JP2010169182A - Roller bearing - Google Patents

Abstract

Provided is a roller bearing which is excellent in lubricity between an end surface and a collar surface of a roller and has a low starting torque, and which is mass-productive and inexpensive.
A tapered roller bearing includes an inner ring, an outer ring, a plurality of tapered rollers disposed between the inner ring and the outer ring, and a plurality of tapered rollers between the inner ring and the outer ring. And a cage 4 that holds the roller 3, and a lubricant is enclosed in a bearing internal space formed between the outer peripheral surface of the inner ring 1 and the inner peripheral surface of the outer ring 2. At both ends in the axial direction of the outer peripheral surface of the inner ring 1, collars 5 and 5 are provided to protrude radially outward. On the large end surface 3 a of the tapered roller 3 that is in sliding contact with the collar 5, a large number of recesses that are oil reservoirs are formed. The concave portion is formed by smoothing the convex portion of the concave and convex portions formed by shot blasting and leaving only the concave portion.
[Selection] Figure 1

Description

  The present invention relates to a roller bearing having a collar.

  In a roller bearing such as a tapered roller bearing, there is a problem that the starting torque is large because the end surfaces of the flanges provided on the inner ring and the outer ring are in sliding contact with each other during rotation. In the following, the surface of the collar that is in sliding contact with the end face of the roller is referred to as a “collar surface”. Because of the problems as described above, a technique has been proposed in which an oil sump is formed on the end face or collar surface of the roller to improve lubricity and reduce the starting torque.

  For example, Patent Document 1 discloses a cylindrical roller bearing in which a linear trough that serves as an oil reservoir is formed on a roller end surface by grinding. Further, in Patent Document 2, there are a large number of intermittent grooves (oil sumps) in a direction crossing the direction of rolling motion or sliding motion, which are inner ring raceway surface, outer ring raceway surface, roller rolling surface, roller end surface, and collar surface. In addition, a cylindrical roller bearing formed by grinding is disclosed.

  Furthermore, Patent Document 3 discloses a cylindrical roller bearing in which a processing line (oil sump) along a direction orthogonal to the circumferential direction of the roller, that is, the radial direction of the roller, is formed by grinding on the end surface of the roller. . Further, Patent Document 4 discloses a tapered roller bearing in which a linear concave portion serving as an oil reservoir is formed in a textured shape on a large end surface of a tapered roller by grinding. Furthermore, Patent Document 5 discloses a tapered roller bearing in which a plurality of dot-shaped minute recesses (oil sumps) are formed on the flange surface by shot blasting.

  Furthermore, in Patent Document 6, regularly arranged minute pits (oil sumps) are formed on the raceway surface of the inner ring, the raceway surface of the outer ring, the rolling surface of the roller, and the end surface of the roller by an electrolytic processing method. A cylindrical roller bearing is disclosed. Furthermore, Patent Document 7 discloses a cylindrical roller bearing in which a recess that becomes an oil reservoir is formed on the end surface of the roller by two-stage barrel processing. That is, after forming irregularities by the first-stage barrel processing, the convex portions are rounded by the second-stage finishing barrel processing to plateau the surface, thereby forming the concave portions.

JP 7-42746 A JP 7-54849 A JP 7-91452 A JP 2003-269468 A JP-A-6-241235 Japanese Patent Laid-Open No. 5-240254 JP-A-2-168211

  However, since the shape of the oil sump is linear in the thing of patent document 1, when the direction where an oil sump extends follows a sliding direction, the oil retention capability of an oil sump becomes low, and the cause of oil shortage There was a risk of becoming. When the direction in which the sump extends is perpendicular to the sliding direction, the oil sump retains oil, but the oil sump deviates from the contact ellipse, so that the oil flows out from the openings at both ends of the linear sump. Since the leakage tends to occur, the lubricity was not sufficient.

  Moreover, although the thing of patent document 2, 3 has the oil holding | maintenance capability of an oil sump, since the shape of the oil sump was linear, there existed a problem that the side leakage of oil was easy to occur. And since it was necessary to grind the end surface of a roller radially, there existed a problem that mass productivity was low. Furthermore, although the thing of patent document 4 has the oil retention capability of an oil sump, and there is no problem in grinding of the end surface of a roller and there is mass-productivity, since the shape of an oil sump is linear, There was a problem that side leakage was likely to occur.

  Furthermore, although the thing of patent document 5 does not have a problem of oil leakage or mass-productivity, since a convex part is also formed by shot blasting which forms a micro recessed part, the end surface of the roller slidably contacting with a collar surface is the convex part. There is a problem that the surface roughness may be deteriorated by being attacked by the above. Furthermore, in order to form the micro pits by the electrolytic processing method, it is necessary to connect an electrode to each micro pit in the one described in Patent Document 6, which causes a problem of high cost and low mass productivity. there were.

Furthermore, the method described in Patent Document 7 has a problem that there is a limit to the size of a member that can be processed because the barrel processing tends to cause a dent, and the barrel processing requires a longer processing time than shot blasting. There was a problem of cost.
Therefore, the present invention solves the problems of the prior art as described above, is excellent in lubricity between the roller end face and the collar face, and has a low starting torque. An object is to provide a roller bearing.

  In order to solve the above problems, the present invention has the following configuration. That is, the roller bearing of the present invention includes an inner ring, an outer ring, a plurality of rollers arranged to be freely rollable between the inner ring and the outer ring, and a collar formed on at least one of the inner ring and the outer ring, In the roller bearing comprising: a plurality of recesses serving as oil reservoirs are formed on the end surfaces of the rollers that are in sliding contact with the collars, and the recesses smooth out the projections of the projections and depressions formed by shot blasting. It is formed by leaving only the recess.

In the roller bearing of the present invention, it is preferable that the projection material used for the shot blasting is made of ceramic and has a substantially spherical shape with a size passing through a sieve having an opening of 75 μm.
Moreover, it is preferable that the surface roughness of the said end surface is Ra 0.15 micrometer or more and 0.4 micrometer or less, and Rsk-5 micrometer or more and -1 micrometer or less.
Further, the inner surface of the recess is substantially spherical, the diameter of the recess is 5 μm or more and 50 μm or less, the depth of the recess is 0.5 μm or more and 4 μm or less, and the area of the recess portion of the entire end surface is The ratio is preferably 10% or more and 40% or less.

  Furthermore, the roller bearing of the present invention is preferably a tapered roller bearing.

  The roller bearing of the present invention is excellent in lubricity between the roller end face and the collar face and has a low starting torque, and is also mass-productive and inexpensive.

It is a fragmentary longitudinal cross-section which shows the structure of the tapered roller bearing which is one Embodiment of the roller bearing which concerns on this invention. It is a roughness profile of the large end face of the tapered roller before and after processing. It is sectional drawing which shows the structure of the testing machine used for the torque test. It is a graph which shows the result of a torque test.

Embodiments of a roller bearing according to the present invention will be described with reference to the drawings. FIG. 1 is a partial longitudinal sectional view showing the structure of a tapered roller bearing which is an embodiment of a roller bearing according to the present invention.
The tapered roller bearing shown in FIG. 1 includes an inner ring 1, an outer ring 2, a plurality of tapered rollers 3 disposed between the inner ring 1 and the outer ring 2, and a plurality of tapered rollers between the inner ring 1 and the outer ring 2. 3, and a bearing internal space formed between the outer peripheral surface of the inner ring 1 and the inner peripheral surface of the outer ring 2 is provided with a lubricant (for example, lubricating oil or grease) (not shown). Is enclosed. In addition, the holder | retainer 4 does not need to be provided.

Further, at both axial end portions of the outer peripheral surface of the inner ring 1, flanges 5 and 5 are provided to protrude radially outward. The outer ring 2 is not provided with a collar. However, contrary to the example of FIG. 1, it is possible to provide a configuration in which ribs are provided at both axial ends of the inner peripheral surface of the outer ring 2 and no ribs are provided on the inner ring 1, or both the inner ring 1 and the outer ring 2 are provided with ribs. It is good also as a structure which provides.
The inner side surfaces 5 a and 5 a of the collars 5 and 5, that is, the collar surfaces function as surfaces that guide and hold the tapered rollers 3, and are in sliding contact with the end surfaces of the tapered rollers 3. Of the end faces of the tapered rollers 3, a large end face 3a is formed with a large number of recesses (not shown) that function as an oil reservoir.

  This recess is formed by shot blasting. That is, by projecting a projection material onto the large end surface 3a, after forming irregularities on the large end surface 3a, the convex portions of the irregularities are smoothed by polishing to leave only the concave portions. Thereby, the large end surface 3a is in a state in which a large number of concave portions are scattered on a flat surface without directivity. In addition, this recessed part may be formed in the small end surface of the tapered roller 3, and may be formed in both end surfaces.

Such a dotted intermittent oil reservoir has a higher oil holding capacity than a linearly continuous oil reservoir. In addition, unlike a linear oil sump, there is no directionality, so that side leakage of oil hardly occurs regardless of the sliding direction. Therefore, since the lubricity between the end surface of the tapered roller 3 and the flange surface 5a is excellent, the starting torque of the tapered roller bearing is low.
Furthermore, since the oil reservoir is formed by shot blasting, manufacturing is easy. Therefore, this tapered roller bearing is high in mass productivity and inexpensive. Further, unlike barrel processing, there is almost no limit to the size of members that can be processed.

  Furthermore, since the convex portion of the irregularities formed by shot blasting is smoothed by polishing, there is no possibility that the surface roughness of the flange surface 5a in sliding contact with the large end surface 3a of the tapered roller 3 will deteriorate. In addition, the method of smoothing a convex part by grinding | polishing is not specifically limited, For example, although grinding | polishing with a grindstone is low cost and high in mass productivity, it can also be performed by shot blasting.

  The projection material used for shot blasting is preferably made of ceramic, and preferably has a substantially spherical shape with a size passing through a sieve having an opening of 75 μm. If the projection material is too large, the surface roughness of the large end surface 3a becomes rough, and there is a risk that both sides will be damaged by sliding with the collar surface 5a. The material of the projection material may be high speed steel as long as it has a hardness equal to or higher than that of ceramics.

  Moreover, it is preferable that the surface roughness of the large end surface 3a in which the recessed part was formed is Ra0.15 micrometer or more and 0.4 micrometer or less, and Rsk-5 micrometer or more and -1 micrometer or less. If the surface roughness of the large end surface 3a is too large, both surfaces may be damaged by sliding with the collar surface 5a. On the other hand, if the surface roughness of the large end surface 3a is too small, the oil retaining ability of the oil reservoir may be insufficient.

Furthermore, the inner surface of the recess formed in the large end surface 3a is preferably substantially spherical, and the diameter of the recess is preferably 5 μm to 50 μm and the depth is preferably 0.5 μm to 4 μm. Furthermore, the ratio of the area of the recessed portion to the area of the large end surface 3a is preferably 10% or more and 40% or less.
If the diameter or depth of the concave portion is too large, the surface roughness of the large end surface 3a becomes rough, and there is a possibility that both surfaces may be damaged by sliding with the collar surface 5a. On the other hand, if the diameter and depth of the recess are too small, the oil retention capacity of the oil reservoir may be insufficient. If the area ratio is too large, the surface roughness of the large end surface 3a becomes rough, and there is a possibility that both surfaces may be damaged by sliding with the collar surface 5a. On the other hand, when the ratio of the area is too small, there is a possibility that the oil retention capacity of the oil reservoir becomes insufficient.

  In addition, this embodiment shows an example of this invention and this invention is not limited to this embodiment. For example, in the present embodiment, a tapered roller bearing has been described as an example of a roller bearing, but the present invention can be applied to various types of roller bearings. For example, cylindrical roller bearings, needle roller bearings, and self-aligning roller bearings. However, the present invention is more suitable for tapered roller bearings and cylindrical roller bearings, and among them, it is particularly suitable for tapered roller bearings.

Hereinafter, the present invention will be described more specifically with reference to examples.
A tapered roller bearing (nominal number: HR30309C) having an oil reservoir similar to the above formed on the large end face of the tapered roller was prepared, and its rotational torque was evaluated. The inner ring, the outer ring, and the tapered roller of this tapered roller bearing are all made of case-hardening bearing steel, the surface thereof is superfinished, and the surface hardness is HRC59-63.

  Formation of the oil reservoir on the large end face of the tapered roller was performed by two-stage shot blasting. That is, after forming irregularities on the large end surface by first-stage shot blasting, the convex portions of the irregularities are polished and smoothed by the second-stage shot blasting to leave only the concave portions.

  First, the first stage shot blasting will be described. As the projection material, substantially spherical glass beads having a particle diameter of about 45 μm that passed through a sieve having an opening of 75 μm were used. In addition, an air blasting apparatus was used as the processing apparatus. The inner diameter of the nozzle for injecting the projection material was 5 mm, and the distance between the tip of the nozzle and the large end surface of the tapered roller was 150 mm. The injection pressure of the projection material was 0.4 MPa or more and 0.8 MPa or less. However, 0.4 MPa or more and 0.6 MPa or less is more preferable. Under such conditions, shot blasting was performed for 3 seconds for each tapered roller, and irregularities were formed on the large end face.

  Next, the second stage shot blasting will be described. As the projection material, an elastic body in which abrasive grains were dispersed inside and on the surface was used. The abrasive grains are made of alumina, diamond, or silicon carbide, and have passed through a sieve having an opening of 10 μm (more preferably 5 μm). The elastic body is made of rubber or thermoplastic elastomer, and its particle size is 0.02 mm or more and 3 mm or less. The particle size is more preferably 0.1 mm or more and 1 mm or less. The ratio of the abrasive grains in the projection material is 10% by mass or more and 90% by mass or less (more preferably 60% by mass or more and 80% by mass or less).

  In addition, an air blasting apparatus was used as the processing apparatus. However, a blasting apparatus using a mechanical energy such as an impeller system can also be used. The inner diameter of the nozzle for injecting the projection material was 5 mm, and the distance between the tip of the nozzle and the large end surface of the tapered roller was 150 mm. The injection pressure of the projection material was set to 0.1 MPa or more and 1.5 MPa or less. However, 0.2 MPa or more and 0.6 MPa or less is more preferable. Moreover, the projection angle was 5 ° or more and 90 ° or less. However, 20 degrees or more and 45 degrees or less are more preferable. Under such conditions, shot blasting was performed for 6 seconds for each tapered roller, and the projections were polished and smoothed out of the projections and depressions formed on the large end surface by the first stage shot blasting, leaving only the depressions.

  The surface roughness of the large end surface before and after performing such two-stage shot blasting was measured. As a result, Ra was 0.04 μm and Rsk−0.5 μm to +0.5 μm before the treatment, but after the treatment, Ra 0.15 μm to 0.40 μm and Rsk-5, depending on shot blasting conditions. It was 0.0 μm to −1.0 μm. The roughness profile of the large end face before processing is shown in FIG. 2A, and an example of the roughness profile of the large end face after processing is shown in FIG.

  Moreover, when the large end surface after a process was observed with the metal microscope, the inner surface shape of the recessed part was substantially spherical shape. Moreover, although it changes with shot blasting conditions, the diameter of the recessed part was 5 micrometers or more and 50 micrometers or less, and the depth of the recessed part was 0.5 micrometers or more and 4.0 micrometers or less. Furthermore, when the ratio of the area of the recessed portion in the entire large end surface was measured, it was 10% or more and 40% or less, although it varied depending on the shot blasting conditions.

The method for measuring the area ratio is as follows. That is, an image binarization process is performed on an image observed by magnifying 500 times with a metal microscope, and binarized into a concave portion and a flat surface portion. The area ratio was calculated.
Next, the tapered roller bearing was rotated at various rotational speeds, and the torque at that time was measured. First, the structure of the testing machine used for this torque test will be described with reference to FIG.

  The testing machine 20 is a vertical inner ring rotating type testing machine. In the test machine 20, the end 24a of the main shaft 24 rotatably supported by the support bearing 23 is fitted into an inner ring 26a of a tapered roller bearing 26 as a test bearing. A collar 26d is formed on the outer peripheral surface of the inner ring 26a and makes sliding contact with the tapered roller 26b. An outer ring 26 c constituting the tapered roller bearing 26 together with the inner ring 26 a and the tapered roller 26 b is fitted in the main body 28. A hydrostatic bearing 31 is provided on the upper end surface in the axial direction of the main body 28, and an axial load is applied to the upper surface thereof.

  In addition, a load cell 33 is connected to the side surface of the main body 28 via a bar 34, and the dynamic friction torque applied to the main body 28 is detected by the load cell 33. Further, a passage 36 for supplying lubricating oil from the outside to the rolling contact surface and the sliding contact surface of the tapered roller bearing 26 is formed in the main body portion 28. A thermocouple 38 that detects the temperature of the rolling contact surface and the sliding contact surface is taken out from the side surface of the main body 28.

In the testing machine 20 having the above-described configuration, the axial load, the radial load, the rotation speed, and the amount of lubricating oil can be arbitrarily changed, and the dynamic friction torque during rotation and the temperature rise of the contact surface can be measured simultaneously. it can.
A taper roller bearing provided with a tapered roller having a large end face subjected to the two-stage shot blasting as described above was mounted on the testing machine 20 as a test bearing, and a torque test was performed. And it compared with the case of the normal tapered roller bearing provided with the tapered roller which has not performed shot blasting.

Test bearing identification number: HR30309C
Load: 3.9kN
Rotational speed: 0 to 5000 rpm
Lubricating oil: Mineral oil whose ISO viscosity grade is ISO VG32 Lubricating oil amount: 500 ml / min
Lubricating oil temperature: 50 ± 5 ° C

  In addition, before measuring the torque, a running-in operation in which rotation was performed at 5000 rpm for 1 hour or more was performed, and it was confirmed that the torque was sufficiently stabilized. In order to eliminate the influence of individual differences in bearings, a torque test was performed according to the following procedure. That is, a running-in operation was performed on the normal tapered roller bearing, and a torque test (a torque test of the bearing before shot blasting) was performed. Thereafter, the flange that was in sliding contact with the small end face of the tapered roller was cut out of the collar of the inner ring, and the tapered roller was taken out. Then, after the two-stage shot blasting as described above was performed on the large end face, it was re-incorporated into the bearing and the running-in operation was performed again, and a torque test (a torque test of the bearing after the shot blasting process) was performed.

  The results are shown in the graph of FIG. From this graph, it is understood that the torque after the shot blasting process is reduced by 10 to 60% in the torque in the low speed rotation range (0 to 1000 rpm) as compared with the bearing before the process.

1 Inner ring 2 Outer ring 3 Tapered roller 3a Large end face 5 Brim 5a Brim face

Claims (5)

In a roller bearing comprising an inner ring, an outer ring, a plurality of rollers arranged to roll between the inner ring and the outer ring, and a flange formed on at least one of the inner ring and the outer ring,
The end surface of the roller that is in sliding contact with the collar is formed with a large number of recesses that serve as oil reservoirs, and the recesses are formed by smoothing the projections by polishing and leaving only the recesses. A roller bearing characterized by being formed.   2. The roller bearing according to claim 1, wherein the projection material used for the shot blasting is made of ceramic and has a substantially spherical shape having a size passing through a sieve having an opening of 75 μm.   The roller bearing according to claim 1 or 2, wherein a surface roughness of the end face is Ra 0.15 µm to 0.4 µm and Rsk -5 µm to -1 µm.   The inner surface of the recess is substantially spherical, the diameter of the recess is 5 μm or more and 50 μm or less, the depth of the recess is 0.5 μm or more and 4 μm or less, and the ratio of the area of the recess portion of the entire end surface is It is 10% or more and 40% or less, The roller bearing as described in any one of Claims 1-3 characterized by the above-mentioned.   It is a tapered roller bearing, The roller bearing as described in any one of Claims 1-4 characterized by the above-mentioned.

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