Patent DE-102010024034-A1 (DE)
Title: Producing a tube, comprises continuously deforming a steel strip to a slit tube, welding the slit of the slit tube subsequent to produce the tube, and subjecting the tube as endless tube to a continuous multi-stage heat-treatment process
Inventor: SCHIESSL RUDOLPH
IPC: B23K31/00
Filed: 2010-06-16
Abstract: The method comprises continuously deforming a steel strip to a slit tube, welding the slit of the slit tube subsequent for the production of the tube, and subjecting the tube as endless tube to a continuous multi-stage heat-treatment process after the welding in the continuous process, where the heat-treatment process is controlled and/or regulated depending on the flow velocity, the tube mass and the alloy of the material of the steel strip. Thermally untreated steel is used as steel strip with an alloy for the formation of a multi-phase material. The method comprises continuously deforming a steel strip to a slit tube, welding the slit of the slit tube subsequent for the production of the tube, and subjecting the tube as endless tube to a continuous multi-stage heat-treatment process after the welding in the continuous process, where the heat-treatment process is controlled and/or regulated depending on the flow velocity, the tube mass and the alloy of the material of the steel strip. Thermally untreated steel is used as steel strip with an alloy for the formation of a multi-phase material. The heat-treatment process is controlled and/or regulated, so that a tube made of multi-phase material develops by the heat-treatment process. The heat-treatment process is carried out in a heat-treatment device (7) having a heating section (7.1) with heating elements, a temperature holding section (7.2) with tempering elements and cooling sections (7.3, 7.4) with cooling elements, where the heating section, the temperature holding section and the cooling sections are controllable, so that the tube is impinged depending on the flow velocity, the tube mass and the alloy of the steel strip with a defined time-dependent temperature progression. The heating elements, the tempering elements and/or the cooling elements are redundant, individually switchable, controlled and/or regulated. The heat-treatment process is carried out in the heat-treatment device with four sections, where the tube is heated in a first section at maximum 930[deg] C, is kept or cooled in a second section at 800[deg] C, is cooled in a third section at 300[deg] C and is cooled in a fourth section at room temperature. The heating elements, the tempering elements and/or the cooling elements are controlled in dependent of the flow velocity, the alloy of the steel strip and/or the required mechanical properties of the tube. The steel strip is used with a nickel- or a copper coating having a maximum thickness of 6 mu m. The tube is guided in a helically coiled manner during the heat-treatment process, and is guided at the outer-circumferential side by a holding device and guiding device with guide rollers, drive rollers and/or guide intermediate elements. The tube is calibrated after the heat-treatment process and is rolled to a measurement. The tube passes through the heat-treatment process as endless tube. Independent claims are included for: (1) a tube; and (2) a device for producing a tube in a continuous process.