US 4,375,026 AGranted

Weld quality monitor

AssigneeThe United States of America as represented by the Secretary of the Army

InventorFrank W. Kearney

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Abstract

Weld arc voltage, weld arc current and weld arc travel speed are monitored n a real-time basis during the welding process. Each monitored quantity or parameter is compared directly with a reference value indicative of a high quality weld, and an alarm is activated when a preselected variation in the measured and the reference quantities occurs. The monitored quantities are also used to calculate additional welding parameters, including heat input, weld bead area and cooling rate. These parameters are also compared to ideal reference values in order to control weld quality. The sensors used for measuring the welding parameters are selected so as to provide minimal interference with the welding process. For example, Hall effect transductors are used for current measurements, while a unique opto-electronic noncontacting sensor is used for measuring the weld speed.

Claims10

Dependent claims

A weld quality monitor adapted for use with an electric arc welding machine producing a weld bead, comprising:

voltage sensor means for producing a signal indicative of weld voltage of said arc welding machine;
current sensor means for producing a signal indicative of weld current of said arc welding machine;
speed sensor means for producing a signal indicative of weld speed of said arc welding machine including two noncontacting radiation responsive sensors spaced longitudinally of said weld bead each generating an output signal, and further comprising comparator means responsive to said two output signals for comparing same and producing a signal indicative of temperature difference along said weld bead, wherein said temperature difference is indicative of said weld speed;
reference signal generating means for generating reference signals indicative of optimum weld voltage, optimum weld current and optimum weld speed;
and
comparator means for comparing said reference signals to said weld voltage signal, said weld current signal and said weld speed signal.

3 more elements

Dependencies are inferred from the claim text.