What does press reverse drawing mean? What are the characteristics and uses of reverse drawing?
There are two basic forms of multiple drawing methods, namely, the forward drawing method and the reverse drawing method. Pressing reverse drawing is a drawing method used to draw the stamping parts as shown in the figure below, and it is also suitable for the second and subsequent drawing of thin materials. There is no significant difference between the positive and negative drawing methods in the deformation mode of the blank. Because of the 180° wrap angle between the blank and the die during reverse drawing, the radial tensile stress is increased, so that the material is not easy to wrinkle, and the drawing coefficient can be reduced by 10-15%. In reverse drawing, the workpiece is easy to be positioned stably, the mold structure is relatively simple, and the height of the punch and the working stroke are smaller than in the case of positive drawing. However, the wall thickness of the die depends on the difference between the diameters of the secondary semi-finished products before and after, and cannot be increased arbitrarily, so it often affects the strength of the die. The change resistance of the material during reverse drawing is larger than that of normal drawing, and the drawing force is also increased by about 20~30%. Therefore, in order to facilitate the flow of materials, the general deep cylindrical drawing parts mostly adopt the positive drawing method. For conical, spherical and parabolic deep drawing parts, in order to avoid the generation of internal wrinkles, the reverse drawing method is often used. Previous post: Several problems that should be paid attention to when processing wide flange cylindrical deep drawing parts