Key Technology And Characteristic Study Of The Continual Mandrel Rolling Compact Process For Producing Minor Diameter Seamless Steel Tubes

Seamless steel tube is a indispensable kind of steel with economic cross section, which is widely used in national economic construction. With the increase of demand on minor diameter seamless steel tubes at home and aboard, domestic production processes mainly focusing on cold rolling, cold drawing and extrusion are behindhand. At the same time the number of production equipment becomes more and more, which leads to serious environment pollution and great energy consumption.With the increase of requirements for environment protection and energy saving, these equipment and processes have been listed in elimination. Due to the advantage of advanced process, fast production and low pollution emissions, three rollers continual mandrel rolling equipment becomes recommend mill for manufacturing minor diameter tubes. However, the existing three rollers continual mandrel rolling equipment mainly aims at production design of large diameter tubes.The process and equipment of minor diameter steel tube are still in the exploring study phase, which is imperative to study. So developing the basis theory and simulation technology research on short process rolling process of minor diameter seamless steel tube and mastering the deformation mechanism and forming regularity can not only simplify the design process of device and process, but also benefit for energy conservation and emissions reduction, less product production process and less investment on equipment and human, which provides important significance and practical value for enterprise competitiveness.The existing pass design theory on three-roller continuous rolling is difficult to solve the problem of continuous rolling process under the condition of small diameter, even short flow process and decrease number of frame more increase the difficulty of the hole pattern design.In order to solve the above problems, combining with theory and practical production experience, continuous rolling deformation process of small diameter steel tube was analyzed theoretically, which revealed the deformation characteristics of small diameter steel tube in continuous rolling process. At last the whole pattern design method of small diameter steel tube in continuous rolling process was deduced.3D meshless method numerical simulation model of steel tube deformation in continuous rolling process was built in order to study deformation feature of small steel tube. The unknown field approximation function was built by using moving least square, and the construction and the derivation process of approximation function were simplified bycombining with the dual point method in the model.The approximation function was corrected with local correction method to exert boundary conditions more fast and accurately.The stiffness matrices of the velocity field and temperature field were constructed using the weighted least square method and the meshless collocation method respectively. The solutions of the two coupled fields were calculated with the indirect coupling method.Geometry changes, temperature field distribution and stress-strain field distribution were studied in the continuous rolling process by simulation.Finally through the experimental verification, this model was effective.The metal deformation character, effects on rolling force energy parameters of hole pattern and roll rotating velocity and the law on expanding deformation and metal flow of small diameter steel tube were studied with simulations and experiments aiming at different hole pattern and dimensions size. Continuous rolling process technology of small diameter steel tube was developed. Finally the theory was reliable through experimental verification,also the process was feasible.