MEASURING METHOD FOR VIBRATION OF WORK PIECE AND APPARATUS THEREFOR

PURPOSE:To correctly detect the vibration of a work piece by detecting the roughness on the surface of the rotating work piece as a signal, and multiplying the detecting signal with a reference signal generated in synchronization with the rotation of the work piece. CONSTITUTION:A detecting output of a first roughness sensor 8 for detecting the roughness in the radial direction of a work piece 7 is inputted to a first multiplier circuit 20, where the output is multiplied with a reference rotation signal applied from a reference rotation signal outputting device 10. The output of the circuit 20 is fed to an operating circuit 21 and operated to obtain the angle and amount of the vibration of the piece 7 in the radial direction. An output of a second roughness detecting sensor 9 for detecting the roughness in the lateral direction of the piece 7 is multiplied with the output of the outputting device 10 in a second multiplier circuit 22 and the result is fed to the circuit 21. The circuit 21 operates the output, thereby obtaining and outputting the angle and amount of the vibration of the piece 7 in the lateral direction.