Cutting Simulation And Experiment Research Of Grooved Insert In Turning Process

In the turning process, unbroken chip is a big problem that must be solved. The common chip breaking methods include changing cutting parameters, adopting new processing technology and using external chip breaking device or grooved inserts. The most common method is using grooved inserts. In order to design the effective groove on the surface of hard alloy blade which can ensure chip breakage, it is usually required to do a large number of cutting experiments after experimentally producing inserts, which is time comsuming and expensive. With development of FEM technology, it is possible to directly simulate the cutting process under different chip breaking groove parameters and cutting parameters. By comparing the chip morphology and breakage process obtained from simulation, it is easier to judge the chip breakage performance of inserts, which avoids repeated cutting tests and reduces the grooved insert designing cost.The corresponding 2D cutting model and the 3D cutting model of turning 45 steel process were established in DEFORM software, including tool model, workpiece model and the tool-workpiece contact relationship. Three kinds of inserts were used to compare the influence of grooved inserts and flat insert on cutting process, in which the geometry parameters of inserts were obtained through reverse engineering principle. The Johnson cook constitutive model and Cockcroft-Latham ductile fracture criterion were chosen for the material model of workpiece. The critical value of ductile fracture was reversely identified by comparing simulation results and experimental tests and was set as 250. Shear friction model was chosen for the friction model between insert and workpiece and friction coefficient was set as 0.6. The relative position of insert and workpiece was consistent with parameters of the turning tests by using back rake angle BR, side rake angle SR and side cutting edge angle SCEA.The serrated chip and chip breaking process were obtained through 2D cutting simulation and the serrated degree of chip increase with the increase in feed rate. Under the same cutting parameters, serrated degree of chip was lager with flat rake insert during cutting process than grooved inserts, while chip breakage was obtained with grooved inserts when the feed rate was large. By further comparison of numerical results under different groove depth and width to depth ratio, it was concluded that chip breakage occurred when the groove depth was 0.15 mm and smaller depth to width ratio.The three-dimensional chip and chip breaking process were obtained through the 3D cutting simulation. By comparing the numerical results and experimental results, it was found that the chip breaking groove is the main reason for chip breaking. Numerical values of the chip flow angle, thickness and width sere consistent with experimental results. The further research of cutting force showed that error of feed force was bigger than 30%, which was related to the numerical wear of back face was smaller than the experimental value. The thrust force and main cutting force could be applied to predict the actual turning process. The analyzing of cutting temperature and tool wear showed that the coating layers have the major influence on temperature and tool wear. Applying 3D FEM model to new grooved insert and new materials, chip breakage, stress/strain distribution and temperature distribution were gained.2D simulation results and 3D simulation results verified the effectiveness of the simulation model in the paper, which provides an effective way for relative research of chip breaking grooved inserts.