2. 1 When bending, there are many main factors that affect the springback in bending operation, including the following aspects: (1) When bending parts with high mechanical properties, in order to reduce the springback value, metal plates with uniform mechanical properties should be selected. ⑵. Material surface quality The accuracy, surface quality and flatness of the thickness of the plate have great influence on the springback. If the tolerance range of sheet thickness is large, the fluctuation of rebound angle will be large; The thinner the sheet metal thickness, the greater the influence in this respect. In addition, if the surface of the material is uneven, convex and contains impurities, stress concentration will occur when bending, which has a great influence on springback. (3). Relative bending radius r/t r- refers to the bending radius. T-refers to the material thickness. The greater the r/t, the greater the rebound value. Therefore, in order to reduce the impact of springback, generally choose a smaller relative bending radius. However, too small a bending radius will lead to bending fracture. This problem must be considered in a balanced way. (4) The larger the bending angle, the larger the deformation zone, but the bending angle has nothing to do with the weakening value of the bending radius. 5. The shape of the bending part and the size of the working part of the die have great influence on the springback value. For example, during bending, the springback of U-shaped parts is smaller than that of V-shaped parts. This is because the bottom of the U-shaped part has tensile deformation during bending, so the rebound is small. [6]. The influence of bending force Generally speaking, when the bending force is small, the rebound angle is large. In fact, the correction of bending belt can basically reduce or approach zero the rebound angle by increasing the acting force.
2.2 Measures to reduce bending rebound
(1) Improve the local structure of the bending part and select appropriate materials.
For example, the stiffener is pressed at the deformed part of the bending part to improve the rigidity of the part and reduce the rebound; For another example, when selecting plates, materials with large elastic modulus and low yield limit can be used for bending, which can reduce springback; For some hard materials, annealing before bending can also reduce springback.
(2) Compensation method
According to the springback trend and springback amount of the bending part, the shape and size of the working part of the punch or die are corrected to compensate the springback amount of the workpiece. Generally speaking, compensation method is the simplest method to eliminate the springback of bending parts, which is widely used in practical production.
3. Please refer to the stamping design manual for simple calculation.