How to solve the problem of necking and pulling of stamping parts when processing aluminum alloy stamping parts of automobiles
Compared with steel parts, the forming process of aluminum parts is more prone to necking and cracking. There are two main reasons for this problem:
First, the stamping formability of the aluminum alloy sheet with the same plastic hardening index n value is much lower than that of the cold-rolled steel sheet. The thickness of the aluminum itself is lower than the anisotropy index, the deep drawability is large, the elongation after partial fracture is low, the forming window is narrow, and the forming capacity is only 1/3 of that of the steel.
Second, aluminum has the characteristics of timeliness. As the heat treatment time increases, the strength, hardness, plasticity and toughness of aluminum itself decrease. Generally speaking, it takes 6 months to produce aluminum coils after heat treatment. In the 6-month production window, the mechanical properties of different batches of aluminum before production vary greatly due to aging, and the difference between mold margin and material properties Poor matching, necking and splitting occur from time to time.
1. The shrinkage treatment plan of the stamping plant is as follows
1. Plate aging control
Aluminum sheet has aging properties, the strength increases with time, the hardness increases, and the plasticity decreases. Before stamping production, due to the different conditions such as the manufacturing process of the plate, the factory state after heat treatment, transportation, and temperature, the mechanical properties of the aluminum plate material before stamping production are quite different, which has a great impact on the production adjustment of the mold, and also leads to frequent production in continuous production. There are problems such as necking and pulling cracks. In order to solve this problem, we can first accumulate the range of mechanical properties for stable production of the mold, and then use the aging characteristics of aluminum to master the timeliness law, and stop using the aluminum with a low yield, so that it is naturally aged, and the yield strength is increased to After the expected range can be produced.
2. Early warning and intermittent supply of aluminum plate mechanical properties.
Renovate the board material card, and print all the board information on the material card, which is convenient for problems in the production process, and can quickly compare and analyze the performance of the material. In addition, the index data of performance problems in production is also summarized and summarized, and the performance early warning range of each aluminum alloy stamping part is formed, and the blue card material is used beyond the time range, which plays a role in early warning of defects.
3. Use digital methods such as Autoform and ATos to help optimize the pulling and cracking of the neck region.
The die set position is prone to necking, especially when the theoretical necking maximum point reported in the drawing simulation or exceeds the safety margin line (FLC), which can be optimized in digital software and equipment.
4. Intelligent grid monitoring system.
According to the experience, the position where the aluminum parts are prone to necking and fracture is summarized, and the mold margin monitoring is carried out on these parts. The main application is the grid strain analysis device (4×5 million pixel three-dimensional stereo camera), the hand-held camera shoots, and the specific situation of the grid strain in the monitoring area can be obtained. It takes about 1 hour from the shooting to the end of the computer operation. The advantage is that it is easy to operate , Fast and easy to calibrate. After the analysis report is output, it will prompt which location is safe and which location is risky. For risk points, mold maintenance personnel evaluate further optimization.
5. Develop equipment with special functions.
In the current stamping parts production equipment, the drawing lower air cushion can realize the function of segmental pressure. The cover plate is set with a small pressure in the early stage of forming, and then the air cushion pressure is set under the segment. The segmental pressure setting can effectively solve the cracking problem of deep-drawn aluminum alloy stampings.
The above is the relevant content of automobile aluminum alloy stamping parts processing. Any machining parts need different machining plans according to their materials and characteristics, and solve problems in a timely manner during the machining process. I hope the above will be helpful to readers.