1.1 The minimum bendingradius of the bending piece： When the material is bent, its outer corners was upturned and the inner layer was compressed. , The tensile and compressing of the material waill more severe when the inner "R" is tmore smaller base on the material thickness is constant . When the tensile stress of the outer fillet exceeds the ultimate strength of the material, cracks and breaks are generated. Therefore, the structure of the bending part Design, should avoid too small curved fillet radius. 1.2 Straight edge height of bending parts： 1.2.1 Minimum straight edge height requirement in general.Bending the straight side of the height should not be too small, the minimum height required: h> 2t. 1.2.2 Special requirements for straight edge height If the design needs to bend the straight side of the height h ≤ 2t, then first increase the height of the bend, bending and then processed to the required size; or in the bending deformation area after processing shallow groove, and then bending. 1.2.3 Flange edge with beveled sides of the flanged edge The minimum height of the side when the corner is bent with a beveled side: h = (2 ~ 4) t> 3mm 1.3 The distance between hole and adges of bending parts ： Hole margin: the first punch after the bend, the hole should be located in the bending deformation area, to avoid bending holes will be deformed. The distance from the hole to the bend is shown in the table below. 1.4 Sectional bending of the process of incision ： 1.4.1 The bending line of the bending part shall avoid the position of the sudden change in size 1.4.2 When the hole is located in the bend deformation zone, take the form of the cut An example of a cutout form when the hole is in the bend zone 1.5 with a hypotenuse of the bend side should avoid the deformation area 1.6 dead side of the design requirements The length of the dead edge of the dead is related to the thickness of the material. As shown below, the general dead edge minimum length L ≥ 3.5t + R. Where t is the wall thickness of the material and R is the minimum inner bending radius of the process. 1.7 Designed to add the process positioning hole In order to ensure the rough positioning of the blank in the mold, to prevent the bending of the pump 1.8 Note bending the relevant size of the pieces, to consider the process A) Punching after punching, L dimensional accuracy is easy to ensure that the processing is convenient. B) and c) If the size L accuracy requirements are high, you need to bend the hole after processing, processing trouble. 1.9 rebound of curved parts There are many factors that affect the springback, including: mechanical properties of materials, wall thickness, bending radius and positive pressure when bending. 1.9.1 The larger the ratio of the radius of the fillet to the plate thickness, the greater the rebound. 1.9.2 Examples of ways to suppress spring back from design Bending parts of the rebound, mainly by the manufacturer in the mold design, take certain measures to avoid. At the same time, from the design to improve the structure to promote the rebound angle as shown below: in the bending area to suppress the ribs, not only can improve the stiffness of the workpiece, but also help to suppress the rebound.