Research On Forming Process And Simulation Of Three-Way Tube

Tee joints are a key component in pipeline transportation systems.Seamless tees with good surface quality and excellent mechanical properties have been widely used in the pipeline industry.At present,seamless tees are generally produced by straight pipes as T-shaped tees and Y-shaped tees.However,with the development of the pipeline industry,it is often necessary to use other shapes of tee pipe,and the existing forming process often cannot form seamless tees with new shape.Therefore,this paper mainly studies the plastic forming process of a tee with special shape,hoping to enrich the processing means of seamless tee.On the basis of reading a lot of literature and in-depth analysis of the structural characteristics of the Y-shaped tee,the hydro-extruding process is proposed.It is a composite forming process based on internal high pressure forming and extrusion forming,which can simultaneously reduce the diameter of branch pipe and expand the main pipe.Based on the process of hydro-extruding,the forming scheme of Y-shaped tee pipe is designed.Compared with the traditional forming scheme of stamping half pipe and butt welding,the new process can obtain a seamless tee and the quality of the pipe is better.The finite element software ABAQUS is adopted to carry out numerical simulation research on push-bending of 180°elbow.The results show that: the wall thickness distribution of the tube blank has a rule that the outer middle portion and the inner front end become thinner,the inner middle portion and the outer rear end become thicker,the outer front end and the inner rear end changed little.Increasing the friction coefficient can reduce the outer wall thickness thinning and increase the inner wall thickness.Excessive friction coefficient or internal pressure may cause the lacking of forming on the elbow.The numerical simulation of the first pass forming of hydro-extruding shows that: The wall thickness of main pipe is thinning due to bulging.The wall thickness of branch pipe is thickening due to the diameter reduce.At the mold parting surface,the wall thickness increases most severely.The main quality problems of this process are uneven wall thickness distribution and wrinkling.The internal pressure plays a decisive role in wrinkling,and when the internal pressure is above 30 MPa,the wrinkles disappear.When the internal pressure is 35 MPa,the forming quality is good.The smaller the coefficient of friction,the smaller the wall thickness difference.A suitable internal pressure loading path can improve the wall thickness distribution.According to the process parameters obtained in the first simulation,the later three pass forming was simulated,and the Y-shaped tee with good quality was obtained.The maximum wall thickness thickening rate was 33.5%,the maximum thinning rate was 18.1%,and the cross-section distortion was less than 2.1%,which proved that the forming scheme was feasible.