1-- lower cutting edge; 2 -- materials; 3 - shear blade
When shearing the copper strip, the material stress starts from elastic and plastic deformation. When the upper cutting edge drops to contact the material, the material will be subjected to the pressure of the upper and lower cutting edges and produce elastic deformation. Due to the presence of torque M, the material will be bent, that is, it will rise up from the contact surface of the cutting edge. As the cutting edge is pressed down, the cutting edge is pressed into the material, and when the internal stress state meets the plastic deformation condition, the plastic deformation occurs, and the deformation is concentrated in the area near the cutting edge. Plastic deformation starts from the edge, and with the deepening of the cutting edge, the deformation zone develops and expands towards the depth of the material, until plastic deformation occurs in the whole thickness direction of the material, and one part of the material slips relative to another part. Torque M presses the material to the side surface of the cutting edge. Therefore, when the cutting edge moves relative to the material, these forces flatten the surface and form a bright belt on the surface of the incision. When the material near the cutting edge reaches the limit strain and stress value, microcracks will be generated. After the crack is generated, it will develop along the direction of *** large shear strain velocity, and the cracks will meet under ***, and the material will be completely separated. Thus, when a crack is formed, burrs are left in the shear section.
The main methods to reduce burr are as follows:
1. Adjust the cutting process reasonably according to the incoming copper strip, such as the overlap degree of cutting edges and the gap between cutting edges;
2. Ensure the quality and accuracy of the cutting edge meet the requirements;
3, to ensure the shear machine accuracy meet the requirements.
And want to remove burr thoroughly, must undertake to copper strip edge processing, the method has rolling method, scraping method, relatively speaking, scraping method is more advanced, can be the edge of copper strip processing into a rounded corner or circular arc.