Bearing element, bearing, machine device, and vehicle

Abstract

To provide a bearing element which is advantageous for reducing manufacturing cost and / or improving product quality.SOLUTION: A metal flow of a body (10) has a first pattern (PA1), a second pattern (PA2), and a third pattern (PA3). The first pattern (PA1) is continuous along a first axial surface (AS1) in the vicinity of the first axial surface (AS1). The second pattern (PA2) is continuous along a second outer peripheral surface (CS2) in the vicinity of the second outer peripheral surface (CS2). The third pattern (PA3) is continuous along a transition surface (CS3) in the vicinity of the transition surface (CS3). The metal flow of the body (10) further has a plurality of continuous lines (CL1, CL2 and CL3) which are continuous in each of the first pattern (PA1), the second pattern (PA2) and the third pattern (PA3).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a bearing element, a method for manufacturing a tubular member, a bearing, a method for manufacturing a mechanical device, a method for manufacturing a vehicle, a mechanical device, and a vehicle. This application claims priority to Japanese Patent Application No. 2023-135416, filed on August 23, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] Fig. 21 shows an inner ring 100 that constitutes a radial angular contact ball bearing. The inner ring 100 is provided with an inner ring raceway 101 having a cross-sectional shape that is approximately a quarter-circular arc at the axial middle portion of its outer circumferential surface. The inner ring 100 also has a cylindrical large diameter portion (groove shoulder portion, flange portion) 102 on its outer circumferential surface on one axial side (right side in Fig. 21), and a cylindrical small diameter portion 103 on its outer circumferential surface on the other axial side (left side in Fig. 21).

[0003] Cylindrical machine parts, such as the inner ring of an angular contact ball bearing, are made by forging metal material and then performing finishing processes such as cutting and grinding.

[0004] Patent Document 1 (JP Patent Publication 2005-288505A) describes a method for producing two pairs of inner and outer rings, each of which constitutes a tapered roller bearing, from one cylindrical metal material. The method described in Patent Document 1 includes a step of hot forging a cylindrical metal material to obtain a stepped cylindrical pre-processed material, and a step of separating the pre-processed material into two cylindrical post-processed materials having different diameters. The method described in Patent Document 1 further includes a step of cold forging and separating the post-processed material having a smaller diameter of the two post-processed materials to obtain two cylindrical members having different diameters, and then finishing these cylindrical members to obtain a set of inner and outer rings, and a step of cold forging and separating the post-processed material having a larger diameter of the two post-processed materials to obtain two cylindrical members having different diameters, and then finishing these cylindrical members to obtain another set of inner and outer rings. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-288505 A Summary of the Invention [Problem to be solved by the invention]

[0006] According to the manufacturing method described in Patent Document 1, when the axial dimensions of the inner ring and outer ring of each pair are approximately the same, the tubular member from which these inner rings and outer rings are obtained can be manufactured with a good material yield. However, the manufacturing method described in Patent Document 1 is not suitable for mass production of inner rings that are used in combination with outer rings with significantly different axial dimensions, such as the inner rings of hubs that constitute a hub unit bearing for supporting vehicle wheels on a suspension system.

[0007] An object of the present invention is to provide a production method that is advantageous in reducing production costs and / or improving product quality. [Means for solving the problem]

[0008] A method for manufacturing a bearing element according to one aspect of the present invention includes a first step of preparing an upset-machined workpiece, a second step of forming a recess, a flange, and a first axial surface in the workpiece by one or two plastic processes, and a third step of punching out the bottom of the recess in the workpiece. The recess has an axial depth relative to the first axial surface, and the flange extends radially outward. The first axial surface formed in the second step provides one end surface of the bearing element. The flange formed in the second step has a surface height at its radially outer end that is substantially the same as or greater than the first axial surface.

[0009] In one aspect of the present invention, the method for manufacturing a tubular member includes an outer peripheral surface having a cylindrical large diameter portion provided on one axial side, a cylindrical small diameter portion provided on the other axial side, and a connecting surface portion connecting the large diameter portion and the small diameter portion. The method for manufacturing a tubular member includes a swaging step of axially crushing a cylindrical raw material to obtain a disk-shaped raw material having an axial dimension smaller than that of the raw material and an outer diameter larger than that of the raw material, a forming step of subjecting the disk-shaped raw material to plastic processing to obtain an intermediate material including an intermediate tubular portion having the large diameter portion, the small diameter portion, and the connecting surface portion on its outer peripheral surface, and a partition portion closing an end opening on the other axial side of the intermediate tubular portion, and a punching step of axially punching out a radially inner portion of the intermediate tubular portion and the partition portion. The axial dimension of the intermediate material or the axial dimension of a spare intermediate material obtained during the forming step is larger than the axial dimension of the tubular member.

[0010] A mechanical device according to one aspect of the present invention includes a cylindrical mechanical component having an outer circumferential surface with a large diameter portion having a cylindrical surface on one axial side, a small diameter portion having a cylindrical surface on the other axial side, and a connecting surface portion connecting the large diameter portion and the small diameter portion. Metal flows (fiber flows, grain flows) inside the mechanical component have an inclined portion in the axial middle portion of the mechanical component that is inclined radially outward as it moves from the other axial side to the one axial side, and the metal flows are denser in the inclined portion than in a portion existing around the inclined portion.

[0011] A method for manufacturing a bearing according to one aspect of the present invention includes the steps of manufacturing a bearing element by the above-described manufacturing method, and assembling a bearing using the bearing element.

[0012] A method for manufacturing a mechanical component according to one aspect of the present invention includes a step of manufacturing a mechanical component by the above-described manufacturing method.

[0013] A method for manufacturing a mechanical device according to one aspect of the present invention includes a step of manufacturing a bearing element by the above-described manufacturing method.

[0014] A method for manufacturing a vehicle according to one aspect of the present invention includes a step of manufacturing a bearing element by the above-described manufacturing method.

[0015] A bearing according to one aspect of the present invention includes a bearing element having a trace produced by the above-described manufacturing method.

[0016] The bearing element according to one aspect of the present invention includes a main body having a cylindrical body and a flange extending outward from the cylindrical body. The main body further includes a first axial surface which is one end surface in the axial direction, a second axial surface which is another end surface in the axial direction, an inner peripheral surface of the cylindrical body, a first outer peripheral surface which is an outer peripheral surface of the cylindrical body, a second outer peripheral surface which is an outer peripheral surface of the flange, and a transition surface between the first outer peripheral surface and the second outer peripheral surface. The flange has a first angle between the first axial surface and the second outer peripheral surface, and a second angle between the transition surface and the second outer peripheral surface. The metal flow of the main body includes a first pattern which is continuous along the first axial surface in the vicinity of the first axial surface, a second pattern which is continuous along the second outer peripheral surface in the vicinity of the second outer peripheral surface, a third pattern which is continuous along the transition surface in the vicinity of the transition surface, and a plurality of continuous lines which are each continuous across the first pattern, the second pattern, and the third pattern. The third pattern has a narrower spacing between the continuous lines than the first pattern, the continuous lines have a plurality of corner elements arranged in the vicinity of the first corner, and the corner elements have sharper corners closer to the first corner. Effect of the Invention

[0017] According to an aspect of the present invention, a manufacturing method is provided that is advantageous in reducing manufacturing costs and / or improving product quality. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view of a hub unit bearing which is a mechanical device according to a first embodiment. [Diagram 2]FIG. 2 is a partial cross-sectional view of an inner ring that constitutes the hub unit bearing of the first embodiment. [Diagram 3] 3A to 3C are cross-sectional views showing the manufacturing method of the cylindrical member of the first embodiment in the order of steps. [Figure 4] Part (a) of FIG. 4 is a cross-sectional view showing the final stage of the second step in the manufacturing method for the cylindrical member of the first embodiment, and part (b) is an enlarged view of part A in part (a). [Diagram 5] Part (a) of Figure 5 is a half cross-sectional view showing the start of the second step in the manufacturing method for the cylindrical member of the first embodiment, and part (b) is a half cross-sectional view showing the end of the second step. [Figure 6] FIG. 6 is a cross-sectional view showing a final stage of the third step in the method for manufacturing the cylindrical member of the first embodiment. [Figure 7] Part (a) of Figure 7 is a half cross-sectional view showing the start of the third step in the manufacturing method for the tubular member of the first embodiment, and part (b) is a half cross-sectional view showing the end of the third step. [Figure 8] 8A to 8D are cross-sectional views showing the manufacturing method of the cylindrical member of the second embodiment in the order of steps. [Figure 9] Part (a) of Figure 9 is a half cross-sectional view showing the start of the second step in the manufacturing method for a cylindrical member of the second embodiment, and part (b) is a half cross-sectional view showing the end of the second step. [Figure 10] 10A to 10C are cross-sectional views showing the manufacturing method of the cylindrical member of the third embodiment in the order of steps. [Figure 11] FIG. 11 is a cross-sectional view showing a final stage of the second step in the manufacturing method for the cylindrical member of the third embodiment. [Figure 12] 12A to 12C are cross-sectional views showing the process steps of a method for manufacturing the cylindrical member of the fourth embodiment. [Figure 13] Part (a) of Figure 13 is a half cross-sectional view showing the start of the third step in the manufacturing method for a cylindrical member of the fourth embodiment, and part (b) is a half cross-sectional view showing the end of the third step. [Figure 14] 14A to 14C are cross-sectional views showing the process steps of a method for manufacturing the cylindrical member of the fifth embodiment. [Figure 15]FIG. 15 is a cross-sectional view showing the final stage of the second step in the method for producing a cylindrical member according to the fifth embodiment. [Figure 16] 16A to 16D are cross-sectional views showing the process steps of a method for manufacturing the cylindrical member of the sixth embodiment. [Figure 17] FIG. 17 is a partial enlarged view showing the final stage of the second step in the manufacturing method for the cylindrical member according to the sixth embodiment. [Figure 18] 18A to 18C are cross-sectional views showing the manufacturing method of the cylindrical member of the seventh embodiment in the order of steps. [Figure 19] FIG. 19 is a partial enlarged view showing the final stage of the third step in the manufacturing method for the cylindrical member of the seventh embodiment. [Figure 20] FIG. 20 is a cross-sectional view showing a method for manufacturing the cylindrical member of the eighth embodiment in the order of steps. [Figure 21] FIG. 21 is a cross-sectional view of an inner ring that constitutes a radial angular contact ball bearing. [Figure 22] FIG. 22 is a cross-sectional view showing a comparative example of a method for manufacturing a cylindrical member in the order of steps. [Figure 23] FIG. 23 is an enlarged view of the upper right portion of part (b) of FIG. [Figure 24] FIG. 24 is a partial schematic diagram of a vehicle equipped with a hub unit bearing (bearing, bearing device). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, embodiments of the present invention will be described with reference to Figures 1 to 24. The reference characters in parentheses correspond to the reference characters shown in the description of the embodiments described later.

[0020] In one embodiment, the manufacturing method of the bearing element (cylindrical member) includes a first step (initial preparation step), a second step (plastic processing step), and a third step (punching step). Additionally, the manufacturing method of the bearing element (cylindrical member) can include at least one other step in addition to the above steps. According to this manufacturing method, the forming load is kept small, and the material usage efficiency (material yield) is improved. In addition, the strength and / or quality of the product is improved.

[0021] In the first step, a workpiece (WP1) is prepared. A workpiece (WP1) having a predetermined shape that has been upset is provided, or a workpiece (WP1) having a predetermined shape is obtained by upsetting in the first step. The workpiece (WP1) prepared in the first step is used in the next step.

[0022] In one example, the workpiece (WP1) prepared in the first step has a generally cylindrical shape (generally disk shape) including a first end surface (ES1), a second end surface (ES2), and an outer circumferential surface (CS1). In one example, the first end surface (ES1) is a relatively uniform flat or curved surface. In another example, the first end surface (ES1) can have another shape. The second end surface (ES2) is the surface opposite the first end surface (ES1). In one example, the circumferential surface (CS1) of the workpiece (WP1) has a curved shape whose diameter changes along the axial direction. In one example, the outer diameter (radial width) of the workpiece (WP1) is set to be larger than the axial length (thickness, height) between the first end surface (ES1) and the second end surface (ES2). When the axial length of the workpiece (WP1) is AL1 and the outer diameter is DM1, AL1 / DM1 can be set to, for example, about 1 / 2, 1 / 3, 1 / 4, 1 / 5, 1 / 6, 1 / 7, 1 / 8, 1 / 9, or 1 / 10 or less. The above values ​​are one example, and other values ​​may be applicable in other examples. Alternatively and / or additionally, in the first step, a workpiece (WP1) having a deformed shape of the above shape or a shape other than the above shape can be prepared.

[0023] In one example, the first step of upsetting includes a pressing process (eg, cold forging) that reduces the axial length (height) and increases the outer diameter (radial width) of the blank.

[0024] In one example, the raw material (20, 20a) is compressed in the axial direction using a press device to form a workpiece (WP1) having a shape that is a deformation of a substantially cylindrical shape (substantially disc shape) or a shape different from a substantially cylindrical shape. For example, the workpiece (WP1) obtained in the first step may have a thickness change (volume change) provided in a predetermined region in the radial direction. The thickness change may include a groove having a predetermined depth and extending in the circumferential direction, and / or a protrusion having a predetermined height and extending in the circumferential direction. In one example, for the workpiece (WP1) obtained in the first step, a processing tool is designed based on, for example, the shape parameters of the final bearing element / cylindrical member and the processing parameters in other steps, and the like, and the initial shape of the workpiece (WP1) is set. Such shape control in the initial stage improves the efficiency of material use (material yield). In addition, the strength of the product is improved based on the flow form of the material.

[0025] In the second step (plastic processing step), a recess (DP1), a flange (FR1), and a first axial surface (AX1) are formed in the workpiece (WP1) by one or two plastic processes using a punching tool (e.g., hot forging). The first axial surface (AX1) is formed by plastic processing of the first end surface (ES1) of the workpiece (WP1). The workpieces (WP3, WP4) formed in the second step have a peripheral wall (CW1) surrounding the recess (DP1) and a flange (FR1) having a shape extending radially outward from the peripheral wall (CW1). The flange (FR1) is provided on the side of the peripheral wall (CW1) facing the first axial surface (AX1). In the workpieces (WP3, WP4), the peripheral wall (CW1) has a second axial surface (AX2) which is an axial end surface arranged on the opposite side of the first axial surface (AX1). In one example, the first axial surface (AX1) and / or the second axial surface (AX2) include a surface perpendicular to the axial direction. The first axial surface (AX1) formed in the second step provides one end surface of the bearing element (the cylindrical member (21, 21a)). In one example, at least a portion of the first axial surface (AX1) is formed in the flange (FR1). The recess (DP1) has an axial depth relative to the first axial surface (AX1). The flange (FR1) formed in the second step has a surface height at the radial outer end (ROE), which is a region near the radial outer end / outer edge, that is substantially the same as or greater than the first axial surface (AX1). For example, the axial surface profile of the radial outer end (ROE) has a height position that is the same or greater in the axial direction than the first axial surface (AX1) with respect to a predetermined reference plane that intersects the flange (FR1) and is perpendicular to the axial direction.

[0026] The radial extent of the radially outer end (ROE) is the radial length from the radially outer end / outer edge of the flange (FR1), and can be, for example, 10, 5.0, 4.0, 3.0, 2.0, 1.0, 0.8, 0.6, 0.4, or 0.2 mm or less. Alternatively, for example, when the outer diameter of the flange (FR1) is FD1 and the radial extent of the radially outer end (ROE) is EW1, EW1 / FD1 can be set to about 1 / 10, 1 / 12, 1 / 14, 1 / 16, 1 / 18, 1 / 20, 1 / 30, 1 / 40, or 1 / 50 or less. The above values ​​are one example, and other values ​​can be applied in another example. Alternatively and / or additionally, in the second step, a deformed shape of the above shape or a shape other than the above may be set.

[0027] In several examples shown in Figures 14-20, the second step includes simultaneously forming a recess (DP1), a flange (FR1), a first axial surface (AX1), and an annular protrusion (AP1) in the upset-machined workpiece (WP1) using a first punch (PC1). In the second step, the recess (DP1), the flange (FR1), the first axial surface (AX1), and the annular protrusion (AP1) are formed by a single punching process. The annular protrusion (AP1) has a shape that protrudes axially outward from the first axial surface (AX1) at the radial outer end (ROE) of the flange (FR1).

[0028] In one example, the first punch (PC1) has a first base portion (P11), a first protrusion portion (P12), and a first punch surface (P13) including a tip region of the first protrusion portion (P12). The first punch surface (P13) corresponds to the bottom surface of the depression (DP1). The first punch (PC1) has a second punch surface (P14) including an outer peripheral surface of the first protrusion portion (P12), and a third punch surface (P15) including an annular surface provided on the first base portion (P11). The second punch surface (P14) corresponds to the inner wall surface (inner peripheral surface) of the depression (DP1). The third punch surface (P15) corresponds to the first axial surface (AX1). The first punch (PC1) has a fourth punch surface (P16) which is a transition surface between the second punch surface (P14) and the third punch surface (P15), and a step (recess, groove) (P17) which is provided near the radial outer edge of the first punch surface (P13) and extends in the circumferential direction. The step (P17) corresponds to the annular protrusion (AP1). The first punch (PC1) is designed based on the shape parameters of the final bearing element (cylindrical member) and the processing parameters in other processes, and the shape of the workpiece (WP4) after plastic processing is set. Such shape control improves the efficiency of material use (material yield). In addition, the strength of the product is improved based on the flow form of the material.

[0029] In several examples shown in FIG. 3-13, the second step includes a first plastic processing step in which a preliminary depression (DP0) is formed on the upset workpiece (WP1) using a second punch (PC2). The second step also includes a second plastic processing step in which a depression (DP1), a flange (FR1), and a first axial surface (AX1) are simultaneously formed on the workpiece (WP2) in which the preliminary depression (DP0) is formed after the first plastic processing step using a third punch (PC3). In the second plastic processing step, the simultaneous formation of the depression (DP1), the flange (FR1), and the first axial surface (AX1) includes filling the corner of the flange (FR1) at the radial outer end (ROE). For example, in the workpiece (WP3) after the second plastic processing step, the corner (edge ​​shape) of the flange (FR1) has a substantially right-angled shape. The curved edge of the workpiece (WP2) after the first plastic processing changes to a nearly right-angled edge of the workpiece (WP3) after the second plastic processing. The second plastic processing by the third punch (PC3) causes a portion of the material of the workpiece (WP2) to flow radially outward, providing a workpiece (WP3) with an increased thickness near the radially outer end.

[0030] In one example, the second punch (PC2) has a second base (P21) and a second protrusion (P22), and the third punch (PC3) has a third base (P31) and a third protrusion (P32). A preliminary depression (DP0) is formed in the workpiece by the second protrusion (P22) of the second punch (PC2). A depression (DP1) is formed in the workpiece by the third protrusion (P32) of the third punch (PC3). The second punch (PC2) has a fifth punch surface (P25) including a tip region of the second protrusion (P22). The fifth punch surface (P25) corresponds to the bottom surface of the preliminary depression (DP0). The second punch (PC2) has a sixth punch surface (P26) including an outer peripheral surface of the second protrusion (P22). The sixth punch surface (P26) corresponds to the inner wall surface of the preliminary depression (DP0). The third punch (PC3) has a seventh punch surface (P37) including a tip region of the third protrusion (P32). The seventh punch surface (P37) corresponds to the bottom surface of the depression (DP1). The third punch (PC3) has an eighth punch surface (P38) including an outer peripheral surface of the third protrusion (P32) and a ninth punch surface (P39) including an annular surface provided on the third base portion (P31). The eighth punch surface (P38) corresponds to the inner wall surface (inner peripheral surface) of the depression (DP1). The ninth punch surface (P39) corresponds to the first axial surface (AX1). The third punch (PC3) has a tenth punch surface (P40) which is a transition surface between the eighth punch surface (P38) and the ninth punch surface (P39).

[0031] In one example, the axial length of the third protrusion (P32) of the third punch (PC3) is smaller than that of the second protrusion (P22) of the second punch (PC2). Also, the inclination (θ11) of the outer circumferential surface (sixth punch surface) (P26) of the second protrusion (P22) of the second punch (PC2) relative to the central axis is larger than the inclination (θ12) of the outer circumferential surface (P35) of the third protrusion (P32) of the third punch (PC3) relative to the central axis.

[0032] In one example, the axial length of the third protrusion (P32) of the third punch (PC3) is smaller than that of the second protrusion (P22) of the second punch (PC2). The outer diameter of the second base (P21) is substantially the same as that of the third base (P31). The average outer diameter of the second protrusion (P22) is larger than that of the third protrusion (P32).

[0033] In one example, the fifth punch face (P25) of the second punch (PC2) has a surface shape in which the surface height in the center is greater than that in other regions. The seventh punch face (P37) of the third punch (PC3) has a surface shape that is more uniform overall than the fifth punch face (P25).

[0034] Based on the shape parameters of the final bearing element (cylindrical member) and the processing parameters of other processes, the second punch (PC2) and the third punch (PC3) are designed, and the shape of the workpiece (WP3) after plastic processing is set. This shape control improves the material usage efficiency (material yield). In addition, the strength of the product is improved based on the material flow form.

[0035] In one embodiment, the tubular member (21, 21a) has an outer peripheral surface having a cylindrical large diameter portion (22) provided on one axial side, a cylindrical small diameter portion (23) provided on the other axial side, and a connecting surface portion (24) connecting the large diameter portion and the small diameter portion. A manufacturing method of the tubular member (21, 21a) includes a swaging process of axially crushing a cylindrical raw material (20, 20a) to obtain a disk-shaped material (25, 25a, 25b) having an axial dimension smaller than the axial dimension of the raw material (20, 20a) and an outer diameter larger than the outer diameter of the raw material (20, 20a), and a plastic processing of the disk-shaped material (25, 25a, 25b) to form the large diameter portion (22) and the small diameter portion (24) on the outer peripheral surface. The method includes a molding step of obtaining an intermediate material (32, 32a, 32b, 32c) including an intermediate tubular portion (30, 30a) having a small diameter portion (23) and the connection surface portion (24) and a partition wall portion (31, 31a, 31b) closing an end opening on the other axial side of the intermediate tubular portion (30, 30a), and a punching step of punching out a radially inner portion of the intermediate tubular portion (30, 30a) and the partition wall portion (31, 31a, 31b) in the axial direction. The axial dimension of the intermediate material (32, 32a, 32b, 32c) or the axial dimension of a spare intermediate material (28, 28a, 28b) obtained during the molding step is larger than the axial dimension of the tubular member (21, 21a).

[0036] In one example, the cylindrical member (21, 21a) may have an inner circumferential surface having an inclined surface portion (41) provided at one axial end portion, the inner diameter of which increases toward one axial end portion, and a cylindrical surface portion (42) provided at an axial intermediate portion and at an end portion on the other axial end portion. The intermediate cylindrical portion (30, 30a) may have the inclined surface portion (41) at one axial end portion of the inner circumferential surface.

[0037] In one example, the forming process can include a pre-forming process in which the disk-shaped material (25, 25a, 25b) is subjected to plastic processing to obtain the preliminary intermediate material (28, 28a, 28b) having a preliminary intermediate cylindrical portion (26, 26a, 26b) and a partition portion (31, 31a, 31b) that closes the end opening on the other axial side of the preliminary intermediate cylindrical portion (26, 26a, 26b), and a post-forming process in which the preliminary intermediate material (28, 28a, 28b) is crushed in the axial direction inside the inner surface of a die having a shape that fits along the outer circumferential surface of the intermediate material (32, 32a, 32b, 32c) to obtain the intermediate material (32, 32a, 32b, 32c). For example, the axial dimension of the preliminary intermediate material (28, 28a, 28b) is larger than the axial dimension of the tubular member (21, 21a), and the axial dimension of the intermediate material (32, 32a, 32b, 32c) is equal to the axial dimension of the tubular member (21, 21a).

[0038] In one example, in the pre-forming step, at least a radially outer portion of an end face on one axial side of the preliminary intermediate cylindrical portion (26, 26a, 26b) can be prevented from contacting a forming die for performing plastic working.

[0039] For example, the outer diameter of one axial side portion of the spare intermediate cylindrical portion (26, 26a, 26b) is slightly smaller than the outer diameter of the large diameter portion (22), and the outer diameter of the other axial side portion of the spare intermediate cylindrical portion (26, 26a, 26b) is slightly smaller than the outer diameter of the small diameter portion (23).

[0040] In one example, the intermediate cylindrical portion (30, 30a) has an annular convex portion (36, 36a, 36b) protruding in one axial direction at a radially outer end portion of an end face on one axial direction side. For example, the forming step is a step of obtaining the intermediate material (32, 32a, 32b, 32c) by performing plastic processing on the disk-shaped material (25, 25a, 25b), and the axial dimension of the intermediate material (32, 32a, 32b, 32c) is larger than the axial dimension of the cylindrical member (21, 21a) by the axial height of the annular convex portion (36, 36a, 36b), and includes a removing step of removing the annular convex portion (36, 36a, 36b) after the forming step.

[0041] For example, in the forming step, it is possible to prevent one axial end face of the annular protrusion (36, 36a, 36b) from coming into contact with a forming die for carrying out plastic working.

[0042] In one example, before the removing step, a uniformizing step can be provided in which the annular convex portion (36, 36a, 36b) formed in the molding step is crushed in the axial direction to make the axial height of the annular convex portion (36, 36a, 36b) uniform around the entire circumference.

[0043] In one embodiment, the mechanical device includes a tubular mechanical component (10) having an outer circumferential surface with a cylindrical large diameter portion (18) provided on one axial side, a cylindrical small diameter portion (19) provided on the other axial side, and a connecting surface portion (7a) connecting the large diameter portion (18) and the small diameter portion (19). The manufacturing method for the mechanical device includes a step of manufacturing the mechanical component (10) by performing a finishing process on a tubular member (21, 21a) manufactured by the above-mentioned manufacturing method for a tubular member.

[0044] In one example, the mechanical component is an inner ring (10), the connection surface portion of the mechanical component is formed by an inner ring raceway (7a) having an arc-shaped cross-sectional shape, and the mechanical device is a bearing device (1).

[0045] For example, the bearing device is a hub unit bearing (1) for supporting an automobile wheel rotatably relative to a suspension device.

[0046] In one embodiment, the vehicle includes a mechanical device 1. A method for manufacturing a vehicle includes a step of manufacturing the mechanical device 1 by the above-described method for manufacturing a mechanical device.

[0047] In one embodiment, the machine device (1) includes a cylindrical machine component (10) having an outer circumferential surface with a cylindrical large diameter portion (18) provided on one axial side, a cylindrical small diameter portion (19) provided on the other axial side, and a connecting surface portion (7a) connecting the large diameter portion and the small diameter portion. The metal flow (fiber flow, grain flow) inside the machine component has an inclined portion (Tp) in the axial middle portion of the machine component that is inclined radially outward as it moves from the other axial side to the one axial side, and the metal flow is denser in the inclined portion (Tp) than in a portion around the inclined portion (Tp).

[0048] In one example, the mechanical component is an inner ring (10), the connection surface portion of the mechanical component is formed by an inner ring raceway (7a) having an arc-shaped cross-sectional shape, and the mechanical device is a bearing device (1).

[0049] For example, the bearing device is a hub unit bearing (1) for supporting an automobile wheel rotatably relative to a suspension device.

[0050] In one embodiment, the vehicle includes the mechanical device described above.

[0051] According to the above-mentioned manufacturing method for a tubular member, it is possible to reduce the manufacturing costs of mechanical components made from a tubular member having an outer peripheral surface with a cylindrical large diameter portion provided on one axial side portion, a cylindrical small diameter portion provided on the other axial side portion, and a connecting surface portion connecting the large diameter portion and the small diameter portion.

[0052] In one embodiment, as shown in the examples of Figures 2, 7, and 15, the bearing element includes a body (10) having a tubular body (TBB) and a flange (FRG) extending outward from the tubular body (TBB). The body (10) has a first axial surface (AS1) which is one end surface in the axial direction, and a second axial surface (AS2) which is another end surface in the axial direction. The body (10) also has an inner peripheral surface (IS1) of the tubular body (TBB), a first outer peripheral surface (CS1) which is the outer peripheral surface of the tubular body (TBB), a second outer peripheral surface (CS2) which is the outer peripheral surface of the flange (FRG), and a transition surface (CS3) between the first outer peripheral surface (CS1) and the second outer peripheral surface (CS2). The flange (FRG) has a first angle (FE1) between the first axial surface (AS1) and the second outer peripheral surface (CS2) and a second angle (FE2) between the transition surface (CS3) and the second outer peripheral surface (CS2).

[0053] In one embodiment, the bearing element (tubular member) has a trace of the manufacturing method described above. In one example, the trace is metal flow (metal fiber flow, fibrous metal structure, grain flow) observed in a cross section of the bearing element (tubular member). Figures 2, 5, 7, 9, and 15 show an example of metal flow in an axial cross section (axial cross section) of the bearing element (tubular member) and its manufacturing process. The trace can also be confirmed based on a texture analysis and / or a structure analysis that is different from an analysis based on metal flow.

[0054] In one example, the metal flow pattern of the main body (10) has a first pattern (PA1), a second pattern (PA2), and a third pattern (PA3). The first pattern (PA1) is continuous along the first axial surface (AS1) in the vicinity of the first axial surface (AS1). The second pattern (PA2) is continuous along the second outer peripheral surface (CS2) in the vicinity of the second outer peripheral surface (CS2). The third pattern (PA3) is continuous along the transition surface (CS3) in the vicinity of the transition surface (CS3). The metal flow pattern of the main body (10) further has a plurality of continuous lines (CL1, CL2, CL3) each of which is continuous across the first pattern (PA1), the second pattern (PA2), and the third pattern (PA3).

[0055] As shown in the examples of Figures 2, 7, and 15, the intervals between the multiple continuous lines (CL1, CL2, CL3) in the third pattern (PA3) are narrower than the intervals between the multiple continuous lines (CL1, CL2, CL3) in the first pattern (PA1). The multiple continuous lines (CL1, CL2, CL3) have multiple corner elements (CE1, CE2, CE3) arranged in the vicinity of the first corner (FE1). The multiple corner elements (CE1, CE2, CE3) have sharper corners as they are closer to the first corner (FE1). The corner element (CE1) is closest to the first corner (FE1). The corner element (CE3) is farther from the first corner (FE1) than the corner element (CE1) and the corner element (CE2). The corner element (CE1) has a sharper corner than the corner element (CE2). The corner element (CE2) has a sharper corner than the corner element (CE3).

[0056] As shown in the examples of Figures 7 and 15, at least one of the multiple corner elements (CE1, CE2, CE3) has a protruding shape protruding toward the first corner (FE1). At least one of the multiple corner elements (CE1, CE2, CE3) has a first curve (CV1) that is convex toward the first corner (FE1) and a second curve (CV2) that is convex toward the inside of the first corner (FE1). For example, the first curve (CV1) and the second curve (CV2) are arranged continuously.

[0057] As shown in the example of FIG. 2, the metal flow of the main body (10) has a fourth pattern (PA4) including a plurality of line elements extending in a direction oblique to the central axis of the main body (10) from the inner circumferential surface (IS1) toward the transition surface (CS3). In the fourth pattern (PA4), the spacing between the plurality of line elements in the radially outer region is narrower than the spacing between the plurality of line elements in the radially inner region. In the fourth pattern (PA4), the plurality of line elements in the radially outer region have a partial curvature (CV3) that is convex toward the radially inner side.

[0058] A bearing element having a predetermined metal flow is advantageous for reducing manufacturing costs and / or improving strength, whereas a continuous line element of metal flow is advantageous for increasing the strength of the body.

[0059] In one embodiment, the bearing comprises the above-mentioned bearing elements, which is advantageous for reducing the cost of the bearing.

[0060] In one embodiment, a machine is provided with the above-mentioned bearing, which is advantageous for reducing the cost of the machine.

[0061] In one embodiment, a vehicle includes the above-mentioned bearing, which is advantageous for reducing the cost of the vehicle.

[0062] FIG. 24 is a partial schematic diagram of a vehicle 200 equipped with a hub unit bearing (bearing, bearing device) 151. The above-mentioned bearing can be applied to both a hub unit bearing for a driving wheel and a hub unit bearing for a driven wheel. In FIG. 24, the hub unit bearing 151 is for a driving wheel and includes an outer ring 152, a hub 153, and a plurality of rolling elements 156. The outer ring 152 is fixed to a knuckle 201 of a suspension device using bolts or the like. The wheel (and braking rotor) 202 is fixed to a flange (rotating flange) 153A provided on the hub 153 using bolts or the like. The vehicle 200 can have a support structure similar to that described above for the hub unit bearing 151 for the driven wheel.

[0063] 22(a) to (c) show, as a comparative example, a method for manufacturing a tubular member (bearing element) 104 for obtaining one inner ring 100 (see FIG. 21) from a cylindrical metal material by hot forging.

[0064] The manufacturing method of the tubular member 104 includes a swaging step, a forming step, and a punching step, each of which is a hot forging step.

[0065] In the swaging process, a cylindrical raw material, which is a single metal material, is crushed in the axial direction to obtain a disk-shaped raw material (workpiece) 105, as shown in Figure 22(a), which has a smaller axial dimension and a larger outer diameter than the raw material.

[0066] In the forming step, the disk-shaped material 105 is subjected to plastic processing such as forward and backward extrusion processing to obtain a cup-shaped intermediate material 106 as shown in Fig. 22(b). The intermediate material 106 includes an intermediate tubular portion 107 having the same outer peripheral surface shape as that of the tubular member 104 and the same axial dimension as that of the tubular member 104, and a partition portion 108 that closes the end opening on the other axial side of the end portion on one axial side (upper side in Fig. 22(b)) and the other axial side (lower side in Fig. 22(b)) of the intermediate tubular portion 107.

[0067] In the punching step, the radially inner portion of the intermediate tubular portion 107 and the partition wall portion 108 of the intermediate material 106 are punched out in the axial direction to obtain the tubular member 104 .

[0068] Although such a manufacturing method can efficiently obtain the tubular member 104 from a cylindrical metal material with few steps, there is room for improvement in the following respects.

[0069] That is, because the tubular member 104 is produced by hot forging, an oxide film (black skin) is formed on its surface. If such an oxide film remains on the surface of the completed inner ring 100, it becomes difficult to ensure the shape precision and surface roughness precision required of the inner ring 100. For this reason, it is necessary to ensure in the tubular member 104 a machining allowance sufficient to remove the oxide film on the surface in finish processing.

[0070] However, when the intermediate material 106 is obtained by performing forward and backward extrusion processing on the disk-shaped material 105, in the molding space of the intermediate material 106 existing inside the molding die, the material (metal material) flowing toward one axial side may not reach the final point, that is, the radially outer end of the end on one axial side.

[0071] In this case, the radially outer end portion of the end face on one axial side of the intermediate material 106 and the tubular member 104 will have a recessed shape, for example, as shown by the dotted line α in Figure 23 (in the illustrated example, the shape is recessed in the direction toward the other axial side as it moves radially outward).

[0072] As a result, there is a possibility that a disadvantage will occur in that it will be impossible to secure a machining allowance sufficient to remove the oxide film by finish processing at the radially outer end of the end face on one axial side of the cylindrical member 104. A cylindrical member in which such a disadvantage occurs will be discarded, which will cause the manufacturing costs of the inner ring 100 to increase.

[0073] One method for preventing the above-mentioned inconveniences from occurring is to increase the processing load when performing forward and backward extrusion processing on the disk-shaped material 105, thereby ensuring that the material reaches the radially outer end of one axial end of the molding space of the intermediate material 106.

[0074] However, this method imposes a large load on the molding die, requires a large processing device, and shortens the life of the molding die, resulting in increased manufacturing costs for the inner ring 100.

[0075] As another method for eliminating the above-mentioned inconvenience, a method can be considered in which the volume of the raw material is increased and the thickness of the machining allowance provided in the tubular member 104 is increased overall. According to this method, even if the radially outer end portion of the end face on one axial side of the tubular member 104 has an undercut shape as shown by the dashed line α in Fig. 23, it becomes easy to ensure a machining allowance sufficient to remove the oxide film by finish processing at the radially outer end portion of the end face on one axial side of the tubular member 104.

[0076] However, with this method, the amount of machining allowance removed in the finish processing is large, that is, the yield rate when manufacturing the inner ring 100 is reduced, and the manufacturing cost of the inner ring 100 increases.

[0077] In the following, examples will be described. In each example, it is possible to reduce the manufacturing cost of a mechanical component made from a tubular member having an outer circumferential surface with a cylindrical large diameter portion provided on one axial side, a cylindrical small diameter portion provided on the other axial side, and a connecting surface portion connecting the large diameter portion and the small diameter portion.

[0078] [First Example] The first embodiment will be described with reference to FIGS.

[0079] This example is an example of manufacturing a cylindrical member (bearing element) for obtaining the inner ring 10 of the hub unit bearing 1 shown in FIG.

[0080] The manufacturing method of the tubular member can be applied to any tubular member having an outer circumferential surface with a cylindrical large diameter portion provided on one axial side, a cylindrical small diameter portion provided on the other axial side, and a connecting surface portion connecting the large diameter portion and the small diameter portion. For example, the manufacturing method of the tubular member can be applied to a bearing device having a structure different from that shown in FIG. 1, specifically, a tubular member (bearing element) for obtaining an inner ring or a plain bearing constituting a single-row or double-row angular ball bearing. In this case, the inner ring or the plain bearing can be manufactured by subjecting the tubular member (bearing element) to finishing processes such as cutting and grinding.

[0081] The method for manufacturing a tubular member can also be used to manufacture tubular members for obtaining various mechanical parts that constitute mechanical devices such as machine tools and vehicles. In this case, the mechanical parts can be manufactured by subjecting the tubular member to finishing processes such as cutting and grinding.

[0082] The material of the tubular member is not particularly limited as long as it is a metal material that can be subjected to hot forging, and various metal materials such as iron alloys such as bearing steel, aluminum alloys, copper alloys, etc. can be used.

[0083] With regard to the hub unit bearing 1, the axially inner side is the right side in FIG. 1, which is the center side in the width direction of the vehicle when assembled to the vehicle, and the axially outer side is the left side in FIG. 1, which is the outer side in the width direction of the vehicle when assembled to the vehicle.

[0084] The hub unit bearing 1 of this example includes an outer ring 2, a hub 3, and a plurality of rolling elements 4a, 4b.

[0085] The outer ring 2 is made of a hard metal such as medium carbon steel, and has double-row outer ring raceways 5a, 5b on its inner circumferential surface. In this example, each of the outer ring raceways 5a, 5b is an angular type having a cross-sectional shape of approximately a quarter circle arc.

[0086] Furthermore, the outer ring 2 has a stationary flange 6 protruding radially outward from an axially intermediate portion. The stationary flange 6 is a portion used for supporting and fixing the outer ring 2 to a knuckle of a suspension device.

[0087] The hub 3 has double row inner ring raceways 7a, 7b on the outer circumferential surface thereof. In this example, each of the inner ring raceways 7a, 7b is an angular type having a cross-sectional shape of a substantially quarter-circular arc.

[0088] Furthermore, the hub 3 has a rotating flange 8 that protrudes radially outward from a portion located axially outward from the outer ring 2. The rotating flange 8 is a portion that connects and fixes the wheel and the braking rotor that constitute the wheel.

[0089] In this example, the hub 3 is formed by combining a hub ring 9 and an inner ring 10 .

[0090] The hub ring 9 is made of a hard metal such as medium carbon steel. The inner ring raceway 7b on the axially outer side is provided on the outer peripheral surface of the axially middle part of the hub ring 9. The rotating flange 8 is provided on the axially outer part of the hub ring 9. The hub ring 9 has a small diameter step 11 at its axially inner end, which has an outer diameter smaller than a part adjacent to the axially outer side and onto which the inner ring 10 is fitted, and also has a step surface 12 facing the axially inner side at its axially outer end. Since the hub unit bearing 1 of this example is for a drive wheel, the hub ring 9 has a spline hole 13 at its radial center for spline engagement with a spline shaft part constituting a drive shaft member.

[0091] The inner ring 10 is made of hard metal such as bearing steel and has a generally cylindrical shape. The inner ring raceway 7a on the inside in the axial direction is provided on the outer circumferential surface of the inner ring 10 at a middle portion in the axial direction.

[0092] Specifically, the outer peripheral surface of the inner ring 10 is configured by connecting a cylindrical large diameter portion 18 provided on the axially inner portion, which is one axial side portion, and a cylindrical small diameter portion 19 provided on the axially outer portion, which is the other axial side portion, by an inner ring raceway 7a on the axially inner side, which is the connecting surface portion.

[0093] In this example, the inner peripheral surface of the inner ring 10 has an inclined surface portion 39 provided at an axially inner end portion on one axial side, the inner diameter of which increases toward the axially inner side, and a cylindrical surface portion 40 provided at an axially intermediate portion and an axially outer end portion on the other axial side. In this example, the inclined surface portion 39 has a cross-sectional shape that is approximately a quarter circle arc. In one example, the inclined surface portion can be formed of a conical surface having a linear generatrix shape.

[0094] In this example, both axial end faces of the inner ring 10 are formed of flat surfaces perpendicular to the axial direction.

[0095] The entire surface of the inner ring 10 is configured as a finished surface that has been subjected to finishing processes such as cutting and grinding.

[0096] The hub 3 has an inner ring 10 fitted and fixed onto a small diameter step 11 of the hub wheel 9 , and an axially outer end face of the inner ring 10 abutting against a step surface 12 of the hub wheel 9 .

[0097] The hub unit bearing can also be applied to a hub unit bearing that has a crimping portion at the axially inner end of the hub wheel that presses down on the axially inner surface of the inner ring, a hub unit bearing in which the axially outer inner ring raceway is provided on the outer peripheral surface of another inner ring that is fitted onto the hub wheel, and a hub unit bearing for a driven wheel that does not have a spline hole in the radial center.

[0098] The rolling elements 4a, 4b are made of iron alloys such as bearing steel or ceramics, and a plurality of rolling elements 4a, 4b are arranged between the double row outer ring raceways 5a, 5b and the double row inner ring raceways 7a, 7b. In this example, the rolling elements 4a, 4b are made of balls, and a back-to-back contact angle and preload are applied to the rolling elements 4a, 4b in each row.

[0099] In this example, the pitch circle diameter of the rolling elements 4a in the axially outer row is the same as the pitch circle diameter of the rolling elements 4b in the axially inner row. However, the hub unit bearing can also be applied to a different diameter PCD type hub unit bearing in which the pitch circle diameter of the rolling elements in the axially inner row is different from the pitch circle diameter of the rolling elements in the axially outer row.

[0100] In the hub unit bearing 1 of this example, the openings on both axial sides of the rolling element installation space 14 that exist between the inner circumferential surface of the outer ring 2 and the outer circumferential surface of the hub 3 are closed by sealing devices 15a, 15b, respectively. This prevents foreign matter such as muddy water from entering the rolling element installation space 14 from the outside through the openings on both axial sides of the rolling element installation space 14 and prevents the lubricating grease sealed in the rolling element installation space 14 from leaking to the outside.

[0101] In the illustrated example, the axially inner seal device 15a comprises a seal ring 16 fitted onto the inner peripheral surface of the axially inner end of the outer ring 2, and a slinger 17 fitted onto the large diameter portion 18 of the inner ring 10, and is configured as a combined seal ring in which the tips of multiple seal lips constituting the seal ring 16 are in sliding contact with the surface of the slinger 17. In other words, the large diameter portion 18 of the inner ring 10 is used as a fitting portion for fitting the slinger 17 onto the outside.

[0102] Next, a method for manufacturing the inner ring (bearing element) 10 in this example will be described with reference to FIGS.

[0103] In the following description of this example, unless otherwise specified, the axial direction refers to the axial direction of the workpiece, one axial side being the upper side in Figs. 3 to 7, and the other axial side being the lower side in Figs. 3 to 7. In Figs. 3 to 7, the axial direction of each illustrated member coincides with the up-down direction. However, the up-down direction in Figs. 3 to 7 does not necessarily coincide with the up-down direction (vertical direction) during processing. In other words, the up-down direction in Figs. 3 to 7 may coincide with the horizontal direction, or may coincide with a direction inclined relative to both the up-down direction (vertical direction) and the horizontal direction.

[0104] The manufacturing method of the inner ring 10 in this example is one embodiment of a manufacturing method and includes a main step of subjecting a cylindrical raw material 20 as shown in FIG. 3(a) to multiple stages of plastic processing to obtain a tubular member 21 as shown in FIG. 3(d), and a finishing step of subjecting the tubular member 21 to finishing processes such as cutting and grinding to obtain the final shape of the inner ring 10.

[0105] The plastic processing in this step is hot forging. Therefore, an oxide film (black skin) is formed on the surface of the tubular member 21 after this step. If such an oxide film remains on the surface of the completed inner ring 10, it becomes difficult to ensure the shape precision and surface roughness precision required of the inner ring 10. For this reason, as shown by the two-dot chain line in FIG. 2, it is necessary to ensure in the tubular member 21 a machining allowance that will be removed in the finishing step. Therefore, the tubular member 21 has a tubular shape with an overall contour that is larger than that of the inner ring 10 by the amount of the machining allowance.

[0106] That is, the outer peripheral surface of the tubular member 21 has a large diameter portion 22 having a cylindrical surface shape provided on one axial side, a small diameter portion 23 having a cylindrical surface shape provided on the other axial side, and a connecting surface portion (transition portion) 24 connecting the large diameter portion 22 and the small diameter portion 23. The large diameter portion 22 has an outer diameter larger than that of the large diameter portion 18 of the inner ring 10 by the amount of the machining allowance. The small diameter portion 23 has an outer diameter larger than that of the small diameter portion 19 of the inner ring 10 by the amount of the machining allowance. The connecting surface portion 24 has a cross-sectional shape of an approximately quarter circular arc, and an outer diameter larger than that of the inner ring raceway 7a of the inner ring 10 by the amount of the machining allowance.

[0107] The inner peripheral surface of the cylindrical member 21 has an inclined surface portion (curved surface portion) 41 provided at one end in the axial direction, the inner diameter of which increases toward the inside in the axial direction, and a cylindrical surface portion 42 provided at an intermediate portion in the axial direction and at the end on the other axial direction. The inclined surface portion 41 has an arc-shaped cross section like the inclined surface portion 39 of the inner ring 10, and has an inner diameter smaller than that of the inclined surface portion 39 by the amount of the machining allowance. The cylindrical surface portion 42 has an inner diameter smaller than that of the cylindrical surface portion 40 of the inner ring 10 by the amount of the machining allowance.

[0108] Both axial end faces of the cylindrical member 21 are formed of flat surfaces perpendicular to the axial direction. The end face on one axial side of the cylindrical member 21 is located on one axial side of the end face on one axial side of the inner ring 10 by the aforementioned machining allowance, and the end face on the other axial side of the cylindrical member 21 is located on the other axial side of the end face on the other axial side of the inner ring 10 by the aforementioned machining allowance.

[0109] The thickness of the removal allowance is not particularly limited, but must be at least thick enough to remove the oxide film, i.e., must be greater than or equal to the thickness of the oxide film. Assuming that the oxide film has a thickness of 0.2 mm to 0.3 mm, the thickness of the removal allowance can be, for example, 0.3 mm to 1.0 mm, and preferably 0.3 mm to 0.5 mm. The above values ​​are merely examples and are not intended to be limiting.

[0110] The process includes a swaging step, a forming step, and a punching step.

[0111] In the swaging process, the cylindrical raw material 20 is crushed in the axial direction to obtain a disk-shaped raw material 25 having an axial dimension smaller than the axial dimension of the raw material 20 and an outer diameter larger than the outer diameter of the raw material 20, as shown in Figure 3(a).

[0112] In this example, the raw material 20 is obtained by cutting a long metal bar to a predetermined length.

[0113] The outer circumferential surface of the disc-shaped material 25 has a substantially arc-shaped cross-sectional shape (generatrix shape) in which the outer diameter of the axial center portion is larger than the outer diameter of both axial end portions. In this example, the outer diameter of the disc-shaped material 25, more specifically, the outer diameter of the axial center portion which is the maximum diameter portion of the disc-shaped material 25, is the same as or approximately the same as the outer diameter of the small diameter portion 23 of the tubular member 21. The outer diameter of both axial end portions which are the minimum diameter portions of the disc-shaped material 25 is slightly smaller than the outer diameter of the small diameter portion 23 of the tubular member 21.

[0114] In the forming process, the disk-shaped material 25 is subjected to plastic processing to obtain an intermediate material 32 including an intermediate tubular portion 30 having a large diameter portion 22, a small diameter portion 23, and a connecting surface portion 24 on its outer surface, and a partition portion 31 that closes the end opening on the other axial side of the intermediate tubular portion 30.

[0115] In this example, the molding process includes a pre-molding process and a post-molding process.

[0116] In the pre-forming step, the disk-shaped material 25 is subjected to a backward extrusion process, which is a plastic processing process, to obtain a cup-shaped preliminary intermediate material 28, as shown in FIG. 3(b), which includes a preliminary intermediate tubular portion 26 having an axial dimension larger than the axial dimension of the tubular member 21, and a partition portion 27 that closes the end opening on the other axial side of the preliminary intermediate tubular portion 26.

[0117] As long as the axial dimension of the auxiliary intermediate tubular portion is larger than the axial dimension of the tubular member and the partition portion closes the end opening on the other axial side of the auxiliary intermediate tubular portion, the shapes of the auxiliary intermediate tubular portion and the partition portion are not particularly limited.

[0118] In this example, in the pre-forming step, the outer diameter of one axial side portion of the preliminary intermediate tubular portion 26 is made slightly smaller than the outer diameter of the large diameter portion 22 of the tubular member 21, and the outer diameter of the other axial side portion of the preliminary intermediate tubular portion 26 is made slightly smaller than the outer diameter of the small diameter portion 23 of the tubular member 21. More specifically, the outer diameter of one axial side portion of the preliminary intermediate tubular portion 26 is made slightly smaller than the inner diameter of the large diameter portion 35a1 of the die 35a used in the post-forming step (see FIG. 7(a)) (= the outer diameter of the large diameter portion 22 of the tubular member 21) by an insertion clearance into the large diameter portion 35a1. In addition, the outer diameter of the other axial side portion of the preliminary intermediate cylindrical portion 26 is made slightly smaller than the inner diameter of the small diameter portion 35a2 (= the outer diameter of the small diameter portion 23 of the tubular member 21) of the die 35a used in the post-forming process (see Figure 7 (a)) by the amount of insertion clearance into the small diameter portion 35a2.

[0119] In this example, the outer circumferential surface of the preliminary intermediate tubular portion 26 includes a cylindrical large diameter portion 22a provided on one axial side, a cylindrical small diameter portion 23a provided on the other axial side, and a connection surface portion (transition portion) 24a that connects the large diameter portion 22a and the small diameter portion 23a and has a cross-sectional shape of a substantially quarter-circular arc. The large diameter portion 22a has an outer diameter slightly smaller than the outer diameter of the large diameter portion 22 of the tubular member 21 by an insertion clearance into the large diameter portion 35a1 of the die 35a, and has an axial dimension larger than the axial dimension of the large diameter portion 22 of the tubular member 21. The small diameter portion 23a has an outer diameter slightly smaller than the outer diameter of the small diameter portion 23 of the tubular member 21 by an insertion clearance into the small diameter portion 35a2 of the die 35a, and has an axial dimension smaller than the axial dimension of the small diameter portion 23 of the tubular member 21. The connection surface portion 24 a has a radius of curvature larger than the radius of curvature of the connection surface portion 24 of the tubular member 21 .

[0120] In this example, the inner peripheral surface of the spare intermediate cylindrical portion 26 is configured as a substantially conical cylindrical surface whose inner diameter becomes larger from the other axial side toward the one axial side.

[0121] The end face on one axial direction side of the spare intermediate cylindrical portion 26 has a cross-sectional shape that is generally arc-shaped and convex toward one axial direction side. That is, the radially inner portion of the end face on one axial direction side of the spare intermediate cylindrical portion 26 is configured with a convex curved surface that is inclined toward the other axial direction side as it approaches the radially inner side, and the radially outer portion of the end face on one axial direction side of the spare intermediate cylindrical portion 26 is configured with a convex curved surface that is inclined toward the other axial direction side as it approaches the radially outer side.

[0122] In this example, the opening width (inner diameter) of the end portion on one axial side of the spare intermediate cylindrical portion 26 is larger than the opening width (inner diameter) of the end portion on one axial side of the cylindrical member 21 .

[0123] In this embodiment, one axial side surface of the partition wall portion 27 is configured as a substantially conical surface that is inclined toward the other axial side as it extends radially inward.

[0124] In this example, the end face on the other axial side of the spare intermediate material 28, which is formed by the end face on the other axial side of the spare intermediate cylindrical portion 26 and the side surface on the other axial side of the partition wall portion 27, is formed by a single flat surface perpendicular to the axial direction.

[0125] Additionally and / or alternatively, a recess that is recessed in the axial direction can be provided in the radial center of the end face on the other axial side of the preliminary intermediate material. Providing such a recess can facilitate the operation of removing the end face on the other axial side of the preliminary intermediate material from the molding die after molding of the preliminary intermediate material.

[0126] In this process, the material constituting the partition wall portion 27 is finally punched out and does not remain in the tubular member 21. For this reason, in this example, the axial thickness of the partition wall portion 27 is made as small as possible, specifically, it is made smaller than the radial thickness of the preliminary intermediate tubular portion 26. This improves the yield.

[0127] The pre-forming step is performed using a press working device 29 as shown in Figures 4 and 5. The press working device 29 includes a die 29a, a die pin 29b, and a punch 29c, each of which is a forming die.

[0128] The die 29a has an inner peripheral surface having a shape that conforms to the outer peripheral surface of the preliminary intermediate material 28 to be obtained, i.e., the outer peripheral surface of the preliminary intermediate tubular portion 26. Specifically, the inner peripheral surface of the die 29a has a stepped cylindrical shape in which a large diameter portion 29a1 provided on one axial side and a small diameter portion 29a2 provided on the other axial side are connected by a curved surface portion 29a3. The large diameter portion 29a1 has a shape that conforms to the large diameter portion 22a of the preliminary intermediate tubular portion 26, the small diameter portion 29a2 has a shape that conforms to the small diameter portion 23a of the preliminary intermediate tubular portion 26, and the curved surface portion 29a3 has a shape that conforms to the connecting surface portion 24a of the preliminary intermediate tubular portion 26.

[0129] The die pin 29b is disposed on the inner diameter side of the small diameter portion 29a2 of the die 29a without any rattling in the radial direction. The tip end face of the die pin 29b on one axial side has a shape conforming to the end face of the spare intermediate material 28 on the other axial side.

[0130] The punch 29c is supported on a support table (not shown) of the press working device 29 so as to be movable in the axial direction.

[0131] The punch 29c has a protrusion (projection) 29c1 at the center of a tip end surface (end surface on the other axial direction). The outer circumferential surface of the protrusion 29c1 has a shape that conforms to a radially inner portion of the end surface on one axial direction side of the spare intermediate cylindrical portion 26 and a portion of the inner circumferential surface of the spare intermediate cylindrical portion 26 that is located on one axial direction side of the partition wall portion 27. The end surface on the other axial direction, which is the tip end surface of the protrusion 29c1, has a shape that conforms to a side surface of the partition wall portion 27 on one axial direction side.

[0132] Furthermore, punch 29c has an annular surface portion 29c2 bent radially outward from one axial end of the outer circumferential surface of protrusion 29c1. In this example, annular surface portion 29c2 is formed of a flat surface perpendicular to the central axis of punch 29c.

[0133] When the press processing device 29 is used to perform rearward extrusion processing on the disk-shaped material 25 to obtain the preliminary intermediate material 28, first, as shown in Figure 5 (a), the disk-shaped material 25 is placed on one axial end face of the die pin 29b.

[0134] Next, the punch 29c is moved to the other axial side, and the end face of the protruding portion 29c1 of the punch 29c on the other axial side presses the radial center of the disk-shaped material 25. As a result, as shown in Figures 5(a) to 5(b) and 4(a), the central portion of the disk-shaped material 25 is crushed in the axial direction between the end face of the protruding portion 29c1 on the other axial side and the end face of the die pin 29b on one axial side, while the material of the radial outer portion of the disk-shaped material 25 is moved to the portion between the outer circumferential surface of the protruding portion 29c1 and the inner circumferential surface of the die 29a, and a preliminary intermediate material 28 is obtained.

[0135] In this embodiment, in the pre-forming step, at least a radial portion of one axial end face of the preliminary intermediate tubular portion 26 is prevented from contacting the molding die for performing the rearward extrusion process.

[0136] More specifically, in this example, as shown in Fig. 4(b), the radially outer portion of the end face on one axial side of the preliminary intermediate tubular portion 26 is not brought into contact with the annular surface portion 29c2 of the punch 29c. Therefore, in this example, the processing load in the pre-forming step can be reduced compared to a case in which the entire end face on one axial side of the preliminary intermediate tubular portion 26 is brought into contact with a molding die for performing the rearward extrusion process. As a result, the durability of the die 29a, the die pin 29b, and the punch 29c can be ensured, and the manufacturing cost of the inner ring 10 can be reduced.

[0137] In the preforming step, the entire end face on one axial side of the preliminary intermediate cylindrical portion may be in contact with the molding die or may not be in contact with the molding die.

[0138] In the pre-forming process, as shown in FIG. 6, the preliminary intermediate material 28 is crushed in the axial direction inside the inner surface of a die 35a having a shape that fits the outer circumferential surface of the intermediate material 32, to obtain a cup-shaped intermediate material 32 having an axial dimension equal to the axial dimension of the tubular member 21, as shown in FIG. 3(c).

[0139] The intermediate material 32 includes a cylindrical intermediate portion 30 and a partition wall portion 31 that closes an end opening on the other axial side of the cylindrical intermediate portion 30 .

[0140] The intermediate tubular portion 30 has an axial dimension equal to the axial dimension of the tubular member 21. The intermediate tubular portion 30 has an outer circumferential surface shape equal to the outer circumferential surface shape of the tubular member 21. That is, the outer circumferential surface of the intermediate tubular portion 30 has, in order from one axial side, a large diameter portion 22, a connection surface portion 24, and a small diameter portion 23.

[0141] The end faces on both axial sides of the intermediate tubular portion 30 have the same shape as the end faces on both axial sides of the tubular member 21, that is, have a flat surface shape perpendicular to the axial direction.

[0142] An end portion on one axial direction of the inner peripheral surface of the intermediate tubular portion 30 has the same shape as an end portion on one axial direction of the inner peripheral surface of the tubular member 21. That is, the inner peripheral surface of the intermediate tubular portion 30 has an inclined surface portion 41 at an end portion on one axial direction. A portion of the inner peripheral surface of the intermediate tubular portion 30 located between the partition wall portion 31 and the inclined surface portion 41 in the axial direction is configured as a tapered surface that is slightly inclined in a direction toward the radially outward direction toward the one axial direction side. The inner diameter of this portion is smaller than the inner diameter of a portion of the inner peripheral surface of the spare intermediate tubular portion 26 located on the one axial direction side of the partition wall portion 27, and is smaller than the inner diameter of the cylindrical surface portion 42 of the tubular member 21.

[0143] The axial thickness of the partition portion 31 is greater than the axial thickness of the partition portion 27 of the spare intermediate material 28. In this example, the side surface on one axial side of the partition portion 31 is formed of a flat surface perpendicular to the axial direction. The side surface on the other axial side of the partition portion 31 has a recess 34 that is recessed in the axial direction in the radial center. Of the side surface on the other axial side of the partition portion 31, a portion that is located radially outward of the recess 34 is formed of a flat surface that exists in the same imaginary plane as the end face on the other axial side of the intermediate tubular portion 30.

[0144] That is, in this example, the end face on the other axial direction of the intermediate material 32, which is constituted by the end face on the other axial direction of the intermediate tubular portion 30 and the side surface on the other axial direction of the partition portion 31, has a recess 34 in the radial center, and a portion located radially outward from the recess 34 is constituted by a single flat surface perpendicular to the axial direction. In this example, since such a recess 34 is provided, it is possible to facilitate the work of removing the end face on the other axial direction of the intermediate material 32 from the molding die after molding of the intermediate material 32. Alternatively, it is possible to omit providing a recess on the end face on the other axial direction of the intermediate material.

[0145] In this example, the partition wall 31 has an annular scratch 33 formed by the processing in the post-forming step at one axial side portion of the radially intermediate portion. The diameter of the circumscribed circle of the scratch 33 is smaller than the inner diameter of the cylindrical member 21.

[0146] The post-forming step is performed using a press working device 35 as shown in Figures 6 to 7. The press working device 35 includes a die 35a, a die pin 35b, and a punch 35c, each of which is a forming die.

[0147] The die 35a has an inner peripheral surface having a shape that follows the outer peripheral surface of the intermediate material 32, i.e., the outer peripheral surface of the intermediate tubular portion 30. Specifically, the inner peripheral surface of the die 35a has a stepped cylindrical shape in which a large diameter portion 35a1 provided on one axial side and a small diameter portion 35a2 provided on the other axial side are connected by a curved surface portion 35a3. The large diameter portion 35a1 has a shape that follows the large diameter portion 22 of the intermediate tubular portion 30, the small diameter portion 35a2 has a shape that follows the small diameter portion 23 of the intermediate tubular portion 30, and the curved surface portion 35a3 has a shape that follows the connecting surface portion 24 of the intermediate tubular portion 30.

[0148] The die pin 35b is disposed on the inner diameter side of the small diameter portion 35a2 of the die 35a without any rattle in the radial direction. The end face on one axial side, which is the tip face of the die pin 35b, has a shape that conforms to the end face on the other axial side of the intermediate material 32. Specifically, the end face on one axial side of the die pin 35b has a convex portion 35b1 in the radial center portion, which has an outer surface shape that conforms to the inner surface shape of the concave portion 34 of the intermediate material 32. Of the end face on one axial side of the die pin 35b, a radially outer portion that is located radially outer than the convex portion 35b1 is formed of a circular ring-shaped flat surface perpendicular to the central axis of the die pin 35b.

[0149] The punch 35c is supported on a support table (not shown) of the press working device 35 so as to be movable in the axial direction.

[0150] The punch 35c has a protrusion 35c1 at the center of a tip surface (end surface on the other axial direction). The outer circumferential surface of the protrusion 35c1 has a shape that conforms to a portion of the inner circumferential surface of the intermediate tubular portion 30 that is located on one axial side of the partition wall portion 31. The end surface on the other axial side, which is the tip surface of the protrusion 35c1, has a shape that conforms to a side surface of the partition wall portion 31 on one axial side.

[0151] Furthermore, the punch 35c has an annular surface portion 35c2 bent radially outward from one axial end of the outer circumferential surface of the protrusion 35c1. The annular surface portion 35c2 is formed of a flat surface perpendicular to the central axis of the punch 35c.

[0152] When the preliminary intermediate material 28 is processed by the press processing device 35 to obtain the intermediate material 32, first, as shown in Fig. 7(a), the preliminary intermediate material 28 is placed on one axial end face of the die pin 35b, more specifically, on one axial end face of the protrusion 35b1. At the same time, the large diameter portion 22a of the preliminary intermediate material 28 is fitted inside the large diameter portion 35a1 of the die 35a without any radial rattle, and the small diameter portion 23a of the preliminary intermediate material 28 is fitted inside the small diameter portion 35a2 of the die 35a without any radial rattle.

[0153] Next, the punch 35c is moved to the other axial side, and the annular surface portion 35c2 of the punch 35c presses the preliminary intermediate tubular portion 26 of the preliminary intermediate blank 28 from one axial side. Furthermore, from this state, the punch 35c is moved to the other axial side until the axial distance between the annular surface portion 35c2 of the punch 35c and the radially outer portion of the end face on one axial side of the die pin 35b becomes the same as the axial dimension of the tubular member 21.

[0154] 7(a) to 7(b) and 6, the preliminary intermediate tubular portion 26 is axially crushed between the annular surface portion 35c2 of the punch 35c and one axial end face of the die pin 35b, while the materials of the preliminary intermediate tubular portion 26 and the partition portion 27 are moved in a direction to fill the space surrounded by the die 35a, the die pin 35b, and the punch 35c, i.e., the gap in the molding space of the intermediate material 32. In this way, the intermediate material 32 is obtained.

[0155] In the post-forming step, the annular surface portion 35c2 of the punch 35c serves as a forming surface for forming one axial end face of the tubular intermediate portion 30. In this example, the end portion on one axial side of the preliminary tubular intermediate portion 26 abuts against the annular surface portion 35c2 of the punch 35c from the early stage of processing in the post-forming step. That is, from the early stage of processing in the post-forming step, a portion for forming the end face on one axial side of the tubular intermediate portion 30 is present in the vicinity of the annular surface portion 35c2 of the punch 35c.

[0156] For this reason, in this example, in the post-forming step, without excessively increasing the processing load, it is possible to reliably make the material reach the radially outer end of the end face on one axial side of the forming space of the intermediate material 32. As a result, it is possible to prevent the radially outer end of the end face on one axial side of the intermediate tubular portion 30 from becoming underfilled as shown by the chain line α in Fig. 23, and to make the cross-sectional shape of the radially outer end of the end face approximately right-angled.

[0157] In this example, at the end of the processing in the post-forming step, the end face on the other axial side of the intermediate material 32 and the end face on one axial side of the die pin 35b do not simply come into contact with each other, but are engaged in a concave-convex manner based on the presence of the recess 34 and the protrusion 35b1. This reduces the adhesive force between the end face on the other axial side of the intermediate material 32 and the end face on one axial side of the die pin 35b, facilitating the task of separating the end face on the other axial side of the intermediate material 32 from the end face on one axial side of the die pin 35b after forming of the intermediate material 32.

[0158] In the punching step, the radially inner portion of the intermediate tubular portion 30 and the partition wall portion 31, which constitute the intermediate material 32, are punched out in the axial direction to obtain the tubular member 21 as shown in FIG. 3(d).

[0159] The shape of the tubular member 21 is the same as that of the intermediate tubular portion 30, except for the radially inner portion. Therefore, in this example, the cross-sectional shape of the radially outer end portion of the end face on one axial side of the tubular member 21 after the punching process can also be a substantially right-angled cross-section. That is, it is possible to prevent the radially outer end portion of the end face on one axial side of the tubular member 21 from having an undercut shape as shown by the chain line α in Fig. 23.

[0160] In this example, since the partition wall 31 having the scratches 33 and the recesses 34 is removed in the punching step, the scratches 33 and the recesses 34 do not remain in the cylindrical member 21 .

[0161] In the finishing step, finishing processes such as cutting and grinding are applied to the entire surface of the cylindrical member 21. This removes the oxide film present on the entire surface of the cylindrical member 21, and ensures the required shape precision and surface roughness precision for each location on the entire surface of the cylindrical member 21, thereby obtaining the inner ring 10.

[0162] In this example, in the pre-forming step, the radially outer portion of the end face on one axial side of the preliminary intermediate tubular portion 26 is prevented from contacting the annular surface portion 29c2 of the punch 29c. Therefore, it is not necessary to make the processing load in the pre-forming step excessively large. Also, in the post-forming step, from the beginning of processing, the material for forming the end face on one axial side of the intermediate tubular portion 30 is present in the vicinity of the annular surface portion 35c2 of the punch 35c. Therefore, it is not necessary to make the processing load in the post-forming step excessively large.

[0163] That is, according to the manufacturing method of this example, even if a machining allowance sufficient to remove the oxide film by finish processing is secured up to the radially outer end of the end face on one axial side of the cylindrical member 21, there is no need to increase the processing load in the pre-forming step and the post-forming step. Therefore, the load applied to the molding die used in the pre-forming step and the post-forming step can be kept low, and the durability of the molding die can be sufficiently ensured. In addition, since there is no need to excessively increase the volume of the raw material 20 and increase the overall thickness of the machining allowance provided on the cylindrical member 21, the yield can be improved. As a result, the cylindrical member 21 can be manufactured at low cost. In turn, the manufacturing cost of the inner ring 10 can be reduced.

[0164] In this example, since no covering scratches 33 remain on the tubular member 21, no covering scratches 33 remain on the inner ring 10 obtained by subjecting the tubular member 21 to finishing processing. Therefore, the quality of the inner ring 10 can be easily ensured.

[0165] In this example, the metal flow Fm inside the inner ring 10 obtained in the finishing process has an inclined portion Tp in the axial middle part of the inner ring 10, which is inclined radially outward as it moves from the other axial side to one axial side, as shown in Figure 2. The metal flow Fm inside the inner ring 10 is denser at the inclined portion Tp than the portion existing around the inclined portion Tp.

[0166] The reason for this is that in the pre-forming step of the manufacturing method of the tubular member 21, as shown in Figures 5(a) and 5(b), a backward extrusion process is performed on the disk-shaped material 25 to form the preliminary intermediate tubular portion 26, which has a larger axial dimension than the tubular member 21. That is, in this example, due to the influence of the backward extrusion process at this time, a metal flow Fm is formed in a part of the other axial half of the preliminary intermediate tubular portion 26 (part B in Figures 5(b) and 7(a)) that is inclined in the radially outward direction from the other axial side to the one axial side and is denser than the surrounding parts. Then, the metal flow Fm of this part is slightly deformed in the post-forming step as shown in part C in Figure 7(b) and is partially removed in the punching step and finishing step, thereby forming the inclined part Tp.

[0167] In other words, if the metal flow lines Fm inside the inner ring 10 have the inclined portions Tp, it can be estimated that the inner ring 10 has been obtained by the manufacturing method of this example.

[0168] [Second Example] The second embodiment will be described with reference to FIGS.

[0169] In the manufacturing method of the inner ring 10 (see FIG. 1) of this example, the post-forming step, punching step, and finishing step in this process are similar to the post-forming step, punching step, and finishing step in this process of Example 1. In the following, the upsetting step and pre-forming step in this process in the manufacturing method of the inner ring 10 of this example will be described.

[0170] In the swaging process, as shown in Fig. 8(a), when obtaining a disk-shaped raw material 25a from a cylindrical raw material 20, the amount of squeezing of the raw material 20 is made larger than that in the first embodiment. As a result, the outer diameter of the disk-shaped raw material 25a, more specifically, the outer diameter of the axial center portion which is the maximum diameter portion of the disk-shaped raw material 25a, is made the same as the outer diameter of the large diameter portion 22 of the tubular member 21 (see Fig. 8(d)) or slightly smaller than the outer diameter of the large diameter portion 22.

[0171] In the pre-forming step, a press processing device 29 having basically the same structure as the press processing device 29 used in the pre-forming step of the first embodiment is used to perform plastic processing such as forward and backward extrusion on the disk-shaped material 25a to obtain a preliminary intermediate material 28 having a preliminary intermediate cylindrical portion 26 and a partition portion 27 as shown in FIG. 8(b).

[0172] At this time, first, as shown in Figure 9(a), the radially outer edge portion of the end face on the other axial side of the disk-shaped material 25a is engaged with the end portion on one axial side of the curved portion 29a3 of the die 29a, thereby holding the disk-shaped material 25a radially inside the large diameter portion 29a1 of the die 29a.

[0173] Next, the punch 29c is moved to the other axial direction, and the end face of the protruding portion 29c1 of the punch 29c on the other axial direction side presses the radial center of the disk-shaped material 25a. As a result, as shown in Fig. 9(a) to Fig. 9(b), the material in the center of the disk-shaped material 25a is moved to the other axial direction side, and is crushed in the axial direction between the end face of the protruding portion 29c1 on the other axial direction side and the end face of the die pin 29b on one axial direction side, and is moved to the portion between the outer circumferential surface of the protruding portion 29c1 and the inner circumferential surface of the die 29a. At the same time, the material in the radial outer portion of the disk-shaped material 25 is crushed in the radial direction between the outer circumferential surface of the protruding portion 29c1 and the inner circumferential surface of the die 29a, and is moved toward the one radial direction side between the outer circumferential surface of the protruding portion 29c1 and the inner circumferential surface of the die 29a. In this way, the preliminary intermediate material 28 is obtained.

[0174] In the present example, in the preforming step, as shown in Fig. 9(b), the radially outer portion of the end face on one axial side of the preliminary intermediate tubular portion 26 is not brought into contact with the annular surface portion 29c2 of the punch 29c. This makes it possible to reduce the processing load in the preforming step.

[0175] 9(a) and 9(b) show the metal flow Fm inside the workpiece (disc-shaped material 25a, preliminary intermediate material 28) before and after the pre-forming step.

[0176] In this example, the metal flow Fm inside the spare intermediate material 28 has the same configuration as in the first embodiment. Therefore, the metal flow Fm inside the completed inner ring 10 also has the same configuration as in the first embodiment. The other configurations and effects of the second embodiment are the same as those of the first embodiment.

[0177] [Third Example] The third embodiment will be described with reference to FIGS.

[0178] In the manufacturing method of the inner ring 10 (see FIG. 1) of this example, the swaging step, post-forming step, punching step, and finishing step in this process are the same as the swaging step, post-forming step, punching step, and finishing step in this process of Example 1. In the following, the pre-forming step in this process in the manufacturing method of the inner ring 10 of this example will be described.

[0179] In this example, of the preliminary intermediate tubular portion 26a and the partition wall portion 27 that constitute the preliminary intermediate material 28a obtained in the pre-forming step, the outer peripheral surface of the preliminary intermediate tubular portion 26a is configured as a cylindrical surface whose outer diameter does not change in the axial direction. The inner peripheral surface of the preliminary intermediate tubular portion 26a is configured as a tapered surface whose inner diameter becomes larger toward one axial side and whose inclination angle with respect to the axial direction is small. In other words, the preliminary intermediate tubular portion 26a has a substantially cylindrical shape.

[0180] In this example, the outer diameter of the preliminary intermediate tubular portion 26a is equal to or slightly smaller than the outer diameter of the small diameter portion 23 of the tubular member 21 (see FIG. 10(d)). In other words, the outer diameter of the preliminary intermediate tubular portion 26a is equal to or slightly smaller than the inner diameter of the small diameter portion 35a2 of the die 35a constituting the press working device 35 (see FIG. 6) used in the post-forming step.

[0181] In this example, as shown in Fig. 11, in a press processing device 29A used in the pre-forming step, the inner peripheral surface of a die 29Aa has a cylindrical surface shape along the outer peripheral surface of the preliminary intermediate tubular portion 26a. The outer peripheral surface of a protrusion 29Ac1 of a punch 29Ac has a tapered surface shape along the inner peripheral surface of the preliminary intermediate tubular portion 26a. The other configurations and effects of the third example are similar to those of the first example.

[0182] [Fourth Example] The fourth embodiment will be described with reference to FIGS.

[0183] In the manufacturing method of the inner ring 10 (see FIG. 1) of this example, the swaging step, punching step, and finishing step in this process are similar to the swaging step, punching step, and finishing step in this process of Example 1. In the following, the pre-forming step and post-forming step in this process in the manufacturing method of the inner ring 10 of this example will be described.

[0184] 12(b), of the preliminary intermediate tubular portion 26b and the partition wall portion 27a constituting the preliminary intermediate material 28b obtained in the pre-forming step, the preliminary intermediate tubular portion 26b has a substantially cylindrical shape similar to Example 3. That is, the outer circumferential surface of the preliminary intermediate tubular portion 26b is formed of a cylindrical surface whose outer diameter does not change in the axial direction, and the inner circumferential surface of the preliminary intermediate tubular portion 26b is formed of a tapered surface whose inner diameter becomes larger toward one axial side and whose inclination angle with respect to the axial direction is small.

[0185] In this example, the outer diameter of the preliminary intermediate cylindrical portion 26b is equal to or slightly smaller than the outer diameter of the large diameter portion 22 of the cylindrical member 21 (see FIG. 10(d)). In other words, the outer diameter of the preliminary intermediate cylindrical portion 26b is equal to or slightly smaller than the inner diameter of the large diameter portion 35a1 of the die 35a constituting the press working device 35 (see FIGS. 13(a) and 13(b)) used in the post-forming step.

[0186] In this example, the end face on one axial side of the die pin 35Ab constituting the press processing device 35A used in the post-forming process is composed of a single flat surface perpendicular to the axial direction, as shown in Figures 13(a) and 13(b).

[0187] In this example, when the preliminary intermediate material 28b is processed by the press processing device 35A to obtain the intermediate material 32a in the post-forming process, first, as shown in FIG. 13(a), the radially outer end portion of the end face on the other axial side of the preliminary intermediate material 28b is engaged with the radially one end portion of the curved portion 29a3 of the die 29a, thereby holding the preliminary intermediate material 28b radially inside the large diameter portion 35a1 of the die 35a.

[0188] Next, the punch 35c is moved to the other axial side, and the annular surface portion 35c2 of the punch 35c presses the preliminary intermediate tubular portion 26 of the preliminary intermediate blank 28 from one axial side. Furthermore, from this state, the punch 35c is moved to the other axial side until the axial distance between the annular surface portion 35c2 of the punch 35c and the end face on one axial side of the die pin 35Ab becomes the same as the axial dimension of the tubular member 21 (see FIG. 12(d)).

[0189] As a result, as shown in Fig. 13(a) and Fig. 13(b), the spare intermediate material 28b is plastically deformed to obtain an intermediate material 32a. In this example, the obtained intermediate material 32a has an annular surface scar 33a generated by processing in the post-forming step at the axially middle part of the radially middle part of the partition wall 31a. The diameter of the circumscribing circle of the surface scar 33a is smaller than the inner diameter of the tubular member 21. In this example, the partition wall 31a having the surface scar 33a is punched out in the punching step, so that the surface scar 33a does not remain in the obtained tubular member 21. The other configurations and effects of the fourth embodiment are similar to those of the first and third embodiments.

[0190] [Fifth Example] The fifth embodiment will be described with reference to FIGS.

[0191] The manufacturing method of the inner ring 10 (see FIG. 1) of this example includes a swaging step, a molding step, a punching step, and a removing step.

[0192] In this embodiment, in the upsetting process, as in the first embodiment, as shown in Fig. 14(a), the cylindrical raw material 20a is crushed in the axial direction to obtain a disk-shaped raw material 25b having a smaller axial dimension and a larger outer diameter than the raw material 20a. At this time, the amount of crushing of the raw material 20a is made larger than in the first embodiment. As a result, the outer diameter of the disk-shaped raw material 25b, more specifically, the outer diameter of the axial center portion which is the maximum diameter portion of the disk-shaped raw material 25b, is made the same as the outer diameter of the large diameter portion 22 of the cylindrical member 21a or slightly smaller than the outer diameter of the large diameter portion 22.

[0193] In this embodiment, the volume of the raw material 20a is made larger than that of the first embodiment by the amount of the annular protrusion 36 formed in the molding process.

[0194] In the molding process, the disk-shaped material 25b is subjected to plastic processing such as forward and backward extrusion processing to obtain an intermediate material 32b having an intermediate cylindrical portion 30a and a partition portion 31b that closes the end opening on the other axial side of the intermediate cylindrical portion 30a, as shown in Figure 14(b).

[0195] The intermediate cylindrical portion 30a differs from the intermediate cylindrical portion 30a of the first embodiment (see FIG. 3(c)) in that it further includes an annular convex portion (annular protrusion) 36 that protrudes from a radially outer end portion of one axial end portion to one axial side. The partition wall portion 31b differs from the partition wall portion 31 of the first embodiment (see FIG. 3(c)) in that it does not have a covering scratch 33.

[0196] The radial width dimension Wa and axial height H of the annular protrusion 36 can be set arbitrarily. The radial width dimension Wa of the annular protrusion 36 is preferably set in the range of 15% to 35% of the radial width dimension Wb of one axial end of the finally obtained tubular member 21a. The axial height H of the annular protrusion 36 is preferably set to be larger than the thickness of the oxide film (black skin) formed on the finally obtained tubular member 21a in this process, and is preferably set in the range of, for example, 3 to 5 times the thickness of the oxide film. The above numerical values ​​are merely examples and are not limiting.

[0197] In this example, the axial dimension of the intermediate material 32b is larger than the axial dimension of the tubular member 21a to be finally obtained by the amount of the axial height H of the annular protrusion .

[0198] The forming step is performed using a press working device 35B as shown in Fig. 15. The press working device 35B differs from the press working device 35 of the first embodiment (see Fig. 6) only in the shape of the annular surface portion 35Bc2 provided on the punch 35Bc. That is, in this example, the annular surface portion 35Bc2 has an annular recessed portion 35Bc3 recessed in the axial direction on the radially outer side.

[0199] When the press processing device 35B processes the disk-shaped material 25b to obtain the intermediate material 32b, first, the radial outer edge portion of the end face on the other axial side of the disk-shaped material 25b is engaged with the end portion on one axial side of the curved portion 35a3 of the die 35a, thereby holding the disk-shaped material 25b radially inside the large diameter portion 35a1 of the die 35a.

[0200] Next, the punch 35Bc is moved to the other axial direction, and the end face of the protruding portion 35c1 of the punch 35Bc on the other axial direction side presses the radial center of the disk-shaped material 25b. As a result, the material in the center of the disk-shaped material 25b is moved to the other axial direction side, and is crushed in the axial direction between the end face of the protruding portion 35c1 on the other axial direction side and the end face of the die pin 35b on one axial direction side, and is moved to the portion between the outer circumferential surface of the protruding portion 35c1 and the inner circumferential surface of the die 35a. At the same time, the material in the radial outer portion of the disk-shaped material 25b is crushed in the radial direction between the outer circumferential surface of the protruding portion 35c1 and the inner circumferential surface of the die 35a, and is moved toward the one radial direction side between the outer circumferential surface of the protruding portion 35c1 and the inner circumferential surface of the die 35a. As a result, the intermediate material 32b is obtained.

[0201] In this example, as described above, a portion of the material that has moved radially toward one side between the outer peripheral surface of the protrusion 35c1 and the inner peripheral surface of the die 35a enters the entire annular recess 35Bc3, thereby forming the annular protrusion 36.

[0202] In this example, in the molding process, an annular protrusion 36 protruding to one axial side is formed at the radially outer end of the end face on one axial side of the intermediate cylindrical portion 30a, thereby preventing the radially outer end of the end face on one axial side of the intermediate cylindrical portion 30a from having an undercut shape as shown by the dashed line α in Figure 23.

[0203] In the punching step, the radially inner portion of the intermediate tubular portion 30a and the partition wall portion 31b constituting the intermediate material 32b are punched out in the axial direction to obtain a preliminary tubular member 37 as shown in FIG. 14(c).

[0204] The shape of the preliminary cylindrical member 37 is the same as that of the intermediate cylindrical portion 30a excluding the radially inner portion thereof. Therefore, in this example, it is possible to prevent the radially outer end portion of the end face on one axial side of the preliminary cylindrical member 37 obtained in the punching process from having an undercut shape as shown by the chain line α in FIG.

[0205] In the removing step, the annular protrusion 36 of the preliminary cylindrical member 37 is removed by cutting to obtain a cylindrical member 21a as shown in FIG. 14(d).

[0206] In this example, since the cylindrical member 21a is obtained in this manner, it is possible to prevent the radially outer end portion of the end face on one axial side of the cylindrical member 21a from having an undercut shape as shown by the chain line α in Fig. 23. In this example as well, the cylindrical member 21a obtained in this manner is subjected to finishing in the finishing step to obtain the inner ring 10.

[0207] In this embodiment, in order to prevent the shape of the radially outer end of the end face on one axial side of the cylindrical member 21a from becoming an undercut shape as shown by the chain line α in Fig. 23, the volume of the raw material 20a is increased by an amount corresponding to the formation of the annular protrusion 36. However, the amount of increase in volume can be made sufficiently smaller than when the machining allowance thickness provided on the cylindrical member is increased overall. Therefore, the cylindrical member 21a can be manufactured at low cost. The other configurations and effects of the fifth embodiment are the same as those of the first embodiment.

[0208] [Sixth Example] The sixth embodiment will be described with reference to FIGS.

[0209] In the manufacturing method of the inner ring 10 (see FIG. 1) of this example, the swaging step, punching step, removing step, and finishing step are similar to the swaging step, punching step, removing step, and finishing step of Example 5. In the following, the molding step of the manufacturing method of the inner ring 10 of this example will be described.

[0210] In this embodiment, in the forming process, the end face on one axial side of the annular protrusion 36a constituting the intermediate material 32c is not brought into contact with a forming die for performing plastic processing such as forward and backward extrusion processing. More specifically, as shown in FIG. 17, the end face on one axial side of the annular protrusion 36a is not brought into contact with the annular recess 35Cc3 of the annular surface portion 35Cc2 provided on the punch 35Cc. Therefore, in this embodiment, the processing load in the second step can be reduced compared to the first embodiment in which the end face on one axial side of the annular protrusion 36 is brought into contact with a forming die for performing plastic processing. As a result, the die 35a, the die pin 35b, and the punch 35Cc have a long life, and the manufacturing cost of the inner ring 10 can be reduced. The other configurations and effects of the sixth embodiment are the same as those of the fifth embodiment.

[0211] [Seventh Example] The seventh embodiment will be described with reference to FIGS.

[0212] In the manufacturing method of the inner ring 10 (see FIG. 1) of this example, the upsetting step (see FIG. 18(a)), molding step (see FIG. 18(b)), punching step (see FIG. 18(d)), removal step, and finishing step are the same as the upsetting step (see FIG. 16(a)), molding step (see FIG. 16(b)), punching step (see FIG. 16(c)), removal step, and finishing step in the sixth embodiment. The manufacturing method of the inner ring 10 of this example includes a uniforming step (see FIG. 16(c)) of aligning the axial heights of the annular protrusions 36a prior to the removal step.

[0213] In this example, as in the sixth embodiment, in the forming step, as shown in Fig. 17, one axial end face of the annular protrusion 36a is not brought into contact with the annular recess 35Cc3 of the punch 35Cc. Therefore, the shape of one axial end face of the annular protrusion 36a does not match the shape of the bottom face of the annular recess 35Cc3, and the axial height of the annular protrusion 36a may not be uniform over the entire circumference. If the axial height of the annular protrusion 36a is not uniform over the entire circumference, the cutting of the annular protrusion 36a becomes intermittent in the removing step, making the cutting difficult.

[0214] Therefore, in this embodiment, in the equalizing step before the start of the punching step, as shown in FIG. 19, the tip face of a punch 38 constituting a pressing device is pressed against one axial end face of the annular protrusion 36a to crush the annular protrusion 36a in the axial direction. This forms an annular protrusion 36b whose axial height is equalized all around. This makes cutting of the annular protrusion 36b continuous and easy in the finishing step. The other configurations and effects of the seventh embodiment are the same as those of the sixth embodiment.

[0215] [Eighth Example] The eighth embodiment will be described with reference to FIG.

[0216] In the manufacturing method of the inner ring 10 (see FIG. 1) of this embodiment, the order of the uniformizing step and the punching step is reversed from that of the seventh embodiment. That is, in this embodiment, the uniformizing step is performed after the punching step. The other configurations and effects of the eighth embodiment are the same as those of the seventh embodiment.

[0217] The above-described embodiments may be combined as appropriate to the extent that no contradiction occurs. [Explanation of symbols]

[0218] 1 Hub unit bearing 2 Outer ring 3. Hub 4a, 4b Rolling elements 5a, 5b Outer raceway 6 Stationary Flange 7a, 7b Inner raceway 8 Rotating flange 9 Hub 10. Inner Circle 11 Small diameter stepped section 12 Step surface 13 Spline hole 14 Rolling element installation space 15a, 15b Sealing device 16 Seal ring 17 Slinger 18 Large diameter section 19 Small diameter section 20, 20a raw material 21, 21a Cylindrical member 22, 22a Large diameter section 23, 23a Small diameter section 24, 24a connection surface 25, 25a, 25b Disc-shaped material 26, 26a, 26b Spare intermediate cylinder part 27, 27a Bulkhead part 28, 28a Spare intermediate material 29, 29A Press processing equipment 29a, 29Aa dice 29a1 Large diameter section 29a2 Small diameter section 29a3 Curved part 29b Dice Spin 29c, 29Ac punch 29c1, 29Ac1 convex part 29c2 Annular surface part 30, 30a Intermediate cylinder part 31, 31a, 31b bulkhead 32, 32a, 32b, 32c, 32d intermediate material 33, 33a Inflicted wounds 34 Recess 35, 35A, 35B Press processing equipment 35a Dice 35a1 Large diameter section 35a2 Small diameter section 35a3 Curved part 35b, 35Ab Dicepin 35b1 Convex part 35c, 35Bc, 35Cc punch 35c1 Convex part 35c2, 35Bc2, 35Cc2 Annular surface part 35Bc3, 35Cc3 Annular recess 36, 36a, 36b Annular protrusion 37, 37a, 37b, 37c spare tubular members 38 Punch 39 Slope section 40 Cylindrical surface part 41 Slope section 42 Cylindrical surface part 100 Inner Circle 101 Inner raceway 102 Large diameter section 103 Small diameter section 104 Cylindrical member 105 Disc-shaped material 106 Intermediate Material 107 Intermediate cylinder part 108 Bulkhead AP1 annular projection AX1 1st axis plane AX2 Second axis surface DP1 recess FR1, FRG Tsuba ROE Radial outer end

Claims

1. A main body having a cylindrical body and a flange extending outward from the cylindrical body, The main body further has a first axial surface which is one end surface in the axial direction, a second axial surface which is another end surface in the axial direction, an inner circumferential surface of the cylindrical body, a first outer circumferential surface which is an outer circumferential surface of the cylindrical body, a second outer circumferential surface which is an outer circumferential surface of the flange, and a transition surface between the first outer circumferential surface and the second outer circumferential surface, the flange has a first angle between the first axial surface and the second outer peripheral surface and a second angle between the transition surface and the second outer peripheral surface; The metal flow of the body is a first pattern that is continuous along the first axial plane in the vicinity of the first axial plane; a second pattern that is continuous along the second outer circumferential surface in the vicinity of the second outer circumferential surface; a third pattern extending along the transition surface adjacent the transition surface; a plurality of continuous lines each continuous across the first pattern, the second pattern, and the third pattern; having an interval between the continuous lines in the third pattern is narrower than an interval between the continuous lines in the first pattern; the plurality of continuous lines includes a plurality of corner elements disposed adjacent the first corner, The plurality of corner elements have a sharper corner closer to the first corner. Bearing elements.

2. a metal flow duct of the main body has a fourth pattern including a plurality of line elements extending in a direction oblique to a central axis of the main body from the inner circumferential surface toward the transition surface; In the fourth pattern, the intervals between the plurality of line elements in the radially outer region are narrower than the intervals between the plurality of line elements in the radially inner region; In the fourth pattern, the plurality of line elements in the radially outer region have a partial curvature that is convex toward the radially inner side.

2. A bearing element according to claim 1.

3. A bearing comprising a bearing element according to claim 1 or 2.

4. A mechanical device comprising the bearing according to claim 3.

5. A vehicle comprising the bearing according to claim 3.

6. A mechanical device including a cylindrical mechanical component having an outer circumferential surface having a cylindrical large diameter portion provided on one axial side, a cylindrical small diameter portion provided on the other axial side, and a connection surface portion connecting the large diameter portion and the small diameter portion, a metal flow passage in the mechanical component has an inclined portion inclined in a direction toward a radially outward side from the other axial side toward the one axial side, at an axial intermediate portion of the mechanical component; The metal flow area is denser in the inclined portion than in a portion around the inclined portion.

7. The mechanical component is an inner ring, and the connection surface portion of the mechanical component is configured by an inner ring raceway having an arc-shaped cross-sectional shape, The mechanical device of claim 6 , wherein the mechanical device is a bearing device.

8. 8. The mechanical device according to claim 7, wherein the bearing device is a hub unit bearing for rotatably supporting a wheel of an automobile relative to a suspension system.

9. A vehicle including the mechanical device according to any one of claims 6 to 8.

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