JP2008202099A - Induction heat treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heat treatment apparatus which can retreat an induction heating coil, so as to keep a gap between the induction heating coil and a localized area to be heated constant, through a high-frequency induction heating operation. <P>SOLUTION: The induction heat treatment apparatus 10 comprises: a workpiece driving means 11 for driving a workpiece; the induction heating coil 15 for induction-heating the workpiece 20; a supporting and moving means 14 for supporting and moving the induction heating coil 15; and a displacement measurement means 40 for measuring a thermal expansion displacement of the workpiece. The displacement measurement means 40 has a contact shoe 43 and a distance sensor 41. The contact shoe 43 is connected with a displacement detection shaft 41a of the distance sensor 41 so that the distance sensor 41 conducts heat so as to be kept into its heat-resistant temperature or lower. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high-frequency heat treatment apparatus. More specifically, when high-frequency induction heating is performed in the vicinity of a heated portion of a workpiece, the dimensional change accompanying the heating of the workpiece is accurately measured, and an induction heating coil and The present invention relates to a high-frequency heat treatment apparatus capable of performing heat treatment while maintaining a constant distance from a workpiece.

  For example, heat treatment by high frequency induction heating is applied to an internal gear that is a large-diameter ring body provided in a concrete mixer truck. In order to impart hardness and wear resistance to the tooth surface of the internal gear, a plurality of induction heating coils are arranged inside the internal gear, and each induction heating coil is placed between every other tooth and tooth valley. High frequency induction heating is performed in the proximity state. When heating is finished, each induction heating coil is moved to a position where it does not interfere, and then the internal gear is rotated by a fixed angle to stop it. Heating is repeated, and the internal gear is rotated twice to heat all the tooth surfaces to, for example, 1000 ° C., and then rapidly cooled to perform heat treatment. At this time, a device has been devised so that high-frequency induction heating can be performed uniformly while keeping the gap between the induction heating coil and the tooth surface constant (see Patent Document 1). However, this heating method requires a very long processing time.

  Therefore, in order to shorten the processing time, a race groove having a semicircular cross section is provided around the outer peripheral surface of the internal gear, and the arc-shaped induction heating coil is provided close to the race groove as a heated portion. A high-frequency heat treatment apparatus for large-diameter ring bodies that has been subjected to high-frequency induction heating and then rapidly cooled has been developed and put into practical use.

  In the heat treatment apparatus, a large-diameter ring body having an outer periphery on a circumferential surface and a heated local portion that goes around the circumferential surface on the circumferential surface is placed on a table, and a pair of substantially semicircular ring body shapes is placed. The induction heating coils are moved closer to each other so as to sandwich the large-diameter ring body from the standby positions on both sides of the large-diameter ring body, and the pair of induction heating coils are brought close to the heated local portion to perform high-frequency induction heating. According to this heating method, the processing time is shortened, but the pair of induction heating coils are not in a state of being combined with a complete semicircle into a circle and being close to the heated local part. There is a problem that high-frequency induction heating is insufficient between the end portion and the end portion of the other induction heating coil, and this portion is not sufficiently quenched.

  Patent Document 2 discloses a method of performing induction hardening while rotating a large-diameter ring body. High-frequency induction quenching of a large-diameter ring body is performed by placing a large-diameter ring body on the rotary table, the outer periphery of which has a circumferential surface and a heated local portion that goes around the circumferential surface on the circumferential surface. Before the quenching, the large-diameter ring body is rotated once, and the contact around the large-diameter ring body is measured to store numerical data.

  In this case, the contacts of the two contact-type distance sensors are brought into contact with the circumferential surface of the large-diameter ring body and the bottom surface of the race groove, and the large-diameter ring body is rotated in this state, and the locus is determined from the combination of the displacements of both contacts. Is decomposed and measured as a corresponding on-axis displacement to obtain position data, and an appropriate coil gap is held based on the result.

  Next, the pair of arc-shaped induction heating coils are moved closer to each other so as to sandwich the large-diameter ring body from the standby positions on both sides of the large-diameter ring body, and the pair of induction heating coils are based on the numerical data stored in the heated local portion. Close.

  Subsequently, while rotating the large-diameter ring body, the pair of induction heating coils is changed so as to keep the gap between the induction heating coil and the heated local portion constant based on the stored numerical data, and the pair of induction heating coils High frequency induction heating is performed by feeding a high frequency induction current.

JP 61-99623 A JP-A-61-106709

  However, the method of performing induction induction hardening while rotating the large-diameter ring body disclosed in Patent Document 2 is that the contacts of the two contact-type distance sensors are connected to the circle of the large-diameter ring body before performing high-frequency induction heating. The gap measurement is performed by contacting the peripheral surface and the bottom surface of the race groove, and since the thermal expansion of the large-diameter ring body is not taken into consideration, there are the following disadvantages.

  That is, for example, when quenching a large-diameter ring body having a diameter of 1200 mm, the heated local portion heated by the induction heating coil having a shape such as an arc shape is about 1000 ° C., and even at the position farthest from the heated local portion It becomes about 300 ° C. For this reason, the value of the thermal expansion of the large-diameter ring body at the time of quenching of the heated portion is increased. When the material of the large-diameter ring body is an iron-based material, the linear expansion coefficient is about 12 × 10 −6, so the large-diameter ring body having a diameter of 1200 mm rises relatively quickly in the vicinity of the heated portion and is about The temperature of the large-diameter ring body gradually increases to about 300 ° C. at 300 ° C. When the entire large-diameter ring body having a diameter of 1200 mm reaches about 300 ° C., the diameter expands by about 4 mm (about 2 mm by radius). Therefore, since the gap setting value between the large-diameter ring body and the induction heating coil is about 2 mm, there is a possibility that the large-diameter ring body and the induction heating coil come into contact with each other at the time of heating. It turns out that the coil needs to be retracted.

  In the gap measuring method disclosed in Patent Document 2, when the large-diameter ring body is thermally expanded, the contactor contacts the large-diameter ring body, an excessive load is applied to the contactor, and the contactor and the measuring instrument are damaged. There is also a possibility that. Moreover, since the tip shape of the contactor is also a small R shape, when the large-diameter ring body rotates while expanding, it is conceivable that the large-diameter ring body is damaged at the tip portion. In addition, since the contact force between the contact and the large-diameter ring body is not specified, if the pressing force against the large-diameter ring body is strong, the large-diameter ring body may be damaged, and if it is weak, it is in a state of expansion and thermal expansion. Will leave the large-diameter ring body and cause erroneous measurement.

  Therefore, during high-frequency induction heating, the contact is not damaged on the work piece, and the distance sensor that has a limited heat resistance without being affected by the high temperature of the work piece functions normally. It has been found that there is a need for a measuring device that can be made to operate.

  In view of the above problems, the present invention can accurately measure the thermal expansion displacement of a heated local portion heated by an induction heating coil during high-frequency induction heating, and the temperature rise of the workpiece Even if it exists, it aims at providing the high frequency heat processing apparatus which can keep the space | interval of an induction heating coil and a workpiece constant.

  In order to achieve the above object, a high-frequency heat treatment apparatus of the present invention includes a workpiece driving means for driving a workpiece, an induction heating coil for induction heating of the workpiece, and induction heating for supporting and moving the induction heating coil. A coil support moving means; and a thermal expansion displacement measuring means for measuring an expansion displacement of the workpiece. The thermal expansion displacement measuring means has a contact and a distance sensor, and the distance sensor is equal to or lower than a heat resistant temperature. The contact and the displacement detection shaft of the distance sensor are connected so as to achieve the heat conduction.

  According to the said structure, the displacement by the thermal expansion of a workpiece can always be detected with a distance sensor, and high frequency induction heating can be performed.

  The contact is preferably biased by biasing means and is in contact with the vicinity of the portion of the workpiece to be heated that is subjected to high frequency induction heating. By urging the contact in this way, the contact can be brought into contact with the workpiece. Moreover, if the urging means has a predetermined length, the heat dissipation action can be increased, and the heat conduction from the workpiece heated to a high temperature can be greatly reduced. Therefore, a distance sensor whose heat-resistant temperature is 100 ° C. or lower can be normally functioned.

  If the contact of the thermal expansion displacement measuring means is a heat-resistant bearing, the workpiece and the bearing are in reliable contact, but the workpiece is thermally expanded and the pressure between the workpiece and the heat-resistant bearing increases. However, there is no risk of scratching the workpiece.

  The high-frequency heat treatment apparatus of the present invention further includes a calculating means, and before the high-frequency induction heating is performed, the calculating means contacts the work piece of the distance sensor and the urging means is compressed to a certain length. When the detection signal of the distance sensor is inputted to be a reference value at this time, the gap variation corresponding to the thermal expansion of the workpiece can be measured from the time when the high frequency induction heating is started.

The induction heating coil support moving means is preferably provided by means of thermal expansion displacement measuring means so as to keep the gap between the induction heating coil and the heated portion of the workpiece substantially constant from the start to the end of the high frequency induction heating. The induction heating coil is moved with respect to the workpiece in accordance with the detected thermal expansion displacement, for example, moved in a direction away from the workpiece.
According to the above configuration, in response to the thermal expansion displacement detected by the thermal expansion displacement measuring means, the induction heating coil is moved from time to time in a direction away from the workpiece in accordance with the detected displacement, and the induction heating coil and the workpiece are processed. High-frequency induction heating can be performed while keeping the gap between the object and the heated portion substantially constant from the start to the end of high-frequency induction heating. Therefore, contact between the induction heating coil and the workpiece can be prevented.

  According to the present invention, since the thermal expansion displacement measuring means in which the heat-resistant contactor and the displacement detection shaft of the distance sensor are connected so that the heat conduction is less than or equal to the heat resistance temperature of the distance sensor is adopted, the distance sensor can be operated normally. While functioning and high-frequency induction heating, it is possible to accurately measure the thermal expansion displacement in the vicinity of the heated local area heated by the induction heating coil and to increase the temperature of the workpiece. In doing so, the object induction heating coil can be retracted to maintain a constant gap with the workpiece. Therefore, the heat treatment by high frequency induction heating for the heated portion can be performed at high speed and without unevenness.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the same or corresponding members are denoted by the same reference numerals.
FIG. 1 is a schematic plan view of the high-frequency heat treatment apparatus according to the present embodiment, and FIG. 2 shows the arrangement of the workpiece and the thermal expansion displacement measuring means in a state cut along the YY direction of FIG. It is a fragmentary sectional side view for demonstrating.
As shown in FIGS. 1 and 2, the high-frequency heat treatment apparatus 10 according to the embodiment of the present invention includes a workpiece driving means 11, an induction heating coil 15 that induction-heats the workpiece 20, and an induction heating coil 15. The induction heating coil support moving means 14 that supports and moves, the thermal expansion displacement measuring means 40 that measures the expansion displacement of the workpiece, and the control unit 30 of the high-frequency heat treatment apparatus are provided. The thermal expansion displacement measuring means 40 is arranged at a position facing the workpiece 20 and separated from the induction heating coil 15. In the illustrated case, only one thermal expansion displacement measuring means 40 is provided, but a plurality of thermal expansion displacement measuring means 40 may be provided according to the workpiece 20.

  As shown in FIG. 2, the thermal expansion displacement measuring means 40 includes a distance sensor 41 and a calculating means 60. The distance sensor 41 may be in contact with the workpiece 20 and measure the dimensional displacement accompanying the high frequency induction heating of the workpiece. As such a distance sensor 41, for example, a contact type distance sensor can be used.

  The control unit 30 is a control unit that controls all driving means of the high-frequency heat treatment apparatus 10. The controller 30 moves the rotating shaft 11A up and down, rotates the chuck of the inner diameter chuck means 13a to 13d, and releases the chuck, performs high-frequency energization and electric shielding from a high-frequency power source (not shown) to the induction heating coil 15, and a movable table device. Various controls such as movement of 14A and 14B, instruction to the coil coolant circulating apparatus, and injection and stop of quenching coolant are performed.

  FIG. 3 is a side view showing the thermal expansion displacement measuring means according to the embodiment of the present invention. As shown in FIG. 3, the thermal expansion displacement measuring means 40 includes a heat-resistant contact 43 and a distance sensor 41, and the heat-resistant contact so that the heat conduction is less than the heat-resistant temperature of the distance sensor 41. 43 and the displacement detection shaft 41a of the distance sensor 41 are connected. Specifically, the thermal expansion displacement measuring means 40 includes a distance sensor 41, a ball spline 42, a heat-resistant contact 43, and an urging means 44.

  A heat-resistant bearing can be used as the heat-resistant contact 43. According to this configuration, the workpiece 20 and the heat-resistant bearing 43 are reliably in contact with each other. Therefore, even if the workpiece 20 is thermally expanded and the pressure between the workpiece 20 and the heat-resistant bearing 43 is increased, there is no possibility of scratching the workpiece.

  As the urging means 44, various springs can be used, for example, a compression coil spring or the like. The contact 43 can be urged to contact the workpiece 20. If the length of the urging means 44 is adjusted to a predetermined length according to the thermal conductivity, the heat radiation action in this length portion increases, and the heat conduction from the workpiece heated to a high temperature is remarkably reduced. can do. Thereby, it can be set to below the heat-resistant temperature of the sensor part of distance sensor 41. For example, the contact-type distance sensor 41 having a heat-resistant temperature of 100 ° C. or less can function normally.

  The thermal expansion displacement measuring means 40 urges the contactor 43 by the urging means 44 and brings the contactor 43 into contact with the vicinity of the portion of the workpiece 20 to be heated by high frequency induction heating of the workpiece 20. Can do. Thereby, the distance sensor 41 can always detect the displacement due to the thermal expansion of the workpiece and perform high-frequency induction heating.

A detection signal from the distance sensor 41 is input to the calculation means 60. Before the high frequency induction heating is performed, when the contact 43 of the distance sensor 41 comes into contact with the workpiece 20 and the urging means 44 is compressed to a certain length, the detection signal of the distance sensor 41 is input. It is comprised so that it may become a reference value. Therefore, the gap fluctuation corresponding to the thermal expansion of the workpiece 20 can be measured from the time when the high frequency induction heating is started.
In this case, the calculation means 60 inputs the detection signal of the distance sensor 41 before starting the high frequency induction heating and sets it as the reference value. However, the case where the reference value is set to the zero point is also included.

  The induction heating coil support moving means 14 has a substantially constant interval between the induction heating coil 15 and the heated local portion 22 of the workpiece 20 (hereinafter also referred to as a gap as appropriate) from the start to the end of the high frequency induction heating. The induction heating coil 15 is configured to move in a direction away from the workpiece 20 in accordance with the thermal expansion displacement detected by the thermal expansion displacement measuring means 40.

According to the high frequency heat treatment apparatus 10 of the present embodiment, the thermal expansion displacement measuring means in which the heat resistant contactor 43 and the displacement detection shaft 41a of the distance sensor are connected so that the heat conduction is not more than the heat resistant temperature of the distance sensor 41. Since 40 is employed, the distance sensor 41 can function normally. Therefore, while performing high-frequency induction heating, it is possible to accurately measure the thermal expansion displacement in the heated local portion 22 of the workpiece 20 heated by the induction heating coil 15 and to measure the temperature of the workpiece 20. As the temperature rises, the object induction heating coil 15 can be retracted to keep the gap between the workpiece 20 constant. For this reason, the heat processing by high frequency induction heating with respect to the to-be-heated local part 22 of the to-be-processed object 20 can be performed at high speed and without unevenness.
Here, the heat treatment by high frequency induction heating includes quenching for rapid cooling after heating, and tempering and annealing by changing the cooling rate after heating.

Next, the case where the ring body as the workpiece 20 is quenched using the high-frequency heat treatment apparatus according to the embodiment of the present invention will be described.
As shown in FIG. 1 and FIG. 2, a heated local portion 22 formed on the circumferential surface 21 by rotating a ring body 20 having a circumferential surface (outer circumferential surface) 21 using the high-frequency induction heat treatment apparatus 10. High frequency induction heat treatment is performed. The ring body 20 is a steel gear as an example, and is formed of an annular body that is precision-cylindrically processed. The heated body is a concave portion having a semicircular sectional shape that goes around the upper half of the circumferential surface 21. 22.

  The high-frequency heat treatment apparatus 10 includes ring body rotating means as the workpiece driving means 11. The ring body rotating means 11 includes a rotary shaft 11A that can be moved up and down by a lifting means (not shown) and a rotation driving means (not shown), a circular rotary table 12 provided on the rotary shaft 11A, and an upper surface of the rotary table 12. And inner diameter chuck means 13a to 13h provided on the outer peripheral portion.

  When the high frequency induction heating is performed, the ring body rotating means raises the rotary shaft 11A and positions the ring body 20 at a high position to rotate the rotary shaft 11A. When the high frequency induction heating is completed, the ring body rotating means rotates the rotary shaft 11A. The rotary shaft 11A is lifted up to position the ring body 20 at a low cooling position.

  The high-frequency heat treatment apparatus 10 includes induction heating coil support moving means 14 that supports and moves the induction heating coil 15 on both sides of the ring body rotating means 11 described above. The induction heating coil support moving means 14 includes movable table devices 14A and 14B. The movable table devices 14A and 14B include a base 14b having a linear motion guide 14a, a movable stand 14c engaged with the linear motion guide 14a, a table 14d supported by the movable stand 14c, a base 14b and a movable stand 14c. And reciprocating means (not shown) for reciprocating the movable stand 14c. The movable table devices 14A and 14B can position and drive the movable stand 14c in units of 0.2 mm, for example.

  On the table 14d, as an induction heating coil, an arcuate induction heating coil 15 and an arcuate shape having a plurality of injection nozzles 16a for injecting quenching coolant onto the heated local portion 22 of the circumferential surface 21 of the ring body 20 are provided. The injection pipe 16 is provided.

  The induction heating coil 15 is connected to a high-frequency power source (not shown) and is connected to a coil coolant circulation device (not shown) that allows cooling water to flow through the induction heating coil 15.

  The injection tube 16 performs high-frequency induction heating on the heated local portion 22 on the circumferential surface 21 of the ring body 20. For example, the heated local portion 22 reaches a temperature of about 1000 ° C. over the entire circumference and rotates after a certain time has passed. When the shaft 11 </ b> A descends while rotating and comes to a low position where the ring body 20 faces, the quenching coolant is ejected vigorously from the injection nozzle 16 a toward the heated portion 22. Thereby, surface hardening of the to-be-heated local part 22 is performed.

  When the ring body 20 is chucked by the inner diameter chuck means 13a to 13d and 13e to 13h, or the chuck is released, the high frequency heat treatment apparatus 10 moves the movable stand 14c and moves the table 15d away from the ring body 20 (standby). The induction heating coil 15 and the injection pipe 16 are configured not to interfere with the ring body 20.

  When performing high frequency induction heating on the ring body 20 chucked by the inner diameter chuck means 13a to 13d and 13e to 13h, the high frequency heat treatment apparatus 10 moves the movable stands 14c on both sides closer to the ring body 20 to perform induction heating. The coil 15 is inserted into the heated local portion 22 of the circumferential surface 21 of the ring body 20 and is positioned in a proximity state that holds a gap of 2 mm, for example.

  The lower injection tubes 16 and 16 of the induction heating coil 15 are provided at positions close to the ring body 20 when the ring body 20 is lowered.

  In FIG. 2, reference numeral 30 denotes a control unit that controls all driving means of the high-frequency heat treatment apparatus 10. The controller 30 moves the rotating shaft 11A up and down, rotates the chuck of the inner diameter chuck means 13a to 13d and releases the chuck, performs high-frequency energization and electric shielding from the high-frequency power source (not shown) to the induction heating coil 15, and a movable table device. Various controls such as the movement of 14A and 14B, the command to the coil coolant circulation device, and the injection and stop of quenching coolant are performed.

  The induction heating coil 15 is supplied with power from a high frequency oscillator. As the frequency, the frequency wave number considering the resistivity of the workpiece 20 and the skin thickness, which is the penetration depth of the high frequency, and the power considering the size of the workpiece 20 are appropriately selected. The frequency of the high-frequency oscillator in the present invention is a frequency of kHz or more. When the induction heating coil 15 is positioned on the heated portion 22 of the circumferential surface 21 of the ring body 20 and high frequency induction heating is performed, the heated portion 22 is heated to a predetermined temperature. When this temperature is 1000 ° C., the upper side of the portion where high-frequency induction heating is performed is heated to about 300 ° C., and the lower side is heated to about 100 ° C. When the temperature of the ring body 20 is gradually raised to a high temperature at a position away from the heated portion 22 and the entire ring body 20 is heated to about 300 ° C., the outer diameter of the ring body 20 is also increased in the coefficient of thermal expansion of the workpiece. However, it expands by about 4 mm, for example.

  In this case, if the induction heating coil 15 is not retracted with respect to the ring body 20 that expands, the induction heating coil 15 and the ring body 20 interfere with each other, and the induction heating coil 15 is damaged. It will be.

  Before starting the high frequency induction heating, the position of the induction heating coil 15 is controlled so that the gap between the induction heating coil 15 and the heated local portion 22 is kept at an appropriate interval, for example, 2 mm of the above dimensions. Then, until the ring body 20 is thermally expanded from the start to the end of the high-frequency induction heating, the thermal expansion displacement measuring means 40 is synchronized with this so that the induction heating coil 15 is also retracted. It is attached.

An example of the thermal expansion displacement measuring means 40 will be described with reference to FIG.
The thermal expansion displacement measuring means 40 includes a distance sensor 41, a ball spline 42, a heat-resistant ball bearing as a contact 43, and a compression coil spring 44 as an urging means. As the distance sensor 41, a contact type distance sensor can be used.

  The distance sensor 41 is supported on the plate 45 by a bracket 46. In the ball spline 42, the ball spline body 42a is supported by the box bracket 47 on the plate 45, and the ball spline shaft 42b is movable. The rear end of the ball spline shaft 42 b is connected to the tip of the displacement detection shaft 41 a of the contact type distance sensor 41.

  As the ball bearing 43, for example, a ball bearing made of stainless steel such as SUS304 can be adopted. The ball bearing 43 is positioned between the fork portions of the fork bracket 48 attached to the tip side of the ball spline shaft 42b, and the shaft 49 with a head is passed through the shaft hole provided in the fork portion of the fork bracket 48 and the bearing inner ring, A nut 50 is fastened to the threaded portion of the head-equipped shaft 49, so that the ball spline shaft 42b is rotatably attached to the tip end side.

  The compression coil spring 44 is positioned between the box bracket 47 and the fork bracket 48 and is attached to the outside of the ball spline shaft 42b. The box bracket 47 is not shown, but may be water cooled. In addition to the configuration in which the box bracket 47 is water-cooled, a connecting portion made of a heat shielding material may be used as a connecting portion that blocks the heat conduction and connects the contactor 43 and the displacement detection unit. The distance sensor 41 detects the displacement detection amount so as to increase in the direction in which the displacement detection shaft 41a is pushed.

  The thermal expansion displacement measuring means 40 having the above configuration is disposed at a predetermined position of the ring body 20 by an air cylinder device 52 provided on the base 51, for example. The induction heat treatment apparatus 10 may include a cover 53 that conceals the thermal expansion displacement measuring means 40, the air cylinder device 52, and the like, and a quenching coolant recovery tank 54.

  The control unit 30 controls the air cylinder device 52 to be in a contracted state before the ring body 20 is chucked and when the chuck is released. As a result, the air cylinder device 52 is contracted and the entire thermal expansion displacement measuring means 40 is positioned at the standby position, and the ball bearing 43, which is a heat-resistant contactor, is positioned at the standby position far away from the ring body 20. .

  The control unit 30 controls the air cylinder device 52 to be in an extended state before the high frequency induction heating is started after the ring body rotating means of the high frequency heat treatment apparatus 10 chucks the ring body 20. As a result, the air cylinder device 52 extends to move the entire thermal expansion displacement measuring means 40 forward, the ball bearing 43 comes into contact with the ring body 20, the compression coil spring 44 is compressed, and the accumulated return force causes the ball The bearing 43 contacts the ring body 20 in a biased state.

  Since the distance sensor 41 is configured to detect the displacement amount so that the displacement detection amount increases in the direction in which the displacement detection shaft 41a is pushed, when the ball bearing 43 contacts the ring body 20, the displacement detection shaft 41a is pushed. The amount of displacement is detected and a detection signal is output.

  The control unit 30 outputs the first latch signal to the computing means 60 when the ball bearing 43 moves from the standby position and stops when it comes into contact with the ring body 20, and thereafter, every time a certain time (for example, several seconds) elapses. The second and subsequent latch signals are output to the arithmetic means 60.

  The computing means 60 is always input with a displacement amount detection signal from the distance sensor 41. Each time the first to several latch signals are input from the control unit 30, each displacement amount detection signal is latched and stored in the memory, and an average value thereof is calculated and stored in the memory as a reference value. Each time a latch signal is input thereafter, each displacement amount detection signal is latched and stored in the memory as a variation value. A difference value is calculated by subtracting a reference value from the fluctuation value, and a signal corresponding to the difference value is output to the control unit 30 as needed.

  The control unit 30 receives a signal corresponding to the difference value from the calculation means 60 and calculates an increase / decrease in the difference value. For example, when the difference value is increased by 0.2 mm or more, the movable stand 14c is driven by the increased dimension, and the induction heating coil 15 is shifted in a direction away from the ring body 20. Thereby, even during high frequency induction heating, even if the position of the heated local portion 22 heated by the induction heating coil 15 is accurately measured and the ring body 20 is thermally expanded, the induction heating coil 15 is made to ring. The gap can be kept constant by shifting in synchronization with the thermal expansion of the body 20.

  With reference to the flowchart of the control command in the control part 30, the quenching procedure of the ring body 20 is demonstrated. FIG. 4 is a flowchart showing an example of a control command from the control unit in the high-frequency heat treatment apparatus of FIG.

(Steps S11 and S12)
For example, the ring body 20 conveyed by a crane or a hoist is placed on the ring body rotating means, chucked and rotated.

(Step S13)
Next, the movable table devices 14A and 14B are moved closer to the ring body 20, the induction heating coil 15 is brought close to the heated local portion 22 of the ring body 20, and the gap between the induction heating coil 15 and the heated local portion 22 is set, for example, Then, the coil cooling liquid circulation device (not shown) is operated to cause the coil cooling liquid to flow inside the induction heating coil 15 and the induction heating coil is driven by the high frequency power supply device (not shown). 15 starts feeding high-frequency current to 15.

(Step S14)
Next, the super heat resistant ball bearing 43 is brought into contact with the ring body 20. Since the ball bearing 43 rotates along with the outer ring due to friction with the ring body 20, the ball bearing 43 does not damage the circumferential surface (outer peripheral surface) 21 of the ring body 20.

(Steps S15 and S16)
Next, a latch signal is output every several seconds, for example, 2 seconds, and the displacement amount detection signal from the distance sensor 41 is input via the calculation unit 60 and the detected value is stored in the memory. Repeat for five times, for example.

(Step S17)
An average value of the stored detection values is calculated, and the average value is stored in a memory as a reference value.

(Step S18)
Subsequently, for example, a latch signal is output every 2 seconds, a displacement amount detection signal from the contact-type distance sensor 41 is input via the calculation means 60, and the detection value is stored in the memory. The difference value is calculated.

(Step S19)
It is determined whether or not the difference value has changed by 0.2 mm or more from the previous difference value.

(Step S20)
When the change is greater than 0.2 mm, the induction heating coil 15 is moved backward by slightly moving the movable table devices 14A and 14B in a direction away from the ring body 20 so as to correspond to the difference value.

  Thereby, even if the ring body 20 is thermally expanded and the heated portion 22 is displaced in a direction approaching the induction heating coil 15, the induction heating coil 15 is substantially equal to the displacement dimension in synchronization with the displacement of the heated portion 22. The gap between the heated portion 22 and the induction heating coil 15 continues to be maintained at about 2 mm.

  The rotating ring body 20 continuously changes the position of the high frequency dielectric heating by the induction heating coil 15 and gradually rises in temperature while rotating several times, and at a position away from the heated local portion 22, for example, 300 Reach ℃. The ball bearing 43 transmits the heat transferred from the ring body 20 to the ball spline shaft 42 b, but the heat is dissipated and is also dissipated at the box bracket 47. Therefore, since the temperature of the heat transmitted to the distance sensor 41 is significantly lower than the heat resistance temperature of the distance sensor 41, for example, 80 ° C., the distance sensor 41 is not thermally destroyed.

(Step S21)
In this manner, the induction heating coil 15 retreats approximately equal to the displacement dimension in synchronization with the displacement of the heated portion 22 until the ring body 20 reaches a predetermined heat treatment temperature (for example, 1000 ° C.). When the ring body 20 reaches a predetermined heat treatment temperature, the energization amount to the induction heating coil 15 is controlled so that the heating by the induction heating coil 15 and the heat radiation of the ring body 20 are balanced.

(Steps S22 to S24)
When the entire circumference of the ring body 20 reaches a predetermined heat treatment temperature, for example, for 5 seconds, the movable table devices 14A and 14B are moved to the standby position, and the air cylinder device 52 is contracted to reduce the induction heating coil 15 and the ball. The bearing 43 is greatly separated from the ring body 20.

(Steps S25 to S27)
Next, the rotating shaft 11A continues to rotate and descends to place the ring body 20 at the quenching position, and the quenching coolant 22 is heated to 1000 ° C. from the spray nozzle of the spray pipe 16. Inject for 5 minutes to quench and quench.

(Steps S28 and S29)
Thereafter, the injection of the quenching coolant is stopped, the rotation shaft 11A is stopped and raised, and the ring body 20 is released from the chuck at the raised position. Thus, quenching of the ring body 20 is completed.

  According to this embodiment, the ring body 20 is placed and rotated on the rotary table while maintaining the concentric state, and then the induction heating coil 15 is moved closer from the standby position to be close to the heated local portion 22, The contact-type distance sensor 41 of the expansion displacement measuring means is moved closer from the standby position and comes into contact with the vicinity of the portion of the circumferential surface 21 of the ring body 20 where high-frequency induction heating is performed.

  Next, high-frequency induction heating is performed by feeding a high-frequency induction current to the induction heating coil 15, and the displacement due to the thermal expansion of the circumferential surface 21 of the ring body 20 is always detected by the thermal expansion displacement measuring means.

  Next, the arc-shaped induction heating coil 15 is moved in a direction away from the ring body 20 in accordance with the detected displacement, and the gap between the induction heating coil 15 and the heated processing local portion 22 of the ring body 20 is high-frequency induction. High-frequency induction heating is performed while being kept substantially constant from the start to the end of heating.

  In this case, the thermal expansion displacement measuring means 40 includes a heat-resistant contact 43 and a distance sensor 41, and the heat-resistant contact 43 and the distance sensor so that the heat conduction is not higher than the heat-resistant temperature of the distance sensor 41. Since the displacement detection shaft 41a of 41 is connected, it is guaranteed that the distance sensor 41 having a low heat-resistant temperature functions normally.

  Thereby, while performing high frequency induction heating, the measurement of the thermal expansion displacement of the to-be-heated local part 22 heated with the induction heating coil 15 of the ring body 20 can be performed correctly. For this reason, as the temperature of the ring body 20 rises, the induction heating coil 15 can be accurately retracted so as to keep the gap constant.

  In the embodiment described above, the calculation unit 60 and the control unit 30 are provided separately, but the control unit 30 may also serve as the calculation unit 60.

Hereinafter, the present invention will be described in more detail based on examples.
The workpiece 20 was subjected to quenching heat treatment of a turning inner race having a diameter of 1200 mm and a thickness of 80 mm made of steel. The inner race 20 of the turning wheel is an annular body processed with precision cylinders, and has a heated local portion 22 that is a concave portion having a semicircular cross-sectional shape that goes around the upper half of the circumferential surface 21. The high-frequency heat treatment apparatus 10 in which two sets of arc-shaped (angle 120 °) induction heating coils 15 and one thermal expansion displacement measuring means 40 are arranged was used.

  In the thermal expansion displacement measuring means 40, the distance sensor 41 uses a contact type distance sensor (manufactured by Keyence, AT3-010), and uses a ball bearing made of SUS304 (made by MISUMI, model number SUB6201ZZ) as the heat-resistant contact 43. As the ball spline 42, THK LT16A + 144L was used. The contact type distance sensor 41 is detected so that the displacement detection amount increases in the direction in which the displacement detection shaft 41a is pushed. The upper limit of measurement of the contact-type distance sensor, that is, the heat-resistant temperature is 80 ° C.

  Each of the two sets of induction heating coils 15 is applied with 300 kW of power at a frequency of 9.8 kHz, heated to 1000 ° C., immediately stopped applying high frequency power, and then cooled to quench. went. The heating time to 1000 ° C. was about 20 seconds.

  During the above heat treatment, the position of the induction heating coil 15 is controlled every 0.2 mm of the displacement of the contact distance sensor so that the gap between the induction heating coil 15 and the heated portion 22 of the workpiece is always 2 mm. Could be controlled. Moreover, the temperature of the part of the contact-type distance sensor during heating could be 80 degrees C or less.

  This makes it possible to accurately measure the thermal expansion displacement of the heated local portion 22 of the large-diameter ring body 20 heated by the arc-shaped induction heating coil 15 during high-frequency induction heating. High-frequency induction heating could be performed uniformly over a short period of about 20 seconds over the entire circumference of the local portion 22.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit and scope of the technical idea.

It is a schematic plan view of the high frequency heat processing apparatus which concerns on embodiment of this invention. It is a partial sectional side view which shows arrangement | positioning of a to-be-processed object and a thermal expansion displacement measuring means in the state cut | disconnected along the YY direction of FIG. It is a partial sectional side view of the thermal expansion displacement measuring means shown in FIG. It is a flowchart which shows an example of the control command from the control part in the high frequency heat processing apparatus of FIG.

Explanation of symbols

10: High-frequency heat treatment device 11: Workpiece drive means (ring body rotating means)
11A: Rotating shaft 12: Rotary table 13a-13d: Manually operated inner diameter chuck means 13e-13h: Air cylinder driven inner diameter chuck means 14: Induction heating coil support moving means 14A, 14B: Movable table device 14a: Linear motion Guide 14b: Base 14c: Movable stand 14d: Table 15: Arc-shaped induction heating coil 16: Injection pipe 16a: Injection nozzle 20: Large-diameter ring body 21: Circumferential surface 22: Heated local part 30: Control part 40: Heat Expansion displacement measuring means 41: Distance sensor (contact distance sensor)
41a: Displacement detection shaft 42: Ball spline 42a: Ball spline body 42b: Ball spline shaft 43: Heat resistant contact (ball bearing)
44: Energizing means (coil spring)
45: Plate 46: Bracket 47: Box bracket 48: Fork bracket 49: Shaft 50: Nut 51: Base 52: Air cylinder device 53: Cover 54: Quenching coolant recovery tank 60: Calculation means

Claims (5)

Workpiece drive means for driving the work piece, induction heating coil for induction heating of the work piece, induction heating coil support moving means for supporting and moving the induction heating coil, and measurement of expansion displacement of the work piece Thermal expansion displacement measuring means
The thermal expansion displacement measuring means includes a contact and a distance sensor, and the contact and the displacement detection shaft of the distance sensor are connected so that the distance sensor has a heat conduction temperature equal to or lower than a heat resistant temperature. A high-frequency heat treatment apparatus characterized by comprising:   2. The high frequency heat treatment apparatus according to claim 1, wherein the contact is urged by an urging means and is in contact with a vicinity of a heated local portion of a workpiece to be subjected to high frequency induction heating. .   The high frequency heat treatment apparatus according to claim 1, wherein the contact is made of a heat resistant bearing.   Further, a calculation means is provided, and the calculation means is configured to detect the distance sensor when the contact of the distance sensor comes into contact with the workpiece before the high-frequency induction heating is performed and the biasing means is compressed to a certain length. The high frequency heat treatment apparatus according to claim 1, wherein the detection signal is input as a reference value.   The induction heating coil support moving means is detected by the thermal expansion displacement measuring means so as to keep the gap between the induction heating coil and the heated portion of the workpiece to be substantially constant from the start to the end of the high frequency induction heating. The high frequency heat treatment apparatus according to claim 1, wherein the induction heating coil is configured to be movable with respect to the workpiece in accordance with the thermal expansion displacement.

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