Research On Numerical Control Single Point Progressive Forming Process Sheet Forming Limit

As a new kind of flexible automation technology,NC single point incremental forming(SPIC)is introduced into the idea of "layered manufacturing".With the aid of trajectory path planning and NC machining program,the machining of parts is finally completed.Compared with the traditional forming technology,this technology can shorten the product cycle,save the cost,reduce the forming force and increase the forming limit,etc.It is especially suitable for many kinds of small batch products,but its forming accuracy is poor.Low production efficiency has become the bottleneck of its application development.In addition,there is rarely a clear experimental study on the forming limit to explain the strain variation in the progressive forming process.The forming limit diagram is seldom used to predict the forming performance of A1 sheet metal and to analyze the influence of processing parameters on the forming limit of A1 sheet metal.Based on the theory of progressive forming and plastic forming,the stress strain and thinning rate of progressive forming process are analyzed in this paper,and the trajectory of tool head in progressive forming process is reasonably planned by means of UG MATLAB and ORIGIN software.Numerical simulation of incremental forming is carried out by using ANSYS/LS-DYNA software.The effects of processing parameters(initial plate thickness,layer feed rate and tool head radius)on stress and strain distribution,thinning rate change and forming limit of different Al sheet metal in progressive forming are analyzed.Finally,based on the above theory and numerical simulation results,incremental forming The correctness of numerical simulation is verified by relevant experimental research.In addition,the forming limit angle and the maximum thinning rate are used to evaluate the forming limit in the gradual forming process.By using the method of simulation analysis and experimental verification,the influence of forming limit and machining parameters on forming limit of A1 sheet metal in progressive forming process is studied.It provides a basis for the research of forming limit and forming precision in the process of incremental forming.The results show that the forming limit of Al sheet metal increases with the increase of forming limit angle,and the fitted forming limit diagram is an inclined line with slope 1.The forming limit angle and the maximum thinning rate are used to evaluate the formability of sheet metal.The influence of processing parameters on the forming limit of Al sheet metal in progressive forming is as follows:under the condition of single variation,when the initial plate thickness is 1.5mm,the incremental forming limit of 1060A1/08A1 and 6061A material is larger,but the forming limit is larger.The accuracy is lower than the initial thickness of 1.0mm and 0.8mm;for 1060Al material,the layer feed is within the range of 0.8mm?1.5mm and the layer feed is 0.8mm,the incremental forming limit is larger and the forming precision is higher.For 1060Al and 6061 Al,When the radius of tool head is 6mm,the limit of progressive forming is maximum,and the precision of tool head is the highest when the radius of tool head is 5mm.