Claims
- 1. A method for forming a hollow sphere with concentric inner and outer spherical surfaces, comprising:
- establishing a detached hollow gas-filled body at an elevated temperature at which the walls of the body are in a flowable state;
- maintaining said body substantially free of contact with a solid support; and
- applying vibrations to said hollow body while it is at an elevated temperature and free of contact with a solid to provide said concentric inner and outer spherical surfaces.
- 2. A method for forming a hollow sphere with concentric inner and outer spherical surfaces, comprising:
- establishing a detached hollow gas-filled body at an elevated temperature at which the walls of the body are in a flowable state;
- maintaining said body substantially free of contact with a solid support;
- maintaining said body in an environment of substantially zero gravity, to thereby avoid a tendency for gas to float towards the top of a body and uncenter the inside surface thereof; and
- applying vibrations to said hollow body while it is at an elevated temperature, free of contact with a solid support, and in an environment of substantially zero gravity to provide said concentric inner and outer spherical surfaces.
- 3. The method described in claim 1 wherein said step of establishing includes:
- heating a material which is solid at room temperature, to an elevated temperature at which it is at least plastic;
- forcing the heated material through an aperture so it flows as a stream therethrough while injecting a gas into the middle of the stream, to form a hollow tube filled with gas; and
- applying vibrations to the hollow tube, to help break up the tube into individual hollow bodies of substantially solid material filled with said gas;
- said hollow tube is surrounded by a gaseous medium after it exits the aperture; and
- said step of applying vibrations includes applying vibrations through the gaseous medium to portions of said tube which have exited the aperture, at substantially the same frequency at which the tube tends to break up in the absence of applied vibrations.
- 4. The method described in claim 1 wherein:
- said hollow body is surrounded by a gaseous medium; and
- said step of applying vibrations includes applying vibrations through the gaseous medium to said hollow body while the body and gaseous medium are substantially stationary relative to each other.
- 5. A method for forming a hollow shell with concentric inner and outer surfaces, comprising:
- applying acoustic vibrations through a gaseous medium to a detached hollow body which lies in the gaseous medium free of contact with a solid, and which is at a temperature at which the material of the walls of the body can flow to provide said concentric inner and outer spherical surfaces.
- 6. Apparatus for forming a hollow sphere with concentric inner and outer spherical surfaces, comprising:
- means for passing a succession of detached hollow gas-filled bodies which are heated to a flowable temperature, along a predetermined path; and
- means positioned beside said path for applying vibrations to said bodies while they are free of contact with a solid to provide said concentric inner and outer spherical surfaces.
- 7. The apparatus described in claim 6 including:
- means for extruding a heated plastic material through a die;
- means for injecting a gas at a pressure above ambient pressure, into the extrusion, to form a gas-filled tube that can expand; and
- means for applying acoustic vibrations to said gas-filled tube, to help break it into hollow bodies of uniform size.
- 8. The apparatus described in claim 6 wherein:
- said means for applying vibrations includes an oscillator and a transducer connected to said oscillator and positioned beside said path of said bodies to apply vibrations to said bodies.
ORIGIN OF THE INVENTION
The invention described herein was made in the performance of work under a NASA contract and is subject to the provisions of Section 305 of the National Aeronautics and Space Act of 1958, Public Law 85-568 (72 Stat. 435; 42 USC 2457).
US Referenced Citations (5)
Non-Patent Literature Citations (2)
Entry |
PCT/US79/00621 Torobin, published 3/1980 priority 8/28/78. |
PCT/US/79/00651 Torobin, published 3/1980 priority 8/28/78. |