1. Deep drawing: drawing products exceeding the limit of drawing can be completed only after more than two times of drawing. After stretching the product in the depth direction of the front station, it will be restretched in the depth direction. The wide flanged stretch is stretched to the desired flanged diameter at the first stretch, and the flanged diameter remains unchanged at the subsequent stretch.
2. Taper drawing: For deep taper parts with h/d>0.8 and α =10° ~ 30°, due to large depth and large deformation degree of billet, forming force is transferred only by local area of contact between billet and punch, it is easy to cause local excessive thinning and even rupture of billet, which needs to be gradually formed after several transitions. The step drawing method firstly stretches the billet into step transition parts, the step shape is tangent to the inner shape of the conical part, and finally expands to form a cone. The tension times and process of step transition parts are the same as that of step cylinder parts.
3, Rectangular redrawing: rectangular part formed by multiple stretches, its deformation is not only different from that of deep cylindrical part, but also very different from that of low box part. Figure 1-46 In the processing of tall rectangular box parts by multi-station automatic transfer press, the shape and size of the parts change with the drawing height in the process of multiple drawing.
4. Surface forming: surface stretching forming, which can reduce the outer flange of metal flat billet and extend the inner flange, forming the hollow products with non-straight wall and non-flat surface shape.
5. Step drawing: The left initial drawing product is redrawn to form the right step bottom. The deeper part deforms at the beginning of the stretch forming and the shallower part deforms at the later stage of the stretch. The lateral wall in the changing part of the step is easy to induce shear stress to produce deformation.
6. Reverse drawing: reverse drawing is a kind of redrawing of the workpiece drawn by the previous process. The reverse stretching method can increase the radial tensile stress and has a good effect on preventing wrinkling. It is also possible to improve the tensile coefficient of redrawing.
7. Ironing: Unlike ordinary drawing, ironing involves changing the thickness of the cylinder wall during the drawing process. The gap between the concave and convex die is less than the thickness of the blank, and the blank straight wall part is under large uniform compressive stress when passing through the gap. During the stretching process, the wall thickness deviation of the container is eliminated, and the smoothness of the container surface is increased, so as to improve the accuracy and strength.
8, Panel drawing: panel products are sheet stamping parts, the surface shape is complex. In the drawing process, the blank deformation is complicated, and its forming property is not simply tensile forming, but the compound forming of deep drawing and expansion simultaneously.
