Industry news

　　Through the analysis of the shear plane section of the plate shear, we can draw the following conclusions: when the bar is sheared, the stress intensity factor of the material attached to the blade is greater than the critical stress intensity factor of the material.

　　The resulting crack expands further until the final crack is evacuated. In the analysis of high shear plate, the critical stress intensity factor can not be used to grasp the strategic key points of low-speed stress intensity factor.

　　Because the critical stress intensity factor, i.e. fracture toughness, changes with speed, the fracture toughness of the material at high speed is significantly lower than that at low speed, but it is not affected by the speed at low speed. When it is higher than a certain speed, the fracture toughness increases sharply with the increase of speed, that is, there is the lowest fracture toughness and corresponding speed at the lowest fracture toughness.

　　At this speed, the fracture toughness of the material is the lowest, the fracture of the material is completely brittle fracture, and the section quality is the best. Microscopically, the number of dislocations caused by lattice slip in the material increases and the density becomes more symmetrical under high-speed load. The generated dislocations slide under load. When the sliding dislocations encounter the grain boundary barrier, there are signs of dislocation aggregation, resulting in stress convergence.

　　When the stress convergence of the shear reaches a critical value, transgranular fracture will occur at the grain boundary. The slip velocity of dislocations increases with the increase of loading velocity, and the formed dislocations are eliminated by the diffusion of other deviations in a short time. Therefore, the plastic zone at the crack tip becomes smaller, the material tends to brittle fracture, and the section quality is better.

　　Safety operation regulations for plate shears

　　1. The plate shearing machine shall be used and maintained by a specially assigned person, and the operator must be familiar with the structure and performance of the machine tool.

　　2. It is forbidden to use the plate shears under overload. Quenching, hard steel, high speed steel, alloy steel, castings and non-metallic hard materials shall not be cut.

　　3. The blade of the plate shear shall be sharp, blunt or damaged, and shall be repaired or smoother in time.

　　4. In case of multi person operation, special personnel shall be assigned for command, coordination and cooperation.

　　5. It is forbidden to cut two different specifications of materials on the plate shear at the same time, and it is also forbidden to cut multiple layers.

　　6. It is forbidden to stay between the metal plate and the workbench when the plate shears are feeding. When cutting short material, press it with an iron plate, and the finger shall be at least 200mm away from the knife edge.

　　7. After alignment with a crowbar, pull out the crowbar immediately before cutting. If the iron plate moves, it should be plugged with a wooden pillow to avoid injury after the foot comes down.

　　8. The cut hard core must be placed stably and not stacked too high. Leftover materials and wastes at corners shall be cleaned in time to keep the site clean and tidy.