JP2015105667A - Manufacturing method of bearing ring in rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a raceway ring which surely forms an oil film between rolling bodies even under a poor lubrication condition by applying proper grinding processing to a raceway face of a rolling bearing, and can improve durability.SOLUTION: In a manufacturing method of raceway rings 11, 12 including a grinding process of raceway faces 11a, 12a, the grinding process grinds the raceway faces 11a, 12a by blowing a grinding material 30 toward the raceway faces 11a, 12a from an angle inclined to a circumferential direction with respect to a direction vertical to the raceway faces 11a, 12a while rotating the raceway rings 11, 12 around an axial center by using the grinding material 30 bonded with grinding grains 32 on a surface of a core body 31 which holds water components, and has elasticity and viscosity.

Description

  The present invention relates to a method for manufacturing a bearing ring in a rolling bearing.

  Some rolling bearings that support various rotating shafts include an inner ring and an outer ring, and a plurality of rolling elements provided between the inner ring and the outer ring, and the rolling elements roll on the inner ring and the outer ring. A raceway surface is formed. Then, the raceway surface is ground and then finished to a predetermined surface roughness by passing through a polishing process such as super-finishing to realize smooth rolling of the rolling element (for example, Patent Document 1). reference).

JP 2004-130457 A

  The rolling bearings as described above are usually used in a lubricated state. However, if the amount of lubricating oil is small, an oil film is not sufficiently formed between the raceway surface and the rolling elements, and seizure is likely to occur. . In particular, when the surface roughness of the raceway surface is large, for example, as shown in FIG. 7, the microscopic projection portion C1 of the raceway surface C becomes large, and the oil film L between the surface D of the rolling elements is broken. Metal contact occurs, causing a decrease in durability.

  On the other hand, if the amount of lubricating oil is increased, a sufficient oil film can be formed between the raceway surface and the rolling elements, and seizure can be suitably prevented, but the disadvantage of increased rotational torque due to stirring resistance. There is. Therefore, there are cases where the use of a rolling bearing under conditions where the amount of lubricating oil is small (poor lubrication conditions) is required, and it is desired to improve durability even under such conditions.

  The present invention relates to a method of manufacturing a bearing ring capable of improving the durability by forming an oil film with a rolling element even under poor lubrication conditions by performing appropriate polishing on the raceway surface of a rolling bearing. The purpose is to provide.

  The present invention is a method of manufacturing a raceway including a polishing step of a raceway surface, wherein the polishing step includes a polishing material in which abrasive particles are adhered to the surface of a core body that retains moisture and has elasticity and adhesion. The abrasive is sprayed toward the raceway surface from an angle inclined in a circumferential direction with respect to a direction perpendicular to the raceway surface while the raceway is rotated about its axis, and the raceway surface is polished. It is characterized by that.

2. Description of the Related Art A method of polishing by spraying an abrasive having abrasive particles attached to the surface of a core body that retains moisture and has elasticity and adhesion onto the surface of a workpiece is known (see, for example, Japanese Patent No. 3376334). ). In the present invention, when manufacturing a bearing ring for a rolling bearing using such a polishing method, the abrasive is sprayed from the angle inclined in the circumferential direction toward the raceway surface while rotating the bearing ring. is there.
According to the present invention, by applying the above polishing method to the raceway surface polishing step, the surface roughness is conventionally reduced (for example, superfinishing using a grindstone) while reducing changes in the shape of the raceway surface. It is possible to perform polishing with little directivity. Thereby, lubricating oil can be suitably held on the raceway surface, an oil film can be easily formed between the raceway surface and the rolling elements, and durability can be improved.

It is preferable to remove the tips of the microscopic protrusions of the raceway surface in a substantially flat shape by the polishing step.
As a result, the cross-sectional shape of the raceway surface becomes a plateau shape (a plateau shape) having a concave portion between the flat surface, and the lubricating oil is held in the concave portion, while the rolling surface is in contact with the rolling element in the flat surface portion. An oil film can be suitably formed between them.

The bearing ring may be made of stainless steel.
With conventional superfinishing etc., it is difficult to reduce the surface roughness of stainless steel, but by applying the polishing method of the present invention, it is possible to suitably reduce the surface roughness even with stainless steel. It becomes.

  According to the present invention, even under poor lubrication conditions, an oil film can be reliably formed between the rolling elements and durability can be improved.

It is sectional drawing which shows one Embodiment of the rolling bearing which can apply the manufacturing method of this invention. It is explanatory drawing which shows the grinding | polishing apparatus which grinds a bearing ring. It is a figure explaining the injection direction of the abrasives with respect to the inner ring of a rolling bearing. It is a figure explaining the injection direction of the abrasives with respect to the outer ring | wheel of a rolling bearing. It is front explanatory drawing which shows the abrasive | polishing material used with a grinding | polishing apparatus. It is sectional explanatory drawing which shows the contact surface of the track surface of a bearing ring, and a rolling element. It is sectional explanatory drawing which shows the contact surface of the conventional track surface and a rolling element.

Hereinafter, embodiments of a rolling bearing according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing an embodiment of a rolling bearing to which the manufacturing method of the present invention can be applied. The rolling bearing 10 is a radial ball bearing, and an outer ring 11 having an outer raceway surface 11a on the inner periphery, and an inner ring having an inner raceway surface 12a disposed coaxially with the outer ring 11 and facing the outer raceway surface 11a on the outer periphery. 12, a plurality of rolling elements 13 interposed between the outer raceway surface 11a and the inner raceway surface 12a, and a cage 14 that holds each rolling element 13 at predetermined intervals along the circumferential direction. The outer surface of the rolling element 13 is configured as a rolling surface that rolls on the outer raceway surface 11a and the inner raceway surface 12a.

The outer ring 11, the inner ring 12 and the rolling element 13 are made of bearing steel such as bearing steel or carburized steel, stainless steel or the like, and are hardened to a predetermined hardness by heat treatment.
The retainer 14 is formed by forming a plurality of pocket portions 14a for accommodating the rolling elements 13 at predetermined intervals along the circumferential direction in a metal or synthetic resin annular body. The outer peripheral surface of the retainer 14 is configured as a guide surface 14 b, and the rotation of the retainer 14 is guided by sliding the guide surface 14 b on the inner peripheral surface of the outer ring 11.

The outer ring 11 and the inner ring 12 of the rolling bearing 10 are manufactured as follows.
First, the inner peripheral surface, the outer peripheral surface, the end surface, and the raceway surfaces 11a and 12a are formed into predetermined shapes by cutting an annular material obtained by forging bearing steel such as bearing steel and carburized steel. And forming an intermediate material.
Next, the intermediate material is subjected to a heat treatment to cure the surface.
The inner peripheral surface, the outer peripheral surface, the end surface, and the raceway surfaces 11a and 12a of the cured intermediate material are subjected to polishing such as rough finishing, intermediate finishing, and precision finishing to form predetermined dimensions.

In the present embodiment, mirror finish is performed as the precision finish of the raceway surface in the polishing process (polishing step). For the mirror finish, a polishing apparatus 20 shown in FIG. 2 is used.
FIG. 2 is an explanatory view showing the polishing apparatus 20. The polishing apparatus 20 is called Aero Wrap (registered trademark), and sprays abrasives from the rotor 21 to spray the outer ring 11 and the inner ring 12 (hereinafter also referred to as track rings) that are workpieces.

  The rotor 21 is formed in a disk shape and is rotationally driven by a motor (not shown). A supply port 21a is formed at the center of the rotor 21, and the abrasive 30 conveyed via the abrasive guide 22 is supplied to the supply port 21a. A through hole (not shown) extending substantially along the radial direction is formed on the radially outer side of the supply port 21 a of the rotor 21.

The outer peripheral surface of the rotor 21 is closed by an endless belt 23 in the region from the vicinity of the lower end to the vicinity of the upper end. The belt 23 is wound around a plurality of pulleys 24, and the pulley 24 rotates following the rotation of the belt 23.
With the above configuration, the abrasive 30 supplied from the supply port 21a of the rotor 21 is sprayed in the direction of the arrow through the through-hole by centrifugal force due to the high-speed rotation of the rotor 21, and sprayed onto the raceways 11 and 12 that are workpieces. It is done.

FIG. 5 is an explanatory front view showing the abrasive.
As shown in FIG. 5, the abrasive 30 used in the polishing apparatus 20 of the present embodiment includes a core 31 and a plurality of abrasive grains 32 attached to the surface due to the adhesiveness of the surface of the core 31. The core 31 contains water and an evaporation preventing material that prevents evaporation of water from the core.

The core 31 is formed of a material having desired elasticity and adhesiveness when it contains water. For example, the core 31 is made of gelatin using a food material. The diameter of the core 31 is about 0.1 mm to 2.0 mm.
The abrasive grains 32 are made of, for example, diamond, silicon carbide, alumina, or a mixture thereof. The grain size of the abrasive grains 32 is set to 3000 mesh to 10,000 mesh. For the evaporation preventing material, for example, water-soluble oils such as ethylene glycol and sorbitol are used.

  In order to manufacture the abrasive 30, first, the core 31 is contained by spraying a mixed solution of water and an evaporation preventive material to give desired elasticity and adhesiveness. The abrasive 30 is manufactured by attaching the abrasive grains 32 to the surface of the core 31 or by mixing the abrasive grains 32 into the core 31. The polishing apparatus 20 and the abrasive 30 described above are known, for example, in Japanese Patent No. 3376334.

The abrasive 30 as described above is supplied to the polishing apparatus 20 and sprayed from the rotor 21 to the race rings (outer ring 11 and inner ring 12), which are workpieces, to polish the raceway surfaces 11a and 12a.
FIG. 3 is a view for explaining the injection direction of the abrasive 30 with respect to the inner ring 12. FIG. 4 is a view for explaining the injection direction of the abrasive 30 with respect to the outer ring 11.
The track rings set in the polishing apparatus 20, that is, the inner ring 12 and the outer ring 11 are polished in a state of being rotationally driven by the rotational drive mechanism 25. The rotation speed of the races 11 and 12 can be set to 1 min ⁻¹ , for example.

As shown in FIG. 3, the abrasive 30 is sprayed on the inner ring 12 in the direction indicated by the arrow A. As shown in FIG. 3A, the blowing direction A of the abrasive 30 is set to an angle α1 inclined in the circumferential direction with respect to the direction perpendicular to the raceway surface 12a. This angle α1 can be set in a range of 30 ° to 60 °, for example.
Further, as shown in FIG. 3B, the blowing direction A of the abrasive 30 is set in a direction perpendicular to the track surface 12a with respect to the axial direction.

On the other hand, as shown in FIG. 4, the outer ring 11 is sprayed with the abrasive 30 in the direction indicated by the arrow B. Specifically, the blowing direction B of the abrasive 30 is set to an angle α2 inclined in the circumferential direction with respect to a direction (vertical direction in the illustrated example) perpendicular to the track surface 11a, as shown in FIG. Has been. The angle α2 can be set to 30 ° to 60 °, for example.
Further, as shown in FIG. 4B, the blowing direction B of the abrasive 30 is set to an angle β inclined in the axial direction with respect to the direction perpendicular to the raceway surface 11a. This angle β can be set to 5 ° to 30 °, for example. The reason for inclining at this angle β is to cause the abrasive 30 injected from the rotor 21 to collide with the track surface 11 a without interfering with the outer peripheral surface of the outer ring 11. In order to spray the abrasive 30 uniformly on the raceway surface 11a, the abrasive 30 may be alternately sprayed from both sides in the axial direction with an inclination of an angle β.

  The abrasive 30 is jetted from the rotor 21 at a high speed and sprayed onto the raceway surfaces 11a and 12a. At this time, the impact when it collides with the raceway surfaces 11a and 12a is absorbed by the elastic force of the abrasive 30, and the abrasive 30 slides on the surfaces of the raceways 11a and 12a, and the friction energy generated at that time causes The surfaces of the raceway surfaces 11a and 12a are polished. Further, since the blowing directions A and B of the abrasive 30 are set to the angles α1 and α2 that are inclined obliquely with respect to the circumferential direction, the surface of the raceway surfaces 11a and 12a is slid while reducing the impact caused by the collision of the abrasive 30. Therefore, it is possible to polish efficiently. Moreover, the entire raceway surfaces 11a and 12a can be uniformly polished by spraying the abrasive 30 while rotating the raceways 11 and 12 at a constant speed.

  As shown in FIG. 6, the cross sections of the raceway surfaces 11a and 12a polished as described above have a shape in which the flat surfaces 11a1 and 12a1 and the recesses 11a2 and 12a2 are arranged side by side. This is a structure in which only the tip of the protruding portion C1 of the raceway surface C shown in FIG. With such a cross-sectional shape, the lubricating oil can be suitably held in the recesses 11a2 and 12a2, and the surface pressure acting on the oil film L from the raceway surfaces 11a and 12a (flat surfaces 11a1 and 12a1) is reduced. The oil film L can be suitably formed between the raceway surfaces 11a and 12a and the rolling surface 13a of the rolling element 13, and the occurrence of seizure or the like can be suitably prevented.

  Further, when the raceway surfaces 11a and 12a are rubbed with a grindstone as in the conventional superfinishing, the raceway surfaces 11a and 12a have polishing eyes having a specific direction, and the lubricating oil follows the direction. Although it becomes easy to flow, in this embodiment, since the abrasive 30 is sprayed on the raceway surfaces 11a and 12a, the polishing eyes which have directionality hardly arise. Thereby, the retention capability of lubricating oil can be improved and lubrication performance can be improved.

  In the present embodiment, the shape of the generatrix of the raceway surfaces 11a and 12a is formed with a radius of curvature almost as designed in the polishing step before the mirror finish, and in the mirror finish, the raceway surface shown in FIG. Since this is a process of removing the tip of the protruding portion C1 of C, it is possible to reduce the surface roughness with almost no change in the shape of the generatrix.

  The following table shows the surface roughness of the raceway surface when the conventional superfinishing polishing method (No. 1) and the polishing method (No. 2) of this embodiment are applied to bearing steel (SUJ2). This is a comparison of the curvature and the radius of curvature of the raceway surface. The polishing method of the present embodiment is applied to the raceway surface after applying a conventional superfinishing polishing method. Therefore, the table also shows the rate of change of the latter with respect to the former.

  According to the above table, in the present embodiment, both the ten-point average roughness Ra and the arithmetic average roughness Rz are suitably smaller than the conventional one, and the rate of change is −55% or more. In particular, in the present embodiment, Ra can be 0.015 μm or less, and Rz can be 0.050 μm or less. On the other hand, the radius of curvature of the raceway is almost unchanged in both cases, and the rate of change is -0.1%. Therefore, in this embodiment, the surface roughness can be effectively reduced without substantially changing the bus bar shape of the raceway surface.

  In addition, the above results can be obtained in substantially the same manner when the polishing method (manufacturing method) of the present embodiment is applied to stainless steel. This stainless steel is polished by conventional superfinishing or the like. Since it is difficult to sufficiently reduce the surface roughness by this method, it is more effective to apply the polishing method (manufacturing method) of this embodiment.

The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the invention described in the claims.
For example, in the above-described embodiment, a polishing apparatus that injects the abrasive by rotation of the rotor is used. However, other types, for example, a polishing apparatus that injects the abrasive by compressed air can also be used.
The present invention is not limited to ball bearings, and can be applied to the manufacture of races such as cylindrical roller bearings, tapered roller bearings, and self-aligning roller bearings.

DESCRIPTION OF SYMBOLS 10: Rolling bearing, 11: Outer ring (bearing ring), 11a: Outer raceway surface, 12: Inner ring (race ring), 12a: Inner raceway surface, 13: Rolling element, 20: Polishing device, 30: Abrasive material, 31: Core, 32: Abrasive grain

Claims (3)

A method of manufacturing a raceway including a raceway surface polishing step,
The polishing step uses a polishing material in which abrasive particles are adhered to the surface of a core body that retains moisture and has elasticity and adhesiveness, and is perpendicular to the raceway surface while rotating the raceway around its axis. A method of manufacturing a bearing ring in a rolling bearing, wherein the abrasive is sprayed toward the raceway surface from an angle inclined in a circumferential direction with respect to a specific direction to polish the raceway surface.   The method of manufacturing a bearing ring in a rolling bearing according to claim 1, wherein a tip of a microscopic projection portion of the raceway surface is removed in a substantially flat shape by the polishing step.   The method for manufacturing a bearing ring in a rolling bearing according to claim 1, wherein the bearing ring is made of stainless steel.

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