Self-Excited Vibrations of Wire-Winding-Type Growing Apparatus for Silicon Single Crystals : Experimental Results and Considerations Relevant to Self-Excited Vibrations

Abstract

In order to minimize the height of a wire-winding-type growing apparatus for silicon single crystals, a wire-rope winding method or a ball-chain winding method is used instead of a stiff shaft pulling a single crystal. When the wire-rope or the ball-chain rotates, amplitudes of the whirling vibration increase gradually with time, and a self-excited vibration occurs. In this paper, the cause of this self-excited vibration is studied experimentally using a model of the wire-winding-type growing equipment for silicon single crystals. The self-excited vibration of a wire-rope occurs when the rotation is above a resonant speed of the wore-rope system, and then only the forward whirling of a wire-rope becomes unstable, independent of the direction of an initially added whirling. On the basis of the experimental results, it is clarified that self-excited vibrations of silicon single crystal growing apparatus are due to an internal friction among element wires of the rope.