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Abstract

A method of manufacturing an exhaust gas manifold, that includes metal exhaust pipes and metal flanges for attaching the pipe openings to corresponding internal combustion engine exhaust ports, employs a hybrid MIG welding process to reduce the occurrences of weld spatter being deposited on the pipe surfaces. Additional benefits are a reduction in applied energy, a resultant reduction in heat being applied to the work pieces, less consumption of weld wire, and improved efficiency of making the weld on the inside surface of the flange adjacent to the pipe opening. The hybrid MIG technique involves moving the head of the weld gun so that its weld wire tip is in contact with the closed path joint formed between an aperture in the flange and the pipe opening. Electrical energy is then applied between the weld wire and the work pieces (flange and pipe) for a relatively short period of time that is sufficient to cause the tip of the weld wire to become a molten drop. When the molten weld material is formed, the application of electrical energy is terminated and the weld wire is retracted or withdrawn away from contact to allow the molten wire drop to enter the joint and form the weld. The weld head is then moved with respect to its current location with respect to the work piece and the weld steps are repeated at a predetermined rate at each point along the joint to complete the weld between the pipe opening and the flange.

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First Claim