JPH0520487B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an induction hardening method and apparatus for a plurality of circumferential surfaces of a long workpiece to be hardened.

<Conventional technology> The conventional technology will be explained below with reference to the drawings.

FIG. 3 is an explanatory diagram of a conventional induction hardening method and apparatus, in which one end of a long workpiece 10 is supported by a fixed center pin 21 and the other end is supported by a movable center pin 22. The workpiece 10 has cylindrical portions 11, 12, and 13 integrally formed with a common axis 23, which is a straight line connecting the ends of both center pins. The circumferential surface 11 of each of these cylindrical parts
In order to form a hardened layer of a predetermined width at predetermined positions of a, 12a, and 13a, the workpiece 10 is rotated about the shaft 23 by a drive device (not shown) while approaching the circumferential surfaces 11a, 12a, and 13a, respectively. Saddle-shaped (or split-type) high-frequency heating coils (hereinafter simply referred to as heating coils) 31, 3
2 and 33 to generate an induced current on their circumferential surfaces to heat them, and then coolant is injected onto these circumferential surfaces from a cooling liquid jacket (not shown) to form a hardened layer on the circumferential surfaces 11a, 12a, and 13a. Form.

<Problems to be Solved by the Invention> However, when the above-mentioned induction hardening is performed, there are problems described below. That is, the cylindrical parts 11, 12, and 13 of the workpiece 10 are heated and expanded by the induced current, and the workpiece 10 as a whole moves in the direction of the movable center pin 22 (in the direction of arrow A in FIG. 3).
It grows to. Therefore, the peripheral surfaces 11a, 12a, 13a
However, since the positions of the heating coils 31, 32, and 33 are fixed, the portions of the circumferential surfaces 11a, 12a, and 13a that are actually heated gradually move from the predetermined positions in the direction of the arrow A. This means that it is shifted in the opposite direction to A. Therefore, the formed hardened layer also shifts from the predetermined position in the direction opposite to arrow A.

The present invention has been devised in view of the above-mentioned circumstances, and when heating a plurality of circumferential surfaces of a long workpiece to be hardened using heating coils provided for each circumferential surface, the workpiece expands. However, it is an object of the present invention to provide an induction hardening method and apparatus that can simultaneously harden predetermined positions of a plurality of peripheral surfaces to be hardened.

<Means for Solving the Problems> In order to solve the above problems, the induction hardening method of claim 1 provides a method in which one end is supported by a fixed center pin and the other end is supported by a movable center pin. The circumferential surface of each cylindrical part of a workpiece that has multiple cylindrical parts whose common axis is the line connecting the
In an induction hardening method in which high-frequency heating coils provided on each peripheral surface are heated simultaneously, each of the high-frequency heating coils is moved a predetermined distance in the direction of a movable center pin in response to the elongation of the workpiece in the axial direction. After heating the peripheral surface, a cooling liquid is injected onto the peripheral surface.

Further, the induction hardening apparatus according to claim 2 has a plurality of cylindrical parts each having one end supported by a fixed center pin and the other end supported by a movable center pin, each having a common axis that is a line connecting the tips of the two center pins. In an induction hardening apparatus that simultaneously heats each circumferential surface of a cylindrical part of a workpiece with a high-frequency heating coil provided for each circumferential surface, a workpiece elongation detection means;
The apparatus includes means for moving the high-frequency heating coils by predetermined distances in the direction of the movable center pin in response to the elongation of the workpiece detected by the detection means.

<Function> After the high-frequency heating coils start heating each circumferential surface, each high-frequency heating coil is moved a predetermined distance in the direction of the movable center pin in response to the elongation of the workpiece in the axial direction, and the circumferential surfaces are heated. After heating, a cooling liquid is injected onto the surrounding surface.

<Example> An example of the present invention will be described below with reference to the drawings. 1 and 2 are drawings for explaining one embodiment of the present invention, in which FIG. 1 is a sectional view of a workpiece and a schematic configuration diagram of an induction hardening device, and FIG. 2 is a movement of a heating coil. FIG. 2 is an explanatory diagram of the device.

The workpieces to be hardened in this example are as follows:
A workpiece 10 having the same structure and hardened peripheral surface as the workpiece described in the conventional technique was taken up. As explained in FIG. 3, saddle-shaped heating coils 31, 32, and 33 are disposed close to the circumferential surfaces 11a, 12a, and 13a of the workpiece 10 to be hardened, respectively. ing. In addition, the heating coils 31, 3
2 and 33 may be split coils. A differential transformer 44 that detects the displacement of the movable center pin 22 serves as a means for detecting the elongation of the entire length of the workpiece 10.
is provided. However, it is not limited to the differential transformer 44, and a capacitance type or eddy current type gap detector or the like may be used. Differential transformer 4
4 is connected to a heating coil position control device 46 via a signal line 45.

Heating coil moving devices 41, 42, 43 are attached to the heating coils 31, 32, 33, respectively. As shown in FIG. 2, the heating coil moving device 41 includes a rack 4 connected to the heating coil 31.
1a, and a pinion 41b that drives the rack 41a in the direction of arrow A in FIG. 1 and in the opposite direction to arrow A.
, a shaft 41c of a pinion 41b, and a pinion drive device 41d that rotationally drives the shaft 41c, and the pinion drive device 41d is connected to a heating coil position control device 46 via a signal line 41e. The heating coil moving devices 42 and 43 also have the same configuration as the heating coil moving device 41, and the pinion drive devices (not shown) of the heating coil moving devices 42 and 43 also have signal lines 42e and 43e, respectively.
It is connected to the heating coil position control device 46 via.

The heating coil position control device 46 calculates the distance to which the heating coils 31, 32, 33 should be moved based on the elongation of the work 10 detected by the differential transformer 44, and also calculates the distance to which the heating coils 31, 32, 33 should be moved. 43
A computer or the like is provided for instructing the moving distance of the heating coils 31, 32, and 33, respectively. In addition, l shown in FIG. 1 is the total length of the work 10 before heating, and l ₁ , l ₂ , and l ₃ are the end of the work 10 on the fixed center pin 21 side, and the peripheral surface 1 of the work 10, respectively.
This is the distance before heating between the center in the axis 23 direction of the cured layer to be formed on 1a, 12a, and 13a.

Next, the above l ₁ , l ₂ , l ₃ , l are each 200,
The operation of this embodiment will be explained using cases of 600, 850, and 1000 mm as examples.

The heating coils 31, 32, 3 are rotated while the workpiece 10 is rotated around the shaft 23 by a drive device (not shown).
When a high frequency current is applied from a high frequency power source (not shown) to 3, the workpiece 10 is heated by the induced current induced in the cylindrical portions 11, 12, and 13 and extends toward the movable center pin 22. Now, assuming that the elongation Δl of the workpiece 10 detected by the differential transformer 44 at a certain time after the start of heating is 10 mm, the distances l ₁ , l ₂ ,
The elongation Δl ₁ , Δl ₂ , Δl ₃ of l ₃ is the distance l ₁ , l ₂ ,
If it is simply proportional to l ₃ , then the elongation Δl ₁ , Δl ₂ ,
Δl ₃ should be 2, 6, and 8.5 mm (assuming that the elongations Δl ₁ , Δl ₂ , and Δl ₃ are simply proportional to the distances l ₁ , l ₂ , and l ₃ , respectively, as described above). instead,
The difference in elongation of the cylindrical parts 11, 12, and 13, which are the parts to be heated, due to the difference in diameter is obtained by conducting a test in advance, and the results are input into the heating coil position control device 46. Based on the results, the heating coil position control device 46 may issue commands to the heating coil moving devices 41, 42, and 43).

Therefore, by moving the heating coils 31, 32, and 33 by 2, 6, and 8.5 mm, respectively, in the direction of the movable center pin 22, the centers of the heating coils 31, 32, and 33 will be aligned with the peripheral surfaces 11a, 12a, and 13a.
It coincides with the center of the hardened layer to be formed in the axis 23 direction. That is, Δl detected by the differential transformer 44 is sent to the heating coil position control device 46 via the signal line 45. The heating coil position control device 46 controls the distance l stored in advance as Δl,
Δl ₁ , Δl ₂ , Δl ₃ are calculated from l ₁ , l ₂ , l ₃ , and the heating coils 31 , 32 , 33 are moved in the direction of the movable center pin 22 according to the calculation results. A command is issued to the moving devices 41, 42, and 43. The signal regarding Δl of the differential transformer 44 is
Although the commands from the heating coil position control device 46 to the heating coil moving devices 41, 42, 43 are continuously transmitted to the heating coil position control device 46, the commands may be continuous or intermittent. good.

In this way, in response to the elongation of the workpiece 10, the centers of the heating coils 31, 32, 33 are moved to the center in the axis 23 direction of the hardened layer to be formed on the peripheral surfaces 11a, 12a, 13a. Therefore, even if the workpiece 10 expands, the peripheral surfaces 11a and 12
A hardened layer can be formed at predetermined positions of a and 13a.

Although a means for elongating the workpiece is provided in this embodiment, the heating coil position control device 46 can control the elongation of the workpiece from pre-stored data such as heating power and heating time without providing such a means. The heating coil moving device 4 calculates the amount of heat generated in
It is also possible to issue commands to 1, 42, and 43.

<Effects of the Invention> As explained above, the invention of claim 1 is capable of adjusting the circumferential surface of each cylindrical part of a workpiece, which has a plurality of cylindrical parts having a common axis, in accordance with the elongation of the workpiece. A high frequency heating coil provided on the surface is moved a predetermined distance in the direction of the movable center pin to heat the peripheral surface.

The invention of claim 2 also provides a high-frequency heating coil provided on each circumferential surface of a cylindrical part of a workpiece having a plurality of cylindrical parts having a common axis, a means for detecting elongation of the workpiece, and a means for detecting elongation of the workpiece. means for moving the high-frequency heating coils a predetermined distance in the direction of the movable center pin in response to the elongation of the workpiece detected by the controller.

Therefore, according to the present invention, even if the workpiece stretches due to heating, a hardened layer can be formed at a predetermined position on each circumferential surface.

[Brief explanation of the drawing]

1 and 2 are drawings for explaining one embodiment of the present invention, in which FIG. 1 is a sectional view of a workpiece and a schematic configuration diagram of an induction hardening device, and FIG. 2 is a movement of a heating coil. FIG. 3 is an explanatory diagram of a conventional induction hardening method and apparatus. 10...Work, 11-13...Cylindrical part, 11
a, 12a, 13a...peripheral surface, 21...fixed center pin, 22...movable center pin, 23...
Shaft, 31-33... Heating coil, 41-43...
Heating coil moving device, 46... Heating coil position control device.

Claims (1)

[Claims] 1. A cylindrical portion of a workpiece having a plurality of cylindrical portions, one end of which is supported by a fixed center pin and the other end supported by a movable center pin, and whose common axis is a line connecting the tips of both center pins. In an induction hardening method in which each circumferential surface is simultaneously heated by high-frequency heating coils provided for each circumferential surface, each high-frequency heating coil is connected to a movable center pin in response to the elongation of the workpiece in the axial direction. An induction hardening method characterized by heating the circumferential surface by moving it a predetermined distance in the direction of , and then injecting a cooling liquid onto the circumferential surface. 2 The circumferential surface of each cylindrical part of a workpiece has a plurality of cylindrical parts supported by a fixed center pin at one end and a movable center pin at the other end, and whose common axis is a line connecting the tips of the center pins, In an induction hardening device that simultaneously heats each circumferential surface with high-frequency heating coils, there is a workpiece elongation detection means, and the high-frequency heating coil is connected to a movable center pin in response to the elongation of the workpiece detected by this detection means. 1. An induction hardening device characterized by comprising means for moving predetermined distances in each direction.