JPH06218481A - Manufacture of light alloy wheel - Google Patents

Abstract

PURPOSE:To unnecessitate a spinning process being a factor causing high in cost and to reduce product cost in the manufacturing method of a light alloy- made wheel by forging. CONSTITUTION:At first, by using up-set dies 11a, 11b, an aluminum alloy-made billet is subjected to the up-set forging to obtain a primary forged material 2 provided with a disk part and a projecting part 2a. The projecting part 2a in the primary forged material 2 is formed in the almost same length as the rim part of the product wheel. Further, in this primary forged material 2, for example, a volume in the circumference of a circle continuously formed by the points being inside by 20mm from the crossing part of the inside surface of the projecting part 2a and the surface of the disk part is set at 3.0-3.7 times of the volume at the position corresponding to the forming surface in the finish forging die. Successively, this primary forged material 2 is subjected to the forging work to form the disk part in the prescribed shape. Further, the end part of the projecting part is subjected to a bending work by flaring to form a rear flange part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a light alloy wheel for manufacturing a one-piece wheel by forging a light alloy such as an aluminum alloy.

[0002]

2. Description of the Related Art Wheels made of aluminum alloy (hereinafter referred to as "aluminum wheels") have been used in automobiles since the 1960s because they are lighter in weight than iron wheels and have excellent fashionability. Initially,
Aluminum wheels were used only in some luxury cars such as sports cars, but in recent years, fashionability has also been demanded in popular cars, so aluminum wheels are widely used in addition to luxury cars. became.

Due to its structure, an aluminum wheel is a one-piece wheel in which a disc surface which is a design surface and a rim portion for supporting a tire are integrally molded, a two-piece wheel formed by combining two members, and a three-piece wheel. It can be classified into three types of three-piece wheels formed by combining two members. The one-piece wheel has the advantages that the quality is uniform and the rigidity is high because the one-piece wheel is uniform in material, and the one-piece wheel may be inconvenient such as missing or loose parts because it is integrally formed. It has the advantage of not having this, and currently, about 85% of all aluminum wheels are 1-piece wheels. This one-piece wheel can be classified into a cast wheel and a forged wheel according to its manufacturing method. Casting wheels have the advantage of being easy to manufacture, and currently most one-piece wheels are manufactured by casting.

However, the aluminum wheels produced by casting have the following drawbacks. That is, in recent years, weight reduction of automobiles has been promoted, and further weight reduction of wheels has been demanded. However, since the metal structure obtained by casting is not wrought like the structure obtained by forging, and the cast material has defects such as shrinkage inherently, when trying to further reduce the weight of the wheel, It is not possible to obtain sufficient strength.

On the other hand, an aluminum wheel manufactured by forging has a metal structure that is forged and has no internal defects, and therefore has extremely high strength and can be easily made lighter than a cast wheel. is there.

9 to 15 show a conventional method of manufacturing an aluminum wheel by forging in the order of steps (Japanese Patent Laid-Open No. 61-11564).
No. 0, JP-A 61-115641, JP-A 4-167943).

First, as shown in FIG. 9, an aluminum alloy billet 21 is prepared as a material. And FIG.
The billet 21 is forged using the forging dies 31a and 31b shown in (1) to obtain a primary forging material 22.

Next, the forging dies 32a, 32 shown in FIG.
This primary forging material 22 is forged by using b, and the secondary forging material 2
Get 3. After that, the forging dies 33a and 33 shown in FIG.
The secondary forged material 23 is forged by b, and the tertiary forged material 24 is obtained. The portion of the third forged material 24 corresponding to the disk surface of the wheel is formed in substantially the same shape as the final product shape (finished product wheel), and the portion 24a corresponding to the rim portion is larger than the rim portion of the finished product wheel. The wall thickness is large and the length (length in the direction parallel to the central axis) is short.

Next, as shown in FIG. 13, the forging material 24 is subjected to spinning by a spinning machine to form a rim portion and a rear flange portion. That is, the third forged material 24
Is attached to the mandrels 34a, 34b of the spinning machine, and while the forging material 24 is being rotated, the roller 35 is pressed against the portion corresponding to the rim portion and extended in the direction parallel to the central axis to form the rim portion 25 and the rear flange portion. To do.

Next, as shown in FIG. 14, the wheel 26 that has been subjected to the spinning process is housed in a heating furnace 36,
Heat treatment is performed at a predetermined temperature for about 12 hours.

Then, as shown in FIG.
While the 6 is attached to the rotating shaft 37 and rotated, a jig 37a, 37b is pressed against the wheel 26 by a robot to perform chamfering, and then characters or numbers are engraved.
This completes the wheel shown in FIG. 16, for example.
Then, after a shipping inspection, the product is shipped.

[0012]

However, the above-mentioned conventional method for manufacturing an aluminum wheel by forging has the following problems. That is, in the above-mentioned conventional method, a spinning process is required to mold the rim portion into a predetermined shape. In order to form the rim portion into a predetermined shape by the spinning process, usually about 3 passes are required, which requires a long time for processing. Therefore, the product cost of the conventional forged wheel is about three times higher than that of the cast wheel.

The present invention has been made in view of the above problems, and a one-piece forged wheel having high strength and light weight can be manufactured without using a spinning process.
An object of the present invention is to provide a method for manufacturing a light alloy wheel that can reduce product cost.

[0014]

A method of manufacturing a light alloy wheel according to a first invention of the present application is a method in which a light alloy material is crushed to form a disc-shaped disc portion and a cylindrical portion from a peripheral portion of the disc portion. A step of forming a primary processed material having a protruding portion, the protruding length of which is set according to the length of the rim portion of the finished product wheel; and the disk portion obtained by subjecting the primary processed material to forging. To a predetermined shape, and a step of bending the end portion of the protrusion by flaring to form a rear flange portion, wherein the primary processed material is a surface inside the protrusion. The volume at the circumference of the circle formed by the points located 20 mm toward the center of the disk portion from the intersection with the surface of the disk portion is 3.0 of the volume at the corresponding portion of the final forging die. To 3.7 times And butterflies.

In the method for manufacturing a light alloy wheel according to the second invention of the present application, a light alloy material is crushed and processed into a cylindrical disk portion and a cylindrical shape protruding from the peripheral edge portion of the disk portion, and the protruding length thereof is A step of forming a primary processed material having a protrusion set according to the length of the rim portion of the finished product wheel;
And a step of forming the disk portion into a predetermined shape by forging the primary processed material, and a step of bending the end portion of the protrusion by flaring to form a rear flange portion, The primary processed material has a final volume in the circumference of a circle formed by a point located 30 mm from the intersection of the inner surface of the protrusion and the surface of the disk portion toward the center of the disk portion. It is characterized by being set to 2.7 to 3.2 times the volume of the corresponding portion of the forging die.

[0016]

In the method of the present invention, first, the material is processed by crushing to form a primary processed material having a disk portion and a protruding portion protruding from the disk portion in a cylindrical shape. In this case, the length of the protruding portion is substantially the same as the length of the rim portion of the finished product wheel.

That is, in the present invention, a primary processed material having a protrusion having a shape substantially equal to the rim portion of the finished product wheel is formed by crushing, and the disk portion of the primary processed material is subjected to forging. After the disk portion is formed into a predetermined shape by bending, the tip of the protruding portion is bent by flaring to form a rear flange portion. As a result, the spinning process, which was conventionally required to form the rim portion and the rear flange portion, becomes unnecessary, and the wheel shape can be finished in a short time. Therefore, according to the method of the present invention, the manufacturing cost of the light alloy wheel can be reduced as compared with the conventional method.

In this case, in order to avoid forging defects such as shrinkage and through flow, the volume distribution of the forging material (primary processing material) at the time of forging is properly set according to the volume distribution of the final forging die. It is necessary to. The inventors of the present application properly analyze the volume of the forging material at the peripheral edge of the disk surface according to the volume of the corresponding portion of the final forging die by performing analysis by the finite element method (FEM) and actually making an aluminum wheel. It was found that by setting the wheel, a wheel without forging defects can be manufactured.

That is, in the present invention, the point located at a position 20 mm away from the center of the disk portion from the intersection of the inner surface of the protrusion of the forged material (primary processed material) and the surface of the disk portion is continuous. The volume at the circumference of the circle to be formed is 3.0 to 3.7 of the volume at the corresponding portion of the final forging die.
Set to double. The volume of the forging material at the circumference is 3.0 of the volume at the corresponding portion of the final forging die.
If it is less than double, shrinkage may occur at the base end of the rim,
Forging defects such as buckling of the rim are likely to occur. On the other hand, if the volume of the forging material in the circumference exceeds 3.7 times the volume of the corresponding portion of the final forging die, forging defects such as through flow are likely to occur at the base end of the rim portion. Become. When these forging defects occur, it is possible to avoid the generation of defective products by adding a flaw removal process, performing a flaw removal process, and then performing the forging process again. Repeatedly causes increase in product cost. Therefore, the volume on the circumference of the circle formed by the points located 20 mm from the intersection of the inner surface of the protruding portion of the forged material (primary processing material) and the surface of the disk portion to the disk center side Should be set to 3.0 to 3.7 times the volume in its corresponding part of the final forging die.

Alternatively, instead of setting as described above, the forging material (primarily processed material) is located at a position 30 mm from the intersection of the inner surface of the protruding portion and the surface of the disk portion toward the center of the disk portion. The volume of the forging material on the circumference of a circle formed by a certain point may be set to be 2.7 to 3.2 times the volume of the corresponding portion of the final forging die. Also in this case, the occurrence of forging defects can be avoided. That is, when the volume of the forging material on the circumference is less than 2.7 times the volume of the corresponding portion of the final forging die, shrinkage occurs at the base end portion of the rim portion or the rim portion is seated. Forging defects such as bending tend to occur. On the other hand, if the volume of the forging material on the circumference exceeds 3.2 times the volume of the corresponding portion of the final forging die, forging defects such as through flow are likely to occur at the base end of the rim portion. Become. For this reason, the volume distribution of the forging material is made in the circumference of a circle formed continuously by the points located 30 mm from the intersection of the inner surface of the protruding portion of the forging material and the surface of the disk portion to the center side of the disk portion. When setting, it is necessary to set the volume of the forging material on the circumference to 2.7 to 3.2 times the volume of the corresponding portion of the final forging die.

The crushed work material may be subjected to a work such as cutting, and the volume distribution of the disk peripheral portion may be set as described above as the primary work material (forging material).

[0022]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

1 to 5 are views showing a method of manufacturing a light alloy wheel according to an embodiment of the present invention in the order of steps.

First, as shown in FIG. 1, a billet 1 is obtained by cutting an ingot of an aluminum alloy into a predetermined size.

Next, as shown in FIG. 2, the crushing die 11
Billet 1 is crushed using a and 11b, and 1
The next processed material (forged material) 2 is obtained. FIG. 7 shows the primary processed material 2
FIG. In this crushing process, the thickness and length of the protruding portion 2a of the primary processed material 2 are made substantially equal to the thickness and length of the rim portion of the finished product wheel. Also,
The volume at the circumference of a circle formed by a point located 20 mm toward the center of the disc from the intersection of the inner surface of the protrusion 2a and the surface of the disc is the final forging die described later. 3.0 to 3. of the volume in the corresponding part.
7 times, or 30 mm from the intersection of the inner surface of the protrusion 2a and the surface of the disk portion to the disk center side
The volume on the circumference of the circle formed by the points at the positions that are just entered is 2.7 to 3.2 times the volume of the corresponding portion of the final forging die described later.

Next, as shown in FIG. 3, forging die 12
Forging the primary processed material 2 using a and 12b (rough cutting)
Then, the secondary processed material 3 is obtained. After that, as shown in FIG. 4, forging (finishing) is performed using the forging dies (final forging dies) 13a and 13b to obtain the tertiary processed material 4. By this rough forging and finishing forging, the disc portion is formed into a predetermined shape.

Next, as shown in FIG. 5, the tip of the protruding portion 2a of the tertiary processed product 4 is bent by flaring to form the rear flange 5 into a predetermined shape.

Then, after heat treatment and pickling,
The valve seat is formed while cutting the rim (protrusion). As a result, for example, a one-piece aluminum wheel having the shape shown in FIG. 6 is completed.

Conventionally, it has been considered difficult to manufacture, for example, a five-spoke one-piece aluminum wheel shown in FIG. 6 by forging, but according to the above-described embodiment method, the disk portion is previously crushed to be crushed. Also, since a primary processed material having a protrusion having a shape substantially the same as the rim portion of the finished product wheel is formed and the primary processed material is subjected to forging to manufacture the wheel, the shape as shown in FIG. 6 is obtained. Wheels and more complex shaped wheels can be easily manufactured. Further, according to the method of this embodiment, the spinning process is unnecessary, and the time required for manufacturing can be shortened to about 1/10 of the conventional time. Therefore, there is an effect that the product cost can be reduced as compared with the conventional case.

Further, according to the method of this embodiment, even in the case of wheels having different designs of the disk portion, the primary processed material formed by the same crushing die can be used if the sizes are the same. It is also possible to reduce the cost of wheels with small quantities. It should be noted that the processed material after the crushing processing may be subjected to cutting processing or the like to adjust the volume distribution to be used as the primary processed material (forged material).

Next, the result of actually manufacturing an aluminum wheel by the method of this embodiment will be described in comparison with a comparative example.

A spoke type aluminum wheel was manufactured by the method shown in FIGS. In this case, the volume distribution of the primary processed material (forged material) was variously changed. Figure 8
FIG. 6 is a graph showing the volume distribution of forging material in Examples and Comparative Examples, where the horizontal axis represents the wheel measurement position and the vertical axis represents the ratio of the forging material volume to the die volume. In addition,
The measurement position 17 on the horizontal axis is the position of the intersection of the inner surface of the protrusion and the surface of the disk portion (hereinafter referred to as the spoke root rim side), and the smaller the measurement position number, the closer to the disk center. . The distance between each measurement position is 10m.
m.

In the embodiment, the ratio of the material volume to the mold volume is 3.37 at a position 20 mm (measurement position 15) from the spoke root rim side, and 3 from the spoke root rim side.
The ratio of the material volume to the die volume at the 0 mm position (measurement position 14) is set to 2.71. In Comparative Example 1, the ratio of the material volume to the mold volume at a position 20 mm (measurement position 15) from the spoke root rim side is 1.98, and at a position 30 mm from the spoke root rim side (measurement position 14). The ratio of material volume to mold volume is 1.
It is set to 47. Further, in Comparative Example 2, a position 20 mm from the root rim side of the spoke (measurement position 15)
The ratio of the material volume to the mold volume is set to 2.99, and the ratio of the material volume to the mold volume at a position (measurement position 14) 30 mm from the spoke root rim side is set to 2.21. Furthermore, in Comparative Example 3, the ratio of the material volume to the mold volume at a position 20 mm (measurement position 15) from the spoke root rim side is 3.77, and a position 30 mm from the spoke root rim side (measurement position 14). The ratio of the material volume to the mold volume in is set to 3.28.

As a result, in the example, forging defects did not occur and an aluminum wheel having a good shape could be manufactured. On the other hand, in Comparative Example 1, shrinkage occurred on the back surface in the vicinity of the root of the spoke, and a defect called fogging also occurred on the disk surface. Further, in Comparative Example 2, shrinkage occurred on the back surface near the root portion of the spoke, and buckling occurred on the spoke portion. Furthermore, in Comparative Example 3, flow through occurred at the root portion of the spoke.

[0035]

As described above, according to the present invention, firstly, a primary processed material is formed which has a disk portion and a protruding portion thereof, the protruding portion being set according to the length of the rim portion of the finished product wheel. Then, after forging the primary processed material, the end portion of the protruding portion is bent by flaring to form the rear flange portion. Therefore, the flaring process conventionally required for manufacturing a one-piece forged wheel is performed. Is unnecessary, and the time required for manufacturing can be significantly shortened. Therefore,
According to the method of the present invention, there is an effect that the product cost of the one-piece forged wheel can be reduced as compared with the conventional method.

[Brief description of drawings]

FIG. 1 is a perspective view showing one step of a method for manufacturing a light alloy wheel according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing one step of the same manufacturing method.

FIG. 3 is a cross-sectional view showing one step of the same manufacturing method.

FIG. 4 is a cross-sectional view showing one step of the same manufacturing method.

FIG. 5 is a cross-sectional view showing one step of the same manufacturing method.

FIG. 6 is a perspective view showing an example of an aluminum wheel after completion.

FIG. 7 is a perspective view showing a primary processed product after the crushing process.

FIG. 8 is a graph showing volume distribution of forging material in Examples and Comparative Examples.

FIG. 9 is a perspective view showing one step of a conventional method for manufacturing an aluminum wheel by forging.

FIG. 10 is a cross-sectional view showing one step of the same manufacturing method.

FIG. 11 is a cross-sectional view showing one step of the same manufacturing method.

FIG. 12 is a cross-sectional view showing one step of the same manufacturing method.

FIG. 13 is a plan view showing one step of the same manufacturing method.

FIG. 14 is a plan view showing one step of the same manufacturing method.

FIG. 15 is a plan view showing one step of the same manufacturing method.

FIG. 16 is a perspective view showing an example of a completed aluminum wheel.

[Explanation of symbols]

1, 21; Aluminum alloy billet 2; Primary processed material 3; Secondary processed material 4; Tertiary processed material 5; Rear flange 11a, 11b; Crushing die 12a, 12b, 13a, 13b, 31a, 31b, 3
2a, 32b, 33a, 33b; Forging die 35; Roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Koike 3-1-1 Kaneshiro-cho, Kita-ku, Nagoya-shi, Aichi Kobe Steel Works, Ltd. Nagoya factory

Claims (2)

[Claims] 1. A light alloy material is crushed to project into a disc-shaped disc portion and a cylindrical portion from the peripheral portion of the disc portion, and the protrusion length is set according to the length of the rim portion of the finished product wheel. Forming a primary processed material having a protruding portion formed thereon, forging the primary processed material to form the disk portion into a predetermined shape, and flaring the end portion of the protruding portion. And a step of forming a rear flange portion by bending with the primary processed material entering from the intersection of the inner surface of the protrusion and the surface of the disk portion to the center of the disk portion by 20 mm. Of a light alloy wheel characterized in that the volume at the circumference of a circle formed by the points at the positions is set to 3.0 to 3.7 times the volume at the corresponding portion of the final forging die. Production method. 2. A light alloy material is crushed to form a disc-shaped disc portion and a cylindrical portion projecting from the peripheral portion of the disc portion, and the protrusion length is set according to the length of the rim portion of the finished product wheel. Forming a primary processed material having a protruding portion formed thereon, forging the primary processed material to form the disk portion into a predetermined shape, and flaring the end portion of the protruding portion. And a step of forming a rear flange part by bending the first processed material into the disk part center side from the intersection of the inner surface of the protrusion and the surface of the disk part by 30 mm. Of a light alloy wheel characterized in that the volume of the circumference of the circle formed by the points at the positions is set to 2.7 to 3.2 times the volume of the corresponding portion of the final forging die. Production method.