JP2013119932A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing capable of compatibly attaining the indentation resistance and the rolling fatigue life at high level while ensuring the easy obtainability of a material.SOLUTION: A deep groove ball bearing 1 includes an outer ring 11, an inner ring 12, a plurality of balls 13, and a seal member 17. At least any one of the outer ring 11, the inner ring 12 and the plurality of balls 13 is formed of quench-hardened steel having the composition consisting of 0.90-1.05% carbon, 0.15-0.35% silicon, 0.01-0.50% manganese, 1.30-1.65% chromium, and the remainder impurities. The rolling bearing is a high-strength bearing component in which the nitrogen concentration at bearing contact surfaces 11A, 12A, 13A is ≥0.25 mass%, and the residual austenite amount is ≤6-12 vol%. By rotating the inner ring 12 with respect to the outer ring 11, a seal lip part 17A is worn, and the inner ring 12 is not brought into contact with the seal lip part 17A.

Description

  The present invention relates to a rolling bearing, and more particularly to a rolling bearing capable of achieving both high pressure scar resistance and rolling fatigue life at a high level.

  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

  For example, in rolling bearings that need to support large loads 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 extended. At the same time, pressure resistance (hardness of formation of the impression 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 rolling bearing capable of.

  A rolling bearing according to the present invention has a first raceway having a first rolling surface and a second rolling surface, and is arranged such that the second rolling surface faces the first rolling surface. A second race ring, a plurality of rolling elements that are in contact with the first rolling surface and the second rolling surface at a rolling contact surface, and arranged side by side on an annular raceway; a first race ring and a second race track; And a seal member disposed so as to close a bearing space which is a space sandwiched between the rings. At least one of the first track ring, the second track ring, and the rolling element is 0.90 mass% or more and 1.05 mass% or less of carbon and 0.15 mass% or more and 0.35 mass% or less of silicon. And containing 0.01 mass% or more and 0.50 mass% or less of manganese, and 1.30 mass% or more and 0.65 mass% or less of chromium, and comprising a hardened and hardened steel composed of the remaining impurities, The nitrogen concentration in the bearing contact surface which is the first rolling surface, the second rolling surface or the rolling contact surface is 0.25% by mass or more, and the residual austenite amount in the bearing contact surface is 6% by volume or more and 12% by volume or less. A high-strength bearing component. The seal member has one end fixed to one of the first and second race rings, and the other end of the seal lip is in contact with the other one of the first and second race rings. . The seal lip portion is worn by rotating the second race ring in the circumferential direction relative to the first race ring, and the other of the first race ring and the second race ring does not contact the seal lip portion. The seal lip portion is made of a high wear material so that the contact state between the other one of the first race ring and the second race ring and the seal lip portion is light contact that can be regarded as substantially zero. ing.

  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 assuming the use of steel of the component composition, the nitrogen concentration at the bearing contact surface is increased to 0.25% by mass or more, and the rolling fatigue life is extended by quenching and hardening. Can do. Here, when the amount of retained austenite is not particularly adjusted, the amount of retained austenite at the bearing 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 bearing contact surface is preferably 6% by volume or more.

  On the other hand, the high-strength bearing component constituting the rolling bearing of the present invention employs a JIS standard SUJ2 equivalent material that is easily available in various countries as a material, and the nitrogen concentration at the bearing contact surface is 0.25% by mass or more, The amount of retained austenite is 6 vol% or more and 12 vol% or less.

  Furthermore, in order to extend the rolling fatigue life, particularly the rolling fatigue life in an environment where foreign matter is mixed, it is effective to arrange a contact-type seal member that suppresses the entry of foreign matter. However, when a general contact-type seal member is employed, there arises a problem that the rotational torque of the rolling bearing increases. On the other hand, in the rolling bearing of the present invention, the seal lip portion that comes into contact with the bearing ring is easily worn by the rotation of the bearing ring and does not come into contact with the initially contacted bearing ring, or It is made of a high wear material that is in a light contact state with a contact pressure that can be regarded as substantially zero. As a result, an increase in rotational torque can be suppressed while intrusion of foreign matter is suppressed. As a material of the seal lip portion, for example, rubber, resin or the like can be employed.

  As described above, the rolling bearing of the present invention includes a high-strength bearing component that achieves both a high level of pressure resistance and a rolling fatigue life as a component while ensuring the availability of materials, and rotational torque. There is provided a seal member capable of further improving the rolling fatigue life while suppressing the increase of the. As a result, according to the rolling bearing of the present invention, it is possible to provide a rolling bearing that achieves both high pressure scar resistance and rolling fatigue life at a high level.

  From the viewpoint of further improving the pressure scar resistance, the amount of retained austenite on the bearing contact surface may be 10% or less. Further, if the nitrogen concentration on the bearing contact surface exceeds 0.5 mass%, the cost for intruding nitrogen into the steel increases, and it becomes difficult to adjust the amount of retained austenite to a desired range. Therefore, the nitrogen concentration in the bearing contact surface is preferably 0.5% by mass or less, and may be 0.4% by mass or less.

  In the rolling bearing, at least the first bearing ring and the second bearing ring may be the high-strength bearing component. Scratch resistance becomes a problem particularly in a raceway. Therefore, when at least one of the bearing rings is made of the high-strength bearing component, the pressure-proof scar resistance of the rolling bearing is more reliably improved.

  In the rolling bearing, the rolling element may be a ball. By using balls for the rolling elements, the rotational torque of the rolling bearing is suppressed. On the other hand, when balls are used for the rolling elements, the static load rating of the bearing is significantly reduced as compared with the roller bearing, so that the pressure scar resistance is a particular problem. On the other hand, the rolling bearing of the present invention includes the above-described high-strength bearing component that is excellent in pressure proof marks. Therefore, by adopting a ball as a rolling element in the rolling bearing of the present invention, it is possible to provide a rolling bearing with a high level of pressure resistance and rolling fatigue life and a reduced rotational torque.

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

  In the rolling bearing, the bearing contact surface may have a hardness of 64.0 HRC or less. When the hardness of the bearing contact surface whose 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 residual austenite to 12% by volume or less. By setting the hardness of the bearing 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 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. Therefore, 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.

  In the above rolling bearing, when the rolling element is pressed against either the first race ring or the second race ring so that the maximum contact surface pressure is 4.4 GPa, either the first race ring or the second race ring is selected. It is preferable that the depth of the indentation formed is 0.5 μm or less. By improving the pressure resistance to this level, it is possible to provide a rolling bearing that can be used in a particularly severe environment. Further, the depth of the indentation is more preferably 0.3 μm or less, and further preferably 0.2 μm or less.

  As is apparent from the above description, according to the rolling bearing of the present invention, it is possible to achieve both high pressure scar resistance and rolling fatigue life at a high level while ensuring the availability of materials. Can be provided.

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 fragmentary sectional view for demonstrating the state after the rotation start of a deep groove ball bearing. 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, a ball 13 as a plurality of rolling elements that are bearing parts, a cage 14, and a seal member 17. 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. Moreover, the ball | bowl rolling surface 13A (surface of the ball | bowl 13) as a rolling-element rolling surface (rolling contact surface) is formed in the some ball | bowl 13. As shown in FIG. The outer ring rolling surface 11A, the inner ring rolling surface 12A, and the ball rolling surface 13A are bearing 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. The seal member 17 is disposed so as to close a bearing space that is a space sandwiched between the outer ring 11 and the inner ring 12, and suppresses entry of foreign matter into the bearing space. 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 bearing contact surfaces, the nitrogen enriched layers 11B and 12B having a higher nitrogen concentration than the inner portions 11C, 12C, and 13C. , 13B are formed. The nitrogen concentration in the outer ring rolling surface 11A, the inner ring rolling surface 12A, and the ball rolling surface 13A as the bearing 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 is easily available in various countries around 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 high-strength bearing parts capable of achieving both a high level of scratch resistance and a rolling fatigue life while ensuring the availability of materials. Yes.

  Referring to FIG. 2, the seal member 17 is made of metal and has an annular shape, and an elastic portion 15 that is an elastic member made of resin or rubber disposed so as to surround the metal core 16. Including. With such a structure, the seal member 17 can be elastically deformed in the elastic portion 15 contacting the outer ring 11 and the inner ring 12 while maintaining a desired rigidity by the cored bar 16. The seal member 17 is fixed by fitting its outer peripheral portion into a seal mounting groove 11E formed on the inner peripheral surface of the outer ring 11. A seal lip portion 17 </ b> A that is an inner peripheral side end portion of the seal member 17 is in contact with the outer peripheral surface of the inner ring 12.

  The seal lip portion 17A is made of a high wear material such as rubber that easily wears. Therefore, referring to FIG. 2, when the inner ring 12 is rotated relative to the outer ring 11, the seal lip portion 17A is worn immediately after the start of rotation, and the inner ring 12 and the seal lip portion as shown in FIG. It will be in the state which 17A does not contact. As a result, the seal lip portion 17A and the outer peripheral surface of the inner ring 12 face each other with a minute gap therebetween. Thereby, the penetration | invasion of the foreign material to the inside of a bearing is reduced, suppressing the raise of rotational torque. As a result, an increase in the rotational torque of the deep groove ball bearing 1 is suppressed, and the rolling fatigue life, particularly in a foreign matter mixed environment, is extended. In the above description, the case where the seal lip portion 17A and the outer peripheral surface of the inner ring 12 are not in contact with each other has been described. However, the contact pressure between the inner ring 12 and the seal lip portion 17A is light enough to be regarded as being substantially zero. It may be reduced to such an extent that it comes into contact.

  As described above, the deep groove ball bearing 1 according to the present embodiment is a high-strength bearing component capable of achieving both high pressure scar resistance and rolling fatigue life at a high level while ensuring the availability of materials. The outer ring 11, the inner ring 12, and the balls 13 are provided, and a seal member 17 that reduces the intrusion of foreign matter into the bearing while suppressing an increase in rotational torque is provided. As a result, the deep groove ball bearing 1 according to the present embodiment is a rolling bearing that achieves both high pressure scar resistance and rolling fatigue life at a high level.

  In the above embodiment, the case where all of the outer ring 11, the inner ring 12 and the ball 13 are made of the high-strength bearing component has been described. However, at least one of the outer ring 11, the inner ring 12 and the ball 13 is described. By using the above-described high-strength bearing parts, it is possible to achieve both high pressure resistance and rolling fatigue life at a high level.

  In addition, since the pressure resistance is a problem particularly in the raceway, it is preferable that either one of the outer ring 11 or the inner ring 12, preferably both are the high-strength bearing parts. Further, although the rolling element may be a roller, from the viewpoint of reducing the rotational torque, a ball is employed instead of the roller for a portion where the roller is employed as in the above embodiment. Is preferred. By adopting a ball bearing in which the rolling element is a ball, the static load rating of the bearing is significantly reduced compared to the roller bearing. Therefore, in particular, the pressure resistance of the bearing ring becomes a problem, but the bearing ring (outer ring 11, When the inner ring 12) is the above-described high-strength bearing component, it is possible to reduce the rotational torque while maintaining the pressure proof resistance at a sufficient level.

  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 bearing 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.

  Next, the bearing component and the rolling bearing manufacturing method in the present embodiment will be described. Referring to FIG. 4, 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 3 are performed by performing processing such as forging and turning on the steel bars and steel wires prepared in step (S10), for example. A molded member formed into a shape such as a ball 13 is 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 bearing 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, Inner ring rolling surface 12A and ball rolling surface 13A are formed. As the finishing process, for example, a grinding process can be performed. Through the above steps, the outer ring 11, the inner ring 12, the ball 13, and the like, which are bearing parts in the present embodiment, are completed.

  Furthermore, an assembly process is performed as a process (S70). In this step (S70), the seal member including the outer ring 11, the inner ring 12, and the ball 13 produced in steps (S10) to (S60), a separately prepared cage 14, and a seal lip portion 17A made of a high wear material. 17 or the like is combined to assemble the deep groove ball bearing 1 in the above embodiment. Thereby, the manufacturing method of the rolling bearing in this Embodiment is completed.

  Here, in the step (S30), the nitrogen concentration of 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 is the bearing contact surface by the finishing process in the subsequent step (S60). Is subjected to a carbonitriding process so that the amount becomes 0.25% by mass or more. That is, in consideration of the allowance in the step (S60), etc., the nitrogen enriched layer in which the nitrogen amount is adjusted so that the nitrogen concentration on the surface after completion of the bearing contact surface can be 0.25% by mass or more. 11B, 12B, and 13B are formed.

  Further, in the step (S50), the amount of retained austenite on 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 is the bearing contact surface by the finishing process in the subsequent step (S60). The molded member is tempered so as to be 6 volume% or more and 12 volume% or less. That is, taking into account the machining allowance in the step (S60), the residual austenite amount on the surface after completion of the bearing contact surface is 6 vol% or more and 12 vol% or less. The amount of austenite 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 scar resistance of the outer ring 11, inner ring 12, and ball 13 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. 5, 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. As described above, the deep groove ball bearing 1 in the first embodiment can be used in the manual transmission 100. The deep groove ball bearing 1 capable of achieving both high pressure scar resistance and rolling fatigue life at a high level is used in a manual transmission 100 in which high surface pressure is applied between the rolling elements and the raceway member. It is suitable for.

(Embodiment 3)
Next, another example of the application of the rolling bearing in the first embodiment will be described. Referring to FIGS. 6 and 7, 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, 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 in the first embodiment can be used in the differential 200. The deep groove ball bearing 1 capable of achieving both high pressure scar resistance and rolling fatigue life at a high level can be used in a differential 200 in which a high surface pressure is applied between the rolling elements and the raceway member. Is preferred.

  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. 8 shows the results of the investigation of the pressure scar resistance, and FIG. 9 shows the results of the hardness measurement.

  Referring to FIGS. 8 and 9, 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. 10 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. 10 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. 10, whereas the true strain level in the hardness measurement corresponds to the region β in FIG. And when the yield point in the area | region (alpha) corresponding to the measurement area | region of an indentation depth is confirmed with reference to FIG. 11, the tempering temperature becomes high in the range of 240 degreeC-300 degreeC, and is higher than this. In the case of low temperature, the yield point is lowered. On the other hand, referring to FIG. 10, it can be seen that, in the region β corresponding to the surface hardness measurement region, if 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 45 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, a deep groove ball bearing has been described as an example of a rolling bearing including the bearing component of the present invention. However, the rolling bearing of the present invention is not limited to this, and a tapered roller bearing, a deep groove ball bearing, and an angular ball. The bearing component of the present invention can be applied to various types of rolling bearings such as a 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 rolling bearing of the present invention can be particularly advantageously applied to a rolling bearing that is required to achieve both high pressure scar resistance and rolling fatigue life at a high level.

  DESCRIPTION OF SYMBOLS 1 Deep groove ball bearing, 2 Thrust needle roller bearing, 11 Outer ring, 11A Outer ring rolling surface, 11B, 12B, 13B Nitrogen enriched layer, 11C, 12C, 13C Inside, 12 Inner ring, 12A Inner ring rolling surface, 13 Ball, 13A Ball rolling surface, 14 Cage, 15 Elastic part, 16 Metal core, 17 Seal member, 100 Manual transmission, 111 Input shaft, 112 Output shaft, 113 Counter shaft, 114a-k gear, 115 Housing, 120A, 120B Rolling bearing , 200 differential, 201 differential case, 201a internal teeth, 201b external teeth, 202a-b pinion gear, 202c-d rotating shaft, 203 sun gear, 204 pinion carrier, 205 armature, 206 pilot clutch, 207 electromagnet, 208 Differential case, 209 cam, 220 Left drive shaft, 221 Right drive shaft.

A rolling bearing according to the present invention has a first raceway having a first rolling surface and a second rolling surface, and is arranged such that the second rolling surface faces the first rolling surface. A second race ring, a plurality of rolling elements that are in contact with the first rolling surface and the second rolling surface at a rolling contact surface, and arranged side by side on an annular raceway; a first race ring and a second race track; And a seal member disposed so as to close a bearing space which is a space sandwiched between the rings. At least one of the first track ring, the second track ring, and the rolling element is 0.90 mass% or more and 1.05 mass% or less of carbon and 0.15 mass% or more and 0.35 mass% or less of silicon. And containing 0.01 mass% or more and 0.50 mass% or less of manganese, and 1.30 mass% or more and 1.65 mass% or less of chromium, comprising a hardened and hardened steel consisting of the remaining impurities, The nitrogen concentration in the bearing contact surface which is the first rolling surface, the second rolling surface or the rolling contact surface is 0.25% by mass or more, and the residual austenite amount in the bearing contact surface is 6% by volume or more and 12% by volume or less. A high-strength bearing component. The seal member has one end fixed to one of the first and second race rings, and the other end of the seal lip is in contact with the other one of the first and second race rings. . The seal lip portion is worn by rotating the second race ring in the circumferential direction relative to the first race ring, and the other of the first race ring and the second race ring does not contact the seal lip portion. The seal lip portion is made of a high wear material so that the contact state between the other one of the first race ring and the second race ring and the seal lip portion is light contact that can be regarded as substantially zero. ing.

Claims (7)

A first bearing ring having a first rolling surface;
A second raceway having a second rolling surface and disposed so that the second rolling surface faces the first rolling surface;
A plurality of rolling elements that are in contact with the first rolling surface and the second rolling surface at a rolling contact surface and arranged side by side on an annular track;
A seal member disposed so as to close a bearing space that is a space sandwiched between the first raceway and the second raceway,
At least one of the first track ring, the second track ring, and the rolling element is:
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 mass% or more and 0.65 mass% or less of chromium, and made of quench-hardened steel consisting of the remaining impurities,
The nitrogen concentration in the bearing contact surface which is the first rolling surface, the second rolling surface or the rolling contact surface is 0.25% by mass or more,
A high-strength bearing component in which the amount of retained austenite at the bearing contact surface is 6% by volume or more and 12% by volume or less,
The seal member has one end fixed to one of the first raceway and the second raceway, and the other end of the seal lip is the other of the first raceway and the second race. In contact with
The seal lip portion is worn by rotating the second race ring in the circumferential direction relative to the first race ring, and the other of the first race ring and the second race ring and the seal lip portion. So that the contact pressure between the other of the first raceway ring and the second raceway ring and the seal lip portion is a light contact that can be regarded as substantially zero. Rolling bearing with lip part made of high wear material.   The rolling bearing according to claim 1, wherein at least the first bearing ring and the second bearing ring are the high-strength bearing parts.   The rolling bearing according to claim 1, wherein the rolling element is a ball.   The rolling bearing according to claim 1, wherein the bearing contact surface has a hardness of 60.0 HRC or more.   The rolling bearing according to claim 1, wherein the bearing contact surface has a hardness of 64.0 HRC or less.   The rolling bearing according to any one of claims 1 to 5, 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.   When the rolling element is pressed against either the first race ring or the second race ring so that the maximum contact surface pressure is 4.4 GPa, the rolling element is applied to either the first race ring or the second race ring. The rolling bearing according to claim 1, wherein a depth of the formed indentation is 0.5 μm or less.

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