JPH0438824B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an induction hardening method for the pin portion of a crankshaft.

Conventional technology Conventionally, when the crankshaft is rotated around the central axis and an energized high-frequency surface hardening coil is placed on the pin portion to perform induction surface hardening on the pin portion, a In order to make the width of the hardened layer uniform, the high frequency surface hardening coil is energized by
The section between the predetermined position before the top dead center of the pin part and the top dead center, and the predetermined section between the top dead center and the predetermined section after the top dead center are subjected to high frequency surface hardening more than the sections other than the above two sections. A method has been adopted to reduce the power applied to the coil (Japanese Patent Application No. 62-333084).

When such hardening is performed, high-frequency current is applied to the high-frequency surface hardening coil for a predetermined period of time determined in advance through experiments or the like.

Problems to be Solved by the Invention However, in recent years, requirements have become increasingly strict regarding the range of variation in the width and depth of the hardened layer formed on the pin portion of the crankshaft. It has become difficult to meet this requirement simply by heating for a predetermined period of time.

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

Means for Solving the Problems In order to solve the above problems, the present invention includes a semi-open saddle-type high-frequency surface-hardened coil mounted on the crankshaft and pin portion, and the crankshaft is rotated around the central axis. At each rotation of the crankshaft, the pin portion rotates in the first section between the top dead center and a predetermined position before the top dead center, and in the first section between the top dead center and a predetermined position after the top dead center. The electric power applied to the high-frequency surface-hardened coil is made smaller than the electric power applied to the high-frequency surface-hardened coil in sections other than both the first and second sections, and only while passing through the second section between The application of electricity to the surface hardening coil is started and stopped when the pin portion rotates by a predetermined angle from the top dead center in sections other than the first and second sections.

Embodiment FIG. 1 is an explanatory diagram of an embodiment of the present invention.
This is a graph showing how high-frequency current is applied to the high-frequency surface-hardened coil in induction hardening of the pin portion of the crankshaft. The horizontal axis represents the rotation angle of the crankshaft, and the vertical axis represents the high-frequency surface-hardened coil. Indicates the magnitude of the high-frequency current applied to the
FIG. 2 shows a cross section of the pin portion 12 of the crankshaft shown in FIG. 3 and the induction hardened coil.
FIG. 3 is a front view of a crankshaft whose pin portion is surface hardened by induction hardening according to the method of the present invention.
FIG. 4 is an enlarged view of the pin portion 12 in FIG. 3.

As shown in FIG. 3, the crankshaft 10 includes integrally formed pin parts 11, 12, 13, 14,
and journal parts 15, 16, 17, 18, 1
It has 9. When the pin portion of the crankshaft 10 is subjected to induction surface hardening, hold both ends of the crankshaft 10 with a center pin or the like so that the longitudinal direction of the crankshaft 10 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 from above, and a high-frequency current is applied to the high-frequency surface hardening coil. This high frequency surface hardening coil uses a semi-open saddle type coil.

FIG. 2 shows a cross section of the pin portion 12 of the crankshaft 10 and the high frequency surface hardening coil 30, 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. Yes, 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 arrow P, the center 21 of the cross section of the pin portion 12 moves on a circular arc 23 about 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, 31 that maintains contact with the outer surface of the pin part 12, and which resists the movement of the pin part 12. Correspondingly, a known pantograph mechanism (not shown) follows the movement of the pin portion 12 by reciprocating in the directions of arrows R and S. 32 is a rotation angle detector such as a rotary encoder for detecting the rotation angle of the crankshaft 10. The rotation angle detector 32 is
A signal indicating the rotation angle of the crankshaft 10 is sent to a controller 34 via a signal line 33. Controller 34
controls the opening/closing of the high frequency current applied to the high frequency surface hardening coil 30 and the magnitude of this high frequency current, that is, the control of the electric power applied to the high frequency surface hardening coil 30.

Next, referring to FIGS. 1 and 2, the induction hardening method for the pin portion of the crankshaft of the present invention will be explained. 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 reaches the highest position (top dead center).
Before the center 21 reaches point C, the angle of rotation of the crankshaft 10 is 1/1 of a predetermined angle θ (usually selected from a range of 15° to 80° depending on the specifications of the required hardened layer). Let point A be the position of the center 21 where θ/2 is 2. Also, center 21
is past point C and the position where the rotation angle of the crankshaft 10 is θ/2 is defined as point B.

Furthermore, the position of the center 21 at the position where energization of the induction hardening coil 30 is first started after the crankshaft 10 starts rotating, and at the position where the crankshaft 10 rotates a predetermined angle from this position and stops energization. Let them be a point S and a point T, respectively. The positions of these points S and T are located on the arc 23 drawn by the center 21 of the pin part 12 in a section other than the section from point A to point B passing through point C, that is, on the high frequency surface hardening coil 30. It is selected at a predetermined position within the section excluding the section where small electric power is applied. This means that if from point A to point C
In the middle of the section up to point B, that is, when the energization is stopped while the power applied to the high-frequency surface hardening coil 30 is being reduced, or when the energization is started at a reduced power. This prevents a difference from occurring between the hardened layer formed by starting and stopping energization when power is not being reduced.

The predetermined positions of these points S and T are determined by n (a positive integer,
(represents the rotational speed of the crankshaft 10 after the start of energization of the high-frequency surface hardening coil 30), and is set in advance. Note that α ₁ and α ₂ are rotation angles of the crankshaft 10 when the center 21 moves from point C to point S and from point S to point T, respectively, in the direction of arrow P. Points A, B, C, S and T in FIG. 1 correspond to points A, B, C, S and T in FIG. 2, respectively.

The rotation angle detector 32 is connected to the crankshaft 10
The rotation angle of the crankshaft 10 in the direction of the arrow P is detected, with the time when the center 21 first reaches the position of the point C as being 0 degrees when the crankshaft 10 starts rotating. and,
When the center 21 reaches the point S for the first time from the point C, the rotation angle detector 32 detects the angle α ₁ and sends a signal to the controller 34 to energize the high frequency surface hardening coil 30 to change the position of the pin part 12. Heating begins.

When the center 21 reaches point A shown in FIG.
When 1 comes to point A for the first time, 360°-θ/2, 2
When it reaches the third time, it detects 2×360°-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 reaches point B, the rotation angle detector 32 detects the angle at which the center 21 has moved (for example, after starting energization to the high-frequency surface hardening coil 30
When it comes to point B for the first time, it detects 360° + θ/2, and when it comes for the second time, it detects 2 × 360° + θ/2).
A signal is sent to the controller 34 to return the current to the high frequency surface hardening coil 30 to its original magnitude.

Next, the center 21 rotates n times from the point S and returns to the point S.
When the rotation angle detector 32 reaches point T after further rotation, the rotation angle detector 32 detects the angle (α ₁
+n×360°+α ₂ ) is detected, and a signal is sent to the controller 34 to stop energizing the high-frequency directional hardening coil 30, thereby ending the heating of the pin portion 12.

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 the signal, the controller 34 can turn on/off the energization to the high-frequency surface hardening coil 30 or control the magnitude of the energizing current.

In addition, as shown in FIG.
2, a fillet portion 12 formed in a direction perpendicular to the longitudinal direction (direction of arrow A) of the crankshaft.
There are 3. The hardened layer 125 is formed only on the cylindrical portion 121, and forming the hardened layer in this way is called flat hardening. Further, the hardened layer 126 is formed on all of the columnar portion 121, the R portion 122, and the fillet portion 123, and forming the hardened layer in this manner is called R hardening. The high frequency surface hardening method of the pin portion of the crankshaft of this embodiment can be applied to both the flat hardening and R hardening.

Effects of the Invention As explained above, according to the present invention, in order to perform induction surface hardening on the pin portion of a rotationally driven crankshaft, electric power is applied to the high frequency surface hardening coil before and after the top dead center of the pin portion. is smaller than other sections, and the pin section is rotated by a predetermined angle from top dead center in sections other than the power reduction section when starting and stopping energization to the high-frequency surface hardening coil. I'm going with the position.

Therefore, according to the high-frequency high-frequency surface hardening method of the pin portion of a crankshaft of the present invention, variations in the width, depth, etc. of the hardened layer formed on the pin portion can be reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention,
This is a graph showing how high-frequency current is applied to the high-frequency surface hardening coil during induction surface hardening of a crankshaft, where the horizontal axis represents the rotation angle of the crankshaft and the vertical axis represents the magnitude of the 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. 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. 11, 12, 13, 14...pin part, 15, 1
6, 17, 18, 19... journal section, 21...
...center, 22...center, 23...arc, 30...
High frequency surface hardening coil, 31...Spacer, 32
...Rotation angle detector, 34...Controller.

Claims (1)

[Claims] 1 A half-open saddle-shaped high-frequency surface-hardened coil is placed on the pin of the crankshaft, and while the crankshaft is rotating around the central axis, the pin is positioned just before top dead center during each rotation of the crankshaft. The high-frequency surface-hardened coil only passes through a first section between a predetermined position and top dead center, and a second section between top dead center and a predetermined position after top dead center. The applied power is smaller than the power applied to the high frequency surface hardening coil in sections other than the first and second sections, and the pin part controls the start and stop of energization to the high frequency surface hardening coil. Said first,
An induction surface hardening method for a pin portion of a crankshaft, characterized in that the method is performed when the pin portion of a crankshaft is rotated by a predetermined angle from top dead center in each section other than the second section.