Research On Chip-Breaking Capability And Machining Chip-Breaking Predictive System With 3-D Complicated Grooved Inserts In Turning

Metal cutting, the conventional method of mechanical machining, develops toward high-speediness, high precision and automation. If chips are not broken, the metal cutting processes will not carry out efficiently and smoothly, especially in automated machining systems. So, a great deal of research has been devoted in understanding the mechanism of chip-control. Especially chip-breaking grooves are the focus because chip breakage depends on them. 3-D complicated groove is perfected than those past grooves. Correspondingly its chip-breaking capability is systematically studied and its chip-breaking predictive system is developed in this dissertation. Some researching results of theory significance and application value have been drawn.Firstly, the domestic and oversea research status of chip-breaking technology is analyzed. 3-D complicated groove is decomposed into four typical chip-breaking units according as geometry elements. Chip flow angle model is established on the basis of Colwell principle. Through predicting chip flow direction, analyzing the relationships between each chip-breaking units and chips, the model of equivalent chip-breaking groove width is built and chip curl radius can be predicted.Secondly, the effect of 3-D complicated groove on chip section profile is found based on cutting experiments. Through analyzing the effect of 3-D complicated groove on chip thickness, studying varying rules of chip width and chip section profile, the model of chip section profile coefficient is established. Researching results show that variation of equivalent chip thickness will change the position of chip neutral plane. Then it causes the change of coefficient of chip section profile. It is the main reason of chip breakage.Thirdly, the chip-breaking limits of 3-D complicated groove are proposed and the models of them are established. Using searching-points analytical method, Chip-breaking curves are simulated by analyzing the chip-breaking processes in steel turning with two 3-D complicated grooved inserts, TNMG160408-QM and TNMG160404-HK5. Cutting experiments are performed to validate the simulated results. The testing results show the chip-breaking predictive models are reasonable and reliable.Fourthly, the chip-breaking mechanism is studied when cutting aluminum alloy with PCD tool. The chip breakers with different parameters are designed for chip breakage. The formulation of chip curl radius is constructed through analyzing the chips subject to chip breakers. The predictive models of the critical feed rate and the critical depth of cut are developed based on chip-breaking conditions. Chip fracture strain is obtained by analyzing the machining capability of aluminum alloy LY12. In order to verify the model, PCD tool with chip breakers is used to cut LY12. Chip -breaking areas are compared with those obtained from the predictive model. Results show the model is reasonable.Lastly, the web-based machining chip-breaking predictive system of 3-D complicated groove is developed. The structure and functions of predictive system are designed according to the theory of experts system. On the basis of chip-breaking predictive models, chip-breaking limits are presented to estimate chip broken or not. Depending on the web-based client-server programming technology, multiple users can access the system and predict chip breakage of 3-D complicated grooved insert anywhere on the internet/intranet at the same time. Compared the predictive results with the experimental results, the system can predict chip breakage well.