Electric heating – Metal heating – Nonatmospheric environment at hot spot
Patent
1980-05-30
1982-09-14
Goldberg, Elliot A.
Electric heating
Metal heating
Nonatmospheric environment at hot spot
219 73, 219136, 228215, B23K 918
Patent
active
043497179
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
TECHNICAL FIELD
This invention relates generally to submerged arc welding and more particularly to dam assemblies for retaining granular flux in position during welding.
BACKGROUND ART
Submerged arc welding with granular flux is a common commercial welding technique. In this technique granular flux is spread in a mound in front of a welding head as the welding head moves across the area of the workpiece being welded. The purpose of the flux is to prevent the welding arc from being exposed to the atmosphere. The electrode in the welding head runs through the flux and the welding arc is fully submerged in the mound of flux. To hold the flux in place while the electrode is passing through the mound, a flux dam is used. A flux dam also aids in forming the mound, reduces the amount of flux required to submerge the welding head and prevents flux from being wasted.
Since a flux dam is positioned adjacent to the welding head, the dam is subjected to high heat from the arc. Typically flux dams overheat, rapidly deteriorate, and burn up in a short period of time. In addition, when the dam begins to deteriorate, its surface becomes irregular and its shape distorts. Flux then can bleed out underneath the dam causing flux to be wasted and possibly leading to exposure of the arc to the atmosphere.
There have been several solutions suggested to the problem of deterioration of flux dams. One technique is the use of a stationary dam that is physically attached to the workpiece. This type of dam rapidly deteriorates and is usually not reused. A second solution has been the use of a traveling dam. A traveling dam moves with the welding head and is water cooled.
Prior patents in this area of technology include U.S. Pat. No. 2,808,500 to Pandjiris issued October 1, 1957; U.S. Pat. No. 2,900,487 to Danhier issued Aug. 18, 1959; and U.S. Pat. No. 2,972,042 to Ashbaker issued Feb. 14, 1961.
Prior solutions to the problem of dam deterioration have never proven to be totally satisfactory. In production situations these dams still deteriorate too rapidly. This requires that the welding process be stopped, the apparatus be disassembled, and the dams replaced.
A further problem is the long setup time required. In production situations the flux dam and the welding head must constantly be positioned on new workpieces and then moved out of the way when the weld is completed. It is desirable to speed up the positioning of the flux dams as much as possible but heretofore flux dams have slowed production because they are awkward to move and must be constantly adjusted.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect the present invention is incorporated into a submerged arc welding apparatus having a platform for a supporting workpiece, a traveling welding head mounted for movement with respect to the platform and a flux dam positionable adjacent to the workpiece for granular flux. The improvement disclosed herein includes an elongate flux dam which is stationary during welding and extends for the length of the weld. The flux dam is supported by a support arm that is pivotally connected to an axle mounted on one side of the platform.
The invention also contemplates a method for welding a workpiece wherein the flux dam is pivoted back and forth with respect to the workpiece along an arcuate path utilizing a support arm that is pivotally connected to a shaft mounted on the welding apparatus.
The present invention solves the problem of flux dam deterioration by using an elongate stationary flux dam and traveling welding heads. The traveling welding heads cause the point of heat generation to continuously move along the length of the workpiece. Thus the point of highest temperature on the adjacent dam continuously moves along the length of the dam from one end of the other. The present invention also solves the problem of flux dam deterioration by cooling the dam using an attached heat exchanger.
The problem of heat distortion is over
REFERENCES:
patent: 2802931 (1957-08-01), Hess
patent: 2808500 (1957-10-01), Daudjiris
patent: 2900487 (1959-08-01), Danhier
patent: 2972042 (1961-02-01), Ashbaker
Lindow Edwin L.
Richards Bradley T.
Caterpillar Tractor Co.
Goldberg Elliot A.
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