Techniques to control metal particle size in a supported catalyst, where metal particles may be fixed on a support by forming chemical bonds with oxygen atoms in a support, were investigated. The effect of metal particle size on a reaction selectivity was elucidated in terms of the ratio of numbers of the edge and corner atoms to those of the surface total atoms in the metal crystallites.
We propose ultrasonic rotary cutting, in which ultrasonic vibrations are imparted to a rotating cemented carbide cylindrical tool to cut hardened steel to reduce the cutting resistance and improve the properties of the machined surface, and investigate the machining characteristics. Machining experiments were conducted under dry and wet conditions to verify the effects of the ultrasonic vibrations. The surface produced via ultrasonic rotary cutting was intermittently machined, which is characteristic of ultrasonic cutting. In dry machining, the cutting resistance was reduced by approximately 20%, and the surface roughness of the machined surface was reduced by approximately 30% when the cutting speed was below the critical speed. We also demonstrated that the surface roughness was improved by ultrasonic vibrations when the cutting speed was equal to or above the critical speed. A similar tendency was observed in wet machining with longer cutting lengths. We then applied ultrasonic rotary cutting to machine a straight R groove in hardened steel and showed that the cutting resistance was reduced, and the tool engagement was improved.
Use of a tool driven by a spin turning method on a 5 axis turning center has an advantage in suppressing a tool wear in the external turning of hard-to-machine materials. However, it is important not easy to control a radial runout of the tool periphery in the spin turning. In this research, a simple rod shaped tungsten carbide was applied as a rotating tool to the turning of a hardened steel workpiece (HRC63). In addition, on-machine grinding method was proposed as a measure to minimize a radial runout of the rotating tool. With this technique, a well suited rake angle, relief angle or chip breaker profile could be easily given to the tool. In spin turning of the hardened steel with a WC rod tool, roughness value of the worked surface was reduced and tool wear was suppressed in comparison with the turning without tool rotation. In addition, it was shown that correction of the tool runout and forming of the tool rake face could be done on the machine.
In our previous research, precise groove machining could be achieved on a cemented carbide workpiece by utilizing a combined method of EDM and grinding using only a single tool, i.e. a rotary PCD disc tool acting as an electrode for EDM and as a wheel for grinding. In this study, the authors applied this method to forming a 3D shape on a cemented carbide workpiece. Firstly, an EC-PCD disc-shaped tool of φ33.4mm was mounted on a spindle of the EDM machine vertically to the workpiece. And the tool was rotated to make a spherical concave on the workpiece by EDM. The surface roughness of the workpiece was Rz=6.4μm and no electrode wear resulted at all. Secondly, the EDMed surface was ground with the same PCD tool. As a result, the improved surface roughness of Rz=1.7μm was obtained on the workpiece maintaining the precise tool profile and dimension.
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