JPS58133318A - Method for applying high frequency hardening to end surface of machine parts having different radii around axial line thereof - Google Patents

Abstract

PURPOSE:To enable hardening imparting uniform hardness and generating no quenching crack, in applying high frequency hardening to the end surfaces of machine parts having different radii around the axial line thereof, by a method wherein ring like grooves are formed to the end surfaces of machine parts and high frequency hardening is applied to the inner side surfaces thereof. CONSTITUTION:Ring like grooves 3 are provided to both end surfaces 2 of the clutch hub for an automobile having each different dimensions such as (a), (b), (c), (d) or (e) and, in this state, high frequency coils are arranged so as to be opposed to respective end surfaces 2 to heat the same and, when the temps. of the inner surfaces of the ring like grooves in the end surfaces 2 reach 850- 900 deg.C, oil hardening is carried out. Because uniform temp. distribution can be assured over the inner surfaces of the ring like grooves 3 during high frequency heating by said ring like grooves, uniform hardness distribution is obtained over the total inner side surfaces after hardening as well as the hardening free from quenching crack or dimensional change.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for induction hardening end faces of mechanical parts having different radii around an axis.

In general, mechanical parts with different radii around the axis include various gears, cams, and transmission parts such as clutch pubs. Induction hardening treatment has been applied. That is, to specifically explain one of these mechanical parts using an automobile clutch hub as an example, this automobile clutch hub is shown in a front view in FIG. 1 and along line I-1 in FIG. As shown in the cross-sectional view, a required number of notches 1 (three in this example) are provided along the circumference with the axis as the center and the radius is smaller than other parts.

Therefore, when induction hardening is applied to the circular surface portion of the end surface 2 shown by the dotted line, the temperature of the surface portion where the notch 2 is located is higher than that of other surface portions when the end surface is heated by high frequency heating because the wall is thin. is reached and quenching is carried out in this state, so the hardness of the surface with the notch is not significantly higher than that of the other surface, but the quenched surface becomes the surface shown by the two-dot chain line. . When induction hardening is applied to the end faces of mechanical parts that have different radii around the axis, not only is it impossible to reliably harden a given surface area, but the hardness distribution on the hardened surface becomes uneven. Furthermore, problems such as quench cracking and dimensional deformation occur due to uneven temperature distribution during heating.

Therefore, the present inventors conducted research to solve the problems that occur when induction hardening is applied to the end faces of mechanical parts that have different radii around the axis as described above.
The end face has the required diameter and width.

When an annular groove of a required depth is formed and induction hardening is applied to the inner surface of the annular groove, a uniform temperature distribution is ensured on the inner surface during induction heating by the annular groove, so that after quenching, The inventors have found that the inner surface has a uniform hardness distribution over the entire surface, and that the occurrence of quench cracking and dimensional deformation is significantly suppressed.

This invention has been made based on the above findings, and will be specifically explained below using Examples.

Embodiment It has the shape shown in the front view in FIG. 3 and the cross-sectional view taken along the line ■-■ in FIG.
: 29.51g, C: 31.8h, d:
25.51i.

e: JPMA-8MF4 with dimensions of 12.0m+1
Inner diameter: 48.5 on both end surfaces 2 of clutch hub for automobiles manufactured by Seed.
Dragon X width: 2.511+71X depth: 2. O and L annular grooves 3 are provided respectively, and in this state, a high frequency coil is placed facing each end face 2 and heated, so that the temperature of the inner surface of the annular groove 3 on the end face reaches 850 to 900°C. The method of the present invention was carried out by oil quenching at the point of time. Further, for the purpose of comparison, a comparative method was carried out under the same conditions except that the annular groove was not formed. The Vickers hardness at points A-F of the automobile clutch hub after implementing both methods was measured. The results of this measurement are shown in the table below as an average of five values.

From the results shown in the table above, the method of the present invention has very little variation in hardness distribution and uniform hardening, whereas the comparative method has significant variation in hardness distribution and is not good. It is clear that hardening cannot be expected. In addition, when we measured the maximum radius of five clutch hubs of two types after induction hardening using the method of the present invention and the comparative method, we found that the comparative method had a dimensional error of ±0.05 mm. In the method of the present invention, ±0.
Only a small dimensional error occurred. In addition, although the above embodiment described an automobile clutch hub,
Of course, similar results can be obtained with various gears and cams.

As described above, the method of the present invention can be applied to transmission parts such as automobile clutch hubs with intermittent notches along the outer circumference, various cams and gears whose outer circumferential surface changes irregularly, etc. This makes it possible to perform good induction hardening on the end faces of mechanical parts that have different radii around the axis without causing quench cracks or dimensional changes.

[Brief explanation of drawings]

Figure 1 is a front view of an automobile clutch hub, Figure 2 is a front view of an automobile clutch hub, and Figure 2 is a front view of an automobile clutch hub.
FIG. 3 is a front view of an automobile clutch hub used in carrying out the method of the present invention; FIG.
The figure is a sectional view taken along the line ■-■ in FIG. In the drawings: 1... Notch, 2... End face, 3... Annular groove. Applicant Mitsubishi Metals Co., Ltd. Agent Tomi 1) Kazuo Figure 1 Figure 3 L Koto 2 Figure 4rJgJ

Claims (1)

[Claims] When applying induction hardening to the end face of a mechanical part having different radii around an axis, an induction hardening method is characterized in that an annular groove is provided in the end face and induction hardening is applied to the inner surface of the annular groove.