Method for manufacturing a cylindrical member, method for manufacturing a mechanical device, and method for manufacturing a vehicle

Abstract

To provide a manufacturing method advantageous in reduction of manufacturing cost and / or improvement of product quality.SOLUTION: A manufacturing method of a cylindrical member includes: an upset step; a molding step of obtaining an intermediate material (32b); a punching step of punching a radially inside portion of an intermediate cylindrical portion (30a) and a partition wall portion (31b) in the axial direction; and a removal step. The intermediate cylindrical portion (30a) includes an annular projection (36) projecting to one side in the axial direction, in the radially outer end portion of the end surface in the one side in the axial direction. An axial dimension of the intermediate material (32b) obtained in the molding step is larger than the axial dimension of the cylindrical member by an amount of the axial height of the annular projection (36). After the molding step, the annular projection (36) is removed in the removal step.SELECTED DRAWING: Figure 14

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a bearing element, a method for manufacturing a cylindrical 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 based on Japanese Patent Application No. 2023-135416 filed on August 23, 2023, and incorporates its content herein by reference.

Background Art

[0002] FIG. 21 shows an inner ring 100 constituting a radial angular ball bearing. The inner ring 100 includes an inner ring raceway 101 having a substantially quarter-circular arc cross-sectional shape at an axially intermediate portion of the outer peripheral surface. Further, the inner ring 100 has a cylindrical large-diameter portion (groove shoulder portion, flange portion) 102 on the outer peripheral surface of a portion on one axial side (the right side in FIG. 21), and a cylindrical small-diameter portion 103 on the outer peripheral surface of a portion on the other axial side (the left side in FIG. 21).

[0003] Cylindrical mechanical parts such as the inner ring of an angular ball bearing are manufactured by subjecting a metal material to forging and then performing finishing processes such as cutting and grinding.

[0004] Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-288505) describes a method for manufacturing two sets of inner rings and outer rings, each constituting a tapered roller bearing, from one cylindrical metal material. The method described in Patent Document 1 includes a step of subjecting the cylindrical metal material to hot forging to obtain a stepped cylindrical pre-processed material, and a step of separating the pre-processed material into two cylindrical post-processed materials having different diameters from each other. Further, the method described in Patent Document 1 includes a step of subjecting the post-processed material having a smaller diameter among the two post-processed materials to cold forging and separation processing to obtain two cylindrical members having different diameters from each other, and then performing finishing processing on these cylindrical members to obtain one set of inner ring and outer ring, and a step of subjecting the post-processed material having a larger diameter among the two post-processed materials to cold forging and separation processing to obtain two cylindrical members having different diameters from each other, and then performing finishing processing on these cylindrical members to obtain another set of inner ring and outer ring.

Prior Art Documents

Patent Document

[0005]

Patent Document 1

Summary of the Invention

Problems 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 the outer ring of each pair are substantially the same, the cylindrical members for obtaining these inner rings and outer rings can be manufactured with good material yield. However, the manufacturing method described in Patent Document 1 is not suitable for mass production of an inner ring used in combination with an outer ring having significantly different axial dimensions, such as the inner ring of a hub that supports a vehicle wheel with respect to a suspension device.

[0007] An aspect of the present invention aims to provide a manufacturing method that is advantageous for reducing manufacturing costs and / or improving product quality.

Means for Solving the Problems

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

[0009] In a method for manufacturing a cylindrical member according to an aspect of the present invention, the cylindrical member includes 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 portion, and an outer peripheral surface having a connecting surface portion connecting the large-diameter portion and the small-diameter portion. The method for manufacturing the cylindrical member includes a pressing step of pressing a columnar raw material in the axial direction to obtain a disk-shaped 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, and a forming step of subjecting the disk-shaped material to plastic working to obtain an intermediate material including an intermediate cylindrical portion having the large-diameter portion, the small-diameter portion, and the connecting surface portion on the outer peripheral surface, and a partition portion closing an end opening on the other axial side of the intermediate cylindrical portion, and a punching step of punching out a radially inner portion of the intermediate cylindrical portion and the partition portion in the axial direction. The axial dimension of the intermediate material or the axial dimension of a preliminary intermediate material obtained during the forming step is larger than the axial dimension of the cylindrical member.

[0010] A mechanical device according to an aspect of the present invention includes a cylindrical mechanical component having a large-diameter portion with a cylindrical surface provided on one axial side portion, a small-diameter portion with a cylindrical surface provided on the other axial side portion, and an outer peripheral surface having a connecting surface portion connecting the large-diameter portion and the small-diameter portion. The metal flow (fiber flow, forging streamline) inside the mechanical component has an inclined portion inclined in a direction toward the outer diameter as it goes from the other axial side to the one axial side at the axial middle portion of the mechanical component, and the metal flow is denser at the inclined portion than at portions existing around the inclined portion.

[0011] A method for manufacturing a bearing according to an aspect of the present invention includes a step of manufacturing a bearing element by the above manufacturing method and a step of assembling a bearing using the bearing element.

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

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

[0015] A bearing according to one aspect of the present invention includes a bearing element having a trace manufactured by the above 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 has a first axial surface that is one axial end surface, a second axial surface that is the other axial end surface, an inner peripheral surface of the cylindrical body, a first outer peripheral surface that is an outer peripheral surface of the cylindrical body, a second outer peripheral surface that is an outer peripheral surface of the flange, and a transition surface between the first outer peripheral surface and the second outer peripheral surface. The flange has a first angle between the first axial surface and the second outer peripheral surface and a second angle between the transition surface and the second outer peripheral surface. The metal flow of the main body has a first pattern that is continuous along the first axial surface in the vicinity of the first axial surface, 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, and a plurality of continuous lines that are continuous across the first pattern, the second pattern, and the third pattern. The interval between the plurality of continuous lines in the third pattern is narrower than the 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 angle. The plurality of corner elements have sharper angles the closer they are to the first angle.

Advantages of the Invention

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

Brief Description of the Drawings

[0018]

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MODE FOR CARRYING OUT THE INVENTION

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

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

[0021] In the first step, a workpiece (WP1) is prepared. A workpiece (WP1) having a predetermined shape formed by broaching is supplied, or a workpiece (WP1) having a predetermined shape is obtained by broaching 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 substantially cylindrical shape (substantially disc shape) including a first end face (ES1), a second end face (ES2), and an outer peripheral face (CS1). In one example, the first end face (ES1) is a relatively uniform flat face or a curved face. In other examples, the first end face (ES1) can have another shape. The second end face (ES2) is the face on the opposite side of the first end face (ES1). In one example, the peripheral face (CS1) of the workpiece (WP1) has a curved shape with a diameter that changes along the axial direction. In one example, the outer diameter (radial width) is set to be larger than the axial length (thickness, height) between the first end face (ES1) and the second end face (ES2) of the workpiece (WP1). When the axial length of the workpiece (WP1) is AL1 and the outer diameter is DM1, AL1 / DM1 can be set to, for example, about 1 / 2, 1 / 3, 1 / 4, 1 / 5, 1 / 6, 1 / 7, 1 / 8, 1 / 9, or 1 / 10 or less. The above numerical values are examples, and other numerical values can be applied in other examples. Alternatively and / or additionally, in the first step, a workpiece (WP1) having a deformed shape of the above shape or a shape other than the above can be prepared.

[0023] In one example, the broaching in the first step includes a pressing process (e.g., cold forging) that reduces the axial length (height) of the material and increases the outer diameter (radial width).

[0024] In one example, using a press device, a workpiece (WP1) having a shape in which raw materials (20, 20a) are axially compressed to deform a substantially cylindrical shape (substantially disc shape) or a shape different from the substantially cylindrical shape is formed. For example, the workpiece (WP1) obtained in the first step can have a thickness change (volume change) provided in a predetermined region in the radial direction. The thickness change can include a groove having a predetermined depth and extending in the circumferential direction, and / or a convex portion having a predetermined height and extending in the circumferential direction. In one example, for the workpiece (WP1) obtained in the first step, based on, for example, the form parameters of the final bearing element / cylindrical member and the processing parameters in other steps, etc., a processing tool is designed and the shape of the workpiece (WP1) at the initial stage is set. By such shape control at the initial stage, an improvement in material use efficiency (material yield) is achieved. Also, based on the flow pattern of the material, an improvement in the strength of the product is achieved.

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

[0026] The radial range of the radially outer end portion (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 range of the radially outer end portion (ROE) is EW1, EW1 / FD1 can be set to about 1 / 10, 1 / 12, 1 / 14, 1 / 16, 1 / 18, 1 / 20, 1 / 30, 1 / 40, or 1 / 50 or less. The above values are examples, and other values can be applied in other examples. Additionally and / or alternatively, in the second step, a deformed shape of the above shape or a shape other than the above can be set.

[0027] In a plurality of examples shown in FIGS. 14 - 20, the second step includes a step of simultaneously forming a recess (DP1), a flange (FR1), a first axial surface (AX1), and an annular protrusion (AP1) on a recessed 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 one punching process. The annular protrusion (AP1) has a shape that protrudes axially outward with respect to the first axial surface (AX1) at the radially outer end portion (ROE) of the flange (FR1).

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

[0029] In the plurality of examples shown in FIG. 3-13, the second step has a first plastic working for forming a preliminary recess (DP0) in the seated workpiece (WP1) using a second punch (PC2). Further, in the second step, after the first plastic working, a second plastic working is performed on the workpiece (WP2) in which the preliminary recess (DP0) is formed, using a third punch (PC3) to simultaneously form a recess (DP1), a flange (FR1), and a first axial surface (AX1). In the second plastic working, the simultaneous formation of the recess (DP1), the flange (FR1), and the first axial surface (AX1) includes filling the corner of the flange (FR1) at the radially outer end portion (ROE). For example, in the workpiece (WP3) after the second plastic working, the corner (edge shape) of the flange (FR1) has a substantially right-angled shape. The curved edge in the workpiece (WP2) after the first plastic working changes to a substantially right-angled edge in the workpiece (WP3) after the second plastic working. By the second plastic working with the third punch (PC3), a part of the material of the workpiece (WP2) flows radially outward, and a workpiece (WP3) is provided in which the thickness near the radially outer end increases.

[0030] In one example, the second punch (PC2) has a second base portion (P21) and a second protruding portion (P22), and the third punch (PC3) has a third base portion (P31) and a third protruding portion (P32). A preliminary depression (DP0) is formed in the workpiece by the second protruding portion (P22) of the second punch (PC2). A depression (DP1) is formed in the workpiece by the third protruding portion (P32) of the third punch (PC3). The second punch (PC2) has a fifth punch surface (P25) including the tip region of the second protruding portion (P22). The fifth punch surface (P25) corresponds to the bottom surface of the preliminary depression (DP0). The second punch (PC2) has a sixth punch surface (P26) including the outer peripheral surface of the second protruding portion (P22). The sixth punch surface (P26) corresponds to the inner wall surface of the preliminary depression (DP0). The third punch (PC3) has a seventh punch surface (P37) including the tip region of the third protruding portion (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 protruding portion (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 protruding portion (P32) of the third punch (PC3) is smaller than that of the second protruding portion (P22) of the second punch (PC2). Also, the inclination (θ11) of the outer peripheral surface (the sixth punch surface) (P26) of the second protruding portion (P22) in the second punch (PC2) with respect to the central axis is larger than the inclination (θ12) of the outer peripheral surface (P35) of the third protruding portion (P32) in the third punch (PC3) with respect to the central axis.

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

[0033] In one example, the fifth punch surface (P25) of the second punch (PC2) has a surface shape in which the surface height at the central portion is larger than that of other regions. The seventh punch surface (P37) of the third punch (PC3) has a uniform surface shape as a whole compared to the fifth punch surface (P25).

[0034] Based on the form parameters of the final bearing element (cylindrical member) and the processing parameters in other processes, etc., the second punch (PC2) and the third punch (PC3) are designed, and the shape of the workpiece (WP3) after plastic processing is set. By such shape control, improvement in material use efficiency (material yield) is achieved. Also, based on the flow pattern of the material, improvement in the strength of the product is achieved.

[0035] In one embodiment, the cylindrical member (21, 21a) has an outer peripheral surface including a large-diameter portion (22) having a cylindrical surface provided on one axial side, a small-diameter portion (23) having a cylindrical surface provided on the other axial side portion, and a connecting surface portion (24) connecting the large-diameter portion and the small-diameter portion. The manufacturing method of the cylindrical member (21, 21a) includes a pressing step of pressing a columnar raw material (20, 20a) in the axial direction to obtain a disk-shaped material (25, 25a, 25b) having an axial dimension smaller than the axial dimension of the raw material (20, 20a) and an outer diameter larger than the outer diameter of the raw material (20, 20a), a forming step of performing plastic working on the disk-shaped material (25, 25a, 25b) to obtain an intermediate cylindrical portion (30, 30a) having the large-diameter portion (22), the small-diameter portion (23), and the connecting surface portion (24) on the outer peripheral surface, and an intermediate material (32, 32a, 32b, 32c) including a partition 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 an inner side portion in the radial direction of the intermediate cylindrical portion (30, 30a) and the partition 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 preliminary intermediate material (28, 28a, 28b) obtained during the forming step is larger than the axial dimension of the cylindrical member (21, 21a).

[0036] In one example, the cylindrical member (21, 21a) can include an inclined surface portion (41) provided at an end on one axial side and having an inner diameter increasing toward one axial side, and an inner peripheral surface having a cylindrical surface portion (42) provided at an intermediate axial portion and an end on the other axial side. Further, the intermediate cylindrical portion (30, 30a) can have the inclined surface portion (41) at an end on one axial side of the inner peripheral surface.

[0037] In one example, the shaping process includes a pre-forming process of subjecting the disc-shaped material (25, 25a, 25b) to plastic working to obtain a preliminary intermediate material (28, 28a, 28b) having a preliminary intermediate cylindrical portion (26, 26a, 26b) and a partition portion (31, 31a, 31b) closing an end opening on the other axial side of the preliminary intermediate cylindrical portion (26, 26a, 26b), and a post-forming process of axially crushing the preliminary intermediate material (28, 28a, 28b) inside the inner peripheral surface of a die having a shape along 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 preliminary intermediate material (28, 28a, 28b) is larger than the axial dimension of the cylindrical member (21, 21a), and the axial dimension of the intermediate material (32, 32a, 32b, 32c) is equal to the axial dimension of the cylindrical member (21, 21a).

[0038] In one example, in the pre-forming process, 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 for plastic working.

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

[0040] In one example, the intermediate cylindrical portion (30, 30a) has an annular convex portion (36, 36a, 36b) protruding axially on the radially outer end portion of the end face on one axial side. For example, the shaping process is a process of subjecting the disc-shaped material (25, 25a, 25b) to plastic working to obtain the intermediate material (32, 32a, 32b, 32c), 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 after the shaping process, a removing process of removing the annular convex portion (36, 36a, 36b) is provided.

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

[0042] In one example, before the removing step, a flattening step can be provided in which the annular convex portions (36, 36a, 36b) formed in the forming step are axially crushed 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 cylindrical large-diameter portion (18) provided on one axial side, a cylindrical small-diameter portion (19) provided on the other axial side portion, and a cylindrical mechanical component (10) having an outer peripheral surface including a connecting surface portion (7a) connecting the large-diameter portion (18) and the small-diameter portion (19). The manufacturing method of the mechanical device includes a step of performing a finishing process on the cylindrical member (21, 21a) manufactured by the above-described manufacturing method of the cylindrical member to manufacture the mechanical component (10).

[0044] In one example, the mechanical component is an inner ring (10), the connecting surface portion of the mechanical component is constituted by an inner ring raceway (7a) having an arcuate 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 vehicle wheel with respect to a suspension device.

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

[0047] In one embodiment, the mechanical device (1) includes a cylindrical large-diameter portion (18) provided on one axial side portion, a cylindrical small-diameter portion (19) provided on the other axial side portion, and a cylindrical mechanical component (10) having an outer peripheral surface including a connecting surface portion (7a) connecting the large-diameter portion and the small-diameter portion. The metal flow (fiber flow, forging streamline) inside the mechanical component has an inclined portion (Tp) inclined in a direction toward the radially outer side as it goes from the other axial side to the one axial side at the axial intermediate portion of the mechanical component, and the metal flow is denser at the inclined portion (Tp) than the portions existing around the inclined portion (Tp).

[0048] In one example, the mechanical component is an inner ring (10), the connecting surface portion of the mechanical component is constituted by an inner ring raceway (7a) having an arcuate 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 vehicle wheel with respect to a suspension device.

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

[0051] According to the manufacturing method of the above cylindrical member, it is possible to suppress the manufacturing cost of a mechanical component made from a cylindrical member having a cylindrical large-diameter portion provided on one axial side portion, a cylindrical small-diameter portion provided on the other axial side portion, and an outer peripheral surface including a connecting surface portion connecting the large-diameter portion and the small-diameter portion.

[0052] In one embodiment, as shown in the examples of FIGS. 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. Further, the body (10) has an inner peripheral surface (IS1) of the cylindrical body (TBB), a first outer peripheral surface (CS1) that is the outer peripheral surface of the cylindrical body (TBB), a second outer peripheral surface (CS2) that is the outer peripheral surface of the flange (FRG), and a transition surface (CS3) between the first outer peripheral surface (CS1) and the second outer peripheral surface (CS2). The flange (FRG) has a first angle (FE1) between the first axial surface (AS1) and the second outer peripheral surface (CS2) and a second angle (FE2) between the transition surface (CS3) and the second outer peripheral surface (CS2).

[0053] In one embodiment, the bearing element (cylindrical member) has traces produced by the above manufacturing method. In one example, the traces are metal flow (metal fiber flow, fibrous metal structure, forging streamline) observed in the cross-section of the bearing element (cylindrical member). In FIGS. 2, 5, 7, 9, and 15, an example of the metal flow in the axial cross-section (axial section) of the bearing element (cylindrical member) and its manufacturing process is shown. The traces can also be confirmed based on tissue analysis and / or structural analysis, which is different from the analysis based on metal flow.

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

[0055] As shown in the examples of FIGS. 2, 7, and 15, the intervals between the plurality of continuous lines (CL1, CL2, CL3) in the third pattern (PA3) are narrower than the intervals between the plurality of continuous lines (CL1, CL2, CL3) in the first pattern (PA1). The plurality of continuous lines (CL1, CL2, CL3) have a plurality of corner elements (CE1, CE2, CE3) arranged in the vicinity of the first corner (FE1). The plurality of corner elements (CE1, CE2, CE3) have sharper corners the closer they are 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 FIGS. 7 and 15, at least one of the plurality of corner elements (CE1, CE2, CE3) has a protruding shape protruding toward the first corner (FE1). At least one of the plurality of corner elements (CE1, CE2, CE3) has a first curvature (CV1) convex toward the first corner (FE1) and a second curvature (CV2) convex toward the inside of the first corner (FE1). For example, the first curvature (CV1) and the second curvature (CV2) are arranged continuously.

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

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

[0059] In one embodiment, the bearing includes the above-described bearing element, which is advantageous for reducing the cost of the bearing.

[0060] In one embodiment, the machine includes the above-described bearing, which is advantageous for reducing the cost of the machine.

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

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

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

[0064] The method for manufacturing the cylindrical member 104 includes a pressing-in step, a forming step, and a punching step, each of which is a step by hot forging.

[0065] In the pressing-in step, a cylindrical raw material, which is a single metal material, is axially crushed to obtain a disk-shaped material (workpiece) 105 having a smaller axial dimension and a larger outer diameter than the raw material, as shown in FIG. 22(a).

[0066] In the shaping process, plastic working such as forward and backward extrusion is performed on the disk-shaped material 105 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 the outer peripheral surface shape of the cylindrical member 104 and the same axial dimension as the axial dimension of the cylindrical member 104, and a partition portion 108 that closes the end opening on the other axial side among the end portions on one axial side (the upper side in Fig. 22(b)) and the end portions on the other axial side (the lower side in Fig. 22(b)) of the intermediate cylindrical portion 107.

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

[0068] Although such a manufacturing method can efficiently obtain the cylindrical member 104 from a cylindrical metal material with a small number of man-hours, there is room for improvement in the following aspects.

[0069] That is, since the cylindrical member 104 is made by hot forging, an oxide film (black skin) is formed on its surface. If such an oxide film remains on the surface of the finished inner ring 100, it becomes difficult to ensure the required shape accuracy and surface roughness accuracy of the inner ring 100. Therefore, it is necessary to ensure enough allowance for the cylindrical member 104 to remove the surface oxide film by finishing.

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

[0071] In that case, in the intermediate material 106 and the cylindrical member 104, the radially outer end portion of the end surface on one axial side has a shape with insufficient material, for example, as shown by the dashed line α in Fig. 23 (in the illustrated example, a shape that retreats in the direction toward the other axial side as it goes radially outward).

[0072] As a result, there may be a problem that it becomes impossible to secure enough margin at the radially outer end of the end face on one axial side of the cylindrical member 104 to remove the oxide film by finishing. Since the cylindrical member in which such a problem has occurred is to be discarded, it causes an increase in the manufacturing cost of the inner ring 100.

[0073] As a method for preventing the occurrence of the problems described above, a method can be considered in which the processing load when performing forward and backward extrusion processing on the disk-shaped material 105 is increased so that the meat surely reaches the radially outer end of the end on one axial side of the forming space of the intermediate material 106.

[0074] However, in this method, the load on the forming die increases, the processing apparatus becomes larger, and the life of the forming die becomes shorter, so that the manufacturing cost of the inner ring 100 increases.

[0075] As another method for solving the problems described above, a method can be considered in which the volume of the raw material is increased to increase the overall thickness of the margin provided in the cylindrical member 104. According to this method, even when the radially outer end of the end face on one axial side of the cylindrical member 104 has a shape with a lack of meat as indicated by the chain line α in FIG. 23, it becomes easy to secure enough margin at the radially outer end of the end face on one axial side of the cylindrical member 104 to remove the oxide film by finishing.

[0076] However, in this method, the amount of margin removed by finishing increases, that is, the yield when manufacturing the inner ring 100 deteriorates, so that the manufacturing cost of the inner ring 100 increases.

[0077] Hereinafter, embodiments will be described. In each embodiment, it is possible to suppress the manufacturing cost of a mechanical part made of a cylindrical member having an outer peripheral surface having a cylindrical large-diameter portion provided on one axial side, a cylindrical small-diameter portion provided on the other axial side portion, and a connecting surface portion connecting the large-diameter portion and the small-diameter portion.

[0078] [First Embodiment] The first embodiment will be described with reference to FIGS. 1 to 7.

[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. 1.

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

[0081] The manufacturing method of the cylindrical member can also be applied to a cylindrical member for obtaining various mechanical parts constituting a mechanical device such as a machine tool or a vehicle. In this case, finishing processes such as cutting and grinding can be performed on the cylindrical member to manufacture the mechanical parts.

[0082] The material of the cylindrical member is not particularly limited as long as it is a metal material capable of hot forging, and various metal materials such as ferroalloys such as bearing steel, aluminum alloys, and copper alloys can be adopted.

[0083] Regarding the hub unit bearing 1, the inner side in the axial direction is the right side in FIG. 1 which is the center side in the vehicle width direction when assembled to the vehicle, and the outer side in the axial direction is the left side in FIG. 1 which is the outer side in the vehicle width direction 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 a double row of outer ring raceways 5a, 5b on its inner peripheral surface. In this example, each of the outer ring raceways 5a, 5b is of the angular type and has a substantially quarter-circular cross-sectional shape.

[0086] Furthermore, the outer ring 2 has a stationary flange 6 that projects radially outward at its axial intermediate portion. The stationary flange 6 is a portion used to support and fix the outer ring 2 to the knuckle of the suspension device.

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

[0088] Furthermore, the hub 3 has a rotating flange 8 that projects radially outward at a portion located axially outside the outer ring 2. The rotating flange 8 is a portion for connecting and fixing the wheel and the rotating body for braking 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 axial intermediate portion of the hub ring 9. Also, the rotating flange 8 is provided on the axially outer portion of the hub ring 9. The hub ring 9 has a small-diameter step portion 11 at its axially inner end, where the outer diameter is smaller than the portion adjacent axially outside, and the inner ring 10 is externally fitted, and has a step surface 12 facing axially inward at the axially outer end of the small-diameter step portion 11. Since the hub unit bearing 1 in this example is for a driving wheel, the hub ring 9 has a spline hole 13 at its radially central portion for spline-engaging a spline shaft portion that constitutes a drive shaft member.

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

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

[0093] In this example, the inner peripheral surface of the inner ring 10 has an inclined surface portion 39 provided at an end portion on the axially inner side which is one axially side, and whose inner diameter increases as it goes axially inward, and a cylindrical surface portion 40 provided at an axially intermediate portion and an end portion on the axially outer side which is the other axially side. In this example, the inclined surface portion 39 has a substantially quarter-circular arc cross-sectional shape. In one example, the inclined surface portion can also be configured by a conical surface having a linear generatrix shape.

[0094] In this example, both end surfaces on both axially sides of the inner ring 10 are configured by flat surfaces orthogonal to the axial direction.

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

[0096] The hub 3 is formed by externally fitting and fixing the inner ring 10 to the small-diameter step portion 11 of the hub ring 9, and bringing the axially outer end surface of the inner ring 10 into contact with the step surface 12 of the hub ring 9.

[0097] The hub unit bearing is also applicable to a hub unit bearing provided with a caulking portion for pressing against the axially inner surface of the inner ring at the axially inner end portion of the hub ring, a hub unit bearing in which the axially outer inner-ring raceway is provided on the outer peripheral surface of another inner ring externally fitted to the hub ring, and a hub unit bearing for a driven wheel having no spline hole at the radially central portion.

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

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

[0100] In the hub unit bearing 1 of this example, the openings on both axial sides of the rolling element installation space 14 existing between the inner peripheral surface of the outer ring 2 and the outer peripheral surface of the hub 3 are respectively blocked by the seal devices 15a and 15b. Thereby, it is possible to prevent foreign matters 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 to prevent the lubricating grease enclosed in the rolling element installation space 14 from leaking to the outside.

[0101] In the illustrated example, the seal device 15a on the inner axial side includes a seal ring 16 fitted inside the inner peripheral surface of the inner end portion of the outer ring 2 in the axial direction, and a slinger 17 fitted outside the large-diameter portion 18 of the inner ring 10, and is constituted by a combined seal ring in which the tip portions of a plurality of seal lips constituting the seal ring 16 are in sliding contact with the surface of the slinger 17. That is, the large-diameter portion 18 of the inner ring 10 is used as a fitting portion for fitting the slinger 17.

[0102] Next, a method for manufacturing the inner ring (bearing element) 10 in this example will be described with reference to FIGS. 3 to 7.

[0103] In the following description regarding this example, unless otherwise specified, the axial direction refers to the axial direction of the workpiece. One side in the axial direction is the upper side in FIGS. 3 to 7, and the other side in the axial direction is the lower side in FIGS. 3 to 7. In FIGS. 3 to 7, the axial direction of each member shown coincides with the vertical direction. However, the vertical direction in FIGS. 3 to 7 does not necessarily coincide with the vertical direction (vertical direction) during processing. That is, the vertical direction in FIGS. 3 to 7 can be made to coincide with the horizontal direction, or can be made to coincide with a direction inclined with respect to either the vertical direction (vertical direction) or the horizontal direction.

[0104] The manufacturing method of the inner ring 10 in this example includes a main process of subjecting a cylindrical raw material 20 as shown in FIG. 3(a) to multi-stage plastic working by a manufacturing method of one aspect to obtain a cylindrical member 21 as shown in FIG. 3(d), and a finishing process of subjecting the cylindrical member 21 to finishing processes such as cutting and grinding to obtain the final shape of the inner ring 10.

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

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

[0107] The inner peripheral surface of the cylindrical member 21 has an inclined surface portion (curved surface portion) 41 provided at one end in the axial direction and having an inner diameter that increases as it goes inward in the axial direction, and a cylindrical surface portion 42 provided at the middle portion in the axial direction and the other end in the axial direction. The inclined surface portion 41 has an arcuate cross-sectional shape 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 replacement amount. 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 replacement amount.

[0108] The end faces on both sides in the axial direction of the cylindrical member 21 are constituted by flat surfaces orthogonal to the axial direction. The end face on one side in the axial direction of the cylindrical member 21 is located on the one side in the axial direction by the replacement amount more than the end face on one side in the axial direction of the inner ring 10, and the end face on the other side in the axial direction of the cylindrical member 21 is located on the other side in the axial direction by the replacement amount more than the end face on the other side in the axial direction of the inner ring 10.

[0109] The replacement thickness is not particularly limited, but it is necessary to be at least a thickness capable of removing the oxide film, that is, equal to or greater than the thickness of the oxide film. Assuming that the thickness of the oxide film is 0.2 mm to 0.3 mm, the replacement thickness can be, for example, 0.3 mm or more and 1.0 mm or less, preferably 0.3 mm or more and 0.5 mm or less. The above numerical values are examples and are not limited thereto.

[0110] This step includes a pressing-in step, a forming step, and a punching step.

[0111] In the pressing-in step, the columnar raw material 20 is axially crushed to obtain a disk-shaped 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 Fig. 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 arcuate cross-sectional shape (generatrix shape) in which the outer diameter at the central portion in the axial direction is larger than the outer diameters at both ends in the axial direction. In this example, the outer diameter of the disk-shaped material 25, more specifically, the outer diameter of the central portion in the axial direction, which is the maximum 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 cylindrical member 21. The outer diameters of the both ends in the axial direction, which are the minimum diameter portions of the disk-shaped material 25, are slightly smaller than the outer diameter of the small-diameter portion 23 of the cylindrical member 21.

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

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

[0116] In the pre-forming process, backward extrusion, which is a plastic working, is performed on the disk-shaped material 25 to obtain a cup-shaped preliminary intermediate material 28 including a preliminary intermediate cylindrical portion 26 having an axial dimension larger than the axial dimension of the cylindrical member 21 as shown in FIG. 3(b), and a partition 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 preliminary intermediate cylindrical portion is larger than the axial dimension of the cylindrical member and the partition portion closes the end opening on the other axial side of the preliminary intermediate cylindrical portion, the shapes of the preliminary intermediate cylindrical portion and the partition portion are not particularly limited.

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

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

[0121] One end face of the preliminary intermediate cylindrical portion 26 on one axial side has a substantially arc-shaped cross-sectional shape that is convex on one axial side. That is, the radially inner portion of the end face of the preliminary intermediate cylindrical portion 26 on one axial side is constituted by a convex curved surface that inclines in the direction toward the other axial side as it goes radially inward, and the radially outer portion of the end face of the preliminary intermediate cylindrical portion 26 on one axial side is constituted by a convex curved surface that inclines in the direction toward the other axial side as it goes radially outward.

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

[0123] In this example, one axial side surface of the partition portion 27 is constituted by a substantially conical surface that inclines in the direction toward the other axial side as it goes radially inward.

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

[0125] Additionally and / or alternatively, a recess recessed axially can be provided at the radially central portion of the end face on the other axial side of the preliminary intermediate material. By providing this recess, after the forming of the preliminary intermediate material, the operation of separating the end face on the other axial side of the preliminary intermediate material from the forming die can be facilitated.

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

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

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

[0129] The die pin 29b is disposed without radial play on the inner diameter side of the small-diameter portion 29a2 of the die 29a. One axial end surface, which is the tip end surface of the die pin 29b, has a shape along the other axial end surface of the preliminary intermediate material 28.

[0130] The punch 29c is supported so as to be axially movable with respect to a support base (not shown) of the press working device 29.

[0131] The punch 29c has a convex portion (projection portion) 29c1 at the center of the tip end surface (the end surface on the other axial side). The outer peripheral surface of the convex portion 29c1 has a shape along 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 peripheral surface of the preliminary intermediate cylindrical portion 26 located on one axial side of the partition portion 27. The other axial end surface, which is the tip end surface of the convex portion 29c1, has a shape along the side surface on one axial side of the partition portion 27.

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

[0133] When obtaining the preliminary intermediate material 28 by subjecting the disk-shaped material 25 to backward extrusion using the press working device 29, first, as shown in Fig. 5(a), the disk-shaped material 25 is placed on the end face on one axial side of the die spindle 29b.

[0134] Next, the punch 29c is moved to the other axial side, and the central portion in the radial direction of the disk-shaped material 25 is pressed by the end face on the other axial side of the convex portion 29c1 of the punch 29c. As a result, as shown in Figs. 5(a) to 5(b) and Fig. 4(a), while the central portion of the disk-shaped material 25 is axially crushed between the end face on the other axial side of the convex portion 29c1 and the end face on one axial side of the die spindle 29b, the thickness of the outer portion in the radial direction of the disk-shaped material 25 is moved to the portion between the outer peripheral surface of the convex portion 29c1 and the inner peripheral surface of the die 29a, and the preliminary intermediate material 28 is obtained.

[0135] In this example, in the pre-forming step, at least a part in the radial direction of the end face on one axial side of the preliminary intermediate cylindrical portion 26 is not brought into contact with the forming die for the backward extrusion process.

[0136] More specifically, in this example, as shown in Fig. 4(b), the outer portion in the radial direction 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. For this reason, in this example, compared with the case where the entire end face on one axial side of the preliminary intermediate cylindrical portion 26 is brought into contact with the forming die for the backward extrusion process, the processing load in the pre-forming step can be suppressed. As a result, the durability of the die 29a, the die spindle 29b, and the punch 29c can be ensured, and the manufacturing cost of the inner ring 10 can be suppressed.

[0137] In the pre-forming step, the entire end face on one axial side of the preliminary intermediate cylindrical portion may or may not be brought into contact with the forming die.

[0138] In the previous pre-forming step, as shown in FIG. 6, inside the inner peripheral surface of a die 35a having a shape along the outer peripheral surface of an intermediate material 32, a preliminary intermediate material 28 is axially crushed to obtain a cup-shaped intermediate material 32 having an axial dimension equal to the axial dimension of the cylindrical member 21 as shown in FIG. 3(c).

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

[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 the same outer peripheral surface shape as 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 end faces on both axial sides of the intermediate cylindrical portion 30 have the same shape as the end faces on both axial sides of the cylindrical member 21, that is, a flat surface shape orthogonal to the axial direction.

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

[0143] The axial thickness of the partition portion 31 is greater than the axial thickness of the partition portion 27 of the preliminary intermediate material 28. In this example, one side surface of the partition portion 31 in the axial direction is constituted by a flat surface orthogonal to the axial direction. The other side surface of the partition portion 31 in the axial direction has a concave portion 34 that is recessed axially in the radially central portion. Among the other side surface of the partition portion 31 in the axial direction, the portion located radially outside the concave portion 34 is constituted by a flat surface existing in the same virtual plane as the end surface on the other axial side of the intermediate cylinder portion 30.

[0144] That is, in this example, the end surface on the other axial side of the intermediate material 32, which is constituted by the end surface on the other axial side of the intermediate cylinder portion 30 and the other side surface of the partition portion 31 in the axial direction, has a concave portion 34 in the radially central portion, and the portion located radially outside the concave portion 34 is constituted by a single flat surface orthogonal to the axial direction. In this example, due to the provision of such a concave portion 34, after the intermediate material 32 is formed, the operation of separating the end surface on the other axial side of the intermediate material 32 from the forming die can be facilitated. Alternatively, it is also possible to omit providing a concave portion on the end surface on the other axial side of the intermediate material.

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

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

[0147] The die 35a has an inner peripheral surface having a shape along the outer peripheral surface of the intermediate material 32, that is, the outer peripheral surface of the intermediate cylindrical portion 30. Specifically, the inner peripheral surface of the die 35a has a stepped cylindrical shape formed by connecting a large-diameter portion 35a1 provided on one axial side and a small-diameter portion 35a2 provided on the other axial side with a curved surface portion 35a3. The large-diameter portion 35a1 has a shape along the large-diameter portion 22 of the intermediate cylindrical portion 30, the small-diameter portion 35a2 has a shape along the small-diameter portion 23 of the intermediate cylindrical portion 30, and the curved surface portion 35a3 has a shape along the connecting surface portion 24 of the intermediate cylindrical 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 radial play. One end face on the axial side, which is the tip end face of the die pin 35b, has a shape along the other end face on the axial side of the intermediate material 32. Specifically, one end face on the axial side of the die pin 35b has a convex portion 35b1 having an outer surface shape along the inner surface shape of the concave portion 34 of the intermediate material 32 at the radially central portion. Among the one end face on the axial side of the die pin 35b, the radially outer portion, which is the portion located radially outside the convex portion 35b1, is constituted by an annular flat surface orthogonal to the central axis of the die pin 35b.

[0149] The punch 35c is supported so as to be axially movable with respect to a support base (not shown) of the press working device 35.

[0150] The punch 35c has a convex portion 35c1 at the center of the tip end face (the end face on the other axial side). The outer peripheral surface of the convex portion 35c1 has a shape along the portion of the inner peripheral surface of the intermediate cylindrical portion 30 located on one axial side of the partition portion 31. The end face on the other axial side, which is the tip end face of the convex portion 35c1, has a shape along the side face on one axial side of the partition portion 31.

[0151] Furthermore, the punch 35c has an annular surface portion 35c2 bent radially outward from the end on one axial side of the outer peripheral surface of the convex portion 35c1. The annular surface portion 35c2 is constituted by a flat surface orthogonal to the central axis of the punch 35c.

[0152] When the preliminary intermediate material 28 is processed by the pressing device 35 to obtain the intermediate material 32, first, as shown in Fig. 7(a), the preliminary intermediate material 28 is placed on the end face on one axial side of the die spindle 35b, more specifically, on the end face on one axial side of the convex portion 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 radial play, 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 radial play.

[0153] Next, the punch 35c is moved to the other axial side, and the preliminary intermediate cylindrical portion 26 of the preliminary intermediate material 28 is pressed from one axial side by the annular surface portion 35c2 of the punch 35c. Further, 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 outer radial portion of the end face on one axial side of the die spindle 35b becomes the same as the axial dimension of the cylindrical member 21.

[0154] Thereby, as shown in Figs. 7(a) to 7(b) and Fig. 6, while the preliminary intermediate cylindrical portion 26 is axially crushed between the annular surface portion 35c2 of the punch 35c and the end face on one axial side of the die spindle 35b, the thickness of the preliminary intermediate cylindrical portion 26 and the partition portion 27 is moved in a direction to fill the gap in the space surrounded by the die 35a, the die spindle 35b, and the punch 35c, that is, the forming space of the intermediate material 32. Thereby, the intermediate material 32 is obtained.

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

[0156] Therefore, in this example, in the post-forming process, even if the processing load is not excessively large, the meat can surely reach up to the radially outer end of the end 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 cylindrical portion 30 from having a meatless shape as indicated by the chain line α in FIG. 23, and the cross-sectional shape of the radially outer end of the end face can be made substantially right-angled.

[0157] In this example, at the end stage of the processing in the post-forming process, 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 merely come into contact as flat surfaces, but are in concavo-convex engagement based on the presence of the concave portion 34 and the convex portion 35b1. For this reason, the sticking 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 is relaxed, and after the intermediate material 32 is formed, the operation 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 can be facilitated.

[0158] In the punching process, the radially inner part and the partition wall part 31 of the intermediate cylindrical portion 30 constituting the intermediate material 32 are punched axially to obtain a cylindrical member 21 as shown in FIG. 3(d).

[0159] The shape of the cylindrical member 21 has the same shape as the intermediate cylindrical portion 30 except for the radially inner part. For this reason, in this example, the cross-sectional shape of the radially outer end of the end face on one axial side of the cylindrical member 21 after the punching process can also be a substantially right-angled cross-section. That is, it is possible to prevent the radially outer end of the end face on one axial side of the cylindrical member 21 from having a meatless shape as indicated by the chain line α in FIG. 23.

[0160] In this example, in the punching process, since the partition wall part 31 having the covering scar 33 and the concave portion 34 is removed, the covering scar 33 and the concave portion 34 do not remain on the cylindrical member 21.

[0161] In the finishing process, finishing processes such as cutting and grinding are performed on the entire surface of the cylindrical member 21. Thereby, the oxide film existing on the entire surface of the cylindrical member 21 is removed, and by ensuring the shape accuracy and surface roughness accuracy required for each location on the entire surface of the cylindrical member 21, the inner ring 10 is obtained.

[0162] In this example, in the preforming process, 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. For this reason, it is not necessary to excessively increase the processing load in the preforming process. Further, in the post-forming process, from the beginning of the processing, the material for forming the end face on one axial side of the intermediate cylindrical portion 30 exists in the vicinity of the annular surface portion 35c2 of the punch 35c. For this reason, it is not necessary to excessively increase the processing load in the post-forming process.

[0163] That is, according to the manufacturing method of this example, even when ensuring enough allowance to remove the oxide film by finishing up to the radially outer end portion of the end face on one axial side of the cylindrical member 21, it is not necessary to increase the processing load in the preforming process and the post-forming process. For this reason, the load applied to the forming die used in the preforming process and the post-forming process can be kept low, and the durability of the forming die can be sufficiently ensured. Also, since it is not necessary to excessively increase the volume of the raw material 20 and overall increase the allowance provided for the cylindrical member 21, the yield can be improved. As a result, the cylindrical member 21 can be manufactured at low cost. Consequently, the manufacturing cost of the inner ring 10 can be suppressed.

[0164] In this example, since no covering scratches 33 remain on the cylindrical member 21, no covering scratches 33 remain on the inner ring 10 obtained by performing finishing on the cylindrical member 21. Therefore, it is easy to ensure the quality of the inner ring 10.

[0165] In this example, as shown in FIG. 2, the metal flow Fm inside the inner ring 10 obtained in the finishing process has an inclined portion Tp that inclines in a direction toward the outer diameter side as it goes from the other axial side toward the one axial side at the intermediate portion in the axial direction of the inner ring 10. The metal flow Fm inside the inner ring 10 is denser at the inclined portion Tp than the portions existing around the inclined portion Tp.

[0166] The reason for this is that in the preforming process of the manufacturing method of the cylindrical member 21, as shown in FIGS. 5(a) to 5(b), backward extrusion processing is performed on the disk-shaped material 25 to form a preliminary intermediate cylindrical portion 26 having a larger axial dimension than the cylindrical member 21. That is, in this example, due to the influence of the backward extrusion processing at this time, a part of the half portion on the other axial side of the preliminary intermediate cylindrical portion 26 (portion B in FIGS. 5(b) and 7(a)) inclines in a direction toward the outer diameter side as it goes from the other axial side toward the one axial side, and a metal flow Fm that is denser than the surrounding portions is formed. Then, the metal flow Fm of this portion is slightly deformed as shown in portion C of FIG. 7(b) in the post-forming process, and becomes the inclined portion Tp by being partially removed in the punching process and the finishing process.

[0167] That is, if the inclined portion Tp exists in the metal flow Fm inside the inner ring 10, it can be estimated that the inner ring 10 is obtained by the manufacturing method of this example.

[0168] [Second Embodiment] The second embodiment will be described with reference to FIGS. 8 to 9.

[0169] Among the manufacturing method of the inner ring 10 (refer to FIG. 1) in this example, the post-forming process, the punching process, and the finishing process in this step are the same as the post-forming process, the punching process, and the finishing process in this step of the first embodiment. Hereinafter, the fitting process and the preforming process in this step among the manufacturing method of the inner ring 10 in this example will be described.

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

[0171] In the pre-forming step, a plastic working such as forward and backward extrusion is performed on the disk-shaped material 25a by 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, to obtain a pre-intermediate material 28 having a pre-intermediate cylindrical part 26 and a partition part 27 as shown in Fig. 8(b).

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

[0173] Next, the punch 29c is moved to the other axial side, and the central part in the radial direction of the disk-shaped material 25a is pressed by the end face on the other axial side of the convex part 29c1 of the punch 29c. As a result, as shown from Fig. 9(a) to Fig. 9(b), the thickness of the central part of the disk-shaped material 25a is moved to the other axial side, and while being axially crushed between the end face on the other axial side of the convex part 29c1 and the end face on one axial side of the die pin 29b, it is moved to the part between the outer peripheral surface of the convex part 29c1 and the inner peripheral surface of the die 29a. At the same time, the thickness of the radially outer part of the disk-shaped material 25 is radially crushed between the outer peripheral surface of the convex part 29c1 and the inner peripheral surface of the die 29a, and is moved radially in one direction between the outer peripheral surface of the convex part 29c1 and the inner peripheral surface of the die 29a. Thereby, the pre-intermediate material 28 is obtained.

[0174] Also 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. Therefore, the processing load in the pre-forming step can be suppressed.

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

[0176] Also in this example, the metal flow Fm inside the preliminary intermediate material 28 is in the same manner as in the first embodiment. Therefore, the metal flow Fm inside the completed inner ring 10 is also in the same manner as in the first embodiment. Other configurations and operational effects of the second embodiment are the same as those of the first embodiment.

[0177] [Third Embodiment] The third embodiment will be described with reference to Figs. 10 to 11.

[0178] Among the manufacturing methods of the inner ring 10 (see Fig. 1) in this example, the pressing-in step, the post-forming step, the punching step, and the finishing step in this process are the same as the pressing-in step, the post-forming step, the punching step, and the finishing step in the corresponding process of the first embodiment. Hereinafter, the pre-forming step in this process among the manufacturing methods of the inner ring 10 in this example will be described.

[0179] In this example, among the preliminary intermediate cylindrical portion 26a and the partition portion 27 that constitute the preliminary intermediate material 28a obtained in the pre-forming step, the outer peripheral surface of the preliminary intermediate cylindrical portion 26a is constituted by a cylindrical surface whose outer diameter does not change in the axial direction. The inner peripheral surface of the preliminary intermediate cylindrical portion 26a is constituted by a tapered surface with a small inclination angle with respect to the axial direction, where the inner diameter increases as it goes toward one axial side. That is, the preliminary intermediate cylindrical 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)). That is, 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 that constitutes the press working device 35 (see Fig. 6) used in the post-forming process.

[0181] In this example, as shown in Fig. 11, in the press working device 29A used in the pre-forming process, the inner peripheral surface of the die 29Aa has a cylindrical surface shape along the outer peripheral surface of the preliminary intermediate cylindrical portion 26a. The outer peripheral surface of the convex portion 29Ac1 of the punch 29Ac has a tapered surface shape along the inner peripheral surface of the preliminary intermediate cylindrical portion 26a. Other configurations and effects of the third embodiment are the same as those of the first embodiment.

[0182] [Fourth Embodiment] The fourth embodiment will be described with reference to Figs. 12 to 13.

[0183] Among the manufacturing methods of the inner ring 10 (see Fig. 1) in this example, the pressing-in process, punching process, and finishing process in this step are the same as the pressing-in process, punching process, and finishing process in the corresponding step of the first embodiment. Hereinafter, the pre-forming process and post-forming process in this step among the manufacturing methods of the inner ring 10 in this example will be described.

[0184] In this example, as shown in Fig. 12(b), among the preliminary intermediate cylindrical portion 26b and the partition portion 27a that constitute the preliminary intermediate blank 28b obtained in the pre-forming process, the preliminary intermediate cylindrical portion 26b has a substantially cylindrical shape, similar to the third embodiment. That is, the outer peripheral surface of the preliminary intermediate cylindrical portion 26b is constituted by 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 constituted by a tapered surface with a small inclination angle with respect to the axial direction, where the inner diameter increases as it goes toward one side in the axial direction.

[0185] In this example, the outer diameter of the preliminary intermediate cylindrical portion 26b is the same as the outer diameter of the large-diameter portion 22 of the cylindrical member 21 (see Fig. 10(d)), or is slightly smaller than the outer diameter of the large-diameter portion 22. That is, the outer diameter of the preliminary intermediate cylindrical portion 26b is the same as 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 process, or is slightly smaller than the inner diameter of the large-diameter portion 35a1.

[0186] In this example, as shown in Figs. 13(a) and 13(b), one axial end face on the axial direction one side of the die pin 35Ab that constitutes the press working device 35A used in the post-forming process is constituted by a single flat surface orthogonal to the axial direction.

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

[0188] Next, the punch 35c is moved to the other axial side, and the preliminary intermediate cylindrical portion 26 of the preliminary intermediate material 28 is pressed from the one axial side by the annular surface portion 35c2 of the punch 35c. Further, 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 one axial end face of the die pin 35Ab becomes the same as the axial dimension of the cylindrical member 21 (see Fig. 12(d)).

[0189] As a result, as shown in FIGS. 13(a) to 13(b), the preliminary intermediate material 28b is plastically deformed to obtain the intermediate material 32a. In this example, the obtained intermediate material 32a has an annular covering defect 33a generated by the processing in the post-forming process at the axial intermediate part of the radial intermediate part of the partition wall part 31a. The diameter of the circumscribed circle of the covering defect 33a is smaller than the inner diameter of the cylindrical member 21. Also in the case of this example, since the partition wall part 31a having the covering defect 33a is punched out in the punching process, the covering defect 33a does not remain in the obtained cylindrical member 21. Other configurations and effects of the fourth embodiment are the same as those of the first embodiment or the third embodiment.

[0190] [Fifth Embodiment] The fifth embodiment will be described with reference to FIGS. 14 to 15.

[0191] The manufacturing method of the inner ring 10 (see FIG. 1) in this example includes a pressing-in process, a forming process, a punching process, and a removing process.

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

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

[0194] In the forming process, plastic working such as forward and backward extrusion is performed on the disk-shaped material 25b to obtain an intermediate material 32b including an intermediate cylindrical part 30a and a partition wall part 31b that closes the end opening on the other axial side of the intermediate cylindrical part 30a, as shown in FIG. 14(b).

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

[0196] The radial width dimension Wa and the axial height H of the annular convex portion 36 can be arbitrarily set. The radial width dimension Wa of the annular convex portion 36 is preferably set in the range of 15% to 35% of the radial width dimension Wb of the end portion on one side in the axial direction of the finally obtained cylindrical member 21a. The axial height H of the annular convex portion 36 is preferably made larger than the thickness of the oxide film (black skin) formed on the finally obtained cylindrical member 21a in this step. For example, it is preferably set in the range of 3 to 5 times the thickness of the oxide film. The above numerical values are only examples and are not limited thereto.

[0197] In this example, the axial dimension of the intermediate material 32b is larger than the axial dimension of the finally obtained cylindrical member 21a by the axial height H of the annular convex portion 36.

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

[0199] When the disk-shaped material 25b is processed by the press working device 35B to obtain the intermediate material 32b, first, the radially outer edge portion of the end surface on the other side in the axial direction of the disk-shaped material 25b is engaged with the end portion on one side in the axial direction of the curved surface portion 35a3 of the die 35a, so that the disk-shaped material 25b is held inside the radially inner portion of the large-diameter portion 35a1 of the die 35a.

[0200] Next, move the punch 35Bc to the other axial side, and press the central portion in the radial direction of the disc-shaped material 25b with the end face on the other axial side of the convex portion 35c1 of the punch 35Bc. As a result, the thickness of the central portion of the disc-shaped material 25b is moved to the other axial side, and while being axially crushed between the end face on the other axial side of the convex portion 35c1 and the end face on one axial side of the die spindle 35b, it is moved to the portion between the outer peripheral surface of the convex portion 35c1 and the inner peripheral surface of the die 35a. At the same time, the thickness of the radially outer portion of the disc-shaped material 25b is radially crushed between the outer peripheral surface of the convex portion 35c1 and the inner peripheral surface of the die 35a, and is moved radially toward one side between the outer peripheral surface of the convex portion 35c1 and the inner peripheral surface of the die 35a. Thereby, an intermediate material 32b is obtained.

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

[0202] In this example, in the forming process, since an annular protrusion 36 that protrudes axially is formed at the radially outer end of the end on one axial side of the intermediate cylindrical portion 30a, it is possible to prevent the radially outer end of the end face on one axial side of the intermediate cylindrical portion 30a from having a cut-out shape as indicated by the chain line α in FIG. 23.

[0203] In the punching process, the radially inner portion and the partition portion 31b of the intermediate cylindrical portion 30a that constitute the intermediate material 32b are axially punched to obtain a preliminary cylindrical member 37 as shown in FIG. 14(c).

[0204] The shape of the preliminary cylindrical member 37 has the same shape as the portion of the intermediate cylindrical portion 30a excluding the radially inner portion. Therefore, in this example, it is possible to prevent the radially outer end of the end face on one axial side of the preliminary cylindrical member 37 obtained in the punching process from having a cut-out shape as indicated by the chain line α in FIG. 23.

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

[0206] In this example, in order to obtain the cylindrical member 21a in this way, it is possible to prevent the radially outer end portion of the end face on one axial side of the cylindrical member 21a from having a cut-out shape as indicated by the chain line α in FIG. 23. Also in the case of this example, finish machining is performed on the cylindrical member 21a obtained in this way in the finishing process to obtain the inner ring 10.

[0207] In this example, in order to prevent the shape of the radially outer end portion of the end face on one axial side of the cylindrical member 21a from having a cut-out shape as indicated by the chain line α in FIG. 23, the volume of the raw material 20a is increased by the amount corresponding to the formation of the annular convex portion 36. However, the increase amount of the volume can be made sufficiently small compared with the case where the thickness of the replacement provided for the cylindrical member is increased as a whole. Therefore, the cylindrical member 21a can be manufactured at low cost. Other configurations and operational effects of the fifth embodiment are the same as those of the first embodiment.

[0208] [Sixth Embodiment] The sixth embodiment will be described with reference to FIGS. 16 to 17.

[0209] Among the manufacturing methods of the inner ring 10 (see FIG. 1) in this example, the press-fitting process, the punching process, the removing process, and the finishing process are the same as the press-fitting process, the punching process, the removing process, and the finishing process of the fifth embodiment. Hereinafter, among the manufacturing methods of the inner ring 10 in this example, the forming process will be described.

[0210] In this example, in the forming process, the end face on one axial side of the annular convex portion 36a constituting the intermediate material 32c is not brought into contact with a forming die for performing plastic working such as forward and backward extrusion working. More specifically, as shown in FIG. 17, the end face on one axial side of the annular convex portion 36a is not brought into contact with the annular concave portion 35Cc3 of the annular surface portion 35Cc2 provided on the punch 35Cc. For this reason, in this example, compared with the first embodiment in which the end face on one axial side of the annular convex portion 36 is brought into contact with a forming die for performing plastic working, the processing load in the second process can be suppressed. As a result, since the die 35a, the die spindle 35b, and the punch 35Cc have a long service life, the manufacturing cost of the inner ring 10 can be suppressed. Other configurations and operational effects of the sixth embodiment are the same as those of the fifth embodiment.

[0211] [Seventh Embodiment] The seventh embodiment will be described with reference to FIGS. 18 to 19.

[0212] Among the manufacturing methods of the inner ring 10 (see FIG. 1) in this example, the fitting process (see FIG. 18(a)), the forming process (see FIG. 18(b)), the punching process (see FIG. 18(d)), the removing process, and the finishing process are the same as the fitting process (see FIG. 16(a)), the forming process (see FIG. 16(b)), the punching process (see FIG. 16(c)), the removing process, and the finishing process in the sixth embodiment. The manufacturing method of the inner ring 10 in this example includes a uniformizing process (see FIG. 16(c)) for making the axial heights of the annular convex portions 36a uniform before the removing process.

[0213] In this example, similar to the sixth embodiment, in the forming process, as shown in FIG. 17, the end face on one axial side of the annular convex portion 36a is not brought into contact with the annular concave portion 35Cc3 of the punch 35Cc. For this reason, the shape of the end face on one axial side of the annular convex portion 36a does not follow the shape of the bottom surface of the annular concave portion 35Cc3, and the axial height of the annular convex portion 36a may not be uniform over the entire circumference. When the axial height of the annular convex portion 36a is not uniform over the entire circumference, in the removing process, cutting of the annular convex portion 36a becomes intermittent, making the cutting difficult.

[0214] Therefore, in this example, in the equalization process before the punching process, as shown in FIG. 19, the tip surface of the punch 38 constituting the press working device is pressed against the end surface on one axial side of the annular convex portion 36a, thereby crushing the annular convex portion 36a in the axial direction. As a result, an annular convex portion 36b having a uniform axial height over the entire circumference is formed. Thereby, in the finishing process, the cutting of the annular convex portion 36b becomes continuous, and the cutting becomes easier. Other configurations and operational effects of the seventh embodiment are the same as those of the sixth embodiment.

[0215] [Eighth Embodiment] The eighth embodiment will be described with reference to FIG. 20.

[0216] In the method for manufacturing the inner ring 10 (see FIG. 1) of this example, the order of the equalization process and the punching process is reversed from that in the case of the seventh embodiment. That is, in this example, the equalization process is performed after the punching process. Other configurations and operational effects of the eighth embodiment are the same as those of the seventh embodiment.

[0217] Each of the above-described examples of the embodiments can be implemented by appropriately combining them within a range that does not cause contradictions.

Description of Reference Numerals

[0218] 1 Hub unit bearing 2 Outer ring 3 Hub 4a, 4b Rolling elements 5a, 5b Outer ring raceways 6 Stationary flange 7a, 7b Inner ring raceways 8 Rotating flange 9 Hub ring 10 Inner ring 11 Small-diameter stepped portion 12 Step surface 13 Spline hole 14 Rolling element installation space 15a, 15b Seal device 16 Seal ring 17 Slinger 18 Large-diameter portion 19 Small-diameter part 20, 20a Raw material 21, 21a Cylindrical member 22, 22a Large-diameter part 23, 23a Small-diameter part 24, 24a Connecting surface part 25, 25a, 25b Disk-shaped material 26, 26a, 26b Preliminary intermediate cylindrical part 27, 27a Partition part 28, 28a Preliminary intermediate material 29, 29A Press working device 29a, 29Aa Die 29a1 Large-diameter part 29a2 Small-diameter part 29a3 Curved surface part 29b Die spindle 29c, 29Ac Punch 29c1, 29Ac1 Convex part 29c2 Annular surface part 30, 30a Intermediate cylindrical part 31, 31a, 31b Partition part 32, 32a, 32b, 32c, 32d Intermediate material 33, 33a Covering scratch 34 Concave part 35, 35A, 35B Press working device 35a Die 35a1 Large-diameter part 35a2 Small-diameter part 35a3 Curved surface part 35b, 35Ab Die spindle 35b1 Convex part 35c, 35Bc, 35Cc Punch 35c1 Convex part 35c2, 35Bc2, 35Cc2 Annular surface part 35Bc3, 35Cc3 Annular concave part 36, 36a, 36b Annular convex part 37, 37a, 37b, 37c Preliminary cylindrical member 38 Punch 39 Inclined surface part 40 Cylindrical surface part 41 Inclined surface part 42 Cylindrical surface 100 Inner ring 101 Inner ring track 102 Large-diameter part 103 Small-diameter part 104 Cylindrical member 105 Disk-shaped material 106 Intermediate material 107 Intermediate cylindrical part 108 Partition part AP1 Annular protrusion AX1 First axial surface AX2 Second axial surface DP1 Depression FR1, FRG Flange ROE Radial outer end

Claims

1. A method for manufacturing a tubular member having an outer circumferential surface having 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, comprising: a swaging step of axially crushing a cylindrical raw material 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 an intermediate tubular portion having the large diameter portion, the small diameter portion, and the connecting surface portion on an outer circumferential surface thereof, and a partition 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, an axial dimension of the intermediate material or an axial dimension of a preliminary intermediate material obtained during the forming process is larger than an axial dimension of the tubular member; the cylindrical member has an inner circumferential surface having an inclined surface portion provided at one axial end portion, the inner diameter of which increases toward the one axial end portion, and a cylindrical surface portion provided at an axial intermediate portion and at the other axial end portion; 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 performing plastic working on the disk-shaped material, an axial dimension of the intermediate material is larger than an axial dimension of the cylindrical member by an axial height of the annular protrusion; a removing step of removing the annular protrusion after the molding step, In the forming step, an end face on one axial side of the annular protrusion is not brought into contact with a forming die for performing plastic working, a uniformizing step, which is performed before the removing step, of uniforming the axial height of the annular convex portion over the entire circumference by axially crushing the annular convex portion formed in the molding step. A method for manufacturing a tubular member.

2. A method for manufacturing a mechanical device including a cylindrical mechanical component having an outer circumferential surface with a large diameter portion having a cylindrical surface provided on one axial side portion, a small diameter portion having a cylindrical surface provided on the other axial side portion, and a connection surface portion connecting the large diameter portion and the small diameter portion, A method for manufacturing a mechanical device, comprising the step of: subjecting a tubular member manufactured by the method for manufacturing a tubular member according to claim 1 to a finish process, thereby manufacturing the mechanical part.

3. The mechanical component is an inner ring, and the connection surface portion of the mechanical component is configured by an inner ring raceway having an arc-shaped cross-sectional shape, The method for manufacturing a mechanical device according to claim 2 , wherein the mechanical device is a bearing device.

4. 4. The method for manufacturing a mechanical device according to claim 3, wherein the bearing device is a hub unit bearing for rotatably supporting a wheel of an automobile relative to a suspension device.

5. A method for manufacturing a vehicle including a mechanical device, comprising: A method for manufacturing a vehicle, comprising the step of manufacturing a mechanical device by the method for manufacturing a mechanical device according to claim 2 .

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