Separated from the sheet metal parts or blanks out the desired shape and size of the punching method. Blanking is the use of cutting edge of stamping die for the contours of the sheet along a shear deformation and separation. Blanking in stamping production accounted for the largest proportion. During the process of blanking, except near the cutting contour lines outside the metal sheet plastic deformation in itself will not produce, so by plate blanking the part still is a flat shape.
Blanking can be classified as shearing, blanking, piercing, cutting and cutting and cutting and so on. ① cut was large plates into the Strip. Secondly, blanking is along a closed separation line on the required parts from the sheets separated. ③ cutting edge is cut out drawing Flash. Was rushed out on a sheet of black punch hole, Groove and shutters, etc.
Blanking in addition outside as preparation, used for direct processing of the gasket, bike sprocket, instrument gears, cams, fork, instrument panel, as well as on the motor, electrical connectors in silicon steel, integrated circuits and so on.
The top die cutting edge of blanking die staggered called clearance. Clearance on shear deformation and failure process, blanking the affect quality, die life. Of blanking clearance on performance, sheet metal thickness of plate, punch and die structure and other factors, generally unilateral clearance sheets thickness loss.
Blanking of upper surface obtained after the blanking by the fallen angle, the shear plane, and Burr of the fracture surface consists of 4 parts (Figure 1). Plastic deformation of shear surface is formed, smooth surface and perpendicular to the plane of the sheet. Fracture surface is breaking the formation of rough surfaces, not perpendicular to the plane of the sheet, show some inclination. General blanking of dimensional accuracy is less than level 5, surface roughness is about α 50~10 r.
Precision blanking methods can improve the quality of blanking the upper surface, all smooth and vertical shear. Fine Blanking die cutting edge near a pair of scissors is the essence of material in a Triaxial compressive stress state in the deformation zone, suppress the occurrence of rupture, isolation is implemented to deformation of the material. To increase pressure in the blanking of peripheral ring, as seen in Figure 2, a v-shaped blank film, die gap decrease or negative clearance (punch than die).
When the volume is low, or blanking small thickness of sheet metal workpiece, latex or polyurethane instead of blanking die of a cutting edge, with another cutting edge completes the job. This method is known as blanking or polyurethane rubber blanking.