Tapered extrusion die and method of forming the same
US4287749A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 15, 1979 |
| Grant date | Sep 8, 1981 |
| Priority date | — |
| Expiry date | Nov 15, 1999 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T408/29
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A sleeve having a tapered outer surface is shrink or interference fitted over the outer surface of a die blank in which is formed a central bore, a larger diameter bore and a transition bore therebetween. The diametrical interference between the sleeve and the die blank is effective in producing an elastic deformation of the smaller diameter bore causing it to assume a conical shape. The die blank and sleeve are restrained within a casing and the inner surface of the die is formed by electrical discharge machining, electrical chemical machining or by other known methods. The die casing and sleeve are removed from the die, allowing the release of the stored strain energy of deformation which causes the smaller bore of the die to assume a conical shape tapering radially outwardly from its inner extremity. The sharp corner that results at the innermost end of the smaller bore is removed by lapping a straight-sided tool through the central opening of the die.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.