Non-destructive evaluation of welded joints of bar wound stator utilizing infrared and thermal methods

Abstract

A method and system for non-destructive evaluation of one or more welds of a stator includes activating the stator welds using an electrical current; recording radiometric thermal images of the welds over time; and analyzing a temperature-time profile of a weld to qualify the weld by one or more of estimating the size of the weld, determining if the temperature of the activated weld has exceeded a predetermined temperature at a predetermined time, or comparing the temperature-time profile of the weld to a reference. The stator may be configured as a bar wound stator. A mask may be applied to the stator to reduce reflections or emissions from non-weld thermal sources.

Description

technical field [0001] The present invention relates to a method and a system for evaluating a welding part of an electric device using a radiation-infrared thermal imaging method. Background technique [0002] Electrical devices such as electric motors and generators having a stator secured within the housing of the motor / generator are well known. A rotor mounted on the shaft is coaxially positioned within the stator and is rotatable about the longitudinal axis of the shaft relative to the stator to transmit the force of the motor. Current flows through the stator windings to form a magnetic field, which causes the rotor and shaft to rotate. [0003] Some stators are generally configured as annular rings and are formed from a stacked thin disk structure or laminations of magnetic steel. Typically, a specific form of copper winding is arranged in the slots of the laminations through which current flows to magnetize the stator assembly and generate the force that causes the...

AI Technical Summary

Problems solved by technology

Visual inspection of welded joints provides a non-destructive method for weld quality inspection, however it is not effective enough for inspection of welds with small surface or cross-sectional areas, nor does visual inspection provide an assessment of the effective size of the heat-affected zone

Functional end of line testing of motor assemblies including bar wound stators provides a general evaluation of the electrical performance of the motor and its windings, however is insufficient to identify specific welds within the stator as having poor electrical performance the direct cause of

Further, the evaluation of the stator welds after end-of-line testing of the stator requires disassembly of the stator to inspect the stator welds, incurring costs associated with disassembly, testing, rework, reassembly and replacement of the stator and motor

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