Bearing shell and method for its production

The invention provides a bearing sleeve and method of forming a sleeve having at least one window whose edge boundary has a first apex region and a second apex region situated opposite one another in the sleeve longitudinal direction. In order to prevent chip formation when pressing the bearing sleeve into a bearing housing, it is provided that, in at least one apex region, the edge boundary forms an angle α≠90° with the sleeve longitudinal direction of the bearing sleeve.

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. national phase application under 35 U.S.C. §371 of International Application No. PCT/DE06/02237 filed Dec. 13, 2006, which claims priority to DE 10 2005 060 637.7 filed Dec. 13, 2005, both of which are herein incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to a bearing bush having at least one aperture whose edge boundary has a first apex and a second apex situated opposite one another in the bush longitudinal direction. The invention further relates to a particular use of said bearing bush, and a manufacturing method.

2. Related Art

Such bearing bushes are used, for example, in brake calipers of motor vehicles. For a combined parking brake-service brake, the bearing bush must have at least one aperture through which a corresponding pin may engage in the bush when the parking brake is actuated.

When these bushes are incorporated into the housing, which may be made of aluminum, for example, the sharp-edged boundary of the aperture may produce chips which may impair the function of the bearing. This drawback occurs in particular for bearings having a butt edge, since when the bushing is pressed in, partial surfaces of the bearing on one side are compressed, and on the opposite side are spread apart. As a result of this deformation of the bearing bush, chip formation is facilitated in particular when the aperture is located in the region of the partial surfaces.

SUMMARY OF THE INVENTION

The object of the invention, therefore, is to provide a bearing bush having an aperture, for which no chip formation occurs when the bearing bush is incorporated into a bearing housing made of a softer material.

This object is achieved by use of a bearing bush, characterized in that the edge boundary in at least one apex forms an angle α≠90°, preferably α<90°, with respect to the longitudinal direction of the bush.

Pressing in the bearing bush causes chip formation, in particular in the rear section of the edge boundary in the insertion direction. When, in only a single apex region, the edge boundary of the aperture has no sections which form an angle α=90° with respect to the longitudinal direction, i.e., is perpendicular to the longitudinal direction, the insertion direction must be taken into account when the bearing bush is pressed in. Since even slight deviations from 90° are sufficient to reduce or prevent chip formation, the design of the aperture according to the invention for installation generally is not readily apparent. In order to make the mounting direction apparent in such cases, supplementary measures such as marking the bush, etc. may be practical.

To avoid these supplementary measures, it is advantageous when the edge boundary of the aperture forms an angle α≠90° with respect to the longitudinal direction of the bush in all sections. The bush may be pressed into the housing in both insertion directions without the formation of chips.

The angle α is preferably selected as follows:

45°<α<90°, in particular 60°<α<90°, and

45°<α<85°, in particular 60°<α<85°.

The aperture may have a circular, oval, or polygonal design.

The aperture preferably tapers in the longitudinal direction in at least one apex, and the edge boundary advantageously tapers off in the apex region. At the tip, due to unavoidable rounding the edge boundary at one point necessarily has an angle α=90°. However, such infinitesimal regions are negligible. It is important that no sections of the edge boundary of greater length are perpendicular to the longitudinal axis.

The aperture is generally circular, since as a rule circular pins are intended to engage in the bush. The circular contour may be maintained when, on at least one apex region, the circular contour is interrupted by an edge boundary which is not perpendicular to the longitudinal direction. It is therefore advantageous when the aperture has a triangular section in the edge boundary for the apex region in question.

The aperture is preferably situated in the region of the partial surfaces. In this embodiment the aperture is preferably formed by two identical recesses in the narrow side of the plate, which is deformed, in particular rolled, with respect to the bearing bush. This embodiment has advantages from a manufacturing standpoint, since the recesses may also be applied when the plates are separated.

In the method for manufacturing a bearing bush having at least one aperture whose edge boundary has a first apex region and a second apex region situated opposite one another in the bush longitudinal direction, wherein the edge boundary forms an angle α≠90° with respect to the longitudinal direction of the bearing bush at least in one apex region,plates are separated from a strip material,when the plates are separated at the sides of the plates forming the butt joint of the bearing bush, in each case at least one recess is punched out which forms the angle α with respect to the plate side(s) at least one end section, andthe plates are subsequently rolled into bushes, and the recesses introduced at the sides of the plates together form at least one aperture at the butt joint.

The cutting of the plate to length and the punching out of the recesses may be performed at the same time. However, it is also possible to first punch out the aperture from the strip material, and then cut the plates to length in the region of the aperture.

One preferred use of the bearing bush is for the bearing of eccentric shafts for combined parking brake-service brakes in motor vehicles. Combined parking brake-service brakes (combination calipers) are used in disk brakes.

DETAILED DESCRIPTION

FIG. 1shows a perspective illustration of a bush or sleeve1having a butt joint20and partial surfaces21a,21b. The bush1also has at any given location a closed aperture or window10having an approximately oval edge boundary11.

The aperture10, viewed in the longitudinal direction3, is centrally positioned in the bush1. However, the aperture10may also be located at any other given position, and may extend, for example, to the end faces4or5. In that case, the aperture10would have a partially open design on the side.

The edge boundary11has two curved sections11a,11bwhich both taper toward one another into apex regions15a,15bsituated in the longitudinal direction3. The particular angle α between the tangent T to the edge boundary11aand the longitudinal direction3is approximately 50° in the embodiment shown here. The aperture10likewise tapers in insertion direction A and in insertion direction B, indicated by the respective arrows. This bearing bush10has the advantage that it can be pressed or pushed, in both direction A and direction B, into the bearing housing without chips being produced through the aperture10when the bearing bush is inserted into the bearing housing.

If the apexes15a,15bin the transition of the boundary sections11a,11bcontain infinitesimal curvatures which in places are perpendicular to the longitudinal axis, no chips are thus produced.

FIG. 2shows a further embodiment having a circular section11c. In the apex region15athis circular contour of the edge boundary11cmerges into two approximately linear sections11a,11bwhich taper toward one another to the apex15a, and thus have no section that is perpendicular to the longitudinal direction3. The two linear sections11a,11btogether form the gabled contour11g. Since such a contour11gis absent in the apex region15b, the bearing bush1must be inserted into the bearing housing in direction A to avoid chip formation.

FIG. 3illustrates a further embodiment of a bearing bush1in which the aperture10has a hexagonal design. The edge boundary11comprises linear sections11athrough11f. The edge boundary sections11a,11band11d,11etaper toward one another into apex regions15a,15b, respectively, so that in this embodiment the angle α is 45°.

FIG. 4illustrates a further embodiment of a bearing bush1having an aperture10with a design corresponding to the edge boundary11inFIG. 1, except that the aperture10is situated in the region of the partial surfaces21a,21b. The aperture10is formed by two equally-sized recesses which are punched out in the end regions of the plate, and is thus formed in the region of the butt joint20after the bush is roll-formed.

As shown inFIG. 5, corresponding recesses33a, bmay be introduced at the narrow ends or sides31,32of the plate30from which the bearing bush1is manufactured. The recesses have end sections34,35contiguous to the plate sides31,32which form the narrow sides of the plate30,30′. These end sections34,35together with the plate sides31,32form the angle α, which is less than 90°.FIG. 5also shows the plate30′ in dashed lines, indicating that the plate is separated from a strip material. The plate30may be separated in the same process step as the introduction of the recess33a, so that an additional process step is not necessary to produce the aperture10.