US 5,259,547 AGranted

Method of manufacturing bi-metallic tubing

AssigneeImperial Chemical Industries PLC

InventorRoy Hardwick

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Abstract

This invention relates to a method for producing bi-metallic tubing wherein a layer (3,31) of a first metal is metallurgically bonded to the exterior surface of a core component (1,29) of a second metal incompatible for solid state bonding with the first metal by processes other than explosive bonding, the resulting cylindrical bonded composite (15,25) is placed within the bore of a thick-walled tube (33) of a metal compatible for solid state bonding with the first metal and the assembly (39) is heated and expanded by passing it over a profiled mandrel (43). In passing over the mandrel sufficient pressure is developed at the interface between the bonded composite and the thick-walled tube to form a metallurgical bond at the interface. When the first metal is the same as the metal of the thick-walled tube the interface is eliminated and a bi-metallic tube consisting of a single outer layer of the first metal with a bonded lining of the second metal is produced. The method is advantageous for producing large diameter tubes having an outer layer of cheaper metal for example, steel and a lining of more expensive metal corrosion-resistant metal, for example, nickel alloy.

Claims13

Dependent claims

A method for producing a bi-metallic tube comprising the steps of:

providing a layer of a first metal;
providing a core component of a second metal, said second metal being incompatible for solid state bonding with said first metal by processes other than explosive bonding;
metallurgically bonding said layer of said first metal to an exterior surface of said core component and thereby forming a cylindrical bonded composite;
placing at least a portion of said cylindrical bonded composite within a bore of a thick-walled tube of a metal compatible for solid state bonding with said first metal and thus forming an annular interface between an exterior surface of said thick-walled tube;
sealing said annular interface and thereby forming an assembled composite;
heating said assembled composite to an elevated temperature at which solid state bonding of said thick-walled tube and said first metal can be effected;
and
forcing said assembled composite at said elevated temperature axially over a mandrel of progressively increasing diameter by means of two or more externally placed barrel rollers whereby said assembled composite is continuously rotated and advanced helically in a space between said rollers and said mandrel, an axial bore is provided in said core component by at least one of forming an axial bore in a solid core component and expanding a preformed axial bore in said core component, the wall thicknesses of said cylindrical bonded composite and said thick-walled tube are simultaneously and progressively reduced and sufficient pressure is developed at said interface to effect metallurgical bonding between said cylindrical bonded composite and said thick-walled tube and thus form said bi-metallic tube.

5 more elements

A method for producing a bi-metallic tube comprising the steps of:

providing a layer of a first metal;
providing a core component of a second metal, said second metal being incompatible for solid state bonding with said first metal by processes other than explosive bonding;
metallurgically bonding said layer of said first metal to an exterior surface of said core component and thereby forming a cylindrical bonded composite;
placing at least a portion of said cylindrical bonded composite within a bore of a thick-walled tube of a metal compatible for solid state bonding with said first metal and thus forming an annular interface between an exterior surface of said thick-walled tube;
connecting said cylindrical bonded composite to said thick-walled tube by connecting means comprising one or more connecting pins, each pin being inserted into a hole drilled along an axis located on said interface and parallel to the axis of said cylindrical bonded composite, said pins being effective to provide one or more keys between said bonded composite and said thick-walled tube;
sealing said annular interface and whereby forming an assembled composite;
heating said assembled composite to an elevated temperature at which solid state bonding of said thick-walled tube and said first metal can be effected;
and
forcing said assembled composite at said elevated temperature axially over a mandrel of progressively increasing diameter by means of two or more externally placed barrel rollers whereby said assembled composite is continuously rotated and advanced helically in a space between said rollers and said mandrel, an axial bore is provided in said core component by at least one of forming an axial bore in a solid core component and expanding a preformed axial bore in said core component, the wall thicknesses of said cylindrical bonded composite and said thick-walled tube are simultaneously and progressively reduced and sufficient pressure is developed at said interface to effect metallurgical bonding between said cylindrical bonded composite and said thick-walled tube and thus form said bi-metallic tube, wherein said connecting means is sufficiently strong to preclude substantial differential rotation between said bonded composite and said thick-walled tube when said assembled composite is forced over said mandrel.

6 more elements

Dependencies are inferred from the claim text.