JP2007239043A - Induction heat-treatment method and induction heat-treated article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an induction heat-treatment method by which the temperature control can be easily obtained and the condition setting of the heat-treatment is easily performed and also, the quality in the treating material can be stabilized and to provide an induction heat-treated article with which a manufacturing cost is restrained and the quality is stabilized. <P>SOLUTION: The induction-hardening method is provided with a surface stabilizing process 11 for forming the stabilized layer of higher oxidizing resistance than the treating material 1 on the surface of the treating material 1 in the temperature zone heated to the treating material 1 and a hardening process 10, with which the treating material 1 forming the stabilized layer in the surface stabilizing process 11 is hardened. Then, the hardening process 10 contains a temperature control process 20, with which the temperature of the treating material 1 forming the stabilized layer is adjusted, and a hardening control process 30 for cooling the treating material 1 by deciding the controlling cooling timing to the treating material 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high-frequency heat treatment method and a high-frequency heat-treated product, and more specifically to a high-frequency heat treatment method and a high-frequency heat-treated product in which an object to be treated is heated by high-frequency heating.

The high-frequency heat treatment method is a heat treatment method in which a high-frequency current is passed through an induction coil to inductively heat a workpiece set adjacent to the induction coil, and heat treatment such as quenching or tempering of the workpiece is performed. . Compared to carburizing and quenching, bright heat treatment, etc., which are generally adopted as heat treatment methods for steel, this induction heat treatment method has a cleaner working environment and can efficiently process a small lot of products in a short time. Is advantageous. Therefore, with respect to the induction heat treatment method and induction heat treatment equipment, many studies have been made for the purpose of controlling the hardness of the workpiece and improving the efficiency of the heat treatment, and various proposals have been made (see, for example, Patent Documents 1 and 2). .
JP 2004-315851 A JP 2004-225081 A

  In the high-frequency heat treatment, the object to be treated is directly heated by induction heating, unlike a heat treatment method in which the object to be treated is heated through an atmosphere in a furnace such as a general atmosphere furnace. Therefore, in order to measure the temperature of the object to be processed, it is necessary to directly measure the temperature of the object to be processed. However, in order to uniformly heat the object to be processed, the high frequency heat treatment equipment is often provided with a drive mechanism for moving the object to be processed, and it may be difficult to install a contact-type thermometer. Many.

  On the other hand, a measure for measuring the temperature of the object to be processed using a radiation thermometer can be considered. However, metals such as steel have a metallic luster and high light reflectance. Therefore, in the object to be processed made of metal, the temperature measurement accuracy of the radiation thermometer often decreases due to the influence of disturbance due to reflection of light from an external light source. Moreover, since metals such as steel have a low emissivity, the amount of light acquired by the radiation thermometer is small, and the influence of the disturbance is further increased.

  For the reasons described above, it is not easy to measure the temperature of the object to be processed in the high-frequency heat treatment, and it is difficult to control the heat treatment (temperature control) according to the heat treatment conditions of temperature and time. Therefore, in general, in the high-frequency heat treatment, heat treatment control (power control) based on heat treatment conditions of electric power and time is often employed. In this high-frequency heat treatment by power control, the heating history given to the workpiece is not clear, so the sample of the workpiece is actually changed while changing the power output from the power source to the induction coil and the time of the output. The heat treatment quality such as hardness and microstructure of the sample was confirmed, and the heat treatment conditions were set experimentally. Therefore, in order to impart desired heat treatment quality to the object to be treated, each time the shape or material of the object to be treated is changed, the heat treatment conditions are set by repeating trial and error of heat treatment while confirming the heat treatment quality. There is a need. As a result, not only is it time-consuming to determine the conditions for the heat treatment, but the quality of the object to be treated is not sufficiently stable, which is a problem of the high-frequency heat treatment. Further, due to this, the manufacturing cost of the high frequency heat treated product heat treated by the high frequency heat treatment is increasing.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a high-frequency heat treatment method that enables temperature control, makes it easy to determine heat treatment conditions, and stabilizes the quality of an object to be treated. Another object of the present invention is to provide a high-frequency heat-treated product with reduced production cost and stable quality.

  The high-frequency heat treatment method according to one aspect of the present invention is a high-frequency heat treatment method in which an object to be processed is heated and hardened by high-frequency heating. The high-frequency heat treatment method includes a surface stabilization step in which a stabilization layer having higher oxidation resistance than the object to be processed is formed on the surface of the object to be processed in a temperature range where the object to be processed is heated. And a quench hardening step in which the workpiece on which the stabilization layer is formed is quench hardened.

  In the quench hardening process, the temperature control process in which the temperature of the object to be processed on which the stabilization layer is formed is adjusted, and the timing at which the heated object to be cooled is determined. A quench control process to be cooled. The temperature control process includes a temperature control temperature measurement process in which the temperature of the surface of the stabilization layer formed on the surface of the workpiece is measured by a radiation thermometer, and temperature information measured in the temperature control temperature measurement process. A temperature adjusting step for outputting a temperature control signal for controlling the heating state of the workpiece based on the temperature control, and a heating step for heating the workpiece by high-frequency heating based on the temperature control signal. .

  The quenching control process includes a temperature measurement process for quenching in which the temperature of the surface of the stabilization layer formed on the surface of the workpiece is measured by a radiation thermometer, and a temperature measured in the temperature measurement process for quenching. The heating time is adjusted based on the information, the timing at which the workpiece is to be cooled is determined and the cooling start signal is output, and the workpiece is cooled based on the cooling start signal And a cooling step in which the workpiece is quenched and hardened.

  In general, in induction hardening, the transition of power output (power output pattern) consisting of parameters of power and time as heat treatment conditions is first determined based on past heat treatment results and operator experience (power control). ). The heat treatment conditions are determined by actually heat-treating the sample of the object to be processed while changing the power and time in consideration of the shape and material of the object to be processed. Therefore, experience and labor are required to determine the heat treatment conditions. Further, in quenching of steel products, it is necessary to rapidly cool an object to be processed after it is kept at a predetermined temperature for a predetermined time. However, it is difficult to accurately grasp the heating history of the workpiece by the above method (power control). Therefore, in order to determine the heat treatment conditions, it is necessary to investigate the quality, such as the hardness and microstructure of the workpiece obtained by actually performing the heat treatment.

  On the other hand, in the induction heat treatment method according to one aspect of the present invention, in the quench hardening process, heating of the workpiece is controlled using temperature and time as parameters (temperature control). Therefore, it is possible to accurately grasp the heating history of the object to be processed, and quenching can be performed by quenching after giving the necessary heating history to the object to be processed. As a result, it is not always necessary to investigate the quality of the workpiece, such as the hardness and microstructure, obtained by actually performing the heat treatment, and experience and labor are not necessarily required to determine the heat treatment conditions. Thus, according to the high frequency heat treatment method in one aspect of the present invention, the above-described problems of high frequency heat treatment are solved.

  In the high-frequency heat treatment method according to one aspect of the present invention that employs temperature control, the temperature measurement accuracy of the object to be processed is extremely important. As described above, in the high-frequency heat treatment, it is difficult to employ a contact thermometer such as a thermocouple for measuring the temperature of the object to be processed due to a layout problem of the heat treatment apparatus. Therefore, in one aspect of the present invention, Also in the high-frequency heat treatment method, a radiation thermometer is employed for measuring the temperature of the workpiece. On the other hand, in the high frequency heat treatment, the atmosphere is not normally controlled, and the object to be processed is heated in the air (in the air). Therefore, when an object to be processed made of steel is heat-treated, the object to be treated is oxidized by oxygen in the atmosphere as the heat treatment proceeds. As a result, the surface state of the object to be processed changes during the heat treatment, and the emissivity changes accordingly. Therefore, the temperature measurement accuracy of the object to be processed by the radiation thermometer decreases.

  When the oxidation resistance of the object to be processed is low, the surface of the object to be processed is oxidized in the initial stage of the heat treatment, and the surface state is hardly changed after that. Therefore, the influence of the change of the surface state on the temperature measurement accuracy is relatively small. . However, when the object to be treated is made of steel containing 3% or more of chromium, for example, martensitic stainless steel such as JIS standard SUS440C, high speed steel such as AISI standard M50, etc., the surface is relatively oxidized. Since it takes a long time, the influence of the change of the surface state on the temperature measurement accuracy becomes large.

  On the other hand, in the high-frequency heat treatment method according to one aspect of the present invention, in the surface stabilization step, the surface of the object to be processed is stabilized with higher oxidation resistance than the object to be processed in the temperature range where the object to be processed is heated. A layer is formed. Therefore, in the quench hardening process, changes in the surface state due to oxidation of the surface of the workpiece are suppressed, and a decrease in temperature measurement accuracy by the radiation thermometer is avoided. As a result, according to the high-frequency heat treatment method in one aspect of the present invention, the quality of the workpiece can be stabilized.

  As described above, according to the high-frequency heat treatment method in one aspect of the present invention, temperature control can be performed, heat treatment conditions can be easily set, and the quality of an object to be processed can be stabilized. A possible high-frequency heat treatment method can be provided.

  In the above temperature control temperature measurement process, in order to avoid an excessive amount of retained austenite due to excessive heating of the object to be processed, a part of the object to be processed, such as an induction coil, is heated. It is preferable to measure the temperature of the part which is close and has the most magnetic flux penetration. Further, in the temperature measuring process for quenching described above, in order to avoid insufficient heating before quenching of the workpiece, a portion of the workpiece to be cooled is located far from a portion where the temperature is low, for example, an induction coil, It is preferred that the temperature of the site with the least penetration is measured.

  The high-frequency heat treatment method according to another aspect of the present invention is a high-frequency heat treatment method in which an object to be treated is heated and hardened by induction heating. The high-frequency heat treatment method includes a data acquisition process, a storage process, a confirmation process, and a mass production process. In the data acquisition step, the process data is acquired by heating and hardening the sample of the workpiece. In the storing step, in order to identify the transition data of the power output output from the power source for high frequency heating to the induction coil in order to heat the sample of the workpiece in the data acquisition step, and the cooling timing of the sample of the workpiece Cooling timing data is stored as process data.

  In the confirmation process, the validity of the transition data of the power output and the cooling timing data is confirmed based on the material data of the workpiece that has been quenched and hardened in the data acquisition process. In the mass production process, the workpiece is quenched and hardened according to the transition data of the power output and the cooling timing data which are stored in the storage process and validated in the confirmation process. And quench hardening in a data acquisition process is implemented by the high frequency heat treatment method in the above-mentioned one aspect of the present invention.

  In the high-frequency heat treatment method according to one aspect of the present invention, a radiation thermometer is employed for measuring the temperature of the workpiece. And the influence of the disturbance which acts on temperature measurement precision is suppressed by performing a surface stabilization process. However, for example, when dirt or water droplets adhere to the lens of the radiation thermometer, the measured temperature may include an error, and it is preferable to take further measures against disturbance.

  On the other hand, in the induction heat treatment method according to the other aspect described above, after performing induction hardening on the sample of the workpiece by the induction heat treatment method according to the aspect of the present invention as the data acquisition step, temperature measurement data, etc. A storage process for storing the process data is provided, and after a confirmation process for confirming the validity of the stored process data, the heat treatment of the mass production process is performed based on the process data whose validity is ensured. Thereby, according to the high-frequency heat treatment method in another aspect of the present invention, temperature control can be performed, heat treatment conditions can be easily set, and the quality of the workpiece can be further stabilized. A high-frequency heat treatment method can be provided.

  In the above confirmation process, the material data investigated to confirm the validity of the power output transition data and the cooling timing data are, for example, the hardness of the workpiece, the microstructure of the steel constituting the workpiece, the residual One or more material data selected from the amount of austenite can be used. In addition, the material data includes temperature data measured in the temperature measurement temperature measurement process and quenching temperature measurement process in the data acquisition process in the storage process, and the cooling timing data stored as the data and process data. However, the sample of the object to be processed after the heat treatment may be actually investigated and acquired.

  The hardness of the workpiece can be obtained by cutting the workpiece after the heat treatment, polishing the cut surface, and then measuring the hardness of the cut surface with a hardness meter such as a Vickers hardness meter or a Rockwell hardness meter. . In addition, the microstructure of the steel constituting the workpiece is cut after the workpiece after heat treatment, the cut surface is polished, and then the cut surface is corroded by a corrosive liquid such as nital (nitric alcohol solution). It can be investigated by observing with a microscope such as a microscope. The amount of retained austenite is determined by, for example, electropolishing a desired portion of the object to be treated after heat treatment, and using an X-ray diffractometer (XRD) to determine whether the martensite α (211) plane and the austenite γ (220) plane It can be calculated by measuring the diffraction intensity.

  The high-frequency heat treatment method according to another aspect of the present invention is a high-frequency heat treatment method in which an object to be processed is heated and tempered by high-frequency heating. The high-frequency heat treatment method includes a surface stabilization process in which a stabilization layer having higher oxidation resistance than the object to be processed is formed on the surface of the object to be processed, and a process in which the stabilization layer is formed in the surface stabilization process. A tempering step in which the object is heated and tempered. The tempering step includes a temperature control step in which the temperature of the workpiece is adjusted, and a tempering control step in which the timing at which the heating of the workpiece is to be finished is determined and the workpiece is cooled. Yes.

  The temperature control process includes a temperature control temperature measurement process in which the temperature of the surface of the stabilization layer formed on the surface of the workpiece is measured by a radiation thermometer, and information on the temperature measured in the temperature control temperature measurement process. A temperature adjusting step for outputting a temperature control signal for controlling the heating state of the workpiece, and a heating step for heating the workpiece by high-frequency heating based on the temperature control signal. Yes. The tempering control process includes a temperature measurement process for tempering in which the temperature of the surface of the stabilization layer formed on the surface of the workpiece is measured by a radiation thermometer, and a temperature measured in the temperature measurement process for tempering. The heating time is adjusted based on the information, the timing at which the workpiece is to be cooled is determined and the cooling start signal is output, and the workpiece is cooled based on the cooling start signal And a cooling step in which tempering of the object to be processed is completed.

  In the induction heat treatment method according to another aspect of the present invention, heat treatment by temperature control is employed in the tempering step. Therefore, similar to the high-frequency heat treatment method in the above one aspect, it is possible to accurately grasp the heating history of the workpiece, and after providing the necessary heating history to the workpiece, tempering by cooling Can be performed. As a result, it is not always necessary to investigate the material, for example, hardness, of the workpiece obtained by actually performing the heat treatment, and experience and labor are not necessarily required to determine the heat treatment conditions.

  In the high-frequency heat treatment method according to another aspect of the present invention, in the surface stabilization step, a stabilization layer having higher oxidation resistance than the object to be processed in the temperature range where the object to be processed is heated on the surface of the object to be processed. Is formed. Therefore, in the tempering process, a change in the surface state due to oxidation of the surface of the workpiece is suppressed, and a decrease in temperature measurement accuracy by the radiation thermometer is avoided. As a result, according to the high frequency heat treatment method in another aspect of the present invention, the quality of the object to be processed can be stabilized.

  As described above, according to the high-frequency heat treatment method according to another aspect of the present invention, temperature control can be performed, heat treatment conditions can be easily set, and the quality of the workpiece can be stabilized. A possible high-frequency heat treatment method can be provided. In the tempering temperature measurement process described above, it is preferable to measure the temperature at a plurality of sites in order to stabilize the quality of the workpiece.

  A high-frequency heat treatment method according to still another aspect of the present invention is a high-frequency heat treatment method in which an object to be processed is heated and tempered by high-frequency heating. The high-frequency heat treatment method includes a data acquisition process, a storage process, a confirmation process, and a mass production process. In the data acquisition step, process data is acquired by heating and tempering the sample of the workpiece. In the storing step, in order to identify the transition data of the power output output from the power source for high frequency heating to the induction coil in order to heat the sample of the workpiece in the data acquisition step, and the cooling timing of the sample of the workpiece Cooling timing data is stored as process data.

  In the confirmation step, the validity of the transition data of the power output and the cooling timing data is confirmed based on the material data of the workpiece tempered in the data acquisition step. In the mass production process, the workpiece is tempered according to the power output transition data and the cooling timing data which are stored in the storage process and validated in the confirmation process. And the tempering in a data acquisition process is implemented by the high frequency heat processing method in another situation of the said invention.

  In the induction heat treatment method according to still another aspect of the present invention, after performing induction tempering on the sample of the object to be processed by the induction heat treatment method according to another aspect of the present invention as a data acquisition step, temperature measurement data or the like is obtained. A storage process for storing the process data is provided, and after a confirmation process for confirming the validity of the stored process data, the heat treatment of the mass production process is performed based on the process data whose validity is ensured. Thereby, according to the high frequency heat treatment method in still another aspect of the present invention, it is possible to control the temperature, to easily determine the conditions of the heat treatment, and to further stabilize the quality of the workpiece. A possible high-frequency heat treatment method can be provided.

  In the confirmation process, the material data investigated to confirm the validity of the power output transition data and the cooling timing data is, for example, the hardness of the workpiece, which is the most important characteristic in tempering the workpiece. It can be. The material data includes temperature data measured in the temperature control temperature measurement step and the tempering temperature measurement step in the data acquisition step in the storage step, and the cooling timing data stored as the data and process data. However, the sample of the object to be processed after the heat treatment may be actually investigated and acquired.

  Preferably, in the high-frequency heat treatment method, the surface stabilization step includes a black body paint application step in which a black body paint is applied to the surface of the object to be processed. In the temperature range where the workpiece is heated, the surface of the workpiece during the heat treatment is applied by applying a black body paint with a very small change in emissivity on the surface of the workpiece and then performing high-frequency heat treatment. The change in emissivity is suppressed. As a result, the accuracy of temperature measurement by the radiation thermometer is further improved, and the quality of the object to be processed is further stabilized.

  Here, as the black body paint, for example, a silicon-based matte paint can be used. More specifically, for example, Pyromark High Temperature Paint manufactured by TEMPIL, high temperature black body paint manufactured by Japan Sensor Co., Ltd. JSC3 etc. can be adopted.

  Preferably, in the high-frequency heat treatment method, the surface stabilization step includes a thermal oxidation step in which an iron oxide layer is formed on the surface of the object to be processed by thermally oxidizing the object to be processed. In the temperature range where the workpiece is heated, high-frequency heat treatment is performed after an iron oxide layer having higher oxidation resistance than that of the workpiece and a small change in emissivity is formed on the surface of the workpiece. Thereby, the change of the emissivity in the surface of the to-be-processed object during heat processing is suppressed. As a result, the accuracy of temperature measurement by the radiation thermometer is further improved, and the quality of the object to be processed is further stabilized.

  Here, from the viewpoint of suppressing a change in emissivity, the iron oxide layer is preferably a thick iron oxide layer, but the effect is that the entire surface of the object to be processed is completely removed by the iron oxide layer. It becomes almost saturated by being covered. Therefore, it is preferable to determine the degree of formation of the iron oxide layer in consideration of improving the heat treatment efficiency.

  Specifically, for example, a sample of an object to be processed is heated at a high frequency, and at that time, a contact thermometer such as a thermocouple is brought into contact with the surface of the object to be processed, and the temperature is measured, The temperature is measured with a meter to obtain temperature measurement data for both. For example, if the rate of change of the difference between the temperature measurement data is 3% or less per 10 seconds, it can be considered that a sufficient iron oxide layer has been formed. Thereafter, by adjusting the emissivity setting of the radiation thermometer, the temperature of the surface of the workpiece on which the iron oxide layer is formed can be accurately measured by the radiation thermometer.

  Preferably, in the above high-frequency heat treatment method, the surface stabilization step includes an acidic solution dipping step in which an iron oxide layer is formed on the surface of the treatment object by dipping the treatment object in an acidic solution. . As in the case described above, in the temperature range where the workpiece is heated, the oxidation resistance is higher than that of the workpiece, and an iron oxide layer having a small change in emissivity is formed on the surface of the workpiece, By performing the high-frequency heat treatment, a change in emissivity on the surface of the object to be processed during the heat treatment is suppressed. As a result, the accuracy of temperature measurement by the radiation thermometer is further improved, and the quality of the object to be processed is further stabilized.

  Here, sulfuric acid, hydrochloric acid, nitric acid, or the like can be employed as the acidic solution for immersing the object to be processed. After the formation of the iron oxide layer, the surface temperature of the object to be processed is measured with a contact thermometer and a radiation thermometer in the same manner as described above, and whether or not the iron oxide layer is sufficiently formed by the same procedure. Judgment can be made.

  A high-frequency heat treatment product according to the present invention is characterized by being heat-treated by the high-frequency heat treatment method described above. According to the high-frequency heat treatment product of the present invention, the heat treatment is performed by temperature control and the high-frequency heat treatment method that makes it easy to determine heat treatment conditions, so that the price can be reduced and the quality is stable. Goods can be provided.

  The high-frequency heat-treated product of the present invention can be applied to mechanical parts made of steel, such as bearing races and rolling elements, and manufactured by quenching and hardening.

  As is apparent from the above description, according to the high-frequency heat treatment method of the present invention, it is possible to control the temperature, easily determine the conditions for heat treatment, and to stabilize the quality of the object to be processed. Can be provided. Furthermore, according to the high frequency heat-treated product of the present invention, it is possible to provide a high-frequency heat treated product with reduced manufacturing cost and stable quality.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing a configuration of a rolling bearing outer ring as a high-frequency heat-treated product in the first embodiment which is an embodiment of the present invention. With reference to FIG. 1, the structure of the rolling bearing outer ring in Embodiment 1 is demonstrated.

  Referring to FIG. 1, rolling bearing outer ring 1 as the high frequency heat treatment product in Embodiment 1 has an annular shape. The rolling bearing outer ring 1 is formed with a rolling surface 1C for rolling while the balls, rollers and the like as rolling elements are in contact with the inner peripheral surface 1B, and in contact with other members, the rolling bearing. It has 1 A of outer peripheral surfaces for hold | maintaining an outer ring | wheel with respect to the said other member. Here, it is preferable that the rolling bearing outer ring 1 has a hardness of 58 HRC or more from the viewpoint of rolling fatigue strength and rigidity. From the viewpoint of dimensional stability, the amount of retained austenite is preferably suppressed to 12% by volume or less.

  And since the rolling bearing outer ring 1 is heat-processed by the high frequency heat processing method in one embodiment of this invention demonstrated below, it becomes a high frequency heat-treated product with which manufacturing cost was suppressed and quality was stabilized. Yes.

  Next, induction hardening equipment as induction heat treatment equipment in Embodiment 1 which is an embodiment of the present invention will be described. FIG. 2 is a schematic diagram showing the configuration of the induction hardening equipment in the first embodiment. With reference to FIG. 2, the structure of the induction hardening equipment in Embodiment 1 is demonstrated.

  With reference to FIG. 2, induction hardening equipment 91 in Embodiment 1 is used in the induction heat treatment method of the present invention in which an object to be treated (for example, rolling bearing outer ring 1) is heated and hardened by induction heating. It is induction hardening equipment, and the temperature control device 50 for adjusting the temperature of the rolling bearing outer ring 1 as the object to be processed, and the quenching for adjusting the timing when the heated rolling bearing outer ring 1 should be cooled. And a control device 60. Further, as will be described later, the outer peripheral surface 1A and the inner peripheral surface 1B of the rolling bearing outer ring 1 are more resistant to oxidation than the rolling bearing outer ring 1 in the temperature range in which the rolling bearing outer ring 1 is heated, that is, in the quenching temperature. A high stabilization layer 9 is formed.

  The temperature control device 50 acquires temperature data of the outer peripheral surface 1A that is considered to have the highest temperature by high-frequency heating in the rolling bearing outer ring 1, and outputs temperature information based on the temperature data of the rolling bearing outer ring 1. A first radiation thermometer 3 as a temperature measuring device, and a temperature control signal connected to the first radiation thermometer 3 for controlling the heating state of the object to be processed based on the temperature information from the first radiation thermometer 3 And a heating device 2 that is connected to the temperature adjusting device 4 and heats the rolling bearing outer ring 1 by high-frequency heating based on a temperature control signal from the temperature adjusting device 4. The heating device 2 includes, for example, an induction coil for flowing a high-frequency current, and a power source that is connected to the induction coil and generates a high-frequency current.

  The quenching control device 60 acquires temperature data of the inner peripheral surface 1B that is farthest from the outer peripheral surface 1A that is considered to have the highest temperature by high-frequency heating and that is considered to have the smallest temperature rise, and the temperature of the inner peripheral surface 1B. A second radiation thermometer 5 serving as a quenching temperature measuring device that outputs temperature information based on the data, and a heating time connected to the second radiation thermometer 5 and based on the temperature information from the second radiation thermometer 5 And a cooling timing adjusting device 6 that determines the timing at which the rolling bearing outer ring 1 should be cooled and outputs a cooling start signal, and is connected to the cooling timing adjusting device 6, and based on the cooling start signal, the rolling bearing outer ring And a coolant injection device 7 as a cooling device for quenching and hardening the rolling bearing outer ring 1 by cooling 1.

  Here, each of the temperature adjusting device 4 and the cooling timing adjusting device 6 is, for example, a personal computer, and one personal computer may serve as both the temperature adjusting device 4 and the cooling timing adjusting device 6.

  Next, the induction hardening method as the induction heat treatment method in Embodiment 1, which is an embodiment of the present invention using the above-described induction hardening equipment, will be described. FIG. 3 is a diagram showing an outline of the induction hardening method according to the first embodiment which is one embodiment of the present invention.

  2 and 3, the induction hardening method according to the first embodiment is an induction heat treatment method in which a workpiece (rolling bearing outer ring 1) is heated and hardened by induction heating, and is a rolling bearing. A surface stabilization process 11 in which a stabilization layer 9 having higher oxidation resistance than the rolling bearing outer ring 1 is formed on the surface of the outer ring 1 in a temperature range where the rolling bearing outer ring 1 is heated, and stable in the surface stabilization process 11. The rolling bearing outer ring 1 on which the chemical layer 9 is formed is provided with a quench hardening step 10 for quench hardening.

  In the quench hardening process 10, the temperature control process 20 in which the temperature of the rolling bearing outer ring 1 on which the stabilizing layer 9 is formed is adjusted, and the timing at which the heated rolling bearing outer ring 1 is to be cooled is determined. And a quenching control step 30 in which the bearing outer ring 1 is cooled.

  The temperature control process 20 includes a temperature control process 23 for measuring the temperature of the surface of the stabilizing layer 9 formed on the outer peripheral surface 1A of the rolling bearing outer ring 1 by the first radiation thermometer 3, and a temperature control process. A temperature adjustment step 24 for outputting a temperature control signal for controlling the heating state of the rolling bearing outer ring 1 based on the temperature information measured in the temperature step 23, and a rolling bearing by high-frequency heating based on the temperature control signal. And a heating step 22 in which the outer ring 1 is heated.

  The quenching control process 30 includes a quenching temperature measuring process 35 in which the surface temperature of the stabilization layer 9 formed on the inner peripheral surface 1B of the rolling bearing outer ring 1 is measured by the second radiation thermometer 5, and quenching. A cooling timing adjustment step 36 in which the heating time is adjusted based on the temperature information measured in the temperature measuring step 35, the timing at which the rolling bearing outer ring 1 should be cooled is determined, and a cooling start signal is output; And a cooling step 37 in which the rolling bearing outer ring 1 is quenched and hardened by cooling the rolling bearing outer ring 1 based on the signal.

  The induction hardening method according to the first embodiment is performed by temperature control, and it is easy to determine the conditions for heat treatment. Therefore, the manufacturing cost of the rolling bearing outer ring 1 can be suppressed and the quality can be stabilized.

  In the surface stabilization step 11, the black body paint layer as the stabilization layer 9 may be formed by applying a black body paint to the surface of the rolling bearing outer ring 1. Further, instead of the black body paint layer, an iron oxide layer may be formed. This iron oxide layer may be formed, for example, by thermally oxidizing the surface of the rolling bearing outer ring 1, or may be formed by immersing the rolling bearing outer ring 1 in an acidic solution.

  Next, a specific procedure of the induction hardening method in the first embodiment will be described in detail by taking an example in which the material of the rolling bearing outer ring 1 is JIS SUJ2.

  Here, the hardness after tempering (tempering hardness) when tempering at 180 ° C. is HRC 58 or more (HV653 or more) from the viewpoint of strength, and the retained austenite amount is 12 vol% or less from the viewpoint of dimensional stability. Is set as a standard value.

  FIG. 4 is a TTA (Time Temperature Authentication) diagram of the SUJ2 material showing the relationship between the quenching temperature and the holding time for satisfying the standard value of the heat treatment. In FIG. 4, the horizontal axis indicates the quenching temperature (° C.), and the vertical axis indicates the holding time (seconds). Further, the region A is a range that does not satisfy the hardness standard, the region B is a range in which the amount of retained austenite does not satisfy the standard, and the region C is a range that satisfies any heat treatment quality standard. With reference to FIG. 4, the determination of the heat treatment conditions of the cooling timing adjustment step in the induction hardening method in the first embodiment will be described.

  In the induction hardening in the first embodiment, first, it is necessary to determine target heat treatment conditions (heating temperature and heating time conditions in quenching). Referring to FIG. 4, the hardness of the rolling bearing outer ring made of SUJ2 easily satisfies the standard as the quenching temperature and the holding time increase. On the other hand, the austenite amount becomes difficult to satisfy the standard as the quenching temperature and the holding time increase. In order to satisfy the heat treatment standard values (hardness standard and residual austenite content standard value), it is easier to control the heat treatment quality by setting conditions at a relatively low temperature for a long time. For example, in the treatment at a relatively high temperature of 1050 ° C., the holding time for ensuring the heat treatment quality standard is 15 seconds or longer, but if the holding time is 17 seconds or longer, the standard cannot be satisfied. On the other hand, in the treatment at 950 ° C., the holding time for ensuring the heat treatment quality is 20 seconds or more, and the standard can be satisfied up to 60 seconds. On the other hand, in order to take advantage of the high-frequency heat treatment that the temperature can be raised in a short time, it is desirable to perform the treatment at as high a temperature as possible for a short time. That is, referring to FIG. 4, the target heat treatment conditions can be determined in consideration of the balance between the ease of control of the heat treatment quality and the efficiency of the heat treatment.

  Note that FIG. 4 is a TTA diagram related to SUJ2, but if a TTA diagram corresponding to the material can be created, the heat treatment conditions may be determined according to the diagram, so the high frequency according to the first embodiment is used. The heat treatment method can be used regardless of the type of material.

  When the heat treatment conditions are determined, referring to FIG. 2, the heat treatment conditions are input to a temperature control device 4 such as a personal computer. The temperature adjusting device 4 is connected to the first radiation thermometer 3 and the heating device 2, and based on the temperature information from the first radiation thermometer 3, heats the temperature control signal by PID (Proportional Integral Differential) control. It can output to the apparatus 2 and the temperature transition of 1 A of outer peripheral surfaces which are the temperature measurement parts of the 1st radiation thermometer 3 can be controlled. The outer peripheral surface 1A is the portion where the magnetic flux penetrates most in the rolling bearing outer ring 1 and the temperature rises most due to high frequency heating.

  At the same time, the temperature measurement data of the second radiation thermometer 5 is taken into the cooling timing adjustment device 6 such as a personal computer, and it is determined whether or not the heating is sufficient from the temperature transition, and the cooling timing is adjusted. The determination of the cooling timing is performed based on whether or not the temperature transition of the inner peripheral surface 1B, which is the temperature measuring unit of the second radiation thermometer 5, falls within the specifications on the TTA diagram. In addition, the inner peripheral surface 1B is a portion where the penetration of the magnetic flux is the smallest in the rolling bearing outer ring 1 and the temperature rise due to the high frequency heating is the smallest. Further, the temperature adjusting device 4 and the cooling timing adjusting device 6 can be combined with the same personal computer.

  The following formulas (1) and (2) can be used to determine whether or not the values are within the standard on the TTA diagram, but preferably the temperature of the workpiece changes every moment. Thus, Expression (3) and Expression (2) obtained by correcting Expression (1) are used.

D _ep = 2 (Dt) ^1/2 Formula (1)
D _ep = A × 2 (Dt) ^1/2 Formula (3)
D: diffusion constant of carbon in steel, t: retention time (seconds), A: correction coefficient D = D ₀ exp (−Q / RT) (2)
D ₀ : Entropy term of diffusion constant, Q: activation energy, R: gas constant, T: absolute temperature (K)
Here, the value of the correction coefficient A is a value obtained from the following equation (4).

erf (A) = 1−0.1573C ₁ / C ₂ Formula (4)
C ₁ : Solid solubility of C at 727 ° C. (in the case of SUJ2: 0.52)
C ₂ : Solid solubility of C at an arbitrary temperature Equation (3) is an equation for calculating the carbon diffusion length D _ep when the value of C _{1 in} Equation (4) becomes C ₂ . The value of C ₂ is the solid solubility of carbon at an arbitrary temperature, and these values can be obtained in advance by experimental or thermodynamic equilibrium calculation. Cooling is performed when the value of the carbon diffusion length D _ep in formula (3) reaches a certain value (D _ep ^* ).

  In addition, the temperature measuring part of the 2nd radiation thermometer 5 does not necessarily need to be one place. By using a plurality of temperature measuring units, it is possible to ensure heat treatment quality at a plurality of sites.

FIG. 5 is an explanatory diagram showing the relationship between the quenching temperature and the holding time for explaining a method of integrating the correction D _ep value from the temperature transition. In the upper left graph of FIG. 5, the horizontal axis is time t and the vertical axis is temperature T, on the temperature control side (outer peripheral surface 1A of the rolling bearing outer ring 1) and quenching control side (inner peripheral surface 1B of the rolling bearing outer ring 1). The temperature transition at is shown. The upper right diagram is an enlarged view of the area α of the upper left graph. Also, the lower part shows a calculation formula for integrating the value of the correction D _ep from the temperature transition.

Referring to FIG. 5, while the workpiece is heated, the temperature of the temperature measurement part for determining the cooling timing (that is, the inner peripheral surface 1B which is the temperature measurement part of the second radiation thermometer 5) is since changes from moment, the value of the correction _{D ep (D} corrected in equation (3) _ep, hereinafter simply referred to _{D ep),} as shown in FIG. _5, and _{D ep1 → D ep2 → ··· →} D epn It is necessary to add up. When the temperature rise of the rolling bearing outer ring 1 is started, the quenching control side (inner peripheral surface 1B side) is delayed as compared with the temperature control side because the magnetic flux enters less than the temperature control side (outer peripheral surface 1A side). Temperature rises. Usually, when the temperature exceeds 727 ° C., the austenitization of iron starts, but when the rate of temperature rise is fast, the heating transformation temperature of iron changes. Therefore, the temperature for calculating the diffusion length must be changed according to the rate of temperature increase.

Since the rate of temperature increase varies depending on the power supply capacity, the shape of the coil and the object to be processed, it is preferable that the temperature for calculating the diffusion length is appropriately changed depending on the type of the apparatus and the object to be processed. When the temperature on the quenching control side exceeds the heating transformation temperature, the diffusion length D _ep is calculated by the equation in the figure. As soon as D _{epn at} any time exceeds D _ep ^* , quenching is started. The value of D _ep ^* is preferably as small as possible within a range in which a predetermined heat treatment quality can be maintained from the viewpoint of reducing the heat treatment time. However, from the viewpoint of stabilizing the quality, it is desirable to set a set value with some safety.

FIG. 6 is a diagram showing changes in hardness and processing time with respect to the value of D _ep ^* . FIG. 6 shows the results when the maximum temperature reached is 900 ° C., the cooling rate is 0 ° C./second, and tempering is performed at 180 ° C. for 120 minutes after quenching. In FIG. 6, the horizontal axis indicates the value of D _ep ^* (mm), and the vertical axis indicates the hardness (HV) and the processing time (seconds). In the figure, black circles indicate hardness and white circles indicate processing time.

Referring to FIG. 6, it can be seen that the processing time increases as D _ep ^* is set larger, because the required diffusion length becomes longer. It can also be seen that the hardness increases as the processing time increases as the value of D _ep ^* is set larger. However, the hardness had a region saturated when the heating was too long, and reached the maximum hardness with D _ep ^* of about 0.015 mm. Accordingly, it is considered that the value of D _ep ^* is preferably 0.015 mm or less. That is, in the case of the present embodiment, for example, the value of D _ep ^* is set to 0.015 mm, and when the integrated D _epn becomes 0.015 mm as described above, a cooling start signal is _sent from the cooling timing adjustment device 6. Output to the coolant injection device 7, and based on this, the coolant injection device 7 cools the rolling bearing outer ring 1 from a temperature of A ₁ point or more to a temperature of M _S point or less, thereby the rolling bearing outer ring 1. It can be hardened by hardening.

Note that the _point A when heated steel refers to a point that the structure of the steel corresponds to the temperature to start the transformation from ferrite to austenite. Further, the M _S point when the steel was austenitized is cooled, it refers to a point corresponding to a temperature to initiate the martensite.

  Next, a modification of the first embodiment will be described. The high-frequency heat treatment method, high-frequency heat treatment facility, and high-frequency heat treatment product in the modification of the first embodiment basically have the same configuration as that of the first embodiment described above. However, the difference is that the following equations (5) and (2) are used to determine whether the temperature transition of the inner peripheral surface 1B of the rolling bearing outer ring 1 is within the standard on the TTA diagram in the determination of the cooling timing. ing. Hereinafter, a method for determining whether or not the temperature transition of the inner peripheral surface 1B of the rolling bearing outer ring 1 has fallen within the standard on the TTA diagram will be described using Equation (5) and Equation (2).

∂C / (∂t) = D∂ ² C / (∂x ² ) (5)
D: carbon diffusion constant in steel, C: carbon concentration (mass%), t: time (seconds), x: distance D = D ₀ exp (−Q / RT) (2)
D ₀ : Entropy term of diffusion constant, Q: activation energy, R: gas constant, T: absolute temperature (K)
Here, when Expression (5) is expressed by a difference equation, the following expression is obtained.

C _{m, n + 1} = rC _{m + 1, n} + (1-2r) C _{m, n} + rC _{m-1, n} (6)
r = D × Δt / (Δx) ² Formula (7)
The cooling timing is determined by solving equation (6) under a certain boundary condition and determining whether the solid solution state of carbon in the material satisfies a predetermined condition. Here, the boundary condition is, for example, that the solid solution concentration of carbon at a certain temperature at the interface between the iron carbide (cementite; Fe ₃ C) and the base material in the steel constituting the rolling bearing outer ring 1 during heating is It can be given under the assumption that it is equal to the solid solubility of carbon.

FIG. 7 is a diagram illustrating a temperature transition of the object to be processed during heating. FIGS. 8 to 10 show the positions at the positions between the two Fe ₃ C at the respective times T (after 0.4 seconds, after 0.8 seconds and after 1.2 seconds) from the start of the solid solution of carbon. It is a figure which shows carbon distribution (distribution of solid solution carbon concentration (mass%)). In FIG. 7, the horizontal axis represents time (seconds) and the vertical axis represents temperature (° C.). 8 to 10, the horizontal axis indicates the distance (position) (mm) from the reference boundary point, and the vertical axis indicates the carbon concentration (mass%). In the calculation of the solid solution state of carbon, the distance between the two Fe ₃ Cs is set to 0.012 mm, and the amount of solid solution carbon (carbon concentration (mass%)) at the boundary point (the interface between Fe ₃ C and the substrate) is calculated. Value) was a value (calculated with thermodynamic equilibrium calculation software) obtained from the solid solubility curve of SUJ2. This solid solubility curve equation (solid solubility equation) can be obtained in advance for each material by experimental or thermodynamic equilibrium calculation.

Referring to FIGS. 7 to 10, for example, when the rolling bearing outer ring 1 is heated as shown in FIG. 7, the distribution of the solute carbon concentration is as shown in FIGS. _When the distance between ₃ C is 0.012 mm, the solid solution carbon concentration is lowest at the position of 0.006 mm), and as the time passes, the solid solution carbon concentration increases as a whole, and the central position And the difference between both ends (the interface between Fe ₃ C and the substrate) tends to be small.

  The cooling start signal in the cooling timing adjustment step 36 can be output when, for example, the inner peripheral surface 1B of the rolling bearing outer ring 1 satisfies the solid solution carbon concentration condition, which is the quenching condition, at the central position. Further, the distance between the two boundary points (the distance between carbides) can be appropriately changed depending on the difference in structure and material before quenching of the workpiece.

  That is, the determination of the cooling timing of this modification is performed as follows, for example. First, the temperature on the quenching control side is measured by the second radiation thermometer 5 (step A), and the carbon content at the boundary is calculated from the measured temperature (step B). Formula (6) is calculated by giving the value of the carbon amount at the boundary to the boundary condition of Formula (6) (Step C). Through the above steps, the solid solution carbon concentration distribution as shown in FIGS. 8 to 10 can be calculated (step D). From the obtained solute carbon concentration distribution, it is confirmed whether or not the carbon concentration at the center position of the solute carbon concentration distribution has reached a predetermined carbon concentration (for example, 0.6 to 0.8 mass%) (step). E). If the carbon concentration at the central position has reached a predetermined carbon concentration, cooling is started (step F). If not, cooling is not started and heating is continued and the process returns to step A again.

  Further, the equation (6) in the step C can be solved by the difference method as follows. First, the carbon concentration at both ends of the carbon distribution in FIGS. 8 to 10 is the carbon concentration at the carbide substrate interface. Accordingly, carbon is supplied from this position to the substrate at a certain concentration (carbon solid solubility).

For example, as shown in FIGS. 8 to 10, if 5 points are separated between adjacent Fe ₃ Cs (7 points if boundary points are included), 5 simultaneous equations can be obtained _{. n} , C _{1, n} , C _{2, n} , C _{3, n} , C _{4, n} , C _{5, n} , C _{6, n} . Among these, C _{0, n} and C _{6, n} are the positions of the interface between the carbide and the substrate, and therefore the value of the carbon concentration can be given from the solid solubility equation. As a result, there are five simultaneous equations and five unknowns, so the values of C _{1, n} , C _{2, n} , C _{3, n} , C _{4, n} , C _{5, n} can be obtained.

  In addition, by calculating the solid solution carbon concentration not only on the quenching control side but also on the temperature control side, the amount of retained austenite on the temperature control side can be estimated from the solid solution state of carbon on the temperature control side. it can.

  FIG. 11 is a diagram showing a distribution of solute carbon concentrations on the temperature control side and the quench control side when quenching is performed by the method of the present modification. In FIG. 11, the horizontal axis indicates the distance (position) (mm) from the reference boundary point, and the vertical axis indicates the carbon concentration (mass%). This data shows that the quenching temperature (heating temperature) is constant at 950 ° C., the rate of temperature rise to the quenching temperature is 300 ° C./second, the distance between carbides is 0.012 mm, and the cooling start condition is the carbon concentration. The value at the center position is 0.6% by mass. From FIG. 11, it can be seen that the value of the solute carbon concentration is generally higher on the temperature control side than on the quenching control side. This is because in the rolling bearing outer ring 1, the temperature on the temperature control side close to the induction coil included in the heating device 2 is higher than that on the quenching control side.

  Furthermore, it is preferable to determine the temperature for starting the calculation of the solid solution carbon concentration, that is, the temperature for starting the solid solution of carbon in the substrate, in consideration of the rate of temperature increase. Hereinafter, the determination method will be described.

When the steel is heated to 727 ° C. (A ₁ point temperature) or more while maintaining an equilibrium state, austenitization starts, and along with this, carbon solid solution starts. However, if the heating rate is high, A ₁ point temperature changes are affecting the heating rate, _C1 point A (heating transformation point) to start the austenitizing at temperatures. Therefore, it is preferable to change the starting temperature of the calculation in consideration of the rate of temperature increase.

FIG. 12 is a diagram showing the change in the heating transformation point depending on the heating rate in steel (JIS SUJ2) having a carbon content of 1 mass%. In FIG. 12, the horizontal axis represents the rate of temperature increase (° C./second), and the vertical axis represents the heating transformation point A _C1 (° C.). Referring to FIG. 12, it can be seen that the heating transformation point A _C1 changes from 727 ° C. to 950 ° C. when the temperature rising rate changes. Therefore, the change in the heating transformation point A _C1 with respect to the change in the heating rate in the composition of the object to be processed is examined in advance, the heating transformation point A _C1 is obtained from the heating rate during the heating of the object to be processed, and the heating transformation is performed. Based on the point _AC1 , the calculation start temperature (carbon solution start temperature) of the solid solution carbon concentration can be determined.

FIG. 13 is a diagram for explaining a method of determining the calculation start temperature of the solute carbon concentration in consideration of the rate of temperature rise. In FIG. 13, the horizontal axis indicates time, and the vertical axis indicates temperature. In FIG. 13, the temperature transition on the temperature control side (the outer peripheral surface 1A of the rolling bearing outer ring 1 in FIG. 2), the temperature transition on the quenching control side (the inner peripheral surface 1B of the rolling bearing outer ring 1 in FIG. 2), and the heating transformation. Point A _C1 is shown.

Referring to FIG. 13, in the initial stage of heating, heating on the temperature control side is rapidly performed, so that the rate of temperature increase on the quenching control side also increases and the heating transformation point increases. When the temperature on the temperature control side approaches a predetermined set temperature, heating is controlled by the temperature adjustment device 4 so that the rate of temperature increase becomes gentle. Therefore, the rate of temperature increase on the quenching control side also becomes gentle, and the heating transformation point A _C1 decreases. When the time elapses, the heating transformation point A _C1 intersects the temperature transition of the quenching control side. Since this intersection point indicates the start temperature of austenitization, the calculation of the solute carbon concentration can be started from the temperature of this intersection point (that is, the start temperature of austenitization).

  And as demonstrated using FIGS. 8-10, when the carbon concentration in the center position of distribution of solute carbon concentration exceeds predetermined carbon concentration (for example, 0.6-0.8 mass%), Immediately after cooling, the workpiece (rolling bearing outer ring 1) can be hardened by hardening.

(Embodiment 2)
FIG. 14 is a diagram showing an outline of the configuration of the induction hardening equipment in the second embodiment which is an embodiment of the present invention. FIG. 15 is a diagram showing an outline of the induction hardening method in the second embodiment which is one embodiment of the present invention. With reference to FIG. 14 and FIG. 15, the induction hardening equipment and the induction hardening method in Embodiment 2 will be described.

  Referring to FIG. 14, induction hardening equipment 92 in the second embodiment basically has the same configuration as induction hardening equipment 91 in the first embodiment. However, the induction hardening equipment 92 according to the second embodiment is connected to the heating device 2, the temperature adjustment device 4, and the cooling timing adjustment device 6, and stores the transition data of the power output and the cooling timing data as process data. In the point provided with the apparatus 70, it differs from the induction hardening equipment 91 of Embodiment 1. FIG.

  Referring to FIG. 15, the induction hardening method according to the second embodiment is an induction heat treatment method in which an object to be treated (for example, the rolling bearing outer ring 1) is quenched and hardened by induction heating, and includes a data acquisition step. And a storage process, a confirmation process, and a mass production process.

  In the data acquisition step, the process data is acquired by heating and hardening the sample of the rolling bearing outer ring 1. In the storing step, the transition data of the power output output from the power source for high frequency heating to the induction coil to heat the sample of the rolling bearing outer ring 1 in the data acquisition step and the cooling timing of the sample of the rolling bearing outer ring 1 are specified. Cooling timing data is stored as process data.

  In the confirmation step, the validity of the transition data of the power output and the cooling timing data is confirmed based on the material data of the rolling bearing outer ring 1 that has been quenched and hardened in the data acquisition step. That is, for example, the temperature transition data of the object to be processed in the data acquisition process is stored, and the stored temperature transition data is analyzed to determine whether there is an influence of disturbance, and the process data stored in the storage process The validity of the power output transition data and the cooling timing data is confirmed. In addition, the material data of the sample of the rolling bearing outer ring 1 that has been actually heat-treated may be actually obtained by experiment, and the validity of the transition data of the power output and the cooling timing data may be confirmed.

  Here, in the temperature measurement of the rolling bearing outer ring 1, when there is an influence of disturbance, an abnormal value is recorded in the temperature transition data. Therefore, it is possible to determine the presence or absence of the disturbance from the stored temperature transition data. For example, when there is a discontinuous region in the temperature transition data, it can be determined that there is a disturbance. In order to make a more accurate determination, a contact-type or non-contact-type thermometer that measures the temperature of the same part can be provided, and the presence or absence of disturbance can be determined based on the consistency of both data. As a specific determination method, for example, when the temperature difference is 5% or more from both data, it can be determined that there is a disturbance. The determination of the disturbance can be made by an operator confirming the temperature transition data, but can also be made by another automated device. Specifically, for example, when the differential value of the temperature transition of the stored temperature transition data is 1000 ° C./second or more or −1000 ° C./second or less, there is a method of determining that there is a disturbance, or the same part as described above. There is a means for providing a thermometer for measuring the temperature of the above and determining that there is a disturbance when a difference of 5% or more occurs between the data of the two.

  In the mass production process, induction hardening of the rolling bearing outer ring 1 is performed in accordance with the transition data and cooling timing data of the power output stored in the storage process and validated in the confirmation process. The quench hardening in the data acquisition process is performed by the induction heat treatment method of the present invention, for example, the induction hardening method of the first embodiment.

  By hardening and hardening the rolling bearing outer ring 1 as an object to be processed by the induction hardening method according to the second embodiment, temperature control becomes possible and not only heat treatment conditions can be easily determined, but also disturbance to process data. Is further suppressed, and the quality of the workpiece (rolling bearing outer ring 1) is stabilized.

  Then, the rolling bearing outer ring 1 as the induction hardened product in the second embodiment, which has been hardened by the induction hardening method in the second embodiment, can be reduced in price and further can be induction hardened with a more stable quality. It has become.

  Next, details of induction hardening in the second embodiment will be described. FIG. 16 is a diagram showing the flow of data and commands in each step of induction hardening according to the second embodiment. In FIG. 16, the data flow in the data acquisition process is indicated by solid arrows, the data flow in the storage process is indicated by broken arrows, the data flow in the confirmation process is indicated by double broken arrows, and the data flow in the mass production process is indicated by double solid arrows. Has been. With reference to FIG. 16, the data flow in each step of induction hardening according to the second embodiment will be described.

  Referring to FIG. 16, in the data acquisition process, the temperature data of the sample of the rolling bearing outer ring 1 as the object to be processed measured by the temperature control temperature measuring device (first radiation thermometer 3) is the temperature adjusting device 4. Sent to. In the temperature control device 4, the necessary power output is determined from the target heating temperature of the rolling bearing outer ring 1 and the obtained temperature data of the sample of the rolling bearing outer ring 1, and the power supply output is commanded to the power supply of the heating device 2. The power supply that has received the command outputs power to the induction coil of the heating device 2, and the sample of the rolling bearing outer ring 1 is heated to a target temperature.

  On the other hand, the temperature data of the sample of the rolling bearing outer ring 1 measured by the quenching temperature measuring device (second radiation thermometer 5) is sent to the cooling timing adjusting device 6. The cooling timing adjusting device 6 determines the cooling timing from the acquired temperature and heating time of the sample of the rolling bearing outer ring 1 and commands the cooling device such as the coolant injection device 7 to start cooling. Thereby, the sample of the rolling bearing outer ring 1 is quenched and hardened by hardening. At this time, since this data acquisition process is performed by temperature control, the heating history of the sample of the rolling bearing outer ring 1 is clear. Therefore, as long as the temperature data is accurate, appropriate heat treatment is performed, and the rolling bearing outer ring 1 having the desired quality is obtained. As a result, it is not necessary to determine the conditions for the heat treatment while checking the quality of the object to be processed, and the conditions can be determined easily. Further, since a stabilization layer is formed on the surface of the object to be processed, the accuracy of temperature measurement by the radiation thermometer is high.

  In the storage step, the temperature data acquired by the temperature adjustment device 4 and the cooling timing adjustment device 6 in the data acquisition step is stored in the storage device 70 as temperature transition data. Moreover, the power supply output which the power supply of the heating apparatus 2 output to the induction coil is memorize | stored in the memory | storage device 70 as transition data of a power supply output. Further, the timing of the cooling start command output from the cooling timing adjusting device 6 to the cooling device such as the coolant injection device 7 is stored in the storage device 70 as cooling timing data. Here, the cooling timing is stored as the time from the start of heating, for example.

  In the confirmation step, for example, a thermometer capable of measuring the same part as the first radiation thermometer 3 and the second radiation thermometer 5 is provided, and the part is temperature-measured. By comparing this temperature measurement data with the temperature transition data measured by the first radiation thermometer 3 and the second radiation thermometer 5 and stored in the storage device 70, the presence or absence of disturbance is determined.

  In the mass production process, the rolling bearing outer ring 1 is heated and hardened based on the power output transition data and the cooling timing data that are stored in the storage process and validated in the confirmation process. At this time, this mass production process is not carried out based on the real-time temperature data from the first radiation thermometer 3 and the second radiation thermometer 5 that may cause disturbance, but the validity of the power supply output whose validity has been confirmed. It is implemented by power control based on the transition data and the cooling timing data. Therefore, the rolling bearing outer ring 1 having stable quality can be obtained.

  The storage device 70 may be installed as an independent device. However, the storage device 70 may be installed as a device such as the temperature adjustment device 4 and the cooling timing adjustment device 6 by a personal computer having a storage unit such as a hard disk. Also good. Moreover, each process of the induction hardening method of this Embodiment can be implemented by operating the said personal computer by the single or several program corresponding to each process, for example using a personal computer as a control apparatus.

(Embodiment 3)
FIG. 17 is a schematic diagram showing the configuration of the induction tempering equipment used in the induction heat treatment method of the third embodiment. With reference to FIG. 17, the structure of the induction tempering equipment in Embodiment 3 is demonstrated.

  Referring to FIG. 17, induction tempering equipment 93 according to Embodiment 3 is used in the induction heat treatment method of the present invention in which an object to be treated (for example, rolling bearing outer ring 1) is tempered by induction heating. A temperature control device 51 for adjusting the temperature of the rolling bearing outer ring 1 as an object to be processed, and a tempering for adjusting the timing when the heated rolling bearing outer ring 1 should be cooled. And a return control device 61. As will be described later, the outer peripheral surface 1A and the inner peripheral surface 1B of the rolling bearing outer ring 1 are more resistant to oxidation than the rolling bearing outer ring 1 in the temperature range in which the rolling bearing outer ring 1 is heated, that is, the tempering temperature. A high stabilization layer 9 is formed.

  The temperature control device 51 obtains temperature data of the outer peripheral surface 1A that is considered to have the highest temperature due to high frequency heating in the rolling bearing outer ring 1, and outputs temperature information based on the temperature data of the rolling bearing outer ring 1. A first radiation thermometer 13 as a temperature measuring device and a temperature control signal connected to the first radiation thermometer 13 for controlling the heating state of the workpiece based on the temperature information from the first radiation thermometer 13 And a heating device 12 that is connected to the temperature adjusting device 14 and heats the rolling bearing outer ring 1 by high-frequency heating based on a temperature control signal from the temperature adjusting device 14. The heating device 12 includes, for example, an induction coil for flowing a high-frequency current and a power source that is connected to the induction coil and generates a high-frequency current.

  The tempering control device 61 obtains temperature data of the inner peripheral surface 1B farthest from the outer peripheral surface 1A considered to have the highest temperature by high frequency heating and considered to have the smallest temperature rise, and the temperature of the inner peripheral surface 1B. A second radiant thermometer 15 serving as a tempering temperature measuring device for outputting temperature information based on the data, and a heating time connected to the second radiant thermometer 15 based on the temperature information from the second radiant thermometer 15 The cooling timing adjusting device 16 that determines the timing at which the rolling bearing outer ring 1 should be cooled and outputs a cooling start signal is connected to the cooling timing adjusting device 16, and based on the cooling start signal, the rolling bearing outer ring And a coolant injection device 17 as a cooling device that terminates tempering of the rolling bearing outer ring 1 by cooling 1.

  Here, each of the temperature adjusting device 14 and the cooling timing adjusting device 16 is, for example, a personal computer, and one personal computer may serve as both the temperature adjusting device 14 and the cooling timing adjusting device 16.

  Next, an induction tempering method will be described as an induction heat treatment method according to Embodiment 3, which is an embodiment of the present invention using the above-described induction tempering equipment. FIG. 18 is a diagram showing an outline of the induction tempering method according to the third embodiment which is an embodiment of the present invention.

  Referring to FIGS. 17 and 18, the induction tempering method of the third embodiment is an induction heat treatment method in which an object to be treated (for example, the rolling bearing outer ring 1) is heated and tempered by induction heating, A surface stabilization process 11 in which a stabilization layer 9 having higher oxidation resistance than the rolling bearing outer ring 1 is formed on the surface of the rolling bearing outer ring 1, and a rolling bearing outer ring in which the stabilization layer 9 is formed in the surface stabilization process. And a tempering step 110 in which 1 is heated and tempered.

  The tempering step 110 includes a temperature control step 120 in which the temperature of the rolling bearing outer ring 1 is adjusted, and a tempering control in which the timing at which the heating of the rolling bearing outer ring 1 should be finished is determined to cool the rolling bearing outer ring 1. Step 130 is included.

  The temperature control process 120 is measured in a temperature control temperature measurement process 123 in which the temperature of the surface of the stabilization layer 9 formed on the surface of the rolling bearing outer ring 1 is measured by a radiation thermometer, and in the temperature control temperature measurement process 123. Based on the temperature information, a temperature adjusting step 124 for outputting a temperature control signal for controlling the heating state of the rolling bearing outer ring 1, and the rolling bearing outer ring 1 is heated by high frequency heating based on the temperature control signal. Heating step 122.

  The tempering control process 130 includes a tempering temperature measurement process 135 in which the surface temperature of the stabilization layer 9 formed on the surface of the rolling bearing outer ring 1 is measured by a radiation thermometer, and a tempering temperature measurement process 135. The heating time is adjusted based on the measured temperature information, the timing at which the rolling bearing outer ring 1 is to be cooled is determined, and the cooling start signal is output, and the rolling is adjusted based on the cooling start signal. And a cooling step 137 in which the tempering of the rolling bearing outer ring 1 is completed when the bearing outer ring 1 is cooled.

  The induction tempering method in the third embodiment is carried out by temperature control, and since it is easy to determine the conditions for heat treatment, the manufacturing cost of the rolling bearing outer ring 1 can be suppressed and the quality can be stabilized. In addition, in the induction tempering method of the third embodiment, for example, the workpiece having the same configuration as the rolling bearing outer ring 1 of the first embodiment described with reference to FIG. Tempering can be performed. As a result, the rolling bearing outer ring 1 as the high frequency heat-treated product in the third embodiment which is an embodiment of the present invention is a high-frequency heat-treated product with reduced manufacturing cost and stable quality.

  In the surface stabilization step 11, as in the first embodiment, a black body paint layer is formed as the stabilization layer 9 by applying a black body paint to the surface of the rolling bearing outer ring 1. Alternatively, an iron oxide layer may be formed instead of the black body paint layer. This iron oxide layer may be formed, for example, by thermally oxidizing the surface of the rolling bearing outer ring 1, or may be formed by immersing the rolling bearing outer ring 1 in an acidic solution.

  Next, the high frequency heat treatment method of the third embodiment will be specifically described by taking the rolling bearing outer ring 1 made of SUJ2 as an example. This rolling bearing outer ring 1 is quenched by quenching from 850 ° C. in an RX gas atmosphere furnace. Here, from the viewpoint of strength, the heat treatment standard of the workpiece after tempering is set to hardness HRC58 or more and HRC62 or less.

The following relational expression is established between the material strength and the tempering temperature and tempering time.
X = 1-exp {-(kt) ^N }
k = Aexp (−Q / RT)
M = M ₀ − (M ₀ −M _f ) X
X: rate of change of mechanical properties, k: reaction rate coefficient, t: tempering time (seconds), N: time index, A: vibration factor term, Q: activation energy, R: gas constant, T: tempering Temperature (K), M: Hardness after tempering, M ₀ : Hardness after quenching, M _f : Raw material hardness Accordingly, the following equation for the tempering time t can be derived from these equations.

t = [ln {(M ₀ −M _f ) / (M−M _f )} × {Aexp (−Q / RT)} ^−N ] ^{1 / N} Expression (8)
The hardness M ₀ and the raw material hardness M _{f after} quenching in the formula (8) can be measured. Further, since N, A, and Q can be obtained experimentally, the value of the tempering temperature T can be substituted and the tempering time t can be calculated by the equation (8). In the cooling timing adjustment step of the third embodiment, the tempering time t can be adjusted based on the equation (8). Expression (8) is a relational expression between the heat treatment temperature and the holding time with respect to the standard quality (hardness) of the object to be processed, and therefore can be used effectively regardless of the shape of the rolling bearing outer ring 1.

  FIG. 19 is a condition diagram showing the relationship between the tempering temperature T and the tempering time t for obtaining a predetermined hardness after tempering. In FIG. 19, the horizontal axis indicates the tempering temperature (° C.), and the vertical axis indicates the holding time (seconds). Region A is a range of HRC62 or higher, region B is a range of HRC58 or lower, and region C is a range of HRC58-62. With reference to FIG. 19, the determination method of the heating temperature and time conditions (tempering conditions) of tempering is demonstrated.

  The condition diagram shown in FIG. 19 can be produced based on the equation (8) for obtaining the tempering time t. Referring to FIG. 19, tempering in a shorter time becomes possible as the tempering temperature becomes higher. For this reason, a higher tempering temperature is desirable from the viewpoint of reducing the heat treatment time. However, since it is considered that tempering unevenness due to temperature unevenness is likely to occur when the tempering temperature is increased, the tempering temperature can be determined from the balance between the heat treatment time and the tempering unevenness.

  When the tempering conditions are determined, the tempering conditions are input to the temperature control device 14 such as a personal computer with reference to FIG. The temperature adjusting device 14 is connected to the second radiation thermometer 13 and the heating device 12, and based on the temperature information from the second radiation thermometer 13, outputs a temperature control signal to the heating device 12 by PID control. The temperature transition of the rolling bearing outer ring 1 is controlled. At the same time, the temperature information of the second radiation thermometer 15 is taken into the cooling timing adjusting device 16 such as a personal computer, and it is determined whether the heating is sufficient from the temperature transition, and the tempering end timing is adjusted.

  FIG. 20 is an explanatory diagram showing the relationship between the tempering temperature and the holding time for explaining a method of integrating the hardness value after tempering from the temperature transition. In the upper left graph of FIG. 20, the temperature transition is shown with time t on the horizontal axis and temperature T on the vertical axis. Further, the upper right diagram is an enlarged view of the area β of the upper left graph. Also, the lower part shows a calculation formula for integrating the value of hardness M after tempering from the temperature transition.

Referring to FIG. 20, since the temperature information from second radiation thermometer 15 changes every moment, the value of M (hardness after tempering) is integrated as shown in FIG. 20 while calculating t _n ^* . It is desirable to calculate as follows. When the condition that the hardness after tempering becomes the target hardness is satisfied, the rolling bearing outer ring 1 is cooled by the coolant injection device 17. The temperature adjusting device 14 and the cooling timing adjusting device 16 can also serve as the same personal computer.

  The heat treatment facility of the third embodiment has basically the same configuration as the heat treatment facility of the first embodiment described above. Therefore, for example, by using a personal computer as a control device and using a program corresponding to the target heat treatment, the induction hardening device and the induction tempering device can be used together.

(Embodiment 4)
FIG. 21 is a diagram showing an outline of the configuration of the induction tempering equipment according to the fourth embodiment which is an embodiment of the present invention. Moreover, FIG. 22 is a figure which shows the outline of the induction tempering method in Embodiment 4 which is one embodiment of this invention. With reference to FIG. 21 and FIG. 22, the induction tempering equipment and the induction tempering method in Embodiment 4 will be described.

  Referring to FIG. 21, induction tempering equipment 94 in the fourth embodiment basically has the same configuration as induction tempering equipment 93 in the third embodiment. However, the induction tempering equipment 94 according to the fourth embodiment is connected to the heating device 12, the temperature adjustment device 14, and the cooling timing adjustment device 16, and stores the transition data of the power output and the cooling timing data as process data. It differs from the induction tempering equipment 93 of Embodiment 3 in that the apparatus 71 is provided.

  Referring to FIG. 22, the induction tempering method according to the fourth embodiment is an induction heat treatment method in which an object to be treated (for example, rolling bearing outer ring 1) is tempered by induction heating, and data acquisition is performed. A process, a storage process, a confirmation process, and a mass production process are provided.

  In the data acquisition step, the process data is acquired by heating and tempering the sample of the rolling bearing outer ring 1. In the storing step, the transition data of the power output output from the power source for high frequency heating to the induction coil to heat the sample of the rolling bearing outer ring 1 in the data acquisition step and the cooling timing of the sample of the rolling bearing outer ring 1 are specified. Cooling timing data is stored as process data.

  In the confirmation step, the validity of the power output transition data and the cooling timing data is confirmed based on the material data of the rolling bearing outer ring 1 tempered in the data acquisition step. That is, for example, the temperature transition data of the object to be processed in the data acquisition process is stored, and the stored temperature transition data is analyzed to determine whether there is an influence of disturbance, and the process data stored in the storage process The validity of the power output transition data and the cooling timing data is confirmed. In addition, the material data of the sample of the rolling bearing outer ring 1 that has been actually heat-treated may be actually obtained by experiment, and the validity of the transition data of the power output and the cooling timing data may be confirmed.

  Here, in the temperature measurement of the rolling bearing outer ring 1, when there is an influence of disturbance, an abnormal value is recorded in the temperature transition data. Therefore, it is possible to determine the presence or absence of the disturbance from the stored temperature transition data. For example, when there is a discontinuous region in the temperature transition data, it can be determined that there is a disturbance. In order to make a more accurate determination, a contact-type or non-contact-type thermometer that measures the temperature of the same part can be provided, and the presence or absence of disturbance can be determined based on the consistency of both data. As a specific determination method, for example, when the temperature difference is 5% or more from both data, it can be determined that there is a disturbance. The determination of the disturbance can be made by an operator confirming the temperature transition data, but can also be made by another automated device. Specifically, for example, when the differential value of the temperature transition of the stored temperature transition data is 1000 ° C./second or more or −1000 ° C./second or less, there is a method of determining that there is a disturbance, or the same part as described above. There is a means for providing a thermometer for measuring the temperature of the above and determining that there is a disturbance when a difference of 5% or more occurs between the data of the two.

  In the mass production process, the rolling bearing outer ring 1 is subjected to induction tempering in accordance with the transition data and cooling timing data of the power output stored in the storage process and validated in the confirmation process. The tempering in the data acquisition process is performed by the induction heat treatment method of the present invention, for example, the induction heat treatment method of the third embodiment.

  By tempering the rolling bearing outer ring 1 as the object to be processed by the induction tempering method in the fourth embodiment, temperature control becomes possible, not only the conditions for heat treatment are easily determined, but also the influence of disturbance on the process data. Is further suppressed, and the quality of the workpiece (rolling bearing outer ring 1) is stabilized.

  Then, the rolling bearing outer ring 1 as the induction tempered product in the fourth embodiment tempered by the induction tempering method in the fourth embodiment is an induction tempered product that is reduced in price and more stable in quality. ing.

  Next, details of induction tempering in the fourth embodiment will be described. FIG. 23 is a diagram showing the flow of data and commands in each step of induction tempering according to the fourth embodiment. In FIG. 23, the data flow in the data acquisition process is indicated by solid arrows, the data flow in the storage process is indicated by broken arrows, the data flow in the confirmation process is indicated by double broken arrows, and the data flow in the mass production process is indicated by double solid arrows. Has been. With reference to FIG. 23, the data flow in each step of induction tempering according to the fourth embodiment will be described.

  Referring to FIG. 23, in the data acquisition process, the temperature data of the sample of the rolling bearing outer ring 1 as the object to be processed measured by the temperature control temperature measuring device (first radiation thermometer 13) is the temperature adjusting device 14. Sent to. In the temperature control device 14, the necessary power output is determined from the target heating temperature of the rolling bearing outer ring 1 and the obtained temperature data of the sample of the rolling bearing outer ring 1, and the power output of the heating device 12 is commanded. The power supply that has received the command outputs power to the induction coil of the heating device 12, and the sample of the rolling bearing outer ring 1 is heated to a target temperature.

  On the other hand, the temperature data of the sample of the rolling bearing outer ring 1 measured by the tempering temperature measuring device (second radiation thermometer 15) is sent to the cooling timing adjusting device 16. The cooling timing adjusting device 16 determines the cooling timing from the acquired temperature and heating time of the sample of the rolling bearing outer ring 1, and commands a cooling device such as a coolant injection device to start cooling. Thereby, the sample of the rolling bearing outer ring 1 is cooled, and tempering is completed. At this time, since this data acquisition process is performed by temperature control, the heating history of the sample of the rolling bearing outer ring 1 is clear. Therefore, as long as the temperature data is accurate, an appropriate heat treatment is performed, and the rolling bearing outer ring 1 having the desired quality is obtained. As a result, it is not necessary to determine the conditions for the heat treatment while checking the quality of the object to be processed, and the conditions can be determined easily. In addition, since a stabilization layer is formed on the surface of the object to be processed, the accuracy of temperature measurement by the radiation thermometer is high.

  In the storage step, the temperature data acquired by the temperature adjustment device 14 and the cooling timing adjustment device 16 in the data acquisition step is stored in the storage device 70 as temperature transition data. Moreover, the power supply output which the power supply of the heating apparatus 12 output to the induction coil is memorize | stored in the memory | storage device 71 as transition data of a power supply output. Further, the timing of the cooling start command output from the cooling timing adjusting device 16 to the cooling device such as the coolant injection device is stored in the storage device 71 as cooling timing data. Here, the cooling timing is stored as the time from the start of heating, for example.

  In the confirmation step, for example, a thermometer capable of measuring the same part as the first radiation thermometer 13 and the second radiation thermometer 15 is provided, and the part is temperature-measured. By comparing this temperature measurement data with the temperature transition data measured by the first radiation thermometer 13 and the second radiation thermometer 15 and stored in the storage device 71, the presence or absence of disturbance is determined.

  In the mass production process, the rolling bearing outer ring 1 is heated and tempered based on the transition data and cooling timing data of the power output stored in the storage process and validated in the confirmation process. At this time, this mass production process is not performed based on the real-time temperature data from the first radiation thermometer 13 and the second radiation thermometer 15 which may cause disturbance, but the power output of which the validity has been confirmed. It is implemented by power control based on the transition data and the cooling timing data. Therefore, the rolling bearing outer ring 1 having stable quality can be obtained.

  The storage device 71 may be installed as an independent device. For example, the storage device 71 may be installed as a device such as the temperature adjustment device 14 and the cooling timing adjustment device 16 by a personal computer having a storage unit such as a hard disk. Also good. Moreover, each process of the induction tempering method of this Embodiment can be implemented by operating the said personal computer by the single or several program corresponding to each process, for example using a personal computer as a control apparatus.

  Examples of the present invention will be described below. A test was conducted to confirm the effect of the surface stabilization step in the high frequency heat treatment method of the present invention. The test procedure is as follows.

  As an object to be tested, a rolling bearing outer ring made of JIS SUJ2 and a rolling bearing outer ring made of JIS SUS440C were selected. And the same site | part of the to-be-processed object was measured with the radiation thermometer and the thermocouple, heating each to-be-processed object to the temperature of 900 degreeC or more and hold | maintaining. In addition, for the rolling bearing outer ring made of JIS SUS440C, after heating, a black body paint (Pyromark High Temperature Paint made by TEMPIL), which has excellent oxidation resistance at the heating temperature and hardly changes in emissivity, is applied to the surface before heating. A similar test was conducted.

  FIG. 24 is a diagram showing test results when a rolling bearing outer ring made of JIS SUJ2 is heated. FIG. 25 is a diagram showing test results when a rolling bearing outer ring made of JIS SUS440C is heated. Moreover, FIG. 26 is a figure which shows the test result at the time of heating, after apply | coating the black body coating material on the surface to the rolling bearing outer ring made from JIS SUS440C. 24 to 26, the horizontal axis indicates the heating time, the vertical axis indicates the heating temperature, the solid line indicates the temperature measurement data of the radiation thermometer, and the broken line indicates the temperature measurement data of the thermocouple. The test results of this example will be described with reference to FIGS.

  Referring to FIG. 24, in the case of a rolling bearing outer ring made of SUJ2, the ratio between the temperature measurement data of the radiation thermometer and the temperature measurement data of the thermocouple is almost within a short time from the start of heating, specifically about 15 seconds. It is constant. This is considered to be because, in the case of a rolling bearing outer ring made of SUJ2, an iron oxide layer was formed on the surface of the outer ring by thermal oxidation in a short time after the start of heating, and the surface state did not change thereafter. .

  On the other hand, referring to FIG. 25, in the case of a rolling bearing outer ring made of SUS440C, when 170 seconds have elapsed from the start of heating, the broken line indicating the thermocouple temperature measurement data is almost horizontal, and thereafter the radiation thermometer The ratio between the measured temperature data and the thermocouple measured data is almost constant. This is probably because SUS440C is superior in oxidation resistance compared to SUJ2, and therefore it takes a longer time to form the iron oxide layer to such an extent that the surface state does not change due to thermal oxidation. . That is, SUS440C needs to be held at 920 ° C. for about 170 seconds in order for the iron oxide layer to be formed to such an extent that the surface state does not change.

  From the above results, it is preferable to perform the surface stabilization process for the SUJ2 workpiece, but when the heat treatment is performed at a high temperature of 960 ° C. or higher, the surface stabilization process is not performed. It can be said that the influence on the temperature measurement accuracy is relatively small. In addition, as shown in FIG. 24, although a difference is recognized between the temperature measurement data of the radiation thermometer and the temperature measurement data of the thermocouple, the difference is eliminated by setting the emissivity of the radiation thermometer. The temperature measurement data of the radiation thermometer can be matched with the temperature measurement data of the thermocouple, which is an accurate temperature.

  On the other hand, regarding the object to be processed made of SUS440, it can be said that there is a great influence on the temperature measurement accuracy when the surface stabilization process is not performed, and it is highly necessary to perform the surface stabilization process. And when implementing the said surface stabilization process by thermal oxidation, it turned out that it needs to hold | maintain at 920 degreeC for about 170 second.

  In addition, referring to FIG. 26, with respect to the object to be processed made of SUS440 which has been heated after applying the black body paint, the temperature measurement data of the radiation thermometer and the temperature measurement data of the thermocouple are measured from the initial stage of heating. The ratio is almost constant. From this, it was confirmed that the temperature measurement accuracy of the object to be processed made of SUS440 by the radiation thermometer can be greatly improved by applying the black body paint as the surface stabilization process.

  From the above results, by performing the surface stabilization process of the present invention, the temperature measurement accuracy by the radiation thermometer is improved, and it is particularly composed of a material having high oxidation resistance such as stainless steel (for example, SUS440C, M50, etc.). It was confirmed that the quality of the induction heat-treated product can be stabilized.

  The embodiments and examples disclosed herein are illustrative in all respects and should not be construed as being restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The high-frequency heat treatment method and high-frequency heat-treated product of the present invention can be particularly advantageously applied to a high-frequency heat treatment method in which an object to be processed is heated by high-frequency heating and a high-frequency heat-treated product that has been heat-treated by high-frequency heating.

2 is a schematic cross-sectional view showing a configuration of a rolling bearing outer ring as a high frequency heat treatment product in Embodiment 1. FIG. It is the schematic which shows the structure of the induction hardening equipment in Embodiment 1. FIG. It is a figure which shows the outline of the induction hardening method in Embodiment 1. FIG. It is a TTA diagram of SUJ2 material which showed the relationship between the quenching temperature for satisfying the standard value of heat processing, and holding time. It is explanatory drawing which shows the relationship between the quenching temperature and the holding time for demonstrating the method of integrating | accumulating the value of correction _| amendment _Dep from a temperature transition. It is a figure which shows the change of the hardness and process time with respect to the value of _Dep ^* . It is a figure which shows the temperature transition of the to-be-processed object during a heating. In 0.4 seconds after the solid solution starting carbon is a diagram showing the carbon distribution at each position between two Fe 3 _C. In 0.8 seconds after the solid solution starting carbon is a diagram showing the carbon distribution at each position between two Fe 3 _C. In 1.2 seconds after the solid solution starting carbon illustrates a carbon distribution at each position between two Fe 3 _C. It is a figure which shows distribution of the solid solution carbon concentration in the temperature control side and the quenching control side at the time of implementing quenching by the method of a modification. It is a figure which shows the change of the heating transformation point by the temperature increase rate in steel (JIS SUJ2) with a carbon content of 1 mass%. It is a figure for demonstrating the method of determining the calculation start temperature of a solute carbon concentration in consideration of a temperature increase rate. It is a figure which shows the outline of a structure of the induction hardening equipment in Embodiment 2. FIG. It is a figure which shows the outline of the induction hardening method in Embodiment 2. FIG. It is a figure which shows the flow of the data in each process of induction hardening which concerns on Embodiment 2, and a command. FIG. 6 is a schematic diagram showing a configuration of induction tempering equipment used in the induction heat treatment method of Embodiment 3. It is a figure which shows the outline of the induction tempering method in Embodiment 3. FIG. It is a condition diagram which shows the relationship between the tempering temperature T and the tempering time t for obtaining predetermined | prescribed hardness after tempering. It is explanatory drawing which shows the relationship between the tempering temperature and the holding time for demonstrating the method of integrating | accumulating the value of the hardness after tempering from a temperature transition. It is a figure which shows the outline of a structure of the induction tempering installation in Embodiment 4. FIG. It is a figure which shows the outline of the induction tempering method in Embodiment 4. FIG. It is a figure which shows the flow of the data in each process of induction tempering which concerns on Embodiment 4, and instruction | command. It is a figure which shows the test result at the time of heating the rolling bearing outer ring made from JIS SUJ2. It is a figure which shows the test result at the time of heating the rolling bearing outer ring made from JIS SUS440C. It is a figure which shows the test result at the time of heating, after apply | coating the black body coating material on the surface to the rolling bearing outer ring made from JIS SUS440C.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 To-be-processed object (rolling bearing outer ring), 1A outer peripheral surface, 1B inner peripheral surface, 1C rolling surface, 2 Heating device, 3rd radiation thermometer, 4 Temperature control device, 5th Radiation thermometer, 6 Cooling timing Adjustment device, 7 Coolant injection device, 9 Stabilization layer, 10 Quenching and curing step, 11 Surface stabilization step, 12 Heating device, 13 First radiation thermometer, 14 Temperature adjustment device, 15 Second radiation thermometer, 16 Cooling timing adjustment device, 17 Coolant injection device, 20 Temperature control step, 22 Heating step, 23 Temperature control step for temperature control, 24 Temperature adjustment step, 30 Quenching control step, 35 Temperature measurement step for quenching, 36 Cooling timing Adjustment process, 37 Cooling process, 50, 51 Temperature control device, 60 Quenching control device, 61 Tempering control device, 70, 71 Storage device, 91, 92 Induction hardening equipment, 93, 94 Induction hardening Equipment.

Claims (8)

A high-frequency heat treatment method in which an object to be treated is heated and hardened by induction heating,
A surface stabilization step in which a stabilization layer having higher oxidation resistance than the object to be processed is formed on the surface of the object to be processed in a temperature range where the object to be processed is heated,
A quench hardening step in which the object on which the stabilization layer is formed is quenched and hardened in the surface stabilization step,
The quench hardening process includes
A temperature control step in which the temperature of the object to be processed on which the stabilization layer is formed is adjusted;
A quenching control step in which a timing at which the heated workpiece is to be cooled is determined, and the workpiece is cooled, and
The temperature control step includes
A temperature measuring step for temperature control in which the temperature of the surface of the stabilization layer formed on the surface of the workpiece is measured by a radiation thermometer;
A temperature adjustment step in which a temperature control signal for controlling the heating state of the object to be processed is output based on the temperature information measured in the temperature measurement temperature measurement step;
A heating step in which the workpiece is heated by the high-frequency heating based on the temperature control signal;
The quench control process includes
A quenching temperature measurement step in which the temperature of the surface of the stabilization layer formed on the surface of the object to be processed is measured by a radiation thermometer,
A cooling timing adjustment step in which a heating time is adjusted based on the temperature information measured in the quenching temperature measurement step, a timing at which the workpiece is to be cooled is determined, and a cooling start signal is output;
A high-frequency heat treatment method comprising: a cooling step in which the workpiece is quenched and hardened by cooling the workpiece based on the cooling start signal. A high-frequency heat treatment method in which an object to be treated is heated and hardened by induction heating,
A data acquisition step in which process data is acquired by heating and quenching the sample of the object to be processed;
Transition data of power output output from the power source for high frequency heating to the induction coil in order to heat the sample of the object to be processed in the data acquisition step, and cooling for specifying the cooling timing of the sample of the object to be processed A storage step in which timing data is stored as the process data;
Based on the material data of the workpiece that has been quenched and hardened in the data acquisition step, a confirmation step in which the validity of the transition data of the power output and the cooling timing data is confirmed;
A mass production process in which the workpiece is quenched and hardened according to the transition data of the power supply output and the cooling timing data which are stored in the storage process and validated in the confirmation process;
The induction hardening method according to claim 1, wherein the quench hardening in the data acquisition step is performed by the induction heat treatment method according to claim 1. A high-frequency heat treatment method for performing tempering by heating an object to be processed by high-frequency heating,
A surface stabilization step in which a stabilization layer having higher oxidation resistance than the object to be treated is formed on the surface of the object to be treated;
A tempering step in which the object on which the stabilization layer is formed in the surface stabilization step is heated and tempered.
The tempering step includes
A temperature control step in which the temperature of the workpiece is adjusted;
A tempering control step in which a timing at which heating of the workpiece is to be finished is determined and the workpiece is cooled, and
The temperature control step includes
A temperature measuring step for temperature control in which the temperature of the surface of the stabilization layer formed on the surface of the workpiece is measured by a radiation thermometer;
Based on the temperature information measured in the temperature control temperature measurement step, a temperature adjustment step for outputting a temperature control signal for controlling the heating state of the workpiece,
A heating step in which the workpiece is heated by the high-frequency heating based on the temperature control signal;
The tempering control step includes
A temperature measurement step for tempering in which the temperature of the surface of the stabilization layer formed on the surface of the workpiece is measured by a radiation thermometer,
A cooling timing adjustment step in which the heating time is adjusted based on the temperature information measured in the temperature measurement step for tempering, the timing at which the workpiece is to be cooled is determined, and a cooling start signal is output;
And a cooling step in which tempering of the object to be processed is completed by cooling the object to be processed based on the cooling start signal. A high-frequency heat treatment method for performing tempering by heating an object to be processed by high-frequency heating,
A data acquisition step in which process data is acquired by heating and tempering the sample of the workpiece;
Transition data of power output output from the power source for high frequency heating to the induction coil in order to heat the sample of the object to be processed in the data acquisition step, and cooling for specifying the cooling timing of the sample of the object to be processed A storage step in which timing data is stored as the process data;
Based on the material data of the object to be tempered in the data acquisition step, a confirmation step in which the validity of the power output transition data and the cooling timing data is confirmed;
A mass production process in which the workpiece is tempered in accordance with the transition data of the power output and the cooling timing data which are stored in the storage process and validated in the confirmation process;
The said tempering in the said data acquisition process is an induction heat treatment method implemented by the induction heat treatment method of Claim 3.   5. The high-frequency heat treatment method according to claim 1, wherein the surface stabilization step includes a black body paint application step in which a black body paint is applied to a surface of the object to be processed.   The surface stabilization step includes a thermal oxidation step in which an iron oxide layer is formed on the surface of the object to be processed by thermally oxidizing the object to be processed. The high-frequency heat treatment method described.   The surface stabilization step includes an acidic solution immersion step in which an iron oxide layer is formed on the surface of the object to be processed by immersing the object to be processed in an acidic solution. The high-frequency heat treatment method according to any one of the above.   A high-frequency heat-treated product produced by being heat-treated by the high-frequency heat treatment method according to any one of claims 1 to 7.

Images