Automobile stamping parts should have good craftsmanship and economy. Important indicators to measure their level are the number of stamping parts, the number and size of the body assembly, and the structure of the stamping parts. Reducing the number of processes in the stamping process means reducing the number of stamping parts, saving the number of tooling, simplifying the transfer device of the stamping process, reducing the operator and stamping area. It is an excellent measure to save investment and energy consumption, so stamping manufacturers can The number of stamping processes is designed as an important way to reduce the cost of automobile manufacturing, and even the product design is improved to meet the requirements of the manufacturing process. At the same time, reasonable total body components of the largest possible size should be used, such as one-piece body left and right side panels and roof cover panels, which can make the car beautiful in appearance. The air resistance is reduced, and the number of stamping parts and welding points can be reduced, which can effectively reduce the cost. In addition, modern automobile manufacturing uses a large number of high-strength steel sheets and galvanized steel sheets that use coil materials and thin-shell integral body structures, all requiring the application of new stamping processes.
Automotive outer covering products have always had the characteristics of large area and thin slab. In automobile outer coverings, the hood outer panel is the "face" of the entire automobile, which brings many technical problems to the stamping production. In the actual production of a new car model, it was found that the surface of the engine hood outer plate was prone to partial depression after stamping production, and additional remedial measures such as correction were required.
Analyze the reasons:
The depressions of the engine hood outer plate are basically concentrated in the middle of the engine hood. Based on the above situation, the depressions are fixed. Considering the equipment parameters, the analysis reasons are as follows:
1. Material forming principle analysis
Use a scribe needle to mark the warp and weft lines with a distance of 100mm on a rough hood outer panel. Because the plastic deformation in the middle is not very obvious, the distance between the middle scribe lines is 10mm. After drawing the plate, we found that the grid lines with a spacing of 100mm around them are stretched and bulged after drawing, reaching a spacing of 103mm, while the grid lines with a center spacing of 10mm are still 10mm after being drawn. There is no stretching and bulging process, and no plastic deformation effect is formed. Therefore, we have come to the conclusion: to solve the problem of intermediate collapse, the middle part of the material must be plastically deformed, so as to improve the rigidity and strength of the material.
Therefore, we decided that the specific rectification method is: to achieve the plastic deformation of the material, the mold must be trimmed, and the drawing bead structure of the drawing die must be changed to control the feeding speed, forming the internal material to be larger than the periphery, causing the intermediate material to bulge and increase the engine The outer surface of the cover is rigid.
2. Hydraulic press parameter adjustment
Keep the pressure of the main cylinder of the hydraulic press and the pressure holding time unchanged during the stamping production, and adjust the hydraulic cushion force, as shown in Figure 2. Through the adjustment of on-site parameters, the actual production pressure of the hydraulic cushion is set to 5MPa, which is slightly higher than the process requirement of 3～4MPa, which exceeds the process range. However, from the results, the strength and rigidity of the parts have not been improved. It shows that the setting of hydraulic machine parameters is not the main reason for the surface depression of the part.
