JP4880412B2 - Induction induction tempering method and induction induction tempering program - Google Patents

Description

  The present invention relates to a high-frequency induction tempering method and a high-frequency induction tempering program for tempering a quenched metal material.

Conventionally, a tempering process has been performed on a hardened metal material to equalize the surface temperature and the internal temperature of the object to be heated, in order to alleviate the residual stress inside the object to be heated and ensure surface hardness. ing.
For example, Patent Document 1 discloses a high-frequency treatment method in which a workpiece is set in a furnace and subjected to batch tempering treatment after the workpiece is continuously quenched by induction induction heating.

According to this, it is possible to facilitate the design of the production line, stabilize the quality, and reduce the energy cost by utilizing the low thermal influence on the surrounding environment, which is an advantage of induction hardening.
JP 2004-327375 A (published November 18, 2004)

However, the conventional high frequency induction tempering method has the following problems.
That is, in the induction induction tempering method disclosed in the above publication, it is only disclosed that after quenching the workpiece by high frequency heating, tempering is performed by batch processing using a furnace. No consideration is given to the selection of tempering conditions.

  For this reason, when there are a plurality of types of parts as the object to be heated, it is necessary to perform an tempering process under a plurality of conditions while heating each part by a high-frequency induction heating coil, and to find an optimum tempering condition. In particular, if the number of types of parts to be heated increases, it takes a long time to find the optimum condition, and therefore, it is required to improve the efficiency of the process until the optimum condition is selected.

  An object of the present invention is to provide a high-frequency induction tempering method and a high-frequency induction tempering program capable of efficiently performing processing from data collection by a plurality of tempering conditions to selection of an optimum tempering condition.

  A high-frequency induction tempering method according to a first invention is a high-frequency induction tempering method for performing a tempering process on a heated object using a high-frequency induction heating coil disposed at a position facing the heated object. A fifth step is provided. In the first step, the surface of the object to be heated and the internal temperature are measured while the object to be heated set at a predetermined position is heated by the high frequency induction heating coil. In the second step, on / off control of the high-frequency induction heating coil is performed based on preset upper and lower limits of the surface temperature until the temperature of the surface and the inside of the heated object becomes uniform. In the third step, the first and second steps are repeated for a plurality of test patterns with different tempering conditions. In the fourth step, the results of the plurality of test patterns obtained in the third step are stored. In the fifth step, an optimum tempering condition is selected based on a predetermined condition from the results of a plurality of test patterns.

Here, in order to find the optimum condition of the tempering process in which the temperature difference between the surface of the object to be heated and the inside is substantially zero, the induction heating coil is automatically turned on / off based on the preset upper limit value / lower limit value. While performing OFF control, the test pattern results under a plurality of tempering conditions are acquired, and these are compared to select the optimum conditions.
Normally, when searching for the optimum conditions for such tempering, the high-frequency induction heating coil is manually turned ON / OFF while sensing the surface and internal temperature of the object to be heated. Acquire multiple data until uniform. However, in such a conventional tempering method, since ON / OFF control of the high frequency induction heating coil is manually performed, it is troublesome because it is necessary to always have a person attached when collecting data.

In the high frequency induction tempering method of the present invention, the ON / OFF control of the high frequency induction heating coil until the temperature of the surface and inside of the object to be heated becomes uniform is automated by setting the upper and lower temperature limits in advance. ing. Then, a plurality of data automatically acquired here is stored, and the optimum tempering conditions are selected by comparing them.
As a result, the data collection operation for finding the optimum tempering conditions can be automated, so that the data collection operation using a plurality of tempering conditions can be performed unattended. As a result, even when there are a plurality of types of parts to be tempered, the work up to the selection of optimum tempering conditions for each part can be made more efficient than before.

The high frequency induction tempering method according to the second invention is the high frequency induction tempering method according to the first invention, wherein the predetermined condition in the fifth step has a small difference between the surface of the object to be heated and the internal tempering parameter. Things are included.
Here, in the fifth step, an optimum test pattern is selected based on the difference in the tempering parameters. The tempering parameter (P) is calculated by the following relational expression (1) using the temperature (T), the time (t), and the constant (C).
P = T × (logt + C) (1)
Thereby, optimal tempering conditions can be selected easily. As a result, the surface hardness of the object to be heated after the tempering process corresponding to the tempering parameter can be maintained at a predetermined value or more to satisfy a predetermined product standard.

  The high frequency induction tempering method according to the third invention is the high frequency induction tempering method according to the first or second invention, wherein the predetermined condition in the fifth step is the completion of the tempering of the surface and the inside of the object to be heated. The time required for is included.

Here, in addition to the selection based on the tempering parameter, the one with a short time until the completion of the tempering process is preferentially selected as the optimum condition.
As a result, conditions that allow the most efficient tempering process can be selected, so that the tempering process can be made more efficient. In addition, by selecting the above-described conditions that the difference in the tempering parameters is small, the optimum tempering conditions can be efficiently implemented.

A high-frequency induction tempering method according to a fourth invention is the high-frequency induction tempering method according to any one of the first to third inventions, wherein in the first step, a plurality of temperature sensors are used to be heated. Measure body surface and internal temperature.
Here, sensing of the temperature of the surface to be heated and the internal temperature for selecting the optimum tempering condition is performed using two or more temperature sensors.
As a result, basically two surface temperature sensors and one internal temperature sensor are used, and depending on the shape of the object to be heated, sensing is performed using one surface temperature sensor and two or more internal temperature sensors. It can be performed. As a result, it is possible to select more optimal tempering conditions based on the sensing results of the plurality of temperature sensors.

A high-frequency induction tempering method according to a fifth invention is the high-frequency induction tempering method according to any one of the first to fourth inventions, wherein the object to be heated processed according to the conditions selected in the fifth step A sixth step of performing the inspection is further provided.
Here, the performance inspection of the heated object processed under the tempering conditions selected as the optimum conditions is performed.

  Thereby, it can be confirmed whether the goods tempered by the selected conditions satisfy, for example, predetermined product standards relating to surface hardness and residual stress. As a result, for those with poor inspection results, further conditions can be selected according to the predetermined priority, so the optimum tempering conditions can be selected more reliably by checking the actual product performance. It becomes possible.

The high frequency induction tempering method according to a sixth aspect of the invention is the high frequency induction tempering method according to the fifth aspect of the invention, and in the sixth step, an inspection relating to at least one of the hardness and residual stress of the object to be heated is performed.
Here, as a specific example of the inspection of the heated object, the surface hardness and the residual stress of the heated object are shown.
Thereby, it can be determined that the tempering condition of the object to be heated in which at least one of the surface hardness and the residual stress does not reach the predetermined performance is not an optimum condition. As a result, the tempering conditions that satisfy the predetermined product performance can be selected more reliably.

The high frequency induction tempering method according to the seventh invention is the high frequency induction tempering method according to the fifth or sixth invention, wherein the optimum tempering condition is selected again based on the inspection result in the sixth step.
Here, according to the result of inspecting the performance of the object to be heated that has been processed under the conditions once selected as the optimum tempering conditions, it is determined whether or not the conditions are to be the final optimum conditions.
As a result, confirm the performance of the actual product. If the performance of the heated object is low, select the next priority in order to select the optimum tempering conditions more reliably. be able to.

An induction induction tempering method according to an eighth invention is the induction induction tempering method according to any one of the first to seventh inventions, wherein a plurality of objects to be heated are tempered based on optimum tempering conditions. A seventh step of performing is further provided.
Here, using the conditions selected as the optimum tempering conditions through the above-mentioned steps as the final tempering conditions, a plurality of objects to be heated are continuously tempered by a batch method or the like, and mass production of products is performed. I do.

  Thereby, by performing mass production using automatically selected optimum tempering conditions, it is possible to significantly improve the processing efficiency up to mass production compared to the conventional tempering treatment.

  A high-frequency induction tempering program according to a ninth invention is a high-frequency induction tempering program for performing a tempering process on a heated object using a high-frequency induction heating coil disposed at a position facing the heated object. A computer is caused to execute an induction induction tempering method including a fifth step. In the first step, the surface of the object to be heated and the internal temperature are measured while the object to be heated set at a predetermined position is heated by the high frequency induction heating coil. In the second step, on / off control of the high frequency induction heating coil is performed until the temperature between the surface and the inside of the heated object becomes uniform based on the preset upper limit value and lower limit value. In the third step, the first and second steps are repeated for a plurality of test patterns with different tempering conditions. In the fourth step, the results of the plurality of test patterns obtained in the third step are stored. In the fifth step, an optimum tempering condition is selected based on a predetermined condition from the results of a plurality of test patterns.

Here, in order to find the optimum condition of the tempering process in which the temperature difference between the surface of the object to be heated and the inside is substantially zero, the induction heating coil is automatically turned on / off based on the preset upper limit value / lower limit value. While performing OFF control, the test pattern results under a plurality of tempering conditions are acquired, and these are compared to select the optimum conditions.
Normally, when searching for the optimum conditions for such tempering, the high-frequency induction heating coil is manually turned ON / OFF while sensing the surface and internal temperature of the object to be heated. Acquire multiple data until uniform. However, in such a conventional tempering method, since the ON / OFF control of the high-frequency induction heating coil is manually performed, it is troublesome because it is necessary to always have a person to collect data.

In the high-frequency induction tempering program of the present invention, the ON / OFF control of the high-frequency induction heating coil until the temperature of the surface and inside of the object to be heated becomes uniform is automated by setting the upper and lower temperature limits in advance. ing. Then, a plurality of data automatically acquired here is stored, and the optimum tempering conditions are selected by comparing them.
As a result, the data collection operation for finding the optimum tempering conditions can be automated, so that the data collection operation using a plurality of tempering conditions can be performed unattended. As a result, even when there are a plurality of types of parts to be tempered, the work up to the selection of optimum tempering conditions for each part can be made more efficient than before.

  According to the high-frequency induction tempering method according to the present invention, operations from data collection of a plurality of tempering conditions to selection of optimum tempering conditions can be made more efficient than before.

A high-frequency induction tempering method according to an embodiment of the present invention will be described below with reference to FIGS.
[Configuration of High Frequency Induction Tempering Device 10]
As shown in FIG. 1, a high-frequency induction tempering apparatus 10 that executes a high-frequency induction tempering method according to this embodiment includes a high-frequency induction heating coil 11 disposed on the inner peripheral surface side of a cylindrical portion of a work (object to be heated) W. A control unit 12 that performs ON / OFF control of the high-frequency induction heating coil 11, a temperature sensor S1 that detects the surface temperature of the heat treatment part Wa included in the workpiece W, and a temperature that detects the temperature inside the heat treatment part Wa. Sensor S2.
And while performing ON / OFF control of the high frequency induction heating coil 11 by the control part 12, the surface and the internal temperature of the desired heat processing part Wa detected by temperature sensor S1, S2 are equalize | homogenized.

  The workpiece W is a component mounted on a construction machine made of carbon steel S48C, and is formed so that the flange portion Wc protrudes from the cylindrical main body Wb. And the heat processing part Wa by which the hardening process was carried out is provided in the inner peripheral surface side of this cylindrical main body Wb. For this reason, in this embodiment, the case where a tempering process is performed with respect to this heat-processed part Wa processed is demonstrated.

  The high frequency induction heating coil 11 is a substantially cylindrical heating means inserted into the inner peripheral surface side of the cylindrical main body Wb in the workpiece W, and is for the heat treatment portion Wb on the inner peripheral surface side of the main body Wb of the workpiece W. Are arranged close to each other. For this reason, the surface of the heat treatment part Wa can be heated by the Joule heat generated in the vicinity of the surface of the heat treatment part Wa of the workpiece W that is the object to be heated by passing an alternating current through the high frequency induction heating coil 11.

  The control unit 12 is a device that controls whether or not a current is passed through the high-frequency induction heating coil 11, and performs ON / OFF control of the high-frequency induction heating coil 11 based on the detection results of the temperature sensors S1 and S2. Further, as shown in FIG. 2, the control unit 12 has, as input information, a set temperature (220 ° C., 190 ° C.) serving as a reference value for performing ON / OFF control of the high-frequency induction heating coil 11 and a lower limit value, Power (voltage, current) applied to the high frequency induction heating coil 11 at the time of temperature rise, temperature increase rate, power (voltage, current) applied to the high frequency induction heating coil 11 at the time of soaking, temperature increase rate, tempering conditions Information on tempering parameters (for example, 180 ° C., 2H) and the like are input. On the other hand, as output information, the product of electric power and heating time at the time of temperature rise, the product of electric power and heating time at the time of soaking, the time of heating OFF, ..., the soaking time, the value of the calculated tempering parameter, Information about cycle time, etc. is output.

  The temperature sensors S <b> 1 and S <b> 2 are respectively set on the surface and the inside of the heat treatment part Wa of the workpiece W that is the object to be heated, and transmit each detection result to the control unit 12. Thereby, in the control part 12, ON / OFF of the high frequency induction heating coil 11 is made so that the detection result (surface temperature and internal temperature) of the surface and the inside in the heat treatment part Wa received from the temperature sensors S1 and S2 respectively becomes uniform. Take control. Specifically, as shown in FIG. 3, a current is passed through the high-frequency induction heating coil 11 to heat the heat treatment part Wa, and is set as an upper limit value in the temperature sensor S1 that detects the surface temperature in the heat treatment part Wa. When the surface temperature reaches the temperature (220 ° C.), the control unit 12 turns off the power supply to the high frequency induction heating coil 11. Then, when the surface temperature drops to the temperature (190 ° C.) set as the lower limit value in the temperature sensor S1, the control unit 12 turns off the power supply to the high frequency induction heating coil 11. In the heat treatment part Wa, as shown in FIG. 3, the temperature sensor S2 that detects the internal temperature of the heat treatment part Wa gradually rises while repeatedly performing such heat treatment. Then, when the surface temperature and the internal temperature in the heat treatment part Wa become uniform (when the difference between the tempering parameters is minimized), the tempering process ends. As described above, the ON / OFF control of the high-frequency induction heating coil 11 when performing the tempering process is performed based on the preset upper limit value and lower limit value of the surface temperature, thereby collecting data in each tempering condition. Can be automated.

The tempering parameter (P) is a parameter calculated by the following relational expression (1) using the temperature (T), time (t), and constant (C), as shown in FIG. In addition, the surface hardness (Rockwell C scale hardness) (HRc), which is one index for verifying the effect of the tempering treatment, has a substantially linear correlation and a proportional relationship.
P = T × (logt + C) (1)
That is, when the tempering parameters are substantially equal, a substantially constant tempering effect can be obtained even when the temperature and time of the tempering process are changed.

<Flow of high-frequency induction tempering method>
In the present embodiment, in the high-frequency induction tempering apparatus 10 having the above-described configuration, for example, regarding the flow of processing when selecting an optimum tempering condition for each part having a different shape, the flowcharts of FIGS. 5 and 6 are used. This will be described as follows.
That is, first, in step S <b> 1, the work W is set at a predetermined position in the high-frequency induction tempering apparatus 10, and the high-frequency induction heating coil 11 is inserted on the inner peripheral surface side of the work W.

Next, in step S2, temperature sensors S1 and S2 are attached to the surface and the inside of the heat treatment part Wa of the workpiece W, respectively.
Next, in step S3, the high-frequency induction heating coil 11 is turned on to pass a current, and induction heating of the heat treatment part Wa of the workpiece W is started.
Next, in step S4, based on the upper limit value (220 ° C.) and the lower limit value (190 ° C.) of the surface temperature described above, the surface and the inside in the heat treatment part Wa are controlled by the ON / OFF control of the high frequency induction heating coil 11. Control the temperature so that the temperature is uniform.

Next, in step S5, tempering is performed at predetermined time intervals according to the relational expression (1) described above based on the detection results of the temperature sensors S1, S2 set on the surface and inside of the heat treatment part Wa and the heating time. Calculate the parameters.
Next, in step S6, it is determined whether or not the tempering parameter calculated in step S5 has reached a predetermined set value. Here, when the tempering parameter does not reach the predetermined value, the process returns to step S4 and the high-frequency induction heating coil 11 is repeatedly turned ON / OFF to control the temperature. On the other hand, if the tempering parameter has reached a predetermined set value, it is determined that the tempering process has been completed, and the process proceeds to step S7.

Next, in step S7, the power of the high frequency induction heating coil 11 is turned off, and the induction heating for the heat treatment part Wa of the workpiece W is ended.
Next, in step S8, it is determined whether or not all of the tests based on a plurality of tempering conditions prepared in advance have been completed. Here, if there is still a test under tempering conditions that has not yet been performed, the process returns to step S3, a different tempering condition is set, induction heating is started again, and tempering is performed. On the other hand, when the test under all tempering conditions is completed, the process proceeds to step S9.

Next, in step S9, data (surface, internal tempering parameters, etc.) at the time of tempering under each tempering condition is stored in a storage means such as a ROM or RAM in the control unit 12.
Next, in step S10, the tempering conditions are ranked based on a predetermined criterion from among the tempering conditions stored in step S9, and the tempering condition most suitable for the predetermined criterion is selected. In the present embodiment, as a criterion for selecting the optimum tempering condition, the one having a small difference in the integrated value of the tempering parameter between the surface and the inside of the heat treatment portion Wa is used. The difference in the tempering parameter between the surface and the inside is expressed as the difference in the area of the graph formed between the broken line indicating the transition between the surface temperature and the internal temperature shown in FIG. 3 and the X axis. For this reason, a temperature difference between the surface and the inside of the heat treatment part Wa from the time of temperature rise to the time of soaking is small, and a short tempering time is selected as the optimum tempering condition.

  As described above, in the high-frequency induction tempering method of the present embodiment, first, the ON / OFF control of the high-frequency induction heating coil 11 when performing the tempering process is performed with the upper limit value and the lower limit value of the surface temperature of the heat treatment portion Wa. It can be done automatically by setting. Then, in the control unit 12, for example, an optimum tempering condition is selected based on a predetermined standard from a plurality of data acquired by repeatedly performing tests with a plurality of tempering conditions on one part (work W). By doing so, it is possible to automatically and efficiently carry out processing from data acquisition of a plurality of tempering conditions to selection of the optimum tempering conditions. As a result, even if it is necessary to select the optimum tempering conditions for parts with different shapes, etc., the optimum tempering conditions can be efficiently selected for each part. Can be speeded up.

Moreover, in this embodiment, after selecting the optimal tempering conditions mentioned above, the process of the workpiece | work W inspection, mass production, etc. is performed according to the flowchart shown in FIG.
That is, in the high-frequency induction tempering method of the present embodiment, from step S11 to step S16, the workpiece W that has been tempered under the selected tempering conditions is sampled, and the surface hardness and the like of the workpiece W are inspected. It includes the step of checking whether the tempering conditions are really optimal.

Specifically, in step S11, the control unit 12 captures the selected tempering condition as a setting condition (set value) for performing the tempering process.
Next, in step S <b> 12, the workpiece W is set at a predetermined position in the high frequency induction tempering apparatus 10.
Next, in step S13, the high-frequency induction heating coil 11 is used to quench the heat treatment part Wa of the workpiece W under predetermined conditions.

Next, in step S14, the condition selected as the optimum tempering condition is set, and the tempering process is performed.
Next, in step S15, a quality inspection regarding the surface hardness and residual stress in the heat treatment portion Wa of the workpiece W that has been tempered is performed.
Next, in step S16, it is determined whether or not the quality satisfies a predetermined standard as a result of the quality inspection. Here, if the predetermined standard is not satisfied, it is determined that the selected tempering condition is not optimal, and the tempering process is performed again according to the tempering condition ranked second. On the other hand, if the predetermined standard is satisfied, the process proceeds to step S17.

Next, in step S17, since it has been found that the selected tempering condition has a predetermined tempering effect, this is set as the final optimum tempering condition, and the condition setting is completed.
Next, in step S18, finally selected tempering conditions are set, and mass production is performed so that an optimum tempering effect can be obtained for each part.

  As described above, the optimum tempering condition is determined by inspecting whether the tempering condition selected as the optimum tempering condition in the process up to step S10 shown in FIG. 5 satisfies the predetermined quality performance. It can be confirmed whether or not. Then, by confirming the quality and performing mass production, it becomes possible to efficiently manufacture the workpiece W having a predetermined performance with certainty.

[Features of high-frequency induction tempering method]
(1)
The high-frequency induction tempering method of the present embodiment is a method of tempering the workpiece W using the high-frequency induction heating coil 11, and as shown in FIG. While heating, the temperature between the surface and the inside of the heat treatment portion Wa is measured, and the high-frequency induction heating coil 11 of the high-frequency induction heating coil 11 is made uniform according to the preset upper and lower limits of the surface temperature until the surface and the inner temperature become uniform. Perform ON / OFF control. And after performing such a tempering process by several tempering conditions, while storing these conditions, the optimal tempering conditions are selected based on a predetermined condition.

  Thereby, the ON / OFF control of the high-frequency induction heating coil 11 can be automatically performed by the above-described high-frequency induction tempering method, and the optimum tempering condition for the workpiece W can be efficiently selected. As a result, for example, even when it is necessary to find the optimum tempering conditions for multiple parts with different materials and shapes, the process up to the selection of the optimum tempering conditions for each part is significantly more efficient than before. It becomes possible to do well.

(2)
In the high frequency induction tempering method of the present embodiment, as shown in FIG. 5, when selecting an optimum condition from among a plurality of tempering conditions acquired by automatically performing ON / OFF control of the high frequency induction heating coil 11. As the predetermined conditions, those having a small difference in integrated values of the tempering parameters (see the relational expression (1) above) between the surface and the inside of the heat treatment portion Wa are used.

This makes it possible to select tempering conditions that can obtain the tempering effect most efficiently from the numerical values (temperature, time, etc.) for calculating the tempering parameters. For example, efficient conditions can be selected while maintaining product performance such as surface hardness that correlates with tempering parameters.
(3)
In the high frequency induction tempering method of this embodiment, as shown in FIG. 1, the surface and internal temperature in the heat treatment part Wa of the workpiece W are measured using a plurality of temperature sensors S1, S2.

Thereby, according to the shape of the workpiece | work W used as the object which performs a tempering process, the surface and internal temperature can be detected appropriately and the data for a tempering process can be acquired.
(4)
In the high-frequency induction tempering method of the present embodiment, as shown in FIG. 6, after selecting an optimum tempering condition based on a criterion such as a tempering parameter, a quality inspection is performed on the workpiece W processed according to the condition.

Thereby, the optimal tempering conditions can be selected more reliably by verifying from the quality aspect whether or not the selected tempering conditions are optimal.
(5)
In the high frequency induction tempering method of the present embodiment, as shown in FIG. 6, a quality inspection relating to surface hardness and residual stress is performed on the workpiece W processed under the conditions selected as the optimum tempering conditions.

As a result, whether or not the selected tempering condition is optimum can be verified more reliably from the viewpoint of quality such as surface hardness and residual stress, and the optimum tempering condition can be selected more reliably.
(6)
In the high-frequency induction tempering method of this embodiment, as shown in FIG. 6, when the above-described quality inspection results do not satisfy the predetermined quality performance, the optimum tempering conditions are selected again.

  As a result, tempering conditions that do not satisfy a predetermined standard in terms of quality cannot be said to be optimal conditions, and therefore a condition with higher ranking can be selected again as the optimal tempering conditions. As a result, as a result of verification in terms of quality, tempering conditions that do not have a predetermined performance can be efficiently tempered by eliminating them from the ranked conditions, and quality aspects such as surface hardness In addition, an excellent workpiece W can be manufactured.

(7)
In the high-frequency induction tempering method of this embodiment, as shown in FIG. 6, the conditions selected as the optimum tempering conditions are set, and a plurality of workpieces W are set to mass-produce products.
Thereby, mass production of a product can be performed efficiently by performing the tempering process under the optimum tempering conditions selected efficiently. In particular, as shown in FIG. 6, mass production of products based on tempering conditions that have been inspected in terms of quality by conducting surface hardness inspections, etc., will ensure more reliable and superior products in terms of performance. It can be carried out efficiently.

[Other Embodiments]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.
(A)
In the above embodiment, the present invention has been described as a high-frequency induction tempering method. However, the present invention is not limited to this.

For example, the present invention can be implemented as a high-frequency induction tempering program that causes a computer to execute the above-described high-frequency induction tempering method.
Even in this case, it is possible to obtain the same effect as described above that processing can be efficiently performed by automation of processing from data acquisition of various tempering conditions to selection of optimum conditions.
(B)
In the said embodiment, as shown in FIG. 4, the example which used carbon steel (S48C) as a material of the workpiece | work W which is a to-be-heated body was demonstrated and demonstrated. However, the present invention is not limited to this.

For example, as shown in FIGS. 7 (a) and 7 (b), an object to be heated formed of an alloy such as chromium molybdenum steel (SCM415) or manganese steel (SMn443) or cast iron may be used as the workpiece.
Even in this case, as shown in FIGS. 7A and 7B, the correlation between the tempering parameter and the surface hardness (HRc) approximates that of the carbon steel (S48C) shown in FIG. Even when other materials are used as the work to be heated, the same effects as described above can be obtained.

(C)
In the above embodiment, as in step S10 shown in FIG. 5, the difference between the integrated values of the tempering parameters (temperature, time) between the surface and the inside of the workpiece W is small as a reference when selecting the optimum tempering conditions. Was described as an example. However, the present invention is not limited to this.

  For example, as a selection condition, as in step S10 and step S10a shown in FIG. 8, in addition to the tempering parameter, a shorter time required for completing the tempering process may be added as the selection condition. In this case, the tempering process can be carried out more efficiently by selecting the condition for ending the tempering process earlier for those having the same tempering parameter difference.

(D)
In the said embodiment, after selecting the optimal tempering conditions, the workpiece | work W by which the tempering process was carried out by the conditions is inspected, and the example which checks whether it has the predetermined | prescribed performance requested | required is given and demonstrated. did. However, the present invention is not limited to this.
For example, after selecting optimum tempering conditions, mass production may be performed as is using the conditions.

However, by checking whether the selected tempering conditions are optimal by checking the performance of the product, the optimum tempering conditions can be selected more reliably. As in the embodiment, it is more preferable to inspect the object to be heated after selecting the optimum tempering conditions.
(E)
In the said embodiment, the example which inspects the workpiece | work W about surface hardness and a residual stress was given and demonstrated after selection of the optimal tempering conditions. However, the present invention is not limited to this.

For example, a check regarding dimensional accuracy may be added as the inspection content. Or, conversely, only one of the surface hardness and the residual stress may be checked.
(F)
In the said embodiment, after selecting the optimal tempering conditions, the several workpiece | work W was set and the example which mass-produces a tempering process was given and demonstrated. However, the present invention is not limited to this.

For example, the optimum tempering condition may be stored as data of the optimum tempering condition for each object to be heated, instead of mass production immediately after selecting the optimum tempering condition.
(G)
In the said embodiment, the components (work W) mounted in a construction machine were mentioned as an example and demonstrated as a to-be-heated body. However, the present invention is not limited to this.

For example, the present invention can be applied to selection of tempering conditions for metal materials used in other fields as well as parts of construction machines.
(H)
In the above embodiment, an example in which the upper limit value and the lower limit value of the surface temperature in the heat treatment part Wa of the workpiece W are set to 220 ° C. and 190 ° C., respectively, in order to automate the data collection for selecting the optimum tempering conditions. And explained. However, the present invention is not limited to this.

For example, the set value can be moved up and down according to the material of the heated object, such as an upper limit value of 260 ° C. and a lower limit value of 210 ° C.
If the upper and lower limit values are changed, the effect of the tempering process may be affected. However, if the tempering parameters are constant, the effect on the performance, such as surface hardness, will be negligible. I know it ’s not. For this reason, even when the set temperature is changed, if it is desired to maintain a substantially constant performance, it is more preferable that when the set temperature is changed, the tempering parameter is made substantially constant by changing the time accordingly.

(I)
In the above embodiment, an example in which the tempering process is performed while measuring the temperature between the surface and the inside of the workpiece (object to be heated) W using the two temperature sensors S1 and S2 has been described. However, the present invention is not limited to this.
For example, when the shape of the object to be heated is complicated, the temperature of each part of the object to be heated may be measured using three or more temperature sensors to perform the tempering process.

  The high-frequency induction tempering method of the present invention automates the processing from data collection by a plurality of tempering conditions to the selection of the optimum tempering conditions, and has the effect that it can be carried out efficiently. On the other hand, it is widely applicable.

Sectional drawing which shows schematic structure of the high frequency induction tempering apparatus which performs the high frequency induction tempering method which concerns on one Embodiment of this invention. Explanatory drawing which shows the content of the input / output in the high frequency induction tempering apparatus of FIG. The graph which shows the surface change of the workpiece | work at the time of performing the tempering process in the high frequency induction tempering method of FIG. The graph which shows the relationship between the surface hardness at the time of using S48C as a material of a workpiece | work by the high frequency induction tempering apparatus of FIG. 1, and a tempering parameter. The flowchart which shows the flow of the high frequency induction tempering method by the high frequency induction tempering apparatus of FIG. 6 is a flowchart showing a process subsequent to the flowchart of FIG. 5. The graph which shows the relationship between surface hardness and a tempering parameter about the material of the workpiece | work used in the high frequency induction tempering method which concerns on other embodiment of this invention. The flowchart which shows the flow of the high frequency induction tempering method which concerns on other embodiment of this invention.

Explanation of symbols

10 High Frequency Induction Tempering Device 11 High Frequency Induction Heating Coil 12 Control Units S1, S2 Temperature Sensor W Workpiece
Wa heat treatment section

Claims (9)

A high-frequency induction tempering method for tempering the heated object using a high-frequency induction heating coil disposed at a position facing the heated object,
A first step of measuring the surface and internal temperature of the heated object while heating the heated object set at a predetermined position by the high-frequency induction heating coil;
A second step of performing ON / OFF control of the high-frequency induction heating coil until the temperature between the surface and the inside of the object to be heated is uniform based on the upper limit value and the lower limit value of the surface temperature set in advance; ,
A third step of repeating the first and second steps for a plurality of test patterns with different tempering conditions;
A fourth step of storing results of the plurality of test patterns obtained in the third step;
A fifth step of selecting an optimum tempering condition based on a predetermined condition from the results of the plurality of test patterns;
High frequency induction tempering method. The predetermined condition in the fifth step includes one having a small difference in the tempering parameter between the surface of the object to be heated and the inside thereof,
The high frequency induction tempering method according to claim 1. The predetermined condition in the fifth step includes one that takes a short time to complete the tempering of the surface and the inside of the object to be heated.
The high frequency induction tempering method according to claim 1 or 2. In the first step, using a plurality of temperature sensors, the temperature of the surface and the inside of the object to be heated is measured.
The high frequency induction tempering method according to any one of claims 1 to 3. A sixth step of inspecting the heated object processed according to the condition selected in the fifth step;
The high frequency induction tempering method according to any one of claims 1 to 4. In the sixth step, an inspection relating to at least one of hardness and residual stress of the object to be heated is performed.
The high frequency induction tempering method according to claim 5. Based on the inspection result in the sixth step, the optimum tempering conditions are selected again.
The high frequency induction tempering method according to claim 5 or 6. A seventh step of performing a tempering treatment of the plurality of the objects to be heated based on the optimum tempering condition;
The high frequency induction tempering method according to any one of claims 1 to 7. A high-frequency induction tempering program for performing a tempering process on the heated object using a high-frequency induction heating coil disposed at a position facing the heated object,
A first step of measuring the surface and internal temperature of the heated object while heating the heated object set at a predetermined position by the high-frequency induction heating coil;
A second step of performing ON / OFF control of the high-frequency induction heating coil until the temperature of the surface and the inside of the object to be heated is uniform based on an upper limit value and a lower limit value set in advance;
A third step of repeating the first and second steps for a plurality of test patterns with different tempering conditions;
A fourth step of storing results of the plurality of test patterns obtained in the third step;
A fifth step of selecting an optimum tempering condition based on a predetermined condition from the results of the plurality of test patterns;
An induction tempering program that causes a computer to execute an induction induction tempering method.

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