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When using stamping equipment for metal stamping and stretching processing, there are 16 types including:
1. Cylindrical stretching processing: The flange (with flange) of cylindrical products is stretched. The flange and bottom are both flat in shape, with the cylindrical side walls being axisymmetric and deformation evenly distributed on the same circumference. The blank on the flange undergoes tensile deformation.
2. Elliptical stretching processing: The deformation of the blank on the flange is called deep drawing deformation, but the amount and ratio of deformation change correspondingly along the contour shape. The larger the curvature, the greater the plastic deformation of the blank; On the contrary, the smaller the curvature, the smaller the plastic deformation of the blank.
3. Low rectangular parts formed by one-time stretching of rectangular stretching processing. When stretching, the tensile resistance at the rounded corners of the flange deformation zone is greater than that at the straight edges, and the degree of deformation at the rounded corners is greater than that at the straight edges.
4. Mountain shaped stretching processing: When the side wall of the stamped part is inclined, the side wall is suspended during the stamping process and does not adhere to the mold. Install the mold only after the molding is completed. The deformation characteristics of different parts of the sidewall during forming are not the same.
5. Hill shaped stretching processing: The deformation of the hill shaped cover plate blank during the forming process is not simply stretching deformation, but a composite forming process where stretching and bulging deformation coexist. The deformation of the billet on the extrusion surface is tensile deformation (radial tensile stress and tangential compressive stress), while the deformation inside the contour (especially in the central area) is bulging deformation (radial and tangential tensile stress).
6. Flange hemispherical stretching processing: When stretching the spherical part, the blank part partially contacts the spherical top of the convex mold, while the rest is in a free state of suspension without constraints. Therefore, the main process problem of this spherical part stretching is severe thinning of the local contact part, or instability and wrinkling of the bent part.
7. Flange stretching processing: The flange part of the stretched product is subjected to shallow stretching processing. The stress and strain situation is similar to compression flanging. Due to tangential compressive stress, it is prone to wrinkling, so the forming limit is mainly limited by compressive wrinkling.
8. Edge stretching processing: Performing angle re stretching processing on the flange of the previous stretched product, which requires the material to have good plasticity.
9. Deep stretching processing: Stretch processed products that exceed the stretching processing limit require two or more stretches to complete. The products processed by stretching in the depth direction at the front workstation are re stretched in the depth direction. The wide flange stretching part is stretched to the required flange diameter during the first stretching, and the flange diameter remains unchanged during subsequent stretching.
10. Cone stretching processing: For deep conical parts with h/d>0.8 and α=10 °~30 °, due to the large depth, the deformation of the blank is significant. The forming force transmitted only by local areas in contact with the punch can easily cause local thinning or even fracture of the blank, requiring multiple transitions to gradually form. The stepped stretching method is to first stretch the billet into a stepped transition piece, whose stepped outer shape is tangent to the inner shape of the conical part, and finally expand into a conical shape. The stretching frequency and process of the stepped transition piece are the same as those of the stepped cylindrical piece.
11. Rectangular re stretching processing: The deformation of the high rectangular part formed by multiple stretching is not only different from the stretching of the deep cylindrical part, but also significantly different from the deformation of the low box shaped part. How does the shape and size of the parts change with the variation of the stretching height during multiple stretching processes of the multi station automatic conveying press when processing high rectangular boxes.
12. Surface forming processing: Surface stretching forming is a stamping method that reduces the outer flange of a metal flat blank and elongates the inner flange, resulting in a hollow product with a non straight wall and non flat bottom surface.
13. Step stretching processing: Re stretch the product that was originally stretched on the left side to form a stepped bottom on the right side. The deeper part deforms during the initial stretching stage, while the shallower part deforms during the later stretching stage. It is easy to induce shear stress and deformation on the side walls of the step section.
14. Reverse stretching processing: Reverse stretching is the process of re stretching a workpiece that has already been stretched in the previous process. The reverse stretching method can increase radial tensile stress and achieve better results in preventing wrinkles. You can also increase the stretching coefficient for further stretching.
15. Thinning and stretching processing: Unlike ordinary stretching, thinning and stretching mainly involves changing the thickness of the stretching tube wall during the stretching process. The gap between the convex and concave molds is smaller than the thickness of the blank. When the straight wall of the blank passes through the gap, it bears a large uniform compressive stress. During the stretching process, the wall thickness becomes thinner while eliminating the deviation of the container wall thickness, increasing the smoothness of the container surface and improving accuracy and strength.
16. Panel stretching processing: Panel products are sheet metal stamping parts with complex surface shapes. During the deep drawing process, the deformation of the blank is complex, and its formability is no longer a simple stretch forming, but a composite forming that involves both deep drawing and bulging.
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