# US 4,400,191 A · Sphere forming method and apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,400,191 A - Document ID: US4400191A - Status: Granted - Kind: A - Application number: 06/403,847 - Filed: 1982-07-30 - Granted: 1983-08-23 - Earliest claimed: 1982-07-30 - Assignees: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration - Inventors: Charles L. Youngberg; Charles G. Miller, deceased; James B. Stephens; Anthony A. Finnerty - Web page: https://patentgrep.com/patent/US4400191A ## CPC - C03B 19/1075: {by blowing, pressing, centrifuging, rolling or dripping} - B01J 2/04: in a gaseous medium {(if combined with suspending the material in a gas, e.g. fluidised beds B01J2/16)} - C03B 19/1095: {Thermal after-treatment of beads, e.g. tempering, crystallisation, annealing} - Y10S 376/916: Methods of making fusion fuel targets - C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A system is provided for forming small accurately-spherical objects. Preformed largely-spherical objects (18) are supported at the opening of a conduit (16) on the update of hot gas emitted from the opening, so the object is in a molten state. The conduit is suddenly jerked away at a downward incline, to allow the molten object to drop in free fall, so that surface tension forms a precise sphere. The conduit portion that has the opening, lies in a moderate-vacuum chamber 40, and the falling sphere passes through the chamber and through a briefly-opened valve (30) into a tall drop tower (32) that contains a lower pressure, to allow the sphere to cool without deformation caused by falling through air. ## Claims ### Claim 1 A method for forming a rounded object, comprising: supporting the object in a largely molten state at an opening in a conduit, including flowing gas in a largely upward vertical direction out of said conduit opening to support the object on the gas flow; and rapidly sidewardly displacing said conduit relative to said object, to allow said object to fall in a vacuum chamber to solidify the object during freefall. ### Claim 2 (depends on 1) The method described in claim 1 wherein: said step of flowing includes flowing hot gas, of a temperature which is at least the temperature at which the object is in a substantially molten state, out of said conduit opening. ### Claim 3 (depends on 1) The method described in claim 1 wherein: said step of displacing includes moving said conduit at a downward incline, to move the walls of said opening simultaneously downwardly and to the side so the body can fall free of the conduit. ### Claim 4 (depends on 1) The method described in claim 1 including: maintaining a valve, which connects to a vacuum drop tower, at a position under said object when said object is supported above said conduit opening, so that when the object falls, it falls to said valve, including initially maintaining said valve closed; and opening said valve shortly before said object falls to said valve, and closing said valve shortly after the object drops therethrough. ### Claim 5 (depends on 1) The method described in claim 1 including: gently stopping said object, including maintaining a liquid oil bath under the falling object, and applying a gas to said oil to form a foam at the top of said liquid bath to cushion the fall of the object. ### Claim 6 (depends on 1) The method described in claim 1 wherein: said step of supporting the object includes maintaining a vacuum in the region which contains said object when it is supported at the conduit opening; and said step of supporting the object also includes feeding said object onto the top of an upwardly facing nozzle which forms said conduit opening, wherein said nozzle has a throat below its top and an expansion section extending upwardly from the throat, while flowing gas upwardly through the nozzle at a rate which is greatly enough to support the object away from the walls of the nozzle, but which is small enough to maintain the object at least partially nestled in the nozzle, whereby to minimize gas flow into said region. ### Claim 7 (depends on 1) The method described in claim 1 wherein: said conduit includes a porous member with at least one recess of about the same size as said object, the pores at said recess forming said conduit opening, and said gas is flowed through said pores at said recess at a rate which supports the objects at least partially nestled in the recess. ### Claim 8 A method for forming a rounded object, comprising: supporting an object on the updraft of hot gas emitted from an opening of a conduit lying under the object; rapidly moving the conduit out from under said object and allowing the object to move downward in free fall, including moving the conduit both downwardly and sidewardly; and cooling to solidify the object during freefall in a vacuum chamber. ### Claim 9 (depends on 8) The method described in claim 8 wherein: said conduit includes a tube that extends at an incline from the vertical, and which has an upper end forming said opening; and said step of rapidly moving the conduit includes moving said tube primarily along its length, at a downward incline. ### Claim 10 Apparatus for forming rounded objects, comprising: walls forming a conduit with an opening which is oriented to emit gas in a largely upward direction; means for flowing gas through said conduit to emit the gas from said opening, to support an object at said opening; means for moving the portion of said conduit which contains said opening, suddenly out of the free fall path of an object supported at said conduit opening to allow the object to fall; and walls forming a chamber that surrounds an object supported at said conduit opening; means for establishing a vacuum in said chamber. ### Claim 11 (depends on 10) The apparatus described in claim 10 including: a drop tower lying under said chamber at the portion thereof which contains an object at said conduit opening, said tower containing a vacuum; a valve connecting said chamber and said drop tower; and means for opening and closing said valve, to pass an object in free fall from the chamber to the drop tower and then close off access between them. ### Claim 12 (depends on 11) The apparatus described in claim 11 including: an oil foam disposed at the lower end of said tower, including oil bubbles containing gas at nearly the low pressure in said tower. ### Claim 13 (depends on 10) The apparatus described in claim 10 including: an object located at said conduit opening; and means for providing hot gas which is emitted from said opening, at a temperature at least about as great as the molten temperature of said object. ### Claim 14 (depends on 10) The apparatus described in claim 10 wherein: said conduit includes a tube extending along an incline and having an upper end forming said opening; and said means for moving includes means for rapidly accelerating said tube downwardly along said incline. ### Claim 15 (depends on 10) The apparatus described in claim 10 including: a largely spherical object; and wherein said conduit opening includes a nozzle with a throat and with an expansion section extending upwardly from said throat, said nozzle being of a size to closely receive said object. ### Claim 16 (depends on 10) The apparatus described in claim 10 wherein: said conduit includes a wall with a recess and a porous wall area leading to said recess, to flow gas into said recess to support an object partially nestled therein. ### Claim 17 Apparatus for forming a spherical object comprising: walls forming a chamber and a drop tower under said chamber; vacuum pump means for maintaining a vacuum in said chamber and in said tower; a conduit located in said chamber, said conduit having an upwardly facing outlet; means for flowing hot gas through said conduit and out of said outlet, to support an object on the updraft of gas from said outlet; means for jerking said conduit at a downward incline, to allow a supported object to fall; and means for briefly opening said valve to allow a falling object to pass from the chamber to the drop tower. ### Claim 18 (depends on 17) In a drop tower of claim 17, the improvement of means for cushioning an object falling through the tower, comprising: an oil bath lying in the lower end of said tower, and bubbles of gas having walls of oil, lying on said oil bath. ### Claim 19 (depends on 18) The improvement described in claim 18 including: means for dropping a plurality of objects of a predetermined diameter through said drop tower; and wherein said bubbles extend to a height above said oil bath, which is greater than the diameter of said objects, whereby a previously-dropped object floating on said oil bath will not be hit by another object. ### Claim 20 A method for processing a material at elevated temperatures at which it is molten, while avoiding contamination by direct contact with a crucible or other container, comprising: applying the material in a solid form to the opening of a conduit, and flowing gas in a largely upward vertical direction out of said conduit opening to support the object on the gas flow; heating the material to a temperature at which it is molten, including heating said gas; and cooling said material in a vacuum chamber during freefall to a temperature at which it is substantially solid. ### Claim 21 (depends on 20) The method described in claim 20 wherein: said step of cooling includes rapidly displacing said conduit relative to said material while it is molten, and allowing the material to fall through a region which is at a lower temperature than the melting temperature of the material.