Plastic and nonmetallic article shaping or treating: processes – Recycling of reclaimed or purified process material
Reexamination Certificate
2000-01-07
2002-06-04
Elve, M. Alexandra (Department: 1725)
Plastic and nonmetallic article shaping or treating: processes
Recycling of reclaimed or purified process material
C264S108000, C264S220000
Reexamination Certificate
active
06398992
ABSTRACT:
BACKGROUND OF THE INVENTION
The prior art for making molds or tooling deals for the most part with fabricating, machining, layered deposition forming, molding or casting of tools for a single dedicated purpose. While the tools may be modified or the materials recycled, often this is accomplished only with multiple steps and at considerable expense. Specific instances of quickly reformable molds have been found which rely on beads, sand or other particulate materials being blown or poured into a container with at least one flexible or elastically extensible surface. An article is pushed against or surrounded by the flexible surface and the contained particulate material, and then a vacuum is pulled on the container to remove air so that ambient air pressure consolidates the beads or particles and holds the flexible surface against them in the shape of the article. Likewise, numerous instances have been found of cushions, pads or seats which rely on introducing or vacuuming air from a bead-filled, flexible or stretchable sealed envelope, while other instances have been found of reformable shapes comprising flexible envelopes which contain mixtures of beads or microspheres combined with binding yet flowable lubricants or highly viscous materials. Some of these shapes have been made temperature responsive, so that heat would soften them and cooling would harden them.
Mass Production Casting or Molding
U.S. Pat. No. 5,348,070 (Fischer et al.) is titled “Process for the Compression of Molding Sand for Casting Molds,” and discloses a method for closely packing sand into a mold through a process of fluidizing it within the mold by a surge of compressed air through the sand and then compressing it by mechanical pressing. The technique requires a pressure rise and a pressure reduction gradient in the fluidizing process and requires initiating the mechanical pressing operation during the controlled pressure reduction. This multi-step process allows the sand grains to be jostled into any voids which could form as a result of particles being allowed to statically press on one another.
U.S. Pat. No. 5,957,189 (Uzaki et al.) describes an “apparatus and method for sequentially feeding quantities of sand into a mold space and subjecting the space to evacuation and then pressure increase after each feed.” The process differs from Fischer in that layers of sand are placed in the mold and consolidated by evacuation of air followed by rapid pressurization or pulse of compressed air, thus avoiding the need for a mechanical tool to press the sand. As with Fischer the pressure uses a considerable amount of compressed air and also requires a vacuum source.
U.S. Pat. No. 5,971,742 (McCollum) is titled “Apparatus for Molding Composite Articles” and describes liquid-supported thin-shell molds. These rapid molds utilize a thin shell or shaped “membrane” which is stabilized or forced against formable material by a backing liquid. The technique requires a separate forming or fabrication step to create the formed shell or membrane.
U.S. Pat. No. 5,928,597 (Van Ert et al.) is titled “Method for Thermoforming Sheet Articles” and discloses a method of thermoforming shapes from sheet materials which also utilizes thin shells which are forced against the sheet by a pressurized liquid which also cools the sheet. Again, as with McCollum, the technique requires that specific-use shells be formed as the mold faces. In addition it is not clear that there is a mechanism other than the stiffness of the thin formed shells to prevent distortion of the molded shape by the generally non-uniform resistance of a sheet undergoing thermoforming.
Custom Casting or Molding
U.S. Pat. No. 3,962,395 (Hägglund) is titled “Method of Producing Castings or Other Mouldings by Means of Vacuum Suction of Flexible Containers Holding Granular Material.” The technique utilizes granular material poured into a container to push against a flexible “wall” of the container comprising an elastic sheet or formed plastic film, which in turn is forced against a shape such as the stump of an amputee's limb. Air is then evacuated or partially evacuated “to cause the granules to form a solid, persistent mass conforming to the shape of the model” which is then removed from contact with the stabilized surface. Hägglund, while interested in a certain degree of accurate conformity to the model, is not concerned, as are Fischer and Uzaki, with a high degree of consolidation of the particulate material without voids.
U.S. Pat. No. 4,327,046 (Davis et al.) is titled “Method for Producing a Rigid, Shaped Mass Support System” and describes a flexible container (envelope) of elastic film filled with a mixture of rigid particles and a curable adhesive binder material. The envelope is molded to fit a contour such as a particular portion of a person's body, and then the envelope is “evacuated to remove volatiles and fix the shape of the contents of the container,” following which the binder is cured to solidify the mixture. Then “the polymeric film can be stripped away, after which an adhesive paint is applied to seal and protect the surface.” Again as with Hägglund, the object is not to furnish precise, complex-shape conformability, but rather to follow relatively gentle contours. Also the process again requires a vacuum source to stabilize the molded form.
Reformable Objects—Seats, Toys, Cushions, Protective Pads etc
U.S. Pat. No. 3,608,961 (Von Heck) is titled “Variable Contour Cushion” and discloses the application of vacuum to press together and stabilize an air-tight envelope partially filled with bead-like materials. There is no attempt to create a precise fit to complex contours or to minimize the quantity of fluid that is introduced and removed from the envelope.
U.S. Pat. No. 4,885,811 (Hayes) is titled “Protecting Bodies During Transit” and shows a restraint consisting of soft, flexible bubbles encased in an air-tight film envelope. The bubbles are soft, having a Shore A Durometer rating of 10 or less. When air is withdrawn from the envelope the restraint molds to the shape of an object which it surrounds, becoming stable while remaining soft and pliable. Again the transfer of air into and out of an envelope is shown, though with the contained bodies being quite resilient when compressed together by ambient pressure. Likewise, there is no attempt to strive for a precise fit to the surrounded body nor to limit quantity of air in and out of the envelope.
U.S. Pat. No. 4,952,190 (Tarnoff et al.) is titled “Deformable Article” and discloses a novelty toy consisting of a flexible shaped bladder with a sealable filling stem which is filled with a moldable filling medium such as a cohesive mixture of hollow or solid microspheres and water. The intent is to product a light, deformable object which can be thrown or caught at significant speed without damaging the objects it hits or a catcher's hand. There is no intent to control the properties of the mixture beyond furnishing this impact-absorbing deformability.
U.S. Pat. No. 5,093,138 (Drew et al.) shows a flowable, pressure-compensating material which consists of a mixture, composition or medium of spherical bodies in a liquid, though with glycerin or some other additive to increase the viscosity of the composition. It is intended for use in padding devices and is one of several similar media with varying degrees of resistance to flow. There is no provision for varying the flowability or resistance to motion within a single material formulation.
U.S. Pat. No. 5,556,169 (Parrish et al.) is titled “Multi-Layer Conformable Support System” and describes an outer fluid-sealed layer containing beads which are movable relative to one another when a fluid such as air is introduced, and which are inhibited from motion by atmospheric pressure when the fluid is evacuated. A second fluid-sealed layer underlays the first layer, and air is introduced into it, pushing on the first bead-containing layer and molding it against a shape pressed into the first layer. The technique does not transfer the beads or beadl
Kerns Kevin P.
Townsend and Townsend / and Crew LLP
LandOfFree
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