Super-precision cylindrical machining

A study has been made of the theory and techniques of turning precise circular components. The possibility of such high accuracy cylindrical machining was analysed according to the principle of making a precise circle. In the study, a form of chucking-type preciison cylindrical machining was developed by combining an insensitive vibration cutting mechanism - using a main spindle system which features an air bearing - with superposition superfinishing. In the first process, the work is chucked on the main spindle and machined using a continuously and systematically pulsating cutting force. In the second process, the work is finished by a newly developed superposition superfinishing device which features equivalent grades of ultrasonic vibration stone. Key points of the techniques are a torsional vibration mode tool for producing accurate, high amplitude vibration of the cutting point, and a contrivance for making accurate movements of the superposition superfinishing device. Machined roundness of 0.1–0.2 μm and surface roughness of 0.03–0.09 μm R_max were obtained with plain carbon steels, stainless steels and hardened steels (H_RC 41, 53, 60). It is considered that turning to roundness ≈ 0, cylindricity ≈ 0 and surface roughness ≈ 0 can be realized by means of this new machining process and its lathe.