The surface of precision drawing stamping parts does not have the defects of die casting parts. The shape of the stretched part should be simple and symmetrical, the mouth should be allowed to rebound slightly, and the side wall should be allowed to have a technological slope. The wall thickness of the wall part of the cylinder generally has the phenomenon of being thick at the top and thin at the bottom. The shape of the precision drawing parts should be simple and symmetrical, the mouth should be allowed to rebound slightly, and the side wall should be allowed to have a technological slope. The wall thickness of the wall part of the cylinder generally has the phenomenon of being thick at the top and thin at the bottom. Hardware tensile parts processing manufacturers propose to pay attention to the dimensions on the design drawings of the tensile parts. Due to the different stresses on the tensile parts, the thickness of the material after stretching changes. Generally speaking, the center of the bottom maintains the original thickness, the material at the bottom rounded corners becomes thinner, the material at the top near the flange becomes thicker, and the material at the rounded corners around the rectangular stretched piece becomes thicker. Standard method for product dimensions of precision stretched parts: When designing stretched products, the dimensions on the product drawing should clearly indicate that the external dimensions or internal dimensions must be guaranteed, and the internal and external dimensions cannot be marked at the same time. Marking method of drawing part dimensional tolerance: the inner radius of the concave-convex arc of the drawing part and the height dimensional tolerance of the once-formed cylindrical drawing part are the double-sided symmetrical deviation, and the deviation value is the national standard (GB) 16 accuracy standard Half of the difference, and prefixed with ±. Explain the types of precision drawing stamping parts processing 　 　 1. Cylinder precision drawing stamping parts processing: the drawing of flanged cylindrical products. The flange and the bottom are both flat, the side wall of the cylinder is axisymmetric, and the deformation is evenly distributed on the same circumference, and the blank on the flange produces deep drawing deformation.　　2. Processing of elliptical precision drawing stamping parts: The deformation of the blank on the flange is the drawing deformation, but the deformation amount and the deformation ratio change accordingly along the contour shape. The larger the curvature, the greater the plastic deformation of the blank; conversely, the smaller the curvature, the smaller the plastic deformation of the blank.　 3. Rectangular precision drawing stamping parts processing: low rectangular parts formed by one-time drawing. When stretching, the tensile resistance at the rounded corners of the flange deformation zone is greater than the tensile resistance at the straight edges, and the degree of deformation at the rounded corners is greater than that at the straight edges.　　4. Mountain-shaped drawing processing: When the side wall of the stamping part is inclined, the side wall is suspended during the stamping process and is not attached to the mold until the end of the forming. The deformation characteristics of different parts of the side wall during forming are not completely the same.　　5. Dome-shaped stretching processing: The deformation of the dome-shaped cover plate during the forming process is not a simple stretching deformation, but a composite forming in which both stretching and bulging deformation exist. The deformation of the blank on the pressing surface is tensile deformation, and the deformation of the blank inside the profile is bulging deformation.　　6. Flanged hemispherical drawing process: When the spherical part is drawn, the blank partly contacts the spherical top of the punch, and most of the rest are in a suspended and unconstrained free state. Therefore, the main process problem of this kind of spherical part stretching is the serious thinning of the local contact part, or the instability and wrinkling of the curved part.　 7. Flange stretch processing: shallow stretch the flange part of the stretched product. The stress and strain situation is similar to compression flanging. Because of the tangential compressive stress, it is easy to wrinkle, so the forming limit is mainly limited by the compression wrinkle.　 8. Edge stretch processing: Perform angular re-stretch processing on the flange of the previously stretched product. This processing requires the material to have good plasticity. 9. Deep precision drawing stamping processing: drawing processing products that exceed the drawing processing limit require more than two stretches to complete. The products that have been stretched in the depth direction of the front station are re-stretched in the depth direction. The wide flange stretch piece is stretched to the required flange diameter during the previous stretch, and the flange diameter remains unchanged when it is stretched later.