JP2020193377A - High frequency quenching method and high frequency quenching device - Google Patents

Abstract

To provide a high frequency quenching method and a high frequency quenching device capable of improving accuracy of quality assurance.SOLUTION: A high frequency quenching method includes: a high frequency heating step S12 for high frequency heating of cam parts C1-C8 of a workpiece 11 which is a cast iron camshaft; a quenching step 14 for quenching the workpiece 11 by cooling the workpiece 11 by a coolant after the high frequency heating step S12; a stabilization step S15 for stabilizing the temperature of the quenched and hardened portions of the cam parts C1-C8 of the workpiece 11 by leaving the workpiece 11 as it is after the quenching step 14; and a first temperature determination step S24 for determining quality of the workpiece 11 after the quenching step 14. In the stabilization step S15, temperatures of the quenched and hardened portions of all the cam parts C1-C8 after the lapse of a predetermined time from the end of the quenching step 14 are measured as first temperatures. In the first temperature determination step S24, the quality of the workpiece 11 is determined to be good when the first temperatures are within a predetermined range.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to an induction hardening method and an induction hardening apparatus.

Conventionally, quality control in the manufacturing process of induction-hardened products is mainly performed by monitoring the condition system of induction heating and quenching and sampling inspection. However, due to equipment defects in the high-frequency heating device and / or cooling device (including deterioration of the heating coil condition and / or the function of the coolant), the heat pattern (heating and cooling temperature and speed) of the non-defective product deviates from the defective product. Sometimes. Then, there is a problem that the accuracy of quality assurance cannot be improved only by monitoring the condition system and sampling inspection.

Therefore, for example, in Patent Document 1, in a high-frequency quenching apparatus for a material to be heat-treated, the high-frequency heating temperature, the primary cooling temperature, and the secondary cooling temperature of the material to be heat-treated are detected for the purpose of stabilizing the quenching quality. It is disclosed that the high frequency heating device and the coolant control mechanism are stopped based on the temperature of the above.

Japanese Patent No. 2631749

The technique of Patent Document 1 is premised on detecting the temperature of the material to be heat-treated during high-frequency heating and the temperature of the material to be heat-treated during cooling by spraying a cooling liquid, which rises to about 900 ° C. However, for such a material to be heat-treated during high-frequency heating or cooling, there is a problem that it is difficult and impractical to accurately detect the temperature of the entire high-frequency heating portion.

Further, in the technique of Patent Document 1, for example, when the high frequency heating device and the coolant control mechanism are stopped by detecting the unstable temperature of a part of the heat-treated material, the other part of the heat-treated material is sufficient. Even if the high-frequency heating temperature or cooling temperature has not been reached, the next process may proceed. Then, there is a problem that it is difficult to guarantee the quenching quality of the entire material to be heat-treated.

An object of the present disclosure is to provide an induction hardening method and an induction hardening apparatus capable of improving the accuracy of quality assurance.

In order to solve the above problems, the high-frequency quenching method according to the first technique disclosed herein includes a high-frequency heating step of heating a plurality of predetermined parts of a cast iron shaft member at high frequencies, and cooling after the high-frequency heating steps. A quenching step of cooling the shaft member with an agent to quench the shaft member, and after the quenching step, the shaft member is left to stabilize the temperature of the hardened portion of the plurality of predetermined portions of the shaft member. The stabilization step of the process and a determination step of determining the quality of the shaft member after the quenching step are provided. In the stabilization step, all the plurality of predetermined items after a predetermined time has elapsed from the end of the quenching step. The temperature of the hardened portion of the hardened portion is measured as the first temperature, and in the determination step, when the first temperature is within a predetermined range, the quality of the shaft member is determined to be good.

When induction hardening is performed on a shaft member having a plurality of induction-hardened parts, the temperature of the quench-hardened portion of the plurality of predetermined parts of the shaft member becomes uniform, that is, stabilized after a lapse of a predetermined time after the quenching step. In this configuration, in the stabilization step of leaving the shaft member to stabilize after the quenching step, the temperature of the hardened portion of all the plurality of predetermined parts of the shaft member after a lapse of a predetermined time from the end of the quenching step is set to the first. Measure by temperature. Then, the quality of the shaft member is determined based on the first temperature. According to this configuration, since the stabilized first temperature of the hardened portion of a plurality of predetermined parts of the shaft member after the quenching step is measured, the temperature can be easily measured and the entire number of products can be easily checked. It is possible to improve the accuracy of quality assurance in induction hardening.

In the second technique, in the first technique, the predetermined time in the stabilization step is the time from the end of the quenching step to the start of stabilization of the temperature of the quenching and hardening portion of the plurality of predetermined portions of the shaft member. It is characterized by being.

According to this configuration, since the temperature is measured at the initial stage where the temperature of the hardened portion of a plurality of predetermined parts of the shaft member stabilizes after the quenching step, it is possible to accurately and easily determine the presence or absence of quench cracking and hardness defect. Can be done.

The third technique is characterized in that, in the first or second technique, the predetermined range of the first temperature is 150 ° C. or higher and 360 ° C. or lower.

If the first temperature is less than 150 ° C., shrinkage of the shaft member becomes a problem, and if it exceeds 360 ° C., poor hardness becomes a problem. According to this configuration, the accuracy of quality assurance can be further improved by determining that the quality of the shaft member is good when the first temperature is within the above range.

In any one of the first to third techniques, the fourth technique is to set the temperature of all the plurality of predetermined parts of the shaft member to the second temperature after the high frequency heating step and before the quenching step. A second temperature measuring step of measuring as, and an equipment evaluation step of evaluating the equipment state in the high frequency heating step and / or the quenching step based on the first temperature and / or the second temperature are provided. It is characterized by that.

According to this configuration, according to this configuration, the equipment state in the high frequency heating step and / or the cooling step is evaluated based on the first temperature and / or the second temperature, so that the apparatus used in these steps The equipment condition can be evaluated more accurately.

The fifth technique is characterized in that any one of the first to fourth techniques includes a sorting step of sorting the shaft member judged to be good or bad in the determination step according to the determination result. And.

According to this configuration, the shaft member judged to be good in the determination step can be advanced to the next stage such as shipping as a product. Further, the shaft member determined to be negative in the determination process can be utilized for evaluation of the equipment condition by verifying the cause.

A sixth technique is one of the first to fifth techniques, wherein the first temperature is measured by a thermal image measuring device that detects infrared rays emitted by the shaft member.

Since the thermal image measuring device measures the temperature of the object by detecting the infrared rays emitted from the object, the temperature of the hardened portion of a plurality of predetermined parts of the shaft member can be easily measured in a non-contact manner in a short time. Can be measured.

The seventh technique is any one of the first to sixth techniques, wherein the shaft member is a camshaft made of spheroidal graphite cast iron, and the plurality of predetermined portions are a plurality of cam portions. And.

According to this configuration, the quality assurance of the camshaft made of spheroidal graphite cast iron can be performed with high accuracy.

Eighth techniques include a high-frequency heating device that heats a plurality of predetermined parts of a cast iron shaft member at a high frequency, a cooling device that cools the heated shaft member with a coolant, and quenchs the shaft member. The temperature measuring device includes a temperature measuring device for measuring the temperature of the plurality of predetermined parts of the shaft member and a determination device for determining the quality of the shaft member, and the temperature measuring device is after a lapse of a predetermined time from the end of the quenching. The temperature of all the quenching and hardening portions of the plurality of predetermined parts is measured as the first temperature, and the determination device determines that the quality of the shaft member is good when the first temperature is within the predetermined range. It is characterized by.

According to this configuration, since the stabilized first temperature of the hardened portion of a plurality of predetermined parts of the shaft member after quenching is measured, it is easy to measure the temperature and to easily check the total number of products. It is possible to improve the accuracy of quality assurance in induction hardening.

The ninth technique is characterized in that, in the eighth technique, the predetermined time is the time from the end of the quenching to the start of stabilization of the temperature of the quenching and hardening portions of the plurality of predetermined portions of the shaft member. To do.

According to this configuration, since the temperature is measured at the initial stage where the temperature of the hardened portion of a plurality of predetermined parts of the shaft member stabilizes after quenching, it is possible to accurately and easily determine the presence or absence of quench cracking and hardness defect. it can.

The tenth technique is characterized in that, in the eighth or ninth technique, the predetermined range of the first temperature is 150 ° C. or higher and 360 ° C. or lower.

According to this configuration, the accuracy of quality assurance can be further improved by determining that the quality of the shaft member is good when the first temperature is within the above range.

The eleventh technique is any one of the eighth to tenth techniques, wherein the temperature measuring device measures the temperature of all the plurality of predetermined parts after high-frequency heating of the shaft member and before quenching as a second temperature. It is characterized by being provided with an equipment evaluation device that evaluates the equipment state in the high frequency heating device and / or the cooling device based on the first temperature and / or the second temperature.

According to this configuration, since the equipment state of the high frequency heating device and / or the cooling device is evaluated based on the first temperature and / or the second temperature, the equipment state of these devices can be evaluated more accurately. ..

The twelfth technique is characterized in that, in any one of the eighth to eleventh techniques, a sorting device for separating good products and defective products of the shaft member based on the judgment result of the judgment device is provided. To do.

According to this configuration, the shaft member determined to be a non-defective product by the determination device can be advanced to the next stage such as shipping as a product. In addition, the shaft member determined to be defective by the determination device can be used for evaluation of the equipment condition by verifying the cause.

The thirteenth technique is any one of the eighth to twelfth techniques, characterized in that the temperature measuring device is a thermal image measuring device that detects infrared rays emitted by the shaft member.

Since the thermal image measuring device measures the temperature of the object by detecting the infrared rays emitted from the object, the temperature of the hardened portion of a plurality of predetermined parts of the shaft member can be easily measured in a non-contact manner in a short time. Can be measured.

The fourteenth technique is any one of the eighth to thirteenth techniques, wherein the shaft member is a camshaft made of spheroidal graphite cast iron, and the plurality of predetermined portions are a plurality of cam portions. And.

According to this configuration, the quality assurance of the camshaft made of spheroidal graphite cast iron can be performed with high accuracy.

As described above, according to the present disclosure, since the stabilized first temperature of the hardened portion of a plurality of predetermined parts of the shaft member after the quenching step is measured, the temperature can be easily measured and the total number of products is increased. The check can be easily performed, and the accuracy of quality assurance in induction hardening can be improved.

It is a side view of the camshaft to be induction hardened. It is a figure which shows the structure of the induction hardening apparatus which concerns on one Embodiment. It is a graph which shows the temperature change of the 8th cam part in the camshaft of FIG. It is a flow chart which shows the process of the induction hardening method which concerns on one Embodiment, and the flow of information is shown by the arrow of the alternate long and short dash line. It is a flow chart which shows the process of the induction hardening method which concerns on another embodiment, and the flow of information is shown by the arrow of the alternate long and short dash line.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of preferred embodiments is merely exemplary and is not intended to limit the disclosure, its applications or its uses.

(Embodiment 1)
<Camshaft>
FIG. 1 shows a side view of a camshaft 11 (shaft member) which is a processing target of the induction hardening method and the apparatus according to the present embodiment.

The camshaft 11 is made of spheroidal graphite cast iron and is mounted on an in-line 4-cylinder engine of an automobile. As shown in FIG. 1, the camshaft 11 has eight cam portions (predetermined portions) indicated by reference numerals C1 to C8 and dot-shaped hatching. Since the cam portions C1 to C8 require high strength, they are target portions for high frequency quenching. The camshaft 11 includes a shaft portion D for connecting the cam portions C1 to C8. The shaft portion D is not a target portion for high frequency heating. Further, in the present specification, the camshaft 11 may be referred to as a "work 11".

The shaft member to be treated by the induction hardening method and the apparatus according to the present embodiment may be a cast iron shaft member having a plurality of predetermined parts requiring induction hardening, and is used for an in-line 4-cylinder engine of an automobile. Not limited to camshafts. Specifically, for example, it may be a camshaft for other multi-cylinder engines, an engine for vehicles other than automobiles, an industrial engine, or the like. Further, the camshaft is not limited to the camshaft, and a balancer shaft or the like may be used.

<Induction hardening equipment>
FIG. 2 is a diagram showing an outline of the configuration of the induction hardening apparatus 100 according to the present embodiment.

The induction hardening device 100 includes a high frequency heating device 110, a cooling device 120, a temperature measuring device 130, a sorting device 140, a control device 150, and a transfer device (not shown).

-High frequency heating device-
The high frequency heating device 110 is a device for performing high frequency heating on the eight cam portions C1 to C8 of the cam shaft 11. The high-frequency heating device 110 is not particularly limited, and a known device used in general induction hardening can be used.

-Cooling device-
The cooling device 120 is a device for rapidly cooling and quenching the camshaft 11, particularly the cam portions C1 to C8, by a method such as spraying a coolant on the camshaft 11 heated at a high frequency. The cooling device 120 is not particularly limited, and a known device used in general induction hardening can be used. As the coolant, a coolant generally used in induction hardening can be used, and specifically, for example, a coolant such as water can be used.

-Temperature measuring device-
The temperature measuring device 130 is a device for measuring the temperature of a plurality of cam parts among the eight cam parts C1 to C8 of the camshaft 11, and preferably for measuring the temperature of all the cam parts C1 to C8. It is a device of. Since the temperatures of the plurality of cam portions are measured, the accuracy of quality assurance of the work 11 can be improved. Further, by measuring the temperatures of all the cam portions C1 to C8, the accuracy of quality assurance of the work 11 can be effectively improved. It is desirable that the device can measure all the temperatures of a plurality of cam portions or cam portions C1 to C8 at the same timing as much as possible. Specific examples of the temperature measuring device 130 include a radiation thermometer, a thermal image measuring device, and the like, and it is preferable to use the thermal image measuring device. When using a radiation thermometer, for example, the temperature of each of a plurality of cam parts may be measured at the same timing as much as possible by using radiation thermometers for the number of cam parts to be measured. .. The number of radiation thermometers can be appropriately changed depending on the configuration of the shaft member, particularly the number of predetermined parts to be induction hardened. A thermal image measuring device is a device that measures the temperature of an object by detecting infrared rays emitted from the object. By using the thermal image measuring device, the temperature of the entire camshaft 11 including the cam portions C1 to C8 can be easily measured in an extremely short time, that is, at substantially the same timing by detecting the infrared rays emitted by the camshaft 11.

In the following description of the induction hardening method, it is assumed that the temperatures of all the cam portions C1 to C8 are measured in order to facilitate understanding.

-Separator-
The sorting device 140 is a device for separating non-defective products and defective products of the camshaft 11 determined by the determination unit 152 described later of the control device 150. Specifically, for example, an apparatus can be adopted in which a non-defective product and a defective product are stamped with a determination result and the two are separated into separate sorting boxes. That is, the sorting device 140 may be composed of a combination of a known carrier that conveys the camshaft 11, a known marking machine that performs marking, a known sorting machine that performs sorting based on the marking, a sorting box, and the like. Specifically, for example, a conveyor can be a general belt conveyor device or the like, a stamping machine can be a general laser stamping machine or the like, and a sorting machine can be a known sorting machine equipped with a sensor or the like for reading a stamp. ..

-Control device-
The control device 150 is communicably connected to the high-frequency heating device 110, the cooling device 120, the temperature measuring device 130, and the sorting device 140, and is a device for controlling and managing the entire induction hardening process described later. The control device 150 includes a storage unit 151, a determination unit 152 (determination device), and a control unit 153. The control device 150 is composed of a general-purpose computer, a network server, and the like, although it is not intended to be limited. Further, the control device 150 includes a display unit, an input unit, and the like (not shown). The display unit and the input unit are not intended to be limited, but are composed of a monitor, a keyboard, a touch panel, and the like. Details of the control device 150 and each part thereof will be described in the item of induction hardening method described later.

-Conveyor-
Although not shown in FIG. 2, the induction hardening device 100 is provided with a transfer device for carrying in / out the camshaft 11 to each of the above-mentioned devices. The transport device is not intended to be limited, but a known device such as a loader can be adopted.

<Induction hardening method>
The induction hardening method according to this embodiment will be described mainly with reference to FIGS. 2 to 4.

As shown in FIG. 4, the high-frequency quenching method includes a preparation step S11, a high-frequency heating step S12, a heating condition determination step S21, a standby step S13, a quenching step S14, a cooling condition determination step S23, and a stabilization step. It includes S15, a first temperature determination step S24 (determination step), and a sorting step S16.

-Preparation process-
In the preparation step S11, the work 11 is carried into the induction hardening apparatus 100. The control device 150 acquires work information such as identification code information, model information, and temperature condition information of the work 11. The work information is recorded in the storage unit 151 (S31). The control unit 153 collates the read work information with the information recorded in advance in the storage unit 151, reads out the high-frequency heating condition and the quenching condition corresponding to the work 11 from the storage unit 151, and reads the high-frequency heating device 110 and the cooling. It is set as each operating condition of the device 120. In addition, each condition corresponding to the work 11 may be set by another method such as inputting from the input unit by the operator.

-High frequency heating process-
The high-frequency heating step S12 is a step of performing high-frequency heating of the eight cam portions C1 to C8 of the work 11 by the high-frequency heating device 110.

Specifically, as shown by arrow A1 in FIG. 2, the work 11 is carried into the high-frequency heating device 110 by a transfer device (not shown). Then, high frequency heating is performed according to the high frequency heating conditions set by the control unit 153. The cast iron structure from the surface of the cam portions C1 to C8 to a certain depth is austenitized by high frequency heating. The heating temperature is a temperature at which the cast iron structure is austenitized, for example, about 900 ° C. to about 1100 ° C. The heating time is the time used in general induction hardening, and can be, for example, about 10 seconds. When the high-frequency heating step S12 is completed, the work 11 is carried out of the high-frequency heating device 110 by the transfer device as shown by the arrow A2 in FIG.

The conditions of high-frequency heating actually performed in the high-frequency heating step S12 are recorded in the storage unit 151 as heating condition actual information (S32).

-Heating condition determination process-
The determination unit 152 makes an OK / NG determination of the actual heating condition information (heating condition determination step S21). For example, if the actual heating condition information is valid in comparison with the preset high-frequency heating conditions, it is determined to be OK. On the other hand, if the actual heating condition information greatly deviates from the preset high-frequency heating conditions due to factors such as equipment failure, it is determined to be NG. The criteria for OK / NG determination are appropriately set according to the specifications of the work 11 and the specifications of the apparatus. The result of this OK / NG determination is recorded in the storage unit 151 (S33).

-Standby process-
The work 11 carried out from the high-frequency heating device 110 stands by, for example, in the atmosphere for about several seconds in preparation for proceeding to the next quenching step S14 (standby step S13).

-Quenching process-
The work 11 carried out from the high-frequency heating device 110 is carried into the cooling device 120 as shown by an arrow A3 in FIG. Then, the coolant is sprayed on the work 11, and rapid cooling, that is, quenching is performed (quenching step S14). When quenching is performed, the cast iron structure that has been austenitized by high-frequency heating becomes martensite. In the present specification, the martensitic portion from the surface of the cam portions C1 to C8 to a certain depth is referred to as a "quenched hardened portion". Quenching conditions such as the temperature of the coolant and the spraying time are conditions in which the cam portions C1 to C8 of the work 11 can be cooled to a temperature at which the cast iron structure becomes martensite. When the quenching step S14 is completed, the work 11 is carried out from the cooling device 120 as shown by the arrow A4 in FIG.

The quenching conditions actually performed in the quenching step S14 are recorded in the storage unit 151 as cooling condition actual information (S36).

-Cooling condition determination process-
In the cooling condition determination step S23, the determination unit 152 makes an OK / NG determination of the cooling condition actual information. For example, if the cooling condition actual information is valid in comparison with the preset quenching conditions, it is determined to be OK. On the other hand, if the cooling condition actual information greatly deviates from the preset quenching conditions due to factors such as equipment failure, it is determined to be NG. The criteria for OK / NG determination are appropriately set according to the work information of the work 11, the specifications of the apparatus, and the like. The result of this OK / NG determination is recorded in the storage unit 151 (S37).

-Stabilization process-
The stabilization step S15 is a step of leaving the work 11 in the air to stabilize its temperature after the quenching step S14, that is, after carrying it out from the cooling device 120.

Here, in the induction hardening method according to the present embodiment, in the stabilization step S15, the temperature measuring device 130 sets the temperature of all the quenching and hardening portions of the cam portions C1 to C8 after a lapse of a predetermined time from the end of the quenching step S14. It is characterized in that it is measured as one temperature. Hereinafter, the details of the stabilization step S15 and the measurement of the first temperature will be described.

First, the work 11 carried out from the cooling device 120 is left as it is in the atmosphere for a certain period of time (stabilization step S15).

Here, the temperature change of the work 11 from the high frequency heating step S12 to the stabilization step S15 will be described with reference to FIG.

The graph of FIG. 3 is a plot of the temperature from the high frequency heating step S12 to the stabilization step S15 by welding a commercially available chromel alumel thermocouple to the cam portion C8 (see FIG. 1) of the work 11 for verification. Is.

As shown in FIG. 3, when high frequency heating is performed in the high frequency heating step S12, the temperature of the cam portion C8 gradually increases to about 1040 ° C. Then, the heating is completed at the time indicated by the arrow B1, and the work 11 is carried out from the high-frequency heating device 110 (see arrow A2 in FIG. 2).

Then, in the standby step S13 from the time of arrow B1 to the time of arrow B2 in FIG. 3, the temperature of the cam portion C8 drops by about 100 ° C.

After that, the work 11 is conveyed into the cooling device 120 (see arrow A3 in FIG. 2), water as a cooling agent starts to be sprayed from the time indicated by arrow B2 in FIG. 3, and the temperature of the cam portion C8 drops sharply. While the coolant is sprayed on the work 11, the temperature of the cam portion C8 fluctuates finely. Then, as shown by arrow B3, when the spraying of the coolant is completed and the work 11 is carried out from the cooling device 120 (see arrow A4 in FIG. 2), the temperature of the quench-hardened portion of the cam portion C8 gradually increases. It rises and eventually stabilizes at a constant temperature. In the temperature rise and stabilization after the time of reference numeral B3 in FIG. 3, the temperature of the cam portion C8 of the work 11 is restored by leaving the work 11 in the atmosphere, that is, the cam portion C8 of the work 11 is hardened. It shows how the temperature inside and on the surface of the cured part is uniform. The temperature fluctuates finely for about 8 seconds from the reference numeral B3 in FIG. 3, and it is considered that this is related to the evaporation of water of the coolant adhering to the work 11.

By verifying the heat pattern of the non-defective product and the heat pattern of the defective product of the work 11 as shown in FIG. 3, the inventors of the present application have verified the temperature in the reheated and stabilized state, that is, the arrow P1 in FIG. It has been found that the temperature after the time indicated by (the present specification may be referred to as "first temperature") falls within a predetermined range for a non-defective product and deviates from the predetermined range for a defective product. Further, the inventors of the present application set the time from the unloading from the cooling device 120 (the end of the quenching step S14) to the start of reaching the first temperature (from the time of arrow B3 to the time of arrow P1 in FIG. 3) of the work 11. It was found that if the specifications of are the same, they are almost constant.

The time required to start reaching the first temperature can be determined by experimentally acquiring the heat pattern of a good product of the work 11 in advance. Then, in the stabilization step S15, the temperature of the quench-hardened portion of the cam portions C1 to C8 after the elapse of a predetermined time is measured as the first temperature, and whether or not the first temperature is within the predetermined range is determined for all the works 11. By verifying in, the quality of the work 11 can be judged for all of them.

Therefore, in the stabilization step S15 of the induction hardening method according to the present embodiment, the temperature measuring device 130 sets the temperature of all the quench-hardened portions of the cam portions C1 to C8 after a lapse of a predetermined time from the end of the quenching step S14 to the first temperature. Measure as. Then, in the next first temperature determination step S24, the quality of the work 11 is determined based on the first temperature. The first temperature measured in the stabilization step S15 is recorded in the storage unit 151 as the first temperature information (S38).

The predetermined time is the time from when the work 11 is taken out from the cooling device 120 until the temperature of the quenching and hardening parts of the cam parts C1 to C8 of the work 11 stabilizes (time from arrow B3 to arrow P1 and after in FIG. 3). ). Then, for a predetermined time, from the viewpoint of accurately and easily determining the presence or absence of shrinkage and hardness failure, preferably, after the work 11 is carried out from the cooling device 120, the quenching and hardening portions of the cam portions C1 to C8 of the work 11 are used. It is the time until the temperature of the above starts to stabilize (the time from the arrow B3 to the arrow P1 in FIG. 3). In the present specification, the time at which the temperature of the work 11 indicated by the arrow P1 in FIG. 3 begins to stabilize is after the fine temperature change due to the evaporation of water in the work 11 is completed and the temperature starts to rise smoothly. The time change rate of the temperature can be set to, for example, 1 or less, preferably 0.7 or less. Specifically, the predetermined time is, for example, 1 second or more and 60 seconds or less, preferably 2 seconds or more and 20 seconds or less.

-First temperature determination process-
The first temperature determination step S24 is a step in which the determination unit 152 of the control device 150 determines the quality of the work 11 based on the above-mentioned first temperature.

Specifically, for example, the determination unit 152 determines that the first temperature is OK when the first temperature is within the predetermined range, and determines the first temperature when the first temperature is outside the predetermined range. Judged as NG. Then, when the first temperature is determined to be OK, the quality of the work 11 is determined to be non-defective. Further, when the first temperature is determined to be NG, the quality of the work 11 is determined to be defective.

As shown by the alternate long and short dash line in FIG. 3, the predetermined range of the first temperature is preferably 150 ° C. or higher and 360 ° C. or lower, and more preferably 180 ° C. or higher and 330 ° C. or lower. If the first temperature is less than 150 ° C., quench cracking of the work 11 due to excessive cooling in the quenching step S14 becomes a problem. Further, when the first temperature exceeds 360 ° C., poor hardness of the cam portions C1 to C8 due to insufficient cooling in the quenching step S14 becomes a problem.

The OK / NG determination result of the first temperature in the first temperature determination step S24 is the same as the result of the quality determination of the work 11, and the result of the quality determination of the work 11 is used as the first temperature determination information. It is recorded in the storage unit 151 (S39).

-Separation process-
The work 11 determined to be a non-defective product or a defective product in the first temperature determination step S24 is separated by the above-mentioned sorting device 140 according to the determination result (separation step S16).

Specifically, for example, first, the work 11 that has completed the stabilization step S15 is carried into the sorting device 140 by a transfer device (not shown). Then, for example, the identification code information, the heating condition determination information, the cooling condition determination information, and the first temperature determination information of the work information stored in the storage unit 151 are imprinted on the work 11 by a laser engraving machine or the like (S161). Then, the non-defective product is sorted into the finished pallet (S162), while the defective product is sorted into the defective product box (S163). In this way, the induction hardening work of the work 11 is completed. The marking is performed on both non-defective products and defective products. As a result, it is possible to improve the accuracy of quality assurance of non-defective products and prevent defective products from being mixed into non-defective products when they are sorted. Good products will proceed to the next stage such as shipping as products with guaranteed quality. On the other hand, defective products are used for verification of the cause and used for evaluation of equipment condition.

<Summary>
As described above, the induction hardening method and apparatus according to the present embodiment measure the first temperature in the stabilization step S15 and determine the quality of the work 11 based on the first temperature. Therefore, the temperature is measured. It is easy and highly accurate, and 100% of products can be easily checked. In this way, the accuracy of quality assurance in induction hardening can be improved.

The work information, heating condition actual information, heating condition determination information, cooling condition actual information, cooling condition determination information, first temperature information, and first temperature determination information recorded in the storage unit 151 are used together with other necessary information. It is linked and saved, and traceability is managed. As a result, the accuracy of quality control for guaranteeing the total number of camshafts 11 can be improved.

(Embodiment 2)
Hereinafter, other embodiments according to the present disclosure will be described in detail. In the description of these embodiments, the same parts as those of the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

<Induction hardening method>
FIG. 5 is a flow showing the steps of the induction hardening method according to the second embodiment.

-Standby process-
The induction hardening method of the first embodiment has a configuration in which the standby step S13 is provided after the induction heating step S12 and before the quenching step S14. In the induction hardening method according to the present embodiment, the temperature of the cam portions C1 to C8 of the work 11 is measured in the standby step S13 (second temperature measuring step).

Specifically, as shown by the arrow P2 in FIG. 3, all the cam portions C1 to C8 of the work 11 are carried out from the high-frequency heating device 110 to the cooling device 120. The temperature is measured by the temperature measuring device 130 as the second temperature. The measured second temperature is recorded in the storage unit 151 of the control device 150 as the second temperature information (S34).

-Second temperature determination process-
Then, in the second temperature determination step S22 (equipment evaluation step), the determination unit 152 (equipment evaluation device) makes an OK / NG determination as to whether or not the second temperature is within a reasonable temperature range.

The heat pattern of a non-defective product of the work 11 as shown in FIG. 3 is generally determined by the specifications of the work 11, the specifications of the device, and the like if there is no problem in the equipment state of the high-frequency heating device 110. Therefore, the second temperature, like the first temperature, falls within a certain temperature range for non-defective products. Therefore, if the second temperature is included in the predicted reasonable temperature range, the OK determination can be performed, and if the second temperature is outside the predicted reasonable temperature range, the NG determination can be performed. In the case of OK determination, the work 11 proceeds to the next quenching step S14 as it is. On the other hand, in the case of NG determination, for example, the operation of the entire induction hardening apparatus 100 can be stopped as an error of the induction heating apparatus 110. As a result, the high frequency heating device 110 can be inspected. In this way, in the second temperature determination step S22, the equipment state of the high frequency heating device 110 can be evaluated according to the determination result. The reasonable temperature range of the second temperature can be, for example, about 850 ° C to about 1050 ° C.

The result of the OK / NG determination of the second temperature is also recorded in the storage unit 151 as the second temperature determination information (S35). The second temperature information and the second temperature determination information are also stored in association with each other together with the above information, and traceability management is performed.

-First temperature determination process-
In the first embodiment, in the first temperature determination step S24, the determination unit 152 determines whether the quality of the work 11 is good or bad depending on whether or not the first temperature is included in the predetermined range. On the other hand, in the first temperature determination step S24 (equipment evaluation step) according to the present embodiment, in addition to the quality determination of the work 11 using the first temperature by the determination unit 152 (equipment evaluation device), the first Equipment evaluation of the cooling device 120 using one temperature may also be performed.

Specifically, as described above, the determination unit 152 makes an OK determination when the first temperature is within a predetermined range. On the other hand, if the first temperature is outside the predetermined range, an NG determination is performed. Then, the work 11 is separated into a non-defective product and a defective product in the sorting step S16 based on the result of the OK / NG determination of the first temperature. Further, when the NG determination is made for the first temperature, that is, when the first temperature is NG determination even though the second temperature is OK determination in the second temperature determination step S22, the cooling device 120 It is highly probable that there is a problem with the equipment condition of. Therefore, in this case, for example, the operation of the entire induction hardening device 100 can be stopped to check the equipment state of the cooling device 120.

-Separation process-
In the marking step S161 of the sorting step S16, in addition to the above information, the second temperature determination information is also stamped on the work 11. Then, the work 11 whose first temperature is determined to be OK is classified as a good product, and the work 11 whose first temperature is determined to be NG is classified as a defective product.

<Summary>
As described above, in the induction hardening method according to the present embodiment, it is possible to first evaluate the equipment state of the induction heating device 110 based on the second temperature. Then, when the second temperature is OK, the equipment state of the cooling device 120 can be evaluated based on the first temperature. According to this configuration, it is possible to diligently check the equipment status of the high-frequency heating device 110 and the cooling device 120, and to promptly inspect these devices when an error occurs. As a result, the yield of the camshaft 11 can be increased, and the accuracy of quality assurance thereof can be effectively increased.

(Other embodiments)
In the second embodiment, when the second temperature is determined to be NG, and when the first temperature is determined to be NG even though the second temperature is OK, the operation of the entire induction hardening apparatus 100 is performed due to an error. It was a configuration to stop, but it is not limited to this configuration. Specifically, for example, even if an NG determination is made at the first temperature or the second temperature, the operation of the entire induction hardening apparatus 100 may be continued. For example, when the second temperature is OK and the first temperature is NG, the second temperature measured is OK as a result of intermittent high-frequency heating due to a malfunction of the high-frequency heating device 110, but actually. It can be assumed that the high frequency heating is insufficient and the first temperature is determined to be NG. In such a case, it is effective to evaluate the equipment state of both the high-frequency heating device 110 and the cooling device 120 and verify the cause based on the determination results of both the first temperature and the second temperature. Therefore, in such a case, it is effective to have a configuration that does not stop the operation of the entire induction hardening apparatus 100 even when the NG determination is made at the first temperature or the second temperature.

In the second embodiment, the quality of the work 11 is judged based only on the first temperature, but the work 11 is judged based on the OK / NG judgment result of the second temperature in addition to the first temperature. The quality may be judged. In this case, in the sorting step S16, if only the work 11 that is determined to be OK for both the first temperature and the second temperature is a good product, and at least one of the first temperature and the second temperature is NG, it is determined and stamped as a defective product. And separated. Since there is a high possibility that the work 11 whose second temperature is determined to be NG is a defective product when the high-frequency heating step S12 is completed, all the work 11 should be stamped and sorted as a defective product regardless of the determination result of the first temperature. It may be. In this way, by determining the quality of the work 11 using the second temperature in addition to the first temperature, it is possible to more accurately confirm whether the heat history of the work 11 follows the heat pattern of a good product. And the accuracy of quality assurance can be further improved.

The present disclosure is extremely useful in the fields of induction hardening methods and induction hardening devices.

11 Camshaft, work (shaft member)
100 Induction hardening device 110 High frequency heating device 120 Cooling device 130 Temperature measuring device 140 Separation device 150 Control device 151 Storage unit 152 Judgment unit (judgment device, equipment evaluation device)
153 Control unit C1 to C8 Cam unit (predetermined part)
S12 High frequency heating process S13 Standby process (second temperature measurement process)
S14 Quenching process S15 Stabilization process S16 Separation process S22 Second temperature determination process S24 First temperature determination process (determination process)

Claims (14)

A high-frequency heating process that heats a plurality of predetermined parts of a cast iron shaft member at high frequencies,
After the high-frequency heating step, a quenching step of cooling the shaft member with a coolant and quenching the shaft member is performed.
After the quenching step, a stabilizing step of leaving the shaft member to stabilize the temperature of the quenching and hardening portion of the plurality of predetermined portions of the shaft member, and
A determination step for determining the quality of the shaft member after the quenching step is provided.
In the stabilization step, the temperature of the quenching and hardening part of all the plurality of predetermined parts after a lapse of a predetermined time from the end of the quenching step is measured as the first temperature.
An induction hardening method characterized in that, in the determination step, the quality of the shaft member is determined to be good when the first temperature is within a predetermined range. In claim 1,
The induction hardening method, characterized in that the predetermined time in the stabilization step is the time from the end of the quenching step to the start of stabilization of the temperature of the quench-hardened portion of the plurality of predetermined portions of the shaft member. In claim 1 or 2,
An induction hardening method characterized in that the predetermined range of the first temperature is 150 ° C. or higher and 360 ° C. or lower. In any one of claims 1 to 3,
A second temperature measuring step of measuring the temperature of all the plurality of predetermined parts of the shaft member as a second temperature after the high frequency heating step and before the quenching step.
A high-frequency hardening method comprising: a high-frequency heating step and / or an equipment evaluation step for evaluating an equipment state in the quenching step based on the first temperature and / or the second temperature. In any one of claims 1 to 4,
An induction hardening method comprising a sorting step of sorting the shaft member judged to be good or bad in the determination step according to the judgment result. In any one of claims 1 to 5,
The first temperature is an induction hardening method characterized in that it is measured by a thermal image measuring device that detects infrared rays emitted by the shaft member. In any one of claims 1 to 6,
The shaft member is a camshaft made of spheroidal graphite cast iron.
An induction hardening device characterized in that the plurality of predetermined portions are a plurality of cam portions. A high-frequency heating device that heats a plurality of predetermined parts of a cast iron shaft member at high frequencies,
A cooling device that cools the heated shaft member with a coolant to quench the shaft member, and
A temperature measuring device for measuring the temperature of the plurality of predetermined parts of the shaft member, and
It is equipped with a determination device for determining the quality of the shaft member.
The temperature measuring device measures the temperature of all the quenching and curing portions of the plurality of predetermined portions after a lapse of a predetermined time from the end of the quenching as a first temperature.
The determination device is an induction hardening device characterized in that the quality of the shaft member is determined to be good when the first temperature is within a predetermined range. In claim 8.
The induction hardening apparatus, characterized in that the predetermined time is the time from the end of the quenching to the start of stabilization of the temperature of the quenching hardened portion of the plurality of predetermined portions of the shaft member. In claim 8 or 9,
An induction hardening apparatus characterized in that the predetermined range of the first temperature is 150 ° C. or higher and 360 ° C. or lower. In any one of claims 8 to 10,
The temperature measuring device measures the temperatures of all the plurality of predetermined parts after high-frequency heating of the shaft member and before quenching as a second temperature.
An induction hardening apparatus comprising: an induction hardening apparatus for evaluating an equipment state in the high frequency heating apparatus and / or the cooling apparatus based on the first temperature and / or the second temperature. In any one of claims 8 to 11.
An induction hardening device including a sorting device that separates non-defective products and defective products of the shaft member based on the determination result of the determination device. In any one of claims 8 to 12,
The temperature measuring device is an induction hardening device characterized by being a thermal image measuring device that detects infrared rays emitted by the shaft member. In any one of claims 8 to 13,
The shaft member is a camshaft made of spheroidal graphite cast iron.
An induction hardening device characterized in that the plurality of predetermined portions are a plurality of cam portions.

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