Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Having separate expander means – Including sleeve and distinct tapered expander
Reexamination Certificate
2003-03-07
2004-12-28
Miller, William L. (Department: 3677)
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Having separate expander means
Including sleeve and distinct tapered expander
C411S016000, C411S071000
Reexamination Certificate
active
06835036
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to an expansion anchor for use in a substrate, more particularly to an expansion anchor for use in holes formed in concrete, cement or masonry.
2. Description of the Related Art
Expansion anchors are known generally for use in a substrate, for example, in the construction industry as lifting anchors for concrete walls, as in U.S. Pat. No. 6,279,274, or for bracing concrete walls and floors of new buildings.
Conventional wedge anchors include a stud and an expansion sleeve or other element that is disposed around the stud, wherein the expansion sleeve is expanded to engage with a wall of a hole to anchor the stud within the hole. Examples of such anchors are disclosed in U.S. Pat. Nos. 3,855,896, 4,291,608 and 5,816,759.
Anchors such as those described typically fail due to pull-out when an overloading force is applied. This is particularly true for concrete and masonry substrates. Pull-out failure occurs when the expansion sleeve pulls through the substrate so that the sleeve and the stud are pulled out of the hole. Pull-out failure is not easily predictable, and can occur over a wide range of forces. For example, for a concrete substrate, an anchor can pull out at about 9,000 pounds of force, and can be predicted within about 3,000 pounds. This range can make engineering design based on the strength of the anchor difficult.
Hard expansion sleeves or expansion members tend to pull out of the substrate easier, particularly hard round wires or members with sharp edges. The hard members tend to cause broaching through the substrate because they are hard enough to pull through the substrate.
Further, traditional expansion anchors can only be removed by either applying enough force to broach the substrate and pull the anchor out of the hole or by cutting the stud off at the hole. Neither option allows the stud to be reused.
Attempts have been made to overcome the above described shortcomings, for example International application WO 00/32946, in particular FIGS. 14A, 14B and 15, and page 15 of the specification which teach a hard spiral member that expands outwardly radially. However, this reference appears to have the same broaching problems as described above.
What is needed is an anchor for use in substrates, particularly in concrete, cement or masonry, that is strong, has a predetermined failure strength, and that preferably can be removed and reused without having to broach or cut the stud.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, an expansion anchor is provided. The inventive anchor includes a stud having threads including a root, a land, and a taper extending between the root and the land. The expansion anchor of the present invention also includes a helical member threadingly engageable with the threads of the stud, the helical member having a leading edge. The helical member is movable between an unexpanded position and an expanded position, wherein in the expanded position the leading edge is forced radially outwardly by the land.
In another aspect of the invention, an expansion anchor is provided comprising a helical member and a stud having threads. The helical member is threadingly engageable with the threads, and the helical member has a finger extending in a leading direction. The helical member is movable between an unexpanded position and an expanded position.
Also in accordance with the invention, a method for anchoring a stud within a substrate is provided. The inventive method includes the steps of providing a stud having a leading end with threads having a root, a land, and a taper extending between the root and the land, providing a helical member having a leading edge, threadingly engaging the helical member with the threads, inserting the leading end of the stud into a hole in a substrate, the hole having a wall, withdrawing the stud from the hole so that the stud moves a predetermined distance relative to the helical member, and expanding the helical member until the leading edge is wedged between the land and the wall.
The present invention provides a novel expansion anchor for use in anchoring a stud within a substrate that resists failure due to pullout, has a predetermined failure strength and, in another aspect, the stud can be removed and reused.
These and other objects, features and advantages are evident from the following description of an embodiment of the present invention, with reference to the accompanying drawings.
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patent: 4613264 (1986-09-01), McIntyre et al.
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patent: 5006023 (1991-04-01), Kaplan
patent: 5042888 (1991-08-01), Shinjo
patent: 5634750 (1997-06-01), Frischmann et al.
patent: 00/32946 (2000-06-01), None
Breh Donald J.
Croll Mark W.
Illinois Tool Works Inc.
Miller William L.
Soltis Lisa M.
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