JPH031620Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an outer race of a rebro joint.

(Prior Art) A rebro joint, which is a telescopic constant velocity joint used in the automobile industry, is composed of a plurality of balls, usually six balls, a cage for holding the balls, an outer race and an inner race.
The outer race and the inner race have V-shaped ball grooves, that is, are arranged symmetrically with each other at equal angles with respect to the rotation axis.

This ball groove rubs violently with the ball, so it needs to have sufficient wear resistance.The outer race and inner race, especially the outer race, are formed by machining and plastic working, and then the ball groove contacts the ball. The entire inner surface including the grooves is hardened by means such as high frequency heating.

(Problem to be solved by the invention) However, the outer race is usually manufactured using steel. The structure of the steel material used in this case is a mixed structure of ferrite and pearlite, but when hardened by high-frequency heating, the structure changes to martensite, and at this time the volume expands. Since this volumetric expansion occurs only in the hardened portion, that is, the inner surface of the outer race, the inner surface is deformed and curved, causing the inner diameter and grooves at both axial ends of the outer race to
BBD (Between Ball Diameter) is larger than that at the center of the shaft. In particular, when the ball groove is in the V-shape described above, the deformation due to strain becomes complicated, so it is very difficult to correct it by cutting, etc. after quenching.

For this reason, in the conventional outer race for rebro joints, the central part of the groove was raised compared to both ends, resulting in a deviation from a true cylinder (height of the bump), or cylindricity, of about 0.10 to 0.15 mm, resulting in a decrease in groove accuracy.
Noise and decreased durability caused by this quenching distortion have been problems.

The present invention is intended to solve the above-mentioned problems in the prior art, and its purpose is to provide an outer race for a rev joint that has improved groove precision, less noise, and excellent durability.

(Means for Solving the Problems) That is, the outer race of the rebro joint of the present invention is symmetrical with respect to the axial center point of the outer circumferential surface, and the depth of the cross section is at the axial center point. At least one recess is formed around the entire circumference in the circumferential direction so that the recess is the deepest and gradually remains toward both ends.

The size, shape, position, and other properties of the recess formed in the center are selected according to the size, shape, wall thickness, heat treatment conditions, etc. of the outer race so that the groove accuracy after heat treatment is within a specified range. do.

Although it is easier to process the number of recesses by forming one groove over the entire circumference, a plurality of recesses may be formed. Further, in the case of one groove, the cross-sectional shape is preferably semicircular, semi-elliptical, triangular, etc., and in the case of two or more grooves, rectangular, trapezoid, etc. can be used in addition to the above-mentioned shapes. or,
When a plurality of recesses are formed, recesses having various sizes, shapes, etc. may be combined.

A commonly used method such as cutting or plastic working can be used to form the recess.

(Function) In the outer race of the present invention, the wall thickness on the axial end face side, where the opening end is more likely to expand due to heat treatment distortion, is made larger than the center part, thereby increasing the restraining force, thereby suppressing distortion. In addition, at least one recess is formed so that the depth of the cross section is deepest at the midpoint in the axial direction and gradually becomes shallower toward both ends, so the shape and number of the recesses can be optimized. By selecting this, stress concentration at the corners of the recess can be eliminated or reduced, so that the rigidity of the entire outer race can be maintained to a sufficient level without reducing it too much.

(Example) In the following example, the present invention will be explained in more detail based on the drawings. Note that the present invention is not limited to the following examples.

Example 1 Figure 1 shows outer lace 1 of Example 1 of the present invention.
The front view shown in the axial direction is shown. In the figure, 2 is a cross groove and 3 is a connecting hole. Further, FIG. 2 is a sectional view taken along the - line in FIG. 1. As is clear from FIG. 2, this example has three different widths and depths.
This is an example in which a book groove-shaped recess 4 is formed. Also, the third
The figure shows an enlarged cross-sectional view of a portion A surrounded by a dashed line in FIG. 2.

Embodiment 2 FIG. 4 shows an enlarged sectional view similar to FIG. 3 of Embodiment 2 of the present invention. This embodiment is an example in which an arc-shaped recess 5 is formed.

Comparative Example: FIG. 5 shows a sectional view corresponding to FIG. 2 of an example of a conventional outer lace. Conventionally, the thickness of the circumferential portion was uniform, resulting in large distortions after heat treatment.

Comparison of accuracy after heat treatment: Figure 6 shows the change in axial accuracy of the conventional and inventive outer races before and after heat treatment. As is clear from the figure, the outer race of the present invention has less distortion after heat treatment than the conventional one, and has greatly improved accuracy, with the amount of change due to distortion being about 1/3 of that of the conventional one. Ta.

Durability comparison test: A rebro joint using the outer lace of the present invention and a rebro joint using a conventional outer lace were attached to a testing machine and their durability (durability time) was compared under the same conditions. The durability is improved by about 1 to 30% compared to
Furthermore, the noise level during the test was also significantly reduced.

(Effects of the invention) As mentioned above, the outer race of the reversible joint of the invention has a recess with a predetermined shape in the axial center of the outer peripheral surface and has a thinner wall thickness than other parts, which reduces the restraining force on the end surface side. The precision of the ball grooves has been improved because the heat treatment distortion has been suppressed.

In addition, this has reduced the deviation of the load applied to the groove at various locations in the axial direction, improving the durability of the product, the rebro joint, and reducing noise.

Furthermore, since the weight of the reversing joint can be reduced, it has the effect of increasing the reliability and commercial value of products such as vehicles that use the reversing joint.

[Brief explanation of the drawing]

Fig. 1 is a front view of Embodiment 1 of the outer lace of the present invention as seen from the axial direction, and Fig. 2 is the − of Fig. 1.
3 is an enlarged sectional view of part A surrounded by the dashed line in FIG. 2, FIG. 4 is an enlarged sectional view similar to FIG. 3 of the second embodiment of the present invention, and The figure is a cross-sectional view corresponding to FIG. 2 of an example of a conventional outer race, and FIG. 6 is a graph showing changes in axial accuracy of the conventional outer race and the present invention outer race before and after heat treatment. In the figure, 1... Outer race, 2... Cross groove, 3... Connection hole, 4, 5... Recess.

Claims (1)

[Scope of utility model registration request] At least one recess is formed in the axial center of the outer circumferential surface symmetrically with respect to the axial center, such that the depth of the cross section is deepest at the axial center and gradually becomes shallower toward both ends. The outer lace of the rebro joint is characterized by being formed over the entire circumference in the circumferential direction.