No abstract

No abstract

A problem has emerged during the end-milling of hardened steels: a high frequency chattering phenomenon. On the other hand, a laser Doppler vibrometer has recently been developed to observe such high frequency vibration phenomena. Therefore, we propose a new method of monitoring chattering in the end-milling of hardened steels using laser Doppler vibrometers. The chattering behaviors of the end-mill shank were measured by two laser Doppler vibrometers from the feed and radial directions at the same time during the end-milling of the hardened steel. The following conclusions were reached: (1) Two kinds of chatter vibrations were confirmed as vibration modes whose frequencies differed during high and low cutting speed conditions. (2) The chatter vibrations at the high cutting speeds clearly differed from regenerative chatter, which has only been researched so far, by accurate measurement of chatter vibration modes.

Seebeck effect, Peltier effect, Thomson effect, electronic thermal conductivity, Hall effect, and Nernst effect are described on the basis of electronic conduction theory, taking account of effective mass anisotropy, nonparabolicity in Ek relation, and temperature dependent band gap. It is shown that the temperature dependence of the band gap does not modify the basic equations for the Seebeck coefficient, thermal conductivity, and Nernst coefficient. In narrow gap semiconductors, existence of minority carriers significantly enhances the electronic thermal conductivity, owing to the multiple carrier transport known as bipolar diffusion. Calibration coefficient £ for the Hall effect (R H ¼ À£=en) is increased by nonparabolicity in the Ek relation. Nernst coefficient gives useful information on scattering properties of the materials.