Study on Rotation Trajectory Variable Machine Tool Spindle

In recent years, there has been a demand for the popularization of electric vehicles and further efficiency improvement of internal combustion engines for environmental measures. The cylindrical shape of motor cases and cylinders is machined by boring, but the problem is that the cylindrical portion is distorted by the fixing force applied during machining and the roundness is reduced. The solution is to perform non-circular machining in anticipation of distortion, but at present there is no machine tool spindle that can achieve this at high speed. In this research, we have developed a machine tool spindle with a mechanism that can control the rotational speed and position of the tip of the tool in the radial direction using a special motor. Radial position control is performed synchronously with rotational speed control by a real-time controller. By controlling precession and nutation during rotation of the tool tip, it can be applied to non-circular machining of motor cases and cylinders. In this paper, we have developed a prototype machine with the proposed spindle structure and verified its basic performance through experiments under no-load conditions.