Double break-off screw
US3937121A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 14, 1975 |
| Grant date | Feb 10, 1976 |
| Priority date | — |
| Expiry date | Apr 14, 1995 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16B41/005
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A double break-off screw fastener is described, which conceals its mode of fastening by means of a "dummy" free-floating middle shaft. The inventive screw contains three sections, a threaded section which does the actual fastening; a middle shaft section which helps to internally fasten the threaded section before breaking-off; and an outer head section which breaks from the middle shaft, thus leaving the middle shaft in a free-floating state. To the outer observer, the middle shaft is free turning giving the impression of a fastening screw. In reality, however, it is nothing more than a dummy member, which carefully conceals the well hidden internal screw thread.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.