Study On Numerical Simulation And Forming Quality Of Single Point Incremental Forming Process For Corrugated Tubes

Single point incremental forming is a flexible forming technology for sheet metal parts.Single point incremental forming technology has the advantages of simple structure clamping device,easy realization of automation and high flexibility.Therefore,there are many applications in sheet metal and tube forming of multi variety and small batch parts.Single point incremental forming of tubes is formed by using simple tools.The tool wheel loads the local area of the tube wall according to the layered forming path.It causes plastic deformation in the forming area of the tube wall,and eventually accumulates deformation to obtain the required tubular parts.At present,the forming process of metal corrugated tubes is hydroforming,mechanical bulging and welding forming.However,there are forming defects in these forming processes.For example,such as complex forming die,high energy consumption and Low production flexibility.The single point incremental forming technology of metal corrugated tubes is established in the thesis.The theoretical derivation,finite element simulation and experimental analysis of incremental forming process of metal tube are carried out.The influence of forming parameters on formability and optimization strategy of processing parameters were obtained.These studies will provide basic research for the application of incremental forming of corrugated tubes.The theoretical analysis model for single incremental forming of metal tubes has been established.By analyzing the changing rule of the contact area and the forming force of the tube wall and the tool wheel,the forming force formula in three directions of contact area can be calculated.The radial deformation of the tube wall and the axial flow pattern of the wall material were analyzed.The theoretical formula for reducing the thickness of the tube wall is established.According to the principle and characteristics of incremental forming technology,a finite element analysis model for incremental forming of metal tubes is established.Abaqus/Explicit was used to simulate the forming process,and the change rule of forming three component forces along the forming time was obtained.The simulation results are in correspondence with the theoretical results,which verify the accuracy of the theoretical model.The stress and strain distribution characteristics of the forming parts were analyzed.The change rules of the tensile and torsion of the tube wall and the thinning of the wall thickness are obtained.Moreover,the simulation results are two kinds of stress three axis curves of tube single point incremental forming and bulging.The forming limit of two forming methods is compared.The experimental platform was built to carry out incremental forming experiments of single corrugated tubes.The experimental results show that the data of the three forces and thickness of the tool wheel are similar to the theoretical and simulation data.It shows that theoretical analysis and finite element simulation are accurate.The influence of interval spacing,spindle speed and axial feed speed on the forming height of corrugation was studied.The influence of different process parameters on forming quality is obtained,and the best combination of process parameters is formed.The relationship between the microstructure and the quality of the parts was obtained by analyzing the microstructure of the surface.After single corrugated tubes incremental forming analysis,the incremental forming mechanism of multi corrugated tubes is further studied.The influence of different distance between corrugations on the forming quality of the corrugated junction area is obtained through simulation and experimental analysis.There are also rules for the stress strain and corrugated profile of corrugated connections.The error of tube wall thickness and profile height is analyzed.The optimization method of incremental forming process parameters considering the influence factors of corrugated profile size,wall thickness and distance between corrugations is obtained.All these studies provide reference for precise control of single point incremental forming of metal corrugated tubes.