RED CD
Blanking is the use of molds to produce separate sheet stamping processes subjects, including blanking and punching. It can be made into parts, but also for the bending, drawing, forming and other processes to prepare rough. Washed down from the Board Division on the shape of the parts required (or rough) called off the branches.
The shape of the workpiece out of the hole required (red to go to waste) is called punching.
Figure I-1 of the washer, from falling branches and punching two processes to complete. Production practice, we die blanking process of a certain understanding of the structure, but perceptual knowledge to rational knowledge up to truly understand the nature of the blanking process, a better design of the development process and die. The following deformation on the blanking process, the quality of stamping parts, stamping die design and stamping die size blade structural design issues discussed. .
Section blanking deformation mechanism
Blanking process
Shown in Figure 1-2 blanking by the deformation process can be seen that the composition of the punch and the upper and lower concave edge chess, material on the concave mold, punch the material deformation gradually decreased until the completion of all the separate blanking. With the punch of the external forces acting on material changes in the number of the material on the external force changes in quantity, material deformation within the continuous development.
The deformation of the blanking process is divided into three stages (Figure 1-2).
1, elastic deformation stage
Punch contact with material force as the punch pressure, the material is elastic compression and bending, and squeeze into the die hole. Then the stress does not exceed the material yield limit, if the punch relief, material or restitution, so that elastic deformation stage.
2, plastic deformation
Punch to pressure, the stress reaches the yield limit of material, some metal is squeezed into the die hole, producing plastic shear deformation, are shining maggot cut surface. For convex, concave feel there is room between the depression, it is the plastic shear deformation is also accompanied by the bending and stretching.
3, fault isolation stage
Materials continue to increase external and internal stress increasing, convex, because the incision die stress concentration, shear strength over the first internal stress, micro-crack appears. Mold continuing under pressure, convex, concave mold cavities of the micro-crack edge to the material constantly within the share capital, then pulled off material separation. Such as convex, concave die gap was reasonable, the upper and lower crack coincide with each other. ' Stress and strain
Further analysis of blanking time of stress and strain state of deformation zone and help to the understanding of the blanking process. Die and punch in the edge of the joint line to take 'cell body, "whose stress-strain diagram shown in Figure 1-3. Can be seen from the figure, it seems
Metal fracture line AB that is cutting edge on-line) at 45 degrees. The main uranium direction I was pulling stress and tensile deformation, tensile stress the gold
Is a fiber elongation; its vertical axis 2 is the compression stress direction and compressive deformation, the fiber extrusion pressure; in the tangential direction of the stress and strain is very small, negligible; and principal stress direction at 45. Direction to the direction of maximum shear stress between the punch and die clearance, elongation and tear off the metal, resulting in broken fracture surface roughness, and with a burr.
The process can also blanking blanking force deformation curves of the figure is confirmed. Figure 2-9 (materials), is punching a 3 mm thick material punching power and punch of the curve. Can be seen from the diagram:
In the process of blanking blanking force size is constantly changing. AB section of the equivalent of punching the elastic deformation stage, BC Section for the plastic deformation stage. When the material internal stress to shear strength began to crack when the material, CD segment for the crack propagation until the material isolated rupture in order teams, DE Dan launch materials introduced die mouth piece.
Cut section of
See Figure 2-10
The deformation process of blanking the red plant parts are not smooth vertical section, the section has three areas, namely, with rounded corners, bright band and the fault zone.
