FIELD: metallurgy.
SUBSTANCE: group of two rectangular plates or slabs welded on edges with continuous longitudinal weld is rolled on hot rolling mills till the rolled metal has the thickness equal to double wall thickness of manufactured pipe; pipes with two longitudinal ribs are obtained from rolled metal by means of expansion; sections of ribs are heated and plastically deformed together with welds relative to longitudinal projections of shaped mandrel introduced to deformed pipe. Possibility of obtaining solid pipes with diameter of up to 3200 mm due to multiple deformation of welds is provided due to the fact that plastic deformation is performed till full contact of rib metal and welds to surface of shaped mandrel. After next deformation the pipe with longitudinal ribs is moved along the mandrel. Ribs formed during plastic deformation and having various height are removed after processing by being cut with a shaped cutter. Mandrel has cross section occupying some part of the circle restricted with a circle with radius equal to radius of inner surface of manufactured pipe. On its cylindrical part there are two similar replaceable projections protruding beyond the limits of the above radius, containing three sections of various height and width. Mandrel can be composite and can contain three housings of certain configuration.
EFFECT: higher accuracy of large-diameter pipes.
5 cl, 20 dwg, 2 ex
