Research On Precision And Surface Quality Of NC Incremental Sheet Metal Forming

NC incremental sheet metal forming technology is a new sheet forming technology,no special die,can give full play to the plasticity of material,realize forming point by point.The technology can speed up the development progress of new products and improve forming quality,and has broad application prospect and market demand.However,due to the low forming accuracy and difficult to popularize,so it is of great significance to optimize and improve the existing progressive forming method in order to enhance the forming precision.Firstly,an orthogonal experiment was carried out on the influence of process parameters on forming quality by using frustum of pyramid as digital model in the article.The differences of quality indexes between lateral and corner of frustum is found,and the basic laws of process parameters affecting forming quality is obtained,which provide optimization for parameter setting of NC incremental forming.Lubrication effects and forming quality of different lubricants were compared via impact test of surface roughness on the forming parts under these lubricant conditions.The results suggest that 46~#machine oil has the best lubrication effect,and average surface roughness is 0.2275?m perpendicular to the feed direction and 0.095?m along the feed direction.Secondly,aiming at the bump phenomena on undersurface in the flat underside parts forming,forming accuracy was improved by optimizing the forming path,and 4forming paths were used to carry out comparative tests.The test results indicate that the isoheight path+multilayer undersurface from inside to outside path can can eliminate undersurface bump and avoid the subsidence on undersurface as well,and the forming efficiency is high.and 3 diverse steps were set for last layer of multilayer undersurface path,it was found that decreasing the step of last layer in multilayer undersurface path advanced both surface quality of part underside and part's geometric accuracy.The forming time of isoheight path+multilayer undersurface from inside to outside path is 43.8%less than that of each layer from inside to outside path.Finally,the reverse bias compensation method was improved,and the forming error of the irregular part was reduced.Using the finite element simulation software conducted numerical simulation to predict the springback amount of each node on the sheet,and then the original digital model was offset reversely,thereby,the part was formed with less geometric error.The maximum normal error of the compensated part is reduced by 42.1%compared with that of the uncompensated part.The study enhanced forming precision and enlarged the application range of reverse bias compensation method.