Thin-Walled Bearing Bushing Produced by Deep Drawing

The present invention is in a thin-walled bearing bushing produced by deep drawing.

There is known a bearing bushing in which a circumferential groove, concentric to the axis of the bearing bushing, is formed in the outer surface of the bottom section of the bearing bushing during deep drawing of the bushing (U.S. Pat. No. 4,377,313). A relatively sharp peripheral edge is formed between the surface of the sleeve section and the outer surface of the bottom section with minimum pressure. In the event a bearing bushing so formed is used to seat pins in universal joints, the face of the pin slides either directly or by way of an intermediate thrust washer placed on the inner surface of the bottom section of the bearing bushing. The axial carrying capacity of this inner surface depends essentially upon the accuracy of shape (evenness) of the inner surface.

The object of the invention is to obtain an improved bearing bushing in which the inner surface of the bottom section of the bushing has a high accuracy of shape (evenness) for obtaining an improved axial load-carrying capacity.

The objects of this invention are achieved by forming the bearing bushing such that the inner surface of the bottom section of the bearing bushing has a highly accurate shape, especially in the radially outer region, so that the bottom section has a large effective carrying capacity for supporting the face of the pin or the pin thrust washer. Thus, dangerous overloads, which may develop by concentrated surface stress at local prominences on the inner surface of the bottom section during operation, are avoided. The structurally determining thickness of the bushing bottom section may be produced with small manufacturing tolerances in the deep drawing process. A uniformly narrow guide slot may be maintained between the inner surface of the bottom section and the opposing face of the pin and guide washer. As such, the pin of the universal joint may be seated in the bearing bushing with little axial play.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects obtained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated a preferred embodiment of the invention.

FIG. 1 shows a longitudinal section through a bearing bushing in a drawing die;

FIG. 2 is a view along line A--A of the outer surface of the bottom section of the bearing bushing of FIG. 1 removed from the drawing die;

FIG. 3 is a longitudinal section through the bearing bushing of FIG. 1 in the installed state;

FIG. 4 is a longitudinal section through a modified bearing bushing in a drawing die;

FIG. 5 is a view along line B--B of the outer surface of the bottom section of the bearing bushing of FIG. 4 removed from the drawing die; and

FIG. 6 is a view of the outer surface of the bottom section of an additional modified bearing bushing.

Referring to the drawings, FIG. 1 shows a thin-walled bearing bushing 1 and a die 2 for making the bearing bushing 1. The bushing 1 is positioned in the bore of the drawing die 2, in which it is produced with the drawing punch 3 and the counterpunch 4. The drawing process, starting from a round blank cut out of band-shaped material, for example, deep-drawing strip steel, is known per se.

The bearing bushing 1 comprises a cylindrical sleeve section 5 and a bottom section 6 closing the sleeve off at one end. A sharp peripheral edge 7 is formed between the surface of the sleeve section 5 and the outer surface of the bottom section 6. In the present case the bottom section 6 of the bushing 1 has an even inner radial surface 8. A fillet having a relatively large radius of cross-section R serves as a transition for the inner surface 8 to the cylindrical bore surface of the sleeve section 5.

A depression 9 (FIG. 2), which is disposed in the vicinity of the peripheral edge 7 and limited radially inward, is pressed axially into the outer surface 10 of the bottom section 6 forming the relatively sharp peripheral edge 7. In the present instance this depression 9 is a groove which is concentric to bushing axis 11 and has an essentially V-shaped cross-section.

The outer surface 10 of the bottom section 6 is also provided with an indentation in the form of circumferential groove 12 displaced radially inward relative to the depression 9 and reducing the wall thickness of the bottom section 6. The groove 12 is concentric with axis 11 of the bearing bushing 1 and has an essentially V-shaped cross-section. The depth 14 of the axial depression 9 of the outer surface 10 of bottom section 6 is greater than the depth 13 of the groove 12. The shape and depth of grooves 9 and 12 are such that the material displacement necessary for formation of an even inner surface of bottom section 6 during deep drawing is ensured.

The depression 9 and the groove 12 are axially impressed on the outer surface 10 of the bearing 1 by corresponding annular projections 16 and 17 of the counterpunch 4 during the deep drawing of the bushing 1 in the drawing die 2 with the centering shoulder 15 for the counterpunch 4. Simultaneously, the flat face of the drawing punch 3 presses against the inner surface 8 so that a smooth, even and accurately shaped inner surface 8 is formed on the bottom section 6 of the bearing bushing 1. A fillet of constant radius R is formed at the periphery between the sleeve section 5 and the bottom section 6.

FIG. 3 depicts bearing bushing 1 mounted by a firm setting within the bore of fork 18 of a universal joint (not shown). The bearing bushing 1 is axially secured at its bottom section 6 by the snap ring 22, which is snapped into a radial annular groove in the bore of the fork 18. Pin 19 of a cross-piece of the universal joint is indicated by broken lines and is seated within a cylindrical roll member 20. The roll member 20 and the flat of the pin 19 are supported by a thin thrust washer 21 of self-lubricating synthetic material on a smooth even inner surface 8 of the bottom section 6. Since this even inner surface 8 does not have protrusions or blemishes, the developed surface stress on the inner surface 8 of the bottom section 6 is uniformly distributed during operation.

FIGS. 4 and 5 show a modified bearing bushing 1, likewise consisting of a cylindrical sleeve section 5 having a bottom section 6 closing off the sleeve on one side. As above, bushing 1 is deep-drawn in the bore of a drawing die 2 with a drawing punch 3 and a counterpunch 4 (FIG. 4). In the present case the counterpunch 4 is formed with three peripherally extending interrupted projections 23 on its face to axially press three radial groove-like depressions 24 onto the outer surface 10 of the bottom section 6. Depressions 24 have a V-shaped cross-section and are disposed in the vicinity of the peripheral edge. The forming of the depressions 24 results in a sharp peripheral edge 7 in the outer radial region. The wall thickness of the bottom section 6 is reduced by an indentation in the form of a concentric circumferential groove 12 having a V-shaped cross-section. The groove 12 is placed radially inward relative to the depressions 24 on the surface of the bottom section 6 of the bushing 1.

The drawing punch 3 has a radially extending flat face 25 which produces an accurately shaped even inner surface 8 on the bottom section 6 of the bearing sleeve 1 by the deep drawing procedure. The fillet between the sleeve section 5 and the bottom section 6 has a constant radius of cross-section R at the periphery.

FIG. 6 depicts outer surface 10 of another embodiment of the invention. Three depressions 24 are disposed in the vicinity of the peripheral edge of the outer surface 10. In this embodiment three peripherally disposed grooved sections 26 are positioned radially inward of the depressions 24, in the outer surface 10 of the bottom section 6. These grooved sections 26 have a V-shaped cross-section and are in each instance located intermediate adjacent depressions 24 at the periphery of the bearing bushing.

The bearing bushings described above may be structurally modified within the scope of the invention. For example, the bottom section of the bearing sleeve may alternatively have, in addition to an even inner radial surface 8, an inner surface concentric to the bushing axis and extending outwardly in a conic section. This conical inner surface may then be slidingly supported on a suitably shaped opposing face of the pin of the universal joint.

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, it being recognized that various modifications are possible within the scope of the invention.