Side Trimming Line

The Process of Shear Deformation

Shear deformation included the process of elastic deformation, crack propagation, plastic deformation and material fracture. In the period of elastic deformation, the upper and lower blade squeeze the steel plate to make the steel plate elastically flatten and bend slightly. The as the distance between the cutting edges continues to approach, the steel reaches the yield limit, plastic deformation occurs inside the metal and a bright cut section is obtained. Shearing continues and stress concentration occurs at the cutting edge and small cracks are induced. The upper and lower cracks expand and overlap, the steel plate is disconnected then the shearing process is completed. Normally, the shoulders and burrs are relatively small, and the cut-off layer and the tear-off layer occupy most of the shear section.

The Relationship of Blade Clearance And Cutting Edge Quality

• Firstly, the standard of cut to length line quality: the cross-section is about 1/5-1/3 of the thickness of the steel slitting line. The dividing line between the cutting surface and the tearing surface is continuous and straight, and the whole shearing is smooth and no notch and big burr.

• And secondly, the relationship of blade clearance and cutting edge quality: the lateral clearance of the cutting edge is the most important factor affecting the shearing quality of the steel slitting line. The practice shows that the size of the lateral clearance is more sensitive than the overlapping amount, therefore, it is the key to adjusting the clearance of the chopper to set a reasonable value of the side clearance. From the cutting section of strip, the cut-off layer ratio will be significantly reduced with the increase of the lateral clearance, while there is no basic change in shoulders and burrs. When the lateral clearance increased into a certain extent, it is not obvious that the trend of cutting layer reduction, but the shoulders and burrs increased. It will cause severe wear of the cutting blade, overload of the equipment, a large proportion of the cut surface and meat staining or secondary shearing on some sections due to the small adjustment of the backlash of the cutting blade. Contrary, the crack cannot be closed, the center part was forcibly broken, burrs and shoulders collapse seriously.

• Thirdly, the relationship of overlap amount and cutting edge quality: the overlap amount of the shear should be determined by the thickness of the strip and the situation of shearing. Generally, when the overlap is too large, the shearing force will be too large. And the edge wire will be bent and the buckle will be caused, if, in the converse condition, the steel plate will not be cut.