Method for producing an at least single-walled tube body from thermoplastic material in an installation , in which at least one tubular preform is discharged from the nozzle head of an extrusion device, the preform is guided vertically downwards, the preform is expanded to a predetermined extent in the transverse direction and to a predetermined shape in an expansion operation by an expanding core arranged centrally in relation to the nozzle head , wherein the preform remains open at the top and bottom, in which, to produce the at least single-walled tube body, which is provided with a corrugated profile or cup-shaped profile, the expanding core has expanding elements provided with a corrugated profile or cup-shaped profile, wherein, by applying a vacuum to the expanding elements, the hot preform takes on the corrugated profile or the cup-shaped profile of the expanding elements , and/or in which, to produce the at least single-walled tube body , an at least two-part hollow mould arranged around the tubular preform is used, wherein the hollow mould has a corrugated profile or a cup-shaped profile, wherein, during the expansion by the expanding device , the preform is pressed against the corrugated profile or the cup-shaped profile of the hollow mould and, as a result of applying a vacuum to the hollow mould and/or compressed air to the expanding core , the preform takes on the shape of the corrugated profile or cup-shaped profile, after the cooling of the at least one preform , the expanding core is moved into a non-expanded state, and in which, after this, the at least single-walled tube body is removed from the installation . in which at least one tubular preform is discharged from the nozzle head of an extrusion device, the preform is guided vertically downwards, the preform is expanded to a predetermined extent in the transverse direction and to a predetermined shape in an expansion operation by an expanding core arranged centrally in relation to the nozzle head , wherein the preform remains open at the top and bottom, in which, to produce the at least single-walled tube body, which is provided with a corrugated profile or cup-shaped profile, the expanding core has expanding elements provided with a corrugated profile or cup-shaped profile, wherein, by applying a vacuum to the expanding elements, the hot preform takes on the corrugated profile or the cup-shaped profile of the expanding elements , and/or in which, to produce the at least single-walled tube body , an at least two-part hollow mould arranged around the tubular preform is used, wherein the hollow mould has a corrugated profile or a cup-shaped profile, wherein, during the expansion by the expanding device , the preform is pressed against the corrugated profile or the cup-shaped profile of the hollow mould and, as a result of applying a vacuum to the hollow mould and/or compressed air to the expanding core , the preform takes on the shape of the corrugated profile or cup-shaped profile, after the cooling of the at least one preform , the expanding core is moved into a non-expanded state, and in which, after this, the at least single-walled tube body is removed from the installation . <EOS>