Papers by Author: Akira Shimokohbe

Abstract: In this paper, a new high-throughput evaluation method for crystallization temperature (Tx) of thin film amorphous alloy is introduced. For measurement of Tx on integrated thin film samples, thermography is used. The order of one hundred Pd-Cu-Si thin film amorphous samples with different composition are integrated on one chip and measured their Tx at once. The validity of measured Tx are examined by comparing with results of differential scanning calorimeter that is a conventional method for Tx measurement, and equilibrium phase diagram of Pd-Si. As results, the difference of two methods is within 10 K and the trend of Tx map has strong correlation with the phase diagram, respectively.

Abstract: The objective of this study is to realize high-speed and high-accuracy electrical discharge machining (EDM) of micro holes using a combination of a conventional EDM machine and a maglev local actuator. In this paper, the conventional EDM machine and the wide-bandwidth, high-precision, 5-DOF controlled maglev local actuator are combined and cooperatively controlled. Then to accelerate the debris ejection from the machined holes, the driving methods of the axial jump and radial vibration of the electrode are discussed. The experimental results show that the maglev local actuator can adjust the gap between the electrode and a workpiece speedily, and the machining speed is improved by 434.2%, compared with conventional EDM machine. Moreover, by the jump and the circular motion of the electrode, the debris ejection can be accelerated, the abnormal electrical discharge can be avoided, and the machining speed also is improved by 580.3%.

Abstract: This paper deals with nanometer positioning in the presence of friction. The object studied is a ball-screw-driven and linear-ball-guide-supported table system. For this system, the friction dominates the resulting performance for micro-motion and the system exhibits microdynamic characteristic which is rather different from macrodynamics. Inherently a controller with high loop-gain is needed to suppress the effect of friction. A PID controller is designed for the table system for step height smaller than 10μm. Experiment and simulation results indicate that the PID controller can provide a sufficiently high-loop gain and effect of friction is suppressed. In point-to-point(PTP) positioning for step heights from 10μm down to 10nm, the positioning error is within ±2 nm and the response dynamics is satisfactory.

Abstract: This paper deals with nanometer positioning in the presence of friction. The object researched is a ball-screw-driven and linear-ball-guide-supported table system. For such system, models that do not account for friction can only be applicable to describe the macrodynamic behavior which is significantly different from the microdynamic one. A PID controller is designed with high-loop gain to suppress the effect of friction. The controller parameters are calculated by pole placement according to macrodynamics, no identification of friction and friction model are necessary. Experiment and simulation results indicate that nanometer positioning can be realized in this system by the controller. In point-to-point (PTP) positioning for step heights from 0.1μm to 1mm, the positioning error is within ±5 nm and the response characteristics are satisfactory.