| 摘要 |
PURPOSE:To control tension contactlessly by allowing a wire to pass magnetic field while current is applied between eyeboards, sensing the frequency of vibration generated, and by adjusting rotation of a wire payoff roll upon the sensed amount. CONSTITUTION:Material wires 1 are wound at a certain speed on a takeup roll in the direction of arrow R and pass between eyeboard brushes 2, 3 to further pass between S- and N-poles of a magnet 4. When voltage is impressed between the eyeboard brushes 2, 3 and current flows, a force oriented in the direction F is applied to the material wire 1 through the action of flux in the gap l between the N- and S-poles and the current flowing between the eyeboard 2, 3 (refer to Flemming's left hand law), and vibration is generated on the wire 1. When the tension on the wire 1 and the gap between eyeboards 2, 3 are represented by T and L, respectively, the natural frequency (f) of the wire 1 is given from the formula f=KT<1/2>/L<1/2>, where K is constant. Thus, sensing of the natural frequency of wire should allow determination of the tension on the wire, and thereupon the takeup roller is controlled.
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