Numerical Simulation Of Drive Shaft Precision Cold-drawn And Mould Optimization Design

Drive shaft is widely used for various auto, machinery and house applianceindustry of shaft parts. When the precision comes up to IT6~IT5, we usually adoptturning-grinding processing method, as a result not only large equipment investment,low production efficiency, and the processing process is not suitable for greenmanufacturing. While the traditional technology of the cold drawing shaft, which islow dimensional precision and poor stability of finished product, can not meet thequality requirements of high precision drive shaft. Drive shaft precision levelcold-drawn technology is optimization, improvement and technology innovation ofthe traditional cold drawing process. This topic research is based on the optimizationof the pretreatment of pickling-phosphating-saponification process conditions, bymeans of finite element simulation of the steady state drawing process to study theimpact of structure parameters, mould drawing technology and prestressed in colddrawing forming process, as while as carrying on the optimization design, so as torealize precision level cold-drawn technical requirements, allow the cold drawingprocss of shaft to be used directly with bearing..This article mainly from the influence factors of the process of drawing, thedrawing force experiment, mould optimized design and prestressed die design thosefour aspects to analyse. First using finite element analysis software ANSYSWorkbench to simulate drive shaft’s steady cold drawing process. A single factorvariable method was used, in turn, to analyze friction coefficient, work cone Angle,sizing belt length, gate amount of machining and drawing speed on the effect of colddrawing forming, which laid a foundation for die structure parameters optimizationdesign. The experimental results show that the drawing force and friction coefficientwas approximate linear relationship, the coefficient of friction has little impact on theforming process of the radial, axial and circumferential stress.Work cone Anglegenerally choose2α=8°~12°, which make the drawing force for smaller values; Sizing belt length the longer the bigger of the drawing force, so it shoulds not be toolong or too short. With the increase of the deformation the drawing force increasesgradually, and available method of double decline can be used to carry on the designdrawing passes. The speed of precision drive shaft should better be between8~10m/min.In drawing force experiment part, the drawing force measurement experiment wasconducted through designing the mould fixed device, as while as the contrast analysisof the difference between the simulation results and the experimental results. In termsof drawing force, forming the diameter, relative errors of the simulation results withthe measured results are below3%, while the use of empirical formula of drawingforce is more than20%relative error.The simulation of forming bar tail line appearedto concave arc is inosculated to the "pit" phenomenon of the back face of the actualdrawn product.Secondly, using the orthogonal experiment method to conduct the mold structureparameters optimization design, combined with the mathematical model ofmulti-objective evaluation function. By means of the orthogonal experimental method,the die structure parameters (work half cone Angle alpha, transition arc radius R,sizing with the length of the Ld) on the drive shaft was researched in the aspect of theeffect of the cold drawing forming. Optimal combination for mould parameters isα=5°、R=5mm、Ld=4mm, under the condition of minimum drawing force, minimumradial compressive stress and the minimum equivalent residual stress. On the basis ofthe results, simulated comparative analysis was carried through between theoptimizing design scheme and the traditional scheme. The results show that theoptimized die structure is better than the traditional scheme, which is beneficial toimprove the quality of cold drawn products, extend the life of the mold.At last, the analysis of the prestressed die design. Through static mechanics modelanalysis of the cold drawing process, it was found that there was a linear relationshipbetween the drawing force variation the prestressed, namely,ΔP=K·Fn,ratio K=sin(α+β) cosα/cosβ(mold work half cone Angle and friction Angle areconstant),which provides important reference for the pretressed applied in the2Dfinite element analysis model.Through numerical simulation contrast prestressedbefore and after applying the steady cold drawing process in the shaft, it is concludedthat in the adding prestressed cases steady-state drawing radial compressive stressincreases, the axial compressive stress and circumferential stress, equivalent stress,the drawing force, the radial compression deformation were reduced.