Zhejiang Zhongxing Steel Pipe Machinery Co., Ltd. would like to introduce the relevant information of cold-rolled pipe mills:
The multi roll cold rolling mill, collectively known as LD type, can be divided into: ① single line rolling mill; ② Multi line rolling mill, capable of rolling two or four pipes simultaneously; ③ Double row rolling mill.
Composition of Multi roll Cold Rolling Pipe Mill
1. Multi roll cold rolling mill frame
The multi roll cold rolling mill frame is a cylindrical thick walled sleeve, with three or more rolling rolls evenly distributed inside the sleeve. The sleeve is uniformly stressed, has good rigidity, and small elastic deformation, which is very advantageous for rolling high-precision and precision pipes. The principle that must be followed in the arrangement of rolling rolls is that one of the rolling rolls must be located vertically below the rolling centerline.
The adjustment of the rolling mill is divided into radial adjustment and axial adjustment. For rolling mills with finished specifications below 60mm, a combination of collective adjustment and individual roll adjustment methods can be used, which means that both collective adjustment and radial adjustment can be performed on individual rolls. Currently, the wedge method is used. The axial position of the rolling mill is self positioning, which means that there is sufficient margin between the width of the rolling mill body and the groove of the slide during design, allowing the rolling mill to move left and right and automatically center. If the outer diameter size of the finished pipe is greater than 60mm (i.e. LD-60 or above rolling mill), there is no need to use collective adjustment method, only a single rolling mill adjustment can be used. Because the collective adjustment mechanism of large-scale rolling mills is relatively complex and will increase the weight of the entire frame significantly, it is extremely unfavorable for improving the speed of the rolling mill.
The method for determining the roll size of a multi roll cold rolling tube mill is based on the comprehensive determination of the rolling pressure, strength and stiffness of the rolls, and the size of the contact stress between the roll diameter and the slide working surface when rolling products of different materials and specifications.
  
2. Multi line rolling mill
In recent years, both LD-8 × 2 and LD-15 × 2 rolling mills have undergone significant improvements in their structures. It is no longer the case that two stands are mounted on one frame, but each stand is mounted on a separate frame. Each frame is driven by a rocker mechanism and is out of phase with each other. Their inertial forces are well balanced, resulting in faster speeds and significantly reduced failure rates. Especially in recent years, servo motor-driven and controlled rotary feed mechanisms have been adopted in cold rolling mills, further reducing the failure rate of the rolling mill and effectively improving its speed, thus significantly increasing the production of the rolling mill.
More information about cold rolling mills can be found on our company's official website: iguys.cn