METHOD FOR FLASH-BUTT WELDING THIN-WALLED CASINGS

The invention is directed to removing microdefects from and increasing the quality of a welded joint. The above-mentioned technical result is achieved in that the method for flash-butt welding especially thin-walled, preferably flexible casings comprises the preparation of the abutting end faces, butt-mounting said casings on centring apparatuses and combined melting under conditions in which the gap provided between the mutually adjoining surfaces which is sufficient for producing welding is initially maintained, wherein deformation of microprojections is performed on each of the abutting casings by means of plastic deformation along the surface being welded of the end face with shortening thereof by a value of ? h = a d + b d2/ R by means of rollers with an irregularity parameter of Ra =0.16 µm, the deformed metal is moved along the end face of the semi-finished product to the side of the inner surface and an inner annular belt extension is formed thereon which has a width within the range of 0.5 - 1.5 d and a thickness within the range of 0.2 - 0.5 d, the abutting casings are mounted in a centring (in relation to the outer diameter) device and the abutting casings are spot-welded in advance along the perimeter in the plane of the seam, with a stepwise movement of the electrode of 20 - 50 d, wherein the main continuous welding is performed in such a way as to form a weld penetration zone with a width of 4-6 d, wherein heat elimination in the parts being welded begins to be achieved at a distance which is no more than 6 - 8 d from the plane of the seam, where d is the thickness of the wall of the casing being welded, in mm; ? and b are the constant coefficients for the range d/R = 0.003÷0.01 which are equal to 0.1 - 0.3 and 0.075 - 0.375, respectively; R is the radius of the casing being welded, in mm. La présente invention vise à éliminer les micro-défauts et à améliorer la qualité d'un joint soudé. Pour ce faire, le procédé de soudage en bout par étincelage, en particulier de tubes à parois minces de préférence flexibles, consiste à préparer les extrémités placées bout à bout, à placer les tubes bout à bout sur des appareils de centrage tout en produisant une fusion, l'espace séparant les surfaces adjacentes et permettant de réaliser le soudage étant préalablement maintenu. Selon cette invention, une déformation de micro-protubérances est effectuée par déformation plastique sur chacun des tubes mis bout à bout le long de la surface à souder de l'extrémi