A Real-Time Forecast On Machined Corner Accuracy And Control System In WEDM

In the corner processing by WEDM, the accuracy of machined corner has always been taken as one of the important properties in WEDM areas. During the processing, the wire electrode is subject to vibration and deformation due to explosive forces and electrostatic forces, making the Wire trace lag behind the NC trace and therefore resulting in errors in machined corners. To improve the accuracy of machined corner, on the one hand increasing the wire electrode tension can decrease the vibration an deformation caused by the above mentioned forces in discharging and thereafter improving the accuracy of machined corner. But there are flaws in this method. On the other hand, a real-time compensation for the error caused by Wire trace behind NC trace is also a feasible method. This method needs real-time detection of machined corner error, thus this paper proposed a real-time forecasting method of machined corner accuracy in WEDM. By detecting the amplitude of wire-electrode vibration and geometrical relation between NC trace and Wire trace, a real-time forecasting system for accuracy of machined corner was set up. With the sampled discharge energy and processing parameters, the system can calculate the wire electrode deformation and the error of machined corner and then display the corner shape of the actual processing on computer, thus achieving the accuracy of real-time processing corner forecast. In order to improve the wire electrode vibration model, we have established experimental database.To verify the accuracy of the real-time forecasting system, we have conducted a series of verification tests of different angles and then compare the experimental results with the system forecast results. It’s showed that different angles impacted the accuracy of the forecast corner shape, particularly in processing the sharp angle there was a comparatively large error and appeared a convex angle phenomenon. The larger error in the machined corner because the small corner angle causes easily repetitive discharges between electrode and workpiece and hence influences both of the radius of erased bulb in one discharge and discharge angle. Finally, after the modification of mathematical models, followed experiments verified the feasibility of the real-time forecasting system.Based on the established WEDM real-time forecasting system, this study proposes several trajectory control methods to raise accuracy of machined corner. Based on the forecasting system, simulations of the actual machining process have been carried out, from which the corrected NC trace can be found. The simulation results help to provide theoretical analysis for the continued studies.