JP2006291247A - Heat treatment method, method for producing thin member for bearing, thin member for bearing and thrust bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment method by which the severe quality assurance can be obtained while suppressing an increase in the production cost, and deformation developed at the hardening time can be restrained. <P>SOLUTION: The heat treatment method includes; a quenching-hardening process having a heating process for heating a material to be treated to a temperature of ≥A<SB>c1</SB>point and a cooling process for cooling the material to be treated, heated to the temperature of A<SB>c1</SB>point in the heating process to a temperature of ≤M<SB>s</SB>point; and a quality judging process, performed after quench-hardening process and judging the quality of the material to be treated. The heating in the heating process is performed by induction-heating and cooling in the cooling process is performed while restricting the material to be treated by using a die. Further, the cooling is performed by using the die as the cooling member for removing the heat from the material to be treated so as to cool the material to be treated from the temperature of ≥A<SB>c1</SB>point to the temperature of M<SB>s</SB>point. The judgement of the quality in the quality judging process, is performed by using an automatic quality judging means for automatically judging the quality. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a heat treatment method, a method for manufacturing a thin member for a bearing, a thin member for a bearing, and a thrust bearing, and more specifically, a heating step of heating an object to be processed to a temperature of _{Ac 1} point or higher, a quench hardening step having a cooling step of cooling the workpiece heated to a temperature not lower than the _Ms point to a temperature not higher than the M _s point, and a material of the workpiece to be processed after the quench hardening step. A heat treatment method including a material determination step, a method for manufacturing a thin member for a bearing including a heat treatment step using the heat treatment method, a thin member for a bearing manufactured by the manufacturing method, and the thin member for a bearing The present invention relates to a thrust bearing.

  In general, a thin bearing race which is a thin member for a bearing employs SPCC (defined in JIS G3141), SCM415 (defined in JIS G4053), etc., which are low-carbon steel as a material. And after these raw materials are shape | molded in a required shape, it hardens by hardening after performing a short-time carburizing process, and the hardness required as a bearing ring is ensured. Further, high carbon steel such as SUJ2 (specified in JIS G4805), SAE1070, etc. may be adopted as a material. In this case, after these materials are formed into a required shape, they are quenched and hardened by being heated in an atmospheric furnace and then quenched to ensure the necessary hardness for the race.

  From the viewpoint of efficient operation of the heat treatment furnace and the quenching apparatus, the quench hardening process is performed by a batch process in which a certain amount of workpieces (orbital rings) are heat treated as one lot. And the heat treatment quality such as hardness and microstructure after quench hardening of the raceway is assured by sampling inspection carried out by extracting a small number of samples from one lot and investigating the quality.

  Moreover, in the quench hardening of the raceway, induction hardening in which quenching is performed by induction heating may be employed. Even in this case, the quality of the heat treatment is guaranteed by sampling inspection from the viewpoint of ensuring productivity.

  In recent years, automobiles and other products that use bearings with thin-walled bearing rings have become increasingly sophisticated and functional. Under such circumstances, strict quality assurance is required for bearing surface hardness and surface scratches. In addition, price reduction is an important issue from the viewpoint of improving price competitiveness.

  Under such circumstances, a method for determining whether induction hardening has been normally performed (for example, see Patent Documents 1 and 2), a method for efficiently performing induction hardening (for example, see Patent Documents 3 and 4). ), An apparatus (for example, see Patent Document 5) for measuring the quenching depth of the induction-hardened work has been proposed.

  On the other hand, thin bearing rings for bearings used in bearings are likely to be deformed during quenching in the manufacturing process. When the deformation of the bearing ring is large, the life of the bearing provided with the bearing ring is reduced.

On the other hand, as a method for suppressing deformation of the steel material when quenching the steel material, a method of setting the scale thickness of the steel plate surface when press quenching the steel plate to 10 μm or less has been proposed. Thereby, a molded part with good shape accuracy can be manufactured (see, for example, Patent Document 6). Moreover, in the press hardening method of steel materials, the method of immersing in a cooling fluid in the state which restrained steel materials using the metal mold | die is proposed (for example, refer patent document 7). Thereby, the deformation | transformation and bending which generate | occur | produce in the case of hardening can be reduced also in high hardness steel materials. In addition, there has been proposed a method of quenching by constraining the outer diameter of the thin ring and the end face in the width direction with a collet (constraining member). Thereby, the deformation | transformation which generate | occur | produces in the case of quenching is suppressed (for example, refer patent document 8).
JP 11-31579 A Japanese Patent Laid-Open No. 9-118917 JP-A-9-31532 Japanese Patent Laid-Open No. 5-263125 JP 2004-177159 A JP 2003-231915 A JP-A-7-157822 JP-A-5-33060

  Although the improvement measures related to the heat treatment disclosed in Patent Documents 1 to 5 contribute to quality improvement and cost reduction of the workpiece, the quality of the workpiece is not guaranteed. In order to perform strict quality assurance on the workpieces, it is ideal to inspect the surface hardness and scratches of each workpiece. However, when all the objects to be processed are inspected by the conventional method in the production line, the production efficiency is lowered, resulting in an increase in cost. This is contrary to the aforementioned demand for lower prices.

  Even when a bearing is manufactured by applying the method disclosed in Patent Documents 6 to 8 for suppressing deformation generated during quenching to a thin-walled bearing member for bearings, the bearing is considered in view of recent high required characteristics. The lifetime of is not always sufficient. Furthermore, bearings are required to have high reliability supported by strict quality assurance.

  Accordingly, an object of the present invention is to provide a heat treatment method that enables strict quality assurance while suppressing an increase in manufacturing cost and that can suppress deformation that occurs during quenching. Another object of the present invention is for a bearing capable of manufacturing a thin-walled member for a bearing that enables strict quality assurance while suppressing an increase in manufacturing cost and that suppresses deformation that occurs during quenching. It is providing the manufacturing method of a thin member. Still another object of the present invention is to provide a thin member for a bearing that enables strict quality assurance while suppressing an increase in manufacturing cost and that suppresses deformation that occurs during quenching. Still another object of the present invention is to provide a thrust bearing having a long life and high reliability at a low cost.

Heat treatment method according to the invention, the object and the step of heating to a temperature above A _c1 point, the workpiece which has been heated to a temperature equal to or higher than A _c1 point in the heating step to a temperature below M _s point It is a heat treatment method including a quench hardening step having a cooling step for cooling, and a material determination step that is performed after the quench hardening step and determines the material of the workpiece. Heating in the heating process is performed by induction heating, and cooling in the cooling process is performed while restraining an object to be processed using a mold. The cooling by the use of a mold as a cooling member for removing heat from the object to be treated is carried out by cooling the object to be treated from a temperature above A _c1 point to M _s point or lower. Furthermore, the material determination in the material determination step is performed using automatic material determination means that automatically determines the material.

  According to the heat treatment method of the present invention, cooling is performed while restraining the object to be processed using a mold in the cooling process, so that deformation of the object to be processed that occurs in the quench hardening process can be suppressed.

In addition, carburizing furnaces and atmosphere furnaces that are widely used for quench hardening treatment generally have a processing line, because the equipment is relatively large and gas for adjusting the atmosphere is used. Are arranged separately. On the other hand, according to the heat treatment method of the present invention, since a relatively small-scale facility using induction heating can be used, it is easy to incorporate the quench hardening facility into the processing line (in-line). Further, by cooling the quench-hardening process using the above mold as a cooling member for removing heat from the object to be processed, the object to be treated a cooling from a temperature above A _c1 point to M _s point below the temperature It is carried out by doing. Accordingly, since it is not necessary to bring oil or water into contact with the object to be processed as a cooling medium, the material determination using the automatic material determining means can be performed without providing a process for cleaning and drying the object to be processed. In addition, the above heat treatment can heat each object to be processed one by one without greatly impairing the processing efficiency. Therefore, the material determination can be smoothly performed for all the objects to be processed by sequentially determining the material for the heat-treated objects. As a result of the above characteristics, according to the heat treatment method of the present invention, it is possible to smoothly perform the processes from quench hardening to quality judgment for quality assurance without generating work in progress. Therefore, it is easy to automate. Therefore, it is possible to provide a heat treatment method that guarantees the quality of each object to be processed while suppressing the heat treatment cost of the object to be processed.

The _Ac1 point means a point corresponding to a temperature at which the steel starts to transform from ferrite to austenite when the steel is continuously heated. Further, the M _s point means a point corresponding to a temperature at which martensite formation starts when the austenitized steel is cooled. The automatic material determination means may be any means that can evaluate the characteristics corresponding to the hardness, microstructure, etc., which are the material changes of the object to be processed by quench hardening. For example, a micro hardness meter, a material discriminator (ultrasonic hardness meter), an eddy current flaw detector, a thermoelectromotive force type foreign material discriminator, a Barkhausen noise measuring device, an X-ray diffractometer and the like can be mentioned. However, it is preferable that evaluation in a short time is possible. Specifically, the quench hardening process using induction heating is completed in about several seconds to several tens of seconds. Therefore, in order to smoothly perform the material determination with one material determination means, the evaluation is performed in less time. It is desirable that is completed. Eddy current flaw detectors and material discriminators (ultrasonic hardness testers) satisfy this condition, and X-ray diffractometers with high output also satisfy this condition.

  Preferably, in the heat treatment method, the material determination in the material determination step is a non-destructive determination in which the material is determined without destroying the workpiece. Specifically, the determination of the material is preferably performed by determining the material without plastic deformation of the workpiece.

  If there is a process of cutting and destroying the object to be processed during the manufacturing process, it is natural that the object to be processed does not become a product, but even if it is a minute plastic deformation (such as a minute indentation) The product characteristics may be adversely affected. In addition, even if the deformation is in a range where there is substantially no problem in the function of the object to be processed in consideration of the use of the object to be processed, the deformation may be a problem in a product where aesthetics are important. Therefore, it is preferable that the material is determined without giving plastic deformation. Therefore, by having the above characteristics, it is possible to provide a heat treatment method that guarantees the quality of each object to be processed while suppressing the heat treatment cost of the object to be processed without impairing the function and aesthetics of the product. it can.

  An eddy current flaw detector, a material discriminator (ultrasonic hardness meter), and an X-ray diffractometer are automatic material determination means that satisfy this condition.

  Preferably, the heat treatment method further includes an appearance inspection step that is performed after the quench hardening step and inspects the appearance of the object to be processed, and the appearance inspection in the appearance inspection step automatically inspects the appearance. Implemented using automatic visual inspection means.

  As a result, not only the internal quality such as hardness and microstructure by quench hardening, but also the quality that appears on the appearance such as scratches on the surface of the object to be processed is guaranteed for each object to be processed. A heat treatment method can be provided.

  As the automatic appearance inspection means, for example, an image analysis inspection apparatus that finds a scratch on the surface of the object to be processed by analyzing an image captured from a camera or the like can be used.

Preferably, in the heat treatment method, the method further includes a tempering step which is performed after the quench hardening step and heats the workpiece to a temperature of A _c1 point or less, and the material determination step is a time point after the tempering step. And after the quench hardening process and before the tempering process.

  Thereby, in the heat treatment method in which quenching and tempering are performed, it is possible to provide a heat treatment method in which the quality of each object to be processed after at least one of the respective steps is guaranteed.

  In the above heat treatment method, the heating in the tempering step is preferably performed by induction heating. Thereby, compared with the case where an atmospheric furnace etc. are used, time for temperature rising becomes short and the efficiency of heat processing improves.

  Preferably, in the heat treatment method, the material determination in the material determination step is a non-destructive determination in which the material is determined without destroying the workpiece. Specifically, the determination of the material is preferably performed by determining the material without plastic deformation of the workpiece.

  Accordingly, as described above, it is possible to provide a heat treatment method that guarantees the quality of each object to be processed while suppressing the heat treatment cost of the object to be processed without impairing the function and aesthetics of the product. .

  Preferably, in the above heat treatment method, an appearance inspection step performed at least one of a time point after the tempering step and a time point after the quench hardening step and before the tempering step. In addition. The appearance inspection in the appearance inspection process is performed using automatic appearance inspection means for automatically inspecting the appearance.

  As a result, in the heat treatment method in which quenching and tempering are performed, not only the internal quality such as hardness and microstructure after at least one of the respective steps, but also the appearance such as scratches on the surface of the workpiece. Regarding the quality that appears above, it is possible to provide a heat treatment method that is guaranteed for each object to be processed.

  Preferably, in the heat treatment method, the material determined in the material determination step is a material corresponding to the hardness of the workpiece. Accordingly, it is possible to provide a heat treatment method that can guarantee the hardness, which is the most important quality regarding the quench hardening process and the tempering process, among the quality of the object to be processed for each object to be processed. In addition, it is desirable that the material to be determined has a high correlation with the hardness in the vicinity of the pass / fail determination threshold and a high resolution. For example, when a workpiece is used as a bearing member, it is desirable that a difference of about 2 HRC is clear in a region in the vicinity of 55HRC to 65HRC (Rockwell hardness) that is a threshold value for pass / fail determination.

  The manufacturing method of the thin member for a bearing according to the present invention includes a heat treatment step using the above heat treatment method. Here, in the present invention, the thin bearing member means a bearing member in which the thickness of the thickest portion is 3 mm or less.

  According to the method for manufacturing a thin member for a bearing according to the present invention, by providing the heat treatment step having the excellent characteristics of the heat treatment method, each product is one by one while the deformation in the heat treatment step is small and the production cost is suppressed. It is possible to manufacture a thin member for a bearing whose quality is guaranteed.

  Preferably, in the method for manufacturing the thin member for a bearing, a material punching step of punching a steel plate to form a workpiece is further provided before the heat treatment step.

  Thereby, in the manufacturing method of the thin member for bearings with small thickness, compared with the case where a to-be-processed object is shape | molded by cutting from a steel bar, manufacture efficiency is high and it can reduce manufacturing cost.

  Preferably, in the manufacturing method of the thin member for a bearing, a cleaning process for removing the deposits attached to the surface of the workpiece, and a cleaning liquid attached to the workpiece in the cleaning process is dried. And a drying step for removing. The cleaning process and the drying process are performed after the punching process and before the heat treatment process.

  This removes deposits such as rust-preventive oil, lubricating oil, and processing waste adhering to the surface of the workpiece in the molding process for molding the workpiece, and removes the deposit on the surface of the workpiece in the cleaning step. The heat treatment step can be performed in a state where the attached cleaning liquid is removed. As a result, these deposits can be prevented from adversely affecting the heat treatment of the workpiece, and contamination of the heat treatment equipment by these deposits can be prevented.

  The thin member for a bearing according to the present invention is manufactured by the method for manufacturing the thin member for a bearing. According to the thin member for a bearing of the present invention, it is possible to provide a thin member for a bearing in which the quality of each product is guaranteed while the deformation during heat treatment is small and the manufacturing cost is suppressed.

  The thin bearing member can be used as a bearing ring for a thrust bearing. In thrust bearings, the outer shape accuracy of the bearing ring is an important characteristic that affects the life of the bearing. As described above, the thin bearing member according to the present invention is suitable as a bearing ring for a thrust bearing because the deformation in heat treatment is small and the quality of each product is guaranteed while suppressing the manufacturing cost.

  A thrust bearing according to the present invention includes a bearing ring that is the above-described thin member for a bearing, and a rolling element disposed on a rolling surface of the bearing ring.

  According to the thrust bearing of the present invention, as described above, since the deformation in the heat treatment is small and the quality of each product is guaranteed while suppressing the manufacturing cost, long life and reliability are achieved. A highly efficient thrust bearing can be provided at low cost. In addition, a rolling surface means the part where a rolling element rolls in a raceway here.

  As is apparent from the above description, according to the heat treatment method of the present invention, it is possible to perform strict quality assurance while suppressing an increase in manufacturing cost and to suppress deformation that occurs during quenching. A method can be provided. In addition, according to the method for manufacturing a thin member for a bearing of the present invention, a thin member for a bearing that enables strict quality assurance while suppressing an increase in manufacturing cost and that suppresses deformation that occurs during quenching is manufactured. can do. Moreover, according to the thin member for a bearing of the present invention, it is possible to provide a thin member for a bearing that enables strict quality assurance while suppressing an increase in manufacturing cost and that suppresses deformation that occurs during quenching. it can. Further, according to the thrust bearing of the present invention, it is possible to provide a thrust bearing having a long life and high reliability at a low cost.

  Hereinafter, the manufacturing method of the thin member for bearings provided with the heat processing process using the heat processing method in one embodiment of the present invention and the thrust bearing provided with the bearing ring manufactured by it are explained.

  FIG. 1 is a diagram showing an outline of a method for manufacturing a thin bearing member in the present embodiment. Moreover, FIG. 2 is a figure which shows the outline of the manufacturing equipment used for the manufacturing method of the thin member for bearings in this Embodiment. 3 is a schematic cross-sectional view showing a high-frequency heating apparatus for quenching as induction heating means for quenching in the manufacturing facility of FIG. FIG. 4 is a schematic sectional view showing a die restraint cooling device as a die restraint cooling means in the manufacturing facility of FIG. FIG. 5 is a schematic cross-sectional view showing a thrust bearing provided with a bearing ring as a thin bearing member in the present embodiment.

  With reference to FIGS. 1-5, the manufacturing method of the thin member for bearings provided with the heat processing process using the heat processing method of this Embodiment, and the thrust bearing provided with the bearing ring manufactured by it are demonstrated.

  As shown in FIG. 1, first, a material punching process is performed in which a steel plate is punched to form a bearing ring as a thin member for bearing which is a workpiece. Specifically, as shown in FIG. 2, the steel plate 15 is moved to a position where punching by the punching device 4 including the upper punching die 42 and the lower punching die 41 can be performed by moving means (not shown). The race 11 is formed by punching with the steel plate 15 sandwiched between the upper punching die 42 and the lower punching die 41.

  Next, as shown in FIG. 1, a cleaning process for removing the deposits attached to the surface of the race 11 is performed. Specifically, as shown in FIG. 2, a position where the molded race 11 can be cleaned by a shower type cleaning device 8 as a cleaning means having a shower portion 82 and a cleaning liquid reservoir 81 by a moving means (not shown). Moved to. Then, the cleaning liquid is ejected toward the raceway ring 11 from the cleaning liquid outlet 82 </ b> A disposed on the surface of the shower unit 82 facing the cleaning liquid reservoir 81, whereby the raceway ring 11 is cleaned.

  Next, as shown in FIG. 1, the drying process for removing the cleaning liquid adhering to the bearing ring 11 in the cleaning process by drying the bearing ring 11 is performed. Specifically, as shown in FIG. 2, the cleaned raceway ring 11 is moved by a moving means (not shown) to a position where it can be dried by a hot air drying device 9 as a drying means provided with a hot air ejection part 91. . Then, hot air is ejected from the jet outlet 91 </ b> A formed in the hot air jet part 91 toward the race ring 11, whereby the race ring 11 is dried.

Next, as shown in FIG. 1, a heating step of heating the washer 11 to a temperature above A _c1 point, the washer 11 which is heated to a temperature equal to or higher than A _c1 point in the heating step follows M _s point temperature The quench hardening process which has a cooling process to cool to is implemented. Specifically, as shown in FIG. 2, the dried race ring 11 includes a quenching induction coil 22 and a quenching rotary table 21 provided by a moving unit (not shown) as a quenching induction heating unit. It is moved to a position where heating by the incoming high-frequency heating device 2 is possible. When the induction coil 22 for quenching is energized with a high-frequency current, the race 11 is heated to a temperature _{equal to} or higher than the _Ac1 point. Furthermore, the bearing ring 11 heated to a temperature _{equal to} or higher than the _{Ac 1} point is held by the arm unit 101 of the moving device 10 as the moving unit, and the arm unit 101 is swung in the direction of the arm unit turning direction 102, thereby The mold 32 and the lower restraint mold 31 are moved to a position where they can be cooled by the mold restraint cooling device 3 as a die restraint cooling means. Then, while the race ring 11 is sandwiched and restrained between the upper restraint mold restraint portion 32A of the upper restraint die 32 and the lower restraint die restraint portion 31A of the lower restraint die 31, heat is generated from the race ring 11. by upper retaining mold 32 and the lower restraining mold 31 is used as a cooling member for removing, washer 11 is cooled to a temperature below M _s point from the temperature of the above _c1 point a. Thereby, the race 11 is quenched and hardened.

  Next, as shown in FIG. 1, a material determination process for determining the material of the bearing ring 11 is performed on the hardened and hardened bearing ring 11. Specifically, as shown in FIG. 2, the hardened and hardened race ring 11 is connected to the hardness measurement holding base 51, the ultrasonic hardness measurement unit 52, and the ultrasonic hardness measurement unit 52 by moving means (not shown). The position is moved to a position where the hardness can be measured by the ultrasonic hardness tester 5 as an automatic material determination means equipped with the measurement control analyzer 53. Then, an ultrasonic wave is automatically emitted from the ultrasonic hardness measuring unit 52 toward the raceway ring 11, and the reflected ultrasonic wave is measured by the ultrasonic hardness measuring unit 52. Then, the measured ultrasonic wave is analyzed by the measurement control analyzer 53, whereby the surface hardness of the raceway ring 11, particularly the hardness of the rolling surface is automatically measured. Since this material determination step measures the hardness using ultrasonic waves, the bearing ring 11 is not plastically deformed. That is, this material determination step is performed as a nondestructive determination that determines the material without destroying the race 11.

  Next, as shown in FIG. 1, an appearance inspection process for inspecting the appearance of the race 11 is performed on the race 11 whose material has been determined. Specifically, as shown in FIG. 2, the raceway ring 11 whose material has been determined is connected to the appearance inspection holding base 61, the camera 62, the monitor 64, the camera 62 and the monitor 64 by moving means (not shown). The image processing apparatus 63 is moved to a position where an appearance inspection can be performed by the image processing apparatus 6 as an automatic appearance inspection means. Then, the image of the track ring 11 is automatically acquired by the camera 62, and the acquired image is taken into the image processing control unit 63 and analyzed, whereby the appearance of the track ring 11 is automatically inspected.

Next, as shown in FIG. 1, a tempering step of heating the _bearing ring 11 to a temperature not _higher than the _Ac1 point is performed on the bearing ring 11 whose appearance has been inspected. Specifically, as shown in FIG. 2, as the tempering induction heating means including the tempering induction coil 72 and the tempering rotary table 71, the outer ring 11 whose appearance has been inspected is moved by a moving means (not shown). It is moved to a position where it can be heated by the high-frequency heating device 7 for tempering. When the high-frequency current is applied to the induction coil 72 for tempering, the race 11 is heated to a temperature not higher than the _Ac1 point and then tempered by being cooled.

  Next, as shown in FIG. 1, a material determination step and an appearance inspection step are performed on the tempered race 11. This material determination process and appearance inspection process are the same processes as those performed after the quench hardening process. Specifically, as shown in FIG. 2, the tempered race 11 is moved to a position where the hardness measurement by the ultrasonic hardness meter 5 and the image processing device 6 can be performed by a moving means (not shown). A visual inspection is performed.

  Through the above-described steps, the race 11 that has been quenched and tempered using a steel plate as a material is manufactured. Then, the raceway that does not satisfy the predetermined standard is excluded by the material determination and the appearance inspection. Thereby, the quality regarding the hardness and appearance of all the races 11 is guaranteed.

  Furthermore, the thin-walled thrust roller bearing which is the thrust bearing of this Embodiment can be manufactured by combining the above-mentioned track ring 11 and the rolling element arrange | positioned on the rolling surface of the track ring 11. FIG.

  The configuration of the thin thrust roller bearing of the present embodiment will be described with reference to FIG. As shown in FIG. 5, the thin thrust roller bearing 1 includes, for example, a pair of race rings 11, 11, a plurality of rolling elements 12, and an annular cage 13. The rolling element 12 is disposed between the pair of raceways 11 and 11 in contact with the rolling surfaces 11A and 11A of the raceways 11 and 11. Further, the rolling elements 12 are arranged at a predetermined pitch in the circumferential direction by the cage 13 and are held so as to be freely rollable. Thereby, each of the race rings 11 and 11 can rotate relatively to each other.

  Next, among the above manufacturing processes, the quench hardening process will be described in detail with reference to FIGS. The quenching high-frequency heating device 2 shown in FIG. 3 includes a quenching turntable 21 made of, for example, a heat insulating material (for example, ceramic) and a quenching induction coil 22. Further, the quenching turntable 21 has a protruding portion 21 </ b> A for setting the race 11. The die restraint cooling device 3 shown in FIG. 4 includes a lower restraint die 31 and an upper restraint die 32, and applies a downward load from above the upper restraint die by a press weight, a hydraulic cylinder, or the like. It has a configuration that can.

Next, the procedure of quench hardening will be described. As shown in FIG. 3, the molded bearing ring 11 is set so as to be in contact with the upper part of the protruding portion 21 </ b> A of the quenching rotary table 21. Next, a high frequency current is passed through the induction coil 22 for quenching, and the race 11 is induction heated. At this time, the race 11 is rotated by the quenching rotary table 21 in order to perform uniform heating. The bearing ring 11 is heated to a temperature of the _Ac1 point or higher by induction heating and is held for a predetermined time.

Thereafter, the race 11 is immediately sandwiched between the lower restraint die 31 and the upper restraint die 32 of the adjacent die restraint cooling device 3, and a press weight is placed on the upper restraint die 32. Thereby, while the race 11 is restrained by the lower restraint die 31 and the upper restraint die 32, the heat is removed by the lower restraint die 31 and the upper restraint die 32 as cooling members, so that the _Ms point or less is obtained. Quenched to the temperature of

  Here, since the thickness of the bearing ring 11 is 3 mm or less and the heat capacity is small, it is sufficient to contact the lower restraint die 31 and the upper restraint die 32 without using a cooling medium such as oil and water. It is possible to cool rapidly.

  Further, for example, the treatment conditions when quenching and hardening the raceway ring 11 made of SAE1070 having an inner diameter of 60 mm, an outer diameter of 80 mm, and a thickness of 1 mm are 900 ° C. to 1050 ° C., and the heating time is 0.5 seconds. It is preferable that the restraint (press) pressure is 11.7 kPa or more and the restraint time is 2 seconds or more. The material of the upper restraint mold restraint part 32A of the upper restraint mold 32 and the lower restraint mold restraint part 31A of the lower restraint mold 31 is the surface of the upper restraint mold restraint part 32A and the lower restraint mold restraint part 31A. From the viewpoint of preventing damage, it is preferable to have a hardness equal to or higher than the hardened and hardened race ring 11, for example, hardened and hardened bearing steel, carbon steel, and stainless steel are preferable. . Moreover, the material of the lower restraint die 31 and the upper restraint die 32 is preferably a material having high thermal conductivity and corrosion resistance.

  Further, regarding the size of the lower restraint die 31 and the upper restraint die 32, it is necessary that the heat capacity difference with the raceway ring 11 to be hardened by hardening is large, and the lower restraint die 31 and the upper restraint die 32 are required. The volume of each is preferably 50 times or more the volume of the race 11. It is to be noted that the lower restraint die 31 and the upper restraint die 32 and the race ring 11 to be hardened by hardening are necessary by using a cooling means including a coolant circulation means for flowing a coolant such as water into the die. It is possible to reduce the volume ratio, and thus the mold restraint cooling device 3 can be made compact. In addition, the same effect can be obtained by using a cooling means including a cooling gas supply member for blowing and cooling a gas such as air to the lower restraint die 31 and the upper restraint die 32. In this case, dust attached to the lower restraint die 31 and the upper restraint die 32 can be removed by blowing the gas.

  The accuracy of the lower restraint mold restraint portion 31A and the upper restraint die restraint portion 32A is preferably high because it affects the accuracy of the raceway ring 11 to be hardened and hardened. That is, it is preferable that warpage and undulation are small and the surface roughness is small (polishing finish level).

  In addition, the heating step and the cooling step in the quench hardening process can be performed in an air atmosphere, but preferably in an atmosphere that suppresses oxidation, for example, in a gas atmosphere having poor reactivity such as nitrogen.

  Normally, when the bearing ring 11 is manufactured under the above conditions, if the tempering temperature is 150 ° C. or less, a bearing ring having a surface layer hardness of 730 HV and a raceway warpage of 30 μm or less can be manufactured. Furthermore, in the present embodiment, hardness measurement and appearance inspection are performed on all the races 11 after quenching and tempering. Therefore, it is possible to manufacture a highly reliable bearing ring 11 in which the quality of the bearing ring is stable and the quality is strictly guaranteed, and the thrust bearing 1 including the same. In addition, since the hardness measurement results and the appearance inspection result data are obtained for all the races 11, the cause of the failure when the faulty race 11 is found can be easily determined by statistically processing these data. It is also possible to improve the reliability of the 11 manufacturing processes themselves.

  In the conventional process, after the race 11 is formed, it is stored in a storage container or the like as a work in progress until it is hardened by hardening. Since the hardened and hardened race rings 11 have low hardness, the race rings 11 may come into contact with each other during transport and handling, and deep scratches may occur. In particular, in the case of the thin ring 11, the thickness that is scraped by the subsequent polishing is often small, so that even if the subsequent steps are carried out normally, scratches may remain and become defective products. . In the present embodiment, the process from the molding of the race 11 to the inspection after tempering can be performed without generating work-in-progress, so there is no possibility of such scratches. Therefore, not only the reliability of the product is high, but it is also possible to suppress the number of bearing rings 11 excluded as defective products, which contributes to a reduction in manufacturing cost. In addition, since the surface state of the steel plate is different between the front side and the back side, it is necessary to align the direction of the race ring 11 on either the front side or the back side when the race ring 11 is manufactured. From the viewpoint of. When the molded bearing ring 11 is stored in a storage container or the like as a work in progress as in the conventional process, it is extremely difficult to manage the orientation of the bearing ring 11. On the other hand, in the present embodiment in which work-in-process is not generated in the middle of the process, the direction of the race 11 can be managed relatively easily at least until the end of the inspection after tempering. As a result, the quality of the race 11 can be stabilized.

  In the present embodiment, the case where the bearing ring 11 as the object to be processed is moved from each device such as the quenching high-frequency heating device 2 and the die restraint cooling device 3 to the next device by the moving means will be described. However, the heat treatment method and the thin-walled member manufacturing method of the present invention are not limited to this. For example, some or all of the devices included in the manufacturing facility are configured to be movable, It may be a mode in which processing such as heating and cooling is performed by moving each device.

  Moreover, in this Embodiment, although the case where the high frequency heating apparatus 2 for quenching and the high frequency heating apparatus 7 for tempering were provided separately was demonstrated, the high frequency heating apparatus 2 for quenching is the high frequency heating apparatus 7 for tempering. The manufacturing facility may be configured to serve as both.

  Further, in the present embodiment, the ultrasonic hardness tester 5 and the image processing device 6 are for performing hardness measurement and appearance inspection after quenching and before tempering, and for measuring hardness and appearance after tempering. Although the case where the one for inspecting is provided separately has been described, the one for performing hardness measurement and appearance inspection after quenching and before tempering performs hardness measurement and appearance inspection after tempering The manufacturing facility may be configured to serve as the purpose.

  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.

Method for manufacturing a heat treatment method and bearing thin member of the present invention includes a heating step of heating the object to be treated to a temperature above A _c1 point, the workpiece which has been heated to a temperature equal to or higher than A _c1 point in the heating step M A heat treatment method including a quench hardening step having a cooling step of cooling to a temperature below the _s point, and a material determination step that is performed after the quench hardening step and that determines the material of the workpiece, and the heat treatment method The present invention can be particularly advantageously applied to a method for manufacturing a thin member for a bearing provided with a heat treatment step using. The thin-walled member for a bearing and the thrust bearing of the present invention can be particularly advantageously applied to a thin-walled member for a bearing manufactured by the above-described manufacturing method and a thrust bearing provided with the thin-walled member for a bearing as a race ring.

It is a figure which shows the outline of the manufacturing method of the thin member for bearings. It is a figure which shows the outline of the manufacturing equipment used for the manufacturing method of the thin member for bearings. It is a schematic sectional drawing which shows the high frequency heating apparatus for hardening as induction heating means for hardening among the manufacturing facilities of FIG. It is a schematic sectional drawing which shows the metal mold | die restraint cooling device as a metal mold | die restraint cooling means among the manufacturing facilities of FIG. It is a schematic sectional drawing which shows the thrust bearing provided with the bearing ring as a thin member for bearings.

Explanation of symbols

  1 Thin-walled thrust roller bearing, 2 quenching high-frequency heating device, 3 die restraint cooling device, 4 punching device, 5 ultrasonic hardness meter, 6 image processing device, 7 tempering high-frequency heating device, 8 shower type cleaning device, DESCRIPTION OF SYMBOLS 9 Hot-air drying apparatus, 10 moving apparatus, 11 track ring, 11A rolling surface, 12 rolling element, 13 retainer, 15 steel plate, 21 quenching rotary table, 21A protrusion part, 22 quenching induction coil, 31 lower part Restraint mold, 31A Lower restraint mold restraint part, 32 Upper restraint mold restraint, 32A Upper restraint mold restraint part, 41 Lower punching mold, 42 Upper punching mold, 51 Hardness measurement holder, 52 Ultrasonic Hardness measurement unit, 53 measurement control analyzer, 61 visual inspection holding table, 62 camera, 63 image processing control unit, 64 monitor, 71 tempering rotary table, 72 tempering guidance Yl, 81 the scrubbing liquid sump, 82 shower part, 82A rinse jets 91 hot air discharge portion, 91A spout 101 arm, 102 arm turning direction.

Claims (5)

And a cooling step of cooling the object to be processed and the heating step of heating to a temperature above A _c1 point, the workpiece which has been heated to a temperature equal to or higher than A _c1 point to a temperature below M _s point the heating step Quench hardening process;
A heat treatment method including a material determination step, which is performed after the quench hardening step and determines a material of the workpiece,
The heating in the heating step is performed by induction heating,
The cooling in the cooling step is performed while restraining the object to be processed using a mold,
The cooling is performed by using the mold as a cooling member for removing heat from the object to be processed, thereby cooling the object to be processed from a temperature of A _c1 or higher to a temperature of M _s or lower. ,
The determination of the material in the material determination step is a heat treatment method performed using automatic material determination means for automatically determining the material. Further comprising a tempering step, which is performed after the quench hardening step and heats the workpiece to a temperature of A _c1 point or less,
The material determination step is performed at least one of a time point after the tempering step and a time point after the quench hardening step and before the tempering step. Item 2. The heat treatment method according to Item 1.   The manufacturing method of the thin member for bearings provided with the heat processing process using the heat processing method of Claim 1 or 2.   The thin member for bearings manufactured by the manufacturing method of the thin member for bearings of Claim 3. A bearing ring which is a thin member for a bearing according to claim 4;
A thrust bearing comprising a rolling element disposed on a rolling surface of the raceway.

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