JP2018003123A - Method of hardening crank shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of hardening a crank shaft capable of making a hardening depth equal.SOLUTION: In a hardening station 2, according to a journal part hardening map and a pin part hardening map, which define relationship between a rotation phase and a rotation speed of a crank shaft 4, a journal part 41 and a pin part 42 of the crank shaft 4 are hardened. The crank shaft 4 after the hardening is transferred to a measurement station 3, a hardening depth of each of the journal part 41 and the pin part 42 is detected. The journal part hardening map and the pin part hardening map are updated such that, based on the detection data of the hardening depth, the rotation speed of a phase position where the hardening depth is small is decreased, and the rotation speed of the phase position where the hardening depth is large is increased to make the hardening depth equal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for quenching a crankshaft. In particular, the present invention relates to an improvement for making the quenching depth uniform.

  Conventionally, a crankshaft used for an automobile engine or the like is subjected to a quenching process as a process for curing the surface of the sliding portion. Generally, induction hardening is performed on the pin portion and the journal portion of the crankshaft.

  Patent Document 1 discloses that induction hardening is performed on a pin portion of a crankshaft. In the induction hardening disclosed in Patent Document 1, the electric power supplied to the heating coil is kept constant, and the rotation speed of the crankshaft during induction hardening is determined when the pin portion passes the top dead center position. The highest is set to the lowest when the pin portion passes the bottom dead center position. That is, when the region having a relatively small heat capacity faces the heating coil, the rotation speed of the crankshaft is increased, and when the region having a relatively large heat capacity faces the heating coil, the rotation speed of the crankshaft is decreased. Yes. As a result, the heating temperature is uniformized at various locations of the pin portions having different heat capacities.

JP 2001-181739 A

  However, there are changes in conditions such as the material ratio of the crankshaft (workpiece), the ambient temperature during induction hardening, and the change in the thickness of the rough profile due to the wear of the mold used to form the crankshaft (forging, etc.). In this case, the processing conditions for making the quenching depth uniform are different. The technique disclosed in Patent Document 1 does not consider means for making the quenching depth uniform according to this change in conditions. For this reason, the quenching depth may become non-uniform depending on the change in conditions.

  As a result, the crankshaft may be deformed due to quenching distortion and the effect of residual stress release in the grinding process after quenching. In such a situation, the machining allowance of the crankshaft in the subsequent processing increases, the processing man-hour increases, and the energy required for processing increases.

  This invention is made | formed in view of this point, The place made into the objective is to provide the quenching method of the crankshaft which can make the quenching depth uniform.

  In order to achieve the above object, the solution of the present invention is a crankshaft quenching method in which a sliding portion of the crankshaft is quenched in the circumferential direction while rotating the crankshaft relative to a heating source. Assuming the insertion method. The crankshaft quenching method includes a step of quenching according to a map that defines a relationship between a rotation phase of the crankshaft relative to the heating source and a rotation speed of the crankshaft, and the crank after quenching. A step of acquiring quenching depth data at various locations in the circumferential direction of the sliding portion of the shaft, and at various locations in the circumferential direction of the sliding portion of the crankshaft based on the quenching depth data. Adjusting the rotation speed of the crankshaft in accordance with the rotation phase of the crankshaft with respect to the heating source so as to make the quenching depth uniform.

  Based on this specific matter, the crankshaft with respect to the heating source is made uniform so that the quenching depth at each location is uniform based on the data of the quenching depth at each location along the circumferential direction of the sliding portion of the crankshaft after quenching. The rotational speed of the crankshaft is adjusted according to the rotational phase. For example, for a phase portion where the quenching depth is small, the crankshaft is changed so that the rotational speed of the crankshaft when the phase portion faces the heating source is lowered at the next quenching. This increases the quenching depth at this phase location. On the other hand, the phase location where the quenching depth is large is changed so that the rotation speed of the crankshaft when the phase location faces the heating source is increased at the next quenching. Thereby, the quenching depth in this phase location becomes small. By adjusting the rotational speed of the crankshaft during quenching in this way, it is possible to make the quenching depth uniform in various places in the circumferential direction of the sliding portion.

  According to the present invention, the rotational speed of the crankshaft is adjusted in accordance with the rotational phase of the crankshaft with respect to the heating source based on the data of the quenching depth at various locations in the circumferential direction of the sliding portion of the crankshaft after quenching. I have to. For this reason, it becomes possible to equalize the quenching depth of each part over the circumferential direction of the sliding part of a crankshaft, and can suppress a deformation | transformation of a crankshaft.

It is a schematic diagram which shows schematic structure of a crankshaft hardening apparatus. It is a figure which shows the relationship between the rotational speed of the crankshaft at the time of induction hardening, and the heat input energy to a crankshaft. It is a figure for demonstrating the amount of heat transfer in the crankshaft at the time of induction hardening. It is sectional drawing of the crankshaft along the IV-IV line in FIG. It is a figure which shows an example of a journal part hardening map. It is sectional drawing of the crankshaft along the VI-VI line in FIG. It is a figure which shows an example of a pin part hardening map. It is a flowchart figure which shows the procedure of induction hardening operation | movement, hardening depth detection operation, and hardening map update operation | movement. FIG. 7 is a view corresponding to FIG. 6 for explaining the quenching depth detection operation.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where a crankshaft used for an automobile engine (for example, a four-cylinder gasoline engine) is induction-quenched will be described as an example.

(Crankshaft quenching device)
FIG. 1 is a schematic diagram showing a schematic configuration of a crankshaft quenching apparatus 1 for carrying out a quenching method according to the present invention.

  As shown in FIG. 1, the crankshaft quenching apparatus 1 includes a quenching station 2 and a measurement station 3. The quenching station 2 is a station that performs quenching processing of the crankshaft 4. The measurement station 3 is a station that measures (detects) the quenching depth of the crankshaft 4 after quenching in order to update the quenching map described later.

  The crankshaft 4 includes a journal portion 41 rotatably supported on a cylinder block (not shown), a pin portion 42 on which a connecting rod (not shown) is swingably supported, and these journals. The arm part 43 which connects the part 41 and the pin part 42, and the counterweight part 44 provided in the opposite side to the pin part 42 are provided. For this reason, the journal portion 41 and the pin portion 42 correspond to the “sliding portion of the crankshaft” in the present invention. The workpiece targeted by the crankshaft quenching apparatus 1 according to the present embodiment is a crankshaft 4 used in a four-cylinder gasoline engine. For this reason, the crankshaft 4 has five journal parts 41, four pin parts 42, eight arm parts 43, and eight counterweight parts 44.

  Hereinafter, the stations 2 and 3 will be described.

-Hardening station-
The quenching station 2 includes a clamp device 21, a rotation drive motor 22, a rotation control device 23, a calculation control device 24, and a high-frequency quenching device 25.

  The clamp device 21 supports the crankshaft 4 in a rotatable manner. In a state where the crankshaft 4 is supported by the clamp device 21, the crankshaft 4 is rotatable about the center line O as a rotation center.

  The rotational drive motor 22 is constituted by an electric motor, and transmits rotational force to the crankshaft 4 supported by the clamp device 21 to rotate the crankshaft 4 around the center line O as a rotation center. .

  The rotation control device 23 outputs a rotation speed command signal to the rotation drive motor 22, thereby controlling the rotation speed of the rotation drive motor 22. That is, the rotational speed of the crankshaft 4 is controlled.

  The arithmetic and control unit 24 stores therein a journal part quenching map and a pin part quenching map, and outputs a control signal in accordance with these quenching maps to the rotation control unit 23. Specifically, a plurality of journal part quenching maps corresponding to each journal part 41 are stored. Similarly, a plurality of pin part quenching maps corresponding to each pin part 42 are stored. When quenching the journal portion 41 of the crankshaft 4, a control signal (rotation according to the rotation phase of the crankshaft 4) according to the journal portion quenching map corresponding to the journal portion 41 to be quenched is performed. A speed control signal) is output from the arithmetic control device 24 to the rotation control device 23. Accordingly, the rotation control device 23 outputs a rotation speed command signal (a signal for instructing the rotation speed according to the journal part quenching map) to the rotation drive motor 22, thereby controlling the rotation speed of the rotation drive motor 22. Is done. On the other hand, when the pin portion 42 of the crankshaft 4 is quenched, a control signal (rotation according to the rotation phase of the crankshaft 4) according to the pin portion quenching map corresponding to the pin portion 42 to be quenched. A speed control signal) is output from the arithmetic control device 24 to the rotation control device 23. Along with this, a rotation speed command signal (a signal for instructing a rotation speed in accordance with the pin portion quenching map) is output from the rotation control device 23 to the rotation drive motor 22, thereby controlling the rotation speed of the rotation drive motor 22. It has come to be.

  The induction hardening device 25 includes a heating coil 25a as a heating source in the present invention, a quenching control device 25b, and an equipment control device 25c. The heating coil 25a receives high-frequency power from a high-frequency power source (not shown), so that a high-frequency current flows, whereby the surfaces of the journal portion 41 and the pin portion 42 are heated by high-frequency induction. Further, the heating coil 25a includes a moving mechanism (not shown) and can move in a direction along the center line O of the crankshaft 4. The moving mechanism moves the heating coil 25a in a direction perpendicular to the center line O so as to maintain a constant distance between the heating coil 25a and the pin part 42 when the pin part 42 is quenched. It also has a function to make it. The quenching control device 25b controls the supply and cut-off of the high-frequency power to the heating coil 25a, and controls the movement of the heating coil 25a by the moving mechanism, so that the heating coil 25a is connected to the journal portion 41 and the pin portion 42. It is designed to face each other. The equipment control device 25c transmits a quench control signal to the quench control device 25b. That is, according to this quenching control signal, the quenching control device 25b is configured to cause the heating coil 25a to be supplied and cut off from the heating coil 25a and to be moved by the moving mechanism.

  The output shaft of the rotary drive motor 22 is provided with a rotor 22a that can rotate integrally with the output shaft. Around the outer periphery of the rotor 22a, an angle encoder 22b for outputting a signal corresponding to the rotational angle position of the rotor 22a is disposed. The output signal of the angle encoder 22b is input to the arithmetic control device 24. As a result, the rotation angle position of the output shaft of the rotary drive motor 22 (corresponding to the rotation angle position (rotation phase) of the crankshaft 4) is obtained.

  Here, the journal part quenching map and the pin part quenching map stored in the arithmetic and control unit 24 will be described. These quenching maps are maps that prescribe the relationship between the rotational phase of the crankshaft 4 that is a workpiece and the rotational speed of the crankshaft 4 (rotational speed of the rotary drive motor 22) in response to induction hardening. .

  When the high frequency power to the heating coil 25a is constant, as shown in FIG. 2, the heat input energy to the crankshaft 4 increases as the rotation speed of the crankshaft 4 decreases. That is, when the heat capacity of the heating part in the crankshaft 4 and the heat transfer amount from the heating part are constant, the quenching depth becomes larger (deeper) as the rotation speed of the crankshaft 4 is lower. Thus, the quenching depth can be adjusted by adjusting the rotational speed of the crankshaft 4 during induction hardening.

  In view of this point, each quenching map has an area where the heat capacity is relatively small and an area where the heat transfer amount is small (area where the amount of heat escape is small) with respect to the journal portion 41 and the pin portion 42 of the crankshaft 4. The crankshaft 4 is rotated at a high rotational speed when facing the 25a, and when the region having a relatively large heat capacity or the region having a large amount of heat transfer (the region having a large amount of heat escape) faces the heating coil 25a, the crankshaft. The rotational speed of 4 is lowered.

  FIG. 3 is a diagram for explaining the amount of heat transfer in the crankshaft 4 when the journal portion 41 is induction hardened. In FIG. 3, the amount of heat transfer per unit time transmitted from the journal unit 41 to other parts is represented by the length of the arrow. As shown in FIG. 3, when heat is applied to the journal portion 41, the amount of heat transferred to the pin portion 42 having a relatively small volume is small, and the amount of heat transferred to the counterweight portion 44 having a relatively large volume is large. It has become. For this reason, in order to make the quenching depth uniform in each of the region on the pin portion 42 side and the region on the counterweight portion 44 side in the journal portion 41, the region on the pin portion 42 side in the journal portion 41 is a heating coil. It is necessary to relatively shorten the time facing the 25a, and relatively lengthen the time the region on the counterweight portion 44 side of the journal portion 41 faces the heating coil 25a. That is, the rotation speed of the crankshaft 4 when the region on the pin portion 42 side faces the heating coil 25a is increased, and the rotation of the crankshaft 4 when the region on the counterweight portion 44 side faces the heating coil 25a. The speed will be lowered.

  4 is a cross-sectional view of the crankshaft 4 taken along the line IV-IV in FIG. 3 (a cross-sectional view at the journal portion 41), and FIG. 5 is a diagram showing an example of the quenching map of the journal portion. Each phase (0 °, 90 °, 180 °, 270 °) of the crankshaft 4 in these drawings represents the rotational phase of the crankshaft 4 when the phase portion faces the heating coil 25a. For this reason, the journal part quenching map defines the rotational speed of the crankshaft 4 when each phase point faces the heating coil 25a during high frequency quenching of the journal part 41.

  As shown in these drawings, in the journal portion 41, when the region on the pin portion 42 side (region where the amount of heat transfer is small) faces the heating coil 25a (when the region of 90 ° phase in the drawing faces the heating coil 25a). ) Of the crankshaft 4 is increased, and the region on the counterweight portion 44 side (region with a large amount of heat transfer) in the journal portion 41 faces the heating coil 25a (the region of phase 270 ° in the figure is the heating coil). The journal portion quenching map is created so as to reduce the rotational speed of the crankshaft 4 (when facing 25a).

  FIG. 6 is a cross-sectional view (cross-sectional view at the pin portion 42) of the crankshaft 4 along the line VI-VI in FIG. 3, and FIG. 7 is a diagram showing an example of the pin portion quenching map. Also in these drawings, each phase (0 °, 90 °, 180 °, 270 °) of the crankshaft 4 (pin portion 42) is the rotational phase of the crankshaft 4 when the phase portion faces the heating coil 25a. Represents. For this reason, the pin portion quenching map defines the rotational speed of the crankshaft 4 when each phase portion faces the heating coil 25a when the pin portion 42 is induction hardened.

  The area on the upper side of the pin portion 42 in FIG. 6 (on the side opposite to the center line O of the crankshaft 4) has a relatively small heat capacity, whereas the lower side of the pin portion 42 in FIG. On the line O side), the heat capacity is relatively large. In view of this, the rotation speed of the crankshaft 4 is increased when the upper region of the pin portion 42 is opposed to the heating coil 25a (when the region having a phase of 90 ° in the drawing is opposed to the heating coil 25a). Pin portion quenching map so as to reduce the rotational speed of the crankshaft 4 when the lower region of the portion 42 faces the heating coil 25a (when the region of phase 270 ° in the drawing faces the heating coil 25a). Has been created.

  The present embodiment is characterized in that the quenching map is updated. Details of the update operation of the quenching map will be described later.

-Measurement station-
The measurement station 3 includes a clamp device 31, a rotation drive motor 32, a rotation control device 33, and a quenching depth detector 34.

  The clamp device 31, the rotation drive motor 32, and the rotation control device 33 have the same configuration as that provided in the quenching station 2 described above. In other words, the rotation control device 33 receives a control signal from the arithmetic control device 24 and outputs a rotation command signal from the rotation control device 33 to the rotation drive motor 32, whereby the crank supported by the clamp device 31. The shaft 4 is configured to rotate.

  The quenching depth detector 34 receives a command signal from the arithmetic and control unit 24 and detects the quenching depth in the journal part 41 and the pin part 42. The quenching depth in the journal part 41 and the pin part 42 can be detected. Since the principle of detecting the quenching depth using this ultrasonic wave is known, the description thereof is omitted here. The means for detecting the quenching depth is not limited to that using ultrasonic waves.

  Further, the quenching depth detector 34 includes a moving mechanism (not shown) and can move in the direction along the center line O of the crankshaft 4. In addition, when detecting the quenching depth of the pin portion 42, the moving mechanism sets the quenching depth detector 34 so as to keep the spacing between the quenching depth detector 34 and the pin portion 42 constant. A function of moving in a direction orthogonal to the center line O is also provided.

  The quenching depth detector 34 moves in a direction along the center line O of the crankshaft 4 by receiving a control signal from the arithmetic control device 24 and moves to a position facing the journal portion 41 and the pin portion 42. Thus, the quenching depth at each location can be detected. Information on the quenching depth in the journal part 41 and the pin part 42 is input to the arithmetic and control unit 24.

  Also in the measurement station 3, the output shaft of the rotary drive motor 32 is provided with a rotor 32 a that can rotate integrally with the output shaft. Around the outer periphery of the rotor 32a, an angle encoder 32b for outputting a signal corresponding to the rotational angle position of the rotor 32a is disposed. The output signal of the angle encoder 32b is input to the arithmetic control device 24. As a result, the rotation angle position of the output shaft of the rotary drive motor 32 (corresponding to the rotation angle position (rotation phase) of the crankshaft 4) is obtained.

(Induction hardening operation and hardening map update operation)
Next, the procedure of the induction hardening operation, the hardening depth detection operation, and the hardening map update operation by the crankshaft hardening apparatus 1 described above will be described with reference to the flowchart of FIG. In the procedure described below, high frequency quenching operation and quenching depth detection operation are sequentially performed on 10 workpieces (crankshaft 4), and data (10 (10)) obtained by this quenching depth detection operation is performed. A case where the quenching map is updated based on the quenching depth detection data in each crankshaft 4) will be described.

-Induction hardening operation-
When the induction hardening operation by the crankshaft hardening apparatus 1 is started, first, the crankshaft 4 (the first crankshaft 4 out of the ten crankshafts 4) formed by forging or the like and before the quenching process is first used. Then, it is rotatably set on the clamping device 21 of the quenching station 2. With the setting of the crankshaft 4, the value N of the work counter stored in the arithmetic control device 24 is reset to “0” in step ST1. This work counter is a counter that is incremented every time the induction hardening operation is completed for one crankshaft 4 (step ST6).

  In this state, the rotation drive motor 22 is actuated by a command signal from the rotation control device 23 to rotate the crankshaft 4. Then, when the rotation angle position of the crankshaft 4 detected based on the output signal from the angle encoder 22b reaches a predetermined initial position, the rotation drive motor 22 is stopped and the rotation angle position of the crankshaft 4 is determined. Then, the initial rotation angle position of the quenching operation is set (step ST2).

  After that, the rotational speed information corresponding to the rotation phase when quenching each journal part 41 of the crankshaft 4 from each journal part quenching map stored in the arithmetic control unit 24 and the arithmetic control unit 24 store it. The rotational speed information corresponding to the rotational phase at the time of quenching each pin portion 42 of the crankshaft 4 is read from each pin portion quenching map (step ST3).

  And induction hardening with respect to the crankshaft 4 is started (step ST4). At this time, the quenching control device 25b sends the heating coil 25a to the journal portion 41 of the crankshaft 4 (for example, the leftmost journal portion 41 in FIG. 1) by the moving mechanism based on the quenching control signal from the equipment control device 25c. The high frequency power is supplied to the heating coil 25a. The high frequency power at this time is kept constant during the quenching operation.

  When the journal unit 41 is quenched, a rotation speed command signal according to the rotation speed information read from the journal unit quenching map corresponding to the journal unit 41 to be quenched is sent from the rotation control device 23. It is output to the rotation drive motor 22. Thereby, the rotational speed of the rotary drive motor 22 (the rotational speed of the crankshaft 4) at the time of quenching the journal portion 41 is controlled, and high-frequency quenching is executed. That is, the rotation speed of the crankshaft 4 when the region on the pin portion 42 side in the journal portion 41 faces the heating coil 25a is set high, and the region on the counterweight portion 44 side in the journal portion 41 faces the heating coil 25a. The rotational speed of the crankshaft 4 at that time is set low, and induction hardening is performed over the entire circumference of the journal portion 41.

  After the entire periphery of the journal portion 41 of the crankshaft 4 (for example, the leftmost journal portion 41 in FIG. 1) is induction hardened, the heating coil 25a is moved in the direction along the centerline O of the crankshaft 4 by the moving mechanism. The heating coil 25a is opposed to the pin portion 42 of the crankshaft 4 (for example, the leftmost pin portion 42 in FIG. 1), and high frequency power is supplied to the heating coil 25a. When the pin portion 42 is quenched, a rotation speed command signal according to the rotation speed information read from the pin portion quenching map corresponding to the pin portion 42 to be quenched is sent from the rotation control device 23. It is output to the rotation drive motor 22. As a result, the rotational speed of the rotary drive motor 22 (the rotational speed of the crankshaft 4) during the quenching of the pin portion 42 is controlled, and high-frequency quenching is executed. That is, the rotation speed of the crankshaft 4 when the region opposite to the centerline O of the crankshaft 4 in the pin portion 42 faces the heating coil 25a is set high, and the centerline O of the crankshaft 4 in the pin portion 42 is set. The rotational speed of the crankshaft 4 when the side region faces the heating coil 25a is set low. As a result, similarly to the journal portion 41 described above, the pin portion 42 is subjected to induction hardening over the entire periphery thereof.

  In this way, while moving the heating coil 25a in the direction along the centerline O of the crankshaft 4, all the journal portions 41 (five journal portions 41) and all the pin portions 42 (four pins) The whole periphery of the part 42) is induction-hardened.

  When induction hardening is completed for all the journal portions 41 and all the pin portions 42, YES is determined in step ST5. Thereafter, the crankshaft 4 subjected to induction hardening is moved from the quenching station 2 to the measuring station 3. That is, the support state of the crankshaft 4 by the clamping device 21 in the quenching station 2 is released, and the crankshaft 4 is set in the clamping device 31 in the measurement station 3. With the setting of the crankshaft 4, the value N of the work counter is incremented (N ← N + 1) in step ST6.

-Hardening depth detection operation-
Next, the quenching depth detection operation in the measurement station 3 is performed. In this quenching depth detection operation, the rotation drive motor 32 is actuated by a command signal from the rotation control device 33 to rotate the crankshaft 4. Then, when the rotation angle position of the crankshaft 4 detected based on the output signal from the angle encoder 32b reaches a predetermined initial position, the rotation drive motor 32 is stopped and the rotation angle position of the crankshaft 4 is determined. The initial rotation angle position of the quenching depth detection operation is set.

  Thereafter, the quenching depth detection operation for the crankshaft 4 is started (step ST7). At this time, in accordance with a control signal from the arithmetic control unit 24, the quenching depth detector 34 is opposed to the journal portion 41 (for example, the leftmost journal portion 41 in FIG. 1) of the crankshaft 4 by the moving mechanism. The quenching depth data is acquired over the entire periphery of the unit 41 and transmitted to the arithmetic control device 24.

  After acquiring the quenching depth data over the entire circumference of the journal portion 41 of the crankshaft 4 (for example, the leftmost journal portion 41 in FIG. 1), the quenching depth detector 34 is connected to the crankshaft 4 by the moving mechanism. The quenching depth detector 34 is moved in a direction along the center line O so as to oppose the pin portion 42 of the crankshaft 4 (for example, the pin portion 42 at the left end in FIG. 1), and extends all around the pin portion 42. Then, the quenching depth data is acquired and transmitted to the arithmetic and control unit 24. FIG. 9 is a cross-sectional view of the crankshaft 4 during the quenching depth detection operation. As shown in this figure, the quenching depth detector 34 is opposed to the pin portion 42 and the crankshaft 4 is rotated, and the quenching depth data is acquired over the entire circumference of the pin portion 42. The data is transmitted to the arithmetic control device 24.

  In this way, while moving the quenching depth detector 34 in the direction along the center line O of the crankshaft 4, all the journal portions 41 (five journal portions 41) and all the pin portions 42 ( The quenching depth data of the entire periphery of the four pin portions 42) are acquired.

  When the acquisition of the quenching depth data for all the journal portions 41 and all the pin portions 42 is completed, a YES determination is made in step ST8. Thereafter, in step ST9, the value N of the work counter is “10”, that is, whether or not the induction hardening operation and the hardening depth detection operation have been completed for the ten crankshafts 4. Determine.

  If the number of crankshafts 4 for which the induction hardening operation and the quenching depth detection operation have been completed has not yet reached 10 and the determination in step ST9 is NO, the process returns to step ST2 and the next crankshaft 4 Induction hardening operation and quenching depth detection operation are started.

-Hardening map update operation-
In this way, the induction hardening operation and the quenching depth detection operation for the crankshaft 4 are repeated, and when the number of crankshafts 4 for which the induction hardening operation and the quenching depth detection operation have been completed reaches ten, YES is determined in step ST9, and the process proceeds to step ST10. In this step ST10, the average value of the quenching depth of each journal part 41 and each pin part 42 obtained by the quenching depth detection operation is calculated. Specifically, the average value of the quenching depth is calculated individually for each journal portion 41 and each pin portion 42.

  Then, in step ST11, a deviation between the average value of the quenching depth of each journal part 41 and each pin part 42 and the quenching depth at each part of each journal part 41 and each pin part 42 is obtained. Is calculated as a quenching depth correction amount in each of the above-mentioned places. For example, with respect to the average value of the quenching depths at the various places in the circumferential direction of the journal portion 41 at the left end in FIG. Calculated as the insertion depth correction amount. In the same manner for the other journal portions 41 and pin portions 42, the quenching depth correction amount at each location is calculated.

  That is, when the actual quenching depth is smaller than the average value of the quenching depth, the quenching depth of the phase location is set so that the quenching depth is increased by the deviation. A correction amount is given. On the other hand, in the phase location where the actual quenching depth is large with respect to the average value of the quenching depth, the quenching depth of the phase location is reduced so as to reduce the quenching depth by the deviation. A correction amount is given.

  In step ST12, the rotational speed information of each journal part quenching map and the rotational speed information of each pin part quenching map are corrected in accordance with the quenching depth correction amount, thereby updating each quenching map. To do. That is, the quenching map is updated so that the rotational speed of the crankshaft 4 is lowered when the phase portion to which the quenching depth correction amount for increasing the quenching depth is opposed to the heating coil 25a. Further, the quenching map is updated so that the rotational speed of the crankshaft 4 is increased when the phase portion to which the quenching depth correction amount for decreasing the quenching depth is opposed to the heating coil 25a.

  In the next induction hardening operation of the crankshaft 4, the crankshaft 4 at the time of induction hardening is used by utilizing the updated rotation speed information of each journal portion quenching map and the rotation speed information of each pin portion quenching map. The rotation speed is controlled. That is, for the phase location where the quenching depth has been reduced, the rotational speed of the crankshaft 4 when the phase location faces the heating coil 25a is lowered in the next high-frequency quenching operation. The quenching depth at this phase point is increased. On the other hand, for the phase location where the quenching depth is large, the rotational speed of the crankshaft 4 when the phase location faces the heating coil 25a is increased in the next high-frequency quenching operation. The quenching depth at this phase point is reduced. Thus, by adjusting the rotational speed of the crankshaft 4 during quenching, the quenching depth of each journal portion 41 and each pin portion 42 can be made uniform.

  Since the above-described induction hardening operation, quenching depth detection operation, and quenching map update operation are performed, the operations in step ST3 and step ST4 are performed according to the present invention as “the rotation phase of the crankshaft relative to the heating source and the crank. This corresponds to “a step of quenching according to a map that defines a relationship with the rotational speed of the shaft”. In addition, the operation of step ST7 corresponds to the “step of obtaining quenching depth data at various locations in the circumferential direction of the sliding portion of the crankshaft after quenching” according to the present invention. Further, the operations of steps ST10 to ST12 and the next quenching operation using the quenching map updated in step ST12 are performed according to the present invention, based on the “quenching depth data”. This corresponds to the step of adjusting the rotational speed of the crankshaft in accordance with the rotational phase of the crankshaft with respect to the heating source so that the quenching depths at various locations in the direction are uniform.

  As described above, in the present embodiment, the quenching depth at each location is based on the quenching depth data at each location in the circumferential direction of each journal portion 41 and each pin portion 42 of the crankshaft 4 after quenching. The journal part quenching map and the pin part quenching map are updated so as to make the same. That is, the rotational speed of the crankshaft 4 is adjusted according to the rotational phase of the crankshaft 4 with respect to the heating coil 25a. As a result, it is possible to make the quenching depth uniform at various locations in the circumferential direction of each journal portion 41 and each pin portion 42. For this reason, it becomes possible to reduce the machining allowance of the crankshaft 4 in the process after induction hardening, the processing man-hours can be reduced, and the energy required for the process can be reduced.

  In the present embodiment, the high-frequency power supplied to the heating coil 25a is kept constant during the quenching operation. As a means for adjusting the quenching depth, it is also known to adjust the high-frequency power, but in this case, a deviation occurs between the adjustment timing of the high-frequency power and the timing at which a predetermined heat input amount is obtained in the crankshaft 4. Therefore, it is difficult to appropriately adjust the quenching depth. According to this embodiment, since it is not necessary to adjust this high frequency power, it is possible to appropriately adjust the quenching depth.

  In the prior art, when post-processing of the quenched crankshaft, it is necessary to measure the amount of deformation of the crankshaft due to quenching distortion or the like. According to the present embodiment, since variation data of the quenching depth of the crankshaft 4 is reflected and the rotational speed of the crankshaft 4 is controlled to perform high-frequency quenching, the variation in deformation amount of the crankshaft is small. Accordingly, it is possible to eliminate the need to measure the deformation amount for each crankshaft 4. Further, as the accumulated amount of the quenching depth variation data increases (as each quenching map is updated), the quenching depth becomes uniform, and the deformation amount of the crankshaft 4 also decreases. It will become. As a result, the number of defective crankshafts 4 can be greatly reduced.

(Other embodiments)
The embodiment described above has been described by taking as an example the case of induction hardening of a crankshaft used in a four-cylinder gasoline engine. The present invention is not limited to this, and can also be applied to a crankshaft used in an engine having three or less cylinders or an engine having five or more cylinders. The present invention can also be applied to a crankshaft used in a diesel engine.

  In the embodiment, the journal part quenching map is stored corresponding to each journal part 41, and the pin part quenching map is stored corresponding to each pin part 42. The present invention is not limited to this, and if the heat capacity and heat transfer amount in each journal part 41 can be handled as substantially the same, the journal part quenching map used for quenching each journal part 41 can be shared. Good. Similarly, when it can be handled that the heat capacity and heat transfer amount in each pin part 42 are substantially the same, the pin part quenching map used for quenching each pin part 42 may be shared.

  The present invention is applicable to a quenching method in which a journal portion and a pin portion of a crankshaft used for an automobile engine are induction-quenched.

DESCRIPTION OF SYMBOLS 1 Crankshaft hardening apparatus 2 Quenching station 22 Rotation drive motor 23 Rotation control apparatus 24 Calculation control apparatus 25a Heating coil (heating source)
3 Measurement station 34 Hardening depth detector 4 Crankshaft 41 Journal part (sliding part)
42 Pin part (sliding part)

Claims (1)

A crankshaft quenching method in which the crankshaft sliding portion is quenched over its circumferential direction while rotating the crankshaft relative to a heating source,
Performing the quenching according to a map defining a relationship between a rotational phase of the crankshaft relative to the heating source and a rotational speed of the crankshaft;
A step of obtaining quenching depth data at various locations in the circumferential direction of the sliding portion of the crankshaft after quenching;
Based on the quenching depth data, the quenching depth of the crankshaft with respect to the heating source in accordance with the rotational phase of the crankshaft is made uniform so that the quenching depth is uniform at various locations in the circumferential direction of the sliding portion of the crankshaft. Adjusting the rotational speed of the crankshaft, and a method for quenching the crankshaft.

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