Shigeki Morii

An attempt at development of a magnetic levitation transport system in vacuum using the mechanism of induced repulsive force

Abstract It is now necessary to make dust-free and contactless transporting systems, for instance, in the field of manufacturing semiconductor memories which are becoming more and integrated. Due to these circumstances, we have developed a basic mechanism of non-contact transport system in vacuum which utilizes the induced repulsive levitation force by alternating magnetic field and the propulsion force of linear motors. In this system, the aluminum transport carrier can be isolated from electromagnets by a stainless steel vacuum tunnel. Levitation of carrier is self-stabilized due to the cross-shape. The system configuration is extremely simple as compared with a conventional active controlled type system. At the present stage of development, the load carrying capacity is about 100 g and the maximum transport velocity is 0.4 m s −1 for a levitation height of about 10 mm and a carrier weight of 300 g.

Vibration Phenomena of Pipes in Fluidized Bed

The quantitative condition starting vibration of pipes by the flow across pipes in fluidized bed was studied experimentally. The occurence of self-excited vibration was observed over the critical flow velocity for a group of pipes, but on the other hand, no self-excited vibration observed for a single pipe. This vibration was found to be fluid elastic vibration. The resonance vibration of pipes caused by karman vortex was not found in fluidized bed even when Re is over 100. From the result of the experiment, the coefficient which determines a critical condition of fluid elastic vibration was found to be close to the value of liquid (water) instead of gas.

Analytical Study on a Dynamical Behavior of Loading Buckets Interacting With Bulk Materials

A new analytical model has been developed to calculate the dynamical behavior of a column on which buckets loading and interacting with bulk materials, such as iron ore and coal with various grain sizes, are set. A set of linear equations of motion was obtained by considering the effective load, the stiffness, and the friction of materials. From the analysis of the equation, the growth of vibration in a column was indicated, which was caused by the cross term of a stiffness matrix because of the interaction between buckets and a material. In addition, bucket speed was found to affect the damping of the vibration through the critical condition Δxω∼vB where Δx is bucket displacement, ω is the characteristic frequency of a column, and v is bucket speed. A simplified characteristic function was obtained for the stability of a system and compared with the results of a laboratory-scale experiment in order to evaluate the analytical model.Copyright