Electrode assembly for arc welding

Abstract

The disclosed technology relates generally to welding technologies and more particularly to electrode assemblies for arc welding, e.g., submerged arc welding. In one aspect, an electrode assembly for submerged arc welding (SAW), the electrode assembly comprising a head portion comprising a contact nozzle and an extension portion removably and serially attached to the contact nozzle and disposed to be proximal to an arcing tip of a consumable electrode relative to the contact nozzle. The extension portion comprises a ceramic sleeve configured to slidingly feed the consumable electrode therethrough, and a pair of metallic sheaths covering opposing ends of the ceramic sleeve.

1 . An electrode assembly for submerged arc welding (SAW), the electrode assembly comprising:
 a head portion comprising a contact nozzle; and   an extension portion removably and serially attached to the contact nozzle and disposed to be proximal to an arcing tip of a consumable electrode relative to the contact nozzle, the extension portion comprising:
 a ceramic sleeve configured to slidingly feed the consumable electrode therethrough, and 
 a pair of metallic sheaths covering opposing ends of the ceramic sleeve. 
   
     
     
         2 . The electrode assembly of  claim 1 , configured such that, during SAW with the consumable electrode inserted therethrough, a ratio between an electrical stick-out distance, measured between the contact tip disposed at an end of the head portion and the arcing tip of the consumable electrode, and a diameter of the consumable electrode exceeds 30. 
     
     
         3 . The electrode assembly of  claim 1 , wherein the electrical stick-out distance exceeds 125 mm. 
     
     
         4 . The electrode assembly of  claim 1 , wherein a gap between the ceramic sleeve and each of the metallic sheaths is filled with a sealant such that the ceramic sleeve and the metallic sheaths are immobilized with respect to each other. 
     
     
         5 . (canceled) 
     
     
         6 . The electrode assembly of  claim 4 , wherein the ceramic sleeve is brazed onto the metallic sheaths such that the sealant comprises a brazing metal. 
     
     
         7 . (canceled) 
     
     
         8 . The electrode assembly of  claim 1 , wherein the metallic sheaths at the opposing ends are separated in a lengthwise direction of the ceramic sleeve by a separation distance, thereby exposing the ceramic sleeve such that electrical shorting is substantially prevented between the metallic sheaths at an electrical bias exceeding 30V. 
     
     
         9 . The electrode assembly of  claim 1 , wherein the extension portion is mechanically coupled to the contact nozzle through one of the metallic sheaths distal to the arcing tip relative to the contact nozzle. 
     
     
         10 . (canceled) 
     
     
         11 . An extension portion configured for a submerged arc welding electrode assembly, the extension portion comprising:
 a ceramic sleeve configured to surround a consumable electrode, and   a pair of metallic sheaths covering opposing ends of the ceramic sleeve,   wherein the extension portion is configured to be arranged serially with a head portion of the submerged arc welding electrode assembly.   
     
     
         12 . The extension portion of  claim 11 , wherein the extension portion is configured such that during welding with the consumable electrode inserted therethrough, a ratio between an electrical stick-out distance, measured between a contact tip portion disposed at an end of the head portion and an arcing tip of the consumable electrode, and the diameter of the electrode exceeds 30. 
     
     
         13 . The extension portion of  claim 11 , wherein a gap between the ceramic sleeve and each of the metallic sheaths is filled with a sealant such that the ceramic sleeve and the metallic sheaths are immobilized with respect to each other. 
     
     
         14 . The extension portion of  claim 11 , wherein the ceramic sleeve comprises a straight cylindrical portion and wherein each of the metallic sheaths comprises a correspondingly straight cylindrical inner wall portion surrounding the straight cylindrical portion of the ceramic sleeve 
     
     
         15 . The extension portion of  claim 11 , wherein the ceramic sleeve comprises a tapered portion formed at one or both ends thereof, and wherein each of the metallic sheaths comprises a correspondingly tapered cylindrical inner wall portion surrounding the tapered portion of the ceramic sleeve. 
     
     
         16 . The extension portion of  claim 15 , wherein the extension portion comprises the tapered portion at the end closer to the arcing tip, in which a width thereof decreases towards the arcing tip, wherein the tapered portion is configured such that tangents of an exterior surface of the extension portion form a triangle or a cone having an angle of apex that is less than 16 degrees. 
     
     
         17 . The extension portion of  claim 16 , wherein the extension portion has a shape, length and a lateral dimension such that the extension portion is configured to not contact a sidewall of a triangular groove having a depth exceeding 4 inches and having an angle of an apex that is less than 16 degrees while the tip of the consumable electrode contacts the apex. 
     
     
         18 . The extension portion of  claim 11 , wherein an inner cavity of the ceramic sleeve has one or both end portions that are flared to have a diameter greater than that of a middle portion of the inner cavity. 
     
     
         19 . The extension portion of  claim 11 , wherein an outer edge of one or both ends of the ceramic sleeve is rounded. 
     
     
         20 . The extension portion of  claim 11 , wherein the metallic sheath formed at an end closer to a stick-out portion of the consumable electrode has an outer edge that is rounded. 
     
     
         21 . (canceled) 
     
     
         22 . The extension portion of  claim 11 , wherein the ceramic sleeve is formed of a material selected from the group consisting of silicon nitride, magnesia-stabilized zirconia, yttria-stabilized zirconia, silicon carbide, magnesium oxide, alumina or a zirconia-toughened alumina. 
     
     
         23 . An electrode assembly for submerged arc welding (SAW), comprising:
 a head portion and an extension portion that are arranged serially to feed a consumable electrode therethrough such that, during SAW, the head portion is disposed to be distal to an arcing tip of the consumable electrode and the extension portion is disposed to be proximal to the arcing tip of the consumable electrode,   wherein the head portion includes a contact tip configured to electrically contact the consumable electrode to deliver power thereto, and   wherein the extension portion comprises:
 a ceramic sleeve configured to sliding feed the consumable electrode therethrough after passing through the contact tip; and 
 a pair of metallic sheaths covering opposing ends of the ceramic sleeve. 
   
     
     
         24 . The electrode assembly of  claim 23  wherein a gap between the ceramic sleeve and each of the metallic sheaths is filled with a sealant such that the ceramic sleeve and the metallic sheaths are immobilized with respect to each other. 
     
     
         25 . The electrode assembly of  claim 23 , wherein the extension portion is mechanically coupled to the contact tip through one of the metallic sheaths distal to the arcing tip relative to the contact tip. 
     
     
         26 . The electrode assembly of  claim 23  wherein the ceramic sleeve comprises a single piece of a ceramic material selected from the group consisting of silicon nitride, magnesia-stabilized zirconia, yttria-stabilized zirconia, silicon carbide, magnesium oxide, alumina or a zirconia-toughened alumina.