Study Of Experiment And Modeling And Control Under Hard-Dry Cutting

As the hardened steel is a typical scuff -resistance and bad machining material, the traditional manufacture order such as cutting-harden-grinding may be changed by using PCBN tool carry out hard turning, and the weariness strength and productivity of workpiece is improved, and the consumed power is reduced The change rule of cutting force while cutting hardened steel by PCBN tools is an importance factor of cutting property of PCBN tools. Study of the change rule of PCBN tool is used to choose high property lathe, eliminate librations, optimize PCBN tools structure and supervising hard turning process, etc. In this paper, the hard cutting force based on experiment is studied, for characteristic of hard turning, harden cutting model is built, and the harden cutting force is forecasted and controlled. In this paper, the hardened bearing steel GCr15 is selected to be the material,a series of cutting forces experiments were done with AMBORITE DBC50 PCBN tool which was supplied by De Beers Industrial Diamonds with CA6140 lathe. The results indicate that in general, the radial force was the highest, followed by the tangential and axial forces. Cutting forces increased almost linearly with feed rate and depth of cut and width of edge, and the change rule of cutting force affected by cutting speed and rigidity of workpiece is different of ordinary cut theory. The results show that there are critical cutting speed and critical rigidity of workpiece, at the critical value, the cutting force is the lowest. The study of effect factors and change rule of cutting force provide theoretic foundation for PCBN tool structure and edge manufacture, cutting parameter selection and process control, and there is important reference meaning for guide production practice.A new cutting force model coupled with edge forces for hard turning is developed to evaluate cutting forces. The least energy method coupled with the effect of PCBN tool edge is developed to evaluate chip flow angle, at the same time, An new analytical chip flow angle model based on single edge tool and equivalent edge is developed, and the solution of chip flow angle model is provided. The equation about harden turning force is established by studying of edge force and actingmechanism near cutting edge, and the cutting force is forecasted in MATLAB environment. Forecasting results reflect cutting force change trend and consistent with experimental result. It provides reference data for more researching cutting technology system, integrality of machined surface and supervising cutting process.A system for control radial force is designed to application in hard turning process, which based on MATLAB/SIMULIINK. A simple PID control algorithm and PID/PD control algorithm is presented and their performances are compared. The PID/PD control algorithm shows relatively security and stabilization, and it very satisfies the demand for control radial force, so it can avoid librations in machining process and improve turning precision and tool life.