A Modified GMAW System for Distortion Reduction and Travel Speed Increase through Separate Heat Input and Deposition Rate Control
Agency / Branch:
DOD / NAVY
Gas Metal Arc Welding (GMAW) is the most widely used welding process. It is also the major process used in shipbuilding. In traditional GMAW and all its modifications, the current which melts the wire is the same as the current which heats the base metal. The base metal heat input is thus proportional to the heat which melts the wire. To maintain a minimally acceptable productivity as measured by the wire melting speed, the base metal heat input is typically much greater than the required to control the distortion at an acceptable level. In the modified GMAW proposed to reduce the post-weld distortion and increase the travel speed, a bypass torch is added to an existing GMAW system to bypass part of the current so that the base metal current is smaller than the wire melting current. Further, by controlling the bypass current, the base metal current can be controlled at whatever the desired level is while the melting current can also be controlled at whatever the desired level is. Hence, in the modified GMAW, the productivity is decoupled from the base metal current and the base metal heat input can thus be reduced without affecting the productivity. As a result, reducing heat input thus distortion and increasing travel speed can be achieved simultaneously. The Phase I project will prove the feasibility of the modified GMAW technology for its practical use in welding a typical ship structure material DH36 at flat, horizontal and vertical (down or up) positions.
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ADAPTIVE INTELLIGENT SYSTEMS
2636 Fireside Circle Lexington, KY 40513
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