Energy Saving in Five-Axis Machine Tools Using Synchronous and Contouring Control and Verification by Machining Experiment

This paper deals with a controller design for five-axis machine tools, which typically consist of three translational and two rotary axes. The flexibility to change the relative orientation between a tool and the workpiece in a five-axis machine tool offers many advantages over conventional 3-D machining. Because machine tools operate around the clock in industrial applications all over the world, there is a requirement not only for high-speed and high-precision operation but also for reduced energy consumption. This paper presents a novel controller design that aims to reduce energy consumption in five-axis machine tools. The proposed design is based on a contouring controller that has been proposed for use in high-precision machining in machine tool systems. The design also takes into consideration the relative orientation error between a tool and the workpiece in five-axis machining. The synchronous controller is used to reduce synchronous error between two parallel actuators, which is a cause of significant mechanical damage. The contouring control system has a degree of freedom (DOF) in the direction tangential to the desired contour curve because this directional error does not directly affect the contouring performance, and hence, this DOF is employed for consumed energy reduction in this study. The experimental results of feed drive motion (without machining) demonstrate the effectiveness of the proposed controller, which reduces energy consumption by 13.2%. In addition, after applying to the machining experiment, the effectiveness was increased to 27.9% because of largely reducing the control input variance caused by the machining task.