Tube forming methods can be used for efficient transition in the production of tubes having varying thickness. Material used to form consecutive tubes may have the same thickness along a separation plane separating a first discrete section from a second discrete section of the material, and the first discrete section and the second discrete section may each have varying thickness in a feed direction of the material. With such a thickness profile, the first discrete section of the material may be formed into a first cylinder having varying thickness and separated from the second discrete portion as the second discrete section is formed into a second cylinder having varying thickness. In particular, the transition between the first cylinder and the second cylinder may be achieved without scrap and/or interruption, resulting in cost-savings and improvements in production throughput associated with forming tubes having varying thickness.

The invention relates to a fluid channel for a heat exchanger, comprising a metal sheet, wherein the metal sheet has at least one core region of an aluminum base alloy and at least one structure arranged inside the fluid channel, wherein the structure lies against a surface of the metal sheet and can be soldered to the metal sheet in a flux-free manner by way of a first soldering location in a soldering operation, and wherein a soldering region of the metal sheet and a counterpart lie against one another and can be soldered to one another in the same soldering operation as a second soldering location while wetting with flux, wherein an open path between the two soldering locations exists before the soldering operation.

This disclosure relates to a method for manufacturing a double pipe, including: a primary roll forming step of forming bending portions on both sides of a strip for an external pipe in a longitudinal direction; a stacking step of stacking a strip for an internal pipe on the strip for the external pipe; a secondary roll forming step of mechanically coupling the strip for the external pipe and the strip for the internal pipe; a forming step of forming the strip for the external pipe and the strip for the internal pipe, mechanically coupled to each other, into a pipe shape; a welding step of bonding the bending portions on both sides of the strip for the external pipe, and the strip for the internal pipe, which are formed into the pipe shape; and a heat treatment step of heat-treating bonded portions of the strip.

An apparatus that manufactures a closed-structure part includes a bottom portion and left and right side wall portions, including a press-forming die that form a plurality of first out-of-plane deformed portions and bent portions, the first out-of-plane deformed portions being formed in a region of a workpiece corresponding to the bottom portion and arranged along a longitudinal direction, each of the first out-of-plane deformed portions having a recessed shape or a protruding shape; a pad and a punch that squash the first out-of-plane deformed portions by clamping the region of the workpiece corresponding to the bottom portion therebetween, a cross-sectional shape of a pressing portion of the punch being curved along the longitudinal direction; and bending dies that bend the bent portions by pressing the punch into a space therebetween while the region of the workpiece corresponding to the bottom portion is clamped between the pad and the punch.

An apparatus that manufactures a closed-structure part includes a bottom portion and left and right side wall portions, including a press-forming die that form a plurality of first out-of-plane deformed portions and bent portions, the first out-of-plane deformed portions being formed in a region of a workpiece corresponding to the bottom portion and arranged along a longitudinal direction, each of the first out-of-plane deformed portions having a recessed shape or a protruding shape; a pad and a punch that squash the first out-of-plane deformed portions by clamping the region of the workpiece corresponding to the bottom portion therebetween, a cross-sectional shape of a pressing portion of the punch being curved along the longitudinal direction; and bending dies that bend the bent portions by pressing the punch into a space therebetween while the region of the workpiece corresponding to the bottom portion is clamped between the pad and the punch.

A method for producing a multilayer large pipe having an outer support layer and at least one inner liner layer. Advantages with regard to productivity and the properties of the multilayer large pipe are achieved by the sequence of method steps wherein production of a support sheet is pre-bent to a predetermined initial bending radius for the support layer and at least one liner sheet is pre-bent to a predetermined initial bending radius for the liner layer, placement of the at least one pre-bent liner sheet against the inside of the pre-bent support sheet, with a positioning and parallel alignment of its longitudinal edges extending in the direction of the bending axis in order to form the support layer and the at least one liner layer, there is integral joining of at least one of two longitudinal edges of the at least one liner sheet to the support sheet, shaping of the composite of the integrally joined support layer and at least one liner layer to form a slit multilayer large pipe by a bending machine, with nonpositive, frictional engagement in liner regions that are not integrally joined, and there is closing of the remaining gap of the slit multilayer large pipe with a longitudinal seam by welding.

A method and apparatus for producing gun barrels having a grooved or ribbed inner surface with straight or helical grooves or ribs, by providing a metallic hollow cylindrical pre-form, placing the pre-form on a core mandrel being part of a flow forming machine having a main machine axis, the core mandrel having a structured outer surface comprising ribs and/or grooves extending straightly parallel to and/or helically around the main axis; and applying forming rollers, in a roller arrangement, to the outside surface of the pre-form so as to apply radial pressure on the pre-form such that its material begins to flow. As the rollers apply force upon the pre-form, a relative motion between the pre-form and the rollers is performed by moving the pre-form in axially parallel to the main axis through the roller arrangement or by moving the roller arrangement alongside the pre-form.

A method manufactures a closed-structure part by forming a flat plate-shaped workpiece into a closed structure including a bottom portion curved along a longitudinal direction. The method includes a first forming step of forming a plurality of first out-of-plane deformed portions and a bent portion, the first out-of-plane deformed portions being formed in a region of the workpiece corresponding to the bottom portion and arranged along the longitudinal direction, each of the out-of-plane deformed portions having a recessed shape or a protruding shape; and a second forming step of squashing the first out-of-plane deformed portions between a pad and a punch such that the region of the workpiece corresponding to the bottom portion is curved and bending bent portions by pressing the punch into a space between dies while the region of the workpiece corresponding to the bottom portion is clamped between the pad and the punch.

A method manufactures a closed-structure part by forming a flat plate-shaped workpiece into a closed structure including a bottom portion curved along a longitudinal direction. The method includes a first forming step of forming a plurality of first out-of-plane deformed portions and a bent portion, the first out-of-plane deformed portions being formed in a region of the workpiece corresponding to the bottom portion and arranged along the longitudinal direction, each of the out-of-plane deformed portions having a recessed shape or a protruding shape; and a second forming step of squashing the first out-of-plane deformed portions between a pad and a punch such that the region of the workpiece corresponding to the bottom portion is curved and bending bent portions by pressing the punch into a space between dies while the region of the workpiece corresponding to the bottom portion is clamped between the pad and the punch.

A method of manufacturing a double-walled elbow pipe segment, comprising the steps of: (a) providing an inner pipe member; (b) providing at least one first support member, and positioning said at least one first support member coaxially over said inner pipe member; (c) providing an outer pipe member and slidably positioning said assembled inner pipe member and said at least one first support member within said outer pipe member such that said at least one first support member is supportingly engaged with an outer surface of said inner pipe member and an inner surface of said outer pipe member, and (d) bending a pipe assembly of said inner pipe member, said at least one first support member and said outer pipe member into at least one first elbow section of a predetermined first angle and in a predetermined first direction between an upstream end portion and a downstream end portion of said pipe assembly.