초록 ▼

A 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 (p.sub.1 or p.sub.n) i

A 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 (p.sub.1 or p.sub.n) is monitored while the torch is operating to detect erosion of the orifice (12) of the nozzle (13), and the voltage U.sub.ne between the electrode (11) and nozzle (13) is monitored, also while the torch is operating, to detect erosion of the electrode (11). A pressure, p.sub.1 or p.sub.n below a reference pressure indicative of a good (un-eroded) nozzle indicates erosion of the orifice (12), and a voltage U.sub.ne above a reference voltage indicative of a good (un-eroded) electrode indicates erosion of the electrode. The pressure measurement and U.sub.ne are compared with appropriate reference values to logically discriminate between wear of the nozzle and wear of the electrode (given that an increase in U.sub.ne due to electrode wear is opposed by a decrease in U.sub.ne 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.

대표청구항 ▼

[ We claim:] [1.] A method for detecting erosion of a nozzle of a plasma arc torch while a plasma jet is being generated by the torch including measuring the pressure of a plasma forming gas supplied to the torch at a location upstream of the nozzle orifice, comparing the measured pressure with a re

[ We claim:] [1.] A method for detecting erosion of a nozzle of a plasma arc torch while a plasma jet is being generated by the torch including measuring the pressure of a plasma forming gas supplied to the torch at a location upstream of the nozzle orifice, comparing the measured pressure with a reference pressure value representative of a non-eroded nozzle, wherein a measured pressure value which is less than said reference value indicates the presence of erosion of the nozzle orifice, and additionally measuring an electrical parameter associated with the plasma jet and comparing the measured electrical parameter with a reference value for detecting a change in length of an arc forming the said plasma, wherein the pressure measurement and comparison with a reference value, and the electrical parameter measurement and comparison with a reference value, are used to distinguish between erosion of the nozzle of the torch and erosion of the electrode of the torch.