Takashi Nishiguchi

Influence of Study Vibration with Small Amplitude Upon Surface Roughness in Diamond Machining

Summary Vibration with small amplitude and low frequency usually remains in precision diamond machine tools even supported on sir mounts, and inevitably deteriorates surface roughness. Analysing an enveloping curve of feed Harks disturbed by a steady vibration, the surface roughness is estimated as the function of both the ratio of vibration amplitude to geometrical roughness, and the phase shift of the vibration to work rotation. This makes it clear that the roughness can be reduced to 20-30% of the sum of the geometrical roughness and a vibration amplitude at optimal cutting conditions. The analytical results are proved in experiment cutting Al alloy with straight and round tools. The lathe used for the experiment was oscillated at low frequency, small relative amplitude between a tool and a workplece, by the disturbance from the floor. These results show that straight tools are more effective for improving surface roughness than round ones, and provide a surface roughness within 0.01μmRnax during the vibration with 5.8Hz frequency, 0.03μmp-p relative amplitude.

Mechanism of Micro Chip Formation in Diamond Turning of Al-Mg Alloy

Abstract This paper deals with diamond turning experiments of Al-Mg alloy. Variation in tool setting angles using straight tools with sharp cutting edges was performed to study the difference between the machined surface roughness and the theoretical surface roughness estimated with a steady vibration model. Tears with 0.1 μm depth which are generated on the side cutting edge deteriorates the machined surface roughness. The tears are cut off by the trailing end cutting edge at a negative tool setting angle. Burrs generated at the tool setting angle less than -0.1° are another cause for the deteriorating the machined surface roughness.

A Study on Diamond Turning of Al-Mg Alloy — Generation Mechanism of Surface Machined with Worn Tool

Abstract It is well-known that the roughness of machined surfaces in diamond turning can be improved with increase of cutting length in comparison with that of the initial stage. This seems to result from an apparent increase in the wear of the diamond tool with cutting length. In this paper, the effect of diamond tool wear on surface roughness is examined for the turning of an Al-Mg alloy. The following results are obtained. (1) The tears generated on the leading end cutting edge of a straight tool deteriorate the surface roughness at a positive tool setting angle. Conversely, the tear marks decrease as the tool wear grows. (2) The surface roughness has a strong correlation with the cutting edge recession of the worn tool. (3) A residual stock removal is generated at a cutting edge recession of more than 0.3μm. Since uneven residual stock removal with tear marks is cut off by the trailing end cutting edge, the surface roughness is improved after a certain cutting length.

Improvement of Productivity in Aspherical Precision Machining with In-situ Metrology

Summary This paper deals with the development of aspherical machining technology with in-situ metrology using the stylus method for the purpose of improving machining accuracy and reducing machining time. This technique is based on the in-situ measurement of machined geometrical accuracy, which makes it possible to calculate both the deviation of nominal tool diameter from the true one and the tool setting error in tool feed and traverse directions. The machining time can be reduced to a half or one-third with application of this procedure to either aspherical grinding or diamond turning.