Why is the stretch of a stretch to be made when it needs to be stretched? This is because the multiple stretching can make the total extension coefficient and the production efficiency is greatly improved, and the product can be ensured by the multi - pass drawing. , a molding is the need for technology, pull the bad all scrapped, many times to pull the uniform, thereby reducing the amount of scrap. This is to the middle of the stress, annealing softening, not easy to produce waste. Under the premise of the tensile parts, 2 need to be made in many parts, in order to guarantee the quality of the surface of the premise, the guarantee of the surface quality of the premise, 1 in line with a certain angle; 3 in the case of guarantee, in line with a certain angle; 4 in the case of the guarantee, in the case of a certain pitch; 6 in the top of the wall, flange and wall, flange and wall, flange and wall, flange and wall of the wall, flange and wall, flange and wall, flange and wall, flange and wall, flange and wall, flange and wall, flange and wall, flange and wall: 5. Corners radius: four corners radius: drawing radius, drawing radius, radius, flange and wall., should be indicated to ensure that the shape of the size, or the inner dimension, can not be marked inside and outside the shape.