Research On Brittle-Ductile Transition Critical Condition Of Ultrasonic Vibrition Turning Of Optical Glass

The development of science and technology makes the application field of brittle materials be more wider. Optical glass is a kind of typical brittle material. It has the characteristic of low toughness and high brittleness, the machining technology of ultra-precision of optical glass has been limited by its characteristics, high precision glass parts used in optical instrument still adopt conventional and complicated technics of grinding and polishing, The cost is too high and productivity is too low. Compared to conventional technics, it has many advantages to cut brittle materials with ultra-precision machine using sharp diamond tools to aspherical, nonsysmmetric surface, and single point diamond turning by applying ultrasonic vibration to the tool tip is regarded as a perfect technic performed on highly brittle materials by any possibility. The research on the condition of brittle-ductile transition of brittle materials is the basis to realize the machinability of this material and gain high machining surface quality.The background of the development of ultra-precision diamond turning, ductile machining technology of brittle materials and the technology of ultrasonic vibration turning are reviewed firstly. According to the experiment of optical glass indentation, the influence of acting force and material property to the deformation forms are studied. the critical loads and critical indentation depths when ductile-brittle transition of different materials are obtained. According to the scratching experiment, the influence of optical glass material property to the process of ducile-brittle transition under the action of ultrasonic vibration. the critical scratching depths when ductile-brittle transition of different materials are obtained.To facilitate ultrasonic vibration machining, an ultrasonic vibration system has been designed and tested afterwards.At last, Conducted optical glass turning experiment with ultrasonic vibration turning by the lathe of our laboratory and the designed ultrasonic vibration system, machining optical glass in a ductile-regime are realized by controlling...