Bending mold is the main process equipment for sheet metal processing. With the development of engineering machinery, automobile, shipbuilding, aerospace, electrical instrumentation and building decoration industry, the forming precision and shape of sheet metal products by sheet metal processing enterprises at home and abroad The complexity requirements are getting higher and higher, and the surface quality requirements of sheet metal parts are getting higher and higher, especially for the bending processing of stainless steel plates and aluminum plates, and no scratches are required. In order to avoid the indentation on the surface of the workpiece during the bending machine, the bending surface, the hardness of the material, the structure of the die, and the accuracy of the selection of the machine tool and the precision of the die are analyzed in the test. The cause of the indentation.
The defects of traditional bending
Figure 1 shows the mould structure in the traditional bending mode. This structure usually has V-shaped grooves of different opening sizes for bending plates of different thicknesses. Under the action of bending force during bending, the plate moves along the edge of the V-shaped notch of the lower die and is subjected to the pressing and sliding friction of the bending force, so that the surface of the formed sheet metal part has obvious indentation and flaw defect. The width of the defect tape is about 0.414 times that of the V-shaped notch, which seriously affects the appearance quality of the product. In order to solve the above-mentioned defects occurring in the conventional bending, it is necessary to overcome the movement of the sheet during the bending process and the frictional force and the pressing force of the V-groove of the lower mold to form the sheet.
Figure 1
Non-indentation bending technology and die structure
Roller type non-indentation mold
The structure of the roller type non-indentation mold is shown in Fig. 2. When the metal sheet is bent, the workpiece is in contact with the cemented carbide core rod on the lower mold during the bending process, and the core rod follows the sheet. The moving direction of rotation causes the workpiece to change from conventional sliding friction to rolling friction after being in contact with the lower mold, which greatly reduces the indentation and scratches on the surface of the workpiece due to the extrusion, thereby effectively improving the appearance of the workpiece. Quality and precision. However, during the bending process, the lower mold roller and the plate still have a pressing force, and the bending and indentation cannot be completely avoided, especially when bending a soft material.
Figure 2
2.Rotating flap type non-indentation mold
The structure of the rotating flap type non-indentation mold is as shown in Fig. 3. During the process of pressing the workpiece into the lower mold body by the upper mold, since the workpiece is in contact with the plane of the rotating flap, the rotating flap rotates in the lower mold body, and the workpiece is entirely During the bending process, there is no relative sliding with the rotating flap. At the same time, the workpiece is in surface contact with the rotating flap, which eliminates the indentation and scratching of the workpiece surface due to the extrusion, which effectively improves the appearance quality and precision of the workpiece.
