| 摘要 |
In the method for grinding and lapping parallel surfaces, a plurality of workpieces are worked at the same time in one operation, at least one of the workpieces consisting of a piezoelectric material, with the aim of virtually continuously monitoring and/or regulating the progress of the working operation by measuring the resonant frequency of the workpiece made of piezoelectric material. The measurement signal is obtained from characteristic changes in the electrical impedance (modulus, phase) using a high-frequency current whose frequency corresponds, at least at certain times, to the resonant frequency of the workpiece made of piezoelectric material. To eliminate disturbances due to impedance changes which do not stem from resonance phenomena, an impedance measurement is carried out at the same time using a measurement current whose frequency lies outside the range of the resonant frequencies, in order to correct the first measurement signal using the thus obtained second measurement signal.
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