FLUX-GATE TRANSDUCER TO CONTROL WELD BUTT Russian patent published in 2012 - IPC G01N27/82 

FIELD: machine building.

SUBSTANCE: proposed transducer comprises welding current power supply 1, magnetic field input device including two current collectors 2, 3 connected in parallel to welding current circuit via electrode 8 and magnetic field registration unit. It is made up of differential flux-gate 9 rigidly connected with welding head 10 and arranged above weld butt. It includes also converter amplifier circuit including the following components connected in parallel: selective amplifier 15 tuned in resonance to frequency (2ω+Ω) (ω - flux-gate excitation frequency, Ω - welding current frequency), phase-shift discriminator 16 with reference voltage generated by another amplifier 17 connected to output of modulator 18. Inputs of the latter are connected to welding current source and master oscillator 13 of frequency 2ω, and smoothing filter 19. Proposed device isolates signal proportional to mismatch between electrode and butt on frequency (2ω+Ω).

EFFECT: higher noise immunity and tracking stability.

1 dwg