JP2012228697A - Shaft member of rolling bearing device for wheel, and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently producing a cold forging having a fitting shaft part, a flange part, and a shaft part from a cylindrical material in a cold forging process, and to provide a shaft member of a rolling bearing device for a wheel, produced by the same.SOLUTION: In the method for manufacturing a shaft member 1 of a rolling bearing device for wheels in which a cylindrical fitting shaft part 30 having a recess 35 opened in the axial direction, a flange part 21 having the flange diameter larger than the diameter of the fitting shaft part, and a columnar shaft part 10 are coaxially arranged along the axial direction, a cold forging 66 integrally having the fitting shaft part 30, the flange part 21, and the shaft part 10 is formed by one forward extrusion and one forward extrusion of the cold forging process by using a columnar material 62 having the outside diameter larger than the diameter of the fitting shaft part and smaller than the flange diameter.

Description

  The present invention relates to a shaft member of a rolling bearing device for a wheel and a manufacturing method thereof.

A shaft member of a wheel rolling bearing device as a hub wheel used in a wheel rolling bearing device and a method of manufacturing the shaft member of the wheel rolling bearing device are disclosed in Patent Document 1, for example.
In addition, as for the shaft member of the rolling bearing device for wheels, the fitting shaft portion, the flange portion, and the shaft portion are arranged coaxially along the axial direction. The shaft portion is formed with a large-diameter shaft portion having a large diameter on the side close to the flange portion, and a small-diameter shaft portion having a small diameter on the side far from the flange portion.
In the manufacturing method of the shaft member of the conventional rolling bearing device for a wheel disclosed in Patent Document 1, a material having at least a large-diameter shaft portion is used, and the receiving side has an inner diameter that matches the outer diameter of the small-diameter shaft portion. The tip of the large-diameter shaft portion of the material is abutted against the punch, and the tip of the large-diameter shaft portion is pushed into the receiving punch by forward extrusion of cold forging to form a small-diameter shaft portion.

JP 2007-152413 A

  The prior art described in Patent Document 1 includes a forward extrusion process in which the tip of the large-diameter shaft portion is pushed into the receiving punch in the cold forging process to form a small-diameter shaft portion, and the outer diameter is smaller than the outer diameter of the flange portion. From a cylindrical material having a diameter, through a cold forging process 4 times or more as shown in the figure (forward extrusion and side extrusion multiple times), fitting shaft part, flange part The cold forging product provided with the shaft portion is formed, and the processing efficiency is not good. In addition, a die for each process is required, which increases processing equipment, processing time, and processing costs.

  The present invention was devised in view of such points, and efficiently produces a cold forged product having a fitting shaft portion, a flange portion, and a shaft portion from a cylindrical material in a cold forging process. And a shaft member of a rolling bearing device for a wheel manufactured by the manufacturing method.

In order to solve the above problems, the shaft member of the wheel rolling bearing device according to the present invention and the manufacturing method thereof take the following means.
A first aspect of the present invention is a method for manufacturing a shaft member of a wheel rolling bearing device in which a fitting shaft portion, a flange portion, and a shaft portion are arranged coaxially along the axial direction.
The fitting shaft portion has a cylindrical shape having a recess opening in the axial direction, the flange portion has a disk shape orthogonal to the axial direction, and a flange diameter that is a diameter in a direction orthogonal to the axial direction in the flange portion. Is larger than a fitting shaft portion diameter which is a diameter in a direction perpendicular to the axial direction of the fitting shaft portion, the shaft portion is cylindrical, and an inner ring raceway surface is formed on the outer peripheral surface, A plurality of bolt holes are formed in the flange portion in a direction perpendicular to the axial direction, and the shaft member of the wheel rolling bearing device is manufactured by cold forging.
First, using a columnar shaft-shaped material having an outer diameter larger than the fitting shaft portion diameter and smaller than the flange diameter, one axial direction of the shaft-shaped material in the first cold forging step. Extrusion is performed so that the diameter of the end portion is expanded to the flange diameter and a cylindrical portion having the diameter of the fitting shaft portion is formed at the other end portion of the shaft-shaped material.
Then, in the second cold forging step, forward extrusion is performed so as to form the concave portion and the shaft portion of the fitting shaft portion from the other axial end portion of the shaft-shaped material, and the wheel A shaft member of the rolling bearing device is formed.

  According to the first aspect of the invention, by using a cylindrical shaft-shaped material having an outer diameter that is larger than the fitting shaft portion diameter and smaller than the flange diameter, the cold forging process is performed as a single extrusion process. It is possible to perform a single forward extrusion process, and it is possible to efficiently form a cold forged product that integrally includes a shaft portion, a flange portion, and a fitting shaft portion.

  Next, 2nd invention of this invention is a manufacturing method of the shaft member of the rolling bearing apparatus for wheels which concerns on the said 1st invention, Comprising: One side flange which is a surface by the side of the said shaft part in the said flange part The surface is formed with a floating island-shaped thick portion that extends from the periphery of the shaft portion to the periphery of the bolt hole and partially thickens the axial thickness of the flange portion. The diameter of the thick part is a floating island diameter that is larger than the diameter of the fitting shaft part and smaller than the flange diameter, and using a cylindrical shaft-shaped material having an outer diameter corresponding to the floating island diameter The shaft member of the rolling bearing device for a wheel is formed in the first cold forging step and the second cold forging step.

  According to the second invention, the cold forging process is performed once by using the cylindrical shaft-shaped material having an outer diameter corresponding to the floating island diameter, further improving the rigidity at the floating island-shaped thick portion. It is possible to carry out the extrusion process and one forward extrusion process, and it is possible to efficiently form a cold forged product integrally having the shaft portion, the flange portion, and the fitting shaft portion.

Next, 3rd invention of this invention is a manufacturing method of the shaft member of the rolling bearing apparatus for wheels which concerns on the said 1st invention or 2nd invention, Comprising: The said extrusion in the said 1st cold forging process In processing, the shape of the outer peripheral surface of the flange portion and the shape of the one-side flange surface of the flange portion, the first one-side mold formed on the flange portion, the fitting shaft portion side of the flange portion And extruding using the first other side mold formed in the shape of the other side flange surface which is a surface and the shape of the outer peripheral surface of the fitting shaft portion, and the fitting from the shaft-shaped material A primary cold forged product is formed in which the outer peripheral surface of the shaft portion, the outer peripheral surface of the flange portion, the one side flange surface, and the other side flange surface are formed.
In the forward extrusion process in the second cold forging step, the shape of the outer peripheral surface of the flange portion, the shape of the one side flange surface, and the shape of the shaft portion at the tip of the one side flange surface And an outer diameter corresponding to the outer diameter of the flange portion formed in the shape of the second one-side mold, the shape of the other-side flange surface, and the shape of the outer peripheral surface of the fitting shaft portion. A substantially cylindrical intermediate die that has a hollow portion having an inner diameter corresponding to the outer diameter of the fitting shaft portion and is fitted to the second one-side die, and the substantially cylindrical intermediate die The second cold-forged product is forward-extruded using a second mold on the other side formed in the shape of the concave portion of the fitting shaft portion and can be fitted into the hollow portion of the fitting, and the fitting is carried out from the primary cold forging product. The secondary cold forging product in which the concave portion of the shaft portion and the shaft portion are formed. Forming a shaft member of the wheel rolling bearing device.

  According to the third aspect of the invention, by using a cylindrical shaft-shaped material having an outer diameter corresponding to the floating island diameter and an appropriate die, the cold forging process is performed once by extrusion and once. The cold forging product which has a shaft part, a flange part, and a fitting shaft part integrally can be formed efficiently.

  Next, 4th invention of this invention is a manufacturing method of the shaft member of the rolling bearing apparatus for wheels which concerns on the said 3rd invention, Comprising: In the said 2nd cold forging process, the said intermediate mold and the said Instead of using the second mold on the other side, a forward extrusion process is performed using an integral mold in which the intermediate mold and the second mold on the other side are integrally formed, whereby the primary cold A secondary cold forged product in which the concave portion of the fitting shaft portion and the shaft portion are formed from the forged product is formed.

  According to the fourth aspect of the present invention, a cold forged product can be formed more efficiently by using an integral mold in which the intermediate mold and the second other mold are integrally formed.

  Next, a fifth invention of the present invention relates to a wheel rolling bearing device manufactured by the method for manufacturing a shaft member of a wheel rolling bearing device according to any one of the first to fourth inventions. A shaft member that is larger than the fitting shaft portion diameter when the shaft member of the rolling bearing device for a wheel is formed in the first cold forging step and the second cold forging step; It is manufactured from a cylindrical shaft-shaped material having an outer diameter smaller than the flange diameter, and has the disk-shaped flange portion.

  According to the fifth aspect of the invention, the cold forging process is performed by one extrusion process using a cylindrical shaft-shaped material having an outer diameter larger than the fitting shaft diameter and smaller than the flange diameter. It can be realized by a forward extrusion process, and has a shaft portion, a flange portion, and a fitting shaft portion integrally, and a shaft member of a wheel rolling bearing device that is efficiently formed can be realized.

It is an axial direction sectional view showing the state where shaft member 1 of the wheel rolling bearing device manufactured with the manufacturing method of the shaft member of the rolling bearing device for wheels of the present invention was assembled as rolling bearing device A for wheels. It is an axial sectional view of the shaft member 1 of the rolling bearing device for wheels. (A) is the figure which looked at the shaft member 1 of the rolling bearing device for wheels shown in FIG. 2 from the AA direction, (B) is the figure seen from the BB direction. It is a figure which shows the change of the shape of the raw material by the process (A)-process (G) until it forms the shaft member of the rolling bearing apparatus for wheels from the shaft-shaped raw material 60. It is a figure explaining the 1st extrusion process of a cold forging process, and the 2nd forward extrusion process, (A) has shown sectional drawing of the metal mold | die and raw material of the 1st extrusion process, (B) Sectional drawing of the die and material of the second forward extrusion process is shown. (C) shows the schematic shape of the material before the first extrusion, (D) shows the schematic shape of the material after the first extrusion, and (E) shows the second forward extrusion. The schematic shape of the processed material is shown.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated using drawing. FIG. 1 is an axial sectional view showing a state in which a shaft member 1 of a wheel rolling bearing device manufactured by the method for manufacturing a shaft member of a wheel rolling bearing device of the present invention is assembled as a wheel rolling bearing device A. Is shown. 2 shows an axial sectional view of the shaft member 1 of the wheel rolling bearing device, and FIG. 3 is a view (A) of the shaft member 1 of the wheel rolling bearing device shown in FIG. And the figure (B) seen from the BB direction is shown.

● [Whole rolling bearing device A and overall structure of shaft member 1 of wheel rolling bearing device (FIGS. 1 to 3)]
Next, the overall structure of the wheel rolling bearing device A and the shaft member 1 of the wheel rolling bearing device will be described with reference to FIGS.
As shown in FIGS. 1 and 2, a shaft member 1 (so-called hub wheel) of a wheel rolling bearing device employed in a wheel rolling bearing device A (so-called wheel hub unit) includes a shaft portion 10 and a flange portion. 21 and the fitting shaft portion 30 are integrally provided coaxially along the axial direction.
When the wheel rolling bearing device A is attached to the vehicle, the shaft portion 10 is located inside the vehicle, the fitting shaft portion 30 is located outside the vehicle, and in FIG. Indicates the inside of the vehicle, and the right direction of the page indicates the outside of the vehicle.

The shaft portion 10 has a substantially cylindrical shape, and a large-diameter shaft portion 11 having a large diameter is formed on a side near the flange portion 21 in the shaft portion 10, and an end portion far from the flange portion 21 is larger than the large-diameter shaft portion 11. A small-diameter shaft portion 12 having a small diameter is formed, and an inner ring abutting surface 12 a that is a surface orthogonal to the rotation axis of the shaft portion 10 is formed at a step portion between the large-diameter shaft portion 11 and the small-diameter shaft portion 12.
The flange portion 21 is located between the shaft portion 10 and the fitting shaft portion 30 and has a disk shape perpendicular to the axial direction (rotation axis ZS direction). The outer diameter of the flange portion 21 is the outer diameter of the shaft portion 10. It is larger than the diameter.
The fitting shaft portion 30 is formed on one end side of the shaft portion 10 (on the side opposite to the small-diameter shaft portion 12), is coaxially formed with the shaft portion 10 and is formed into a continuous, substantially cylindrical shape, and has a wheel (not shown). Center hole is fitted.
As shown in FIG. 3, a bolt hole 24 in which a hub bolt 27 for tightening a wheel is disposed by press-fitting is formed in the flange portion 21 extending in a disk shape in the outer diameter direction.
As shown in FIGS. 1 and 2, the fitting shaft portion 30 is formed with a brake rotor fitting portion 31 on the flange portion 21 side, and has a slightly smaller diameter wheel on the tip side than the brake rotor fitting portion 31. A fitting portion 32 is formed.
Further, as shown in FIG. 1, the surface around the center hole of the brake rotor 55 abuts on the rotor support surface 22 that is the surface of the flange portion 21 on the side of the fitting shaft portion 30.
A concave forged concave portion 35 is formed on the inner diameter side of the fitting shaft portion 30.

As shown in FIGS. 1 and 2, the large-diameter shaft portion 11 of the shaft portion 10 of the shaft member 1 of the rolling bearing device for a wheel described in the present embodiment has an outer periphery in the vicinity of the boundary portion with the flange portion 21. A first inner ring raceway surface 18 constituting one bearing portion of a double row angular ball bearing as a rolling bearing is formed on a part of the surface so as to be continuous in the circumferential direction.
Further, a seal surface 19 described later that is continuous in the circumferential direction is formed on a part of the outer peripheral surface adjacent to the first inner ring raceway surface 18 and close to the flange portion 21.
Further, an inner ring 42 having a second inner ring raceway surface 44 formed so as to be continuous in the circumferential direction is fitted on the outer circumferential surface of the small-diameter shaft portion 12. The inner ring 42 is fitted until it hits the inner ring abutting surface 12a.
And the protrusion part from the inner ring | wheel 42 in the small diameter shaft part 12 (shaft end part 15 in FIG. 1) is caulked radially outward to form a caulking part 17, and the caulking part 17 and the inner ring abutting surface 12a The inner ring 42 is fixed.
Further, as shown in FIG. 1, when the inner ring 42 is fixed with the caulking portion 17 and the inner ring abutting surface 12a by caulking the shaft end 15 of the small diameter shaft portion 12, the inner ring 42 has a strength capable of fixing. The area of the inner ring abutting surface 12a is set.

Moreover, as shown in FIG. 1, the outer ring | wheel 45 is arrange | positioned maintaining the annular space in the outer peripheral surface of the axial part 10 of the shaft member 1 of the rolling bearing apparatus for wheels.
On the inner peripheral surface of the outer ring 45, a first outer ring raceway surface 46 facing the first inner ring raceway surface 18 formed on the shaft member 1 of the wheel rolling bearing device, and a second inner ring formed on the inner ring 42. A second outer ring raceway surface 47 facing the raceway surface 44 is formed. Each inner ring raceway surface and each outer ring raceway surface are formed to be continuous in the circumferential direction on each surface.
Between the first inner ring raceway surface 18 and the first outer ring raceway surface 46, a plurality of first rolling elements 50 are held by a cage 52 and arranged so as to be able to roll. Between the two outer ring raceway surfaces 47, a plurality of second rolling elements 51 are held by a cage 53 and are arranged to be able to roll.
The plurality of first rolling elements 50 and the plurality of second rolling elements 51 are subjected to axial preload based on the caulking force when the caulking portion 17 is formed by caulking the end of the small diameter shaft portion 12. An angular ball bearing is provided.

As shown in FIG. 1, a vehicle body side flange 48 is integrally formed on the outer peripheral surface of the outer ring 45, and the vehicle body side flange is a knuckle, a carrier, etc. supported by a vehicle suspension device (not shown). Fastened to the mounting surface of the vehicle body side member with a bolt or the like.
A seal member 56 is press-fitted and assembled to the inner peripheral surface of the opening adjacent to the first outer ring raceway surface 46 in the outer ring 45, and the tip of the lip 58 of the seal member 56 is in sliding contact with the seal surface 19 ( The gap between the outer ring 45 and the shaft member 1 of the wheel rolling bearing device is sealed.
Further, as shown in FIGS. 3B and 2, the surface of the flange portion 21 on the side of the shaft portion 10 has a floating island shape in order to improve the rigidity around the bolt hole 24 while suppressing an increase in weight. A floating island-shaped thick portion 29 having a partial thickness is formed.

● [Manufacturing method of shaft member 1 of rolling bearing device for wheel (FIG. 4)]
Next, the manufacturing method of the shaft member 1 of the rolling bearing device for wheels is demonstrated using FIG.
4 (A) to 4 (G) show how the shaft member 1 of the rolling bearing device for a wheel is formed from the shaft-shaped material 60 through each process, and shows the cross-sectional shape of the material after each process.
The shaft member 1 of the rolling bearing device for a wheel described in the present embodiment includes a first annealing / coating process, a first cold forging process, a second annealing / coating process, and a second cold forging process. It is manufactured through a turning process, a heat treatment process, and a polishing process.
First, prior to the first annealing / coating process, a substantially cylindrical structural carbon steel having a carbon content of about 0.5% such as S45C, S50C, S55C, etc. is cut to a predetermined length to form a shaft-shaped material 60. (See FIG. 4A).
The outer diameter (φH) of the substantially cylindrical shaft-shaped material 60 is substantially the same as the outer diameter of the floating island-shaped thick portion 29 of the shaft member 1 of the wheel rolling bearing device.

[First annealing / coating process (FIGS. 4B, 4C)]
In the first annealing / coating step, at least the following annealing treatment and coating treatment are performed.
In the annealing treatment, the shaft-shaped material 60 is heated at a temperature equal to or higher than the transformation point temperature (preferably, a temperature higher by about 20 ° C. to 70 ° C. than the transformation point temperature).
Thereby, the carbon component in the shaft-shaped material 60 is spheroidized and spheroidized and annealed to form the annealed shaft-shaped material 61 (see FIG. 4B). This annealed shaft material 61 improves the ductility of the material itself.

In the coating process, the surface of the annealed shaft material 61 is coated with a lubricant to form a coated shaft material 62 having the lubricant film 36 (see FIG. 4C).
For example, a coated shaft material 62 having a lubricant film (phosphate film) 36 is formed by applying phosphate as a lubricant to the surface of the annealed shaft material 61.
The coated shaft material 62 reduces the frictional force generated between the cold forging mold and the material (material) by the lubricant film 36 on the surface thereof.
In addition, after the above annealing treatment and before the above coating treatment, a shot blast treatment is performed, and when the surface of the annealed shaft material 61 is shaved and fine irregularities are formed so that the surface becomes rough, the coating treatment It is more preferable because a film can be formed more stably.

[First cold forging step (FIG. 4D)]
In the first cold forging step, side extrusion in which the diameter of one end in the axial direction of the coated shaft-shaped raw material 62 becomes the diameter (φG) of the flange portion 21, and the other end in the axial direction The first cold forged product 65 is formed by performing an extruding process (composite extruding process) that simultaneously performs a backward extrusion process in which the diameter of the fitting shaft part 30 becomes the diameter (φE) (see FIG. 4D). ).
As described above, by expanding the floating island diameter (φH), which is the outer diameter of the floating island-shaped thick portion 29, to the diameter (φG) of the flange portion 21, the amount of expansion is suppressed to a relatively small value, thereby cracking the flange portion. The occurrence of cracks and the like can be prevented appropriately.
The shape of the mold used in the first cold forging step will be described later.

[Second annealing / coating process]
In the second annealing / coating process, in order to extrude the forged concave portion 35 and the shaft portion 10 of the fitting shaft portion 30 from the primary cold forged product 65, the first annealing / coating treatment is performed once again. Similarly, at least annealing treatment and coating treatment are performed to form a primary cold forged product 65 that has been annealed and coated.
As a result, the stress remaining in the material after the first cold forging is removed, and the ductility of the primary cold forged product 65 is improved and the friction coefficient is reduced again. Occurrence can be prevented appropriately.
The second annealing / coating process may be omitted.

[Second Cold Forging Process (FIG. 4E)]
In the second cold forging step, the large-diameter shaft portion 11 is formed at one end while forming the forged recess 35 at the center end surface of the fitting shaft portion 30 at the other end of the primary cold forged product 65. Then, a forward cold-extrusion process is performed so as to form the small-diameter shaft portion 12, and a secondary cold forging product 66 in which the fitting shaft portion 30, the flange portion 21, the large-diameter shaft portion 11, and the small-diameter shaft portion 12 are formed is formed. (See FIG. 4E).
Further, the forward extrusion process refers to a process in which a material is placed inside a mold (so-called die), another mold (so-called punch) is pushed in, and the material is made to flow in the direction in which the mold is pushed.
The backward extrusion process is a process in which a material is placed inside a mold (so-called die), another mold (so-called punch) is pushed in, and the material is made to flow in a direction opposite to the direction in which the mold is pushed. .
Side extrusion is a direction in which a material is placed inside a die (so-called die), another die (so-called punch) is pushed in, and the direction in which the die is pushed in (mainly orthogonal) Refers to the process of making the material flow.

[Turning process (Fig. 4 (F))]
In the turning process, a part of the secondary cold forged product 66, for example, the rotor support surface 22 on one side of the flange portion 21 (corresponding to the other side flange surface 21A described later), and the end surface 33 of the fitting shaft portion 30 And the bolt hole 24 is drilled in the flange portion 21 to form a turned forged product 67 (see FIG. 4F).
In this turning process, at least the lubricant coating 36 of the wheel fitting portion 32 (see FIG. 2) of the fitting shaft portion 30 of the secondary cold forged product 66 is left without being turned.
In the present embodiment, as shown in FIG. 2, the lubricant coating 36 is formed on the surface on the opposite side of the rotor support surface 22 of the flange portion 21 (corresponding to a one-side flange surface 21B described later) and the first inner ring raceway. The seal surface 19 formed adjacent to the shoulder portion of the surface 18, the surface of the forged recess 35, and the end surface of the shaft end portion 15 at the tip of the small diameter shaft portion 12 of the shaft portion 10 are left without being turned. .
Conventionally, at least the lubricant coating 36 of the wheel fitting portion 32 in FIG. 2 is turned, and in addition to the portions where the lubricant coating 36 is left in the prior art, at least lubrication of the wheel fitting portion 32 in the present application. Extra agent coating 36 is left.
Then, the turning range is reduced by the amount of the lubricant film 36 left, and the turning process is easy and takes a short time.

[Heat treatment step (FIG. 4G)]
Next, in the heat treatment step (quenching and tempering step), the first inner ring raceway surface 18 of the shaft portion 10 of the turned forged product 67 is induction-quenched and then tempered to form a heat-treated forged product 68 (FIG. 4). (See (G)). In this case, induction hardening is not performed on the seal surface 19, the outer peripheral surface of the small diameter shaft portion 12, and the inner ring abutting surface 12a. Thereby, the time of a heat treatment process can be shortened. As shown in FIG. 2, a hardened layer S is formed around the first inner ring raceway surface 18 by quenching and tempering.

[Polishing process]
In the polishing step, the first inner ring raceway surface 18 of the heat-treated forged product 68 is polished to form the shaft member 1 of the wheel rolling bearing device.

● [Details of cold forging process (Fig. 5)]
Next, the details of the first cold forging process and the second cold forging process will be described with reference to FIG.
In the description of the present embodiment, the film-treated shaft-shaped material 62 (shaft-shaped material) having an outer diameter that is substantially the same (equal or slightly smaller) as the outer diameter (φH) of the final floating island-shaped thick portion 29 is used. The cold forging product which integrally has the fitting shaft part 30, the flange part 21, the large diameter shaft part 11, and the small diameter shaft part 12 is formed through one extrusion process and one forward extrusion process.
5A shows a cross-sectional view of the die and the material of the extrusion process (complex extrusion process, the first cold forging process), and FIG. 5B shows the forward extrusion process (second extrusion process). The cold forging process) and the cross-sectional view of the material are shown. FIG. 5C shows the schematic shape of the material before extrusion, FIG. 5D shows the schematic shape of the material after extrusion, and FIG. 5E shows the result after forward extrusion. The outline shape of the material is shown.
5A and 5B, in the sectional view of the mold and the material for explaining the extrusion process and the forward extrusion process, the right side of the drawing from the center line is a state before performing the extrusion process (or the forward extrusion process). (The state in which the material is set) is shown, and the left side of the paper from the center line shows a state in which the extrusion processing (or forward extrusion processing) is completed.

Next, the shape and configuration of the mold in the first cold forging step (extrusion process) and the shape of the material before and after the cold forging will be described with reference to FIGS. 5 (A), (C), and (D). .
As shown in FIG. 5A, in the first cold forging process, the coated shaft material 62 is extruded (side) using the first one-side mold K11 and the first other-side mold K12. (Composite extrusion process which is a side extrusion process and a backward extrusion process).
The first one-side mold K11 has a shape of the outer peripheral surface of the flange portion 21 having a final diameter (φG) of the flange portion 21 and a one-side flange surface 21B that is a surface of the flange portion 21 on the shaft portion 10 side. (The shape including the shape of the floating island-shaped thick portion 29).
The first other-side mold K12 is formed in the shape of the other-side flange surface 21A that is the surface on the side of the fitting shaft portion 30 in the flange portion 21 and the shape of the outer peripheral surface of the fitting shaft portion 30. .
Then, the coated shaft material 62 (see FIG. 5C) is arranged at the center of the first one-side mold K11 where the floating island-shaped thick portion 29 is located, and the first other-side mold K12 is lowered. Then, the outer peripheral surface of the fitting shaft portion 30, the outer peripheral surface of the flange portion 21, the one-side flange surface 21B, and the other-side flange surface are formed by being fitted to the first one-side mold K11 and performing extrusion processing. 21A and a primary cold forged product 65 (see FIG. 5D) formed thereon.
In order to prevent damage to the mold, the “volume of the space surrounded by the first one-side mold K11 and the first other-side mold K12” is “the volume of the coated shaft material 62”. "Is set larger than.
In the portion where the floating island-shaped thick portion 29 is not formed on the one-side flange surface 21B in FIG. 5A, the thickness is gradually changed from the thick portion on the central side to the thin portion on the outer peripheral side. When the inclination angle of the inclined portion is set to 20 ° ≦ θ ≦ 60 °, it can be formed into a more preferable shape.

Next, the shape and configuration of the mold in the second cold forging step (forward extrusion process) and the shape of the material before and after the cold forging will be described with reference to FIGS. 5 (B), (D), and (E). To do.
As shown in FIG. 5B, in the second cold forging step, a primary cold forged product 65 using a second one-side mold K21, a second other-side mold K22, and an intermediate mold K23. Is extruded forward. Although the auxiliary mold K24 is also used in the present embodiment, the auxiliary mold K24 may be omitted.
The second one-side mold K21 includes a shape of the outer peripheral surface of the flange portion 21, a shape of the one-side flange surface 21B of the flange portion 21, and a shape and a small diameter of the large-diameter shaft portion 11 at the tip of the one-side flange surface 21B. It is formed in the shape of the shaft portion 12.
The auxiliary mold K24 is supported by the elastic body K24S with an elastic force applied to the tip of the small-diameter shaft portion of the second one-side mold K21, and is movable while supporting the extruded material. Since it moves to an appropriate position according to the variation in the volume of the material, it is possible to prevent the occurrence of burrs.
The intermediate mold K <b> 23 is formed in the shape of the other flange surface 21 </ b> A of the flange portion 21 and the shape of the outer peripheral surface of the fitting shaft portion 30. The intermediate mold K23 has a cylindrical shape having the outer diameter of the flange portion 21, and has a hollow portion having an inner diameter corresponding to the outer diameter of the fitting shaft portion 30 at the center portion. Mate to K21.
The second other mold K22 is formed in a shape corresponding to the recess (forged recess 35) of the fitting shaft part 30, and the second other mold K22 is fitted into the cavity of the intermediate mold K23.
Then, the primary cold forged product 65 is disposed in the second one-side mold K21, the intermediate mold K23 is fitted into the second one-side mold K21, and the second other-side mold K22 is replaced with the intermediate mold K23. The first cold forging product 65 (for the outer peripheral surface of the fitting shaft portion 30) and the forged concave portion 35 (for the outer peripheral surface and one side of the flange portion 21) The secondary cold forged product 66 in which the large-diameter shaft portion 11 and the small-diameter shaft portion 12 are formed can be formed.
In addition, even if it performs the process similar to the 1st annealing and the coating process performed before the 1st cold forging process between the 1st cold forging process and the 2nd cold forging process. good.

  In the above description, the example in which the intermediate mold K23 and the second other mold K22 in FIG. 5B are configured separately has been described. However, the intermediate mold K23 and the second other mold K22 are separated from each other. An integrated mold that is an integrated mold may be formed and used in the second cold forging step. In this case, a secondary cold forged product in which the forged concave portion 35 of the fitting shaft portion 30 and the shaft portion 10 are formed from the primary cold forged product 65 can be formed more efficiently.

In the method of manufacturing the shaft member of the wheel rolling bearing device described in the present embodiment, as described above, structural carbon steel such as S45C, S50C, and S55C is heated at a temperature equal to or higher than the transformation point temperature in the annealing process. Then, an annealed shaft-shaped material 61 is formed, and a lubricant film 36 is applied to the surface of the annealed shaft-shaped material 61 in the subsequent coating process to reduce the frictional force generated between the cold forging mold. The film-treated shaft-shaped material 62 is formed, and the material is excellent in forgeability.
Furthermore, by using the shaft-shaped raw material 60 having an outer diameter corresponding to the outer diameter of the final floating island-shaped thick portion 29, in the subsequent cold forging process, the primary cold forging process and the secondary cold forging process. The cold forging which integrally has the fitting shaft part 30, the flange part 21, the large diameter shaft part 11, and the small diameter shaft part 12 by one extrusion process (composite extrusion process) and one forward extrusion process. The product (secondary cold forged product 66) can be formed efficiently.
In the description of the present embodiment, at least the annealing treatment and the coating treatment are performed on the shaft-like material in the first annealing / coating step before the first cold forging step. However, the first annealing / coating step may be omitted. Further, the floating island-shaped thick portion 29 may be omitted.

The shaft member of the wheel rolling bearing device of the present invention and the manufacturing method thereof are not limited to the manufacturing method, process, process, etc., appearance, configuration, structure, etc. described in the present embodiment, and do not change the gist of the present invention. Various changes, additions and deletions can be made within the range.
The numerical values used in the description of the present embodiment are examples, and are not limited to these numerical values.
In the description of the present embodiment, an example in which the number of bolt holes 24 is four has been described. However, the number of bolt holes 24 is plural, and the number is not limited to four. Of course, the shape of the floating island-shaped thick portion 29 shown in FIG. 2B is also changed according to the number of the bolt holes 24.

DESCRIPTION OF SYMBOLS 1 Shaft member of rolling bearing apparatus for wheels 10 Shaft part 11 Large diameter shaft part 12 Small diameter shaft part 12a Inner ring abutting surface 15 Shaft end part 17 Caulking part 18 1st inner ring raceway surface 19 Seal surface 21 Flange part 21A The other side flange surface 21B One side flange surface 30 Fitting shaft portion 35 Forged recess 36 Lubricant coating 42 Inner ring 44 Second inner ring raceway surface 45 Outer ring 46 First outer ring raceway surface 47 Second outer ring raceway surface 60 Axis material 61 Annealed shaft material 62 Coated shaft material 65 Primary cold forged product 66 Secondary cold forged product 67 Turned forged product 68 Heat treated forged product A Rolling bearing device for wheel K11 First one side die K12 First other side die K21 2nd one side mold K22 2nd other side mold K23 Intermediate mold K24 Auxiliary mold

Claims (5)

In the manufacturing method of the shaft member of the rolling bearing device for a wheel in which the fitting shaft portion, the flange portion, and the shaft portion are arranged coaxially along the axial direction.
The fitting shaft portion has a cylindrical shape having a recess opening in the axial direction;
The flange portion has a disk shape orthogonal to the axial direction,
A flange diameter that is a diameter in a direction orthogonal to the axial direction in the flange portion is larger than a fitting shaft portion diameter that is a diameter in a direction orthogonal to the axial direction in the fitting shaft portion,
The shaft portion has a cylindrical shape, and an outer ring surface is formed on the outer peripheral surface,
A plurality of bolt holes are formed in the flange portion in a direction orthogonal to the axial direction,
The shaft member of the rolling bearing device for wheels is manufactured by cold forging,
Using a cylindrical shaft-shaped material having an outer diameter larger than the fitting shaft diameter and smaller than the flange diameter,
In the first cold forging step, the diameter of one end portion in the axial direction of the shaft-shaped material is expanded to the flange diameter, and the diameter of the fitting shaft portion is set to the other end portion of the shaft-shaped material. Extrusion to form a cylindrical part having,
In the second cold forging step, forward extrusion is performed so as to form the concave portion and the shaft portion of the fitting shaft portion from the other axial end portion of the shaft-shaped material, and the wheel rolling Forming a shaft member of the bearing device;
Manufacturing method of shaft member of rolling bearing device for wheel. It is a manufacturing method of the rolling bearing device for wheels according to claim 1,
One flange surface that is the surface of the flange portion on the side of the shaft portion extends from the periphery of the shaft portion to the periphery of the bolt hole, and the axial thickness of the flange portion is partially thickened. The floating island-shaped thick portion is formed, and the diameter of the floating island-shaped thick portion is a floating island diameter that is larger than the diameter of the fitting shaft portion and smaller than the flange diameter,
Using a cylindrical shaft-shaped material having an outer diameter corresponding to the floating island diameter, a shaft member of the rolling bearing device for a wheel is formed in the first cold forging step and the second cold forging step. To
Manufacturing method of shaft member of rolling bearing device for wheel. It is a manufacturing method of the shaft member of the rolling bearing device for wheels according to claim 1 or 2,
In the extrusion process in the first cold forging step,
A first one-side mold formed on the shape of the outer peripheral surface of the flange portion and the shape of the one-side flange surface of the flange portion;
Using the shape of the other side flange surface which is the surface of the flange portion on the side of the fitting shaft portion, and the shape of the outer peripheral surface of the fitting shaft portion, using the first other side mold Extrusion process
Forming a primary cold forged product in which an outer peripheral surface of the fitting shaft portion, an outer peripheral surface of the flange portion, the one side flange surface, and the other side flange surface are formed from the shaft-shaped material; ,
In the forward extrusion process in the second cold forging step,
A second one-side mold formed on the shape of the outer peripheral surface of the flange portion, the shape of the one-side flange surface, and the shape of the shaft portion at the tip of the one-side flange surface;
It is formed in the shape of the other side flange surface and the shape of the outer peripheral surface of the fitting shaft portion, has an outer diameter corresponding to the outer diameter of the flange portion, and corresponds to the outer diameter of the fitting shaft portion. A substantially cylindrical intermediate mold having a hollow portion of an inner diameter dimension and fitted to the second one-side mold;
A second cylindrical mold that can be fitted into the hollow portion of the intermediate mold having a substantially cylindrical shape and that is formed in the shape of the concave portion of the fitting shaft portion, is subjected to forward extrusion processing,
Forming a shaft member of the rolling bearing device for a wheel which is a secondary cold forged product in which the concave portion of the fitting shaft portion and the shaft portion are formed from the primary cold forged product;
Manufacturing method of shaft member of rolling bearing device for wheel. It is a manufacturing method of the shaft member of the rolling bearing device for wheels according to claim 3,
In the second cold forging step, instead of using the intermediate mold and the second other mold, the intermediate mold and the second other mold are integrally formed. Forming a secondary cold forged product in which the concave portion of the fitting shaft portion and the shaft portion are formed from the primary cold forged product by performing forward extrusion using
Manufacturing method of shaft member of rolling bearing device for wheel. It is a shaft member of the rolling bearing device for wheels manufactured by the manufacturing method of the shaft member of the rolling bearing device for wheels according to any one of claims 1 to 4,
When forming the shaft member of the rolling bearing device for a wheel in the first cold forging step and the second cold forging step, the diameter is larger than the diameter of the fitting shaft portion and larger than the flange diameter. It is manufactured from a cylindrical shaft-shaped material having a small outer diameter, and has the disk-shaped flange portion.
A shaft member of a rolling bearing device for wheels.

Images