Method for Manufacturing a Rim

Abstract

A method for manufacturing a rim is provided to overcome the problem that the strength of the rim as manufactured by the conventional manufacturing method reduces due to the annealing of the welding operation. The method includes processing a first material with a cold stamping process to form a disc embryo, with the first material being made of steel; processing a second material with a cold rolling process to form a rim embryo, with the second material being made of steel; coupling the disc embryo and the rim embryo with each other by a welding approach to form a semi-processed rim; and processing the semi-processed rim with a hot stamping process to form the rim.

Claims

1. A method for manufacturing a rim, comprising: processing a first material with a cold stamping process to form a disc embryo, wherein the first material is made of steel; processing a second material with a cold rolling process to form a rim embryo, wherein the second material is made of steel; coupling the disc embryo and the rim embryo with each other by a welding approach to form a semi-processed rim; and processing the semi-processed rim with a hot stamping process to form the rim.

2. The method for manufacturing the rim as claimed in claim 1, wherein processing the semi-processed rim includes sending the semi-processed rim to a heating furnace having a temperature of 1050-1280 C. for heating and stamping operations.

3. The method for manufacturing the rim as claimed in claim 1, wherein the first and second materials are high-strength alloy steel.

4. The method for manufacturing the rim as claimed in claim 1, wherein processing the first material with the cold stamping process includes performing 5-7 rounds of the cold stamping process on the first material to form the disc embryo.

5. The method for manufacturing the rim as claimed in claim 1, wherein processing the second material with the cold rolling process includes performing 4-6 rounds of cold rolling process on the second material to form the rim embryo.

6. The method for manufacturing the rim as claimed in claim 1, wherein the welding approach is gas-shielded arc welding.

7. The method for manufacturing the rim as claimed in claim 1, wherein the welding approach is full welding.

8. The method for manufacturing the rim as claimed in claim 1, wherein processing the semi-processed rim includes a quenching process.

9. The method for manufacturing the rim as claimed in claim 1, wherein processing the first material includes forming a plurality of decorative holes on the disc embryo.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

[0020] It is another objective of the invention to provide a method for manufacturing a rim where the welded parts of the rim are not annealed.

[0021] FIG. 1 shows a flowchart of a method for manufacturing a rim according to a preferred embodiment of the invention.

[0022] FIG. 2 is an exploded, perspective view of a rim according to the preferred embodiment of the invention.

[0023] FIG. 3 is a cross sectional view of the rim after assembly according to the preferred embodiment of the invention.

[0024] In the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms first, second, inner, outer and similar terms are used hereinafter, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings, and are utilized only to facilitate describing the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0025] FIG. 1 shows a method for manufacturing a rim according to a preferred embodiment of the invention. The method includes a disc portion forming step S1, a rim portion forming step S2, a welding step S3 and a hot stamping step S4.

[0026] Referring to FIGS. 1 and 2, the disc portion forming step S1 is configured to process a first material with cold stamping process to form a disc embryo 1. The first material is a disc embryo which is carbon steel having a carbon content of 0.08-2%. Alternatively, the first material is alloy steel. Based on this, the first material can have a rust resistance or acid resistance and can be high-strength alloy steel to possess excellent rigidity. The invention is not limited to any option. The disc embryo 1 includes a body 11 having a through-hole 12 at a center thereof, a plurality of screw holes 13 surrounding the body 11, and a coupling portion 14 on an outer periphery thereof. In the cold stamping process of the invention, the first material is sent to the stamping machine to undergo the processes such as cutting, bending, stretching, etc. Since it is not required to cope with the rebounding of the metal, the disc embryo 1 can be obtained in 5-7 rounds of processing. The disc embryo 1 needs to undergo a certain number of rounds of the processing until the through-hole 12 and the screw holes 13 are formed and the coupling portion 14 is completely shaped.

[0027] Besides, the disc portion forming step S1 is also configured to form a plurality of decorative holes 15 on the disc embryo 1. The decorative holes 15 are located between the screw holes 13 and the coupling portion 14 and are not limited to any shape. For example, each decorative hole 15 is in a circular, triangular or trapezoid shape. The decorative holes 15 are preferably arranged in pairs. Thus, the decorative holes 15 can enhance the circulation of the air while providing an aesthetic effect.

[0028] The rim portion forming step S2 is configured to process a second material with cold rolling process to form a rim embryo 2. The second material is a steel coil which is carbon steel having a carbon content of 0.08-2%. Alternatively, the second material is alloy steel. Based on this, the second material can have rust resistance or acid resistance and can be high-strength alloy steel to possess excellent rigidity. The invention is not limited to any option. Then, the second material undergoes some processes to form a narrow, thin steel plate, such as, but is not limited to, cutting, flattening, etc. In the cold rolling process of the rim embryo 2, the second material is sent to a rolling mill to undergo a rolling process, a bending process, etc. Thus, the second material can be rolled into a circular form. The head and terminal ends of the rolled second material are welded together to form an enclosed structure, which then undergoes a plurality of rounds of precise-shaping processes to form the rim embryo 2. The rim embryo 2 includes a peripheral body 21. A protruding part 22 is formed at each of two ends of the peripheral body 21. An engagement portion 23 is formed on an inner periphery of the rim embryo 2. Since it is not required to cope with the metal rebounding that occurs in the case of cold rolling process, the rim embryo 2 can be formed after 4-6 rounds of rolling and bending processes. The rim embryo 2 needs to undergo a certain number of rounds of the processing until a rim is substantially shaped in a manner that the engagement portion 23 of the rim embryo 2 can match the coupling portion 14 of the disc embryo 1.

[0029] The welding step S3 is configured to couple the coupling portion 14 of the disc embryo 1 and the engagement portion 23 of the rim embryo 2 with each other by welding, so as to form a rim. In this embodiment, gas-shielded arc welding is used to couple the coupling portion 14 and the engagement portion 23 by fusion bonding. The operation of the gas-shielded arc welding is not limited to the space and is convenient. Also, the gas-shielded arc welding can smelt the welded parts into a fused state and therefore forms a secure welded structure after welding. The disc embryo 1 and the rim embryo 2 form a semi-processed rim after welding. A welded part W of the coupling portion 14 and the engagement portion 23 is welded by full welding to provide a more secure welding quality.

[0030] The hot stamping step S4 is configured to process the semi-processed rim with hot stamping process to produce a rim as a finished product. In the hot stamping process, the semi-processed rim is sent to a heating furnace having a temperature of 1050-1280 C. to soften the steel material. Then, the softened steel material is sent to a hot stamping machine to undergo the stamping processes, precisely shaping the semi-processed rim into a desired shape or further adjusting the thickness of the semi-processed rim to a meet the requirement. Thus, a rim is formed as a finished product. In addition, the rim as a finished product can be cooled down by a cooling system in a quenching process, thus obtaining a Martensite crystal structure. Accordingly, the welded part W can also be re-heated and quenched so that the heat affected zones are not annealed, forming a high-strength rim.

[0031] In summary, in the method for manufacturing a lightweight and high-strength rim according to the invention, the steel material will have a higher strength after the hot stamping process. In the same time, the heat affected zones are heated and quenched. Thus, the heat affected zones are not annealed, and the strength after the hot stamping processes is not adversely affected by the softening of the heat affected zones. Therefore, under the same weight, the rim according to the invention has a higher strength compared with the other rims. On the contrary, under the same strength, the rim according to the invention can have a smaller thickness compared with the other rims. As a result, the weight of the rim can be reduced, reducing the fuel consumption.

[0032] Although the invention has been described in detail with reference to its presently preferable embodiments, it will be understood by one of ordinary skill in the art that various modifications can be made without departing from the spirit and the scope of the invention, as set forth in the appended claims.