Research On Numerical Simulation And Process Parameters Optimization Of Titanium Pipe Cold Push-Bending

In recent years, titanium seamless elbow with high specific strength and corrosion resistant advantages are widely used in Aerospace and petrochemical field. Cold push-bending forming technology with high efficiency, low cost, good mechanical properties of products, etc. was widely used in carbon steel, stainless steel and other easy deformation pipe bending. However, the plastic deformation capacity of titanium is weak at room temperature. When we use cold push-bending process to produce titanium elbow, the bending method can not copy form that for the carbon steel, stainless steel. Therefore, in this paper the forming characteristics and rules of titanium tube cold push-bending was studied systematically. The results would provide theoretical guidance and practical reference to the further application of titanium alloy elbow.At first,in this paper, the performance and characteristics of titanium and some common bending methods was introduced on the basis of a lot of reading literature. Then the basic principle of the titanium tube cold push-bending and the common bending defects was researched,and the main defects are: outer arc side wall thinning, thickening of the wall thickness of the inner side of the arc, cross-section distortion, etc. And some prevention and improvement measures were put forward for the above defect. Then, titanium tube cold push-bending geometric parameters were analyzed in this paper. At the same time, in order to understand the material properties of titanium tubes, uniaxial tensile test is completed with the titanium tube material, and the establishment of material models of finite element modeling based on the uniaxial tension test results.Secondly, to further study the process of titanium tube cold push-bending process, research the influence of process parameters on the titanium tube cold push-bending forming, we presented the research method which combining the finite element numerical simulation analysis and the experiment. Using the finite element analysis software to simulate titanium tube cold push- bending process, analyzing the distribution of wall thickness, as well as the forming limit and strain state of the titanium cold push bend based on the finite element results. And then the actual cold push-bending processing of titanium tube was completed with cold push-bending die, and the true value of wall thickness of the forming elbow was measured. And then the reliability of the cold push-bending finite element simulation model was verified through comparing the actual results with the simulation results. And then the influence characteristics and rules of mandrel structure, the pushing distance of the push rod, die clearance, friction coefficient, bending speed and other parameters on titanium cold push-bending were researched with the reliable cold push-bending finite element model. And the reasonable range of process parameters was determined on the basis of titanium elbow forming quality.Finally, according to the research findings above, titanium tube cold push-bending process parameters were optimized using the virtual orthogonal experiment, and the optimum process parameters was determined ultimately. Then the actual processing of titanium tube was completed with the cold push-bending die with the optimum process parameters, The results showed that quality of titanium elbow is high which verified the correctness of the optimization results.