Precautions for drawing parts and accuracy of drawing parts

1、 Precautions for stamping and stretching parts

stamping and stretching parts should be as simple and symmetrical as possible, and can be stretched and formed at one time

generally, the wall thickness tolerance or thinning requirements of stamping and stretching parts shall not exceed the variation law of wall thickness in deep drawing process. According to statistics, the larger thickening amount of simple wall in constant thin drawing process is (0.2 ~ 0.3) t, and the larger thinning amount is (0.1 ~ 0.18) t (t is the sheet thickness)

when the deformation degree of parts in one drawing is too large, multiple drawing is required to avoid drawing crack. At this time, on the premise of protecting the required surface quality, the possible traces during the drawing process shall be allowed on the inner and outer surfaces

on the premise of meeting the assembly requirements, the side wall of the drawing part shall be allowed to have a certain slope

when there is a hole on the bottom or flange of the stamping and stretching part, the distance from the hole edge to the side wall shall meet a ≥ R + 0.5T (or R + 0.5T)

the fillet radius of the bottom and wall of the stamping and stretching part, the flange and wall, and the four corners of the rectangular part shall meet: R ≥ T, R ≥ 2T, Rg ≥ 3T, otherwise, the adjustment process shall be added. If only one adjustment is needed, the fillet radius can be R ≥ (0.1 ~ 0.3) t, R ≥ (0.1 ~ 0.3) T.

the radial dimension of stamping and stretching parts should only be marked with the overall dimension or internal dimension, rather than the internal and external dimensions at the same time. For the drawing part with steps, the dimension in the height direction shall generally be based on the bottom of the drawing part

II. Accuracy of stamping and stretching parts

1) the size range of stamping and stretching parts is large, ranging from a few millimeters to a few meters; The precision of drawing parts is also high, up to it10. If finishing drawing is adopted, the precision can reach 1t8, and the surface quality is similar to grinding. Therefore, in the production of automobile, motorcycle, tractor, aircraft, electronic instruments and daily necessities and other industrial sectors, deep drawing technology plays a very important role. 2) Generally, the dimensional accuracy of drawing parts shall be below 1t13 and not higher than 1t11. For deep drawing parts with high precision requirements, the adjustment process shall be added after deep drawing to improve its precision. Due to the influence of material anisotropy, the mouth or flange outer edge of deep drawing parts is generally not competitive, resulting in the phenomenon of "ear making", and the trimming process needs to be added