Stretch forming is a stamping process in which the plate is formed into an open hollow part using a processing method. As one of the main stamping processes, drawing has been widely used. The drawing process can be used to manufacture thin-walled metal stamping parts with irregular shapes such as cylindrical, rectangular, trapezoidal, spherical, conical and parabolic. If combined with other stamping processes, more complex parts can be produced.
1. The design of drawing hardware stamping parts should be simple and symmetrical as far as possible, and can be drawn once. In the design of drawing parts, it should be noted that the external or internal dimensions must be guaranteed;
2. The wall thickness tolerance or thinning of metal stamping parts in deep drawing should not exceed the variation law of drawing process wall thickness. Generally, the maximum thickness of tube wall is (0.2 ~ 0.3) t, and the maximum thinning amount is (0.1 ~ 0.18) t, where t is the sheet thickness.
3. For the workpiece to be drawn for several times (H ＞ 0.5d), the inner and outer walls or flange surface of flange drawing parts shall be allowed to have indentation during drawing.
4. On the premise of ensuring the assembly requirements, the side wall of the drawing part should be allowed to have a certain slope.
5. All dimensions not noted on the part drawing belong to free dimension. The dimension tolerance can be determined according to IT14 level by looking up the tolerance table. The dimension in the diameter direction and height direction of the part meets the requirements of the part tolerance grade in the drawing process.
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