JP2009097628A - Bearing device for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device for a wheel capable of restraining looseness in the circumferential direction, superior in connection workability of a hub wheel and an outside joint member of a constant velocity universal joint, and superior in maintainability capable of separating the hub wheel and the outside joint member of the constant velocity universal joint. <P>SOLUTION: This bearing device for the wheel is provided by separably joining the hub wheel 1 and a shaft part 12 of the outside joint member of the constant velocity universal joint 3 fitted to and inserted into a hole part 22 of the hub wheel 1 via a recess-projection fitting structure M. The recess-projection fitting structure M is constituted by pressing a projection part 35 arranged in any one of an outer diameter surface of the shaft part 12 and an inner diameter surface 37 of the hole part 22 of the hub wheel 1 and extending in the axial direction, in the other in the axial direction, and forming a recessed part 36 fitted in close contact to the projection part 35 by the projection part 35 in the other, and closely contacting the whole area of a fitting contact part 38 of the projection part 35 and the recessed part 36. The recess-projection fitting structure M allows separation by impartment of extraction force in the axial direction. A positioning inner wall 22c is arranged in the hole part 22 of the hub wheel 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a wheel bearing device for rotatably supporting a wheel with respect to a vehicle body in a vehicle such as an automobile.

  The wheel bearing device has evolved from a structure in which a double row rolling bearing called a first generation is used alone to a second generation in which a vehicle body mounting flange is integrated with an outer member. The third generation in which the inner raceway is integrally formed on one of the double row rolling bearings on the outer periphery of the hub wheel having an integral, and the constant velocity universal joint is integrated with the hub wheel. A fourth generation type has been developed in which the other inner rolling surface of the double row rolling bearing is integrally formed on the outer periphery of the outer joint member constituting the joint.

  For example, Patent Document 1 describes what is called a third generation. As shown in FIG. 15, the wheel bearing device called the third generation includes a hub wheel 102 having a flange 101 extending in the outer diameter direction, and a constant velocity universal joint 104 in which an outer joint member 103 is fixed to the hub wheel 102. And an outer member 105 disposed on the outer peripheral side of the hub wheel 102.

  The constant velocity universal joint 104 includes an outer joint member 103, an inner joint member 108 disposed in the bowl-shaped portion 107 of the outer joint member 103, and the inner joint member 108 and the outer joint member 103. A ball 109 is provided, and a holder 110 that holds the ball 109. Further, a spline portion 111 is formed on the inner peripheral surface of the center hole of the inner joint member 108, and an end spline portion of a shaft (not shown) is inserted into the center hole, and the spline portion 111 on the inner joint member 108 side The spline portion on the shaft side is engaged.

  The hub wheel 102 has a cylindrical portion 113 and the flange 101, and a short cylindrical shape in which a wheel and a brake rotor (not shown) are mounted on the outer end surface 114 (end surface on the opposite joint side) of the flange 101. A pilot part 115 is provided in a protruding manner. The pilot portion 115 includes a large-diameter first portion 115a and a small-diameter second portion 115b. A wheel is externally fitted to the first portion 115a, and a brake rotor is externally fitted to the second portion 115b.

  A notch 116 is provided on the outer peripheral surface of the end portion of the cylindrical portion 113 on the side of the flange portion 107, and an inner ring 117 is fitted into the notch 116. A first inner raceway surface 118 is provided in the vicinity of the flange on the outer peripheral surface of the cylindrical portion 113 of the hub wheel 102, and a second inner raceway surface 119 is provided on the outer peripheral surface of the inner ring 117. Further, a bolt mounting hole 112 is provided in the flange 101 of the hub wheel 102, and a hub bolt for fixing the wheel and the brake rotor to the flange 101 is mounted in the bolt mounting hole 112.

  The outer member 105 is provided with two rows of outer raceway surfaces 120 and 121 on its inner periphery, and a flange (vehicle body mounting flange) 132 on its outer periphery. Then, the first outer raceway surface 120 of the outer member 105 and the first inner raceway surface 118 of the hub wheel 102 face each other, and the second outer raceway surface 121 of the outer member 105 and the raceway surface 119 of the inner ring 117 are formed. Opposing and the rolling element 122 is interposed between these.

  The shaft portion 123 of the outer joint member 103 is inserted into the tube portion 113 of the hub wheel 102. The shaft portion 123 has a threaded portion 124 formed at the end of the ridged portion, and a spline portion 125 is formed between the threaded portion 124 and the hooked portion 107. Further, a spline portion 126 is formed on the inner peripheral surface (inner diameter surface) of the tube portion 113 of the hub wheel 102, and when the shaft portion 123 is inserted into the tube portion 113 of the hub wheel 102, The spline portion 125 engages with the spline portion 126 on the hub wheel 102 side.

Then, the nut member 127 is screwed onto the threaded portion 124 of the shaft portion 123 protruding from the cylindrical portion 113, and the hub wheel 102 and the outer joint member 103 are connected. At this time, the inner end surface (back surface) 128 of the nut member 127 and the outer end surface 129 of the cylindrical portion 113 are in contact with each other, and the end surface 130 on the shaft portion side of the hook-shaped portion 107 and the outer end surface 131 of the inner ring 117 are in contact with each other. That is, by tightening the nut member 127, the hub wheel 102 is sandwiched between the nut member 127 and the hook-shaped portion 107 via the inner ring 117.
JP 2004340403 A

  Conventionally, as described above, the spline portion 125 on the shaft portion 123 side and the spline portion 126 on the hub wheel 102 side are engaged. For this reason, it is necessary to perform spline processing on both the shaft portion 123 side and the hub wheel 102 side, which increases the cost and at the time of press-fitting, the spline portion 125 on the shaft portion 123 side and the spline portion 126 on the hub wheel 102 side. It is necessary to match the unevenness of the teeth. At this time, if the teeth are pressed by matching the tooth surfaces, the uneven teeth may be damaged (peeled). Moreover, if it press-fits by matching the large diameter of an uneven | corrugated tooth | gear, without matching a tooth surface, the play of a circumferential direction will arise easily. As described above, when there is a backlash in the circumferential direction, the transmission performance of the rotational torque is inferior and abnormal noise may occur. For this reason, it has been difficult to establish both the damage to the concavo-convex teeth and the play in the circumferential direction in the case of spline fitting as in the prior art.

  Further, it is necessary to screw the nut member 127 to the screw portion 124 of the shaft portion 123 protruding from the cylindrical portion 113. For this reason, it has a screw fastening operation at the time of assembly, which is inferior in workability, has a large number of parts, and inferior in part manageability.

  In view of the above problems, the present invention can suppress circumferential backlash, and is excellent in connection workability between the hub wheel and the outer joint member of the constant velocity universal joint, and at the same time with the hub wheel and the constant velocity. Provided is a wheel bearing device that can be separated from an outer joint member of a universal joint and has excellent maintainability.

  The wheel bearing device according to the present invention includes a hub wheel, a double row rolling bearing, and a constant velocity universal joint as a unit, and a hub wheel and an outer joint of the constant velocity universal joint that is fitted into the hole of the hub ring. A wheel bearing device in which a shaft portion of a member is detachably coupled via a concave-convex fitting structure, and either the outer diameter surface of the shaft portion of the outer joint member or the inner diameter surface of the hole portion of the hub wheel A convex portion provided on one side and extending in the axial direction is press-fitted into the other along the axial direction, and a concave portion that closely fits to the convex portion is formed on the other side, and the convex portion and the concave portion are fitted. The concave / convex fitting structure in which the entire contact area is in close contact with each other, and this concave / convex fitting structure allows separation by applying an axial pull-out force, and the end surface of the outer joint member on the side opposite to the joint side abuts. The positioning inner wall for restricting the press-fitting is provided in the hole of the hub wheel.

  According to the wheel bearing device of the present invention, the concave / convex fitting structure has the entire fitting contact portion between the convex portion and the concave portion in close contact with each other. No gap is formed. In addition, if an axial pulling force is applied to the shaft portion of the outer joint member, the outer joint member can be removed from the hole of the hub wheel. In addition, after the shaft portion of the outer joint member is pulled out from the hole portion of the hub wheel, if the shaft portion of the outer hand member is press-fitted again into the hole portion of the hub wheel, the entire fitting contact region between the convex portion and the concave portion can be obtained. The concave-convex fitting structure can be configured to closely contact each other.

  Press fitting can be regulated by the positioning inner wall, and a predetermined press fitting amount can be secured. That is, the axial length of the concave-convex fitting structure can be secured to a predetermined amount.

  It is preferable to fix the hub wheel and the shaft portion of the outer joint member through a screw structure. Thereby, after press-fitting, the axial removal of the shaft portion of the outer joint member from the hub wheel is restricted.

  It is preferable to enable press-fitting by screwing of the screw structure at least during re-press-fitting. Accordingly, the shaft portion of the outer joint member can be press-fitted into the hole of the hub wheel without using a press-fitting press machine or the like.

  The outer joint member includes a mouth portion in which the inner joint member is housed, and the shaft portion protruding from the bottom portion of the mouth portion, and an end portion of the hub wheel is crimped to be fitted on the hub wheel. A preload can be applied to the inner ring of the rolling bearing. At this time, it is preferable to provide a gap between the mouth portion of the outer joint member and the crimped portion formed by crimping the end portion of the hub wheel, and a seal member for sealing the gap is disposed. preferable.

  It is also preferable that a sealing material is interposed between the seating surface of the screw-structured bolt member that fixes the hub wheel and the shaft portion of the outer joint member, and the positioning inner wall.

  A convex portion of the concave-convex fitting structure is provided on the shaft portion of the outer joint member, and at least the hardness of the axial end portion of the convex portion is made higher than the inner diameter portion of the hole portion of the hub wheel so that the shaft portion is the hub wheel. By press-fitting into the hole portion of the convex portion from the axial end portion side, a concave portion that closely fits to the convex portion is formed on the inner diameter surface of the hole portion of the hub wheel at the convex portion, and the concave-convex fitting structure is formed. It may be configured. At this time, the convex portion bites into the concave portion forming surface (the inner diameter surface of the hole portion of the hub wheel), so that the hole portion is slightly expanded in diameter, and the convex portion is allowed to move in the axial direction. However, if the movement in the axial direction stops, the diameter of the hole portion is reduced to return to the original diameter. Thereby, the whole recessed part fitting part of a convex part closely_contact | adheres to the corresponding recessed part.

  It is preferable to provide a storage portion for storing a protruding portion generated by forming the concave portion by the press-fitting on the outer diameter side of the shaft portion on the opposite joint side than the concave-convex fitting structure. Here, the protruding portion is the material of the capacity of the concave portion into which the concave portion fitting portion of the convex portion is fitted (fitted), and is extruded from the formed concave portion, or cut to form the concave portion. It is comprised from what was extruded, what was extruded, and what was cut.

  By setting the inner diameter dimension of the inner diameter surface of the hole portion of the hub wheel to be smaller than the maximum diameter dimension of the circle connecting the vertices of the projections and larger than the maximum diameter dimension of the recesses of the shaft outer diameter surface between the projections The intermediate portion in the protruding direction of the convex portion can correspond to the position of the concave portion forming surface before forming the hole concave portion of the hub wheel.

  Further, a convex portion of the concave-convex fitting structure is provided on the inner diameter surface of the hole portion of the hub wheel, and at least the hardness of the axial end portion of the convex portion is set to the outer diameter portion of the shaft portion of the outer joint member of the constant velocity universal joint. The convex portion on the hub wheel side is press-fitted into the shaft portion of the outer joint member from the axial end portion side, thereby projecting to the outer diameter surface of the shaft portion of the outer joint member. The concave-convex fitting structure may be formed by forming a concave portion that closely fits to the portion. As the convex portion bites into the outer diameter surface of the shaft portion, the hole of the hub wheel is slightly expanded in diameter, allowing the convex portion to move in the axial direction and stopping the axial movement. In this case, the diameter of the hole is reduced to return to the original diameter. As a result, the entire fitting contact region between the convex portion and the concave portion (outer diameter surface of the shaft) of the mating member fitted into the convex portion is brought into close contact.

  At this time, it is preferable to provide an accommodating portion for accommodating the protruding portion generated by forming the concave portion by the press-fitting on the inner diameter surface of the hole portion of the hub wheel.

  In addition, the diameter dimension of the arc connecting the vertices of the plurality of convex portions of the hole portion is made smaller than the outer diameter size of the shaft portion of the outer joint member, and the inner diameter size of the hole inner diameter surface between the convex portions is made smaller than that of the outer joint member. By making it larger than the outer diameter dimension of the shaft portion, the intermediate portion in the protruding direction of the convex portion can correspond to the position of the concave portion forming surface of the shaft portion before forming the concave portion.

  The sum of the circumferential thicknesses of the projecting direction intermediate portions of the convex portions is the sum of the circumferential thicknesses at positions corresponding to the intermediate portions of the mating convex portions that fit between the convex portions adjacent in the circumferential direction. It is also preferable to make it smaller.

  It is preferable to arrange the concave-convex fitting structure at a position directly below the raceway surface of the rolling bearing. That is, if the shaft portion is press-fitted into the hole of the hub wheel, the hub wheel expands. This expansion generates a hoop stress on the raceway surface of the rolling bearing. Here, the hoop stress refers to a force for expanding the diameter in the outer diameter direction. For this reason, when a hoop stress is generated on the bearing raceway surface, there is a risk of causing a reduction in rolling fatigue life and occurrence of cracks. Therefore, by arranging the concave-convex fitting structure at a position directly below the raceway surface of the rolling bearing, generation of hoop stress on the bearing raceway surface can be suppressed.

  If the shaft part press-fitting guide structure is provided on the convex part press-fitting start side, the shaft part can be press-fitted along the shaft part press-fitting guide structure when the shaft part is press-fitted into the hole of the hub wheel.

  The hardness difference between the convex portion side and the concave portion forming side is preferably 20 or more in terms of HRC. Thus, when the convex portion is press-fitted to the other side, it is possible to press-fit only by applying a relatively small pressure input (press-fit load). Further, since it is not necessary to apply a large press-fitting load, the formed uneven teeth can be prevented from being damaged (peeled).

  In the present invention, in the concavo-convex fitting structure, there is no gap formed in the radial direction and the circumferential direction, so that all of the fitting parts contribute to rotational torque transmission, stable torque transmission is possible, No abnormal noise is generated. Furthermore, since the contact is made without a gap, the strength of the torque transmitting portion is improved. For this reason, the wheel bearing device can be made lightweight and compact.

  In addition, by applying an axial pulling force to the shaft portion of the outer joint member, the outer joint member can be removed from the hole of the hub wheel, so that the workability (maintenability) of repair and inspection of each part is improved. Improvements can be made. In addition, after the repair / inspection of each part, the shaft portion of the outer joint member is press-fitted into the hole of the hub wheel again, thereby forming a concave-convex fitting structure in which the entire fitting contact portion between the convex portion and the concave portion is in close contact. Can do. For this reason, the wheel bearing device capable of stable torque transmission can be configured again.

  A convex portion provided on either the outer diameter surface of the shaft portion of the outer joint member or the inner diameter surface of the hole portion of the hub wheel is press-fitted into the other along the axial direction, thereby closely fitting to this convex portion. A concave portion to be formed can be formed. For this reason, an uneven | corrugated fitting structure can be formed reliably. Moreover, it is not necessary to form a spline portion or the like on the member where the recess is formed, and it is excellent in productivity and does not require the phase alignment between the splines. Damage to the tooth surface can be avoided and a stable fitting state can be maintained.

  Press fitting can be regulated by the positioning inner wall, and a predetermined press fitting amount can be secured. That is, the axial length of the concave-convex fitting structure can be secured to a predetermined amount. For this reason, by positioning, the dimensional accuracy of the wheel bearing device is stabilized, and the axial length of the concave-convex fitting structure disposed along the axial direction can be secured to a stable length. Thus, torque transmission can be improved.

  By fixing through the screw structure, the shaft part is prevented from coming off from the hub wheel in the axial direction after press-fitting, and stable torque transmission is possible over a long period of time.

  Further, in the case where the end of the hub ring is crimped and the preload is applied to the inner ring of the rolling bearing, it is not necessary to apply the preload to the inner ring by the mouth portion of the outer joint member. For this reason, it is possible to press-fit the shaft portion of the outer joint member without considering the preload to the inner ring, and it is possible to improve the connectivity (assembly property) between the hub wheel and the outer joint member. Since the mouse portion is not in contact with the hub wheel, it is possible to prevent the generation of abnormal noise due to the contact between the mouse portion and the hub wheel.

  If the gap between the mouth part of the outer joint member and the crimped part where the end of the hub ring is crimped is sealed with a seal member, rainwater and foreign matter can be prevented from entering through this gap and the concave and convex parts can be fitted. It is possible to avoid deterioration of adhesion due to rainwater or foreign matter on the structure. If a sealing material is interposed between the bearing surface of the screw-structure bolt member and the inner wall for positioning, rainwater and foreign matter can be prevented from entering the concave-convex fitting structure from this bolt member, and quality can be improved. it can.

  Further, the convex portion of the concave-convex fitting structure is provided on the shaft portion of the outer joint member, and the hardness of the axial end portion of the convex portion is made higher than the inner diameter portion of the hole portion of the hub wheel so that the shaft portion is the hub. If it press-fits into the hole part of a ring | wheel from the axial direction edge part side of a convex part, the hardness by the side of a shaft part can be made high and the rigidity of a shaft part can be improved. In addition, a convex portion of the concave-convex fitting structure is provided on the inner diameter surface of the hole portion of the hub wheel, and the hardness of the axial end portion of the convex portion is determined from the outer diameter portion of the shaft portion of the outer joint member of the constant velocity universal joint. In the case where the convex portion on the hub wheel side is press-fitted into the shaft portion of the outer joint member from the end portion in the axial direction, there is no need to perform hardness treatment (heat treatment) on the shaft portion side, so that the constant velocity Excellent productivity of universal joint outer joint members.

  By providing a storage portion for storing the protruding portion that is generated by forming the concave portion by press-fitting, the protruding portion can be held (maintained) in the storage portion, and the protruding portion does not enter the inside of the vehicle outside the apparatus. . In other words, the protruding portion can be kept stored in the storage portion, and it is not necessary to perform the removal processing of the protruding portion, so that the number of assembling work can be reduced, improving the assembling workability and reducing the cost. Can be planned.

  In addition, by arranging the intermediate part in the protruding direction of the convex part on the concave part forming surface before forming the concave part, the convex part bites into the concave part forming surface during press-fitting, so that the concave part can be reliably formed. it can. That is, a sufficient press-fitting allowance for the other side of the convex portion can be taken. As a result, the formability of the concave-convex fitting structure is stabilized, there is no variation in press-fit load, and a stable torsional strength can be obtained.

  The convex part on the side where the concave part is formed by making the circumferential thickness of the intermediate part in the protruding direction of the convex part smaller than the dimension at the position corresponding to the intermediate part between the convex parts adjacent in the circumferential direction ( The thickness in the circumferential direction of the projecting intermediate portion of the convex portion between the concave portions formed can be increased. For this reason, the shear area of the convex part of the other party (the convex part having low hardness between the concave parts due to the formation of the concave parts) can be increased, and the torsional strength can be ensured. Moreover, since the tooth thickness of the convex portion on the higher hardness side is small, the press-fitting load can be reduced and the press-fitting property can be improved.

  By arranging the concave-convex fitting structure at a position directly below the raceway surface of the rolling bearing, generation of hoop stress on the bearing raceway surface is suppressed. As a result, it is possible to prevent a bearing failure such as a decrease in rolling fatigue life, occurrence of cracks, and stress corrosion cracking, and a high-quality bearing can be provided.

  Further, when the shaft portion is press-fitted into the hole of the hub wheel, the shaft portion can be press-fitted along the shaft portion press-fitting guide structure. As a result, stable press-fitting is possible, and it is possible to prevent misalignment and tilting.

  Since the hardness difference between the convex portion side and the concave portion forming side is set to 20 or more by HRC, when the convex portion is press-fitted to the other side, it can be press-fitted only by applying a relatively small pressure input (press-fit load). The press fit can be improved. In addition, since it is not necessary to apply a large press-fitting load, it is possible to prevent the formed uneven teeth from being damaged (peeled), and to stabilize the uneven fitting structure in which no gaps are generated in the radial and circumferential directions. Can be configured.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 shows a wheel bearing device according to a first embodiment. This wheel bearing device is a hub wheel 1, a double row rolling bearing 2 and a constant velocity universal joint 3 integrated with each other. 1 and the shaft portion 12 of the outer joint member of the constant velocity universal joint 3 that is inserted into the hole portion 22 of the hub wheel 1 are detachably coupled via the concave-convex fitting structure M.

  The constant velocity universal joint 3 includes a plurality of outer rings 5 serving as outer joint members, an inner ring 6 serving as an inner joint member disposed on the inner side of the outer ring 5, and a plurality of torque transmissions interposed between the outer ring 5 and the inner ring 6. The ball 7 and the cage 8 that is interposed between the outer ring 5 and the inner ring 6 and holds the ball 7 are configured as main members. As shown in FIG. 8 and the like, the inner ring 6 is spline-fitted by press-fitting an end portion 10a of the shaft 10 into the shaft hole inner diameter 6a and is coupled to the shaft 10 so as to be able to transmit torque. Note that a retaining ring 9 for retaining the shaft is fitted to the end portion 10a of the shaft 10.

  The outer ring 5 is composed of a mouse part 11 and a stem part (shaft part) 12. The mouse part 11 has a bowl shape opened at one end, and a plurality of track grooves 14 extending in the axial direction are circumferentially formed on the inner spherical surface 13 thereof. It is formed at equal intervals in the direction. In the inner ring 6, a plurality of track grooves 16 extending in the axial direction are formed on the outer spherical surface 15 at equal intervals in the circumferential direction.

  The track groove 14 of the outer ring 5 and the track groove 16 of the inner ring 6 make a pair, and one ball 7 as a torque transmitting element can roll on each ball track constituted by the pair of track grooves 14 and 16. It is incorporated. The ball 7 is interposed between the track groove 14 of the outer ring 5 and the track groove 16 of the inner ring 6 to transmit torque. The cage 8 is slidably interposed between the outer ring 5 and the inner ring 6, contacts the inner spherical surface 13 of the outer ring 5 at the outer spherical surface, and contacts the outer spherical surface 15 of the inner ring 6 at the inner spherical surface. The constant velocity universal joint in this case is a Zepper type, but is another constant velocity universal joint such as an undercut free type having a straight straight portion at the bottom of each track groove 14, 16. May be.

Moreover, as shown in FIG. 8 etc., the opening part of the mouse | mouth part 11 is block | closed with the boot 18. As shown in FIG. The boot 18 includes a large diameter portion 18a, a small diameter portion 18b, and a bellows portion 18c that connects the large diameter portion 18a and the small diameter portion 18b. The large-diameter portion 18a is externally fitted to the opening of the mouse portion 11, and is fastened by the boot band 19a in this state, and the small-diameter portion 18b is externally fitted to the boot mounting portion 10b of the shaft 10, and in this state, the boot band 19b It is concluded.

  As shown in FIGS. 1 and 7, the hub wheel 1 includes a cylindrical portion 20 and a flange 21 provided at an end of the cylindrical portion 20 on the side opposite to the joint. The hole portion 22 of the cylindrical portion 20 has a shaft portion fitting hole 22a and a tapered hole 22b on the anti-joint side, and is positioned so as to protrude in the inner diameter direction between the shaft portion fitting hole 22a and the tapered hole 22b. An inner wall 22c is provided. That is, the shaft portion 12 of the outer ring 5 of the constant velocity universal joint 3 and the hub wheel 1 are coupled to each other through the concave-convex fitting structure M described later in the shaft portion fitting hole 22a. In addition, the recessed part 51 is provided in the end surface by the side of the non-shaft part fitting hole of this positioning inner wall 22c.

  The hole portion 22 has a large-diameter portion 46 on the opening side on the side opposite to the inner wall for positioning relative to the shaft portion fitting hole 22a, and a small-diameter portion 48 on the inner wall side for positioning relative to the shaft portion fitting hole 22a. A tapered portion (tapered hole) 49a is provided between the large diameter portion 46 and the shaft portion fitting hole 22a. The tapered portion 49a is reduced in diameter along the press-fitting direction when the hub wheel 1 and the shaft portion 12 of the outer ring 5 are coupled.

  The rolling bearing 2 includes an inner member (inner ring) 24 that fits in a stepped portion 23 provided on the joint side of the tubular portion 20 of the hub wheel 1, and an outer member that fits outside the shaft portion 12 of the hub wheel 1. 25. The outer member 25 is provided with two rows of outer raceways (outer races) 26 and 27 on its inner circumference, and a first inner raceway (provided on the outer circumference of the first outer raceway 26 and the shaft portion of the hub wheel 1). The inner race) 28 is opposed to the second outer raceway surface 27 and the second inner raceway surface (inner race) 29 provided on the outer peripheral surface of the inner ring 24 is opposed to the ball as the rolling element 30 therebetween. Is installed. Note that seal members S are attached to both openings of the outer member 25. A knuckle 34 (see FIG. 8) extending from a vehicle suspension device (not shown) is attached to the outer ring which is the outer member 25.

  In this case, the end of the hub wheel 1 on the joint side is swaged, and a preload is applied to the inner member (inner ring) 24 by the swaged portion 31. As a result, the inner ring 24 can be fastened to the hub wheel 1. The flange 21 of the hub wheel 1 is provided with a bolt mounting hole 32, and a hub bolt 33 for fixing the wheel and the brake rotor to the flange 21 is mounted in the bolt mounting hole 32.

  The shaft portion 12 of the outer ring 5 is provided with a screw hole 50 that opens at the end surface on the anti-joint side (anti-mouse side) in the shaft center portion. The screw hole 50 is a tapered portion 50a whose opening is expanded toward the opening. A small-diameter portion 12b is provided at the end of the shaft portion 12 on the anti-joint side (anti-mouse side). That is, the shaft portion 12 includes a main body portion 12a having a large diameter and a small diameter portion 12b.

  As shown in FIGS. 2 and 3, the concave-convex fitting structure M includes, for example, a convex portion 35 provided in the shaft portion 12 and extending in the axial direction, and an inner diameter surface of the hole portion 22 of the hub wheel 1 (in this case, the shaft The inner surface 37) of the part fitting hole 22a is formed with a concave part 36, and the entire fitting contact part 38 of the convex part 35 and the concave part 36 of the hub wheel 1 fitted to the convex part 35 is in close contact. Yes. That is, a plurality of convex portions 35 are arranged at a predetermined pitch along the circumferential direction on the outer peripheral surface of the shaft portion 12 on the side opposite to the mouse portion, and the inner diameter surface of the shaft portion fitting hole 22a of the hole portion 22 of the hub wheel 1 A plurality of concave portions 36 into which the convex portions 35 are fitted to 37 are formed along the circumferential direction. That is, the convex part 35 and the concave part 36 fitted to this are tight-fitted over the entire circumference in the circumferential direction.

In this case, each convex portion 35 has a triangular shape (mountain shape) having a convex rounded apex in cross section, and the fitting contact portion (concave fitting portion) 38 of each convex portion 35 is shown in FIG. It is the range A shown in b), and is the range from the mid-section of the mountain in the cross section to the summit. Further, a gap 40 is formed on the inner diameter side with respect to the inner diameter surface 37 of the hub wheel 1 between the adjacent convex portions 35 in the circumferential direction.

  In this way, the hub wheel 1 and the shaft portion 12 of the outer ring 5 of the constant velocity universal joint 3 can be connected via the concave-convex fitting structure M. At this time, as described above, the end of the hub wheel 1 on the joint side is swaged, and the swaged portion 31 applies preload to the inner member (inner ring) 24. It is not necessary to apply a preload to the inner ring 24 at the part 11, and the mouse part 11 is not in contact with the end part of the hub wheel 1 (in this case, the caulking part 31).

  Since the mouse part 11 is not in contact with the end part of the hub wheel 1 (in this case, the crimping part 31), it is between the crimping part 31 of the hub wheel 1 and the bottom outer surface 11a of the mouse part 11. Is provided with a gap 58. For this reason, as shown in FIGS. 6A and 6B, it is preferable that the gap 58 is closed with a seal member 59. In this case, the gap 58 is formed from between the caulking portion 31 of the hub wheel 1 and the bottom outer surface 11a of the mouth portion 11 to between the shaft portion fitting hole 22a and the main body portion 12a of the shaft portion 12. In this embodiment, the seal member 59 is disposed at a corner portion between the caulking portion 31 of the hub wheel 1 and the main body portion 12a. The seal member 59 may be an O-ring as shown in FIG. 6A or a gasket as shown in FIG. 6B.

  A bolt member 54 is screwed into the screw hole 50 of the shaft portion 12 from the anti-joint side. As shown in FIG. 1, the bolt member 54 includes a flanged head portion 54a and a screw shaft portion 54b. As shown in FIG. 7, the screw shaft portion 54b includes a large-diameter base portion 55a, a small-diameter main body portion 55b, and a tip-side screw portion 55c. In this case, a through hole 56 is provided in the positioning inner wall 22 c, the shaft portion 54 b of the bolt member 54 is inserted into the through hole 56, and the screw portion 55 c is screwed into the screw hole 50 of the shaft portion 12. The hole diameter d1 of the through hole 56 is set slightly larger than the outer diameter d2 of the large base portion 55a of the shaft portion 54b. Specifically, 0.05 mm <d1−d2 <0.5 mm or so. The maximum outer diameter of the threaded portion 55c is set to be the same as or slightly smaller than the outer diameter of the large base portion 55a.

  In the present wheel bearing device, as shown in FIG. 2, a shaft press-fitting guide structure M1 that guides the press-fitting of the shaft 12 at the time of press-fitting is provided on the convex press-fitting start side. In this case, it consists of a female spline 44 provided in the tapered portion 49 a of the hole portion 22. That is, as shown in FIG. 4 (a), the guide recess 44a has a predetermined pitch (in this case, the same pitch as the arrangement pitch of the projections 35) along the circumferential direction on the shaft fitting hole 22a side of the taper portion 49a. Is provided.

  In this case, as shown in FIG. 7, the bottom diameter D10 of the guide recess 44a is the maximum outer diameter of the projection 35, that is, the maximum diameter of the circle connecting the vertices of the projection 35 which is the projection 41a of the spline 41. As shown in FIG. 4A, a radial clearance C1 is formed between the top of the convex portion 35 and the bottom of the guide concave portion 44a.

  Next, the fitting method of the uneven fitting structure M will be described. In this case, as shown in FIG. 7, the outer diameter portion of the shaft portion 12 is subjected to thermosetting treatment, and the spline 41 including the convex portions 41 a and the concave portions 41 b along the axial direction is formed on the hardened layer H. For this reason, the convex part 41a of the spline 41 is cured, and the convex part 41a becomes the convex part 35 of the concave-convex fitting structure M. The spline 41 is provided on the small diameter side of the main body 12 a of the shaft 12. The range of the hardened layer H in this embodiment is from the outer end edge of the spline 41 to a part of the bottom wall of the mouth portion 11 of the outer ring 5 as shown by the cross hatched portion. As this thermosetting treatment, various heat treatments such as induction hardening and carburizing and quenching can be employed. Here, induction hardening is a hardening method that applies the principle of heating a conductive object by placing Joule heat in a coil through which high-frequency current flows, and generating Joule heat by electromagnetic induction. is there. The carburizing and quenching is a method in which carbon is infiltrated / diffused from the surface of the low carbon material and then quenched. The module of the spline 41 of the shaft portion 12 is a small tooth of 0.5 or less. Here, the module is a pitch circle diameter divided by the number of teeth.

  On the inner diameter surface 37 side of the hole portion 22 of the hub wheel 1 (that is, the inner diameter surface of the shaft portion fitting hole 22a), an uncured portion (unburned state) that is not subjected to thermosetting treatment is used. The hardness difference between the hardened layer H of the shaft portion 12 of the outer ring 5 and the uncured portion of the hub wheel 1 is 20 points or more in HRC. More specifically, the hardness of the hardened layer H is about 50 HRC to 65 HRC, and the hardness of the uncured portion is about 10 HRC to 30 HRC.

  At this time, the projecting direction intermediate portion of the convex portion 35 corresponds to the position of the concave portion forming surface (in this case, the inner diameter surface 37 of the shaft portion fitting hole 22a) before the concave portion is formed. That is, as shown in FIG. 7, the inner diameter dimension D of the inner diameter surface 37 of the shaft portion fitting hole 22a is connected to the maximum outer diameter of the convex portion 35, that is, the apex of the convex portion 35 which is the convex portion 41a of the spline 41. It is set to be smaller than the maximum diameter dimension (circumscribed circle diameter) D1 of the circle and larger than the outer diameter dimension, that is, the maximum diameter dimension D2 of the circle connecting the bottom of the concave portion 41b of the spline 41 to the shaft outer diameter surface between the convex portions. The That is, D2 <D <D1. Further, D1 is set smaller than the hole diameter dimension D3 of the large-diameter portion 46 of the hole 22.

  The spline 41 can be formed by various processing methods such as rolling processing, cutting processing, press processing, and drawing processing, which are known publicly known means. Moreover, various heat processing, such as induction hardening and carburizing hardening, can be employ | adopted as a thermosetting process. Note that the press-fitting start end surface 35 a of the convex portion 35 formed by forming the spline 41 is a flat surface orthogonal to the axial direction of the shaft portion 12.

  Then, as shown in FIG. 7, a seal member 59 is externally fitted to the shaft portion 12 so that the shaft center of the hub wheel 1 and the shaft center of the outer ring 5 of the constant velocity universal joint 3 are aligned. In this state, the shaft portion 12 of the outer ring 5 is inserted (press-fitted) into the hub wheel 1. That is, each protrusion 35 of the shaft portion 12 is fitted into each guide recess 44a of the shaft portion press-fitting guide structure M1. Thereby, the axial center of the hub wheel 1 and the axial center of the outer ring 5 are brought into a coincident state. At this time, since the end portion of each guide recess 44a on the uneven fitting structure side is a flat surface 77a (see FIG. 2) orthogonal to the press-fitting direction, the press-fitting start end surface 35a of the convex portion 35 is received. It is possible to press fit from this state. At this time, as described above, the diameter D of the inner diameter surface 37 of the shaft fitting hole 22a, the maximum outer diameter D1 of the protrusion 35, and the minimum outer diameter D2 of the recess of the spline 41 are as described above. Further, since the hardness of the convex portion 35 is 30 points or more larger than the hardness of the inner diameter surface 37, if the shaft portion 12 is press-fitted into the hole portion 22 of the hub wheel 1, the convex portion 35 becomes the inner diameter. The convex portion 35 bites into the surface 37, and the concave portion 36 into which the convex portion 35 is fitted is formed along the axial direction.

  This press-fitting is performed until the end surface 52 comes into contact with the end surface 53 of the positioning inner wall 22c in the small diameter portion 12b of the shaft portion 12. As a result, as shown in FIGS. 3A and 3B, the entire fitting contact portion 38 between the convex portion 35 at the end of the shaft portion 12 and the concave portion 36 fitted therein is in close contact. In other words, the shape of the convex portion 35 is transferred to the other-side concave portion forming surface (in this case, the inner diameter surface 37 of the shaft portion fitting hole 22a of the hole portion 22). At this time, the convex portion 35 bites into the inner diameter surface 37 of the hole portion 22, so that the hole portion 22 is slightly expanded in diameter, and the convex portion 35 is allowed to move in the axial direction. When the movement stops, the hole 22 is reduced in diameter to return to the original diameter. In other words, the hub wheel 1 is elastically deformed in the radial direction when the convex portion 35 is press-fitted, and a preload corresponding to this elastic deformation is applied to the tooth surface of the convex portion 35 (surface of the concave portion fitting portion). For this reason, the concave / convex fitting structure M in which the entire concave portion fitting portion of the convex portion 35 is in close contact with the corresponding concave portion 36 can be reliably formed. That is, a female spline 42 that closely contacts the male spline 41 is formed on the inner diameter surface of the hole 22 of the hub wheel 1 by the spline (male spline) 41 on the shaft portion 12 side.

  In this way, the concave-convex fitting structure M is configured. In this case, the concave-convex fitting structure M is disposed at a position directly below the raceway surfaces 26, 27, 28, 29 of the rolling bearing 2. Here, the direct under-position is a position that does not correspond to the radial direction with respect to the ball contact portion position of the raceway surfaces 26, 27, 28, and 29.

  After the press-fitting, the bolt member 54 is screwed into the screw hole 50 of the shaft portion 12 from the opposite joint side. In this manner, by screwing the bolt member 54 into the screw hole 50 of the shaft portion 12, the flange portion 60 of the head portion 54a of the bolt member 54 is fitted into the recessed portion 51 of the positioning inner wall 22c. As a result, the positioning inner wall 22c is sandwiched between the end surface 52 of the shaft portion 12 on the opposite joint side and the head portion 54a of the bolt member 54. That is, the hub wheel 1 and the shaft portion 12 of the outer ring 5 are fixed by the screw structure M2.

  The gap 58 can be closed between the caulking portion 31 of the hub wheel 1 and the bottom outer surface 11a of the mouth portion 11 by the seal member 59 fitted on the shaft portion 12.

  In this case, a sealing material (not shown) may be interposed between the seat surface 60a of the bolt member 54 and the positioning inner wall 22c. For example, the sealing material (sealing agent) made of various resins that can be cured after application on the seating surface 60a of the bolt member 54 and exhibit sealing performance between the seating surface 60a and the bottom surface of the recessed portion 51 of the positioning inner wall 22c. ) May be applied. In addition, as this sealing material, the thing which does not deteriorate in the atmosphere where this wheel bearing apparatus is used is selected. Further, a sealing material may be interposed between the fitting contact portions 38 between the convex portions 35 and the concave portions 36. In this case, the press-fitting may be performed in a state where a seal material (seal agent) similar to the seal material (seal agent) applied to the seating surface 60 a of the bolt member 54 is applied to the surface of the convex portion 35.

  By the way, when the shaft portion 12 of the outer ring 5 is press-fitted into the hole portion 22 of the hub wheel 1, as shown by the phantom line in FIG. A press-fitting load (axial load) may be applied from the press-fitting jig K to the stepped surface G by engaging the press-fitting jig K. The stepped surface G may be provided on the entire circumference in the circumferential direction or at a predetermined pitch along the circumferential direction. For this reason, the press-fitting jig K to be used only needs to be able to apply an axial load corresponding to these stepped surfaces G.

  As described above, in the present invention, the concave-convex fitting structure M in which the entire fitting contact portion 38 between the convex portion 35 of the shaft portion 12 and the concave portion 36 of the hub wheel 1 is in close contact can be reliably formed. Moreover, it is not necessary to form a spline portion or the like on the member in which the concave portion 36 is formed, which is excellent in productivity, and does not require the phase alignment between the splines. The tooth surface can be prevented from being damaged, and a stable fitting state can be maintained.

  In the concave / convex fitting structure M, the entire fitting contact portion 38 between the convex portion 35 and the concave portion 36 is in close contact with each other. Therefore, in the fitting structure M, there is no gap in which play occurs in the radial direction and the circumferential direction. . For this reason, all the fitting parts contribute to rotational torque transmission, stable torque transmission is possible, and no abnormal noise is generated.

  Since the shaft portion press-fitting guide structure M1 is provided, when the shaft portion 12 is press-fitted into the hole 22 of the hub wheel 1, it can be press-fitted along the shaft portion press-fitting guide structure M1.

  By the way, if the shaft portion 12 is press-fitted into the hole portion 22 of the hub wheel 1, the formed protruding portion 45 is curled while being curled, as shown in FIGS. It is accommodated in a space accommodating portion 57 composed of a space provided on the diameter side. Here, the protruding portion 45 is the material of the capacity of the concave portion 36 into which the convex portion 35 is inserted (fitted), and is extruded from the concave portion 36 to be formed, and is cut to form the concave portion 36. It is comprised from what was extruded, what was extruded, and what was cut. For this reason, the protruding portion 45 which is a part of the material scraped off or pushed out from the inner diameter surface of the hole portion 22 enters the storage portion 57.

  Thus, by providing the storage portion 57 for storing the protruding portion 45 generated by forming the concave portion by the press-fitting, the protruding portion 45 can be held (maintained) in the storage portion 57, and the protruding portion 45 is outside the apparatus. Never get into any other vehicle. That is, the protruding portion 45 can be kept stored in the storage portion 57, and it is not necessary to perform the removal processing of the protruding portion 45, so that the number of assembling operations can be reduced, and the assembly workability can be improved. Cost reduction can be achieved.

  Press fitting can be regulated by the positioning inner wall 22c, and a predetermined press fitting amount can be secured. That is, the axial length of the concave-convex fitting structure M can be secured to a predetermined amount. For this reason, by positioning, the dimensional accuracy of the wheel bearing device is stabilized, and the axial length of the concave-convex fitting structure M disposed along the axial direction is secured to a stable length. Thus, torque transmission can be improved.

  By fixing with the screw structure M2, the axial disengagement of the shaft portion 12 from the hub wheel 1 is regulated after press-fitting, and stable torque transmission is possible over a long period of time.

  Since the end of the hub wheel 1 is crimped and preload is applied to the inner ring 24 of the rolling bearing 2, it is not necessary to apply preload to the inner ring by the mouth portion 11 of the outer ring 5. For this reason, it is possible to press-fit the shaft portion 12 of the outer ring 5 without considering the preload to the inner ring 24, and it is possible to improve the connectivity (assembly property) between the hub wheel 1 and the outer ring 5. Since the mouse part 11 is not in contact with the hub wheel 1, it is possible to prevent the generation of noise due to the contact between the mouse part 11 and the hub wheel 1.

  Since a gap 58 between the mouth portion 11 of the outer ring 5 and the crimped portion 31 formed by crimping the end of the hub wheel 1 is sealed with a seal member 59, rainwater and foreign matter are removed from the gap 58. Intrusion is prevented, and deterioration of adhesion due to rain water, foreign matter, or the like can be avoided. Since a sealing material is interposed between the seating surface 60a of the bolt member 54 having a screw structure for fixing the hub wheel 1 and the shaft portion 12 of the outer ring 5 and the positioning inner wall 22c, irregularities from the bolt member 54 are provided. Intrusion of rainwater and foreign matter into the fitting structure M is prevented, and quality can be improved.

  In addition, by arranging the intermediate portion in the protruding direction of the convex portion 35 on the concave portion forming surface before the concave portion is formed, the convex portion 35 bites into the concave portion forming surface during press-fitting, and the concave portion 36 is reliably formed. can do. That is, the press-fitting allowance with respect to the other side of the convex part 35 can be taken sufficiently. As a result, the formability of the concave-convex fitting structure M is stabilized, there is no variation in press-fit load, and a stable torsional strength is obtained.

  In the embodiment shown in FIG. 1 and the like, the convex portion 35 of the concave-convex fitting structure M is provided on the shaft portion 12 of the outer ring 5, and the hardness of the axial end portion of the convex portion 35 is set from the inner diameter portion of the hole portion of the hub wheel 1. If the shaft portion 12 is press-fitted into the hole portion 22 of the hub wheel 1, the hardness on the shaft portion side can be increased and the rigidity of the shaft portion can be improved.

  In particular, since the hardness difference between the convex portion side and the concave portion forming side (in this case, the inner diameter surface side of the hole 22 of the hub wheel 1) is 20 or more in HRC, when press-fitting the convex portion 35 to the other side, The press-fitting can be performed only by applying a relatively small press-fitting (press-fitting load), and the press-fitting property can be improved. Further, since it is not necessary to apply a large press-fitting load, it is possible to prevent the formed uneven teeth from being damaged (peeled), and to stabilize the uneven fitting structure M that does not generate gaps in the radial and circumferential directions. Can be configured.

  By arranging the concave-convex fitting structure M at a position directly below the raceway surface of the rolling bearing 2, occurrence of hoop stress on the bearing raceway surface is suppressed. As a result, it is possible to prevent a bearing failure such as a decrease in rolling fatigue life, occurrence of cracks, and stress corrosion cracking, and a high-quality bearing 2 can be provided.

  As in the above-described embodiment, the spline 41 formed on the shaft portion 12 uses small teeth with a module of 0.5 or less, so that the formability of the spline 41 can be improved and the press-fit load is reduced. Can be achieved. In addition, since the convex part 35 can be comprised with the spline normally formed in this kind of shaft, this convex part 35 can be easily formed at low cost.

  By the way, the outer ring 5 can be pulled out from the hub wheel 1 by removing the bolt member 54 by screwing the bolt member 54 out of the state shown in FIG. That is, the fitting force of the concave-convex fitting structure M can be pulled out by applying a pulling force of a predetermined force or more to the outer ring 5.

  For example, the hub wheel 1 and the constant velocity universal joint 3 can be separated by a jig 70 as shown in FIG. The jig 70 includes a base 71, a pressing bolt member 73 that is screwed into a screw hole 72 of the base 71 so as to be able to advance and retreat, and a screw shaft 76 that is screwed into the screw hole 50 of the shaft portion 12. A through hole 74 is provided in the base 71, and the bolt 33 of the hub wheel 1 is inserted into the through hole 74, and the nut member 75 is screwed into the bolt 33. At this time, the base 71 and the flange 21 of the hub wheel 1 are overlapped, and the base 71 is attached to the hub wheel 1.

  After attaching the base 71 to the hub wheel 1 or before attaching the base 71 as described above, the screw shaft 76 is inserted into the screw hole 50 of the shaft portion 12 so that the base 76a protrudes from the positioning inner wall 22c to the anti-joint side. Screw together. The protruding amount of the base portion 76a is set longer than the axial length of the uneven fitting structure M. The screw shaft 76 and the pressing bolt member 73 are disposed on the same axis (on the axis of this wheel bearing device).

  Thereafter, as shown in FIG. 8, the pressing bolt member 73 is screwed into the screw hole 72 of the base 71 from the anti-joint side, and in this state, screwed to the screw shaft 76 side as indicated by an arrow. At this time, since the screw shaft 76 and the pressing bolt member 73 are arranged on the same axis (on the axis of the wheel bearing device), the screw bolt 73 is caused by this screwing. The screw shaft 76 is pressed in the direction of the arrow. As a result, the outer ring 5 moves in the direction of the arrow with respect to the hub ring 1, and the outer ring 5 is detached from the hub ring 1.

  Further, from the state in which the outer ring 5 is detached from the hub wheel 1, the hub wheel 1 and the outer ring 5 can be connected again using, for example, the bolt member 54. That is, with the base 71 removed from the hub wheel 1 and the screw shaft 76 removed from the shaft 12, the projection 35 of the shaft 12 is fitted into the guide recess 44a as shown in FIG. Let Thereby, the phase of the male spline 41 on the shaft portion 12 side and the female spline 42 of the hub wheel 1 formed by the previous press-fitting match. At this time, as shown in FIG. 4A, a radial gap C1 is formed between the top of the projection 35 and the bottom of the guide recess 44a.

  In this state, as shown in FIG. 9, the bolt member 54 is screwed into the screw hole 50 of the shaft portion 12 through the through hole 56, and the bolt member 54 is screwed into the screw hole 50 (the screw structure M2). Screw). Thereby, as shown in FIG. 10B, the shaft portion 12 is fitted into the hub wheel 1. At this time, the hole portion 22 is slightly expanded in diameter, allowing the shaft portion 12 to enter in the axial direction, and the end surface 52 abuts the end surface 53 of the positioning inner wall 22c on the small diameter portion 12b of the shaft portion 12. Invade until. In this case, as shown in FIG. 10C, the end surface 35 a of the convex portion 35 abuts on the end surface 36 a of the concave portion 36. If the movement in the axial direction is stopped, the hole 22 is reduced in diameter to return to the original diameter. As a result, as in the previous press-fitting, the concave-convex fitting structure M in which the entire concave portion fitting portion of the convex portion 35 is in close contact with the corresponding concave portion 36 can be reliably configured.

  Since the opening portion of the screw hole 50 of the shaft portion 12 is a tapered portion 50a that expands toward the opening side, there is an advantage that the screw shaft 76 and the bolt member 54 can be easily screwed into the screw hole 50.

  By the way, in the first time (press-fitting for forming the recess 36 in the inner diameter surface 37 of the hole 22), the press-fitting load is relatively large, so it is necessary to use a press machine or the like for press-fitting. On the other hand, in such re-pressing, since the press-fitting load is smaller than the first press-fitting load, the shaft portion 12 can be stably and accurately inserted into the hole of the hub wheel 1 without using a press machine or the like. 22 can be press-fitted. For this reason, the outer ring 5 and the hub wheel 1 can be separated and connected in the field.

  In this way, by applying an axial pulling force to the shaft portion 12 of the outer ring 5, the outer ring 5 can be removed from the hole 22 of the hub wheel 1, so that the workability (maintenance of repair / inspection of each part) is maintained. Property) can be improved. Moreover, by fitting the shaft portion 12 of the outer ring 5 into the hole portion 22 of the hub wheel 1 again after repair and inspection of each part, the fitting contact portion 38 between the convex portion 35 and the concave portion 36 is closely contacted. Structure M can be constructed. For this reason, the wheel bearing device capable of stable torque transmission can be configured again.

  The shaft press-fitting guide structure M1 has the guide concave portion 44a that matches the phase of the convex portion 35 and the phase of the other concave portion 36, so that the shaft portion 12 of the outer hand member is again attached to the hub wheel 1. When press-fitting into the hole 22, it is inserted into the recess 36 formed by the previous press-fitting, and the recess 36 is not damaged. For this reason, the uneven | corrugated fitting structure M which does not produce the clearance gap which produces backlash in a radial direction and the circumferential direction again can be comprised with high precision.

  By forming a gap between the top of the projection 35 and the bottom of the guide recess 44a, etc., the projection 35 can be easily fitted into the guide recess 44a in the pre-press-in process, and the guide recess 44a does not hinder the press-fitting of the convex portion 35. For this reason, the assemblability can be improved.

  When the bolt member 54 is screwed into the screw hole 50, the base portion 55 a of the bolt member 54 is in a state corresponding to the through hole 56 as shown in FIG. 7. Moreover, the hole diameter d1 of the through hole 56 is set to be slightly larger than the outer diameter d2 of the large base portion 55a of the shaft portion 54b (specifically, about 0.05 mm <d1-d2 <0.5 mm). Therefore, the outer diameter of the base portion 55a of the bolt member 54 and the inner diameter of the through-hole 56 can constitute a guide when the bolt member 54 is screwed through the screw hole 50, and without misalignment. The shaft portion 12 can be press-fitted into the hole portion 22 of the hub wheel 1. In addition, if the axial length of the through hole 56 is too short, a stable guide cannot be exhibited. On the other hand, if it is too long, the thickness dimension of the positioning inner wall 22c becomes large, and the uneven fitting structure M Cannot be secured in the axial direction, and the weight of the hub wheel 1 is increased. Therefore, various changes can be made in consideration of these.

  In the embodiment, as shown in FIG. 4A, the radial gap C1 is formed between the top of the projection 35 and the bottom of the guide recess 44a, but as shown in FIG. 4B. In addition, circumferential gaps C2 and C2 may be formed between the side portion of the convex portion 35 and the side portion of the guide concave portion 44a. Further, as shown in FIG. 4C, the radial gap C1 between the top of the convex portion 35 and the bottom of the guide concave portion 44a, and the side portion of the convex portion 35 and the side portion of the guide concave portion 44a. A circumferential clearance C2 may be formed between them. By forming such a gap, the protrusion 35 can be easily fitted into the guide recess 44a in the pre-press-in process, and the guide recess 44a does not prevent the protrusion 35 from being press-fitted.

In the spline 41 shown in FIG. 2, the pitch of the convex portions 41a and the pitch of the concave portions 41b are set to be the same. For this reason, in the said embodiment, as shown in FIG.2 (b), it respond | corresponds to the circumferential direction thickness L of the protrusion direction intermediate part of the convex part 35, and the said intermediate part between the convex parts 35 adjacent to the circumferential direction. The circumferential dimension L0 at the position is substantially the same.

  On the other hand, as shown in FIG. 11A, the circumferential thickness L2 of the projecting direction intermediate portion of the convex portion 35 is set at a position corresponding to the intermediate portion between the convex portions 35 adjacent in the circumferential direction. It may be smaller than the circumferential dimension L1. That is, in the spline 41 formed on the shaft portion 12, the circumferential thickness (tooth thickness) L <b> 2 of the intermediate portion in the projecting direction of the convex portion 35 is set to the height of the convex portion 43 on the hub wheel 1 side fitted between the convex portions 35. It is made smaller than the circumferential thickness (tooth thickness) L1 of the intermediate portion in the protruding direction.

  Therefore, the total tooth thickness Σ (B1 + B2 + B3 +...) Of the convex portion 35 on the entire circumference on the shaft 12 side is replaced by the total tooth thickness Σ (A1 + A2 + A3 +) of the convex portion 43 (convex tooth) on the hub wheel 1 side.・ It is set smaller than. As a result, the shear area of the convex portion 43 on the hub wheel 1 side can be increased, and the torsional strength can be ensured. And since the tooth thickness of the convex part 35 is small, a press-fit load can be made small and a press-fit property can be aimed at. When making the sum total of the circumferential thickness of the convex part 35 smaller than the sum total of the circumferential direction thickness in the other convex part 43, the circumferential direction thickness L2 of all the convex parts 35 is the convex part adjacent to the circumferential direction. It is not necessary to make it smaller than the circumferential dimension L1 between 35. That is, among the plurality of convex portions 35, even if the circumferential thickness of the arbitrary convex portion 35 is the same as the circumferential dimension between the convex portions adjacent in the circumferential direction, it is larger than the circumferential dimension. However, it is sufficient if the sum is small.

  In addition, although the convex part 35 in Fig.11 (a) is made into the trapezoid cross section (Mt. Fuji shape), as a shape of the convex part 35, as shown in FIG.11 (b), an involute tooth shape may be sufficient.

  The shaft press-fitting guide structure M1 may be as shown in FIG. In FIG. 12 (a), the end of the guide recess 44a on the concave-convex fitting structure M side is an inclined surface 77b that is inclined to reduce the diameter along the press-fit direction (press-fit progress direction). That is, the inclination angle θ of the inclined surface 77b is, for example, about 45 °.

  12 (b) and 12 (c), the radial depth dimension of the guide recess 44a is reduced along the press-fitting direction. In FIG. 12B, the end portion on the concave-convex fitting structure M side is a flat surface 77a orthogonal to the press-fitting direction, and in FIG. 12C, the end portion on the concave-convex fitting structure M side is the press-fitting direction (press-fit). The inclined surface 77b is inclined along the traveling direction.

  If the end of the guide recess 44a on the uneven fitting structure side is a flat surface 77a orthogonal to the press-fitting direction, the shaft 12 is received by the flat surface 77a when the shaft 12 is press-fitted into the hole 22. be able to. Moreover, if it is the inclined surface 77b, the convex part 35 can be stably inserted from the recessed part 44a for a guide to the recessed part 36 of the other party. Even if the radial depth of the guide concave portion 44a is reduced along the press-fitting direction, the convex portion 35 can be stably fitted from the guide concave portion 44a to the counterpart concave portion 36.

  Further, the screw structure M2 may be as shown in FIG. 13 showing the second embodiment. That is, the screw shaft 80 protrudes from the end surface 52 of the shaft portion 12 a without providing a screw hole in the shaft portion 12, and the nut member 81 is screwed onto the screw shaft 80.

  In this case, after the shaft portion 12 is press-fitted into the hole portion 22 of the hub wheel 1 to form the concave / convex fitting structure M, the screw shaft protrudes toward the tapered hole 22b side through the through hole 56 of the positioning inner wall 22c. The nut member 81 is screwed to 80. In this state, the end surface 52 of the shaft portion 12a is in contact with the end surface 53 of the positioning inner wall 22c.

  In the wheel bearing device shown in FIG. 13, the shaft portion 12 can be detached from the hub wheel 1 by removing the nut member 81 from the screw shaft 80. At this time, for example, a pulling force can be applied through the end surface of the screw shaft 80 or the like.

  From the state in which the outer ring 5 is detached from the hub wheel 1, for example, the hub wheel 1 and the outer ring 5 can be connected again using the nut member 81. That is, as shown in FIG. 10A, the convex portion 35 of the shaft portion 12 is fitted into the guide concave portion 44a. Thereby, the phase of the male spline 41 on the shaft portion 12 side and the female spline 42 of the hub wheel 1 formed by the previous press-fitting match. At this time, as shown in FIG. 4A and the like, a radial gap C1 is formed between the top of the projection 35 and the bottom of the guide recess 44a.

  In this state, the nut member 81 is screwed onto the screw shaft 80, and the nut member 81 is screwed with respect to the screw (screwing of the screw structure M2). As a result, as shown in FIG. 10B, the shaft portion 12 is fitted into the hub wheel 1, and finally, as shown in FIG. It contacts the end surface 36a. As a result, as in the previous press-fitting, the concave-convex fitting structure M in which the entire concave portion fitting portion of the convex portion 35 is in close contact with the corresponding concave portion 36 can be reliably configured.

  By the way, in the said embodiment, while forming the spline 41 which comprises the convex part 35 in the axial part 12 side, hardening processing is given with respect to the spline 41 of this axial part 12, and the internal diameter surface of the hub wheel 1 is unhardened ( Raw materials). On the other hand, as shown in the third embodiment of FIG. 14, the spline 61 (consisting of the ridges 61a and the ridges 61b) is formed on the inner surface of the hole portion 22 of the hub wheel 1 by a hardening process. In addition, the shaft portion 12 may not be subjected to a curing process. The spline 61 can also be formed by various processing methods such as broaching, cutting, pressing, and drawing, which are publicly known means. Further, various heat treatments such as induction hardening and carburizing and quenching can be employed as the thermosetting treatment.

  In this case, the intermediate portion in the protruding direction of the convex portion 35 corresponds to the position of the concave portion forming surface (the outer diameter surface of the shaft portion 12) before the concave portion is formed. That is, the diameter dimension (minimum diameter dimension of the convex portion 35) D4 connecting the vertices of the convex portion 35 which is the convex portion 61a of the spline 61 is smaller than the outer diameter dimension D6 of the shaft portion 12, and the concave portion 61b of the spline 61 is formed. The diameter dimension (inner diameter dimension of the inner diameter surface of the fitting hole between the convex portions) D5 is set to be larger than the outer diameter dimension D6 of the shaft portion 12. That is, D4 <D6 <D5.

  If the shaft portion 12 is press-fitted into the hole portion 22 of the hub wheel 1, the concave portion 36 into which the convex portion 35 is fitted can be formed on the outer peripheral surface of the shaft portion 12 by the convex portion 35 on the hub wheel 1 side. Thereby, the whole fitting contact part 38 of the convex part 35 and the recessed part fitted to this is closely_contact | adhered.

  Here, the fitting contact portion 38 is a range B shown in FIG. 14B, and is a range from the middle of the mountain shape to the top of the mountain in the cross section of the convex portion 35. Further, a gap 62 is formed on the outer diameter side of the outer peripheral surface of the shaft portion 12 between the adjacent convex portions 35 in the circumferential direction.

  Even in the case shown in FIG. 14, it is preferable to provide the shaft press-fitting guide structure M1. In this case, a guide recess 44b may be provided on the shaft portion 12 side. Further, a radial gap C1 is formed between the top of the convex portion 35 and the bottom of the guide concave portion 44a, or a circumferential gap C2 between the side portion of the convex portion 35 and the side portion of the guide concave portion 44a, C2 can be formed, and further, the radial gap C1 and the circumferential gaps C2 and C2 can be formed.

  Even in the case shown in FIG. 14, since the protruding portion 45 is formed by press-fitting, it is preferable to provide a storage portion 57 for storing the protruding portion 45. Since the protruding portion 45 is formed on the mouse side of the shaft portion 12, the storage portion is provided on the hub wheel 1 side.

  As described above, the convex portion 35 of the concave-convex fitting structure M is provided on the inner diameter surface 37 of the hole portion 22 of the hub wheel 1, and the hardness of the axial end portion of the convex portion 35 is set to the outer diameter of the shaft portion 12 of the outer ring 5. In the case of press-fitting higher than the portion, it is not necessary to perform the hardness treatment (heat treatment) on the shaft portion side, so that the productivity of the outer joint member (outer ring 5) of the constant velocity universal joint is excellent.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, as the shape of the convex portion 35 of the concave-convex fitting structure M, FIG. In the embodiment shown in FIG. 2, the cross section is triangular, and in the embodiment shown in FIG. 11A, the cross section is trapezoidal (mountain shape), but other shapes such as a semicircular shape, a semielliptical shape, and a rectangular shape are available. The area of the convex part 35, the number, the circumferential arrangement pitch, and the like can be arbitrarily changed. That is, it is not necessary to form the spline 41, and the convex portion (convex tooth) 41a of the spline 41 to be the convex portion 35 of the concave-convex fitting structure M, and it may be a key or a curved wave. It may form a mating surface of the mold. In short, the convex portion 35 disposed along the axial direction can be press-fitted into the mating side, and the concave portion 36 can be formed on the mating side with the convex portion 35 so as to closely fit the convex portion 35. It is only necessary that the entire fitting contact portion 38 between the portion 35 and the concave portion fitted thereto is in close contact, and that rotational torque can be transmitted between the hub wheel 1 and the constant velocity universal joint 3.

  The hole portion 22 of the hub wheel 1 may be a deformed hole such as a polygonal hole other than a circular hole, and the cross-sectional shape of the end of the shaft portion 12 fitted into the hole 22 is also a polygon other than a circular cross section. It may be an irregular cross section. Furthermore, when the shaft portion 12 is press-fitted into the hub wheel 1, only the press-fitting start end portion of the convex portion 35 needs to be harder than the portion where the concave portion 36 is formed. There is no. In FIG. 3 and the like, the gap 40 is formed, but the gap 40 between the convex portions 35 may bite into the inner diameter surface 37 of the hub wheel 1. Note that the hardness difference between the convex portion 35 side and the concave portion forming surface side formed by the convex portion 35 is preferably 20 points or more in HRC, but 20 points if the convex portion 35 can be press-fitted. It may be less.

  Although the end surface (press-fit start end) of the convex portion 35 is a surface orthogonal to the axial direction in the embodiment, it may be inclined at a predetermined angle with respect to the axial direction. In this case, it may be inclined from the inner diameter side toward the outer diameter side toward the anti-convex portion side or inclined toward the convex portion side.

  Furthermore, you may provide the small recessed part arrange | positioned by the predetermined pitch along the circumferential direction in the internal diameter surface 37 of the hole 22 of the hub wheel 1. FIG. The small recess needs to be smaller than the volume of the recess 36. By providing such a small recess, the press-fit property of the protrusion 35 can be improved. That is, by providing the small concave portion, the capacity of the protruding portion 45 formed when the convex portion 35 is press-fitted can be reduced, and the press-fit resistance can be reduced. Moreover, since the protrusion part 45 can be decreased, the volume of the storage part 57 can be reduced, and the workability of the storage part 57 and the strength of the shaft part 12 can be improved. Various shapes such as a semi-elliptical shape and a rectangular shape can be adopted as the shape of the small concave portion, and the number can be arbitrarily set.

  A roller may be used as the rolling element 30 of the bearing 2. In the above-described embodiment, the third generation wheel bearing device is shown. However, the first generation, the second generation, or the fourth generation may be used. In addition, when press-fitting the convex portion 35, even if the side where the concave portion 36 is formed is fixed and the side where the convex portion 35 is formed is moved, the side where the convex portion 35 is formed is reversed. It may be fixed and the side where the recess 36 is formed may be moved or both may be moved. In the constant velocity universal joint 3, the inner ring 6 and the shaft 10 may be integrated via the concave / convex fitting structure M described in the above embodiments.

  The sealing material interposed between the seat surface 60a of the bolt member 54 of the screw structure M2 for fixing the hub wheel 1 and the shaft portion 12 and the positioning inner wall 22c is the seat surface of the bolt member 54 in the above embodiment. The resin is applied to the 60a side, but conversely, the resin may be applied to the positioning inner wall 22c side. Further, resin may be applied to the seating surface 60a side and the positioning inner wall 22c side. When the bolt member 54 is screwed, such a sealing material is omitted if the seat surface 60a of the bolt member 54 and the bottom surface of the recessed portion 51 of the positioning inner wall 22c are excellent in adhesion. It is also possible to do. That is, it is possible to improve the adhesiveness of the bolt member 54 with the seating surface 60a by grinding the bottom surface of the recessed portion 51. Of course, the sealing material can be omitted if the adhesiveness can be exhibited even in a so-called turning finish state without grinding the bottom surface of the concave portion 51.

  As shown in FIGS. 4A, 4B, and 4C, the guide recesses 44a are formed with gaps C1 and C2 between the protrusions 35. It is only necessary that the misalignment or the tilt of the core does not occur at the time of press-fitting, and the convex part 35 presses against the inner surface of the guide concave part 44a so as not to increase the press-fitting load. Further, the axial length of the guide recess 44a can be arbitrarily set, and if it is long, it is preferable for alignment, but the upper limit is limited by the axial length of the hole 22 of the hub wheel 1. On the contrary, if the axial length of the hole 22 of the hub wheel 1 is short, the hub wheel 1 may not function as a guide and may cause misalignment or tilt. For this reason, it is necessary to determine the axial length of the guide recess 44a in consideration of these.

  Moreover, the cross-sectional shape of the guide recess 44a is not limited to that shown in FIG. Various changes can be made according to the cross-sectional shape and the like of the convex portion 35. The number of guide recesses 44a may be smaller or larger than the number of projections 35 without matching the number of projections 35. In short, it is only necessary that some convex portions 35 are fitted in some guide concave portions 44a so that the phase of the convex portions 35 coincides with the phase of the concave portion 36 formed by the previous press-fitting.

  The inclination angle θ of the inclined surface 77b at the end of the guide recess 44a and the inclination angle θ1 of the bottom of the guide recess 44a can be arbitrarily changed. If the inclination angle θ of the inclined surface 77b is close to 90 °, it becomes functionally the same as the flat surface 77a orthogonal to the press-fitting direction, and if the inclination angle θ is small, the guide recess 44a becomes longer, and the uneven fitting structure M The axial length of is shortened. Moreover, if the inclination | tilt angle (theta) 1 of a bottom part becomes large, the structure of the recessed part 44a for guides will become difficult, and if it is small conversely, the function in the case of making it incline cannot be exhibited. For this reason, it is necessary to set the inclination angles θ and θ1 in consideration of these.

It is a longitudinal cross-sectional view of the wheel bearing apparatus which shows 1st Embodiment of this invention. It is an expanded longitudinal cross-sectional view of the said uneven | corrugated fitting structure. The uneven | corrugated fitting structure of the said wheel bearing apparatus is shown, (a) is the ZZ sectional view taken on the line of FIG. 2, (b) is the X section enlarged view of (a). The shaft part press-fit guide structure of the said wheel bearing apparatus is shown, (a) is the WW line cross section of FIG. 2, (b) is an expanded sectional view which shows the 1st modification of a shaft part press-fit guide structure. (C) is an expanded sectional view which shows the 2nd modification of an axial part press-fit guide structure. It is a principal part enlarged view of the said wheel bearing apparatus. The sealing member which seals the clearance gap between the mouse | mouth part of the outer ring | wheel of the said wheel bearing apparatus and the caulking part of a hub ring is shown, (a) is an expanded sectional view when an O-ring is used, (b) FIG. 3 is an enlarged cross-sectional view when a gasket is used. It is sectional drawing which shows the decomposition | disassembly state of the said wheel bearing apparatus. It is sectional drawing which shows the isolation | separation method of an uneven | corrugated fitting structure. It is sectional drawing which shows the repressing method. The re-pressing method is shown, (a) is a cross-sectional view showing a state immediately before press-fitting, (b) is a cross-sectional view showing the press-fitting process, and (c) is a cross-sectional view showing a press-fitting completion state. It is sectional drawing which shows the modification of an uneven | corrugated fitting structure. The shaft part press fit guide structure is shown, (a) is a sectional view of the first modification, (b) is a sectional view of the second modification, and (c) is a sectional view of the third modification. It is sectional drawing of the wheel bearing apparatus which shows 2nd Embodiment of this invention. The wheel bearing apparatus which shows 3rd Embodiment of this invention is shown, (a) is a cross-sectional view. (B) is the Y section enlarged view of (a). It is sectional drawing of the conventional wheel bearing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hub wheel 2 Bearing 3 Constant velocity universal joint 11 Mouse | mouth part 12 Shaft part 22 Hole 22c Positioning inner wall 24 Inner ring 26, 27 Outer raceway surface 28, 29 Inner raceway surface 31 Clamping part 35 Convex part 36 Concave part 38 Fitting contact Part 44a Guide recess 45 Overhang portion 50 Screw hole 52 End surface 57 Storage portion 58 Clearance 59 Seal member 60a Seat surface M Concavity and convexity fitting structure M1 Shaft portion press-fitting guide structure M2 Screw structure

Claims (17)

The hub wheel, double row rolling bearing, and constant velocity universal joint are unitized, and the hub wheel and the shaft portion of the outer joint member of the constant velocity universal joint that is inserted into the hole of the hub wheel are unevenly fitted. A wheel bearing device separably coupled through a structure,
A convex portion extending in the axial direction provided on one of the outer diameter surface of the shaft portion of the outer joint member and the inner diameter surface of the hole portion of the hub ring is press-fitted into the other along the axial direction, and the convex portion on the other side. Forming a concave portion that closely fits to the convex portion, and constitutes the concave / convex fitting structure in which the entire fitting contact portion between the convex portion and the concave portion is in close contact, and the concave / convex fitting structure has an axial pulling force. A wheel bearing device, characterized in that an inner wall for positioning is provided in a hole portion of a hub wheel, which allows separation by application and restricts press-fitting by contact of an end surface of the shaft portion of the outer joint member on the side opposite to the joint.   The wheel bearing device according to claim 1, wherein the hub wheel and the shaft portion of the outer joint member are fixed through a screw structure.   The wheel bearing device according to claim 2, wherein the screw structure can be press-fitted by screwing at least at the time of re-press-fitting.   The outer joint member includes a mouth portion in which the inner joint member is housed, and the shaft portion protruding from the bottom portion of the mouth portion, and an end portion of the hub wheel is crimped to be fitted on the hub wheel. The wheel bearing device according to any one of claims 1 to 3, wherein a preload is applied to an inner ring of the rolling bearing.   The wheel bearing device according to claim 4, wherein a gap is provided between a mouth portion of the outer joint member and a crimping portion formed by crimping an end portion of the hub wheel.   The wheel bearing device according to claim 5, wherein a seal member that seals a gap between the mouth portion of the outer joint member and the caulking portion of the hub wheel is disposed. 7. The sealing material according to claim 2, wherein a seal member is interposed between a seating surface of a bolt member having a screw structure for fixing the hub wheel and the shaft portion of the outer joint member, and the positioning inner wall. The wheel bearing apparatus of any one of Claims.   A convex portion of the concave-convex fitting structure is provided on the shaft portion of the outer joint member, and at least the hardness of the axial end portion of the convex portion is made higher than the inner diameter portion of the hole portion of the hub wheel so that the shaft portion is the hub wheel. By press-fitting into the hole portion of the convex portion from the axial end portion side, a concave portion that closely fits to the convex portion is formed on the inner diameter surface of the hole portion of the hub wheel at the convex portion, and the concave-convex fitting structure is formed. The wheel bearing device according to any one of claims 1 to 7, wherein the wheel bearing device is configured.   The wheel bearing device according to claim 8, wherein a storage portion that stores a protruding portion generated by forming the concave portion by the press-fitting is provided on the outer diameter side of the shaft portion on the opposite joint side than the concave-convex fitting structure.   The inner diameter dimension of the inner diameter surface of the hole of the hub ring is set to be smaller than the maximum diameter dimension of the circle connecting the apexes of the projections and larger than the maximum diameter dimension of the recesses of the shaft outer diameter surface between the projections. The wheel bearing device according to claim 8 or 9, wherein the wheel bearing device is characterized.   A convex portion of the concave-convex fitting structure is provided on the inner diameter surface of the hole portion of the hub wheel, and at least the hardness of the axial end portion of the convex portion is higher than the outer diameter portion of the shaft portion of the outer joint member of the constant velocity universal joint. The convex portion on the hub wheel side is press-fitted into the shaft portion of the outer joint member from the axial end side thereof, so that the convex portion is formed on the outer diameter surface of the shaft portion of the outer joint member. The wheel bearing device according to any one of claims 1 to 7, wherein the concave-convex fitting structure is formed by forming a concave portion to be closely fitted.   The wheel bearing device according to claim 11, wherein a housing portion for housing a protruding portion generated by forming the concave portion by the press-fitting is provided on an inner diameter surface of the hole portion of the hub wheel.   The diameter dimension of the arc connecting the vertices of the plurality of convex portions of the shaft hole is made smaller than the outer diameter size of the shaft portion of the outer joint member, and the inner diameter size of the hole inner diameter surface between the convex portions is changed to the shaft portion of the outer joint member. The wheel bearing device according to claim 11 or 12, wherein the outer diameter dimension of the wheel bearing device is larger.   The sum of the circumferential thicknesses of the projecting direction intermediate portions of the convex portions is the sum of the circumferential thicknesses at positions corresponding to the intermediate portions of the mating convex portions that fit between the convex portions adjacent in the circumferential direction. The wheel bearing device according to any one of claims 1 to 13, wherein the wheel bearing device is also made smaller.   The wheel bearing device according to any one of claims 1 to 14, wherein the concave-convex fitting structure is arranged at a position directly below the raceway surface of the rolling bearing. The wheel bearing device according to any one of claims 1 to 15, wherein the shaft press-fitting guide structure is provided on a convex press-fitting start side.   The wheel bearing device according to any one of claims 1 to 16, wherein a hardness difference between the convex portion side and the concave portion forming side is set to 20 or more in HRC.

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