After the strip is out of the furnace, the temperature drops and the yield strength increases. But after annealing, the yield strength of the strip is much lower than that of the hard rolling state. In addition, the continuous stop and start-up in the exit section lead to great tension fluctuation, so there are many cold wrinkles in the exit section of the production sheet. Cold wrinkling generally occurs in the following three situations: first, when the speed is increased in the looper; second, when the strip steel is twisted when the straightening roller is working; third, in the area where the tension is relatively high on the coiler. Looper raising speed is the most prone to cold crease. One thing that many people don't know is that in the process of roller running from low speed to high speed, although it is rotating, there is an acceleration process like linear motion, including shaft acceleration and acceleration torque. For the active roller, the torque comes from the motor, while the acceleration torque of the passive roller comes from the tension or tension of the strip steel on the roller. That is to say, when the speed is increased after the exit stops, the roller in the exit looper has a process from static or low-speed running state to high-speed running state, which is driven by the exit tension roller through the strip steel. The torque of many rollers in the looper comes from the tension between the exit tension roller and the looper. It can be seen that the number is large, so It is easy to make the cold wrinkling of the strip steel with high tension. In order to prevent the slip line phenomenon caused by the single side tension of the strip steel after plating due to the single roll deviation correction, the double roll deviation correction is used at the exit, but it will cause the strip steel not in the same plane and produce the distortion, and also make the tension flow in the strip steel disturbed, resulting in the occurrence of cold crease. In order to prevent the collapse of the galvanized sheet, a lot of tension is used, but the effect is that the strip may wrinkle, which is easy to understand. In order to prevent cold wrinkling, the first thing is to slow the lifting speed of the exit coiling. There are some contradictions with production, because the production line speed is very fast when producing thin plates, and the time allowed to stop, cut, unload and take up is relatively short, so the operators are eager to speed up. In order to prevent waste products, it is necessary for the main operation of the process section to properly reduce the speed of the production line and cooperate with the operation. Moreover, if the coiling has started, the time saved by fast and slow speed up will not be too much. Secondly, it is necessary to take care of the rectifying roll to prevent the serious distortion of strip steel and wrinkle. The rectifying range of the rectifying roll can be reduced, and even the rectifying roll can be aligned or fixed at a proper position according to the shape of the plate, and the automatic operation can be resumed after it is stable. Thin plates are generally narrow plates, slightly off the roll impact is not too big. In addition, as long as the take-up tension is reduced, the wrinkle of the coiler can be prevented by applying less oil or using steel sleeve and paper sleeve.