A new method of machine sculptured surfaces by applying ultrasonic elliptical vibration cutting

Abstract

A new machining method is proposed to obtain sculptured mirror surfaces by applying elliptical vibration cutting. The tool is vibrated elliptically, unlike conventional rotating end mills, and is fed along the sculptured surface while the rotational position of the tool is controlled in accordance with the sculptured surface orientation in the proposed method. In order to realize the sculptured surface machining of hardened die steel with single crystal diamond tool, special components are required, i.e. a vibration system that can generate an arbitrary ultrasonic elliptical vibration in the 3D space, a 4-axis controlled precision machine tool and a special CAM system. The elliptical vibration system, which consists of a 3 DOF ultrasonic vibration tool and a vibration controller, is developed. The vibration tool can generate the arbitrary elliptical vibration at 34.4 kHz by combining two bending vibrations and a longitudinal vibration. The vibration controller is fabricated to keep the elliptical vibration to have a desired lotus in the 3D space. The 4-axis controlled precision machine tool, which consists of an air spindle, precision linear guides, precision ball screws and so on, is developed. Commercial CAM software is utilized and a special post processor is developed to generate tool paths for the 4-axis control machining of sculptured surfaces. The developed ultrasonic elliptical vibration machining system is applied to precision diamond cutting of hardened die steel, and it is confirmed that mirror surface machining with surface roughness of less than 0.28 /spl mu/m Rz can be realized for spherical surface machining of hardened die steel.