Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/02—Making uncoated products
  • B21C23/04—Making uncoated products by direct extrusion
  • B21C23/08—Making wire, rods or tubes
  • B21C23/12—Extruding bent tubes or rods
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C23/00—Extruding metal; Impact extrusion
  • B21C23/002—Extruding materials of special alloys so far as the composition of the alloy requires or permits special extruding methods of sequences
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/12—Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/131—Curved articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
  • B29C48/475—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using pistons, accumulators or press rams
  • B29C48/48—Two or more rams or pistons

Definitions

• This disclosure relates to a method and equipment for forming curved metal alloy profiles and more particularly aluminium alloy profiles with predesigned curvature in one extrusion-bending process.
• Aluminium alloy profiles are extensively used as construction elements in industrial manufacturing for the production of ultra-light component structures with a high contour complexity, including seat rails, stringers, and frames in the aircraft industry as well as window frames and roof rails in the automotive industry. This is mainly because they facilitate construction of lightweight, strong, and stiff structures. Taking into account the demand for reduced aerodynamic resistance as well as improved aesthetics, the manufacture and application of highly precise curved aluminium alloy profiles with well adapted properties are quite necessary.
• 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.
• an apparatus for extrusion of a material 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.
• the method may comprise moving both of the first and second compression elements to compress the material within the extrusion chamber.
• the method may comprise moving the first compression element and second compression element at different speeds.
• Moving the first and second compression elements may comprise moving the first and second compression elements along a common axis.
• Moving the first and second compression elements along a common axis may comprise moving the first and second compression elements towards each other in opposite directions along the common axis.
• the plane of the cross-section of the extrusion orifice may be 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.
• Moving the first and second compression elements may comprise moving the first compression element along a first axis and moving the second compression element along a second axis different to the first axis.
• the first axis and the second axis may be parallel to each other.
• the plane of the cross-section of the extrusion orifice may be 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.
• the first axis and the second axis may be at an angle to one another.
• the plane of the cross-section of the extrusion orifice may be 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.
• the method may further comprise providing a guide means adjacent to the extrusion orifice to control curvature of the extruded material.
• the method may further comprise providing a mandrel in the extrusion chamber opposite to the extrusion orifice. Extruding the material through the extrusion orifice may comprise extruding the material with a hollow cross-section defined by the mandrel and orifice. The plane of the cross-section of the mandrel that defines the hollow cross-section of the extruded material may be parallel to the plane of the cross-section of the extrusion orifice.
• the method may further comprise preheating the material before providing it into the extrusion chamber.
• the first compression element and second compression element may be configured to be moved simultaneously.
• the first compression element and second compression element may be configured to be moved at different speeds.
• the first compression element and second compression element may have different cross-sectional areas perpendicular to their direction of movement.
• the first compression element and second compression element may be configured to be moved along a common axis.
• the first compression element and second compression element may be configured to be moved towards each other in opposite directions along the common axis.
• the plane of the cross-section of the extrusion orifice may be parallel to the common axis.
• the first compression element may be configured to be moved along a first axis and the second compression element may be configured to be moved along a second axis different to the first axis.
• the first axis and the second axis may be parallel to each other.
• the plane of the cross-section of the extrusion orifice may be perpendicular to the first and second axes.
• the first axis and the second axis may be at an angle to one another.
• the plane of the cross-section of the extrusion orifice may be perpendicular to a line that bisects the first and second axes.
• the extrusion material may be a metal alloy.
• the metal alloy may be aluminium alloy or magnesium alloy.
• the extrusion orifice may be provided by an extrusion die that defines the geometry of the orifice.
• the apparatus may further comprise a guide means adjacent to the extrusion orifice to control curvature of the extruded material.
• the apparatus may further comprise a mandrel in the extrusion chamber opposite to the extrusion orifice.
• the extrusion material may be preheated.
• the extrusion chamber may be cylindrical.
• the cross-sectional area of the extrusion chamber may be larger than the cross- sectional area of the extrusion orifice.
• a method of forming curved metal alloy profiles comprising:
• Figure 1a is a schematic illustration of an extrusion apparatus known in the art
• Figure 1 b is a schematic illustration of another extrusion apparatus known in the art
• Figure 2 is a schematic illustration of an extrusion apparatus according to an embodiment
• Figure 3a is a schematic illustration of another extrusion apparatus according to an embodiment
• Figure 3b is a cross-section through the line m-m in Figure 3a;
• Figure 4 is a schematic illustration of yet another extrusion apparatus according to an embodiment
• Figure 5 is a schematic illustration of the orientation of a first, second and third axis of an extrusion apparatus according to an embodiment.
• Figure 1a shows an extrusion apparatus known in the art.
• a cylindrical extrusion chamber 102 has two open ends 104 and 106.
• An extrusion die 108 with a designed orifice 110 is installed at the first open end 104.
• the geometry of the orifice 1 10 is designed to form the extruded material into a chosen shape.
• a hot or cold billet 1 12 is placed into the extrusion chamber 102 from the second open end 106.
• a punch 114 is positioned at the second open end 106. Its working face 1 16 would usually be protected by a dummy block 1 18.
• Another extrusion apparatus known in the art is shown in Figure 1 b.
• an extrusion chamber 130 has an L-shape in transverse section, rather than being a straight cylinder. In this manner, the billet 132 is forced along a straight section 134 to form the straight extrudate 136.
• the straight section 134 is of sufficient length to ensure that the extrudate 136 is formed in a straight manner.
• FIG. 2 shows an extrusion apparatus 200 according to the present disclosure.
• a cylindrical extrusion chamber 202 has two open ends 204 and 206.
• a hot or cold billet 208 is placed into the extrusion chamber 202 from the first open end 204 and/or the second open end 206.
• an aluminium alloy billet may be pre-heated to 350-550°C for warm or hot extrusion or remain unheated for cold extrusion.
• a first punch 210 is positioned at the first open end 204.
• a second punch 212 is positioned at the second open end 206.
• the respective working faces 214 and 216 of the first and second punches 210 and 212 are protected by respective dummy blocks 218 and 220.
• An extrusion die 222 with a designed orifice 224 is installed in the side wall of the extrusion chamber 202.
• the first punch 210 together with dummy block 218 act as a first compression element and the second punch 212 together with dummy clock 220 act as a second compression element.
• the skilled person with recognise that these compression elements could be replaced by any other suitable compression means.
• the first and second compression elements are independently movable relative to the extrusion chamber 202. As described below, this allows the profile of an extrudate to be controlled, particularly with respect to its curvature. In operation, pressure is applied to the two dummy blocks 218 and 220 via the corresponding two punches 210 and 212 simultaneously.
• the velocity of the first punch 210 is vi, and the velocity of the second punch 212 is V2.
• the billet 208 is forced sideways out of the extrusion chamber 202 through the die orifice 224. Its exiting direction is perpendicular to the punch motion direction.
• the rate of mass flow provided by each of the compression elements can be adjusted.
• the velocities of the punches 210 and 212 can be adjusted to provide a curved extrudate.
• a flow velocity gradient is produced across the die orifice 224. Therefore, the extruded profile bends towards the side of the extrusion chamber 202 which has the lower extrusion velocity.
• the velocity vi of the first punch 210 is larger than the velocity V2 of the second punch 212. Therefore, the extrudate 226 bends towards the second open end 206.
• the area of the first dummy block 218 is greater than that of the second dummy block 220. In this instance, the extruded profile will bend downwards as shown in Fig. 2 even when
• S is the cross-sectional area
• v is the velocity. Therefore, increasing the velocity vi and/or the area of the first dummy block 218 can lead to more material flowing into the upper side of the die exit 222 compared with the lower side.
• the extrusion and bending operations are performed simultaneously. This removes the need for post-processing of straight extruded pieces to provide curvature, and overcomes the issues mentioned above.
• the curvature of the extrudate 226 can be adjusted. If the velocity ratio is defined as V2/V1 , a lower velocity ratio tends to increase the material flow velocity gradient at the die exit and lead to greater curvature. When this velocity ratio is less than 1/3, bending curvature increases significantly with reducing velocity ratio. Maximum curvature results at zero velocity of the lower punch 212. The velocity ratio could be changed during extrusion. This will enable the curvature of the extrudate 226 to be changed as extrusion proceeds, which allows more complex extrusions.
• an extrusion ratio is defined as the ratio of the cross-sectional area of the billet to the cross-sectional area of the extruded profile. These areas are controlled by adjusting the cross-sectional area of the extrusion chamber 202 and the extrusion orifice 224 respectively.
• the extrusion ratio can be defined as the square of the diameter ratio of the extrusion chamber 202 to the orifice 224.
• Di 2 For a tubular circular extrusion (a hollow bar), it can be defined as Di 2 /( D ⁇ -Dz 2 ), where Di , D2, D3 are the respective diameters of the extrusion chamber 202, the orifice 224 and a mandrel fixed to the inner wall of the extrusion chamber opposite to the exit die to define the wall thickness of the tube.
• a larger extrusion ratio tends to increase the material flow velocity gradient at the die exit and lead to greater curvature.
• the curvature of the extrudate 226 For a constant diameter of the extrusion chamber 202, the curvature of the extrudate 226 is increased as the diameter of the orifice 224 is decreased. Conversely, the curvature of the extrudate 226 is reduced as the diameter orifice 224 is increased.
• the effect of changing the extrusion ratio is less than that of changing the velocity ratio, especially when velocity ratio is greater than 0.5. Below this value, the effect of extrusion ratio increases as velocity ratio V2/V1 decrease
• Figure 3a shows an alternative extrusion apparatus 300 according to the present disclosure.
• the apparatus 300 is similar to the apparatus 100 of Figure 1a, except that two adjacent punches are used instead of a single punch.
• a cylindrical extrusion chamber 302 has two open ends 304 and 306.
• a hot or cold billet 308 is placed into the extrusion chamber 302 from the second open end 306.
• First and second punches 310 and 312 are positioned adjacent to one another at the second open end 306.
• the respective working faces 314 and 316 of the first and second punches 310 and 312 are protected by a respective dummy blocks 318 and 320.
• An extrusion die 322 with a designed orifice 324 is installed at the first open end 304.
• the length of the first dummy block 318 is shown as longer than that of the second dummy block 320.
• the second dummy block 320 may entirely pass the first dummy block 318.
• the billet 308 may flow out of the chamber 302 from the gap between the first dummy block 318 and the second dummy block 320.
• FIG. 3b shows the dummy blocks 318 and 320 with different cross-sectional areas perpendicular to their direction of movement.
• Figure 4 shows yet another alternative extrusion apparatus 400 according to the present disclosure.
• the apparatus comprises a Y-shaped extrusion chamber 402, having a first bore 404, a second bore 405 and a central container 406.
• the first bore 404 and the second bore 405 are positioned at an angle to each other and converge to meet the central container 406, forming the Y-shape.
• Each of the first bore 404, the second bore 405 and the central container 406 has an open end opposite to the point of convergence.
• a first hot or cold billet 407 is placed into the open end of the first bore 404.
• a second hot or cold billet 408 is placed into the open end of the second bore 405.
• a first punch 410 is positioned at the open end of the first bore 404.
• a second punch 412 is positioned at the open end of the second bore 405.
• the respective working faces 414 and 416 of the first and second punches 410 and 412 are protected by a respective dummy block 418 and 420.
• An extrusion die 422 with a designed orifice 424 is installed at the open end of the central container 406.
• the first and second compression elements can be positioned at an angle a, shown in Figure 5.
• the first and second axes correspond to the first and second compression elements, with the third axis bisecting the first and second axes and corresponding to the direction of extrusion from the die orifice.
• the plane of the cross-section of the extrusion orifice is perpendicular to a line bisecting the first and second axes, with the third axis being parallel to this line.
• SPD of the billet results in an extruded profile with an ultra-fine grain size, thereby improving the mechanical properties of the extruded profile.
• SPD of the billet increases as the angle ⁇ decreases (i.e. as angle a increases), thereby giving rise to improved mechanical properties arising from SPD with reduced angle ⁇ .
• the first and second axes may be orientated at an angle 0° ⁇ a ⁇ 360°.
• the extrusion apparatus schematically illustrated in Figure 4 may have any arbitrary angle between 0° and 360°.
• curved sections with undistorted cross- sections can be achieved by utilising asymmetric flow in the extrusion die. Since it is a natural bending process based on internal differential material flow rather than external bending force, defects such as distortion and thinning of the cross-section are avoided. The combination of the extrusion and bending processes into a single process, thus eschews the complication of an extra external bending apparatus.
• the compression elements may move at the same velocity, with the velocity gradient across the extrusion orifice being a function of geometric features (such as a greater surface area for one dummy block/compression element in comparison with the other).
• a combination of geometric features and the velocities of the compression elements may result in a desired velocity gradient at the extrusion orifice.
• a guide external to the die orifice 224 may be employed to ensure precise curve accuracy. Any of the above embodiments may be used for extrusion of solid bars or tubes.
• a mandrel may be fixed to the inner wall of the extrusion chamber opposite to the exit die.
• the size of the mandrel relative to the size of the die orifice will define the wall thickness of the extruded tube.
• the curvature of the tube is reduced with increase of wall thickness of the tube.
• the effect of the wall thickness on curvature is small, compared with that of the velocity ratio. Otherwise, a similar tendency in the extrusion of round bars described before also occurs in extrusion of round tubes.
• any of the above embodiments may be used to produce curved profiles in any material that can be manufactured by the conventional extrusion procedure.
• the principal application is extrusion of metal alloys. These include aluminium, magnesium, copper, steel, titanium and nickel.
• the system has been described with reference to aluminium since this is where the most commercially feasible applications are likely to be, but the implementation is not exclusively related to aluminium.
• the hot metal billet used can be virtually any metal alloy billet which is heated to the temperature generally used in the hot extrusion process.
• a True Temperature Technology (3T) facility is utilized to record exit temperature of the extruded part. By adjusting the extrusion velocities of the two punches while keeping the extrusion velocity ratio constant, exit temperature is maintained at a reasonable temperature where solution heat treatment (SHT) takes place.
• SHT solution heat treatment
• the target exit temperature for an extruded part is dependent on the metal alloy. For the 6xxx series aluminium alloys, temperatures within a range of 500-530°C for solution heat treatment should be realised at the die exit to achieve optimal mechanical properties.
• the extruded part can be quenched after SHT using water, mist spray or air cooling, depending on the alloy and the final mechanical property requirements.
• a method of extruding a material comprising:
• 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
• a method according to clause 1 comprising moving both of the first and second compression elements to compress the material within the extrusion chamber.
• a method according to clause 2, comprising moving the first compression element and second compression element at different speeds.
• moving the first and second compression elements comprises moving the first and second compression elements along a common axis.
• 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.
• 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.
• a method according to clause 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.
• the material is a metal alloy.
• the metal alloy is aluminium alloy or magnesium alloy.
• the extrusion orifice is provided by an extrusion die that defines the geometry of the orifice.
• a method according to any one of the preceding clauses further comprising providing a guide means adjacent to the extrusion orifice to control curvature of the extruded material.
• a method according to any one of the preceding clauses further comprising providing a mandrel in the extrusion chamber opposite to the extrusion orifice.
• extruding the material through the extrusion orifice comprises extruding the material with a hollow cross-section defined by the mandrel and orifice.
• a method according to any one of the preceding clauses further comprising preheating the material before providing it into the extrusion chamber.
• the extrusion chamber is cylindrical.
• a method according to clause 20 wherein the cross-sectional area of the extrusion chamber is larger than the cross-sectional area of the extrusion orifice.
• an extrusion chamber for receipt of an extrusion material, the extrusion chamber comprising an extrusion orifice;
• first compression element and second compression element are in communication with the interior of the extrusion chamber and being independently movable relative to the extrusion chamber.
• first compression element and second compression element are configured to be moved
• 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.
• first axis and the second axis are parallel to each other.
• the plane of the cross-section of the extrusion orifice is perpendicular to the first and second axes.
• first axis and the second axis are at an angle to one another.
• the plane of the cross-section of the extrusion orifice is perpendicular to a line that bisects the first and second axes.
• an apparatus according to any one of clauses 22 to 32, wherein the extrusion material is a metal alloy.
• An apparatus according to any one of clauses 22 to 35, wherein the extrusion orifice is provided by an extrusion die that defines the geometry of the orifice.
• An apparatus according to any one of clauses 22 to 36, further comprising a guide means adjacent to the extrusion orifice to control curvature of the extruded material.
• An apparatus according to any one of clauses 22 to 37, further comprising a mandrel in the extrusion chamber opposite to the extrusion orifice.
• An apparatus according to any one of clauses 22 to 38, wherein the extrusion material is preheated.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Extrusion Of Metal (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)

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• 2017
  • 2017-05-10 GB GBGB1707519.3A patent/GB201707519D0/en not_active Ceased
• 2018
  • 2018-05-10 US US16/612,232 patent/US20200206794A1/en not_active Abandoned
  • 2018-05-10 WO PCT/GB2018/051260 patent/WO2018206960A1/en not_active Ceased
  • 2018-05-10 EP EP18725607.8A patent/EP3621753B1/en active Active
  • 2018-05-10 JP JP2019561951A patent/JP7270553B2/ja active Active
  • 2018-05-10 CN CN201880046445.XA patent/CN110891703B/zh active Active
  • 2018-05-10 KR KR1020197036499A patent/KR102449312B1/ko active Active
  • 2018-05-10 CN CN202210474856.7A patent/CN114682639B/zh active Active

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