JPH01188624A - High-frequency surface hardening method for crank shaft - Google Patents

Abstract

PURPOSE:To form a hardened layer to a uniform width and depth by energizing a high-frequency heating coil which moves in follow up to the part to be hardened of a crank shaft at a specific period while rotating the crank shaft at the time of subjecting the pin part and journal part of the crank shaft to high-frequency hardening. CONSTITUTION:The crank shaft is rotated in a direction P around a rotation center 22. The arrival of the center 21 of the pin part 12 of the crank shaft at a point S past a point C is detected by a limit switch 35S and a controller 34 starts energization to the high-frequency surface hardening coil 30 which moves in follow up to the pin part 12. The arrival of the center 21 of the pin part 12 at a point A is detected by a limit switch 35a and the energization quantity is decreased by the controller 34; in succession, the arrival of said part at a point B is detected by a limit switch 35b and the energization quantity of high-frequency current is returned to the original quantity. This energization quantity is continued until the center of the pin part 12 arrives at the point A past the point S and the point T. The energization quantity is decreased again when the center arrives at the point A and this operation is repeated prescribed times, by which the high-frequency hardened layer is formed to the layer having the uniform width and depth without having fluctuations.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an induction hardening method for crankshafts.

Conventional ■ Limb Distortion Conventionally, when performing induction surface hardening on the heated portions of the bottle and journal portions of a crankshaft, energization is carried out after a predetermined energization time has elapsed from the time when high frequency current is started to be applied to the high frequency surface hardening coil. The heating of the heated part is finished by cutting off the heating.

This current application time is empirically determined depending on the material and shape of the heated part, the required width and depth of the hardened layer, and the range of variation thereof.

■However, recently, the requirements for the range of variation in width, depth, etc. of the hardened layer formed on the heated part of the crankshaft have become increasingly strict. It has become difficult to meet this requirement simply by heating for a predetermined period of time using an induction hardening coil.

The present invention has been made in view of the above, and an object of the present invention is to provide a method for high-frequency surface hardening of a crankshaft, which reduces variations in the width, depth, etc. of the hardened layer formed on the heated portion of the crankshaft. It is said that

In order to solve the problem beyond the problem of "°", the present invention provides a mechanism that moves to follow the heated part of a rotationally driven crankshaft when the heated part comes to a predetermined position. A high-frequency current is applied to the high-frequency surface hardening coil to start heating the heated part, and then when the crankshaft rotates by a predetermined angle, the current supply is stopped to finish heating the heated part.

The crankshaft is driven to rotate, and the high-frequency surface hardening coil follows the heated portion of the crankshaft. When the heated portion of the crankshaft reaches a predetermined position, electricity is started to be applied to the high frequency surface hardening coil, and heating of the heated portion is started.

Thereafter, energization is continued until the crankshaft rotates by a predetermined angle, and then energization is stopped to complete heating of the heated portion.

Embodiment FIG. 1 is an embodiment of the present invention, and is a graph showing a method of applying a high-frequency current to a high-frequency surface hardening coil in high-frequency surface hardening of a crankshaft, in which the horizontal axis represents the rotation angle of the crankshaft. , the vertical axis shows the magnitude of high-frequency current. FIG. 2 shows a cross section of the pin portion 12 of the crankshaft shown in FIG. 3, as well as an induction surface hardening coil and the like. FIG. 3 is a front view of a crankshaft subjected to induction hardening by the method of the present invention. Figure 4 is the third
It is an enlarged view of the pin part 12 of a figure.

As shown in FIG. 3, crank shirt number 0 has integrally formed pin portions 11.12.13.14 and journal portions 15.16.17.18.19. When performing induction surface hardening on the pin and journal portions of the crankshaft 10, hold both ends using a center pin or the like so that the longitudinal direction of the crankshaft 0 is horizontal, and rotate the crankshaft 10 in this state. At the same time, the high-frequency surface hardening coil is brought into contact with the pin portion or the journal portion from above, and a high-frequency current is applied to the high-frequency surface hardening coil.

FIG. 2 shows a cross section of the pin portion 12 of the crankshaft 10 and the induction surface hardening coil etc. in order to explain the above-mentioned induction surface hardening, and 21 is the center of the cross section of the pin portion 12, and 22 is the center of rotation of crankshaft number 0, that is, the center of the cross section of any journal portion. By rotating the crankshaft 10 about the center 22 in the direction of arrow P, the center 21 of the cross section of the pin portion 12
moves on an arc 23 centered on the center 22. That is, the pin portion 12 rotates once per revolution in the direction of arrow Q while revolving in the direction of arrow P. Reference numeral 30 denotes an induction hardened coil, which is separated from the pin part 12 by a predetermined distance by a pair of spacers 31 and 31, and is moved by a known pantograph mechanism (not shown) in response to the movement of the pin part 12. 12 by reciprocating in the directions of arrows R and S. 32 is crankshaft 1
It is a rotation angle detector such as a rotary encoder that detects a zero rotation angle. The signal of the rotation angle of the crankshaft 10 detected by the rotation angle detector 32 is transmitted through the signal line 3.
3, the signal is sent to a controller 34 that switches on and off the high frequency current that flows through the high frequency surface hardening coil 30. Also, 3
5a, 35b, 35s and 35t are pin parts 12
The center 21 is points A and B, which will be described later.

This is a non-contact type limit switch that detects when S and T are reached, and is connected to the controller 3 by a signal line (not shown).
Connected to 4.

Next, the induction hardening method for crankshafts of the present invention will be explained with reference to FIGS. 1 and 2.

Point C is the position of the center 21 of the cross section of the pin portion 12 when the crankshaft 10 is rotated and the pin portion 12 is at the highest position. Before the center 21 reaches point C, the rotation angle of the crankshaft 10 is set to 1/ of the predetermined angle θ.
Let point A be the position of the center 21 such that θ/2 is 2. Further, the position where the center 21 passes the point C and the rotation angle of the crankshaft 10 is θ/2 is defined as a point B.

Further, after the crankshaft O starts rotating, the positions of the center 21 at the first position where the high-frequency surface hardening coil 30 starts to be energized and the last position where the energization is stopped are defined as a point S and a point T, respectively. The positions of these points S and T are set according to the required width and depth of the hardened layer and their variations, etc.
(represents 100 revolutions of the crankshaft after the start of energization to the induction hardening coil 30), and is set in advance. Also, the center 21 is from point C to point S, and from point S to point T.
The crankshaft 10 when moving in the direction of arrow P to
Let the rotation angles of C1 and C2 be respectively. Points A, B, C1S and T in Figure 1 are respectively points A, B, C1S and T in Figure 2.
It corresponds to B, C, S and T.

First, the rotation of the crankshaft 10 is started while the high frequency surface hardening coil 30 is not energized. The limit switch 35s detects that the center 21 of the pin portion 12 has passed the point C and reached the point S, and the controller 34 starts applying high frequency current to the high frequency surface hardening coil 30. Thereafter, the limit switch 35a detects that the center 21 has reached point A, and the controller 34 lowers the magnitude of the high frequency current as shown in FIG.

While the center 21 moves from point S to point A, the crankshaft IO rotates by a rotation angle of (360°-θ/2-C1). Next, the limit switch 35b detects that the center 21 has passed through the point C and reached the point B, and the controller 34
The magnitude of the high-frequency current is returned to its original magnitude. While the center 21 goes from point A to point B, the crankshaft 1
0 is the rotation angle and rotates by θ. Next, the high-frequency current of the original magnitude continues to be energized until the center 21 passes through points S and T and reaches point A, and the limit switch 35a detects that the center 21 has reached point A, and the controller 34, the magnitude of the high frequency current is reduced again. While the center 21 moves from point B to point A, the crankshaft 10 rotates by a rotation angle of (360°-θ).

Thereafter, the same energization cycle as above is repeated.

Immediately after the center 21 passes the point S for the first time, it is rotated by a predetermined rotation angle, that is, n x 360 degrees, to be located again at the point S, and then from this point S, the crankshaft 10
is the rotation angle and rotated by C2, center 2 at point T.
1 is detected by the limit switch 35t, and the controller 34 stops energizing the high-frequency surface hardening coil 30 to end the heating of the pin portion 12. That is, the high-frequency surface hardening coil 30 is energized while the crankshaft 10 rotates through an angle of n×360°+α2, and the high-frequency current is applied while the center 21 moves from point A to point B during each rotation. The magnitude of the current will be reduced.

In addition, as shown in FIG. 4, the pin part 12 has a columnar part 12.
1, an R section 122 following this, and a fillet section 123 following the R section 122 and formed in a direction perpendicular to the longitudinal direction of the crankshaft (direction of arrow A).

The hardened layer 125 is formed only on the columnar portion 121, and forming the hardened layer in this way is called flat hardening. Further, the hardened layer 126 is
21, is formed on all of the R portion 122 and the fillet portion 123, and forming a hardened layer in this way is called R hardening.

The high-frequency surface hardening method of the crankshaft of this embodiment can be applied to both the flat hardening and R hardening.

As explained above, according to the present invention, when the induction heating coil is energized to heat the heated portion of the crankshaft, the heated portion of the crankshaft that is rotationally driven is placed at a predetermined position. When the crankshaft reaches the specified angle, high-frequency current is applied to the induction surface hardening coil to start heating the heated part, and then when the crankshaft has rotated by a predetermined angle, the current is turned off and heating of the heated part is finished. This has the advantage that variations in the width, depth, etc. of the hardened layer formed on the heated portion of the crankshaft are reduced.

[Brief explanation of the drawing]

FIG. 1 is an embodiment of the present invention, and is a graph showing a method of applying a high-frequency current to a high-frequency surface hardening coil in high-frequency surface hardening of a crankshaft, in which the horizontal axis represents the rotation angle of the crankshaft; The vertical axis indicates the magnitude of high frequency current. FIG. 2 shows a cross section of the pin portion 12 of the crankshaft shown in FIG. 3, as well as an induction surface hardening coil and the like. FIG. 3 is a front view of a crankshaft subjected to induction hardening by the method of the present invention. Figure 4 is the third
It is an enlarged view of the pin part 12 of a figure. 11.12.13.14, ... pin part, 15.16.
17, 18.19... Journal portion, 21... Center, 22... Center, 23... Arc, 30... High frequency surface hardening coil, 31... Spacer, 32... Rotation angle Detector, 34...Controller, 35a, 35b
, 35s, 35t...Limit switch.

Claims (1)

[Claims] (1) When the heated part of the rotationally driven crankshaft comes to a predetermined position, a high-frequency current is applied to a high-frequency surface hardening coil that moves to follow the heated part to heat the heated part. A method for induction surface hardening of a crankshaft, characterized in that when the crankshaft has rotated by a predetermined angle, the current supply is stopped and the heating of the heated portion is completed.