Source: http://www.google.com/patents/US7172714?dq=6519629
Timestamp: 2014-10-31 20:45:29
Document Index: 768213046

Matched Legal Cases: ['Application No. 60', 'art 45', 'art 45', 'art 45', 'art 45', 'art 45', 'art 305', 'art 332']

Patent US7172714 - Use of state-change materials in reformable shapes, templates or tooling - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsTechniques for generating a stable, force-resisting positive or negative representation of a shape. A state-changeable mixture includes uniform, generally ordered, closely-spaced solid bodies and a liquid carrier medium, with the liquid filling any voids or interstices between the bodies and excluding...http://www.google.com/patents/US7172714?utm_source=gb-gplus-sharePatent US7172714 - Use of state-change materials in reformable shapes, templates or toolingAdvanced Patent SearchPublication numberUS7172714 B2Publication typeGrantApplication numberUS 10/824,333Publication dateFeb 6, 2007Filing dateApr 13, 2004Priority dateJan 11, 1999Fee statusPaidAlso published asUS7402265, US20050035477, US20070187855Publication number10824333, 824333, US 7172714 B2, US 7172714B2, US-B2-7172714, US7172714 B2, US7172714B2InventorsTheodore L. JacobsonOriginal Assignee2Phase Technologies, Inc.Export CitationBiBTeX, EndNote, RefManPatent Citations (27), Referenced by (2), Classifications (11), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetUse of state-change materials in reformable shapes, templates or toolingUS 7172714 B2Abstract Techniques for generating a stable, force-resisting positive or negative representation of a shape. A state-changeable mixture includes uniform, generally ordered, closely-spaced solid bodies and a liquid carrier medium, with the liquid filling any voids or interstices between the bodies and excluding air or gas bubbles from the mixture. Within the mixture, the solid bodies can be caused to transition from a near-liquid or fluent condition of mobility to a stable, force-resisting condition. To create mobility, a small excess quantity or transition liquid is introduced to create a fluent condition by providing a slight clearance between the bodies which permits the gently-forced introduction of at least two simultaneous slip planes between ordered bulk masses of the bodies at any point in the mixture. Transition to the stable condition is caused by extraction of the transition liquid, removing the clearance between bodies and causing them to make stable, consolidated contact.
providing a plurality of solid bodies;
surrounding the plurality of solid bodies with a volume of carrier liquid, the volume of carrier liquid being sufficient to coat the bodies and fill interstices between the bodies;
removing at least some of the carrier liquid that occupies the interstices so that the bodies become substantially close-packed solid bodies having a coating of the carrier liquid thereon, the coating being sufficiently thin that the bodies have interstices therebetween devoid of liquid, the coating being a state-changeable coating having an adhesive state and a non-adhesive state; and
causing the state-change coating to change from the non-adhesive state to the adhesive state so as to result in a solidified porous volume.
2. The method of claim 1 wherein the solid bodies are hollow.
3. The method of claim 1 wherein the bodies are of substantially the same density throughout their respective volumes.
the carrier liquid includes a solvent and an adhesive material, the solvent being sufficient such that the adhesive material does not exhibit its adhesive property; and
causing the state-change coating to change from the non-adhesive state to the adhesive state includes removing a sufficient amount of solvent so that adhesive material left on the surface of the solid bodies defines the state-change coating and exhibits its adhesive property.
the carrier liquid is a material above its melting temperature; and
causing the state-change coating to change from the non-adhesive state to the adhesive state includes lowering the temperature of the material below its melting temperature.
6. The method of claim 5 wherein the material is a eutectic alloy.
7. The method of claim 5 wherein the material is a paraffin.
8. A fabrication method comprising:
providing a plurality of substantially close-packed solid bodies, the bodies having a state-changeable non-metallic coating, the state-changeable coating having an adhesive state and a non-adhesive state, the state-changeable coating being sufficiently thin that the substantially closed-packed bodies have interstices therebetween; and
9. The method of claim 8 wherein the solid bodies are hollow.
10. The method of claim 8 wherein the bodies are of substantially the same density throughout their respective volumes.
11. The method of claim 8 wherein said providing the bodies comprises:
surrounding the plurality of solid bodies with a volume of carrier liquid, the volume of carrier liquid being sufficient to coat the bodies and fill the interstices between the bodies; and
removing at least some of the carrier liquid that occupies the interstices to leave the coating on the bodies with the interstices devoid of liquid.
14. The method of claim 13 wherein the material is a paraffin.
15. A fabrication method comprising:
providing a plurality of substantially close-packed solid bodies, the bodies having a state-changeable non-metallic coating, the state-changeable coating having an adhesive state and a non-adhesive state, the state-changeable coating being sufficiently thin that the substantially closed-packed bodies have interstices therebetween;
causing the state-change coating to change from the non-adhesive state to the adhesive state so as to result in a solidified porous volume; and
thereafter, causing at least a portion of the state-change coating to change from the adhesive state to the non-adhesive state so as to allow at least a portion of the solid bodies to provide a volume in a formable state.
16. The method of claim 15 wherein the solid bodies are hollow.
17. The method of claim 15 wherein the bodies are of substantially the same density throughout their respective volumes.
18. The method of claim 15 wherein said providing the bodies comprises:
CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation of U.S. patent application Ser. No. 10/150,747, filed May 17, 2002, now U.S. Pat. No. 6,780,352, issued Aug. 24, 2004, which is a continuation-in-part of U.S. patent application Ser. No. 09/478,956, filed Jan. 7, 2000, titled �The use of State-Change Materials in Reformable Shapes, Templates or Tooling,� now U.S. Pat. No. 6,398,992, issued Jun. 4, 2002, which claims priority from U.S. Patent Application No. 60/115,472, filed Jan. 11, 1999, titled �Generation of Stable Near-Net Shapes from Confined, Mobile, Lockable Particle Masses (The use of State-Change Mediums in Reformable Shapes, Templates or Tooling),� the entire disclosures of which (including all attached documents) are incorporated by reference in its entirety for all purposes.
BACKGROUND OF THE INVENTION The present invention relates generally to reformable materials, and more specifically to mixtures, primarily solid/liquid mixtures, that can be formed into desired shapes and then re-used to form other desired shapes. The desired shapes may be end products, or may be templates or tools used to form end products or other templates or tools.
U.S. Pat. No. 2,517,902 (Luebkeman); U.S. Pat. No. 3,962,395 (H�gglund); U.S. Pat. No. 4,931,241 (Freitag); U.S. Pat. No. 5,198,167 (Ohta et al.); U.S. Pat. No. 5,262,121 (Goodno); U.S. Pat. No. 5,348,070 (Fischer et al.); U.S. Pat. No. 5,374,388 (Frailey); U.S. Pat. No. 5,928,597 (Van Ert et al.); U.S. Pat. No. 5,957,189 (Uzaki et al.); U.S. Pat. No. 5,971,742 (McCollum); and U.S. Pat. No. 6,224,808 (Essinger et al.). The following U.S. patents relate to formable objects of use:
U.S. Pat. No. 3,608,961 (Von Heck); U.S. Pat. No. 4,327,046 (Davis et al.); U.S. Pat. No. 4,885,811 (Hayes); U.S. Pat. No. 4,952,190 (Tarnoff et al.); U.S. Pat. No. 5,093,138 (Drew et al.); U.S. Pat. No. 5,556,169 (Parrish et al.); U.S. Pat. No. 5,881,409 (Pearce); and U.S. Pat. No. 5,966,763 (Thomas et al.). SUMMARY OF THE INVENTION In brief, the present invention provides a reversible state-changeable mixture comprising a plurality of solid bodies and a carrier medium, with the carrier medium filling any voids or interstices between the bodies. Within the mixture, the solid bodies can be caused to transition from a formable state, preferably a near-liquid or fluent condition of mobility, to a stable, force-resisting condition through introduction and then extraction of a slight excess quantity of the carrier medium beyond that required to fill the interstices of the bodies when closely packed. In most embodiments, the carrier medium is a liquid preferably excluding any air or other gases from the mixture, and most of the discussion will revolve around such embodiments. However, some embodiments use a carrier medium that is a liquid-gas froth.
The mixture can be rapidly shifted from a formable (preferably near-liquid or fluent) state to a stable force-resisting state and back again to the formable state, through slightly altering the carrier-solid proportions of the mixture, and the invention further provides methods and apparatus for using the mixture. Embodiments are characterized by one or more of the following advantages: the ability to pressurize a mixture and drive it against a complex surface as if it were a liquid; the ability to create a �near-net� or extremely accurate representation of a shape due to the negligible volumetric change that accompanies a state change; the ability to effect the state-change with a very small volume of single-constituent transfer and with consequently small actuation devices without the need for a vacuum pump, without chemical reactions, and with no need for thermal or electrical energy to be applied to the mixture; the ability to greatly alter the volume of any elastic or otherwise dimensionally changeable container, envelope or chamber through the free-flowing transfer of the mixture from one container to another; and the ability to tailor the mixture to satisfy a wide variety of physical specifications in either the flowable or the stable state.
In yet other embodiments, flexible elements containing state-change mixtures are used to capture exterior or interior contours of a shape and to transfer the contours to other state-change elements. Through such �templating� operations a negative of a shape or surface may be produced and then a shape or surface identical to the first may be produced by forming the surface of a mixture against the transfer template. Individual elements might also be used to transfer portions of one shape to another shape and so create variations that combine the contours of two or more shapes into a single shape.
In additional flat envelope embodiments internal and external elements improve their functioning as lightweight tooling and templates. Included are methods to support these mixture-containing envelope structures, both internally with flexible reinforcements and externally with tubular �foot� structures that also contain state-change mixtures. The flat envelopes may also be backed or supported by liquids or dry media as extensively shown in prior art; e.g., U.S. Pat. No. 5,971,742 to McCollum, U.S. Pat. No. 5,374,388 to Frailey, U.S. Pat. No. 3,962,395 to H�gglund, and others. However, the novel properties of the current invention improve significantly on the art by combining the ability to capture precise impressions of a shape with the ability to be switched from a liquid-like state to a firm state, or even to a fully hardened state that resembles concrete yet can be returned to a formable condition.
To reiterate, according to embodiments of the invention, the state change from liquid-like to solid-like properties within the mixtures is effected by the transfer of a small amount of excess carrier medium, the transition liquid, into and out of the mixtures. When the transition liquid is present, preferably in just-sufficient quantity to create the degree of support and clearance that provides for at least two slip-planes, the solid bodies have a degree of mobility similar to that of the liquid medium of the mixture. The slip-plane condition of mobility can be generated through very small liquid pressure differentials or through externally imposed forces that displace the carrier liquid and the supported bodies along with the liquid. Ordered bulk masses of the bodies can shift relative to other ordered masses at any point within a continuous volume of the mixture, and the location of the slip-planes can fluidly shift under any slight differential force transferred from one body to another. It is preferred to prevent frictional contact between bodies during such force transfer by having the liquid medium of the mixture furnish a viscous or �streaming� resistance to contact, and also for the medium to furnish a degree of body-surface lubrication so that light body contacts do not create friction between bodies.
BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B show a mixture of packed spherical bodies, surrounded by a liquid medium in a container with a piston lid, and further show ordered masses of the bodies undergoing shear or slip-plane movement by addition of a small excess of the medium;
FIGS. 3A�3D show mixture bodies of varying geometries;
FIGS. 5A�5C show elastic-membrane inserts being collapsed and then expanded inside a hollow shape by filling them with a state-change mixture;
FIGS. 7A�7D show state-change mixtures that are not transferred, and shows them in thin envelopes that are pushed against shapes by fluid pressure and an array of sliding pins, and further shows the tips of an array of pins with small volumes of mixture in separate envelopes, and also shows the mixture in a chamber with expandable fluid-filled elements within the mixture volume;
FIGS. 8A�8D show voids within sculptable, quasi-stabilized volumes of state-change mixtures, and shows impression-forming of the mixture by pushing a shape or tool against a surface membrane and driving solid bodies into the voids, and also show displacement-forming of the mixture by pushing bodies along the surface;
DESCRIPTION OF SPECIFIC EMBODIMENTS Behavior of State-Change Mixture Comprising Solid Bodies and a Liquid Medium (FIGS. 1A and 1B)
These flow characteristics can be improved by adding a small quantity (generally less than 1% by volume), of a soluble long-chain polymer to the liquid medium. While the polymer somewhat increases the viscosity of the medium, a valuable benefit is that it aids in �streaming� the bodies past one another without friction-generating contact, with the suspended molecular chains acting as a zero-friction cushioning medium. This cushioning property is believed to facilitate non-contact momentum transfers from body to body, and the close-spacing of bodies in conjunction with this momentum transfer assures that slip-planes can form simultaneously and freely at any point within a mixture that has enough transition liquid added to form at least two slip-planes.
FIG. 2A shows the elements of a system using the materials and principles of FIGS. 1A and 1B to achieve a practical result. An open container 38 has elastic envelope 32 filled with mobile state-change mixture 35 and this envelope has a port 40 communicating with a mixture transfer manifold 42. The elastic envelope could be replaced by a membrane that is sealed across the opening of container 38, as long as the container is completely sealed except for its connection to manifold 42. Transition liquid chamber 12 is attached to the manifold rather than container 38, and the mixture is free to flow through the manifold. When an impression-making pattern part 45 is impressed into the free surface of envelope 32, a volume of the mixture equal to the volume of the pattern is displaced and flows out of the chamber-constrained envelope. Piston 14 is then drawn upward to extract transition liquid 10, causing all solid bodies of the mixture to make consolidated, ordered contact. If the extraction force of piston 14 is increased beyond the low level necessary to remove the excess, then a �negative� pressure relative to ambient atmospheric pressure will be created within the mixture if it is contained in a sealed envelope and manifold. Depending on the properties of the mixture, consolidation under atmospheric pressure may or may not be necessary to achieve desired levels of consolidated resistance to externally imposed forces.
The enlargement of FIG. 2A shows some of the limitations and constraints on the accuracy of an impression created with these solid-body/liquid mixtures and a confining membrane that is pushed against the bodies by exterior forces such as ambient atmospheric pressure. The dashed line shows the profile that, ideally, membrane 32 would assume. In fact the membrane tends to follow the contours of the surface bodies; however, it can be appreciated that there is a relationship between the membrane thickness and the size of underlying solid bodies that determines the surface �smoothness.� From testing it has been determined that the surface is essentially smooth if the solid bodies have a maximum dimension of no more � the thickness of an elastomeric membrane made of latex rubber, silicone, or urethane. Apparently the compression of the membranes at regions of inward indentation (into the surface gaps between contacting bodies) thickens these regions. Also, perhaps there is a tendency, through isotropic distribution of forces in an elastic membrane, for the outer surface to be flat despite small ripples or indentations on the opposing surface. As will be shown in FIGS. 3F and 3G, other �smoothing� solutions can be applied with mixture variations and combinations.
FIG. 2B shows a third, generally unrecognized consolidation force that can be applied by the liquid medium. Container 38, along with the mixture contained behind a membrane, is now located within a vacuum chamber 44 that has been evacuated. Liquid medium 9 along with the quantity of transition liquid 10 has no dissolved gases, an extremely low vapor pressure at ambient temperature, and the capability to �wet� the surfaces of the bodies and the membrane. In addition to the commonly understood action of consolidating particulate or granular fill through evacuating air from the containing sealed envelope, there is an additional consolidation force that can be imposed on bodies within the container through using the tensile strength of the liquid medium. This can be done by direct liquid extraction, as with a piston and cylinder, or by indirect methods such as a vacuum within a connected liquid reservoir. This tensile property is rated in terms of atmospheres of negative pressure, and while theoretical tensile strengths of common liquids range from 200 to 1,000 negative atmospheres (roughly −3,000 to −15,000 psi), more easily achieved laboratory results are in the range of 20�30 negative atmospheres (−300 to −350 psi). Assuming that the problems of adsorbed gases on the bodies or liquid-contained gases can be handled in practical devices (easily overcome in laboratory samples), it can be appreciated that consolidation forces far in excess of that achievable by air evacuation (limited to 14.7 psi) can be achieved by direct liquid extraction. Essentially, the solid bodies of the invention would be forced against one another as if tensile strands were attached to each body and to the membrane and all strands were pulled at once through manifold 42, thereby driving membrane 32 against the bodies and the bodies against the container surfaces. Therefore, consolidation would take place even if a vacuum existed on the outer face of the flexible membrane.
FIG. 3A shows a state-change mixture in which the solid bodies are geometrically regular flakes with rounded edges, and the bodies are aligned and generally held parallel to one another due to limited clearance and due to having a dual-density, self-orienting property. For instance the bodies might be formed from a laminate in which the top half 50 is of lower density than the liquid carrier medium, and the bottom half 52 is of higher density, with the combination having a similar density to the medium. With a small quantity of excess liquid (the transition liquid quantity) that perhaps furnishes no more than a few molecular layers between each body, the bodies will be supported and easily moved with respect to one another by liquid flow as previously described. The edges of the bodies might be rounded, as by a tumbling and polishing operation, to facilitate this liquid-supported motion without having sharp or flat edges collide and stick to one another. The medium might also incorporate a �cushioning� or lubricative material such as the soluble polymers previously described.
FIG. 3B shows another type of mixture, with the bodies 55 being closely spaced short fibers. Since the fibers have a density matching that of the liquid carrier medium, they tend to flow with the medium when it is displaced, yet do not rotate or disorient due to the close spacing and �streaming� characteristics of the carrier medium, such as are furnished by dissolved long-chain polymer solutions. In this figure the displacement is caused by linear stretching 60 of a thin membrane envelope 58 containing the mixture. With a constant-volume containment, this stretching causes a thinning 68 of the state-change mixture. It is contemplated that the fiber-like bodies would tend to move freely due to being partially aligned with the direction of flow, yet remain in a generally uniform and ordered structure. When the fiber bodies are forced together by extracting the transition liquid and causing ambient pressure to drive the membranes against them, a stable continuous mat is formed.
The stabilized mat thus formed will tend to resist extension or compression in the plane of the mat if the fiber-bodies' surfaces have a significant coefficient of friction. If thin, the mat thus formed would tend to be flexible and springy if the fibers were likewise springy. The fibers as shown also have a wavy or smoothly crimped geometry that would tend to make them more resistant to slipping when the mat is flexed, and adherence of the membrane to the surface layers of fibers would also aid in maintain dimensional stability despite flexing. It is envisioned that, among other uses, a fiber filled mixture in such a thin envelope could be used as a stretchable �pattern� for taking custom clothing dimensions. For instance filled envelopes might be incorporated into a spandex-like garment that is slipped on while the contained mixture is in the mobile state, and is then stabilized by extracting the transition liquid. The pattern garment might have multiple zippers or other separable means of joining so that it could be removed without putting excessive force on the consolidated mat structure within each envelope.
FIG. 3D shows hexagonal rod elements 66 with rounded ends 69. These would again be ordered and closely spaced in the mixture, and would furnish a high degree of packing and surface contact. A consolidated mass of such rod-like bodies would tend to have a directional beam strength aligned with the long axis, and strength would be a function of the length of the rods which would affect the number of discontinuities in a consolidated mass. Applications might include but not be limited to structures that resist �breaking� or crumpling along one axis under impacts or imposed forces, yet deform or progressively crumple along another axis of stress.
Other types of solid bodies might be used without departing from the spirit of the invention. For instance, besides spheres, flakes, regular polyhedrons, rods and the like, shapes with protuberances or hollows could be used. Some of these bodies might even mate together under consolidating force and require extensive pummeling or rolling forces to be again separated. Likewise flakes might be wavy, have various perimeter shapes etc. There might also be an extensive variety of surface properties, such as low-friction surfaces that will permit slip-displacement even when the bodies are forced together, or high-friction �waffle� surfaces that completely resist slip-displacement when consolidated together. The surfaces might even have suction-creating surfaces or other means for causing the bodies to cling together mechanically so that the consolidated state-change mixture has considerable resistance to tensile as well as compressive forces. Similarly the medium might have specific switchable properties, for instance performing as a lubricant or, under desired force, electrical, chemical or temperature conditions, acting as an adhesive that binds the bodies when they are consolidated against each other. Finally, as will be further described in reference to FIGS. 10A and 10B, the carrier medium might itself be a material with a reversible state-change, such as a paraffin or a eutectic alloy that melts and solidifies within a useful temperature range.
The invention's method for providing near-liquid mobility, and either following or preceding that condition with a stable force-resisting state, may be further understood by considering the elementary model of FIG. 3E. The solid bodies 8 are shown free of containment and all forces other than liquid-medium surface tension at contacting regions. To reach the condition shown, first the transition liquid is extracted, and then further extraction reduces the liquid between particles to separate surface-tension �membranes� 71 that connect each body. Surface tension would cause the remaining fluid to force the already generally ordered solid bodies into stable, ordered, consolidated contact. Conceivably bodies with regions of mating contact, and with interstices remaining open to liquid flow between the bodies after contact, could have sufficient liquid removed that surface tension forces alone would push smooth mating surfaces into adhesion-generating contact. The polyhedrons and rods of FIGS. 3C and 3D might have small grooves or rounded edges to facilitate liquid medium extraction, which might be facilitated by driving the liquid out with air or another gas. Driven by surface tension and by electromagnetic forces between extremely smooth surfaces, any remaining liquid might be driven out, allowing relatively strong surface adhesion forces to develop. With the liquid medium reintroduced between the bodies, surface tension forces would cease to operate and polar molecules of the medium would again wet the bodies and wedge the mating surfaces apart.
It can be appreciated that this body-to-body adhesion, which is a prerequisite with many body types for developing tensile strength within the particle mass, can be furnished in numerous ways. For instance a solvatable adhesive can be used, in which case the liquid carrier medium may be a mixture of the adhesive and solvent. After consolidation, the liquid medium is drained or driven out of voids between bodies and the solvent is driven off by heating or dry air, leaving each body bonded to its neighbors. When the medium is reintroduced, the adhesive bonds between the bodies are dissolved and mobility via the transition liquid may again be used. While the solvent-adhesive mixture might leave elastic bonds, a sodium silicate or �water glass� carrying medium could be used to create a rigidly bonded particle mass. Additional thermally switched adhesive media can also be imagined, such as thermoplastics with a low melt viscosity, waxes, water-based formulation or even water alone.
The third element from the left is an impression-capturing container 97 with a holding cap or lid 105 that can secure a pattern part 45 in a desired position and orientation. The lid itself may also comprise a container holding a state-change mixture behind a membrane, perhaps with a tack-release adhesive on the outer surface to hold the part against the lid membrane. The lid could also be connected to manifold 42, perhaps through a flexible manifold line. The container is shown after part 45 has been pushed into the lower-container membrane. When the bodies are locked in place as described with reference to FIG. 2, a �female� tool 108, in the form of a negative impression of the part, has been created.
The fourth element of the system is a similar impression-capturing container 100 with lid 105. The lid holds a part 45 that has a cavity, and the state-change mixture has been pumped from the transfer chamber to push the membrane into the cavity. When the bodies of the mixture are locked in place by extracting the medium with the two-way pump as previously described, a �male� tool 102 has been created that protrudes above the lower container.
It can be appreciated that either container, with the form-creating shape (part 45) removed, can be used as a mold or die to produce a replica of the shape. For instance a curing liquid polymer can be injected into the left-most container, or a soft, deformable material �blank� can be formed in the right-most container by operating it as a pair of matched dies, through the actions of lifting the lid, placing the blank over the male tool, and then pressing the lid down against the blank.
Such packing could also be facilitated by using floating bodies of lower density than the liquid carrier medium. The bodies would then tend to self-pack, due to their buoyancy, against an upper or lower surface. The surfaces of the bodies would have to have very little contact friction or tendency to adhere together under light contact forces; otherwise there would not only be resistance to the bodies' filling-in of any voids or slip-planes. There might also be the well-recognized problems of settling and sticking together as occurs with many particle suspensions, especially when there is a density mismatch between the solids and the suspending liquids. As previously described, having a transition liquid quantity, and having either matching densities or �cushioning� non-contact properties in the liquid medium can eliminate such friction and adhesion problems between bodies as long as the body surfaces themselves are not prone to stick together either with our without full immersion in a liquid carrier medium.
Insert or Template Applications (FIGS. 5A�5E)
The formed and stabilized template elements 115 are then placed back in hollow shape 110 along with the non-filled elements. The non-filled elements are filled and solidified, the first set of solidified elements are now emptied of the state-change mixture and removed, and the now-solidified elements can again have their contours preserved in a transfer mold 121. It can be appreciated that, by this iterative process, the entire volume and any contours of the hollow shape's interior can be templated, and at the end of the process a complete �male� tool replica of the interior will be created from the membrane elements.
Grouped Membrane Elements to Replicate Highly Contoured Shapes (FIGS. 6A�6B)
Groups of membrane elements have another valuable property besides the iterative shape-capture abilities described with reference to FIGS. 5A�5E. Since elastic, extensible membranes have a finite limit in terms of their degrees of stretch, replicating shapes with a great deal of variation might require limiting the degree of stretch of any one element by sharing the elongation amongst two or more membrane elements or envelopes. FIG. 6A shows a triplet of balloon-like elements 125, while FIG. 6B shows the elements inside a common container 128. The surfaces of the membranes are lubricated or otherwise free to slip past one another in addition to being freely mobile over bodies of the state-change mixture within, as shown at region 130 in the 6B enlargement.
As a complex and highly contoured shape is pushed into the membrane envelopes, the surfaces of the membranes stretch. Due to the mobility of the membranes this stretch is not localized, i.e., limited to the portions of the surfaces in contact with the shape, but rather distributed along each membrane. In other words the sides, and perhaps even the bottom of each envelope, contribute to the stretch of the membrane portions in contact with the shape. In effect the �free surface of stretch� encompasses much of the membrane envelope instead of being limited to the top surface.
State-Change Mixture in Constant-Volume Elastic Envelopes (FIGS. 7A�7C)
This embodiment might also use a second state-change medium in underlying envelope 137, with the mixture contained by having the upper envelope 135 sealed to the open top of the container. If envelope 135 held a heavy state-change mixture as will be described with reference to FIG. 10A, then it might be desirable to give the mixture a stable �bed� of a much lighter state-change mixture. It is contemplated that such an embodiment might be used in which a very hard and durable reformable tool would be prepared in the upper envelope and then used for molding or stamping operations for which such stable backing is necessary.
The pins can have a variety of other forms. The pin itself might comprise an envelope that contains a state-change mixture, so that even more shape-assuming versatility is possible. For instance the envelope-pins would be able to expand sideways into deep or long undercuts in a shape, or they might be used inside a hollow body as shown in FIGS. 5A�5E, and likewise be iteratively filled and stabilized with the dimensions transferred to other pin arrays or transfer molds for �storing� impressions of the shape. The envelope-pins might also have a smaller stiff pin or one or more flexible �spine� pins within the envelopes that could be selectively placed or withdrawn to further facilitate shape-capturing or stabilization of solidified pin elements. The pins could also contain fillable voids as will be shown in the following FIG. 7D and FIGS. 8A�8D.
Impression-Molded Mixture with Voids (FIGS. 8A�8D)
FIG. 8A shows a volume of state-change mixture 160 that can be molded into a desired shape by taking advantage of �quasi-stable� properties that are achieved by allowing ambient pressure to consolidate the bodies, yet making provision for displacing the bodies. An array of flexible, thin-walled tubes 163 permeate the volume of the mixture, and when the array is pressurized with a fluid 166 (liquid or gas) and then drained, a void structure is created within the volume of bodies. The volume with voids is stable, since ambient pressure also acts within the drained tubes to push against the surrounding bodies with the same force as imposed on the membrane.
FIG. 8C shows another type of void structure. This is created by a three-dimensional array of hollow, collapsible nodes 170, much like tiny balloons, which are interconnected by flow tubes 173. The void structure resides inside a volume of state-change mixture in the same manner as the tube structure in FIGS. 8A and 8B, and is likewise filled with a fluid, drained, and then refilled with an incompressible liquid or state-change mixture after the mixture is displaced to the desired shape. It is envisioned that such a regularly-space, many-void structure could fill perhaps 80% of the total mixture chamber volume, and so permit a higher degree of displacement-forming than tube structure 163. This distributed-node structure creates what is in essence a quasi-stable, selectively collapsible �foam� structure, in which the bodies have a large percentage of evenly distributed void-volume into which they can be displaced.
FIG. 8D shows how an indentation or impression 171 could be automatically �sculpted� into a void-filled volume of the state-change mixture. An automated milling machine has a small shaping or sculpting tool 173 mounted in its spindle, which doesn't need to rotate. The sculpting tool is a small ball, and the mill creates the desired shape with two distinct operations. The first operation is a tamping motion, with the tool pushed repeatedly against the surface of the mixture to rough out the shape, thereby leaving a dimpled surface. In the second operation, the ball is moved with a sliding motion along the membrane to smooth out the surface. There is a surface lubricant (not shown) to allow the ball tool to slip freely over the containing membrane without catching.
The thin mixture-containing envelope of FIG. 7B, supported on a pin array could also be sculpted by use of such an automated tool. However, this envelope, as well as the envelope-tipped array of FIG. 7C, might be formed to shape much more quickly than a bulk quantity of the medium as previously discussed. Each pin could be moved separately from the surrounding pins by being pushed vertically by a tool, with the whole array being quickly �punched� into a predetermined position. Following this positioning, the pins would be locked in place and the smoothing motion of the tool applied.
Displacement Sculpting (FIGS. 9A�9B)
FIG. 9A shows another type of automated shaping tool 174, while FIG. 9B shows a progressive displacement-sculpting method. The shaping tool is of a �profilometer� type, in which a smooth contact element is automatically configured through a sequence of curves as it moves over the sculptable surface. The tool is used to progressively and sequentially displace the state-change mixture as shown at 180 a�e, with an enveloping membrane being held against the surface bodies by pressure differential as previously described. The tool moves a layer of bodies along the surface of the underlying bodies, in effect �sweeping� them along beneath the surface of the membrane, which slips freely under the tool and also over the surface of the stationary beads underlying the displaced beads. Through a series of such sweeping movements, a portion of the body mass 176 is displaced to create the desired shape 179. It can also be appreciated that the sweeping tool can be used to impression-mold a state-change mixture with voids, and it is contemplated that both the impression-molding and displacement-sculpting methods would be used together in many forming operations. The profilometer tool could also be used for tamping, and would perform such an operation in addition to the sweeping or smoothing operations, much more quickly than could the single ball tool of FIG. 8D. Such a profiling device could also be used with the envelopes and pin arrays of FIGS. 7B and 7C, as well as with the non-membrane system to be described with reference to FIG. 10B.
Further Mold and Tool Embodiments (FIGS. 10�16)
FIG. 10C shows a technique for adding a surface coating to a shaped and hardened porous mixture without affecting the �net shape� or precise dimensions of the mixture's surface. As an example, with the membrane removed a hardenable liquid epoxy material 190 is brushed or sprayed onto the surface in sufficient quantity to permeate to a predetermined depth. Small openings or uncoated areas are left at the �low� points on the formed surface, i.e., those points that the membrane will contact last as it is pressed by atmospheric pressure due to a vacuum being applied to the porous mixture.
FIG. 10D shows a porous hardened tool, with the surface membrane removed, being used as a �vacuum former.� Clamp 193 is used to form an air tight seal between a formable sheet 196 and the tool's open top. If the sheet is thermoplastic, it can be heated to formability and then forced down against the tool surface by atmospheric pressure as vacuum 198 is applied. Other formable materials or materials combinations, such as a �prepreg� composite sheet material overlaid with an airtight membrane, can also be formed. The surface coating previously described could also be applied to increase the durability or impermeability of the porous tool, with vacuum draw holes being drilled in the surface as is done with conventional thermoforming tools. Likewise the coated shape could be used as a durable nested fixture which holds thin-shell parts for various trim and fabrication operations.
FIG. 11 shows a low-density state-change mixture 200. In this example, hollow beads 203 are carried in a frothed medium 205 comprising small, stable bubbles. As with the earlier-described mixtures, this mixture can flow and be pumped to and from containers through small-diameter tubing or piping, yet still constitute a �mobile solid� that is stabilized by extracting the froth to below ambient pressure. The froth would likely return to a liquid state since the bubbles would expand and rupture when the carrier liquid was suctioned from the mixture container as previously described. However, the froth could be reconstituted from the liquid and pumped into the bodies to regenerate the mobile mixture.
FIG. 12C shows a varied-pressure method for consolidating the coated particles of 12B without relying on a liquid that completely fills the interstices between the mixture bodies. The method can be applied to any mixture in which the residual liquid furnishes a degree of lubricity between the bodies, and the method may also be applied to dry particulate media including powders as long as the lubricity between surfaces permits relative movement between the bodies or particles without �clumping� as described in U.S. Pat. No. 5,556,169 to Parrish et al., and others. However, the liquid-aided lubricity and the adhesive locking of consolidated bodies as described above gives particular advantage to bodies with a light coating of the appropriate liquid.
FIGS. 14A and 14B show a flexible, extensible flat envelope portion 269 containing a state-change mixture. Also shown are additional elements that-contribute to the envelope's functions as a lightweight tool, mold, or template. A flexible reinforcement element 271 is held in a sleeve 273 that is attached at intervals to the interior of the bottom surface of the envelope. These elements may be composed of bundles of flexible glass or carbon fibers, or of any other material that is in an easily extensible form such as the serpentine configuration shown. Arrays of these reinforcements may be arranged in parallel as shown or may cross each other orthogonally or at other angles. These elements can be wetted by the carrier liquid of the mixture and may also be penetrated by bodies of the mixture so that upon consolidation they are held firmly in place within the mixture and the surrounding envelope. Hardening of the mixture by the various methods described will in effect produce a thin-shell reinforced concrete structure.
Also shown are the cross ties 275 and the support and feed tubes 279 that further contribute to the functions of the envelope. The cross ties serve to hold the opposed surfaces of envelope 269 in relation to one another, thereby preventing an uncontrolled separation of the two surfaces. The ties may be positioned at any interval that effectively controls undesired movement of the state-change mixture within. The mixture may also be contained within a flexible, porous fibrous structure (not shown) such as a light, extensible, non-woven piling mat product that is customarily used for insulation, or may be otherwise held by any arrangement of ties, cellular structures or the like that serve the purpose of preventing the mixture from �slumping� or otherwise shifting within the envelope while in the formable state.
FIG. 16 shows a single-face tool configuration using the membrane envelope of FIG. 14. Envelope 269 has been impressed with pattern part 305 and consolidated or hardened. Tubular supports 279 have flexed and conformed to the impressed contour and have been likewise consolidated or hardened. As shown the tool configuration has approximately 15% of the volume of an equivalent �tub� type of tool as shown in FIG. 2A through FIG. 6B. As previously described the configuration could be further supported by filling the open volume around the support tubes with additional fill media including the lightweight state-change mixtures as previously described, or otherwise supported through backing the envelope with liquid as disclosed by McCollum. The use of one type of mixture within the envelope, another type within the support elements and yet another type as a broad support medium would be an extension of the concepts described with reference to FIG. 3. The concept of FIG. 16 further integrates those of FIG. 7 and FIG. 13.
FIG. 17 is a diagram of an existent prototype tool-forming system that has a �single-face� reformable tool 310, in which the solid bodies of the mixture are held rather than being transported into and out of the tool. The liquid medium is held in a storage tank 313 and is delivered into and extracted from tool 310 by a liquid pump 319. A liquid heater 322 is used to heat the liquid, which in some tests has been water with a water-soluble adhesive that has a temperature-dependent viscosity. Heating the liquid reduces its viscosity and so facilitates flow into the interstices of the solid bodies held in the tool. The heat is also used at a later stage to evaporate water from the residual adhesive clinging to the bodies. Additional components of the system will be noted as the system operating procedure is described.
A pattern part 332, mounted on a plate 334, is now placed against the membrane. If the plate is not easily pressed down against the membrane so that its smooth edges rest against the membrane, then the elastic vacuum seal 329 is placed so that it seals the plate against the membrane at the tool's rim. Valve 337 is then opened so that air is withdrawn from between the plate and the membrane, causing the membrane to stretch over and follow the contours of the pattern. Since the mixture is in a mobile condition and has no air bubbles that might position themselves against the membrane, as the membrane is drawn against pattern 332 and plate 334 the contained mixture follows the membrane and so completely follows the contours of the pattern. If there are significant concavities on the pattern then talc or some other �vacuum breaking� substance is put on the pattern or the membrane surface so that air will be removed from the concavities.
The plate and pattern can now be removed, which action is accomplished by turning off vacuum pump 316 and opening up the atmospheric valve 338, thereby breaking the vacuum between the pattern and the surface membrane. The membrane can now serve as a tool face or further tool hardening step can be taken. In tests of the system, one of the liquids used has been water containing a water-soluble adhesive, though the process described can work similarly with any solvent and soluble-adhesive liquid. The vacuum in the liquid tank can be used to create a pressure differential between the tool and the tank. If the liquid entering the tool has been heated above room temperature and the tank is at room temperature, then sufficient vacuum in the tank will cause a vapor boil-off to begin in the tool. This will in turn drive liquid from the tool under vapor pressure, while at the same time �drying� the adhesive that remains on the bodies.
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