JP6023493B2 - Method of manufacturing bearing ring, bearing ring and rolling bearing - Google Patents

Description

  The present invention relates to a method for manufacturing a bearing ring, a bearing ring, and a rolling bearing, and more specifically, while suppressing the manufacturing cost of a quenching device, the quench hardening layer is formed along the rolling surface by induction hardening. Manufacturing method of bearing ring that can be uniformly formed over the entire length, rolling bearing bearing ring in which a hardened hardened layer is formed along the rolling surface by induction hardening, and rolling provided with the bearing ring It relates to bearings.

  Induction hardening may be employed as a hardening treatment for the rolling rings of rolling bearings made of steel. This induction hardening can simplify the equipment and heat treatment in a short time compared to the general quench hardening process in which the race is heated in the furnace and then immersed in a coolant such as oil. It has the advantage of becoming.

  However, in induction hardening, in order to simultaneously heat the annular region to be hardened and hardened along the raceway surface of the raceway, it is necessary to inductively heat the raceway so as to face the raceway surface. It is necessary to arrange an induction heating member such as a coil. For this reason, when quenching and hardening a large race, a large coil corresponding to that and a large-capacity power source corresponding to the coil are required, which increases the production cost of the quenching apparatus.

As a measure for avoiding such a problem, there is a case where moving quenching using a small induction heating coil is employed. In this moving quenching, high-frequency induction heating is performed using a coil that is arranged to face a part of the annular region to be heated of the race and moves relatively along the region, and is heated. By spraying a coolant such as water immediately after passing through the coil to the region, the region is sequentially hardened and hardened. However, when this moving quenching is simply adopted, the coil turns once from the quenching start area (quenching start area) and finally quenches the area where quenching should be performed (quenching end area). When hardening, the quenching start area and the quenching end area partially overlap. For this reason, there is a concern about occurrence of quench cracks due to re-quenching of the overlapped region. The region adjacent to the overlapping region, since it is tempered by being heated to a temperature of less than ₁ point A along with the heating of the quenching termination region, there is a possibility that the hardness is lowered. Therefore, when moving quenching is employed, it is common to take measures to leave a region (soft zone) where quenching is not performed between the quenching start region and the quenching end region. This soft zone has low yield strength due to low hardness, and insufficient wear resistance. Therefore, when a soft zone is formed on the race, it is necessary to consider that the soft zone does not become a load region.

  On the other hand, after carrying out the above moving quenching to form a soft zone, a method has been proposed in which a region corresponding to the soft zone is excised and a hardened plug body is fitted in the region (for example, , See Patent Document 1). Thereby, it can avoid that the soft zone with low hardness remains.

  In addition, a method of avoiding the formation of a soft zone by using two coils that move in opposite directions in the circumferential direction of the raceway has been proposed (see, for example, Patent Document 2). In this method, the quenching is started in a state where the two coils are arranged adjacent to each other, and the quenching is finished at a position where the two coils meet again, thereby avoiding the formation of a soft zone and re-quenching. It is also possible to avoid the occurrence of a region to be generated.

JP-A-6-17823 JP-A-6-2003326

  However, the method disclosed in Patent Document 1 has a problem that the number of man-hours for manufacturing the race is significantly increased. Further, in the method disclosed in Patent Document 2, the residual stress accompanying quench hardening is concentrated in the region that is finally quenched, and there is a concern about the occurrence of heat treatment distortion and quench cracking. In addition, with the diversification of applications of rolling bearings, bearing parts and rolling bearings are required to have durability in various environments.

  The present invention has been made in order to solve the above-described problems, and its purpose is to suppress the production cost of the quenching apparatus and to completely cure the quench hardened layer along the rolling surface by induction quenching. A method of manufacturing a bearing ring that can be formed uniformly over the circumference and that can produce a highly durable bearing ring, and a hardened hardened layer is formed along the rolling surface over the entire circumference by induction hardening. It is an object of the present invention to provide a bearing ring of a rolling bearing that is formed and has high durability, and a rolling bearing including the bearing ring.

The method for manufacturing a bearing ring according to the present invention is a method for manufacturing a bearing ring for a rolling bearing. The method of manufacturing this bearing ring includes 0.43% to 0.65% carbon, 0.05% to 0.14% silicon, and 0.60% to 1.10%. % Of manganese, 0.30% by mass or more and 1.20% by mass or less of chromium, and 0.15% by mass or more and 0.75% by mass or less of molybdenum, and the balance iron and impurities. And an induction heating member that is arranged to face a part of the annular region that is to be a rolling surface of the race ring in the molded body, and for induction heating the induction body. A step of forming an annular heating region heated to a temperature of at least _one point A on the formed body by relatively rotating along the direction, and a step of simultaneously cooling the entire heating region to a temperature of not more than the _MS point And.

In the method for manufacturing a raceway ring according to the present invention, the induction heating member arranged so as to face a part of the annular region to be a rolling surface relatively rotates along the circumferential direction, thereby forming a molded body. A heating region is formed. Therefore, it is possible to employ a small induction heating member with respect to the outer shape of the race. As a result, the manufacturing cost of the quenching device can be suppressed even when a large raceway is quenched and hardened. In the method for manufacturing a bearing ring according to the present invention, the entire heating region is simultaneously cooled to a temperature below the _MS point. Therefore, it is possible to simultaneously form a hardened hardened layer along the rolling surface over the entire circumference, and the residual stress is suppressed from being concentrated in a part of the region.

  In addition, at present, where rolling bearings are used in a wide variety of applications, the failure mode of rolling bearings has also changed. For example, peeling caused by hydrogen embrittlement (hereinafter, hydrogen brittle peeling) may occur (for example, Tamada). Kenji et al., “A new type of microstructural change in electrical and auxiliary bearings”, NTN TECHNIC REVIEW, 1992, No. 61, p29-35). Hydrogen embrittlement debonding is characterized in that it takes place in a much shorter time than usual, and a non-directional fatigue structure is formed around the delamination start point. Even now, the mechanism of its occurrence has not been elucidated. However, hydrogen significantly reduces the fatigue strength of steel, and the life becomes shorter as the hydrogen storage amount increases. (E.g., Y. Matsubara and H. Hamada, "A Novel Method to Evaluate the Inflation of the Fraction of Hydrogen in St.," p153-166).

  On the other hand, in the method for manufacturing a bearing ring of the present invention, it is possible to ensure sufficient quenching hardness and hardenability while suppressing hydrogen embrittlement separation by reducing Si (silicon). Steel having a component composition is adopted as a material. Thus, according to the method of manufacturing the raceway of the present invention, while suppressing the production cost of the quenching device, the quench hardening layer is uniformly formed over the entire circumference along the rolling surface by induction quenching, And the manufacturing method of the bearing ring which can manufacture the bearing ring which has high durability can be provided.

  Here, the reason why the component range of steel constituting the formed body, that is, the component range of steel constituting the manufactured race is limited to the above range will be described.

Carbon: 0.43 mass% or more and 0.65% mass% or less The carbon content greatly affects the hardness of the raceway of the raceway after quench hardening. If the carbon content of the steel constituting the formed body (bearing ring) is less than 0.43% by mass, it will be difficult to impart sufficient hardness to the rolling surface after quench hardening. On the other hand, when the carbon content exceeds 0.65% by mass, there is a concern about generation of cracks (quenching cracks) during quench hardening. Therefore, the carbon content is set to 0.43% by mass or more and 0.65% by mass or less. In order to more reliably suppress the occurrence of burning cracks while more surely imparting sufficient hardness to the rolling surface, the carbon content of the steel may be 0.56 mass% or more and 0.64 mass% or less. It is preferably 0.60% by mass or more and 0.64% by mass or less, more preferably 0.62% by mass or more and 0.64% by mass or less.

Silicon: 0.05 mass% or more and 0.14 mass% or less Silicon contained in steel is used as a deoxidizing element during steelmaking, and refractory in a blast furnace contains silicon dioxide, which is steel. Therefore, it is not common to reduce the silicon content in bearing steel. Further, silicon has a function of improving the hardenability of the steel and improving the temper softening resistance. For this reason, bearing steels with increased silicon content have been developed. However, in the present invention, the silicon content is reduced to 0.14% by mass or less from the viewpoint of suppressing hydrogen brittle exfoliation. On the other hand, if the silicon used as a deoxidizing element during steelmaking is reduced to less than 0.05% by mass as described above, the manufacturing cost of steel increases. Therefore, the silicon content is set to 0.05% by mass or more.

Manganese: 0.60% by mass or more and 1.10% by mass or less Manganese contributes to improvement of hardenability of steel. If the manganese content is less than 0.60% by mass, this effect cannot be sufficiently obtained. On the other hand, if the manganese content exceeds 1.10% by mass, the hardness of the material before quenching increases, and the workability in cold working decreases. Therefore, manganese content was made into 0.60 mass% or more and 1.10 mass% or less. In order to suppress a decrease in cold workability while ensuring higher hardenability, the manganese content of the steel is preferably 0.70 mass% or more and 1.00 mass% or less, 0.85 mass% % Or more and 0.95% by mass or less is more preferable.

Chromium: 0.30% by mass or more and 1.20% by mass or less Chromium contributes to improvement of hardenability of steel. If the chromium content is less than 0.30% by mass, this effect cannot be sufficiently obtained. On the other hand, when the chromium content exceeds 1.20% by mass, there arises a problem that the material cost increases. Therefore, the chromium content is set to 0.30% by mass or more and 1.20% by mass or less. From the viewpoint of reducing raw material costs while ensuring higher hardenability, the chromium content of the steel is preferably 0.70% by mass or more and 0.90% by mass or less, and 0.70% by mass or more and 0.0. More preferably, it is 80 mass% or less.

Molybdenum: 0.15 mass% or more and 0.75 mass% or less Molybdenum also contributes to improving the hardenability of the steel. If the molybdenum content is less than 0.15% by mass, this effect cannot be sufficiently obtained. On the other hand, when the molybdenum content exceeds 0.75% by mass, there arises a problem that the material cost increases. Therefore, the molybdenum content is set to 0.15 mass% or more and 0.75 mass% or less. From the viewpoint of reducing raw material costs while ensuring higher hardenability, the molybdenum content of the steel is preferably 0.25 mass% or more and 0.35 mass% or less, and preferably 0.25 mass% or more and 0.0. It is particularly preferably 30% by mass or less, more preferably 0.25% by mass or more and 0.27% by mass or less.

  In the method for manufacturing the bearing ring, a step of performing a tempering treatment on the molded body may be further included before the step of forming the heating region.

In a raceway ring that is manufactured by partially quenching and hardening the region including the rolling surface by induction hardening, it has a hardness that can secure a predetermined strength even in a region that is not hardened (non-hardened region). Need to be. On the other hand, by carrying out the tempering treatment before induction hardening, it is possible to easily impart an appropriate hardness to the non-cured region. Here, "tempering treatment", after the entire shaped body and held heated above the A ₁ transformation point of the quenching temperature range predetermined time, the molded body is cooled to a temperature below M _S point in terms of the quenching treatment, including a process for tempering treatment by the molded body is heated to a tempering temperature range below the a ₁ transformation point for a predetermined time.

  The method for manufacturing a bearing ring may further include a step of performing a normalizing process on the molded body before the step of forming the heating region. Thereby, when the intensity | strength requested | required of a non-hardening area | region is comparatively low, appropriate hardness can be easily provided to a non-hardening area | region.

  In the step of performing the normalizing process, the shot blasting process may be performed while the molded body is cooled by spraying hard particles together with gas on the molded body.

  Thus, the shot blasting process can be performed simultaneously with the gust cooling at the normalizing process. Therefore, the scale generated in the surface layer portion of the compact is removed by the heating of the normalizing process, and the deterioration of the characteristics of the raceway due to the generation of the scale and the decrease of the thermal conductivity due to the generation of the scale are suppressed.

  In the method for manufacturing a race, the induction heating member may relatively rotate two or more times along the circumferential direction of the molded body in the step of forming the heating region. Thereby, the dispersion | variation in the temperature in the circumferential direction of a rolling surface can be suppressed, and homogeneous quench hardening can be implement | achieved.

  In the above-described method for manufacturing a race, a plurality of induction heating members may be arranged along the circumferential direction of the molded body in the step of forming the heating region. Thereby, the dispersion | variation in the temperature in the circumferential direction of a rolling surface can be suppressed, and homogeneous quench hardening can be implement | achieved.

  In the method for manufacturing a race, the temperature at a plurality of locations in the heating region may be measured in the step of forming the heating region. Thereby, after confirming that homogeneous heating has been realized in the circumferential direction of the rolling surface, quenching and hardening can be performed. As a result, uniform quenching hardening can be realized in the circumferential direction of the rolling surface.

  The track ring according to one aspect of the present invention is manufactured by the above-described track ring manufacturing method of the present invention, and has an inner diameter of 1000 mm or more. According to the race in one aspect of the present invention, the hardened hardened layer is rolled by the induction hardening while the cost of the heat treatment is suppressed by being manufactured by the method for manufacturing the race according to the present invention. A large-sized race ring formed uniformly along the entire circumference can be provided.

A bearing ring according to another aspect of the present invention is a rolling bearing bearing ring having an inner diameter of 1000 mm or more. This bearing ring has a carbon content of 0.43% to 0.65% by mass, silicon of 0.05% to 0.14% by mass, and 0.60% to 1.10% by mass of silicon. Containing manganese, 0.30 mass% or more and 1.20 mass% or less chromium, and 0.15 mass% or more and 0.75 mass% or less molybdenum, and it is comprised from the steel which consists of remainder iron and impurities , A hardened layer is formed over the entire circumference along the rolling surface.

  In the raceway in the other aspect described above, the hardened hardened layer is formed over the entire circumference along the rolling surface by induction hardening. Therefore, the raceway in the above-mentioned other aspect is a raceway excellent in durability that can make any region of the rolling contact surface a load region. In the raceway in the above-mentioned other aspects, it is possible to realize sufficiently high hardness by quench hardening, suppress quench quenching while ensuring high hardenability, and suppress hydrogen embrittlement separation. Steel having an appropriate composition is adopted as a material. Thus, according to the raceway in another aspect of the present invention, a large raceway with excellent durability can be provided.

  A rolling bearing according to the present invention includes an inner ring, an outer ring disposed so as to surround the outer peripheral side of the inner ring, and a plurality of rolling elements disposed between the inner ring and the outer ring. At least one of the inner ring and the outer ring is the raceway ring according to the present invention.

  According to the rolling bearing of the present invention, a large-sized rolling bearing having excellent durability can be provided by including the raceway of the present invention.

  In the wind power generator, the rolling bearing is a rolling device that rotatably supports the main shaft with respect to the housing by fixing the main shaft connected to the blade through the inner ring and fixing the outer ring with respect to the housing. It can be used as a bearing (rolling bearing for wind power generator). The rolling bearing of the present invention, which is a large rolling bearing having excellent durability, is suitable as a rolling bearing for a wind power generator. In particular, the rolling bearing of the present invention is suitable as a rolling bearing for use in offshore wind power generators that are liable to intrude hydrogen from the atmosphere into the race (bearing parts) because it is used in a high humidity environment. .

Note that the _point A when heated steel refers to a point that the structure of the steel corresponds to the temperature to start the transformation from ferrite to austenite. Further, the M _s point means a point corresponding to a temperature at which martensite formation starts when the austenitized steel is cooled.

  As is apparent from the above description, according to the method for manufacturing a bearing ring, the bearing ring and the rolling bearing of the present invention, the quench hardened layer is formed on the rolling surface by induction hardening while suppressing the manufacturing cost of the quenching apparatus. A method for manufacturing a bearing ring that can be uniformly formed along the entire circumference and that can produce a highly durable bearing ring, and a hardened hardened layer is formed on the rolling surface by induction hardening. It is possible to provide a rolling bearing bearing ring that is formed over the entire circumference along the circumference and that has high durability, and a rolling bearing including the bearing ring.

It is a flowchart which shows the outline of the manufacturing method of a rolling bearing inner ring | wheel. It is the schematic for demonstrating a hardening hardening process. It is a schematic sectional drawing which shows the cross section along line segment III-III of FIG. FIG. 5 is a schematic diagram for explaining a quench hardening process in a second embodiment. FIG. 6 is a schematic diagram for explaining a quench hardening process in a third embodiment. 10 is a flowchart showing an outline of a method for manufacturing a rolling bearing inner ring in a fourth embodiment. It is the schematic which shows the structure of the wind power generator provided with the rolling bearing for wind power generators. It is a schematic sectional drawing which expands and shows the periphery of the spindle bearing in FIG. It is a figure which shows the influence of the silicon content which gives to the durability in the environment where hydrogen embrittlement peeling may generate | occur | produce.

  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)
First, Embodiment 1 which is one embodiment of the present invention will be described by taking as an example a method for manufacturing an inner ring which is a bearing ring of a rolling bearing. Referring to FIG. 1, in the inner ring manufacturing method according to the present embodiment, a molded body preparation step is first performed as a step (S <b> 10). In this step (S10), 0.43% to 0.65% carbon, 0.05% to 0.14% silicon, and 0.60% to 1.10% by mass. A steel material containing the following manganese, 0.30 mass% or more and 1.20 mass% or less chromium, and 0.15 mass% or more and 0.75 mass% or less molybdenum, and the balance iron and impurities is prepared. By performing processing such as forging and turning, a molded body having a shape corresponding to a desired shape of the inner ring is produced. More specifically, a molded body corresponding to the shape of the inner ring having an inner diameter of 1000 mm or more is produced. Examples of steel that satisfies the above component composition include JIS standard SUP13.

Next, a normalizing step is performed as a step (S20). In this step (S20), after the fabricated molded body is heated to a temperature not lower than the A ₁ transformation point in the step (S10), the normalizing process by being cooled to a temperature below the A ₁ transformation point implementation Is done. At this time, the cooling rate at the time of cooling in the normalizing process may be a cooling rate at which the steel constituting the formed body is not transformed into martensite, that is, a cooling rate lower than the critical cooling rate. The hardness of the molded body after the normalizing treatment is high when the cooling rate is large, and is low when the cooling rate is small. Therefore, desired hardness can be imparted to the molded body by adjusting the cooling rate.

Next, with reference to FIG. 1, a quench hardening process is implemented. This quench hardening process includes an induction heating process performed as the process (S30) and a cooling process performed as the process (S40). In the step (S30), referring to FIG. 2 and FIG. 3, the coil 21 as the induction heating member is in the circumferential direction of the rolling surface 11 (annular region) that is the surface on which the rolling element should roll in the molded body 10. It is arranged to face a part of. Here, the surface of the coil 21 that faces the rolling surface 11 has a shape along the rolling surface 11 as shown in FIG. Next, the molded body 10 is rotated around the central axis, specifically in the direction of the arrow α, and a high frequency current is supplied to the coil 21 from a power source (not shown). Thereby, the surface layer region including the rolling surface 11 of the formed body 10 is induction-heated to a temperature of A ₁ point or more, and an annular heating region 11A along the rolling surface 11 is formed. At this time, the temperature of the surface of the rolling surface 11 is measured and managed by a thermometer 22 such as a radiation thermometer.

Next, in the step (S40), for example, water as a cooling liquid is sprayed onto the entire molded body 10 including the heating region 11A formed in the step (S30), so that the entire heating region 11A is M. Simultaneous cooling to a temperature below the _S point. As a result, the heating region 11A is transformed into martensite and cured. By the above procedure, induction hardening is performed and the quench hardening process is completed.

Next, a tempering step is performed as a step (S50). In this step (S50), the molded body 10 that has been quenched and hardened in steps (S30) and (S40) is charged into, for example, a furnace, heated to a temperature of A ₁ point or less, and held for a predetermined time. Thus, a tempering process is performed.

  Next, a finishing step is performed as a step (S60). In this step (S60), for example, a finishing process such as a polishing process is performed on the rolling surface 11. With the above process, the inner ring of the rolling bearing is completed, and the production of the inner ring in the present embodiment is completed. As a result, referring to FIG. 2 and FIG. 3, an inner ring 10 having an inner diameter of 1000 mm or more and having a hardened hardened layer formed uniformly along the rolling surface 11 along the rolling surface 11 by induction hardening is completed. .

In the present embodiment, in the step (S30), the coil 21 disposed so as to face a part of the rolling surface of the molded body 10 is relatively rotated along the circumferential direction so that the molded body 10 is A heating region 11A is formed. Therefore, it is possible to employ a small coil 21 with respect to the outer shape of the molded body 10, and the manufacturing cost of the quenching apparatus can be suppressed even when the large molded body 10 is quenched and hardened. . In the present embodiment, the entire heating area 11A is simultaneously cooled to a temperature not higher than the _MS point. Therefore, it becomes possible to form an annular quenching and hardening region that is homogeneous in the circumferential direction, and the residual stress is prevented from concentrating on a part of the region. Furthermore, in the present embodiment, steel having an appropriate component composition that can secure sufficient quenching hardness and hardenability while suppressing hydrogen brittle exfoliation by reducing Si is adopted as a material. Has been. As a result, the manufacturing method of the inner ring in the present embodiment uniformly forms a hardened hardened layer along the rolling surface by induction hardening while suppressing the manufacturing cost of the quenching apparatus and is high. This is a method of manufacturing a bearing ring capable of manufacturing a durable bearing ring.

  In addition, although the said process (S20) is not an essential process in the manufacturing method of the bearing ring of this invention, the non-hardening area | region (area | region other than a hardening hardening layer) of the bearing ring manufactured by implementing this is carried out. The hardness of can be adjusted. When the strength required for the non-cured region is relatively small, an appropriate hardness can be easily imparted to the non-cured region.

  Moreover, in the said process (S20), a hard particle is sprayed with the gas to the molded object 10, and a shot blast process may be implemented, cooling the molded object 10. FIG. Thus, the shot blasting process can be performed simultaneously with the gust cooling at the normalizing process. Therefore, the scale generated in the surface layer portion of the molded body 10 due to the heating of the normalizing treatment is removed, and the deterioration of the characteristics of the raceway due to the generation of the scale and the decrease of the thermal conductivity due to the generation of the scale are suppressed. Here, as hard particle | grains (projection material), the metal particle | grains which consist of steel, cast iron, etc. are employable, for example.

  Further, in the step (S30), the molded body 10 may be rotated at least once. However, in order to suppress temperature variation in the circumferential direction and achieve more uniform quench hardening, the molded body 10 may be rotated a plurality of times. preferable. That is, it is preferable that the coil 21 as the induction heating member relatively rotate two or more times along the circumferential direction of the rolling surface of the molded body 10.

(Embodiment 2)
Next, Embodiment 2 which is another embodiment of the present invention will be described. The inner ring manufacturing method according to the second embodiment is basically performed in the same manner as in the first embodiment, and has the same effects. However, the inner ring manufacturing method according to the second embodiment is different from the first embodiment in the arrangement of the coils 21 in the step (S30).

That is, with reference to FIG. 4, in the step (S30) in the second embodiment, a pair of coils 21 is arranged with the molded body 10 interposed therebetween. And while the molded object 10 rotates in the direction of arrow (alpha), the high frequency current is supplied with respect to the coil 21 from a power supply (not shown). Thereby, the surface layer region including the rolling surface 11 of the formed body 10 is induction-heated to a temperature of A ₁ point or more, and an annular heating region 11A along the rolling surface 11 is formed.

  As described above, by arranging a plurality (two in the present embodiment) of the coils 21 along the circumferential direction of the molded body 10, the method for manufacturing the inner ring of the rolling bearing in the second embodiment is performed in the circumferential direction. This is a method of manufacturing a bearing ring capable of suppressing temperature variation and realizing uniform quench hardening. Further, in order to further suppress the variation in temperature in the circumferential direction, the coils 21 are preferably arranged at equal intervals in the circumferential direction of the molded body 10.

(Embodiment 3)
Next, Embodiment 3 which is still another embodiment of the present invention will be described. The inner ring manufacturing method according to the third embodiment is basically performed in the same manner as in the first and second embodiments, and has the same effects. However, the inner ring manufacturing method in the third embodiment is different from the first and second embodiments in the arrangement of the thermometer 22 in the step (S30).

  That is, referring to FIG. 5, in step (S30) in the third embodiment, the temperatures at a plurality of locations (here, 4 locations) of rolling surface 11 that is the heating region are measured. More specifically, in the step (S30) of the third embodiment, a plurality of thermometers 22 are arranged at equal intervals along the circumferential direction of the rolling surface 11 of the molded body 10.

  Thereby, since the temperature of several places is measured simultaneously in the circumferential direction of the rolling surface 11, after confirming that the uniform heating is implement | achieved in the circumferential direction of the rolling surface 11, the molded object 10 is rapidly cooled. A quench hardening treatment can be carried out. As a result, according to the method for manufacturing the inner ring of the rolling bearing in the third embodiment, more uniform quench hardening in the circumferential direction of the rolling surface 11 can be realized.

(Embodiment 4)
Next, a fourth embodiment which is still another embodiment of the present invention will be described. The inner ring manufacturing method according to the fourth embodiment is basically performed in the same manner as in the first to third embodiments, and has the same effects. However, the inner ring manufacturing method according to the fourth embodiment is different from the first to third embodiments in that a tempering step is performed instead of the normalizing step.

That is, referring to FIG. 6, in the fourth embodiment, the tempering process is performed after the process (S10) is performed as in the first to third embodiments. The tempering step includes a whole quenching step (S21) and a high temperature tempering step (S22). In step (S21), after the entire molded bodies 10 are held by being heated to a quenching temperature range of not lower than the A ₁ transformation point a predetermined time, by being cooled to a temperature below M _S point, the molded body 10 shrink Is processed. Next, in step (S22), the molded body 10, which is the quenching in step (S21) is, by being heated to a tempering temperature range below the A ₁ transformation point is held for a predetermined time, it is tempered The Thereby, even when a relatively high strength is required for the non-hardened region, the hardness and structure of the non-hardened region can be appropriately adjusted to give a desired strength. Here, the said quenching temperature range is 800 degreeC or more and 1000 degrees C or less, for example, and the molded object 10 is hold | maintained only for the time of 40 minutes or more and 240 minutes or less in the said quenching temperature range. Moreover, the said tempering temperature range is 600 degreeC or more and 720 degrees C or less, for example, and the molded object 10 is hold | maintained in the said tempering temperature range only for the time of 120 minutes or more and 720 minutes or less, for example. The hardness of the molded body after the tempering treatment can be set according to the strength required for the non-hardened region of the race, but can be set to, for example, 270 HV or more and 370 HV or less.

  In addition, in the said embodiment, although the case where the coil 21 was fixed and the molded object 10 was rotated was demonstrated, the molded object 10 may be fixed and the coil 21 may be rotated in the circumferential direction of the molded object 10, The coil 21 may be relatively rotated along the circumferential direction of the molded body 10 by rotating both the coil 21 and the molded body 10. However, since the coil 21 requires wiring for supplying a current to the coil 21, it is often reasonable to fix the coil 21 as described above.

  Further, in the above embodiment, the case where the inner ring of the radial type rolling bearing is manufactured as an example of the bearing ring has been described. However, the bearing ring to which the present invention can be applied is not limited to this, for example, a radial type rolling bearing. It may be an outer ring or a bearing ring of a thrust type bearing. Here, in the step (S30), for example, when the outer ring of the radial type rolling bearing is heated, the coil 21 may be disposed so as to face the rolling surface formed on the inner peripheral side of the molded body. Further, in the step (S20), for example, when heating the bearing ring of the thrust type rolling bearing, the coil 21 may be disposed so as to face the rolling surface formed on the end surface side of the molded body.

  Furthermore, the length of the coil 21 as the induction heating member in the circumferential direction of the molded body 10 can be appropriately determined so as to achieve efficient and uniform heating. For example, the length of the region to be heated is 1 / 12, that is, a length such that the central angle with respect to the central axis of the molded body (orbital ring) is 30 °.

  Furthermore, specific conditions for induction hardening in the present invention can be set appropriately in consideration of conditions such as the size, thickness, material, and power supply capacity of the race (molded body).

Moreover, in order to suppress the variation in the temperature in the circumferential direction, it is preferable to provide a step of holding the molded body in a state where the heating is stopped after the induction heating is completed and before cooling to a temperature equal to or lower than the _MS point. . More specifically, for example, by maintaining the state in which the heating is stopped for 3 seconds after the completion of the heating, it is possible to suppress the variation in the temperature in the circumferential direction on the surface of the heated region.

(Embodiment 5)
Next, Embodiment 5 in which the bearing ring of the present invention is used as a bearing ring constituting a bearing for a wind turbine generator (a rolling bearing for a wind turbine generator) will be described.

  Referring to FIG. 7, wind power generator 50 is connected to blade 52 that is a swirl wing, main shaft 51 that is connected to blade 52 at one end so as to include the central axis of blade 52, and the other end of main shaft 51. The speed-up gear 54 is provided. Further, the speed increaser 54 includes an output shaft 55, and the output shaft 55 is connected to the generator 56. The main shaft 51 is rotatably supported around the shaft by a main shaft bearing 3 which is a rolling bearing for a wind power generator. A plurality of main shaft bearings 3 (two in FIG. 7) are arranged in the axial direction of the main shaft 51, and are respectively held by a housing 53. The main shaft bearing 3, the housing 53, the speed increaser 54, and the generator 56 are housed in a nacelle 59 that is a machine room. The main shaft 51 protrudes from the nacelle 59 at one end and is connected to the blade 52.

  Next, the operation of the wind power generator 50 will be described. Referring to FIG. 7, when the blade 52 rotates in the circumferential direction in response to the wind force, the main shaft 51 connected to the blade 52 rotates around the shaft while being supported by the main shaft bearing 3 with respect to the housing 53. The rotation of the main shaft 51 is transmitted to the speed increaser 54 to be accelerated, and converted into rotation around the output shaft 55. Then, the rotation of the output shaft 55 is transmitted to the generator 56, and an electromotive force is generated by the electromagnetic induction action to achieve power generation.

  Next, a support structure for the main shaft 51 of the wind turbine generator 50 will be described. Referring to FIG. 8, main shaft bearing 3 as a rolling bearing for wind power generator includes an annular outer ring 31 as a raceway of the wind bearing for rolling power generator, and wind power generation disposed on the inner peripheral side of outer ring 31. An annular inner ring 32 as a bearing ring of the rolling bearing for the device, and a plurality of rollers 33 disposed between the outer ring 31 and the inner ring 32 and held by an annular retainer 34 are provided. An outer ring rolling surface 31 </ b> A is formed on the inner circumferential surface of the outer ring 31, and two inner ring rolling surfaces 32 </ b> A are formed on the outer circumferential surface of the inner ring 32. The outer ring 31 and the inner ring 32 are arranged so that the two inner ring rolling surfaces 32A face the outer ring rolling surface 31A. Further, the plurality of rollers 33 are in contact with the outer ring rolling surface 31A and the inner ring rolling surface 32A along the two inner ring rolling surfaces 32A at the roller contact surface 33A and are held by the cage 34. By being arranged at a predetermined pitch in the circumferential direction, it is rotatably held on a double row (two rows) annular track. The outer ring 31 is formed with a through hole 31E that penetrates the outer ring 31 in the radial direction. Lubricant can be supplied to the space between the outer ring 31 and the inner ring 32 through the through hole 31E. With the above configuration, the outer ring 31 and the inner ring 32 of the main shaft bearing 3 are rotatable relative to each other.

  On the other hand, the main shaft 51 connected to the blade 52 passes through the inner ring 32 of the main shaft bearing 3 and contacts the inner peripheral surface 32F of the inner ring at the outer peripheral surface 51A and is fixed to the inner ring 32. Further, the outer ring 31 of the main shaft bearing 3 is fitted into an inner wall 53 </ b> A of a through hole formed in the housing 53 so as to come into contact with the outer peripheral surface 31 </ b> F, and is fixed to the housing 53. With the above configuration, the main shaft 51 connected to the blade 52 can rotate about the shaft relative to the outer ring 31 and the housing 53 integrally with the inner ring 32.

  Further, flange portions 32E that protrude toward the outer ring 31 are formed at both ends in the width direction of the inner ring rolling surface 32A. Thereby, a load in the axial direction (axial direction) of the main shaft 51 generated when the blade 52 receives wind is supported. The outer ring rolling surface 31A has a spherical shape. Therefore, the outer ring 31 and the inner ring 32 can make an angle with each other around the center of the spherical surface in a cross section perpendicular to the rolling direction of the rollers 33. That is, the main shaft bearing 3 is a double-row self-aligning roller bearing. As a result, even when the main shaft 51 is bent due to the wind received by the blade 52, the housing 53 can stably and rotatably hold the main shaft 51 via the main shaft bearing 3.

  And the outer ring | wheel 31 and the inner ring | wheel 32 as a bearing ring of the rolling bearing for wind power generators in Embodiment 5 are manufactured by the manufacturing method of the bearing ring described in the said Embodiment 1-4, for example. The outer ring 31 and the inner ring 32 are raceways of a rolling bearing for a wind power generator having an inner diameter of 1000 mm or more. A hardened and hardened layer is uniformly formed on the outer ring 31 and the inner ring 32 over the entire circumference along the outer ring rolling surface 31A and the inner ring rolling surface 32A by induction hardening. That is, the outer ring 31 and the inner ring 32 have an inner diameter of 1000 mm or more, are formed by induction hardening, and have a hardened hardening layer having an annular shape with a uniform depth along the circumferential direction. The surface of the hardened layer is an outer ring rolling surface 31A and an inner ring rolling surface 32A, respectively. Further, the outer ring 31 and the inner ring 32 are suitable components that can realize sufficiently high hardness by quench hardening, suppress quench cracking while ensuring high hardenability, and suppress hydrogen brittle peeling. Steel having a composition is adopted as a material. As a result, the outer ring 31 and the inner ring 32 are large-sized races in which a quench-hardened layer is uniformly formed along the rolling surface by induction hardening while suppressing the cost of heat treatment. This is a bearing ring that constitutes a bearing for a wind power generator that can be used even in a harsh environment in which hydrogen embrittlement separation may occur.

  In the same composition as the steel employed in the present invention, a test piece made of steel in which only silicon is changed is prepared, and the influence of the silicon content on the durability in an environment where hydrogen embrittlement peeling can occur is shown. Experiments to investigate were conducted. The experimental procedure is as follows.

  A rolling test was performed under the conditions shown in Table 1. More specifically, as shown in Table 1, the driving side has a cylindrical shape with an outer diameter (diameter) of 40 mm, a width of 12 mm, and a secondary curvature radius of 60 mm, and the outer surface has a surface roughness Ra of 0.02 μm. A cylinder and a driven cylinder (same shape) were prepared. Then, the drive side cylinder and the driven side cylinder were rotated in opposite directions in the circumferential direction while being brought into contact with each other on the outer peripheral surface under the condition of a maximum contact surface pressure of 2.1 GPa. At this time, as shown in Table 1, the driving side cylinder and the driven side cylinder (test piece) were driven by different motors so that a difference of 2% occurred in the absolute value of the rotational speed. And the time required until the crack generate | occur | produced on the outer peripheral surface of the test piece was investigated. Prior to this rolling test, the specimens (driving side cylinder and driven side cylinder) were charged with cathode hydrogen under the conditions shown in Table 2. Moreover, as steel which comprises a test piece, in the same component composition as the steel employ | adopted in this invention, the steel which changed only silicon was prepared and six types of test pieces were produced. Table 3 shows the specific component composition of steel constituting each test piece. As shown in Table 3, the contents of alloy elements C (carbon), Cr (chromium), Mn (manganese) and Mo (molybdenum), and main impurities P (phosphorus) and S (sulfur) are determined. Steel having substantially constant and varying Si (silicon) content was prepared, and test pieces (test pieces 1 to 6) were prepared. In Table 3, the unit of numerical values is mass%, and the balance is iron and impurities.

  Next, experimental results will be described with reference to FIG. In FIG. 9, the horizontal axis represents the silicon content of the steel constituting the test piece, and the vertical axis represents the time until crack initiation, that is, the life. As shown in FIG. 9, in the region where the Si content is 0.05% by mass or more, the life is shortened as the Si content increases. And when Si content exceeds 0.14 mass%, the lifetime of the test piece is shortened to about 80% when Si content is 0.05 mass%. From this fact, it can be said that when the bearing component is used under conditions where hydrogen embrittlement separation may occur, the Si content of the steel constituting the bearing component is preferably 0.14% by mass or less.

  In addition, the manufacturing method of the bearing ring of this invention is suitable for manufacture of the bearing ring of a large-sized rolling bearing. In Embodiment 5 described above, a wind turbine generator bearing has been described as an example of a large-sized rolling bearing, but application to other large-sized rolling bearings is also possible. Specifically, for example, a bearing ring of a rolling bearing for CT scanner that rotatably supports a rotating mount on which an X-ray irradiation unit of a CT scanner is installed with respect to a fixed mount arranged to face the rotating mount. The manufacturing method of the raceway of the present invention can be suitably applied to the manufacture of the above. The method for manufacturing a bearing ring according to the present invention can be applied to a bearing ring of any rolling bearing such as a deep groove ball bearing, an angular ball bearing, a cylindrical roller bearing, a tapered roller bearing, a self-aligning roller bearing, and a thrust ball bearing. It is.

  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 raceway manufacturing method, raceway ring, and rolling bearing of the present invention are raceways that are required to uniformly form a hardened hardened layer along the rolling surface while suppressing the manufacturing cost of the quenching apparatus. The present invention can be applied particularly advantageously to a method for manufacturing a ring, a rolling ring bearing ring that requires a hardened hardened layer to be formed over the entire circumference along the rolling surface, and a rolling bearing provided with the bearing ring.

  3 Main shaft bearing, 10 Molded body (inner ring), 11 Rolling surface, 11A Heating area, 21 Coil, 22 Thermometer, 31 Outer ring, 31A Outer ring rolling surface, 31E Through hole, 31F Outer surface, 32 Inner ring, 32A Inner Rolling surface, 32E collar, 32F inner peripheral surface, 33 rollers, 33A roller contact surface, 34 cage, 50 wind power generator, 51 main shaft, 51A outer peripheral surface, 52 blade, 53 housing, 53A inner wall, 54 speed increaser , 55 output shaft, 56 generator, 59 nacelle.

Claims (9)

A method of manufacturing a bearing ring for a rolling bearing,
0.43% by mass or more and 0.65% by mass or less of carbon, 0.05% by mass or more and 0.14% by mass or less of silicon, 0.60% by mass or more and 1.10% by mass or less of manganese, The process of preparing the compact | molding | casting which contains 30 mass% or more and 1.20 mass% or less chromium, and 0.15 mass% or more and 0.75 mass% or less of molybdenum which consists of remainder iron and an impurity. When,
An induction heating member that is arranged so as to face a part of an annular region that is to be a rolling surface of the raceway in the molded body and that is relatively heated along a circumferential direction of the annular region. To form an annular heating region heated to a temperature of A ₁ point or more in the molded body,
And a step of simultaneously cooling the entire heating region to a temperature equal to or lower than the _MS point.   The track ring manufacturing method according to claim 1, further comprising a step of performing a tempering treatment on the molded body prior to the step of forming the heating region.   The track ring manufacturing method according to claim 1, further comprising a step of performing a normalizing process on the molded body prior to the step of forming the heating region.   The track ring manufacturing according to any one of claims 1 to 3, wherein in the step of forming the heating region, the induction heating member relatively rotates two or more times along a circumferential direction of the molded body. Method.   5. The method for manufacturing a bearing ring according to claim 1, wherein, in the step of forming the heating region, a plurality of the induction heating members are arranged along a circumferential direction of the molded body.   The method for manufacturing a bearing ring according to any one of claims 1 to 5, wherein in the step of forming the heating region, temperatures at a plurality of locations in the heating region are measured. A bearing ring for a rolling bearing having an inner diameter of 1000 mm or more,
0.43% by mass or more and 0.65% by mass or less of carbon, 0.05% by mass or more and 0.14% by mass or less of silicon, 0.60% by mass or more and 1.10% by mass or less of manganese, Containing 30% by mass or more and 1.20% by mass or less of chromium, and 0.15% by mass or more and 0.75% by mass or less of molybdenum, and is composed of steel consisting of the remaining iron and impurities,
A race ring in which a hardened and hardened layer is formed over the entire circumference along the rolling surface. Inner ring,
An outer ring disposed so as to surround the outer peripheral side of the inner ring;
A plurality of rolling elements disposed between the inner ring and the outer ring;
The rolling bearing according to claim 7, wherein at least one of the inner ring and the outer ring is a bearing ring of the rolling bearing according to claim 7 . In the wind turbine generator, a main shaft connected to a blade penetrates and is fixed to the inner ring, and the outer ring is fixed to the housing, thereby supporting the main shaft rotatably with respect to the housing. Item 9. A rolling bearing according to Item 8 .

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