Plasma arc torch interlock with disabling control arrangement system

A plasma arc torch system for effecting various metal processes on a workpiece comprising:

• an electrical power source;
• a gas supply source for generating a plasma;
• a torch body including an electrode and an electrically conductive nozzle assembly circumscribing said electrode at a fixed distance therefrom;
• fault detect circuit means for sensing a short circuit between said nozzle assembly and said electrode and disabling said power source in response thereto;
• a cable connected to said torch body, a main electrical conductor within said cable connected at one end to said electrode and at its other end to said power source;
• sensing means within said cable detecting a puncture of the cable sufficient to contact said main conductor and in response to said contact actuating said fault detect circuit means to disable said power source;
• said sensing means includes a continuous, electrically conductive shield comprised of a metal foil embedded in said cable and circumscribing said main conductor and extending the length of said cable;
• and a drain lead in electrical contact with said shield and said nozzle assembly, said sensing means actuated when any electrically conductive object punctures said shield and contacts said main conductor thus establishing a short circuit between said electrode and said nozzle;
• said cable has a generally cylindrical outer jacket of an insulating, pliable plastic material;
• said shield comprises a metal foil embedded in said jacket;
• said drain lead comprises a bare wire extending the length of said cable and in contact with said foil;
• said main conductor contained in an insulated, plastic coating so that said outer jacket must be initially pierced and said coating must be subsequently punctured by an electrically conductive object extending therebetween before said sensing means is actuated.

In a plasma arc torch system including an electrical power source, a torch body having an electrode and an insulated, electrically conductive nozzle assembly circumscribing said electrode at a fixed distance therefrom, a fault detect circuit means including a pilot arc lead connected to the nozzle assembly at one end and at its other end to ground for sensing a short circuit between said nozzle assembly and said electrode and disabling said power source in response to a short detected thereby;

• and a disabling mechanism comprising:
• a cable connected to said torch body, a main electrical conductor within said cable connected at one end to said electrode and at its other end to said power source;
• and
• sensing means within said cable detecting a puncture of the cable sufficient to contact said main conductor and in response to said contact actuating said fault detect circuit means to disable said power source, said sensing including a continuous, electrically conductive shield circumscribing the main conductor and a drain lead in electrical contact with said shield and said pilot arc lead so that a short between the drain lead and main conductor will be sensed and conveyed to said pilot arc lead to actuate said fault detect circuit means.

A plasma arc torch system including an electrical power source, a torch body having an electrode and an electrically conductive nozzle assembly circumscribing said electrode at a fixed distance therefrom, a fault detect circuit means for sensing a short circuit between said nozzle assembly and said electrode and disabling said power source in response to a short detected thereby;

• and a disabling mechanism comprising:
• a cable connected to said torch body, a main electrical conductor within said cable connected at one end to said electrode and at its other end to said power source;
• sensing means within said cable detecting a puncture of the cable sufficient to contact said main conductor and in response to said contact actuating said fault detect circuit means to disable said power source;
• said sensing means includes a continuous, electrically conductive shield embedded in said cable and circumscribing said main conductor and extending the length of said cable;
• a drain lead in electrical contact with said shield and said nozzle assembly, said sensing means actuated when any electrically conductive object punctures said shield and contacts said main conductor to establish a short circuit between said electrode and said nozzle to actuate said fault detect circuit means;
• said cable has a generally cylindrical outer jacket of an insulating, pliable plastic material;
• said shield comprises a metal foil embedded in said jacket;
• said drain lead comprises a bare wire extending the length of said cable and in contact with said foil;
• said main conductor contained in an insulated, plastic coating so that said outer jacket must be initially pierced and said coating must be subsequently punctured by an electrically conductive object extending therebetween before said sensing means is actuated.

A plasma arc torch system for effecting various processes on a metal workpiece comprising

• an electrical power source;
• a gas supply source for generating a plasma;
• a torch body including an electrode connected to said main power source and an insulated, electrically conductive nozzle assembly circumscribing said electrode;
• fault detect circuit means for sensing a short circuit between said nozzle assembly and said electrode and disabling said power source in response thereto;
• a pilot arc contact wire in electrical contact with said nozzle assembly, a pilot arc switch, a pilot arc lead connected to said fault detect circuit means and said pilot arc switch, a pilot arc lead connected to said fault detect circuit means and said pilot arc switch, a main power switch between said electrode and said power source, said fault detect circuit means actuated when said pilot arc switch and said main power switch are actuated to establish a pilot arc between said nozzle assembly and said electrode a predetermined voltage measure relative to said pilot arc lead is exceeded;
• said nozzle assembly includes a generally cylindrical nozzle sleeve member within said torch body and a cup shaped tip member adapted to be threadingly secured to said nozzle body, as a pilot arc wire contact;
• a continuity lead within said torch body, a continuous circuit source of electrical power connected to said continuity lead, said cup shaped tip member when properly fastened to said body establishing an electrical connection therethrough from said continuity lead to said drain lead and continuity circuit means measuring continuity between said continuity lead and said pilot arc wire contact so that in response to a lack of continuity therebetween said main power source is disabled whereby said torch is rendered safe at all times.

A plasma arc torch system for effecting various processes on a metal workpiece comprising

• an electrical power source;
• a gas supply source for generating a plasma;
• a torch body including an electrode connected to said main power source and an insulated, electrically conductive nozzle assembly circumscribing said electrode;
• fault detect circuit means for sensing a short circuit between said nozzle assembly and said electrode and disabling said power source in response thereto;
• rectifying means to generate a series of d.c. electrical pulses applied to said electrode;
• switch means to initiate a pilot arc between said nozzle and said electrode during start-up of said torch system which is transferred to said workpiece as a plasma arc during normal operation of said plasma arc torch system;
• triggering means to vary the phase angle and current of said pulses from one value when said pilot arc is established to a second value when said plasma arc is established;
• means to sense the current in each electrical pulse during the formation of a pilot arc and in response to a pulse exceeding a predetermined current value, at the moment said pilot arc is transferred to said plasma arc, to actuate said triggering means to reduce the phase angle of said pilot arc pulses.