Adjustment of roll shape rolling roll

In order to improve the strip shape and reduce the lateral thickness difference, the actual convexity and actual deflection of the work must be controlled to meet the requirements of a certain lateral thickness difference. There are many conditions in the rolling process that will affect the actual crown and actual deflection of the work roll, such as:

1. The length of the rolling working time, the height of the rolling speed, the different types of rolled products, the difference in cooling conditions, etc. will cause changes in the temperature distribution of the rolls, resulting in changes in the thermal crown of the rolls, and thus the actual convexity of the rolls. Degree change

2. In the rolling process, the actual wear of the rolls continues to increase, which will also cause the actual crown to change

3. The influence of changes in rolling thickness, width, tension, etc. and uneven rolling mechanical properties will affect the changes in the size and distribution of the rolling force, thereby changing the actual degree of work rolls.

An original roll crown 0 selected in the roll shape design is fixed, which obviously cannot maintain a good shape. This requires continuous adjustment of the actual roll crown and actual deflection during the rolling process (that is, the roll Type adjustment). At present, the roll shape adjustment methods used in actual production are as follows:

1. According to a reasonable roll shape design, based on experience or calculation, calculate the original convexity of 0 for the given strip specifications, so that it can maintain the required strip shape and lateral thickness difference. In production, use different work original convexity to adapt to various specifications of strips;

2. Adjust the roll temperature distribution along the length of the roll body, that is, change the heat. By controlling the temperature distribution of the roll, such as cooling the roll in sections along the length of the roll, changing the flow and temperature of the coolant in each section, the thermal crown of the roll can be changed, thereby changing the actual crown of the roll and achieving the adjustment of the roll shape. the goal of. The advantage of this method is that the equipment and control methods used are very simple, but its adjustment speed is very slow, the inertia is large, it cannot meet the requirements of high-speed rolling, and it cannot always maintain the symmetry and stability of the roll thermal crown;

3. Change the reduction schedule, adjust the rolling force, and change the actual deflection of the roll. For example, by reducing the amount of reduction and reducing the deflection of the roll itself, the symmetrical edge waves generated by the steel can be alleviated or eliminated. The disadvantage of this method is that changing the reduction will affect the thickness of the strip exit

4. The hydraulic bending device is adopted to adjust the deflection of the roll and change the actual degree of the roll. When this method is adopted, the two ends of the work roll are subjected to an additional bending force, which can increase or decrease the deflection of the roll during the rolling process, so that the actual deflection of the roll is automatically or manually maintained at the optimal value. The outstanding advantages of hydraulic bending rolls are fast and accurate, can meet the requirements of high speed and high precision, realize automatic control of plate shape; can make one roll shape meet the production of multiple specifications, facilitate the grinding of rolls, and reduce the number of roll changes. , Improve the operation rate. However, the disadvantage of this method is that the force increases the consistency between the roll and the related parts of the rolling mill, and reduces the service life of the parts.