A method for forming curved lengths of extruded profiles/sections in metal alloys

Abstract

A method of extruding a material, comprising providing the material into an extrusion chamber of an extrusion apparatus, wherein the extrusion chamber comprises an extrusion orifice and the extrusion apparatus comprises a first compression element and a second compression element in communication with the interior of the extrusion chamber, the first and second compression elements being independently movable relative to the extrusion chamber, moving at least one of the first and second compression elements to compress the material within the extrusion chamber and cause a velocity gradient in the extrusion material across the extrusion orifice and extruding the material through the extrusion orifice such that the velocity gradient forms an extrudate with a curved profile.

1 . A method of extruding a material, comprising:
 providing the material into an extrusion chamber of an extrusion apparatus, wherein the extrusion chamber comprises an extrusion orifice and the extrusion apparatus comprises a first compression element and a second compression element in communication with the interior of the extrusion chamber, the first and second compression elements being independently movable relative to the extrusion chamber;   moving at least one of the first and second compression elements to compress the material within the extrusion chamber and cause a velocity gradient in the extrusion material across the extrusion orifice; and   extruding the material through the extrusion orifice such that the velocity gradient forms an extrudate with a curved profile.   
     
     
         2 . A method according to  claim 1 , comprising moving both of the first and second compression elements to compress the material within the extrusion chamber. 
     
     
         3 . A method according to  claim 2 , comprising moving the first compression element and second compression element at different speeds. 
     
     
         4 . A method according to  claim 2  or  3 , wherein the first compression element and second compression element have different cross-sectional areas perpendicular to their direction of movement. 
     
     
         5 . A method according to any of  claims 1  to  4 , wherein moving the first and second compression elements comprises moving the first and second compression elements along a common axis. 
     
     
         6 . A method according to  claim 5 , wherein moving the first and second compression elements along a common axis comprises moving the first and second compression elements towards each other in opposite directions along the common axis. 
     
     
         7 . A method according to  claim 5  or  6 , wherein the plane of the cross-section of the extrusion orifice is parallel to the common axis such that extruding the material through the extrusion orifice comprises extruding the material through the extrusion orifice substantially perpendicular to the common axis. 
     
     
         8 . A method according to any of  claims 1  to  4 , wherein moving the first and second compression elements comprises moving the first compression element along a first axis and moving the second compression element along a second axis different to the first axis. 
     
     
         9 . A method according to  claim 8 , wherein the first axis and the second axis are parallel to each other. 
     
     
         10 . A method according to  claim 9 , wherein the plane of the cross-section of the extrusion orifice is perpendicular to the first and second axes such that extruding the material through the extrusion orifice comprises extruding the material through the extrusion orifice substantially parallel to the first and second axes. 
     
     
         11 . A method according to  claim 8 , wherein the first axis and the second axis are at an angle to one another. 
     
     
         12 . A method according to  claim 11 , wherein the plane of the cross-section of the extrusion orifice is perpendicular to a line that bisects the first and second axes such that extruding the material through the extrusion orifice comprises extruding the material through the extrusion orifice substantially parallel to the line. 
     
     
         13 . A method according to any one of the preceding claims, wherein the material is a metal alloy. 
     
     
         14 . A method according to  claim 13 , wherein the metal alloy is aluminium alloy or magnesium alloy. 
     
     
         15 . A method according to any one of the preceding claims, wherein the extrusion orifice is provided by an extrusion die that defines the geometry of the orifice. 
     
     
         16 . A method according to any one of the preceding claims, further comprising providing a guide means adjacent to the extrusion orifice to control curvature of the extruded material. 
     
     
         17 . A method according to any one of the preceding claims, further comprising providing a mandrel in the extrusion chamber opposite to the extrusion orifice. 
     
     
         18 . A method according to  claim 17 , wherein extruding the material through the extrusion orifice comprises extruding the material with a hollow cross-section defined by the mandrel and orifice. 
     
     
         19 . A method according to any one of the preceding claims, further comprising preheating the material before providing it into the extrusion chamber. 
     
     
         20 . A method according to any one of the preceding claims, wherein the extrusion chamber is cylindrical. 
     
     
         21 . A method according to  claim 20 , wherein the cross-sectional area of the extrusion chamber is larger than the cross-sectional area of the extrusion orifice. 
     
     
         22 . An apparatus for extrusion of a material, the apparatus comprising:
 an extrusion chamber for receipt of an extrusion material, the extrusion chamber comprising an extrusion orifice;   a first compression element and a second compression element, the first and second compression elements being in communication with the interior of the extrusion chamber and being independently movable relative to the extrusion chamber.   
     
     
         23 . An apparatus according to  claim 22 , wherein the first compression element and second compression element are configured to be moved simultaneously. 
     
     
         24 . An apparatus according to  claim 23 , wherein the first compression element and second compression element are configured to be moved at different speeds. 
     
     
         25 . An apparatus according to  claim 23  or  24 , wherein the first compression element and second compression element have different cross-sectional areas perpendicular to their direction of movement. 
     
     
         26 . An apparatus according to any of  claims 22  to  25 , wherein the first compression element and second compression element are configured to be moved along a common axis. 
     
     
         27 . An apparatus according to  claim 26 , wherein the first compression element and second compression element are configured to be moved towards each other in opposite directions along the common axis. 
     
     
         28 . An apparatus according to  claim 26  or  27 , wherein the plane of the cross-section of the extrusion orifice is parallel to the common axis. 
     
     
         29 . An apparatus according to any of  claims 22  to  25 , wherein the first compression element is configured to be moved along a first axis and the second compression element is configured to be moved along a second axis different to the first axis. 
     
     
         30 . An apparatus according to  claim 29 , wherein the first axis and the second axis are parallel to each other. 
     
     
         31 . An apparatus according to  claim 30 , wherein the plane of the cross-section of the extrusion orifice is perpendicular to the first and second axes. 
     
     
         32 . An apparatus according to  claim 29 , wherein the first axis and the second axis are at an angle to one another. 
     
     
         33 . An apparatus according to  claim 32 , wherein the plane of the cross-section of the extrusion orifice is perpendicular to a line that bisects the first and second axes. 
     
     
         34 . An apparatus according to any one of  claims 22  to  32 , wherein the extrusion material is a metal alloy. 
     
     
         35 . An apparatus according to  claim 24 , wherein the metal alloy is aluminium alloy or magnesium alloy. 
     
     
         36 . An apparatus according to any one of  claims 22  to  35 , wherein the extrusion orifice is provided by an extrusion die that defines the geometry of the orifice. 
     
     
         37 . An apparatus according to any one of  claims 22  to  36 , further comprising a guide means adjacent to the extrusion orifice to control curvature of the extruded material. 
     
     
         38 . An apparatus according to any one of  claims 22  to  37 , further comprising a mandrel in the extrusion chamber opposite to the extrusion orifice. 
     
     
         39 . An apparatus according to any one of  claims 22  to  38 , wherein the extrusion material is preheated. 
     
     
         40 . An apparatus according to any one of  claims 22  to  39 , wherein the extrusion chamber is cylindrical. 
     
     
         41 . An apparatus according to  claim 40 , wherein the cross-sectional area of the extrusion chamber is larger than the cross-sectional area of the extrusion orifice. 
     
     
         42 . A method according to any one of  claims 1  to  21 , further comprising varying the speed of movement of the first compression element and/or the second compression element to vary the velocity ratio as the material is extruded. 
     
     
         43 . An apparatus according to any one of  claims 22  to  41 , wherein the first compression element and/or the second compression element are configured to be moved at a varying speed.