Research And Improving On Regulating System Of Skin-pass-mill In CGL

Recently, the needing of zinc coating coil is increasing, more and more hot dip continuous galvanizing lines have been built. For improving the quality of the production, many factories spent a lot of money to bring in skin-pass-mill from other countries.Skin-pass-mill is a very important equipment. It can make the steel strip surface smooth as well as better machining performance. Its control system is very complex, including electrical drive control, hydraulic gap control, elongation control, bending-roll control, etc. Besides, skin-pass-mill is laid on the middle of the CGL, it plays an important role on tension control and speed control of the line.This thesis is mainly talking about the skin-pass-mill of Beijing Shougang Flourish Technology Ltd. Through researching the PLC program and documents of the skin-pass-mill detailedly, we have learned the ropes of skin-pass-mill's control system. On the basis of that, we solved some problems which disturbed the line normal running seriously. By using fuzzy PID control instead of traditional PID, the response of skin-pass-mill's control system became more quickly and more precisely, the problem of thin steel strip has been solved, also calibration sequence can be executed normally. By compensating for friction torque, back-rolls can reach the line speed quite quickly. The line's working order is much better than before.