Learn from all kinds of metal stamping mold development and manufacturing experience, deep drawing mould is not good, because the material produce flow, and stamping the springback problem is sometimes very headache, there is no accurate reliable formula of springback, are generally not everyone by experience, according to different materials, different R Angle to compensate. So what are the factors that affect the rebound of metal stamping parts?
1. Mechanical properties of stamping materials
There are different strength metal stamping parts on the car body, from ordinary plate to high strength plate, different plates have different yield strength, the higher the yield strength of the plate, the more prone to rebound phenomenon, especially DP series dual phase high strength steel.
2. Thickness of stamping material
In the process of forming, sheet thickness has a great influence on the bending performance, with the increase of sheet thickness, rebound phenomenon will gradually reduce, this is because with the increase of sheet thickness, the increase of the material involved in plastic deformation, and then elastic recovery deformation is also increased, therefore, the rebound becomes smaller.
With the continuous improvement of material strength level of thick sheet metal parts, the dimension accuracy of parts caused by springback is becoming more and more serious. The nature and size of springback of parts are required to be understood in mold design and later process debugging, so as to take corresponding countermeasures and remedy schemes.
3. Shape and complexity of stamping parts
The springback of parts of different shapes is very different, and parts of complex shape will generally add a sequence shaping to prevent springback phenomenon if the forming is not in place, and more parts of special shape are prone to springback phenomenon, such as U-shaped parts, in the analysis of forming process, must consider the springback compensation.
4. Stripper blank holder force of die parts
The blank holder force stamping process of die stripper is an important technological measure. By optimizing the blank holder force, the flow direction of material can be adjusted and the stress distribution inside the material can be improved. The increase of blank holder force can make the part draw more fully, especially the part side wall and R Angle position. If the forming is sufficient, the internal and external stress difference will be reduced, so that the rebound will be reduced.
5. Die drawing bar
Mould drawbead has been widely applied in today's technology, reasonable setting the location of the drawing, can effectively change the direction of material flow and distribution of effective pressure on the surface of the feeding resistance, thus improve the material formability, prone to springback parts on drawbead, can make the parts forming more fully, the stress distribution more uniform, thereby the springback decrease.
How to control the rebound of metal stamping parts
The best time to reduce or eliminate stamping springback is during product design and die development. With the help of CAE springback analysis in the early stage, the springback amount is predicted accurately, the product design and process are optimized, and the product shape, process and compensation are used to reduce springback. And in the hardware mold debugging stage, we must strictly follow the guidance of process analysis to try the mold. Compared with ordinary SE analysis, the workload of springback analysis and correction is increased by 30% ~ 50%, but the mold debugging cycle can be greatly shortened.
Springback is closely related to drawing forming process. Under different drawing conditions (tonnage, stroke and feed amount, etc.), although there is no forming problem for stamping parts, the springback will be more obvious after cutting. The springback analysis and drawing forming analysis use the same software, but the key is how to set the analysis parameters, and the springback results are effectively evaluated.