SUMMARY OF THE DISCLOSURE

[0001 ] A "metal alloy" as used herein is defined as an alloy based on a metal. One species is a multi-component alloy wherein the multi-component alloy realizes an entropy of mixing of at least 1 .25. Species within the genus of "metal alloy" includes aluminum alloys, nickel alloys, titanium alloys, steels, cobalt alloys, and chromium alloys. Aluminum alloys are presented as an example herein. Exemplary aluminum alloys may include AA (Aluminum Association) 2xxx, 3xxx, 5xxx, 6xxx, and 7xxx series aluminum alloy formulations.

[0002] This disclosure presents an apparatus and a process for economically forming a formed product (e.g. that is completely cast, partially cast/wrought, or completely wrought) with fine grain solid structure and near final shape structure.

[0003] Briefly, a metal alloy or metal alloy matrix composite with a specific composition is selected to be cast and formed into a product. The elemental components for this metal alloy or alloy matrix are prepared as feedstock melt and loaded into a mold cavity. The mold cavity is then closed and the melt compressed at a first pressure while the melt is cooled from a molten state to a first, semi-solid product state. Applied pressure is then increased to a second, forming pressure to form the near final shape of the product. This second pressure is maintained while cooling continues until a fully solid state product is achieved. Pressure is then again increased to a third pressure further compressing the product to achieve a substantially final product shape while at the same time temperature could be quickly reduced, or quenched, to ambient temperature. In some embodiments, quench occurs while the product is in the mold (e.g. cooling the mold). In some embodiments, the product is removed from the mold and directly quenched (e.g. product in communication with the quench medium).

[0004] The final product produced via this method has a fine grain structure and final shape that is achievable by such a three or four step pressurization/temperature quench process. One embodiment of the final product produced in accordance with this disclosure may be utilized as a vehicle wheel such as an automotive, commercial transportation (e.g. truck wheel) or aircraft wheel and/or may be used in aerospace applications. [0005] An embodiment in accordance with the present disclosure may be viewed as an apparatus for casting and forming a metal alloy or alloy matrix composite product. This apparatus includes a pressure casting mold configured to receive and compress a metal alloy melt, a cooling system operably connected to the mold for controllably reducing temperature of the alloy melt in the mold while the melt is compressed, a pressurizer operably connected to the mold for applying a sequence of predetermined compressive pressures to the metal alloy in the mold, and a quench device operable, in a three step process, to rapidly reduce temperature of the product in the mold in order to maintain near final internal product properties obtained at one of the predetermined pressures or, in a four step process, to receive the product from the mold while in a hot solid state and rapidly reduce temperature of the product in order to maintain near final internal product properties obtained at one of the predetermined pressures. This apparatus is especially useful in producing an aluminum metal alloy wheel product or other alloys deemed heat treatable.

[0006] The pressurizer is, in some embodiments, maintained at a first predetermined pressure such as atmospheric pressure until the metal alloy or or metal alloy matrix composite melt is cooled to a semi-solid high temperature state. The pressurizer is configured to apply to the metal alloy in the mold a second predetermined pressure greater than the first predetermined pressure while the metal alloy in the mold is cooled from the semi-solid state to below the solidus temperature for the alloy in the mold. Then the pressurizer applies to the metal alloy in the mold a third predetermined pressure greater than the second predetermined pressure to form a final product at the temperature below the solidus temperature.

[0007] The quench device is operable in some embodiments to receive the final product from the mold at the high temperature and cool the final product to an ambient temperature within about 60 seconds. This quench device in some embodiments has a plurality of rotating fluid spray nozzles operable to direct a cooling fluid around the solidified metal alloy final product during the quench operation. The quench device includes a frame for supporting the product above a rotating array of fluid spray nozzles while the nozzles are raised to and lowered from around the product as required. In some embodiments the quench device includes a frame for supporting the product and an array of fluid spray nozzles operable to spray a fluid over all surfaces of the product. In other embodiments, the quench device is configured to cool the final or near final product while in the mold to an ambient temperature within about 60 seconds.

[0008] An embodiment in accordance with the present disclosure may alternatively be viewed as a method of casting and forming a metal alloy or metal alloy matrix composite product. This method includes pouring a molten metal alloy or alloy matrix composite melt into a mold cavity, closing the mold cavity, and applying a first pressure to the molten metal alloy in the mold cavity. Then cooling the molten metal alloy or alloy matrix composite melt in the mold cavity to a predetermined semi-solid state, and applying a second pressure to the semi-solid state metal alloy to form the metal alloy into a near-final/final shape product, and then applying a third pressure to the near final to final shape metal alloy product at a high temperature solid state temperature (e.g. to prevent distortion during quenching), then quenching the final shape metal alloy product to reduce its temperature to an ambient temperature. In some embodiments the first pressure on the metal alloy is maintained while it is cooling to a semi-solid state. The second pressure is, in some embodiments, greater than the first pressure, and the third pressure is greater than the second pressure. In some embodiments the quenching includes subjecting the metal alloy product to cooling from a flowing fluid such as a water spray to reduce temperature of the metal alloy product to ambient temperature within about 45 seconds.

[0009] An exemplary embodiment in accordance with the present disclosure may alternatively be viewed as a metal alloy or alloy matrix product (e.g. that is completely cast, partially cast/wrought, or completely wrought) formed by a three or four step pressurization temperature quench process. This process includes providing a mold cavity, introducing a molten metal into the mold cavity, closing the mold cavity, applying a first pressure to the molten metal alloy in the mold cavity, and cooling the molten metal alloy in the mold cavity to a predetermined semi-solid state, then applying a second pressure to the semi-solid state metal alloy to form the metal alloy into a final shape product, applying a third pressure to the final shape metal alloy product at a high temperature solid state temperature, and finally quenching the final shape metal alloy product to reduce its temperature to an ambient temperature.

[0010] In some embodiments the first pressure is maintained on the metal alloy while it is cooling to a semi-solid state, the second pressure is greater than the first pressure and the third pressure is greater than the second pressure. The process, in some embodiments, further includes cooling the semi-solid state alloy to a high temperature solid state while at the second pressure.

[001 1 ] The quenching operation may include subjecting the metal alloy or alloy matrix composite product to cooling from a flowing fluid such as a pressurized gas, such as air, an air/moisture spray or a water spray. The quenching reduces temperature of the metal alloy product to near ambient temperature in some embodiments within 45 seconds. In some embodiments the quenching reduces temperature of the metal alloy product from 600F to 400F within about 5 seconds and the quenching may reduce temperature of the metal alloy product from about 900F to 140F within about 30 seconds. This quench operation may be followed by an artificial aging process to enhance properties and attributes within the final product.

[0012] An embodiment in accordance with the present disclosure may be viewed as a cast aluminum alloy or metal alloy matrix composite wheel product formed in an apparatus that includes a pressure casting mold configured to receive and compress a metal alloy or metal matrix composite melt, a cooling system operably connected to the mold for controllably reducing temperature of the alloy melt in the mold while the melt is compressed, a pressurizer operably connected to the mold for applying a sequence of predetermined compressive pressures to the metal alloy in the mold, and a quench device operable to rapidly reduce temperature of the product while in the mold or to receive the product from the mold while in a hot solid state and rapidly reduce temperature of the product in order to maintain near final internal product properties or attributes obtained at one of the predetermined pressures.

[0013] The process may include operations of introducing the molten metal alloy or molten metal alloy matrix composite into the mold cavity, applying a first pressure to the molten metal alloy in the mold cavity, cooling the molten metal alloy or molten metal alloy matrix composite in the mold cavity to a predetermined semi-solid state while at the first pressure, applying a second greater pressure to the semi-solid state metal alloy or metal matrix composite to form the metal alloy or metal matrix composite into a near-final or final shape wheel product, applying a third pressure greater than the second pressure to the near-final or final shape metal alloy or metal matrix composite wheel product at a high temperature solid state temperature, and thereafter quenching the near-final/final shape metal alloy or metal matrix composite wheel product to reduce its temperature to an ambient temperature. This process, in some embodiments, includes cooling the semi-solid state alloy to a high temperature solid state while at the second pressure and the quenching includes subjecting the metal alloy or metal matrix composite product to cooling from a flowing fluid such as compressed air or a water spray either while in the mold or after removal from the mold. This spray, in some embodiments, reduces temperature of the metal alloy or metal matrix composite product to ambient temperature within 45 seconds. More preferably the quenching reduces temperature of the metal alloy or metal matrix composite product from 600F to 400F within about 5 seconds and reduces temperature of the metal alloy or metal matrix composite product from about 900F to 140F within about 30 seconds.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a schematic sectional view of an exemplary embodiment of a cast and pressure forming mold apparatus in accordance with the present disclosure.

[0015] FIG. 2 is a schematic side view of a quenching apparatus holding the cast and forming mold shown in FIG. 1 in accordance with the present disclosure.

[0016] FIG. 3 is a process flow diagram of the method of forming in accordance with the present disclosure.

[0017] FIG. 4 is an exemplary phase/state diagram for a metal alloy family.

DETAILED DESCRIPTION

[0018] In the description that follows, like numerals are utilized to describe like components and subcomponents in the various views.

[0019] As noted above, this disclosure presents a system/apparatus and method for casting and forming a metal alloy product. FIG. 1 is an exemplary sectional view of an apparatus 100 for molding and pressure forming an alloy or alloy matrix composite product such as a wheel in a mold cavity 102. The mold cavity 102 is defined by a lower mold die 104 and an upper mold die 106 that can be squeezed together via a force piston 108 in order to apply predetermined compressive pressures to the metal alloy or metal alloy based matrix composite melt 1 10 and solidifying alloy product formed in the cavity 102 between mold dies 104 and 106.

[0020] First a metal alloy or metal alloy based matrix composite melt 1 10 is injected into the exemplary mold cavity 102 and then the mold cavity 102 is closed via valves 1 12, 1 14 and 1 16. A first pressure is applied to the melt 1 10 and temperature is then controllably reduced at the first pressure until the metal melt achieves a semi-solid state.

[0021 ] Then piston 108 applies a greater second predetermined pressure greater than the first pressure to compressively form the melt at the semi-solid state into a solid near final product shape in the mold cavity 102 while temperature is further reduced from above liquidus to below liquidus but above the solidus temperature of the alloy.

[0022] Then piston 108 applies a still greater third predetermined pressure (when the temperature is below the solidus) to the now solid near final shape product to achieve a final near final shape throughout the final product 200 in the mold 102. The mold dies 104 and 106 are then separated and the final product 200 is removed and transferred to a quenching apparatus 300, while still in a high temperature solid state (temperature above the solvus temperature of the alloy).

[0023] A controlled fluid wash/spray is then applied to the product 200 in the quenching apparatus 300 to rapidly reduce temperature of the final product 200 to ambient temperature of about 140F thereby maintaining internal product attributes while reducing quench distortion.

[0024] An exemplary apparatus 300 for accomplishing this rapid reduction or quenching operation is shown in FIG. 2. A schematic representation of a wheel rim product 200 is shown supported by a frame 120. A movable quenching nozzle ring array 122 is supported below the product 200. This array 122 is operable via piston 124 to rise up around the product 200 in the frame 120. The array 122 includes a plurality of spaced nozzles 126 around the periphery of the product 200 and nozzles 128 positioned to spray jets of flowing fluid around an interior portion of the product when the array 122 is in a raised position. [0025] FIG. 3 shows an operational process or method for forming a metal alloy or metal alloy based matrix composite product 200 in accordance with the present disclosure. The process begins in operation 150 where a metal alloy or matrix composite melt is poured into the mold cavity 102 formed between the mold dies 104, 106. The melt is then compressed in operation 152 at a first pressure. Control then transfers to operation 154.

[0026] Referring now to FIG. 4, a state diagram for typical metal alloys is shown. The vertical line W _L indicates the states of an exemplary alloy composition of elements A and B such as in product 200, as an example. Other alloys would be characterized at different points along the horizontal composition % axis. The vertical axis is temperature T of the alloy. In the S1 and S1 +S2 regions the alloys are fully solid. In the L+S1 region the alloy is partially solid, i.e. in a semi-solid state. The LL line indicates the liquidus line, above which, region L, the alloy is fully liquid.

[0027] For a typical aluminum alloy wheel rim product 200, this liquidus temperature would be on the order of about 1200°F. Initially the molten alloy melt is fully liquid, at a temperature, indicated by dot 170, well above the liquidus line when it is poured into the mold cavity 102 and the first pressure is applied. This first pressure may be atmospheric pressure. The melt cools from temperature 170 at the first pressure to a semi-solid state indicated by dot 180 on the state diagram of FIG. 4. The semi-solid state temperature is somewhere within a range of from about 1 160F to about 1 100F for a typical aluminum wheel alloy.

[0028] When the near final semi-solid state 180 is reached, in the L+S1 region, control transfers to operation 156. In operation 156, compressive pressure applied by the piston 108 is increased to a second predetermined pressure within a force range of about 100 to 300 tons of force. Control then transfers to operation 158. This second predetermined pressure is maintained in operation 158 in order to press form the metal into a near final product shape and maintained for a period of time, approximately 1 to 5 minutes while temperature is reduced until fully solid, for example, to a temperature indicated by dot 182, in the S1 region. Control then transfers to operation 160.

[0029] In operation 160, pressure is again increased to a third compressive pressure higher than the second pressure, sufficiently high enough to impose plastic deformation and/or reduce, prevent and/or eliminate quench distortion in the solidified metal. This third predetermined pressure is maintained for a relatively short time period of time, on the order of 30-120 seconds to form the product into a final shape product 200. Control then transfers to quench operation 162.

[0030] In an exemplary quench operation 162, the final shaped product 200 is removed from the mold cavity 102, while at a temperature well within the S1 region, a range of about 1 1 OOF to about 750F in the illustration of FIG. 4, and suspended from a support 121 in an exemplary quenching apparatus 120 shown in FIG. 2. The ring array of spray nozzles 122 is raised up around the suspended final product 200 and pressurized flowing fluid, for example, forced air, a water spray, or mist is applied, or drenched, over and around all surfaces of the product 200 held by support 121 in order to rapidly cool the product 200, indicated by dot 182 in the state diagram of FIG. 4, to ambient temperature, thereby substantially ensuring that the fine grain structure formed during the application of the third pressure in operation 160 is maintained in the final product 200.

[0031 ] In another exemplary quench operation, the cooling fluid is drenched over the final product 200 while it is still within the mold to rapidly reduce temperature of the product to substantially ambient temperatures.

[0032] FIG. 4 shows a state diagram for a two component alloy for manufacturing a component according to the method and with an apparatus according to the present disclosure. On the X-axis the ratio of the amount of a metal alloy (WL) is stated, which comprises XA% of a metal A and XB% of a metal B. The vertical line WL represents one exemplary alloy composition. On the Y axis, the temperature (T) is given. The temperature range for the step of first predetermined pressure application, which is, in some embodiments, below the liquidus temperature (TL) and above the solidus temperature TS (TL>T2>TS), is indicated by dot 180. In dependency of the process time at the pressure application (operation 158) a remaining degree of deformation of less than 15% remains for the following compressing operation (operation 160). The step of compressing (operation 160) the metal alloy within the mold at the third predetermined pressure greater than the second predetermined pressure takes place at a temperature indicated by dot 182 especially in a temperature range between the temperature 180 and half the solidus temperature , or 0.5TS(T2>T3>0.5TS). [0033] Optionally, a partial metal post-compressing operation takes place at stress-exposed component regions, which can be achieved by means of introducing another die from above (not shown). This optional partial post-compressing operation, in some embodiments, takes place at a temperature below the temperature indicated by dot 182. Another optional operation may include post quench artificial aging of the final product. This post quench artificial aging is utilized to improve Tensile Yield Strength (TYS) and Ultimate Tensile Strength (UTS) of the final product such as a wheel. In some embodiments, post quenching additional operations can be performed on the final shape metal alloy or metal matrix composite product in order to provide the functional form of the product for its commercial application (e.g. wheel with rim, etc.).

[0034] While various embodiments of the new technology described herein have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. For example, the apparatus may be reversed in that the ring of spray nozzles may be stationary and the wheel rim product to be quenched lowered so as to be drenched with the cooling liquid spray. The quenching fluid may be other than a water spray. For example, in some embodiments, forced air or another gas, or an organic solvent fluid might be utilized, instead of water or a water spray, that has the appropriate heat quenching properties. The apparatus may alternatively be utilized for a different product than a wheel. The wheel product shown is merely exemplary. It is to be expressly understood that such modifications and adaptations are within the spirit and scope of the presently disclosed technology.