Plasma torch condition monitoring

• Main Authors: ROGOZINSKI; MACIEJ WLODZIMIERZ, DOOLETTE; ASHLEY GRANT, SANDERS; NICHOLAS A, RAMAKRISHNAN; SUBRAMANIA, COUCH, JR.; RICHARD W
• Format: Patent
• Language: English
• Published: 10.02.1998
• Edition: 6
• Subjects: ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OFNEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMICBEAMS

PCT No. PCT/AU95/00164 Sec. 371 Date Sep. 24, 1996 Sec. 102(e) Date Sep. 24, 1996 PCT Filed Mar. 24, 1995 PCT Pub. No. WO95/26251 PCT Pub. Date Oct. 5, 1995A method and apparatus for monitoring the condition of a plasma arc torch determines whether the nozzle (13) of the torch and an electrode (11) of the torch have suffered any erosion and distinguishes the two. The pressure of a plasma forming gas that is supplied for the torch (p1 or pn) is monitored while the torch is operating to detect erosion of the orifice (12) of the nozzle (13), and the voltage Une between the electrode (11) and nozzle (13) is monitored, also while the torch is operating, to detect erosion of the electrode (11). A pressure, p1 or pn below a reference pressure indicative of a good (un-eroded) nozzle indicates erosion of the orifice (12), and a voltage Une above a reference voltage indicative of a good (un-eroded) electrode indicates erosion of the electrode. The pressure measurement and Une are compared with appropriate reference values to logically discriminate between wear of the nozzle and wear of the electrode (given that an increase in Une due to electrode wear is opposed by a decrease in Une due to nozzle wear). The apparatus and method may provide a binary "good" or "bad" output for the nozzle and electrode, respectively, or may allow for the degree of wear of each to be determined.