Metal stretching processing technology

As one of the main stamping processes, drawing of metal stamping parts is widely used. Various thin-walled parts with cylindrical, rectangular, stepped, spherical, conical, parabolic and other irregular shapes can be made by drawing process.
1. Hemispherical drawing with flange: when the spherical part is drawn, the blank is in local contact with the spherical top of the punch, and most of the rest are in the free state of suspension and unconstrained. Therefore, the main technical problem of this kind of spherical parts is the serious thinning of local contact part or the instability and wrinkling of curved surface part.
2. Flange stretching processing: the flange part of the stretching product is processed by shallow stretching. The stress and strain of the flange is similar to that of the compression flanging. Because of the tangential compressive stress, it is easy to wrinkle, so the forming limit is mainly limited by the compression wrinkling.
3. Edge stretching processing: the flange of the products drawn in the previous process is re stretched in angular shape, which requires good plasticity of the material.
4. Deep drawing processing: products exceeding the limit of drawing processing need to be stretched for more than two times. The products that have been drawn in the depth direction of the front station are re stretched in the depth direction.
5. Conical drawing processing: for the deep conical parts with H / d > 0.8 and α = 10 ° to 30 °, due to the large depth, the deformation degree of the blank is large. The forming force is transferred only by the local area of the blank and the punch, which easily causes the local excessive thinning and even fracture of the blank, and needs to be formed gradually through multiple transitions.