JPH03215628A - Method and device for high-frequency hardening - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 parts 11 and 12 that are integrally formed with a common axis 23 that is a straight line connecting the tips of both center pins.
, 13. Each peripheral surface 1 of these cylindrical parts
In order to form a hardened layer of a predetermined width at predetermined positions of 1a, 12a, and 13a, the workpiece IO is rotated about the shaft 23 by a drive device (not shown), and the peripheral surface 11a is
, 12a, and 13a, a high-frequency current is passed through the saddle-shaped (or split-type) high-frequency heating coils C (hereinafter simply referred to as heating coils) 31, 32, and 33 to induce an induced current on their circumferential surfaces. After heating, a cooling liquid is injected onto these peripheral surfaces from a cooling liquid jacket (not shown) to form a hardened layer on the peripheral surfaces 11a, 12a, and 13a.

<Problems to be Solved by the Invention> However, when the above-mentioned induction hardening is performed, there are problems described below. In other words, workpiece 1 is
The cylindrical portions 11, l2, and I3 of
It extends in the direction of arrow A in the figure. Therefore, the peripheral surface 11a,
12a and 13a also extend in the direction of arrow A, but
On the other hand, 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 are gradually shifted from the predetermined positions in the direction opposite to arrow A. become.

Therefore, the formed hardened layer also shifts from the predetermined position in the direction opposite to arrow A.

The present invention was devised in view of the above 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. In an induction hardening method in which each peripheral surface of a cylindrical part of a workpiece having a plurality of cylindrical parts whose common axis is a line connecting In response to the elongation of the workpiece in the direction, each of the high-frequency heating coils is moved a predetermined distance in the direction of the movable center pin to heat the circumferential surface, and then a cooling liquid is injected onto the circumferential 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 device that simultaneously heats each peripheral surface of a cylindrical part of a workpiece using high-frequency heating coils provided for each peripheral surface, a workpiece elongation detection means and a workpiece elongation detected by the detection means are used. Correspondingly, means are provided for moving the high frequency heating coils each predetermined distance in the direction of the movable center pin.

<Operation> 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. , inject cooling liquid onto the surrounding surface.

<Example> Hereinafter, an example of the present invention will be described 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.

As the workpiece to be hardened in this embodiment, a workpiece 10 having a structure and a peripheral surface to be hardened similar to the workpiece described in the conventional technique was taken up. As explained in FIG. 3, the peripheral surfaces 11a and 12 of the workpiece 10 to be hardened are
a, 13a, respectively, a saddle-shaped heating coil 31,
32 and 33 are arranged close to each other.

Note that the heating coils 31, 32, and 33 may be split coils. A differential transformer 44 for detecting displacement of the movable center pin 22 is provided as means for detecting the elongation of the entire length of the workpiece 10. 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 44 connects signal line 4
5 to the heating coil position control device 4G.

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 41a connected to the heating coil 3l, and a rack 41a that
A pinion 4lb that is driven in the direction of arrow A in the figure and a direction opposite to arrow A, a shaft 41C of pinion 4lb, and a shaft 41
The pinion drive device 41d is connected to the heating coil position control device 46 via a signal line 41e. Heating coil moving devices 42 and 43 also have the same configuration as heating coil moving device 41, and heating coil moving devices 42 and 4
The pinion drive devices 3 (not shown) also have signal lines 42.
It is connected to the heating coil position control device 46 via e and 43e.

Note that the heating coil position control device 46 is connected to the differential transformer 44.
From the elongation of the workpiece 10 detected by the heating coils 31 and 3
Calculate the distance to move the heating coils 31, 33, and move the heating coils 31, 33 to the heating coil moving devices 41, 42, 43, respectively.
A computer or the like is provided for instructing the moving distances 32 and 33. In addition, l shown in Fig. 1 is the workpiece 1.
0 is the total length before heating, and 21, l2, and L are the end of the fixed center pin 21 side of the workpiece 10 and the peripheral surface 11, respectively.
This is the distance before heating between the center in the axis 23 direction of the cured layer to be formed on a, 12a, and 13a.

? In addition, the above-mentioned zl, 1z, 1. s and l are each 20
The operation of this embodiment will be explained by taking examples of cases where the distance is 0 mm, 600 mm, 850 mm, and 1000 mm.

When the workpiece 10 is rotated around the shaft 23 by a drive device (not shown) and a high-frequency current is applied to the heating coils 31, 32, 33 from a high-frequency power source (not shown), the workpiece 10 is moved by the induction induced in the cylindrical portions 1l, 12, 13. It is heated by the electric current 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 distance j! +, I! ．． t, Qs elongation Δ! ! ．． 1, Δ2■,
ΔI! ．． 3 are distances L, f2, !, respectively. If it is simply proportional to 3, then the elongation is Δ11, Δ! 2.Δi, is
2, 6, and 8.5 mm (instead of assuming that the elongations Δ21, Δj22, and Δ!!.3 are simply proportional to the distances l1, i!.2, and l3, respectively). First, a test is conducted in advance to determine 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.
Input to 6? Based on this result, the heating coil position control device 46 moves the heating coil moving devices jl41, 42.
, 43).

Therefore, the number of heating coils 31, 32, 33 is 2 and 6, respectively.
, 8.5 mm in the direction of the movable center pin 22, the centers of the heating coils 31, 32, 33 will be aligned with the center of the hardened layer to be formed on the peripheral surfaces 11a, 12a, 13a in the direction of the axis 23. matches. 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 f, I!, which is stored in advance as Δ2. ．． ．． , ffi■, 23, Δl1
, ΔL, Δ2, and move the respective heating coil moving devices 41, 42, 42, so that the heating coils 31, 32, 33 move in the direction of the movable center pin 22 according to the calculated results.
Issue a command to 43. The signal regarding Δl of the differential transformer 44 is continuously transmitted to the heating coil position control device 46, but the commands from the heating coil position control device 46 to the heating coil moving devices 41, 42, and 43 are not continuous. It may be continuous or intermittent.

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

Although a means for detecting the elongation of the workpiece is provided in this embodiment, the heating coil position control device 46 detects the workpiece from pre-stored data such as heating power and heating time without providing such a means. Calculate the amount of heat generated in
It is also possible to calculate the elongation of the workpiece corresponding to this amount of heat and issue a command to the heating coil moving devices 41, 42, and 43.

<Effects of the Invention> As explained above, the invention of claim 1 is such that the circumferential surface of each cylindrical part of a workpiece having a plurality of cylindrical parts having a common axis is adjusted so that the circumferential surface of each cylindrical part corresponds to 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 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. Figure 3 is an explanatory diagram of the conventional induction hardening method and equipment. IO...work, 11-13...-cylindrical part, lla,
12a, 13a...Surrounding surface, 21...Fixed center pin, 22...Movable center pin, 23...
Axis, 31-33... Heating coil, 41-43... Heating coil moving device, 46... Heating coil position control device.

Claims (2)

[Claims] (1) Each circumferential surface of a cylindrical part of a workpiece having a plurality of cylindrical parts supported by a fixed center pin at one end and a movable center pin at the other end, the common axis being a line connecting the tips of the center pins. In the induction hardening method, in which each of the high-frequency heating coils is simultaneously heated with high-frequency heating coils provided on each peripheral surface, each of the high-frequency heating coils is set in a predetermined direction in the direction of the movable center pin in response to the elongation of the workpiece in the axial direction. An induction hardening method characterized by injecting a cooling liquid onto the circumferential surface after heating the circumferential surface by moving it a distance. (2) Each circumferential surface of a cylindrical part of a workpiece having a plurality of cylindrical parts supported by a fixed center pin at one end and a movable center pin at the other end, with a line connecting the tips of both center pins serving as a common axis. In an induction hardening device that simultaneously heats the two surfaces with high-frequency heating coils installed on each circumferential surface, the workpiece elongation detection means and the high-frequency heating coil are moved to the movable center in response to the elongation of the workpiece detected by this detection means. An induction hardening device characterized by comprising means for moving each pin a predetermined distance in the direction of the pin.