It is used for cutting thick strip or billet. In order to ensure the smoothness of the shear section of the rolled parts after cutting, the flying shear with the blade is usually adopted. The crank rotary lever flying shear is one of these flying shear machines. Because the blade of this kind of flying shear machine is perpendicular to the rolling piece when cutting and rolling, the shear section is smooth. When cutting strip, the inclined blade can be used to reduce shear force. The disadvantage of this flying shear is that the structure is complex, the dynamic characteristics of the shear mechanism are not good, and the movement speed of the rolled parts should not be too fast. A crank-link flying shears used in a small section steel plant with a speed of less than 5m/s and a thickness of 30-70 shearing pieces.