Bearing element manufacturing method, cylindrical member manufacturing method, bearing element, bearing, machinery manufacturing method, vehicle manufacturing method, machinery, and vehicle

Abstract

To provide a bearing element manufacturing method, a cylindrical member manufacturing method, a bearing element, a bearing, a machinery manufacturing method, a vehicle manufacturing method, a machinery, and a vehicle which are advantageous for reducing manufacturing cost and / or improving product quality.SOLUTION: This bearing element manufacturing method comprises: a first step of preparing an upset workpiece; a second step of forming a depressed part (DP1), a flange (FR1), and a first axial plane (AX1) on the workpiece through one or two plastic machining processes; and a third step of punching the bottom of the depressed part (DP1) of the workpiece. The depressed part (DP1) has an axial depth with respect to the first axial plane (AX1). The flange (FR1) extends outward in a radial direction. The first axial plane (AX1) formed in the second step provides one end surface of a bearing element. The flange (FR1) formed in the second step has a surface height substantially equal to or higher than the first axial plane (AX1) at the outer end in the radial direction.SELECTED DRAWING: Figure 3

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 from Japanese Patent Application No. 2023-135416, filed August 23, 2023, the contents of which are incorporated herein by reference. [Background technology]

[0002] Figure 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 substantially quarter-circular arc cross section at the axial middle portion of its outer circumferential surface. The inner ring 100 also has a cylindrical large-diameter portion (groove shoulder portion, rib portion) 102 on its outer circumferential surface on one axial side (right side in Figure 21), and a cylindrical small-diameter portion 103 on its outer circumferential surface on the other axial side (left side in Figure 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 2005-288505 A) describes a method for producing two pairs of inner and outer rings, each of which constitutes a tapered roller bearing, from a single cylindrical metal blank. The method described in Patent Document 1 includes the steps of hot forging the cylindrical metal blank to obtain a stepped cylindrical pre-processed blank and separating the pre-processed blank into two cylindrical post-processed blanks having different diameters. The method described in Patent Document 1 also includes the steps of cold forging and separating the smaller-diameter of the two post-processed blanks to obtain two cylindrical members having different diameters, and then finishing these cylindrical members to obtain a set of inner and outer rings; and cold forging and separating the larger-diameter of the two post-processed blanks 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] Japanese Patent Application Laid-Open No. 2005-288505 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 members 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 make up a hub unit bearing that supports vehicle wheels on a suspension system.

[0007] An object of an aspect of the present invention is to provide a manufacturing method that is advantageous in reducing manufacturing 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 face 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, a method for manufacturing a tubular member includes an outer peripheral surface having a cylindrical large-diameter portion on one axial side, a cylindrical small-diameter portion on the other axial side, and a connecting surface portion connecting the large-diameter portion and the small-diameter portion. The method 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 plastically processing the disk-shaped raw material to obtain an intermediate material including an intermediate tubular portion having, on its outer peripheral surface, the large-diameter portion, the small-diameter portion, and the connecting surface portion, and a partition wall portion that closes 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 wall 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] One aspect of the present invention relates to a mechanical device including a cylindrical mechanical component having an outer circumferential surface with a large-diameter portion in a cylindrical surface-like shape provided on one axial side, a small-diameter portion in a cylindrical surface-like shape provided on the other axial side, and a connecting surface portion connecting the large-diameter portion and the small-diameter portion. The metal flow (fiber flow) inside the mechanical component has an inclined portion in an axially intermediate 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 flow is denser in the inclined portion than in the portion surrounding 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 the 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 comprises a bearing element having a trace of having been manufactured by the above-described manufacturing method.

[0016] A 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 that is one axial end surface, a second axial surface that is the other axial end surface, an inner circumferential surface of the cylindrical body, a first outer circumferential surface that is the outer circumferential surface of the cylindrical body, a second outer circumferential surface that is the 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 circumferential surface and a second angle between the transition surface and the second outer circumferential surface. The metal flow lines of the main body include a first pattern that is continuous along the first axial surface near the first axial surface, a second pattern that is continuous along the second outer circumferential surface near the second outer circumferential surface, a third pattern that is continuous along the transition surface near the transition surface, and a plurality of continuous lines that are continuous across the first pattern, the second pattern, and the third pattern. The intervals between the plurality of continuous lines in the third pattern are narrower than the intervals between the plurality of continuous lines in the first pattern. The plurality of continuous lines have a plurality of corner elements arranged near the first corner. The corner elements have sharper corners as they are closer to the first corner. [Effects 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 explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view of a hub unit bearing, which is a mechanical device of the first embodiment. [Figure 2]FIG. 2 is a partial cross-sectional view of an inner ring that constitutes the hub unit bearing of the first embodiment. [Figure 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 of the cylindrical member of the first embodiment, and part (b) is an enlarged view of part A in part (a). [Figure 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 the 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 cylindrical 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 the final stage of the second step in the manufacturing method of the cylindrical member of the third embodiment. [Figure 12] 12A to 12C are cross-sectional views showing the manufacturing method of the cylindrical member of the fourth embodiment in the order of steps. [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 manufacturing method of the cylindrical member of the fifth embodiment in the order of steps. [Figure 15]FIG. 15 is a cross-sectional view showing the final stage of the second step in the manufacturing method of the cylindrical member of the fifth embodiment. [Figure 16] 16A to 16D are cross-sectional views showing the manufacturing method of the cylindrical member of the sixth embodiment in the order of steps. [Figure 17] FIG. 17 is a partial enlarged view showing the final stage of the second step in the manufacturing method of 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 of the cylindrical member according to the seventh embodiment. [Figure 20] 20A to 20C are cross-sectional views showing the manufacturing method of 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] 22A to 22C are cross-sectional views 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 INVENTION

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

[0020] In one embodiment, the manufacturing method of a bearing element (cylindrical member) comprises a first step (initial preparation step), a second step (plastic processing step), and a third step (punching step). Additionally, the manufacturing method of a bearing element (cylindrical member) can comprise at least one other step in addition to the above steps. This manufacturing method reduces the forming load and improves material usage efficiency (material yield). It also improves the strength and / or quality of the product.

[0021] In the first step, a workpiece (WP1) is prepared. The workpiece (WP1) having a predetermined shape that has been upset is provided, or the 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 a disk shape) including a first end surface (ES1), a second end surface (ES2), and an outer peripheral 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 a different shape. The second end surface (ES2) is the surface opposite the first end surface (ES1). In one example, the outer peripheral 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 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, approximately 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 modified 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 pressure treatment (eg, cold forging) that reduces the axial length (height) of the blank and increases the outer diameter (radial width).

[0024] In one example, the raw material (20, 20a) is axially compressed using a press device to form a workpiece (WP1) having a shape that is a deformed version of a generally cylindrical shape (generally a disc shape) or a shape different from a generally cylindrical shape. For example, the workpiece (WP1) obtained in the first step may have a thickness change (volume change) 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 of other steps, and the initial shape of the workpiece (WP1) is set. Such shape control in the initial stage improves material utilization efficiency (material yield). Furthermore, the strength of the product is improved based on the material flow pattern.

[0025] In the second process (plastic processing process), 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 process have a peripheral wall (CW1) surrounding the recess (DP1) and a flange (FR1) 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 located 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 process provides one end surface of the bearing element (the tubular 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 process has a surface height at the radially outer end (ROE), which is a region near the radially outer end / outer edge, that is substantially the same as or greater than that of the first axial surface (AX1). For example, the axial surface profile of the radially outer end (ROE) has a height position that is the same as or greater in the axial direction than that of the first axial surface (AX1) relative 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 approximately 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 merely examples, and other values ​​may be applicable in other examples. Alternatively and / or additionally, a modified shape of the above shape or a shape other than the above may be set in the second step.

[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 operation. The annular protrusion (AP1) has a shape that protrudes axially outward from the first axial surface (AX1) at the radially 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 face (P13) including a tip region of the first protrusion portion (P12). The first punch face (P13) corresponds to the bottom surface of the depression (DP1). The first punch (PC1) has a second punch face (P14) including the outer peripheral surface of the first protrusion portion (P12), and a third punch face (P15) including an annular surface provided on the first base portion (P11). The second punch face (P14) corresponds to the inner wall surface (inner peripheral surface) of the depression (DP1). The third punch face (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 (depression, groove) (P17) located near the radially outer edge of the first punch surface (P13) and extending circumferentially. 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 of other processes, and the shape of the workpiece (WP4) after plastic processing is set. This shape control improves material utilization efficiency (material yield). Furthermore, the strength of the product is improved based on the material flow pattern.

[0029] In several examples shown in Figures 3-13, the second step includes a first plastic working process in which a pre-dent (DP0) is formed in the upset workpiece (WP1) using a second punch (PC2). The second step also includes a second plastic working process in which, after the first plastic working process, a pre-dent (DP0) is formed in the workpiece (WP2) using a third punch (PC3) to simultaneously form a pre-dent (DP1), a flange (FR1), and a first axial surface (AX1). In the second plastic working process, the simultaneous formation of the pre-dent (DP1), the flange (FR1), and the first axial surface (AX1) includes rounding the corner of the flange (FR1) at the radially outer end (ROE). For example, in the workpiece (WP3) after the second plastic working process, 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 working is changed to a nearly square edge of the workpiece (WP3) after the second plastic working. The second plastic working by the third punch (PC3) causes part of the material of the workpiece (WP2) to flow radially outward, providing a workpiece (WP3) with an increased thickness near its radially outer end.

[0030] In one example, the second punch (PC2) has a second base portion (P21) and a second protrusion portion (P22), and the third punch (PC3) has a third base portion (P31) and a third protrusion portion (P32). The second protrusion portion (P22) of the second punch (PC2) forms a preliminary depression (DP0) in the workpiece. The third protrusion portion (P32) of the third punch (PC3) forms a depression (DP1) in the workpiece. The second punch (PC2) has a fifth punch face (P25) including a tip region of the second protrusion portion (P22). The fifth punch face (P25) corresponds to the bottom surface of the preliminary depression (DP0). The second punch (PC2) has a sixth punch face (P26) including the outer peripheral surface of the second protrusion portion (P22). The sixth punch face (P26) corresponds to the inner wall surface of the preliminary depression (DP0). The third punch (PC3) has a seventh punch surface (P37) including the 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 the 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 shorter than that of the second protrusion (P22) of the second punch (PC2). Also, the inclination (θ11) of the outer peripheral 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 peripheral 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 protrusions (P32) of the third punch (PC3) is smaller than that of the second protrusions (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 protrusions (P22) is larger than that of the third protrusions (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, and the seventh punch face (P37) of the third punch (PC3) has a surface shape that is uniform overall compared to the fifth punch face (P25).

[0034] The second punch (PC2) and third punch (PC3) are designed based on the shape parameters of the final bearing element (cylindrical member) and the processing parameters of other processes, and the shape of the workpiece (WP3) after plastic processing is set. This shape control improves material utilization 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 step of axially crushing a cylindrical raw material (20, 20a) to obtain a disk-shaped raw material (25, 25a, 25b) having an axial dimension smaller than that of the raw material (20, 20a) and an outer diameter larger than the outer diameter of the raw material (20, 20a), and a plastic working step of applying the large-diameter portion (22) and the small-diameter portion (23) to the outer peripheral surface. The method includes a molding step of obtaining an intermediate material (32, 32a, 32b, 32c) including an intermediate cylindrical portion (30, 30a) having a small diameter portion (23) and the connecting surface portion (24) and a partition wall portion (31, 31a, 31b) closing an end opening on the other axial side of the intermediate cylindrical portion (30, 30a), and a punching step of punching out a radially inner portion of the intermediate cylindrical 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 cylindrical member (21, 21a).

[0036] In one example, the cylindrical member (21, 21a) may have an inner peripheral surface having an inclined surface portion (41) provided at one axial end portion thereof, the inner diameter of which increases toward one axial end portion, and cylindrical surface portions (42) provided at an intermediate axial portion and an end portion on the other axial end portion. Also, the intermediate cylindrical portion (30, 30a) may have the inclined surface portion (41) at one axial end portion of the inner peripheral 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 that has a shape that follows the outer peripheral 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 spare 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 the radially outer portion of the end face on one axial side of the preliminary intermediate cylindrical portion (26, 26a, 26b) can be prevented from contacting a forming die used for plastic working.

[0039] For example, the outer diameter of one axial side portion of the auxiliary 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 auxiliary 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) that protrudes toward one axial direction at a radially outer end portion of an end surface on one axial direction side. For example, the forming step is a step of obtaining the intermediate material (32, 32a, 32b, 32c) by plastic working 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 the forming step includes a removal step of removing the annular convex portion (36, 36a, 36b).

[0041] For example, in the forming step, the end face on one axial side of the annular convex portion (36, 36a, 36b) can be prevented from coming into contact with a forming die used for plastic working.

[0042] In one example, before the removing step, a uniforming step can be provided in which the annular convex portions (36, 36a, 36b) formed in the molding step are crushed in the axial direction to make the axial height of the annular convex portions (36, 36a, 36b) uniform over 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-described 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 rotatably supporting a wheel of an automobile relative to a suspension device.

[0046] In one embodiment, a 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 a sloped portion (Tp) in the axially intermediate portion of the machine component that slopes radially outward from the other axial side to the one axial side, and the metal flow is denser in the sloped portion (Tp) than in the portion around the sloped 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 rotatably supporting a wheel of an automobile relative to a suspension device.

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

[0051] According to the above-described method for manufacturing 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 large-diameter portion having a cylindrical surface provided on one axial side, a small-diameter portion having a cylindrical surface provided on the other axial side, and a connecting surface portion connecting the large-diameter portion and the small-diameter portion.

[0052] 2, 7, and 15, the bearing element includes a body (10) having a cylindrical body (TBB) and a flange (FRG) extending outward from the cylindrical body (TBB). The body (10) has a first axial surface (AS1) that is one axial end surface and a second axial surface (AS2) that is another axial end surface. The body (10) also has an inner circumferential surface (IS1) of the cylindrical body (TBB), a first outer circumferential surface (CS1) that is the outer circumferential surface of the cylindrical body (TBB), a second outer circumferential surface (CS2) that is the outer circumferential surface of the flange (FRG), and a transition surface (CS3) between the first outer circumferential surface (CS1) and the second outer circumferential 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) bears traces of production by the above-described manufacturing method. In one example, the traces are metal flow (metal fiber flow, fibrous metal structure, grain flow lines) observed in a cross section of the bearing element (tubular member). Figures 2, 5, 7, 9, and 15 show examples of metal flow in an axial cross section (axial cross section) of a bearing element (tubular member) and its manufacturing process. The traces can also be confirmed based on microstructural analysis and / or structural analysis, which are different from analysis based on metal flow.

[0054] In one example, the metal flow patterns of the main body (10) have 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 patterns of the main body (10) further have a plurality of continuous lines (CL1, CL2, CL3) that are each 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 spacing between the multiple continuous lines (CL1, CL2, CL3) in the third pattern (PA3) is narrower than the spacing 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 near 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 elements (CE1) and (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 Figure 2, the metal flow of the main body (10) has a fourth pattern (PA4) including a plurality of line elements extending obliquely with respect 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 radially inward.

[0058] A bearing element having a predetermined metal flow is advantageous in terms of reducing manufacturing costs and / or improving strength. A continuous line element of metal flow is advantageous in terms of 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-described bearing, which is advantageous for reducing the cost of the machine.

[0061] In one embodiment, a vehicle includes the above-described 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-described bearing can be applied to both hub unit bearings for driving wheels and hub unit bearings for driven wheels. In FIG. 24, the hub unit bearing 151 is for a driving wheel and includes an outer ring 152, a hub 153, and multiple 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. Furthermore, the vehicle 200 can have a support structure similar to that described above for the hub unit bearing 151 for the driven wheel.

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

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

[0065] In the upsetting 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 to obtain a cup-shaped intermediate material 106 as shown in Fig. 22(b). The intermediate material 106 includes an intermediate cylindrical portion 107 having the same outer peripheral surface shape as that of the cylindrical member 104 and the same axial dimension as that of the cylindrical member 104, and a partition wall 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 cylindrical portion 107.

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

[0068] Although this manufacturing method allows for efficient production of the cylindrical member 104 from a cylindrical metal material with a small number of steps, there is room for improvement in the following respects.

[0069] That is, because tubular member 104 is produced by hot forging, an oxide film (black scale) is formed on its surface. If this oxide film remains on the surface of inner ring 100 after completion, it becomes difficult to ensure the shape precision and surface roughness precision required of inner ring 100. For this reason, it is necessary to ensure that tubular member 104 has enough machining allowance to remove the oxide film on the surface during 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 present inside the molding die, the material (metal material) flowing toward one axial side may not reach the final point, which is the radially outer end of the end on one axial side.

[0071] In this case, the radially outer end 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, a shape that retreats toward the other axial side as it moves radially outward).

[0072] As a result, there is a possibility that an inconvenience will occur in which it will not be possible to secure a machining allowance sufficient to remove the oxide coating 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 an inconvenience occurs will be discarded, which will increase the manufacturing costs of the inner ring 100.

[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 disc-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 increases the load on the molding die, requires larger processing equipment, and shortens the life of the molding die, resulting in increased manufacturing costs for the inner ring 100.

[0075] Another method for overcoming the above-described inconveniences is to increase the volume of the raw material and increase the overall thickness of the machining allowance provided in the tubular member 104. With this method, even if the radially outer end of the end face on one axial side of the tubular member 104 has an undercut shape as shown by the chain line α in Fig. 23 , it becomes easy to ensure that the radially outer end of the end face on one axial side of the tubular member 104 has a machining allowance large enough to remove the oxide film by finish processing.

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

[0077] In each of the embodiments, it is possible to reduce the manufacturing costs of a mechanical component made from a tubular member having an outer circumferential surface with a large-diameter portion having a cylindrical surface provided on one axial side, a small-diameter portion having a cylindrical surface 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 method for manufacturing a tubular member can be used to manufacture 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 method for manufacturing a tubular member can be used to manufacture a bearing device having a structure different from the example shown in Fig. 1, specifically, a tubular member (bearing element) for obtaining an inner ring or sliding bearing that constitutes a single-row or double-row angular contact ball bearing. In this case, the tubular member (bearing element) can be subjected to finishing processes such as cutting and grinding to manufacture the inner ring or sliding bearing.

[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 cylindrical member is not particularly limited as long as it is a metal material that can be hot forged, and various metal materials such as iron alloys such as bearing steel, aluminum alloys, copper alloys, etc. can be used.

[0083] With respect 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 angular and has a cross-sectional shape that is approximately a quarter-circular arc.

[0086] Furthermore, the outer ring 2 has a stationary flange 6 that protrudes radially outward from an axially intermediate portion. The stationary flange 6 is a portion used to support and fix the outer ring 2 to a knuckle of a suspension device.

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

[0088] Furthermore, the hub 3 has a rotating flange 8 that protrudes radially outward from a portion located axially outward of the outer ring 2. The rotating flange 8 is a portion that connects and fixes the wheel and 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 rotation 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 the part adjacent to it on the axially outer side and onto which the inner ring 10 is fitted, and the axially outer end of the small diameter step 11 has a step surface 12 facing inward in the axial direction. Because 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 that constitutes a drive shaft member.

[0091] The inner ring 10 is made of a hard metal such as bearing steel and has a substantially cylindrical shape. An inner ring raceway 7a on the inner side in the axial direction is provided on the outer peripheral surface of the inner ring 10 at an axially intermediate portion.

[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 the axially inner end portion, which is on one axial side, and whose inner diameter increases toward the axially inner side, and a cylindrical surface portion 40 provided at the axially intermediate portion and the axially outer end portion, which is on the other axial side. In this example, the inclined surface portion 39 has a cross-sectional shape that is approximately a quarter-circular arc. In one example, the inclined surface portion can also be configured as a conical surface having a linear generatrice shape.

[0094] In this example, the end faces on both sides of the inner ring 10 in the axial direction are formed as 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 stepped portion 11 of the hub ring 9, and the axially outer end face of the inner ring 10 abuts against a stepped surface 12 of the hub ring 9.

[0097] The hub unit bearing can also be applied to a hub unit bearing having a crimped portion at the axially inner end of the hub wheel that presses against 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 outside of 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 an iron alloy 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 and the pitch circle diameter of the rolling elements 4b in the axially inner row are the same. However, the hub unit bearing can also be applied to a different diameter PCD hub unit bearing in which the pitch circle diameter of the rolling elements in the axially inner row are 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 tip ends of multiple seal lips that make up 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, with one axial side being the upper side in Figures 3 to 7 and the other axial side being the lower side in Figures 3 to 7. In Figures 3 to 7, the axial direction of each illustrated member coincides with the up-down direction. However, the up-down direction in Figures 3 to 7 does not necessarily coincide with the up-down direction (vertical direction) during processing. In other words, the up-down direction in Figures 3 to 7 can coincide with the horizontal direction or with a direction inclined relative to both the up-down direction (vertical direction) and the horizontal direction.

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

[0105] The plastic working in this step is hot forging. As a result, an oxide film (black scale) is formed on the surface of the tubular member 21 after this step. If this 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 Figure 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 cylindrical 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 cylindrical member 21 has a large diameter portion 22 with a cylindrical surface provided on one axial side, a small diameter portion 23 with a cylindrical surface 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 that is approximately a 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 axial end portion, whose inner diameter increases toward the inside of the axial direction, and a cylindrical surface portion 42 provided at an intermediate axial portion and the other axial end portion. The inclined surface portion 41 has an arc-shaped cross section similar to 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 by 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 amount of the 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 amount of the machining allowance.

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

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

[0111] In the upsetting 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 into a predetermined length.

[0113] The outer peripheral surface of the disk-shaped material 25 has a substantially arc-shaped cross section (generatrix shape) in which the outer diameter of the axial center portion is larger than the outer diameters of both axial end portions. In this example, the outer diameter of the disk-shaped material 25, more specifically, the outer diameter of the axial center portion, which is the largest diameter portion of the disk-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 diameters of the axial end portions, which are the smallest diameter portions of the disk-shaped material 25, are 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 cylindrical portion 26 having an axial dimension larger than the axial dimension of the cylindrical member 21, and a partition wall portion 27 that closes the end opening on the other axial side of the preliminary intermediate cylindrical portion 26.

[0117] As long as the axial dimension of the auxiliary intermediate cylindrical portion is larger than the axial dimension of the cylindrical member and the partition wall portion closes the end opening on the other axial side of the auxiliary intermediate cylindrical portion, the shapes of the auxiliary intermediate cylindrical portion and the partition wall 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 cylindrical portion 26 is made slightly smaller than the outer diameter of the large diameter portion 22 of the cylindrical member 21, and the outer diameter of the other axial side portion of the preliminary intermediate cylindrical portion 26 is made slightly smaller than the outer diameter of the small diameter portion 23 of the cylindrical member 21. More specifically, the outer diameter of one axial side portion of the preliminary intermediate cylindrical 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 cylindrical member 21) by an insertion clearance for 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 of the die 35a used in the post-forming process (see Figure 7(a)) (= the outer diameter of the small diameter portion 23 of the tubular member 21) 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 connecting surface portion (transition portion) 24a connecting the large-diameter portion 22a and the small-diameter portion 23a and having a cross-sectional shape that is approximately a 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 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 an axial dimension smaller than the axial dimension of the small-diameter portion 23 of the tubular member 21. The connecting surface portion 24 a has a radius of curvature larger than the radius of curvature of the connecting surface portion 24 of the cylindrical member 21 .

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

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

[0122] In this example, the opening width (inner diameter) of the end portion on one axial side of the auxiliary 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 example, 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 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 blank, which makes it easier to remove the end face on the other axial side of the preliminary intermediate blank from the molding die after molding of the preliminary intermediate blank.

[0126] In this step, the material that forms 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, smaller than the radial thickness of the preliminary intermediate tubular portion 26. This improves yield.

[0127] The pre-forming step is carried out 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 shaped to fit 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 formed by a large-diameter portion 29a1 provided on one axial side and a small-diameter portion 29a2 provided on the other axial side, connected by a curved surface portion 29a3. The large-diameter portion 29a1 has a shape that fits the large-diameter portion 22a of the preliminary intermediate tubular portion 26, the small-diameter portion 29a2 has a shape that fits the small-diameter portion 23a of the preliminary intermediate tubular portion 26, and the curved surface portion 29a3 has a shape that fits the connecting surface 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 play in the radial direction. The tip end face of the die pin 29b, which is the end face on one axial side, has a shape that conforms 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 its tip end surface (the end surface on the other axial side). The outer circumferential surface of the protrusion 29c1 has a shape that follows the radially inner portion of the end surface on one axial side of the preliminary intermediate cylindrical portion 26 and the portion of the inner circumferential surface of the preliminary intermediate cylindrical portion 26 that is located on one axial side of the partition wall portion 27. The end surface on the other axial side, which is the tip end surface of the protrusion 29c1, has a shape that follows the side surface of the partition wall portion 27 on one axial side.

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

[0133] When the press processing device 29 is used to perform backward 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, punch 29c is moved to the other axial side, and the end face of protrusion 29c1 of punch 29c on the other axial side presses the radial center portion of disk-shaped material 25. As a result, as shown in Figures 5(a) and 5(b) and 4(a), the center portion of disk-shaped material 25 is crushed in the axial direction between the end face of protrusion 29c1 on the other axial side and the end face of die pin 29b on one axial side, while the material on the radial outer side of disk-shaped material 25 is moved to the portion between the outer peripheral surface of protrusion 29c1 and the inner peripheral surface of die 29a, and a preliminary intermediate material 28 is obtained.

[0135] In this example, in the pre-forming step, at least a radial portion of one axial end face of the preliminary intermediate cylindrical portion 26 is prevented from coming into contact with the forming die used for the rearward extrusion process.

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

[0137] In the pre-forming step, the entire end surface on one axial side of the preliminary intermediate cylindrical portion may be in contact with the forming die, or may not be in contact with the forming 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 follows the outer peripheral 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 the end opening of the cylindrical intermediate portion 30 on the other axial side.

[0140] The intermediate cylindrical portion 30 has an axial dimension equal to the axial dimension of the cylindrical member 21. The intermediate cylindrical portion 30 has an outer peripheral surface shape equal to the outer peripheral surface shape of the cylindrical member 21. That is, the outer peripheral surface of the intermediate cylindrical 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 axially opposite end faces of the intermediate cylindrical portion 30 have the same shape as the axially opposite end faces of the cylindrical member 21, that is, flat surfaces perpendicular to the axial direction.

[0142] The one axial end of the inner circumferential surface of the intermediate tubular portion 30 has the same shape as the one axial end of the inner circumferential surface of the tubular member 21. That is, the inner circumferential surface of the intermediate tubular portion 30 has an inclined surface portion 41 at the one axial end. Of the inner circumferential surface of the intermediate tubular portion 30, a portion 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 radially outward as it approaches the one axial side. The inner diameter of this portion is smaller than the inner diameter of the portion of the inner circumferential surface of the auxiliary intermediate tubular portion 26 located axially further to the one axial side than the partition wall portion 27, and is also smaller than the inner diameter of the cylindrical surface portion 42 of the tubular member 21.

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

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

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

[0146] The post-forming step is performed using a press working device 35 as shown in Figures 6 and 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 shaped to fit the outer peripheral surface of the intermediate material 32, i.e., the outer peripheral surface of the tubular intermediate portion 30. Specifically, the inner peripheral surface of the die 35a has a stepped cylindrical shape formed by a large-diameter portion 35a1 provided on one axial side and a small-diameter portion 35a2 provided on the other axial side, connected by a curved surface portion 35a3. The large-diameter portion 35a1 has a shape that fits the large-diameter portion 22 of the tubular intermediate portion 30, the small-diameter portion 35a2 has a shape that fits the small-diameter portion 23 of the tubular intermediate portion 30, and the curved surface portion 35a3 has a shape that fits the connecting surface 24 of the tubular intermediate portion 30.

[0148] The die pin 35b is arranged on the inner diameter side of the small diameter portion 35a2 of the die 35a without any radial backlash. The end face on one axial side, which is the tip surface of the die pin 35b, has a shape that follows 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, the convex portion 35b1 having an outer surface shape that follows the inner surface shape of the recess 34 of the intermediate material 32. Of the end face on one axial side of the die pin 35b, the radially outer portion, which is located radially outward of the convex portion 35b1, is composed of a circular flat surface that is 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 its tip end surface (the end surface on the other axial side). The outer circumferential surface of the protrusion 35c1 has a shape that follows the portion of the inner circumferential surface of the intermediate cylindrical 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 end surface of the protrusion 35c1, has a shape that follows the side surface of the partition wall portion 31 on one axial side.

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

[0152] When the preliminary intermediate material 28 is processed using 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 into 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 into 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 35c2 of the punch 35c presses the preliminary intermediate tubular portion 26 of the preliminary intermediate blank 28 from one axial side. From this state, the punch 35c is further moved to the other axial side until the axial distance between the annular surface 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), 7(b) and 6, the preliminary intermediate tubular portion 26 is crushed in the axial direction 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 gaps in the space surrounded by the die 35a, the die pin 35b and the punch 35c, i.e., the forming space of the intermediate material 32. In this way, the intermediate material 32 is obtained.

[0155] In the post-forming step, the annular surface 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, from the early stage of processing in the post-forming step, the end portion on one axial side of the preliminary tubular intermediate portion 26 abuts against the annular surface 35c2 of the punch 35c. In other words, from the early stage of processing in the post-forming step, a portion for forming the one axial end face of the tubular intermediate portion 30 is present in the vicinity of the annular surface 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 having an underfill shape 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 contact each other but are engaged with each other in a concave-convex manner based on the presence of the recessed portion 34 and the protruding portion 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 work 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 the intermediate material 32.

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

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

[0160] In this example, the partition wall 31 having the scratches 33 and the recesses 34 is removed in the punching step, so that 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 29c2 of the punch 29c. Therefore, there is no need to apply an excessively large processing load in the pre-forming step. Also, in the post-forming step, from the beginning of processing, a portion for forming the end face on one axial side of the intermediate tubular portion 30 is present in the vicinity of the annular surface 35c2 of the punch 35c. Therefore, there is no need to apply an excessively large processing load in the post-forming step.

[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 tubular 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, thereby ensuring sufficient durability of the molding die. Furthermore, 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 tubular member 21, yield can be improved. As a result, the tubular member 21 can be manufactured at low cost. This, in turn, reduces the manufacturing cost of the inner ring 10.

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

[0165] In this example, the metal flow region Fm inside the inner ring 10 obtained in the finishing process has a sloped portion Tp in the axially middle part of the inner ring 10 that slopes radially outward as it moves from the other axial side to one axial side, as shown in Figure 2. The metal flow region Fm inside the inner ring 10 is denser at the sloped portion Tp than the portion around the sloped 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 a disk-shaped material 25 to form a preliminary intermediate tubular portion 26 that has a larger axial dimension than the tubular member 21. That is, in this example, due to the effect of the backward extrusion process at this time, a metal flow Fm is formed in part of the other axial half of the preliminary intermediate tubular portion 26 (part B in Figures 5(b) and 7(a)). The metal flow Fm in this part is inclined radially outward as it moves from the other axial side to one axial side and is denser than the surrounding part. Then, the metal flow Fm in 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] That is, if there is a sloped portion Tp in the metal flow lines Fm inside the inner ring 10, it can be assumed that the inner ring 10 is obtained by the manufacturing method of this example.

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

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

[0170] In the upsetting 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 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 working device 29 having basically the same structure as the press working device 29 used in the pre-forming step of the first embodiment is used to perform plastic working such as forward and backward extrusion on the disk-shaped material 25a, thereby obtaining a preliminary intermediate material 28 having a preliminary intermediate cylindrical portion 26 and a partition wall portion 27 as shown in FIG. 8(b).

[0172] In this case, 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 protrusion 29c1 of the punch 29c on the other axial side presses the radial center of the disc-shaped material 25a. As a result, as shown in Figures 9(a) and 9(b), the material in the central portion of the disc-shaped material 25a is moved to the other axial direction and crushed in the axial direction between the end face of the protrusion 29c1 on the other axial side and the end face of the die pin 29b on one axial side, and moved to the portion between the outer surface of the protrusion 29c1 and the inner surface of the die 29a. At the same time, the material in the radially outer portion of the disc-shaped material 25a is crushed in the radial direction between the outer surface of the protrusion 29c1 and the inner surface of the die 29a and moved toward one radial direction between the outer surface of the protrusion 29c1 and the inner surface of the die 29a. This results in a preliminary intermediate material 28.

[0174] In this example, in the pre-forming step, as shown in Fig. 9(b), the radially outer portion of the end face on one axial side of the preliminary intermediate cylindrical portion 26 is not brought into contact with the annular surface portion 29c2 of the punch 29c, thereby reducing the processing load in the pre-forming step.

[0175] 9(a) and 9(b) show the metal flow Fm inside the workpiece (disk-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 example. Therefore, the metal flow Fm inside the completed inner ring 10 also has the same configuration as in the first example. The other configurations and effects of the second example are the same as those of the first example.

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

[0178] In the manufacturing method of 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. The pre-forming step in this process in the manufacturing method of inner ring 10 of this example will be described below.

[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 increases 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 cylindrical portion 26a is the same as or slightly smaller than the outer diameter of the small diameter portion 23 of the cylindrical member 21 (see FIG. 10(d)). In other words, the outer diameter of the preliminary intermediate cylindrical portion 26a is the same as 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 working device 29A used in the pre-forming step, the inner peripheral surface of a die 29Aa has a cylindrical surface shape that conforms to the outer peripheral surface of the auxiliary intermediate tubular portion 26a. The outer peripheral surface of a protrusion 29Ac1 of a punch 29Ac has a tapered surface shape that conforms to the inner peripheral surface of the auxiliary 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 method for manufacturing inner ring 10 (see FIG. 1) of this example, the swaging step, punching step, and finishing step in this process are the same as the swaging step, punching step, and finishing step in this process of Example 1. Below, the pre-forming step and post-forming step in this process in the method for manufacturing inner ring 10 of this example will be described.

[0184] 12(b), of the preliminary intermediate cylindrical portion 26b and the partition wall portion 27a that constitute the preliminary intermediate material 28b obtained in the pre-forming step, the preliminary intermediate cylindrical portion 26b has a substantially cylindrical shape, similar to Example 3. That is, the outer peripheral surface of the preliminary intermediate cylindrical portion 26b is configured as a cylindrical surface whose outer diameter does not change in the axial direction, and the inner peripheral surface of the preliminary intermediate cylindrical portion 26b is configured as a tapered surface whose inner diameter increases toward one side in the axial direction 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 the same as 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 the same as or slightly smaller than the inner diameter of the large diameter portion 35a1 of the die 35a that constitutes 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 that constitutes 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, in the post-forming process, when the preliminary intermediate material 28b is processed using the press processing device 35A to obtain the intermediate material 32a, first, as shown in Figure 13(a), the radial outer end of the end face on the other axial side of the preliminary intermediate material 28b is engaged with the end on one radial side 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 Figures 13(a) and 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 overcut 33a caused by processing in the post-forming step in the axially middle portion of the radially middle portion of the partition wall portion 31a. The diameter of the circumscribing circle of the overcut 33a is smaller than the inner diameter of the tubular member 21. In this example, too, the partition wall portion 31a having the overcut 33a is punched out in the punching step, so the overcut 33a does not remain in the obtained tubular member 21. The other configurations, functions, and effects of the fourth embodiment are similar to those of the first or third embodiment.

[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 forming step, a punching step, and a removing step.

[0192] In this example, in the upsetting process, as in the first embodiment, as shown in Fig. 14(a), a 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 central 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 tubular member 21a or slightly smaller than the outer diameter of the large diameter portion 22.

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

[0194] In the forming process, the disk-shaped material 25b is subjected to plastic processing such as forward and backward extrusion processing to obtain an intermediate material 32b, as shown in Figure 14(b), which has 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.

[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 axially from the radially outer end of one axial end portion. 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 as desired. 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 larger than the thickness of the oxide film (black scale) formed on the finally obtained tubular member 21a in this step, 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 cylindrical 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 apparatus 35B as shown in Fig. 15. The press working apparatus 35B differs from the press working apparatus 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 axially to the other side, and the end face of the protrusion 35c1 of the punch 35Bc on the other axial side presses the radial center of the disk-shaped material 25b. This causes the material in the central portion of the disk-shaped material 25b to move axially to the other axial side, where it is crushed axially between the end face of the protrusion 35c1 on the other axial side and the end face of the die pin 35b on one axial side, and then moved to the portion between the outer surface of the protrusion 35c1 and the inner surface of the die 35a. At the same time, the material in the radially outer portion of the disk-shaped material 25b is crushed radially between the outer surface of the protrusion 35c1 and the inner surface of the die 35a, and then moved radially to the one radial side between the outer surface of the protrusion 35c1 and the inner surface of the die 35a. This produces the intermediate material 32b.

[0201] In this example, as described above, a portion of the material that moves 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 that protrudes to one axial direction 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 becoming underfilled as shown by the chain line α in Figure 23.

[0203] In the punching step, the radially inner portion of the intermediate cylindrical portion 30a and the partition wall portion 31b that constitute the intermediate material 32b are punched out in the axial direction to obtain a preliminary cylindrical 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, and 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 step from having an undercut shape as shown by the chain line α in Fig. 23 .

[0205] In the removing step, the annular projection 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 of the end face on one axial side of the cylindrical member 21a from having an underfill shape as shown by the chain line α in Figure 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 example, to prevent the shape of the radially outer end of the end face on one axial side of the cylindrical member 21a from becoming undercut as shown by the chain line α in FIG. 23, the volume of the raw material 20a is increased by the amount required to form the annular protrusion 36. However, the amount of increase in volume can be made sufficiently smaller than when the thickness of the machining allowance provided on the cylindrical member is increased overall. Therefore, the cylindrical member 21a can be manufactured at low cost. The other configurations, functions, 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 inner ring 10 (see FIG. 1) of this example, the swaging step, punching step, removing step, and finishing step are the same as the swaging step, punching step, removing step, and finishing step of Example 5. The molding step of the manufacturing method of inner ring 10 of this example will be described below.

[0210] In this embodiment, during the forming process, one axial end face of the annular protrusion 36a constituting the intermediate material 32c does not contact a molding die used for plastic working, such as forward / backward extrusion. More specifically, as shown in FIG. 17 , one axial end face of the annular protrusion 36a does not contact the annular recess 35Cc3 of the annular surface 35Cc2 of the punch 35Cc. Therefore, in this embodiment, the processing load in the second step is reduced compared to the first embodiment, in which one axial end face of the annular protrusion 36a contacts a molding die used for plastic working. As a result, the die 35a, die pin 35b, and punch 35Cc have a longer life, thereby reducing the manufacturing cost of the inner ring 10. The remaining configuration, functions, and effects of the sixth embodiment are similar to 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 process (see FIG. 18(a)), molding process (see FIG. 18(b)), punching process (see FIG. 18(d)), removal process, and finishing process are the same as the upsetting process (see FIG. 16(a)), molding process (see FIG. 16(b)), punching process (see FIG. 16(c)), removal process, and finishing process in Example 6. The manufacturing method of the inner ring 10 of this example includes a uniforming process (see FIG. 16(c)) that aligns the axial heights of the annular protrusions 36a before the removal process.

[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 surface 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 will be discontinuous and difficult in the removal step.

[0214] Therefore, in this example, in the equalizing step before the punching step, as shown in Figure 19, the tip surface of a punch 38 constituting a press processing device is pressed against one axial end surface of the annular protrusion 36a, thereby crushing the annular protrusion 36a in the axial direction. This forms an annular protrusion 36b whose axial height is uniform all around. This makes cutting of the annular protrusion 36b continuous and easy in the finishing step. The other configurations, functions, and effects of the seventh example are the same as those of the sixth example.

[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 example, the order of the equalizing step and the punching step is reversed from that of the seventh example. That is, in this example, the equalizing step is performed after the punching step. The other configurations and effects of the eighth example are the same as those of the seventh example.

[0217] The examples of the above-described embodiments can be combined as appropriate within the scope of not causing any contradiction. [Explanation of symbols]

[0218] 1 Hub unit bearing 2 outer ring 3. Hub 4a, 4b rolling elements 5a, 5b Outer ring raceway 6 Stationary Flange 7a, 7b Inner raceway 8 Rotating flange 9 Hub Wheel 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 barrel 27, 27a Bulkhead part 28, 28a Preliminary intermediate material 29, 29A Press processing equipment 29a, 29Aa dice 29a1 Large diameter part 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 wound 34 Recess 35, 35A, 35B Press processing equipment 35a Dice 35a1 Large diameter part 35a2 Small diameter section 35a3 Curved part 35b, 35Ab Dice Spin 35b1 Convex part 35c, 35Bc, 35Cc punch 35c1 convex part 35c2, 35Bc2, 35Cc2 Annular surface part 35Bc3, 35Cc3 Annular recess 36, 36a, 36b Annular convex portion 37, 37a, 37b, 37c spare cylindrical 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 section AP1 annular projection AX1 1st axis plane AX2 Second axis surface DP1 recess FR1, FRG Tsuba ROE radial outer end

Claims

1. 1. A method for manufacturing a bearing element, comprising: A first step of providing an upset workpiece; a second step of forming a recess, a flange, and a first axial surface in the workpiece by one or two plastic working steps, the recess having an axial depth relative to the first axial surface, and the flange extending radially outward; a third step of punching out the bottom of the recess in the workpiece; Equipped with 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 a radially outer end portion that is substantially equal to or greater than the first axial surface. A method for manufacturing a bearing element.

2. (a) the second step includes a step of simultaneously forming the recess, the flange, the first axial surface, and the annular protrusion in the workpiece using a first punch, and the annular protrusion has a shape that protrudes axially outward from the first axial surface at the radially outer end of the flange, or (b) the second step includes forming a preliminary recess in the workpiece using a second punch, and then simultaneously forming the recess, the flange, and the first axial surface in the workpiece using a third punch, and the simultaneous formation of the recess, the flange, and the first axial surface includes filling a corner of the flange at the radially outer end portion. The method of manufacturing a bearing element according to claim 1 .

3. the first punch has a first base portion, a first protrusion portion, a first punch surface including a tip region of the first protrusion portion, a second punch surface including an outer peripheral surface of the first protrusion portion, a third punch surface including an annular surface provided on the first base portion, a fourth punch surface which is a transition surface between the second punch surface and the third punch surface, and a step provided near a radial outer edge of the first punch surface and extending in a circumferential direction, A method for manufacturing a bearing element according to claim 2.

4. the second punch has a second base portion and a second protrusion portion; the third punch has a third base portion and a third protrusion portion, an axial length of the third protrusion of the third punch is smaller than that of the second protrusion of the second punch; an inclination of an outer peripheral surface of the second protrusion of the second punch with respect to a central axis is larger than an inclination of an outer peripheral surface of the third protrusion of the third punch with respect to a central axis; A method for manufacturing a bearing element according to claim 2.

5. the second punch has a second base portion and a second protrusion portion; the third punch has a third base portion and a third protrusion portion, an axial length of the third protrusion of the third punch is smaller than that of the second protrusion of the second punch; an outer diameter of the second base portion is substantially the same as an outer diameter of the third base portion; The average outer diameter of the second protrusions is larger than the average outer diameter of the third protrusions. A method for manufacturing a bearing element according to claim 2.

6. manufacturing a bearing element by a manufacturing method according to any one of claims 1 to 5; assembling a bearing using the bearing element; A method for manufacturing a bearing, comprising:

7. A method for manufacturing a mechanical device, comprising the step of manufacturing a bearing element by the manufacturing method according to any one of claims 1 to 5.

8. A method for manufacturing a vehicle, comprising the step of manufacturing a bearing element by the manufacturing method according to any one of claims 1 to 5.

9. A bearing comprising a bearing element having a mark produced by the manufacturing method according to any one of claims 1 to 5.

10. A main body has 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 the outer circumferential surface of the cylindrical body, a second outer circumferential surface which is the 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 peripheral surface in the vicinity of the second outer peripheral surface; a third pattern that is continuous along the transition surface in the vicinity of the transition surface; a plurality of continuous lines each continuous across the first pattern, the second pattern, and the third pattern; and an interval between the plurality of continuous lines in the third pattern is narrower than an interval between the plurality of continuous lines in the first pattern; the plurality of continuous lines have a plurality of corner elements arranged in the vicinity of the first corner, The plurality of corner elements have sharper corners closer to the first corner. Bearing element.

11. the metal flow lines of the main body have a fourth pattern including a plurality of line elements extending from the inner circumferential surface toward the transition surface in a direction oblique to a central axis of the main body; 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. A bearing element according to claim 10.

12. A bearing comprising a bearing element according to claim 10 or 11.

13. A mechanical device comprising the bearing according to claim 12.

14. A vehicle comprising the bearing according to claim 12.

15. A method for manufacturing a tubular member having an outer circumferential 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, an upsetting step of crushing a cylindrical raw material in an axial direction to obtain a disk-shaped raw material having an axial dimension smaller than the axial dimension of the raw material and an outer diameter larger than the outer diameter of the raw material; a molding step of subjecting the disk-shaped material to plastic processing to obtain an intermediate material including, on an outer circumferential surface thereof, an intermediate tubular portion having the large diameter portion, the small diameter portion, and the connecting surface portion, and a partition wall portion closing an end opening on the other axial side of the intermediate tubular portion; a punching step of punching out a radially inner portion of the intermediate cylindrical portion and the partition wall portion in an axial direction, A method for manufacturing a tubular member, wherein the axial dimension of the intermediate material or the axial dimension of a spare intermediate material obtained during the molding process is larger than the axial dimension of the tubular member.

16. the cylindrical member has an inner circumferential surface having an inclined surface portion provided at one end in the axial direction, the inner diameter of which increases toward the one end in the axial direction, and cylindrical surface portions provided at an intermediate portion in the axial direction and at the end on the other end in the axial direction; The method for manufacturing a tubular member according to claim 15 , wherein the intermediate tubular portion has the inclined surface portion at one axial end of the inner circumferential surface.

17. The molding step includes: a pre-forming step of subjecting the disk-shaped material to plastic working to obtain the preliminary intermediate material having a preliminary intermediate tubular portion and a partition wall portion that closes an end opening on the other axial side of the preliminary intermediate tubular portion; a post-forming step of crushing the preliminary intermediate material in the axial direction inside an inner peripheral surface of a die having a shape that conforms to the outer peripheral surface of the intermediate material to obtain the intermediate material, The method for manufacturing a tubular member according to claim 15, wherein the axial dimension of the preliminary intermediate material is larger than the axial dimension of the tubular member, and the axial dimension of the intermediate material is equal to the axial dimension of the tubular member.

18. 18. The method for manufacturing a tubular member according to claim 17, wherein in the pre-forming step, at least a radially outer portion of an end face on one axial side of the preliminary intermediate tubular portion is not brought into contact with a forming die for performing plastic working.

19. 18. The method for manufacturing a tubular member according to claim 17, wherein an outer diameter of one axial side portion of the preliminary intermediate tubular portion is slightly smaller than an outer diameter of the large diameter portion, and an outer diameter of the other axial side portion of the preliminary intermediate tubular portion is slightly smaller than an outer diameter of the small diameter portion.

20. the intermediate cylindrical portion has an annular protrusion protruding toward one axial direction at a radially outer end portion of an end surface on one axial direction side, the forming step is a step of obtaining the intermediate material by subjecting the disk-shaped material to plastic processing, the axial dimension of the intermediate material is larger than the axial dimension of the cylindrical member by an amount corresponding to the axial height of the annular convex portion; The method for manufacturing a tubular member according to claim 16 , further comprising, after the molding step, a removing step of removing the annular protrusion.

21. The method for manufacturing a tubular member according to claim 20 , wherein in the forming step, an end face on one axial side of the annular convex portion is not brought into contact with a forming die for performing plastic working.

22. 22. The method for manufacturing a tubular member according to claim 21, further comprising, prior to the removing step, a uniforming step of axially crushing the annular convex portion formed in the molding step to make the axial height of the annular convex portion uniform over the entire circumference.

23. A method for manufacturing a mechanical device including a cylindrical mechanical component having an outer circumferential 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, A method for manufacturing a mechanical device, comprising the step of manufacturing the mechanical part by performing a finishing process on a tubular member manufactured by the method for manufacturing a tubular member according to any one of claims 15 to 22.

24. 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 section, The method for manufacturing a mechanical device according to claim 23, wherein the mechanical device is a bearing device.

25. 25. The method for manufacturing a mechanical device according to claim 24, wherein the bearing device is a hub unit bearing for rotatably supporting a wheel of an automobile relative to a suspension device.

26. A method for manufacturing a vehicle including a mechanical device, comprising: A method for manufacturing a vehicle, comprising the step of manufacturing the mechanical device by the method for manufacturing the mechanical device according to claim 23.

27. A mechanical device including a cylindrical mechanical component 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, a metal flow groove inside the mechanical component has, in an axially intermediate portion of the mechanical component, an inclined portion inclined in a direction toward the radially outward side as it moves from the other axial side to the one axial side, The mechanical device, wherein the metal flow is denser in the inclined portion than in a portion existing around the inclined portion.

28. 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 section, 28. The mechanical device of claim 27, wherein the mechanical device is a bearing device.

29. 29. The machine of claim 28, wherein the bearing assembly is a hub unit bearing for rotatably supporting a wheel of a motor vehicle relative to a suspension system.

30. A vehicle including the mechanical device of any one of claims 27 to 28.

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