CN111133210A

CN111133210A - Retainer for tapered roller bearing and tapered roller bearing

Info

Publication number: CN111133210A
Application number: CN201880062093.7A
Authority: CN
Inventors: 清水拓也
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2017-09-28
Filing date: 2018-09-26
Publication date: 2020-05-08
Anticipated expiration: 2038-09-26
Also published as: JP6875971B2; CN111133210B; WO2019065768A1; JP2019065880A

Abstract

Provided are a retainer for a tapered roller bearing, which has excellent strength at a fillet portion, and a tapered roller bearing using the retainer. The retainer (5) is formed with pocket parts (9) between adjacent column parts (8), a large diameter ring part and the column parts (8), and a small-diameter ring portion and the column portion (8) are respectively connected by forming a round corner portion, a mold parting line (X) formed by injection molding is respectively formed on a pair of surfaces of the adjacent column portion (8) forming the pocket portion (9) along the axial direction, the pair of surfaces has a pair of tapered surfaces (8a, 8a) which is closer to the large-diameter ring portion side than the mold parting line (X) and reduces the circumferential width of the pocket portion (9) in the outer diameter direction, and a pair of tapered surfaces (8b, 8b) which is closer to the small-diameter ring portion side than the mold parting line (X) and reduces the circumferential width of the pocket portion (9) in the outer diameter direction, and the taper angle (theta a) of the pair of surfaces (8a, 8a) is smaller than the taper angle (theta b) of the pair of surfaces (8b, 8 b).

Description

Retainer for tapered roller bearing and tapered roller bearing

Technical Field

The present invention relates to a resin-made retainer for a tapered roller bearing used for railway vehicles, automobiles, industrial machines, and the like, and a tapered roller bearing using the retainer.

Background

A tapered roller bearing generally includes an inner ring having a tapered raceway surface on an outer circumferential surface thereof, an outer ring having a tapered raceway surface on an inner circumferential surface thereof, a plurality of tapered rollers rolling between the raceway surface of the inner ring and the raceway surface of the outer ring, and a cage holding each of the tapered rollers so as to be rollably held in a pocket portion. The cage connects the large-diameter ring portion and the small-diameter ring portion by the plurality of pillar portions, and the tapered rollers are accommodated in the pocket portions between the pillar portions.

Conventionally, a metal material such as a rolled steel plate has been used as a retainer for a tapered roller bearing. However, the metal cage has a problem that the weight thereof becomes heavy, and the wear portion generated in the bearing during use promotes the deterioration of the lubricating oil, thereby shortening the product life of the bearing. Therefore, from the viewpoint of weight reduction and long life of the bearing, a resin-made cage is known as an injection-molded article of a resin composition. However, since the resin-made cage has lower strength than the metal-made cage, a method of securing the strength of the resin-made cage has been proposed.

As a method for securing the strength of the resin holder, a method is known which focuses on a weld line formed by joining molten resins at the time of injection molding. For example, in the technique described in patent document 1, the weld line is generated only in the small-diameter ring portion, and the weld line is not generated in the large-diameter ring portion, thereby improving the strength of the large-diameter ring portion with respect to the radial direction. In the technique described in patent document 2, the weld line is generated only in one ring portion, and the weld line contains reinforcing fibers having a disordered orientation, thereby improving the strength of the retainer.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2014-92252

Patent document 2: japanese patent laid-open publication No. 2013-46982

Disclosure of Invention

Problems to be solved by the invention

However, the strength of the resin holder is not improved only by controlling the weld line. When the tapered roller bearing rotates, various forces such as a pressing force from the tapered rollers and a centrifugal force are applied to the cage. In particular, a high stress is applied to a rounded corner portion (corner R portion) serving as a connection portion between the pillar portion and each ring portion due to stress concentration. Therefore, under the use conditions where a higher stress is generated, such as under high-speed rotation and high vibration, the resin holder may be damaged by the rounded portion. Therefore, in order to improve the strength of the resin-made retainer, it is desirable to reduce stress concentration at the rounded portion and to reduce the occurrence of stress.

The present invention has been made in view of such a background, and an object thereof is to provide a retainer for a tapered roller bearing having excellent strength at a rounded portion between a column portion and each ring portion, and a tapered roller bearing using the retainer.

Means for solving the problems

The retainer for a tapered roller bearing of the present invention is an injection-molded article of a resin composition, wherein the retainer comprises a large-diameter ring portion, a small-diameter ring portion, and a plurality of column portions connecting the large-diameter ring portion and the small-diameter ring portion, pocket portions are formed between adjacent column portions, the large-diameter ring portion and the column portions, and the small-diameter ring portion and the column portions are connected to each other by forming rounded portions, mold parting lines formed by injection molding are formed on a pair of faces of the adjacent column portions constituting the pocket portions along an axial direction, the pair of faces have a pair of tapered first faces and a pair of tapered second faces, the pair of first faces are located on a large-diameter ring portion side with respect to the mold parting line and reduce a circumferential width of the pocket portions in an outer diameter direction, the pair of second faces are located on a small-diameter ring portion side with respect to the mold parting line and reduce a circumferential width of the pocket portions in the outer, the taper angles of the pair of first surfaces are smaller than the taper angles of the pair of second surfaces.

Further, a concave thinned portion (Japanese: ぬすみ部) is provided in the large diameter ring portion as the rounded portion between the large diameter ring portion and the pillar portion. The ratio of the axial length of the thinned portion to the axial width of the large-diameter ring portion is less than 10%.

Further, a concave thinned portion is provided in the small diameter ring portion as the rounded portion between the small diameter ring portion and the pillar portion.

The tapered roller bearing of the present invention includes an inner ring having a tapered raceway surface on an outer circumferential surface thereof, an outer ring having a tapered raceway surface on an inner circumferential surface thereof, a plurality of tapered rollers rolling between the raceway surface of the inner ring and the raceway surface of the outer ring, and a cage for rollably holding the tapered rollers in pockets, wherein the cage is the tapered roller bearing cage of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

In the retainer for a tapered roller bearing according to the present invention, since the pair of first surfaces of the tapered pair of first surfaces, which are closer to the larger-diameter ring portion side than the mold parting line and narrow the circumferential width of the pocket portion in the outer diameter direction, and the pair of second surfaces of the tapered pair of second surfaces, which are closer to the smaller-diameter ring portion side than the mold parting line and narrow the circumferential width of the pocket portion in the outer diameter direction, are formed on the pair of surfaces of the adjacent column portions constituting the pocket portion in the axial direction, respectively, the pair of second surfaces are in contact with the tapered roller and the pair of first surfaces are not in contact with the tapered roller in a state where the retainer holds the tapered roller. That is, the tapered rollers are held by the pair of second surfaces of the adjacent pillar portions.

In this configuration, since the taper angle of the pair of first surfaces is smaller than the taper angle of the pair of second surfaces, the width in the circumferential direction of the pocket portion on the large-diameter ring portion side is wider than that in the case where these taper angles are the same. As a result, the radius of curvature of the rounded portion between the pillar portion and the large-diameter ring portion can be increased. In this case, the pair of first surfaces do not contact the tapered roller, and therefore, even if the radius of curvature of the rounded portion is increased, interference with the tapered roller is less likely to occur. This can alleviate the stress concentration at the rounded portion, and can improve the strength of the resin holder.

Further, since the large-diameter ring portion is provided with the concave thinned portion as the rounded portion between the large-diameter ring portion and the column portion, the radius of curvature of the rounded portion can be made larger, and the stress concentration can be appropriately relaxed. Further, since the ratio of the axial length of the thinned portion at the rounded portion to the axial width of the large-diameter ring portion is less than 10%, a decrease in strength of the large-diameter ring portion due to a decrease in the axial width of the large-diameter ring portion can be suppressed.

Further, since the small diameter ring portion is provided with the concave thinned portion as the rounded portion between the small diameter ring portion and the pillar portion, stress concentration can be alleviated also in the rounded portion on the small diameter ring portion side.

The tapered roller bearing of the present invention includes an inner ring having a tapered raceway surface on an outer circumferential surface thereof, an outer ring having a tapered raceway surface on an inner circumferential surface thereof, a plurality of tapered rollers rolling between the raceway surface of the inner ring and the raceway surface of the outer ring, and a cage for rollably holding the tapered rollers in pocket portions, wherein the cage is the tapered roller bearing cage of the present invention, and the strength of the fillet portion of the cage is excellent, so that the tapered roller bearing can be suitably reduced in weight and prolonged in life.

Drawings

Fig. 1 is an axial sectional view of a tapered roller bearing of the present invention.

Fig. 2 is a perspective view showing a tapered roller bearing cage according to the present invention.

Fig. 3 is a schematic view of a retainer mold used for injection molding.

Fig. 4 is an enlarged perspective view of the tapered roller bearing retainer of the present invention.

Fig. 5 is a diagram showing a relationship between the tapered roller and the round portion.

Fig. 6 is a diagram showing a contact relationship between the tapered rollers and the cage.

Fig. 7 is a diagram showing a relationship between the cage and the bearing peripheral member.

Fig. 8 is a schematic sectional view along the axis of the tapered roller.

Fig. 9 is a view of a thinned portion provided as a rounded portion.

Fig. 10 is a diagram showing the distribution of stress generated in the rounded portion.

Detailed Description

The tapered roller bearing of the present invention is explained based on fig. 1. Fig. 1 is an axial sectional view of a tapered roller bearing. As shown in fig. 1, the tapered roller bearing 1 includes an inner ring 2 having tapered raceway surfaces 2a on an outer circumferential surface thereof, an outer ring 3 having tapered raceway surfaces 3a on an inner circumferential surface thereof, a plurality of tapered rollers 4 rolling between the raceway surfaces 2a of the inner ring 2 and the raceway surfaces 3a of the outer ring 3, and a cage 5 holding the tapered rollers 4 rollably at a constant interval in a circumferential direction. Each of the raceway surfaces is tapered such that the diameter of the raceway surface increases/decreases in the axial direction. The angle of the taper is not particularly limited, but is usually about 15 ° to 60 ° with respect to the axial direction.

Fig. 2 shows an example of a tapered roller bearing retainer according to the present invention. The cage 5 includes a large-diameter ring portion 6, a small-diameter ring portion 7, and a plurality of pillar portions 8 connecting these, and a pocket portion 9 is formed between adjacent pillar portions 8. The tapered roller 4 is accommodated in the pocket portion 9. The large-diameter ring portion 6 and the column portion 8 are connected to each other by forming a rounded portion 10a that smoothly continues these portions. Similarly, the small-diameter ring portion 7 and the column portion 8 are connected to each other by forming a rounded portion 10b that smoothly continues these portions. The rounded portions 10a and 10b are formed in an arc shape in radial cross section. This rounded portion can suppress excessive stress concentration at the position where each

ring portion

6, 7 and the pillar portion 8 intersect.

The retainer 5 is an injection-molded article of a resin composition and is obtained by two molds in the axial direction (axial drawing). Fig. 3 shows a schematic view of the mold. As shown in fig. 3, the mold 11 is a mold for a bearing holder for manufacturing the annular holder 5 by injection molding of a resin composition. The mold 11 includes at least a fixed mold 12 and a movable mold 13 that can be locked/unlocked with respect to the fixed mold 12, and a molding cavity 14 having a desired shape of the bearing holder is formed by abutting the fixed mold 12 and the movable mold. In the manufacture of the cage 5, specifically, one or more gates serving as resin injection ports are provided with respect to the molding cavity 14, and molten resin is injected from the gates and filled into the molding cavity. When the molding cavity is filled with resin, pressure is applied in such a manner as to compress the resin in the molding cavity (dwell pressure). After the molten resin is cooled and solidified in the mold for a certain period of time, the mold is opened to obtain a resin-made bearing holder.

Fig. 4 shows an enlarged perspective view of the holder 5. As shown in fig. 4, a pair of surfaces of the adjacent pillar portions 8 form pocket portions 9. A pair of surfaces of the adjacent pillar portions 8 face each other with the pocket portion therebetween. Here, in the above-described injection molding, the surface of each pillar portion 8 on which the pocket portion 9 is formed is influenced by the two molds due to the relationship of the parting surfaces of the two molds. Therefore, the metal parting lines X formed by injection molding are formed on the pair of surfaces along the axial direction of the tapered roller bearing 1 (the axial direction of the cage 5). In this case, the surfaces of the column portions 8 forming the pocket portions 9 are discontinuous surfaces separated by the metal parting line X, and the surfaces of the column portions 8 forming the pocket portions 9 have a surface 8a on the side of the large-diameter ring portion 6 (large-diameter side) with respect to the metal parting line X and a surface 8b on the side of the small-diameter ring portion 7 (small-diameter side) with respect to the metal parting line X. The metal parting line X is offset from the center of the column portion 8 toward the large-diameter ring portion 6.

In fig. 4, the large diameter side surface 8a is formed by a fixed die 12, and the small diameter side surface 8b is formed by a movable die 13. The large-diameter side surface 8a may be formed by the movable die 13, and the small-diameter side surface 8b may be formed by the fixed die 12.

In fig. 4, one pair of adjacent pillar portions 8 includes a pair of surfaces 8a, 8a on the side of the large-diameter ring portion 6 (large-diameter side) with respect to the metal parting line X and a pair of

surfaces

8b, 8b on the side of the small-diameter ring portion 7 (small-diameter side) with respect to the metal parting line X. Both the pair of surfaces 8a, 8a and the pair of

surfaces

8b, 8b are formed in a tapered shape so as to narrow the width of the pocket portion 9 in the circumferential direction toward the outer diameter direction. When the tapered roller 4 is housed in this configuration, the pair of

surfaces

8b and 8b contact the tapered roller 4, while the pair of surfaces 8a and 8a do not contact the tapered roller 4.

Further, when the bearing rotates, various forces are applied to the cage 5, particularly, the round portions 10a and 10b shown in fig. 4, and high stress is generated due to stress concentration. Therefore, in order to increase the strength of the cage 5, it is desirable to alleviate the stress concentration of the rounded portions 10a and 10 b. In particular, in the tapered roller bearing, the large-diameter ring portion 6 generates higher stress than the small-diameter ring portion 7, and therefore, the countermeasure at the fillet portion 10a becomes more important.

Here, as a method of alleviating the stress concentration, for example, it is conceivable to increase the radius of curvature (arc size) of the round portion. It is expected that the stress is dispersed and generated by increasing the radius of curvature, and the stress concentration is relaxed. However, for example, as shown in fig. 5(a), when the radius of curvature of the rounded portion 10a is made larger than the radius of curvature of the chamfered portion 4a of the tapered roller 4, the rounded portion 10a interferes with the chamfered portion 4a of the tapered roller 4, and it is difficult to hold the tapered roller 4.

As a countermeasure, for example, as shown in fig. 5(b), it is conceivable to provide a concave thinned portion N as the round portion 10a in the axial direction of the large-diameter ring portion 6 and increase the radius of curvature of the round portion 10 a. In this case, the stress concentration can be alleviated and the interference with the chamfered portion 4a of the tapered roller 4 can be prevented. However, in this case, if the thinned portion N is increased (for example, increased in the axial direction) in order to increase the radius of curvature of the rounded portion 10a, the axial width of the large-diameter ring portion 6 is decreased, and the cross-sectional area is further decreased, which may result in a decrease in the strength of the cage 5.

Therefore, it is necessary to prevent the strength of the retainer 5 from being reduced by the thinned portion when the thinned portion is provided. For example, as shown in fig. 6, it is conceivable to increase the axial sectional height (radial width) h of the large-diameter ring portion 6 and to prevent the strength from being lowered by making the large-diameter ring portion 6 thicker in the radial direction. In FIG. 6, the size relationships of h1 and h2 are h1 < h 2. In this case, when the radial width h of the large-diameter ring portion 6 is increased, the mold parting line X becomes closer to the radially inner side. As a result, the area of the surface 8b becomes smaller, and as a result, the contact length d between the pillar portion 8 and the tapered roller 4 becomes shorter. In fig. 6, the size relationship of d1 and d2 is d1> d 2. Thus, it may be difficult to stably hold the tapered rollers 4 due to the increase in the radial width h of the large-diameter ring portion 6.

On the other hand, as another alternative, for example, as shown in fig. 7, it is conceivable to increase the axial sectional length (axial width) L of the large-diameter ring portion 6 and to prevent the strength from being lowered by making the large-diameter ring portion 6 thicker in the axial direction. However, since the bearing peripheral member 15 and the like are present in the vicinity of the axial direction of the cage 5, if the axial width L of the large-diameter ring portion 6 is increased, interference with the bearing peripheral member 15 may occur.

As described above, it is considered that the method of providing the thinned portion or the like to increase the radius of curvature of the rounded portion 10a is advantageous in relaxing stress concentration on the rounded portion 10a, but it is difficult to maintain the strength of the large-diameter ring portion 6.

Therefore, the cage 5 of the present invention has a structure in which the radius of curvature of the rounded portion 10a can be increased while the strength of the large-diameter ring portion 6 is maintained. Specifically, in a pair of adjacent pillar portions 8 constituting the pocket portion 9, the taper angle of the pair of large-diameter side surfaces 8a and 8a is made smaller than the taper angle of the pair of small-diameter side surfaces 8b and 8 b. That is, the taper angle is changed with respect to the pair of large-diameter surfaces 8a and 8a with respect to the mold parting line X so as to increase the circumferential width of the pocket portion 9. The pair of large-diameter-side surfaces 8a and 8a is a "pair of first surfaces", and the pair of small-diameter-

side surfaces

8b and 8b is a "pair of second surfaces". The following description is made with reference to fig. 8.

Fig. 8 is a schematic sectional view of the tapered roller 4 as viewed from the small-diameter ring portion 7 side along the axis thereof. On the pair of surfaces adjacent to each other of the pillar portions 8, the taper angle of the pair of surfaces 8a, 8a on the large diameter side is defined as θ a, and the taper angle of the pair of

surfaces

8b, 8b on the small diameter side is defined as θ b. Here, in the conventional cage, θ a and θ b are the same angle (θ a ═ θ b), whereas in the cage 5 of the present invention, θ a is smaller than θ b (θ a < θ b). Thus, the circumferential width W on the outer diameter side of the pocket portion 9 on the large-diameter ring portion 6 side (the back side of the paper surface in fig. 8) is wider than that in the case where θ a and θ b are at the same angle. As a result, the radius of curvature of the rounded portion 10a can be increased. This can alleviate the stress concentration in the rounded portion 10a and suppress the application of high stress to the rounded portion 10 a.

On the other hand, as shown in fig. 8, the tapered roller 4 is held in contact with a pair of

surfaces

8b and 8b on the small diameter side (the front side of the paper in fig. 8). Therefore, even if the taper angle θ a of the pair of surfaces 8a, 8a is changed to the smaller side to widen the circumferential width W of the pocket portion 9, the retainability of the tapered roller 4 can be maintained.

Here, the taper angle θ b of the pair of small-diameter-

side surfaces

8b and 8b is not particularly limited as long as it is an angle at which the tapered roller 4 can be stably held, and is, for example, 20 to 60 degrees, and more preferably 30 to 50 degrees. On the other hand, the taper angle θ a of the pair of large-diameter-side surfaces 8a and 8a is not particularly limited as long as it is smaller than the taper angle θ b. The difference between the taper angle theta a and the taper angle theta b is, for example, 1 to 10 degrees, preferably 1 to 5 degrees. In view of these, it is particularly preferable that the taper angle θ b is 30 to 50 degrees, and the taper angle θ a is an angle smaller than the taper angle θ b by 1 to 5 degrees.

In order to more appropriately alleviate stress concentration on the rounded portion 10a, a concave thinned portion is preferably provided as the rounded portion 10 a. The radial cross section of the thinning portion is formed in an arc shape. The position where the thinned portion is provided is not particularly limited, and for example, as shown in fig. 9, the thinned portion 16 may be provided in the large-diameter ring portion 6 along the outer diameter surface of the tapered roller 4. Here, since the cage 5 of the present invention has relaxed the stress concentration by the adjustment of the taper angle, the thinned portion can be made smaller when the thinned portion is provided as compared with the conventional cage.

For example, in fig. 9, when the axial length of the thickness reduction portion 16 along the outer diameter surface of the tapered roller 4 is t1 and the axial width of the large-diameter ring portion 6 (including t1) along the outer diameter surface of the tapered roller 4 is t2, the thickness reduction amount in the conventional cage (the cage having the same taper angle θ a and taper angle θ b) is 10 to 20% in terms of the axial length ratio (t1/t2) of the large-diameter ring portion 6. In contrast, the cage of the present invention alleviates stress concentration by changing the taper angle, and therefore can be reduced by a smaller amount than a conventional cage. As a specific numerical value, the thinning amount can be made less than 10% in terms of the axial length ratio (t1/t2) of the large-diameter ring portion 6. That is, in the case where the cage of the present invention is provided with the thinned portion, the amount of thinning can be made small, and therefore, the stress concentration of the round portion 10a can be more appropriately relaxed while maintaining the strength of the large-diameter ring portion 6.

In the above description, the case where the large-diameter rounded portion 10a is the thinned portion 16 has been described, but the thinned portion 16 can be provided similarly to the small-diameter rounded portion 10 b. The position and shape of the thinned portion 16 may be changed depending on the rounded portion 10a and the rounded portion 10 b. From the point of strength and stress dispersion of the cage 5, it is preferable to provide the thinned portion 16 at the large-diameter ring portion 6 in the axial direction, and to provide the thinned portion 16 at the small-diameter ring portion 7 in the axial direction.

The resin composition used as the material of the bearing retainer of the present invention may be any resin composition as long as it can be injection molded and has sufficient heat resistance and mechanical strength as the material of the retainer. Examples of the synthetic resin to be the base resin of the resin composition include polyamide 6(PA6) resin, polyamide 6-6(PA66) resin, polyamide 6-10(PA610) resin, polyamide 6-12(PA612) resin, polyamide 4-6(PA46) resin, polyamide (PA) resins such as polyamide 9-T (PA9T) resin, polyamide 6-T (PA6T) resin, polymetaxyleneadipamide (polyamide MXD-6) resin, injection moldable fluororesins, Polyethylene (PE) resins such as low-density polyethylene, high-density polyethylene, and ultrahigh-molecular-weight polyethylene, Polyacetal (POM) resins, polyphenylene sulfide (PPS) resins, polyether ether ketone (PEEK) resins, Polyamideimide (PAI) resins, Polyetherimide (PEI) resins, and injection moldable Polyimide (PI) resins. Among these synthetic resins, PA resin is preferably used because of its excellent heat resistance and injection moldability. These synthetic resins may be used alone or as a polymer alloy of two or more kinds.

In order to improve the mechanical strength such as the elastic modulus of the retainer, it is preferable to blend a fibrous reinforcing material such as glass fiber, aramid fiber, carbon fiber, or various mineral fibers (whiskers) into these resins within a range that does not inhibit injection moldability. Further, additives other than the fibrous reinforcing material may be added as necessary. Examples of the additive include inorganic fillers such as calcium silicate and talc, solid lubricants such as graphite and Polytetrafluoroethylene (PTFE) resin, and antistatic agents.

A tapered roller bearing using the retainer for a tapered roller bearing according to the present invention can prevent the retainer from being damaged at the fillet portion. Further, by using the resin-made cage, the bearing can be reduced in weight and prolonged in life.

While the embodiments of the present invention have been described above with reference to the drawings, the tapered roller bearing of the present invention is not limited to this.

Examples

The retainer having the shape shown in fig. 2 was molded using a resin composition in a mold shown in fig. 3. In the manufactured cage, the taper angle θ a of the pair of large-diameter sides is 38 degrees, and the taper angle θ b of the pair of small-diameter sides is 40 degrees. In this cage, the thinned portion is not provided as a rounded portion which is a connection portion between the large-diameter ring portion and the pillar portion. The stress generated under drop impact conditions was calculated using a 3D model of the cage. The stress distribution of the calculated stress is shown in fig. 10.

Comparative example

The same resin composition as in example was used to form a cage by injection molding. In the manufactured cage, the taper angle θ a of the pair of large diameter sides and the taper angle θ b of the pair of small diameter sides are both 40 degrees. Further, a thinned portion is provided as a rounded portion which serves as a connection portion between the large-diameter ring portion and the pillar portion. The thinned portion is provided to the large-diameter ring portion along an outer diameter surface of the tapered roller. The axial length (t1) of the thinned portion along the outer diameter surface of the tapered roller is 1.6mm, and the axial width (t2) of the large-diameter ring portion along the outer diameter surface of the tapered roller is 9.0 mm. The ratio (t1/t2) of the axial length of the thinned portion to the axial width of the large diameter ring portion is about 18%. Using the 3D model of the cage, the stress generated under the same conditions as in example 1 was calculated. The stress distribution of the calculated stress is shown in fig. 10.

In fig. 10, in the stress distribution of the comparative example, a stress of 51MPa at maximum is generated in the center of the thinned portion. On the other hand, in the stress distribution of the example, a maximum stress of 38MPa is generated in the center of the round portion. As described above, in the cage of the example, the stress concentration at the rounded portions is relaxed and the generated stress is reduced by about 25% as compared with the cage of the comparative example. Further, since the cage of the example does not have the thinned portion unlike the cage of the comparative example, the strength of the large-diameter ring portion is suppressed from being lowered, and the cage is excellent in strength.

Industrial applicability

The retainer for a tapered roller bearing of the present invention has excellent strength at the rounded portion, and therefore, can be widely used as a retainer for a tapered roller bearing used for railway vehicles, automobiles, industrial machines, and the like.

Description of the reference numerals

1 tapered roller bearing

2 inner ring

3 outer ring

4 tapered roller

5 holding rack

6 major diameter ring part

7 minor diameter ring part

8 column part

9 pocket part

10 round corner

11 mould

12 fixed die

13 Movable die

14 shaped cavity

15 bearing peripheral parts

16 thinning part.

Claims

1. A retainer for a tapered roller bearing, which is an injection-molded article of a resin composition, characterized in that,

the retainer comprises a large-diameter ring part, a small-diameter ring part and a plurality of column parts for connecting the large-diameter ring part and the small-diameter ring part, wherein a pocket hole part is formed between the adjacent column parts,

the large diameter ring portion and the column portion, and the small diameter ring portion and the column portion are connected to each other by forming rounded portions,

a mold parting line formed by injection molding is formed along an axial direction on a pair of surfaces of the column portion adjacent to each other constituting the pocket portion, the pair of surfaces having a pair of tapered first surfaces located on a larger diameter ring portion side than the mold parting line and narrowing a circumferential width of the pocket portion in an outer diameter direction, and a pair of tapered second surfaces located on a smaller diameter ring portion side than the mold parting line and narrowing a circumferential width of the pocket portion in the outer diameter direction,

the taper angle of the pair of first faces is smaller than the taper angle of the pair of second faces.

2. The retainer for a tapered roller bearing according to claim 1,

a concave thinned portion is provided in the large-diameter ring portion as the rounded portion between the large-diameter ring portion and the column portion.

3. The retainer for a tapered roller bearing according to claim 2,

the ratio of the axial length of the thinned portion to the axial width of the large-diameter ring portion is less than 10%.

4. The retainer for a tapered roller bearing according to claim 1,

a concave thinned portion is provided in the small diameter ring portion as the rounded portion between the small diameter ring portion and the column portion.

5. A tapered roller bearing comprising an inner ring having a tapered raceway surface on an outer circumferential surface thereof, an outer ring having a tapered raceway surface on an inner circumferential surface thereof, a plurality of tapered rollers rolling between the raceway surface of the inner ring and the raceway surface of the outer ring, and a cage for rollably holding the tapered rollers in pockets,

the retainer is the tapered roller bearing retainer according to claim 1.