| 主权项 |
1. An apparatus for monitoring welding in a resistance welder, the resistance welder including first and second electrodes operating on a weld subject, wherein the weld subject includes at least two metal sheets, the two metal sheets disposed between the first and second electrodes, the apparatus comprising:
an ultrasonic probe disposed within the first electrode that generates a burst of acoustic energy that is directed to the weld subject, receives reflected acoustic energy reflected from the weld subject in response to the burst and generates an output signal in response to the reflected acoustic energy, the reflected acoustic energy including a phase inverted acoustic wave reflected from an interface between a liquid zone and a solid portion of the weld subject proximal to the ultrasonic probe; and a computer that receives the output signal, the computer determining a characteristic of the liquid zone that forms during welding based on determining that the output signal includes the phase inverted acoustic wave, the computer determining the characteristic based upon a change in slope of a curve of a time of flight value of the phase inverted acoustic wave, the computer determining a thickness of the liquid zone based upon a distance between a peak of the phase inverted acoustic wave and a peak of a second acoustic wave reflected from an interface between the liquid zone and a solid portion of the metal sheet distal to the ultrasonic probe, wherein the ultrasonic probe receives a third acoustic wave reflected from an interface between the two metal sheets, and wherein the computer monitors a peak of the third acoustic wave over time to evaluate the liquid zone. |
