Patent ID: 7019248

Claim:
A shielding gas control device incorporated as an element in a gas metal arc welding system that comprises: a) a shielding gas source, b) a gas delivery hose, c) a variable flow-control device having an input and output port, d) a gas metal arc welding wire feeder, e) a gas accumulator, f) a gas solenoid or off-on gas control means having an input and output port, g) a welding torch, and h) a shielding gas nozzle; wherein: i) if said shielding gas source is a high pressure cylinder the output pressure is regulated to less than about 700 kilopascals (101 pounds per square inch), and j) said shielding gas source is in fluid connection with said gas delivery hose whose internal gas pressure is controlled to be greater than about 160 kilopascals (23 pounds per square inch) so as to provide automatic flow compensation for flow restrictions that occur when welding, and k) said variable flow-control device is mounted in, on, or in close proximity to said gas metal arc welding wire feeder and the input port of said variable flow-control device is in fluid connection with the end of said shielding gas delivery hose closest to said gas metal arc welding wire feeder, and l) the output port of said variable flow-control device is in fluid connection with said gas accumulator; said gas accumulator having a predetermined internal volume to provide the desired amount of extra shielding gas at the weld start, and m) said gas accumulator is in fluid connection with the input port of said gas solenoid, and n) the output port of said gas solenoid is in fluid connection with said welding torch, and o) said welding torch is in fluid connection with said shielding gas nozzle; whereas said variable flow-control device: i) regulates the rate of flow of shielding gas into said gas accumulator, and ii) is of a design such that, when welding is stopped and thereby said gas solenoid blocks the flow of the shielding gas, said variable flow-control device allows the gas pressure in said gas accumulator to essentially equalize with the higher gas pressure in said gas delivery hose that exists at that time.