Seiko Seiki Kabushiki Kaisha

Hideki Omori

Hiroyuki Kihara

Okikazu Kuwahara

A device for detecting a bending magnitude of a rotary shaft comprises a first pair of coils spaced from and facing the outer surface of a shaft and having an inductance value, and a second pair of coils spaced from and facing the outer surface of the shaft and connected in series to the first pair of coils at respective nodal points. The second pair of coils has an inductance value different from the inductance value of the first pair of coils. A pair of high frequency oscillators applies a high frequency voltage across the first and second pairs of coils to generate at each of the nodal points an output signal corresponding to a bending magnitude of the shaft, each output signal having a constant linearity characteristic resulting from the difference in inductance value between the first and second pairs of coils. An amplifier is connected to each of the nodal points for amplifying the output signals from the nodal points. A synchronizing signal generator generates a synchronization signal, and a synchronizing detector is connected to each amplifier for detecting the amplified output signal from the amplifier based on the synchronization signal. A low-pass filter is connected to each of the synchronizing detectors for cutting a high frequency component from the output signal detected by the synchronizing detector and producing an output signal having a constant linearity characteristic.

Device for detecting the bending magnitude of a shaft

The control system is provided in a grinding machine composed of an axially movable rotational shaft having a grinding tool and being supported magnetically by electromagnets. The control system includes a target position modifying controller for modifying or shifting a reference target levitating position of the rotational shaft in a retreating direction away from a workpiece reaches a predetermined amount. The control system further includes a rigidity modifying controller operative during quick feed operation of the rotational shaft for making a rigidity of the rotational shaft lower than that in the grinding operation by adjusting exciting currents of the electromagnets. The control system still further includes a dressing controller operative during dressing of a new grinding tool for detecting that the grinding tool begins to touch a dresser and for judging that the dressing is completed just when an arithmetic value calculated based on the detection reaches a predetermined value.

Control system of grinding machine

A control system is provided in a grinding machine composed of an axially movable rotational shaft having a grinding tool and being supported magnetically by electromagnets. The control system includes a target position modifying controller for modifying or shifting a reference target levitating position of the rotational shaft in a retreating direction away from a workpiece reaches a predetermined amount. The control system further includes a rigidity modifying controller operative during quick feed operation of the rotational shaft for making a rigidity of the rotational shaft lower than that in the grinding operation by adjusting exciting currents of the electromagnets. The control system still further includes a dressing controller operative during dressing of a new grinding tool for detecting that the grinding tool begins to touch a dresser and for judging that the dressing is completed just when an arithmetic value calculated based on the detection reaches a predetermined value.

A grinder with a deflection sensor for controlling the grinding work conditions based on an amount of deflection of a grinding shaft occurring in the normal direction relative to the grinding shaft which is detected by measuring inductance with the deflection sensor. Based on a deflection of the grinding shaft detected during grinding work, the feed of the grinder is controlled, and the sharpness of the grinder is determined based on changes of the detected deflection amount during spark-out, moreover an error in the signal from the deflection detector caused by a thermal change can be compensated, whereby grinding work is carried out under an optimum condition, and the grinding accuracy and efficiency are improved.

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Narashino, Japan

Hideki Omori