The Experiment And Numerical Simulation Study On Multi-pass Conventional Spinning

Metal spinning is a forming process which can produce a variety of symmetricalseamless rotary parts. It refers to different technologies such as forging, extrusion,bending, deep drawing, rolling, et al, meanwhile it possesses local continuous plasticdeformation feature. Due to the advantages of low material cost, high processingefficiency, good product quality and simple molds design, the spinning has been widelyapplied to defense, aerospace and civil fields.In this paper, the forming of curved bus-type rotary part with material1070aluminum is investigated. The multi-pass spinning forming method has been adopted inthis paper. Based on the characteristics of the spinning part, the forming moulds such asmandrel, tailstock and spinning roller have been designed and the forming programs forthe spinning roller has been made. Forming process has been analyzed deeply throughcombination the methods of physical experiment and numerical simulation.The grid coordinate method had been introduced to analyze the deformation ofmulti-pass curved bus-type part during the physical tests, it shows that the bendingplastic deformation dominating the whole spinning process in the blank and the torsiondeformation is only observed in the region of the spinning part tail during the shapingprocess. Thus, the spinning part has a good symmetry. In addition, steel rollers andrubber rollers had been used respectively for the investigation of the influence of rollerhardness on surface quality of the spinning part. In the case of steel rollers, darkerwaviness appeares on the spinning part surface, while the spinning part has a smoothsurface which used rubber rollers. Moreover, the hardness of surface before and afterspinning was observed. It’s found that the hardness of the outside surface and the innersurface are both increased compared to the original hardness of the blank, the hardnessof outside surface and the inner surface is increase by67.15%and50.84%, respectively.Furthermore, the influence of feed ratio f and clearance C in shaping process onhardness of the spinning part was investigated. It shows that the feed ratio has a litterimpact and clearance has a great impact on hardness. The hardness of the outsidesurface and inner surface increase by5.02%and2.01%for f=6.428mm/r compared tof=1.714mm/r, the hardness of the outside surface and inner surface increase by50.4%and58.24%for C=0.5mm compared to C=1.2mm. Besides, the defects and theinfluence on radial thickness and radial strain of parts of clearance in shaping process were analyzed. In the shaping process, rupture occurred when the clearance C is0.5mm,wrinkling appeared when the clearance C is1.2mm. The radial strain of the spinningpart increases with the decrease of the clearance, while the radial thickness decreaseswith the decrease of the clearance. So an appropriate clearance in the spinning processcan effectively reduce the appearance of rupture, wrinkling and other defects.Based on the FEM software ABAQUS, The finite element models of multi-passcurved bus-type spinning process, which are accord with the experimental conditions ofprocess and parameters settings on various programs, were established for numericalcalculation. Compared with the experimental results to verify the reliability of themodel, it shows that the radial thickness maximal error and radial strain maximal errorare11.3%and15.8%, respectively. This indicated the feasibility of the numericalmodel.Finally, deformation mechanism during spinning process and the effect of theimportant technological parameters on spinning process were further simulation studiedbased on the above FEM model. It indicates that deformation mainly occurred on theflat portion of the blank and the stress and strain along this region are very large. Themaximum thickness of the blank occurs at the edge of the blank after each pass. Thefeed ratio and the roller installation angle have a great impact while the speed rotationof spindle and the friction coefficient have a litter impact on spinning process. It isprone to wrinkle during spinning process as the increases of feed rate which canincrease the equivalent strain. The roller installation angle should not be too large or toosmall, the thickness of sheet is uniform and the equivalent stress is smaller when theinstallation angle β is45°. The spinning part with a higher speed rotation of spindle hasa better forming quality and smaller equivalent strain than that with a lower speedrotation.