JP2021080973A - Rolling bearing and method for manufacturing the same - Google Patents

Abstract

To provide a rolling bearing that can improve durability and improve strength by suppressing wear of a retainer.SOLUTION: In a rolling bearing, a retainer includes irregularities in at least part of an inner surface of a pocket. The retainer includes 200-500 irregularities of which opening diameter is 10-30 μm and depth is 1-3 μm, per 1 mm2. The irregularities are formed by being subjected to blast processing such as shot-peening.SELECTED DRAWING: Figure 2

Description

The present invention relates to rolling bearings and methods for manufacturing the same.

As a method for manufacturing a cage for rolling bearings, a blank product obtained by punching a steel plate material is made into a substantially tubular drawn product by press working such as drawing, and then this drawing product is punched to form a pocket hole. It is common to heat-treat. Further, since burrs, burrs, residual foreign substances and the like are generated during press working and heat treatment, blasting and barrel processing are performed to remove them.

In the method for manufacturing a cage for needle roller bearings described in Patent Document 1, when removing burrs, burrs, residual foreign substances, etc. generated during press working or heat treatment by blasting, the working pressure of the projection material of glass beads It is described that the nitrided film applied to the cage is maintained well by specifying the projection time and the projection time.

Japanese Unexamined Patent Publication No. 2015-132343

By the way, according to the method for manufacturing a cage described in Patent Document 1, there is room for further improvement in the rotational torque of the obtained rolling bearing and the wear and strength of the cage.

Therefore, an object of the present invention is to provide a rolling bearing that can suppress the rotational torque of the rolling bearing and the wear of the cage, improve the durability, and improve the strength.

That is, the present invention relates to the following rolling bearings and a method for manufacturing the same.
(1) At least in a rolling bearing having a rolling element and a cage
The cage is a rolling bearing having irregularities on at least a part of the inner surface of the pocket.
(2) The rolling bearing according to (1), which has an opening diameter of 10 to 30 μm and ^{200 to 500 of the irregularities having a depth of 1 to 3 μm per 1 mm 2.}
(3) The rolling bearing according to (1) or (2), wherein the surface texture spectral ratio Str defined by ISO 25178 is 0.2 or more on the surface having the unevenness.
(4) At least in a method for manufacturing a rolling bearing having a rolling element and a cage.
The cage is a method for manufacturing a rolling bearing in which at least a part of the inner surface of a pocket is blasted to form irregularities.
(5) The method for manufacturing a rolling bearing according to (4), wherein the rolling bearing has an opening diameter of 10 to 30 μm and ^{200 to 500 of the irregularities having a depth of 1 to 3 μm per 1 mm 2.}
(6) The method for manufacturing a rolling bearing according to (4) or (5), wherein the surface texture spectral ratio Str defined by ISO 25178 is 0.2 or more on the surface on which the unevenness is formed.

According to the rolling bearing of the present invention and the method for manufacturing the same, the cage has a low rotational torque due to low friction due to having irregularities on at least a part of the inner surface of the pocket, and the cage is worn. It is difficult to cause lubricant contamination due to the generation of wear debris, and the strength is improved to prevent damage to the cage.

FIG. 5 is a cross-sectional view of a cage and roller having a cage that is blasted. It is a figure which looked at the cage of FIG. 1 from the outside in the radial direction. It is a figure which shows the injection angle of the shot material to the surface of a cage. It is a perspective view which shows the other cage which is blasted.

Hereinafter, the rolling bearing according to the embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the cage and roller 1 as a rolling bearing includes a plurality of needle-shaped rollers 2 as rolling elements and a metal cage 10. The cage 10 is a so-called gantry cage, and surrounds a pair of substantially annular ring portions 11 and 11 arranged on both sides in the axial direction and the radial outer portions of the pair of ring portions 11 and 11. A plurality of pillar portions 12 that are connected in the direction at predetermined intervals are provided. A pocket 13 for holding the roller 2 is formed between the adjacent pillar portions 12 and the pair of ring portions 11, 11.

Here, burrs and burrs are generated on the inner surface of the pocket 13 formed by punching, and a large number of fine streaky irregularities are formed as processing marks. In this case, when the inner surface of the pocket 13 is observed and a polar coordinate graph is obtained, one strong peak (angle spectrum) appears in a certain direction (for example, around 90 °). The polar coordinate graph and the angle spectrum are defined in ISO 25178. In such streaky processing marks, the valleys are aligned in one direction, and the lubricating ability is low.

Therefore, in the present invention, the inner surface of the pocket 13 after punching is blasted to eliminate streaky processing marks and to form a large number of fine irregularities. In the polar graph of the surface where burrs and burrs are crushed by the collision of shot materials, the angular spectra are dispersed in almost all directions. Further, the peak height of the angle spectrum does not become particularly high only at a specific angle, and the unevenness is uniformly distributed in almost all directions.

The fine irregularities may be formed on the entire surface of the cage 10, but are at least a part of the inner surface of the pocket 13 shown in FIG. 2, and needle-shaped rollers are formed on both sides of the pillar portion 12 in the axial direction. The joint between the circumferential surface 14 that contacts 2 in the circumferential direction, the axial surface 15 of the ring portions 11 and 11 that come into axial contact with the needle roller 2, and the column portion 12 and the ring portions 11 and 11. It may be formed on at least one of the surfaces 16. Therefore, fine irregularities may be formed on the entire inner surface of the pocket 13.

The fine irregularities formed on the circumferential surface 14 and the axial surface 15 have a higher ability to hold the lubricant than the streaky processing marks. Therefore, by holding the lubricant, the rotational torque of the rolling bearing is increased. Can be lowered, and the occurrence of wear when the needle-shaped rollers 2 rotate while being in contact with each other can be suppressed. Further, since the compressive residual stress is increased by fine irregularities on at least a part of the inner surface of the pocket, the strength of the cage 10 can be improved in the portion where the stress concentration acts.

In the present embodiment, if the distribution of unevenness ^{is 10 to 30 μm per 1 mm 2 and} the density is 200 to 500 fine unevenness having a depth of 1 to 3 μm, lubrication due to unevenness is present. A rolling bearing having a sufficiently high agent holding capacity and excellent durability can be obtained. In particular, it is preferable that there ^{are 300 to 400 irregularities / mm 2} having an opening diameter of 15 to 25 μm and a depth of 1.5 to 2.5 μm.

Further, here, a surface having irregularities (streak-like processing marks) before blasting is called an "anisotropic surface", and a surface in which irregularities are distributed in various directions is called an "isotropic surface". Called. The surface texture spectral ratio (Str) defined by ISO 25178 is known as an index representing an anisotropic surface and an isotropic surface. This Str is in the range of 0 to 1, and the closer it is to 1, the higher the "isotropic".

In the present embodiment, Str is preferably 0.2 or more, more preferably 0.5 or more, and particularly preferably 0.7 or more. If the Str is less than 0.2, the isotropic property of the unevenness is insufficient, the holding ability of the lubricant due to the unevenness is not sufficient, and the effect of improving the durability may not be sufficiently obtained.

Further, as a result of the shot materials colliding with each other due to the blasting treatment, the Str value approaches 1, and the compressive residual stress on the surface of the cage 10 can be increased. The surface compressive residual stress is preferably 500 MPa or more. More preferably, the surface compressive residual stress is 800 MPa or more.

In addition to the high Str, it is preferable that the surface roughness Ra of the surface of the cage 10 is appropriately adjusted. The smaller the surface roughness Ra, the less damage the needle roller 2 has. Specifically, the average roughness Ra of the surface of the cage 10 is preferably 0.4 μm or less, and more preferably 0.3 μm or less.

In terms of durability, the harder the surface of the cage 10, the more preferable it is, and the Vickers hardness in the region (outermost surface portion) from the surface to a depth of 2 μm is preferably 700 to 900 HV, preferably 750 to 800 HV. Is more preferable.

The rolling bearing of the present invention has irregularities formed on the surface of the cage 10 in a predetermined region, and is preferably satisfied with the uneven distribution as described above, as well as surface compressive residual stress, surface average roughness, and surface hardness. If possible, the other components are not limited, but it is preferable that the same unevenness is formed when the cage 10 comes into contact with the surface. By eliminating the streaky processing marks on the surface of the needle roller 2 and forming irregularities, the holding ability of the lubricant is enhanced even on the roller side, and the durability of the rolling bearing is further improved.

(Production method)
The present invention also relates to a method for manufacturing a rolling bearing having the above-mentioned cage.
The cage 10 first produces a blank product by punching a metal plate such as a steel plate (SPCC material, SPCE material, etc.), a carbon steel plate, a chrome molybdenum steel plate (SCM material), and draws the metal plate to form a substantially tubular shape. Get a squeezed product. Next, the squeezed products are sequentially punched at predetermined intervals to form pocket holes to form a predetermined cage shape. Then, nitriding treatment is performed to obtain a cage.

Further, the shot material is blasted to collide with the surface of the nitriding cage 10 at high speed to crush the tops of the streaky processing traces and form fine irregularities. The treatment conditions for the blasting treatment are not limited as long as the irregularities specified above can be formed and the surface texture such as roughness, hardness, and compressive residual stress can be obtained, but an example is as follows.

Shot blasting, sandblasting, shot peening and the like are typical examples of the blasting process, and the shot peening process is efficient and therefore preferable. As the shot material, particles (shot material) made of ceramic such as steel or SiC can be used. Further, the smaller the shot material, the more preferable, the shot material having a particle size of 30 to 60 μm is preferable, and the shot material having a particle size of 40 to 50 μm is more preferable. The smaller the shot material, the finer the unevenness formed. The shape of the shot material may be various shapes other than the spherical shape. The higher the injection speed of the shot material, the more advantageous it is, and the shot pressure is preferably 0.3 to 0.5 MPa or more, more preferably 0.35 to 0.45 MPa.

Further, regarding the injection angle of the shot material onto the surface of the cage 10, it is preferable that the shot material collides with the surface L of the cage 10 perpendicularly as shown in FIG. That is, the shot material can be injected while swinging the injection nozzle 20 on the same cross section so that the line passing through the center of the injection port of the injection nozzle 20 and the tangent line L on the surface of the cage 10 are orthogonal to each other. preferable. As a result, the shot material collides with the surface of the cage 10 so as to be orthogonal to the surface, and unevenness can be efficiently formed.

Further, the surface of the cage 10 may be blasted at the same time by using a plurality of injection nozzles. As a result, the surface of the cage 10 can be efficiently blasted.

The present invention is not limited to those exemplified in the above embodiments, and can be appropriately modified without departing from the gist of the present invention.
For example, in the above embodiment, the portal type cage has been described as the cage applied to the needle roller bearing, but the present invention is not limited to this, and the M type cage 10a as shown in FIG. 4 is not limited to this. It may be. In FIG. 4, the same or equivalent parts as those shown in FIGS. 1 and 2 are designated by the same reference numerals in the drawings, and the description thereof will be omitted or simplified.

The pillar portion 12 of the M-type cage 10a has a large diameter portion 12a having the same outer diameter as the ring portion 11 and a reduced diameter portion 12b whose diameter is reduced so as to be close to the axis of the cage 10a at the center in the axial direction. And an inclined portion 12c connecting the large diameter portion 12a and the reduced diameter portion 12b.
In the M-type cage 10a configured in this way, the large-diameter portion 12a holds the needle-shaped roller 2 on the outer peripheral surface side of the cage 10a, and the reduced-diameter portion 12b holds the needle-shaped roller 2 on the axial side of the cage 10a. Holds the needle roller 2. Therefore, the fine irregularities may be formed on the entire surface of the cage 10a, but are at least a part of the inner surface of the pocket 13 and are in contact with the needle-shaped rollers 2 in the circumferential direction 14 or needle-shaped. It may be formed on at least one of the axial surface 15 of the ring portions 11 and 11 that come into axial contact with the roller 2 and the surface 16 of the joint between the column portion 12 and the ring portions 11 and 11.

Further, when the cage is incorporated in the shell-shaped outer ring, fine irregularities may be formed on a portion in contact with the outer ring, such as an outer peripheral surface of the ring portion or an axial outer end surface.

The rolling bearing of the present invention is not limited to the cage and roller described above, and may be another type of rolling bearing such as a ball bearing or a roller bearing.

1 Rolling bearing 2 Roller (rolling element)
10, 10a Cage 11 Wheel 12 Pillar 13 Pocket 14, 15 Surface where rollers come into contact 16 Surface of joint between wheel and pillar

Claims (6)

At least in rolling bearings with rolling elements and cages
The cage is a rolling bearing having irregularities on at least a part of the inner surface of the pocket. The rolling bearing according to claim 1, wherein the rolling bearing has an opening diameter of 10 to 30 μm and a depth of 1 to 3 μm, and has ^{200 to 500 of the irregularities per 1 mm 2.} The rolling bearing according to claim 1 or 2, wherein the surface texture spectral ratio Str defined by ISO 25178 is 0.2 or more on the surface having the unevenness. At least in the method of manufacturing a rolling bearing having a rolling element and a cage.
The cage is a method for manufacturing a rolling bearing in which at least a part of the inner surface of a pocket is blasted to form irregularities. The method for manufacturing a rolling bearing according to claim 4, further comprising 200 to 500 of the irregularities having an opening diameter of 10 to 30 μm and a depth of 1 to 3 μm ^{per 1 mm 2.} The method for manufacturing a rolling bearing according to claim 4 or 5, wherein the surface texture spectral ratio Str defined by ISO 25178 is 0.2 or more on the surface on which the unevenness is formed.

Images