JP2013119930A - Bearing component and rolling bearing, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing component and a rolling bearing capable of compatibly attaining the indentation resistance and the rolling fatigue life at the high level while ensuring the easy obtainability of a material, and to provide a method for manufacturing the same.SOLUTION: An outer ring 11, an inner ring 12, and a ball 13 which are bearing components are formed of quench-hardened steel having the composition consisting of, by mass, ≥0.90% and ≤1.05% carbon, ≥0.15% and ≤0.35% silicon, ≥0.01% and ≤0.50% manganese, ≥1.30% and ≤1.65% chromium, and the remainder impurities. The nitrogen concentration in a contact surface which is a surface in contact with other components is ≥0.25%, and the residual austenite amount in the contact surface is ≥6 vol% and ≤12 vol%.

Description

  The present invention relates to a bearing component, a rolling bearing, and a manufacturing method thereof, and more specifically, a bearing component, a rolling bearing, and a manufacturing method thereof that can achieve both high pressure resistance and rolling fatigue life at a high level. It is about.

  In recent years, machine life has been extended and maintenance free. As a result, the rolling fatigue life of the rolling bearing used in the machine is required to be extended. In order to achieve a longer rolling fatigue life, a measure to change the material of bearing parts (track members and rolling elements) which are parts constituting a rolling bearing can be considered. Specifically, the rolling fatigue life can be extended by adding an alloy component effective for extending the life to steel, which is a typical material for bearing parts.

  However, when a special material is used for the material of the bearing component, it may be difficult to procure the material depending on the manufacturing location, considering the current situation that the manufacturing bases are spreading all over the world. Therefore, considering such a situation, it is not necessarily preferable to increase the rolling fatigue life using a special material.

  On the other hand, as another measure for extending the rolling fatigue life, it has been proposed to extend the life of bearing parts and rolling bearings by heat treatment (see, for example, Patent Documents 1 to 3).

Japanese Patent Laid-Open No. 7-190072 JP 2003-226918 A JP 2000-161363 A

  On the other hand, in rolling bearings that need to support a large load, such as tapered roller bearings, deep groove ball bearings, angular contact ball bearings, and tandem angular contact ball bearings used in automotive differentials and transmissions, the rolling fatigue life is long. Along with the lifetime, pressure resistance (hardness of formation of indentation when the rolling element is pressed against the raceway member) is required. However, even when the rolling fatigue life is extended by the conventional heat treatment including the above-mentioned Patent Documents 1 to 3, there is a problem that the pressure scar resistance becomes insufficient.

  The present invention has been made in order to solve the above-described problems, and its purpose is to achieve both high pressure scar resistance and rolling fatigue life at a high level while ensuring the availability of materials. It is to provide a bearing component capable of supporting, a rolling bearing, and a method of manufacturing the same.

  The bearing component according to the present invention comprises 0.90 mass% or more and 1.05 mass% or less carbon, 0.15 mass% or more and 0.35 mass% or less silicon, or 0.01 mass% or more and 0.50 mass% or less. A contact surface that is made of quench-hardened steel containing not more than mass% manganese and not less than 1.30 mass% and not more than 1.65 mass% chromium, and is made of the remaining impurities and is in contact with other components. The nitrogen concentration in is 0.25% by mass or more, and the amount of retained austenite on the contact surface is 6% by volume or more and 12% by volume or less.

  The present inventor assumes that JIS standard SUJ2 equivalent material (JIS standard SUJ2, ASTM standard 52100, DIN standard 100Cr6, GB standard GCr5 or GCr15, and ΓOCT standard ЩX15), which is easily available in various countries around the world, is adopted as a material. We investigated the measures to achieve both high pressure scar resistance and rolling fatigue life at a high level. As a result, the following knowledge was obtained and the present invention was conceived.

  By adopting the above component composition, it is possible to use, as a material, the above-mentioned national standard steel that is easily available in various countries around the world. And on the premise of using the steel of the said component composition, the nitrogen concentration in a contact surface is raised to 0.25 mass% or more, and a rolling fatigue life is prolonged by hardening by hardening. it can. Here, when the amount of retained austenite is not particularly adjusted, the amount of retained austenite at the contact surface is about 20 to 40% by volume in relation to the amount of nitrogen. However, in such a state where the amount of retained austenite is large, there arises a problem that the pressure resistance is lowered. And by reducing the amount of retained austenite to 12% by volume or less, it is possible to improve the pressure resistance. On the other hand, when the amount of retained austenite is reduced to less than 6% by volume, the rolling fatigue life, particularly the rolling fatigue life in an environment in which hard foreign matter enters the bearing (foreign matter mixed environment) is lowered. Therefore, the amount of retained austenite at the contact surface is preferably 6% by volume or more.

  On the other hand, in the bearing component of the present invention, a JIS standard SUJ2 equivalent material that is easily available in various countries is used as a material, and the nitrogen concentration at the contact surface is 0.25% by mass or more and the residual austenite amount is 6% by volume. It is made into 12 volume% or less above. As a result, according to the bearing component of the present invention, it is possible to provide a bearing component capable of achieving both high pressure scar resistance and rolling fatigue life at a high level while ensuring the availability of materials. . From the viewpoint of further improving the pressure scar resistance, the amount of retained austenite on the contact surface may be 10% or less. Moreover, when the nitrogen concentration in a contact surface exceeds 0.5 mass%, while the cost for making nitrogen infiltrate into steel becomes high, it will become difficult to adjust the amount of retained austenite to a desired range. Therefore, the nitrogen concentration on the contact surface is preferably 0.5% by mass or less, and may be 0.4% by mass or less.

  In the bearing component, the hardness of the contact surface may be 60.0 HRC or more. As a result, the rolling fatigue life and the pressure scar resistance can be further improved.

  In the bearing component, the hardness of the contact surface may be 64.0 HRC or less. When the hardness of the contact surface where the nitrogen concentration is increased to 0.25% by mass or more is maintained in a state exceeding 64.0 HRC, it is difficult to adjust the retained austenite to 12% by volume or less. By setting the hardness of the contact surface to 64.0 HRC or less, it becomes easy to adjust the amount of retained austenite to a range of 12% by volume or less.

  The rolling bearing according to the present invention includes a race member and a plurality of rolling elements arranged in contact with the race member. At least one of the race member and the rolling element is the bearing component of the present invention.

  The rolling bearing of the present invention includes the bearing component of the present invention as at least one of a race member and a rolling element. As a result, according to the rolling bearing of the present invention, it is possible to provide a rolling bearing capable of achieving both high pressure scar resistance and rolling fatigue life at a high level while ensuring the availability of materials. .

  The rolling bearing may support a rotating member that rotates in a differential or a transmission so as to be rotatable with respect to another member that is disposed adjacent to the rotating member.

  A high surface pressure is applied between a rolling element and a raceway member in a bearing used in a differential or a transmission. For this reason, bearings for such applications are required not only to increase the rolling fatigue life but also to improve the pressure resistance. For this reason, the rolling bearing of the present invention capable of achieving both high pressure scar resistance and rolling fatigue life at a high level is suitable as a bearing used in a differential or a transmission.

  The method for manufacturing a bearing component according to the present invention includes 0.90 mass% or more and 1.05 mass% or less of carbon, 0.15 mass% or more and 0.35 mass% or less of silicon, and 0.01 mass% or more. A step of producing a molded member by molding steel comprising the balance impurities, and containing 0.50% by mass or less of manganese and 1.30% by mass to 1.65% by mass of chromium; A step of carbonitriding, a step of quench-hardening the carbonitrided molded member, a step of tempering the quench-hardened molded member, and processing the tempered molded member And a step of forming a contact surface that is a surface in contact with another component. In the step of carbonitriding the formed member, the formed member is carbonitrided so that the nitrogen concentration of the contact surface is 0.25% by mass or more in the step of forming the contact surface. In the step of tempering the molded member, the molded member is tempered so that the amount of retained austenite on the contact surface is 6% by volume to 12% by volume in the step of forming the contact surface.

  According to the bearing component manufacturing method of the present invention, the bearing component of the present invention can be manufactured.

  In the method for manufacturing the bearing component, in the step of tempering the molded member, the molded member may be tempered in a temperature range of 240 ° C. or higher and 300 ° C. or lower. This makes it easy to adjust the amount of retained austenite on the contact surface to a range of 6% by volume to 12% by volume. Moreover, carbon is dissolved in the hardened steel. This solid solution carbon contributes to solid solution strengthening of the material (steel) in the vicinity of the contact surface. On the other hand, when the tempered steel is tempered, a part of the dissolved carbon precipitates as carbide. This precipitated carbide contributes to precipitation strengthening of the material (steel) in the vicinity of the contact surface. When the tempering treatment temperature is less than 240 ° C., the solid solution strengthening of the material in the vicinity of the contact surface is sufficient, but the precipitation strengthening is insufficient. On the other hand, when the treatment temperature of the tempering treatment exceeds 300 ° C., precipitation strengthening of the material near the contact surface is sufficient, but solid solution strengthening is insufficient. And the process temperature of a tempering process shall be 240 degreeC or more and 300 degrees C or less, the balance of a solid solution strengthening and precipitation strengthening will become favorable, and a pressure | voltage resistant mark property will improve.

  In the method for manufacturing a bearing component, in the step of quenching the molded member, the molded member may be quenched by being rapidly cooled from a temperature range of 860 ° C. or lower. Thereby, it is possible to suppress the difficulty in adjusting the balance between the solid solution amount and the precipitation amount of carbon after quench hardening and the tempering treatment of the retained austenite amount.

  In the method for manufacturing a bearing component, in the step of quenching the molded member, the molded member may be quenched by being rapidly cooled from a temperature range of 820 ° C. or higher. Thereby, it is possible to suppress the difficulty in adjusting the balance between the solid solution amount and the precipitation amount of carbon after quench hardening and the tempering treatment of the retained austenite amount.

  A rolling bearing manufacturing method according to the present invention assembles a rolling bearing by combining a step of preparing a race member, a step of preparing a plurality of rolling elements, and a plurality of rolling members so as to contact the race member. Process. And at least any one of the process of preparing a race member and the process of preparing a plurality of rolling elements is carried out using the manufacturing method of a bearing component of the above-mentioned present invention. Thereby, the rolling bearing of the present invention can be manufactured.

  As is clear from the above description, according to the bearing component, the rolling bearing, and the manufacturing method thereof of the present invention, the pressure scar resistance and the rolling fatigue life are at a high level while ensuring the availability of the material. It is possible to provide a bearing component, a rolling bearing, and a manufacturing method thereof that can be compatible.

It is a schematic sectional drawing which shows the structure of a deep groove ball bearing. It is the schematic fragmentary sectional view which expanded and showed the principal part of FIG. It is a schematic sectional drawing which shows the structure of a thrust roller bearing. FIG. 4 is a schematic partial cross-sectional view of the raceway ring of FIG. 3. It is a schematic sectional drawing of the roller of FIG. It is a flowchart which shows the outline of the manufacturing method of a rolling bearing. It is a schematic sectional drawing which shows the structure of a manual transmission. It is a schematic sectional drawing which shows the structure of a differential. It is the schematic which shows arrangement | positioning of the pinion gear of FIG. It is a figure which shows the relationship between tempering temperature and indentation depth. It is a figure which shows the relationship between tempering temperature and hardness. It is a figure which shows the relationship between a true strain and a true stress. It is a figure which expands and shows the area | region (alpha) of FIG.

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

(Embodiment 1)
Hereinafter, Embodiment 1 which is one embodiment of the present invention will be described. Referring to FIGS. 1 and 2, deep groove ball bearing 1 that is a rolling bearing in Embodiment 1 includes an outer ring 11 as a first race member that is a bearing component, and an inner ring as a second race member that is a bearing component. 12, balls 13 as a plurality of rolling elements that are bearing parts, and a cage 14. The outer ring 11 is formed with an outer ring rolling surface 11A as an annular first rolling surface. The inner ring 12 is formed with an inner ring rolling surface 12A as an annular second rolling surface facing the outer ring rolling surface 11A. Further, the balls 13 are formed with ball rolling surfaces 13A (the surfaces of the balls 13) as rolling elements rolling surfaces. The outer ring rolling surface 11A, the inner ring rolling surface 12A, and the ball rolling surface 13A are contact surfaces of these bearing components. The balls 13 are in contact with each of the outer ring rolling surface 11A and the inner ring rolling surface 12A on the ball rolling surface 13A, and are arranged at a predetermined pitch in the circumferential direction by an annular retainer 14. It is rotatably held on an annular track. With the above configuration, the outer ring 11 and the inner ring 12 of the deep groove ball bearing 1 are rotatable relative to each other.

  Referring to FIG. 2, the outer ring 11, the inner ring 12, and the ball 13, which are bearing parts, are 0.90 mass% or more and 1.05 mass% or less carbon, and 0.15 mass% or more and 0.35 mass% or less. Containing silicon, 0.01 mass% or more and 0.50 mass% or less manganese, and 1.30 mass% or more and 1.65 mass% or less chromium, and made of quench-hardened steel consisting of the remaining impurities. ing. In the region including the outer ring rolling surface 11A, the inner ring rolling surface 12A, and the ball rolling surface 13A as contact surfaces, nitrogen enriched layers 11B, 12B, having a higher nitrogen concentration than the inner 11C, 12C, 13C, 13B is formed. The nitrogen concentration in the outer ring rolling surface 11A, the inner ring rolling surface 12A and the ball rolling surface 13A as contact surfaces which are the surfaces of the nitrogen-enriched layers 11B, 12B and 13B is 0.25% by mass or more. Furthermore, the amount of retained austenite on the outer ring rolling surface 11A, the inner ring rolling surface 12A, and the ball rolling surface 13A is 6% by volume or more and 12% by volume or less.

  The outer ring 11, the inner ring 12 and the ball 13 which are bearing parts in the present embodiment are made of steel having a component composition of the JIS standard SUJ2 equivalent steel, so that the material can be easily obtained all over the world. And on the premise of using the steel of the said composition, the nitrogen concentration in outer ring rolling surface 11A, inner ring rolling surface 12A and ball rolling surface 13A is increased to 0.25% by mass or more and is hardened and hardened. As a result, the rolling fatigue life is extended. And, the amount of retained austenite is reduced to 12% by volume or less, so that the pressure scar resistance is improved, and the amount of retained austenite is made to be 6% by volume or more. The rolling fatigue life of is maintained at an appropriate level. As a result, the outer ring 11, the inner ring 12 and the ball 13 are bearing parts capable of achieving both high pressure scar resistance and rolling fatigue life at a high level while ensuring the availability of materials.

  In the outer ring 11, the inner ring 12 and the ball 13, the hardness of the outer ring rolling surface 11A, the inner ring rolling surface 12A and the ball rolling surface 13A which are contact surfaces is preferably 60.0 HRC or more. As a result, the rolling fatigue life and the pressure scar resistance can be further improved.

  In the outer ring 11, the inner ring 12 and the ball 13, the hardness of the outer ring rolling surface 11A, the inner ring rolling surface 12A and the ball rolling surface 13A is preferably 64.0 HRC or less. Thereby, it becomes easy to adjust the amount of retained austenite in the outer ring rolling surface 11A, the inner ring rolling surface 12A, and the ball rolling surface 13A to a range of 12% by volume or less.

  Referring to FIGS. 3 to 5, a thrust needle roller bearing 2 that is a rolling bearing in the modification of the first embodiment has basically the same configuration as the deep groove ball bearing 1 and has the same effect. Play. However, the thrust needle roller bearing 2 is different from the deep groove ball bearing 1 in the configuration of the raceway member and the rolling element. That is, the thrust needle roller bearing 2 has a disk-like shape, and a pair of race rings 21 as race members disposed so that one main surfaces thereof face each other, and a plurality of needle rollers 23 as rolling elements. And an annular retainer 24. The plurality of needle rollers 23 are in contact with a raceway rolling surface 21A formed on one main surface of the pair of raceways 21 facing each other on a roller rolling contact surface 23A that is an outer peripheral surface of the needle roller 23, and By being arranged at a predetermined pitch in the circumferential direction by the cage 24, the cage 24 is held so as to roll on an annular track. With the above configuration, the pair of race rings 21 of the thrust needle roller bearing 2 can rotate relative to each other.

  The bearing ring 21 of the thrust needle roller bearing 2 corresponds to the outer ring 11 and the inner ring 12 of the deep groove ball bearing, and the needle roller 23 of the thrust needle roller bearing 2 corresponds to the ball 13 of the deep groove ball bearing, and is made of the same material. In addition, it has nitrogen-enriched layers 21B and 23B, internal portions 21C and 23C, raceway rolling surfaces 21A and rolling contact surfaces 23A having the same nitrogen concentration and retained austenite amount. Thereby, the bearing ring 21 and the needle roller 23 are bearing parts capable of achieving both a high pressure scar resistance and a rolling fatigue life at a high level while ensuring the availability of materials.

  Next, the bearing component and the rolling bearing manufacturing method in the present embodiment will be described. With reference to FIG. 6, first, a steel material preparation step is performed as a step (S10). In this step (S10), a steel material made of JIS standard SUJ2 equivalent steel such as JIS standard SUJ2, ASTM standard 52100, DIN standard 100Cr6, GB standard GCr5 or GCr15, and ΓOCT standard X15 is prepared. Specifically, for example, a steel bar or a steel wire having the above composition is prepared.

  Next, a forming step is performed as a step (S20). In this step (S20), the outer ring 11 and the inner ring 12 shown in FIGS. 1 to 5 are performed by performing processing such as forging and turning on the steel bars and steel wires prepared in step (S10), for example. , Molded members formed into shapes such as balls 13, races 21, and needle rollers 23 are produced.

  Next, a carbonitriding step is performed as a step (S30). In this step (S30), the formed member produced in step (S20) is carbonitrided. This carbonitriding process can be performed as follows, for example. First, the molded member is preheated in a temperature range of about 780 ° C. to 820 ° C. for a period of 30 minutes to 90 minutes. Next, the preheated molded member is heated in an atmosphere in which ammonia gas is further introduced into an endothermic gas such as RX gas whose carbon potential is adjusted by adding propane gas or butane gas as an enriched gas. And carbonitrided. The temperature of the carbonitriding process can be set to 820 ° C. or higher and 880 ° C. or lower, for example. The carbonitriding time can be set according to the nitrogen concentration of the nitrogen-enriched layer to be formed on the molded member, and can be set to 3 hours or more and 9 hours or less, for example. Thereby, a nitrogen rich layer can be formed, suppressing decarburization of a forming member.

  Next, a quenching process is implemented as process (S40). In this step (S40), the molded member on which the nitrogen-enriched layer is formed by the carbonitriding process in step (S30) is quenched by being rapidly cooled from a predetermined quenching temperature. By setting the quenching temperature to 860 ° C. or less, it becomes easy to adjust the balance between the solid solution amount and the precipitation amount of carbon and the amount of retained austenite in the subsequent tempering step. Further, by setting the quenching temperature to 820 ° C. or higher, it becomes easy to adjust the balance between the solid solution amount and the precipitation amount of carbon and the amount of retained austenite in the subsequent tempering step. The quenching treatment can be carried out, for example, by immersing the molded member in quenching oil as a coolant maintained at a predetermined temperature.

  Next, a tempering step is performed as a step (S50). In this step (S50), the molded member quenched in the step (S40) is tempered. Specifically, for example, the tempering treatment is performed by holding the molded member in an atmosphere heated to a temperature range of 210 ° C. or higher and 300 ° C. or lower for a time period of 0.5 hours or longer and 3 hours or shorter.

  Next, a finishing process is performed as a process (S60). In this step (S60), the contact surface that is a surface that comes into contact with other components by processing the molded member that has been tempered in step (S50), that is, the outer ring rolling surface 11A of the deep groove ball bearing 1, The ring rolling surface 12A and the ball rolling surface 13A, and the raceway rolling surface 21A and the rolling contact surface 23A of the thrust needle roller bearing 2 are formed. As the finishing process, for example, a grinding process can be performed. The outer ring 11, inner ring 12, ball 13, race ring 21, needle roller 23, etc., which are bearing parts in the present embodiment, are completed through the above steps.

  Furthermore, an assembly process is performed as a process (S70). In this step (S70), the outer ring 11, the inner ring 12, the ball 13, the race ring 21, the needle roller 23 produced in steps (S10) to (S60) and the cages 14 and 24 prepared separately are assembled. Together, the deep groove ball bearing 1 and the thrust needle roller bearing 2 in the above embodiment are assembled. Thereby, the manufacturing method of the rolling bearing in this Embodiment is completed.

  Here, in the step (S30), the outer ring rolling surface 11A, the inner ring rolling surface 12A and the ball rolling surface 13A of the deep groove ball bearing 1 which are contact surfaces by finishing in the subsequent step (S60), and the thrust needle The formed member is carbonitrided so that the nitrogen concentration of the raceway rolling surface 21A and the rolling contact surface 23A of the roller bearing 2 is 0.25% by mass or more. That is, in consideration of the allowance in the step (S60), etc., the nitrogen enriched layer 11B in which the nitrogen amount is adjusted so that the nitrogen concentration on the surface after completion of the contact surface can be 0.25% by mass or more. , 12B, 13B, 21B, and 23B are formed.

  Further, in the step (S50), the outer ring rolling surface 11A, the inner ring rolling surface 12A and the ball rolling surface 13A of the deep groove ball bearing 1 which are contact surfaces by the finishing process in the subsequent step (S60), and the thrust needle roller. The molded member is tempered so that the amount of retained austenite on the raceway rolling surface 21A and the rolling contact surface 23A of the bearing 2 is 6% by volume or more and 12% by volume or less. That is, considering the machining allowance in the step (S60) and the like, the retained austenite is obtained by tempering so that the amount of retained austenite on the surface after completion of the contact surface can be 6% by volume or more and 12% by volume or less. The amount is adjusted. Thereby, the bearing component in the said this Embodiment can be manufactured.

  In the step (S50), the molded member is preferably tempered in a temperature range of 240 ° C. or higher and 300 ° C. or lower. As a result, carbon solid-dissolved in the substrate by the quenching process is precipitated as a carbide at an appropriate ratio. As a result, an appropriate balance between solid solution strengthening and precipitation strengthening is achieved, and the pressure resistance of the outer ring 11, inner ring 12, ball 13, race ring 21, and needle roller 23 that are bearing parts is improved.

(Embodiment 2)
Next, an example of the use of the rolling bearing in the first embodiment will be described. Referring to FIG. 7, manual transmission 100 is a constant-mesh manual transmission, and includes input shaft 111, output shaft 112, counter shaft 113, gears (gears) 114 a to 114 k, and housing 115. It has.

  The input shaft 111 is rotatably supported by the deep groove ball bearing 1 with respect to the housing 115. A gear 114a is formed on the outer periphery of the input shaft 111, and a gear 114b is formed on the inner periphery.

  On the other hand, the output shaft 112 is rotatably supported on the housing 115 by the deep groove ball bearing 1 on one side (right side in the figure), and can be rotated on the input shaft 111 by the rolling bearing 120A on the other side (left side in the figure). It is supported by. Gears 114c to 114g are attached to the output shaft 112.

  The gear 114c and the gear 114d are respectively formed on the outer periphery and the inner periphery of the same member. The member in which the gear 114c and the gear 114d are formed is rotatably supported with respect to the output shaft 112 by the rolling bearing 120B. The gear 114e is attached to the output shaft 112 so as to rotate integrally with the output shaft 112 and to be slidable in the axial direction of the output shaft 112.

  Each of the gear 114f and the gear 114g is formed on the outer periphery of the same member. The member in which the gear 114f and the gear 114g are formed is attached to the output shaft 112 so as to rotate integrally with the output shaft 112 and to be slidable in the axial direction of the output shaft 112. When the member on which the gear 114f and the gear 114g are formed slides to the left in the figure, the gear 114f can mesh with the gear 114b. When the member slides to the right in the figure, the gear 114g and the gear 114d Engageable.

  Gears 114 h to 114 k are formed on the countershaft 113. Two thrust needle roller bearings 2 are arranged between the countershaft 113 and the housing 115, and thereby an axial load (thrust load) of the countershaft 113 is supported. The gear 114h always meshes with the gear 114a, and the gear 114i always meshes with the gear 114c. The gear 114j can mesh with the gear 114e when the gear 114e slides to the left side in the drawing. Furthermore, the gear 114k can mesh with the gear 114e when the gear 114e slides to the right in the drawing.

  Next, the shifting operation of the manual transmission 100 will be described. In the manual transmission 100, the rotation of the input shaft 111 is transmitted to the countershaft 113 by meshing between the gear 114 a formed on the input shaft 111 and the gear 114 h formed on the countershaft 113. The rotation of the countershaft 113 is transmitted to the output shaft 112 by meshing the gears 114 i to 114 k formed on the countershaft 113 with the gears 114 c and 114 e attached to the output shaft 112. Thereby, the rotation of the input shaft 111 is transmitted to the output shaft 112.

  When the rotation of the input shaft 111 is transmitted to the output shaft 112, the gear meshing between the input shaft 111 and the counter shaft 113 and the gear meshing between the counter shaft 113 and the output shaft 112 are changed. The rotational speed of the output shaft 112 can be changed stepwise with respect to the rotational speed of the input shaft 111. Further, the rotation of the input shaft 111 can be directly transmitted to the output shaft 112 by directly meshing the gear 114 b of the input shaft 111 and the gear 114 f of the output shaft 112 without using the counter shaft 113.

  Hereinafter, the shifting operation of the manual transmission 100 will be described more specifically. When the gear 114f does not mesh with the gear 114b, the gear 114g does not mesh with the gear 114d, and the gear 114e meshes with the gear 114j, the driving force of the input shaft 111 is the gear 114a, the gear 114h, the gear 114j, and It is transmitted to the output shaft 112 via the gear 114e. This is the first speed, for example.

  When the gear 114g meshes with the gear 114d and the gear 114e does not mesh with the gear 114j, the driving force of the input shaft 111 is transmitted via the gear 114a, the gear 114h, the gear 114i, the gear 114c, the gear 114d, and the gear 114g. It is transmitted to the output shaft 112. This is the second speed, for example.

  When the gear 114f meshes with the gear 114b and the gear 114e does not mesh with the gear 114j, the input shaft 111 is directly coupled to the output shaft 112 by meshing with the gear 114b and the gear 114f, and the driving force of the input shaft 111 is Directly transmitted to the output shaft 112. This is the third speed, for example.

  As described above, the manual transmission 100 includes the deep groove ball bearing 1 in order to rotatably support the input shaft 111 and the output shaft 112 as rotating members with respect to the housing 115 disposed adjacent thereto. Yes. The manual transmission 100 also includes a thrust needle roller bearing 2 for rotatably supporting a counter shaft 113, which is a rotating member, with respect to a housing 115 disposed adjacent thereto. As described above, the deep groove ball bearing 1 and the thrust needle roller bearing 2 in the first embodiment can be used in the manual transmission 100. The deep groove ball bearing 1 and the thrust needle roller bearing 2 that can achieve both high pressure scar resistance and rolling fatigue life at a high level are manuals in which a high surface pressure is applied between the rolling elements and the raceway member. It is suitable for use in the transmission 100.

(Embodiment 3)
Next, another example of the application of the rolling bearing in the first embodiment will be described. Referring to FIGS. 8 and 9, differential 200 includes differential case 201, pinion gears 202a and 202b, sun gear 203, pinion carrier 204, armature 205, pilot clutch 206, electromagnet 207, rotor clutch ( Differential case) 208 and a cam 209.

  The inner teeth 201a provided on the inner periphery of the differential case 201 and each of the four pinion gears 202a mesh with each other, each of the four pinion gears 202a and each of the four pinion gears 202b mesh with each other, Each of the four pinion gears 202b and the sun gear 203 mesh with each other. The sun gear 203 is connected to the end of the left drive shaft 220 as the first drive shaft, so that the sun gear 203 and the left drive shaft 220 can rotate together. Further, each of the rotation shafts 202c of the pinion gear 202a and each of the rotation shafts 202d of the pinion gear 202b are held by the pinion carrier 204 so as to be able to rotate. The pinion carrier 204 is connected to the end portion of the right drive shaft 221 as the second drive shaft, so that the pinion carrier 204 and the right drive shaft 221 can rotate together.

  The electromagnet 207, the pilot clutch 206, the rotor clutch (difference case) 208, the armature 205, and the cam 209 constitute an electromagnetic clutch.

  The external teeth 201b of the differential case 201 are meshed with a gear of a ring gear (not shown), and the differential case 201 rotates by receiving power from the ring gear. When there is no differential between the left drive shaft 220 and the right drive shaft 221, the pinion gears 202a and 202b do not rotate, and the three members of the differential case 201, the pinion carrier 204, and the sun gear 203 rotate as a unit. To do. That is, power is transmitted from the ring gear to the left drive shaft 220 as indicated by arrow B, and power is transmitted from the ring gear to the right drive shaft 221 as indicated by arrow A.

  On the other hand, when resistance is applied to one of the left drive shaft 220 and the right drive shaft 221, for example, the left drive shaft 220, resistance is applied to the sun gear 203 connected to the left drive shaft 220, and the pinion gears 202a and 202b Each rotates. Then, rotation of the pinion gears 202a and 202b accelerates the rotation of the pinion carrier 204, and a differential is generated between the left drive shaft 220 and the right drive shaft 221.

  Further, the electromagnetic clutch is energized when a certain level of differential occurs between the left drive shaft 220 and the right drive shaft 221, and a magnetic field is generated by the electromagnet 207. The pilot clutch 206 and the armature 205 are attracted to the electromagnet 207 by magnetic induction and generate friction torque. The friction torque is converted in the thrust direction by the cam 209. Then, the main clutch is pressed against the differential case 208 via the pinion carrier 204 by the friction torque converted in the thrust direction, thereby generating a differential limiting torque. The thrust needle roller bearing 2 receives a reaction force in the thrust direction generated by the cam 209 and transmits this reaction force to the differential case 208. As a result, a thrust force doubled by the cam 209 proportional to the friction torque is generated. Thus, the electromagnet 207 can control only the pilot clutch 206, amplify the torque by the boost mechanism, and can arbitrarily control the friction torque.

  Here, between the cam 209 and the differential case 208, the thrust needle roller bearing 2 in the first embodiment is disposed. Further, the deep groove ball bearing 1 according to the first embodiment is disposed between the differential case 208 and a member disposed on the outer peripheral side of the differential case 208. Thus, the deep groove ball bearing 1 and the thrust needle roller bearing 2 in the first embodiment can be used in the differential 200. The deep groove ball bearing 1 and the thrust needle roller bearing 2 capable of achieving both high pressure scar resistance and rolling fatigue life at a high level are differentials in which a high surface pressure is applied between the rolling elements and the raceway member. Suitable for use within 200.

  Experiments were conducted to investigate the effects of heat treatment conditions on the characteristics of bearing parts. First, a flat plate made of JIS standard SUJ2 was prepared, preheated at 800 ° C. for 1 hour, then heated to 850 ° C. in an atmosphere in which ammonia gas was added to RX gas and kept for 4 hours for carbonitriding. Thereafter, the flat plate was quenched and hardened by being immersed in the quenching oil as it was from 850 ° C. which is the heating temperature in the carbonitriding treatment. Further, the flat plate was tempered at various temperatures. A SUJ2 standard rolling bearing steel ball having a diameter of 19.05 mm was pressed against the obtained flat plate with a load of 3.18 kN (maximum contact surface pressure 4.4 GPa), held for 10 seconds, and then unloaded. And the pressure dent resistance was investigated by measuring the depth of the dent formed on the flat plate by pressing the steel ball. Further, the surface hardness of the same test piece was measured with a Rockwell hardness meter. FIG. 10 shows the result of investigation of the pressure scar resistance, and FIG. 11 shows the result of measurement of hardness.

  Referring to FIGS. 10 and 11, the surface hardness decreases as the tempering temperature increases, while the indentation depth has a minimum value. Specifically, by setting the tempering temperature to 240 ° C. or more and 300 ° C. or less, the indentation depth is 0.2 μm or less. From this point of view, it can be said that the tempering temperature is preferably 240 ° C. or more and 300 ° C. or less from the viewpoint of improving the pressure dent resistance.

Here, it is considered that the optimum value of the tempering temperature is determined as follows. When quenching is performed, carbon is in a solid solution state in the steel substrate. On the other hand, when tempering is performed, a part of the carbon solid-dissolved in the substrate is precipitated as a carbide (for example, Fe ₃ C). At this time, the higher the temperature of the tempering treatment, the lower the contribution of solid solution strengthening to the yield strength of the steel and the greater the contribution of precipitation strengthening. Then, by performing the tempering process in a temperature range of 240 ° C. or more and 300 ° C. or less, the balance of these strengthening mechanisms becomes optimal, and the yield strength takes a maximum value, so that the pressure-proof scar resistance is particularly high.

  In addition, the reason why the indentation has the maximum value despite the monotonously decreasing surface hardness measured based on the deformation of the steel by pressing the indentation as in the case of the indentation depth measurement is as follows. It is considered to be street.

FIG. 12 is a diagram showing the relationship between the true stress and the true strain at each tempering temperature of a tensile test piece (JIS Z2201 No. 4 test piece) subjected to a treatment in which only the carbonitriding process is omitted in the heat treatment for the flat plate. . FIG. 12 is a true stress-true strain diagram modeled by an n-th power hardening elastoplastic material. The characteristics are different according to the following equation at the boundary of σ _Y yield stress.

Here, σ is the true stress, E is the Young's modulus, ε is the true strain, K is the plastic coefficient, n is the work hardening index, and σ _Y is the yield stress. However, the Young's modulus E was measured by a resonance method, and the processing effect index n and the composition coefficient K were measured by a tensile test. Then, these were substituted into the above two formulas, and the intersection was defined as σ _Y.

  Here, the true strain level in the measurement of the indentation depth corresponds to the region α in FIG. 12, whereas the true strain level in the hardness measurement corresponds to the region β or more in FIG. And if the yield point in the area | region (alpha) corresponding to the measurement area | region of an indentation depth is confirmed with reference to FIG. 13, the yield point becomes high in the range whose tempering temperature is 240 degreeC-300 degreeC, and than this In the case of low temperature, the yield point is lowered. On the other hand, referring to FIG. 12, it can be seen that, in the region β corresponding to the surface hardness measurement region, when the same strain amount is applied, a larger stress is required as the tempering temperature is lowered. Due to such a phenomenon, although the hardness is lowered as compared with the case where the tempering temperature is 180 ° C. to 220 ° C., the tempering temperature is set to 240 ° C. to 300 ° C. It is thought to improve.

  In addition to the tempering temperature, the amount of retained austenite on the surface, depth of indentation, life, ring crushing strength, and aging rate were investigated for the test pieces heat-treated under conditions in which the surface nitrogen concentration and the quenching temperature were changed.

Here, the indentation depth was measured in the same manner as described above. The case where the indentation depth was less than 0.2 μm was evaluated as B, the case where the indentation depth was 0.2 to 0.4 μm was evaluated as C, and the case where the indentation depth was 0.4 μm or more was evaluated as D. The service life of the bearing is used for the transmission under the condition that the oil film parameter becomes 0.5 under clean oil lubrication after forming the indentation on the raceway surface under the same conditions as the measurement of the indentation depth. This was carried out by simulating the loading conditions. The life of a test piece having a quenching temperature of 850 ° C., a tempering temperature of 240 ° C., and a surface nitrogen content of 0.4% by mass is defined as a reference (B). The case was rated as D. The ring crushing strength was evaluated by preparing a ring having an outer diameter of 60 mm, an inner diameter of 54 mm, and a width of 15, and compressing the ring with a flat plate in the radial direction, and investigating the load at which cracks occurred. The case where the load at the time of a crack generation was 5000 kgf or more was evaluated as A, the case where it was 3500-5000 kgf was evaluated as B, and the case where it was less than 3500 kgf was evaluated as D. Moreover, the secular change rate was evaluated by holding the test piece at 230 ° C. for 2 hours and measuring the dimensional change amount of the outer diameter before the heat treatment. Where the amount of change is of 10.0 × 10 ⁵ or less A, B the case of ^{10.0 × 10 5 ~30.0 × 10 5} , the case of ^{30.0 × 10 5 ~90.0 × 10 5} C The case of 90.0 × 10 ⁵ or more was evaluated as D. The test results are shown in Table 1.

  With reference to Table 1, in the test piece which satisfy | fills all the conditions of surface nitrogen concentration 0.25-0.5 mass%, quenching temperature 820-860 degreeC, and tempering temperature 240-300 degreeC, all the said Excellent evaluation was obtained for the items.

  In the above embodiment, the deep groove ball bearing and the thrust needle roller bearing have been described as examples of the rolling bearing including the bearing component of the present invention. However, the rolling bearing of the present invention is not limited to this, and the tapered roller bearing and the deep groove The bearing component of the present invention can be applied to various types of rolling bearings such as a ball bearing, an angular ball bearing, and a tandem angular ball bearing. In addition, the application of the rolling bearing of the present invention is exemplified by transmission and differential, but the application of the rolling bearing of the present invention is not limited to this, and can be applied to various machines. It is particularly suitable for applications that require traceability.

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

  The bearing parts, rolling bearings, and manufacturing methods thereof of the present invention are particularly advantageously applied to bearing parts, rolling bearings, and manufacturing methods thereof that are required to achieve both a high level of scratch resistance and rolling fatigue life. Can be done.

  1 deep groove ball bearing, 2 thrust needle roller bearing, 11 outer ring, 11A outer ring rolling surface, 11B, 12B, 13B, 21B, 23B nitrogen-enriched layer, 11C, 12C, 13C, 21C, 23C inside, 12 inner ring, 12A inside Rolling surface, 13 balls, 13A Ball rolling surface, 14, 24 Cage, 21 Track, 21A Rolling surface, 23 Needle roller, 23A Rolling contact surface, 100 Manual transmission, 111 Input shaft, 112 Output Shaft, 113 Countershaft, 114a-k gear, 115 housing, 120A, 120B Rolling bearing, 200 differential, 201 differential case, 201a internal tooth, 201b external tooth, 202a-b pinion gear, 202c-d rotating shaft, 203 sun gear, 204 Pinion carry , 205 armature 206 pilot clutch, 207 electromagnet 208 differential case, 209 cam, 220 left drive shaft, 221 the right drive shaft.

Claims (10)

0.90% by mass or more and 1.05% by mass or less of carbon, 0.15% by mass or more and 0.35% by mass or less of silicon, 0.01% by mass or more and 0.50% by mass or less of manganese, Containing 30% by weight or more and 1.65% by weight or less chromium, comprising a hardened and hardened steel consisting of the remaining impurities,
The nitrogen concentration in the contact surface that is a surface in contact with another component is 0.25% by mass or more,
The bearing component whose residual austenite amount in the said contact surface is 6 volume% or more and 12 volume% or less.   The bearing component according to claim 1, wherein the contact surface has a hardness of 60.0 HRC or more.   The bearing component according to claim 1, wherein the hardness of the contact surface is 64.0 HRC or less. A track member;
A plurality of rolling elements arranged in contact with the raceway member,
At least any one of the said track member and the said rolling element is a rolling bearing which is a bearing component of any one of Claims 1-3.   The rolling bearing according to claim 4, wherein a rotating member that rotates in a differential or a transmission is rotatably supported with respect to another member that is disposed adjacent to the rotating member. 0.90% by mass or more and 1.05% by mass or less of carbon, 0.15% by mass or more and 0.35% by mass or less of silicon, 0.01% by mass or more and 0.50% by mass or less of manganese, Containing 30% by mass or more and 1.65% by mass or less of chromium, and forming a molded member by molding steel composed of the remaining impurities;
Carbonitriding the molded member; and
A step of quench hardening the carbonitrided molded member;
A step of tempering the molded member subjected to quench hardening;
Forming a contact surface that is a surface in contact with another component by processing the molded member that has been tempered,
In the step of carbonitriding the molded member, the molded member is carbonitrided so that the nitrogen concentration of the contact surface is 0.25% by mass or more in the step of forming the contact surface,
In the step of tempering the molded member, the forming member is tempered in the step of forming the contact surface such that the amount of retained austenite on the contact surface is 6% by volume or more and 12% by volume or less. A manufacturing method for parts.   The method for manufacturing a bearing part according to claim 6, wherein in the step of tempering the molded member, the molded member is tempered in a temperature range of 240 ° C. or higher and 300 ° C. or lower.   The method for manufacturing a bearing part according to claim 6 or 7, wherein in the step of quenching the molded member, the molded member is quenched by being rapidly cooled from a temperature range of 860 ° C or lower.   9. The production of a bearing part according to claim 6, wherein in the step of quenching the molded member, the molded member is quenched by being rapidly cooled from a temperature range of 820 ° C. or higher. Method. A rolling bearing manufacturing method comprising:
Preparing a raceway member;
Preparing a plurality of rolling elements;
A step of assembling the rolling bearing by combining a plurality of the rolling elements so as to contact the raceway member,
At least one of the step of preparing the race member and the step of preparing the plurality of rolling elements is performed using the method for manufacturing a bearing component according to any one of claims 6 to 9. A method of manufacturing a rolling bearing.

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