Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Externally threaded fastener element – e.g. – bolt – screw – etc. – Thread or shank structure
Reexamination Certificate
2000-09-19
2001-12-25
Wilson, Neill (Department: 3627)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Externally threaded fastener element, e.g., bolt, screw, etc.
Thread or shank structure
C411S309000, C411S411000, C411S418000
Reexamination Certificate
active
06332741
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is generally directed to a novel anchor device or fastening member which is particularly suited for use in the attachment of various fixtures and equipment to masonry, concrete, and other hard and/or friable substrates.
The prior art in one-piece, masonry tapping fasteners have uniform thread forms throughout the entire length of the fastener. They are typically heat treated to a case hardened metallurgical structure. These masonry tapping fasteners have failed for a variety of reasons, such as stripping out during the installation process, brittle failure while resisting the applied loads, and premature failure due to embrittlement and stress corrosion. As a result, users of these fasteners have been required to use other styles of fasteners that have exhibited better load versus displacement characteristics than that of a masonry tapping fasteners. These fasteners also back out of the substrate with relative ease in applications involving dynamic loads and system vibrations.
The present invention provides an anchor device or fastening member which overcomes the problems presented in the prior art and which provides additional advantages over the prior art, such advantages will become clear upon a reading of the attached specification in combination with a study of the drawings.
OBJECTS AND SUMMARY OF THE INVENTION
A general object of the present invention is to provide a novel fastening member which is particularly suited for use in the attachment of various fixtures and equipment to masonry, concrete, and other hard and/or friable substrates.
An object of the present invention is to provide a fastening member which produces a higher torque differential between the tapping torque of the thread and the strip-out torque of the fastening member, thereby resulting in a fastening member that has more inherent reliability, and the capability of being used in a wider variety of substrates versus the prior art.
Another object of the present invention is to provide a fastening member which has less overall axial movement per unit load, while resisting withdrawal forces.
Yet another object of the present invention to provide a fastening member which imparts higher radial loads on the substrate which results in large spall cones and generally higher pullout values in masonry.
A further object of the present invention is to provide a fastening member which provides a more uniform stress distribution at the surface and the upper regions of the substrate.
Yet a further object of the present invention is to provide a fastening member which has a higher resistance to dynamic loads, and system impacts and vibrations.
An even further object of the present invention is to provide a fastening member which provides an overall more ductile anchorage.
Briefly, and in accordance with the foregoing, the present invention discloses a fastening member which is particularly suited for use in the attachment of various fixtures and equipment to masonry, concrete, and other hard and/or friable substrates. The fastening member includes a head and a shank which depends therefrom. The shank has a first threaded portion having a predetermined thread angle and a predetermined hardness, and a second threaded portion having a predetermined thread angle and a predetermined hardness. The first threaded portion is proximate to the head and the second threaded portion extends from the first threaded portion. The thread angle of the first threaded portion is different than the thread angle of the second threaded portion. In addition, the hardness of the first threaded portion is softer than the hardness of the second threaded portion. This provides for a more ductile anchorage when the fastening member is engaged with the substrate.
REFERENCES:
patent: 3133578 (1964-05-01), Moskovitz
patent: 3643543 (1972-02-01), Gutshall
patent: 3937119 (1976-02-01), Ernst
patent: 4730970 (1988-03-01), Hyner et al.
patent: 6086302 (2000-07-01), Gerhard
Textron Inc.
Trexler, Bushnell Giangiorgi, Blackstone & Marr, Ltd.
Wilson Neill
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