Electric heating – Metal heating – By arc
Patent
1982-07-12
1985-01-22
Envall, Jr., Roy N.
Electric heating
Metal heating
By arc
219 74, 2191372, B23K 916
Patent
active
044954018
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to electric welding and, more particularly, to a torch for gas-shielded arc welding in a narrow deep groove.
2. Background Art
Known in the art is a torch for gas-shielded arc welding in a narrow deep groove, comprising a current contact torch bit featuring an electrode set normally to the welded surface, and two nozzles, one nozzle being placed before and the other after the electrode as the latter travels in relation to the workpiece.
The torch bit, nozzles and groove walls produce an enclosed volume around the electrode, which is filled with shielding gas (cf., French Pat. No. 2,272,781, filed 1976). Such design of a torch provides for good gas shielding only when the electrode is set normally to the workpiece surface. If this torch uses a tilted electrode of an extended free length, the gas shield deteriorates substantially. Moreover, the known torch has its nozzles periodically blocked up by molten metal splatter.
Also known is a torch for gas-shielded arc welding, comprising a current contact torch bit with an electrode and an O-shaped nozzle having double walls, the space between sald walls being communicated with a gas-feeding tube. The top portion of the outer nozzle wall features several horizontally arranged holes. The torch tip and the nozzle are introduced into the groove, the nozzle being positioned above the arc so that the axis of the nozzle and the axis of the tilted electrode intersect at the groove bottom. The arc is shielded by a flow of gas escaping from the nozzle. The gas flow is protected against injecting air intake by carbon dioxide fed from a hole at the top of the nozzle (cf., the USSR Inventor's Certificate No. 566,432, Aug. 13, 1975).
This torch is also insufficiently protected in the arc and weldpool zone because the flow section of the nozzle tends to grow smaller due to sticking of metal drippings. Clusters of splatter can also fall into the weldpool and cause weld defects, the welding process has, therefore, to be stopped periodically to clean the torch. Besides, the nozzle being positioned above the arc, the position of the electrode in the groove in relation to the edges is difficult to watch.
SUMMARY OF THE INVENTION
The object of the invention is to improve a torch for gas-shielded arc welding in a narrow deep groove so that the nozzle is not blocked up with splatter of molten metal and splashes do not fall into the weldpool, thus enhancing the quality of welding and the efficiency of the welding process.
The invention resides in a torch for gas-shielded arc welding in a narrow deep groove which comprises a current contact bit with an electrode and a nozzle for feeding shielding gas to the welding zone, which communicates with a gas-feeding tube and is provided with at least one row of horizontally arranged holes, according to the invention, the nozzle is made as an enclosed chamber shaped as a symmetrical wedge whose sharp edge faces the electrode and is located in one plane with the axis thereof, the side walls and bottom of the chamber having at least one additional row of holes whose axes lie in one plane approximately perpendicular to the walls of the groove.
In order to provide reliable gas shield of the weld zone for girth seams of various curvature it is advisable that the torch be equipped with a ledge secured externally on the chamber wall opposite the sharp edge, the inclination of the ledge in relation to the chamber bottom being variable.
A torch for arc welding in a narrow deep groove, made in accordance with the present invention provides for reliable gas shielding of the arc and weldpool from air, protection of the weldpool from metal splatter, reduction of the shielding gas consumption, observation of the electrode position in relation to the groove walls.
BRIEF DESCRIPTION OF DRAWINGS
The invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 illustrates a general view of a torch for arc welding
REFERENCES:
patent: 3826888 (1974-07-01), Garfield et al.
Bairakovsky Gennady M.
Gorb Vyacheslav F.
Sidorov Evgeny P.
Sidorov Viktor V.
Sukhov Leonid V.
Envall Jr. Roy N.
Nauchno-Proizvodstvennoe Obiedinenie Po Tekhnologii Mashinostroe
Sigda Catherine M.
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