Abrading – Rigid tool – Rotary cylinder
Reexamination Certificate
2000-02-22
2001-04-10
Banks, Derris H. (Department: 3723)
Abrading
Rigid tool
Rotary cylinder
C451S540000
Reexamination Certificate
active
06213859
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to drilling tools, and particularly to a tool for drilling holes for anchor bolts.
BACKGROUND OF THE INVENTION
Anchor bolts, sometimes also referred to as expansion bolts, the terms being used interchangeably herein, are bolts that have a threaded shank whose tip is fashioned to expand outwards when screwed into a hole. By torquing the anchor bolt sufficiently, the expanded end grips the inner circumference of the hole strongly enough to anchor even heavy objects to a wall or ceiling.
In general, the anchor bolt is simply inserted in a hole whose diameter is slightly larger than the nominal diameter of the anchor bolt shank. The anchor bolt is tightened and expands, thereby gripping the hole.
SUMMARY OF THE INVENTION
The present invention seeks to provide a novel tool for drilling holes for anchor bolts. The tool includes a shank with a bifurcated end formed with a bore, the bifurcated end being formed with an abrasive annulus. The abrasive annulus can serve as a regular drill. A wedge member is inserted in the bore of the shank, and can push apart the bifurcated end when pressed or pushed into the bore of the shank.
The tool prepares a hole for an anchor bolt in the following manner: First, a regular hole is drilled in a wall or ceiling. The drilling tool of the present invention is then inserted in the drilled hole, with the wedge member inserted in the bore of the shank. The wedge member preferably has a conical tip that abuts against the end of the hole, thereby distancing the abrasive annulus from the end of the hole. The drilling tool is then pushed to press the wedge member into the bore of the shank, thereby spreading out the bifurcated end of the shank. The result is that the abrasive annulus drills a counterbore in the wall or ceiling of a larger diameter than the initial, regular hole. During drilling, the conical tip of the wedge member bears against the end of the hole, with the drilling tool rotating about the center of the tip. Thus, the tip acts as a centering support for the drilling tool.
After drilling the counterbore, an anchor bolt of any kind, plastic or metal, can be inserted in the hole. The anchor bolt will now expand not against the regular hole, but rather against the counterbore, meaning that the anchor bolt is expanding against a larger area, thereby forming a stronger fastened connection. It is important to note that because the anchor bolt expands against the counterbore instead of the regular, straight hole, the torque required to expand the anchor bolt is less than that required heretofore in the prior art, and yet the strength of the fastened connection is significantly greater.
It is noted that the drilling tool of the present invention can be manufactured in a variety of sizes and lengths, and can span a multiplicity of diameters, from small to large. The drilling tool can drill any material, such as concrete, brick, masonry, stone (e.g., marble), glass or wood, for example.
There is thus provided in accordance with a preferred embodiment of the present invention a drilling tool including a shank having a chuck end adapted for being held in a chuck of a drill, and an opposite, bifurcated end formed with a bore, the bifurcated end including two portions separated from each other by a gap, an abrasive annulus formed at least partially around the bifurcated end, and a wedge member slidingly disposed in the bore, the wedge member operative to push the two portions away from each other when moved towards the chuck end.
In accordance with a preferred embodiment of the present invention the wedge member includes a tenon that extends outwards from the wedge member, the tenon being received in the gap and guiding the wedge member during sliding travel in the bore.
Further in accordance with a preferred embodiment of the present invention a biasing device is inserted in the bore that urges the wedge member in a direction generally away from the chuck end.
Still further in accordance with a preferred embodiment of the present invention the wedge member includes a generally conical tip pointing away from the chuck end.
Additionally in accordance with a preferred embodiment of the present invention the bifurcated end extends generally conically outwards beyond a diameter of the chuck end.
In accordance with a preferred embodiment of the present invention the wedge member is bifurcated and formed with a bore, the bifurcated wedge member including two portions separated from each other by a gap, an abrasive annulus being formed at least partially around the bifurcated wedge member, wherein an additional wedge member is slidingly disposed in the bore of the first-mentioned wedge member, the additional wedge member being operative to push the two portions of the first-mentioned wedge member away from each other when pushed towards the chuck end.
Further in accordance with a preferred embodiment of the present invention the abrasive annulus is formed at a tip of the bifurcated end. Preferably the abrasive annulus is constructed of a diamond coating.
REFERENCES:
patent: 4055051 (1977-10-01), Finney
patent: 4518290 (1985-05-01), Frichamann et al.
Yekutiely Barak
Yekutiely David
Banks Derris H.
Hoffman Wasson & Gitler
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