Comparison And Analysis Of The Inner Cavity’s Shape Of The Combined Flat Extrusion Cylinder And Study On The Distribution Of The Interference Between The Cylinders

In terms of metal extrusion processing’s essence, it is a method of applying an external force to produce a plastic deformation of the metal which is subjected to a three direction stress in a pressure vessel, and from ad hoc hole or gap being squeezed out, resulting in certain section shape and size of the extrusion product. As the core component of extrusion equipment, the extrusion tube has the following disadvantages: high working temperature, concentrated stress, frequent friction between the lining and the processing material and short life. Many studies at home and abroad have shown that compared with the circular extrusion cylinder, the flat extrusion cylinder can provide more favorable flow conditions when the extruded flat width profiles can be used to reduce the extrusion pressure, but because of the larger curvature of the inner hole, the stress concentration is more obvious. So it is necessary to optimize the structure. In this paper, the design scheme of three kinds of flat extrusion cylinder is compared with the circular extrusion cylinder,and the optimal design scheme is studied and analyzed in the case of varying interference.This paper mainly carried out the following work:(1) By using the method of plane problem in polar coordinates, the cylinder under uniform pressure should be used to analyze and calculate the stress distribution. With the stress superposition formula is derived in this paper combined the cylinder, the stress distribution of cylinder is obtained under the action of the assembly should stress and hydrostatic pressure. Combined with the finite element method to simulate the extrusion tube and compare the analytical solution and the finite element solution.(2) According to classical mechanics and design criteria of extrusion cylinder to establish a three-dimensional model of elliptic flat extrusion cylinder, a semi-circular flat extrusion cylinder, double fillet transition type flat extrusion cylinder. Using the finite element software, the first two kinds of flat extrusion tube were calculated and compared with different interference, and the optimal amount of the cylinder and the two kinds of flat extrusion tube were determined.(3) Comparative analysis of extrusion stress distribution in the different dimensions of the double fillet fillet flat. Then select the optimal hole size. The optimal solutions of three kinds of flat extrusion cylinder and cylinder are compared. Follow up research and analysis of the optimal plan.(4) By observing the shape variable of the double fillet transition flat extrusion tube in the middle and the inner cylinder combined loading, and design the flat extrusion cylinder with variable interference amount. An optimal solution for varying magnitude of interference is obtained by comparing a large amount of computation data and it is equal to the outer surface of the inner cylinder when the inner cylinder and the middle tube are combined. Four different size parameters are selected to design the comparison method and test the stress and strain, and determine the selection method of varying the amount of interference.In this paper, the research methods and analysis results has significant meanings on optimize the structure design, improve the stress distribution, and improve the service life of the flat extrusion tube.