ELECTRODE FOR AIR-ARC GOUGING AND PROCESS FOR MAKING THE SAME

摘要

The invention relates to an electrode for air-arc gouging consisting of a thin-walled carbon steel pipe with basic fluoro-calcic lining, with alumina, cellulose and colloidal graphite additions and to a process for preparing the same. According to the invention, the electrode is made of a thin-walled carbon steel pipe cut at lengths of 400, 500 or 1000 mm, with a diameter of 4 ± 0.08 mm, with an external lining of a homogenized powdery mixture of 26...28% marble, 21...22% fluorspar, 7...8% rutile, 3...3.5% ferrosilicon 45, 3...3.5% alumina, 5...6% cellulose, 5...6% colloidal graphite, 23...29% iron powder, 1% carboxylcellulose and an inorganic binder of liquid sodium silicate in a ratio of 18...20% of the total powdery mass, the percentage being expressed by mass. The process, as claimed by the invention, consists in cutting the thin-walled carbon steel pipes at lengths of 400, 500 or 1000 mm, filling the ends thereof with stearin on a depth of 10 mm by submerging them into melted stearin, removing the stearin excess from the pipe exterior, preparing the basic mixture by batching and homogenizing the constituents, extruding the basic lining on pipes with high pressing pressures of 3.5 at, so as to provide high compactness thereof, the so obtained electrodes being left to dry in air, at 16...25°C, after which they are introduced into a furnace provided with two stearin collectors where, in a first stage, they are maintained for 2.5 h at a temperature of 150 ± 10°C and then are further dried at 250 ± 10°C, for 0.5 h.