SAND CAST PROTOTYPE SYSTEM PROVIDING MATERIAL PROPERTIES THAT REPLICATE HIGH PRESSURE DIE-CASTING

Description

The present disclosure relates to developing sand cast prototypes, and, more particularly, to developing sand cast prototypes having similar properties as a high pressure die cast production part.

High pressure die casting is a metal casting process that is characterized by forcing molten metal under high pressure into a mold cavity having a predetermined shape of a casting. Modern vehicles, especially those of hybrid and electric vehicles, are moving toward simpler vehicle body designs by die casting ultra-large single-piece panels and components that serve as a load bearing structure of the vehicle body. These ultra-large single-piece castings are often referred to as mega-castings or giga-castings due to the huge size of the die casting machines used to make these castings. Ultra-large castings allow vehicle bodies to be lighter and less complex to manufacture by replacing the large number of stamped panels required to form the vehicle body with a single-piece casting.

Aluminum-silicon based alloys are typically used in die casting of vehicle body components and in the ultra-large single-piece castings due to the alloys' lightweight, superior moldability, mass producibility, and high strength. Traditionally, only one melt is used for each cast component.

Development of a high-pressure die cast (HPDC) prototype, particularly for ultra-large or giga casting, can be very expensive and time-consuming (often more than one year) in developing a die tooling. Development of prototypes for other metal mold casting processes, for example low-pressure die casting, counterpressure casting, and semi-permanent molding, may also suffer from expensive and time-consuming metal mold development. Because of high cost and long lead times of metal molds, a sand-casting process is often employed for prototype development. However, due to intrinsic differences between sand casting and metal mold processes (e.g., cooling rate, filling patterns, fill times, and so forth), sand cast prototypes do not match levels or distribution of mechanical properties of production metal mold parts.

Thus, while high-pressure die cast prototyping achieves its intended purpose, there is a need for a new and improved method for prototyping high-pressure die cast or other metal mold production parts that minimizes time and expense.

SUMMARY

According to several aspects of the present disclosure, a prototype sand-casting system for producing a sand cast prototype that duplicates material properties of a high pressure die casting part is provided. The prototype sand-casting system includes a sand-casting mold, a plurality of ingates in fluid connection with the mold cavity, a runner system, a first furnace, and a second furnace. The sand-casting mold includes a mold cavity having a predetermined shape of a casting. The plurality of ingates are configured to direct multiple concurrent casting alloys including a first molten metal alloy and a second molten metal alloy into the mold cavity to form the casting. The runner system is fluidly coupled to the plurality of ingates, and the first molten metal alloy at least partially mixes with the second molten metal alloy in the runner system. The first furnace is fluidly coupled to the runner system, and the first furnace provides the first molten metal alloy to the runner system. The second furnace is fluidly coupled to the runner system, and the second furnace provides the second molten metal alloy to the runner system. The first molten metal alloy and the second molten metal alloy are concurrent casting alloys.

In accordance with another aspect of the disclosure, the prototype sand-casting system includes a runner system having a single runner that receives the first molten metal alloy and the second molten metal alloy. The first molten metal alloy and the second molten metal alloy mix in the single runner.

In accordance with another aspect of the disclosure, the first molten metal alloy and the second molten metal alloy are different compositions.

In accordance with another aspect of the disclosure, the prototype sand-casting system includes a runner system having a first runner that fluidly couples the first furnace and the mold cavity and includes a second runner that fluidly couples the second furnace and the mold cavity.

In accordance with another aspect of the disclosure, the prototype sand-casting system includes a mold cavity in which the first molten metal alloy and the second molten metal alloy mix.

In accordance with another aspect of the disclosure, the first molten metal alloy and the second molten metal alloy are determined at least partially based on a virtual casting tool simulation to duplicate material properties of high-volume high pressure die casting (HPDC) production parts.

In accordance with another aspect of the disclosure, the prototype sand-casting system includes a third ingate in fluid connection with the mold cavity configured to direct a third molten metal alloy into the mold cavity to form the casting.

In accordance with another aspect of the disclosure, the prototype sand-casting system includes a third furnace that provides a third molten metal alloy to the runner system.

In accordance with another aspect of the disclosure, the prototype sand-casting system includes a third molten metal alloy different than the first molten metal alloy and the second molten metal alloy.

In accordance with another aspect of the disclosure, the prototype sand-casting system includes at least one riser fluidly coupled to the mold cavity.

According to several aspects of the present disclosure, a prototype sand-casting system for producing a sand cast prototype that duplicates material properties of a high pressure die casting part is provided. The prototype sand-casting system includes a sand-casting mold, a first runner system, a second runner system, a first furnace, and a second furnace. The sand-casting mold includes a mold cavity having a predetermined shape of a casting. The first runner system is in fluid connection with the mold cavity, and the first runner system directs a first molten metal alloy into the mold cavity to form the casting. The second runner system is in fluid connection with the mold cavity, and the second runner system directs a second molten metal alloy into the mold cavity to form the casting. The second molten metal alloy at least partially mixes with the first molten metal alloy in the mold cavity. The first furnace provides the first molten metal alloy to the first runner system. The second furnace provides the second molten metal alloy to the second runner system, and the first molten metal alloy and the second molten metal alloy concurrently flow into the mold cavity.

In accordance with another aspect of the disclosure, the first molten metal alloy and the second molten metal alloy are different compositions.

In accordance with another aspect of the disclosure, the first molten metal alloy and the second molten metal alloy are different compositions. The first molten metal alloy and the second molten metal alloy are determined at least partially based on virtual casting tools to duplicate material properties of high-volume high pressure die casting (HPDC) production parts.

In accordance with another aspect of the disclosure, the prototype sand-casting system includes a third furnace that provides a third molten metal alloy to a third runner system. The third runner system is fluidly coupled and provides the third molten metal alloy to the mold cavity.

In accordance with another aspect of the disclosure, the third molten metal alloy is different than the first molten metal alloy and the second molten metal alloy.

In accordance with another aspect of the disclosure, the prototype sand-casting system includes at least one riser fluidly coupled to the mold cavity.

According to several aspects of the present disclosure, a method for providing a sand cast prototype replicating material properties of a high pressure die cast is provided. The method includes providing a first molten metal alloy to a runner system from a first furnace. The first molten metal alloy is determined at least partially based on virtual casting tools to duplicate material properties of high-volume high pressure die casting (HPDC) production parts. The method further includes providing a second molten metal alloy to the runner system from a second furnace. The second molten metal alloy is determined at least partially based on virtual casting tools to duplicate material properties of high-volume high pressure die casting (HPDC) production parts. The method further includes flowing the first molten metal alloy and the second molten metal alloy from the runner system to a sand-casting mold including a mold cavity having a predetermined shape of a casting.

In accordance with another aspect of the disclosure, the first molten metal alloy and the second molten metal alloy are different compositions.

In accordance with another aspect of the disclosure, the method includes providing a third molten metal alloy to the runner system from a third furnace. The third molten metal alloy is determined at least partially based on virtual casting tools to duplicate material properties of high-volume high pressure die casting (HPDC) production parts.

In accordance with another aspect of the disclosure, the third molten metal alloy is different than the first molten metal alloy and the second molten metal alloy.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

FIG. 1 is a diagrammatic illustration of a simplified prototype sand-casting system having a runner system with a single runner, in accordance with the present disclosure;

FIG. 2 is a diagrammatic illustration of a simplified prototype sand-casting system having a runner system with a first runner and a second runner, in accordance with the present disclosure;

FIG. 3 is a top view of the prototype sand-casting system illustrated in FIGS. 1 and 2, in accordance with the present disclosure;

FIG. 4 is a side cross section view of the prototype sand-casting system shown in FIGS. 1 and 2 along lines 4-4 illustrated in FIG. 3, in accordance with the present disclosure; and

FIG. 5 is a flowchart illustrating a method for providing the sand cast prototype that replicates material properties of a high pressure die cast using the prototype sand-casting system depicted FIGS. 1 and 2, in accordance with the present disclosure.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. The illustrated embodiments are disclosed with reference to the drawings, where like numerals indicate corresponding parts throughout the several drawings. The figures are not necessarily to scale, and some features may be exaggerated or minimized to show details of particular features. The specific structural and functional details disclosed are not intended to be interpreted as limiting, but as a representative basis for teaching one skilled in the art as to how to practice the disclosed concepts.

The system and method disclosed herein use a virtual casting tool and multiple concurrent casting alloys for matching sand cast prototype mechanical properties and distribution throughout a mold with a simulated high pressure die cast (HPDC) production part. Typical mechanical property variation predicted in HPDC or other metal mold castings are achieved by using these multiple concurrent casting alloys in a sand cast prototype.

FIG. 1 is a diagrammatic illustration of a simplified prototype sand-casting system 10 in accordance with one aspect of the present disclosure. The prototype sand-casting system 10 is configured to provide a sand-casting prototype with mechanical properties and mechanical distribution similar or equivalent to mechanical properties and distribution of a HPDC or other metal mold production part. The prototype sand-casting system 10 includes a sand-casting mold 12, at least one ingate 14, a runner system 16, a first furnace 18, and a second furnace 20.

The sand-casting mold 12 depicted in FIG. 1 has an internal surface 22 defining a mold cavity 24. The mold cavity 24 is configured to receive a molten metal to form a casting having a predetermined shape of the mold cavity 24. The internal surface 22 includes protruding details and cavities to define the mold cavity 24 having a predetermined shape and geometry for forming the desired contours and features of a cast component, for example for a vehicle (e.g., an engine block). Such protruding details and cavities can form walls and structural elements, for example bosses and ribs (not shown). The shape of the mold cavity 24 is a negative impression of the shape of the predetermined casting. The sand-casting mold 12 can be an additively manufactured (e.g., three-dimension (3D) printed sand cores and molds) and may include a variety of sand compositions (e.g., silica) and sand bonding materials and processes.

Shown in FIG. 1, a riser 26 can be fluidly coupled to the mold cavity 24. The riser 26 is a reservoir coupled to the sand-casting mold 12 for preventing cavities within the mold due to shrinking and for letting gas and steam be released from the mold cavity 24. When molten metal flows into the mold cavity 24, the molten metal enters the riser 26 once the mold cavity 24 is full. As the molten metal is less dense than when in a solid state, a void forms in the casting due to shrinkage caused by cooling. Molten metal is supplied from the riser to feed the mold cavity 24 as the molten metal solidifies and shrinks. Thus, a void forms in the riser 26 instead of the casting. Each riser 26 location and size may be manipulated in the prototype sand-casting system 10 to match porosity expected from HPDC parts. While FIG. 1 illustrates three risers 26, it will be appreciated that less or more risers 26 can be disposed as part of the sand-casting mold 12 and fluidly coupled to the mold cavity 24.

At least one molten metal or alloy, for example a molten aluminum-silicon based alloy, is provided to the mold cavity 24. When determining the molten metal or alloy type and the detailed composition, some considerations for mechanical properties and distribution (e.g., ultimate tensile strength (UTS), yield strength (YS), elongation) and fatigue of each prototype may include porosity/oxide volume fraction (more porosity farther from each ingate), secondary phase particle volume fraction and sizes, secondary dendrite arm spacing (a sand casting cools slower than a HPDC casting and thus secondary dendrite arm spacing in sand casting in typically larger than that of a HPDC casting), and so forth. Factors to consider when determining molten metal alloys that affect local microstructure and defects may include alloy composition (when multiple ingates are used), melt treatment, gating/riser design, melt pouring temperature, a local 3D print core, local chill, heat treatment design, multiple sand types used in the sand core, and/or sand bonding processes. The molten metal or molten alloy can include a variety of elements, for example, aluminum (Al), silicon (Si), iron (Fe), copper (Cu), magnesium (Mg), manganese (Mn), zinc (Zn), strontium (Sr), and the like. The simulated molten metal alloy can be used for early product development, weldability, machining, mechanical property testing, and/or early product validation.

In an example, a first molten metal alloy 28 and a second molten metal alloy 30, which are different alloys and have different metal alloying treatment, flow into and at least partially mix within the mold cavity 24. Multiple concurrent casting alloys are used to mimic HPDC casting. When HPDC prototype casting with a single melt, the melt may have different material properties (e.g., elongation) at different locations within the mold, which may be difficult to predict. For example, when HPDC casting, prediction of material properties close to the ingates is good, while farther from the ingates is less accurate, which is also amplified when giga-casting. Using different molten metal alloys within a sand cast is advantageous because each alloy behaves differently in different portions of the mold cavity 24 and can predict molten metal alloys within a prototype HPDC mold. The first molten metal alloy 28 and the second molten metal alloy 30 may be disposed in different regions/zones of the mold cavity 24 to match mechanical property predictions to that of a metal mold (e.g., a HPDC mold). Thus, using a sand cast prototype with multiple molten metal alloys gives better predicted uniform qualities throughout the casting.

In an example, the first molten metal alloy 28 includes an aluminum-silicon based alloy, and the second molten metal alloy 30 is an aluminum-silicon based alloy that is different than the first molten metal alloy 28. In some instances, and as shown in FIG. 1, a third molten metal alloy 32 may also flow into the mold cavity 24 from a third furnace 34 and at least partially mix with the first molten metal alloy 28 and the second molten metal alloy 30 within the mold cavity 24. In some instances, two of the first molten metal alloy 28, the second molten metal alloy 30, or the third molten metal alloy 32 may be the same alloy while the other is a different alloy.

Shown in FIG. 1, the prototype sand-casting system 10 includes at least one ingate 14 (or inner gate). The ingate 14 is in fluid connection with the mold cavity 24 and is a conduit configured to direct a molten metal alloy (e.g., first molten metal alloy 28, second molten metal alloy 30, third molten metal alloy 32) into the mold cavity 24 to form the prototype sand casting. Each ingate 14 is configured to ensure that molten metal alloy flow is proportional to the volume of the mold cavity 24 for a given casting section and to ensure that the molten metal alloy completely fills that respective section of the mold cavity 24. Additionally, each ingate 14 can facilitate mixing of multiple molten metal alloys (e.g., first molten metal alloy 28, second molten metal alloy 30, third molten metal alloy 32).

Location (e.g., an ingate 14, the mold cavity 24, and the like) of mixing of the molten metal alloys can be determined by a virtual casting tool to optimize sand cast material properties, for example porosity. Another mechanical property variation that may be predicted is elongation distribution throughout the sand cast prototype. Typically, elongation distribution and degradation increases proportionally to distance from each ingate 14. Thus, when multiple ingates are used and location of each ingate is optimized, less degradation throughout the sand cast prototype occurs. In the example depicted in FIG. 1, the prototype sand-casting system 10 has multiple ingates including a first ingate 14A, a second ingate 14B, a third ingate 14C, and a fourth ingate 14D. In some aspects, the prototype sand-casting system 10 may include additional ingates (e.g., a fifth ingate, a sixth ingate, and so forth) or less ingates (e.g., three ingates, two ingates).

Still referring to FIG. 1, the runner system 16 is at least one runner 36 (e.g., a channel) fluidly coupled to the at least one ingate 14. The runner system 16 facilitates smooth flow of molten metal to the at least one ingate 14 and reduces velocity of the molten metal ensuring a steady flow and preventing slag from entering the mold cavity 24. Shown in FIG. 1, the runner system 16 has a single runner 36 fluidly coupled to the first ingate 14A, the second ingate 14B, the third ingate 14C, and the fourth ingate 14D. When a single runner 36 is used, the first molten metal alloy 28, the second molten metal alloy 30, and the third molten metal alloy 32 (when included) mixes in the single runner 36 giving a softer mechanical property differential of the casting within the mold cavity 24.

Referring to FIG. 2, a prototype sand-casting system 10 is illustrated having a runner system 16 with a first runner 38 and a second runner 40. In this example with multiple runners, the prototype sand-casting system 10 also includes a sand-casting mold 12, a first furnace 18, and a second furnace 20. The first runner 38 fluidly couples the first furnace 18 directly to the mold cavity 24 of the sand-casting mold 12 such that the first molten metal alloy 28 does not contact the second runner 40. The first runner 38 flows the first molten metal alloy 28 to the mold cavity 24. The second runner 40 fluidly couples the second furnace 20 directly to the mold cavity 24 such that the second molten metal alloy 30 does not contact the first runner 38. The second runner 40 flows the second molten metal alloy 30 directly into the mold cavity 24. The first runner 38 and the second runner 40 may not include a separate ingate as in the prototype sand-casting system 10 illustrated in FIG. 1 or may not include an ingate at all. As the first molten metal alloy 28 and the second molten metal alloy 30 flow into the mold cavity 24, the first molten metal alloy 28 and the second molten metal alloy 30 at least partially mix while in the mold cavity 24 to replicate material properties of a HPDC casting within the prototype sand-casting system 10 and in accordance with predictions of the virtual casting tool.

Referring again to FIG. 1, the first furnace 18 is fluidly coupled to the runner system 16. The first furnace 18 is configured to melt and provide the first molten metal alloy 28 to the runner system 16 and the mold cavity 24. The first furnace 18 can include, for example, an induction furnace, an electric arc furnace, a crucible furnace, and the like. Additionally, the first furnace 18 may be a low-pressure furnace and configured to provide the first molten metal alloy 28 under no or low pressure to the runner system 16.

Additionally, FIG. 1 shows the second furnace 20 fluidly coupled to the runner system 16. The second furnace 20 is configured to provide the second molten metal alloy 30 to the runner system 16 and the mold cavity 24. The second furnace 20 can include, for example, an induction furnace, an electric arc furnace, a crucible furnace, and the like. FIG. 1 also illustrates the optional third furnace 34, which is fluidly coupled and provides the third molten metal alloy 32 to the runner system 16. In some aspects, the prototype sand-casting system 10 can include additional furnaces (e.g., a fourth furnace, a fifth furnace, and so forth). Moreover, the prototype sand-casting system 10 may include additional components, for example a pouring device (not shown) for pouring each molten metal alloy from respective furnaces.

FIG. 3 is a top view of the prototype sand-casting system 10 illustrated in FIGS. 1 and 2. The first molten metal alloy 28 is shown flowing into a first portion 42 of the mold cavity 24, and the second molten metal alloy 30 is shown flowing into a second portion 44 of the mold cavity 24. The first molten metal alloy 28 and the second molten metal alloy 30 at least partially mix with in the mold cavity 24.

FIG. 4 is a side cross section view of the prototype sand-casting system 10 along lines 4-4 illustrated in FIG. 3. As shown in FIG. 3, the first molten metal alloy 28 flows into the first portion 42 of the mold cavity 24 through a first ingate 14A, and the second molten metal alloy 30 flows into the second portion 44 of the mold cavity 24 through a second ingate 14B. The view in FIG. 4 shows the first molten metal alloy 28 and the second molten metal alloy 30 mixing proximate to a central location 46 between the first ingate 14A and the second ingate 14B. In other instances, the first molten metal alloy 28 and the second molten metal alloy 30 (and other alloys, if included) also mix throughout the mold cavity 24.

FIG. 5 is a flowchart illustrating a method 100 for providing the sand cast prototype that duplicates material properties of a high pressure die casting part using the prototype sand-casting system 10 illustrated in FIGS. 1 and 2.

Starting at block 102, method 100 includes providing the first molten metal alloy 28 to a runner system 16 from the first furnace 18. Providing the first molten metal alloy 28 may include determining a composition of the first molten metal alloy 28. The first molten metal alloy 28 composition is determined at least partially based on a virtual casting tool. The virtual casting tool may include a software simulation configured to design and tailor multi-scale defects and microstructure in the sand cast prototype. The virtual casting tool determines the first molten metal alloy 28 composition to duplicate or replicate material properties of high-volume high pressure die casting (HPDC) production parts. In an example, the virtual casting tool determines a castable product geometry, provides a sand-casting process simulation, provides a sand cast prototype microstructure and porosity prediction, and provides a sand cast prototype part local property prediction. The simulation and resulting predictions are then used to determine and provide the composition of the first molten metal alloy 28. The method 100 then proceeds to block 104.

Block 104 includes providing the second molten metal alloy 30 to the runner system 16 from the second furnace 20. The composition of the second molten metal alloy 30 is determined at least partially based on the virtual casting tool. Similarly for the first molten metal alloy 28, the virtual casting tool determines the second molten metal alloy 30 composition to duplicate material properties of high-volume high pressure die casting (HPDC) production parts from the sand-casting simulation predictions. Method 100 may then proceed to block 106.

Block 106 includes an optional step of providing a third molten metal alloy 32 to the runner system 16 from a third furnace 34. When included, the third molten metal alloy 32 composition is determined at least partially based on the virtual casting tool. The virtual casting tool determines the third molten metal alloy 32 composition, to duplicate material properties of high-volume high pressure die casting (HPDC) production parts. Method 100 then proceeds to block 108.

Block 108 includes flowing the first molten metal alloy 28 and the second molten metal alloy 30 from the runner system 16 to the sand-casting mold 12 and the mold cavity 24. Flowing the first molten metal alloy 28 and the second molten metal alloy 30 includes pouring each molten metal alloy respectively from the first furnace 18, the second furnace 20, and/or the third furnace 34. The virtual casting tool prediction and prototype casting steps (e.g., block 102, block 104, block 106, and/or block 108) may be repeated until the mechanical properties of the sand cast prototype are similar or equivalent to predicted mechanical properties of the HPDC product. The method 100 then ends.

The prototype sand-casting system 10 and method 100 for providing a sand cast prototype of the present disclosure offers several advantages. Because development of a high-pressure die cast (HPDC) prototype can be expensive and time-consuming, the prototype sand-casting system 10 is advantageous and designed to duplicate a HPDC process rather than be optimized for peak sand-casting material properties. Using sand casting method for developing the HPDC prototype reduces the amount of time required and expense because of the reduced time requirement and the expense of sand casting.