JP2016023690A - Thrust bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thrust bearing in which rust is not generated even if caulking a peripheral part of a case which uses a trivalent-chromate treated steel plate.SOLUTION: In a trivalent-chromate treated case 8b which is applied with trivalent chromate treatment on a surface, a notch is formed at a lower end of a peripheral wall 7b of the case, and a groove 15 is formed at an internal peripheral side of a root portion of left and right peripheral walls 7c of the notch by grinding. An external peripheral face of the peripheral wall 7b of the case 8b is protected by a cylindrical die after assembling a thrust bearing, the tapered die is pressed to a portion of the peripheral wall 7c of the case 8b without rotating it in a state that swelling to an outside diameter side caused by caulking is prevented, and a caulked part 18 is formed by bending a portion which is thinned in thickness by the groove 15.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thrust bearing used for a suspension of an automobile or the like, and more particularly to a kingpin thrust bearing.

  The thrust bearing shown in FIG. 5 is a conventional thrust bearing used for a kingpin portion of an automobile or the like. In this thrust bearing, a plurality of rolling elements (balls) 5 are interposed between raceway grooves 3 and 4 formed on opposing surfaces of the shaft washer 1 and the housing washer 2, respectively. A case 8 comprising an end face 6 and a peripheral wall 7 is fitted to the shaft washer 1, and the outer peripheral surfaces of both washer disks 1 and 2 are covered by the peripheral wall 7. A seal member 10 is fitted on the outer periphery of the housing washer 2, and a contact seal portion capable of relative rotation is formed between the seal member 10 and the peripheral wall 7 of the case 8. Further, by the caulking portion 9 provided at the peripheral portion of the peripheral wall 7, each washer 1, 2 and the rolling element 5 are integrated in an inseparable state while allowing relative rotation of the shaft washer 1 and the housing washer 2. The structure is easy to handle. An O-ring seal member 11 is interposed between the end surface 6 of the case 8 at the corner portion of the inner diameter surface of the shaft washer 1.

JP 2007-309352 A JP 09-206672 A

  By the way, the thrust bearing used in such a kingpin portion is required to have a rust prevention performance because the outer peripheral surface is directly exposed to muddy water in a vehicle-mounted state, and to provide a mechanism for preventing separation of the washer. The crimped portion 9 is formed by press working from a plated steel plate, and the diameter of the crimped portion 9 is reduced by rolling caulking. As the plated steel plate used as the material of the case 8, conventionally, a deep-drawn steel is used as a base metal, which is galvanized and then chromated with hexavalent chromium has been used. Hexavalent chromium has good repairability of the chromate film, and since the periphery of the case 8 is crimped, the chromate film was repaired and the case was not easily rusted even when the roller and the case surface were rubbed many times.

However, the use of hexavalent chromium in automobile applications has been banned due to the effect of the ELV directive (End-of Life Vehicles Directive), and recently, trivalent chromate has been used for chromate treatment of plated steel sheets. Since trivalent chromate is brittle and easy to peel off, and the chromate film has poor repairability, the case using a trivalent chromate-plated steel sheet can maintain rust-proof performance by press forming, but shrinking by rolling caulking. The chromate layer in the diameter part (the part in contact with the roller) is destroyed, and white rust (zinc hydroxide or basic zinc carbonate) is likely to be generated.
The white rust itself is due to the sacrificial anticorrosive effect of zinc and contributes to the rust prevention of the base metal, but it is gradually washed away by water and gradually depleted of zinc, exposing the deep drawn steel as the base metal. And lead to red rust.

  As a countermeasure against this problem, after rolling and caulking, a top coat is applied to protect the trivalent chromate film, or a rust preventive paint containing chromic acid as disclosed in Patent Document 2 is applied. However, when these measures are taken, it is necessary to degrease before construction, and it is difficult to construct the thrust bearing after assembly.

As a solution to the above-mentioned problem, the applicant considered that the trivalent chromate film should be protected by initially eliminating the caulking itself, and as shown in FIGS. 6 and 7, a locking groove 12 is formed on the inner diameter side of the case 8a. Although it was considered that the outer and inner rings were not separated by cutting by turning and fitting a locking ring 13 made of spring steel or resin there, there were many dimensional restrictions and it was difficult to implement for the following reasons.
Reason 1: Considering the automatic insertion of the locking ring 13 by an assembly machine, since the outer diameter side of the locking ring 13 needs to be inclined, the cross-sectional shape of the locking ring 13 is circular or rhombus The radial width of the cross section must be less than the dimension b in FIG. In order to stabilize the posture of the locking ring 13 in the locking groove 12, the locking ring 13 needs to be buried in the locking groove 12 about half, so that the locking ring inner diameter side after the locking ring is mounted. The amount of protrusion from the inner diameter of the case was not so large, and a sufficient effect of non-separation of the outer and inner rings could not be obtained.
Reason 2: Considering the automatic insertion of the locking ring 13 by the assembly machine, in order for the locking ring 13 carried to the lower end of the case to fit into the locking groove 12 as it is, the lower end of the locking groove 12 and the lower end of the case The distance a needs to be less than half of the axial dimension φd of the locking ring 13, but the vicinity of the lower end of the peripheral wall 7 a of the case 8 a is weak and difficult to cut the locking groove 13 accurately. It was.
Reason 3: The locking ring 13 has a reduced diameter and is attached to the locking groove 12 so that it has a C-shaped chip shape. However, the cut portion is not caught when passing through an automatic insertion guide (not shown) of the assembly machine. If the locking force is lowered so that the locking force after insertion into the locking groove 12 is insufficient, the thrust bearing used for the king pin portion disposed under the suspension spring is also subjected to an impact load. The stop ring 13 was easy to fall.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a thrust bearing that does not generate rust even when a peripheral portion of a case using a trivalent chromate plated steel plate is caulked.

In order to solve the above problems, the present invention has the following configuration.
A rolling element is interposed between the raceway grooves formed on the opposing surfaces of the shaft washer and the housing washer, respectively, and a case composed of an end face and a peripheral wall is fitted to the axial washer, and the both washer are supported by the peripheral wall. A seal member is fitted to the outer periphery of the housing washer, and a contact seal portion that is relatively rotatable is formed between the seal member and the peripheral wall of the case, and is provided on the peripheral wall. In the thrust bearing that makes it impossible to separate the two washer and the rolling element while allowing the relative rotation of the shaft washer and the housing washer by the crimped portion,
The case is formed of a plated steel plate having a trivalent chromate surface, and has a notch at the end of the peripheral wall.

  With the above configuration, even if the case made of a plated steel plate whose surface is trivalent chromate is caulked, the chromate film is maintained to prevent white rust from being generated and the rust prevention performance of the case is not impaired.

It is sectional drawing of the thrust bearing which concerns on the Example of this invention. It is a principal part enlarged view of FIG. FIG. 3 is a side view of FIG. 2. It is a figure explaining the crimping process of the Example of this invention. It is sectional drawing of the conventional thrust bearing. It is sectional drawing of the thrust bearing of a prior invention. It is a principal part enlarged view of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. The feature of the present invention is that the structure of the case has been devised, and the structure and operation of the other parts are the same as the conventional structure shown in FIG. The overlapping description will be omitted, and the structure and operation of the case, which is a characteristic part of the present invention, will be described in detail below.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a sectional view of a thrust bearing showing an embodiment of the present invention. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a side view of FIG. FIG. 4 is a diagram illustrating the caulking process according to the embodiment of the present invention.

  A case 8b made of a plated steel plate whose surface is trivalent chromate is provided with a notch 14 at the lower end portion of the peripheral wall 7b, and is turned on the inner peripheral side of the root portion of the left and right peripheral walls 7c of the notch 14. The groove portion 15 is provided. The reason why the groove portion 15 is turned is that if this portion is thinned by stamping, the portion is hardened and becomes difficult to bend.

  After the thrust bearing is assembled, as shown in FIG. 4, the thrust bearing is turned over and the outer peripheral surface of the peripheral wall 7b of the case 8b is protected by a cylindrical die 16 to prevent swelling to the outer diameter side by caulking. In this state, the taper mold 17 is pressed against the peripheral wall 7c of the case 8b without rotating, and the thinned portion is bent by the groove 15 to form the crimped portion 18. By processing in this way, the contact between the outer peripheral portion of the caulking portion 18 of the case 8b and the taper die 17 is at the same level as in press molding (not to be rubbed many times like rolling caulking) The chromate film is maintained to prevent the occurrence of white rust, and the rust prevention performance of the case 8b is not impaired.

  The notch portion 14 is attached at the blank stage when the case 8b is pressed, and a flower-shaped blank material is drawn into a U-shaped cross section, and the center of the bottom plate portion is punched to obtain a case shape. This processing method is the same as the conventional case 8 (see FIG. 5) except that the blank is cut into a flower shape. At the time of caulking, the outer peripheral portion of the caulking portion 18 that comes into contact with the taper die 17 is a press working shear surface on which no plating is placed. For this reason, the case 8b is not deteriorated in rust prevention performance due to the caulking process, and the rust prevention performance is not inferior to the conventional case. In addition, although the notch part 14 and the surrounding wall 7c are made into the substantially square shape, for example, it is good also as a shape which expands a notch in the root part of the surrounding wall 7c, and is easy to bend.

  In this embodiment, the thrust bearing used for the kingpin portion is exemplified. However, the thrust bearing for the kingpin is designed to generate a load to be supported and a starting torque necessary to prevent a resonance phenomenon of an axle called shimmy. In addition to balls, cylindrical rollers and tapered rollers are also used as rolling elements. Further, when a large starting torque is required, a hollow disc-like sliding plate may be sandwiched between the outer and inner rings instead of the rolling elements. The caulking method of the present invention is applicable to any type of king pin thrust bearing.

DESCRIPTION OF SYMBOLS 1 Axis washer 2 Housing washer 3, 4 Track groove 5 Rolling body 6 End surface 7, 7a, 7b, 7c Peripheral wall 8, 8a, 8b Case 9 Caulking part 10, 11 Seal member 12 Locking groove 13 Locking ring 14 Cutting Notch portion 15 Groove portion 16 Die 17 Taper type 18 Caulking portion

Claims (1)

A rolling element is interposed between the raceway grooves formed on the opposing surfaces of the shaft washer and the housing washer, respectively, and a case composed of an end face and a peripheral wall is fitted to the axial washer, and the both washer are supported by the peripheral wall. A seal member is fitted to the outer periphery of the housing washer, and a contact seal portion that is relatively rotatable is formed between the seal member and the peripheral wall of the case, and is provided on the peripheral wall. In the thrust bearing that makes it impossible to separate the two washer and the rolling element while allowing the relative rotation of the shaft washer and the housing washer by the crimped portion,
The thrust bearing according to claim 1, wherein the case is formed of a plated steel plate having a trivalent chromate surface, and a notch is provided at an end of the peripheral wall.

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