section{Introduction}
Tension is one of the most important factors in the hot rolling production of steel line materials. It has great influence on the size accuracy and surface quality of hot-rolled parts. At present, the development of tension control technology on hot-rolling line is the inevitable trend of current advanced hot-rolling technology. In this paper, the influences of tension on product accuracy and the main control methods are analyzed.
section{Influence of Tension on Product Accuracy}
The tension control technology in the hot roller product is mainly used to maintain the stability and precision of the product during the rolling process. In the hot rolling process, the rolling force and deformation are the basic basis of the product size and shape. In the process of rolling, due to the influence of the machine, temperature, speed and other factors, the change of tension value will produce force rocking on the steel strip. This will cause the combination of force, temperature and geometry errors to produce inaccuracy in the steel strip shape, size deviation and surface quality, etc.
Therefore, improper tension control will affect the product accuracy and surface quality. For example, if the tension is too large, it will cause the product surface to be wrinkled, rough, and impurity layer to appear, which will seriously affecting the product accuracy. On the other hand, the insufficient tension will cause the product internal and surface cracks and other defects, and even scrap the product. In general, the tension which is too large, too small or unstable will greatly reduce the product accuracy and machining quality.
section{Main Control Methods of Tension}
In order to maintain the accuracy of hot-rolled products, it is necessary to control the tension of the steel strip at a reasonable level during the rolling process. The main methods are:
subsection{Friction Control}
Friction control is the most commonly used tension control technology in hot-rolling line. It mainly uses the mechanical friction generated between the steel strip and the presser roller to adjust the tension and maintain the stability of the strip. In addition, the friction control can also prevent the steel from sliding and shaking, better maintaining the stability and precision of the product shape and size.
subsection{Loading Adjustment}
Statistically, the tension of the steel strip mainly depends on the load of the presser roller and the slip ratio of the steel strip on the roller surface. Through controlling the surface pressure of the roller, the tension of the steel strip in the hot rolling line can be adjusted to guarantee the precision of the product.
subsection{Magnetic Control}
Magnetic control technology is a method of using magnetic force to control the tension of the steel strip in the hot-rolling process. It mainly relies on the use of the power of magnetic force to change the position and trajectory of the steel strip and to adjust the tension of the steel strip during the rolling process. This method can quickly and accurately adjust the tension, reduces the errors caused by the tension change, and keeps high accuracy for the length and size of the steel strip.
section{Conclusion}
In summary, the tension control technology of the hot rolling line is mainly used to adjust the tension of the steel strip in the hot rolling process. Improper tension control will directly affect the size precision and surface quality of the product. In order to obtain satisfactory product accuracy, professional tension control technology such as friction control, loading adjustment and magnetic control should be adopted.
