Method for the manufacture of vacuum tubes stems
US4846746A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 25, 1987 |
| Grant date | Jul 11, 1989 |
| Priority date | — |
| Expiry date | Nov 25, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J9/30
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method of manufacturing stems for vacuum tubes is disclosed. The method makes it possible, in particular, to improve the quality of the seal between the metallic bushings and the glass of the stem. The method consists in loading a bottom mold with a first glass piece and a second glass piece and metallic conductors, and then in heating the glass pieces before pressing them against each other between the bottom mold and the top mold. According to one characteristic of the invention, the first piece, which constitutes an external piece partially fixed in the bottom mold, is directly heated only on an upper part which is not fixed, and the two glass pieces are pressed against each other as soon as the upper part has reached a so-called working temperature in order to prevent prolonged contact between the upper part and a limited surface of the conductors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.