| 摘要 |
PURPOSE:To improve the measurement accuracy of the fine unbalance quantity of a body to be measured and to fix a main bearing body to a housing by measuring the unbalance quantity of the body to be measured based on a deviation of a control current flowing through a magnetic bearing from a steady value. CONSTITUTION:Gaps between a main shaft 1 and detection parts 5a-5c vary owing to unbalance accompanying the rotation of the body 4 to be measured; and the quantity of displacement of the main shaft 1 is detected by the detection parts 5a and 5b and inputted as displacement signals to a control circuit 12 and the up/down oscillation is detected by the detection part 5c and inputted to the circuit 12 similarly. Then distributors 14a and 14b distribute control currents which induce attractive force to the magnetic bearings 6a-6c, the main shaft 1 is held neutral at any time with the attractive force of the magnetic bearings 6a-6c. At this time, the quantity of unbalance of the body 4 to be measured is found by displacement current measuring instruments 15a and 15b and an adder 16 and displayed on a display part 17. Consequently, the measurement accuracy of the fine unbalance quantity in a balance test of the body to be measured is improved greatly and the main bearing body can be fixed directly to the housing.
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