The use of high-strength panels in body structures can result in body weight reductions of up to 25%, saving about 15% of fuel. Therefore, improving the utilization rate of high-strength plates in body structural parts is of great significance for realizing lighter weight of automobiles, energy conservation, environmental protection, and safety performance.
This article focuses on the fact that the high-strength sheet metal stamping process design and mold manufacturing considerations are mainly introduced in automotive panels.
Stamping
Figure 1 shows a stamped part of the front anti-collision beam that our company undertakes to develop a mold project. Its material is D340LA, material thickness is 1.2mm, external dimensions: length is 1290mm, width is 220mm, height is 67mm.
Figure 1 Front anti-collision beam outer plate
According to the size of the product shown in Figure 1, we can see that the external shape of the product is not complicated, but it belongs to high-strength steel. In general, for the stamping process of high-strength sheet metal parts, problems such as distortion, rebound and warpage of the parts must be solved. Therefore, note the following during the stamping process:
1. Drawing and forming should be sufficient
When the high-strength sheet metal parts are stamped, their shapes should be drawn as far as possible. Do not rely on the later-order burring or shaping process. That is to say, the drawing must be carried out so that the sheet material is fully plastically deformed and reduced. Its own rebound stress. However, how to make the high-strength sheet produce sufficient plastic deformation needs to be achieved through the design of a reasonable process supplement. In the past, the drawbeads of such parts were usually designed to be circular, but for this part, we used square ribs, see Figure 2 and Figure 3.
Fig.2 Numerical simulation of the outer beam of the front anti-collision beam
Fig. 3 Dimensions of drawbars on front outer beam of anti-collision beam
2. Perform CAE analysis
After the digital simulation is done by the drawing forming process, the CAE analysis must be carried out, and based on the results of the analysis, the rebound tendency of the part is determined, and then the data is compensated and the compensated digital model is used as the processing basis. Fig. 4 and Fig. 5 are the drawing process springback compensation for the part.
Fig. 4 Longitudinal rebound compensation of outer beam of front anti-collision beam
3. Determination of punching die surface processing data
After the drawing process, the trimming and punching die face processing data before the trimming process must be based on the final debugged drawing piece, but can not be used as the drawing number after the CAE analysis. Module data prevail. This requires the inverse drawing of the final drawing piece, and then uses the inversely modeled data as a numerical model for machining the edge punching die.
Figure 5 Lateral rebound compensation of the outer beam of the front anti-collision beam
4. Analysis of numerical simulation of edge-turn shaping processing
The CAE analysis and springback compensation are also applied to the numerical model of the flanging and shaping, and this is used as the processing basis for this process. The rebound compensation of the part's flange-shaping operation is shown in Figure 6.
Fig. 6 Springback compensation of the shaping process of the front anti-collision beam outer plate
5. Other attention issues
In addition to the above problems, the staff should also determine the materials of the working parts according to the characteristics of the parts and determine which pieces need special heat treatment.
Mold manufacturing
Although the computer technology is very advanced at present, the objective conditions when using CAE analysis by the computer and the actual environment when the mold work can not be exactly the same, need to be compensated according to the actual situation of debugging in the production debugging. Therefore, it is necessary to take into account the compensation method taken during mold making. The main precautions are as follows:
1. Drawing die
For drawing-type dies, if the dies are cast, the slush-type casting should have more allowance in the mold for later rectification. If the mold uses an insert structure, at least 2 sets of material must be prepared.
2. Trimming and Punching Mould
For the repair type molds after the drawing process and before the flange trimming, the mold surface data must be based on the final debugging pieces.
3 flanging plastic mold
For the flanging and shaping molds, at least two sets of materials must be prepared because the mold working parts mostly adopt the insert structure.
4. Experience accumulation
Record detailed data for each adjustment and accumulate relevant experience in the stamping of such materials.
Conclusion
The above content introduces the stamping process design and mold manufacturing considerations for high-strength sheet metal in automotive panels. These precautions have been fully applied to the development of the front anti-collision beam outer shell mold and have been used very successfully. Not only satisfied the customers to shorten the production cycle, improve product quality requirements, but also for our plant development of high-strength sheet mold has accumulated valuable experience, so that our plant's overall stamping technology has risen again a new level.
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