Analysis of the bending process in the processing of metal stamping parts!

Process analysis of bending processing in the processing of metal stamping parts! Metal stamping processing, also known as sheet metal punching or cold stamping, is one of the most advanced methods in pressure processing. Stamping processing generally uses sheet metal as raw materials (metal pipe materials and non-metallic materials are also used); the punching die installed on the press is used for reciprocating motion, and pressure is applied with the sheet metal at room temperature to cause separation or deformation. So as to obtain parts of certain shape, size and performance. There are also many types of metal parts stamping processing, such as: punching, bending, stretching and other processing methods. So today we will talk about the analysis of the bending process. First, analysis of the bending process Bending is a stamping process that uses materials to produce plastic deformation and form a certain angle shape. Bending can be done on a Euroton press with a mold, or can be done on a dedicated bending machine or bending equipment. According to different processing materials, bending can be divided into sheet metal bending, tube bending, profile bending, bar bending, etc.; according to the different equipment used for bending forming, it can be divided into bending, rolling, stretching, roll bending, etc. . The accuracy of bending parts processing is related to many factors, such as the mechanical properties and thickness of the material of the bending parts, the mold structure and the accuracy of the mold, the number of processes and the sequence of the processes, and the shape and size of the bending parts themselves. Bending parts with high precision requirements must strictly control the material thickness tolerance. Generally, the economic tolerance level of bending parts is best to be below IT13 level, and it can reach IT11 level by adding shaping and other processes. (1) Bending process The process of bending is to use the V-shaped bending mold to press and bend the mold structure diagram of the V-shaped part. The convex mold 1 and the concave mold 2 are basically consistent with the inner and outer contours of the bending workpiece. When the external force (if the slider of the force machine moves) pushes the convex mold down, the sheet material placed between the convex and concave molds is bent into Required artifacts. Bending can be divided into free bending and correcting bending. The difference is that free bending means that when the punch, sheet metal, and concave die are completely attached, the pressure is no longer pressed down; while correcting bending is to apply on the basis of free bending. Pressing down makes the workpiece produce one-step plastic deformation to reduce the springback of the bent part. Second, analysis of bending deformation The characteristics of bending deformation can be obtained by setting a square grid on the side of the sheet before bending and observing the changes of the grid before and after bending. After observing the bending, it can be found through the coordinate grid: (1) The square coordinate grid of the rounded part changes from a square to a fan shape, and the other parts are not deformed or deformed very little. (2) In the deformation zone, the side grid changes from a square to a fan shape; the outer side of the die is stretched tangentially by hand, and the length is elongated; the inner side near the punch is compressed in the tangential direction, and the length is shortened. From the inner and outer surfaces to the center of the sheet, the degree of shortening and elongation gradually decreases. The layer of metal whose length does not change before and after deformation between shortening and elongation becomes the neutral layer. There is a type of change in the section of the bending deformation zone during stamping, and we need to observe the change of the section after bending. We can find that: (1) The cross section of the sheet material in the deformation zone is deformed. After the inner layer of the curved narrow plate is tangentially compressed, it flows in the width direction to increase the width; after the outer layer is tangentially stretched, the material deficiency is supplemented by the width and thickness directions, resulting in a narrower width (the entire The section is a sector with a wide inside and a narrow outside). For a wide board with a larger width, due to the large amount of material in the width direction, the resistance is large, and the material is difficult to flow in the width direction, and the cross-sectional shape remains basically unchanged, still rectangular. (2) The thickness is reduced. When the sheet is bent, the inner layer is shortened by the tangential compression surface, and the thickness should be increased. However, because the punch presses the sheet tightly, the thickness increase resistance is great, and the outer layer is stretched by tangential stretching, and the thickness direction becomes thinner. Bound. The increase in thickness is less than the decrease in the entire thickness, so that the phenomenon of thickness reduction occurs. The general bending parts belong to the wide plate bending, so the width direction of the plate is basically unchanged before and after bending. If the bending radius of the bending piece is r and the thickness of the bending sheet is t, the bending piece with a smaller bending radius r/t will become thinner due to the obvious thinning of the sheet thickness in the deformation zone during bending. According to the principle of constant volume, It will inevitably increase the length of the sheet.