JP2012183560A - Shaft member of rolling bearing for wheel and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively manufacturing a cold forged article having a fitting shaft part, a flange part, and a shaft part from a circular columnar raw material by a cold forging step and a shaft member of a rolling bearing of a wheel manufactured by the manufacturing method.SOLUTION: In the method for manufacturing the shaft member of the rolling bearing for the wheel in which the fitting shaft member 30, the flange part 21, and the shaft part 10 are arranged coaxially along an axial direction, the fitting shaft part has a cylindrical shape having a concave part 35 opening in the axial direction, the flange part has a disk shape perpendicular to the axial direction, the shaft part has a circular columnar shape and formed with an inner wheel track surface in an outer peripheral surface, the cold forged article 64 having integrally the fitting shaft member, the flange part, and the shaft part is formed by only forward extruding machining in the cold forging step using the circular columnar raw material 62 having an outer diameter corresponding to an outer diameter of the flange part 21 in the shaft member 1 of the rolling bearing for the wheel.

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. Cold with a fitting shaft, flange, and shaft after three or more cold forgings from a cylindrical material with a diameter (forward extrusion and side extrusion multiple times) A forged product 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.
First, the first invention of the present invention is the method of manufacturing a shaft member of a rolling bearing device for a wheel in which a fitting shaft portion, a flange portion, and a shaft portion are arranged coaxially along the axial direction. The shaft portion has a cylindrical shape with a recess opening in the axial direction, the flange portion has a disk shape orthogonal to the axial direction, the shaft portion has a cylindrical shape, and an inner ring raceway surface is formed on the outer peripheral surface. Has been.
And the shaft member of the rolling bearing device for wheels is manufactured by cold forging, and a columnar shaft-shaped material having an outer diameter corresponding to the outer diameter of the flange portion is used. It is a manufacturing method of the shaft member of the rolling bearing device for wheels which forms the shaft member of the rolling bearing device for wheels only by extrusion processing.

  According to the first aspect of the present invention, by using a columnar shaft-shaped material having an outer diameter corresponding to the outer diameter of the flange portion, the shaft of the rolling bearing device for a wheel can be obtained only by performing forward extrusion in cold forging. Since the member can be formed, the shaft member of the wheel rolling bearing device can be formed very efficiently.

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: In the said 1st said forward extrusion process in the said cold forging process, A first one-side mold formed in the shape of the outer peripheral surface of the flange portion and the shape of the one-side flange surface that is the surface of the flange portion on the shaft portion side, and the fitting shaft in the flange portion The first side mold formed in the shape of the other side flange surface that is the surface of the part and the shape of the outer peripheral surface of the fitting shaft part, and forward-extruding the shaft A primary cold forging product in which the outer peripheral surface of the fitting shaft portion, the outer peripheral surface of the flange portion, the one side flange surface, and the other side flange surface are formed from a shaped material.
And in the second forward extrusion process in the cold forging step, the shape of the outer peripheral surface of the flange portion, the shape of the one side flange surface, the shape of the shaft portion at the tip of the one side flange surface, And the fitting shaft is formed with a second one-side mold formed on the other side, a shape of the other-side flange surface, and a shape of an outer peripheral surface of the fitting shaft portion, and has an outer diameter of the flange portion. A first intermediate mold having a substantially cylindrical shape having a hollow portion having an inner diameter corresponding to the outer diameter of the first portion and fitting with the second one-side mold, and a cavity of the first intermediate mold having a substantially cylindrical shape The first cold forging product further by the forward extrusion using the second other side mold formed in the shape of the concave portion of the fitting shaft portion. The wheel rolling, which is a secondary cold forged product in which a concave portion of the shaft portion and the shaft portion are formed. Ri to form a shaft member of the bearing device.

  According to the second aspect of the present invention, the cold forging process is realized by the first and second forward extrusion processes by using a cylindrical shaft-shaped material having an outer diameter of the flange portion and an appropriate die. The cold forging product which has a shaft part, a flange part, and a fitting shaft part integrally can be formed efficiently.

  Next, a third invention of the present invention is a method of manufacturing a shaft member of a wheel rolling bearing device according to the second invention, wherein the first intermediate mold and the second other mold are used. Instead, the first intermediate die and the second other die are integrally formed by first extruding using a first integrated die, and the fitting is further performed from the primary cold forging product. A shaft member of the rolling bearing device for a wheel, which is a secondary cold forged product in which a concave portion of the shaft portion and the shaft portion are formed, is formed.

  According to the third aspect of the invention, the cold forging product can be formed more efficiently by integrating the first intermediate mold and the second other mold.

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 1st invention, Comprising: In the said 1st said forward extrusion process in the said cold forging process, The third one side formed in the shape of the outer peripheral surface of the flange portion, the shape of the one side flange surface, and the shape of the temporary shaft portion having a smaller diameter than the small diameter shaft portion at the tip of the one side flange surface Using the mold, the shape of the other side flange surface, and the shape of the outer peripheral surface of the fitting shaft portion, a fourth other side mold formed in the forward direction, the shaft-shaped material From the outer peripheral surface of the fitting shaft portion, the outer peripheral surface of the flange portion, the one side flange surface, the other side flange surface, and the temporary cold shaft portion are formed.
And in the second forward extrusion process in the cold forging step, the shape of the outer peripheral surface of the flange portion, the shape of the one side flange surface, the shape of the shaft portion at the tip of the one side flange surface, A first mold on one side, a shape of the flange surface on the other side, and a shape of an outer peripheral surface of the fitting shaft portion, and an outer diameter of the flange portion and the fitting shaft. A substantially cylindrical second intermediate mold that has a hollow portion with an inner diameter corresponding to the outer diameter of the portion and fits with the fourth one-side mold, and a cavity of the substantially cylindrical second intermediate mold The first cold forged product is further fitted by further extruding forward using a fourth other side mold formed in the shape of the concave portion of the fitting shaft portion and being able to be fitted to the portion. The wheel rolling, which is a secondary cold forged product in which a concave portion of the shaft portion and the shaft portion are formed. Ri to form a shaft member of the bearing device.

  According to the fourth aspect of the present invention, the cold forging process is realized by the first and second forward extrusion processes by using a cylindrical shaft-shaped material having an outer diameter of the flange portion and an appropriate die. The cold forging product which has a shaft part, a flange part, and a fitting shaft part integrally can be formed efficiently.

  Next, a fifth invention of the present invention is a method of manufacturing a shaft member of a wheel rolling bearing device according to the fourth invention, wherein the second intermediate mold and the fourth other mold are used. Instead, the second intermediate mold and the fourth other mold are integrally formed by forward extrusion using a second integrated mold, and the fitting is further performed from the primary cold forging product. A shaft member of the rolling bearing device for a wheel, which is a secondary cold forged product in which a concave portion of the shaft portion and the shaft portion are formed, is formed.

  According to the fifth aspect of the present invention, a cold forged product can be formed more efficiently by integrating the second intermediate mold and the fifth other mold.

  Next, 6th invention of this invention is a shaft member of the rolling bearing apparatus for wheels manufactured by the manufacturing method of the shaft member of the rolling bearing apparatus for wheels which concerns on the said 1st invention-5th invention. When the shaft member of the rolling bearing device for a wheel is formed in the cold forging step, it is manufactured from a cylindrical shaft-shaped material having an outer diameter corresponding to the outer diameter of the flange portion, The flange portion is included.

  According to the sixth aspect of the present invention, the cylindrical shaft-shaped material having an outer diameter corresponding to the outer diameter of the flange portion is used only in the forward extrusion process in the cold forging process, and the shaft portion, the flange portion, The shaft member of the rolling bearing device for a wheel which has a fitting shaft part integrally and is formed efficiently 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 the figure which looked at the shaft member 1 of the rolling bearing apparatus for wheels shown in FIG. 1 from the B direction (hub bolt 27 is abbreviate | omitting illustration). It is an axial sectional view of the shaft member 1 of the rolling bearing device for wheels. 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 1st Embodiment of the detail of the 1st, 2nd front extrusion process in a cold forging process, (A) shows sectional drawing of the metal mold | die and raw material of a 1st front extrusion process (B) shows a sectional view of the mold and material of the second forward extrusion, (C) shows a schematic shape of the material before the first forward extrusion, (D) Shows the schematic shape of the material after the first forward extrusion, and (E) shows the schematic shape of the material after the second forward extrusion. It is a figure explaining 2nd Embodiment of the detail of the 1st, 2nd front extrusion process in a cold forging process, (A) shows sectional drawing of the metal mold | die and raw material of a 1st front extrusion process (B) shows a sectional view of the mold and material of the second forward extrusion, (C) shows a schematic shape of the material before the first forward extrusion, (D) Shows the schematic shape of the material after the first forward extrusion, and (E) shows the schematic shape of the material after the second forward extrusion.

  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.

● [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 3, 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 in the shape of a disc located between the shaft portion 10 and the fitting shaft portion 30 and orthogonal to the axial direction, and the outer diameter of the flange portion 21 is larger than the outer diameter of the shaft portion 10.
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. 2, 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 3, the fitting shaft portion 30 has a brake rotor fitting portion 31 formed on the flange portion 21 side, and a wheel having a slightly smaller diameter than the brake rotor fitting portion 31 on the distal end side. 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 3, the large-diameter shaft portion 11 of the shaft portion 10 of the shaft member 1 of the wheel rolling bearing device described in this 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 connected to the seal surface 19 (adjacent outer peripheral surface). The gap between the outer ring 45 and the shaft member 1 of the wheel rolling bearing device is sealed.

● [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 wheel rolling bearing device described in the present embodiment is manufactured through an annealing process, a coating process, a cold forging process, a turning process, a heat treatment process, and a polishing process.
First, prior to the annealing process, a substantially cylindrical structural carbon steel having a carbon content of about 0.5%, such as S45C, S50C, S55C, etc., is cut into a predetermined length to form a shaft material 60 (FIG. 4). (See (A)).
The outer diameter (φB) of the substantially cylindrical shaft-shaped material 60 is the outer diameter (φB ′ (≈φB) of the flange portion 21 of the shaft member 1 of the wheel rolling bearing device: the shaft member of the wheel rolling bearing device. The maximum outer diameter of 1 is used.

[1. Annealing treatment process (FIG. 4B)]
In the annealing treatment step, 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.

[2. Film processing step (FIG. 4C)]
Next, in the coating processing step, the surface of the annealed shaft material 61 is coated with a lubricant to form a coated shaft material 62 having the lubricant coating 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.

[3. Cold forging process (FIGS. 4D and 4E)]
The subsequent cold forging process includes a primary cold forging process and a secondary cold forging process.
In the primary cold forging process, the forged die apparatus 62 (details will be described later) is used to forwardly extrude the coated shaft-shaped material 62, and the flange portion 21 and the fitting shaft are used. The outer diameter of the part 30 is formed, and the primary cold forging product 63 by forward extrusion of cold forging is formed (see FIG. 4D).
The cross-sectional shape shown in FIG. 4D shows an example of the cross-sectional shape in the case of the first embodiment described later.

In the secondary cold forging step, a forging recess 35 is formed on the end face of the center portion of the fitting shaft portion 30 of the primary cold forging product 63 using a forging die device (details will be described later) for forward extrusion of cold forging. The secondary cold forging product 64 in which the large-diameter shaft portion 11 and the small-diameter shaft portion 12 are formed, and the fitting shaft portion 30, the flange portion 21, the large-diameter shaft portion 11, and the small-diameter shaft portion 12 are formed. (See FIG. 4E).
Note that the cross-sectional shape shown in FIG. 4E is the same in both a first embodiment and a second embodiment described later.
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.

[4. Turning process (Fig. 4 (F))]
In the turning process, a part of the secondary cold forged product 64, for example, the rotor support surface 22 on one side of the flange portion 21 and the end surface 33 of the fitting shaft portion 30 are turned, and the bolt hole 24 is formed in the flange portion 21. Is drilled to form a turned forged product 66 (see FIG. 4F).
In this turning process, at least the lubricant coating 36 of the wheel fitting portion 32 (see FIG. 3) of the fitting shaft portion 30 of the secondary cold forged product 64 is left without being turned.
In the present embodiment, as shown in FIG. 3, the lubricant film 36 is formed adjacent to the surface of the flange portion 21 opposite to the rotor support surface 22 and the shoulder portion of the first inner ring raceway surface 18. Further, the seal surface 19 (corresponding to the adjacent outer peripheral surface), 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. 3 is turned, and in addition to the portions where the lubricant coating 36 is left in the prior art, in the present application, at least the lubrication of the wheel fitting portion 32 is performed. 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.

[5. Heat treatment process (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 66 is induction-quenched and then tempered to form a heat-treated forged product 67 (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. 3, a hardened layer S is formed around the first inner ring raceway surface 18 by quenching and tempering.

[6. Polishing process]
In the polishing step, the first inner ring raceway surface 18 of the heat-treated forged product 67 is polished to form the shaft member 1 of the wheel rolling bearing device.

● [Details of Cold Forging Process in First Embodiment (FIG. 5)]
Next, the details of the cold forging process in the first embodiment will be described with reference to FIG.
In the first embodiment, from the coated shaft material 62 (shaft material) having an outer diameter (φB) equal to or slightly smaller than the outer diameter (φB ′) of the final flange portion 21, twice. 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 the forward extrusion process.
5A shows a sectional view of the first forward extrusion mold and material, and FIG. 5B shows a sectional view of the second forward extrusion mold and material. Yes. FIG. 5C shows the schematic shape of the material before the first forward extrusion, and FIG. 5D shows the schematic shape of the material after the first forward extrusion. (E) has shown the schematic shape of the raw material after a 2nd front extrusion process.
5A and 5B, the right side of the drawing from the center line is a state before the forward extrusion process (a state where the material is set). The left side of the paper from the center line shows a state where the forward extrusion process has been completed.

As shown in FIG. 5A, in the first (first) forward extrusion process, the first lower mold K11 (corresponding to the first one-side mold), the first upper mold K12 (the first other mold) The shaft-processed shaft-shaped material 62 is forward extruded using a side die).
The first lower mold K11 is formed with a shape of the outer peripheral surface of the flange portion 21 and a shape of a flange back surface 21B (corresponding to one side flange surface) which is a surface of the flange portion 21 on the shaft portion 10 side. Yes.
In the first upper mold K12, the shape of the flange surface 21A (corresponding to the other flange surface) that is the surface of the flange portion 21 on the side of the fitting shaft portion 30 and the shape of the outer peripheral surface of the fitting shaft portion 30 Is formed.
Then, the coated shaft material 62 is disposed in the first lower mold K11, the first upper mold K12 is lowered and fitted to the first lower mold K11, and the forward extrusion process is performed. A primary cold forged product 63 in which the outer peripheral surface of the coaxial portion 30, the outer peripheral surface of the flange portion 21, the flange back surface 21B, and the flange surface 21A are formed can be formed.
In order to prevent damage to the mold, the “volume of the space surrounded by the first lower mold K11 and the first upper mold K12” is more than the “volume of the coated shaft-shaped raw material 62”. Is also set larger.

Then, as shown in FIG. 5B, in the second (second) forward extrusion process, the second lower mold K21 (corresponding to the second one-side mold), the second upper mold K22 (second The primary cold forged product 63 is forward-extruded using the intermediate die K23 (corresponding to the first intermediate die) and the auxiliary die K24.
In the second lower mold K21, the shape of the outer peripheral surface of the flange portion 21, the shape of the flange back surface 21B of the flange portion 21, the shape of the large diameter shaft portion 11 and the shape of the small diameter shaft portion 12 ahead of the flange back surface 21B. The shape is formed.
The auxiliary mold K24 is supported by an elastic force applied to the tip of the small diameter shaft portion of the second lower mold K21, and is movable while supporting the extruded material. Since it moves to an appropriate position according to the variation in volume, the generation of burrs can be prevented.
The intermediate die K23 is formed with the shape of the flange surface 21A of the flange portion 21 and the shape of the outer peripheral surface of the fitting shaft portion 30. Further, 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, and the second lower mold K21. To fit.
The second upper mold K22 is formed with the shape of the recess (forged recess 35) of the fitting shaft part 30, and the second upper mold K22 is fitted into the cavity of the intermediate mold K23.
Then, the primary cold forged product 63 is arranged in the second lower mold K21, the intermediate mold K23 is fitted into the second lower mold K21, and the second upper mold K22 is inserted into the cavity of the intermediate mold K23. The outer peripheral surface of the fitting shaft portion 30, the forged recess 35, the outer peripheral surface of the flange portion 21, the flange back surface 21B, the flange surface 21A, the large diameter shaft portion 11, and the small diameter A secondary cold forged product 64 in which the shaft portion 12 is formed can be formed.
In the above description, the example in which the intermediate mold K23 and the second upper mold K22 in FIG. 5B are configured separately has been described. However, the intermediate mold K23 and the second upper mold K22 are separated from each other. An integrated mold (corresponding to the first integrated mold) may be formed and used for the second forward extrusion process. In this case, a secondary cold forged product can be formed more efficiently.

● [Details of Cold Forging Process in Second Embodiment (FIG. 6)]
Next, details of the cold forging process in the second embodiment will be described with reference to FIG. In the second embodiment, compared to the first embodiment shown in FIG. 5, the temporary shaft portion 10 </ b> K is formed in the first forward extrusion process, and the second forward extrusion process. The difference is that the end face 33 (see FIG. 3) of the cylindrical fitting shaft portion 30 to be formed is formed by the intermediate mold K23.
As in the first embodiment, the coated shaft material 62 (shaft material) having an outer diameter (φB) equal to or slightly smaller than the outer diameter (φB ′) of the final flange portion 21. Thus, a cold forged product having the fitting shaft portion 30, the flange portion 21, the large-diameter shaft portion 11, and the small-diameter shaft portion 12 integrally is formed through two forward extrusion processes.
6A shows a sectional view of the first forward extrusion mold and material, and FIG. 6B shows a sectional view of the second forward extrusion mold and material. Yes. FIG. 6C shows the schematic shape of the material before the first forward extrusion, and FIG. 6D shows the schematic shape of the material after the first forward extrusion. (E) has shown the schematic shape of the raw material after a 2nd front extrusion process.

As shown in FIG. 6A, in the first (first) forward extrusion process, the first lower mold K31 (corresponding to the third one-side mold), the first upper mold K32 (the third other mold) The coating-processed shaft material 62 is forward extruded using an auxiliary mold K34.
In the first lower mold K31 in the second embodiment, the shape of the temporary shaft portion 10K having a diameter (φC) smaller than the diameter of the small-diameter shaft portion 12 is provided at the tip of the flange back surface 21B (corresponding to the one-side flange surface). The second embodiment is the same as the first embodiment except that it is formed and the auxiliary mold K34 is provided at the position of the temporary shaft portion 10K.
The auxiliary mold K34 is supported by an elastic force applied to the tip of the temporary shaft portion of the first lower mold K31, and is movable while supporting the extruded material. Since it moves to an appropriate position according to the change in the volume of the material, it is possible to prevent the occurrence of burrs.
The first upper mold K32 in the second embodiment is the same as the first upper mold K12 in the first embodiment.
Then, the coated shaft material 62 is disposed in the first lower mold K31, the first upper mold K32 is lowered, fitted into the first lower mold K31, and subjected to forward extrusion, thereby fitting. A primary cold forged product 63 formed with the outer peripheral surface of the shaft portion 30, the outer peripheral surface of the flange portion 21, the flange back surface 21B, the flange surface 21A (corresponding to the other flange surface), and the temporary shaft portion 10K. Can be formed.

As shown in FIG. 6B, in the second (second) forward extrusion process, the second lower mold K41 (corresponding to the fourth one-side mold), the second upper mold K42 (fourth). The primary cold forged product 63 is forward extruded using an intermediate die K43 (corresponding to the second intermediate die) and an auxiliary die K44.
The second lower mold K41 and the auxiliary mold K44 in the second embodiment are the same as the second lower mold K21 and the auxiliary mold K24 in the first embodiment.
In the intermediate mold K43 and the second upper mold K42 in the second embodiment, the shape of the end surface 33 (see FIG. 3) for the fitting shaft portion 30 is not the second upper mold K42 but the intermediate mold K43. The other points are the same as in the first embodiment.
Then, the primary cold forged product 63 is disposed in the second lower mold K41 (the provisional shaft portion 10K has a smaller diameter than the small-diameter shaft portion 12 and can be appropriately disposed), and the intermediate mold K43 is disposed in the second mold K41. (2) The lower mold K41 is fitted, the second upper mold K42 is lowered into the cavity of the intermediate mold K43, and forward extrusion is performed, so that the outer peripheral surface of the fitting shaft part 30 and the forged recess 35, The secondary cold forging product 64 in which the outer peripheral surface of the flange portion 21, the flange back surface 21B, the flange surface 21A, the large diameter shaft portion 11, and the small diameter shaft portion 12 are formed can be formed.
In the above description, the example in which the intermediate mold K43 and the second upper mold K42 in FIG. 6B are configured separately has been described. However, the intermediate mold K43 and the second upper mold K42 are separated from each other. An integrated mold (corresponding to a second integrated mold) may be formed and used for the second forward extrusion process. In this case, a secondary cold forged product 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 the outer diameter of the final flange portion 21, in the subsequent cold forging process, two forward extrusion processes of the primary cold forging process and the secondary cold forging process are performed. Efficiently forming a cold forged product (secondary cold forged product 64) integrally including the fitting shaft portion 30, the flange portion 21, the large-diameter shaft portion 11, and the small-diameter shaft portion 12 (only by forward extrusion). can do.

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.

DESCRIPTION OF SYMBOLS 1 Shaft member of rolling bearing apparatus for wheels 10 Shaft part 10K Temporary 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 (adjacent outer peripheral surface) )
21 Flange part 21A Flange surface (the other side flange surface)
21B Flange back surface (one side flange surface)
30 Coupling 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 Shaft material 61 Annealed shaft material 62 Coated shaft shape Material 63 Primary cold forged product 64 Secondary cold forged product 66 Turned forged product 67 Heat-treated forged product A Rolling bearing device for wheels K11 First lower die (first one side die)
K12 First upper mold (first other mold)
K13 Auxiliary mold K21 Second lower mold (second one mold)
K22 Second upper mold (second other mold)
K23 Intermediate mold (first intermediate mold)
K24 Auxiliary mold K31 1st lower mold (3rd one side mold)
K32 First upper mold (third other mold)
K34 Auxiliary mold K41 Second lower mold (fourth one side mold)
K42 2nd upper mold (4th other side mold)
K43 Intermediate mold (second intermediate mold)
K44 Auxiliary mold

Claims (6)

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,
The shaft portion has a cylindrical shape, and an outer ring surface is formed on the outer peripheral surface,
The shaft member of the rolling bearing device for wheels is manufactured by cold forging,
A columnar shaft-shaped material having an outer diameter corresponding to the outer diameter of the flange portion is used, and in the cold forging process, the shaft member of the rolling bearing device for a wheel is formed only by forward extrusion.
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,
In the first forward extrusion process in the 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 that is the surface of the flange portion on the shaft portion side;
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 Extrude forward,
Forming a primary cold forged product in which the outer peripheral surface of the fitting shaft portion, the 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 second forward extrusion process in the 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;
A hollow portion having an outer diameter of the flange portion and an inner diameter dimension corresponding to the outer diameter of the fitting shaft portion, which is formed in the shape of the other flange surface and the shape of the outer peripheral surface of the fitting shaft portion. A first intermediate mold having a substantially cylindrical shape fitted to the second one-side mold,
A second cylindrical mold that can be fitted into the hollow part of the first intermediate mold having a substantially cylindrical shape and is formed in the shape of the concave part of the fitting shaft part, and forward-extrusion processing,
Forming a shaft member of the rolling bearing device for a wheel which is a secondary cold forged product in which a concave portion of the fitting shaft portion and the shaft portion are further 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 2,
Instead of using the first intermediate mold and the second other mold, the first intermediate mold and the second other mold are integrally formed with the first integrated mold. Extrusion process
Forming a shaft member of the rolling bearing device for a wheel which is a secondary cold forged product in which a concave portion of the fitting shaft portion and the shaft portion are further 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 1,
In the first forward extrusion process in the cold forging step,
The third one formed in the shape of the outer peripheral surface of the flange portion, the shape of the one-side flange surface, and the shape of the temporary shaft portion having a smaller diameter than the small-diameter shaft portion at the tip of the one-side flange surface. Side mold,
Using the third other side mold formed in the shape of the other side flange surface and the shape of the outer peripheral surface of the fitting shaft portion, forward extrusion processing,
A primary cold forging 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, the other side flange surface, and the temporary shaft portion are formed from the shaft-shaped material. Form the
In the second forward extrusion process in the cold forging step,
A fourth 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;
A hollow portion having an outer diameter of the flange portion and an inner diameter dimension corresponding to the outer diameter of the fitting shaft portion, which is formed in the shape of the other flange surface and the shape of the outer peripheral surface of the fitting shaft portion. A second intermediate mold having a substantially cylindrical shape fitted to the fourth one-side mold,
A fourth cylindrical mold that can be fitted into the hollow part of the second intermediate mold having a substantially cylindrical shape and is formed in the shape of the concave part of the fitting shaft part, and forward-extruding using,
Forming a shaft member of the rolling bearing device for a wheel which is a secondary cold forged product in which a concave portion of the fitting shaft portion and the shaft portion are further 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 4,
Instead of using the second intermediate mold and the fourth other-side mold, the second intermediate mold and the fourth other-side mold are integrally formed with a second integrated mold. Extrusion process
Forming a shaft member of the rolling bearing device for a wheel which is a secondary cold forged product in which a concave portion of the fitting shaft portion and the shaft portion are further formed from the primary cold forged product;
Manufacturing method of shaft member of rolling bearing device for wheel. A wheel member of a wheel rolling bearing device manufactured by the method of manufacturing a shaft member of a wheel rolling bearing device according to any one of claims 1 to 5,
When the shaft member of the rolling bearing device for a wheel is formed in the cold forging step, it is manufactured from a cylindrical shaft-shaped material having an outer diameter corresponding to the outer diameter of the flange portion, Having a flange,
A shaft member of a rolling bearing device for wheels.

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