Cold stamping and bending process of stainless steel pipe flanging pipe

There are two main cold stamping, drawing and bending methods for flanging stainless steel pipes, one is the spinning method, and the other is the combination of drawing and spinning. When purely using cold press forming, it is difficult to bend the top shape through a mold. Although it is possible to use spinning forming, the efficiency is relatively low and it is not suitable. A forming method that combines spinning and drawing can be used. It is first drawn into a parabolic shape, and then the top is folded and formed by spinning. This is a more suitable solution, so the third solution is the most suitable.

The processing technology of stainless steel elbow pipes is drawing forming, trimming, spinning and flanging, punching and flanging, and tapping in sequence, so that the parts can be completed. If pre-made holes are punched, the height of the flanging vertical edge will be neater. However, the punch diameter of the punched clamp joint is small, which is troublesome for punching and flanging.

In addition, in the process of producing stainless steel flanged chuck tubes, the outer edge of the blank is generally a non-deformation zone because it is constrained by the blank holder force or because the ratio between the outer edge width and the diameter of the flange hole is large, and the vertical wall part has been deformed. The force transmission area and the bottom of the hole are the deformation area. The deformation zone is in a state of bidirectional tensile stress, and the deformation zone will become thinner under the action of tensile stress, which is the same as the expansion thermal spray shape. It can be said that it is basically difficult to solve the problem of small punch punching, especially the flanging positioning problem. If prefabricated holes are not punched, the flanging height can be ensured and the positioning is easy, and the operation is very convenient; however, the vertical edges of the stainless steel pipe flanging pipes may have inconsistent heights, and sometimes cracks may occur.

The round hole stainless steel flanged pipe belongs to the elongation type flanging. When the stainless steel pipe is flanged, the deformation area of the blank is acted upon by tensile stress in the tangential direction, forming a tangential tensile strain stress that reaches the maximum value at the edge of the hole and is a unidirectional stress state. , according to the yield rule, it can be determined that the edge of the hole is the first part to undergo plastic deformation, and the thickness thinning is the most serious, so it is also the most likely to form cracks. When stainless steel flanged pipes are used, the deformation zone is subject to radial tensile stress, and the resulting radial strain value is relatively small.

For inner hole flanging of non-round holes, the stress and strain distribution in the deformation zone along the flanging line is uneven. When the flange height is the same, the tangential tensile stress and tangential elongation deformation will be larger in parts with a smaller radius of curvature; while in parts with a larger curvature radius, the tangential tensile stress and tangential elongation deformation will be larger. Small. The straight line part is similar to the bending deformation. Because of the continuity of the material, the deformation of the curved part will extend to the straight part, so that the tangential elongation deformation of the curved part of the motor is alleviated to a certain extent.