The plate shears use the moving upper blade and the fixed lower blade to apply shear force to metal plates of various thicknesses with reasonable blade clearance, so that the plates can be broken and separated according to the required size. Working principle and structure of plate shears. Plate shears are often used to cut blank plates with straight edges. The cutting process shall be able to ensure the straightness and parallelism of the cutting surface of the sheet to be cut, and minimize the distortion of the sheet to obtain high-quality workpieces. Plate shears belong to a kind of forging machinery, whose main function is in the metal processing industry. The blade of the plate shears is an important working part of the plate shears. In the cross cutting system, the cutting action takes two straight cutting edges, of which the movable upper blade is inclined to cut, with a front angle of a> 0, relative to the fixed lower blade. The plate is clamped by a lower bracket on the lower knife. When the inclined upper knife is downward, the small gap between the upper knife and the knife (1%-25% of the plate thickness), the plate is cut gradually from one end to the other. This can be regarded as a static process at the beginning of the neglect and at the end of the cutting. The transverse shear deformation is accompanied by bending deformation, because the plate must conform to the inclination of the blade. The two deformations interact with each other, resulting in shape defects, which are related to the inclination and the reduction of the width of the shear strip. The purpose of a cross cutting process is to reduce the edge quality (Burr) and flatness with a certain force. Therefore, in practice, the change of inclination angle between 0.5 ° and 3 ° is used as the adjustment between the quality of the plate and the required force.