How to solve the springback problem of stamping parts?
- Stress change curve after unloading
(1) From ordinary plates to high-strength steel plates, stampings of different materials and strengths have different yield strengths. The higher the yield strength of the sheet, the easier it is to spring back. In the thick plate components, hot-rolled carbon steel sheets or hot-rolled low-alloy high-strength steel sheets are used as materials. The surface quality of the hot-rolled sheet is higher than that of the cold-rolled sheet, the thickness is small, the mechanical properties are unstable, and the elongation is low.
2. Stress change before and after springback
(2) In the forming process, the thickness of the material has an important influence on the bending performance of the plate. When the thickness of the plate increases, the springback phenomenon gradually decreases. With the increase of the plate thickness, the plastic deformation increases, the elastic recovery deformation increases, and the springback decreases.
3. Tangential stress of board contacts
With the continuous improvement of the quality level of thick plates, the problem of dimensional accuracy of parts caused by springback is becoming more and more serious. In order to understand the resilience properties and dimensions of the parts, take corresponding countermeasures and measures, carry out mold design and process debugging.
The ratio of the bending radius to the thickness of the thick plate is small, and the stress change in the thickness direction cannot be missed.
Parts of different shapes vary greatly in how they spring back on the part. Parts with complex shapes usually increase the number of moldings. They spring back when they are not formed in place, and some fractals are easier to spring back, such as U-shaped pieces, so bixu considers springback compensation when analyzing and forming.
(4) The greater the bending angle, the greater the accumulation of rebound value, and the rebound will generate tension. The deformation length of the stamping part increases with the increase of the bending angle.
(5) When designing the mold, the gap between the molds should not exceed twice the thickness of the material in the working part, and integrate the product into it. In order to obtain better material flow, the partial molding of the mold should be carried out after the mold is processed. Especially for bending dies, the larger the working gap, the larger the springback. When the thickness range of the sheet is small and the springback is large, it is difficult to determine the formwork gap well.
(6) The bending radius is proportional to the amount of springback, so the greater the bending degree, the more difficult it is for the elbow to be bent.
(7) The molding process is an urgency to limit the springback value. Generally speaking, the springback of positive bending is better than that of free bending. If the machining results of the same batch of stampings are the same, the bending force required to correct the bending is much greater than the bending force required for the free bending. Therefore, if both methods involve similar bending forces, the end result will be different. The greater the correcting force required to correct the bending, the smaller the springback of the stamped part, and the correcting moment will elongate the fibers in the deformed area to achieve the forming effect. When the elbow is unloaded, the surface and inner fibers are shortened, but the springback direction of the two sides is opposite, which reduces the outward springback of the stamping part to a certain extent.
The above is how to solve the springback problem of automobile stamping parts. In short, the commonly used materials for automotive stamping parts must not only meet the technical standards of the designed products, but also meet the requirements of the processing technology such as drilling, electroplating, and cleaning after stamping. I hope it helps readers.