Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
1998-11-27
2001-05-15
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Plain bearing
C384S296000
Reexamination Certificate
active
06231239
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a bearing bush with a backing comprising at least one layer, in particular an overlay, on its inner surface, as well as to the use and method for the production thereof.
2. Description of Related Art
Bearing bushes have many uses, e.g. in door hinges, as roller bearing systems, pedal bearings in flexible joints etc.
Depending on the use to which the bushes are to be put and their installation position, said bushes comprise one or two flanges (end flanges) at one or both bush ends. The bushes are installed by interference fit, whereby an immovable fit is ensured. However, this is only achieved if the bush is inserted into an appropriately solid component.
If bushes are to be used in rubber components, the fit is markedly poorer. To remedy this, it has hitherto been attempted to roughen or knurl the outer surface. The resilient material had hitherto to be vulcanised onto the bush, wherein damage could occur to the sliding material of the bush owing in part to the high temperatures occurring during this process. Moreover, where end flanges were to be provided, these had to be flanged later.
For other applications, such as pedal bearings or the like, where the bushes have to be arranged in a pedal lever, additional guide elements, such as bosses, are required, into which two flanged bushes are inserted. This is particularly necessary when the wall thickness of the pedal lever is less than the axial length of the bushes.
A ball bearing system is known from U.S. Pat. No. 3,351,999 which comprises an appropriately shaped bush consisting of a porous metal impregnated with a lubricant. To produce the ball bearing system, a cylindrical bush is inserted together with the ball into a holding device slotted on the outside. By an upsetting process, the bush, and thus also the holding device, is given a round contour, wherein, owing to the external slot, the bush undergoes slight deformation, which is intended to assist fixing in the holding device. In the area of the deformation, the bush does not adjoin the ball, because the deformation does not cause the inner surfaces of the bead-shaped deformation to adjoin each other. The oblique outer surfaces of the deformed areas do not provide the bush with a secure fit.
A plain pedal bearing is known from DE-PS 841 087, in which the bush, in which a tube is mounted, may follow the rocking motion of the tube to a limited degree. To limit the rocking motion, the bush comprises an outwardly directed bead, which may move in a recess provided in an annular component surrounding the bush. The bush consists of steel and does not comprise any sliding coating. The bead is open on the inside and comprises radial slots distributed around its circumference, whereby the stability of the bead is considerably weakened, such that a bush of this type is not suitable for rigid installation with lateral loading, because with time the bush loosens and leaves its original installation position.
U.S. Pat. No. 1,793,874 describes a bearing comprising a curved bush in which a sliding web is inserted. The bush is surrounded by a supporting or holding ring, which comprises one or two bead-type deformations on its outside for fixing in a housing. A sliding web is also arranged between the bush and the holding device, such that the bush is mounted movably in the holding device. This bearing system is complex and expensive owing to the number of components and additionally requires a correspondingly large amount of space.
SUMMARY OF THE INVENTION
The object of the invention is therefore to provide a bearing bush which may be installed without auxiliary components and provides a secure fit, in particular in conjunction with resilient components. It is also the object of the invention to provide an appropriate production method for such bearing bushes.
This object is achieved with a bearing bush in which at least one flange (center flange) in the form of a circumferential closed bead is provided at a distance from the bush ends.
A closed bead or closed flange is to be understood to mean a bead or flange in which the inner surfaces are mutually adjacent. In this way, the flange is not only space-saving, but also more stable than beads with cavities (so-called open beads).
The outer surfaces of the flange are preferably oriented so as to be parallel to the longitudinal axis of the bearing bush. This has the advantage that the flange lies flat against the component in which the bearing bush is installed. Fixing thereof is thereby improved.
The radial extension r of the bead is preferably greater than its axial extension a. Fixing to or in a component is thereby improved further and detachment from the component is prevented.
One or more center flanges permit the achievement of a defined installation position without auxiliary components. Thus, for example, a component whose material thickness is less than the axial length of the bush may be arranged between two center flanges.
If one or two end flanges are provided, it is possible, for example, to achieve asymmetric fixing of the component. Several components may also be connected with one bush, if the bush comprises a corresponding number of flanges, whether centre and/or end flanges.
When used with components of resilient materials, the centre flange serves in fixing, such that additional measures, such as roughening of the outer surface of the bush, are not necessary.
Bearing bushes of this type may be used as an insert for a roller of resilient material, in particular of rubber.
Another use to which a bearing bush with two center flanges may be put is as a pedal bearing system. A pedal bearing system according to the invention is characterised in that the boss and bushes take the form of a bush with two center flanges. The pedal lever is arranged or fixed between the two centre flanges. The advantage of this pedal bearing system consists in the fact that, instead of the conventional three components—a boss and two flanged bushes—only one component is required, namely the bush according to the invention with two center flanges, whereby the production and assembly costs may be lowered.
A bearing bush with at least one center flange and at least one end flange may be used as a bearing system for a flexible joint, in particular for a steering column.
The production method takes as its starting point a bearing bush produced according to conventional methods, which, however, exhibits the peculiarity that the inner surface of the backing is exposed in at least one annular area spaced from the bush ends. The center flange is produced in this exposed area during the production process proper.
As a rule, this prefabricated bearing bush is not provided with the centre flange(s) until subjected to further processing, in the course of which, depending on the use to which it is to be put, it is connected with further components.
This prefabricated bearing bush may also already be provided with one or two end flanges.
The production method is characterised in that such a prefabricated bearing bush is used, the backing of which is exposed in at least one area spaced from the bush ends, in that an internal mandrel is inserted into this bearing bush, in that this bearing bush is held around its outer surface, at least one gap being left opposite to the exposed area, and in that the bearing bush is upset in the axial direction, the material thereby being displaced into the gap to form a flange. If several center flanges are to be produced, a die should be used which comprises an appropriate number of gaps, in which the center flanges may be formed.
REFERENCES:
patent: 1793874 (1931-02-01), Skillman
patent: 3351999 (1967-11-01), McCloskey
patent: 4048703 (1977-09-01), Lehnhart
patent: 4231623 (1980-11-01), Kaufman
patent: 4796457 (1989-01-01), Iijima
patent: 841087 (1949-07-01), None
patent: 195349 (1962-03-01), None
patent: 2406460 (1975-08-01), None
patent: 1 458 047 (1976-12-01), None
Damour Philippe
Deusser Stephan
Kirchhof Klaus
Footland Lenard A.
Glyco-Metall-Werke Glyco B.V. & Co. KG
Reising Ethington, Barnes, Kisselle, Learman & McCulloch, P.C.
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