A method of producing an inner spiral grooved tube using a first drawing die using first and second drawing dice and a revolving flyer is provided. The method includes a first twisting-drawing step to form an intermediate twisted tube by reducing a diameter of a linear grooved tube, on an inner surface of which a plurality of straight grooves is formed along with a longitudinal direction, in conjunction with imparting twist to the linear grooved tube by passing the linear grooved tube through the first drawing die and then by revolving the liner grooved tube by wrapping the linear grooved tube around the revolving flyer; and a second twisting-drawing step to form an inner spiral grooved tube by reducing a diameter of the intermediate twisted tube by passing the intermediate twisted tube, which revolves with the revolving flyer, through the second drawing die in conjunction with imparting twist to the intermediate twisted tube.

A method in accordance with the present application includes sending a raw tube from a drum to an unwinding side capstan while the raw tube is rotated around a central axis perpendicular to a winding shaft of the drum by rotating the drum and the unwinding side capstan about the central axis concurrently with unwinding of the raw tube from the drum holding the raw tube, on an inner surface of which multiple straight grooves along a longitudinal direction of the raw tube are formed with an interval in a circumferential direction, in a coil shape, to wind the raw tube around the unwinding side capstan, and drawing in which the unwound raw tube is drawn while the diameter of the raw tube is reduced, and then the raw tube is wound around the drawing side capstan to twist the raw tube and obtain an inner spiral grooved tube.

A method in accordance with the present application includes sending a raw tube from a drum to an unwinding side capstan while the raw tube is rotated around a central axis perpendicular to a winding shaft of the drum by rotating the drum and the unwinding side capstan about the central axis concurrently with unwinding of the raw tube from the drum holding the raw tube, on an inner surface of which multiple straight grooves along a longitudinal direction of the raw tube are formed with an interval in a circumferential direction, in a coil shape, to wind the raw tube around the unwinding side capstan, and drawing in which the unwound raw tube is drawn while the diameter of the raw tube is reduced, and then the raw tube is wound around the drawing side capstan to twist the raw tube and obtain an inner spiral grooved tube.

The present disclosure relates to a method of producing a tube of a duplex stainless steel, in particular a duplex stainless steel suitable for use in fuel injection systems for injection of fuel into the combustion chamber of a combustion engine.

A method for manufacturing a double-wall heat-exchanger tube including an external tube and an internal tube, these tubes being metallic, cylindrical and coaxial. This method includes providing a first tube having an inside diameter d.sub.1int and an outside diameter d.sub.1ext, this first tube being intended to form the external tube, a second tube having an inside diameter dint and an outside diameter d.sub.2ext, this second tube being intended to form the internal tube, and a cylindrical coaxial tubular leaf made from Fe.sup.0 having an inside diameter dint and an outside diameter d.sub.ext, such that 0.15 mm(d1intdext)0.25 mm, 0.15 mm(dintd2ext)0.25 mm, and 10 m(dextdint)200 m.

A method in accordance with the present application includes sending a raw tube from a drum to an unwinding side capstan while the raw tube is rotated around a central axis perpendicular to a winding shaft of the drum by rotating the drum and the unwinding side capstan about the central axis concurrently with unwinding of the raw tube from the drum holding the raw tube, on an inner surface of which multiple straight grooves along a longitudinal direction of the raw tube are formed with an interval in a circumferential direction, in a coil shape, to wind the raw tube around the unwinding side capstan, and drawing in which the unwound raw tube is drawn while the diameter of the raw tube is reduced, and then the raw tube is wound around the drawing side capstan to twist the raw tube and obtain an inner spiral grooved tube.

A method in accordance with the present application includes sending a raw tube from a drum to an unwinding side capstan while the raw tube is rotated around a central axis perpendicular to a winding shaft of the drum by rotating the drum and the unwinding side capstan about the central axis concurrently with unwinding of the raw tube from the drum holding the raw tube, on an inner surface of which multiple straight grooves along a longitudinal direction of the raw tube are formed with an interval in a circumferential direction, in a coil shape, to wind the raw tube around the unwinding side capstan, and drawing in which the unwound raw tube is drawn while the diameter of the raw tube is reduced, and then the raw tube is wound around the drawing side capstan to twist the raw tube and obtain an inner spiral grooved tube.

A method in accordance with the present application includes sending a raw tube from a drum to an unwinding side capstan while the raw tube is rotated around a central axis perpendicular to a winding shaft of the drum by rotating the drum and the unwinding side capstan about the central axis concurrently with unwinding of the raw tube from the drum holding the raw tube, on an inner surface of which multiple straight grooves along a longitudinal direction of the raw tube are formed with an interval in a circumferential direction, in a coil shape, to wind the raw tube around the unwinding side capstan, and drawing in which the unwound raw tube is drawn while the diameter of the raw tube is reduced, and then the raw tube is wound around the drawing side capstan to twist the raw tube and obtain an inner spiral grooved tube.

A method in accordance with the present application includes sending a raw tube from a drum to an unwinding side capstan while the raw tube is rotated around a central axis perpendicular to a winding shaft of the drum by rotating the drum and the unwinding side capstan about the central axis concurrently with unwinding of the raw tube from the drum holding the raw tube, on an inner surface of which multiple straight grooves along a longitudinal direction of the raw tube are formed with an interval in a circumferential direction, in a coil shape, to wind the raw tube around the unwinding side capstan, and drawing in which the unwound raw tube is drawn while the diameter of the raw tube is reduced, and then the raw tube is wound around the drawing side capstan to twist the raw tube and obtain an inner spiral grooved tube.

Systems, devices, and methods are described for drawing materials. In certain embodiments, the material is metal tubing that is hollow along its length. The drawing system may include a first drawing machine that is fixed or stationary and a second drawing machine that moves relative to the first drawing machine. In certain embodiments, the position of the second drawing machine is determined with respect to a desired position, wherein the second drawing machine is downstream from the first drawing machine, and wherein the material is successively drawn by the first and second drawing machines. The drawing speed of the first drawing machine may be adjusted from a first speed to a second speed based on the determined position of the second drawing machine. A programmable logic controller may be provided to control, at least in part, operations of the drawing system.