# US 4,391,622 A · Method for the precision/manufacture of glass articles

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- Number: US 4,391,622 A
- Document ID: US4391622A
- Status: Granted
- Kind: A
- Application number: 06/264,738
- Filed: 1981-05-18
- Granted: 1983-07-05
- Earliest claimed: 1980-05-28
- Assignees: U.S. Philips Corporation
- Inventors: Cornelis L. Alting; Rudolf Brehm; Jan Haisma
- Web page: https://patentgrep.com/patent/US4391622A

## CPC

- C03B 11/084: {material composition or material properties of press dies therefor}
- C03B 2215/05: Press-mould die materials
- C03B 2215/76: Pressing whereby some glass overflows unrestrained beyond the press mould in a direction perpendicular to the press axis
- C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES

## Abstract

By using special dies, lenses from glass can be manufactured with great precision. Such dies are manufactured from quartz glass. Quartz glass can be worked with the required shape accuracy and the required smoothness, for example, by a polishing treatment succeeded by sputtering.

## Claims

### Claim 1

In a method for precision manufacture of glass articles molded in a mold or hot-pressed in a die, the improvement comprises the step of using a mold or die having at least contact surfaces made from quartz glass or an amorphous SiO.sub.2 with upto 7.5% by weight of TiO.sub.2 with a coefficient of linear expansion of at most 60.times.10.sup.-8 per .degree.C., wherein said glass articles have a substantially higher coefficient of linear expansion.

### Claim 2 (depends on 1)

A method according to claim 1, wherein pure quartz glass having a coefficient of linear expansion of at most 60.times.10.sup.-8 per .degree.C. is used to form said contact surfaces.

### Claim 3 (depends on 1)

A method according to claim 1, wherein glass ceramic being amorphous SiO.sub.2 with upto 7.5% by weight of TiO.sub.2 and having a coefficient of linear expansion ranging from 0 per .degree.C. to 10.times.10.sup.-8 per .degree.C. is used to form said contact surfaces.