Patent Description:
Many metallic components are produced using casting processes, a common casting process used is sand casting. Sand casting is a metal casting process characterized by using sand as the mold material. Sand casting uses mold boxes, known as flasks, filled with compacted sand to produce the mold cavities and gate system that is filled with molten metal to create the cast component. Sand casting is a relatively cheap method of casting components, but it also can result in lower quality and less predictable results of the final cast component. Components that require high accuracy, tight tolerances, and internal passages can be difficult to produce using sand casting processes. Other casting processes, such as investment casting, give a higher degree of precision for highly complex parts but are usually applied to smaller components than sand casting processes. Further, permanent mold and die casting processes are used for high-volume industries but typically make less complex parts than sand or investment casting processes. As such, there is a need for a casting process with less variation, better quality, and more predictable results for the final cast component. Casting techniques are disclosed in <CIT>, <CIT> and <CIT>.

According to one aspect of the invention, a method for producing structural components is provided as defined by independent claim <NUM>.

According to another aspect of the invention, a casting assembly for producing a structural component is provided as defined by independent claim <NUM>.

This disclosure presents a hybrid casting process which uses the advantages of several casting processes to optimize the final cast component. The hybrid casting process uses conventionally manufactured or additively manufactured internal cores to produce complex internal passages as used in the sand-casting process. The hybrid casting process enables complex internal and external geometries as achieved in investment casting. Further, the hybrid casting process utilizes actively heated and/or cooled permanent molds, as used in die casting, to provide thermal control for optimum solidification of specific areas of the casting without relying on excessive gating systems/channels to feed metal into the part. The permanent molds can be filled with loose or chemically set sand to create a mold around the additive cores or a fluid ceramic media can be introduced to create a mold as in solid mold or investment casting. As such, the hybrid casting process results in less variation, better quality, and more predictable results for the final cast component.

<FIG> is a flow chart illustrating steps of method <NUM> for producing structural components using a hybrid casting process. <FIG> is a schematic diagram showing a first step of method <NUM>. <FIG> is a schematic diagram showing a second step of method <NUM>. <FIG> is a schematic diagram showing a third step of method <NUM>. <FIG> is a schematic diagram showing a fourth step of method <NUM>. <FIG> is a schematic cross-sectional diagram illustrating a structural component produced using the hybrid casting process. <FIG> will be discussed together.

Method <NUM> includes steps <NUM>, <NUM>, <NUM>, <NUM> , <NUM>, and <NUM>. As shown best in <FIG>, step <NUM> includes aligning core <NUM> within metallic mold <NUM> by coupling core <NUM> to metallic locators <NUM> attached to metallic mold <NUM>. Step <NUM> includes filling metallic mold <NUM> with a molten metallic material. Step <NUM> includes solidifying the metallic material within metallic mold <NUM> to produce cast component <NUM>. As shown best in <FIG>, step <NUM> includes removing cast component <NUM> from metallic mold <NUM>. Step <NUM> includes identifying datum location <NUM>, wherein datum location <NUM> is a central axis of aperture <NUM> extending through cast component <NUM> to core <NUM>. As shown best in <FIG>, step <NUM> includes removing material from one or more of internal surface <NUM> and external surface <NUM> of cast component <NUM> based off datum location <NUM>. Each of steps <NUM>-<NUM> will be discussed in further detail below.

Referring again to <FIG>, casting assembly <NUM> for producing structural components is shown. Casting assembly <NUM> includes metallic mold <NUM>, metallic locators <NUM>, core <NUM>, and fluid channels <NUM>. Metallic mold <NUM> is a hollow container used to give shape to a molten or hot liquid material when it cools and hardens. Metallic mold <NUM> includes walls <NUM> defining surfaces of the to be cast component <NUM>. More specifically, walls <NUM> of metallic mold <NUM> are used to produce external and/or internal surfaces of cast component <NUM>. Each individual wall <NUM> of metallic mold <NUM> can be coupled together to form the overall shape of metallic mold <NUM> and the to be cast component <NUM>. In some examples, walls <NUM> of metallic mold <NUM> can be coupled together using fasteners that can be removed to separate and decouple walls <NUM> of metallic mold <NUM>. In other examples, walls <NUM> of metallic mold <NUM> can be coupled together through welds and/or formed from a single piece of material through machining operations. Metallic mold <NUM> is constructed from a metallic material, and in some examples, metallic mold <NUM> can be constructed from one or more of a cast iron, alloy steel, nickel alloy, copper alloy, and tungsten alloy. Further, metallic mold <NUM> is constructed from a material that has a higher temperature melting point than the metallic material poured into metallic mold <NUM>.

In the example shown, metallic mold <NUM> is a cube or box shaped mold, such that the resulting cast component <NUM> has a cube or box shaped external shape. In this example, the cube or box shaped cast component <NUM> has greater external tolerancing and flexibility but requires more machining operations to achieve the desired final external shape of the cast structural component. In an example, walls <NUM> of metallic mold <NUM> can have a complex shape that generally outlines the external geometry of the desired cast structural component. In this example, cast component <NUM> with a near net external geometry requires less machining operations to achieve the desired final external shape but also has less flexibility, as compared to a cube or box shaped mold, discussed further below.

Metallic locators <NUM> are positioned adjacent a top of metallic mold <NUM> and locators <NUM> extend inward toward a center of metallic mold <NUM>. Locators <NUM> are removably coupled to metallic mold <NUM> such that locators <NUM> can be coupled and decoupled from metallic mold <NUM> as required during the casting process. Locators <NUM> are configured to aid in properly positioning and aligning core <NUM> within metallic mold <NUM>, discussed further below. In some examples, locators <NUM> can be one or more of a pin, an aperture, a hook, an indent, a clevis, or a surface, among other options. In the example shown there are two locators <NUM>, each positioned on opposite sides of metallic mold <NUM> and extending inward toward a center of metallic mold <NUM>. In another embodiment, there can be more or less than two locators <NUM> coupled to metallic mold <NUM> and locators <NUM> can be positioned at any desired location on metallic mold <NUM>. In any embodiment, locators <NUM> are configured to accurately position core <NUM> within metallic mold <NUM> to meet internal and external tolerancing and other requirements for internal features of the final cast structural component.

Core <NUM> is a component of casting assembly <NUM> that is utilized to produce one or more internal passages and internal features within cast component <NUM>, producing internal features of the cast structural component. In some examples, core <NUM> can be utilized to produce fluid flow channels within a structural component that cannot be produced using traditional drilling, milling, or turning operations. Core <NUM> can be a ceramic core that is constructed from a ceramic material. Core <NUM> can be produced using a casting process or through an additive manufacturing process. As previously introduced, step <NUM> of method <NUM> includes aligning core <NUM> within metallic mold <NUM> by coupling core <NUM> to metallic locators <NUM> attached to metallic mold <NUM>. More specifically, a machine tool (not shown) is utilized to lower core <NUM> within walls <NUM> of metallic mold <NUM>. Core <NUM> is lowered into metallic mold <NUM> until core <NUM> interfaces with locators <NUM> coupled to metallic mold <NUM>. Core <NUM> is then coupled to locators <NUM>, securing core <NUM> to locators <NUM> and metallic mold <NUM>. Core <NUM> is now precisely positioned within metallic mold <NUM> to produce internal passages and internal features within cast component <NUM> and the final cast structural component.

Step <NUM> includes filling metallic mold <NUM> with a molten metallic material. More specifically, a metallic material is heated to a temperature above the metallic materials melting point to produce liquefied metal. The molten metallic material is poured into metallic mold <NUM> with the coupled core <NUM>, such that the molten metallic material fills metallic mold <NUM> and surrounds core <NUM> positioned within metallic mold <NUM>. In some examples, the molten metallic material can be one or more of an aluminum alloy and a magnesium alloy, among other options. Step <NUM> includes solidifying the metallic material within metallic mold <NUM> to produce cast component <NUM>. Solidifying the metallic material includes strategically allowing the metallic material to cool in temperature to solidify into a solid metallic cast component <NUM> with specific material properties. The specific material properties for cast component <NUM> will vary depending on the structural component being produced and the requirements for the mechanical and thermal properties of the structural component. The material properties of cast component <NUM> is controlled through thermal management techniques that alter the solidification dynamics of cast component <NUM>.

As shown in <FIG>, casting assembly <NUM> can include fluid channels <NUM> that are utilized to control the solidification dynamics of cast component <NUM>. Fluid channels <NUM> can be positioned adjacent walls <NUM> of metallic mold <NUM> and fluid channels <NUM> are configured to provide a flow path for heating or cooling fluid to flow through. Fluid channels <NUM> can be one or more of a tube, hose, channel, conduit, or the like that includes a hollow central portion in which heating or cooling fluid can flow through. In some examples, fluid channels are positioned within walls <NUM> of metallic mold <NUM> such that fluid channels <NUM> are integral with walls <NUM> of metallic mold <NUM>. In other examples, fluid channels <NUM> can be affixed to exterior surfaces <NUM> and interior surfaces <NUM> of walls <NUM> of metallic mold <NUM>. Fluid channels <NUM> are fluidly coupled to a fluid source (not shown) positioned remote from casting assembly <NUM> and fluid channels <NUM> are configured to receive fluid from the fluid source. Fluid channels <NUM> can be separated into groups of channels such that some fluid channels <NUM> have a hot fluid flowing through them and other fluid channels <NUM> have a cold fluid flowing through them. Fluid channels <NUM> with hot fluid flowing through the fluid channels are configured to heat metallic mold <NUM>. Fluid channels <NUM> with cold fluid flowing through the fluid channels are configured to cool metallic mold <NUM>. In some examples, thinner portions of metallic mold <NUM> may require heating and thicker portions of metallic mold <NUM> may require cooling to achieve the desired solidification dynamics of cast component <NUM>. In other examples, heating or cooling specific sections of the mold may also be accomplished by use of electric resistance heaters, inductions coils, or the use of a variety of conductive metals or ceramic media with heat transfer attributes.

In the example shown in <FIG>, casting assembly <NUM> includes a plurality of sections/portions that have either heating or cooling fluid channels <NUM> positioned adjacent walls <NUM> of metallic mold <NUM>. In the present invention, metallic mold <NUM> includes at least a first portion <NUM>, a second portion <NUM>, a third portion <NUM>, and a fourth portion <NUM>. The first portion <NUM> of metallic mold <NUM> is positioned on an exterior surface <NUM> of metallic mold <NUM>; the second portion <NUM> of metallic mold <NUM> is positioned on an interior surface <NUM> of metallic mold <NUM>; the third portion <NUM> of metallic mold <NUM> is positioned on an exterior surface <NUM> of metallic mold <NUM>; and the fourth portion <NUM> of metallic mold <NUM> is positioned on an interior surface <NUM> of metallic mold <NUM>. Further, in some examples, first portion <NUM> and second portion <NUM> of metallic mold <NUM> include hot fluid channels <NUM> and the hot fluid flowing through fluid channels <NUM> heats first portion <NUM> and second portion <NUM> of metallic mold <NUM>. In addition, in some examples, third portion <NUM> and fourth portion <NUM> of metallic mold <NUM> include cold fluid channels <NUM> and the cold fluid flowing through fluid channels <NUM> cools third portion <NUM> and fourth portion <NUM> of metallic mold <NUM>. In other examples, metallic mold <NUM> can include at least one heating device and at least one cooling device that are coupled to metallic mold <NUM> and configured to increase and decrease the temperature of surfaces of metallic mold <NUM>, respectively. In one example, the heating device can be a resistance heating element configured to increase in temperature when an electric current is supplied to the resistance heating element.

As such, metallic mold <NUM> can include hot/cold fluid channels <NUM> and/or heating/cooling devices that are configured to heat and cool different portions of metallic mold <NUM> to achieve the desired solidification dynamics of cast component <NUM>. In some examples, thinner portions of cast component <NUM> may require heating and thicker portions of cast component <NUM> may require cooling during the solidification process to achieve the desired cooling characteristics and mechanical and thermal properties for cast component <NUM>. Further, metallic mold <NUM> being constructed from a metallic material aids in the solidification process because metal is conductive and more effective at heating and cooling, as compared to traditional sand molds which are insulators. In addition, metallic mold <NUM> including heating and cooling devices is advantageous over traditional sand molding because it eliminates the need for at least some venting, gating, and waste flow channels that were previously required to achieve proper cooling characteristics for large structural cast components.

More specifically, metallic mold <NUM> including heating and cooling devices is advantageous over traditional sand molding because the casting process requires less metal to cast the part due to relying on active heating and cooling rather than gating systems to achieve a sound casting with desirable material properties. Removing the traditional gating systems results in less overall metallic material used during the casting process, less waste, and in turn lower costs for producing the structural component. In turn, this compensates for a larger external envelope for the part that will require machining to final dimensions. As such, controlling the solidification process of cast component <NUM> is key to achieving a final structural component with the desired mechanical and thermal properties, while also reducing waste and increasing profits.

As shown in <FIG>, step <NUM> includes removing cast component <NUM> from metallic mold <NUM>. After cast component <NUM> has completed the solidification process, cast component <NUM> is removed from metallic mold <NUM>. Cast component <NUM> can be removed from metallic mold <NUM> using various techniques. In one example, the fasteners coupling walls <NUM> of metallic mold <NUM> are removed and walls <NUM> are separated from cast component <NUM>. In another example, an aperture within metallic mold <NUM> allows access to a bottom side of cast component <NUM> and cast component <NUM> can be pushed from a bottom surface upward to separate cast component <NUM> from metallic mold <NUM>. Then a crane, hoist, or other similar device can be used to raise cast component <NUM> from metallic mold <NUM>. Once cast component <NUM> is removed from metallic mold <NUM>, core <NUM> is removed from cast component <NUM> and the hollow channels and/or features remain within the interior of cast component <NUM>. In one example, core <NUM> can be removed from cast component <NUM> by breaking core <NUM> into small pieces and then the small pieces are shaken out from the interior of cast component <NUM>. In another example, a release agent/liquid can be applied to core <NUM> and a heating process can be used to melt/dissolve core <NUM> into smaller particles that can then be poured or shaken out from the interior of cast component <NUM>.

Step <NUM> includes identifying datum location <NUM>, wherein datum location <NUM> is a central axis of aperture <NUM> extending through cast component <NUM> to core <NUM>. Datum location <NUM> is a reference point on or within cast component <NUM> in which all final edges and surfaces of the structural component are measured from. More specifically, datum location <NUM> is a fixed starting point in which all machining operations are measured from to produce the final external dimensions and geometry of the structural component. In one examples, datum location <NUM> can be a central axis of aperture <NUM> extending through cast component <NUM>. In other examples, datum location can be a surface, edge, or other feature of cast component <NUM> in which all final edges and surfaces of the structural component are measured from.

As shown best in <FIG>, step <NUM> includes removing material from one or more of internal surface <NUM> and external surface <NUM> of cast component <NUM> based off datum location <NUM>. More specifically, a CNC machine is used to machine and remove material from internal surfaces <NUM> and external surfaces <NUM> of cast component <NUM> to produce the final dimensions and geometry of the structural component. Removing material from internal surfaces <NUM> and external surfaces <NUM> of cast component <NUM> can be one or more of a turning operation, drilling operation, and milling operation, among other options. The CNC machine uses datum location <NUM> as the origin (<NUM>,<NUM> location) in which all geometric dimensions and tolerances are measured from to ensure the final machined cast component <NUM> meets the dimensional requirements for the desired structural component. <FIG> is a schematic cross-sectional diagram illustrating an example structural component produced using the hybrid casting process.

The hybrid casting process described in method <NUM> produces cast components that have less variation, better quality, and more predictable results, resulting in high customer satisfaction and lower overall costs. The hybrid casting process provides a method to control internal and external casting mold movement to produce a higher percentage of conforming structural components. The hybrid casting process provides a method to consistently align core <NUM> within metallic mold <NUM>, reducing variation from part to part. Further, providing metallic mold <NUM> with excess material on external surfaces <NUM> of cast component <NUM> allows for a simpler external envelope which can be more readily cast and machined to final desired dimensions during the final machining processes to achieve the desired dimensions and tolerances for all internal and external features of the cast structural component. Metallic mold <NUM> is a reusable mold that can be used to produce many structural components with the same mold, thus metallic mold <NUM> reduces variation from part to part as compared to traditional sand molds. Method <NUM> and the hybrid casting process produce internal features with less variation by allowing more internal tolerance which is balanced by external machining to achieve to final external geometry. Further, method <NUM> and casting assembly <NUM> allow for more effective thermal management during the cooling of cast component <NUM> which produces better castings, as compared to traditional sand castings. The reusable metallic mold <NUM> gives a more consistent product than expendable sand molds with less process variation, leading to better quality, less material waste, lower cost, more predictable results, and high customer satisfaction.

Claim 1:
A method for producing structural components, the method comprising:
aligning a core (<NUM>) within a metallic mold (<NUM>) by coupling the core to metallic locators (<NUM>) attached to the metallic mold (<NUM>), wherein the metallic mold (<NUM>) includes an exterior surface (<NUM>) and an interior surface (<NUM>);
filling the metallic mold (<NUM>) with a molten metallic material;
solidifying the metallic material within the metallic mold (<NUM>) to produce a cast component (<NUM>) by:
heating a first portion (<NUM>) of the metallic mold (<NUM>) during the solidifying of the metallic material within the metallic mold (<NUM>), wherein the first portion (<NUM>) of the metallic mold (<NUM>) is on the exterior surface (<NUM>) of the metallic mold (<NUM>);
heating a second portion (<NUM>) of the metallic mold (<NUM>) during the solidifying of the metallic material within the metallic mold (<NUM>), wherein the second portion (<NUM>) of the metallic mold (<NUM>) is on the interior surface (<NUM>) of the metallic mold (<NUM>);
cooling a third portion (<NUM>) of the metallic mold (<NUM>) during the solidifying of the metallic material within the metallic mold (<NUM>), wherein the third portion (<NUM>) of the metallic mold (<NUM>) is on the exterior surface (<NUM>) of the metallic mold; and
cooling a fourth portion (<NUM>) of the metallic mold (<NUM>) during the solidifying of the metallic material within the metallic mold (<NUM>), wherein the fourth portion (<NUM>) of the metallic mold (<NUM>) is on the interior surface (<NUM>) of the metallic mold (<NUM>);
wherein the heating and cooling of portions (<NUM>, <NUM>, <NUM>, <NUM>) of the metallic mold (<NUM>) is selected to achieve desired solidification dynamics of the cast component (<NUM>);
removing the cast component (<NUM>) from the metallic mold (<NUM>);
identifying a datum location (<NUM>), wherein the datum location (<NUM>) is a reference point in which all edges and surfaces of the cast component (<NUM>) are measured from and wherein the datum location (<NUM>) is a central axis of an aperture (<NUM>) extending through the cast component (<NUM>) to the core (<NUM>); and
removing material from one or more of an internal surface (<NUM>) and external surface (<NUM>) of the cast component (<NUM>) based off the datum location (<NUM>).