Alloy testing apparatus using eddy current conductivity probe

Abstract

An analog signal produced in response to eddy current probing of a test part is digitized by an analog-to-digital processor and then entered into a microprocessor-based computer. The digitized conductivity test signal is then acted on by a series of processors including a zero suppress processor which determines if the probe is in contact with a part to be tested and has settled in that position so that an accurate conductivity measurement can be made; a data acquisition processor which receives the conductivity test signal and converts it by means of an interpolation routine into a conductivity signal referenced to a predetermined standard, such as % IACS; a limit processor which compares the converted conductivity test signal with conductivity limits retrieved from the computer memory and based on different alloys and tempers, and which causes the results of such comparison to be displayed on 'good/bad' alarms; a peak detection processor which determines that a peak conductivity has been registered after the probe has been disposed in positive contact with the test part; a parts counting processor which responds to the detection of a peak conductivity and in response thereto increments a parts-tested counter; a speech synthesizer processor which is enabled by the peak detection processor and verbally announces, by speech synthesis, the measured peak conductivity; and a recalibration interrupt processor in which the main loop of the programmed microcomputer is interrupted after a predetermined operating interval to disable the test apparatus until it has been recalibrated using a standard of known conductivity.