KR102356668B1 - Manufacturing method and apparatus for complicated shaped disk alloy wheel - Google Patents

Abstract

Disclosed is a method for manufacturing an aluminum wheel for a vehicle, which can manufacture a complicatedly shaped disk wheel by using a forging process, thereby improving formability and mechanical strength. The method has the following features of: 1) improving formability through step-by-step multi-stage pressurization including upsetting; 2) extruding the front after extruding the rear, and forging a trapezoidal material by adjusting the inclination angle (slope angle) of the exterior; 3) installing protrusions at an upper end between the outer frame of a mold and a lower mold so that the material passes between the protrusions during the forging to obtain an effect of the extruding; 4) installing protrusions at a lower end between the outer frame of the mold and the lower mold in the case of products with ribs protruding from the back of a disk, to control the forging speed of the material; and 5) cutting the material, preheating the same, coating the same with a release agent solution, executing main heating thereof, and forging the same to improve the complicated flow of the material during the forging.

Description

Manufacturing method and apparatus for complicated shaped disk aluminum wheel {Manufacturing method and apparatus for complicated shaped disk alloy wheel}

The present invention relates to a method for forging an aluminum wheel for a vehicle, and more particularly, to a method and apparatus for manufacturing an aluminum wheel for a vehicle capable of improving the formability and mechanical strength of a disc-shaped aluminum wheel with a complex shape using a hot forging process. it's about

In general, a vehicle wheel includes a rim (rim) and a disk (disk). The rim is a part that is in close contact with the tire to maintain air pressure, and is a part that forms the outer shape of the wheel. The disc is the inner part (center) of the rim, and has a flat section mounted on the axle hub of the vehicle and a curved section connected to the rim. It supports the rim so that it is not deformed by

Wheels for vehicles are classified in various ways according to their structure or design. For example, in terms of structure, it is divided into one-piece, two-piece, and three-piece wheels according to the number of components.

The one-piece wheel is made by molding the rim and disk in a single mold. It is easy to manufacture and secures rigidity, so there is little variation in quality, but it is difficult to realize various designs and weight reduction in terms of technology. A two-piece wheel is a wheel in which the rim and disk are separately formed or only the outer rim is separately formed and welded or bolted together. Therefore, various designs and weight reduction are possible. In addition, the three-piece wheel is a wheel assembled by separately forming an outer rim, an inner rim, and a disk and fastening them with bolts. It is advantageous for stylish and diverse designs and light weight.

Currently, most vehicle wheels are manufactured from an aluminum (Al) alloy material advantageous in lightness. The manufacturing method is largely divided into a casting method and a forging method. The casting method is a method of pouring molten aluminum alloy into a mold, and the forging method is a method of heating, pressing, and cutting an alloy material.

The problem is the case of forging a disc wheel with a complex shape using a high-strength alloy. Currently, the design aspect of the wheel is being emphasized, and the shape of the wheel is becoming more complicated, making it difficult to apply the forging method. The complex-shaped disc wheel means a wheel in which the position of the disc 10 is close to the center of the rim 20 or is designed downward, like the M-shaped wheel of FIG. 1A or the H-shaped wheel of FIG. 1B .

Conventionally, in order to manufacture a disc wheel with a complex shape, a casting method in which aluminum is made into a molten metal and formed is mainly used. However, the conventional method of manufacturing a disc wheel with a complex shape causes shrinkage, pinholes, and foreign substances inside the material during the manufacturing process. In addition, even if forging technology is used to secure excellent mechanical rigidity, it is difficult to form wheel products with complex shapes using conventional forging technology, and especially, it is difficult to apply to mass production because the amount of material wasted is severe.

Republic of Korea Patent Registration No. 10-1303854 (2013.9.4.) Republic of Korea Patent Registration No. 10-0661199 (2006.12.22.)

A method and apparatus for manufacturing an aluminum wheel for a vehicle that improve formability and mechanical strength using forging technology by solving the conventional problem of using a casting method for manufacturing a complex-shaped disc wheel are proposed.

In order to solve the above problems, the present invention provides a method and apparatus for manufacturing a disc aluminum wheel having a complex shape including the following features.

1. During the forging process, formability is effectively improved through step-by-step multi-stage pressurization including up-setting according to the position in the same facility.

2. Attach the outer frame of the upper mold (upper mold) to the upper mold support for the manufacture of H-shaped or M-shaped wheels that are difficult to form because the location of the disk is near the center of the rim or is designed to the lower part, and the lower mold (lower mold) is placed on the lower mold A method of forming the rim in the air after rear extrusion by mounting it at a distance from the support, and then adjusting the inclination angle (slope angle) of the outer frame to form a shape that cannot be formed by front extrusion (for example, trapezoidal shape) of product forging method and mold structure.

3. In order to obtain the effect of the extrusion process by installing or forming lateral projections on the upper part of the outer frame of the upper mold and/or the upper part of the lower mold, the material is extruded through the gap narrowed by the projection(s) during the forging process. method.

4. In the case of the design in which the ribs protrude on the back of the disk of the product, the formability is low. To solve this problem, a protrusion is installed in the lower part of the lower mold in the lateral direction to control the forging speed of the material to make the material uniform. Forging induction and overlap prevention.

5. Sodium tripolyphosphate (10 wt% to 15 wt%) and sodium acrylate (15 wt% to 25 wt%) ) as the main component, coated with a release agent solution with a thickness of 100 μm to 300 μm to perform main preheating.

The configuration and operation of the present invention will become clearer through specific embodiments described later in conjunction with the drawings.

The present invention can also be applied to aluminum wheels of complex shapes with different disk surface positions, such as H-shape or M-shape, so that excellent mechanical rigidity is ensured, and productivity is increased by easy molding of wheel products with complex shapes, and forging Since there is no need to scrape off afterwards, the amount of wasted material is reduced, resulting in cost reduction.

In addition, various materials such as A6061, A2014, A7075 can be used by using the characteristic temperature suitable for the forging characteristics of each material. That is, conventionally, only the materials of A60XX and A20XX could be molded for forging aluminum wheels. However, by applying the multi-stage pressing method and forging speed controllable mold technology according to the present invention, moldability is difficult, so only extrusion or simple molding is possible. Complex shape wheel products made of the A70XX material, which were used previously, can also be manufactured by forging.

1A and a front, rear, and cross-sectional view of an M-shaped section wheel;
1b is a rear view and a cross-sectional view of an H-shaped section wheel;
2 is a flowchart of a method for manufacturing an aluminum wheel according to the present invention;
3 is a detailed process configuration diagram of the forging process 150 of FIG.
4 and 5 are block diagrams of a forging apparatus applicable to the forging process of the present invention
6 is a rear perspective view, a rear view, and a cross-sectional view of an aluminum wheel product having a complex shape;

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the preferred embodiments described in detail below in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described below and may be implemented in various other forms. The examples are only provided to completely disclose the present invention and to completely inform those of ordinary skill in the art to which the present invention pertains to the scope of the invention, and the present invention is defined by the claims will be.

In addition, the terminology used herein is for the purpose of describing the embodiment and is not intended to limit the present invention. In this specification, the singular also includes the plural unless otherwise specified. Also, as used herein, the term 'comprise (comprise, comprising, etc.)' refers to the presence or absence of one or more other components, steps, operations, and/or elements other than the stated elements, steps, operations, and/or elements. It is used in a sense not to exclude addition.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the embodiment, if a detailed description of a related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

2 is a flowchart of a method for manufacturing an aluminum wheel according to the present invention. Basically, the present invention performs 'main preheating after preheating' and 'step-by-step multi-stage pressurization including upsetting'. The process of the aluminum wheel manufacturing method of the present invention will be described with reference to FIG. 2 .

First, the raw material is cut (110). In order to improve the flowability of complex-shaped metal materials during forging, the cut raw materials are preheated to 100° C. to 150° C. (120). A release agent solution containing sodium tripolyphosphate (10% by weight to 15% by weight) and sodium acrylate (15% by weight to 25% by weight) as main components is coated to a thickness of 100 μm to 300 μm (130). Then, the main preheating is performed at a temperature of 400°C to 530°C (140).

In the past, graphite-based oil-based mold release agents were sprayed and applied to the mold and material to improve mold adhesion or flow formability of the product. After pre-heating to 100° C. to 150° C. before putting it in, the developed aqueous release agent is coated to a thickness of 100 to 300 μm, and preheated to a temperature of 400° C. to 530° C.

After the main preheating operation (140), the forging process (150) is entered.

FIG. 3 shows the configuration of the forging process 150 of FIG. 2 .

The forging process 150 of the present invention includes step-by-step multi-stage pressurization 151 including upsetting according to a position in the same equipment during the forging process in order to effectively improve formability. In the conventional molding method, after setting a pressure target value according to the size and shape of the product, the upper die is pushed down in the lower die direction, and the product is formed with a single oblique inclination in proportion to the position value and the load value. After setting the pressure target value according to the product and shape through multi-stage pressurization, a delay time of 2 to 4 seconds is inserted at about 1/3 of the target pressure to stop the inertia of the initial gradient of pressure and time and pressurize again. It further facilitates the formability of complex shape sections. Then, a delay time of 2 to 4 seconds is inserted at about 2/3 of the target pressure to facilitate the formability of the secondary complex shape area.

In addition, the forging process 150 of the present invention attaches the outer mold to the upper mold and protrudes the lower mold 50 so that the rim of the product is molded longer than the mold in the air, followed by the front extrusion method (152). And, it includes adjusting (153) the inclination angle (gradient angle) of the outer frame in order to produce, for example, a trapezoidal aluminum wheel product that cannot be molded by the front extrusion method.

In addition, the forging process 150 of the present invention includes forming protrusions 154 in the mold to allow the material to pass through the gap narrowed by the protrusions during the forging process to enhance the extrusion effect and control the forging speed of the material.

This forging process 150 will be described in detail with reference to FIGS. 4 and 5 . 4 and 5 are diagrams of a forging apparatus applicable to the forging process 150 according to the present invention.

The mold device used in the forging process 150 of the present invention, as shown in FIGS. 1A and 1B, is designed such that the position of the disk is close to or lower than the center of the rim, such as an H-shaped or M-shaped wheel, which makes forging difficult products. In order to manufacture by forging, the upper mold 40 on which the outer mold 45 is formed is attached to the upper mold support, and the lower mold 50 is spaced from the lower mold support surface without contacting and mounting the lower mold 50 on the support surface (lower mold support surface) of the lower mold support. It adopts a front extrusion after rear extrusion method that allows the rim of the product to be molded in the air longer than the mold by floating it upwards. In addition, by adjusting the inclination angle (gradient angle) of the outer frame 45, it is possible to manufacture a product of a shape (eg, trapezoidal shape) that cannot be molded by a front extrusion method.

That is, as shown in FIGS. 4 and 5 , when forging a product (see FIGS. 1a and 1b ) having a deep disk, which is a reference plane on which the wheel is mounted on a vehicle, the upper part to which the upper mold 40 and the outer frame 45 are attached. When the cylinder 60 is pressed toward the aluminum round bar material 70 put on the lower die 50, rear extrusion occurs based on the upper die in which the material is pushed up from the distribution of the lower die 50 to the upper die, and then the pushed material is the upper die When it collides with the outer frame (45) of (40), it is pushed between the outer frame (45) and the lower mold (50) and forward extrusion is performed. At this time, since the lower mold 50 is floated upward from the lower mold supporting surface, the material passing through the gap between the outer mold 45 and the lower mold 50 is a mold as long as the material is supplied without a separate outer mold 45 . It is molded in the air into a longer tube shape. The part molded into a tube shape in the air becomes the rim part of the product.

In addition, the upper protrusions 80 in the lateral direction from the upper part of the outer mold 45 of the upper mold or in the lateral direction from the upper part of the lower mold 50, or in the upper part of the external mold 45 and the upper part of the lower mold 50 in the lateral direction. ) is formed (or installed) so that the material passes through the gap narrowed by the upper protrusion 80 during forging. Since the aluminum material passes through the gap narrowed by the upper protrusion 80 between the outer frame 45 and the lower mold 50, the cross-sectional area through which the material flows is reduced, the extrusion effect is increased, the density of the material is increased, and the rigidity is improved. .

In addition, in the case of a product having a shape in which ribs protrude from the rear surface of the disk by design, the moldability is poor due to the ribs. In order to solve this problem, in the lateral direction from the lower part of the outer mold 45 of the upper mold 40 or from the lower part of the lower mold 50 to the lateral direction, or the lower part of the outer mold 45 and the lower part of the lower mold 50 . The lower protrusion 90 is formed (or installed) in the lateral direction to control the forging speed of the material to achieve uniform forging of the material and to prevent overlap. If forging is performed when there are ribs on the outer or back surface of the disc, unlike the casting process, the flowability of the material is affected, so it is necessary to control the speed in the rib area (because the cross-sectional area of the area without ribs is small, the flow rate with the rib area is small. difference). In this way, even when a complex shape is set not only on the front part of the product but also on the back part, the forging speed is controlled by reducing the cross-sectional area using the lower protrusion between the outer frame and the lower mold to reduce the partial shape, length, overlap, etc. of the material. can be controlled

By the above process, as in the H-shaped or M-shaped wheel of FIGS. 1A and 1B, the rib is formed not only on products that are difficult to forge because the position of the disk is near or below the center of the rim, but also on the inner surface of the disk as shown in FIG. Aluminum wheel products with complex shapes, such as those that have already been made, can be manufactured through the forging process.

In addition, it is possible to obtain various usability of materials such as A6061, A2014, and A7075 using the characteristic temperature suitable for the forging characteristics of each material. Because, in the past, only A60XX and A20XX could be formed during hot forging of aluminum. However, when applying the multi-step pressing method and the mold technology that can control the forging speed, the complex shape product of A70XX material was difficult to form and only extrusion or simple molding was possible. It is also possible to manufacture

Although the present invention has been described in detail through preferred embodiments of the present invention, those of ordinary skill in the art to which the present invention pertains will realize that the present invention is different from the contents disclosed in the present specification without changing the technical spirit or essential characteristics thereof. It will be understood that the invention may be embodied in other specific forms. It should be understood that the embodiments described above are illustrative in all respects and not restrictive. In addition, the protection scope of the present invention is determined by the claims described below rather than the above detailed description, and all changes or modifications derived from the claims and their equivalent concepts should be interpreted as being included in the technical scope of the present invention. do.

Claims (9)

Aluminum wheel manufacturing method,
preheating the raw material to 100°C to 150°C in order to improve the flowability of the complex-shaped metal material during forging;
coating a release agent containing 10 wt% to 15 wt% of sodium tripolyphosphate and 15 wt% to 25 wt% of sodium acrylate on the preheated raw material to a thickness of 100 μm to 300 μm;
performing main preheating at a temperature of 400° C. to 530° C. on the raw material coated with the release agent; and
and performing a forging process on the raw material after the main preheating. According to claim 1, wherein the forging process,
A method for manufacturing a disc aluminum wheel with a complex shape, including step-by-step multi-stage pressurization including upsetting, according to a position in the same facility during the forging process. The method of claim 2, wherein the step-by-step multi-stage pressurization including the upsetting
After setting the pressure target value according to the product and shape,
At 1/3 of the target pressure, a delay time of 2 to 4 seconds is inserted to stop and pressurize the initial slope inertia of pressure and time,
Then, at 2/3 of the target pressure, a delay time of 2 to 4 seconds is inserted and the second pressurization is performed. According to claim 1, wherein the forging process,
By attaching the upper mold having the outer mold to the upper mold support and mounting the lower mold at a distance from the lower mold support surface, the rim of the product is molded into a tube shape in the air. Complex including performing a front extrusion method after rear extrusion A method for manufacturing a disk-shaped aluminum wheel. According to claim 1, wherein the forging process
Disc aluminum wheel with complex shape, characterized in that the cross-sectional area of the gap through which the material passes during the forging process is reduced by using the upper protrusion protruding laterally on at least one of the upper part of the upper part of the outer frame of the upper mold and the upper part of the lower mold manufacturing method. According to claim 1, wherein the forging process
Disc aluminum wheel with complex shape, characterized in that the cross-sectional area of the gap through which the material passes during the forging process is reduced by using the lower protrusion protruding laterally on at least one of the lower part of the outer frame of the upper mold and the lower part of the lower mold manufacturing method. An apparatus used in the forging process included in the method for manufacturing a disc aluminum wheel with a complex shape according to any one of claims 1 to 3,
an upper die attached to the upper die support and having an outer frame; and
It includes a lower mold mounted at a distance from the lower mold supporting surface to the upper part,
The apparatus for manufacturing a complex-shaped disc aluminum wheel, characterized in that the material input to the lower mold is molded into a tube shape in the air by the lower mold mounted at a distance from the upper mold to form a rim of aluminum. The method according to claim 7, comprising an upper protrusion protruding laterally on at least one of an upper portion of an outer frame of the upper mold and an upper portion of a lower mold,
Complex shape disc aluminum wheel manufacturing apparatus, characterized in that it reduces the cross-sectional area of the gap through which the material passes during the forging process. The method according to claim 7, comprising a lower protrusion protruding laterally on at least one of a lower portion of the outer frame of the upper mold and a lower portion of the lower mold,
Complex shape disc aluminum wheel manufacturing apparatus, characterized in that it reduces the cross-sectional area of the gap through which the material passes during the forging process.

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