Research On Optimization Of NC Moldless Pipe Bender And Automatic Generation Of Machining Program

When the metal pipe is bent,it will face the phenomenon of springback and so on,which makes the precision of the forming part deviate from the design.According to this problem,based on the NC moldless pipe bender,this paper studies the section quality optimization,springback correction and spline bending forming of four kinds of analysis objects from both theoretical and experimental aspects,and develops the pre-processing software based on IGES.First of all,a series of bending preforming tests have been carried out on the overall understanding of the pipe bender,and the quality problems(wrinkle and tear)of the bending forming section of the pipe have been found.By optimizing the edge treatment of the bending deformation zone and setting the transition amount for the Z axis feed,the wrinkling is effectively alleviated.At the same time,under the condition of ensuring the wrinkle quality,the buffer amount is set for the offset of the X-Y table to alleviate the influence of the transition amount.Secondly,the most appropriate constitutive relation is selected by analyzing the factors affecting the springback of pipe bending,the elastic-plastic hypothesis and the stress-strain law at the deformation stage,and then the preliminary springback prediction and correction mathematical model is deduced.After bending forming test,the final mathematical model of each analysis object is fitted in Matlab.Then,a process analytical method was proposed to transform the spline curve into a number of straight lines and arcs according to the adjustable step length,which was verified in the bending forming experiment.Finally,based on IGES,the pre-processing software for generating NC machining codes is redeveloped,the function of section quality optimization is added,the user interface is simplified,the mathematical model of springback correction is supplemented,and the spline curve bending is added.The IGES file can be converted to the user’s requirement through five steps: file preprocessing,spline curve discretization,spline curve segmentation,multi entity sorting and transforming geometric information into NC code.The accuracy of the springback correction mathematical model and the wrinkle rate of bending deformation proposed in this paper are controlled within 5%,which provides a good theoretical basis and solution for bending forming and has certain practical application significance.