JPH0116890B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hardening method for hardening an outer ring of a constant velocity universal joint using steel balls for power transmission.

Generally, in constant velocity universal joints like the one above,
The spherical cage contact surface formed on the inner peripheral surface of the outer ring and the surface of steel guide grooves formed in the axial direction at equal angular intervals on this cage contact surface are induction hardened to improve durability. However, if the hardened layer is made too thick, the thickness of the unhardened layer becomes thin and the fatigue resistance decreases, so the thickness of the hardened layer cannot be made very thick. In particular, as shown in FIG. 1, one rotating shaft 1 and the other rotating shaft 2 form a predetermined angle θ, and the upper steel ball 3 is located on the end surface side of the guide groove 5 formed on the inner peripheral surface of the outer ring 4. When the rotating shaft 1 or 2 rotates while being located at the end 5a, the guide groove 5
Since a load in the rotational direction acts intermittently on the end 5a, if the thickness of the quenching near the end 5a is thick, the end 5a is likely to suffer fatigue failure, which may reduce the durability of the joint. Become.

For this reason, the thickness of the hardened layer 6 on the surface of the guide groove 5 is preferably made thinner as it approaches the end 5a, as shown in FIG. As shown in FIG. 3, the hardened layer near the end 5a becomes thicker than the other parts, so such a hardening method cannot be used.

In addition, as shown in FIG. 4, hardening is performed with an annular metal ring 7 attached to the end surface of the outer ring 4, so that heat from the outer periphery of the end portion 5a is absorbed mainly by the endothermic action of the metal ring 7. A hardening method has been proposed in which the thickness of the hardened layer near the end portion 5a is reduced.
In this device, the annular metal ring 7 acts as a low-resistance single-turn secondary coil, and much of the high frequency energy radiated from the heating coil 8 is absorbed by the metal ring 7. This method has the disadvantage that the excitation power must be considerably higher than that of general heating methods, and the cost required for the hardening process is high.

In view of these conventional problems, the present invention is designed to absorb the heat on the outer periphery of the end portion 5a without absorbing the high frequency energy radiated from the heating coil. I will explain based on this.

In FIG. 5, reference numeral 10 indicates an outer ring of a constant velocity universal joint formed at one end of the shaft 10a, and this outer ring 10
A spherical cage contact surface 11 and a plurality of guide grooves 12 extending in the axial direction at equal angular intervals on the cage contact surface 11 are formed inside the cage.

Reference numeral 20 denotes a heat absorbing body that constitutes a hardening head together with a hardening coil 23. A shingle-shaped base 21 of this heat absorbing body 20 is made of a non-metallic insulating material, and a hardening coil is placed in the center of this base 21. 23 is supported. In addition, 19 is a heat absorbing body 20
The piston rod of the drive cylinder (not shown) that advances and retreats is shown.

The forward side side of the base 21 is made of steel, brass,
The rod-shaped leg portion 22 is made of a metal material with high thermal conductivity and low resistivity, such as aluminum.
The same number of guide grooves 12 are provided protruding parallel to the central axis of the outer ring 10 at equal angular intervals. The width of the leg portion 22 is set to be wider than the width of the guide groove 12 by a predetermined amount, as shown in FIG.
It is set slightly thicker than the distance between the bottom of the outer ring 10 and the outer peripheral surface of the outer ring 10. Further, a notch 22 a having an arc shape is formed inside the tip of the leg portion 22 , and when the heat absorbing body 20 is moved to the forward end, the axial end surface of the notch 22 a touches the outer circumference of the end surface of the outer ring 10 . come into contact with

On the other hand, the heating coil 23 is made of a copper pipe, and this heating coil 23 has a coil portion 23a located inside the outer ring 10 at the forward end.
and a straight portion 23b that supplies the output from the high frequency power source 24 to the coil portion 23a. As shown in FIG. 8, a large number of holes 25 for jetting cooling water are bored in the coil portion 23a.

Next, to explain the hardening operation using the hardening apparatus having the above configuration, first, the shaft 10a is rotated to position the outer ring 10 at a predetermined angular phase, and the guide groove 12 is rotated.
After matching the angular position of the leg portion 22 with the angular position of the leg portion 22, the heat absorbing body 20 is moved forward, and the distal end surface of the leg portion 22 is engaged with the end surface of the outer ring 10. Thereafter, the high frequency power supply 24 is operated for a predetermined period of time to heat the inner circumferential surface of the outer ring 10, and when the heating is completed, cold water is force-fed into the heating coil 23 and cooled water is spouted from the spout hole 25, and the outer ring 10 is heated. The inner peripheral surface is rapidly cooled to complete the hardening.

In this way, when induction hardening is performed with the tip end surface of the leg portion 22 of the heat absorbing body 20 in contact with the vicinity of the guide groove 12 forming portion of the end surface of the outer ring 10, the heat on the outer periphery of the end portion 12a on the end surface side of the guide groove 12 is is absorbed by the leg portions 22, so the thickness of the hardened layer of the guide groove 12 gradually becomes thinner as it approaches the end portion 12a, and the thickness of the unhardened layer near the end portion 12a is increased. Can be done.

In addition, since the heat absorber 20 does not act as a secondary coil, high frequency energy is not absorbed by the heat absorber during heating, and the high frequency energy emitted from the heating coil 23 is effectively used to heat the inner peripheral surface of the outer ring. Available for

Note that in the above embodiment, the heat absorbing body was constructed by protruding legs parallel to the central axis on the side surface of the base having approximately the same diameter as the outer ring 10; The heat absorbing body may be constructed by using the base as a base and having legs projecting in the radial direction from the inner circumferential surface of the base.

As described above, in the present invention, a heat absorbing body having a non-metallic base with a base of a good thermal conductor protruding from the base is disposed so that the tips of the legs abut near the guide groove forming part of the outer ring end surface. Since the cage contact surface and the guide groove are induction hardened at the same time, not only can the hardened thickness of the guide groove become thinner as it approaches the end face, but also the high frequency energy radiated from the heating coil can be applied to the heat absorber. This has the advantage that the high frequency energy radiated from the heating coil can be effectively used for heating the cage contact surface and the guide groove.

[Brief explanation of drawings]

Figure 1 is a diagram showing the state when a pair of rotating shafts of a constant velocity universal joint form a predetermined angle, Figure 2 is a diagram showing a preferred hardened state of the guide groove formed on the inner circumference of the outer ring, Figure 3 shows the hardened state by general induction hardening, Figure 4 shows the conventional induction hardening method, Figures 5 to 8 show examples of the present invention, and Figure 5 shows the hardening state. A diagram showing the state in which the head is coupled to the outer ring of the constant velocity universal joint. Figure 6 is a cross-sectional view taken along the line - - of Figure 5. Figure 7 is a cross-sectional view taken along the line - - of Figure 5. The figure is an enlarged view of the surface of the coil portion 23a in FIG. 5. DESCRIPTION OF SYMBOLS 10... Outer ring, 11... Cage contact surface, 12... Guide groove, 20... Heat absorber, 21... Base, 22... Leg, 2
3...Heating coil.

Claims (1)

[Claims] 1. A method of hardening a spherical cage contact surface formed on the inner peripheral surface of an outer ring of a constant velocity universal joint, and a plurality of guide grooves formed in the axial direction at equal angular intervals on this cage contact surface, Legs made of a good thermal conductor are protruded from a non-metallic base at angular intervals equal to the angular intervals to constitute a heat absorbing body, and the ends of the legs are connected to the outer ring end surface. The guide groove is disposed so as to be in contact with the vicinity of the end of the guide groove, and in this state, the cage contact surface and the guide groove surface are induction hardened by a heating coil disposed inside the outer ring. Hardening method for quick adjustable joints.