Wedge anchor for concrete
An expansion wedge anchor for insertion in a hole delimited by a wall comprises an expander member and an expansion member, the expander member being provided at a leading end of the expander member, the expander member comprising a flaring end, the expansion member being expandable at a trailing end thereof and being adapted to engage the wall of the hole when the expander member is positioned in the hole, wherein upon longitudinal withdrawal of the expander member from the hole, the expander member displaces longitudinally relative to the expansion member with the flaring end thereof gradually causing the trailing end of the expansion member to expand, whereby a trailing edge of the expansion member engages the wall of the hole. The trailing end is adapted, when expanded by the flaring member, to extend at an angle with respect to a longitudinal axis of said expander member. In the method of setting the expansion wedge anchor in the hole, the following steps are found: (a) providing an expander member and an expansion member; and (b) displacing the expander member such as to cause a trailing end of the expander member to engage the wall of the hole.
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This Application is a Continuation of U.S. patent application Ser. No. 11/011,755 filed on Dec. 14, 2004 (now U.S. Pat. No. 7,587,873 issued on Sep. 15, 2009), which is a Continuation of U.S. patent application Ser. No. 09/857,403 filed on Jun. 1, 2001 (now U.S. Pat. No. 6,829,871 issued on Dec. 14, 2004), which is a National Entry Application of PCT Application No. PCT/CA99/01129 filed on Dec. 1, 1999, which claims priority on U.S. Provisional Application No. 60/110,530 filed on Dec. 1, 1998. All documents above are herein incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to fasteners and, more particularly, to expandable fasteners for mounting to concrete structures, and the like.
2. Description of the Prior Art
Expandable anchors of many different types are already known. More particularly, expandable anchors have been developed for insertion into a hole formed in a support structure such that a cylindrical expansion sleeve of the anchor may be selectively expanded into frictional contact with the inside peripheral surface of the hole such that the anchor becomes frictionally anchored in the support structure. Typically, the expandable anchor includes an elongated expander member having a threaded first end and a flared second end opposite the first end with a cylindrical surface extending between the first and second ends around which there is provided the aforementioned expansion sleeve. The threaded first end is like a headless screw and extends outwardly of the support structure once the expandable anchor is positioned in the hole thereof. A nut threaded on the visible part of the threaded first end may be used as an actuating mechanism with an object to be secured to the support structure being typically located between the nut and the support structure as the threaded first end of the expandable anchor extends through this object. By rotating the nut, it engages the outer surface of the object and thus bears upon it such as to pull the expander member in an outward direction. As the expansion sleeve is already sufficiently frictionally engaged with the inside surface of the hole, when the expandable anchor is pulled by the rotation of the nut, the expansion sleeve stays substantially stationary in the hole and thus, as the expander member is pulled out of the hole, the flared second end of the expander member causes the cylindrical expansion sleeve to expand radially outwardly thereby increasing a friction between the expansion sleeve and the hole and thus further securing the expandable anchor therein.
Since the expansion sleeve must already be frictionally engaged with the hole before the expandable anchor is pulled, the outside diameter of the expansion sleeve must be similar to, even slightly greater than, the inside diameter of the hole in order to ensure an initial frictional contact therebetween which will then allow the expansion sleeve to remain still in the hole while the expander member is pulled outwardly thereof and thus allow the expansion sleeve to be expanded by the flared end of the expander member. This diameter of the expander member, at rest, results in that the expandable anchor when initially inserted in the hole must be inconveniently driven with significant force therein as the expansion sleeve is already frictionally engaged with the inside wall of the hole. The flared end then acts as a wedge to expand the expansion sleeve into greater frictional contact with the inside of the hole.
For instance, U.S. Pat. No. 2,647,431 issued on Aug. 4, 1953 to Lewis discloses an expansion bolt comprising a hollow shell having a leading end adapted to be expanded by a wedge into frictional contact with the peripheral wall of a hole. Resilient spurs, in some cases as part of a separate bail, are provided at opposite trailing ends of the shell, i.e. the end which is nearest to the opening of the hole, in order to engage the wall of the hole and prevent initial rotation of the shell relative to the hole until the shell frictionally engages the wall.
U.S. Pat. No. 3,250,170 issued on May 10, 1966 to Siegel, U.S. Pat. No. 3,620,120 issued on Nov. 16, 1971 to Warner, U.S. Pat. No. 4,337,012 issued on Jun. 29, 1982 to Sohnius, U.S. Pat. No. 4,403,894 issued on Sep. 13, 1983 to Clark, U.S. Pat. No. 5,028,188 issued to Jul. 2, 1991 to Prince and U.S. Pat. No. 5,344,257 issued on Sep. 6, 1994 to Wright et al. all disclose to expand a shell in a direction normal to a hole axis such that the periphery of the shell frictionally engages a wall of the hole. Notably, U.S. Pat. Nos. 3,620,120, 5,028,188 and 5,344,257 each describes having a resilient shell for facilitating the introduction of the expandable anchor within a hole while providing sufficient holding pressure to prevent the shell and associated wedge member from spinning in the hole as a torque is applied to a bolt for axially displacing the wedge member such as to radially expand the shell.
U.S. Pat. No. 2,783,673 issued on Mar. 5, 1957 to Lewis et al. and U.S. Pat. No. 5,352,066 issued on Oct. 4, 1994 to Schaeffer et al. also both disclose an expandable shell for facilitating the installation thereof within a hole. The leading end of the shell may be expanded at an angle with respect to the central axis of the hole.
Also known are undercut wedge anchors, wherein the hole formed in the support structure is enlarged with a tool at a distance from the visible opening of the hole such that the expandable undercut wedge anchor may thereafter be inserted in the hole until its expansion sleeve becomes located behind a shoulder defined at the junction of the enlarged area and the remainder of the hole. Once expanded, the expansion sleeve may abut this shoulder and thus retain the anchor in position in the support structure.
SUMMARY OF THE INVENTIONIt is therefore an aim of the present invention to provide an improved expandable wedge anchor for use in holes in various materials, e.g. concrete.
It is also an aim of the present invention to provide an expandable wedge anchor having an expander member and an expansion member capable of spring-like deformation.
It is a further aim of the present invention to provide an expandable wedge anchor wherein the expansion member is capable of being expanded at a trailing end thereof.
It is a still further aim of the present invention to provide an expandable wedge anchor wherein the expansion member may be rotated in the hole such that its trailing end produces an undercut in the hole into which the expanded trailing end nests.
It is a still further aim of the present invention to provide a spiral wedge anchor also in accordance with the present invention.
Therefore, in accordance with the present invention, there is provided an expansion wedge anchor for insertion in a hole delimited by a wall, comprising an expander means and an expansion means, said expansion means being provided at a leading end of said expander means, said expander means comprising flaring means, said expansion means being expandable at a trailing end thereof and being adapted to engage the wall of the hole when said expander means is positioned in the hole, wherein upon longitudinal withdrawal of said expander means from the hole, said expander means displaces longitudinally relative to said expansion means with said flaring means thereof gradually causing said trailing end of said expansion means to expand, whereby a trailing edge of said expansion means engages the wall of the hole.
More particularly, said trailing end is adapted, when expanded by said flaring means, to extend at an angle with respect to a longitudinal axis of said expander means.
Also in accordance with the present invention, there is provided a method of setting an expansion wedge anchor in a hole delimited by a wall, comprising the steps of: (a) providing an expander member and an expansion member; and (b) displacing said expander member such as to cause a trailing end of said expansion member to engage the wall of the hole.
More particularly, in step (b), said trailing end is expanded such as to extend at an angle with respect to a longitudinal axis of said expander member.
Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof, and in which:
The purpose of this new non-slip expansion anchor concept is to provide an improved anchor design capable of achieving superior performance over convention al type expansion anchors presently offered. Another area to be considered is that of the effect of vibratory loading on the anchor performance. This is relevant considering the anchor is designed to provide minimal relaxation of the anchor assembly after installation. In conventional expansion anchors the bolt tends to loosen after the initial setting torque has been applied and as a result it must be re-tightened to establish the proper clamping load. The positive set between the anchor bolt and clip segments will provide minimal slip or creep once the anchor is set and the load is applied to the anchor.
The expander member 12 also includes a flared distal end 20 around which is provided the expansion member 14 which is dimensioned to frictionally engage the walls of the hole. Once the anchor 10 has been introduced in the hole H, the nut N is rotated to displace the expander member 12 translationally outwardly of the hole H, As the friction forces between the expansion member 14 and the hole H are sufficient for it to remain stationary therein during the displacement of the expander member 12, the flared end 20 of the expander member 12 causes the expansion member to expand, as seen in
In
The expansion member 34 comprises a leading support 46, an expandable collar 48 and a leg 50 connecting the support 46 and collar 48 together. The collar 48 is split at 52 to allow it to expand, as seen in
In operation, the rotation of the nut N causes the expander member 32 to displace longitudinally and outwardly along the hole H. As the collar 48 of the expansion member 34 frictionally engages the walls of the hole H, it remains stationary therein while the groove 58 slides along the leg 50. It is noted that the leg 50 is biased outwardly, i.e. to an open or deployed position, to ensure the initial frictional engagement of the collar 48 with the walls of the hole H. It is also noted that the outside surface of the collar 48 is knurled for additional friction.
The partial withdrawal of the expander member 32 from the hole H causes the flared end 40 to expand outwardly the collar 48 with a trailing edge 60 of the collar 48 engaging the walls of the hole H at an angle with respect to a longitudinal axis of the hole H (see
It is noted that the cylindrical intermediate section 42 allows the collar 48 to be received in a collapsed position (see
The expandable member 34 is also provided on its leg 50 with a reinforcement rib 62 to provide more rigidity to the leg 50. The leading support 46 of the expandable member 34 comprises a concave bottom 64 to still give more rigidity to the leg 50. At the very end of the flared section 40 of the expander member 32 is a radial flat section land 66 to allow for maximum interference between the hole H, the expander member 32 and the expansion member 34.
In the following descriptions which pertain to variants of the anchor 30 of
In
The expansion member 34b of anchor 80 defines a pair of rounded radii 82 and 84 to increase the rigidity of the legs 50b.
Therefore, with respect to the anchor of FIGS. 6A to 7E′, the new wedge concept is made up of two components. One is a specially formed stud or expander member which is partially threaded at one end. Assembled to the bottom end is a multi segment expansion clip or expansion member which is assembled to the flared end of the stud opposite the threaded end.
The stud (
The expansion clip (
Each segment is connected to a formed concave shaped section via a formed leg section. Each leg connecting a segment has a strengthening rib and internal radii to add rigidity to the clip assembly. Another feature located on each segment is a locking tab which helps control expansion and keep the clip segments in line. This provides for a full 360 degree expansion. A portion of each is knurled to provide additional friction and holding power.
Anchor Installation/FunctionA nut/washer is assembled to the threaded end of the stud assembly. The embedment is determined and measured from directly under the washer to the bottom end of the bolt. The anchor is driven into a pre-drilled hole in the concrete. As the anchor is driven into the hole using a hammer, the pre-expanded segments of the clip assembly provide the frictional resistance to resist the axial pullout resulting during the initial setting of the anchor.
As the installation torque is increased, the nut is tightened flush against the flat washer and the concrete. As a result the tapered portion at the bottom of the stud is pulled upward into the clip segments causing expansion of the lower clip segments located toward the bottom portion of the bolt (see
The purpose of this undercut type anchor concept is to provide a high strength instant holding mechanical type anchor designed to achieve superior pullout performance in concrete while provided a positive lock into the concrete to prevent anchor slip or creep.
The feature of being instant holding makes it suitable for applications needing to apply the load immediately which is not the case with chemical type anchors. This anchor must be capable of withstanding both vibratory and shock type loads without failure. Failure would be determined by the improved load versus displacement relationship.
The undercut anchor 100 consists of two specially formed components, namely a stud or expander member 102 and a clip or expansion member 104, both made of high strength steel to provide the resistance needed to overcome the forces acting as a result of the high installation torque required to set the anchor into the concrete. Existing designs consist of more than two assembled components.
The expander member 102 which is made of high strength steel to resist heavy duty tension and shear applications comprises a threaded section 106, a proximal hex drive element 108 located at the top or beginning of the threaded section as a positive means of providing the spinning or rotational action to the anchor 100 during installation. The standard hex element 108 allows the use of a conventional type socket type drive for fast access and easy removal.
At the opposite end of the expander member 102 is a specially designed stud configuration that provides a means to expand the undercut mechanism (or expansion member 104) which will provide the positive lock between the expander member 102 and the concrete of the support structure S. This stud configuration consists of longitudinal opposed first leading and second trailing flared portions 110 and 112, respectively. The trailing tapered portion 112, located towards the threaded section 106, provides a means of expanding the undercut mechanism or expansion member 104 which in turn defines the undercut into the concrete. At a proximal end of the trailing flared portion 112, is a collar 114 which is used to prevent the undercut mechanism or expansion member 104 from moving onto the threaded section 106 of the expander member 102.
The leading flared portion 110 provides a means of expanding the bottom portion, or distal end, of the expansion member 104, to thus complete the undercut/locking process. At the end of each flared portion is a specially formed configuration to prevent the expansion member 104 from rotating free of the expander member 102 during the initial undercut action and during the final installation process.
The multiple function specially designed undercut mechanism/expansion member 104 which is made of high strength steel comprises an expandable collar 116, a leading support 118 and a pair of legs 120, reinforced with ribs 122, connecting the expandable collar 116 and the leading support 118 together. The leading support 118 has a formed end 124 at the bottom to reduce friction and serve as a means of providing a way of forcing the expandable collar 116 against the trailing flared portion 112 of the expander member 102.
The expandable collar 116 is split at 126 to allow it to expand and has at its trailing end a pair of inwardly directed tabs 128 which with the legs 120 engage trailing and leading recesses 130 and 132, respectively, defined in the trailing and leading flared portions 112 and 110. The expansion member 104 is held captive by these longitudinal recesses 130 and 132 thereby preventing the expansion member 104 from rotating with respect to the expander member 102 and forcing it to work vertically without twisting. The expandable collar 116 defines opposed leading and trailing edges 134 and 136, respectively. Between the flared portions 110 and 112, the expander member 102 defines a cylindrical portion 138 which allows the expandable collar 116 to be received in a collapsed position when the anchor 100 is initially driven in the hole H.
Anchor Installation/FunctionThe anchor 100 is driven into the pre-drilled hole H until it is reaches its bottom (see
Once the undercut action has been completed, the expander member 102 is set by assembling the nut N and washer W to a trailing end of its threaded section 106. The nut N is rotated until it is hand tight against the flat washer W and flush with the support structure S. As the nut N is tightened to a specified torque, it draws the expander member 32 longitudinally and outwardly out of the hole H. Although the trailing flared portion 112 disengages from the collar 116, the trailing edge 136 of the collar 116 remains set in the undercut (see
The partial withdrawal of the expander member 102 from the hole H thus causes the leading flared portion 110 to expand the collar 116 outwardly with the leading edge 134 of the collar 116 engaging the walls of the hole H (see
The anchor 100 thus provides the undercut needed to maintain the locked position of the installed anchor 100. The upper portion of the expansion member 104 also contains a special configuration which includes a formed cutting edge 136 and/or surface to allow it to cut into the concrete and aggregate via the axial rotation provided by the drive tool spinning the expander member 102. To increase resistance to wear, a special coating (e.g. abrasive, diamond coatings) or a series of hardened particles 140 can be applied onto the surface and/or cutting edge 136 of the undercut portion of the expansion member 104.
The hex drive element 108 can take other forms as long as the expander member 102 can be gripped from outside the hole H and rotated.
In the present non-slip wedge anchors (see
In the case of the undercut wedge, there is a first expansion of the expansion member followed by a rotation of the bolt such that the expanded upper edge of the expansion member cuts into 360° of concrete and thus provides the undercut needed to maintain the locked position of the anchor. More specifically, the first expansion of the expansion member is effected by applying a constant downward pressure on the bolt so as to cause the expansion to move axially over an upper flared portion of the bolt. Once the undercut action has been completed, the expansion member is expanded by drawing a lower flared portion of the bolt into the expansion member via operation of a nut threadably engaged with the threaded end of the bolt, thereby completing the setting of the undercut/expansion mechanism.
A main advantage of the above-described non-slip and undercut wedge anchors resides in the fact that they provide a much stronger grip than that of known friction-based sleeve designs. In the case of the undercut wedge anchor, no separate drill bit is required to define the undercut.
C) Spiral Wedge Anchor (FIGS. 14 to 15)When referring throughout this disclosure and claims to terms such as “withdraw”, it is readily understood that the expander member is not completely removed from the hole, but rather partly displaced longitudinally out of the hole and relative to the expansion member for effecting the expansion of the expansion member. The anchored position of the present anchors well illustrate this configuration (see
Claims
1. An expansion wedge anchor for insertion in a hole delimited by a wall, comprising an expander means and an expansion means, said expansion means being provided at a leading end of said expander means, said expander means comprising flaring means, said expansion means being expandable at a trailing end thereof and being adapted to engage the wall of the hole when said expander means is positioned in the hole, wherein upon longitudinal withdrawal of said expander means from the hole, said expander means displaces longitudinally relative to said expansion means with said flaring means thereof gradually causing said trailing end of said expansion means to expand, whereby a trailing edge of said expansion means engages the wall of the hole.
2. An expansion wedge anchor as defined in claim 1, wherein said trailing end is adapted, when expanded by said flaring means, to extend at an angle with respect to a longitudinal axis of said expander means and to so engage the wall of the hole, and wherein said expander means and said expansion means are each made of a single unitary component.
3. An expansion wedge anchor as defined in claim 1, wherein said expander means comprise proximally of said flaring means a threaded section adapted to be engaged, at a proximal end thereof outside of the hole, by a female threaded member which when rotated causes said expander means to displace translationally along the hole.
4. An expansion wedge anchor as defined claim 1, wherein said flaring means comprise a flared end which tapers towards said threaded section, an intermediate section being provided proximally of said flared end and having a diameter less than that of said threaded section, said intermediate section providing space to accommodate outwardly thereof at least part said expansion means in a collapsed position thereof at least for during insertion of said anchor in the hole.
5. An expansion wedge anchor as defined in claim 1, wherein said expander means defines a shoulder at a junction of said threaded section and said intermediate section for preventing said expansion means from reaching threaded section.
6. An expansion wedge anchor as defined in claim 1, wherein said expansion means comprises a leading support located distally past said leading end, an expandable collar means provided proximally of said leading support and at least one leg means extending outwardly of said expander means and connecting said collar means to said leading support, said collar means defining said trailing edge and being adapted to be outwardly expanded by said flaring means wherein said collar means is angled relative to a longitudinal axis of the hole, said collar means flaring from a distal end thereof toward a proximal end thereof, said proximal end defining said trailing edge, whereby said collar means engages the wall of the hole more deeply proximally than distally.
7. An expansion wedge anchor as defined in claim 6, wherein said collar means defines a longitudinal split for each said leg means.
8. (canceled)
9. (canceled)
10. An expansion wedge anchor as defined in claim 7, wherein at each said split, facing edges of said collar means define cooperating mating means, and wherein said cooperating mating means comprise tongue and groove elements provided transversally on respective ones of said facing edges.
11. (canceled)
12. An expansion wedge anchor as defined in claim 6, wherein said flaring means define a recessed longitudinal guide for each said leg means for preventing said expansion means from rotating with respect to said expander means.
13. (canceled)
14. (canceled)
15. An expansion wedge anchor as defined in claim 1, wherein said flaring means comprise a trailing flared portion which tapers away from said threaded section and which is adapted to expand said trailing end of said expansion means such that said trailing edge thereof engages the wall of the hole, wherein said expansion means is adapted to rotate with said expander means, whereby upon rotation of said expander means said trailing edge of said expansion means defines an undercut in the wall of the hole and subsequently remains lodged in said undercut.
16. An expansion wedge anchor as defined in claim 15, wherein said flaring means further comprise an intermediate portion being provided distally of said trailing flared portion and having a diameter less than that of said threaded section, said intermediate portion providing space to accommodate outwardly thereof at least part said expansion means in a collapsed position thereof at least for during insertion of said anchor in the hole.
17. An expansion wedge anchor as defined in claim 15, wherein said expander means comprise proximally, for access outside of the hole when said expansion means is located in the hole, a drive means engageable by a tool for rotating said expander means and said expansion means.
18. An expansion wedge anchor as defined in claim 15, wherein said expander means further comprises a leading flared portion tapering towards said threaded section, said intermediate portion extending between said leading and trailing flared portions, wherein said leading flared portion is adapted to expand a leading end of said expansion means.
19. An expansion wedge anchor as defined in claim 18, wherein, once said undercut has been formed in the wall of the hole by a rotation of said trailing edge, said expander means is adapted to be translationally withdrawn from the hole such that said leading flared portion engages and expands said leading end of said expansion means such as to engage the hole, a leading edge of said leading end of said expansion means extending into the wall.
20. An expansion wedge anchor as defined in claim 19, wherein said leading end of said expansion means extends at an angle with respect to the longitudinal axis of said expander means and so engages the wall of the hole.
21. An expansion wedge anchor as defined in claim 18, wherein said expansion means comprise an expendable collar means defining said trailing and leading ends and said trailing and leading edges, a leading support provided distally of said collar means, and at least one leg means extending outwardly of said expander means and connecting said collar means to said leading support, said collar means being adapted to be outwardly expanded by said trailing flared portion wherein said trailing end of said collar means is angled relative to a longitudinal axis of the hole, said collar means being adapted to be outwardly expanded by said leading flared portion wherein said leading end of said collar means is angled relative to the longitudinal axis of the hole.
22. (canceled)
23. (canceled)
24. An expansion wedge anchor as defined in claim 21, wherein said leading and trailing flared portions of said expander means define leading and trailing recessed longitudinal guides which respectively engage said leg means and tab means provided proximally at said trailing end of said expansion means, thereby preventing said expansion means from rotating with respect to said expander means.
25. (canceled)
26. A method of setting an expansion wedge anchor in a hole delimited by a wall, comprising the steps of: (a) providing an expander member and an expansion member; and (b) displacing said expander member such as to cause a trailing end of said expansion member to engage the wall of the hole.
27. A method as defined in claim 26, wherein in step (b) said trailing end is expanded such as to extend at an angle with respect to a longitudinal axis of said expander member, and wherein after step (b), step (c) consists of rotating said expander member and said expansion member from outside of the hole such that the trailing end of said expansion member forms an undercut in the wall of the hole and remains lodged therein.
28. (canceled)
29. A method as defined in claim 27, wherein after step (c), step (d) consists of displacing said expander member relative to said expansion member such as to cause a leading end of said expansion member to engage the wall of the hole.
Type: Application
Filed: Sep 15, 2009
Publication Date: Aug 26, 2010
Applicant: COBRA FIXATIONS CIE LTEE - COBRA ANCHORS CO. LTD. (Montreal)
Inventors: Thomas W. McSherry (Sinking Spring, PA), Pierre McDuff (Outremont)
Application Number: 12/585,453
International Classification: E04C 5/12 (20060101); F16B 13/06 (20060101); E04B 1/35 (20060101);