Ultrasonically controlled thickness machining

Claim 1

A machining device for controlled thickness machining of a rotating workpiece comprising a cutting tool positioned adjacent to the surface of said workpiece and adapted to be moved into engagement therewith to effect a cutting operation thereof, an ultrasonic transmitter and receiver probe, a hydraulic actuator for positioning said tool and said probe, both said tool and said probe affixed to said actuator, said probe including a housing provided with a fluid entrance port and a fluid exit port for directing controlled fluid flow through said housing, a thin metallic reference strip mounted in said housing exit port, an ultrasonic transmitter-receiver sensor positioned within said probe housing a given distance from the front surface of said workpiece, said exit port with said reference strip being in axial alignment with said sensor, a master pulser-receiver coupled to said probe sensor, said sensor adapted to direct ultrasonic pulses onto said reference strip and said workpiece and receive reflected pulses from said strip and from the front and back surfaces of said workpiece, a slave pulse-receiver, said slave pulse-receiver and said master pulser-receiver adapted to receive said reflected pulses from said probe sensor, a gated first thickness readout unit coupled to said master pulserreceiver for receiving said reflected signals and providing a first output voltage proportional to the distance between said reference strip and the front surfaces of said workpiece, a gated second thickness readout unit coupled to said slave pulsereceiver for receiving said reflected signals and providing a second output voltage proportional to the distance between the front and back surfaces of said workpiece, a first adjustable gain amplifier coupled to the output of said first thickness readout unit, a second adjustable gain amplifier coupled to the output of said second thickness readout unit, means for combining and amplifying the outputs of said first and second amplifiers to provide a summed output signal therefrom, a reference set point signal, means for comparing said summed signal with said set point signal, a servo valve, means for connecting the output of said comparing means to said servo valve, and means for connecting said servo valve to said hydraulic actuator, whereby the machining of said workpiece to a desired thickness is effected.