Abstract: To provide a process for producing a thermal sprayed, metal plated steel tube having a metal layer substantially uniform and favorable over the whole surface in a highly productive manner. [Means for solving] A process for producing a metal tube comprising continuously forming a metal plate composed of a first component into a tubular shape and continuously welding its butted ends to form the metal tube, wherein, after the continuous welding, a metal layer composed of a second component which is different from the first component is formed by thermal spraying directly over the surface of the metal tube, the metal layer having no discontinuities in the circumferential and lengthwise directions. Especially it is preferred that the process comprises a process step of making the thickness distribution of the metal layer more uniform after formation of the thermal sprayed metal layer over the external surface.

Abstract: Provided is a method of manufacturing a battery having an electrode module including: a positive plate having a cathode collector portion formed by attaching a lead member to a cathode substrate made of a foamed metal plate; and a cathode collector plate welded to the cathode collector portion. The method includes: a pre-welding positive plate forming process of forming a pre-welding positive plate, which is the positive plate before welding, such that the pre-welding positive plate has a projection projecting from a pre-welding cathode collector portion, which is the cathode collector portion before welding; and a welding process of melting a pre-welding cathode collector plate to weld it to the projection. In the pre-welding positive plate forming process, the projection is formed into such a shape that the condition that S?1.3W is satisfied, where W and S represent the width and the circumferential length of the projection, respectively.

Abstract: A container tank body and a processing method thereof are provided. The tank body is arranged in a frame with a square-shaped cross section and comprises a cylindrical main body part, end enclosures arranged at two ends of the cylindrical main body part and fixedly connected with the cylindrical main body part, and a tank body strengthening device. The cylindrical main body part comprises a plurality of parts with an arc-shaped cross section, the parts are formed by bending and welding a same panel, and the cross section of the cylindrical main body part of the tank body is generally arranged between the square-shaped cross section of the frame and an inscribed circle of the square-shaped cross section. A tank container comprising the tank body is also disclosed.

Abstract: A method for manufacturing a clad material composed of a core material and one or more skin materials which are superposed on either one or both faces of the core material, includes a clad material preparation process where an ingot for core material is manufactured by dissolving and casting a metal, and an ingot for skin material is manufactured by dissolving and casting a different metal for skin material, without hot rolling. The ingot for skin material is superposed as a skin material at a predetermined position of either one or both faces of the ingot for core material and the superposed material is hot-rolled to manufacture a clad material.

Abstract: Methods for bonding a porous tantalum structure to a substrate are provided. The method includes placing a compressible or porous interlayer between a porous tantalum structure and a cobalt or cobalt-chromium substrate to form an assembly. The interlayer comprising a metal or metal alloy that has solid state solubility with both the substrate and the porous tantalum structure. Heat and pressure are applied to the assembly to achieve solid state diffusion between the substrate and the interlayer and the between the porous tantalum structure and the interlayer.

Abstract: A method for production of spacers to hold at least a number of elongated fuel rods (5) in a fuel unit (20) for placement in a re-actor (1) is described. The method comprises the steps of providing at least two spacers (30), to provide a set of mandrels (40) comprising a number of mandrels (42), to arrange at least two spacers (30) with one on top of the other on the set of mandrels (40), and to heat treat the spacers (30) when they are arranged on the set of mandrels (40) so that the cells (31) in the spacers (30) adapts to the mandrels (42).

Abstract: Drum for a washer and a dryer including a cylindrical metal body part, reduced parts at opposite end parts of the body part, each having a diameter smaller than a diameter of the body part, and bent parts each having a folded edge of the reduced part, thereby providing a drum that can prevent occurrence of vibration and noise.

Abstract: A metal sheet composite comprising an outer metal sheet having a flange which is folded over around a flanging edge; an inner metal sheet which forms a joint with the flange; and a welding or soldering seam which is produced on or in the joint and fixedly connects the metal sheets to each other. A method for joining metal sheets and a device for flanging and welding or soldering are also disclosed. The device includes: a tool head; a flanging member, arranged on the tool head, for roll-flanging or slide-flanging; and a welding or soldering tool arranged on the tool head, wherein the flanging member and the welding or soldering tool are arranged such that the flanging member forms a pressing means for a welding or soldering process which can be performed using the welding or soldering tool.

Abstract: There is provided a method for producing a multi-colored or multi-alloy extruded shape, such as metal tubing for use in forming rings. At least two contrastingly colored metal components or metal components made from different alloys are arranged in a container. The metal components in the container are compressed so as to form a billet of distorted multi-colored or multi-alloy metal. The billet is extruded thereby forming multi-colored or multi-alloy patterns in the extruded shape.

Abstract: A tapered tube manufacturing apparatus and method of operation comprises an entry station adapted to receive a tapered tube having an open, longitudinal seam with spaced longitudinal edges extending the length of the tapered tube. A feed line section moves the tapered tube from the entry section into a welding station while maintaining the longitudinal seam coincident with a pass center line which defines a direction of movement of the tapered tube through the entry station, the feed line section and the welding station. A pair of squeeze rolls in the welding station move the tapered tube through the welding station where the edges of the seam are heated, squeezing the open seam closed for welding the edges of the seam together, and then move the welded tapered tube into a cooling and transition station while maintaining the welded seam coincident with the pass center line.

Abstract: Method for manufacturing a crankcase of a piston compressor, wherein the piston compressor is provided with a crankcase which is provided with recesses for therein receiving cylinders and with at least an inlet opening, wherein from a flat sheet at least one substantially rectangular body blank is manufactured provided with the desired cylinder receiving recesses, wherein the body blank is then angle bent in an angle bending machine for forming a body part having a limited number of folds, wherein at least two substantially flat end walls are manufactured from a flat sheet, wherein thereupon the at least one body part and the at least two end walls are positioned with respect to each other using a positioning tool and are connected with each other with a welding robot for forming the crankcase. Also disclosed is a crankcase obtained with the method, and a piston compressor provided with such a crankcase.

Abstract: A tube for a heat exchanger is formed by bending a three-layer clad material of an aluminum alloy to have an overlapped portion. The three-layer clad material is formed by a core material layer containing Mg not smaller than 0.2 wt % after brazing, a brazing material layer on one surface of the core material layer, and a high melting-point material layer on the other surface of the core material layer. The brazing material layer has a thickness not smaller than 25 ?m before the brazing, and has a melting point lower than 600° C. The high melting-point material layer has a melting point equal to or higher than 600° C. In addition, the brazing material layer and the high melting-point material layer opposite to each other in the overlapped portion are bonded by the brazing at a temperature not lower than 450° C. for a time within 12 minutes.

Abstract: A method of manufacturing a component by superplastic forming and diffusion bonding a first layer, a second layer, a first membrane, and a second membrane, the first and second membranes being disposed between the first and second layers with the first membrane adjacent the first layer and the second membrane adjacent the second layer, by a method of applying a stop-off material in a first predetermined pattern between the first layer and the first membrane so preventing a diffusion bond from forming between the first layer and the first membrane across regions defined by said first predetermined pattern; applying the stop-off material in a second predetermined pattern between the second layer and the second membrane preventing a diffusion bond from forming between the second layer and the second membrane across regions defined by said second predetermined pattern; and providing a damping material between the first and second membranes.

Abstract: A hemming working is performed by a positioning step of positioning a first panel formed with a projected portion for welding on a second panel formed with a flange portion; a first bending step of bending the flange portion; and a second bending step of pressing the flange portion on an outer side of the projected portion.

Abstract: The invention relates to a method for shaping sheet steel. In said method, a blank is produced from the sheet steel, the blank is inserted into a shaping tool, and the shaped workpiece is produced from the blank in a one-stage process by means of the shaping tool. Before being shaped, the blank is heated to such a degree that the steel does not undergo any phase transition and the blank is shaped in the ferritic, pearlitic, or bainitic range without exceeding the eutectoid temperature or the recrystallization temperature. The invention also relates to an apparatus for carrying out said method.

Abstract: The present invention relates to an apparatus and a method for hot bonding metal plates having advantages that removing an oxidation film of the metal plates and bonding the metal plates are simultaneously accomplished and a bonding force between the metal plates is enhanced by applying a strong bonding pressure to the metal plates. The present invention has advantages that overlapped metal plates are compressed vertically and a shaving blade is formed at a shaving mold. Therefore, as the metal plates move, an oxidation film coated on the overlapped surfaces of the metal plates is removed. In addition, a home is formed at the shaving mold so that excess metal together with an oxidation film coated on front portions of the metal plates are removed and simultaneously the metal plates are bonded with a strong pressure.

Abstract: There is provided multicolored metal rings and multicolored metal tubing and a method for producing metal rings and metal tubing for use in forming multicolored rings. At least two contrastingly colored metal components are arranged in a container. The metal components in said container are compressed so as to form a billet of distorted multicolored metal. The billet is extruded thereby forming multicolored patterns in the tubing.

Abstract: A composite of sheet metal parts on or for a vehicle comprises a first sheet metal part forming a first outer shell region and comprising a first joining region which projects from the first outer shell region via a bent transition towards an inner side of the composite. The composite further comprises a second sheet metal part forming a second outer shell region and comprising a second joining region which projects from the second outer shell region towards the inner side of the composite, the second joining region facing the first joining region. The composite also comprises a welding or soldering seam along which the sheet metal parts are connected, wherein the seam runs along or alongside a flange edge formed in the first joining region at a distance from the first outer shell region, a flange deviating from the first joining region along the flange edge.

Abstract: A filter element (1) wound from a plurality of filter layers in which the circumferential contour (5, 5?) of a cross-sectional area (4) of the filter element (1) has at least one circumferential contour section (5?) undercutting the envelope contour (6, 6?) of the cross-sectional filter element area (4).

Abstract: A dicing tool having: a foodstuff holder for holding a block of foodstuff and a cutting base; the cutting base having: a rectangular framework for sliding the foodstuff holder therealong; a first part having an triangular shaped front edge, equally spaced triangular cutting blades being arranged in a triangular arrangement that follows the profile of the triangularly shaped front edge; a handle; a second part having a second upper surface and a right front edge and a left front edge arranged in a deep V shape, with continuous blades attached to the right and left front edges; wherein the second upper surface is always parallel to the first surface and can be slidingly reciprocated between an upper position and a lower position where the horizontal blade is substantially on a level with the first surface and the base of the triangular cutting blades.

Abstract: Provided are a low-cost battery in which an outermost first electrode plate is designed to be bent at a bent portion farther from a current collector than its own joint end so that a near portion extending from the bent portion to the joint end is positioned inward in a lamination direction than a distant portion positioned farther from the current collector than the bent portion, and first electrode plates including the outermost first electrode plate are connected to a collector joint part, and a manufacturing method thereof. In the battery of the invention, a negative collector joint part is connected to a negative joint end of an inside negative electrode plate with a fillet formed of metal melted from the negative collector joint part itself and also connected to a negative joint end of an outermost negative electrode plate with a fillet formed of metal melted from the negative collector joint part itself.

Abstract: A hemming working is performed by a positioning step of positioning a first panel formed with a projected portion for welding on a second panel formed with a flange portion; a first bending step of bending the flange portion; and a second bending step of pressing the flange portion on an outer side of the projected portion.

Abstract: In a secondary battery, for providing a structure which can enable a welding operation even when a gap is formed between a current collecting plate and a winding assembly, recessed portions are formed in a positive current collecting plate. The recessed portions are disposed opposite to the winding assembly. A laser beam is irradiated to welding protrusions located between the recessed portions to melt the welding protrusions. Here, since the end surface of a positive electrode foil is uneven in height, the positive electrode foil does not contact the positive current collecting plate necessarily. The welding operation is performed by heating, melting, and dropping the welding protrusions by the use of a YAG laser under the welding condition of a laser power of 900 W and a welding speed 2 m/min.

Abstract: An apparatus for filtering well fluids and method of manufacture is disclosed. The apparatus comprises an inner support, a filter spirally wrapped around the inner support, and an outer support wrapped around the filter enclosing the filter between the inner and outer supports. The filter has longitudinal edges which overlap and the filter is held in place by friction with the inner and outer supports. The method of manufacturing the apparatus comprises continuously and simultaneously wrapping a filter and outer support around an inner support and disposing the filter between the outer and inner supports.

Abstract: A process of making a shaped product consisting of aluminium or an aluminium alloy comprising the steps of producing an intermediate object by extrusion or rolling and having at least one flat surface, coating the at least one flat surface with a brazing flux retaining coating which is composed of flux particles and a binder containing at least 10% by weight of a synthetic resin based, as its main constituent, on methacrylate homopolymer or a methacrylate copolymer, reshaping of the intermediate object into the shaped product and heating the shaped product to a temperature sufficient to provide at least one brazed connection between defined parts of the shaped products.

Abstract: Discrete billets are rolled through a plurality of roll stands arranged along a rolling mill pass line to produce successive product lengths having reduced cross sections and front and tail ends. At a selected location along the pass line, the tail end of each product length is joined to the front end of the next successive product length to thereby permit uninterrupted continuous rolling through the remainder of the mill.

Abstract: The present invention provides a tailored blank having a pair of sheet metal constituent parts each having a pair of oppositely directed major surfaces. The first constituent part has an aperture while the second constituent part has an embossment to fit the aperture. The first and second constituent parts are then secured to one another to form the tailored blank. The blank may then be subsequently formed into a component of varying material characteristics.

Abstract: A process produces a welded seamless PIPE having good yield strength and excellent corrosion and/or erosion resistance. Up to a maximum outside diameter corrosion and/or erosion resistant CRA PIPE is cold worked from a welded hollow, rather than using the traditional seamless pierced hollow method. A high-speed roll-forming mill is also utilized, rather than using the slow traditional break press to form the welded hollow. Welded hollow dimensions can be achieved which comply with the method of cold working's capability to produce the yield strengths and dimensional tolerances required to meet the service criteria of the PIPE's intended application.

Abstract: Side hole-bearing tubular bodies made of metal and having an inside diameter of up to 2 mm are manufactured by a method which includes punching from a metal sheet a sheet blank in the developed shape of a tubular body and punching in the sheet blank a hole which corresponds to the side hole in the tubular body and/or notches which form the side hole when the sheet blank is pressed into, a tubular shape, in such a way that the metal sheet and the sheet blank remain partly joined; pressing the sheet blank into a tubular shape; and cutting apart the metal sheet and the sheet blank where they remain joined. Metal tubular bodies manufactured in this way can have one or more side holes of any shape, position or number thereon, and are highly suitable for use in medical devices such as syringe needles.

Abstract: A method and a roll-forming system for producing a metal profile are provided, wherein the wall thickness of the metal profile varies along its longitudinal axis. For this purpose, a sheet-metal strip with a thickness that varies along its length is used. Before welding together the profile or tube, which is manufactured through shaping into a closed profile or tube, this piece is sized to a desired outer diameter and in this way any existing ripples in the strip edges are made level, so that a simple, conventional straight welding of the profile or tube is possible.

Abstract: A method of manufacture of a body assembly of a refuse vehicle includes forming a first, second and third components of the assembly. A first and second locating constructions are formed in the first component. The second component is formed so as to have a first mating structure which is adapted to mate with the first locating construction in the first component so as to uniquely locate the second component with respect to the first component. The third component is formed so as to have a second mating structure which is adapted to mate with the second locating construction in the first component so as to uniquely locate the third component with respect to the first component.

Abstract: A tube welding machine (1) is of modular construction, the individual modules (2, 3, 4, 5) being arranged on a common support rail (6).

Abstract: A method of producing metal clamping rings which serve to secure elastic sleeves on components which are movable relative to one another, such as, for securing convoluted boots on joints and intermediate shafts of motor vehicle driveshafts. The method includes producing a strip portion from plate metal, which strip portion comprises strip ends which match and complement one another and which are delimited so as to be undercut-free in the longitudinal direction; bending the strip portion so as to render same round and fixing same so as to form a cylindrical ring with abutting strip ends; and welding the strip ends so that they form a clamping ring.

Abstract: An apparatus for filtering well fluids and method of manufacture is disclosed. The apparatus comprises an inner support, a filter spirally wrapped around the inner support, and an outer support wrapped around the filter enclosing the filter between the inner and outer supports. The filter has longitudinal edges which overlap and the filter is held in place by friction with the inner and outer supports. The method of manufacturing the apparatus comprises continuously and simultaneously wrapping a filter and outer support around an inner support and disposing the filter between the outer and inner supports.

Abstract: In a process for producing welded steel pipes, a pipe is molded cold from a TM-rolled sheet, welded together and sized to the desired diameter, whereby the sheet includes steel with (in wt. %) 0.02 to 0.20% carbon, 0.05 to 0.50% silicon, 0.50 to 2.50% manganese, 0.003 to 0.06% aluminum, the remainder being iron with potentially other production-related impurities. After welding and sizing, the pipe is subjected to a heat treatment process at a temperature of 100-300° C. and for a holding time that is suited to the thickness of the pipe wall, with subsequent cooling with air or by forced cooling. The resulting pipe is resistant to aging and has sufficiently integral deformation reserve against fracturing with the same high degree of strength, without exceeding the upper limit for the ratio of yield strength to tensile stress according to the current industry standards for conventional steels.

Abstract: A method for manufacturing a multiple walled tube comprising a rolling of a plated metal strip through at least two complete revolutions to form a tube having at least a double wall which has a plated layer on the inside of the tube, said rolling being followed by a heating of the tube to cause the surface of the tube walls, which are in contact with one another, to be brazed and wherein said metal strip is plated on one side, the other side being formed by the steel of the metal strip and wherein said brazing is realised by brazing directly the plated side on the steel.

Abstract: A process for improving 6XXX alloys, such as 6013, preferably includes heating, hot rolling, inter-rolling thermal treatment at a very high temperature such as 1020° F. or more, again hot rolling (with or without subsequent continuous hot rolling or cold rolling or both), solution heat treating and artificial aging. The initial heating, inter-rolling, thermal treatment and solution treatment, especially the latter two, are carried out at very high temperatures such as 1030° F. Each aforesaid hot rolling stage produces substantial metal thickness reduction. The improved sheet or plate product has a substantially reduced occurrence of reduced density features revealed in scanning electron microscope examination at 500× and exhibits improved (reduced) fatigue crack growth rate providing an advantage in aerospace applications such as fuselage skin, especially fuselage belly skin.

Abstract: An apparatus and method of manufacturing a wellscreen for subterranean use in oil, gas, and water wells, incorporating numerous automated processes, whereby layers of mesh are continuously sintered to a perforated strip, formed into a tube, placed over a perforated base pipe, and sealed with end rings.

Abstract: Side hole-bearing tubular bodies made of metal and having an inside diameter of up to 2 mm are manufactured by a method which includes punching from a metal sheet a sheet blank in the developed shape of a tubular body and punching in the sheet blank a hole which corresponds to the side hole in the tubular body and/or notches which form the side hole when the sheet blank is pressed into, a tubular shape, in such a way that the metal sheet and the sheet blank remain partly joined; pressing the sheet blank into a tubular shape; and cutting apart the metal sheet and the sheet blank where they remain joined. Metal tubular bodies manufactured in this way can have one or more side holes of any shape, position or number thereon, and are highly suitable for use in medical devices such as syringe needles.

Abstract: An arm body of a working machine has a hollow and triangular cross-section. A bucket-connection bracket is jointed to one longitudinal end of an arm body, and an arm cylinder bracket is jointed to another longitudinal end of the arm body, thereby forming an arm. With the triangular cross-sectional structure, the arm body is less prone to deformation under the stress of a load. The improved triangular cross-sectional structure permits the plate thickness of the arm body to be reduced, and the rigidity of the arm body to be increased without mounting a cross-section restraint material in the arm body. The cross-section of the boom will not deform even though the plate thickness is reduced. Therefore, it is possible to reduce the weight of the boom and still prevent deformation of the boom under heavy load.

Abstract: High strength steel tube is made from a full hard, cold rolled steel sheet having a chemistry compliant to S.A.E. J 403 grade 1026. The high strength of the tube is a result of specified thermal-mechanical processing of hot rolled sheet followed by controlled percent cold rolled reduction, and does not require post-welding thermal heat treatment and/or cold drawing processing.

Abstract: A process for the production of metal pipes is described in which a thin-walled metal band inclined toward cold spots is gradually formed into a slotted pipe, the longitudinal edges lying flush against one another are welded to one another, and the welded pipe is reduced in its diameter. The forming of the metal band into the slotted pipe is done by opposing metal forming rollers or forming cylinders cooperating pairwise. The forming rollers or forming cylinders guide the metal band to be deformed in its edge area with rolling friction between them. Therein the forming and guiding of the metal band is done with forming rollers and/or forming cylinders and the reduction with rollers whose surface hardness is greater than 100 GPa.

Abstract: The present invention provides a method for molding an assembly panel by manufacturing a blank for a main panel and a blank for a reinforcing panel; temporarily welding the blank for the reinforcing panel to the blank for the main panel along a predetermined welding line; holding the two welded panels in a press and molding the same into a predetermined shape; trimming scraps from the main panel; and spot welding the two panels so that the two panels adhere to each other more firmly.

Abstract: The present invention is a hollow-pipe forming apparatus and its products, which mainly comprises a driving mechanism, a fuse-welding mechanism and a feeding mechanism etc. The driving mechanism connects with a cylindrical internal mold at an output end of a driver, with the outside diameter of the internal mold being equal to the inside diameter of the pipe to be produced. The fuse-welding mechanism is a general fuse-welding machine, which has a welding gun. The feeding mechanism supports a metal strip thereon, and the metal strip is caused to pass through a leveling and fixing rack and overlap onto the internal mold of the driving mechanism after being unrolled, so that the leveling and fixing rack can exert a stretching and leveling effect on the metal strip. When the metal strip is overlapped onto the internal mold, it will form an angle between it and the internal mold. Therefore, the metal strip on the feeding mechanism can overlap onto the internal mold of the driving mechanism in an appropriate angle.

Abstract: The invention relates to a method of manufacturing heat transfer tubes for a heat exchanger such as an automobile radiator. The tubes are preferably formed of copper or a copper alloy. A sheet of the material is folded into a shape that resembles a B and is brazed together with a brazing material that is free from flux. The brazing material is in the form of a foil or paste. The paste typically includes a powder filler, a binder, and a carrier, which may be a liquid or a wax.

Abstract: An apparatus to produce straight bead welded tubes from flat sheet metal blanks with two parallel longitudinal edges includes two form tool halves. The two form tool halves have outer cylindrical half shells borne by a tool support, and are disposed laterally inverted in relation to one another. They are moved towards one another and out of an opened receiving position for the sheet metal blanks into a closed position, in which the two longitudinal edges are held together by the two form tool halves. The apparatus also includes a welding device, which moves over the two form tool halves along the two longitudinal edges retained in a welding position. The two form tool halves have cylindrical internal mandrel halves which are fixedly associated with the outer cylindrical half shells and which cooperate with the outer cylindrical half shells to produce form gaps for insertion of the sheet metal blanks.

Abstract: In a process for producing longitudinally welded tubes, a metal strip, which is continuously pulled from a supply, is gradually formed into a slit tube and the longitudinal slit of said slit tube is welded. The metal strip (2) is pulled through a plurality of drawing dies (8, 9, 10, 11) arranged one behind the other and having a diameter that decreases in production direction, and in each of the drawing dies (8, 9, 10, 11) is increasingly bent in circumferential direction. The slit tube is closed in a last forming step (15) immediately in front of the welding point.

Abstract: In a process for producing welded steel pipes, a pipe is molded cold from a TM-rolled sheet, welded together and sized to the desired diameter, whereby the sheet includes steel with (in wt. %) 0.02 to 0.20% carbon, 0.05 to 0.50% silicon, 0.50 to 2.50% manganese, 0.003 to 0.06% aluminum, the remainder being iron with potentially other production-related impurities. After welding and sizing, the pipe is subjected to a heat treatment process at a temperature of 100-30° C. and for a holding time that is suited to the thickness of the pipe wall, with subsequent cooling with air or by forced cooling. The resulting pipe is resistant to aging and has sufficiently integral deformation reserve against fracturing with the same high degree of strength, without exceeding the upper limit for the ratio of yield strength to tensile stress according to the current industry standards for conventional steels.

Abstract: The invention relates to a double-layered sheet comprising two cover sheets (1, 2) with a space between them, and a fill material (3) which fills the space between said cover sheets. Said fill material is made of plastic, in particular of porous duroplastic plastic, comprising embedded hard bodies (6, 7, 8, 9). In order to obtain the best possible geometrical moment of inertia while keeping the weight per surface area low, and in particular in order to prevent shearing out under pressure, of the cover sheet (1) acting as a compression chord, during pressing together of the double-layered sheet, the fill material is characterised by at least two stress/strain characteristic curves. In particular the fill material comprises pores which are sealed off from each other.

Abstract: A method for manufacturing a multiple walled tube comprising a rolling of a plated metal strip through at least two complete revolutions to form a tube having at least a double wall which has a plated layer on the inside of the tube, said rolling being followed by a heating of the tube to cause the surface of the tube walls, which are in contact with one another, to be brazed and wherein said metal strip is plated on one side, the other side being formed by the steel of the metal strip and wherein said brazing is realised by brazing directly the plated side on the steel.