Hub unit bearing and method for manufacturing a hub unit bearing

Abstract

To provide a hub unit bearing which can improve durability with respect to a stress amplitude caused by a rotation flexure load, with a simple structure, and a production method of the hub unit bearing.SOLUTION: A hub unit bearing comprises: an outer ring member which has a plurality of rows of outer ring orbital planes on its inner peripheral surface; an inner ring member which has a plurality of rows of inner ring orbital planes on its outer peripheral surface; and rolling bodies, the plurality of rolling bodies being provided on each row, between each outer ring orbital plane and each inner ring orbital plane. The inner ring member comprises: a hub ring; and an inner ring which is externally fitted and fixed to a small diameter step part formed on an inboard side end part of the hub ring. On a radial center part of an outboard side end surface of the hub ring, a bottomed recess part which is open toward the outboard side, is provided. On a radial center part of the bottom surface on an inboard side of the recess part, padding is protruded toward the outboard side.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a hub unit bearing and a method for manufacturing the hub unit bearing.

Background Art

[0002] Conventionally, a hub unit bearing that rotatably supports a vehicle wheel with respect to a suspension device has been known. In a pilot portion of a hub ring that constitutes the hub unit bearing, a recess (cavity) is formed by forging in order to reduce weight and project a hub flange radially outward. In recent years, the demand for weight reduction of the hub unit bearing, which is the sprung weight, has increased, and the number of hub unit bearings having a recess with a large axial dimension that reaches the inboard side of the hub flange has been increasing.

[0003] FIG. 7 is a cross-sectional view of a hub unit bearing described in Patent Document 1. Patent Document 1 discloses a hub unit bearing as shown in FIG. 7 as a solution to such problems. This hub unit bearing includes an inner member 151, an outer member 152, and a double row of balls 153, 153 that are rotatably accommodated between the two members 151, 152. The inner member 151 is composed of a hub ring 154 and an inner ring 155 press-fitted into the hub ring 154 with a predetermined interference.

[0004] The hub ring 154 integrally has a wheel mounting flange 156 for attaching a wheel (not shown) to one end portion. On the outer peripheral surface of the hub ring 154, one inner raceway surface 154a of the double row and a small-diameter step portion 154b formed via a shaft-like portion 157 extending in the axial direction from the inner raceway surface 154a are provided. On the other hand, the inner ring 155 has the other inner raceway surface 155a of the double row formed on the outer peripheral surface, is press-fitted into the small-diameter step portion 154b of the hub ring 154, and is axially fixed by a caulking portion 158 formed by plastically deforming the end portion of the small-diameter step portion 154b.

[0005] The outer member 152 integrally has a body mounting flange 152b on its outer circumference for attachment to a knuckle (not shown), and an outer rolling surface 152a facing the inner rolling surface 154a of the hub wheel 154, and the other outer rolling surface 152a facing the inner rolling surface 155a of the inner wheel 155 are integrally formed on its inner circumference. Double rows of balls 153, 153 are housed between these two rolling surfaces and are held to roll freely by retainers 159, 159. In addition, a seal 160 is fitted to seal the annular space between the outer member 152 and the hub wheel 154, and a bottomed short cylindrical cover 161 formed by press molding from a steel plate is fitted to the inner circumferential surface of the end of the outer member 152.

[0006] Here, the hub wheel 154 has a solid structure portion 162 formed only in the portion corresponding to the fitting surface A of the inner ring 155 of the small-diameter stepped portion 154b, and the rest is a hollow structure portion (recess, cavity) 163. That is, the end faces 162a and 162b of the solid structure portion 162 are provided on a plane perpendicular to the axial direction passing through both ends of the fitting surface A, and a new hollow structure portion 163 is also provided on the inner end side of the solid structure portion 162. The hollow structure portion 163 has the maximum volume possible while ensuring the rigidity of the hub wheel 154, and aims to achieve weight reduction while ensuring the strength and rigidity of the hub wheel 154.

[0007] In the hub unit bearing shown in Figure 7, weight can be reduced as the volume of the hollow structure (recess) 163 of the hub ring 154 increases. However, the heat treatment distortion generated when the contour of the hub ring 154 is high-frequency hardened acts as tensile residual stress on the hollow structure 163. Therefore, if the stress amplitude due to rotational bending load acts on this hollow structure 163, there is a risk of cracks forming in the hollow structure 163 of the hub ring. In addition, the material flow during forging is poor, reducing forgeability, and there is a risk of reduced die life and forging defects occurring during forging.

[0008] Figure 8 is a cross-sectional view of the hub unit bearing described in Patent Document 2. Figure 9 is a schematic cross-sectional view of the hub ring 104 in the hub unit bearing described in Patent Document 2 when stress relief holes 114 and 115 are not provided.

[0009] Figure 9 shows the fiber flow (forging flow lines) F, which is the flow of the fibrous metal structure observed when a metal material is forged. Since forging is carried out by applying compressive force from both the left and right directions to a rod-shaped member extending in the left-right direction in the figure, as shown in Figure 9, the area near the center B of the bottom surface of the recess (recess, cavity) 113 of the hub wheel 104 is weaker in terms of strength because the fiber flow F is difficult to form there. Furthermore, tensile residual stress is likely to occur near the center B of the bottom surface. Therefore, when a stress amplitude due to a rotational bending load is applied, cracks may occur near the center B of the bottom surface.

[0010] Therefore, in order to address the above-mentioned problems, the hub unit bearing described in Patent Document 2 has first and second stress-relieving holes 114 and 115 formed on the bottom surface of the recess 113 of the hub ring 104, as shown in Figure 8. More specifically, the hub unit bearing of Patent Document 2 comprises an inner member 101 and an outer member 102, and a double row of rolling elements (balls) 103, 103 that are rotatably housed in a cage 109 between the two members 101 and 102. The inner member 101 consists of a hub ring 104 and an inner ring 105 that is press-fitted into the hub ring 104 and fixed by a crimping portion 108.

[0011] The base 106a of the wheel mounting flange 106 of the hub wheel 104 is formed as an arcuate surface. A predetermined hardened layer 110 with a surface hardness in the range of 58 to 64 HRC is formed on the hub wheel 104 by high-frequency induction hardening, extending from the base 106a to the small-diameter stepped portion 104b. A mortar-shaped recess (recess, cavity) 113 is formed at the end of the hub wheel 104 by forging, and the depth of this recess 113 is set to approximately the position corresponding to the base 106a. After high-frequency induction hardening of the hub wheel 104, a first stress relief hole 114 is formed by machining, which is tapered from the recess 113 toward the inner board and has a depth set between two rows of rolling elements 103, and a second stress relief hole 115 has a smaller diameter than the first stress relief hole 114. The tip of this second stress-relieving hole 115 is secured near the position of the shoulder portion 104c, which abuts against the small end face of the inner ring 105. By forming these stress-relieving holes 114 and 115, the aim is to reduce cyclic stress compared to a design without this type of stress-relieving hole. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Japanese Patent Publication No. 2007-269066 [Patent Document 2] Japanese Patent Publication No. 2011-189771 [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] The stress-relieving holes 114 and 115 described in the aforementioned Patent Document 2 are formed in the center of the bottom surface of the recess (recess, cavity) 113 by cutting with a lathe or drill. However, this method requires a drilling process, which tends to be less efficient and more costly than turning. Furthermore, since this drilling process must be performed with a long tool such as a drill, cutting efficiency is further reduced, making it unavoidable that processing costs will increase.

[0014] This invention has been made in view of the above circumstances, and aims to provide a hub unit bearing and a method for manufacturing a hub unit bearing that can improve durability against stress amplitude due to rotational bending load with a simple configuration. [Means for solving the problem]

[0015] The above objective of the present invention is achieved by the following configuration. (1) An outer ring member having double rows of outer ring raceway surfaces on its inner circumferential surface, An inner ring member having double rows of inner ring raceway surfaces on its outer circumferential surface, Between each of the outer ring raceway surfaces and each of the inner ring raceway surfaces, multiple rolling elements are provided for each row, A hub unit bearing equipped with, The inner ring member comprises a hub ring and an inner ring fixed to a small-diameter stepped portion formed on the inboard side end of the hub ring. A recessed area with a bottom that opens toward the outboard side is provided at the radial center of the outboard end face of the hub wheel. A raised section is provided at the radial center of the bottom surface on the inboard side of the recess, projecting toward the outboard side. A hub unit bearing characterized by the following features. (2) A method for manufacturing a hub unit bearing as described in (1), The material that will become the hub ring is inserted between the first mold on the outboard side and the second mold on the inboard side and forged, thereby forming the build-up material of the hub ring. A method for manufacturing a hub unit bearing, characterized by the following: (3) The radial center of the inboard side surface of the first type is provided with a recess that is recessed toward the outboard side, The recess forms the build-up material of the hub wheel. (2) A method for manufacturing a hub unit bearing as described in (2). (4) The radial center portion of the first type is provided with a through hole that penetrates in the axial direction, The through hole forms the build-up material of the hub ring. (2) A method for manufacturing a hub unit bearing as described in (2).

Advantages of the Invention

[0016] According to the present invention, it is possible to provide a hub unit bearing and a method for manufacturing the hub unit bearing, which have a simple structure and can improve durability against stress amplitude due to rotational bending load.

Brief Description of the Drawings

[0017] [Figure 1] It is a cross-sectional view of a hub unit bearing according to the first embodiment. [Figure 2] It is a diagram for explaining a method for manufacturing the hub unit bearing of the first embodiment. [Figure 3] It is a diagram showing the fiber flow of a hub ring. [Figure 4] It is a cross-sectional view of a hub unit bearing according to the second embodiment. [Figure 5] It is a diagram for explaining a method for manufacturing the hub unit bearing of the second embodiment. [Figure 6] It is a diagram showing the fiber flow of a hub ring. [Figure 7] It is a cross-sectional view of a hub unit bearing described in Patent Document 1. [Figure 8] It is a cross-sectional view of a hub unit bearing described in Patent Document 2. [Figure 9] It is a diagram showing a schematic cross-section of a hub ring when no stress relaxation hole is provided in the hub unit bearing described in Patent Document 2.

Modes for Carrying Out the Invention

[0018] [First Embodiment] FIG. 1 is a cross-sectional view of a hub unit bearing 10 according to the first embodiment of the present invention.

[0019] In this specification, "inboard side" refers to the vehicle body side of the hub unit bearing 10 when it is mounted on the vehicle body, which is the right side in Figure 1 and is indicated as "IN" in the figure. "Outboard side" refers to the wheel side of the hub unit bearing 10 when it is mounted on the vehicle body, which is the left side in Figure 1 and is indicated as "OUT" in the figure. "Axial direction" refers to the direction in which the rotation axis O of the hub unit bearing 10 extends, which is the left-right direction in Figure 1. "Radially outward" refers to the direction away from the rotation axis O. "Radially inward" refers to the direction approaching the rotation axis O. "Circumferential direction" refers to the direction of rotation around the rotation axis O.

[0020] As shown in Figure 1, the hub unit bearing 10 is for the driven wheel and comprises an outer ring member 11 with double rows of outer ring raceway surfaces 11a, 11a formed on its inner circumferential surface 11b, an inner ring member (hub ring 12 and inner ring 13) with double rows of inner ring raceway surfaces 12a, 13a formed on its outer circumferential surfaces 12b, 13b, and a plurality of rolling elements 14 arranged in multiples for each row between the double rows of outer ring raceway surfaces 11a, 11a and the double rows of inner ring raceway surfaces 12a, 13a.

[0021] The double-row outer ring raceway surfaces 11a, 11a formed on the inner circumferential surface 11b of the outer ring member 11 are spaced apart from each other in the axial direction. A flange 11c is formed on the outer circumferential surface of the outer ring member 11, which is coupled and fixed to a knuckle (not shown) that constitutes the suspension system.

[0022] The inner ring member comprises a hub ring 12 and an inner ring 13 that is separate from the hub ring 12. Inner ring raceway surfaces 12a and 13a are formed on the outer circumferential surface 12b of the hub ring 12 and the outer circumferential surface 13b of the inner ring 13, respectively. The inner ring raceway surfaces 12a and 13a of the hub ring 12 and the inner ring 13 are radially opposite to the outer ring raceway surfaces 11a and 11a of the outer ring member 11, respectively.

[0023] Multiple rolling elements 14 are arranged at equal intervals in the circumferential direction on a double-row track consisting of outer ring raceway surfaces 11a, 11a and inner ring raceway surfaces 12a, 13a.

[0024] Multiple rolling elements 14 contact the outer ring raceway surfaces 11a, 11a and the inner ring raceway surfaces 12a, 13a at predetermined contact angles, forming a back-to-back (DB) bearing. This allows the hub ring 12 and the inner ring 13 to rotate relative to the outer ring member 11.

[0025] A small-diameter stepped portion 12c is formed at the inboard end of the hub wheel 12. The inner ring 13 is fitted onto the small-diameter stepped portion 12c. After the inner ring 13 is fitted onto the small-diameter stepped portion 12c of the hub wheel 12, the end of the small-diameter stepped portion 12c is crimped radially outward, thereby fixing the inner ring 13 to the hub wheel 12. The crimping process presses the inner ring 13, providing the appropriate preload.

[0026] In this embodiment, the hub unit bearing 10 is for the driven wheel, and therefore the hub wheel 12 is solid and does not have a through hole that penetrates axially.

[0027] The hub wheel 12 has a cylindrical pilot portion 20 provided at the outboard end of the hub wheel 12, and a flange portion 18 positioned adjacent to the inboard side of the pilot portion 20 to support the wheel. The flange portion 18 is disc-shaped or star-shaped, extending radially outward from the outer circumferential surface 12b of the hub wheel 12. Multiple through holes 18a are provided in the flange portion 18 at equal intervals in the circumferential direction, penetrating in the axial direction. Multiple hub bolts 19 for fastening a wheel and brake rotor (not shown) are fixed to each through hole 18a.

[0028] On the inboard side of the outer ring member 11, a sensor-equipped cap 25 is provided, along with an outboard side seal 24, to seal the internal bearing space 10a. The sensor-equipped cap 25 is made of synthetic resin and has a bottomed cylindrical shape, and includes a cap body 25a with a sensor element molded and fixed to it, and a metal ring 25b molded and fixed to the cap body 25a. The cap body 25a is provided with a hole 25c for inserting a sensor cable plug. The cap 25 is fixed to the outer ring member 11 by fitting the outboard side of the metal ring 25b into the inboard side end of the inner circumferential surface 11b of the outer ring member 11.

[0029] An encoder 26 is fixed to the inboard end of the outer circumferential surface 13b of the inner ring 13. The encoder 26 comprises a core metal 27 and an encoder body 28.

[0030] The core metal 27 is made by press-forming a magnetic metal sheet such as a cold-rolled steel sheet, and is configured in an annular shape. The core metal 27 has a fitting cylindrical portion 27a, an outward-facing flange portion 27b, and a support plate portion 27c.

[0031] The fitting cylinder portion 27a is cylindrical in shape, and its outboard side is fitted onto the inboard end of the outer peripheral surface 13b of the inner ring 13 by interference fit. The outward-facing flange portion 27b bends at a right angle radially outward from the outboard end of the fitting cylinder portion 27a. The support plate portion 27c bends at a right angle radially inward from the inboard end of the fitting cylinder portion 27a.

[0032] The encoder body 28 is made of magnetic rubber (rubber magnet) formed by dispersing magnetic powder such as ferrite in rubber such as acrylonitrile butadiene rubber (NBR) or acrylic rubber (ACM), and is constructed in an annular shape. It is supported and fixed around the entire circumference on the inboard side of the support plate portion 27c. The encoder body 28 has a detection portion on the inboard side surface in which north poles and south poles are arranged alternately and at equal pitches in the circumferential direction.

[0033] As the encoder 26 rotates with the wheel, the south pole and north pole located on the detected part of the encoder body 28 alternately pass near the detection part of the sensor-equipped cap 25. As a result, changes in the density of magnetic flux entering and leaving the detected part and passing through the detection part are detected, and consequently, the rotation speed of the wheel is detected.

[0034] A recessed area 15 with a bottom that opens toward the outboard side is provided at the radial center of the outboard-side end face 12d of the hub wheel 12. The recessed area 15 is formed such that its inner diameter decreases toward the inboard side.

[0035] In this embodiment, the inboard end 15b of the recess 15 lies at position C in the axial direction between the outboard inner ring raceway surface 12a of the double-row inner ring raceway surfaces 12a and 13a and the flange portion 18. That is, compared to the second embodiment described later, the inboard end 15b is located on the outboard side, and the axial dimension (depth) of the recess 15 is smaller.

[0036] A build-up 16 is provided at the radial center of the inboard-side bottom surface 15a of the recess 15, that is, in the portion of the bottom surface 15a that overlaps with the rotation axis O, projecting toward the outboard side. The build-up 16 is composed of a curved surface whose outer diameter decreases as it approaches the outboard side. The outboard-side end (tip) of the build-up 16 is located on the rotation axis O.

[0037] The shape of the build-up material 16 does not need to be limited to the illustrated example; it can be arbitrarily modified as long as it protrudes from the radial center of the bottom surface 15a (on the rotation axis O) toward the outboard side.

[0038] Figure 2 is a diagram illustrating the manufacturing method of the hub unit bearing according to the first embodiment. As shown in Figure 2, the build-up material 16 of the hub ring 12 is formed by inserting the material that will become the hub ring 12 between the lower die 31 (first die) on the outboard side and the upper die 33 (second die) on the inboard side and performing die forging.

[0039] The outboard side surface 33a of the upper die 33 (lower side surface in Figure 2) has a shape that corresponds to the surface shape of the inboard side (upper side in Figure 2) of the hub wheel 12. Note that the hub wheel 12 shown in Figure 2 is in a state before the end of the small-diameter stepped portion 12c is crimped radially outward, so the end of the small-diameter stepped portion 12c is flat. An axial gap S is interposed between the end of this small-diameter stepped portion 12c and the outboard side surface 33a of the upper die 33.

[0040] The inboard side surface 31a (upper side surface in Figure 2) of the lower mold 31 has a shape that corresponds to the surface shape of the outboard side (lower side in Figure 2) of the hub wheel 12. The radial center of the lower mold 31 (center in the left-right direction in Figure 2) has a protrusion 31b that projects toward the inboard side. The shape of this protrusion 31b matches the shape of the recess 15 of the hub wheel 12. In particular, the radial center of the inboard side surface 31a of the protrusion 31b of the lower mold 31 is provided with a recess 32 that is recessed toward the outboard side (lower side in Figure 2). The groove shape of this recess 32 matches the shape of the build-up 16 provided on the bottom surface 15a of the recess 15 of the hub wheel 12.

[0041] By performing hot forging using the lower die 31 and upper die 33 as described above, a recess 15 can be formed in the hub wheel 12. As a result of the formation of the recess 15, the flange portion 18 is formed to protrude radially outward. In the forging method shown in Figure 2, semi-closed forging is employed to reduce the stress on the recess 32 provided at the tip of the convex portion 31b of the lower die 31. Therefore, after the flange portion 18 and the recess 15 are formed, a flash (burr) 17 is formed around the flange portion 18. Thus, the forged material for the hub wheel 12 is completed by removing the flash 17 in a subsequent trimming process. Note that forging is not limited to hot forging; cold forging may also be used if processing is possible, and the same effects as described above can be obtained in that case as well.

[0042] Figure 3 shows the fiber flow F of the hub wheel 12. As shown in Figure 3, in the hub wheel 12 obtained by the method described above, the inflection point of the fiber flow F moves toward the outer board side due to the buildup 16, approaching the vicinity of the radial center of the bottom surface 15a of the recess 15 (in the case without the buildup 16), and the direction of the fiber flow F also approaches the direction perpendicular to the rotation axis O, thereby further improving durability against stress amplitude due to rotational bending load. Furthermore, the tensile strength of the radial center of the bottom surface 15a of the recess 15 is improved by the buildup 16, and the tensile residual stress is relieved, thereby improving durability against stress amplitude due to rotational bending load.

[0043] As described above, according to this embodiment, there is no need for processes such as creating stress relief holes by machining as in the conventional technology, and the durability against stress amplitude due to rotational bending load can be improved with a simple configuration in which build-up material 16 is simultaneously created by forging when creating the recess 15.

[0044] In this embodiment, the terms "lower mold 31" and "upper mold 33" are merely convenient ways of referring to the two molds as a pair, and do not indicate the vertical orientation of the molded product during forging.

[0045] [Second Embodiment] Figure 4 is a cross-sectional view of a hub unit bearing 10 according to a second embodiment of the present invention. The hub unit bearing 10 of this embodiment differs from that of the first embodiment in the configuration of the hub ring 12. For components of the hub unit bearing 10 of this embodiment that are the same as those of the first embodiment, the same reference numerals are used to omit or simplify their description.

[0046] In the hub wheel 12 of the first embodiment, the inboard end 15b of the recess 15 was located at position C in the axial direction between the outboard inner ring raceway surface 12a of the double-row inner ring raceway surfaces 12a, 13a and the flange portion 18 (see Figure 1). In contrast, in the hub wheel 12 of this embodiment, the inboard end 15b of the recess 15 axially overlaps with the outboard inner ring raceway surface 12a of the double-row inner ring raceway surfaces 12a, 13a, or is located on the inboard side of the outboard inner ring raceway surface 12a. That is, the recess 15 is formed to reach the radially inward side of the outboard inner ring raceway surface 12a of the double-row inner ring raceway surfaces 12a, 13a. Therefore, the axial dimension (depth) of the recess 15 in this embodiment is deeper than in the first embodiment. When forming a deep recess 15 as in this embodiment, while the hub wheel 12 is significantly lighter, the molded product is prone to shape defects due to compressed air remaining on the bottom surface 15a of the recess 15 during molding.

[0047] Figure 5 is a diagram illustrating the manufacturing method of a hub unit bearing according to the second embodiment. In order to prevent the occurrence of molded product shape defects as described above, as shown in Figure 5, a through hole 34 is provided in the radial center of the lower mold 31, which penetrates the lower mold 31 in the axial direction. The through hole 34 extends axially along the rotation axis O and communicates with the tip of the protrusion 31b of the lower mold 31.

[0048] Furthermore, by performing the forging process as described above, the through-hole 34 forms a build-up 16 on the bottom surface 15a of the recess 15 of the hub wheel 12, and any air remaining on the bottom surface 15a of the recess 15 of the hub wheel 12 during forming is released through the through-hole 34. Therefore, shape defects in the molded product can be suppressed.

[0049] The through-hole 34 can also be provided in the radial center of the recess 15 of the lower mold 31 (see Figure 2) in the first embodiment. In this case, the through-hole communicates with the recess 32 of the lower mold 31.

[0050] In the forging die used for hot forging in this embodiment, unlike the lower die 31 of the first embodiment (see Figure 2), a recess 32 is not provided at the tip of the protrusion 31b, and the axial distance between the bottom of the recess 15 of the hub wheel 12 (inboard side end 15b) and the flange portion 18 is long. Therefore, even when a semi-sealed type is used in this embodiment, the stress reduction effect at the tip of the protrusion 31b of the lower die 31 is small, so a sealed type forging die can be used.

[0051] In the example shown in Figure 5, a flush 17 is formed around the flange portion 18 because it is a semi-sealed type. However, if a sealed type forging die is used, the flush 17 will not be formed, eliminating the need for a trimming process to remove the flush, which is preferable.

[0052] Figure 6 shows the fiber flow F of the hub wheel 12. As shown in Figure 6, the hub wheel 12 obtained by the method described above has its inflection point of the fiber flow F moved towards the outboard side by the buildup 16, approaching the vicinity of the radial center of the bottom surface 15a of the recess 15 (in the case without the buildup 16), and the direction of the fiber flow F also approaches the direction perpendicular to the rotation axis O, thereby further improving durability against stress amplitude due to rotational bending load. Furthermore, the tensile strength of the radial center of the bottom surface 15a of the recess 15 is improved by the buildup 16, and the tensile residual stress is relieved, thereby improving durability against stress amplitude due to rotational bending load. [Explanation of Symbols]

[0053] 10 Hub unit bearings 10a Bearing internal space 11 Outer ring member 11a Outer ring raceway surface 11b Inner surface 11c flange 12 Hub ring (inner ring component) 12a Inner ring raceway surface 12b Outer surface 12c Small diameter stepped section 12d Outboard side end face 13. Inner ring (inner ring component) 13a Inner ring raceway surface 13b Outer surface 14 Rolling elements 15 recesses 15a Bottom 15b Inboard side end 16 Meat Platter 17 Flash 18 Flange section 18a Through hole 19 Hub bolts 20 Pilot Section 24 Outboard side seal 25 Sensor-equipped cap 25a Cap body 25b Metal ring 25c hole 26 encoders 27 Mandrel 27a Fitting cylinder part 27b Outward-facing flange 27c Support plate part 28 Encoder body 31 Lower mold (first mold) 31a Inboard side 31b Convex part 32 recesses 33 Upper mold (second mold) 33a Outboard Side 34 Through holes F Fiber Flow O Rotation axis S-axis clearance

Claims

1. An outer ring member having double rows of outer ring raceway surfaces on its inner circumferential surface, An inner ring member having double rows of inner ring raceway surfaces on its outer circumferential surface, Between each of the outer ring raceway surfaces and each of the inner ring raceway surfaces, multiple rolling elements are provided for each row, A hub unit bearing equipped with, The inner ring member comprises a hub ring and an inner ring fixed to a small-diameter stepped portion formed on the inboard side end of the hub ring. A recessed area with a bottom that opens toward the outboard side is provided at the radial center of the outboard end face of the hub wheel. A raised section is provided at the radial center of the bottom surface on the inboard side of the recess, projecting toward the outboard side. The aforementioned build-up is composed of a curved surface whose outer diameter decreases towards the outboard side, is formed continuously in the circumferential direction, and its outboard side end is located on the rotation axis of the hub unit bearing. A hub unit bearing characterized by the following features.

2. A method for manufacturing a hub unit bearing according to claim 1, The material that will become the hub ring is inserted between the first mold on the outboard side and the second mold on the inboard side and forged, thereby forming the build-up material of the hub ring. A method for manufacturing a hub unit bearing, characterized by the following:

3. The radial center of the inboard side of the first type is provided with a recess that is recessed toward the outboard side. The recess forms the build-up material of the hub wheel. A method for manufacturing a hub unit bearing according to claim 2.

4. The radial center portion of the first type is provided with a through hole that penetrates in the axial direction. The through hole forms the build-up material of the hub ring. A method for manufacturing a hub unit bearing according to claim 2.

Images