Design And Research Of Regulating System For Tool Clearance Of Ultra-large Shears

During the process of shearing, the tool clearance of shears affects the quality of sheet. If the clearance is appropriate, the sheet metal gets good quality, the sheet force is reduced, and also the life of tool and shears are extended. Otherwise, if the clearance is too small, the tool is weared quickly,. If the clearance is too big, the plate will be tore. Now,most of shears only use potentiometer to control the rotation and stop motor to determine the clearance in China. This method not only has low precision of clearance, the stability and accuracy of control is relatively poor. Especially for the ultra-large shears, the longer cutting tools make the bigger error of clearance. To solve the problem, the paper is used to research the regulating system for tool clearance of ultra-large shears. The shear is increased a clearance detective device on the basis of the ultra-large shears, to ensure the precision of the clearance adjustment and to improve the efficiency.To solve the problem of the large inertia for the adjusting mechanism of ultra-large shears, top slide, adjusting motor and eccentric shaft of the key adjustment mechanism were analyzed, found the effect ultra-lager shears’ large inertia for adjusting result. According to the characteristics and requirements for the adjusting clearance of the shears, the paper was proposed the non-contact detection of tool clearance and the method of automatic adjustment. To achieve the direct detection of the tool clearance, researched the method of non-contact detection on the basis of the technology of non-contact eddy current sensor. To establish a mathematical model to analyze the parameters of PID, researched the method of the feedback control of ultra-large shears for tool clearance on the basis of technology of PID control and servo drive. The paper designed a regulating system for combination of open and close loopcontrol on the basis of Siemens S7-300 PLC, including the main control configuration of S7-300, the program of PID control and motor control.According to the debugging and simulation analysis of regulating system for tool clearance of ultra-large shears, it showed that the detection error of eddy current sensor was less than 0.05 mm, the adjustive range of the tool clearance was from 0.05 mm to 3mm, the regulative error of clearance was less than 0.05 mm, and the time of each adjustment was in ten seconds. These proved that the system could effectively complete the adjustment of tool clearance and achieve the adjustment function.