Shell-shaped needle bearing

Abstract

The invention provides a shell-shaped needle bearing capable of ensuring the strength of a retainer and stably guiding needle rollers through the retainer even when the circumferential gap between adjacent needle rollers is narrow. The shell-shaped needle bearing is characterized in that: pressing surfaces (10) are formed on both side surfaces in the circumferential direction of the column center section (8c) so that the cross-sectional shape of the column center section (8c) forms a trapezoid in which the width in the circumferential direction gradually narrows toward the outside in the radial direction, the pressing surfaces (10) corresponding to the bevel edges of the trapezoid, and pressing surfaces (10) are formed on both side surfaces in the circumferential direction of the column center section (8c); groove-shaped relief parts (12) are provided so that the side surfaces on both sides in the circumferential direction of the column inclined part (8b) are recessed in the circumferential direction with respect to the press surface (10), and the relief parts (12) extend in the radial direction on the side surfaces on both sides in the circumferential direction of the column inclined part (8b).

Description

Technical Field

[0001] The present invention relates to a shell-shaped needle roller bearing. Background Art

[0002] Compared with other forms of rolling bearings, the shell-shaped outer ring type needle roller bearing has a small radial thickness and a high load capacity, and is therefore widely used in fields such as automobiles and industrial machinery (for example, Patent Document 1).

[0003] The shell-shaped needle roller bearing of Patent Document 1 has: a shell-shaped outer ring formed by deep drawing of 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 retainer for maintaining the circumferential intervals of the plurality of needle rollers.

[0004] The retainer has: a pair of ring portions facing each other in the axial direction with a needle roller interposed therebetween; and a plurality of column portions passing between circumferentially adjacent needle rollers and connecting the pair of ring portions. Here, the circumferentially adjacent column portions and the pair of ring portions form a pocket for receiving the needle roller. A plurality of pockets are sequentially formed in the strip steel that becomes the retainer by blanking, the strip steel having the pockets formed therein is cut into a predetermined length and bent into a cylindrical shape, and the ends of the strip steel bent into the cylindrical shape are welded to form the retainer.

[0005] In addition, each column portion constituting the retainer has: a pair of column end portions extending from the pair of ring portions toward the inside in the axial direction with a constant outer diameter; a pair of column inclined portions extending obliquely such that the outer diameter gradually decreases from the pair of column end portions toward the inside in the axial direction; and a column central portion connecting the pair of column inclined portions. The circumferential side surface of the column portion (column end portion, column inclined portion, column central portion) maintains the blanking cross section formed by the blanking of the pocket, and therefore, the cross-sectional shape of the column portion becomes a square having a constant circumferential width along the radial direction.

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2007-16828

[0007] The inventors of the present application studied the following: in the shell-shaped needle roller bearing as in Patent Document 1, in order to increase the load capacity, the number of needle rollers is increased without changing the bearing size.

[0008] That is, in the shell-shaped needle roller bearing as in 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, the circumferential width of the column central portion of the retainer disposed between circumferentially adjacent needle rollers also needs to be reduced, and the strength of the retainer is lowered. Therefore, the inventors of the present application focused on the fact that the circumferential gap between adjacent needle rollers has a shape that gradually widens from the position of the pitch circle of the needle roller toward the inside in the radial direction, and studied to ensure the circumferential width of the column central portion of the retainer by making the position of the column central portion of the retainer closer to the inside in the radial direction than before.

[0009] However, when the position of the central portion of the column of the retainer is brought closer to the radially inner side, there is a concern that the position where the needle roller contacts the central portion of the column becomes a corner portion at the radially outer end of the circumferential side of the central portion of the column. In this case, there is a concern that the central portion of the column is pressed radially inward due to the needle roller climbing on the central portion of the column and contacts the shaft. Summary of the Invention

[0010] The problem to be solved by the present invention is to provide a shell type needle roller bearing that can ensure the strength of the retainer even when the circumferential gap between adjacent needle rollers is narrow and can stably guide the needle rollers through the retainer.

[0011] To solve the above problems, in the present invention, a shell type needle roller bearing having the following structure is provided.

[0012] [Structure 1]

[0013] A shell type needle roller bearing having:

[0014] A shell-shaped outer ring;

[0015] A plurality of needle rollers arranged at intervals in the circumferential direction along the inner circumference of the shell-shaped outer ring; and

[0016] A retainer that maintains the circumferential interval of the plurality of needle rollers,

[0017] The retainer has: a pair of ring portions opposed to each other in the axial direction with the needle rollers interposed therebetween; and a plurality of column portions that pass between the needle rollers adjacent in the circumferential direction and connect the pair of ring portions,

[0018] Each of the column portions has: a pair of column end portions extending axially inward from the pair of ring portions with a constant outer diameter; a pair of column inclined portions extending obliquely such that the outer diameter gradually decreases from the pair of column end portions toward the axial inner side; and a column central portion that connects the pair of column inclined portions,

[0019] The shell type needle roller bearing is characterized in that

[0020] Pressing surface machining surfaces are formed on the circumferential sides on both sides of the column central portion in such a way that the cross-sectional shape of the column central portion becomes a trapezoid whose circumferential width gradually narrows toward the radially outer side. The pressing surface machining surfaces correspond to the hypotenuses of the trapezoid. The pressing surface machining surfaces are formed as contact surfaces with the outer circumference of the needle roller. Grooved avoidance portions are provided on the circumferential sides on both sides of the column inclined portion so as to be recessed in the circumferential direction with respect to the pressing surface machining surfaces. The avoidance portions extend radially on the circumferential sides on both sides of the column inclined portion.

[0021] If such a structure is adopted, press surfaces are formed on the side surfaces on both circumferential sides of the central portion of the column in such a manner that the cross-sectional shape of the central portion of the column is a trapezoid whose circumferential width gradually narrows toward the radially outer side. The press surfaces correspond to the hypotenuses of the trapezoid. Therefore, when the needle roller contacts the central portion of the column, it is in surface contact with the press surface and does not contact the corner portion at the radially outer end of the circumferential side surface of the central portion of the column. Therefore, even when the position of the central portion of the column is moved closer to the radially inner side in order to reduce the circumferential gap between adjacent needle rollers, it is possible to prevent the needle roller from climbing onto the central portion of the column, and the needle roller can be stably guided. In addition, the cross-sectional shape of the central portion of the column is formed as a trapezoid whose circumferential width gradually narrows toward the radially outer side. Therefore, when the circumferential gap between adjacent needle rollers is narrow, it is also easy to make the circumferential width of the central portion of the column large, and it is easy to ensure the strength of the cage.

[0022] In addition, a relief portion is formed in which the circumferential side surface of the inclined portion of the column is recessed in the circumferential direction with respect to the press surface. Therefore, when a mold 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 prevent the mold from interfering with the inclined portion of the column and to make the mold contact only the central portion of the column. Therefore, it is possible to stably form the press surface (the surface corresponding to the hypotenuse of the trapezoid) of the central portion of the column.

[0023] 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 for lubricating the inside of the toroidal needle roller bearing. Therefore, it is possible to prevent the oil film of the needle roller from breaking.

[0024] [Structure 2]

[0025] According to the toroidal needle roller bearing described in Structure 1,

[0026] The column end portion is formed such that the outer diameter of the column end portion is larger than the outer diameter of the central portion of the column and the inner diameter of the column end portion is smaller than the outer diameter of the central portion of the column.

[0027] End guiding surfaces are formed on the side surfaces on both circumferential sides of the column end portion. The end guiding surfaces extend at a right angle to the circumferential direction so as to intersect the press surface when viewed from the axial direction, and contact the outer circumference of the needle roller.

[0028] If such a structure is adopted, the column end portion is formed such that the outer diameter of the column end portion is larger than the outer diameter of the central portion of the column and the inner diameter of the column end portion is smaller than the outer diameter of the central portion of the column. Therefore, when viewed from the axial direction, the central portion of the column and the column end portion are in an overlapping positional relationship, and the shape of the column portion is such that the radial position change is small along the axial direction. Therefore, when the needle roller contacts the central portion of the column, it is not easy to generate torque around the axial direction in the column portion, and the durability of the cage can be improved.

[0029] In addition, an end guiding surface that contacts the outer periphery of the needle roller is formed at the column end portion. Therefore, 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, the moment load acting on the position of the root of the column portion due to the contact of the needle roller can be suppressed, and the needle roller can be guided.

[0030] [Structure 3]

[0031] According to the cup-shaped needle roller bearing described in Structure 2, wherein,

[0032] A concave arc-shaped corner R portion that connects the end guiding surface and the side surface on the inner side in the axial direction of the ring portion without forming a circumferentially recessed portion with respect to the end guiding surface is formed therebetween.

[0033] If this structure is adopted, since the corner R portion is provided without forming a circumferentially recessed portion with respect to the end guiding surface, the rigidity of the root of the column portion can be ensured, and the stress concentration at the root of the column portion can be alleviated by the corner R portion.

[0034] [Structure 4]

[0035] According to the cup-shaped needle roller bearing described in Structure 2 or 3, wherein,

[0036] The surface roughness of the pressing surface machining surface is smaller than the surface roughness of the end guiding surface.

[0037] If this structure is adopted, since the surface roughness of the pressing surface machining surface is small, oil film rupture can be prevented when the needle roller bearing contacts the pressing surface machining surface. Therefore, even when a low-viscosity oil is used as the oil for lubricating the inside of the cup-shaped needle roller bearing, the bearing life can be ensured.

[0038] [Structure 5]

[0039] According to the cup-shaped needle roller bearing described in any one of Structures 2 to 4, wherein,

[0040] There are provided a convex arc-shaped central side R portion that smoothly connects the pressing surface machining surface and the avoiding portion when viewed radially, and a convex arc-shaped end side R portion that smoothly connects the end guiding surface and the avoiding portion.

[0041] If this structure is adopted, the pressing surface machining surface is smoothly connected to the avoiding portion via the convex arc-shaped central side R portion, and the end guiding surface is smoothly connected to the avoiding portion via the convex arc-shaped end side R portion. Therefore, oil film rupture can be prevented when the needle roller contacts the pressing surface machining surface or the end guiding surface.

[0042] [Structure 6]

[0043] According to the cup-shaped needle roller bearing described in any one of Structures 2 to 5, wherein,

[0044] When viewed axially, the position where the above-mentioned end guide surface intersects the above-mentioned pressing surface machining surface is within a range of 90% or less from the radially outer end of the above-mentioned pressing surface machining surface.

[0045] If this structure is adopted, the circumferential clearance between the outer periphery of the end portion of the needle roller and the end guide surface is small, so that the skew of the needle roller (the inclination of the axis direction of the needle roller) can be effectively prevented.

[0046] [Structure 7]

[0047] For the cup-shaped needle roller bearing according to any one of Structures 1 to 6, wherein,

[0048] The distance (the shortest distance connected by a straight line) from the radially inner end of one of the pair of column end portions facing each other in the circumferential direction across the above-mentioned respective needle rollers to the radially inner end of the other column end portion is set to be 90% or more and 110% or less of the outer diameter of the above-mentioned needle roller.

[0049] If this structure is adopted, the circumferential clearance between the outer periphery of the end portion of the needle roller and the column end portion is small, so that the skew of the needle roller (the inclination of the axis direction of the needle roller) can be effectively prevented.

[0050] In the cup-shaped needle roller bearing of the present invention, pressing surface machining surfaces are formed on the side surfaces on both sides in the circumferential direction of the central portion of the column in such a way that the cross-sectional shape of the central portion of the column becomes a trapezoid whose circumferential width gradually narrows toward the radially outer side, and this pressing surface machining surface corresponds to the hypotenuse of the trapezoid. Therefore, when the needle roller contacts the central portion of the column, it is in surface contact with the pressing surface machining surface and does not contact the corner portion at the radially outer end of the circumferential side surface of the central portion of the column. Therefore, even when the position of the central portion of the column is moved closer to the radially inner side in order to reduce the circumferential clearance between adjacent needle rollers, it is possible to prevent the needle roller from climbing onto the central portion of the column and to stably guide the needle roller. In addition, since the cross-sectional shape of the central portion of the column is formed into a trapezoid whose circumferential width gradually narrows toward the radially outer side, it is easy to make the circumferential width of the central portion of the column larger when the circumferential clearance between adjacent needle rollers is narrow, and it is easy to ensure the strength of the cage.

[0051] In addition, a relief portion is formed in which the circumferential side surface of the column inclined portion is recessed in the circumferential direction with respect to the pressing surface machining surface. Therefore, when a mold having a concave portion with a trapezoidal cross section is pressed against the central portion of the column to plastically machine the central portion of the column into a trapezoidal cross section, it is possible to prevent the mold from interfering with the column inclined portion and to make the mold contact only the central portion of the column. Therefore, it is possible to stably form the pressing surface machining surface (the surface corresponding to the hypotenuse of the trapezoid) of the central portion of the column.

[0052] In addition, a circumferential gap is formed between the avoidance portion and the needle roller, and this gap functions as a flow path for oil lubricating the interior of the cup-shaped needle roller bearing, so that rupture of the oil film of the needle roller can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is a cross-sectional view of a cup-shaped needle roller bearing according to an embodiment of the present invention.

[0054] Figure 2 is a view of the needle rollers and cage of the cup-shaped needle roller bearing Figure 1 viewed from the outer diameter side.

[0055] Figure 3 is a cross-sectional view along line III-III Figure 2 shown in FIG.

[0056] Figure 4 is a cross-sectional view along line IV-IV Figure 2 shown in FIG.

[0057] Figure 5 is a view magnifying the vicinity of the end of the pocket of the cage Figure 2 shown in FIG.

[0058] Figure 6 is Figure 2 a partial perspective view of the cage shown in FIG.

[0059] Figure 7 is a view showing the state Figure 4 wherein the needle roller shown in FIG. is in contact with the pressing surface machining surface at the center of the column.

[0060] Figure 8 is a view of the contact position between the needle roller and the center of the column Figure 7 shown in FIG. viewed circumferentially.

[0061] Figure 9 is a view showing the state Figure 4 wherein the needle roller shown in FIG. is in contact with the end guiding surface at the end of the column.

[0062] Figure 10 is a view of the contact position between the needle roller and the center of the column Figure 9 shown in FIG. viewed circumferentially.

[0063] REFERENCE MARK DESCRIPTION

[0064] 1... housing-shaped outer ring; 2... needle roller; 3... cage; 7... ring portion; 8... column portion; 8a... column end portion; 8b... column inclined portion; 8c... column central portion; 9... pocket; 10... pressing surface machining surface; 11... end guiding surface; 12... avoiding portion; 13... central side R portion; 14... end side R portion; 15... corner R portion; d1... outer diameter of column end portion; d2... inner diameter of column end portion; d3... outer diameter of column central portion; S... shaft. Detailed implementation

[0065] Figure 1 Indicates a housing-shaped needle roller bearing related to the implementation of the present invention. This housing-shaped needle roller bearing has a housing-shaped outer ring 1, a plurality of needle rollers 2 and a cage 3.

[0066] The housing-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. An annular outer ring raceway surface 6 is formed on the inner circumference of the cylindrical portion 4, and this outer ring raceway surface 6 is in rolling contact with the needle roller 2. The housing-shaped outer ring 1 is a stamped part formed by deep drawing a circular steel plate into a bottomed cylindrical shape. The plate thickness of the portion of the cylindrical portion 4 of the housing-shaped outer ring 1 where the outer ring raceway surface 6 is formed is set within the range of 0.5 mm or more and 1.2 mm or less (preferably 1.0 mm or less).

[0067] The axial direction refers to the direction parallel to the central axis of the housing-shaped outer ring 1 (the central axis of the bearing), the radial direction refers to the direction perpendicular to the central axis of the housing-shaped outer ring 1, and the circumferential direction refers to the direction along the circumference surrounding the central axis of the housing-shaped outer ring 1. The cage 3 is formed symmetrically with respect to the axial center. The axial inner side refers to the direction along the axis approaching the axial center of the cage 3, and the axial outer side refers to the direction along the axis away from the axial center of the cage 3.

[0068] The needle roller 2 is a roller having a cylindrical outer circumference with a constant outer diameter. Each needle roller 2 is arranged at a constant interval in the circumferential direction along the outer ring raceway surface 6 on the inner circumference of the housing-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.

[0069] The cage 3 has: a pair of ring portions 7, opposed to each other in the axial direction with a plurality of needle rollers 2 interposed therebetween; and a plurality of column portions 8, passing through between adjacent needle rollers 2 in the circumferential direction and connecting the pair of ring portions 7. The pair of ring portions 7 are respectively opposed to the inner side surfaces of the pair of flange portions 5 of the housing-shaped outer ring 1, and the pair of ring portions 7 are in contact with the pair of flange portions 5, thereby restricting the axial movement of the cage 3 relative to the housing-shaped outer ring 1. The cage 3 is a steel cage formed by welding the two ends of a circular steel strip formed with a plurality of pockets 9 at equal intervals in the circumferential direction. The cage 3 is a roller guiding type cage that is radially positioned by contacting each needle roller 2 and not contacting the cylindrical portion 4 of the housing-shaped outer ring 1.

[0070] As shown Figure 2 in the figure, the circumferentially adjacent (in the up-and-down direction in the figure) column portions 8 and a pair of ring portions 7 form a pocket 9 for accommodating the needle rollers 2. The pocket 9 is a square through-opening formed by penetrating the cage 3 in the radial direction (in the direction perpendicular to the paper surface in the figure). The cage 3 accommodates the needle rollers 2 in each pocket 9, and maintains the circumferential intervals of the plurality of needle rollers 2 by bringing the column portions 8 that demarcate each pocket 9 in the circumferential direction into contact with the needle rollers 2.

[0071] As shown Figure 3 in the figure, the column portion 8 has: a pair of column end portions 8a extending inward in the axial direction from the pair of ring portions 7 with a constant outer diameter d1; a pair of column inclined portions 8b inclined and extending such that the outer diameter gradually decreases from the pair of column end portions 8a toward the axial inner side; and a column central portion 8c connecting the pair of column inclined portions 8b. The column central portion 8c extends in the axial direction with a constant outer diameter d3 along the axial direction, and connects the axial inner ends of the pair of column inclined portions 8b to each other. 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.

[0072] Each ring portion 7 is formed in an annular shape extending in the circumferential direction along the axial end surface of the needle roller 2. The cross-sectional shape of each ring portion 7 is formed as a square having a radial height equal to the radial thickness of the column end portion 8a. The cage 3 is a V-shaped cage in which the ring portion 7 and the column portion 8 are V-shaped when viewed from the circumferential direction. The radial thicknesses of the ring portion 7 and the column end portion 8a are set to be 10% or more (preferably 20% or more, more preferably 35% or more) of the roller diameter of the needle roller 2.

[0073] As shown Figure 4 in the figure, the positional relationship between the column central portion 8c and the column end portion 8a is set such 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, at a radial thickness of 10% or more (preferably 20% or more, more preferably 30% or more) from the radially outer end of the column central portion 8c toward the radially inner side in the entire radial thickness of the column central portion 8c, the positional relationship where the column central portion 8c and the column end portion 8a overlap is formed. The column end portion 8a is formed as a square cross-section having a constant circumferential width along the radial direction.

[0074] As shown Figure 6As shown, pressing surfaces 10 are formed on the side surfaces on both circumferential sides of the central portion 8c of the column. The pressing surfaces 10 are flat surfaces formed by performing a process (pressing process) of plastically deforming the central portion 8c of the column into a trapezoidal cross-section by pressing a mold having a concave portion with a trapezoidal cross-section against the central portion 8c of the column from the radially outer side. By forming the pressing surfaces 10, the cross-sectional shape of the central portion 8c of the column becomes a trapezoid whose circumferential width gradually narrows toward the radially outer side (upward in the figure). The pressing surfaces 10 are surfaces corresponding to the hypotenuses of the isosceles trapezoid that is the cross-sectional shape of the central portion 8c of the column. The radially outer ends of the pressing surfaces 10 intersect the circumferential ends of the outer diameter surface of the central portion 8c of the column at an obtuse angle. The pressing surfaces 10 are 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 pressing surfaces 10 may also be formed over 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. Since the surface roughness of the pressing surfaces 10 becomes smaller than that before processing by performing the pressing process, the surface roughness of the pressing surfaces 10 (the surface roughness of the pressing surfaces 10 measured along the axial direction) is smaller than the surface roughness of the end guiding surfaces 11 (the surface roughness of the end guiding surfaces 11 measured along the axial direction) described later.

[0075] As Figure 7 shown, the distance from the radially inner end of one of the pair of central portions 8c of the column facing each other across the needle roller 2 to the radially inner end of the other central portion 8c of the column is less than the outer diameter of the needle roller 2. Thus, in a state without the shaft S, when the needle roller 2 moves radially inward, the pair of central portions 8c of the column facing each other across the needle roller 2 restricts the radially inward movement of the needle roller 2 and prevents the needle roller 2 from falling off the pocket 9 radially inward.

[0076] As Figure 2 shown, relief portions 12 are formed on the side surfaces on both circumferential sides (upper and lower sides in the figure) of the inclined portion 8b of the column. The relief portions 12 recess the side surfaces on both circumferential sides of the inclined portion 8b of the column in the circumferential direction (up and down directions in the figure) with respect to the pressing surfaces 10. The relief portions 12 are groove-shaped recesses that penetrate the circumferential side surfaces of the inclined portion 8b of the column in the radial direction (the direction perpendicular to the paper surface in the figure) and extend. The relief portions 12 are formed to be adjacent to the axial ends (left and right ends in the figure) of the pressing surfaces 10. The pressing surfaces 10 are continuously formed without interruption along the axial direction between the pair of relief portions 12 located on both axial sides of the pressing surfaces 10.

[0077] As Figure 4As shown, planar end guiding surfaces 11 are formed on the side surfaces on both circumferential sides (left and right sides in the figure) of the column end 8a, and the end guiding surfaces 11 extend in a direction perpendicular to the circumferential direction. The end guiding surfaces 11 are arranged to intersect the pressing surface machining surface 10 when observed from the axial direction (direction perpendicular to the paper surface in the figure). In addition, the end guiding surfaces 11 are formed such that the position where the end guiding surfaces 11 intersect the pressing surface machining surface 10 is within 90% (preferably within 70%) of the pressing surface machining surface 10 from the radially outer end (upper end in the figure) of the pressing surface machining surface 10 when observed from the axial direction.

[0078] The radially outer end of the end guiding surface 11 perpendicularly intersects the circumferential end of the outer diameter surface of the column end 8a. In the figure, the entire radial thickness of the column end 8a is taken as the end guiding surface 11, but the end guiding surface 11 only needs to be formed in a region of 10% or more (preferably 20% or more, more preferably 50% or more) from the radially outer end of the column end 8a toward the radially inner side in the entire radial thickness of the column end 8a. In addition, from Figure 7 the radially inner end of one of the pair of column ends 8a that are circumferentially opposed across the needle roller 2 (specifically, the radially inner end of the circumferential side surface of one of the column ends 8a that faces the other column end 8a) to the radially inner end of the other column end 8a (specifically, the radially inner end of the circumferential side surface of the other column end 8a that faces the one column end 8a), the distance (the shortest distance connected by a straight line) is set to be 90% or more and 110% or less of the outer diameter of the needle roller 2.

[0079] As Figure 5 shown, when observed from the radial direction, a convex arc-shaped central side R portion 13 is formed at the axially outer end (left end in the figure) of the pressing surface machining surface 10, and a convex arc-shaped end side R portion 14 is also formed at the axially inner end (right end in the figure) of the end guiding surface 11. The central side R portion 13 smoothly connects the pressing surface machining surface 10 and the avoidance portion 12, and the end side R portion 14 smoothly connects the end guiding surface 11 and the avoidance portion 12. In addition, a concave arc-shaped corner R portion 15 that connects the end guiding surface 11 and the side surface on the axially inner side (right side in the figure) of the ring portion 7 without generating a portion that is recessed in the circumferential direction (up and down direction in the figure) with respect to the end guiding surface 11 is formed between them.

[0080] The retainer 3 can be manufactured as follows.

[0081] First, the strip steel as the material of the retainer 3 is roll-formed such that the cross-sectional shape perpendicular to the length direction is V-shaped. Next, by performing blanking on the strip steel, the Figure 2 pocket holes 9 shown are sequentially formed. Through this blanking, Figure 5The side on the axially inner side of the ring portion 7 shown, the corner R portion 15, the circumferential side of the column end portion 8a, the end side R portion 14, the avoidance portion 12, the central side R portion 13, the circumferential side of the column central portion 8c (the side in the state before forming the surface pressing processed surface 10). Here, the blanking process is performed by blanking from the side corresponding to the radially outer side of the retainer 3 toward the side corresponding to the radially inner side. As a result, on the circumferential side of the column end portion 8a, a shear surface and a fracture surface are sequentially formed from the radially outer side toward the radially inner side, and this shear surface becomes the end guiding surface 11. The shear surface is a smooth surface that extends straight in the plate thickness direction (blanking direction), and the fracture surface is an irregular concavo-convex surface generated by tearing the material of the steel strip. Then, 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 radially outer side of the retainer 3 to plastically deform the column central portion 8c into a trapezoidal cross section (surface pressing process), whereby as Figure 4 shown, the surface pressing processed surfaces 10 on both sides of the column central portion 8c are formed. Then, the strip steel is cut into a specified length and bent into a cylindrical shape, the two ends of the strip steel bent into this cylindrical shape are welded, and finally heat treatment is performed, whereby Figure 1 the retainer 3 shown is obtained.

[0082] For this retainer 3, as described below, the surface pressing processed surface 10 and the end guiding surface 11 are in contact with the outer circumference of the needle roller 2, and the circumferential interval of the needle roller 2 is maintained by this contact.

[0083] That is, when Figure 1 the shell type needle roller bearing shown rotates, the radial load applied to the shell type needle roller bearing is supported by a part of the needle rollers 2 in the region (load region) that is being loaded with the radial load among all the needle rollers 2 arranged in a full circumference. Moreover, the needle roller 2 is particularly prone to generate hysteresis and lead in this load region, and contact with the column portion 8 of the retainer 3 occurs. In addition, Figure 1 when the shell type needle roller bearing shown is used in a state where the axial direction is horizontal after assembly, the retainer 3 descends due to its own weight, and the center position of this retainer 3 is eccentric downward with respect to the center position of the outer ring.

[0084] Therefore, when the load region is in the lower half circumference of the shell type needle roller bearing, as Figure 7 、 Figure 8 shown, the outer circumference of the needle roller 2 located in the load region is in contact with the surface pressing processed surface 10 of the column central portion 8c. Here, the needle roller 2 is in contact with the surface pressing processed surface 10 at a radial position included within the radial thickness of the column end portion 8a ( Figure 8 the contact position of the needle roller 2 with the column portion 8 is indicated by the symbol P1 in

[0085] Further, when viewed axially, the end guide surface 11 and the press surface machining surface 10 are configured to intersect within a range of 90% or less (preferably 70% or less) of the press surface machining surface 10 from the radially outer end of the press surface machining surface 10. Therefore, the circumferential clearance between the outer periphery of the end of the needle roller 2 and the end guide surface 11 is small, and the skew of the needle roller 2 (tilt in the axial direction of the needle roller 2) can be effectively prevented.

[0086] On the other hand, in the case where the load region is located in the upper half circumference of the cup-shaped needle roller bearing, as Figure 9 , Figure 10 shown, the outer periphery of the end of the needle roller 2 located in the load region contacts the end guide surface 11 of the column end portion 8a. At this time, the axial distance from the contact position P2 of the needle roller 2 and the column portion 8 to the root of the column portion 8 is short. Therefore, the moment load acting on the position of the root of the column portion 8 (the position of the corner R portion 15 shown in Figure 6 ) is small.

[0087] As Figure 6 shown, in this cup-shaped needle roller bearing, press surface machining surfaces 10 are formed on both side surfaces in the circumferential direction of the column central portion 8c in such a manner that the cross-sectional shape of the column central portion 8c is a trapezoid whose circumferential width gradually narrows toward the radially outer side, and the press surface machining surfaces 10 correspond to the oblique sides of the trapezoid. Therefore, as Figure 7 shown, when the needle roller 2 contacts the column central portion 8c, it is in surface contact with the press surface machining surface 10 and does not contact the corner portion at the radially outer end of the circumferential side surface of the column central portion 8c. Therefore, even when the position of the column central portion 8c is moved closer to the radially inner side in order to reduce the circumferential clearance between adjacent needle rollers 2, it is possible to prevent the needle roller 2 from climbing onto the column central portion 8c, and the needle roller 2 can be stably guided. Further, as Figure 7 shown, the cross-sectional shape of the column central portion 8c is formed as a trapezoid whose circumferential width gradually narrows toward the radially outer side. Therefore, when the circumferential clearance between adjacent needle rollers 2 is narrow, it is easy to make the circumferential width of the column central portion 8c larger, and it is easy to ensure the strength of the cage 3.

[0088] Further, as Figure 5 , Figure 6 shown, a relief portion 12 is formed in which the circumferential side surface of the column inclined portion 8b is recessed in the circumferential direction with respect to the press surface machining surface 10. Therefore, when a mold having a concave portion with a trapezoidal cross-section is pressed against the column central portion 8c to plastically process the column central portion 8c into a trapezoidal cross-section, it is possible to prevent the mold from interfering with the column inclined portion 8b and to make the mold contact only the column central portion 8c. Therefore, the press surface machining surface 10 (the surface corresponding to the oblique side of the trapezoid) of the column central portion 8c can be stably formed.

[0089] Further, as Figure 2As shown, a circumferential gap is formed between the avoidance portion 12 and the needle roller 2, and this gap functions as a flow path for oil that lubricates the interior of the cup-shaped needle roller bearing. Therefore, it is possible to prevent the oil film of the needle roller 2 from breaking.

[0090] In addition, as Figure 3 shown, the cup-shaped needle roller bearing is formed with a column end portion 8a 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. Therefore, as Figure 4 shown, when viewed axially, the column central portion 8c and the column end portion 8a have an overlapping positional relationship, and the shape of the column portion 8 is such that the radial positional change is small along the axial direction. Therefore, as Figure 7 shown, when the needle roller 2 contacts the column central portion 8c, it is not easy to generate a torsional force around the axial direction in the column portion 8, and the durability of the cage 3 can be improved.

[0091] In addition, for this cup-shaped needle roller bearing, as Figure 9 shown, an end guiding surface 11 that contacts the outer circumference of the needle roller 2 is formed on the column end portion 8a. Therefore, as Figure 10 shown, when the needle roller 2 contacts the column end portion 8a, the axial distance from this contact position P2 to the root of the column portion 8 (corner R portion 15) is short. Therefore, it is possible to suppress the moment load acting on the position of the root of the column portion 8 (the position of the corner R portion 15) due to the contact of the needle roller 2 and guide the needle roller 2.

[0092] In addition, for this cup-shaped needle roller bearing, as Figure 5 shown, the corner R portion 15 is provided so as not to have a portion that is recessed in the circumferential direction with respect to the end guiding surface 11. Therefore, it is possible to ensure the rigidity of the root of the column portion 8 (the size of the circumferential width of the root of the column portion 8), and to relieve the stress concentration at the root of the column portion 8 through the corner R portion 15.

[0093] In addition, for this cup-shaped needle roller bearing, Figure 7 、 Figure 8 shown, the surface roughness of the pressing surface machining surface 10 is small. Therefore, it is possible to prevent the oil film from breaking when the needle roller bearing contacts the pressing surface machining surface 10. Therefore, even when a low-viscosity oil is used as the oil for lubricating the interior of the cup-shaped needle roller bearing, the bearing life can be ensured.

[0094] In addition, for this cup-shaped needle roller bearing, as Figure 5 shown, the pressing surface machining surface 10 is smoothly connected to the avoidance portion 12 via a convex arc-shaped central side R portion 13, and the end guiding surface 11 is smoothly connected to the avoidance portion 12 via a convex arc-shaped end side R portion 14. Therefore, it is possible to prevent the oil film from breaking when the needle roller 2 contacts the pressing surface machining surface 10 or the end guiding surface 11.

[0095] In addition, for this shell-shaped needle roller bearing, the distance from the radially inner end of one column end portion 8a to the radially inner end of the other column end portion 8a of a pair of column end portions 8a that are circumferentially opposed to each other with the needle rollers 2 interposed therebetween as shown is set to be 90% or more and 110% or less of the outer diameter of the needle rollers 2. Therefore, the circumferential clearance between the outer periphery of the end portion of the needle roller 2 and the end portion guide surface 11 is small, and the skew of the needle roller 2 (the inclination in the axial direction of the needle roller 2) can be effectively prevented. Figure 7 In the above-described embodiment, as the cage 3, a V-shaped cage in which the annular portion 7 and the column portion 8 are V-shaped when viewed in the circumferential direction is taken as an example for explanation. However, the present invention can also be applied to an M-shaped cage and a W-shaped cage.

[0096] In the above-described embodiment, as the cage 3, a V-shaped cage in which the annular portion 7 and the column portion 8 are V-shaped when viewed in the circumferential direction is taken as an example for explanation. However, the present invention can also be applied to an M-shaped cage and a W-shaped cage.

[0097] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the present invention is not the above description, but is shown by the scope claimed in this application, and is intended to include the meanings equivalent to the scope claimed in this application and all modifications within the scope.

Claims

1. A shell-shaped needle roller bearing having: A shell-shaped outer ring (1); A plurality of needle rollers (2) arranged at circumferentially spaced intervals along the inner circumference of the shell-shaped outer ring (1); and A cage (3) for maintaining the circumferential spacing of the plurality of needle rollers (2), The cage (3) having: a pair of annular portions (7) opposed to each other in the axial direction with the needle rollers (2) therebetween; and a plurality of column portions (8) passing between the needle rollers (2) adjacent in the circumferential direction and connecting the pair of annular portions (7), Each of the column portions (8) having: a pair of column end portions (8a) extending inward in the axial direction from the pair of annular portions (7) with a constant outer diameter (d1); a pair of column inclined portions (8b) inclined and extending such that the outer diameter gradually decreases from the pair of column end portions (8a) toward the axial inner side; and a column central portion (8c) connecting the pair of column inclined portions (8b), The shell-shaped needle roller bearing is characterized in that Pressing surface machining surfaces (10) are formed on the side surfaces on both circumferential sides of the column central portion (8c) such that the cross-sectional shape of the column central portion (8c) becomes a trapezoid whose circumferential width gradually narrows toward the radially outer side, the pressing surface machining surfaces (10) corresponding to the hypotenuse of the trapezoid, and the pressing surface machining surfaces (10) are formed as contact surfaces with the outer circumference of the needle rollers (2), Groove-shaped avoidance portions (12) are provided such that the side surfaces on both circumferential sides of the column inclined portions (8b) are recessed in the circumferential direction with respect to the pressing surface machining surfaces (10), and the avoidance portions (12) extend radially along the side surfaces on both circumferential sides of the column inclined portions (8b).

2. The shell-shaped needle roller bearing according to claim 1, wherein 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) are formed on the side surfaces on both circumferential sides of the column end portions (8a), and the end guiding surfaces (11) extend at right angles to the circumferential direction so as to intersect the pressing surface machining surfaces (10) when viewed axially and contact the outer circumference of the needle rollers (2).

3. The shell-shaped needle roller bearing according to claim 2, wherein A concave arc-shaped corner R portion (15) is formed between the end guiding surface (11) and the axially inner side surface of the annular portion (7) to connect the two in such a manner that no portion recessed in the circumferential direction with respect to the end guiding surface (11) is produced.

4. The shell-shaped needle roller bearing according to claim 2 or 3, wherein The surface roughness of the pressing surface machining surface (10) is smaller than the surface roughness of the end guiding surface (11).

5. The shell-shaped needle roller bearing according to any one of claims 2 to 4, wherein It has a convex circular arc-shaped central side R portion (13) that smoothly connects the pressed surface machining surface (10) to the avoidance portion (12) when observed radially, and a convex circular arc-shaped end side R portion (14) that smoothly connects the end guiding surface (11) to the avoidance portion (12).

6. The shell-shaped needle roller bearing according to any one of claims 2 to 5, characterized in that When observed axially, the position where the end guiding surface (11) intersects the pressed surface machining surface (10) is within a range of 90% or less of the pressed surface machining surface (10) from the radially outer end of the pressed surface machining surface (10).

7. The shell-shaped needle roller bearing according to any one of claims 1 to 6, characterized in that The distance from the radially inner end of one of the pair of column end portions (8a) that are circumferentially opposed across each needle (2) to the radially inner end of the other column end portion (8a), that is, the shortest distance connected by a straight line, is set to be 90% or more and 110% or less of the outer diameter of the needle (2).

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