Shell type needle roller bearing

Abstract

To provide a shell type needle roller bearing capable of ensuring strength of a holder even when a circumferential interval between adjacent needle rollers is narrow, and capable of stably guiding the needle roller using the holder.SOLUTION: A shell type needle roller bearing is characterized such that face-pressed surfaces 10 corresponding to hypotenuses of a trapezoid are formed on both circumferential side surfaces of a column central part 8c so that the cross-sectional shape of the column central part 8c is trapezoidal with a circumferential width gradually narrowing radially outward, and groove-shaped relief parts 12 are provided extending radially on both circumferential side surfaces of a column inclined part 8b so that both circumferential side surfaces of the column inclined part 8b are recessed circumferentially relative to the face-pressed surfaces 10.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] This invention relates to a shell-shaped needle roller bearing.

Background Art

[0002] Shell-shaped needle roller bearings are widely used in fields such as automobiles and industrial machinery because they have a smaller radial thickness and a higher load capacity compared to other types of rolling bearings (for example, Patent Document 1).

[0003] The shell-shaped needle roller bearing of Patent Document 1 has a shell-shaped outer ring formed by drawing a steel plate, a plurality of needle rollers arranged at intervals in the circumferential direction along the inner circumference of the shell-shaped outer ring, and a cage that holds the circumferential intervals of the plurality of needle rollers.

[0004] This cage has a pair of annular portions facing each other in the axial direction with needle rollers in between, and a plurality of column portions that connect the pair of annular portions through the spaces between adjacent needle rollers in the circumferential direction. Here, the column portions adjacent to each other in the circumferential direction and the pair of annular portions form pockets for accommodating the needle rollers. This cage is formed by sequentially forming a plurality of pockets in a strip steel that is the material of the cage by punching, cutting the strip steel with the pockets formed to a predetermined length and bending it into a cylindrical shape, and welding both ends of the strip steel bent into a cylindrical shape.

[0005] Each column portion constituting the cage has a pair of column end portions that extend axially inward from the pair of annular portions with a constant outer diameter, a pair of column inclined portions that extend inclinedly so that the outer diameter gradually decreases as they extend axially inward from the pair of column end portions, and a column central portion that connects the pair of column inclined portions. The circumferential side surface of this column portion (column end portion, column inclined portion, column central portion) remains as a punched cross-section formed by punching the pocket, and therefore, the cross-sectional shape of the column portion is a rectangular shape with a constant circumferential width along the radial direction.

Prior Art Documents

Patent Documents

[0006] Patent Document 1 Japanese Patent Application Laid-Open No. 2007-16828 Summary of the Invention Problems to be Solved by the Invention

[0007] The inventor of the present application considered increasing the number of needle rollers without changing the bearing size in a shell-shaped needle roller bearing such as Patent Document 1 in order to increase the load capacity.

[0008] That is, in a shell-shaped needle roller bearing such as Patent Document 1, when the number of needle rollers is increased without changing the bearing size, the circumferential gap between adjacent needle rollers becomes narrower. Therefore, it is necessary to also reduce the circumferential width of the center part of the cage pillar arranged between adjacent needle rollers in the circumferential direction, and the strength of the cage decreases. Therefore, the inventor of the present application focused on the fact that the circumferential gap between adjacent needle rollers has a shape that gradually widens radially inward from the position of the pitch circle of the needle rollers, and considered securing the circumferential width of the center part of the cage pillar by moving the position of the center part of the cage pillar radially inward compared to the prior art.

[0009] However, when the position of the center part of the cage pillar is moved radially inward, there is a possibility that the position where the needle roller contacts the center part of the pillar becomes the corner part at the radially outer end of the circumferential side surface of the center part of the pillar. In this case, the needle roller may ride over the center part of the pillar, and there is a possibility that the center part of the pillar is pressed radially inward and contacts the shaft.

[0010] The problem to be solved by this invention is to provide a shell-shaped needle roller bearing that can ensure the strength of the cage even when the circumferential gap between adjacent needle rollers is narrow, and can stably guide the needle rollers with the cage. Means for Solving the Problems

[0011] In order to solve the above problems, this invention provides a shell-shaped needle roller bearing having the following configuration. [Structure 1] A shell-shaped outer ring, a plurality of needle rollers arranged at intervals in the circumferential direction along the inner circumference of the shell-shaped outer ring, and a cage for holding the circumferential intervals of the plurality of needle rollers, wherein the cage has a pair of annular portions facing each other in the axial direction with the needle rollers therebetween, and a plurality of column portions connecting the pair of annular portions through between the circumferentially adjacent needle rollers, in the shell-shaped needle roller bearing, each of the column portions has a pair of column end portions extending axially inward with a constant outer diameter from the pair of annular portions, a pair of column inclined portions extending obliquely so that the outer diameter gradually decreases toward the axially inner side from the pair of column end portions, and a column central portion connecting the pair of column inclined portions, surface pressing processed surfaces corresponding to the hypotenuses of the trapezoids are formed on the side surfaces on both circumferential sides of the column central portion so that the cross-sectional shape of the column central portion becomes a trapezoid whose circumferential width gradually narrows toward the radially outer side, the surface pressing processed surfaces are made into contact surfaces with the outer circumferences of the needle rollers, and groove-shaped relief portions extending in the radial direction are provided on the side surfaces on both circumferential sides of the column inclined portions so as to recess the side surfaces on both circumferential sides of the column inclined portions in the circumferential direction with respect to the surface pressing processed surfaces. The shell-shaped needle roller bearing is characterized by this.

[0012] When this configuration is adopted, since the surface pressing processed surfaces corresponding to the hypotenuses of the trapezoids are formed on the side surfaces on both circumferential sides of the column central portion so that the cross-sectional shape of the column central portion becomes a trapezoid whose circumferential width gradually narrows toward the radially outer side, when the needle roller contacts the column central portion, it does not contact the corner portions at the radially outer ends of the circumferential side surfaces of the column central portion, but makes surface contact with the surface pressing processed surfaces. Therefore, even when the position of the column central portion is shifted radially inward to narrow the circumferential gap between adjacent needle rollers, it is possible to prevent the needle roller from riding on the column central portion, and it becomes possible to stably guide the needle roller. Further, since the cross-sectional shape of the column central portion is a trapezoid whose circumferential width gradually narrows toward the radially outer side, even when the circumferential gap between adjacent needle rollers is narrow, it is easy to make the circumferential width of the column central portion large, and it is easy to ensure the strength of the cage.

[0013] In addition, since a relief portion is formed by recessing the circumferential side surface of the column inclined portion in the circumferential direction with respect to the surface pressing surface, when a die having a concave portion with a trapezoidal cross section is pressed against the central portion of the column to plastically process the central portion of the column into a trapezoidal cross section, it is possible to bring the die into contact only with the central portion of the column while preventing the die from interfering with the column inclined portion. Therefore, it is possible to stably form the surface pressing surface (the surface corresponding to the hypotenuse of the trapezoid) of the central portion of the column.

[0014] In addition, a circumferential gap is formed between the relief portion and the needle roller, and since this gap functions as a flow path for oil that lubricates the inside of the shell-type needle roller bearing, it is possible to prevent oil film breakdown of the needle roller.

[0015] [Configuration 2] The outer diameter of the column end portion is formed to be larger than the outer diameter of the central portion of the column, and the inner diameter of the column end portion is formed to be smaller than the outer diameter of the central portion of the column. The shell-type needle roller bearing according to Configuration 1, wherein end guide surfaces that extend perpendicularly in the circumferential direction so as to intersect the surface pressing surface when viewed from the axial direction and that contact the outer circumference of the needle roller are formed on both side surfaces in the circumferential direction of the column end portion.

[0016] When this configuration is adopted, since the outer diameter of the column end portion is formed to be larger than the outer diameter of the central portion of the column and the inner diameter of the column end portion is formed to be smaller than the outer diameter of the central portion of the column, when viewed from the axial direction, the central portion of the column and the end portion of the column overlap with each other, and the shape of the column portion has a small change in the radial position along the axial direction. Therefore, when the needle roller contacts the central portion of the column, it is difficult for a torsional force around the axial direction to be generated in the column portion, and it is possible to enhance the durability of the cage.

[0017] In addition, since the end guide surface that contacts the outer circumference of the needle roller is formed on the column end portion, when the needle roller contacts the column end portion, the axial distance from the contact position to the root of the column portion is short. Therefore, it is possible to guide the needle roller while suppressing the moment load acting on the position of the root of the column portion due to the contact of the needle roller.

[0018] [Configuration 3] The shell-shaped needle roller bearing according to Configuration 2, wherein a concave arc-shaped corner R portion is formed between the end guide surface and the inner axial side surface of the annular portion to connect the two so as not to form a portion recessed in the circumferential direction with respect to the end guide surface.

[0019] When this configuration is adopted, since the corner R portion is provided so as not to form a portion recessed in the circumferential direction with respect to the end guide surface, it is possible to relieve the stress concentration at the base of the column portion at the corner R portion while ensuring the rigidity at the base of the column portion.

[0020] [Configuration 4] The shell-shaped needle roller bearing according to Configuration 2 or 3, wherein the surface roughness of the surface pressing processed surface is smaller than the surface roughness of the end guide surface.

[0021] When this configuration is adopted, since the surface roughness of the surface pressing processed surface is small, it is possible to prevent oil film breakage when the needle roller bearing comes into contact with the surface pressing processed surface. Therefore, even when a low-viscosity oil is used as the oil for lubricating the inside of the shell-shaped needle roller bearing, it is possible to ensure the bearing life.

[0022] [Configuration 5] The shell-shaped needle roller bearing according to any one of Configurations 2 to 4, having a convex arc-shaped central side R portion that smoothly connects the surface pressing processed surface and the relief portion when viewed in the radial direction, and a convex arc-shaped end side R portion that smoothly connects the end guide surface and the relief portion.

[0023] When this configuration is adopted, the surface pressing processed surface is smoothly connected to the relief portion via the convex arc-shaped central side R portion, and the end guide surface is smoothly connected to the relief portion via the convex arc-shaped end side R portion. Therefore, it is possible to prevent oil film breakage when the needle roller comes into contact with the surface pressing processed surface or the end guide surface.

[0024] [Configuration 6] When viewed from the axial direction, the position where the end guide surface intersects the surface pressing processed surface is within a range of 90% or less from the radially outer end of the surface pressing processed surface to the surface pressing processed surface, and the shell-shaped needle roller bearing according to any one of Configurations 2 to 5.

[0025] When this configuration is adopted, the circumferential play between the outer periphery of the end of the needle roller and the end guide surface is small, so it is possible to effectively prevent the skew of the needle roller (the axial direction of the needle roller tilts).

[0026] [Configuration 7] Among the pair of column ends facing each other in the circumferential direction with each needle roller interposed therebetween, the distance from the radially inner end of one column end to the radially inner end of the other column end (the shortest distance connected by a straight line) is set to 90% or more and 110% or less of the outer diameter of the needle roller, and the shell-shaped needle roller bearing according to any one of Configurations 1 to 6.

[0027] When this configuration is adopted, the circumferential play between the outer periphery of the end of the needle roller and the column end is small, so it is possible to effectively prevent the skew of the needle roller (the axial direction of the needle roller tilts).

Advantages of the Invention

[0028] In the shell-shaped needle roller bearing of this invention, the cross-sectional shape of the central part of the column is trapezoidal such that the circumferential width gradually narrows toward the radially outer side, and surface pressing processed surfaces corresponding to the oblique sides of the trapezoid are formed on the side surfaces on both circumferential sides of the central part of the column. Therefore, when the needle roller contacts the central part of the column, it does not contact the corner part at the radially outer end of the circumferential side surface of the central part of the column, but makes surface contact with the surface pressing processed surface. Therefore, even when the position of the central part of the column is shifted radially inward to narrow the circumferential gap between adjacent needle rollers, it is possible to prevent the needle roller from riding on the central part of the column, and it is possible to stably guide the needle roller. Further, since the cross-sectional shape of the central part of the column is trapezoidal such that the circumferential width gradually narrows toward the radially outer side, even when the circumferential gap between adjacent needle rollers is narrow, it is easy to increase the circumferential width of the central part of the column, and it is easy to ensure the strength of the cage.

[0029] In addition, since a relief portion is formed by recessing the circumferential side surface of the column inclined portion in the circumferential direction with respect to the surface pressing surface, when a die having a concave portion with a trapezoidal cross section is pressed against the central portion of the column to plastically process the central portion of the column into a trapezoidal cross section, it is possible to bring the die into contact only with the central portion of the column while preventing the die from interfering with the column inclined portion. Therefore, it is possible to stably form the surface pressing surface (the surface corresponding to the oblique side of the trapezoid) of the central portion of the column.

[0030] In addition, a circumferential gap is formed between the relief portion and the needle roller, and this gap functions as a flow path for oil that lubricates the inside of the shell type needle roller bearing, so it is possible to prevent oil film breakage of the needle roller.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0032] FIG. 1 shows a shell-shaped needle roller bearing according to an embodiment of the present invention. This shell-shaped needle roller bearing has a shell-shaped outer ring 1, a plurality of needle rollers 2, and a cage 3.

[0033] The shell-shaped outer ring 1 has a cylindrical portion 4 and a pair of flange portions 5 extending radially inward from both axial ends of the cylindrical portion 4. On the inner circumference of the cylindrical portion 4, a cylindrical outer ring raceway surface 6 with which the needle rollers 2 rollingly contact is formed. The shell-shaped outer ring 1 is a press-worked product formed by drawing a circular steel plate into a bottomed cylindrical shape. The plate thickness of the portion of the cylindrical portion 4 of the shell-shaped outer ring 1 where the outer ring raceway surface 6 is formed is set in the range of 0.5 mm or more and 1.2 mm or less (preferably 1.0 mm or less).

[0034] The axial direction is a direction parallel to the central axis of the shell-shaped outer ring 1 (the central axis of the bearing), the radial direction is a direction perpendicular to the central axis of the shell-shaped outer ring 1, and the circumferential direction is a direction along the circumference that circulates around the central axis of the shell-shaped outer ring 1. The cage 3 is formed symmetrically with respect to the axial center. Axially inward means a direction approaching the axial center of the cage 3 along the axial direction, and axially outward means a direction moving away from the axial center of the cage 3 along the axial direction.

[0035] The needle roller 2 is a roller having a cylindrical outer circumference with a constant outer diameter. Each needle roller 2 is arranged at regular intervals in the circumferential direction along the outer ring raceway surface 6 on the inner circumference of the shell-shaped outer ring 1. The diameter of the needle roller 2 is 6 mm or less, and the axial length of the needle roller 2 is 3 times or more and 10 times or less the diameter of the needle roller 2.

[0036] The cage 3 has a pair of annular portions 7 that face each other in the axial direction with a plurality of needle rollers 2 therebetween, and a plurality of column portions 8 that connect the pair of annular portions 7 through the spaces between the circumferentially adjacent needle rollers 2. The pair of annular portions 7 are respectively disposed to face the inner side surfaces in the axial direction of the pair of flange portions 5 of the shell-shaped outer ring 1, and by the pair of annular portions 7 contacting the pair of flange portions 5, the axial movement of the cage 3 relative to the shell-shaped outer ring 1 is restricted. The cage 3 is a steel cage formed by welding both ends of an annular steel strip in which a plurality of pockets 9 are formed at equal intervals in the circumferential direction. The cage 3 is a roller guide type cage that does not contact the cylindrical portion 4 of the shell-shaped outer ring 1 and positions the radial direction by contacting each needle roller 2.

[0037] As shown in Fig. 2, the column portion 8 and the pair of annular portions 7 adjacent to each other in the circumferential direction (the vertical direction in the figure) form a pocket 9 for accommodating the needle roller 2. The pocket 9 is a rectangular through-opening formed by penetrating the cage 3 in the radial direction (the direction perpendicular to the paper surface in the figure). The cage 3 accommodates the needle roller 2 in each pocket 9 and keeps the circumferential intervals of the plurality of needle rollers 2 by bringing the column portion 8 that partitions each pocket 9 in the circumferential direction into contact with the needle roller 2.

[0038] As shown in Fig. 3, the column portion 8 has a pair of column end portions 8a that extend axially inward from the pair of annular portions 7 with a constant outer diameter d1, a pair of column inclined portions 8b that extend obliquely so that the outer diameter gradually decreases toward the axially inner side from the pair of column end portions 8a, and a column central portion 8c that connects the pair of column inclined portions 8b. The column central portion 8c extends axially with a constant outer diameter d3 along the axial direction and connects the axially inner ends of the pair of column inclined portions 8b. The column end portion 8a is formed such that the outer diameter d1 of the column end portion 8a is larger than the outer diameter d3 of the column central portion 8c, and the inner diameter d2 of the column end portion 8a is smaller than the outer diameter d3 of the column central portion 8c.

[0039] Each annular portion 7 is formed in an annular shape extending in the circumferential direction along the axial end face of the needle roller 2. The cross-sectional shape of each annular portion 7 is a rectangular shape having the same radial height as the radial thickness of the column end portion 8a. This cage 3 is a V-shaped cage in which the annular portion 7 and the column portion 8 exhibit a V shape when viewed from the circumferential direction. The radial thickness of the annular portion 7 and the column end portion 8a is set to be 10% or more (preferably 20% or more, more preferably 35% or more) of the roller diameter of the needle roller 2.

[0040] As shown in FIG. 4, the positional relationship between the column central portion 8c and the column end portion 8a is set so that there is a portion where the column central portion 8c and the column end portion 8a overlap when viewed from the axial direction. In the figure, in the radial thickness of 10% or more (preferably 20% or more, more preferably 30% or more) from the radial outer end of the column central portion 8c toward the radial inner side in the entire radial thickness of the column central portion 8c, the column central portion 8c has a positional relationship of overlapping with the column end portion 8a. The column end portion 8a is formed in a rectangular cross-sectional shape with a constant circumferential width along the radial direction.

[0041] As shown in FIG. 6, surface pressing surfaces 10 are formed on both side surfaces in the circumferential direction of the central portion 8c of the column. The surface pressing surface 10 is a flat surface formed by pressing a die having a concave portion with a trapezoidal cross section against the central portion 8c of the column from the radially outer side to plastically deform the central portion 8c of the column into a trapezoidal cross section (surface pressing process). By forming this surface pressing surface 10, the cross-sectional shape of the central portion 8c of the column is a trapezoid whose circumferential width gradually narrows toward the radially outer side (upward in the figure). The surface pressing surface 10 is a surface corresponding to the hypotenuse of an isosceles trapezoid which is the cross-sectional shape of the central portion 8c of the column. The radially outer end of the surface pressing surface 10 intersects the circumferential end of the outer diameter surface of the central portion 8c of the column at an obtuse angle. The surface pressing surface 10 is formed over a region of 20% or more from the radially outer end of the central portion 8c of the column toward the radially inner side in the entire radial thickness of the central portion 8c of the column. The surface pressing surface 10 may be formed in a region of 40% or less from the radially outer end of the central portion 8c of the column toward the radially inner side in the entire radial thickness of the central portion 8c of the column. The surface pressing surface 10 has a smaller surface roughness than before the surface pressing process, and therefore, the surface roughness of the surface pressing surface 10 (the surface roughness of the surface pressing surface 10 measured along the axial direction) is smaller than the surface roughness of the end guiding surface 11 described later (the surface roughness of the end guiding surface 11 measured along the axial direction).

[0042] As shown in FIG. 7, among a pair of central portions 8c of the column facing each other with the needle roller 2 interposed therebetween, the distance from the radially inner end of one central portion 8c of the column to the radially inner end of the other central portion 8c of the column is smaller than the outer diameter of the needle roller 2. Thereby, when the needle roller 2 moves radially inward in a state where the axis S is absent, a pair of central portions 8c of the column facing each other with the needle roller 2 interposed therebetween restricts the radially inward movement of the needle roller 2, and prevents the needle roller 2 from dropping radially inward from the pocket 9.

[0043] As shown in Fig. 2, relief portions 12 are formed on the side surfaces on both circumferential sides (upper and lower sides in the figure) of the column inclined portion 8b, which recess the side surfaces on both circumferential sides of the column inclined portion 8b in the circumferential direction (up and down directions in the figure) with respect to the surface pressing processed surface 10. The relief portion 12 is a groove-shaped recess that extends through the circumferential side surface of the column inclined portion 8b in the radial direction (a direction perpendicular to the paper surface in the figure). The relief portion 12 is formed adjacent to both axial ends (left and right ends in the figure) of the surface pressing processed surface 10. The surface pressing processed surface 10 is continuously formed along the axial direction without interruption between a pair of relief portions 12 located on both axial sides of the surface pressing processed surface 10.

[0044] As shown in Fig. 4, flat end guiding surfaces 11 extending in a direction perpendicular to the circumferential direction are formed on the side surfaces on both circumferential sides (left and right sides in the figure) of the column end portion 8a. The end guiding surface 11 is provided so as to intersect the surface pressing processed surface 10 when viewed from the axial direction (a direction perpendicular to the paper surface in the figure). Also, when viewed from the axial direction, the position where the end guiding surface 11 intersects the surface pressing processed surface 10 is formed within a range of 90% or less (preferably 70% or less) from the radial outer end (upper end in the figure) of the surface pressing processed surface 10.

[0045] The radial outer end of the end guiding surface 11 intersects perpendicularly with the circumferential end of the outer diameter surface of the column end portion 8a. In the figure, the entire radial thickness of the column end portion 8a is taken as the end guiding surface 11, but the end guiding surface 11 may be formed over a region of 10% or more (preferably 20% or more, more preferably 50% or more) inward in the radial direction from the radial outer end of the column end portion 8a within the entire radial thickness of the column end portion 8a. Also, among a pair of column end portions 8a facing each other in the circumferential direction with the needle roller 2 shown in Fig. 7 interposed therebetween, the distance (the shortest distance connected by a straight line) from the radial inner end of one column end portion 8a (specifically, the radial inner end of the circumferential side surface of one column end portion 8a on the side facing the other column end portion 8a) to the radial inner end of the other column end portion 8a (specifically, the radial inner end of the circumferential side surface of the other column end portion 8a on the side facing the one column end portion 8a) is set to be 90% or more and 110% or less of the outer diameter of the needle roller 2.

[0046] As shown in Fig. 5, when viewed from the radial direction, a convex arc-shaped central side R portion 13 that smoothly connects the surface pressing processed surface 10 and the relief portion 12 is formed at the axial outer end (left end in the figure) of the surface pressing processed surface 10, and a convex arc-shaped end side R portion 14 that smoothly connects the end guiding surface 11 and the relief portion 12 is also formed at the axial inner end (right end in the figure) of the end guiding surface 11. Further, a concave arc-shaped corner R portion 15 that connects the end guiding surface 11 and the side surface on the axial inner side (right side in the figure) of the annular portion 7 so as not to form a portion recessed in the circumferential direction (up and down direction in the figure) with respect to the end guiding surface 11 is formed.

[0047] This cage 3 can be manufactured as follows.

[0048] First, a strip steel that is the material of the cage 3 is roll press formed so that the cross-sectional shape perpendicular to the longitudinal direction is V-shaped. Next, the pockets 9 shown in Fig. 2 are sequentially formed by punching the strip steel. By this punching process, the side surface on the axial inner side of the annular portion 7 shown in Fig. 5, the corner R portion 15, the circumferential side surface of the column end portion 8a, the end side R portion 14, the relief portion 12, the central side R portion 13, and the circumferential side surface of the column central portion 8c (the side surface in the state before forming the surface pressing processed surface 10) are formed. Here, the punching process is performed so as to punch from the side corresponding to the outer side in the radial direction of the cage 3 toward the side corresponding to the inner side in the radial direction. As a result, on the circumferential side surface of the column end portion 8a, a shear cross-section and a fracture cross-section are sequentially formed from the outer side in the radial direction toward the inner side in the radial direction, and the shear cross-section becomes the end guiding surface 11. The shear cross-section is a smooth surface that extends straight in the plate thickness direction (punching direction), and the fracture cross-section is an irregular uneven surface generated by tearing the material of the steel strip. Thereafter, a die (not shown) having a concave portion with a trapezoidal cross-section is pressed against the column central portion 8c from the side corresponding to the outer side in the radial direction of the cage 3 to perform a process (surface pressing process) of plastically deforming the column central portion 8c into a trapezoidal cross-section, thereby forming the surface pressing processed surfaces 10 on both sides of the column central portion 8c as shown in Fig. 4. Thereafter, the strip steel is cut to a predetermined length, bent into a cylindrical shape, both ends of the strip steel bent into the cylindrical shape are welded, and finally heat treatment is performed to obtain the cage 3 shown in Fig. 1.

[0049] As described below, in this cage 3, the surface pressing surface 10 and the end guiding surface 11 come into contact with the outer periphery of the needle roller 2, and by this contact, the circumferential interval of the needle roller 2 is maintained.

[0050] That is, when the shell-type needle roller bearing shown in Fig. 1 is rotating, the radial load applied to the shell-type needle roller bearing is supported by some of the needle rollers 2 passing through the region (load region) where the radial load is applied among all the needle rollers 2 arranged on the entire circumference. And the needle roller 2 is particularly likely to cause a retardation in its load region and come into contact with the column portion 8 of the cage 3. Further, when the shell-type needle roller bearing shown in Fig. 1 is assembled and used in a state where the axial direction is horizontal, the cage 3 drops due to its own weight, and the central position of the cage 3 is eccentric downward with respect to the central position of the outer ring.

[0051] Therefore, when the load region is in the lower half circumference of the shell-type needle roller bearing, as shown in Figs. 7 and 8, the outer periphery of the needle roller 2 in the load region comes into contact with the surface pressing surface 10 of the column central portion 8c. Here, the needle roller 2 is in contact with the surface pressing surface 10 at a radial position included within the range of the radial thickness of the column end portion 8a (the contact position between the needle roller 2 and the column portion 8 is indicated by reference numeral P1 in Fig. 8). Therefore, it is difficult for a torsional force around the axial direction to occur in the column portion 8.

[0052] Also, when viewed from the axial direction, since the end guiding surface 11 and the surface pressing surface 10 are configured to intersect within a range of 90% or less (preferably 70% or less) from the radial outer end of the surface pressing surface 10 of the surface pressing surface 10, the circumferential play between the outer periphery of the end of the needle roller 2 and the end guiding surface 11 is small, and it is possible to effectively prevent the skew of the needle roller 2 (the axial direction of the needle roller 2 is inclined).

[0053] On the one hand, when the load region is in the upper half circumference of the shell-shaped needle roller bearing, as shown in FIGS. 9 and 10, the outer circumference of the end of the needle roller 2 in the load region contacts the end guide surface 11 of the column end 8a. At this time, the axial distance from the contact position P2 between the needle roller 2 and the column part 8 to the root of the column part 8 becomes short. Therefore, the moment load acting on the position of the root of the column part 8 (the position of the corner R part 15 shown in FIG. 6) is small.

[0054] As shown in FIG. 6, in this shell-shaped needle roller bearing, the cross-sectional shape of the column central part 8c is trapezoidal with the circumferential width gradually narrowing toward the radially outer side, and surface pressing surfaces 10 corresponding to the hypotenuse of the trapezoid are formed on the side surfaces on both circumferential sides of the column central part 8c. Therefore, as shown in FIG. 7, when the needle roller 2 contacts the column central part 8c, it does not contact the corner part at the radially outer end of the circumferential side surface of the column central part 8c, but makes surface contact with the surface pressing surface 10. Therefore, even when the position of the column central part 8c is moved radially inward to narrow the circumferential gap between adjacent needle rollers 2, it is possible to prevent the needle roller 2 from riding on the column central part 8c, and the needle roller 2 can be stably guided. Further, as shown in FIG. 7, since the cross-sectional shape of the column central part 8c is trapezoidal with the circumferential width gradually narrowing toward the radially outer side, even when the circumferential gap between adjacent needle rollers 2 is narrow, it is easy to make the circumferential width of the column central part 8c large, and it is easy to ensure the strength of the cage 3.

[0055] Also, as shown in FIGS. 5 and 6, since a relief part 12 is formed by recessing the circumferential side surface of the column inclined part 8b in the circumferential direction with respect to the surface pressing surface 10, when a die having a concave part with a trapezoidal cross-section is pressed against the column central part 8c to plastically process the column central part 8c into a trapezoidal cross-section, it is possible to contact the die only with the column central part 8c while preventing the die from interfering with the column inclined part 8b. Therefore, it is possible to stably form the surface pressing surface 10 (the surface corresponding to the hypotenuse of the trapezoid) of the column central part 8c.

[0056] Also, as shown in Fig. 2, a circumferential gap is formed between the relief portion 12 and the needle roller 2, and this gap functions as a flow path for oil that lubricates the inside of the shell-type needle roller bearing. Therefore, it is possible to prevent oil film breakage of the needle roller 2.

[0057] Further, as shown in Fig. 3, in this shell-type needle roller bearing, the outer diameter d1 of the column end portion 8a is larger than the outer diameter d3 of the column central portion 8c, and the inner diameter d2 of the column end portion 8a is smaller than the outer diameter d3 of the column central portion 8c. Thus, as shown in Fig. 4, when viewed from the axial direction, the column central portion 8c and the column end portion 8a overlap each other, and the shape of the column portion 8 has a small radial position change along the axial direction. Therefore, as shown in Fig. 7, when the needle roller 2 contacts the column central portion 8c, a torsional force around the axial direction is less likely to occur in the column portion 8, and it is possible to enhance the durability of the cage 3.

[0058] Also, as shown in Fig. 9, in this shell-type needle roller bearing, the end guide surface 11 that contacts the outer periphery of the needle roller 2 is formed on the column end portion 8a. Therefore, as shown in Fig. 10, when the needle roller 2 contacts the column end portion 8a, the axial distance from the contact position P2 to the base of the column portion 8 (the corner R portion 15) is short. Therefore, it is possible to guide the needle roller 2 while suppressing the moment load acting on the position of the base of the column portion 8 (the position of the corner R portion 15) due to the contact of the needle roller 2.

[0059] Also, as shown in Fig. 5, in this shell-type needle roller bearing, the corner R portion 15 is provided so as not to form a portion that is recessed in the circumferential direction with respect to the end guide surface 11. Therefore, while ensuring the rigidity of the base of the column portion 8 (the magnitude of the circumferential width of the base of the column portion 8), it is possible to relieve stress concentration at the base of the column portion 8 at the corner R portion 15.

[0060] 7 and 8, this drawn cup needle roller bearing has small surface roughness on the face-pressed surface 10, which prevents oil film breakdown when the needle roller bearing comes into contact with the face-pressed surface 10. Therefore, even when low-viscosity oil is used to lubricate the inside of the drawn cup needle roller bearing, it is possible to ensure a long bearing life.

[0061] Furthermore, as shown in Figure 5, in this drawn cup needle roller bearing, the face-pressed surface 10 is smoothly connected to the relief portion 12 via the convex arc-shaped central side R portion 13, and the end guide surface 11 is smoothly connected to the relief portion 12 via the convex arc-shaped end side R portion 14, so it is possible to prevent oil film breakdown when the needle roller 2 comes into contact with the face-pressed surface 10 or the end guide surface 11.

[0062] Furthermore, in this shell-type needle roller bearing, of the pair of column end portions 8a that face each other circumferentially with each needle roller 2 sandwiched therebetween as shown in Figure 7, the distance from the radial inner end of one column end portion 8a to the radial inner end of the other column end portion 8a is set to be 90% or more and 110% or less of the outer diameter of the needle roller 2, so that there is little circumferential play between the outer periphery of the end of the needle roller 2 and the end guide surface 11, making it possible to effectively prevent skewing of the needle roller 2 (tilting of the axial direction of the needle roller 2).

[0063] In the above embodiment, the retainer 3 is described as an example of a V-shaped retainer in which the annular portion 7 and the column portion 8 are V-shaped when viewed circumferentially, but the present invention can also be applied to M-shaped retainers and W-shaped retainers.

[0064] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0065] 1 Drawn cup outer ring 2 needle rollers 3 Cage 7 Annular part 8 Column part 8a Column end part 8b Column inclined part 8c Column central part 9 Pocket 10 Surface pressing processed surface 11 End guiding surface 12 Relief part 13 Central side R part 14 End side R part 15 Corner R part d1 Outer diameter of column end part d2 Inner diameter of column end part d3 Outer diameter of column central part S Axis

Claims

1. A shell-shaped outer ring (1); A plurality of needle rollers (2) arranged at intervals in the circumferential direction along the inner circumference of the shell-shaped outer ring (1); A cage (3) for maintaining the circumferential interval of the plurality of needle rollers (2), The cage (3) has a pair of annular portions (7) facing each other in the axial direction with the needle rollers (2) therebetween, and a plurality of column portions (8) connecting the pair of annular portions (7) passing between the circumferentially adjacent needle rollers (2); In the shell-shaped needle roller bearing, each of the column portions (8) has a pair of column end portions (8a) extending axially inward from the pair of annular portions (7) with a constant outer diameter (d1), a pair of column inclined portions (8b) extending obliquely so that the outer diameter gradually decreases toward the axially inner side from the pair of column end portions (8a), and a column central portion (8c) connecting the pair of column inclined portions (8b). Surface pressing processed surfaces (10) corresponding to the hypotenuses of the trapezoids are formed on the side surfaces on both circumferential sides of the column central portion (8c) so that the cross-sectional shape of the column central portion (8c) is trapezoidal with the circumferential width gradually narrowing toward the radially outer side, and the surface pressing processed surfaces (10) are the contact surfaces with the outer circumferences of the needle rollers (2). A shell-shaped needle roller bearing, characterized in that groove-shaped relief portions (12) extending in the radial direction are provided on the side surfaces on both circumferential sides of the column inclined portions (8b) so as to be recessed in the circumferential direction with respect to the surface pressing processed surfaces (10).

2. The column end portions (8a) are formed such that the outer diameter (d1) of the column end portions (8a) is larger than the outer diameter (d3) of the column central portion (8c), and the inner diameter (d2) of the column end portions (8a) is smaller than the outer diameter (d3) of the column central portion (8c). End guiding surfaces (11) that extend at right angles in the circumferential direction so as to intersect the surface pressing processed surfaces (10) when viewed axially and contact the outer circumferences of the needle rollers (2) are formed on the side surfaces on both circumferential sides of the column end portions (8a). The shell-shaped needle roller bearing according to Claim 1

3. A concave arc-shaped corner R portion (15) that connects the end guiding surfaces (11) and the axially inner side surfaces of the annular portions (7) is formed so as not to cause a portion recessed in the circumferential direction with respect to the end guiding surfaces (11). The shell-shaped needle roller bearing according to Claim 2

4. 4. A drawn cup needle roller bearing according to claim 2, wherein the surface roughness of said face-pressed surface (10) is smaller than the surface roughness of said end guide surface (11).

5. 4. A drawn cup needle roller bearing according to claim 2 or 3, having, when viewed from the radial direction, a convex arc-shaped central R portion (13) that smoothly connects the face-pressed surface (10) and the relief portion (12), and a convex arc-shaped end R portion (14) that smoothly connects the end guide surface (11) and the relief portion (12).

6. 4. A drawn cup needle roller bearing according to claim 2 or 3, wherein the position at which the end guide surface (11) intersects with the face-pressed surface (10) is within a range of 90% of the face-pressed surface (10) from the radial outer end of the face-pressed surface (10) when viewed from the axial direction.

7. 4. A drawn cup needle roller bearing according to claim 1, wherein, of the pair of column end portions (8 a) that face each other in the circumferential direction with each needle roller (2) sandwiched therebetween, the distance from the radially inner end of one column end portion (8 a) to the radially inner end of the other column end portion (8 a) (the shortest distance connected in a straight line) is set to be 90% or more and 110% or less of the outer diameter of each needle roller (2).

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