CASTING APPARATUS

Description

FIELD

The present disclosure relates to an apparatus for casting, and more particularly to an apparatus for casting a single crystal part, intermediate component.

BACKGROUND

Some applications of metals require components or parts that are exceptionally wear resistant and heat resistant. Among these applications are engines such as aircraft engines. Conventionally, such durable components are produced from single crystal components. Such single crystal components are produced by precise cooling and controlled crystallization of a molten metal within a mold. The crystallization begins at a seed crystal and proceeds in a predetermined direction relative to the seed crystal.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present disclosure, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1A is a side cross-sectional view of an exemplary casting apparatus with a plurality of molds in a heater.

FIG. 1B is a side cross-sectional view of the exemplary casting apparatus of FIG. 1A with the plurality of molds lowered into a cooler.

FIG. 2 is a schematic view of a baffle of the exemplary casting apparatus of FIGS. 1A-1B along the line 2-2.

FIG. 3 is a schematic view of a cooling plate of the exemplary casting apparatus of FIGS. 1A-1B along the line 3-3.

FIG. 4 is a schematic view of another baffle.

FIG. 5 is a schematic view of another cooling plate.

DETAILED DESCRIPTION

Reference will now be made in detail to present embodiments of the disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the disclosure.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations. Additionally, unless specifically identified otherwise, all embodiments described herein should be considered exemplary.

The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.

The present disclosure is generally related to casting components with directional solidification. In general, directional solidification furnaces for columnar grain or single crystal components, such as aerospace turbine blades, are designed for multi-piece molds. Such multi-piece molds may include molds to form large amounts of components, such as 20 turbine blades. During the casting process, molten casting material (such as molten metal) is poured into the molds, and chill plates cool the molds to solidify the casting material. Because the molds are generally close together, shadowing and neighbor effects may inhibit heat transfer from the chill plates. Moreover, a centralized integral pour cups may cover parts of the chill plates, reducing encircled radiant cooling. Such constraints may lead to uneven microstructures in the finished component resulting from portions of the molten casting material cooling faster than other portions of the molten casting material.

To provide more even cooling of the molten casting material, a baffle can be disposed between a heater of the directional solidification furnace and the chill plate to block thermal radiation emitted by the heater, allowing molten casting material in the molds beneath the baffle to solidify evenly. Additionally, the baffle blocks the thermal radiation from reaching the chill plate, which allows the chill plate to completely encircle the molds. The complete encirclement provides evenly circumferential heat transfer from the molds, cooling the casting material evenly. This improved cooling improves the microstructures of the columnar grain or single crystal component. In particular, the improved microstructure improves the crystalline structure of the component, which may improve mechanical properties of the component, such as greater tensile strength, reduced cracking, and the like.

Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures. FIGS. 1A-1B are a cross-sectional views of an exemplary casting apparatus 100 for directional solidification of a columnar grain or single crystal part. The casting apparatus 100 includes a heater 102, a material supply 104, a cooler 106, a baffle 108, and a plurality of molds 110. The casting apparatus 100 is configured to cast directionally solidified parts that are formed of a single crystal grown from a seed crystal or with columnar grains extending along the length of the part. Such parts may include turbine blades and the like. FIG. 1A shows the plurality of molds 110 raised into the heater 102, i.e., at a first position at a beginning of the directional solidification process. FIG. 1B shows the plurality of molds 110 at a second position lowered into the cooler 106, which cools and solidifies the lower portion of the material provided to the plurality of molds 110.

The heater 102 provides heat to casting material, maintaining the liquid state of the molten casting material so that the casting material can be deposited into the plurality of molds 110. The heater 102 includes a heating wall 112 and a heating ceiling 114. The heating wall 112 and the heating ceiling 114 define an interior heating chamber 116. The interior heating chamber 116 is a cavity or space into which material designed to be heated is placed, such as a molten casting material. Heat radiates from the heating wall 112 and the heating ceiling 114 into the interior heating chamber 116 (shown as arrows H in FIGS. 1A-1B), heating material disposed in the interior heating chamber 116. When the heater 102 is under a vacuum, the only mode of heat transfer to the molten casting material may be radiative heating from the heater 102. The heater 102 may be a directional solidification furnace configured to heat material that is deposited into the plurality of molds 110 to cast directionally solidified parts. In particular, the heater 102 may maintain a temperature of the interior heating chamber 116 beyond a melting temperature of the casting material, preventing the casting material from solidifying.

The material supply 104 distributes the molten casting material and deposits the molten casting material into the plurality of molds 110. The material supply 104 is disposed in the interior heating chamber 116 and is heated by the heater 102 to maintain the liquid state of the molten casting material in the material supply 104. Specifically, the material supply 104 includes a material housing 118 (such as a tundish), a supply support 120, and one or more material depositors 122 extending from the material housing 118. The material housing 118 distributes the molten casting material received from a material source (not shown) exterior to the casting apparatus 100, and the material depositors 122 transmit the molten casting material to the plurality of molds 110. In the first position shown in FIG. 1A, the material depositors 122 are disposed above and spaced from the plurality of molds 110 such that molten casting material flows through each of the material depositors 122 and down into the plurality of molds 110. That is, the material depositors 122 are disconnected from the plurality of molds 110, and the molten casting material is exposed to the heater 102 prior to flowing into the plurality of molds 110. The supply support 120 holds the material housing 118 and the material depositors 122 in the interior heating chamber 116. The material supply 104 may be formed of high-temperature resistant material that does not melt at temperatures to which the interior heating chamber 116 is heated.

The cooler 106 assists in solidifying the molten casting material in the plurality of molds 110. The cooler 106 is disposed beneath the heater 102. More specifically, the cooler 106 includes a cooling wall 124 and a cooling plate 126. The cooling wall 124 and the cooling plate 126 define an interior cooling chamber 128 therebetween. The heating wall 112 is spaced above the cooling wall 124 by a support 130 extending from the heating wall 112 to the cooling wall 124. The support 130 extends from the heater 102 to the cooler 106, separating the heater 102 from the cooler 106. In FIGS. 1A-1B, the supply support 120 is also supported by the support 130 by a supply base 121, specifically, the supply base 121 may be located at a center portion of the support 130. Alternatively, it will be appreciated that the supply support 120 may be arranged on the support 130 in any suitable manner. In the arrangement shown in FIGS. 1A and 1B, the material housing 118, material depositors 122, and the supply support 120 of the material supply 104 remain within the interior heating chamber 116 when the plurality of molds 110 are lowered into the cooler 106 as shown in FIG. 1B, increasing the cooling efficiency of the plurality of molds 110 in the cooler 106. However, in some embodiments, the material supply 104 may be supported by the cooling plate 126 and lowered into the cooler 106 along with the plurality of molds 110.

The cooler 106 cools the molten casting material in the plurality of molds 110 by transferring away heat emitted from the plurality of molds 110 (shown as arrows C in FIGS. 1A-1B), forming the part by directional solidification. When the cooler 106 is under a vacuum, the only mode of heat transfer may be thermal radiation emitted by the plurality of molds 110. More specifically, in the second position shown in FIG. 1B, the cooling wall 124 transfers heat radiated from the plurality of molds 110 away from the interior cooling chamber 128, decreasing a temperature of an exterior surface 132 of the plurality of molds 110. The cooling plate 126 defines an upper surface 134 that is exposed to the interior cooling chamber 128, and the plurality of molds 110 are disposed on the upper surface 134 of the cooling plate 126, which conducts heat away from the plurality of molds 110. The cooler 106 may be an apparatus that uses a working fluid to remove heat from the plurality of molds 110, such as a forced gas cooler or a fluidized bed cooler.

The baffle 108 is disposed between the heater 102 and the cooler 106 and surrounds the plurality of molds 110. Specifically, the baffle 108 is fixed to the support 130 between the heater 102 and the cooler 106 with a suitable fastener 136, such as a pin, a bolt, or the like. The baffle 108 defines a plurality of openings 138, and each of the plurality of molds 110 is disposed in one of the plurality of openings 138. More specifically, each of the plurality of material depositors 122 is arranged above one of the openings 138 of the baffle 108 to provide molten casting material to the respective one of the plurality of molds 110 or only a subset of the plurality of molds 110 disposed in the respective one of the openings 138. The baffle 108 may be shaped to extend along the cooling wall 124, e.g., in a circular shape. It will be appreciated that the baffle 108 may have a suitable shape to fit within the casting apparatus 100, in particular, a shape that allows for secure attachment to the support 130. In FIGS. 1A-1B, the baffle 108 is fixed to a lower surface of the support 130, and it will be appreciated that the baffle 108 may be fixed to the support 130 in any suitable manner, such as to a top surface of the support 130, to an interior surface of the support 130, to multiple surfaces of the support 130, or variations and combinations thereof. In some embodiments, the baffle 108 and the support 130 may be a single-piece, integrated structure.

The baffle 108 is arranged to block thermal radiation from the heater 102 from reaching the cooler 106. That is, the baffle 108 is formed of a heat-resistant material that absorbs or reflects the thermal radiation that radiates from the heating wall 112, stopping the thermal radiation from reaching the cooler 106. Such a heat-resistant material may absorb or reflect thermal radiation emitted by the heater 102, inhibiting portions of the casting apparatus 100 that are not within a line of sight of the heater 102 from heating. In particular, the baffle 108 includes an interior portion 140 that is disposed above the cooling plate 126 such that the baffle 108 is between the heater 102 and the cooling plate 126, blocking the thermal radiation emitted by the heater 102 from reaching the cooling plate 126. The baffle 108 may be disposed against the cooling wall 124 to block the thermal radiation from reaching the cooling wall 124. By positioning the baffle 108 to block the thermal radiation from the heater 102, operation of the cooler 106 is improved because less heat reaches the plurality of molds 110 beneath the baffle 108, reducing the amount of heat that the cooler 106 must transfer away during the solidification process. The improved cooling of the molten casting material in the plurality of molds 110 improves the microstructure of the solidified components. In some embodiments, the heating ceiling 114 is attached to and/or supported on the interior portion 140 of the baffle 108.

The plurality of molds 110 receive material from the material supply 104 to form the components. Each of the plurality of molds 110 is a single unit and separate from other molds 110. That is, the plurality of molds 110 are individual, distinct molds each for casting a part, rather than a single connected structure that can cast a plurality of parts. Each of the plurality of molds 110 extends from the cooler 106 through the baffle 108 and into the interior heating chamber 116 of the heater 102. In the interior heating chamber 116, each of the plurality of molds 110 is disposed beneath a material depositor 122 of the material supply 104 to receive molten casting material from the material depositors 122.

More specifically, each of the plurality of molds 110 includes a base 142 in the interior cooling chamber 128 supported by the cooling plate 126 and a housing 144 extending upward through the baffle 108 into an interior heating chamber 116 of the heater 102 beneath the material depositors 122. Each base 142 is separate from each other base 142 of the plurality of molds 110, supported in a “spaced-apart” arrangement on the cooling plate 126. That is, each base 142 is separated from each other base 142 by at least a portion of the cooling plate 126. Upon receiving the molten casting material from the material depositors 122, the plurality of molds 110 transfer heat from the molten casting material to the cooler 106, such as to the cooling plate 126, to solidify the molten casting material. In particular, the housing 144 of each of the plurality of molds 110 emits heat into the cooling chamber 128 which may be absorbed by the cooling wall 124, and the base 142 of each of the plurality of molds 110 conducts heat to the cooling plate 126.

The plurality of molds 110 may solidify the molten casting material in columnar grains or as single crystals, forming components with improved mechanical strength and resilience. Because the casting apparatus 100 includes more than one mold 110, a plurality of components may be cast at once, reducing the overall time needed to form a specified number of cast components. This reduction in manufacturing time improves changeover, reduces withdrawal time, and uses less overall casting material that may otherwise be used in the casting apparatus 100. FIG. 2 shows eight molds 110, and it will be appreciated that the plurality of molds 110 may include a different number of molds 110, such as 10, 12, 15, or 20.

The plurality of molds 110 are movable through the openings 138 of the baffle 108 during the directional solidification process. Specifically, at a beginning of the directional solidification process, an entirety of each of the plurality of molds 110 may be disposed in the heater 102 and receives molten casting material from the material depositors 122. Then, each of the plurality of molds 110 is withdrawn into the cooler 106 at a controlled speed. As the plurality of molds 110 descend into the cooler 106, the casting material solidifies directionally to form the directionally solidified part.

The plurality of molds 110 extend through the openings 138 of the baffle 108 into the interior heating chamber 116 of the heater 102. More specifically, the housing 144 of each of the plurality of molds 110 defines a respective exterior surface 132 (FIGS. 2-3), and the baffle 108 extends around at least a portion of the exterior surface 132 of each of the plurality of molds 110. The baffle 108 shields the cooling plate 126, the interior cooling chamber 128, and a lower portion of each of the plurality of molds 110 from heat emitted by the heater 102, improving cooling of the molten casting material. More specifically, the upper surface 134 of the cooling plate 126 includes an interior portion 146 disposed radially inward of the plurality of molds 110, and the interior portion 140 of the baffle 108 is disposed between the interior portion 146 of the cooling plate 126 and the heater 102. The baffle 108 blocks thermal radiation from reaching the interior portion 146 of the cooling plate 126, allowing the cooling plate 126 to provide heat transfer in the cooling chamber 128 around the exterior surface 132 of each of the plurality of molds 110, as described in greater detail below.

The plurality of molds 110 are arranged on the cooling plate 126 to receive and solidify the molten casting material when the cooling plate 126 moves from the first position to the second position. Specifically, the first position includes alignment of the material supply 104 with the housing 144 of each of the plurality of molds 110 for receiving the molten casting material into the plurality of molds 110 and alignment of the base 142 of each of the plurality of molds 110 with the plurality of openings 138 in the baffle 108 to shield the interior cooling chamber 128 and the exposed portion of the upper surface 134 of the cooling plate 126 from the heater 102, and the second position includes alignment of the housing 144 of each of the plurality of molds 110 at the plurality of openings 138 in the baffle 108 such that the plurality of molds 110 are positioned within the interior cooling chamber 128. By aligning the material supply 104 with the plurality of molds 110 in such a manner, the molten casting material solidifies in the plurality of molds 110 directionally to form the directionally solidified part.

Now referring to FIG. 2, a cross-sectional schematic view of the baffle 108 and the plurality of molds 110 of the casting apparatus 100 along the line 2-2 in FIGS. 1A-1B is shown. As described above, the baffle 108 includes a plurality of openings 138 arranged around an interior portion 140, and each of the plurality of molds 110 extends through one of the plurality of openings 138. In FIG. 2, each of the openings 138 extends entirely around an exterior surface 132 of one of the plurality of molds 110. Because the baffle 108 blocks thermal radiation emitted by the heater 102, only the portions of the plurality of molds 110 extending out from the openings 138 of the baffle 108 and portions of the plurality of molds 110 exposed by the gaps between the openings 138 of the baffle 108 and the exterior surfaces 132 are directly exposed to thermal radiation. In this form, the molten casting material in the material supply 104 is heated by the heater 102 (FIGS. 1A-1B) to maintain its liquid state, and the molten casting material flows into each of the plurality of molds 110. Then, the plurality of molds 110 are withdrawn through the baffle 108 into the cooler 106, and the portions of the plurality of molds 110 in the cooler 106 are shielded by the baffle 108.

Now referring to FIG. 3, a cross-sectional view of the cooling plate 126 and the plurality of molds 110 of the casting apparatus 100 along the line 3-3 in FIGS. 1A-1B is shown. As described above, the cooling plate 126 supports the plurality of molds 110 and transfers heat away from the molten casting material. More specifically, the base 142 of each of the plurality of molds 110 defines a perimeter 148, and the cooling plate 126 provides heat transfer around at least a portion of the perimeter 148. In FIG. 3, the cooling plate 126 contacts the base 142 along the perimeter 148 of each of the plurality of molds 110, providing a circumferentially even heat transfer gradient from the molten casting material through the base 142 of each of the plurality of molds 110 to the cooling plate 126. The consistent heat transfer, conducted by the cooling plate 126 around the base 142 of each of the plurality of molds 110 and emitted by the housing 144 of each of the plurality of molds 110 to the cooling chamber 128, improves crystal growth and grain formation of the casting material, which provides a more consistent crystalline structure for the solidified component.

With reference to FIG. 4, a cross-sectional view of a baffle 150 and a plurality of molds 110 of another casting apparatus according to some embodiments is shown. In FIG. 4, openings 152 of the baffle 150 open to an outer edge 154 of the baffle 150, such that each of the plurality of molds 110 is disposed along the outer edge 154. In such a form, the baffle 150 may be designed to arrange the plurality of molds 110 at specified locations in the casting apparatus, such as beneath a material depositor of a material supply 104 (FIGS. 1A-1B), while shielding portions of the plurality of molds 110 from thermal radiation emitted by the heater 102 (FIGS. 1A-1B).

With reference to FIG. 5, a cross-sectional view of a cooling plate 126 and the plurality of molds 110 of the casting apparatus of FIG. 4 is shown. The cooling plate 126 extends contacts a portion of a perimeter 148 of an exterior surface 132 of each of the plurality of molds 110, such as at least 50% of the perimeter 148 of the exterior surface 132 of each of the plurality of molds 110. The cooling plate 126 thus provides heat transfer to only a portion of the perimeter 148, and the remainder of the base 142 may transfer heat to the cooling wall 124. Because the baffle 150 shields an interior portion 146 of the cooling plate 126 from thermal radiation emitted by the heater, the interior portion 146 of the cooling plate 126 can more evenly transfer heat away from the exterior surface 132 of each of the plurality of molds 110. This improved heat transfer from the plurality of molds 110 may cause the molten casting material to solidify into an improved crystalline structure, such as more even columnar grains or more consistent single crystal growth. The improved crystalline structure may improve mechanical properties of the component, such as greater tensile strength, reduced cracking, and the like.

Further aspects are provided by the subject matter of the following clauses:

A casting apparatus including a heater including a heating wall defining an interior heating chamber, a material supply disposed in the interior heating chamber, the heater configured to provide heat to the material supply, a cooler disposed beneath the heater, the cooler including a cooling wall defining an interior cooling chamber and a cooling plate configured to support a plurality of molds on an upper surface thereof, and a baffle disposed between the heater and the cooler, the baffle attached to one or both of the heating wall or the cooling wall and extending across the heater and cooler thereby separating the interior cooling chamber from the interior heating chamber, the baffle including a plurality of openings, each one of the plurality of openings configured to receive a respective one of the plurality of molds, wherein the cooling plate is movable from a first position to a second position, the first position positions the plurality of molds to receive a molten casting material from the material supply while shielding the interior cooling chamber and the cooling plate from the heater and the second position positions the plurality of molds within the interior cooling chamber to solidify the molten casting material in the plurality of molds.

The casting apparatus of any of the previous clauses, wherein each of the plurality of molds defines a housing having an exterior surface, and each of the plurality of openings of the baffle is configured to extend around at least a portion of the exterior surface of the each of the plurality of molds.

The casting apparatus of any of the previous clauses, wherein, in the first position, the heater is configured to extend around at least a portion of the exterior surface of each of the plurality of molds.

The casting apparatus of any of the previous clauses, wherein, in the second position, the cooler is configured to extend around at least a portion of the exterior surface of each of the plurality of molds.

The casting apparatus of any of the previous clauses, the plurality of molds are disposed on the cooling plate, and the cooling plate is configured to extend around at least a portion of the exterior surface of each of the plurality of molds.

The casting apparatus of any of the previous clauses, wherein each of the plurality of molds includes a base defining a perimeter, and the cooling plate is configured to extend around at least 50% of the perimeter of the exterior surface of each base of the plurality of molds.

The casting apparatus of any of the previous clauses, wherein the cooling plate extends around the perimeter of each base of the plurality of molds.

The casting apparatus of any of the previous clauses, further including the plurality of molds, each of the plurality of molds including a base and a housing extending upward from the base, each base separate from one another and supported in a spaced-apart arrangement on the cooling plate such that a portion of the upper surface of the cooling plate is exposed within the interior cooling chamber, wherein the first position includes alignment of the material supply with the housing of each of the plurality of molds for receiving the molten casting material into the plurality of molds and alignment of the base of each of the plurality of molds with the plurality of openings in the baffle to shield the interior cooling chamber and the exposed portion of the upper surface of the cooling plate from the heater, and the second position includes alignment of the housing of each of the plurality of molds at the plurality of openings in the baffle such that the plurality of molds are positioned within the interior cooling chamber.

The casting apparatus of any of the previous clauses, wherein the heater is a directional solidification furnace.

The casting apparatus of any of the previous clauses, wherein the heater further includes a heating ceiling, wherein the heating ceiling, the heating wall, and the baffle define the interior heating chamber.

The casting apparatus of any of the previous clauses, further including a support extending from the heater to the cooler, wherein the baffle is fixed to the support.

The casting apparatus of any of the previous clauses, further including a fastener, wherein the baffle is fixed to the support with the fastener.

The casting apparatus of any of the previous clauses, wherein the cooler is one of a forced gas cooler or a fluidized bed cooler.

The casting apparatus of any of the previous clauses, wherein the material supply further includes a plurality of material depositors, each of the plurality of material depositors arranged above one of the plurality of openings of the baffle.

The casting apparatus of any of the previous clauses, further including a support extending from the heater to the cooler, wherein the material supply includes a material housing and a supply support, the supply support being supported on the support.

The casting apparatus of any of the previous clauses, wherein the material supply further includes a plurality of material depositors extending from the material housing, each of the plurality of material depositors arranged above one of the plurality of openings of the baffle.

The casting apparatus of any of the previous clauses, wherein each of the plurality of material depositors is spaced above one of the plurality of molds disposed in the plurality of openings.

The casting apparatus of any of the previous clauses, wherein the supply support is arranged to hold the material housing and the material depositors in the interior heating chamber.

The casting apparatus of any of the previous clauses, wherein the supply support includes a supply base disposed on the support.

The casting apparatus of any of the previous clauses, wherein the support separates the heating wall from the cooling wall.

This written description uses examples to disclose the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.