Research On Technology Of Multi-pass Die-less Non-circular Spinning

Spinning is an advanced manufacturing process with little or no cutting.The tool,such as a spinning roller,is pressed against a metal sheet or cylindrical blank to produce continuous local plastic deformation on the workpiece and gradually form the required rotary part.Spinning technology is usually applied to the forming of hollow parts with circular cross-section.In order to spin hollow parts with non-circular cross-sections,which is overcoming the limitations of metal spinning,researchers all over the world study on the technology of spinning hollow parts with non-circular cross-sections and proposed a variety of methods.In the study,a new high-efficiency non-circular spinning technology is adopted.Rollers are arranged on the rollers disc,which is driven by the principal axis of the roller.And the principal axis of the roller is synchronized with the principal axis of the workpiece.Relative motion between the roller and the workpiece is used to spin the workpiece,and the radial feed of the principal axis of the roller does not need to be considered during the spinning process.Furthermore,the rotation rate of the workpiece and the accuracy of the roller trajectory are both guaranteed.Through this new non-circular spinning technology,the diameter of the processed blank is increased from 50 mm to 100 mm,the thickness is increased from 1.5mm to 2mm,and the rotation rate of the workpiece is increased from 40r/min to 60r/min.In theory,the higher the rotation rate,the more stable the processing state.And the triangular workpiece which is more difficult to form are processed.In the stable spinning stage,its shape accuracy is within the range of ±0.25 mm.In this paper,the finite element theory related about the simulation of non-circular spinning is discussed.ABAQUS 2016 is used to establish the finite element model of non-circular spinning.The strategy employed to improve the simulation efficiency and ensure the accuracy of simulation results is analyzed.And the selections of the key process are discussed.The motion trajectory and processing principle of the three-rollers triangle,double-rollers triangle and singleroller triangle are deducted and the method for polygon non-circular spinning based on different rollers setting is proposed.Through the simulation results of the three types of non-circular spinning,the deformation process,equivalent stress and strain distribution,three-direction strain,typical section wall thickness distribution,spinning force history during processing and dimensional accuracy of formed workpieces are all analysed.Based on this new non-circular spinning method,a non-circular spinning equipment is designed and developed.The layout of the equipment is analyzed to make sure the rationality of the components.A spinning force measurement system was designed which could follow the rotation of the roller.The measurement system could collect data for analysis and improving the non-circular spinning.The non-circular spinning equipment was used to study the non-circular spinning process,and the non-circular spinning theory and simulation analysis results were verified.Taking threerollers triangle,double-rollers triangle and single-roller triangle as the research objects,the influence of the feed rate,the rotation rate of the workpiece principal axis,the working arc radius of the roller and the length of the roller shank on the spinning force,workpiece wall thickness,workpiece roughness,workpiece hardness,are all analyzed.The strain of the workpiece during processing was revealed through the grid test,and the dimensional accuracy of the workpiece is examined.The defects in the experiment were analyzed,and the processing parameters of threerollers triangle were optimized based on the principle of gray correlation degree.