Abstract: A planar heat sink, using heat pipe principals, is constructed by encapsulating a metalized heat fugitive plastic mandrel in a copper electroform bath and removing the plastic mandrel. The heat pipe chamber of the heat sink is constructed with a plurality of cruciform shaped vanes, wicking structures, for improved wetting and to prevent the formation of droplets. The plastic mandrel is injection molded having opposing negative front and back panels containing negative vanes. The core and cavity for the injection mold tool are formed by electroforming a machined aluminum plate which is etched by laser with the vane pattern.

Abstract: An improved method for stereolithographically making an object by alternating the order in which similar sets of vectors are exposed over two or more layers. In another method, a pattern of tightly packed hexagonal tiles are drawn. Each tile is isolated from its neighboring tiles by specifying breaks of unexposed material between the tiles. Using an interrupted scan method, vectors are drawn with periodic breaks along their lengths. In another method, modulator and scanning techniques are used to reduce exposure problems associated with the acceleration and deceleration of the scanning system when jumping between vectors or changing scanning directions. In another method, a capability for automatically inserting vents an drains into a three-dimensional object representation is provided.

Abstract: An improved method for stereolithographically making an object by alternating the order in which similar sets of vectors are exposed over two or more layers. In another method, a pattern of tightly packed hexagonal tiles are drawn. Each tile is isolated from its neighboring tiles by specifying breaks of unexposed material between the tiles. Using an interrupted scan method, vectors are drawn with periodic breaks along their lengths. In another method, modulator and scanning techniques are used to reduce exposure problems associated with the acceleration and deceleration of the scanning system when jumping between vectors or changing scanning directions. In another method, a capability for automatically inserting vents an drains into a three-dimensional object representation is provided.

Abstract: A method is disclosed for making a molded refractory article comprising the steps of providing a mold including a molding pattern, the mold and molding pattern defining a mold cavity; filling the mold cavity around the molding pattern with a mixture comprising refractory particles and a heat fugitive binder; inserting a plurality of elements of relatively high melting point material into the mixture to displace a portion of the mixture; curing the mixture; separating the mold and molding pattern from the cured mixture; and sintering the combination of the cured mixture and mixture displacing elements to provide a reinforced molded refractory article. The mixture displacing elements preferably comprise a plurality of parallel tool steel rods. Also disclosed is an apparatus for molding the aforedescribed reinforced refractory article.

Abstract: Improved apparatus and methods for forming a layer of material over a surface of a previously-formed cross-section of a three-dimensional object in anticipation of forming a next cross-section of the object out of the layer. A volume of material, including at least some excess material, is placed over the surface, and the excess material is swept off by placing the excess material in the predetermined path of a sweeping member, the path being substantially in a plane spaced from a working surface of material. The member may be directed to sweep the excess material away through a successive number of sweeps, which may vary for each cross-section, at least a velocity which may vary for each sweep. Additionally, the clearance between the member and the surface of the previous cross-section may vary for each sweep. A "winged" member is also provided, comprising two legs extending from a base, and a "Trident" embodiment is also provided, comprising three legs extending from a base.

Abstract: An improved method for stereolithographically making an object by alternating the order in which similar sets of vectors are exposed over two or more layers. In another method, a pattern of tightly packed hexagonal tiles are drawn. Each tile is isolated from its neighboring tiles by specifying breaks of unexposed material between the tiles. Using an interrupted scan method, vectors are drawn with periodic breaks along their lengths. In another method, modulator and scanning techniques are used to reduce exposure problems associated with the acceleration and deceleration of the scanning system when jumping between vectors or changing scanning directions.

Abstract: Methods and apparatus for use in building three-dimensional objects on substantially a cross-sectional basis including methods and apparatus for forming successive layers using counter-rotating rollers, ink jet recoaters, spinning members which sling material, applicator bars that dispense material via a meniscus and/or independently dispensed streams, and also including methods and apparatus to determine a preferred region over which to form a layer and to check for building errors.

Abstract: Improved apparatus and methods for forming a layer of material over a surface of a previously-formed cross-section of a three-dimensional object in anticipation of forming a next cross-section of the object out of the layer. A volume of material, including at least some excess material, is placed over the surface, and the excess material is swept off by placing the excess material in the predetermined path of a sweeping member, the path being substantially in a plane spaced from a working surface of material. The member may be directed to sweep the excess material away through a successive number of sweeps, which may vary for each cross-section, at least a velocity which may vary for each sweep. Additionally, the clearance between the member and the surface of the previous cross-section may vary for each sweep. A "winged" member is also provided, comprising two legs extending from a base, and a "Trident" embodiment is also provided, comprising three legs extending from a base.

Abstract: Methods and apparatus for providing a vibrational enhancement to the recoating process in stereolithography are disclosed. The formation of a thin layer of building material over a previous layer of structure of a partially completed three-dimensional object, in preparation for formation of an additional layer of structure, is enhanced by the use of vibrational energy imparted to the building medium. In a first preferred apparatus, vibration is induced into the surface of the material by a plurality of vibrating needles that penetrate below the working surface to a sufficient depth to ensure adequate coupling but not deep enough to come into contact with the surface of the partially completed part. In a second preferred apparatus, vibration is coupled directly to the object support. The vibrational energy is then transmitted through the part to the surface of the building material.

Abstract: Methods and apparatus for providing a vibrational enhancement to the recoating process in stereolithography are disclosed. The formation of a thin layer of building material over a previous layer of structure of a partially completed three-dimensional object, in preparation for formation of an additional layer of structure, is enhanced by the use of vibrational energy imparted to the building medium. In a first preferred apparatus, vibration is induced into the surface of the material by a plurality of vibrating needles that penetrate below the working surface to a sufficient depth to ensure adequate coupling but not deep enough to come into contact with the surface of the partially completed part. In a second preferred apparatus, vibration is coupled directly to the object support. The vibrational energy is then transmitted through the part to the surface of the building material.

Abstract: Apparatus and method for stereolithographically forming a three-dimensional object includes a vessel for holding a building material and a smoothing member for forming a uniform coating over a previously formed layer of the object. The smoothing member has a plurality of blades. The smoothing member is swept over a previously formed layer of the object, in at least two directions. Different clearances between the lower surface of the smoothing member and the upper surface of the previously formed layer are used to provide a uniform coating for a subsequent layer over the previously formed layer. The sweeping velocity of the smoothing member can be varied. Retractable needles are attached to the smoothing member for adjusting a blade gap between a lower surface of the smoothing member and the surface of the building material.

Abstract: The instant invention is directed to related methods of producing a three-dimensional object by dispensing sheets of a material, capable of physical transformation upon exposure to synergistic stimulation, onto a substantially flat working surface of a previous cross-section. In one preferred embodiment, sheets of a photoresist are employed which change solubility upon exposure to electromagnetic radiation. In other preferred embodiments, non-photoreactive sheets are employed, which ablate upon exposure to infrared radiation.

Abstract: An improved method for stereolithographically making an object by alternating the order in which similar sets of vectors are exposed over two or more layers. In another method, a pattern of tightly packed hexagonal tiles are drawn. Each tile is isolated from its neighboring tiles by specifying breaks of unexposed material between the tiles. Using an interrupted scan method, vectors are drawn with periodic breaks along their lengths. In another method, modulator and scanning techniques are used to reduce exposure problems associated with the acceleration and deceleration of the scanning system when jumping between vectors or changing scanning directions.

Abstract: Amorphous boric oxide-containing product having about 85 to 92% B.sub.2 O.sub.3 is produced by heating boric acid at an elevated temperature of up to about 275.degree. C. to dehydrate the boric acid and form a molten glass which is cooled to a solid glassy product. This solid glass can be comminuted to produce a particulate product. Preferably the boric acid is heated at 220.degree. to 275.degree. C., with about 250.degree. to 270.degree. C. being most preferred. The process is readily adapted to a continuous process in which the boric acid is placed on a moving continuous steel belt and conveyed through a heating zone. The molten glassy product is cooled to form a solid glassy product which is removed from the belt and comminuted to a desirable particle size range.

Abstract: Improved apparatus and methods for forming a layer of material over a surface of a previously-formed cross-section of a three-dimensional object in anticipation of forming a next cross-section of the object out of the layer. A volume of material, including at least some excess material, is placed over the surface, and the excess material is swept off by placing the excess material in the predetermined path of a sweeping member, the path being substantially in a plane spaced from a working surface of material. The member may be directed to sweep the excess material away through a successive number of sweeps, which may vary for each cross-section, at least a velocity which may vary for each sweep. Additionally, the clearance between the member and the surface of the previous cross-section may vary for each sweep. A "winged" member is also provided, comprising two legs extending from a base, and a "Trident" embodiment is also provided, comprising three legs extending from a base.

Abstract: An improved method for stereolithographically forming a three-dimensional object wherein ordinarily solidified internal walls of the object remain at least partially unsolidified. Any unsolidified medium within the object can be drained from the internal walls of the object prior to post-curing so that a hollow three-dimensional object is formed. The object is formed on a layer by layer basis with the internal portion of each layer of the object formed as a grid of solidified portions and unsolidified portions wherein the solidified and unsolidified portions are different on each layer. Objects formed in this manner can be used as patterns in investment casting.

Abstract: A method and apparatus for eliminating or substantially reducing curling effects in stereolithographically formed objects. Synergistic stimulation is applied to a curable material to form a three dimensional object through the build up of successive layers. Curling between successive layers is eliminated or substantially reduced by curing a balancing layer in relation to a balanced layer such that reverse curl of the balanced layer caused by the balancing layer offsets or negates normal curl of the balanced layer caused by the balancing layer.

Abstract: Systems for and methods of generating three-dimensional objects from a medium capable of selective physical transformation upon exposure to synergistic stimulation, whereby sheets of medium corresponding to cross-sectional layers of the three-dimensional object are dispensed from a source, the dispensed sheets then being selectively exposed to synergistic stimulation thereby forming a layer of the three-dimensional object, the areas not exposed to synergistic stimulation being removed, and whereby successive sheets corresponding to successive cross-sectional layers are dispensed and selectively exposed to synergistic stimulation and integrated together with preceding layers to provide substantially a layer by layer buildup of the three-dimensional object, thereby forming the three-dimensional object.

Abstract: An improved method for stereolithographically making an object by alternating the order in which similar sets of vectors are exposed over two or more layers. In another method, a pattern of tightly packed hexagonal tiles are drawn. Each tile is isolated from its neighboring tiles by specifying breaks of unexposed material between the tiles. Using an interrupted scan method, vectors are drawn with periodic breaks along their lengths. In another method, modulator and scanning techniques are used to reduce exposure problems associated with the acceleration and deceleration of the scanning system when jumping between vectors or changing scanning directions.

Abstract: Apparatus and methods for stereolithographically forming a three-dimensional object includes a vessel for holding a building material and a smoothing member for forming a uniform coating over a previously formed layer of the object. The smoothing member has a plurality of blades. The smoothing member is swept over a previously formed layer of the object, in at least two directions. Different clearances between the lower surface of the smoothing member and the upper surface of the previously formed layer are used to provide a uniform coating for a subsequent layer over the previously formed layer. The sweeping velocity of the smoothing member can be varied. Retractable needles are attached to the smoothing member for adjusting a blade gap between the lower surface of the smoothing member and the surface of the building material.