EP4705045A1

EP4705045A1 - Profiled dummy block extrusion devices, methods, and systems

Info

Publication number: EP4705045A1
Application number: EP24798082.4A
Authority: EP
Inventors: Daniel Cooper; Gregory OBERHAUSEN
Original assignee: University of Michigan System
Current assignee: University of Michigan System
Priority date: 2023-04-28
Filing date: 2024-04-26
Publication date: 2026-03-11
Also published as: WO2024227019A1

Abstract

An extrusion device includes an extrusion chamber, a die assembly having an internal cavity in communication with the extrusion chamber, and a dummy block configured to push a billet of material from the extrusion chamber through the internal cavity of the die assembly to form an extruded profile, a surface of the dummy block in contact with the billet of material being a non-uniform surface.

Description

PROFILED DUMMY BLOCK EXTRUSION DEVICES, METHODS, AND SYSTEMS

[0001] This application claims the benefit of U.S. provisional application entitled “Profiled Dummy Block Extrusion Devices, Methods, and Systems,” filed on April 28, 2023, and assigned Serial No. 63/462,720, the entire disclosure of which is hereby expressly incorporated by reference.

BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

[0002] The disclosure relates to devices, methods, and systems for reducing a volume of scrap produced during metal extrusion.

Brief Description of Related Technology

[0003] Metal extrusion is a method of manufacturing metal components. During metal extrusion, a block of the extrusion metal, or billet, having a certain cross section and length starts off as a work piece in an extrusion chamber and is forced to flow through a die of a same or smaller cross-sectional area, thus forming the billet into a new cross section or profile. Numerous cross sections are manufactured by this method. The cross section or profile produced will be uniform over the entire length of the metal extrusion. In one example, a cylindrical billet may be formed into a round part of smaller diameter, a hollow tube, or some other profile. Billets of other shapes are possible.

[0004] Although metal extrusion is possible at room temperature, it is often performed while the billet is at an elevated temperature. Extruding the metal billet while it is at an elevated temperature decreases the yield strength of the metal billet, which leads to a reduction in force required to pass the metal billet through the die of a smaller cross-sectional area. Additionally, extruding the billet material while it is at an elevated temperature may increase the strength of a transverse or charge weld formed between consecutive billets pushed or forced to flow through the die, the transverse or charge welds becoming part of the extruded profile.

SUMMARY OF THE DISCLOSURE [0005] In accordance with one aspect of the present disclosure, an extrusion device includes an extrusion chamber, a die assembly including an internal cavity in communication with the extrusion chamber, and a dummy block configured to push a billet of material from the extrusion chamber through the internal cavity of the die assembly to form an extruded profile. A surface of the dummy block in contact with the billet of material is a non-uniform surface.

[0006] In accordance with another aspect of the present disclosure a system for forming an extruded profile includes an extrusion chamber, a die assembly including an internal cavity in communication with the extrusion chamber, a dummy block, and a shaping chamber. The dummy block is configured to push a shaped billet of material from the extrusion chamber through the internal cavity of the die assembly to form an extruded profile. A surface of the dummy block in contact with the shaped billet of material is a non-uniform surface. The shaping chamber is configured to shape a billet of material into the shaped billet of material.

[0007] In accordance with yet another aspect of the present disclosure, a method of forming an extruded profile includes compressing a billet of material between a first plate having a non-uniform first plate surface configured to contact a first end of the billet of material and a second plate having a non-uniform second plate surface configured to contact a second end of the billet of material to form a shaped billet of material. The method of forming an extruded profile further comprises pushing the shaped billet of material from an extrusion chamber through an internal cavity of a die assembly to form an extruded profile. The shaped billet of material is pushed through the internal cavity of the die assembly by a dummy block having a non-uniform surface in contact with the shaped billet of material.

[0008] In connection with any of the aforementioned aspects, the devices, methods, and systems described herein may alternatively or additionally include any combination of one or more of the following features. The non-uniform surface includes two or more depressions or protuberances. The two or more depressions are formed in a flat surface of the dummy block in contact with the billet of material. One of the two or more depressions has a semi-ellipsoid shape. The two or more depressions include a first depression having a first shape and a second depression having a second shape different than the first shape. The two or more depressions include a first depression having a first size and a second depression having a second size different that the first size. The die assembly further comprises an internal mandrel disposed within the internal cavity and two or more bridges connecting the internal mandrel to an interior surface of the die assembly, the two or more bridges forming two or more portholes between the two or more bridges, and the two or more depressions correspond to the two or more portholes. The non-uniform surface includes a depression and a protuberance. An air vent channel extends from the non-uniform surface through the dummy block. The shaping chamber includes a first plate having a first plate surface configured to contact a first end of the billet of material, the first plate surface being a non- uniform surface and a second plate having a second plate surface configured to contact a second end of the billet of material opposite the first end, the second plate surface being a non-uniform surface. At least one of the first plate and the second plate is configured to translate, compressing the billet of material between the first plate surface and the second plate surface, forming the billet of material into the shaped billet of material. The first plate surface includes two or more depressions configured to form two or more protuberances in a first end of the shaped billet of material. The second plate surface includes two or more protuberances configured to form two or more depressions in a second end of the shaped billet of material. The first plate surface and the second plate surface are complementary. The first plate surface corresponds to the surface of the dummy block. The surface of the dummy block configured to contact the shaped billet of material is a front surface of the dummy block. An area of the front surface of the dummy block is smaller than a cross sectional area of an interior of the extrusion chamber and a side surface of the dummy block includes a recess configured to receive a portion of the shaped billet of material when the shaped billet of material is pushed through the internal cavity of the die assembly. At least one of the first plate includes an air vent channel extending from the first plate surface through the first plate or the second plate includes an air vent channel extending from the second plate surface through the second plate. The method of forming an extruded profile further comprises receiving a portion of the shaped billet of material in a recess in a side of the dummy block as the shaped billet of material is pushed through the internal cavity of the die assembly to form an extruded profile. The compressing the billet of material further comprises forming two or more protuberances on a first end of the shaped billet of material by a non-uniform first plate surface including two or more depressions. The compressing the billet of material further comprises forming two or more depressions in a second end of the shaped billet of material by a non-uniform second plate surface including two or more protuberances. BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0009] For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawing figures, in which like reference numerals identify like elements in the figures.

[0010] Figure 1 illustrates an extrusion device in accordance with one example of the present disclosure.

[0011] Figure 2 illustrates a perspective view of a die assembly in accordance with one example of the present disclosure.

[0012] Figure 3 illustrates a front view of the die assembly of Figure 2 in accordance with one example of the present disclosure.

[0013] Figure 4 illustrates an extruded profile in accordance with one example of the present disclosure.

[0014] Figure 5 is a photograph of a three-dimensional model of a plurality of transverse welds formed in an extruded profile in accordance with one example of the present disclosure.

[0015] Figure 6 illustrates a dummy block including a profiled or non-uniform surface in accordance with one example of the present disclosure.

[0016] Figure 7 is a diagram depicting removal of a back-end defect during a conventional extrusion process.

[0017] Figure 8 is a flow chart for removal of the back-end defect according to the diagram of Figure 7.

[0018] Figure 9 is a diagram depicting extrusion of the back-end defect through a die assembly in accordance with one example of the present disclosure.

[0019] Figure 10 is a flow chart for extrusion of the back-end defect through the die assembly according to the diagram of Figure 9.

[0020] Figure 11 is a graph depicting a volume of an extruded profile including the back- end defect removed from an extruded profile extruded using a dummy block having a non- uniform or profiled surface.

[0021] Figure 12 is a diagram depicting extrusion of a profile using a fluted dummy block in accordance with one example of the present disclosure. [0022] Figure 13 is a flow chart for extrusion of a profile using a fluted dummy block according to the diagram of Figure 12.

[0023] Figure 14 illustrates a fluted dummy block in accordance with one example of the present disclosure.

[0024] Figure 15 illustrates a system for forming an extruded profile in accordance with one example of the present disclosure.

[0025] Figure 16 illustrates a shaped billet of material in accordance with one example of the present disclosure.

[0026] Figure 17 illustrates a method of forming an extruded profile in accordance with one example of the present disclosure.

[0027] While the disclosed die assemblies, dummy blocks, methods, and systems are susceptible of embodiments in various forms, there are illustrated in the drawing (and will hereafter be described) specific embodiments of the invention, with the understanding that the disclosure is intended to be illustrative and is not intended to limit the invention to the specific embodiments described and illustrated herein.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0028] As described above, a transverse or charge weld may be formed in an extruded profile between consecutive billets of material pushed or forced to flow through a die. During metal extrusion, a dummy block may be configured to translate along a length of an extrusion chamber in a series of pushes. During each of the series of pushes, the dummy block may be configured to push or force a billet of material through the die. At the end of each push, the dummy block may retreat or return to its original position and a subsequent billet may be placed in the extrusion chamber to be pushed by the dummy block and extruded through the die.

[0029] Accordingly, during metal extrusion, a first billet of material may be placed into an extrusion chamber. The dummy block may then force a portion of the first billet of material through the die assembly in a first push. At the end of the first push, a portion of the first billet may remain in the extrusion chamber and the dummy block may retreat to its original position. A second billet of material may then be placed in the extrusion chamber and the dummy block may begin a second push. During the second push, one end of the second billet of material may be in contact with the dummy block and an opposite end of the second billet of material may be disposed in the extrusion chamber and in contact with an end of the first billet of material (i.e., the end not already extruded and still in the extrusion chamber).

[0030] Accordingly, an interface between the second billet of material and the first billet of material may begin in the extrusion chamber. Conventionally, an interface between the second billet of material and the first billet of material includes a flat surface of the second billet of material in contact with a flat surface of first billet of material. During the second push of the dummy block, the interface between the second billet of material and the first billet of material may be forced through the die assembly. As the interface between the second billet of material and the first billet of material is forced through the die assembly, the interface between the second billet of material and the first billet of material may be transformed into one or more elongated or tongue shaped transverse welds. A transverse weld may be formed in the extruded profile for each porthole through which the interface between the two billets of material is pushed. The one or more elongated or tongue shaped welds may be formed by differential metal flow velocities across the billet cross-section as the billet flows through the portholes of the die assembly. As the interface between the second billet of material and the first billet of material is pushed through the die assembly, an elongated or tongue shape weld may be formed for each porthole in the die assembly through which the first billet of material and the second billet of material flow.

[0031] During many extruding applications, portions of the extruded profile including the elongated transverse welds formed between consecutive billets of material must be removed from the extruded profile and scrapped, due to the inferior mechanical properties (e.g., yield strength, ultimate tensile stress, hardness, toughness, and the like) in these portions. The transverse weld formed between consecutive billets may have inferior mechanical properties as compared to portions of the extruded profile not including the transverse weld. The transverse weld is a metallurgical defect that forms between consecutively extruded billets of material and can be the most significant source of extrusion scrap, representing an average loss of 20% in standard extruded profiles.

[0032] Extrusion devices, methods, and systems for reducing the length of a transverse weld formed in an extruded profile between consecutive billets of material, and thus reducing the amount of extrusion scrap, are described. The devices, systems, and methods described herein may include a dummy block having a profiled or non-uniform surface configured to contact and push a billet of material through the die assembly. The non-uniform surface of the dummy block may reduce the length of a transverse weld in an extruded profile formed between consecutive billets of material by accounting for differential metal flow velocities across a cross-section of the billet of material as the billet of material is pushed through the die assembly. Accordingly, a non-uniform shape of the surface of the dummy block may be designed in consideration of the die assembly and/or the desired shape of the profiled to be extruded. The extrusion devices, methods, and systems described herein may also decrease the quantity of scrap created from the removal of the back-end defect from an extruded profile. The new metal flow created by the profiled dummy blocks may concentrate the conglomeration of oxides and spinels that form the backend defect into a smaller volume than a volume including the oxides and spinels when a profile is extruded using a flat dummy block.

[0033] The extrusion device includes an extrusion chamber configured to receive a billet of material. The extrusion device further includes a die assembly configured to form an extruded profile having a desired shape and/or size. The die assembly may dictate size and shape of a profile extruded by the extrusion device. Different die assemblies may be used to form different extruded profiles having different sizes, different shapes, and different interior hollow sections. The die assembly may be disposed at one end of the extrusion chamber and includes an internal cavity that is in communication with the extrusion chamber. The extrusion device further includes a dummy block configured to push a billet of material from the extrusion chamber through the internal cavity of the die assembly. A surface of the dummy block configured to contact the billet of material may be a profiled or non-uniform surface as described above. The profiled or non-uniform surface may be selected or designed to reduce the length of one or more transverse welds between consecutive billets of material in an extruded profile. Accordingly, a shape of the profiled or non-uniform surface may vary depending on the die assembly and the extruded profile to be formed. Accordingly, the profiled or non-uniform surface may have various shapes. In some examples, the non- uniform surface of the dummy block may include one or more depressions. In some examples, the one or more depressions may be formed in a flat surface of the dummy block in contact with the billet of material. In some examples, one or more of the depressions may have a semi-ellipsoid shape. In some examples, the non-uniform surface may include two or more depressions having different shapes. For example, the non-uniform surface may include a first depression having a first shape and a second depression having a second shape different than the first shape. In some examples, the non-uniform surface may include depressions having different sizes. For example, the non-uniform surface may include a first depression having a first size and a second depression having a second size different than the first size. In some examples, the die assembly may include an internal mandrel and one or more bridges connecting an inner surface of the die assembly to the internal mandrel. The one or more bridges may form one or more portholes between the one or more bridges and an interior surface of the die assembly. In some examples, the one or more depressions may correspond to the one or more portholes.

[0034] In some examples, the dummy block including the non-uniform surface may be a fluted dummy block. The fluted dummy block may include one or more recesses formed in a side surface or side surfaces of the dummy block. The one or more recesses may be configured to receive a portion of the billet of material as the billet of material is pushed through the die assembly. The one or more recesses may be configured to receive a portion of the billet of material including the billet skin. The billet skin is a portion of the billet of material around or along an exterior surface of the billet of material that includes a conglomeration of oxides and other contaminants.

[0035] In some examples, systems and methods for forming an extruded profile may include a shaping chamber (separate from the extrusion press) configured to form or shape the billet of material into a shaped billet of material prior to loading the shaped billet into the extrusion chamber of the extrusion press. The shaped billet of material may include a shaped billet first end or a shaped billet second end formed to have a non-uniform surface. The shaping chamber may include a first plate having a first plate surface configured to contact a first end of the billet of material and a second plate having a second plate surface configured to contact a second end of the billet of material. In some examples, at least one of the first plate surface and the second plate surface may be a non-uniform surface. In some examples, at least one of the first plate and the second plate are configured to translate compressing the billet of material between the first plate surface and the second plate surface, forming the billet of material into a shaped billet of material.

[0036] In some examples, the billet may be formed into a shaped billet in-situ, within the extrusion chamber. When the billet is formed into a shaped billet in-situ, the profiled dummy block may comprise the first plate as described above. Further, when forming the shaped billet in-situ there may be no second plate. Instead, an end of the billet opposite the end of the billet contacting the profiled dummy block is formed against the back end or butt of the previously extruded billet. In some examples, when the billet is formed into a shaped billet in- situ axial and radial tapered heating of the billet may be used to soften the end of the new billet contacting the butt or back end of the previously extruded billet, allowing the new billet to form around the profiled butt or back end of the previously extruded billet. [0037] In some examples, the billet may be formed into a shaped billet within the extrusion chamber, with the profiled dummy block forming the first plate as described above, and there being a temporarily placed second plate between the end of the extrusion chamber and die. In these examples, the profiled dummy block may translate as the second plate remains stationary. As the dummy block translates, the billet may be compressed and formed into a profiled, shaped billet. After the shaped billet is formed, the profiled dummy block may retract, and the extrusion chamber may separate from the die and the second plate may be removed. The extrusion chamber may separate from the die as is common in front loading extrusion presses. The extrusion chamber and die may then close and extrusion of the profiled billet through the die may proceed by translating the profiled dummy block towards the die.

[0038] The extrusion devices, systems, and methods described herein may be used alone or in combination with other known or later developed devices, methods, and systems for forming an extruded profile.

[0039] The extrusion devices, systems, and methods described herein are configured to reduce a quantity of scrap generated during metal extrusion. The extrusion devices, systems, and methods described herein are configured to reduce the length of a transverse weld formed in an extruded profile between consecutive billets of material, thus reducing the length of a portion of the extruded profile that must be removed from the extruded profile and scrapped. The extrusion devices, systems, and methods described herein may include a profiled or non-uniform dummy block configured to compensate for differential metal flow velocities across an interface between consecutive billets of material as the interface is pushed through the die assembly, reducing the length of transverse welds formed in the extruded profile. The extrusion devices, methods, and systems described herein may also decrease the quantity of scrap created from the removal of the back-end defect from an extruded profile. The new metal flow created by the profiled dummy blocks may concentrate the conglomeration of oxides and spinels that form the backend defect into a smaller volume than a volume including the oxides and spinels when a profile is extruded using a flat dummy block.

[0040] Although described below in connection with metal extrusion, the disclosed die assembly devices, methods, and systems are also useful in various other applications. For example, the disclosed die assembly devices, methods, and systems may be used in connection with other materials, such as plastic extrusion and food processing extrusion (e.g., cooling and/or filling the interior of extruded foods). [0041] FIG. 1 illustrates an extrusion device 100 in accordance with one example of the present disclosure. As illustrated in FIG. 1 , the extrusion device 100 includes an extrusion chamber 110, a die assembly 120, and a dummy block 130. The extrusion chamber 110 may be configured to accommodate a billet of material 140 to be extruded through the die assembly 120. The extrusion chamber 110 may have a shape corresponding to the shape of the billet of material 140. In some examples, the extrusion chamber 110 may have a cylindrical shape (i.e., circular cross section) or a rectangular prism or cuboid shape (i.e., square or rectangular cross section). Other shapes are possible. The extrusion chamber 110 may include chamber walls that surround the billet of material 140 as the billet of material 140 is fed into and extruded through the die assembly 120.

[0042] The extrusion device further includes a dummy block 130. The dummy block 130 may be disposed in the extrusion chamber 110. The dummy block 130 may be configured to push or force a billet of material 140 from inside the extrusion chamber 110 through the die assembly 120 to form the extruded profile. In some examples, the extrusion device may further include a stem 150 attached to the dummy block 130. The stem 150 may extend telescopically (i.e., linearly inside the extrusion chamber 110). As the stem 150 extends, the dummy block 130 may force the billet material from inside the extrusion chamber 110 through the die assembly 120 to form the extruded profile. The stem 150 may be configured to retract from the extended position in order to create space within the extrusion chamber 110 for a subsequent billet to be placed in the extrusion chamber 110 and pushed through the die assembly 120. A surface of the dummy block configured to contact a billet of material 140 as the billet of material 140 is pushed through the die assembly 120 may be a profiled or non-uniform surface. The non-uniform surface of the dummy block 130 is described below in detail with reference to FIG. 6.

[0043] Referring to FIGS. 1 -3, the extrusion device further includes a die assembly 120. The die assembly 120 may include an inflow end 121 , an outflow end (e.g., opposite the inflow end 121 ), and an internal cavity 122 extending between the inflow end 121 and the outflow end. The inflow end 121 of the die assembly 120 may be in communication with the extrusion chamber 110 and may be configured to receive a billet of material 140. The internal cavity 122 may be configured to convey the billet of material 140, received at the inflow end 121 through one or more portholes 123, through the die assembly 120. The internal cavity 122 forms an interior surface 124 of the die assembly 120. The die assembly 120 may further include one or more internal mandrels 125 disposed within the internal cavity 122 and connected or coupled to the interior surface 124 of the die assembly 120 via one or more bridges 126. The portholes 123 are the openings or inlets of the internal cavity 122 separated by the bridges 126.

[0044] The inflow end 121 of the die assembly 120 may be configured to receive a block or billet of material 140 (the “billet material”). The billet material may be a material from which an extruded profile is manufactured. In some examples, the billet material may be a metal. In some examples, the billet material may be aluminum or an aluminum alloy. For example, the billet material may be aluminum alloys AA6060, AA6061 , AA6063, or AA6082. In other examples, the billet material may be a higher strength aluminum alloy, such as a 7000 series aluminum alloy (e.g., AA7005, AA7055, and the like). The billet material is not limited to the above-mentioned alloys or alloy ranges. It should be appreciated that an alloy belonging to any range of alloys may be used. In other examples, the billet material may be copper, steel, magnesium, lead, or any alloy thereof. In yet further examples, the billet material may be plastic or food product.

[0045] The billet material may be at an elevated temperature when it is received by the inflow end 121 of the die assembly 120. Receiving the billet material at an elevated temperature reduces the yield strength of the billet material and subsequently reduces the force required to feed the billet material through the die assembly 120. The temperature of the billet material when it is received by the inflow end 121 of the die assembly 120 may depend on the billet material used. For example, if the billet material is aluminum or an aluminum alloy, the billet material may be between 700 °F and 930 °F when it is received by the inflow end 121 of the die assembly 120. The billet material may be received by the inflow end 121 of the die assembly 120 at other temperatures as well. During the extrusion process, the plastic deformation of the material as it flows through the die may cause a further increase to the material temperature and cause it to transform into a single-phase solid solution.

[0046] The outflow end of the die assembly 120 is located opposite the inflow end 121 . The outflow end of the die assembly 120 may be configured to extrude the billet material into the extruded profile. The outflow end of the die assembly 120 may include an opening (e.g., an orifice) having a shape corresponding to a desired outer perimeter of the extruded profile. When the billet material reaches the outflow end of the die assembly 120 it may be extruded (e.g., pushed, thrust, forced) through the opening in the outflow end of the die assembly 120. Accordingly, while passing through the outflow end, the billet material may be forced into the shape of the opening in the outflow end (e.g., a shape corresponding to a desired outer perimeter of the extruded profile). After passing through the outflow end, the billet material may become an extruded profile having an outer perimeter corresponding to the shape of the opening in outflow end of the die assembly 120. The shape of the opening in the outflow end may be variously modified to create extruded profiles having various shapes and sizes.

[0047] The internal cavity122 of the die assembly 120 extends from the inflow end 121 of the die assembly 120 to the outflow end of the die assembly 120. The internal cavity 122 may be configured to convey the billet material from the inflow end 121 of the die assembly

120 to the outflow end of the die assembly 120. The internal cavity 122 may include one or more portholes 123 (e.g., openings, inlets) disposed between the bridges 126 in the die assembly 120. As the billet of material 140 is pushed through the internal cavity 122 of the die assembly 120, the billet of material 140 may flow around the bridges 126 through the one or more portholes 123. When an interface between consecutive billets of material (i.e., a first and second billet of material 140) is pushed through a porthole of the die assembly 120, differential metal flow velocities may cause the interface between the consecutive billets of material to be elongated, resulting in a tongue shaped transverse weld between the consecutive billets of material in the extruded profile. Differential metal flow velocities may cause an elongated or tongue shaped weld to be formed in the extruded profile for each porthole 123 through which the interface between consecutive billets of material is pushed. Accordingly, a number of portholes 123 in the die assembly 120 may correspond to a number of elongated transverse welds formed in the extruded profile. The die assembly 120 further includes an interior surface 124 formed by the internal cavity 122 of the die assembly 120. The interior surface 124 may extend around the internal cavity 122 from the inflow end

121 to the outflow end of the die assembly 120. The internal cavity 122 may vary in size and shape and may or may not be uniform from the inflow end 121 to the outflow end.

[0048] An internal mandrel 125 may be configured to form an interior hollow section in an extruded profile. As the billet material moves through the internal cavity 122 of the die assembly 120, the billet material may be forced to move around the internal mandrel 125. In other words, the internal mandrel 125 is held in place by the bridges 126 and over which the billet material flows to form the internal shape of the profile. As the billet material is extruded through the outflow end of the die assembly 120, the billet material may be forced to flow both through the opening in the outflow end and around the internal mandrel 125 of the die assembly 120. In some examples, the internal mandrel 125 may extend into the opening formed in the outflow end. As the billet material passes through the opening in the outflow end of the die assembly 120, the billet material may move past (e.g., be extruded past) the end of the internal mandrel 125. As the billet material moves past the end of the internal mandrel 125, an interior hollow section may be formed in the extruded profile. The internal mandrel 125 may form an interior hollow section in the extruded profile corresponding to the size and location of the internal mandrel 125. The size and location of the internal mandrel 125 may be variously modified to create interior hollow sections of various shapes and sizes within the extruded profile.

[0049] In some examples, the die assembly 120 may include one or more internal mandrels 125 disposed within the internal cavity 122. Each of the one or more internal mandrels 125 may create a respective interior hollow section in the extruded profile as the billet material is extruded through the outflow end of the die assembly 120 and around each of the one or more internal mandrels 125. Multiple internal mandrels 125 may be used in order to create complex extruded profiles having multiple interior hollow sections. For example, two mandrels may be used to form an extruded profile including two interior hollow sections.

[0050] FIGS. 2 and 3 illustrate a die assembly 120 in accordance with one example of the present disclosure. The die assembly 120 as illustrated in FIGS. 2 and 3 may be used to form the extruded profile illustrated in FIG. 4. The die assembly 120 of FIGS. 2 and 3 is provided merely by way of example to illustrate one die assembly 120 that may be included in the extrusion device. Various different die assemblies may be included in the extrusion device to form extruded profiles having various shapes and sizes.

[0051] Referring to FIGS. 2 and 3, the die assembly 120 in accordance with one example of the present disclosure may include four internal mandrels 125 configured to form an extruded profile having four interior hollow sections. The four internal mandrels 125 of the die assembly 120 illustrated in FIGS. 2 and 3 may be configured to form the four interior hollow sections of the extruded profile illustrated in FIG. 4. Although a die assembly 120 including four internal mandrels 125 is illustrated, a die assembly 120 including any number of internal mandrels 125 may be used. Further, the die assembly 120 of FIGS. 2 and 3 includes a plurality of bridges 126 connecting the four internal mandrels 125 to an interior surface 124 of the die assembly 120. Each of the bridges 126 may extend from an internal mandrel 125 to an interior surface 124 of the die assembly 120, connecting the internal mandrel 125 to the interior surface 124 of the die assembly 120. In some examples, two or more bridges 126 may connect a single internal mandrel 125 to the interior surface 124 of the die assembly 120. For example, multiple bridges 126 may extend from a single internal mandrel 125 similar to multiple spokes extending from the hub of a wheel. The die assembly interior surface 124 of the die assembly 120. Further, the die assembly 120 of FIGS. 2 and 3 includes seven portholes 123 formed between the bridges 126. However, the present disclosure is not limited thereto. A die assembly 120 included in the extrusion device may include any number of bridges 126 and any number of portholes 123 between the bridges 126.

[0052] Referring to FIG. 4, an extruded profile 170 in accordance with one example of the present disclosure is illustrated. An extruded profile 170 that may be formed using the die assembly 120 of FIGS. 2 and 3 is illustrated. As shown in FIG. 4, the extruded profile 170 may be divided into a plurality of extruded profile sections 171-177. Each of the extruded profile sections 171-177 may correspond to a porthole, such as a porthole 123 shown in FIG. 3 in the die assembly 120 as shown in FIGS. 2 and 3 used to form the extruded profile 170 and may represent a portion of the extruded profile 170 formed by metal (i.e., a portion of the billet of material) flowing through the corresponding porthole 123. Accordingly, the number of extruded profile sections may correspond to the number of portholes included in a die assembly used to form the extruded profile. Further, because the extruded profile sections 171-177 each correspond to a porthole, such as a porthole 123 shown in FIG, 3 through which metal is pushed to form the portion of the extruded profile 170 included in the respective extruded profile section 171-177, each of the extruded profile sections 171-177 may include or represent an elongated or tongue shaped transverse weld between consecutive billets of material pushed through the respective porthole 123. Referring to FIG. 4, an extruded profile including seven extruded profile sections (171-177) corresponding to the seven portholes 123 included in the die assembly 120 of FIGS. 2 and 3 is illustrated. Each of the seven extruded profile sections 171 -177 illustrated in FIG. 4 may include or represent a transverse weld formed between consecutive billets of material as the interface between consecutive billets of material is pushed through a porthole 123 as shown in FIG. 3 corresponding to the extruded profile section 171 -177.

[0053] Referring to FIG. 5, a three-dimensional model 190 or representation of a plurality of transverse welds formed in an extruded profile is illustrated. In some examples, numerical models , for example, finite element models or analysis, computational fluid dynamic models, finite difference methods or models, finite volume methods or models, or experimental models may be used to construct the three-dimensional model illustrated in FIG. 5. FIG. 5 illustrates a model 190 of a plurality of transverse welds 191 formed in the extruded profile of FIG. 4 as an interface between consecutive billets of material is pushed or extruded through the die assembly 120 of FIGS. 2 and 3. As illustrated in FIG. 5, the model includes seven transverse welds 191 . Each of the seven transverse welds illustrated in FIG. 5 may be formed as an interface between consecutive billets of material is pushed through one of the seven portholes 123 illustrated in FIG. 3 of the die assembly 120 of FIGS. 2 and 3. The number of transverse welds in the extruded profile may correspond to the number of portholes 123, shown in FIG. 3, in the die assembly 120. For example, a die assembly including four portholes may be used to form an extruded profile including four transverse welds.

[0054] Referring to FIG. 6, a dummy block 130 including a non-uniform or profiled surface 131 in accordance with one example of the present disclosure is illustrated. As illustrated in FIG. 6, the dummy block 130 includes a non-uniform surface 131. The non-uniform surface 131 may be configured to contact a billet of material as the billet of material is pushed through the internal cavity of the die assembly by the dummy block 130. The non-uniform surface 131 may include one or more depressions 132 (e.g., concavity, dent, divot, pit, and the like). In some examples, as illustrated in FIG. 6, the one or more depressions 132 may be formed in an otherwise flat surface of the dummy block 130. In other examples, one or more depressions 132 may be formed in an otherwise concave or convex surface of the dummy block 130.

[0055] The non-uniform surface 131 of the dummy block 130 may be configured to reduce the length of one or more transverse welds formed in an extruded profile. The non-uniform surface 131 may be configured to reduce a differential (e.g., a range) of metal flow velocities through each of the portholes, such as the portholes 123 shown in FIG. 2 (but other portholes may be used) of the die assembly, such as the die assembly 120 shown in FIGS. 2 and 3 (but other die assemblies may be used). As a portion of the billet of material flows through a porthole in the die assembly 120, an area through which the portion of the billet of material may flow may be gradually restricted or decreased in size. Accordingly, as the billet of material is pushed through the die assembly, a portion of the billet of material may contact any one of the interior surface of the die assembly, a bridge, or an internal mandrel. As these portions of the billet of material contact the die assembly, shear stresses between the billet and extrusion chamber and die result in differential metal flow velocities through each of the portholes. Accordingly, in some examples, portions of the billet of material 140 flowing through a center of the porthole may flow through the porthole (and thus the die assembly) more quickly than portions of the billet of material flowing through the porthole at or near a perimeter of the porthole. [0056] The non-uniform surface 131 may be configured to compensate for the differential metal flow velocities through the die ports, reducing a differential of metal flow velocities through the die ports. Accordingly, reducing a differential or range of metal flow velocities through each of the portholes may reduce a length (e.g., along the extruded profile) of the elongated or tongue shaped transverse weld formed in the extruded profile as an interface between consecutive billets of material is pushed through each porthole.

[0057] Accordingly, the non-uniform surface 131 of the dummy block 130 may be designed or selected in consideration of the die assembly, for example, the die assembly 120 shown in FIGS. 2 and 3 (but other die assemblies may be used) and the extruded profile, for example, the extruded profile 170 (but other extruded profiles may be used) to be formed by the die assembly 120. A design process for determining the non-uniform surface 131 of the dummy block 130 may include performing numerical methods or modeling (e.g., finite element modeling) of the conventional extrusion process to determine a velocity flow field for points throughout a billet of material. Next, points along the conventional flat interface between consecutive billets of material can be iteratively tracked (over time for a set time, 7) through the extrusion process using the velocity field to determine the shape of a conventional transverse weld between consecutive billets of material. Next, a new plane of points corresponding to a shortened transverse weld can be tracked backward (over time, for the same set time, 7) using the same velocity flow field to define the shape of an interface between consecutive billets of material that results in a shortened transverse weld.

[0058] In converse, in some examples, the same process may be used to determine a non- uniform surface 131 of the dummy block 130 that increases the length of one or more transverse welds in the billet of material. In some examples, it may be desirable to lengthen the one or more transverse welds, spreading them throughout an extruded profile. Lengthening the transverse welds may be desirable in examples where a portion of the extruded profile including the transverse welds is not removed. In these examples, lengthening the transverse weld may increase the local surface expansion at the interface, distributing the broken surface oxide fragments (that do not weld together) across a greater area, and potentially increasing the local weld strength as a result. In these examples, the non-uniform surface 131 of the dummy block 130 may include one or more protuberances, projections, or bulges instead of the one or more depressions 132. Further, in these examples, the one or more protuberances may be formed on a convex surface of the dummy block 130. [0059] In some examples, the non-uniform surface 131 of the dummy block 130 may include both depressions 132 and protuberances. The non-uniform surface 131 of the dummy block 130 may include one or more depressions 132 configured to shorten the length of transverse welds formed by one or more portholes and one or more protuberances configured to lengthen transverse welds formed by one or more portholes. In these examples, the relatively long transverse welds may be shortened by depressions 132 and relatively short transverse welds may be lengthened by protuberances so as to create transverse welds having substantially similar lengths.

[0060] In some examples, the shape of an interface between consecutive billets of material that results in a shortened transverse weld corresponds to the shape of the non-uniform surface 131 of the dummy block 130 that results in a shortened transverse weld. As a billet of material is pushed through the internal cavity of the die assembly, the non-uniform surface 131 of the dummy block 130 contacts an end (e.g., back end) of the billet, shaping the back end of the billet. As the billet of material is pushed through the internal cavity of the die assembly, the back end of the billet of material in contact with the non-uniform surface 131 may be shaped so as to have a shape complimentary to the non-uniform shape of the dummy block 130. Accordingly, a subsequent billet of material may be pushed into the back end of the billet of material having a shape complimentary to the non-uniform surface 131 of the dummy block 130, resulting in an interface between consecutive billets of material having a shape corresponding to the shape of the non-uniform surface 131 of the dummy block 130.

[0061] In some examples, the shape of an interface between consecutive billets of material that results in shortened transverse welds may be substantially similar to the shape of the non-uniform surface 131 of the dummy block 130 that results in a shortened transverse weld. When the shaped or profiled billet is formed in-situ between a profiled dummy block 130 and the profiled back end or butt of the previously extruded billet, the interface between the consecutive billets of material may begin as a flat surface against the profiled surface of the back end of the previously extruded billet. The shape of the profiled back end of the previously extruded billet may correspond to the shape of profiled dummy block 130. During extrusion the flat surface of the subsequent or second billet of material 140 may deform around the profiled back end of the previously extruded or first billet. The profiled back end of the previously extruded billet may deform slightly as the flat surface deforms around the profiled back end of the previously extruded profile, resulting in an interface between consecutive billets of material that is substantially similar to the shape of the non-uniform surface 131 of the profiled dummy block 130. [0062] After the shape of the non-uniform surface 131 of the dummy block 130 that results in a shortened transverse weld is determined, the shape may be rationalized, or modified, before being implemented. For example, the shape of the non-uniform surface 131 may be modified in the design stage to ensure that the dummy block 130 may be removed from the end of the billet of material without altering the shape of the end of the billet of material. Additionally, during the design stage, the non-uniform surface 131 of the dummy block 130 may be modified to ensure that the shape of the non-uniform surface 131 does not plastically deform or excessively elastically deform during extrusion. In some examples, the shape of the non-uniform surface 131 may be modified so as to be more easily formed in the dummy block 130 using conventional tooling.

[0063] Accordingly, the number, size, and shape of the one or more depressions 132 or bulges in the non-uniform surface 131 of the dummy block 130 may vary according to the shape of the non-uniform surface 131 determined to reduce the length or increase the strength of the transverse welds and the any subsequent modifications to the shape of the non-uniform surface 131. In some examples, as illustrated in FIG. 6, the one or more depressions 132 may have a semi-ellipsoid shape. In other examples, the one or more depressions 132 may have semi-spherical shape, a conical shape, a frustoconical shape, a rectangular shape, a tetrahedron shape, or the like. In some examples, the non-uniform surface 131 may include depressions 132 having two or more different shapes. In some examples, as illustrated in FIG. 6, the non-uniform surface 131 may include depressions 132 having two or more different sizes.

[0064] Additionally, the number of depressions 132 in the non-uniform surface 131 may vary. In some examples, the number of depressions 132 in the non-uniform surface 131 may correspond to a number of portholes, for example, the portholes 123 shown in FIG. 2 (but other portholes may be used in the die assembly, for example, the die assembly 120 shown in FIGS. 2 and 3 (but other die assemblies may be used) (as in FIG. 6, corresponding to the die assembly 120, extruded profile 170, and conventional transverse weld shapes 191 shown in FIGS. 3, 4 and 5 respectively). In these examples, each of the depressions 132 may compensate for a differential metal flow velocity through one of the portholes, for example, the portholes 123 shown in FIG. 3 (but other portholes may be used) in the die assembly, for example, the die assembly 120 shown in FIGS. 2 and 3 (but other die assemblies may be used). In some examples, the number of depressions 132 in the non- uniform surface 131 may not exceed the number of portholes in the die assembly. In some examples, the non-uniform surface 131 may include fewer depressions 132 than the number of portholes included in the die assembly.

[0065] Referring to FIG. 6, a non-uniform or multi-profile surface 131 including a plurality of depressions 132 configured to reduce the length of transverse welds formed in the extruded profile, for example, the extruded profile 170 of FIG. 4 (but other extruded profiles may be used) by the die assembly, for example, the die assembly 120 of FIGS. 2 and 3 (but other die assemblies 120 may be used) is illustrated. In this example, the non-uniform surface 131 of the dummy block 130 includes seven depressions 132 corresponding to the seven portholes, for example, portholes 123 as shown in FIG. 3 (but other portholes may be used), in the die assembly, for example, the die assembly 120 as shown in FIGS 2 and 3 (but other die assemblies may be used. However, in some examples, the number of depressions 132 in the dummy block 130 may be fewer than the number of portholes included in the die assembly. In some examples, during modification or rationalization of the non-uniform surface 131 of the dummy block 130 as described above, the non-uniform shape of the surface of the dummy block 130 may be modified. In some examples, the non-uniform surface 131 of the dummy block 130 may be modified to exclude one or more features or depressions 132 in the non-uniform surface 131. One or more features or depressions 132 may be excluded from the non-uniform surface 131 due to anticipated deformation in the dummy block 130, impracticality of forming the feature or depression in the non-uniform surface 131 (e.g., due to size, shape), lack of need or desire to shorten a specific transverse weld formed by the corresponding porthole, or the like. Accordingly, in some examples, a non-uniform surface 131 of the dummy block 130 may include fewer depressions 132 than portholes included in a corresponding die assembly. In some examples, the non-uniform surface 131 may have fewer depressions 132 than the die assembly has portholes, as it may be determined that it is only desirable to reduce the length of one or more transverse welds having a relatively long length as compared to other transverse welds. In other examples, the dummy block 130 may include more depressions 132 than portholes included in a corresponding die assembly.

[0066] In some examples, a non-uniform or multi-profile surface of a dummy block 130 may reduce the length of transverse welds formed in extruded profiles using various die assemblies. For example, the non-uniform or multi-profile surface may reduce the length of transverse welds formed in extruded profiles by various dies configured to form extruded profiles of different sizes having the same shape. In another example, the non-uniform or multi-profile surface may reduce the length of transverse welds formed in extruded profiles by various dies configured to form extruded profiles of different shapes have the same or a substantially similar shape. A non-uniform surface 131 of a dummy block 130 selected to reduce the length of the transverse welds in an extruded profile having a first shape and size may also reduce the length of the transverse welds formed in a different extruded profile having the first shape but a second, different size. For example, the non-uniform surface 131 of the dummy block 130 selected or designed in consideration of an extruded profile having a first size may also reduce the length of the transverse welds formed in a different extruded profile having the same shape, but a different smaller size. Similarly, the non-uniform surface 131 of the dummy block 130 selected or designed in consideration of an extruded profile having a first size may also reduce the length of the transverse welds formed in a different extruded profile having the same shape, but a different larger size. Accordingly, the same non-uniform surface 131 of a dummy block 130 may be used to reduce the length of transverse welds in multiple different extruded profiles of the same shape in varying sizes. Using the same dummy block 130, including the same non-uniform surface 131 , to form extruded profiles of varying sizes may reduce the frequency with which a dummy block 130 must be changed during extrusion operations, improving the efficiency of the extrusion operation. While a non-uniform or multi-profile surface of a dummy block 130 is described above with respect to extruded profiles having different sizes and/or shapes, the shape of the die assembly determines the flow of metal through the die assembly and thus the length of transverse welds formed in the extruded profile. Accordingly, the non-uniform or multiprofiled surface of the dummy block 130 may reduce the length of transverse welds in extruded profiles formed with different die assemblies configured to form extruded profiles having different shapes and/or sizes. Referring to FIG. 6, the dummy block 130 may further include one or more air vent channels 133. The air vent channels 133 may extend through the dummy block 130 from a non-uniform or profiled surface of the dummy block 130 to an opposite side of the dummy block 130. The air vent channels 133 may be configured to allow air to travel through, preventing air from being trapped in the billet of material during extrusion. In some examples, an opening of the air vent channels 133 may be disposed in the depressions 132 formed in the non-uniform surface 131. In other examples, an opening of the air vent channels 133 may be disposed adjacent to one or more protuberances in the non-uniform surface 131 of the dummy block 130. The air vent channels 133 may be formed using gun drilling or micro drilling. An opening of the air vent channel on the non-uniform surface 131 of the dummy block 130 may have a sufficiently small area so as to prevent the billet of material from flowing into the opening during extrusion. For example, the openings may have an area less than 1 square millimeter. In another example, the openings may have an area less than .25 square millimeters. The number and size of air vent channels 133 may vary. For example, the number and size of the air vent channels 133 may vary based on the die assembly and the shape of the profile to be extruded (e.g., thickness of profile walls), a volume of trapped air, and/or a speed of the extrusion stroke of the dummy block 130. The shape of the air vent channels 133 may vary. For example, the air vent channels 133 may have a cylindrical shape, a rectangular shape, or the like. In some examples, a cross sectional area of the air vent channels 133 may vary along the length of the air vent channels 133. For example, a cross sectional area may gradually increase as a distance away from the non-uniform surface 131 of the dummy block 130 increases. In some examples, one or more air vents may extend through a portion of the dummy block stem.

[0067] In some examples, burping may be performed to release air trapped between the dummy block 130 and the billet of material. During extrusion, burping occurs when the translation of the dummy block 130 stops, and the dummy block 130 is retracted a small distance allowing air trapped between the dummy block 130 and the billet of material to be released. Burping may be performed both when air vent channels 133 are included in the dummy block 130 and when air vent channels 133 are not included in the dummy block 130.

[0068] In some examples, burping may be performed to release air trapped between the billet loaded into the extrusion chamber and either the profiled butt of a previously extruded billet or a second plate with a non-uniform surface 131 . During extrusion, burping occurs when the translation of the dummy block 130 stops, and the extrusion container is retracted a small distance from the die or second plate, allowing air trapped between the newly loaded billet and the second plate or previously extruded billet butt to be released. Burping may be performed both when air vent channels 133 are included in the dummy block 130 and second plate and when air vent channels 133 are not included in the dummy block 130 and second plate.

[0069] In some examples, the stem may extend telescopically during extrusion. In some examples, as the stem extends telescopically, a shape of the dummy block 130 may change. In these examples, the shape of the dummy block 130 may change during extrusion in order to further reduce the length of transverse welds formed in the extruded profile and/or a volume of the extruded profile including the back-end defect.

[0070] Referring to FIG. 7, a diagram illustrating removal of a back-end defect 201 during a conventional extrusion process is illustrated. Referring to FIG. 7, during metal extrusion an exterior surface of the billet of material 140 extruded includes a conglomeration of oxides and other contaminants. The oxides and other contaminants may be deposited in the exterior of the outer surface as the hot outer surface of the billet of material 140 reacts with oxygen in the air during casting of the billet of material 140. A thickness of the billet skin or exterior surface of the billet including oxides and other contaminants may range from roughly 0.05 mm to 0.5 mm. The thickness of the skin or exterior surface of the billet material 140 including oxides and other contaminants may vary depending on the quality of the composition of the billet and the quality of the casting of the billet of material 140. As a billet of material 140 is pushed through the internal cavity of the die assembly 120, the billet skin may accumulate at the back end of the billet. Differential metal flow velocities across a cross-section of the billet may cause the billet skin to accumulate at the back end of the billet. The accumulation of the billet skin at the back end of the billet may be referred to as the back-end defect 201 . The back-end defect 201 is a metallurgical defect that must be removed from an extruded profile 202 due to its inferior mechanical properties (e.g., yield strength, ultimate tensile stress, hardness, toughness, and the like).

[0071] Referring to FIG. 8, a flow chart for removing the back-end defect 201 according to the diagram of FIG. 7 is illustrated in accordance with one example of the present disclosure. Referring to FIGS. 7 and 8, in a first act S101 , a first billet of material 140 is extruded or pushed through the die assembly 120. Referring to FIGS. 7 and 8, in s second act S103, during a conventional metal extrusion process, after each push by the dummy block 230, the back-end defect 201 is sheared off and scrapped. Further, referring to FIGS. 7 and 8, in a third act S105, a new or second billet of material 140 may be placed in the extrusion chamber 110 and during a fourth act S107, the new or second billet of material 140 may be extruded through the die assembly 120. However, during metal extrusion using a profiled dummy block including a non-uniform surface as described herein, the back end of the dummy block, including the back-end defect 201 , may not be sheared off, because the back end of the billet of material 140 includes a surface complimentary to the non-uniform surface of the dummy block configured to define an interface between consecutive billets of material.

[0072] Referring to FIGS. 9 and 10, a diagram depicting extruding a back end defect 301 through a die assembly 120 and a flow chart for extruding the back end defect 301 through the die assembly 120 according to the diagram of FIG. 9, respectively, are illustrated in accordance with examples of the present disclosure. In a first act S201 , a first billet of material is extruded or pushed through the die assembly 120. Still referring to FIGS. 9 and 10, in a second act S203, the back end defect 301 may be consolidated within a rear of the first billet as the first billet is extruded through the die assembly 120. Accordingly, in some examples, as illustrated in FIGS. 9 and 10, in a third act S205 a new billet 140 may be loaded into the extrusion chamber 110 and in a fourth act S207, the back-end defect 301 may be pushed or extruded through the internal cavity of the die assembly 120. After being pushed through the internal cavity of the die assembly 120, the back-end defect 301 may be disposed within the extruded profile 302 adjacent to and in front of the transverse weld 303 formed between consecutive billets of material. After being pushed through the die assembly 120, into the extruded profile 302, a portion of the extruded profile 302 including the back- end defect 301 may be removed from the extruded profile 302 together with the portion of the extruded profile 302 including the transverse weld 303. In some examples, a portion of the extruded profile 302 including the back-end defect 301 may be elongated as the back- end defect 301 is pushed through the die assembly 120 into the extruded profile 302. However, even though a portion of the extruded profile 302 including the back-end defect 301 may be elongated, a total volume of scrap generated using a profiled dummy block 130 including a non-uniform surface as described herein may be less than a total volume of scrap generated using a conventional extrusion process including a flat dummy block 130. A volume of the extruded profile 302 including the back-end defect 301 pushed through the die assembly 120 into the profile and the transverse weld 303 formed by a dummy block 130 including a non-uniform surface as described herein may be less than a volume of the back- end defect (e.g., 201) removed before being pushed through die assembly 120 and a transverse weld formed by a dummy block 130 including a conventional flat surface.

[0073] Referring to FIG. 11 , a graph depicting a scrapped volume of an extruded profile, for example, the extruded profile 302 shown in FIG. 9 (but other extruded profiles may be used) including the back-end defect, for example, the back-end defect 301 as shown in FIG. 9 (but other back-end defects may be used) removed from the extruded profile 302 extruded using a dummy block having a non-uniform or profiled surface is illustrated. During metal extrusion using a non-unform dummy block, the non-uniform surface of the dummy block may concentrate the conglomeration of billet skin oxides and spinels into a more concentrated and smaller volume of material than a volume of material including the billet skin oxides and spinels when the profile is extruded using a flat dummy block. Accordingly, a volume of the extruded profile including the back-end defect pushed through the die assembly into the profile using a dummy block including a non-uniform surface as described herein that must be removed and scrapped may be less than a volume of the back-end defect removed before being pushed through die assembly using a flat dummy block. Figure 11 illustrates an example of the shape of the back-end defect (determined using numerical methods) formed using a non-uniform concave dummy block during extrusion of a round rod. The volume of the conventional sheared butt corresponds to an equivalent scrap length in the final profile of 350 mm, greater than the 41-235 mm scrap length created using the non-uniform dummy block.

[0074] In some examples, when the back-end defect is pushed through the die assembly into the extruded profile, the non-uniform surface of the dummy block, in addition to reducing the length of the transverse welds 303, for example, the transverse welds 303 shown in FIG, 9 (but other transverse welds may be used), reduce a length of a portion of the extruded profile including the back-end defect as compared to if the back-end defect were either sheared off as a billet butt (roughly 10% of the billet length) or pushed through the die assembly by a dummy block including a conventional flat surface. In some examples, numerical methods, for example, finite element modeling, may be used to determine a length and thus a volume the portion of the extruded profile including the back-end defect that must be removed and scrapped. Accordingly, in some examples a non-uniform surface of the dummy block may be selected in consideration of the volume of the portion of the extruded profile including the back-end defect that must be scrapped. Accordingly, a volume of scrap generated during extrusion using a dummy block including a non-uniform or profiled surface as described herein may be further reduced. In other examples, peeled extrusion billets that have had the billet skin removed prior to being loaded into the extrusion chamber may be used to further reduce and/or avoid the need for back-end defect removal.

[0075] Referring to FIGS. 12-14, in some examples, the billet skin 435 may be removed as the billet of material 140 is pushed through the die assembly 120. A fluted dummy block 430 may be used to remove the billet skin 435 as the billet of material 140 is pushed through the die assembly 120. Removing the billet skin 435 as the billet of material 140 is pushed through the die assembly 120 may eliminate the need to shear off the back-end defect, for example, the back-end defect 201 shown in FIG. 7 (but the present disclosure is not limited thereto) after each push of the dummy block 430 or remove a portion of the extruded profile, for example, a portion of the extruded profile 302 shown in FIG. 9 (but the present disclosure is not limited thereto) including the back-end defect, for example, the back end defect 301 shown in FIG. 9, (but the present disclosure is not limited thereto). FIG. 12 depicts a process of forming an extruded profile 402 using a fluted dummy block 430 in accordance with one example of the present disclosure, FIG. 13 is a flow chart for forming an extruded profile 402 using a fluted dummy block 430 according to FIG. 12, and FIG. 14 illustrates a fluted dummy block 430 in accordance with one example of the present disclosure. [0076] Referring to FIG. 14, the fluted dummy block 430 includes a non-uniform or multiprofile surface 439. The non-uniform surface 439 may be the same as the non-uniform surface described above with respect to FIG. 6. The non-uniform surface 439 of the dummy block 430 may be a front surface of the dummy block 430 configured to contact a billet of material as the billet of material is pushed through a die assembly. As illustrated in FIG. 14, the non-uniform surface 439 of the dummy block 430 includes two depressions 436. In some examples, an area of the front surface (e.g., non-uniform surface 439) of the dummy block 430 may be smaller than a cross sectional area of the interior of the extrusion chamber 110. Additionally, the fluted dummy block 430 may include one or more side surfaces 437. In some examples, the fluted dummy block 430 may have a cylindrical shape including only a single side surface 437 extending around the entire fluted dummy block 430. In other examples, the fluted dummy block 430 may have the shape of a rectangular prism including four side surfaces 437. The shape of the fluted dummy block 430 may correspond to the shape of the billet of material to be extruded through a die assembly.

[0077] The fluted dummy block 430 further includes a recess 438 disposed in a side surface 437 of the fluted dummy block 430. In some examples, a recess or recesses 438 may be disposed around or along the entire side surface 437 of the dummy block 430. For example, a recess 438 may be disposed continuously around the entire side surface 437 of the fluted dummy block 430. In other examples, the recess 438 may be disposed only around a portion or portions (e.g., intermittently) of the side surface 437. In some examples, a recess or recesses 438 may be disposed on some but not all sides of the fluted dummy block 430. For example, the dummy block 430 may have the shape of a rectangular prism and include recesses 438 on two of the sides of the fluted dummy block 430.

[0078] Referring back to FIGS. 12, the recess or recesses disposed in the side surface 437 of the fluted dummy block 430 may be configured to receive a portion of a billet of material, as the billet of material is pushed or extruded through the internal cavity of the die assembly 120. The recess may be configured to receive the billet skin 435 as the billet of material 140 is pushed through the die assembly 120. For example, as illustrated in FIG. 12, as the fluted dummy block 430 contacts a back end of the billet of material 140, an outer surface of the billet of material 140 including the billet skin may flow around an outer surface of the front surface of the dummy block 430 into one or more recesses, for example, one or more recesses 438 as shown in FIG. 14 (but other recesses may be used) formed in a side surface or side surfaces 437 of the fluted dummy block 430. [0079] In some examples, the fluted dummy block 430 may be a floating dummy block. A floating dummy block is dummy block that is configured to be removed from an extrusion chamber 110 or a dummy block stem after each push of the dummy block 430. In some examples, a floating dummy block may be pushed out of an end of the extrusion chamber 110 after each push. For example, referring to FIGS. 12 and 13, in a first act S301 , a first billet of material 140 is extruded through the die assembly 120 using the fluted dummy block 430. In other examples, the floating dummy 430 block may be removed from the extrusion chamber 110 and/or the stem in a different way. The floating dummy block 430 may be removed from the extrusion chamber 110 and/or the stem after each push of the dummy block 430. For example, referring to FIGS. 12 and 13, in a second act S303, the dummy block 430 is removed from the extruded profile 402 (e.g., a portion of the extruded profile including the first billet of material 140 which has not been extruded through the die assembly 120). According to some examples, the fluted dummy block 430 may be sheard from the extruded profile 402. The billet material accumulated in the recess or recesses of the fluted dummy block 430 may be referred to as skull. In some examples, the floating dummy block 430 may be removed from the extrusion chamber 110 or dummy block stem after each use of the dummy block 430 to remove the skull accumulated in the one or more recesses during each push of the dummy block 430. In examples including a floating fluted dummy block 430, multiple different floating fluted dummy blocks 430 may be alternatively interchanged allowing the skull in the recess or recesses of one of the dummy blocks 430 to be removed during a subsequent push of the billet or material using a second floating fluted dummy block 430. For example, referring to FIGS. 12 and 13, in a third act S305, a new or second billet of material 140 and a clean fluted dummy block 430 (e.g., without skull) would be placed in the extrusion chamber 110. In a fourth act S307, the new or second billet of material 140 may be extruded through the die assembly 120, the billet skin 435 of the new or second billet of material 140 flowing into the one or more recess as the billet of material 140 is extruded through the die assembly 120.

[0080] In other examples, the fluted dummy block 430 may not be removed from the extrusion chamber 110 after each push of the dummy block 430. In some examples, the recess or recesses included in the floating dummy block 430 may be large enough so as to accommodate billet material (e.g., billet skin) from multiple pushes of the dummy block 430. In these examples, the skull may be removed from the one or more recesses in the fluted dummy block 430 after multiple pushes by the dummy block 430. [0081] Referring to FIG. 15, a system 500 for forming a preformed or shaped billet 600 (see FIG. 16) and an extruded profile is illustrated. The system 500 for forming an extruded profile includes an extrusion device 510 and a shaping chamber 530. The extrusion device 510 may be the same as the extrusion device 100 as described above with respect to FIG. 1 . For example, the extrusion device may include the extrusion chamber 110 of FIG. 1 , the die assembly 120 of FIGS. 2 and 3, and the dummy block 130 of FIG. 6, and may be configured to form the extruded profile 170 of FIG. 4.

[0082] The system 500 for forming an extruded profile in accordance with one example of the present disclosure further includes a shaping chamber 530. The shaping chamber 530 may be configured to form or shape a billet of material into a preformed or shaped billet of material 600 (see FIG. 16). The shaping chamber 530 may be configured to form a non- uniform or multi-profile surface on at least one of a front end or a back end of the shaped billet of material 600. In some examples, the shaping chamber may be configured to form a non-uniform or multi-profile surface on both the back end 620 and the front end 630 of the shaped billet of material 600.

[0083] Referring to FIG. 16, a shaped or preformed billet of material 600 in accordance with one example of the present disclosure is illustrated. The shaped billet of material 600 may be formed by the shaping chamber 530 illustrated in FIG. 15. In some examples, the shaping chamber 530 may be configured to form a non-uniform surface 610 on a back end 620 of the shaped billet of material 600 that is complimentary to the non-uniform surface formed in a surface of the dummy block 130 configured to contact the shaped billet of material 600 as the shaped billet of material 600 is pushed through the die assembly 120. Additionally, in some examples the shaping chamber 530 may be configured to form a non-uniform surface 610 on a front end 630 of the shaped billet of material 600 corresponding to the non-uniform surface of the dummy block 130 configured to contact the shaped billet of material 600 as the shaped billet of material 600 is pushed through the die assembly 120.

[0084] Accordingly, in some examples, the non-uniform interface between consecutive billets of material determined to reduce the length of the transverse welds between consecutive billets of material in an extruded profile may be directly applied to a front end 620 and/or a back end 630 of the shaped billet 600. Accordingly, in these examples, a desired interface between consecutive billets of material may be directly formed in the front end 620 and/or back end 630 of the shaped billet 600 instead of being formed in the back end 620 of the billet of material (e.g., 140) after each push of the dummy block 130 as described above with respect to some examples of the dummy block 130 of FIG. 6. Further, as a shape of the non-uniform surface 131 of the dummy block 130 is complimentary to a shape of the back end 620 of the shaped billet 600, the non-uniform shape of the back end 620 of the billet 600 may be maintained as the shaped billet of material 600 is pushed through the die assembly 120. Directly forming a desired interface between consecutive billets in a shaped billet of material 600 may further reduce a length of one or more transverse welds formed in the extruded profile, further reducing a volume of scrap produced during an extrusion process.

[0085] Returning back to FIG. 15, the shaping chamber may include a first plate 540 and a second plate 550. The first plate 540 and the second plate 550, respectively, may be comprised of tooling steel. For example, the first plate 540 and the second plate 550 may be comprised of H-13 steel alloy. The first plate 540 may include a first plate surface 541 configured to contact a first or back end of the billet of material (e.g., a billet to be formed or shaped into the shaped billet 600). The first plate surface 541 may be a non-uniform or multiprofile surface and may be configured to form a first end or back end 620 of the shaped billet of material 600 so as to have a non-uniform surface complimentary to the non-uniform first plate surface 541 . The non-uniform shape of the first plate surface 541 may vary. In some examples, the non-uniform shape of the first plate surface 541 may correspond to the non- uniform shape of the dummy block surface 131 configured to contact the shaped billet of material 600 as it is pushed through the die assembly 120. Accordingly, in some examples, the first plate surface 541 may include one or more depressions or concavities 542. The number, size, and shape of the one or more depressions 542 in the first plate surface 541 may vary according to the shape of the non-uniform surface determined to reduce the length of the transverse welds in an extruded profile. In some examples, as illustrated in FIG. 15, the one or more depressions 542 may have a semi-ellipsoid shape. In other examples, the one or more depressions 542 may have semi-spherical shape, a conical shape, a frustoconical shape, a rectangular shape, a tetrahedron shape, or the like. In some examples, the first plate surface 541 may include depressions 542 having two or more different shapes. In some examples, as illustrated in FIG. 15, the non-uniform first plate surface 541 may include depressions 542 having two or more different sizes.

[0086] Further, the second plate 550 may include a second plate surface 551 configured to contact a second or front end of the billet of material (e.g., a billet of material to be formed or shaped into the shaped billet 600). The second plate surface 551 may be a non-uniform or multi-profile surface and may be configured to form a second end or front end 630 of the shaped billet of material 600 so as to have a non-uniform surface complementary to the non- uniform second plate surface 551 . The non-uniform shape of the second plate surface 551 may vary. In some examples, the non-uniform shape of the second plate surface 551 may be complimentary to the non-uniform shape of the dummy block surface configured to contact the shaped billet of material 600 as it is pushed through the die assembly 120 and/or complimentary to the non-uniform first plate surface 541 . Accordingly, in some examples, the second plate surface may include one or more protuberances, bulges or protrusions 552 (e.g., corresponding to the depressions or concavities in the non-uniform dummy block surface and/or first plate surface). The number, size, and shape of the one or more protuberances 552 in the second plate surface 552 may vary according to the shape of the non-uniform surface determined to reduce the length of the transverse welds in an extruded profile. In some examples, as illustrated in FIG. 15, the one or more protuberances 552 may have a semi-ellipsoid shape. In other examples, the one or more protuberances 552 may have semi-spherical shape, a conical shape, a frustoconical shape, a rectangular shape, a tetrahedron shape, or the like. In some examples, the second plate surface 551 may include protuberances 552 having two or more different shapes. In some examples, as illustrated in FIG. 15, the non-uniform second plate 552 surface may include protuberances 552 having two or more different sizes.

[0087] Referring to FIG. 15, at least one of the first plate 540 and the second plate 550 may be configured to translate so as to compress the billet of material (e.g, to be formed into the shaped billet 600) between the first plate surface 541 and the second plate surface 551 so as to form the shaped billet of material 600. In some examples, only the first plate 540 may translate to compress the billet of material (e.g., billet of material 140 shown in FIG. 1 to be formed into the shaped billet 600). In other examples, only the second plate 550 may translate to compress the billet of material in between the first plate 540 and second plate 550. In yet other examples, both the first plate 540 and the second plate 550 may translate to compress the billet of material between the plates (e.g., 540, 550).

[0088] Referring to FIG. 15, the first plate 540 and/or the second plate 550 may include air vent channels 560. Similar to the air vent channels 133 described above with respect to FIG. 6, the air vent channels 560 may extend from the non-uniform first plate surface 541 to an opposite side of the first plate 540 and/or a non-uniform second plate surface 551 to an opposite side of the second plate 550 to prevent air from being trapped in the billet during shaping of the shaped billet 600. An opening of the air vent channels 560 may be disposed in the depressions 542 and/or adjacent to the protuberances 552 formed in the first plate surface 541 and/or the second plate surface 551 , respectively. As described above, an opening of the air vent channels 560 may be sufficiently small so as to prevent billet material from flowing into the air vent channels 560 during shaping of the billet. Further, as described above, the quantity, size, and/or shape of the air vent channels 560 may vary. In some examples, as described above, burping may be performed to release air trapped between the first plate surface and/or the second plate surface and the billet. Burping may be performed in both examples of with or without air vent channels.

[0089] Referring to FIG. 17, a flow chart for forming an extruded profile in accordance with one example of the present disclosure is illustrated. The flow chart as described herein may be used with any of the extrusion devices or systems for forming an extruded profile described herein. Additional, different, or fewer acts may be included.

[0090] In a first act S401 , a billet of material (e.g., billet 140, Figure 1) may be compressed to form a shaped billet of material, for example, the shaped billet of material 600 as shown in FIG. 16 (but other shaped billets of material may be used. For example, the billet of material may be placed into the shaping chamber discussed above with reference to FIG. 15. After being placed in the shaping chamber, for example, the shaping chamber 530 (but other shaping chambers may be used), at least one of a first plate, for example, the first plate 540 as shown in FIG. 15 (but other plates may be used) and a second plate, for example, the second plate 550 as shown in FIG. 15 (but other plates may be used) may translate so as to compress the billet of material into the shaped billet of material. In some examples, at least one end (e.g., a first end or second end) of the shaped billet may include a non-uniform surface. At least one of a first plate surface, for example, the first plate surface 541 (but other plate surface may be used) configured to contact a first end of the billet of material and a second plate surface, for example, the second plate surface 551 (but other plate surfaces may be used) configured to contact a second end of the billet of material may be a non- uniform surface configured to form a complimentary non-uniform surface at one of the ends of the shaped billet of material.

[0091] In another example, a shaped billet may be formed within the extrusion chamber as it is compressed between the non-uniform surface of the dummy block and a temporary non- uniform plate (e.g., second plate) placed at the end of the extrusion chamber. In yet another example, a shaped billet may be formed as it is compressed between the non-uniform surface of the dummy block and the profiled back end or butt of the previously shaped billet. In some examples, when the shaped billet is formed between the non-uniform surface of the dummy block and the back end of the previously shaped billet, tapered axial and radial heating of the loaded billet may assist, via softening, forming of the billet around the profiled butt of the previously extruded billet.

[0092] In a second act S403, a shaped billet of material may be extruded through a die assembly to form an extruded profile. In some examples, the shaped billet of material may be placed into an extrusion chamber of an extrusion device, such as those described above, so as to have a non-uniform surface located at a back end of the shaped billet of material in contact with the non-uniform surface of the dummy block as the shaped billet of material is pushed through the internal cavity of the die assembly. In some examples, the non-uniform surface of the back end of the shaped billet of material and the non-uniform surface of the dummy block may be complimentary. The extruded profile may then be pushed through the die assembly by the non-uniform surface of the dummy block to form an extruded profile.

[0093] In some examples, a third act S405 may be included. The third act S405 may be included when a fluted dummy block including a non-uniform surface in contact with the shaped billet of material is used to push the shaped billet of material through the die assembly. In the third act S405, a portion of the shaped billet of material may be received in one or more recesses formed in a side surface of the dummy block. In the third act S405, a portion of the billet of material including the billet skin may be received into one or more recesses formed in one or more side surfaces of the dummy block as the shaped billet of material is pushed through the die assembly.

[0094] While the present invention has been described with reference to specific examples, which are intended to be illustrative only and not to be limiting of the invention, it will be apparent to those of ordinary skill in the art that changes, additions and/or deletions may be made to the disclosed embodiments without departing from the spirit and scope of the invention.

[0095] The foregoing description is given for clarity of understanding only, and no unnecessary limitations should be understood therefrom, as modifications within the scope of the invention may be apparent to those having ordinary skill in the art.

Claims

What is Claimed is:

1 . An extrusion device comprising: an extrusion chamber; a die assembly including an internal cavity in communication with the extrusion chamber; and a dummy block configured to push a billet of material from the extrusion chamber through the internal cavity of the die assembly to form an extruded profile, wherein a surface of the dummy block in contact with the billet of material is a non-uniform surface.

2. The extrusion device of claim 1 , wherein the non-uniform surface includes two or more depressions or protuberances.

3. The extrusion device of claim 2, wherein the two or more depressions are formed in a flat surface of the dummy block in contact with the billet of material.

4. The extrusion device of claim 2, wherein one of the two or more depressions has a semi-ellipsoid shape.

5. The extrusion device of claim 2, wherein the two or more depressions include a first depression having a first shape and a second depression having a second shape different than the first shape.

6. The extrusion device of claim 2, wherein the two or more depressions include a first depression having a first size and a second depression having a second size different than the first size.

7. The extrusion device of claim 1 , wherein: the die assembly further comprises an internal mandrel disposed within the internal cavity and two or more bridges connecting the internal mandrel to an interior surface of the die assembly, the two or more bridges forming two or more portholes between the two or more bridges, and the two or more depressions correspond to the two or more portholes.

8. The extrusion device of claim 1 , wherein: the surface of the dummy block configured to contact the billet of material is a front surface of the dummy block, an area of the front surface of the dummy block is smaller than a cross sectional area of an interior of the extrusion chamber, and a side surface of the dummy block includes a recess configured to receive a portion of the billet of material when the billet of material is pushed through the internal cavity of the die assembly.

9. The extrusion device of claim 1 , wherein the non-uniform surface includes a depression and a protuberance.

10. The extrusion device of claim 1 , further comprising: an air vent channel extending from the non-uniform surface through the dummy block.

11. A system for forming an extruded profile, the system comprising: an extrusion chamber; a die assembly including an internal cavity in communication with the extrusion chamber; a dummy block configured to push a shaped billet of material from the extrusion chamber through the internal cavity of the die assembly to form an extruded profile, wherein a surface of the dummy block in contact with the shaped billet of material is a non-uniform surface; and a shaping chamber configured to shape a billet of material into the shaped billet of material.

12. The system of claim 9, wherein the shaping chamber further comprises: a first plate having a first plate surface configured to contact a first end of the billet of material, the first plate surface being a non-uniform surface; and a second plate having a second plate surface configured to contact a second end of the billet of material opposite the first end, the second plate surface being a non-uniform surface, wherein at least one of the first plate and the second plate is configured to translate, compressing the billet of material between the first plate surface and the second plate surface, forming the billet of material into the shaped billet of material.

13. The system of claim 10, wherein the first plate surface includes two or more depressions configured to form two or more protuberances in a first end of the shaped billet of material.

14. The system of claim 10, wherein the second plate surface includes two or more protuberances configured to form two or more depressions in a second end of the shaped billet of material.

15. The system of claim 10, wherein the first plate surface and the second plate surface are complementary.

16. The system of claim 10, wherein the first plate surface corresponds to the surface of the dummy block.

17. The system of claim 9, wherein the non-uniform surface of the dummy block includes two or more depressions.

18. The system of claim 15, wherein the two or more depressions have a semi-ellipsoid shape.

19. The system of claim 9, wherein; the surface of the dummy block configured to contact the shaped billet of material is a front surface of the dummy block, an area of the front surface of the dummy block is smaller than a cross sectional area of an interior of the extrusion chamber, and a side surface of the dummy block includes a recess configured to receive a portion of the shaped billet of material when the shaped billet of material is pushed through the internal cavity of the die assembly.

20. The system of claim 9, wherein at least one of the first plate includes an air vent channel extending from the first plate surface through the first plate or the second plate includes an air vent channel extending from the second plate surface through the second plate.

21 . A method of forming an extruded profile, the method comprising: compressing a billet of material between a first plate having a non-uniform first plate surface configured to contact a first end of the billet of material and a second plate having a non-uniform second plate surface configured to contact a second end of the billet of material to form a shaped billet of material; and pushing the shaped billet of material from an extrusion chamber through an internal cavity of a die assembly to form an extruded profile, the shaped billet of material being pushed through the internal cavity of the die assembly by a dummy block having a non- uniform surface in contact with the shaped billet of material.

22. The method of claim 17, further comprising: receiving a portion of the shaped billet of material in a recess in a side of the dummy block as the shaped billet of material is pushed through the internal cavity of the die assembly to form an extruded profile.

23. The method of claim 17, wherein the compressing the billet of material further comprises forming two or more protuberances on a first end of the shaped billet of material by a non-uniform first plate surface including two or more depressions.

24. The method of claim 17, wherein the compressing the billet of material further comprises forming two or more depressions in a second end of the shaped billet of material by a non-uniform second plate surface including two or more protuberances.