Mathematical Model And Experimental Research On Ball Spinning Process Of Thin-walled Pipe

Ball spinning is a continuous local plastic forming process.Ball spinning has the characteristics of simple tooling,small tonnage of forming equipment,symmetrical forming load,high unit contact pressure,high dimensional accuracy of finished products,good surface roughness,etc.thus it has been widely used in the production of thin-walled tubes with high precision,high strength and small diameter.The mechanical analysis of ball spinning process has always been the focus of domestic and foreign experts and scholars,rotational pressure is one of the important force and energy parameters in ball spinning process,fast and accurate calculation of rotational pressure is an important prerequisite for equipment selection and mold design.As a tool for direct deformation during spinning,the size of ball diameter directly affects the spinning angle,the number of balls and other technological parameters,which ultimately leads to obvious differences in the quality of spinning finished products,it is of great significance to further study the selection method of ball diameter to guide actual production.Based on plastic mechanics,this thesis uses the methods of theoretical calculation,finite element numerical simulation and spinning experiment to systematically and deeply study the mechanical properties of ball spinning process,the selection of ball diameter and the spinning characteristics of AZ31 B magnesium alloy.In this paper,the upper limit method is used to establish the relationship between ball spinning process parameters and force and energy parameters,the relationship between each process parameter and force and energy parameters is studied,the real-time calculation model of ball spinning pressure is given,by adjusting the process parameters,the spinning pressure can be adjusted to control the quality of the formed products,comparing the theoretical calculation results with the finite element numerical simulation results,the calculation error is within 6%,which verifies the correctness of the theoretical calculation;The selection method of ball diameter is given,and the selection method of ball diameter with small thinning rate is discussed emphatically,the stress and strain distribution are analyzed through finite element simulation,and the strain distribution with different ball diameter selection methods is compared,which verifies the rationality of the ball diameter selection method in this paper;According to the situation of ball throw in the experiment and simulation,the theoretical analysis is carried out,and the connection between rotation speed,cone angle and ball throw is discussed;The spinning experiments of magnesium alloy balls were carried out,and the influence of different technological parameters on the spinning performance of magnesium alloy was analyzed,magnesium alloy pipe fittings with higher surface quality were spun by reasonably matching the parameters.