JPH0692070B2 - Ball spherical surface processing method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a ball spherical surface of a ball stud for a ball joint used particularly in a steering system and a suspension system of an automobile.

2. Description of the Related Art In the conventional ball spherical surface processing method, in the step of cutting a ball stud ball head, as shown in FIG. 2, the ball head 103 is cut into a finished spherical shape, After that, the ball head 103 and the spherical surface 104 were rolled and finished in order to increase the surface roughness.

Problems to be Solved by the Invention In the above-described ball spherical surface processing method, the ball stud 101 and the ball head 103 are already formed into a true sphere in the cutting step before the rolling and finishing step. Therefore the ball head
Since the spherical surface 104 and the rolling surface 114 of the rolling roller 113 are completely aligned with each other, there is a problem that the surface roughness does not increase even if a load is increased to increase the surface roughness. That is, the ball stud 101
This is because the equator spherical surface 105 of the ball head 103 in the axial rotation does not have an escape area for the material volume even if it is pressed by the rolling roller 113, and cannot be deformed like a rigid body. Therefore, the rolling load is not applied to the spherical surface 107 near the end, and the surface roughness does not increase.

Means for Solving Problems The ball head of the ball stud is preliminarily formed into a spherical shape so that the diameter in the axial direction is a minute long diameter, and then a rolling process is performed to correct the minute long diameter of the spherical surface of the ball head. .

In the rolling finishing process, the spherical surface near the end of the ball stud ball head comes into contact with the rolling surface of the rolling roller before the spherical surface near the equator and is corrected while receiving pressing force, and then near the equator. The spherical surface is pressed against the rolling surface of the rolling roller.

EXAMPLES Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial cross-sectional plan view showing a rolling process according to an embodiment of the present invention. The left half shows the state at the start of rolling and the right half shows the state after the end of rolling.

1 is a ball stud with a handle, which has a ball head 3 at one end.

Reference numerals 13 and 13 denote a pair of rolling rollers having spherical rolling surfaces 14 and 14, respectively.

Next, a method of processing the spherical surface of the ball stud 1 will be described.

First, as shown in the left half of FIG. 1, the ball head 3 is molded so that the diameter in the axial direction thereof is a conical shape with a slight major axis.
The forming method includes cutting, forging and casting.

If the radius of the ball head 3 after rolling is L, the equator radius 6
Is the length L, and the radius 8 near the end is the length L + b.

The size of b is 10 when the diameter of the ball head 3 is 20 mm to 40 mm.
μ to 15 μ is suitable. If b is smaller than 10 μ, the surface roughness of the spherical surface 7 near the end does not increase, as in the conventional case. If the value of b is larger than 15 μ, the radius 8 near the end cannot be corrected to the length L by rolling.

Next, the ball stud 1 and the spherical surface 4 of the ball head 3 formed in a jujube shape are roll-finished.

That is, as shown in the left half of FIG. 1, the rolling rollers 13, 13 are rotated, and the ball stud 1 ball head 3 is brought into contact with the rolling surfaces 14, 14 of the rolling rollers 13, 13 which are rotating. Press.

As described above, since the ball head 3 is formed so that the radius 8 near the end is larger than the radius 6 near the equator in the forming step, the rolling surfaces 14 and 14 of the rolling rollers 13 and 13 have the same shape. The spherical surface 7 near the end contacts the spherical surface 5 near the equator. Therefore, the spherical surface 7 near the end portion is corrected by the pressing force of the rolling rollers 13, 13 and then the spherical surface 5 near the equator is corrected.

After the completion of rolling, as shown in the right half of Fig. 1, the rolling roller 1
Rolled surfaces 14, 14 of 3, 13 and ball head 3 spherical surface 4 coincide.

That is, after the rolling is completed, the length of the radius 10 near the equator and the length of the radius 12 near the end are both L. The surface roughness of the spherical surface 9 near the equator and that of the spherical surface 11 near the end are similarly increased.

As described above, according to the present invention, in the rolling finishing step, the spherical surface near the end of the ball stud ball head comes into contact with the rolling surface of the rolling roller before contacting the rolling surface of the rolling roller before the spherical surface near the equator. The spherical surface near the equator is pressed against the rolling surface of the rolling roller under pressure, and the surface roughness increases even at the spherical surface near the end of the ball stud ball head. Increase uniformly.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention and is a partial sectional plan view showing a ball stud and a rolling roller in a rolled state. FIG. 2 is a partial sectional plan view showing a ball stud and a rolling roller in a rolled state by a conventional method. (Explanation of symbols) 1 …… Ball stud. 3 ... ball head. 4 ... spherical surface.

Claims (1)

[Claims] 1. A rolling process in which the ball head 3 of the ball stud 1 is formed into a spherical shape in advance so that the diameter in the axial direction thereof becomes a minute long diameter, and then the minute long diameter of the ball head 3 spherical surface 4 is corrected. A method for processing a spherical surface of a ball, which comprises: