The main goal of roughing of metal molds is to pursue the material removal rate per unit time and to prepare the geometric contour of the workpiece for semi-finishing. During the cutting process, due to the change of the metal area of the cutting layer, the load on the hardware tool changes, the cutting process is unstable, the wear speed of the metal tool is not uniform, and the quality of the machined surface is degraded.
Many of the CAM software currently developed can maintain a constant cutting condition by the following measures, thereby obtaining good processing quality. Constant cutting load. A constant cutting area and material removal rate are obtained by calculation to balance the cutting load with the tool wear rate to improve tool life and machining quality. Avoid suddenly changing the tool feed direction. Avoid burying the tool in the workpiece. For example, when machining the mold cavity, the tool should be prevented from being inserted vertically into the workpiece. Instead, the inclined lower knife method should be adopted. It is best to use a spiral lower knife to reduce the tool load. When machining the mold core, the tool should be first removed from the workpiece and then horizontal. Cut into the workpiece. Therefore, the semi-finishing strategy should be optimized to ensure a uniform residual machining allowance on the surface of the workpiece after semi-finishing.
The optimization process includes: calculation of the contour after roughing, calculation of the maximum remaining machining allowance, determination of the maximum allowable machining allowance, and profile division of the remaining machining allowance greater than the maximum allowable machining allowance. If the remaining machining allowance value of the partial milling process is taken as the remaining machining allowance for the semi-finishing process, the process can not only remove the uncut corners of the roughing process, but also complete the semi-finishing.