JPH0414166B2 - - Google Patents

Description

[Detailed description of the invention] Industrial applications The present invention relates to an induction hardening method for shafts.

BACKGROUND TECHNOLOGY In order to carry out induction hardening of shafts in as short a time as possible, the recent trend is to increase the moving speed of shafts or induction hardening coils as much as possible. However, the rotation speed of the shafts is 300 rpm.
If the width of the induction hardened coil is 10 mm, the moving speed should be changed from the previous 3 to 20 mm/sec to, for example, 50 mm/sec.
Assuming this, it takes 0.2 seconds for one point on the shaft to pass through the induction hardening coil, and the shaft only rotates once during that time. When such induction hardening is performed, heating unevenness occurs in the heated portion of the shaft in the circumferential direction, and the distortion of the shaft becomes extremely large. In order to prevent this, the rotational speed of the shafts is increased to rotate more while the heated part passes through the induction hardening coil, thereby preventing uneven heating of the heated part. .

Problems to be Solved by the Invention However, when induction hardening a shaft that has grooves, recesses, or protrusions formed in the longitudinal direction of the shaft and is provided with serrations (teeth), splines, etc., the shaft as described above is When the rotational speed of the serrations, splines, etc. is increased, it becomes difficult for the cooling liquid to hit the bottom and one side of the serrations, splines, etc., resulting in problems such as changes in the diameter of overpins and falling teeth of the serrations, splines, etc. The reason for this will be explained with reference to FIG.

FIG. 2 shows a state in which coolant is injected to the serrations, and a plurality of serrations 81 are formed on the shaft 80. The coolant 91 injected from the coolant jacket 90 hits the tips 81a of the serrations, and since the shaft 80 is rotating in the direction of arrow A, the coolant 92 hits the side surface 81b of the serrations 81 (in the direction of rotation of the shaft). side surface), so the tooth tip 81a
And the side surface 81b is appropriately cooled. but,
On the side surface 81c of the serrations 81 (the side surface in the opposite rotational direction of the shaft), the coolant 93 follows this side surface, and the serrations 81 act as a water wheel and splash the coolant, causing the coolant to flow to the side surface. Since this attempts to prevent the air from hitting the side surface 81c, cooling of the side surface 81c becomes insufficient. Further, the water wheel effect of the serrations 81 described above also tries to prevent the cooling liquid from hitting the bottom portion 81d of the serrations 81, so that the bottom portion 81d also becomes insufficiently cooled. As a result, problems such as a change in the diameter of the overpin and the falling of the teeth occur.

The present invention has been made in view of the above,
The object of the present invention is to provide an induction hardening method for shafts that does not cause changes in overpin diameter or collapse of teeth in serrations, splines, etc. of shafts.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides shafts having a portion in which grooves, recesses, protrusions, etc. are formed in the longitudinal direction of the shaft, and portions in which grooves, recesses, protrusions, etc. are not formed. In the induction hardening method for shafts in which the shafts are hardened while rotating, in the portions where the grooves, recesses, or convex portions are formed, the moving speed of the induction hardening coil unit or the shafts and the rotational speed of the shafts are and are respectively smaller than the moving speed and rotational speed in a portion where the groove, recess, convex portion, etc. are not formed.

Operation When the shafts are rotated, the induction hardening coil is energized, and the cooling liquid is injected from the cooling liquid jacket, the shafts or the induction hardening coil unit are rotated so that the shafts pass through the induction hardening coil unit. will be moved. When a portion having grooves, recesses, protrusions, etc. is formed passes through the induction hardening coil unit, the moving speed of the induction hardening coil unit or shafts and the rotational speed of the shafts are different from those of the grooves, recesses or protrusions. The moving speed and rotational speed are each smaller than the moving speed and rotational speed in a portion where no convex portion or the like is formed.

Embodiment FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and shows a vertical front end view of a shaft provided with serrations at both end portions and an induction hardened coil unit.

10 is a shaft to be induction hardened. A portion P near one end of the shaft 10 is provided with serrations (teeth) 11 by forming grooves in the longitudinal direction of the shaft 10, and a similar portion R near the other end is provided with serrations (teeth) 11. Serrations 12 are formed. Part Q of shaft 10
is a part where serrations are not formed. 21 is an induction hardening coil, and 22 is a cooling liquid jacket that injects cooling liquid to the heated portion.The induction hardening coil 21 and the cooling liquid jacket 22 are combined into one induction hardening coil unit 20. It is assembled.

In order to induction harden the shaft 10, the shaft 10 is
is moved in the direction of arrow B to pass the induction hardened coil 21 and coolant jacket 22 (the induction hardened coil unit 20 may be moved in the opposite direction to arrow B).

When the portion Q is hardened, both the movement and the rotation of the shaft 10 are performed at high speed. When hardening the portion P, the rotational speed of the shaft 10 is made smaller than when hardening the portion Q, and the moving speed is made smaller accordingly. Part R is hardened in the same manner as part P. Note that when the portion Q is hardened, the output of the induction hardening coil is increased.

By hardening in this way, the number of rotations during which the portion P passes through the induction hardened coil unit 20 is made smaller than the number of rotations during which the portion Q passes through the induction hardened coil unit 20, and the moving speed is also reduced. Therefore, uneven cooling of the entire portion P is reduced. In other words, the coolant not only properly hits the tooth tips and the side surface of the serrations 11 in the direction of rotation, but also the side surface of the serrations 11 in the opposite direction. The coolant also hits the bottom well.
Therefore, it is possible to prevent distortion from occurring on the sides and bottom of the serrations 11. The same applies to portion R.

Although the above is an example in which the serrations are provided at both ends of the shaft, the serrations may be provided anywhere on the shaft.

Furthermore, although the above description has been made regarding the induction hardening method for a shaft on which serrations are formed, the induction hardening method of the present invention can also be applied to a shaft on which splines are provided. Furthermore, it goes without saying that the present invention can also be applied to shafts in which grooves, recesses, protrusions, etc. are generally formed in the longitudinal direction of the shaft.

Effects of the Invention As described above, according to the present invention, grooves, recesses, convex portions, etc. are formed in the longitudinal direction of the shaft in induction hardening of shafts provided with serrations, splines, etc. Alternatively, the moving speed of the induction hardened coil unit or shafts and the rotational speed of the shafts are made smaller in areas where convex portions, etc. are formed, compared to areas where grooves, recesses, or convex portions, etc. are not formed. This allows the coolant to properly hit the sides and bottom of the serrations, splines, etc. Therefore, problems such as changes in the diameter of overpins such as serrations and splines, and falling of teeth do not occur.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and is a vertical front end view of a shaft and an induction hardened coil unit provided with serrations at both ends, and FIG. Indicates the state in which liquid is being sprayed. 10... Shaft, 11, 12... Serration, 20... Induction hardening coil unit, 21...
...Induction hardening coil, 22...Cooling liquid jacket.

Claims (1)

[Claims] 1. In an induction hardening method for shafts, which involves moving and hardening a shaft having portions in which grooves, recesses, convex portions, etc. are formed in the longitudinal direction of the shaft, and portions in which grooves, concave portions, or convex portions are not formed, while rotating the shaft, the grooves, The moving speed of the induction hardened coil unit or the shafts and the rotational speed of the shafts in the areas where the grooves, depressions, or the like are not formed are the same as those in the areas where the grooves, depressions, or protrusions are not formed. This is an induction hardening method for shafts that is characterized by reducing both the moving speed and the rotational speed.