JP2000042685A - Method of forming disk portion having through hole, method of manufacturing automobile wheel provided with disk portion having through hole, hot forging device - Google Patents

Abstract

(57) Abstract: In a method of forming a disk portion having a through hole, it is possible to prevent the generation of processing waste having a low regeneration rate and to form the through hole with simple equipment. A method of forming a disk portion (12) having a through hole using a material that can be hot forged, comprising: forming a bottom wall that is open to the front surface and protrudes to the rear surface from the material by hot forging. A recess forming step of setting the thickness of the boundary region connected to the outside from the bottom wall to 0.1 mm to 3 mm at the same time as forming the provided concave portion, and separating the bottom wall and the outside at the boundary region and performing the penetration. A bottom wall removing step of forming a hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for forming a disk portion having a through hole from a hot forgeable metal material such as an aluminum alloy or a magnesium alloy.

[0002]

2. Description of the Related Art As a method of manufacturing an automobile wheel, in which a desk portion having a through hole for decoration and a rim portion following the outer periphery of the desk portion are integrally formed, a material such as an aluminum alloy or a magnesium alloy is hot forged. A technique for forming a through hole by cutting is known.

In this technique, a flat disk portion is formed by clamping a central portion of a thick disk-shaped material heated to a temperature equal to or higher than a transformation point with a pair of dies, and then forming the flat disk portion. The rim is formed by spinning the outer periphery of the rim to temporarily make an intermediate product. Next, the intermediate product is set on a milling machine or the like, and a decorative through-hole is formed in the disk portion by cutting, and then a finishing process such as polishing is performed.

However, when the through hole is formed by cutting as described above, there are the following problems. . Since the cutting chips are small, the recycling rate when recycling the cutting chips into a new material is poor. When the cutting chips are heated to a melting point or higher to regenerate the cutting chips into a new material, an oxide film having a certain thickness is inevitably formed on the surface of the cutting chips. Therefore, when the cutting waste is small, the ratio of the oxide film that needs to be disposed of to the regenerated product obtained as a result of heating and melting increases, and the regenerating rate of the material deteriorates.

[0005] When the through hole is formed by cutting, it is necessary to provide a mechanism that fixes the intermediate product at the processing location and mechanical equipment that has the function of accurately aligning the blade with the workpiece to be processed. Can not.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above points, and the inventions of claims 1 to 3 are:
It is an object of the present invention to provide a method for forming a disk portion that can prevent the generation of processing waste having a low reproduction rate and can form a through hole with simple equipment. The inventions of claims 4 to 5 prevent the generation of processing waste having a low recycle rate,
An object of the present invention is to provide a method of manufacturing a vehicle wheel that can form a through hole with simple equipment.

A sixth object of the present invention is to provide a hot forging apparatus for forming an intermediate product manufactured during the execution of the fourth invention.

[0008]

According to a first aspect of the present invention, there is provided a method for forming a disk portion having a through hole using a hot forgeable material. Forming, by hot forging from the material, a concave portion having a bottom wall opened to the front surface and projecting to the rear surface, and at the same time, the thickness of a boundary region extending from the bottom wall to the outside thereof is 0.1 mm.
and a bottom wall removing step of separating the bottom wall and its outside at the boundary region to form the through hole.

According to the above-described means, when the concave portion is formed in the concave portion forming step, the bottom wall is projected to the back surface side, and the thickness of the boundary region extending from the bottom wall to the outside is set to 0.1 mm.
It is set to 1 mm to 3 mm, whereby the boundary region becomes thin. Next, a through hole is formed by separating the bottom wall and the outside of the concave portion at the boundary region. At this time, since the thickness of the boundary area is as thin as 0.1 mm to 3 mm, for example, the bottom wall is hit by a hitting means such as a simple hitting device or a hammer to perform the operation of hitting the bottom wall. Can be removed.

As a method of removing the bottom wall, a method of using a simple pressing device, a method of cutting and removing a thin wall-like boundary region outside the bottom wall and the like in addition to the above-described hitting device and the like. , Various techniques can be adopted. Specifically, the bottom wall removing step may be "the boundary area is broken by hitting the bottom wall with a striking means" as in the invention of claim 2. In this case, As described above, the through hole can be formed only by hitting the bottom wall.

[0011] Specifically, the recess forming step includes the steps of "forming a first mold having a recess-forming projection corresponding to the recess, and forming the bottom wall. And a step of clamping the material with a second mold having a material escape concave portion. The technical means of the invention according to claim 4 for solving the above-mentioned problem is that “from a disk portion having a through hole and an outer rim and an inner rim following the outer periphery of the disk portion by using a hot forgeable material. A method for manufacturing an automobile wheel, comprising integrally forming a rim portion comprising: forming a first disk forming surface provided with a concave portion forming convex portion; and forming the outer rim or the inner rim on an outer periphery of the first disk forming surface. A first mold having a first annular molding surface for forming the material, and a concave portion for material escape facing the convex portion for forming the concave portion;
A second disk forming surface facing the disk forming surface;
A hot forging apparatus provided with a second mold having a second annular forming surface forming the inner rim or the outer rim on the outer periphery of the disk forming surface, and a forming roller forming the outer peripheral surface of the rim portion By pressing the material between the first disk molding surface and the second disk molding surface, a concave portion having a bottom wall opened to the front surface and protruding to the rear surface corresponds to the formation position of the through hole. At the same time as the thickness of the boundary region from the bottom wall to the outside is 0.1 mm to 3 mm.
And a part of the material protruding to the outer periphery of the first disk molding surface and the second disk molding surface is pressed against the first annular molding surface and the second annular molding surface by the molding roller, and After rotating the rim by spinning the first and second molds to form an intermediate product, and removing the intermediate product from the first and second molds,
The bottom wall and the outside thereof are separated at the boundary region to form the through hole in the intermediate product. "

According to the above technical means, when a material that can be hot forged is pressed between the first and second dies, a part of the material is used for forming a concave portion on the first disk forming surface of the first die. Pressed by the protrusions, this forms a recess with a bottom wall that opens to the front and protrudes to the back. In this case, the bottom wall of the concave portion protrudes toward the back surface side, and a boundary region extending from the bottom wall to the outside thereof is set to a thin shape having a thickness of 0.1 mm to 3 mm. Next, the material that has protruded to the outer periphery of the first and second disk molding surfaces in the first and second dies is pressed against the first and second annular molding surfaces by a molding roller, and the first and second annular molding surfaces are pressed. By synchronously rotating the mold, the rim is spinned, thereby completing the intermediate product.
Next, the intermediate product is removed from the first and second molds, and the bottom wall of the above-mentioned concave portion formed in the disk portion is hit with, for example, a simple hitting means. Then, the thin boundary region is broken. That is, the bottom wall and the outside thereof are separated from each other at a boundary region between them. Thereby, a through-hole is formed in the portion.

According to a fifth aspect of the present invention, there is provided a semiconductor device comprising: the material comprises a disk equivalent part and a cylindrical rim equivalent part formed along the outer periphery of the disk equivalent part; On the other hand, the intermediate product is molded in a state where the material is interposed between the first and second molds so that the rim-equivalent portion is fitted outside.

In this case, a cylindrical rim equivalent portion serving as a rim portion is formed on the outer periphery of the disk equivalent portion of the material, and the basic shape of the rim portion is already formed.
There is no need to start machining the rim from the basic shape. According to a sixth aspect of the present invention, there is provided "a rim portion comprising a disc portion having a concave portion having a bottom wall opened to the front surface and projecting to the rear surface, and an outer rim and an inner rim following the outer periphery of the disc portion. A hot forging apparatus for forming a member, wherein the outer rim or the inner rim is formed on a first disk forming surface having a concave portion forming convex portion forming the concave portion and an outer periphery of the first disk forming surface. A first mold having a first annular molding surface for forming the second disk, a second disk molding surface having a material escape recess facing the projection for forming the recess, and facing the first disk molding surface; A second mold having a second annular molding surface forming the inner rim or the outer rim on the outer periphery of the molding surface, and a molding roller forming the outer peripheral surface of the rim portion were provided. " This method is used for implementing the method of claim 4. That hot forging device is obtained.

[0015]

As described above, according to the first to third aspects of the present invention, the through hole is formed by separating the bottom wall formed on the disk portion from the outside.
As in the case where a through-hole is formed by cutting, small cutting chips having a poor regeneration rate are not generated.

Further, a through-hole can be formed simply by hitting an arbitrary place in the bottom wall of the concave portion, and a mechanism for fixing an intermediate product to a processing place and a cutting tool can be precisely mounted on the processing part as in the conventional case described above. There is no need to match. Therefore, it is possible to provide a method of forming a disk portion in which a through hole can be formed with simple equipment. Claim 4
According to the inventions of the fifth to fifth aspects, it is possible to provide a method of manufacturing a vehicle wheel in which through holes can be formed with simple equipment without generating small chips having a low regeneration rate.

According to the fifth aspect of the present invention, since it is not necessary to start machining from the basic shape of the rim, machining of the automobile wheel can be made more efficient. According to the sixth aspect of the present invention, it is possible to provide a hot forging apparatus for forming an intermediate produced during the implementation of the fourth aspect of the present invention.

[0018]

Next, embodiments of the present invention will be described. FIG. 1 is an overall schematic view of a partially cut-away portion of a hot forging device for explaining an embodiment of the present invention. FIG. 9 is a plan view (a view of a surface exposed to the outside of the vehicle body when mounted on the vehicle body) of the vehicle wheel (17) to be manufactured, and FIG. 10 is an enlarged view of a line XX of FIG. It is sectional drawing. [Overall Configuration] In the hot forging apparatus shown in FIG. 1, a first die (20) is provided in a suspended state on an upper side member (61) of a gate frame (6). Below the lower holder (6)
A second mold (30) attached to 2) is provided. or,
Forming rollers (4) and (40) are provided on both sides of the second mold (30).

The details of each section will be described below. [About the first mold (20)] The first mold (20) is an upper member (61).
It is attached to the lower surface of the rotary bed (50) in the cylindrical upper holder (63) suspended from the bottom and opening downward. The upper holder (63) is attached to an output shaft of a hydraulic cylinder (64) disposed on the upper surface of the upper member (61), and a pair of guide posts (68a) protruding from the upper surface of the upper holder (63). (68b) slidably penetrates the upper side member (61). The rotary bed (5
0) is rotatably held by the upper holder (63) by the bearings (60a) and (60b), and is incorporated in the worm wheel (52) formed on the outer peripheral surface of the body and the upper holder (63). It is connected to an output shaft of a drive motor (not shown) via a worm gear device including a worm (53).

Accordingly, the first mold (20) is driven to rotate by the drive motor and is driven up and down by the hydraulic cylinder (64). The lower surface of the first mold (20) is a first disk molding surface (21), and the first disk molding surface (21)
Corresponds to the three-dimensional shape of the outer surface of the disk portion (12) of the vehicle wheel (17) to be manufactured as shown in FIGS. 9 and 10 (the surface exposed to the outside of the vehicle body when mounted on the vehicle body). . Specifically, as shown in FIGS. 2 and 8, the first mold (2
In the first disk forming surface (21) of (0), cylindrical concave portion forming convex portions (23a) (23b) corresponding to the through holes (13a) (13b) (13c) formed in the disk portion (12). ) (23c) are circumferentially arranged at 120 degree intervals. Each concave part forming convex part (23
a) (23b) (23c) has an outer peripheral surface that matches the inner peripheral surface of the through holes (13a), (13b), and (13c).
3a) (23b) Through hole (13a) (13b)
The inner peripheral surface of (13c) is formed. Also, in the center of the lower surface of the first disk forming surface (21), the disk (1
A central convex portion (26) having concave portions (27a) and (27b) for forming irregularities for decoration protrudes from 2). A groove running in a mesh shape may be formed on the surface of the first disk forming surface (21). In such a case, a through hole (13) is formed on the surface of the disk portion (12).
a) (13b) (13c) and a mesh-shaped three-dimensional pattern are formed.

The first annular molding surface (25) which is continuous with the outer periphery of the first disk molding surface (21) is formed on the inner periphery of the outer rim (14a) of the rim portion (14) of the vehicle wheel (17). It has a surface shape that conforms to the surface and the following outer surface. [Regarding the second mold (30)] The second mold (30) opposed to the first mold (20) from below is provided with a bearing () in a cylindrical lower holder (62) that opens upward. 69a) is fixed to the upper end of a rotating bed (65) rotatably mounted by (69b), and the rotating bed (65) has a worm wheel (66) formed on the outer periphery of its body and a lower holder (62). And a worm (67) built in the worm gear device (not shown) and a drive motor (common to the drive motor for rotating the rotary bed (50) for the first mold (20)). Are linked. or,
The rotary bed (65) is configured to rotate synchronously with the rotary bed (50) for the first mold (20) described above.

The upper surface of the second mold (30) is a second disk forming surface.
As shown in FIG. 2, the second disk forming surface (31) has convex portions (23a) (23) for forming concave portions of the first mold (20).
b) A cylindrical material escape recess (73a) facing (23c)
(73b) and (73c) are formed. Also, the inner diameter of these material escape recesses (73a) (73b) (73c) is
3a) (23b) It is set slightly larger than the outer diameter of (23c). Further, a central concave portion (74) facing the central convex portion (26) of the first mold (20) is formed on the second disk forming surface (31), and a bottom wall of the central concave portion (74) is formed. Is mounted with a push pin (75) that can move up and down, and the push pin (75) is moved up and down by a drive source (not shown).

The second annular molding surface (35), which is continuous with the outer periphery of the second disk molding surface (31), is formed in a tapered shape tapering upward, and is provided on the rim of the vehicle wheel (17). It has a surface shape that matches the inner peripheral surface of the inner rim (14b) of the portion (14) and the outer surface following the inner rim (14b). [About the forming rollers (4) and (40)] * About the forming roller (4) * The forming roller (4) located on the side of the second mold (30) is arranged on the side plate of the portal frame (6). The forming device (7) is mounted on the supporting device (7). The supporting device (7) drives the forming roller (4) in a horizontal direction by a first hydraulic cylinder incorporated therein, and is supported by a second hydraulic cylinder. It is a type that drives up and down. The forming roller (4) is rotatably mounted on a support shaft (41) penetrating the center thereof.

The range from the drop center (15) to the outer rim (14a) of the rim portion (14) shown in FIG.
The range from the inner rim (14b) to the tire bead portion (19) and the annular rising portion (18) is processed by a forming roller (40) described later. For this reason, when the forming roller (4) is sectioned along the axis, the shape near the upper end of the forming roller (4) is from the drop center (15) of the vehicle wheel (17) to the outer rim (14a). The shape of the forming roller
The outer peripheral shape of the lower part of (4) is formed in a tapered shape tapering downward. * About the forming roller (40) * The forming roller (40) provided on the opposite side of the forming roller (4) with respect to the second mold (30) is supported by a supporting device (8). The device (8) is mounted on the side plate of the portal frame (6). This support device (8) also drives the forming roller (40) in the horizontal and vertical directions by two hydraulic cylinders. Next, the operation of manufacturing the automobile wheel (17) shown in FIGS. 9 and 10 using the hot forging apparatus will be described. * Forging operation * First, an aluminum alloy having a disk equivalent part (101) as shown in FIG. 2 and a cylindrical rim equivalent part (102) formed along the outer periphery thereof and heated to a temperature higher than the transformation point is used. A hot forgeable material (10) such as a magnesium alloy is prepared.

Next, a recess forming step is performed. Therefore, first, the material (10) is externally fitted to the second mold (30) from above, and then the first mold (20) is lowered by operating the hydraulic cylinder (64). FIG. 2 shows that the dropped first mold (20) is made of material (1).
0) shows a state of approaching to the upper surface.

In this state, when the first mold (20) is further lowered by the operation of the hydraulic cylinder (64), the disk equivalent portion (101) of the material (10) is formed into the first disk of the first mold (20). Surface (21)
And the second disk forming surface (31), whereby the disk equivalent portion (101) is moved between the first disk forming surface (21) and the second disk forming surface (31) as shown in FIG. Deforms according to the uneven shape. Then, the first mold in material (10)
The portions pressed by the concave portion forming convex portions (23a), (23b), and (23c) of (20) are the material release concave portions (73a) (73
b) Move into (73c). Therefore, a concave portion (11) is formed in the disk-equivalent portion (101) of the material (10) as a recessed portion of the concave portion forming convex portion (23a), and as shown in FIG. 3 and FIG. The thickness t of the outer peripheral portion (160) which is a boundary region extending from the bottom wall (16) to the outside thereof is reduced. Specifically, the thickness t is desirably set to 0.1 mm to 3 mm.
It is more desirable to set it in the range of 5 mm to 1.5 mm. When the wall thickness t is larger than 3 mm, it becomes difficult to break the portion of the wall thickness t and remove the bottom wall (16) as described later. On the other hand, when the wall thickness t is less than 0.1 mm and extremely thin, , 1st mold
When the mold (20) and the second mold (30) approach each other to the closest position, the material (10) hardly protrudes outside from the material escape recesses (73a) (73b) (73c). This is because an extremely large force is required to bring the first mold 20 and the second mold 30 closer to the final position.

Next, a drive motor (not shown) is operated to rotate the worms (53) and (67), whereby the first mold (20) holding the material (10) and the second mold (20) are pressed. The mold (30) is synchronously rotated about its pinching direction axis (vertical axis in FIG. 1). Next, the forming roller (4) is advanced by the operation of the support device (7), and as shown in FIG. 4, the forming roller (4) is pressed against the rim-equivalent portion (102) of the material (10). Then, a rim-equivalent portion (102) protruding on the outer periphery of the first disk forming surface (21) and the second disk forming surface (31) is formed between the forming roller (4) and the first annular forming surface (25). And forming rollers
It is finished in a predetermined shape between (4) and the second annular forming surface (35). At this time, the rim-equivalent part (102) is
The spinning process is performed by being pressed between the rim portion (25) and the first annular forming surface (25), whereby a shape ranging from the drop center (15) of the rim portion (14) to the outer rim (14a) is completed.

Next, a forming roller is formed by a supporting device (7).
(4) is retracted to the initial position and then the support device (8)
The molding roller (40) approaches the second annular molding surface (35) side of the second mold (30), and as shown in FIG. 5, the second annular molding surface (35) and the molding roller ( Press the rim-equivalent part (102) with 40). In this state, by moving the forming roller (40) horizontally and downward to move the forming roller (40) to the tip of the inner rim (14b) shown in FIG.
The outer shape of the inner rim (14b) extending from the tire through the tire bead portion (19) to the annular rising portion (18) is subjected to spinning.

Next, the forming roller (4) is supported by the supporting device (8).
0) to the initial position and simultaneously move the hydraulic cylinder (6
The first mold (20) is raised by 4), and then the push pin (75) is raised, so that the intermediate product (81) shown in FIG.
Can be removed from the mold (30). Thus, the recess forming step is completed. Next, as shown in FIG. 7, the bottom wall (16) of the concave portion (11) formed in the disk portion (12) of the intermediate product (81) is connected to a simple hitting device (55) or a hammer (not shown). When struck by the striking means, as shown in FIG. 12, the bottom wall (16) and the outer peripheral portion (160), which is a boundary region outside the bottom wall (16), are broken, whereby the bottom wall (16) and the outside are separated. The bottom wall (16) is removed. In addition, the bottom wall of the other convex portions (23b) and (23c) is removed in the same manner to complete the bottom wall removing step, and thereafter, a fracture mark is formed on the outer peripheral portion (160) of the bottom wall (16). The burr is removed, and a finishing process such as polishing is performed. Then, as shown in FIGS. 9 and 10, the recesses (11), (11), (11)
The vehicle wheel (17) having the disk portion (12) in which the through holes (13a), (13b), and (13c) corresponding to are formed is completed.

In this case, the outer peripheral portion (16) is hit by hitting the bottom wall (16) of the concave portion (11) corresponding to the through hole (13a) and the like.
0), thereby removing the bottom wall (16). Therefore, the above-mentioned through holes (13a), (13b), and (13c) can be machined with a simpler facility than the above-mentioned milling machine having a function of fixing a workpiece to be machined at a machining place or accurately aligning a blade with a workpiece. Automobile wheels can be manufactured. Further, since the bottom wall (16) serving as scrap is larger than the small cutting chips generated when cutting with the milling machine or the like, scrap having a high recycle rate when regenerating to a new material is generated, and material resources are wasted. Is reduced. [Modification] In the above embodiment, the first mold (20) has the first
(23a) (23b) (23
c) protruding, but the projections (23a) (23b) (23
c) protrudes from the second disk forming surface (31) of the second mold (30), and the corresponding material escape recesses (73a) (73b)
(73c) may be formed on the first disk molding surface (21) of the first mold (20).

In the above embodiment, the outer surface of the disk portion (12) of the vehicle wheel (17) is formed on the first disk forming surface (21) of the first mold (20). Disc molding surface
The inner surface of the disk portion (12) may be formed in (21). In such a case, the inner surface of the inner rim (14b) is formed on the first annular forming surface (25) following the first disk forming surface (21), while the second disk forming surface of the second mold (30) is formed. The outer surface of the disk portion (12) is formed at (31), and the outer rim (14a) is formed at the second annular forming surface (35) following the outer periphery thereof.

Also, a disk portion (12) of an automobile wheel
The recess (11) is formed in such a manner that the bottom wall (16) of the recess (11) does not protrude on the back surface of the portion to be formed, and the bottom wall (11) is hit so that the through holes (13a) (13b) ( It is theoretically possible to form 13c).

[Brief description of the drawings]

FIG. 1 is an overall schematic view of a partially cut-away portion of a hot forging device illustrating an embodiment of the present invention.

FIG. 2 shows a first mold (20) and a second mold (3) in which a material (10) is set in a second mold (30) of the hot forging apparatus shown in FIG.
0), forming roller (4), forming roller (40), sectional view showing the relationship between material (10)

FIG. 3 is a view of a state where a first mold (20) is lowered from the state of FIG. 2;

FIG. 4 shows a state in which the forming roller (4) is moved from the state of FIG.
02) Side view

5 is a view showing a state in which the forming roller (4) is returned to the initial position from the state of FIG. 4 and the forming roller (40) is moved to the rim-equivalent portion (102) side.

FIG. 6 shows a state in which the forming roller (40) is in an annular rising portion from the state of FIG.
Diagram of the state where it has moved to (18)

7 is a sectional view of the intermediate product (81) taken out of the second mold (30) shown in FIG.

FIG. 8 is a bottom view of the first mold (20) shown in FIG. 1;

FIG. 9 is a plan view of an automobile wheel (17).

FIG. 10 is an enlarged cross-sectional view taken along line XX in FIG. 9;

FIG. 11 is an outer peripheral portion of a bottom wall (16) formed in a recess forming step.
Enlarged view showing details of (160)

FIG. 12 is a sectional view showing a state where the bottom wall (16) is separated from the intermediate product (81).

[Explanation of symbols]

 (4) (40) ・ ・ ・ Forming roller (10) ・ ・ ・ Material (11) ・ ・ ・ Recess (12) ・ ・ ・ Disk part (13a) (13b) (13c) ・ ・ ・ Through hole (14)・ ・ ・ Rim (16) ・ ・ ・ Bottom wall (20) ・ ・ ・ First mold (21) ・ ・ ・ First disc forming surface (23a) (23b) (23c) ・ ・ ・ Convex for forming concave portion Part (25) ・ ・ ・ First annular molding surface (30) ・ ・ ・ Second die (31) ・ ・ ・ Second disk molding surface (35) ・ ・ ・ Second annular molding surface (81) ・ ・ ・Intermediate product (160)

Claims (6)

[Claims] 1. A method for forming a disk portion having a through hole using a material that can be hot forged, comprising a bottom wall that is opened to the front surface and protrudes to the back surface by hot forging from the material. At the same time as forming the recess, the thickness of the boundary region extending from the bottom wall to the outside thereof is 0.1 mm to 3 mm.
A method of forming a disk portion having a through-hole, comprising: a recess forming step of setting the diameter to mm; and a bottom wall removing step of forming the through-hole by separating the bottom wall and the outside at the boundary region. 2. The method according to claim 1, wherein the step of removing the bottom wall breaks the boundary region by hitting the bottom wall with a hitting means. 3. The step of forming a concave portion includes a first die having a concave portion forming convex portion corresponding to the concave portion, and a second die having a material releasing concave portion for forming the bottom wall. 3. The method for forming a disk having a through hole according to claim 1, further comprising a step of clamping the material. 4. A method for manufacturing an automobile wheel, wherein a disk portion having a through hole and a rim portion including an outer rim and an inner rim following an outer periphery of the disk portion are integrally formed using a hot forgeable material. A first mold having a first disk forming surface provided with a convex portion for forming a concave portion and a first annular forming surface for forming the outer rim or the inner rim on an outer periphery of the first disk forming surface; A second disk forming surface facing the first disk forming surface and a second disk forming surface facing the first disk forming surface; and forming the inner rim or the outer rim on the outer periphery of the second disk forming surface. Using a hot forging device provided with a second mold having a second annular forming surface to be formed, and a forming roller for forming the outer peripheral surface of the rim portion, wherein the first disk forming surface and the second disk forming are provided. By pinching the material with A concave portion having a bottom wall opened to the front surface and projecting to the rear surface is formed at a position corresponding to the formation position of the through hole, and at the same time, the thickness of the boundary region extending from the bottom wall to the outside thereof is 0.1 mm to 3 mm. And pressing a part of the material protruding to the outer periphery of the first disk molding surface and the second disk molding surface against the first annular molding surface and the second annular molding surface with the molding roller, By rotating the first and second molds synchronously to spin the rim to form an intermediate product, after removing the intermediate product from the first and second molds, the bottom wall and its A method of manufacturing an automobile wheel including a disk portion having a through-hole, wherein the through-hole is formed in the intermediate product by separating the outside from the outside at the boundary region. 5. The material comprises a disk-equivalent part and a cylindrical rim-equivalent part formed along the outer periphery of the disk-equivalent part, and the rim-equivalent part is provided on at least one of the first and second molds. 5. The method for manufacturing an automobile wheel having a disk portion having a through hole according to claim 4, wherein the intermediate product is formed in a state where the material is interposed between the first and second molds in a form in which the outer portion is fitted. . 6. A member having a disk portion formed with a concave portion having a bottom wall opened to the front surface and protruding from the rear surface, and a rim portion including an outer rim and an inner rim following an outer periphery of the disk portion is formed. A first disk forming surface provided with a concave portion forming convex portion for forming the concave portion, and a second disk for forming the outer rim or the inner rim on the outer periphery of the first disk forming surface. A first mold having one annular molding surface, a second disk molding surface having a material escape concave portion facing the concave portion forming convex portion, and a second disk molding surface facing the first disk molding surface; A hot forging apparatus provided with a second mold having a second annular forming surface forming the inner rim or the outer rim on the outer periphery, and a forming roller forming an outer peripheral surface of the rim portion.