JPH0324232A - Method for induction hardening of gear - Google Patents

Abstract

PURPOSE:To execute the hardening of plural kinds of gears in a common equipment by setting the frequency of a high frequency current flowing in a coil to the lowest hardening depth and, in case of a gear having a high hardening depth, repeatedly subjecting it to induction heating with air-cooling. CONSTITUTION:At the time of subjecting gears to hardening by utilizing induction heating, the frequency of a high frequency current flowing in a coil is set to the value in accordance with the lowest hardening depth. In case of a gear having the lowest hardening depth, it is hardened by single induction heating according to the conventional method. In case of a gear having a high hardening depth, it is subjected to induction heating for a time and is air cooled for prescribed time; in the meanwhile, the heat that the tip part holds is transmitted to the dedendum part. Then, the gear is subjected to induction heating once more and is almost uniformly heated to the dedendum part. Hereafter, induction heating is similarly repeated to obtain a sufficient hardened layer. In this way, there is no need for preparing separate hardening equipments or changing the frequency conditions, and set-up change man-hours can be reduced as well as the equipment cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for hardening a gear placed in a coil using induction heating using a high-frequency current, and more specifically, it relates to a method for hardening a gear placed in a coil using induction heating using a high-frequency current. The present invention relates to a method for hardening a plurality of different types of gears using a common hardening device.

2. Prior Art and its Problems As a method of induction hardening the teeth of a ring gear, there is a method shown in FIGS. 5 and 6, for example. In this method, a ring gear 3 positioned on a jig 2 is placed inside an annular coil 1, and while the ring gear 3 is rotated together with the jig 2, a high frequency current is passed through the coil 1, and the ring gear 3 is heated by induction heating. The tooth portion 7 is heated mainly. After heating for a predetermined period of time, the coil 1 is raised as shown by the imaginary line in FIG. 6, and quenching water is immediately injected from the injection port 5 of the water jacket 4 to cool it, thereby performing quenching. Reference numeral 6 indicates a cooling water passage provided within the coil l. Further, 12 indicates a cooling water port, and 13 indicates a quenching water port.

By the way, in ring gears used in the drive system of automobiles, for example, even if they are of the same size, the stress load state on the tooth portion 7 differs depending on the car model or specifications. The pattern of the quenched hardened layer of part 7 is shown in Fig. 2 (A), (B) and Fig. 3 (A).
), (B).

For example, Figure 3 (A). In the case of the ring gear 23 in (B), the entire tooth portion 7 from the tooth tip to the tooth root is covered with the quenched hardened layer 8.
Figure 2 (A). In the case of the ring gear 33 shown in (B), a relatively shallow quenched hardened layer 9 is required at the tooth tip at one end in the tooth trace direction.

In such a case, considering the general characteristic of the equipment that the lower the frequency of the high-frequency current, the greater the quenching depth can be obtained, in the case of the quenching patterns shown in Figs. 2(A) and 2(B), the third Compared to the patterns in Figures (A) and (B), a frequency several times higher (generally 5 to 8 times higher, depending on the gear size, etc.) is required, and therefore the quenching depth is reduced as shown above. It is extremely difficult to harden two types of ring gears 23, 33 that have a large difference in temperature using a common hardening device with a constant frequency. As a result, a separate hardening device is required for each hardening pattern, resulting in an undesirable increase in equipment costs.

It is also possible to change the frequency of one hardening device each time depending on the type of ring gear, but in that case, it would take a lot of man-hours and time to modify and change the equipment, and the equipment operating rate would be reduced. In combination with the decline, equipment costs will rise similarly to the above.

The present invention was made in view of the above problems.
The purpose is to provide a method that enables hardening of a plurality of types of gears having different hardening depths as described above using common equipment without changing the frequency.

Means for Solving the Problems In the present invention, the frequency of the high-frequency current flowing through the coil is set to a value corresponding to the smallest hardening depth, and when hardening a gear with the smallest hardening depth, 1. While hardening is performed by induction heating twice, when hardening gears with a larger hardening depth, induction heating by a coil is repeated at least twice with a predetermined air cooling time in between.

Function According to this method, in the case of a gear with the smallest hardening depth, the frequency is set in advance according to the hardening depth. It is hardened using the following steps.

On the other hand, in the case of gears with a large hardening depth, the frequency conditions do not match the hardening depth (the frequency is too high), so if the gear is hardened using the same procedure as above, only the tooth tip surface will be Due to heating, the quenching depth is too small and a necessary and sufficient quenching hardened layer cannot be obtained.

Therefore, once induction heating is performed, it is air cooled for a predetermined period of time, during which time the heat held by the tooth tip is transmitted to the tooth root, and then induction heating is performed again to ensure that the tooth root is heated almost uniformly. become. Then, as above, air cooling →
By going through the water cooling procedure, a necessary and sufficient quenched layer can be obtained.

Example Ring gears 23, 33 having the specifications shown below were processed using the hardening equipment shown in FIGS. 5 and 6 as shown in FIGS. Hardening was performed to obtain a hardening pattern.

Ring gear specifications not included
Diameter within 284.015MM
Diameter 254. OJIJI thickness
Size 10, Ou + number of teeth 1 1 1 pressure angle 20° shift M
-0.5 Diamond Lubitch
10/12 (module) (2.54
) Regarding the ring gear 33 having a pattern with a small hardening depth shown in FIGS. 2(A) and (B), the ring gear 33 as shown in FIG. 1(A) is Induction heating was performed for 2 seconds, and after 2.5 seconds of air cooling (cooling), quenching water at a temperature of 30 to 34° C. was injected from the water jacket 4 (FIG. 6) for water cooling. however,
As shown in FIG. 4, the position of the coil (2) relative to the ring gear 33 was set to be a predetermined amount β higher than in the case of the hardening turn shown in FIGS. 3(A) and (B).

On the other hand, Fig. 3(A). For the ring gear 23 with a large hardening depth pattern shown in (B), the output is 9, QKV,
Induction heating was performed for 6 seconds as shown in Figure 1 (B) under the condition of a frequency of 200 KHz, and then after 2.5 seconds of air cooling (cooling) time, heating was performed again under the same conditions as above for 7.5 seconds. Induction heating was performed for seconds. After heating, after 4.5 seconds of air cooling (cooling),
Water cooling was performed by spraying quenching water at ~34°C.

As a result, Figure 2 (A). In the case of the hardened layer 9 of (B), the hardened layer 9 has a Rockwell hardness of HaC50.
Virtual machining of the tooth tip surface/Radius (R) 3 centered on the nozzle part 10
It was formed up to a range of ~5 mm.

Also, Fig. 3(A). In the case of the hardened turn of (B), the hardened layer 8 of HRC50 is 1 to 3 times lower than the tooth bottom surface 11.
It was confirmed that it was formed deep into MII.

Effects of the Invention According to the present invention, the frequency of the high-frequency current flowing through the coil is set to a value corresponding to the smallest quenching depth, and the gear with the smallest quenching depth is quenched by one induction heating. ,
Gears with large quenching depths are quenched by repeating induction heating at least twice with a predetermined air cooling time in between, making it possible to change the frequency conditions for multiple types of gears with different quenching depths. Since the hardening process can be performed using a common hardening device without any hardening, there is no need to prepare separate hardening devices depending on the hardening depth or change the frequency conditions each time, which is required in the past, reducing equipment costs. In addition, this has the effect of significantly reducing the number of man-hours required for setup changes.

[Brief explanation of the drawing]

FIG. 1(A) is a diagram showing an embodiment of the present invention, and is a process explanatory diagram for hardening a hardened material with a small hardening depth.
Figure (B) is an explanatory diagram of the process for hardening a ring gear with a large hardening depth, and Figure 2 (A) is an enlarged view of the main parts showing the hardening pattern of a ring gear with a small hardening depth. B) is a cross-sectional view taken along the line nn in Figure (A), and Figure 3 (
A) is the hardening of a ring gear with a large hardening depth. Figure 3 (B) is an enlarged view of the main part showing the turn, Figure 3 (B) is a sectional view taken along line A schematic explanatory diagram showing an example of an induction hardening apparatus, FIG. 6 is a sectional view taken along the line VI-Vl in FIG. 5. DESCRIPTION OF SYMBOLS 1... Coil, 7... Teeth, 8, 9... Quenched hardened layer, 23.33... Ring gear. Figure 2 (A) (B) Figure 3

Claims (1)

[Claims] (1) When induction hardening is applied to gear teeth, a common hardening device is used to harden multiple types of gears with different hardening depths, and the frequency of the high-frequency current flowing through the coil is set to the lowest The value is set according to the hardening depth, and gears with the smallest hardening depth are hardened with one induction heating using a coil, while gears with a large hardening depth are hardened with a specified air cooling time. A method for induction hardening gears, which comprises repeating induction heating using a sandwiched coil at least twice.