Off-line feedrate optimization with multiple constraints for corner milling of a cavity

High quality and high efficiency are very important factors in the mold industry and must be considered in machining technology development. Corners are one of the typical features in a cavity mold that can cause low accuracy, tool wear, cutter defection, and vibration. Therefore, off-line feedrate optimization in a corner-milling process has been proposed as a means for avoiding these drawbacks. The corner-milling process could be divided into five stages according to the contact conditions between the cutter and workpiece. An improved chip thickness model based on the actual trajectory of the cutter was presented to predict the movement of the cutter along a curved path. Various feedrate optimizations were presented with varying control parameters. In this paper, three feedrate optimizations were implemented using three control parameters, relative volume, milling force, and cutter deflection, based on the differential element method (DEM). A corner-milling force experiment indicated that the simulation results using a modified milling force model agreed well with actual experimental milling results. Following this, a feedrate optimization with multiple constraints was built, according to a combination of three feedrate optimizations and then consider the acceleration and deceleration limitation. The simulation by using the method in this paper demonstrated that the machining time of rough milling, semi-finish milling, and finish milling could be reduced. In addition, it was found that the resulting milling force varies within a narrow range.