this flange serves to fix the bearing bushing in position, and it can be press-fitted into said step of the bore of the roller. On the other hand, it is possible th
Graemann Peter
Koschig Richard
Schulze Peter
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Joh. Winklhofer & Sohne GmbH & Co. KG
Jones David
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