Brief Introduction of Dynamic Changing Specifications of Packaging Steel Strip Cold Rolling

Brief Introduction of Dynamic Changing Specifications of Packaging Steel Strip Cold Rolling
　　Dynamic specification change is an indispensable function for full continuous cold rolling or pickling-rolling mill online unit. When different hot rolled coils (which can be different steel types, different thicknesses or different widths) are welded, they are continuously entered into the cold rolling unit. (At this time, the speed drops to about 300m/min) when it is rolled into cold rolled coils of different thicknesses. For the process computer setting model, it is not difficult to set and calculate the front and rear coils separately. The difficult thing is how to execute them, and adjust the roll gap and speed one by one according to what timing, so that a not too long wedge is passed. After the transition section, the required thickness and tension of the back material are reached and a smooth transition is ensured, without large tension fluctuations (not to mention breakage).
　　In order to make the transition smooth, the change of the setting value of the front and rear materials is implemented in stages. Slowing down the transition process is beneficial to the control of tension, but the wedge-shaped transition section should not be too long. Once the wedge-shaped transition section is greater than the distance between the frames, the transition section Being in two racks at the same time will make the problem more complicated. Therefore, in addition to changing the set value in stages, the key is to strengthen the comprehensive control of thickness, speed, and tension to speed up the transition (to reduce the length of unqualified strips) . Dynamic change of specifications requires precise tracking of the welding seam, and after the wedge-shaped transition section of the first frame is formed, the following racks are required to maintain the wedge-shaped transition section according to the elongation. The key is to control the starting point of the wedge-shaped transition section (with the welding seam). Distance) and end position.
　　When the wedge-shaped transition section passes through a certain frame, the speed of the frame and its front and rear frames should be adjusted to make the tension transition to the set value required by the back material, and to maintain the front tension as required by the front material This is the key control requirement, and the tension does not fluctuate too much during the adjustment process. Therefore, dynamic specification change requires L2 and L1 to cooperate and switch to closed-loop feedback control functions such as AGC and ATC (tension control) in time.