JPS6056204B2 - Method for hardening the inner surface of the socket of the outer ring of a constant velocity universal joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of hardening the inner surface of a socket portion of an outer ring of a constant velocity universal joint mainly used in a rotational force transmitting portion of an automobile or the like by high-frequency induction heating.

In general, a constant velocity universal joint represented by Japanese Patent Publication No. 33-1305 has a stem portion 2 on which a running wheel (not shown) is fitted and held, and a bell mouth-shaped socket provided at one end of this stem portion 2, as shown in Fig. 5. An outer ring 1 consisting of a portion 3, an inner ring 5 connected to a shaft 4 as a drive shaft, and an inner ring 5 inserted between the outer ring 1 and the inner ring 5.
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Then, the outer surfaces of the stem portion 2 and the socket portion 3 of the outer ring 1 are hardened by high-frequency induction heating according to the ideal hardening pattern shown by the symbol A in FIG. The surface of the outer ring 1 is also hardened using the ideal hardening pattern indicated by the symbol B in FIGS. 1 and 2, thereby increasing the hardness of the inner and outer surfaces of the outer ring 1. However, in this type of universal joint, in order to maintain the joint's flexibility and rotational force transmission function, it is necessary to interpose a large number of the joint balls 6 between the socket portion 3 and the inner ring 5. Therefore, the inner surface of the socket part 3 is carved with a groove (ball fitting groove) 7 into which the ball 6 fits properly, and the ball 6 existing in this groove 7 is inserted into the inner ring of the socket part 3. It is maintained at a predetermined position between 5 and 5. Therefore, as shown in Fig. 2, the wall thickness of the socket part 3 is thinner at the groove 7 portion, and thicker at the rib 8 portion between the grooves 7, so that the entire wall is very flower-shaped. It has become uneven. Further, the groove 7 is usually carved with a cutter, but at this time, the tip of the cutter hits the inner wall surface of the shoulder portion of the socket 3, so that the groove 7 is carved as shown in FIGS. 1 and 3. Relatively deep pocket 9 is socket shoulder 1? Since it is formed on the inner surface, the wall thickness of the socket shoulder portion 10 is formed to be very thin. Therefore, when high-frequency induction heating is applied to the inside and surface of the socket of the outer ring 1, the hardened layer becomes deeper in the groove 7 compared to its wall thickness, whereas the hardened layer in the rib 8 becomes deeper than its wall thickness. The hardened layer becomes shallow compared to the thickness, and the 6th
As shown in Figure 6, the hardened layer has a non-uniform depth, and in the pocket part 9, the hardened layer is deep compared to its wall thickness, and as shown in Figure 6b, the hardened layer is formed on the outer wall of the socket. (This causes what is called a .degree. pull-out of the cured layer), and the desired cured pattern B as shown in FIGS. 1 and 2 cannot be obtained. As a result, changes in the material structure occur over the entire inner layer of the socket portion 3, leading to a decrease in product strength and resulting in poor heat treatment. The present invention is intended to prevent such inconveniences, and the third
As shown in the figure, the socket part 3 of the outer ring 1 is placed with its opening facing downward, and a surface-hardened coil body 11 for high-frequency induction heating is plunged into the socket part 3 from below. When heating the inner surface of the socket part 3 by applying current to one of the hardened coil bodies 11 while rotating the coil body 11, cooling water 12 is applied to the outer wall surface of the socket outside the socket part 3. , cooling the outer wall surface of the socket.

By doing this, the socket shoulder portion 10 and the groove 7, which are thin-walled portions, are formed.
Since the cooling efficiency of the socket portion corresponding to the rib 8 is higher than that of the other portion, that is, the cooling efficiency of the socket portion corresponding to the rib 8, even if cooling water is sprinkled over the entire socket portion 3, the cooling efficiency of the socket shoulder portion 10 and The outer circumferential surface of the groove 7 is particularly strongly cooled, and the heating rate of the pocket portion 9 and the groove 7 is kept relatively slower than that of other parts, that is, the rib 8, resulting in hardening with a uniform thickness. A hardened layer is obtained, and removal of the hardened layer at the socket 3 is prevented. As a means for applying water to the outer wall surface of the socket part 3, semicircular water jackets 13, 13 are arranged in a ring shape around the socket part 3 as shown in FIG.
It is conceivable to spout the cooling water 12 from the nozzles 14 provided in the group, but at this time both water jets! Yaketsu 13,
The envelopes 14a, 14b of the 13 nozzle groups are configured to intersect the horizontal plane 15 as shown in the figure, and both envelopes 14a, 14b are oriented to which each nozzle 14...
If the intersection 16 is configured to correspond to the thinnest part of the socket, the relative injection amount of cooling water at this intersection 16 is the largest, so the thinnest part of the socket can be cooled most strongly. It is useful.

Further, the same effect can be obtained by changing the diameter of the nozzle 14. As detailed above, the present invention provides surface hardening of the inner surface of the socket part of the outer ring of a constant velocity universal joint to a required depth by high-frequency induction heating, with the J opening of the socket facing downward, and the opening By inserting the quenched coil body from below and applying cooling water directly to the outer wall surface of the socket, the outer wall surface of the socket corresponding to the surface to be quenched of the socket is heated in parallel with the above surface heating operation. The surface heating rate is suppressed to a slow state by cooling the surface.
If the method of the present invention is applied to the socket part to be surface hardened as described in the above embodiment, the socket part is provided with pockets and grooves, and the wall thickness is locally or overall thin.
A hardened layer of uniform thickness is obtained on the inner surface of the flower-shaped socket.
In addition, since it is possible to prevent the so-called "degree pull-out" on the inner and outer surfaces of the socket part of the hardened layer, it is useful in obtaining the ideal hardening pattern as shown in FIGS. 1 and 2, and also prevents product defects. do not have.

Furthermore, since the opening of the bellmouth-shaped socket faces downward, the heating coil is inserted into the opening from below, and the cooling water is applied to the outer wall surface, the cooling water is applied to the inside that is to be quenched. Therefore, concerns about product defects such as uneven baking are further reduced.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams showing the ideal hardening pattern during surface hardening of the outer ring of a constant velocity universal joint, Figure 3 is a sectional view for explaining the method of the present invention, and Figure 4 is an illustration of the outer ring of the FIG. 5 is a schematic diagram of the water application means, FIG. 5 is a cross-sectional configuration diagram showing an example of a constant velocity universal joint, and FIGS. 6A and 6B are schematic diagrams showing the hardened layer, respectively. 1...Outer ring, 3...Socket part, 11...
...High frequency induction heating coil body, 12...
Cooling water.

Claims (1)

[Claims] 1. A method for uniformly induction hardening the inner surface of a bellmouth-shaped socket of an outer ring of a constant velocity universal joint to a desired depth and uniformity using a heating hardening coil body fitted into the socket, which method comprises: The opening of the socket is directed downward, the quenched coil body is inserted into this opening from below, and cooling water is applied directly to the outer wall surface of the socket corresponding to the surface to be hardened of the socket. Therefore, the outer wall surface of the socket part is cooled in parallel with the heating operation of the inner surface of the socket part, and the surface heating rate of the thin-walled part of the flower-shaped socket part is suppressed to a relatively slow state. A method for hardening the inner surface of the socket of the outer ring of a constant velocity universal joint.