Study On The Extrusion Process Of Forming Bending Pipe Based On Flow Velocity Field Control

With the advance of lightweight vehicles and the rapid development of aerospace technology, curved pipe with its high specific strength and high stiffness, so there is a wide range of applications, the development of cars, large aircraft raised the urgent need of thin bending aluminum alloy pipe. The development of industries such as cars, large aircraft has also raised a higher demand for the quality of thin bending aluminum alloy pipe, development of new technology for pipe bending forming technology development to become an important direction.The research group use the imbalance metal flow theory put forward ways of eccentric extrusion forming bending pipe parts. Using eccentric structure design, through take measures on the mold structure, billets, process parameters,etc. to increase the metal flow imbalance. The use of imbalance flow of materials in the pipe extrusion process directly through the extrusion obtained pipe bending parts. Achieve pipe extrusion and bending process by one-time forming.In this paper, first using finite element method,achieved three-dimensional numerical simulation of the forming process by DEFORM-3D finite element commercial software,study the eccentric extruded forming pipe bending parts based on material flow control method. Achieved velocity field distribution , material flow , stress and strain field distribution ,squeezing pressure of the process. Analysis shows that pipe bending parts achieved by this method the stress distribution is uniform, wall thickness uniform, the same bending radius of curvature.Then, optimize the model to design the needed die for experiment on this basis, first test and verify through the soft materials rubber mud and Pb, after deformation we analyze the thickness of workpiece as well as the radius of curvature to verify the feasibility of this method.Second achieved three-dimensional finite element numerical simulation of bending aluminum-alloy tube in differential velocity, in the role of two-block punch, through the extrusion bending forming method one or more blocks of billet will be extruded from the mold, extrusion and bending composite to form pipe bending parts, by controlling the extrusion velocity gradient in the extrusion process to achieve different angles of bending, control the pipe radius and wall-thickness accuracy. Through the finite element analysis of the forming process under the action of pairs of punch to obtain its velocity distribution, material flow mode, stress distribution, wall thickness distribution, load changes, as well as extrusion deformation of workpiece. The results show that the stress distribution uniform, wall thickness uniform, the control of the bend radius can be achieved by controlling the velocity gradient.Numerical simulation and actual test verification showed that metal flow evenly, pipe radius and wall thickness can be precision controlled, and effectively improved the quality of bending pipe during the method of forming process. At the same time, on this basis, laid a good foundation for the forming process under the action of multi-punch, the direction of bending over can be achieved under the action of multi-punch.