METHOD FOR MANUFACTURE OF LIGHT-ALLOY PIPES Russian patent published in 2001 - IPC

FIELD: metal working. SUBSTANCE: method involves heating blank; applying process lubricant; molding tube by providing direct flowing of metal from container under the action of press stamp into annual gap between die and movable needle of constant or variable section, provided with circular holes; separating tube from remainder of billet by breaking through the latter. Ground blank used is provided with drilled through central bore having diameter making 0.24-0.26 of needle diameter and with conical part adjacent to opening end faced to stamp of vertical hydraulic extrusion press during pressing, with central angle of conical part being within the range of 24-26 deg. Pipe is produced in press equipped with broaching system by successively expanding blank and pressing pipe, with mentioned operations being performed in single operating cycle. Expansion operation is effected by means of needle fixed on broaching system and provided with expanding front conical portion with central angle of 29-31 deg. Conical portion is terminated with guiding cylindrical nose of diameter corresponding to that of bore in blank. Prior to expansion operation, process lubricant formed as mixture of flaked graphite and high-viscosity machine oil used in the ratio of (1:5)-(1: 3) is applied to conical part surface. Method allows continuous blanks with central bore of small diameter to be used for producing pipes with constant section which may be provided with succession of widened portions, and provides increase of precision of hot pressing pipes to the level of cold pressing pipes. Moreover, method requires smaller amounts of metal cutting and deforming equipment. EFFECT: reduced consumption of light alloys, decreased labor consumption and reduced product ional costs. 2 dwg