US20200101528A1 - Steel foam and method for manufacturing steel foam - Google Patents
Steel foam and method for manufacturing steel foam Download PDFInfo
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- US20200101528A1 US20200101528A1 US16/700,338 US201916700338A US2020101528A1 US 20200101528 A1 US20200101528 A1 US 20200101528A1 US 201916700338 A US201916700338 A US 201916700338A US 2020101528 A1 US2020101528 A1 US 2020101528A1
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- pores
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D25/00—Special casting characterised by the nature of the product
- B22D25/005—Casting metal foams
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/08—Features with respect to supply of molten metal, e.g. ingates, circular gates, skim gates
- B22C9/086—Filters
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/10—Cores; Manufacture or installation of cores
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/22—Moulds for peculiarly-shaped castings
- B22C9/24—Moulds for peculiarly-shaped castings for hollow articles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D29/00—Removing castings from moulds, not restricted to casting processes covered by a single main group; Removing cores; Handling ingots
- B22D29/001—Removing cores
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/12—All metal or with adjacent metals
- Y10T428/12479—Porous [e.g., foamed, spongy, cracked, etc.]
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- Powder Metallurgy (AREA)
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Abstract
A steel foam component includes a steel body having a plurality of pores. The plurality of pores forms a generally uniform pattern throughout the body and occupies at least 20 percent of a volume of the body.
Description
- This application is a divisional of U.S. patent application Ser. No. 15/532,746, filed Jun. 2, 2017, which is a national stage entry of International Application No. PCT/US2015/066253, filed Dec. 17, 2015, which is a continuation-in-part of U.S. patent application Ser. No. 14/576,367, filed Dec. 19, 2014, and claims priority to U.S. Provisional Patent Application No. 62/121,620, filed Feb. 27, 2015, the entire contents of each of which are incorporated by reference herein.
- The present invention relates to steel foam and, more particularly, to steel foam and methods of producing steel foam.
- Metal is considered a foam if pores are distributed within the metal to take up a certain minimum percentage of the total volume of the metal. The introduction of pores or voids into a metal component typically decreases the density and weight of the metal component compared to a solid metal component. Metal foam components also frequently display a higher plate bending stiffness than solid metal components. Currently, commercial metal foam components are generally limited to aluminum, despite the fact that steel foam components would exhibit many superior properties if they could be produced in volume at reasonable cost.
- Embodiments of the present invention provide the ability to produce steel foam components having consistent densities. In addition, embodiments of the present invention provide the ability to produce steel foam components having predictable mechanical properties. Furthermore, embodiments of the present invention provide the ability to produce steel foam components on an industrial scale.
- Additional embodiments provide the ability to produce gradient density lightweight steel foam. Further embodiments provide the ability to produce selective variable density lightweight steel foam.
- The present invention provides engineers working with steel a new degree of freedom: density. The design space potentially covered by steel applications can grow significantly with density as a variable. Among other things, the present invention opens new opportunities for designers to find suitable military and naval applications for not only energy absorption, but also blast resistant and ballistic applications to resist the impact of sharp objects due to their high strength and hardness.
- Some embodiments of the present invention provide a method of producing a steel foam component, wherein the method comprises providing a mold defining a cavity, positioning an insert within the cavity of the mold, wherein the insert is configured to form a generally uniform pattern of pores within the steel foam component and occupies at least 20 percent of the cavity, pouring molten steel into the cavity, cooling the molten steel into the steel foam component, and removing the steel foam component and the insert from the mold.
- In some embodiments, the present invention provides a steel foam component comprising a body having a plurality of pores, the plurality of pores forming a generally uniform pattern throughout the body and occupying at least 20 percent of a volume of the body.
- Some embodiments of the present invention provide an insert for use with a mold for creating a steel foam component, wherein the insert comprises a 3D-printed body including a plurality of interconnected cores, the 3D-printed body being configured to be positioned within the mold to form the steel foam component having a desired density that is less than a solid steel component.
- Other aspects of the present invention will become apparent by consideration of the detailed description and accompanying drawings.
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FIG. 1 is a schematic of a system for producing a steel foam component. -
FIG. 2 is a perspective view of an insert for use with the system ofFIG. 1 . -
FIG. 3 is a perspective view of another insert for use with the system ofFIG. 1 . -
FIG. 4 is a perspective view of yet another insert for use with the system ofFIG. 1 . -
FIG. 5 is a perspective view of a steel foam component produced using the insert ofFIG. 3 . -
FIG. 6 is a perspective view of a steel foam component produced using the insert ofFIG. 4 . -
FIG. 7 is a perspective view of a steel foam component produced using the insert ofFIG. 5 . -
FIG. 8 is a flow chart depicting a method of producing a steel foam component using the system ofFIG. 1 . -
FIG. 9 is a perspective view of another steel foam component produced using the insert ofFIG. 2 . -
FIG. 10 is a cross-sectional view of the steel foam component ofFIG. 9 . - Before embodiments of the present invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.
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FIG. 1 illustrates asystem 10 for producing a steel foam component. The illustratedsystem 10 includes a threedimensional mold 14 formed in two halves, a bottom half 18 (i.e., a drag) and a top half 22 (i.e., a cope). Themold 14 is formed from wood or metal and filled with drag sand. Thebottom half 18 and thetop half 22 define acavity 34 within the drag sand of themold 14. Thecavity 34 is formed in the shape of the steel foam component being produced. At least one of thehalves cavity 34. Theopening 38 allows molten steel to be poured into thecavity 34. Thecavity 34 is defined by an upperinner surface 42, a lowerinner surface 46, and an innerperipheral surface 50 extending between the upperinner surface 42 and the lowerinner surface 46. - Positioned within the
pour opening 38 is afilter 62. In some embodiments, thefilter 62 may be composed of alumina. In other embodiments, thefilter 62 may be composed of other materials suitable for use with molten steel. In the illustrated embodiment, thefilter 62 is coupled to thetop half 22 of themold 14. Thefilter 62 is secured within the pour opening 38 and substantially fills a length of the pour opening 38. - The
system 10 also includes at least onechaplet 66 positioned within thecavity 34 of themold 14. Eachchaplet 66 is a relatively thin shim made of metal. Thechaplets 66 support aninsert 78 above the lowerinner surface 46 of the mold so that theinsert 78 is spaced apart from (i.e., does not directly contact) thelower surface 46. -
FIGS. 2-4 illustrate embodiments ofinserts 78 a-c for use in thesystem 10 ofFIG. 1 . In the illustrated embodiments, theinserts 78 a-c are 3D-printed inserts (i.e., inserts formed using a 3D printer). In other embodiments, theinserts 78 a-c may be made using other suitable means. For example, theinserts 78 a-c could be extruded, blow-molded, form molded, cast, packed, machined, carved, or otherwise formed into a desired shaped. The process used to create theinserts 78 a-c can be highly-repeatable (like 3D printing or extruding), can be randomized (like blow-molding), or can be a one-off-type process (e.g., hand sculpted). - In addition, the illustrated
inserts 78 a-c are composed of sand bonded with a chemical binder (e.g., resin), but may alternatively be composed of other suitable materials. As used herein, “sand” refers to any flowable material or media, such as small breads, grains, or granules. For example, the sand may be conventional sand, foundry sand, kinetic sand, sand-fiber mixtures, sand-clay mixtures, ceramics, silica alumina, combinations of materials, and the like. The sand is a media that can withstand high temperatures for steel casting, but is held together by a binder that burns off slowly when exposed to the high temperatures. - Although the
inserts 78 a-c are described below with reference to specific embodiments, it should be readily apparent that other shapes and sizes of inserts may also or alternatively be employed. For example, by creating theinserts 78 a-c with a 3D printer, the geometric configuration of theinserts 78 a-c may be selected and designed to create any desired pattern of pores within a steel component. Furthermore, the dimensions of the inserts78 a-c may be scaled as desired to match the dimensions of any steel component. Multiple inserts may also be positioned within a single mold cavity to achieve desired geometries and sizes. - As shown in
FIG. 2 , theinsert 78 a includes a plurality ofinterconnected cores 82 a. The illustratedcores 82 a are in the form of repeating geometric shapes. By way of example only, theinterconnected cores 82 a are arranged inrows 84 a arranged parallel to a horizontal axis H. The repeatinginterconnected cores 82 a are further arranged incolumns 88 a that are parallel to a vertical axis V. The horizontal axis H and the vertical axis V are used to facilitate discussion of theinserts 78 a-c with reference to the figures, and are not intended to be limiting. - Each of the
interconnected cores 82 a includes acentral portion 86 a andprotrusions 90 a extending from thecentral portion 86 a. The illustratedcentral portions 86 a are spheres. In the illustrated embodiment, fourprotrusions 90 a extend from each of thecentral portions 86 a in directions parallel to either the horizontal axis H or the vertical axis V. As shown, two of theprotrusions 90 a extend parallel to the horizontal axis H and in opposite directions. Further, two of theprotrusions 90 a extend parallel to the vertical axis V and in opposite directions. Theprotrusions 90 a adjacent edges of theinsert 78 a further define ends that are flat surfaces 947 a. Each core 82 a additionally includes twosecondary protrusions 98 a extending in opposite directions from thecentral portions 86 a along a third axis T. The third axis T is perpendicular to the horizontal axis H and the vertical axis V. The illustratedsecondary protrusions 98 a are generally smaller than theprotrusions 90 a. Theprotrusions 98 a further define ends withflat surfaces 102 a. Theinsert 78 a further defines aperiphery 120 a, which includes theendmost rows 84 a (i.e., highest and lowest along the vertical axis V) and theendmost columns 88 a (i.e., leftmost and rightmost along the horizontal axis H.). - Although the illustrated
central portions 86 a are spherical, in other embodiments, thecentral portions 86 a may be non-spherical. For example, thecentral portions 86 a may be square, hexagonal, octagonal, rotund, bulbous, oblong, footballs, and the like. Alternatively, thecentral portions 86 a may essentially be omitted such that theprotrusions central portions 86 a may vary throughout theinsert 78 a. - The illustrated
interconnected cores 82 a inFIG. 2 are connected together using 3D-printing techniques. For example, theinterconnected cores 82 a along theperiphery 120 a are coupled to two otherinterconnected cores 82 a if located at the corners of theinsert 78 a, and are coupled to three otherinterconnected cores 82 a if located elsewhere along theperiphery 120 a of theinsert 78 a. In addition, each core 82 a located within theperiphery 120 a is connected to fourother cores 82 a. In other embodiments, other geometric and non-geometric shapes may be created by interconnecting thecores 82 a in other manners (e.g., thecores 82 a can be connected diagonally, in a honeycomb pattern, as a double helix, in a web, etc.). - As shown in
FIG. 3 ,interconnected cores 82 b of the illustratedinsert 78 b includecentral portions 86 b that are substantially spherical. Further, eachinterconnected core 82 b includes six similarly-sized protrusions 106 b extending from thecentral portions 86 b. Theprotrusions 106 b are oriented such that two of theprotrusions 106 b extend along the vertical axis V in opposite directions, two of theprotrusions 106 b extend along the horizontal axis H in opposite directions, and two of theprotrusions 106 b extend along the third axis T in opposite directions. Eachprotrusion 106 b defines aflat end surface 112 b. - The
interconnected cores 82 b form a plurality ofrows 84 b parallel to the horizontal axis H. Theinterconnected cores 82 b also form a plurality ofcolumns 88 b arranged parallel to the vertical axis V. In the illustrated embodiment, theinsert 78 b includes sixteenrows 84 b and sixteencolumns 88 b ofcores 82 b. Further, theinterconnected cores 82 b form a plurality oflayers 92 b, each formed of sixteen rows and sixteen columns ofinterconnected cores 82 b. Thelayers 92 b are arranged along the third axis T, which is perpendicular to the vertical axis V and the horizontal axis H. In the illustrated embodiment, theinsert 78 b includes twolayers 92 b ofcores 82 b, but may alternatively include three ormore layers 92 b ofcores 82 b. - The
interconnected cores 82 b inFIG. 3 are connected together using 3D-printing techniques. For example, theinterconnected cores 82 b along aperiphery 120 b of theinsert 78 b are coupled to three otherinterconnected cores 82 b if located at the corners of theinsert 78 b, or four otherinterconnected cores 82 b if located elsewhere along aperiphery 120 b of theinsert 78 b. In addition, each core 82 b located within theperiphery 120 b is connected to fiveother cores 82 b. Theperiphery 120 b is defined by theendmost rows 84 b and theendmost columns 88 b of theinsert 78 b. - As shown in
FIG. 4 ,interconnected cores 82 c of theinsert 78 c includecentral portions 86 c and similarly-sized protrusions 106 c having flat end surfaces 112 c, similar to theinterconnected cores 82 b shown inFIG. 3 . Theinsert 78 c ofFIG. 4 , however, includes eightrows 84 c ofcores 82 c that are parallel to the horizontal axis H, and eight columns 88 c ofcores 82 c that are parallel to the vertical axis V. Further, theinterconnected cores 82 c form eightlayers 92 c ofcores 82 b, eachlayer 92 c formed of eight rows and eight columns ofinterconnected cores 82 c. Thelayers 92 c are arranged along the third axis T, which is perpendicular to the vertical axis V and the horizontal axis H. The illustratedinsert 78 c is, thereby, substantially cube-shaped. -
FIG. 5 illustrates asteel foam component 140 a made using theinsert 78 a ofFIG. 2 and thesystem 10 ofFIG. 1 . The illustratedsteel foam component 140 a has abody 144 a in the shape of a rectangular prism. Thecomponent 140 a includes afirst face 148 a that is generally square in shape, asecond face 152 a that is generally square in shape and located opposite the first face 148, and aperipheral edge 156 a extending between thefirst face 148 a and thesecond face 152 a. As shown, theperipheral edge 156 a is four-sided. Thebody 144 a also includes a plurality ofpores 174 a that can form a generally uniform pattern along theperipheral edge 156 a. Thepores 174 a are empty voids in thesteel foam component 140 a. - The
pores 174 a inFIG. 5 each have a similar geometric shape. The similar geometric shape generally matches the shape of theinterconnected cores 82 a of theinsert 78 a ofFIG. 2 . Similar to the arrangement of the plurality ofinterconnected cores 82 a, each of the plurality ofpores 174 a is connected to at least one other of the plurality ofpores 174 a. Thepores 174 a are also arranged in a series ofpore rows 176 a and porecolumns 180 a, corresponding to the number ofrows 84 a andcolumns 88 a of theinsert 78 a. As shown inFIG. 5 , thepore rows 176 a are parallel to the horizontal axis H. Thepore columns 180 a are parallel to the vertical axis V. Although uniformity of thepores 174 a has advantages, it will be appreciated that in other embodiments the core size, shape, and/or arrangement can vary across one or more of these directions as desired for the particular application and component characteristics. For example, the core sizes and/or shapes can increase along at least one of the axes H, V, T. The shapes and/or sizes of thepores 174 a can be varied by changing the shape and/or size of the correspondinginsert 78 a. - As illustrated in
FIG. 5 , thepores 174 a communicate through theperipheral edge 156 a of thesteel foam component 140 a. Theopenings 178 a of the plurality ofpores 174 a that communicate through theperipheral edge 156 a of the steel component are generally the size of theprotrusions 90 a of theinsert 78 a ofFIG. 2 . - In other embodiments, the plurality of
pores 174 a may not communicate with theperipheral edge 156 a and/or may communicate with the first andsecond faces FIG. 5 may be modified such that there areopenings 178 a on thefirst face 148 a and/or thesecond face 152 a. In such embodiments, theopenings 178 a of the plurality ofpores 174 a that communicate through the first and/orsecond faces small protrusions 98 a of theinsert 78 a ofFIG. 2 . As another example, the embodiment shown inFIG. 5 may be modified such that there are no openings on one or more of the faces of theperipheral edge 156 a, such as by eliminating theprotrusions 90 a on such edges of theinsert 78 a shown inFIG. 2 . - Further, the embodiment shown in
FIG. 4 may be modified such that there are onlyopenings 178 a along one side of theperipheral edge 156 a, or only a portion of theopenings 178 a may be on a side of one or moreperipheral edges 156 a. In any case, at least onepore 174 a of the plurality ofpores 174 a is configured to communicate through either theperipheral edge 156 a or the first and/orsecond faces steel foam component 140 a. -
FIGS. 6-7 illustratesteel foam components 140 b-c that are produced using thesystem 10 ofFIG. 1 and theinserts 78 b-c ofFIGS. 3-4 , respectively. Similar to the uniform arrangement ofinterconnected cores 82 b-c inFIGS. 3-4 , respectively, eachsteel foam component 140 b-c includes abody 144 b-c having a plurality ofpores 174 b-c arranged in a uniform manner, withrows 176 b-c ofpores 174 b-c being arranged parallel to the horizontal axis H andcolumns 180 b-c ofpores 174 b-c being arranged parallel to the vertical axis V. Thepores 174 b-c are further arranged in pore layers 182 b-c along the third axis T. The illustrated embodiments showopenings 178 b-c of thepores 174 b-c on theperipheries 120 b-c of thesteel foam components 140 b-c. Theopenings 178 b-c may also or alternatively be located elsewhere on thecomponents 140 b-c. The illustratedopenings 178 b-c are generally the same size as the similarly-sized protrusions 106 b-c of theinserts 78 b-c. - As discussed above in reference to
FIG. 5 , other arrangements ofpores 174 b-c are possible on theperipheral edges 156 b-c and/or the first andsecond faces 148 b-c, 152 b-c of the embodiments shown inFIGS. 6-7 . Further, the pores 174 a-c in the embodiments shown inFIGS. 5-7 occupy at least 20% of the volumes of the respective bodies. In some embodiments, the pores 174 a-c occupy between about 20% and about 60% of the volumes of the bodies 144 a-c. Also, in some embodiments the pores 174 a-c occupy between about 40% and about 60% of the volumes of the bodies 144 a-c. In the illustrated embodiment, the pores 174 a-c occupy approximately 50% of the volumes of the bodies 144 a-c. In further embodiments, the pores 174 a-c may occupy more than 60% of the volumes of the bodies 144 a-c, depending at least in part upon the geometry of theinserts 78 a-c and the desired structural properties of the steel foam components 140 a-c. -
FIG. 8 is a flow chart depicting a method of producing (e.g., casting) a steel foam component 140. References below to the steel foam component 140 generally refer to the steel foam components 140 a-140 c fromFIGS. 2-4 , which are formed using the casting method with theinserts 78 a-c, respectively, fromFIGS. 5-7 , although it will be appreciated that the method discussed below is equally applicable to inserts made of any other core shapes, core sizes, and core arrangements as discussed herein. - At
Step 200, the mold 14 (FIG. 1 ) is provided. As discussed above, themold 14 is made of thebottom half 18 and thetop half 22, which together define thecavity 34. Thecavity 34 is formed to have the shape and dimensions of the desired component 140. Further, themold 14 defines the pouropening 38. At first, thebottom half 18 and thetop half 22 are separated until aninsert 78 is positioned within thecavity 34. - Next, at
Step 204, theinsert 78 is positioned within thebottom half 18 of themold 14. Theinsert 78 can be one of the 3D-printedinserts 78 a-c illustrated inFIGS. 2-4 . Alternatively, theinsert 78 can be another 3D-printed insert having a different size, shape, and/or geometrical configuration than theinserts 78 a-c discussed above, and/or can be an insert produced in any of the other manners described herein. After theinsert 78 is positioned in thecavity 34, thetop half 22 of themold 14 is coupled to (e.g., positioned on top of) thebottom half 18. Theinsert 78 fills a desired volume of thecavity 34 with a generally uniform pattern. The volume filled by theinsert 78 ultimately forms pores 174 (i.e., voids) within the steel foam component 140, as shown inFIGS. 5-7 . As noted above, theinsert 78 occupies at least 20% of the volume of thecavity 34. In other embodiments, theinsert 78 occupies between about 20% and about 60% of the volume of thecavity 34. In other embodiments, theinsert 78 occupies no less than about 60% of the volume of thecavity 34. - In some embodiments, the
insert 78 is positioned in thecavity 34 such that theinsert 78 is spaced apart from the lowerinner surface 46 of themold 14 and/or from the upperinner surface 42 of themold 14. The one ormore chaplets 66, as shown inFIG. 1 , may be used to space theinsert 78 from the lowerinner surface 46 of themold 14. Spacing theinsert 78 from the upper and/or lowerinner surfaces cavity 34 adjacent the upper and/or lowerinner surfaces insert 78 may be positioned within thecavity 34 such that at least a portion of the insert 78 (e.g., the periphery 120) abuts the innerperipheral surface 50. Having theinsert 78 abut the innerperipheral surface 50 inhibits steel from completely filling the volume adjacent thesurface 50. - Positioning the
insert 78 so it is spaced from the lowerinner surface 46 of themold 14 provides the steel foam component 140, after casting, with a continuous first face (i.e., a solid surface without any openings 178 within the first face 148). Positioning theinsert 78 so it is spaced from the upperinner surface 42 of themold 14 provides the steel foam component 140, after casting, with a continuous second face (i.e., a solid surface without any openings 178 within the second face 152). Positioning theinsert 78 so that it abuts the innerperipheral surface 50 of themold 14 creates the openings 178 in the peripheral edges 156 of the steel foam component 140. In some embodiments, theinsert 78 may also or alternatively be spaced apart from the innerperipheral surface 50 of themold 14 so that one or more of the peripheral edges 156 of the steel foam component 140 are continuous. - At
Step 208, thealumina filter 62 is positioned within the pour opening 38 of themold 14. Thefilter 62 can be positioned within theopening 38 when themold 14 is first created, or when themold 14 is assembled after theinsert 78 is in position. In some embodiments, this step may be omitted if a filter is not needed. - At
Step 212, molten steel is poured into thecavity 34 of themold 14 through the pouropening 38. As the molten steel is poured into thecavity 34, the molten steel fills thecavity 34 between theinsert 78 and the lowerinner surface 46, the upperinner surface 42, and the innerperipheral surface 50. The alumina filter 62 (if present) helps control the velocity of the molten steel being poured into thecavity 34, and inhibits the molten steel from deforming or crushing theinsert 78 before the steel has cooled. - At
Step 216, the molten steel can be cooled using known techniques (e.g., waiting a period of time). - After the steel has cooled, the steel foam component 140 can then be removed from the
mold 14, atStep 220. At this stage, theinsert 78, which may be a 3D-printedsand insert 78, has broken down into a powder or other flowable form. The powder still remains within the steel foam component 140. As such, theinsert 78 is removed from themold 14 with the steel foam component 140. - At
Step 224, the powder remains of theinsert 78 are decored (i.e., removed) from the steel foam component 140. In some embodiments, the powder remains may exit the steel foam component 140 through the openings 178 by, for example, shaking the component 140. In other embodiments, a new hole may be drilled or cut into the steel foam component 140 to facilitate removal of the powder from the component 140, such as when the steel foam component is provided with no exterior holes through which the powder can exit, or whether an insufficient number of such holes exist. Once theinsert 78 is removed from the component 140, the plurality of pores 174 are exposed (i.e., left as empty voids within the steel foam component 140). Further, the steel foam component 140 may be processed to remove excess parts from the steel foam component 140 that are byproducts of the casting process. For example, the pour opening 38 may have retained cooled steel that remains attached to the desired component. This excess cooled steel can be cut off of the component 140 using known techniques. - At
Step 228, the steel foam component 140 may be treated to achieve desired physical properties. For example, the component 140 may be heated treated to a desired hardness (e.g., between 100 BHN and 400 BHN). Additionally, the component may be welded by conventional welding techniques to other steel foam components 140 to form a desired structure. The steel foam components 140 are also machinable by common metalworking techniques. The resulting steel foam components 140 can comprise plain carbon and low alloy steels of matrix strengths varying, for example, from 50 ksi to 150 ksi. - Although the steel foam components shown in
FIGS. 5-7 are rectangular prisms, other shapes are possible. For example, steel foam components that are cylindrical, spherical, or that have other geometric and non-geometric shapes are also contemplated. Further, the steel foam components may be formed as combinations of geometric shapes, or may include any combination of geometric and non-geometric shapes. The inserts and molds in such instances would be altered accordingly to create the desired shapes and densities of the steel foam components. - The above techniques allow for the creation of steel foam components with ballistic resistant applications for military structures (e.g., ballistic plates), civilian structures (e.g., buildings and bridges), naval applications, and the like. The steel foam components also have applications in energy absorption and blast resistance. The steel foam components also have controllable and uniform densities. Steel foam components manufactured according to the processes described herein can be produced relatively inexpensively and on an industrial scale. Compared to aluminum foams, steel foams have higher specific stiffness, higher hardness, and higher strength. Structural advantages of steel foam compared to solid steel include minimization of weight, maximization of flexural strength, increased energy dissipation, and increased mechanical damping. Further applications for steel foam components include, among other things, pistons and propellers. In particular, in a vehicle equipped with a steel foam component for crash protection, the steel foam component decelerates over a longer distance and a longer period of time, thereby limiting changes in speed experienced by vehicle occupants. Further, non-structural benefits of the steel foam components include lower thermal conductivities, improved acoustic performances, allowance of air and fluid transport within the steel foam component, and better electromagnetic and radiation shielding properties.
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FIGS. 9 and 10 illustrate anothersteel foam component 140 d that is produced using thesystem 10 ofFIG. 1 and, for example, theinsert 78 a ofFIG. 2 . Thesteel foam component 140 d is similar to thecomponent 140 a described with respect toFIG. 5 . The illustratedcomponent 140 d, however, has a gradient density. That is, thecomponent 140 d includes afirst section 186 d that is solid, followed asecond section 190 d that haspores 174 d. In the illustrated embodiment, the gradient density is realized along the thickness t of the component (i.e., along the axis T). In other embodiments, the gradient density may also or instead be realized along another dimension of the component (e.g., height and/or width along the axes V and H). Any gradient density in any single dimension or any combination of dimensions is possible, and falls within the spirit and scope of the present invention. With continued reference to the embodiment ofFIGS. 9 and 10 , the volume of thesections second section 190 d is greater than the volume of thefirst section 186 d, by way of example only. - In some embodiments, the gradient density may be formed over more than two sections, or layers, of the
component 140 d. For example, thecomponent 140 d may include a first section that is solid, followed by a second section that has pores, followed by a third section having a greater density of pores of the same or different size. In such embodiments, thecomponent 140 d may have solid steel on either or both sides of a porous central section. Alternatively, thecomponent 140 d may include a first section that is solid, followed by a second section that has a plurality of pores occupying a first volume (e.g., 20%) of the section, followed by a third section that has a plurality of pores occupying a second volume (e.g., 40%) of the section, etc. The volume occupied by the pores (and, thereby, the density of the sections) may increase, decrease, alternate, or otherwise vary in any manner along any one or more dimensions of thecomponent 140 d. For example, gradient densities can exist across the thickness of a plate as shown inFIG. 9 , and/or across the width or length of the plate. As other examples, gradient densities can exist in various elements with pores located on one side or end of a plate and pores of different density located across the rest of the plate, pores located in a middle of a plate with pores of different density located on opposite width-wise sides of the plate and/or opposite length-wise ends of the plate, pores located about a periphery of a rectangular or round plate or in a central portion of a rectangular or round plate with the balance of the plate having pores of different density, pores located along a portion (e.g., center or end) of a rod, shaft, strut, or other elongated element and pores of different density along the rest of such a member, pores located proximate an external surface of a rod, shaft, strut, or other elongated element and with pores of different density located further in the interior of such a member (or vice versa), and the like. Alternatively, steel foam components with selective variable densities could have a first pattern of pores formed in a first section to form a first density, and a second pattern of pores formed in a second section to form a second density that is different than the first density. Selective variable densities could also be formed in three or more distinct sections of a steel foam component. - Steel foam components having gradient densities are usable as, among other things, armor plating in military vehicles. For example, the steel foam components can be made in accordance with military spec MIL-PRF-32269 for perforated homogeneous steel armor. By way of example, a solid steel plate of 12 inches by 12 inches by 1 inch may have a weight of 40 pounds and a pounds per square foot (PSF) value of 40. In contrast, by providing a gradient density, the
steel foam component 140 d illustrated inFIGS. 9-10 has a PSF value of 28. Other PSF values are also achievable by varying the gradient density of thecomponent 140 d, depending on the desired application and performance characteristics for thecomponent 140 d. - In further embodiments, steel foam components may be manufactured with selective variable densities. That is, the components may have pores only in certain, predetermined sections of the components, and the remainder of the components may be solid steel. For example, selective variable densities can exist in various elements with pores located on one side or end of a plate with no pores located across the rest of the plate, pores located in a middle of a plate with no pores located on opposite width-wise sides of the plate and/or opposite length-wise ends of the plate, pores located about a periphery of a rectangular or round plate or in a central portion of a rectangular or round plate with no pores in the balance of the plate, pores located along a portion (e.g., center or end) of a rod, shaft, strut, or other elongated element and no pores along the rest of such a member, pores located proximate an external surface of a rod, shaft, strut, or other elongated element and no pores of different density located further in the interior of such a member (or vice versa), and the like.
- In some embodiments, a component with distinct “parts” could have one “part” that is porous and another “part” that is solid steel. For example, a piston typically includes a crown portion (i.e., a first “part”) and a skirt portion (i.e., a second “part”). If the piston was formed as a selectively variable steel foam component, the crown portion could have pores, while the skirt portion could be solid steel. Other multi-“part” components are also possible (e.g., a propeller with porous blades and a solid steel hub).
- Steel foam produced in accordance with the present invention is usable in manners similar to standard (i.e., non-foamed) steel. For example, steel foam components are weldable using conventional welding techniques. In addition, steel foam is machinable using conventional machine tools.
- Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention.
- Various features and advantages of the invention are set forth in the following claims.
Claims (14)
1. A steel foam component comprising:
a steel body having a plurality of pores, the plurality of pores forming a generally uniform pattern throughout the body and occupying at least 20 percent of a volume of the body.
2. The steel foam component of claim 1 , wherein each of the plurality of pores has a similar geometric shape.
3. The steel foam component of claim 1 , wherein each of the plurality of pores is in fluid communication with at least one other pore of the plurality of pores.
4. The steel foam component of claim 1 , wherein the plurality of pores occupies between about 20 percent and about 60 percent of the volume of the body.
5. The steel foam component of claim 1 , wherein the plurality of pores occupies between about 40 percent and about 60 percent of the volume of the body.
6. The steel foam component of claim 1 , wherein the body includes a first face and a second face spaced apart from the first face, and wherein the first face and the second face are continuous steel.
7. The steel foam component of claim 6 , wherein the body also includes a peripheral edge extending between the first face and the second face, and wherein at least one of the plurality of pores communicates through the peripheral edge.
8. The steel foam component of claim 6 , wherein the first face and the second face are square in shape.
9. The steel foam component of claim 1 , wherein the plurality of pores is arranged in a series of rows and a series of columns within the body.
10. The steel foam component of claim 9 , wherein the series of rows is arranged parallel to a first axis and the series of columns is arranged parallel to a vertical axis, the second axis being perpendicular to the first axis.
11. The steel foam component of claim 9 , wherein the plurality of pores is further arranged in pore layers along a third axis, the third axis being perpendicular to the first axis and the second axis.
12. The steel foam component of claim 1 , wherein each of the plurality of pores is spherical in shape.
13. The steel foam component of claim 1 , wherein each of the plurality of pores is an empty void.
14. The steel foam component of claim 1 , wherein the steel body is in the shape of a rectangular prism.
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US16/700,338 US20200101528A1 (en) | 2014-12-19 | 2019-12-02 | Steel foam and method for manufacturing steel foam |
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US14/576,367 US9623480B2 (en) | 2014-12-19 | 2014-12-19 | Steel foam and method for manufacturing steel foam |
US201562121620P | 2015-02-27 | 2015-02-27 | |
PCT/US2015/066253 WO2016100598A1 (en) | 2014-12-19 | 2015-12-17 | Steel foam and method for manufacturing steel foam |
US15/532,746 US10493522B2 (en) | 2014-12-19 | 2015-12-17 | Steel foam and method for manufacturing steel foam |
US16/700,338 US20200101528A1 (en) | 2014-12-19 | 2019-12-02 | Steel foam and method for manufacturing steel foam |
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PCT/US2015/066253 Division WO2016100598A1 (en) | 2014-12-19 | 2015-12-17 | Steel foam and method for manufacturing steel foam |
US15/532,746 Division US10493522B2 (en) | 2014-12-19 | 2015-12-17 | Steel foam and method for manufacturing steel foam |
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US20170361375A1 (en) | 2017-12-21 |
US10493522B2 (en) | 2019-12-03 |
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