Land Infrared Limited

Thomas G Beynon

Ian Hamilton Ridley

Peter J Kirby

Radiation thermometer

Method and apparatus for monitoring the quality of a weld performed with an electrode mounted on an automatically controlled electrode support arm which moves between a rest position and a series of spaced operative positions in each of which a weld operation is performed. The apparatus includes a radiation detector for connection to a monitoring system and a radiation collector attached to the support arm adjacent the electrode and coupled to the radiation detector by optical fibers to receive in use a first level of radiation from electrode and a second level of radiation from the weld zone when the arm is in its operative position. A reference source of radiation is also provided that is located such that when the support arm is in its rest position, the collector receives a third level of radiation from the reference source, whereby the radiation detector generates three signals corresponding to the three levels of radiation impinging on the detector for supply to the monitoring system.

Weld monitoring

A radiation thermometer comprises two radiation detectors for detecting radiation in wavelength bands centered on two different wavelengths .lambda..sub.1,.lambda..sub.2 (where .lambda..sub.1 &gt;.lambda..sub.2) from a rotating body such as a gas turbine motor and for generating first and second signals S.sub.1,&lt;S.sub.2 &gt;respectively related to the radiance profile around said body and the average radiance around said body. A time averaging circuit generates a signal &lt;S.sub.1 &gt;representing an average value of said first signal. A dividing circuit generates a signal related to the ratio of &lt;S.sub.1 &gt;to &lt;S.sub.2 &gt;; and a monitor monitors at least one of said signals, predetermined arithmetic combinations of said signals, and quantities related thereto and provides corresponding output signals.

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Sheffield, United Kingdom

Thomas G Beynon