Study Of Cutting Force Control In Micro Usm

The ever-increasing demand for miniaturized products has largely motivated the development micro-manufacturing technology. Micro Ultrasonic Machining (MUSM) is capable of machining high aspect-ratio features in chemically inert, nonconductive, hard, brittle materials such as quartz, glass and ceramics. However, the cutting force of MUSM is hard to control because it is highly influenced by the accuracy of the machining system and the massive processing parameters. The machining characteristics and repeatability of micro features machined by USM is greatly influenced by the cutting force variations. Therefore, a constant cutting force control system is essential for stabilizing the machining process and improving machining characteristics of the MUSM.In this paper, the principle of MUSM technology and its development is briefly introduced. After analyzing the factors that affecting the processing stability and the cutting force variations, MUSM cutting force control systems are designed based on the Fuzzy and integral separation PID control algorithm. Experiments results indicate that the integral separation PID control system has the better control effect. Compared with the original control system, the fluctuation range of the cutting force using PID system decreases by60%and the processing efficiency increases by10%.In addition, the processing quality is also significantly improved. Using the new control system, micro-hole, triangle hole, square hole, hexagonal hole and3D cavities were machined by electrodes with corresponding cross sectional shapes.Experiments were also carried out to study the effect of abrasive size, tool diameter, setting cutting force value and tool speed on the machining force under the new control system. Meanwhile, the influence of abrasive size and feed depth of tool on processing efficiency was also studied. It was found that the fluctuation range of the cutting force increases with the increase in cutting force as well as the increase in tool rotating speed. The processing efficiency increases with the increase of abrasive size and is significantly reduced when the tool feed to a certain depth. However, the effect of abrasive size and tool diameter on the fluctuation range of cutting force is not obvious.Under the new control system, the cutting force will not increase too large with the increasing machining depth. Therefore, the tool’s bending or breaking can be prevented.