A Study Of Supporting Modes Of Die-less Spinning Of Curvilinear Generatrix Parts

The spinning forming is an advanced manufacturing technology to realize the less or non machining of thin-walled rotary parts,with the advantages of high precision,good flexibility,saving material,easy to realize mechanization and automation etc.,and become an important development direction of plastic forming technology.However,the traditional spinning process need specific mandrel to produce the corresponding product,and is limited when applied to many varieties,small batch production.In recent years,although the die-less spinning is out of the limit of the specific mandrel,but because of the single stress of the sheet metal,the processing is not stable,which cause the springback deformation of the product and obvious error of shape precision.For the technical problems mentioned above,the method of auxiliary support is used to perform die-less spinning of curvilinear generatrix parts in this paper,which increases the plastic deformation of the sheet metal and improves the shape accuracy of the forming parts.The main contents and contributions of this paper are as follows:(1)Based on the ANSYS/LS-DYNA software,the dynamic simulation model of the die-less spinning process is constructed.By extracting the key processing size of the components,a synthetic simulation model is established for the realistic die-less spinning of curvilinear generatrix parts.The simulation model is validated by the energy method and the experimental comparison method,which lays the foundation for the subsequent study of the die-less spinning of curvilinear generatrix parts based on auxiliary support.(2)A die-less spinning method based on auxiliary mandrel support is proposed.By using the auxiliary mandrel which is compatible with the initial section of the curvilinear generatrix profile,compared with the unsupported die-less spinning,the influence of die-less spinning method based on auxiliary mandrel support on the shape precision and thickness reduction of sheet metal was studied by means of simulation and experimental comparison.The experimental results show that the maximum shape error of the mandrel-suppout die-less spinning is 8.11mm,which is 81.94%higher than that of the unsupported coreless spinning.The average shape error is 1.60mm,which is higher than that of the unsupported coreless spinning 92.45%.The results show that the arithmetic mean of the maximum shape error is 6.45mm,and the arithmetic mean of average shape error is 1.61 mm.It is shown that the die-less spinning method supported by the auxiliary manderl has great influence on the overall bending of the sheet metal forming,but the deformation of the curve with large concave and convex degree will appear during the processing.But there will be processing distortion for the curvilinear generatrix parts with greater degree of concavity and convexity.(3)The die-less spinning method based on auxiliary roller pulse support and servo support is proposed.The deformation process of the sheet in the radial direction is regarded as the local deformation of the sheet matel,which is divided into several small segments along the radial direction,and the supporting roller is supported for each segment.The shape and thickness accuracy of the workpiece of the three curvilinear generatrix curve are compared with by simulation and experiment.The precision of the shape and thickness of the workpiece produced by the die-less spinning method based on pulse support and servo support is studied.The results show that the arithmetic mean of the maximum shape error of pulse support die-less spinning method is 19.66mm,the arithmetic mean of the average shape error is 10.19mm.And the arithmetic mean of the maximum shape error of the servo support die-less spinning method is 19.68mm,the arithmetic mean of the average shape error is 9.80mm,but the shape of the workpiece is similar to the target shape without distortion.(4)The die-less spinning method based on composite pulse support and composite servo support is proposed.Combined the advantages of auxiliary manderl support and auxiliary roller support in sheet metal spinning,a new die-less spinning method is proposed,in which the auxiliary manderl and the auxiliary roller are used for the composite support.The shape and thickness accuracy of the workpiece of the three curvilinear generatrix curve are compared with by simulation and experiment.The precision of the shape and thickness of the workpiece produced by the die-less spinning method based on composite pulse support and composite servo support is studied.The results show that the arithmetic mean of the maximum shape error of the composite pulse support die-less spinning is 8.87mm,and the arithmetic mean of the average shape error is 3.70mm.The arithmetic mean of the maximum shape error of the composite servo die-less spinning is 4.55mm,the arithmetic mean of the average shape error of composite servo die-less spinning 1.37mm,which forming effect is optimal without distortion.(5)The five kinds of auxiliary supporting modes in die-less spinning are comprehensively compared,and the application of the optimal forming method is verified.The comprehensive influence of various supporting methods on the product processing was analyzed from the whole and part contour shape accuracy and the wall thickness reduction of the workpiece,and the influence degree of the auxiliary support on the die-less spinning process is quantitatively expressed.At last,five different processing contour curves were used for experimental processing with the optimal method,the composite servo support method,of the die-less spinning.The experimental results show that the maximum shape error is about 5.91mm,the average shape error is about 2.48mm,the minimum wall thickness is about 1.19mm,the maximum wall thinning rate is about 36.68%,and the average wall thickness reduction rate is about 20.14%.The flexibility of the composite servo support in the different curvilinear generatrix parts of the die-less spinning process is further verified.