JPH01319633A - High-frequency surface hardening method for crank shaft - Google Patents

Abstract

PURPOSE:To prevent the fluctuation in a quench-hardened layer by energizing and de-energizing an induction heating coil in a specific position according to the rotation of the crank shaft at the time of hardening the part to be heated of the crank shaft by heating with the heating coil. CONSTITUTION:The hardening coil 30 of the pin part 12 of the crank shaft 10 is brought into contact with the pin part 12 at a specified spacing from said part via a spacer 31 at the time of subjecting the pin part 11-14 of said crank shaft to the surface hardening by high-frequency heating. The coil is moved back and forth in arrow R and S directions in accordance with the movement of the pin part 12 so as to follow up said movement. The crank shaft 10 is rotated around an axial center 22 and the pin part 12 revolves in a P direction while rotating in a Q direction. An angle detector 32 detects the rotating angle alpha1 of the pin part 12 upon arrival of the center 21 of said part at the point S from the point C and sends a detection signal to a controller 34 which energizes the coil 30 to start heating of the pin part 12. The detector 32 detects the rotating angle (alpha1+nX360 deg.+alpha2) and stops the energization to the coil 30 to end the heating of the pin part 12 when the center 21 rotates n times from the point S and arrives at the point T after arriving again at the point S. The pin part 12 having no fluctuations in the width and depth of the hardened layer is thus obtd.

Description

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

Conventional ■ Limb blood Conventional When performing induction surface hardening on the heated parts of the crankshaft pins and journals, the current is applied 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 demands on 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 satisfy this requirement simply by heating the heated portion of the steel 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 irregularities in the width, depth, etc. of the hardened layer formed on the heated portion of the crankshaft. The purpose is

In order to solve the problem of f-stage or higher gears, the present invention provides a system for detecting when the heated portion of the rotationally driven crankshaft has reached a predetermined position by adjusting the rotation angle of the crankshaft. A high-frequency current is applied to a high-frequency surface hardening coil that is detected by a detector and moves to follow the heated part, and heating of the heated part is started, and then the crankshaft is rotated by a predetermined angle. An angle detector detects this and stops the energization, thereby ending the heating of the heated portion.

B1 The crankshaft is driven to rotate, and the high-frequency surface hardening coil moves following the heated portion of the crankshaft. The rotation angle detector detects that the heated part of the crank shirt has arrived at the predetermined position, and energization is started to the high-frequency surface hardening coil, which starts heating the heated part. After that, the energization continues. After the heating of the crankshaft is started, the rotation angle detector detects that the crankshaft has rotated by a predetermined angle, and the energization is stopped to end the heating of the heated portion.

Embodiment FIG. 1 C; 1 This is an embodiment of the invention, and is a graph showing a method of applying a high JO wave current to an induction surface hardening coil in induction surface hardening of a crankshaft, in which the horizontal axis represents the crankshaft. The rotation angle of the shaft is shown, and the vertical axis shows the magnitude of the high-frequency current. FIG. 2 shows a cross section of the pin portion 12 of the crankshaft shown in FIG. 3Q and the induction hardened coil. FIG. 3 is a front view of a crankshaft subjected to induction hardening by the method of the present invention. Fourth
The figure is an enlarged view of the pin portion 12 in FIG. 3.

As shown in FIG. 3, the crankshaft 10 includes an integrally formed pin portion 1112, I3.
It has a wall section 15, 16, 17, 18, 19. When the pins and glossy parts of this crank shirt 1-10 are subjected to induction hardening, hold both ends of the crank shirt 1-10 with a center bin or the like so that the longitudinal direction of the crank shirt 1-10 is horizontal. In this state, while rotating the crankshaft 10, 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. A semi-loop saddle coil is used for heating.

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 the crankshaft 10, 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 the arrow P, the center 2 of the cross section of the pin portion 12 is rotated.
1 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 I).

30 is an induction surface hardened coil which is spaced a predetermined distance from the pin part 12 by a pair of spacers 31, 31 which maintain contact with the outer surface of the pin part 12, and which corresponds to the movement of the pin part 12. A known pantograph mechanism (not shown) follows the movement of the pin portion 12 by reciprocating in the directions of arrows R and S.

Reference numeral 32 denotes a rotation angle detector such as a rotary encoder, which detects the rotation angle of the crank shirt [10]. The rotation angle detector 32 sends a signal indicating the rotation angle of the crankshaft 10 to the controller 34 via a signal line 33. The controller 34 controls the opening and closing of the high frequency current supplied to the high frequency surface hardening coil 30 and the magnitude of this high frequency current.

Next, the induction hardening method for the pin portion of a crankshaft according to the present invention will be explained with reference to FIGS. 1 and 2. Point C is the position of the center 2I 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. Point A is the position of the center 21 before the center 21 reaches point C, where the rotation angle of the crankshaft 10 is θ/2, which is 1/2 of the predetermined angle θ.

Also, when the center 21 passes the point C, the crankshaft→・foot 1
Let point B be the position where the rotation angle is 0 and θ/2. Further, after the crankshaft 10 starts rotating, the center 21 is at a position where the induction current is first started to be energized and the crankshaft 10 is rotated by a predetermined angle from this position and the energization is stopped. Let the positions be point S and point T, respectively. These points S and T
The position of n (a positive integer representing the number of revolutions of the crankshaft 10 after the start of energization of the induction hardening coil 30) is determined according to the required width, depth, and variations thereof of the hardened layer. ) is set in advance.

Also, when the center 21 moves from point C to point S and from point S to point 1'' in the direction of arrow P, the crankshaft 10
The rotation angles of are α and α2, respectively. Points A, B, C, S and T in Figure 1 are respectively points A, B, C, S and T in Figure 2.
It corresponds to B, C, S and T.

The rotation angle detector 32 takes the position of the center 21 at the point C as 0 degrees, and detects the rotation angle of the crankshaft 10 in the direction of the arrow P.
Detect the rotation angle. Then, when the center 21 comes from point C to point S for the first time, the rotation angle detector 32 detects the angle α1, sends a signal to the controller 34, and energizes the high frequency surface hardening coil 30 to Heating begins. Next, when the center 21 rotates n times from point S to point S, and then further rotates to point 'I'', the rotation angle detector 32 detects the angle (αI −+− n
X350°-)-α2) is detected, and a signal is sent to the controller 34 to stop energizing the high-frequency surface hardening coil 30, thereby ending the heating of the pin portion 12.

Further, the high frequency surface hardening coil 30 can also be energized as follows. That is, the induction hardened coil 30
While being energized as described above, when the center 21 reaches the point △ shown in the second time, the rotation angle detector 32 detects the angle at which the center 21 has moved (for example, after the start of energization to the high-frequency surface hardening coil 30 When the center 21 comes to point A for the first time, it is 360
°-θ/2.When it comes to the second time, it is 2 x 360°-
θ/2) and sends a signal to the controller 34 to reduce the magnitude of the current flowing to the high frequency surface hardening coil 30. When the center 21 passes point A and comes to point B, the rotation angle detector 32 detects the angle at which the center 21 has moved (for example, when the center 21 reaches point B for the first time after starting energization to the high-frequency surface hardening coil 30)
When it comes, it detects 360° + θ/2. When it comes the second time, it detects 2 × 360° - ÷ θ/2), and sends a signal to the controller 34 to control the current flowing to the high-frequency surface hardening coil 30. Return to original size.

As described above, the rotation angle detector 32 detects that the center 21 of the pin portion 12 has come to points S, A, B, and T, and sends signals corresponding to these points to the controller 34. Based on this signal, the controller 34 controls the high frequency surface hardening coil 3.
It is possible to open and close energization to 0 and control the magnitude of the energized current.

In addition, as shown in FIG. 4, the pin part 12 has a columnar part 12.
There are a fillet portion 123 formed in a direction perpendicular to the longitudinal direction of the crankshaft (direction of arrow A) following the eighth portion 122.

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
It is formed on all of the 21.8 part 122 and the fillet part 123, and forming a hardened layer in this way is called R hardening.

The high-frequency surface hardening method of the crankshaft according to this embodiment can be applied to both of the above-mentioned graph I hardening and R hardening. Further, the same can be applied to the journal portion.

As described above, according to the present invention, the rotation angle detector of the crankshaft detects that the heated portion of the rotationally driven crankshaft has come to a predetermined position, and the heated portion of the crankshaft is detected. A high-frequency current is applied to the high-frequency surface-hardened coil that follows the heating section to start heating the heating section, and then the rotation angle detector detects that the crankshaft has rotated by a predetermined angle and turns on the current. Since the heating of the heated portion is completed by stopping, there is an advantage that variations in the width, depth, etc. of the hardened layer formed on the heated portion of the crank shirt (.) 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 and the induction hardened coil. The third is a front view of the crank shirt 1 subjected to induction surface hardening by the method of the present invention. FIG. 4 is an enlarged view of the pin portion 12 in FIG. 3. 11.12.13.14, ... pin part, 15.16.
17.18.19... Journal portion, 21... Center, 22... Center, 23... Circular arc, 30... High frequency surface hardening coil, 31... Spacer, 32... Rotation angle Detector, 34...controller.

Claims (1)

[Claims] (1) A rotation angle detector of the crankshaft detects that the heated part of the rotationally driven crankshaft has come to a predetermined position, and a high-frequency current is applied to the high-frequency surface hardening coil that moves to follow the heated part. Electrification is applied to start heating the heated part, and then the rotation angle detector detects that the crankshaft has rotated by a predetermined angle, and the energization is stopped to finish heating the heated part. This is an induction hardening method for crankshafts.