Research On The Theories Of Taper-rolling Process Of Endless Spirals And FEA Simulation

The spiral-rolling with the axes of conical rollers in different surfaces is advanced compared with other forming methods so it is widely adopted in the forming field. Nevertheless, because of its complicated technique of production and difficult adjustment process, manufactures have still been broadly using the method to adjust the rolling by experience. A great deal of steel is wasted and the advantage of high efficiency and low consumption is damaged.In order to solve the difficult problem of rolling adjustment and direct the manufacturing, the theory of non-unplanar rolling of endless spirals is studied and the laws of forming is concluded in this dissertation.The taper-rolling process of endless spirals includes two kinds of deformation. One is the deformation of forming circles as the workpiece is unequally compressed; the other is the deforming in forming spiral pitches as the workpiece is currently roll-bended, The nip condition, steady rolling condition, metal flowing condition, balancing condition and neutral angle are deduced. After the equation of roller surface is built, the leading parameters of controlling the deformation of the workpiece—the thickness t and the direction of the roller exitαfrom which the workpiece goes out, are proposed and deduced and their analysis method and iteration method are established. The parameters which characterize spatial location of rollers and workpiece are defined. The adjusting and optimizing program are worked out by using C which discuss the laws of how the spatial parameters affect the shape of spirals and provide initial value for rolling simulation.The rolling process is simulated by elastic-plastic FEM.The key skills, such as contract, friction model, grid remeshing are researched and discussed. A simulating model is presented and Stress, Strain, Contact Friction Force, Contact Normal Force,Moment, Width Extension are analyzed and explored in the rolling process. The effect of key parameters on the shape of spirals are classified and simulated. Finally,the laws of rolling shape results, force variation, forming speed varying with spatial parameters S₁,S₂,H,Δθ,θ₀ and other parameters friction coefficientμ_s, material M, rotational velocityωareanalyzed and action principles are illuminated simultaneously.By using "prediction—simulation—fine turning" method, the preinstall spirals' rolling parameters are obtained. The parameters and laws derived from simulation can be used in guiding taper- rolling process of endless spirals, thus the adjustment speed is faster, much steel for test is saved, and rolling accuracy is improved.