Needle roller bearing retainer and needle roller bearing

Abstract

A retainer (20) for a needle roller bearing is formed by a stamped metal plate, the stamped metal plate integrally comprising: a cylindrical portion (21) having a plurality of columnar portions (21a) and a plurality of grooves (21b); a flange portion (23) extending from one axial end of the cylindrical portion (21) to the inner diameter side via a bent portion (22); and a flange portion (25) extending from the other axial end of the cylindrical portion (21) to the inner diameter side via a bent portion (24). The radial dimension (L1) of the outer curved surface (22a) of the bent portion (22) provided between the cylindrical portion (21) and the flange portion (23) and the wall thickness (T1) of the one axial end of the cylindrical portion (21) satisfy L1 / T1≤1.4.

Description

Technical Field

[0001] The present invention relates to a retainer for a needle roller bearing, and more particularly to a retainer for a needle roller bearing formed by press working. Background Art

[0002] For example, Patent Document 1 shows an eccentric oscillating gear reducer assembled in an industrial robot or machine tool. The reducer includes: a cylindrical housing, an internal gear provided in the housing, a planetary gear meshing with the internal gear, and a crankshaft that causes the planetary gear to perform planetary motion. When the input shaft rotates and the crankshaft rotates, the planetary gear installed on the eccentric portion of the crankshaft performs planetary motion while meshing with the internal gear, and the revolution component of the planetary motion is output as the rotation of the output shaft. In the reducer, needle bearings are respectively assembled between the journal of the crankshaft and the output shaft, and between the eccentric portion of the crankshaft and the planetary gear.

[0003] The retainer of a needle roller bearing is often formed by cutting, but in order to reduce the manufacturing cost, it is sometimes formed by pressing (for example, refer to Patent Document 2 listed below).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-32087

[0007] Patent Document 2: Japanese Patent Application Publication No. 2012-57751

[0008] Patent Document 3: Japanese Patent Application Publication No. 2011-12699 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, in industrial robots, as the robot itself becomes larger or the weight it can carry increases, the radial load applied to the bearings of the reducer assembled in the robot increases, and as the radial load increases, the thrust load (induced thrust load) also increases. In particular, in the case where the crankshaft of the reducer is supported only by needle bearings as in the above-mentioned Patent Document 1, it is easy to apply thrust loads to these needle bearings. When the needle bearing moves in the axial direction and the retainer abuts against other components (retainers of other needle bearings, or retaining rings that limit the axial movement of the needle bearing, etc.), stress is applied to the retainer, so it is possible to improve reliability by taking strength measures for the retainer.

[0011] For example, when the retainer is formed by cutting, the shape can be easily changed, so measures such as locally thickening the wall of the portion requiring strength can be taken. However, when the retainer is formed by stamping, it is not easy to locally thicken the wall, so other measures are required.

[0012] For example, in the above-mentioned Patent Document 3, deformation or damage of the retainer is prevented by increasing the contact area between the retainer and the washer abutting against the retainer in the axial direction. However, such a countermeasure cannot be applied to the case where the washer is not provided or the shape of the washer cannot be changed.

[0013] Therefore, an object of the present invention is to improve the durability of a needle roller bearing cage formed of a press-formed product against thrust loads.

[0014] Solutions to Solve Problems

[0015] For example, Figure 8 The needle roller bearing retainer 120 shown is composed of a stamped product, which integrally includes: a cylindrical portion 121, which is formed with a groove 121b for retaining the needle roller 110; and a pair of flange portions 123, 125, which extend from the axial ends of the cylindrical portion 121 to the inner diameter side through the curved portions 122, 124. Fig. 9 As shown in the enlarged view in FIG. 1 , when the other member M contacts the retainer 120 from one axial side (right side in the figure), the inner diameter end of the flange portion 123 on one side is displaced axially inward, but the outer diameter end is hardly displaced because it is supported by the cylindrical portion 121. As a result, the outer diameter end P of the outer end surface 123a of the flange portion 123 (i.e., the inner diameter end of the outer curved surface 122a of the bent portion 122) becomes a point that supports the thrust load F.

[0016] However, in the case where the curved portion 122 between the flange portion 123 and the cylindrical portion 121 is formed by bending, the curved portion 122 is bent with a substantially uniform wall thickness. Therefore, the radial dimension L1 of the outer curved surface 122a of the curved portion 122 is substantially equal to the sum of the wall thickness T1 of the cylindrical portion 121 and the radial dimension L2 of the inner curved surface 122b of the curved portion 122 (L1≈T1+L2). In this case, if the radial dimension L2 of the inner curved surface 122b of the curved portion 122 is reduced, the radial dimension L1 of the outer curved surface 122a of the curved portion 122 can be reduced, but the radial dimension L2 of the inner curved surface 122b of the curved portion 122 cannot be reduced at will due to manufacturing reasons. Therefore, in the conventional retainer composed of a stamped product, the radial dimension L1 of the outer curved surface 122a of the curved portion 122 is about 1.5 times the wall thickness T1 of the cylindrical portion 121.

[0017] The present invention focuses on the point that the inner diameter end of the outer curved surface of the above-mentioned curved portion becomes the point for supporting the thrust load F, and is characterized in that the point for supporting the thrust load is arranged on the outer diameter side compared with the past by reducing the radial dimension of the outer curved surface of the curved portion compared with the past. Specifically, the radial dimension L1 of the outer curved surface of the curved portion is set to be less than 1.4 times the wall thickness T1 of the end of the cylindrical portion. As a result, the moment load applied to the flange portion is reduced, and the stress applied to the curved portion is reduced, so that the durability of the retainer can be improved.

[0018] Based on the above, the present invention provides a retainer for a needle roller bearing, which is composed of a stamped product of a metal plate, and the stamped product of the metal plate integrally has: a cylindrical portion, which has a plurality of column portions and a plurality of grooves arranged circumferentially between adjacent column portions; a flange portion on one side, which extends from an axial end portion of the cylindrical portion to the inner diameter side via a bent portion; and a flange portion on the other side, which extends from the other axial end portion of the cylindrical portion to the inner diameter side via a bent portion, and the radial dimension L1 of the outer curved surface of the bent portion arranged between the cylindrical portion and the flange portion on one side and the wall thickness T1 of the axial end portion of the cylindrical portion satisfy L1 / T1≤1.4.

[0019] The above invention is mainly applicable to a retainer of a needle roller bearing having a roller filling rate of 70% or more, and more specifically, a retainer having a circumferential ratio of the grooves in the cylindrical portion of 70% or more.

[0020] The above-mentioned retainer is designed, for example, so that the radial dimension L1 of the outer curved surface of the curved portion, the radial dimension L2 of the inner curved surface of the curved portion, and the thickness T1 of one axial end of the cylindrical portion satisfy L1<T1+L2.

[0021] In the above retainer, for example, L1 / T1≤1.4 can be satisfied by grinding the region including at least the outer diameter end (the boundary with the outer curved surface of the bent portion) of the axially outer end surface of one flange portion. Alternatively, L1 / T1≤1.4 can be satisfied by bending the cylindrical portion and one flange portion so that the angle between the cylindrical portion and one flange portion is 89.9° or less.

[0022] In the above-mentioned cage, it is more preferable that a radial dimension L1 of the outer curved surface of the bent portion and a thickness T1 of one axial end portion of the cylindrical portion satisfy 0.5≤L1 / T1≤1.3.

[0023] The above-mentioned retainer can be manufactured through the following steps: a step of drawing a metal plate to form a formed product that integrally has a cylindrical forming portion and a bottom that closes its other axial end portion; a step of punching the axis of the bottom to form the flange portion on the other side; a step of bending the cylindrical forming portion to form the flange portion on one side; and a step of punching multiple circumferential locations of the cylindrical forming portion to form the multiple grooves.

[0024] In the above-mentioned manufacturing method, if a thin-walled region having a thinner wall thickness than other regions is provided in a region including one axial end portion of the cylindrical forming portion, and the thin-walled region is subjected to bending processing, the bending processing becomes easy. Since the wall thickness of the one axial end portion of the cylindrical portion is thinner than the wall thickness of the axial center portion of the cylindrical portion, the retainer formed in this way is particularly preferably applied to the present invention to improve durability.

[0025] Effects of the Invention

[0026] As described above, according to the present invention, the durability of the needle roller bearing cage formed of a press-formed product against the thrust load can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a cross-sectional view of a crankshaft provided in a speed reducer and a needle roller bearing supporting the crankshaft.

[0028] Figure 2 It is a cross-sectional view of the retainer of the needle roller bearing.

[0029] Figure 3 It is an enlarged view of the vicinity of one flange portion of the above-mentioned retainer.

[0030] Figure 4 It is an enlarged view of the vicinity of the other flange portion of the retainer.

[0031] Figure 5A It is a cross-sectional view showing the manufacturing process of the cage.

[0032] Figure 5B It is a cross-sectional view showing the manufacturing process of the cage.

[0033] Figure 5C It is a cross-sectional view showing the manufacturing process of the cage.

[0034] Figure 5D It is a cross-sectional view showing the manufacturing process of the cage.

[0035] Figure 5E It is a cross-sectional view showing the manufacturing process of the cage.

[0036] Fig. 5F It is a cross-sectional view showing the manufacturing process of the cage.

[0037] Figure 6 It is an enlarged cross-sectional view of a retainer according to another embodiment.

[0038] Figure 7 This is a graph showing the results of a test to confirm the effect of the present invention.

[0039] Figure 8 This is a cross-sectional view of a conventional needle roller bearing cage.

[0040] Fig. 9 yes Figure 7 Magnified view of the retainer. DETAILED DESCRIPTION

[0041] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0042] Figure 1 The crankshaft 1 of the eccentric oscillating gear reducer provided in the joint part of the industrial robot is shown. The crankshaft 1 has: a pair of journals 1a, which are provided at two locations separated in the axial direction; a pair of eccentric parts 1b, which are provided between the pair of journals 1a; and a spur gear mounting part 1c, which is provided at one end in the axial direction. The outer peripheral surface of the pair of journals 1a is formed into a cylindrical surface shape with the rotation center O as the center. The outer peripheral surface of the pair of eccentric parts 1b is formed into a cylindrical surface shape with the axis offset from the rotation center O as the center. The axis of the outer peripheral surface of each eccentric part 1b is arranged at a different phase relative to the rotation center O, for example, arranged at a phase different by 180°.

[0043] The outer peripheral surface of each journal portion 1a of the crankshaft 1 is mounted on the gear frame 3 via a needle bearing 2. In addition, the outer peripheral surface of each eccentric portion 1b of the crankshaft 1 is mounted on the inner peripheral surface of the planetary gear 4 via a needle bearing 2. The crankshaft 1 is supported by only these four needle bearings 2 so as to be rotatable. A spur gear 5 is fixed to the outer peripheral surface of the spur gear mounting portion 1c of the crankshaft 1. It should be noted that the overall structure of the eccentric oscillating gear reducer is the same as that of the known eccentric oscillating gear reducer (for example, the eccentric oscillating gear reducer shown in Patent Document 1), so a detailed description is omitted.

[0044] The needle roller bearing 2 has a plurality of needle rollers 10 and a retainer 20 for retaining the plurality of needle rollers 10. In the present embodiment, the inner raceway surface of the needle roller bearing 2 is directly formed on the outer peripheral surface of the crankshaft 1, and the outer raceway surface of the needle roller bearing 2 is directly formed on the inner peripheral surface of the gear carrier 3 and the planetary gear 4. The roller filling rate of the needle roller bearing 2 is, for example, greater than 70%, preferably greater than 80%. In addition, the roller filling rate of the needle roller bearing 2 is set with an upper limit according to the strength of the retainer 20, for example, less than 90%. It should be noted that the roller filling rate γ is expressed by the following formula.

[0045] Roller filling rate γ = (Z·DA) / (π·PCD)

[0046] Among them, Z: number of rollers, DA: roller diameter, PCD: roller pitch diameter

[0047] The retainer 20 is formed by a stamping product of a metal plate, such as Figure 2 As shown in FIG. 1 , the retainer 20 integrally comprises: a cylindrical portion 21; a flange portion 23 on one side extending from one axial end portion (the right end in the figure) of the cylindrical portion 21 to the inner diameter side via a curved portion 22; and a flange portion 25 on the other side extending from the other axial end portion (the left end in the figure) of the cylindrical portion 21 to the inner diameter side via a curved portion 24. The retainer 20 is a so-called outer ring guided type that is guided by the outer circumferential surface of the cylindrical portion 21 contacting with the raceway surface (the inner circumferential surface of the gear carrier 3 or the inner circumferential surface of the planetary gear 4).

[0048] The cylindrical portion 21 has: a plurality of columnar portions 21a arranged at equal intervals in the circumferential direction; and a plurality of grooves 21b provided between adjacent columnar portions 21a. In the present embodiment, the proportion of the grooves 21b in the cylindrical portion 21 in the circumferential direction is 70% or more. The wall thickness T1 at one axial end of the cylindrical portion 21 is thinner than the wall thickness T2 at the axial center of the cylindrical portion 21. In the example shown in the figure, as shown in FIG. Figure 3 As shown in the enlarged view in FIG. 1 , the column 21a has: a main body 21a1, which is formed with a wall thickness of T2; and a gradual change portion 21a2, which is arranged adjacent to one axial side of the main body 21a1, and the wall thickness gradually decreases from T2 to T1. The outer peripheral surface of the gradual change portion 21a2 is arranged on the same cylindrical surface as the outer peripheral surface of the main body 21a1, and the inner peripheral surface of the gradual change portion 21a2 is tapered and gradually expands in diameter toward one axial side. The other axial end of the cylindrical portion 21 has the same wall thickness T2 as the axial center portion. It should be noted that in the example shown in the figure, the column 21a is straight along the axial direction, but it is not limited to this. For example, it can also be formed into a cross-section roughly M-shaped with the axial center portion of the column 21a arranged on the inner diameter side.

[0049] The curved portion 22 provided between the cylindrical portion 21 and the flange portion 23 has an outer curved surface 22a which makes the outer peripheral surface of the one axial end portion of the cylindrical portion 21 continuous with the outer end surface 23a of the one flange portion 23, and an inner curved surface 22b which makes the inner peripheral surface of the one axial end portion of the cylindrical portion 21 continuous with the inner end surface 23b of the one flange portion 23. The radial dimension L1 of the outer curved surface 22a of the curved portion 22 is 1.4 times or less (L1 / T1≤1.4) of the wall thickness T1 of the one axial end portion of the cylindrical portion 21, preferably 1.3 times or less (L1 / T1≤1.3), more preferably 1.2 times or less (L1 / T1≤1.2), and further preferably 1 time or less (L1 / T1≤1). In the example shown in the figure, the radial dimension L1 of the outer curved surface 22a of the curved portion 22 is smaller than the sum of the wall thickness T1 of one axial end of the cylindrical portion 21 and the radial dimension L2 of the inner curved surface 24b (L1<T1+L2). In addition, in the example shown in the figure, the radial dimension L1 of the outer curved surface 22a of the curved portion 22 is smaller than the wall thickness T2 of the main body 21a1 of the columnar portion 21a (L1<T2). The lower limit value of the radial dimension L1 of the outer curved surface 22a of the curved portion 22 is set from the viewpoint of strength or manufacturing convenience, for example, 0.5 times or more of the above-mentioned wall thickness T1 (L1 / T1≥0.5).

[0050] A ground surface is provided in a region including at least the outer diameter end of the outer end surface 23a of one flange portion 23. In the present embodiment, a ground surface is provided in the entire region of the outer end surface 23a of one flange portion 23. In accordance with such grinding, the wall thickness T3 of one flange portion 23 is smaller than the wall thickness T1 of one axial end portion of the cylindrical portion 21.

[0051] like Figure 4 As shown in the enlarged view in FIG. 1 , the curved portion 24 provided between the cylindrical portion 21 and the flange portion 25 on the other side has an outer curved surface 24a which makes the outer peripheral surface of the cylindrical portion 21 continuous with the outer end surface 25a of the flange portion 25 on the other side, and an inner curved surface 24b which makes the inner peripheral surface of the cylindrical portion 21 continuous with the inner end surface 25b of the flange portion 25 on the other side. The sum of the radial dimension L3 of the outer curved surface 24a of the curved portion 24 and the wall thickness T2 of the other axial end of the cylindrical portion 21 and the radial dimension L4 of the inner curved surface 24b is substantially equal (L3≈T2+L4). The outer end surface 25a of the flange portion 25 on the other side is not provided with a ground surface, and the entire area becomes a stamping surface. The wall thickness T4 of the flange portion 25 on the other side is thicker than the wall thickness T2 of the other axial end of the cylindrical portion 21.

[0052] The bent portion 22 between the flange portion 23 and the cylindrical portion 21 on one side is formed by bending, and the bent portion 24 between the flange portion 25 and the cylindrical portion 21 on the other side is formed by drawing (details will be described later). It should be noted that in the example shown in the figure, the angle between the flange portions 23, 25 and the cylindrical portion 21 is set to approximately 90°, but the angle of one or both of them can also be set to a value slightly smaller than 90°.

[0053] When other components abut against the retainer 20 from one axial side, as shown in FIG. Figure 3 As shown in FIG. 1 , a thrust load F1 is applied to the outer diameter end P1 of the outer end surface 23a of one flange portion 23 (i.e., the inner diameter end of the outer end surface 23a of the flange portion 23 and the outer curved surface 22a of the curved portion 22). In the present embodiment, since the radial dimension L1 of the outer curved surface 22a of the curved portion 22 is reduced (specifically, L1 / T1≤1.4 is satisfied), the point P1 to which the thrust load F1 is applied is set on the outer diameter side. As a result, the moment load applied to the flange portion 23 is reduced, and therefore, the stress applied to the curved portion 22 or the axial end portion of the cylindrical portion 21 due to the inclination of the flange portion 23 is reduced. In particular, in the present embodiment, the wall thickness T1 of the axial end portion of the cylindrical portion 21 is reduced, so the load applied to this portion is reduced, and the durability of the retainer 20 against the thrust load is improved.

[0054] On the other hand, when other components abut against the retainer 20 from the other axial side, as shown in FIG. Figure 4 As shown in FIG. 1 , a thrust load F2 is applied to the outer diameter end P2 of the outer end surface 25a of the flange portion 25 of the other flange portion 25 (i.e., the inner diameter end of the outer end surface 25a of the flange portion 25 and the outer curved surface 24a of the curved portion 24). Since the radial dimension L3 of the outer curved surface 24a of the curved portion 24 is larger than the radial dimension L1 of the outer curved surface 22a of the curved portion 22, the point P2 to which the thrust load F2 is applied is set at a smaller radius than the outer curved surface 24a of the curved portion 22. Figure 3 The point P1 shown is located on the inner diameter side. Therefore, the moment load applied to the flange portion 25 becomes larger, but since the wall thickness T2 of the other axial end of the cylindrical portion 21 and the wall thickness of the curved portion 24 continuous with the other axial end of the cylindrical portion 21 become thicker, there is no problem with durability. Of course, the radial dimension L3 of the outer curved surface 24a of the curved portion 24 may be reduced in the same manner as the curved portion 22. In this case, the durability of the retainer 20 is further improved.

[0055] Next, a method of manufacturing the above-mentioned retainer 20 by press working will be described using FIG. 5 .

[0056] First, a flat metal plate (such as a steel plate) is punched into a predetermined shape to form a blank W0 (see Figure 5AThen, the blank W0 is subjected to a drawing process to form a cup-shaped molded product W (see Figure 5B ). The drawing process may also be performed in multiple times. Through the above-mentioned drawing process, the cylindrical forming portion W1 is elongated, so that the wall thickness of the cylindrical forming portion W1 becomes thinner than the wall thickness of the bottom W2. In addition, through the above-mentioned drawing process, a thin-walled portion W11 having a thinner wall thickness than other regions is formed in the region including the end portion of the opening side of the cylindrical forming portion W1. The thin-walled portion W11 is formed, for example, by transferring the shape of the mold (punch).

[0057] Next, the bottom W2 of the molded product W is punched out along its axis to form an opening W20 (see Figure 5C The bottom portion W2 formed with the opening portion W20 in this manner serves as the other flange portion 25 of the retainer 20 .

[0058] Next, the other axial end portion of the cylindrical molded portion W1 of the molded product W is pressed several times by a bending die to be bent toward the inner diameter side (see Figure 5D At this time, the thin-walled portion W11 of the cylindrical molded portion W1 is bent to facilitate the bending process. By this bending process, the flange portion W3 extending from the cylindrical molded portion W1 toward the inner diameter side is formed.

[0059] Next, the flange portion W3 is punched out at its axis to form an opening W30 of a predetermined diameter (see Figure 5E ). The flange portion W3 formed with the opening portion W30 in this way becomes the flange portion 23 of one side of the retainer 20. Then, the cylindrical molded portion W1 is punched out at multiple locations in the circumferential direction along the radial direction to form multiple opening portions W10 (see Fig. 5F The opening W10 formed in this way becomes the concave groove 21 b of the retainer 20 , and the cylindrical molded portion W1 having the opening W10 becomes the cylindrical portion 21 of the retainer 20 .

[0060] The outer end surface 23a of the flange portion 23 of the retainer 20 formed by press molding is subjected to grinding. Specifically, the outer end surface 23a' of the flange portion 23 before the grinding is performed is set at Figure 3The outer end face 23a' and the outer curved surface 22a of the curved portion 22 are arranged at the position indicated by the dotted line in the figure. The outer end face 23a' is ground to form the outer end face 23a indicated by the solid line by grinding the region (the entire region in this embodiment) at least including the outer diameter end of the outer end face 23a', and the boundary P1 between the outer end face 23a and the outer curved surface 22a of the curved portion 22 is moved to the outer diameter side than the boundary P1' before grinding. As a result, the radial dimension L1 of the outer curved surface 22a of the curved portion 22 is reduced, thereby satisfying L1 / T1≤1.4.

[0061] The present invention is not limited to the above-described embodiment. Hereinafter, other embodiments of the present invention will be described, but repeated descriptions of the same points as the above-described embodiment will be omitted.

[0062] exist Figure 6 In the embodiment shown, the radius of curvature of the curved portion 22 is reduced, thereby reducing the radial dimension L1 of the outer curved surface 22a of the curved portion 22. In the example shown in the figure, the radius of curvature of the curved portion 22 is reduced by actively reducing the angle between the flange portion 23 and the cylindrical portion 21 (for example, set to 89.9° or less), thereby reducing the radius of curvature of the curved portion 22 and reducing the radial dimension L1 of the outer curved surface 22a, thereby satisfying L1 / T1≤1.4. It should be noted that in the present embodiment, the outer curved surface 22a strictly extends to a point Q on the inner diameter side relative to the axially outer end P1 (apex), but in the present invention, the radial dimension L1 of the outer curved surface 22a means the radial dimension between the outer diameter end of the outer curved surface 22a and the axially outer end P1.

[0063] The cage and the needle roller bearing including the cage of the present invention are not limited to the speed reducer of an industrial robot, but can also be assembled as a bearing for supporting a rotating shaft of other machines such as a machine tool.

[0064] [Example 1]

[0065] Through FEM analysis, it is confirmed that Figure 2 A plurality of test pieces with different radial dimensions L1 of the outer curved surface 22a of the curved portion 22 of the retainer 20 and different wall thicknesses T1 of one axial end of the cylindrical portion 21 were tested to see whether stress was generated in the damaged region when another member was brought into contact from one axial side. The results are shown in Table 1 below.

[0066]

Table 1

[0067] L1 T1 L1 / T1 FEM analysis Example 1 1 1 1 ○ Comparative Example 1 1.53 1 1.53 × Comparative Example 2 0.98 0.54 1.81 × Example 2 0.92 0.67 1.37 ○ Example 3 0.6 0.46 1.3 ○

[0068] As shown in Table 1, stress in the damage region was generated in Comparative Examples 1 and 2 where L1 / T1 exceeded 1.4, whereas stress in the damage region was not generated in Examples 1 to 3 where L1 / T1 was 1.4 or less.

[0069] Next, thrust loads were applied to a plurality of conventional products with L1 / T1 of 2.0 and a plurality of products of the present invention with L1 / T1 of 1.33, and a rotation test was performed. Figure 7 As shown in the figure, the conventional products all broke in a short time (one axial end of the column part broke). In contrast, for the product of the present invention, the retainer did not break even when the time exceeded 8.1 times the reference time (the test was still ongoing at the time of writing this specification). Based on the above results, it is confirmed that the durability of the retainer is improved by the present invention in which L1 / T1 is set to 1.4 or less.

[0070] Description of Reference Numerals

[0071] 1 Crankshaft

[0072] 2 Needle roller bearings

[0073] 20 Retainer

[0074] 21 Cylinder

[0075] 22 Bend

[0076] 23 flange portion on one side

[0077] 24 Bend

[0078] 25 The other flange

[0079] W molded product

[0080] W1 Cylinder forming section

[0081] W11 Thin wall part

[0082] W2 Bottom

[0083] W3 flange part.

Claims

1. A retainer for a needle roller bearing, which is composed of a stamped product of a metal plate, wherein the stamped product of the metal plate integrally comprises: a cylindrical portion having a plurality of columnar portions and a plurality of grooves arranged in the circumferential direction between adjacent columnar portions; a flange portion on one side extending from one axial end portion of the cylindrical portion to the inner diameter side via a bent portion; and a flange portion on the other side extending from the other axial end portion of the cylindrical portion to the inner diameter side via a bent portion, wherein: The inner diameter end of the outer curved surface of the bent portion serves as a support point for supporting the thrust load applied to the needle roller bearing retainer from one axial side. The angle between the cylindrical portion and the one flange portion is formed to be less than 89.9°, so that the axially outer end surface of the one flange portion is formed into a conical surface that is displaced axially inward as it moves toward the inner diameter side. The support point is located at a position closer to the outer diameter side than when the angle is formed to be greater than 90 degrees, so that the radial distance L1 between the outer peripheral surface of the cylindrical portion and the support point and the wall thickness T1 of one axial end portion of the cylindrical portion satisfy L1 / T1≤1.4, The radial distance L1 between the outer circumferential surface of the cylindrical portion and the supporting point, the radial dimension L2 of the inner curved surface of the bent portion, and the thickness T1 of one axial end portion of the cylindrical portion satisfy L1<T1+L2.

2. The needle roller bearing retainer according to claim 1, wherein: The ratio of the concave groove in the cylindrical portion in the circumferential direction is 70% or more.

3. A retainer for a needle roller bearing, which is composed of a stamped metal sheet, wherein the stamped metal sheet integrally comprises: a cylindrical portion having a plurality of columnar portions and a plurality of grooves arranged in the circumferential direction between adjacent columnar portions; a flange portion on one side extending from one axial end portion of the cylindrical portion to the inner diameter side via a bent portion; and a flange portion on the other side extending from the other axial end portion of the cylindrical portion to the inner diameter side via a bent portion, wherein: The inner diameter end of the outer curved surface of the bent portion serves as a support point for supporting the thrust load applied to the needle roller bearing retainer from one axial side. A ground surface is provided in a region including at least the outer diameter end of the axially outer end surface of the flange portion of the one side, so that the support point is located at a position closer to the outer diameter side than before the ground surface is formed, so that the radial distance L1 between the outer peripheral surface of the cylindrical portion and the support point and the wall thickness T1 of the axial end portion of the cylindrical portion satisfy L1 / T1≤1.4, The radial distance L1 between the outer circumferential surface of the cylindrical portion and the supporting point, the radial dimension L2 of the inner curved surface of the bent portion, and the thickness T1 of one axial end portion of the cylindrical portion satisfy L1<T1+L2.

4. The needle roller bearing retainer according to any one of claims 1 to 3, wherein: The radial distance L1 between the outer peripheral surface of the cylindrical portion and the supporting point and the wall thickness T1 of one axial end portion of the cylindrical portion satisfy 0.5≤L1 / T1≤1.

3.

5. The needle roller bearing retainer according to any one of claims 1 to 3, wherein: A thickness T1 of one axial end portion of the cylindrical portion is thinner than a thickness T2 of an axial center portion of the cylindrical portion.

6. A needle roller bearing, wherein: The needle roller bearing has: The needle roller bearing retainer according to any one of claims 1 to 5; and A plurality of needle rollers are accommodated in the plurality of grooves of the needle roller bearing retainer.

7. The needle roller bearing according to claim 6, wherein: The roller filling rate is more than 70%.

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