Method for making small gas-filled beads
US3998618A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 17, 1975 |
| Grant date | Dec 21, 1976 |
| Priority date | — |
| Expiry date | Nov 17, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J9/261
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method and apparatus are disclosed for making small gas-filled beads by locating a heat deformable tube on top of a heated platen in a controlled atmosphere chamber, with a multiple, spaced knife-edge structure located on top of the tube. When the temperature of a tube is raised to its softening temperature, gravity forces the knife edges through the tube, sealing the tube into separated compartments or ampuls with gas in the interior of each compartment. The articles are cooled below the softening temperature of the tube, are separated into ampuls and then the ampuls are reheated above the softening temperature to the working temperature of the tube in a sphere forming cycle under conditions of carefully maintained temperature and pressure such that the surface tension of the glass coupled with the gas within the ampul causes the ampul to take on the shape of a sphere with uniformly thick walls and size, dependent on the temperature and pressure conditions during the reheating cycle.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.