PROCESS FOR MANUFACTURING CORRUGATED PIPES Russian patent published in 1996 - IPC

FIELD: plastic metal working. SUBSTANCE: in accordance with proposed process corrugated pipes are manufactured thanks to deformation of hollow billets. Before corrugating operation hollow billets are subjected to thermal treatment which consists in heating to temperature of transition of structure into single-phase state of dispersive-solidifying alloy, for instance, on nickel base. After holding accelerated cooling of billets with flow of inert gas to temperature 600-650 C is carried out. Next cooling is conducted in protective atmosphere. Then corrugation of billets is performed; billets having wall thickness less than 0.25 mm during one pass, billets having wall thickness exceeding 0.25 mm - during two passes. During one pass deformation is carried out under pressure corresponding to stress within intervals 1,1σ_0,2 and 0,8σ_B, during two passes - within intervals 1,1σ_0,2-0,6σ_B, and 1,1σ_0,2-0,5σ_B., correspondingly. Thermal treatment described above is performed after each deformation. EFFECT: enhanced quality of manufactured corrugated pipes. 1 tbl