Punch press forming CRT shadow masks
US4890471A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 17, 1989 |
| Grant date | Jan 2, 1990 |
| Priority date | — |
| Expiry date | Jan 17, 2009 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB21D22/02
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A CRT shadow mask 9 is made by clamping the outer periphery of a blank, stretch or draw-forming the main spherical surface 9a of the mask, releasing the clamping and wipe-forming the skirt 9c of the mask, and finally press-forming a peripheral spherical border 9e inward of the skirt and having a sharper angle of inclination. The border prevents the spring-back of the high yield strength mask material and the attendant formation of creases and dimples in the mask surface. The die press for implementing the process features an inner pad 32 surrounded by an outer pad 31, both defining spherical surfaces configured to mate with those of a punch 1 for individually forming the main surface and border of the mask. The components are arranged such that a single downward stroke of the press successively implements all of the forming steps.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.