GB1509096A - Method of and apparatus for arc welding and handling gases generated during said arc welding - Google Patents

Abstract

1509096 Removal of welding smoke SALEN INTERDEVELOP AB 19 Nov 1975 [3 Dec 1974] 47590/75 Heading F4X [Also in Division B3] In arc welding, a smoke extractor fan is driven by a motor energized by transformer welding current. As shown, welding current is conducted to a welding rod holder 16 from a step-down transformer 20 via cables 14, 15 interconnected at a smoke extraction device 21. The latter includes a fan 10 having a driving motor 11 energized by current bled from the welding current line at the interconnection of the cables 14, 15. The transformer 20, the motor 11 and the device 21 are earthed respectively by a cable 23, permanent magnet or electromagnetic feet 13 and, via an earthed workpiece 9, a cable 12. The device 21 includes a suction hose 17 terminating in an interchangeable nozzle comprising, e.g. an elongated slot (for seam welding) or, as shown, a combined inlet and face shield 18. Alternatively, the cable 15 and hose 17 and the holder 16 and nozzle may be combined. Fresh and dust cleaning air may be supplied to the welding zone, via a second hose 24, by a second fan driven separately or by the motor 11. In an alternative construction, the cable 15 may be in the form of a wire mesh hose enclosing both smoke extraction and fresh air passages. The device 21 may incorporate a smoke filter, built-in or attached thereto, and an adjustable outlet nozzle 19 exhausting into the surrounding air or to a central vacuum plant. The energization of the motor 11 may be started and terminated by a welding-currentflow-responsive relay, the termination preferably being delayed; alternatively, the termination may be manual. The fan motor current may be thyristor controlled to be dependent on welding current level, and the fan motor voltage may be rendered constant or limited to protect the fan motor against high voltages occurring under no welding load.