Method and apparatus for automatic gas control for a plasma arc torch

摘要

A method and apparatus for controlling a gas supply to a plasma arc torch uses a proportional control solenoid valve positioned adjacent the torch to manipulate the gas flow to the torch, thereby extending electrode life during arc transfer and shutdown. Swirl ring design can be simplified and gas supply and distribution systems become less complicated. The invention also allows manipulation of shield gas flow to reduce divot formation when making interior cuts. The system can be controlled with a digital signal processor utilizing a feedback loop from a sensor.

主权项

1. A method for extending consumable life in a plasma cutting system, the method comprising:
providing a processor to correlate a duration of an operation of an electrode producing a plasma arc in a cutting operation with ramping of a plasma cutting gas and rate of change of a plasma arc current; determining the duration of the cutting operation; and selecting, by the processor:
i) a ramp time of a plasma gas pressure at shutdown based upon the duration of the cutting operation, wherein the ramp time of the plasma gas pressure is increased for a longer duration cutting operation and decreased for a shorter duration cutting operation;ii) a rate of change of the plasma arc current at shutdown based upon the duration of the cutting operation, wherein the rate of change of the plasma arc current is decreased for a longer duration cutting operation and increased for a shorter duration cutting operation; oriii) a combination thereof.