The rolling methods of seamless steel pipes on cold rolling mills can be divided into oblique rolling, longitudinal rolling, and transverse rolling. Perforation is often done using oblique rolling, while pipe rolling is done using oblique rolling and longitudinal rolling. For diameter reduction, longitudinal rolling is mostly used, while transverse rolling is more commonly used in special occasions such as rotary presses. For longitudinal rolling, we divide it into two categories based on whether the roll pass changes during rolling: one is the type where the pass changes during rolling, such as the cold and hot Pilger rolling mill with periodic rolling; The other type is the fixed hole pattern that does not change, mainly used for continuous rolling of steel pipes, which is most commonly used in steel pipe hot rolling.
We mainly study the continuous longitudinal rolling of fixed hole patterns. For the continuous longitudinal rolling of fixed hole patterns, it is generally divided into two types: two roll and three roll (four roll is rarely used). The main feature of two roll is that the mechanism is simple, easy to manufacture and maintain, and the stiffness is better than that of three roll. However, three roll has obvious advantages: the hole pattern is composed of three sections of arcs, and the force is uniform when the steel pipe deforms. The machining accuracy of the frame is extremely high, and the rolling quality is better than that of two roll. Therefore, the use of three roll continuous longitudinal rolling is becoming more and more widespread. Most fixed reducing machines, tension reducing machines, pipe jacking machines, and pipe stripping machines use three roll continuous longitudinal rolling. Even traditional continuous pipe mills that only use two roll are now adopting three roll continuous longitudinal rolling. Roll. Therefore, studying the pass of three roll continuous longitudinal rolling is of positive significance for us to keep up with the development direction of steel pipe rolling, study the rolling process of steel pipes, and develop steel pipe rolling equipment.
For more information about our company's cold-rolled pipe mill, please refer to the website: iguys.cn