A study to investigate contact detection and recognition of the cutting state by means of the acoustic emission (AE) technique in ultra-precision turning is presented. Detection of accurate cutting-edge position was achieved through investigation of the contact limit between the cutting edge and workpiece through use of the AE technique. Moreover, to recognize the cutting state, changes in AE signals instigated by corresponding changes in the cutting condition were monitored. In the contact-detection experiment, contact between the cutting edge and workpiece was detected with a cut depth of 10 nm. Likewise, in the cutting state recognition experiment, AE signal waveforms were observed to demonstrate changes corresponding to changes in the cutting state. These results confirm the feasibility of using the AE technique in cutting state monitoring experiments.
In this study, a method for generating ring intensity distribution at a refraction-type lens with an aspheric element was proposed, and the beam shaping optical element was finished using only ultra-precision cutting. The shape of the optical element and its irradiance pattern were determined from numerical calculation based on its geometrical and physical optics. An ultra-precision lathe was employed to fabricate beam shaping optical elements, and acrylic resin was used as the material. The transmittance of an optical element (a rotationally symmetrical body) with an aspheric surface fabricated using a single-crystal diamond tool was over 98%, and its surface roughness was 9.6 nm Ra. The method enabled the formation of a circular melting zone on a piece of stainless steel with a thickness of 300 m through pulse YAG laser ( ¼ 1:06 m) processing such that the average radius was 610 m and the width was 100-200 m. Circular processing using a ring beam shaping optical element can be realized by single-pulse beam irradiation without beam scanning. #
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