Akira Hosokawa

A017 Thermal Dressing of Metal Bonded Diamond Wheel by Nd:YAG Laser : Optimization of air-jet irradiation angle

In this study, a pulsed Nd:YAG laser beam is used as a non-contact thermal dressing tool for a metal bonded diamond wheel. In order to efficiently remove the bond material, it is necessary to direct air on the spot irradiated by the laser so as to blow away the molten binder. The new integrated laser-air head makes it possible to make an appropriate chip pocket depth with less residual re-solidification layer of bond material. The grinding experiments of the hot-pressed SiC reveals that the laser-dressed wheel has somewhat better grinding performance than the conventional rotary dressed wheel.

Studies on High-Speed Milling with Small Ball End Mill

A new three-color infrared radiation pyrometer using an optical fiber is developed for measuring cutting temperature in high speed machining by small ball end mill. The high speed air spindle unit is adopted to the ordinary milling machine so that the maximum spindle revolution of 40000rpm is attainable. The ball radius of the carbide cutter is 3mm and the side cutting of carbon steel with ballnose is executed without cutting fluid. Cutting temperature distribution along the ball-nosed cutting-edge is measured. The influences of spindle rotational speed, radial depth of cut and feed per tooth on the temperature distribution at the flank face are examined. The maximum temperature of peripheral cutting edge about 700°C is obtained even at the rotation angle of 180° after cutting, and it drops along the ballnose toward the ball tip. Relatively large temperature gradient arises along the ball cutting-edge at higher spindle revolution because cutting speed depends on the local tool radius. Depth of cut and feed per tooth, at the same time, affect the overall temperature at the ball cutting edges. The cooling characteristics in air cutting reveals that the temperature difference during one cycle of intermittent cutting increases as spindle speed decreases. The relationship between the peripheral cutting speed and the tool temperature varies from tool shank to ball tip because the interactions between cutting edge and workpiece change along the ballnose.