A Smooth Five-axis Transformation Function in CNC System

Five-axis machine tool is the equipment of manufacturing high precision workpieces such as turbine blades in aviation fields. In industrial motion controller, after G-code interpreter recognize and interpret motion commands, before interpolation and trajectory planning, cartesian space instructions are processed via forward transformation to generate cutter location data. In this paper, a smooth five-axis transformation function is proposed and put into practical use in CNC system. Because of the non-linear relationship between axis space and programming space in 5-axis machine, vibrations occur during converting smooth interpolation data into axis motion, actuator space is not smooth. Based on the existing RTCP function, a method of converting interpolated data into axis motion is proposed, to generate continuous velocity in actuator space. By calculating the nonlinear mapping relationship between the axis space and the programming space of the five-axis machine tool, and then calculate the scaling factor, the speed of the axis space is calculated, so as to ensure smooth and continuous speed in axis space. Through actual machining of typical "S" specimens, it is verified the method in this paper can meet surface finish requirements.