JP4467480B2 - Wheel bearing device and caulking method thereof - Google Patents

Description

  The present invention relates to a wheel bearing device that rotatably supports a wheel serving as a driving wheel of an automobile or the like, and a caulking method thereof.

  Conventionally, what is shown in FIG. 5 is proposed as a wheel bearing device for driving wheel support (for example, patent document 1). This is because the balls 25 are interposed in double rows between the raceway surfaces 23 and 24 where the outer member 21 and the inner member 22 face each other, and the inner member 22 is a hub wheel having a wheel mounting hub flange 29a on the outer periphery. 29 and an inner ring 30 fitted to the outer periphery of the inboard side end of the hub wheel 29. The stem portion 33a of the outer ring 33 of the constant velocity joint is inserted into the central hole 31 of the hub wheel 29 and is splined, and the step surface 33b of the constant velocity joint outer ring 33 is pressed against the inboard side end surface 30a of the inner ring 30. It is done. In this state, the inner member 22 is tightened by the constant velocity joint outer ring 33 and the nut 34 by screwing the nut 34 into the tip of the stem portion 33a.

In this proposed example, the inner ring 30 is externally fitted to the step 35 formed on the outer periphery of the end portion on the inboard side of the hub wheel 29, and the step portion 36 is formed on the inner periphery of the end portion on the inboard side of the inner ring 30. the inboard end of the wheel hub 29 by expanded deformation on the outer diameter side that are crimped to the stepped portion 36 of the inner ring 30.
JP-A-9-164803

However, the above-described wheel bearing device has the following problems.
(1) Since the caulking portion 29b of the hub wheel 29 is large, the radial step of the step portion 36 formed at the end portion on the inboard side of the inner ring 30 is shown in FIG. The radius difference needs to be about 5 to 7 mm. When the step of the stepped portion 36 is increased in this way, the area of the inboard side end surface 30a of the inner ring 30 is reduced, so that the contact surface pressure with the stepped surface 33b of the constant velocity joint outer ring 33 is increased. Therefore, it causes wear and abnormal noise.
(2) If the caulking portion 29b of the hub ring 29 is to be stored inside (outboard side) from the inboard side end of the inner ring 30, the axial length of the step portion 36 of the inner ring 30 is set to 7 as shown in FIG. It needs to be about ~ 8mm. As described above, when the axial length of the inner ring step portion 36 is increased, the inner ring step portion 36 tends to be positioned on the extended line of the ball contact angle, and deformation of the inner ring due to a load load during operation increases, resulting in a short life. there is a possibility. Further, when the axial length of the inner ring step portion 36 is increased, the fitting length (area) of the inner ring 30 with respect to the hub ring 29 is reduced accordingly, so that inner ring creep occurs and the bearing life may be reduced. . These problems can be avoided by increasing the width of the entire inner ring, but this requires extra space in the axial direction.
(3) Further, since the caulking portion 29b of the hub wheel 29 is large, the caulking tool interferes with the inner ring 30 in the swing caulking process, and the machining is difficult.

  An object of the present invention is to prevent the inner ring from coming off during the assembly process to the vehicle without adversely affecting the bearing function, to enable caulking with a particularly low working force, and to avoid interference with the caulking die. It is an object of the present invention to provide a wheel bearing device and a caulking method for the same that can reduce the restriction of the product shape that occurs in the above.

The wheel bearing device of the present invention includes an outer member having a double-row raceway surface on the inner periphery, an inner member having a raceway surface facing these raceway surfaces, and a double-row interposed between the opposing raceway surfaces. A rolling ring, and the inner member has a hub flange for mounting a wheel on the outer periphery and a through hole in the center, and an inner ring fitting provided on the outer periphery of the inboard side end of the hub ring. The inner ring is fitted to the surface portion, the hub ring and the inner ring form the raceway surface of each row , the hub ring is coupled to the outer ring of the constant velocity joint, and the end face facing the inboard side of the inner ring is the The wheel bearing device for supporting a driving wheel, which is pressed against a step surface facing the outboard provided on the outer ring of the constant velocity joint, has the following configuration.
That is, the inner ring has an inboard side end on the inner peripheral surface that extends to the end surface on the inboard side of the inner ring, and the inner ring has a depth that is small enough to prevent the inner ring from coming off during the assembly process to the vehicle. A step portion is provided, and a caulking portion that engages with a step surface of the inner ring facing the axial direction is provided by caulking processing of the hub ring, and the caulking portion does not protrude from the end surface of the inner ring. Shall. The through hole of the hub wheel has a spline groove that meshes with a spline on the outer periphery of the stem portion of the constant velocity universal joint, and a general diameter portion in which the spline groove is formed on the inner peripheral surface of the through hole. The inboard side portion is a two-stage step consisting of a large diameter step portion at the end of the inboard side and an intermediate diameter step portion having a smaller diameter than the large diameter step portion and a larger diameter than the general diameter portion. The shape is attached. Further, the inner periphery to become a caulking type pressing portion is a portion, tapered portions a transfer surface spread open mouth side of the pressing surface of the pressing clamp type of the crimping portion in the larger diameter section of difference unit The inclination angle of the tapered portion with respect to the hub wheel central axis is 5 to 60 °. The caulking die pressing portion of the hub wheel serves as a transfer surface of the pressing surface of the caulking die when, for example, a caulking die whose outer periphery is a tapered pressing surface is used. .

According to this configuration, since the step portion is provided on the inner peripheral surface of the inner ring and the caulking portion by the caulking process of the hub wheel is engaged in the step portion, the hub of the inner ring due to the external force generated in the assembly process to the vehicle It can prevent the ring from coming off. Since the stepped portion has a very limited range of the inner periphery of the inner ring, the stepped portion can be made as small as possible while ensuring the slip-off resistance of the inner ring. For this reason, there is little decrease in the area of the end surface of the inner ring while providing the stepped portion, the increase in contact surface pressure with the step surface of the constant velocity universal joint is suppressed, and it is possible to prevent the occurrence of wear and noise due to the occurrence of inner ring creep, etc. Thus, it is possible to suppress a decrease in bearing life.
Further, since the inboard side end of the through hole has a two-stepped shape, the intermediate diameter step portion serves as a guide when inserting the stem portion of the constant velocity joint outer ring, and the assemblability is further improved.
In particular, the caulking die pressing portion, which is the portion that becomes the inner periphery of the caulking portion in the large diameter step portion, is a tapered portion that widens the opening side, so that the caulking portion is caulked with the caulking die. When machining, caulking can be performed with a small machining load. For this reason, the load at the time of the caulking process on the raceway surface of the bearing and the rolling element can be reduced, and the caulking process can be performed at a low cost by using an inexpensive equipment having a small capacity.
The smaller the inclination angle of the pressing surface of the caulking die, the lower the load that can be applied, but the smaller the inclination angle, the deeper the inner part of the caulking part becomes. The leading portion of the caulking die that is the caulking die portion to be lengthened becomes longer. For this reason, it is necessary to avoid interference with the end face on the intermediate diameter step portion in the large diameter step portion of the hub wheel through hole, which restricts the product shape. For this reason, the setting range of 5 to 60 ° is preferable as the inclination angle of the pressing surface which can avoid the interference and can perform the caulking process with a low processing load.
Thus, in this wheel bearing device, it is possible to prevent the inner ring from being lost in the assembly process to the vehicle without adversely affecting the bearing function.

  In the present invention, the hardness of the caulking portion of the hub wheel may be HRC28 or less. If the hardness of the crimped portion is reduced to HRC28 or less, the crimping process can be performed with a lower processing load.

  The caulking method of the caulking portion of the wheel bearing device of the present invention is the caulking processing method of the caulking portion in the wheel bearing device of the invention, wherein the caulking portion in the wheel bearing device is Before the caulking process, a caulking die in which the inner diameter surface is a cylindrical portion that becomes a part of the large-diameter stepped portion and the outer periphery of the tip is a tapered pressing surface is used. The inclination angle of the pressing surface with respect to the axis is set to 5 to 60 °, and the cylindrical portion is expanded in diameter by pressing the pressing surface of the caulking die against the opening edge of the inner periphery of the cylindrical portion. The above-mentioned caulking portion is used.

  According to this configuration, since the caulking die whose outer periphery is a tapered pressing surface is used, caulking can be easily performed with a low processing load. In addition, since the inclination angle of the pressing surface of the caulking die is set to 5 ° or more, the tip introduction portion of the caulking die can be shortened, and the product generated to avoid interference between the product and the caulking die The restriction on the shape can be reduced, and since it is set to 60 ° or less, caulking can be performed with a low processing force.

  In the present invention method, the hardness of the pressing surface of the caulking die may be HRC30 or higher. When the hardness of the pressing surface of the caulking die is HRC30 or higher, the caulking process that causes plastic deformation to the caulking portion can be performed, and continuous caulking can be performed.

  In the method of the present invention, the pressing surface of the caulking die may have a surface roughness Ra of 1 μm or less. When the surface roughness of the pressing surface of the caulking die is reduced to Ra 1 μm or less, the caulking part can be caulked smoothly without causing appearance or processing problems due to galling or adhesion. it can.

The wheel bearing device of the present invention includes an outer member having a double-row raceway surface on the inner periphery, an inner member having a raceway surface facing these raceway surfaces, and a double-row interposed between the opposing raceway surfaces. A rolling ring, and the inner member has a hub flange for mounting a wheel on the outer periphery and a through hole in the center, and an inner ring fitting provided on the outer periphery of the inboard side end of the hub ring. The inner ring is fitted to the surface portion, the hub ring and the inner ring form the raceway surface of each row , the hub ring is coupled to the outer ring of the constant velocity joint, and the end face facing the inboard side of the inner ring is the In a wheel bearing device for supporting a driving wheel that is pressed against a step surface facing an outboard side provided on an outer ring of a constant velocity joint, an inboard side end of the inner ring is connected to an inboard side end of the inner ring. Following to the end face, the inner peripheral edge of the end face, The small depth of the stepped portion to the extent capable of preventing the inner ring of the omission in the assembly process to both provided, pressurized to engage the stepped surface facing in the axial direction of the step portion of the inner ring by caulking of the wheel hub A tightening portion is provided, and the caulking portion does not protrude from the end surface of the inner ring, and the through hole of the hub wheel has a spline groove on the inner peripheral surface that meshes with a spline on the outer periphery of the stem portion of the constant velocity universal joint. Then, the portion on the inboard side of the inner diameter surface of the through hole with respect to the general diameter portion where the spline groove is formed has a large diameter step portion on the inboard side end, and a diameter smaller than the large diameter step portion. A two-step stepped shape formed by an intermediate diameter step portion having a larger diameter than the general diameter portion, and a crimping die pressing portion that is a portion that becomes an inner periphery of the crimp portion in the large diameter step portion Since the opening is tapered, the bearing functions Without affecting, it can prevent omission inner ring in the assembly process of the vehicle. Further, since the inclination angle of the tapered portion with respect to the central axis of the hub wheel is 60 ° or less, it is possible to perform caulking with a low processing force, and since the inclination angle is 5 ° or more, the tip of the caulking die is pressed. The length of the introduction portion that enters the deeper side than the tightening portion can be shortened, and the restriction on the product shape that occurs to avoid interference between the product and the crimping mold can be reduced.

  The caulking method of the caulking portion of the wheel bearing device of the present invention is a caulking method of the caulking portion in the wheel bearing device of the present invention, wherein the caulking portion in the wheel bearing device is Before the caulking process, a caulking die in which the inner diameter surface is a cylindrical portion that becomes a part of the large-diameter stepped portion and the outer periphery of the tip is a tapered pressing surface is used. The inclination angle of the pressing surface with respect to the axis is set to 5 to 60 °, and the cylindrical portion is expanded in diameter by pressing the pressing surface of the caulking die against the opening edge of the inner periphery of the cylindrical portion. Therefore, it is possible to perform caulking with a low processing force and reduce the restriction on the product shape that occurs to avoid interference between the product and the caulking die. it can.

An embodiment of the present invention will be described with reference to FIGS. This embodiment is a third generation type inner ring rotation type and is applied to a wheel bearing device for driving wheel support. In this specification, the side closer to the outer side in the vehicle width direction of the vehicle when attached to the vehicle is referred to as the outboard side, and the side closer to the center of the vehicle is referred to as the inboard side.
The wheel bearing device includes an outer member 1 having a double-row raceway surface 3 formed on the inner periphery, an inner member 2 having a raceway surface 4 opposed to each raceway surface 3, and these outer members 1. And the double-row balls 5 interposed between the raceway surfaces 3 and 4 of the inner member 2. This wheel bearing device is a double-row angular ball bearing type, and the balls 5 are held by a cage 6 for each row. Each of the track surfaces 3 and 4 has an arc shape in cross section, and each of the track surfaces 3 and 4 is formed so that the ball contact angle θ is aligned with the back surface. Both ends of the bearing space between the outer member 1 and the inner member 2 are sealed by seals 7 and 8, respectively.

The outer member 1 is a member on the fixed side, and has a flange 1a attached to the knuckle in the suspension device (not shown) of the vehicle body on the outer periphery, and the whole is an integral part.
The inner member 2 is a rotating member, and is fitted to the outer periphery of the hub wheel 9 having a hub flange 9a for wheel mounting on the outer periphery and the inboard side end of the shaft portion 9b of the hub wheel 9. The inner ring 10 made. The hub ring 9 and the inner ring 10 are formed with the raceway surfaces 4 in each row. The hub wheel 9 has a through hole 11 in the center.

  As shown in enlarged sectional views in FIG. 2 and FIG. 4, a stepped inner ring fitting surface portion having a smaller diameter than the outer periphery of the other portion of the hub wheel 9 is provided on the outer periphery of the inboard side end of the hub wheel 9. 15 is formed, and the inner ring 10 is fitted to the inner ring fitting surface portion 15. A stepped portion 16 having a depth corresponding to the inner peripheral edge of the end surface 10a is provided at the inboard side end of the inner ring 10 up to the end surface 10a on the inboard side of the inner ring 10. The step portion 16 is located on the inboard side with respect to the straight line L that forms the contact angle θ of the raceway surface 4 of the inner ring 10. The inner surface of the stepped portion 16 has a shape including a straight portion 16a formed of a cylindrical surface and a stepped surface 16b facing in the axial direction. The step surface 16b is an inclined surface whose cross section along the bearing axial direction is a straight line or a curve. The step surface 16b may be a surface perpendicular to the axial direction.

  At the inboard side end of the hub wheel 9, a caulking portion 9 c that engages with a step surface 16 b facing the axial direction of the step portion 16 of the inner ring 10 by caulking is provided. 2 shows a state before the crimping process of the crimping portion 9c, and FIG. 4 shows a state after the crimping process. The caulking portion 9 c substantially fills the inside of the step portion 16 of the inner ring 10, but does not protrude from the end surface 10 a of the inner ring 10. The caulking portion 9c has a hardness of HRC28 or less.

  The crimping process is performed using a crimping die 18 shown in FIG. The caulking die 18 has a pressing surface 18a whose outer periphery is tapered, and this pressing surface 18a is pressed against the opening edge of the inner periphery of the cylindrical portion of the caulking portion 9c to form the cylindrical shape of the caulking portion 9c. The caulking process is performed by caulking the part in an expanded state. The inclination angle β with respect to the axis of the pressing surface 18a of the caulking die 18 is 5 to 60 °.

  The hardness of the pressing surface 18a of the caulking die 18 needs to be at least larger than the caulking portion 9c in order to enable caulking and continuous machining. Therefore, in this embodiment, steel, cemented carbide or the like having a hardness of HRC30 or higher is used as the material of the crimping mold 18, for example. In addition to this, the caulking die 18 may have a hardness of the pressing surface 18a of HRC30 or higher by using a material having a required hardness by surface treatment. The surface roughness of the pressing surface 18a in the caulking die 18 is set to Ra1 μm or less.

  The inner peripheral surface of the through hole 11 of the hub wheel 9 has a general diameter portion 11a in which a spline groove 11aa is formed. The portion on the inboard side with respect to the general diameter portion 11a includes a large diameter step portion 11b at the end of the inboard side and a groove bottom diameter of the spline groove 11aa of the general diameter portion 11a having a smaller diameter than the large diameter step portion 11b. It has a two-step stepped shape including an intermediate diameter step portion 11c having a larger diameter. The intermediate diameter step portion 11 c is set to a position B deeper in the axial direction than the axial position A of the step portion 16 of the inner ring 10.

In assembling the wheel bearing device to the vehicle, the stem portion 13a of the outer ring 13 serving as one joint member of the constant velocity joint 12 is inserted into the through hole 11 of the hub wheel 9, and the spline on the outer periphery of the stem portion 13a. 13 aa and the spline groove 11 aa on the inner peripheral surface of the through hole 11 are spline-fitted, and the constant velocity joint outer ring 13 is coupled to the inner member 2 by tightening a nut 14 that is screwed to the tip of the stem portion 13 a. At this time, the step surface 13 b facing the outboard side provided in the constant velocity joint outer ring 13 is pressed against the end surface 10 a facing the inboard side of the inner ring 10, and the inner member 2 is formed by the constant velocity joint outer ring 13 and the nut 14. Is tightened.
The hub flange 9a for wheel attachment is located at the end of the hub wheel 9 on the outboard side, and a wheel (not shown) is attached to the hub flange 9a with a bolt 17 via a brake rotor.

According to the wheel bearing device of this configuration, the step portion 16 is provided on the inner peripheral surface of the inner ring 10 and the caulking portion 9c obtained by caulking the hub wheel 9 is engaged in the step portion 16, so that the vehicle It is possible to prevent the inner ring 10 from coming off from the hub wheel 9 due to an external force generated in the assembly process. Since the stepped portion 16 has a very limited range of the inner periphery of the inner ring 10, the stepped portion 16 can be made as small as possible while ensuring the slip-off resistance of the inner ring 10. For this reason, there is little decrease in the area of the end surface of the inner ring 10 while providing the stepped portion 16, the increase in contact surface pressure with the step surface 13b of the constant velocity joint outer ring 13 is suppressed, and wear and noise due to the occurrence of inner ring creep etc. Occurrence can be prevented and bearing life reduction can be suppressed.
The through hole 11 of the hub wheel 9 has a portion on the inboard side with respect to the general diameter portion 11a in which the spline groove 11aa is formed, a large diameter step portion 11b on the inboard side end, and a smaller diameter than the large diameter step portion 11b. Therefore, when the intermediate diameter step portion 11c is inserted into the stem portion 13a of the constant velocity joint outer ring 13, the intermediate diameter step portion 11c has a two-step stepped shape. As a result, the assemblability is further improved.

  In this embodiment, since the hardness of the caulking portion 9c is HRC28 or less, the caulking process can be performed with a lower processing load. For this reason, the load by the process load with respect to the raceway surfaces 3 and 4 of a bearing and the rolling element 5 is reduced, and the said caulking process can be performed at low cost using an inexpensive equipment with small capacity.

In the caulking process, the outer periphery of the end of the caulking die 18 is a tapered pressing surface 18a, and the inclination angle β (FIG. 3) with respect to the axis of the pressing surface 18a is 5 to 60 °. The pressing surface 18a of the mold 18 is pressed against the opening edge of the cylindrical portion 11b, which is the inner diameter surface of the crimping portion 9c before the crimping process, which is a part of the large-diameter step portion 11b of the hub wheel through hole 11. Thus, the cylindrical portion 11b is swaged in an expanded state to form a swaged portion 9c as shown in FIG. 4, and from this point, swaging can be easily performed with a low processing load.
The smaller the inclination angle β of the pressing surface 18a of the caulking die 18 is, the more caulking can be performed with a lower processing load. On the other hand, when the inclination angle β is smaller, the inner surface of the caulking portion 9c is obtained. The length E of the leading end introduction portion of the caulking die 18 that enters deeper than the cylindrical portion 11b becomes longer. Therefore, in order to avoid interference between the end surface on the intermediate diameter step portion 11c side in the large diameter step portion 11b of the hub wheel through hole 9 and the crimping die 18, the product shape is restricted.
For this reason, the above-mentioned setting range of 5 to 60 ° is suitable as the inclination angle β of the pressing surface 18a that can avoid the interference and can perform caulking with a low processing load.

  Moreover, in this embodiment, since the hardness of the pressing surface 18a of the crimping die 18 is set to HRC30 or higher which is larger than the hardness of the crimping portion 9c (HRC28 or less), the above-described plastic deformation is applied to the crimping portion 9c. Caulking can be performed and continuous caulking can be performed.

  In this embodiment, the intermediate diameter step portion 11c of the hub ring through hole 11 is set to a position B deeper in the axial direction than the position A in the axial direction of the step portion 16 of the inner ring 10. Even if the inclination angle β of the abutting surface 18a is reduced and the introduction portion at the tip of the crimping die 18 is introduced beyond the crimping portion 9c, the crimping die 18 has the intermediate diameter step portion 11c. The caulking process can be performed smoothly without interfering with.

  In the above caulking process, the caulking die 18 is in contact with the caulking portion 9c with a high contact pressure, and depending on the caulking conditions, the appearance of the caulking portion 9c is impaired due to the occurrence of galling or adhesion. There is a risk, and in some cases, it may become impossible to perform crimping. However, in this embodiment, since the surface roughness of the pressing surface 18a of the caulking die 18 is Ra1 μm or less, the caulking portion 9c has a problem in appearance and processing due to galling or adhesion. The caulking process can be performed smoothly without causing the deformation.

It is sectional drawing of the wheel bearing apparatus concerning one Embodiment of this invention. It is a partial expanded sectional view before hub wheel caulking of the bearing device for the wheels. It is explanatory drawing of the hub ring caulking process of the bearing apparatus for the wheels. It is a partial expanded sectional view after hub wheel caulking of the bearing device for the wheels. It is sectional drawing of a prior art example. It is a partial expanded sectional view of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Outer member 2 ... Inner member 3 ... Outer member raceway surface 4 ... Inner member raceway surface 5 ... Ball 9 ... Hub ring 9a ... Hub flange 9c ... Clamping part 10 ... Inner ring 10a ... Inner ring end surface 11 ... through hole 11a ... general diameter portion 11aa ... spline groove 11b ... large diameter step portion 11c ... intermediate diameter step portion 13 ... constant velocity joint outer ring 13a ... constant velocity joint outer ring stem portion 13aa ... stem portion spline 15 ... inner ring fitting Surface portion 16 ... Inner ring step portion 16b ... Step surface 18 ... Caulking die 18a ... Pressing surface

Claims (5)

An outer member having a double-row raceway surface on the inner periphery, an inner member having a raceway surface facing these raceway surfaces, and a double-row rolling element interposed between the opposing raceway surfaces, The member consists of a hub wheel having a hub flange for wheel mounting on the outer periphery and a through hole in the center, and an inner ring fitted to an inner ring fitting surface portion provided on the outer periphery of the inboard side end of the hub wheel. The hub wheel and the inner ring are formed with raceways of the respective rows, and the hub ring is coupled to the outer ring of the constant velocity joint, and the end surface facing the inboard side of the inner ring is provided on the outer ring of the constant velocity joint. In the wheel bearing device for driving wheel support pressed against the step surface facing the outboard side ,
The inner ring has an inboard side end on the inner peripheral surface that extends to the end surface on the inboard side of the inner ring, and has a depth that is small enough to prevent the inner ring from coming off during the assembly process to the vehicle. A stepped portion is provided, and a crimping portion is provided that engages with a stepped surface of the inner ring facing the axial direction by crimping of the hub ring, and the crimped portion does not protrude from the end surface of the inner ring. The through hole of the hub wheel has a spline groove on the inner peripheral surface that meshes with an outer spline of the stem portion of the constant velocity universal joint, and a general diameter in which the spline groove is formed on the inner peripheral surface of the through hole. A portion on the inboard side with respect to the portion is composed of a two-step portion having a large-diameter step portion at an end of the inboard side and an intermediate-diameter step portion having a smaller diameter than the large-diameter step portion and a larger diameter than the general-diameter portion. A stepped shape and the large diameter step portion The inner circumference and press portion in a caulking mold made against portions of the tightening unit, a transfer surface of the pressing surface of the pressing clamp-type and tapered portion opening side spreads, the hub wheel center axis of the tapered portion A bearing device for a wheel, wherein an inclination angle with respect to the angle is 5 to 60 °.   2. The wheel bearing device according to claim 1, wherein the hardness of the caulking portion of the hub wheel is HRC28 or less.   3. The method for caulking the caulking portion in the wheel bearing device according to claim 1 or 2, wherein the caulking portion in the wheel bearing device has an inner surface that is large before caulking. A caulking die having a cylindrical portion which becomes a part of the diameter step portion and having a tapered pressing surface on the outer periphery of the tip is used. The inclination angle of the pressing die with respect to the axis of the pressing surface is 5 -60 °, and the pressing surface of the caulking die is pressed against the opening edge of the inner periphery of the cylindrical portion, so that the cylindrical portion is caulked in an expanded state to form the caulking portion. Clamping method for the caulking part of the bearing device for automobiles.   4. The method for caulking a caulking portion of a wheel bearing device according to claim 3, wherein the hardness of the pressing surface of the caulking die is HRC30 or more.   5. A method for caulking a caulking portion of a wheel bearing device according to claim 3 or 4, wherein a surface roughness of the pressing surface of the caulking die is Ra1 [mu] m or less.

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