Aluminum alloy automotive sheet and tube hydroforming process

[China Aluminum Industry Network] The average surface quality of aluminum alloys processed by ordinary stamping processes is poor, and the yield rate is low (only about 70%), which cannot meet the requirements for high precision, high reliability, high efficiency, and low defect manufacturing of body parts. The hydroforming technology of auto body parts has been applied in the automotive industry in developed countries such as Europe, America, Japan and South Korea. The high pressure of the equipment has reached 400 MPa. The aluminum alloy auto engine hood inner and outer panels, door inner and outer panels and fenders are processed. The cover has been loaded into the car. Large aluminum castings and hydroformed parts are the two core technologies of the Audi A8.

The advantages of hydroforming compared to the stamping process are as follows.

(1) Reduce the blank size and save material.

(2) Improve the forming limit and reduce the number of molding passes.

(3) The surface quality and dimensional accuracy of parts are greatly improved.

(4) Reduce the number and cost of matching tools.

(5) Reduce subsequent machining and assembly welding.

(6) It is possible to form parts with complex shapes, large deformation, and high integrity requirements.

This technology has become the mainstream technology for car lightweighting in foreign countries, and it has developed toward integration, speed, large-scale, and accurate. Although China has succeeded in the development of large-tonnage prototypes, such as 1600t and 1050t plate hydroforming equipment, there are still some major difficulties in the promotion and application of aluminum plate hydroforming technology in China.

(1) Lack of knowledge based on aluminum plate hydroforming design knowledge. The hydroforming knowledge provided to the designers is not systematic or comprehensive, resulting in the inability of our designers to take into account the application of hydroforming technology to lightweight structures.

(2) There is insufficient research on the formability and quality control system of aluminum sheet facing hydraulic forming technology. The results of studies on the formability and quality control of most aluminum sheet facing ordinary press forming do not apply to hydroforming techniques.

(3) A lot of tooling molds and ultra-high pressure hydraulic source systems have yet to make breakthroughs in the key technologies for industrialization.

(4) Research on equipment-wide linkage equipment with aluminum plate hydroforming as the core is incomplete. Due to the above reasons, the parallel operation system oriented to industrialization has not been practically applied. The tooling and mold development are difficult to form and the commissioning cycle is long. Therefore, the cost is relatively high and it is still rarely used in domestic models.