Gas shielding apparatus for welding

A gas shielding apparatus for shielding a weld formed with an electrode of a welding torch assembly with a gaseous substance, said gas shielding apparatus comprising:

• a torch body portion for supporting said electrode, said torch body portion having a first chamber defining a first plenum for producing a primary shield stream of said gaseous substance;
• a shroud body portion positioned outwardly of said torch body portion and having a second chamber defining a second plenum for producing a secondary shield stream of said gaseous substance substantially surrounding said primary shield stream;
• a trailer shield portion extending laterally from said shroud body portion and having a third chamber defining a third plenum for producing a trailer shield stream of said gaseous substance;
• and
• gas distribution means coupled to said first plenum, said second plenum and said third plenum for distributing measured amounts of a gaseous substance from an external supply to said first plenum, said second plenum and said third plenum, said gas distribution means including a flow metering system for transporting said gaseous substance through said first plenum at a first flow rate and through said second plenum at a second flow rate greater than said first flow rate to provide said secondary shield stream with a greater velocity than said primary shield stream and form a gas impermeable barrier between said primary shield stream and said secondary shield stream.

A gas shielding apparatus for shielding a weld formed with an electrode of a welding torch assembly, said gas shielding apparatus comprising:

• a torch body portion adapted for supporting said electrode with a tip of said electrode projecting from said torch body portion, said torch body portion having a primary shield plenum defined therein for producing a primary shield stream;
• a shroud body portion positioned outwardly of said torch body;
• a trailer shield portion extending laterally from said shroud body portion, said trailer shield portion having a trailer shield plenum defined therein for producing a trailer shield stream;
• and
• gas distribution means coupled to said primary shield plenum and said trailer shield plenum for transporting measured amounts of a gaseous substance from an external supply to said primary shield plenum and said trailer shield plenum, said gas distribution means including at least one perforated metering plate configured and positioned to meter the flow of said gaseous substance from said external supply and deliver a first predetermined amount of said gaseous substance to said primary shield plenum and a second predetermined amount of said gaseous substance to said trailer shield plenum.