US 6,155,117 A · Edge detection and seam tracking with EMATs

Abstract

A method for detecting the location of an edge, interface, seam or other structure of a workpiece uses one or two electromagnetic acoustic transducers (EMATs) to transmit an ultrasonic wave along the workpiece toward the edge and to receive a reflected wave. The velocity of the wave in the material is used in conjunction with the round trip time-of-flight (TOF) of the transmitted and reflected wave, to calculate the location of the edge. This is done by placing the transducer or transducers at known locations on the workpiece. A surface wave or 90 degree shear wave can be utilized and no contact is needed between the transducer and the surface of the workpiece. Rough and/or dirty surfaces and hostile environments can be accommodated while practicing the invention.

Claims12

Dependent claims

A method for detecting the location of an edge of a workpiece, comprising:

positioning electromagnetic acoustic transducer (EMAT) sensor means at a known location adjacent the workpiece, using the EMAT sensor means to generate an ultrasonic wave along a surface of the workpiece toward the edge, and detecting a reflected ultrasonic wave from the edge;
measuring a round trip time-of-flight (TOF) of the ultrasonic wave to propagate from the EMAT sensor means to the edge, be reflected from the edge, and propagate back to the EMAT sensor means;
and
knowing a velocity of the ultrasonic wave in the workpiece, calculating the distance from the EMAT sensor means to the edge using the TOF and the velocity to determine the location of the edge on the workpiece as a function of the known location of the EMAT sensor means.

1 more element

Dependencies are inferred from the claim text.

Edge detection and seam tracking with EMATs

Life of this patent

Edge detection and seam tracking with EMATs

Life of this patent

Abstract

Claims12