JPH051326A - Induction hardening method for gear - Google Patents

Abstract

PURPOSE:To apply induction hardening to a gear without causing strain in the gear by equalizing hardening conditions on the side of a couple of teeth with respect to respective teeth of the gear. CONSTITUTION:High frequency heating is applied to the teeth to be hardened while allowing a gear 10, where the teeth to be hardened are formed in the outside peripheral part, to turn on the shaft of the gear 10. Subsequently, the turning of the gear is stopped, and then, the gear is immersed in a coolant L and the coolant L is agitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear induction hardening method.

[0002]

2. Description of the Related Art A conventional technique will be described below with reference to the drawings. 3 and 4 are explanatory views of a conventional induction hardening method for gears. FIG. 3 shows a part of a jacket for injecting a cooling liquid and a part of the gear, and FIG. 4 shows a part of the gear. ..

A gear 10 for quenching the surface of a tooth 19 formed on an outer peripheral portion thereof is supported horizontally, rotatably, and vertically movable, and has an annular shape (not shown in FIGS. 3 and 4) around the tooth 19. A high frequency heating coil is provided, and a high frequency current is supplied to the high frequency heating coil for a predetermined time while rotating the gear 10 about its axis.

Then, the gear 10 is immersed in a cooling liquid, and the gear 10 is rotated about its axis at a rotational speed lower than that at the time of high frequency heating, and the cooling liquid jetting jacket 80 provided in the cooling liquid is rotated. A cooling liquid L is jetted from the nozzle 81 to the teeth 19 to quench the teeth.

The reason why the rotation speed of the gear 10 is lowered during cooling rather than during heating is as follows. That is, when the rotational speed of the gear 10 during jet cooling is made as fast as during heating, the cooling liquid jetted from the nozzle 81 cools the tooth side 13 and the tooth bottom 12 connected to the tooth side 13 sufficiently before As a result of the tooth side 13 and the tooth bottom 12 rotating, the effective depth of the hardened layer 14 formed on the tooth bottom 13 due to insufficient cooling of the tooth side 13 and tooth bottom 12.
This is because D (Fig. 4) becomes shallower and the quenching hardness decreases. In addition, 11 is a tooth tip.

[0006]

However, when the gear 10 is quenched by such a conventional induction hardening method, the gear 10 tends to be distorted. That is, as shown in FIG. 4, while rotating the gear 10 in the direction of arrow Q,
When the cooling liquid L is jetted to the teeth 19, one tooth 19 has a pair of tooth sides.
Of 13a and 13b (Fig. 4), the tooth side 13 on the rotation direction side of the gear 10
Since the amount of the cooling liquid L that hits a is larger than the amount of the cooling liquid L that hits the tooth side 13b opposite to the rotation direction of the gear 10, the tooth side 13a cools faster than the tooth side 13b.
13a swells, and the gear 10 is distorted.

That is, when the gear 10 is cooled while being rotated, the cooling conditions between the tooth sides 13a and 13b of the tooth 19 differ. The present invention has been made in view of the above circumstances, and provides an induction hardening method for a gear that does not cause distortion in the gear by making the cooling conditions of the pair of teeth of each tooth of the gear the same. It is intended to be provided.

[0008]

In order to solve the above-mentioned problems, a method of induction hardening a gear according to the present invention is to rotate a gear having teeth to be hardened on its outer peripheral portion around a gear shaft. While heating the teeth with high frequency, the rotation of the gear is stopped, the gear is then immersed in the cooling liquid, and the cooling liquid is agitated.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the induction hardening method for gears of the present invention will be described below with reference to the drawings. 1 and 2 are explanatory views of an induction hardening apparatus capable of realizing the present embodiment, FIG. 1 is a sectional explanatory view in a cooling step, and FIG. 2 is a sectional explanatory view in a heating step.

The gear 10 hardened by the method of this embodiment is the gear 10 described in FIGS. 3 and 4. This gear 10
The bottom portion 41 of the cooling liquid tank 40 containing the cooling liquid L is placed on the tip portion of the cylinder 20 that penetrates in a liquid-tight manner, freely liftable and rotatable. The cylinder 20 is moved up and down and rotated by a drive mechanism (not shown). Above the cooling liquid tank 40, an annular high frequency heating coil is formed so as to surround the gear 10.
50 are provided. Incidentally, 10a is a shaft of the gear 10.

Another cooling liquid tank 60 is installed so as to surround the cooling liquid tank 40, and the cooling liquid tank 40 has a bottom surface.
Both the tank 41 and the bottom surface 61 of the coolant tank 60 are formed so as to be substantially on the same plane. A pipe 70 connecting the bottom surfaces 41 and 61 is provided with a pump 70 and a pair of valves 72, and the pump 70 is arranged between the valves 72.

The pump 70 is a pump for transferring the cooling liquid L in the cooling liquid tank 60 into the cooling liquid tank 40. Reference numeral 90 denotes a metal concentrator, which is mounted on the side surface of the gear 10 as shown in FIG. This is to prevent it from wrapping around.

Next, a method of induction hardening the gear 10 will be described. First, in a state where the cooling liquid L is fully supplied to the cooling liquid tank 40 and the cooling liquid L is also supplied to the cooling liquid tank 60 to an appropriate depth, the cylinder 20 lifted above the high frequency heating coil 50. One outlet ring 90, the gear 10 and the other outlet ring 90
Place on the same core. Then, the cylinder 20 is lowered so that the teeth 19 of the gear 10 are opposed to the high frequency heating coil 50. Then, the pair of valves 72 are opened and the pump 70 is activated to start the transfer of the cooling liquid L in the cooling liquid tank 60 into the cooling liquid tank 40.

Next, when the cylinder 20 is rotated in the direction of arrow P, the gear 10 rotates about its shaft 10a. In this state, a high-frequency current is applied to the high-frequency heating coil 50 from a high-frequency power source (not shown) for a predetermined time, and the gear 10
Heat teeth 19 of. Then, the rotation of the cylinder 20 is stopped,
As shown in FIG. 1, the cylinder 20 is lowered and the gear 10 is immersed in the cooling liquid L.

The cooling liquid L transferred from the cooling liquid tank 60 into the cooling liquid tank 40 by the pump 70 is
From the bottom to the top in 40, it overflows and falls into the coolant tank 60. That is, since the cooling liquid L is agitated in the cooling liquid tank 40, it uniformly contacts all the surfaces of the heated teeth 19 of the gear 10. That is, the tooth tip 1 shown in FIG.
1. The tooth bottom 13 as well as the tooth sides 13a and 13b are uniformly cooled by the cooling liquid L, so that the gear 10 is not distorted. Further, the depth D of the hardened layer of the tooth bottom 12 becomes a desired depth, and the hardness of the hardened layer 14 can also be set to a desired value.

[0016]

As described above, according to the induction hardening method for gears of the present invention, the gears having the teeth to be hardened on the outer peripheral portion are rotated about the shaft of the gear while the teeth are heated by induction heating. After that, the rotation of the gear is stopped, the gear is then immersed in the cooling liquid, and the cooling liquid is agitated.

Therefore, according to the induction hardening method for gears of the present invention, since the cooling conditions for the pair of teeth of each tooth of the gears are the same, distortion can occur in the hardened gears. In addition, since a jacket having a complicated structure for ejecting the cooling liquid to the gears is not required, the structure of the quenching device is simplified.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory diagram in a cooling process of an induction hardening apparatus that can realize an embodiment of the present invention.

FIG. 2 is a cross-sectional explanatory view in a heating process of an induction hardening apparatus that can realize an embodiment of the present invention.

FIG. 3 is an explanatory view of a conventional technique, showing a part of a jacket and a part of a gear that inject a cooling liquid.

FIG. 4 is an explanatory view of a conventional technique and shows a part of a gear.

[Explanation of symbols]

 10 Gear 10a Shaft 19 Teeth 40 Coolant tank 50 High frequency heating coil 60 Coolant tank 70 Pump L Coolant

Claims (1)

Claim: What is claimed is: 1. While rotating a gear whose teeth to be hardened are formed on the outer peripheral portion around the axis of the gear, heat the teeth at high frequency, then stop the rotation of the gear, and then A method for induction hardening a gear, comprising immersing the gear in a cooling liquid and stirring the cooling liquid.