The concept of instantaneous clearance is put forward, and its influence on the quality of shearing fracture is stu died.

In the process of shearing plates, there are a lot of factors that will affect shearing quality, such as knife gap, pinch roll assembly precision and pinch roll synchronization, knife assembly precision, precision of equipment correlated with shears.

Based on the influence of the shearing technical parameters and the operational statement of equipments on shearing quality,the causes of "burr" and "missed cutting line" were analyzed,the main affecting factors are trimming knife gap and running-off of plate according to the actual production.

In view of defects of shearing quality of channel steel,such as bur,tear,shear drag and short life of cutter,some measures were put forward.

And comprehensive analysis is also made on critical factors that can influence slitting quality as well as on tension control mode.

This paper analyzes the form of blank area of sower and affect on cutting quality by theory.

Theoretical results and on-site shear quality both indicate that new structural features such as asymmetry and negative offset play an important role in ensuring pure rolling shear and keeping blade clearance constant,which provide an effective means to improve quality of steel plate.

In order to improve the cutting quality of copper tube, different cutting modes with toothless cutters are analyzed with the mechanism clarified.