With the development of high efficiency and automation in automotive stamping production, progressive die will be more widely used in automotive stamping production. Progressive die is a kind of high-tech die product with high technical difficulty, high manufacturing precision and long production cycle. The multi-position progressive die will be one of the key die products in China. The stamping parts with complex shapes, especially the small and medium-sized complex stamping parts which need multi-pairs of stamping dies according to the traditional process, are more and more developed. Many progressive die forming is adopted.
The quality and performance of the die material are important factors that affect the quality, life and cost of the die. In recent years, in addition to a variety of high toughness and high wear resistance cold working die steel, flame quenching cold working die steel, powder metallurgy cold working die steel, the selection of cast iron materials in large and medium-sized stamping dies abroad is a trend worthy of attention. Nodular graphite cast iron has good strength, toughness and wear resistance, its weldability, machinability, surface hardening properties are also good, and the cost is lower than alloy cast iron, so it is widely used in automotive stamping die.
Advanced processing technology and equipment is an important foundation for improving productivity and ensuring product quality. It is not uncommon to find CNC machine tools with double workbenches, automatic tool changer (ATC), photoelectric control system for automatic machining and on-line measuring system for workpieces in advanced automotive die enterprises. NC machining has developed from simple surface machining to full processing of surface and structural surface, from low-speed machining to high-speed machining, and the development of machining automation technology is very rapid.
Stamping technology of high strength steel for automobile dies is the future development direction.
High strength steels are used in automobiles because of their excellent properties such as yield strength ratio, strain hardening characteristics, strain distribution ability and collision energy absorption. At present, the main high strength steels used in automotive stamping parts are paint hardened steel (BH steel), dual phase steel (DP steel), phase transformation induced plasticity steel (TRIP steel), etc. ULSAB expects 97% of the advanced concept vehicle models (ULSAB - AVC) to be made of high strength steel in 2010, and the proportion of advanced high strength steel sheet in the whole vehicle will exceed 60%, and the proportion of dual phase steel will account for 74% of the vehicle steel sheet.
Now a large number of IF steel based soft steel series will be replaced by high strength steel series, high strength low alloy steel will be replaced by dual phase steel and ultra high strength steel plate. At present, the application of high strength steel sheet for automobile parts in China is mostly limited to structural parts and beam parts, and the tensile strength of the materials used is mostly less than 500 MPa. Therefore, to master the stamping technology of high strength steel plate quickly is an important problem to be solved urgently in China's automotive die industry.