Patent Application
20090113713
1. Field of the Invention
The invention relates to a method for making a wheel rim, more particularly to a method for making a wheel rim involving a casting step.
2. Description of the Related Art
Referring to
1) forging a solid metallic block 1 into a wheel rim blank 5 using different forging molds 2, 3, 4;
2) heat-treating the wheel rim blank 5;
3) spinning the wheel rim blank 5 using a spinning device 6 to form a rim body 501 for the wheel rim blank 5; and
4) milling a solid disk portion of the wheel rim blank 5 and turning a lateral wall portion of the rim body 501 to form a wheel rim 7 having a plurality of ribs 701.
Although the conventional method can be used to make the wheel rim 7, it has the following shortcomings:
1. Since the solid metallic block 1 is used to make the wheel rim blank 5, a plurality of forging procedures using a variety of forging molds are required. Furthermore, an additional heat treatment using a heating furnace is required between two forging procedures. Therefore, the forging step for forming the wheel rim blank 5 of the conventional method should be conducted using a variety of processing devices, and thus is costly and time-consuming.
2. It takes about 4 hours to accomplish the milling of the solid disk portion of the wheel rim blank 5, and a large amount of waste material is produced after the milling procedure. Therefore, the milling procedure is also time-consuming and costly.
3. If the wheel rim to be made has a relatively large size, the numbers of the forging and heat-treating procedures are increased due to the limitation of the allowable deformation for each of the forging procedures. Therefore, it is more difficult to make a wheel rim having a relatively large size using the conventional method.
The object of the present invention is to provide a method for making a wheel rim that can overcome the aforesaid shortcomings of the conventional method for making a wheel rim.
Accordingly, a method for making a wheel rim of the present invention includes the steps of:
A) casting an aluminum alloy containing silicon and magnesium into a blank including a lateral portion and a disk portion that is surrounded by the lateral portion and that has a plurality of radial elements extending toward and connected to the lateral portion;
B) forging the disk portion of the blank to form the radial elements into radial ribs;
C) solution heat-treating the blank after forging; and
D) spinning the lateral portion to form a rim body.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:
Referring to
1) Preparing an Aluminum Alloy:
Preferably, the aluminum alloy used in the method of the present invention includes 3-6 wt % Si, 0.4-0.7 wt % Mg, 0-0.1 wt % Cu, 0-0.12 wt % Fe, 0-0.05 wt % Mn, 0-0.05 wt % Zn, 0-0.05 wt % Ni, 0-0.25 wt % Ti, and a balance of Al, based on the total weight of the aluminum alloy. In the preferred range of the Si amount, the flowability and the feeding effect of the molten aluminum alloy during the following casting step is improved as the Si amount is increased. Better surface finish of a cast blank can be obtained as the Si amount is increased. Additionally, in the preferred range of the Mg amount, the mechanical strength of the cast blank can be improved as the Mg amount is increased due to the increased amount of Mg2Si.
2) Casting:
Referring to
3) Forging:
Referring to
4) Solution Heat-Treating:
The blank 10 after forging is treated by a solution heat-treatment, which is conducted by heating the blank 10 to a temperature ranging from 520 to 540° C. for a period ranging from 4 to 8 hours, and water-quenching the blank 10.
5) Spinning:
Referring to
6) Aging-Treating:
The blank 10 is aging-treated by heating the blank 10 to a temperature ranging from 140 to 160° C. for a period ranging from 1 to 7 hours, and air-cooling the blank 10.
7) Finishing:
Referring to
1. The blank 10 made by the casting step of the present method is formed with the disk portion 11 having a profile similar to that of a corresponding portion of the wheel rim 20 to be made. Furthermore, the blank 10 is then processed by a single forging step. Therefore, the aforesaid shortcomings of the prior art due to the requirement of a plurality of forging procedures can be avoided.
2. The blank 10 made by the casting step of the present invention is formed with a plurality of radial elements 13, which are then forged to form the radial ribs 14. Therefore, the time-consuming milling procedure required in the prior art can be avoided, and the waste material produced by the present method can be significantly reduced as compared to the prior art.
3. Since a single forging procedure is required in the present method, the problem regarding the limited allowable deformation of the forging procedures of the prior art can be avoided.
4. Since the blank 10 is made by casting using a suitable mold, the flexibility of the shape of the wheel rim 20 can be increased by the present method.
5. Since suitable amounts of Si and Mg are included in the aluminum alloy used in the present method, the aluminum alloy has a suitable flowability for the casting procedure and a sufficient deformation for the forging procedure.
While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
