Abstract:
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.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    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 INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to fasteners and, more particularly, to expandable fasteners for mounting to concrete structures, and the like. 
         [0004]    2. Description of the Prior Art 
         [0005]    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. 
         [0006]    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. 
         [0007]    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. 
         [0008]    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. 
         [0009]    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. 
         [0010]    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 INVENTION 
       [0011]    It 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. 
         [0012]    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. 
         [0013]    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. 
         [0014]    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. 
         [0015]    It is a still further aim of the present invention to provide a spiral wedge anchor also in accordance with the present invention. 
         [0016]    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. 
         [0017]    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. 
         [0018]    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. 
         [0019]    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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    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: 
           [0021]      FIGS. 1A and 1B  are longitudinal cross-sectional views of a first variant of a non-slip wedge anchor in accordance with the present invention shown respectively in at rest and installed positions thereof; 
           [0022]      FIG. 1C  is a bottom plan view of the anchor of  FIG. 1A ; 
           [0023]      FIGS. 2A and 2B  are longitudinal cross-sectional views of a second variant of a non-slip wedge anchor in accordance with the present invention shown respectively in at rest and assembled positions thereof; 
           [0024]      FIGS. 3A and 3B  are respectively elevational and bottom plan views of an expander member of the anchor of  FIGS. 2A and 2B ; 
           [0025]      FIGS. 3C ,  3 D and  3 E are respectively front elevational, side elevational and bottom plan views of an expansion member of the anchor of  FIGS. 2A and 2B ; 
           [0026]      FIGS. 4A and 4B  are longitudinal cross-sectional views of a third variant of a non-slip wedge anchor in accordance with the present invention shown respectively in at rest and assembled positions thereof; 
           [0027]      FIGS. 5A and 5B  are respectively elevational and bottom plan views of an expander member of the anchor of  FIGS. 4A and 4B ; 
           [0028]      FIGS. 5C ,  5 D and  5 E are respectively front elevational, side elevational and bottom plan views of an expansion member of the anchor of  FIGS. 4A and 4B ; 
           [0029]      FIGS. 6A and 6B  are longitudinal cross-sectional views of a fourth variant of a non-slip wedge anchor in accordance with the present invention shown respectively in at rest and assembled positions thereof; 
           [0030]      FIGS. 7A and 7B  are respectively elevational and bottom plan views of an expander member of the anchor of  FIGS. 6A and 6B ; 
           [0031]      FIGS. 7C ,  7 D and  7 E are respectively front elevational, side elevational and bottom plan views of an expansion member of the anchor of  FIGS. 6A and 6B ; 
           [0032]      FIGS. 8A and 8B  are longitudinal cross-sectional views of a first variant of an undercut wedge anchor in accordance with the present invention shown respectively in first and second positions thereof in a support structure; 
           [0033]      FIGS. 9A to 9D  are respectively front elevational, side elevational, bottom plan and top plan views of an expander member of the undercut wedge anchor of  FIGS. 8A and 8B ; 
           [0034]      FIGS. 9E to 9G  are respectively front elevational, side elevational and bottom plan views of an expansion member of the undercut wedge anchor  FIGS. 8A and 8B ; 
           [0035]      FIGS. 10A to 10D  are respectively front elevational, side elevational, bottom plan and top plan views of a second variant of an undercut wedge anchor in accordance with the present invention; 
           [0036]      FIGS. 11A to 11C  are respectively front elevational, side elevational and top plan views of a third variant of an undercut wedge anchor in accordance with the present invention; 
           [0037]      FIGS. 12A to 12C  are respectively front elevational, side elevational and bottom plan views of a fourth variant of an undercut wedge anchor in accordance with present invention; 
           [0038]      FIGS. 13A to 13C  are respectively front elevational, side elevational and bottom plan views of a fifth variant of an undercut wedge anchor in accordance with present invention; 
           [0039]      FIG. 14A  is a front elevational view of a spiral wedge anchor also in accordance with the present invention; 
           [0040]      FIG. 14B  is a variant of the spiral wedge anchor of  FIG. 14A ; 
           [0041]      FIG. 14C  is a top plan view of either anchor of  FIGS. 14A and 14B ; and 
           [0042]      FIG. 15  is a vertical cross sectional view showing the spiral anchor wedge of  FIG. 14A  in an expanded position within a hole defined in a support structure such that the anchor retains an object to this support structure. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A) Non-Slip Wedge Anchors (FIGS. 1 to 7) 
       [0043]    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. 
         [0044]      FIGS. 1A and 1B  illustrate a non-slip wedge anchor  10  in accordance with the present invention which is shown respectively in at rest and installed positions thereof. In  FIG. 1C , the anchor  10  is seen from its underside. The anchor  10  includes an expander member  12  and an expansion member  14 . The expander member  12  is designed to be inserted in a hole H defined in a support structure S, such as a concrete element, and comprises a treaded section  16  adapted to extend in the hole H while having a proximal end  18  which extends outside of the hole H such as to be engaged by a threaded female member, such as a nut N, with a washer W being herein shown between the nut N and the support structure S. Typically, an object, although not herein shown, is held by the anchor  10  to the support structure S; it is noted that, in the present embodiment, as well as in the other embodiments of the various anchors herein shown and described, such an object has not been illustrated. 
         [0045]    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  FIG. 1B , thereby anchoring the anchor  10  in the hole H. The expansion member includes a double-layered, folded over, proximal or trailing end  22  which defines an internal abutment shoulder  24  which can be engaged by an enlarged annular flange  26  provided distally of the flared end  20  of the expander member  12 . 
         [0046]    In  FIGS. 2A and 2B , a second wedge anchor  30  in accordance with present invention is illustrated and which comprises an expander member  32  (shown in detail in  FIGS. 3A and 3B ) and an expansion member  34  (shown in detail in  FIGS. 3C to 3E ), or expandable clip. The expander member  32  is similar to the expander member of  FIG. 1A  in that it includes a treaded section  36 , having a proximal end  38 , a leading flared end  40  and a reduced diameter intermediate cylindrical section  42  therebetween. A shoulder  44  is defined at a junction of the intermediate and threaded sections  42  and  36 . 
         [0047]    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  FIG. 2B , and defines thereat mating tongue and groove elements  54  and  56 , respectively. As seen in  FIGS. 2A and 2B , the leg  50  of the expansion member  34  is held captive in a groove  58  defined longitudinally in the flared end  40  (see  FIGS. 3A and 3B ) thereby preventing the expansion member  34  from rotating with respect to the expander member  32  and forcing it to work vertically without twisting. 
         [0048]    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. 
         [0049]    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  FIG. 2B ). Such an engagement with the hole H at a trailing end of the expandable member  34 , and with an angle opposed to that of the flared end  40 , is very secure and increases the force required to pull out the expanded anchor  30  from the support structure S. 
         [0050]    It is noted that the cylindrical intermediate section  42  allows the collar  48  to be received in a collapsed position (see  FIG. 2A ) when the anchor  30  is initially driven in the hole H. Also, the shoulder  44  prevents the expandable member  34  from moving up on the threaded section  36  of the expander member  32 . The tongue and groove elements  54  and  56  align the collar  48  at its split  52  to provide a peripheral, 360°-like, gripping of the expandable member  34  into the walls of the hole H. 
         [0051]    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 . 
         [0052]    In the following descriptions which pertain to variants of the anchor  30  of  FIGS. 2A and 2B , components which are identical in function and in structure to corresponding components of the anchor  30  bear the same references as in  FIGS. 2A to 3E , whereas similar parts have been attributed suffixes to their reference numerals with respect to the numerals used in  FIGS. 2A to 3E . Any components which are new to the anchors of the following variants are identified by new reference numerals. 
         [0053]    In  FIGS. 4A to 5E  and  6 A to  7 E, third and fourth wedge anchors  70  and  80 , respectively, also in accordance with present invention are illustrated. These anchors  70  and  80  are very similar to the anchor  30 , except that their respective expansion members  34   a  and  34   b  have respectively 2 and 3 legs  50   a  and  50   b,  respectively, as opposed to the single leg  50  embodied in the expansion member  34  of anchor  30 . The multiple splits  52   b  result in that the collar  48   b  includes three clip segments. 
         [0054]    The expansion member  34   b  of anchor  80  defines a pair of rounded radii  82  and  84  to increase the rigidity of the legs  50   b.    
         [0055]    Therefore, with respect to the anchor of FIGS.  6 A to  7 E′, 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. 
         [0056]    The stud ( FIGS. 7A and 7B ) is made of high strength steel which can be heat treated for heavy duty applications. The stud is unique in that it contains a number of features unlike conventional wedge type anchors. The stud is comprised of an external thread at one end which has a reduced diameter at the bottom end of the thread which engages the multi segmented clip. The difference in diameter prevents the clip from travelling upward onto the threads of the bolt. The end of the bolt opposite to the thread end has a flared section extending outward. The end of the flare incorporates several guide segments used to maintain the position of the expansion member as it expands during installation and is also used to prevent rotation of the total clip itself. At the very end of the flared section of the bolt is a radial flat section land to allow for maximum interference between the hole, stud and expansion clip. 
         [0057]    The expansion clip ( FIGS. 7C to 7E ) is made of high strength steel and is comprised of three formed segments which are pre-expanded prior to assembly. Each of the segments compresses against the hole in the concrete when driven into the hole providing frictional resistance to axial pullout during installation and after the load is applied. 
         [0058]    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/Function 
       [0059]    A 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. 
         [0060]    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  FIG. 6B ). The constant outward force provided by the upper section of the segments cause the clip segments to dig into or interfere with the concrete thus preventing the clip assembly from sliding or creeping upward which causes the bolt to loosen in the hole of the concrete. Once the installation torque is reached, the load can be applied to the bolt. 
       B) Undercut Wedge Anchor (FIGS. 8 to 13) 
       [0061]    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. 
         [0062]    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. 
         [0063]      FIGS. 8A and 8B  illustrate an undercut wedge anchor  100  in accordance with the present invention which is shown respectively in first and second positions thereof in a support. 
         [0064]    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. 
         [0065]    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. 
         [0066]    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 . 
         [0067]    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. 
         [0068]    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 . 
         [0069]    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/Function 
       [0070]    The anchor  100  is driven into the pre-drilled hole H until it is reaches its bottom (see  FIG. 8A ). A rotary drill with a hex drive socket attached is assembled to the external hex drive element  108 . To facilitate the undercut action, the installer forces the expander member  102  down by applying constant downward pressure thereon while it is spinning Once the expansion member  104  is frictionally engaged to the walls of the hole H, the further downward displacement of the expander member  102  causes the trailing flared section  112  to engage the expansion member  104  and forces the latter to expand radially outward (see  FIG. 8A ), such that the rotation of the expander member  102  resulting from it being connected to the rotary drill causes the expansion member  104  to rotate (as it connected at its tabs  128  and legs  120  to the trailing and leading recesses  130  and  132  of the expander member  102 ). The spinning of the expansion member  104  causes its trailing edge  136  to cut into the support structure S (e.g. of concrete), thus providing the initial undercut action. 
         [0071]    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  FIG. 8B ) in view of its memory, for instance resulting from the trailing edge  136  having been plastically deformed. As the expandable collar  116  remains stationary by virtue of the positive locking engagement of its trailing edge  136  with the walls of the hole H, the leading flared portion  110  causes the leading end of the collar  116  to expand outwardly (see  FIG. 8B ). The expansion member  104  is prevented from rotating by its legs  120  being laterally confined in the recesses  132  and being thus limited to relative longitudinal displacement therein. It is noted that the expandable collar  116  may be spring loaded or biased outwardly, i.e. to a partly open or deployed position, to ensure the initial frictional engagement thereof with the walls of the hole H. 
         [0072]    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  FIG. 8B ) thereby completing the setting of the undercut mechanism/expansion member  104 . 
         [0073]    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 . 
         [0074]    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. 
         [0075]      FIGS. 10A to 10D ,  11 A to  11 C,  12 A to  12 C and  13 A to  13 C show four variants of the undercut wedge anchor  100  wherein the expansion member  104  of  FIGS. 9E to 9G  has been modified, for instance at its formed end  114  and tabs  128  (with similar adjustments to the trailing recesses  130 ). 
         [0076]    In the present non-slip wedge anchors (see  FIGS. 1 to 7 ) and undercut wedge anchors (see  FIGS. 8 to 13 ), the expansion of the expansion member (see, for instance,  FIG. 7C  of the non-slip wedge anchor and  FIGS. 8B and 9E  of the undercut wedge anchor) results from that at least proximal or trailing edge thereof, i.e. and upper section of the expandable segments thereof, bites into or interferes with the peripheral concrete wall of a receiving hole thereby preventing the assembly from sliding or creeping upwards and cause the bolt to loosen in the hole defined in the concrete structure. This prevents axial removal of the anchor from the hole. By so expanding the expansion member, resistance to axial pullout is improved. The resiliency of the expansion member allows the anchor to be easily inserted in the hole while urging the same against the wall of the hole to prevent the expansion member from rotating as a torque is applied to a nut engaged to the bolt. The rotation of the nut causes the bolt to move translationally outwardly of the hole and thus causes a flared expander portion of the bolt to move axially into the stationary expansion member to expand the expansion member as per the way described hereinbefore. With respect to the non-slip wedge anchor, this is well illustrated in  FIG. 6B , and in the case of the undercut wedge anchor, this is well shown in  FIG. 8B . 
         [0077]    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. 
         [0078]    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) 
       [0079]      FIG. 14A  illustrates a spiral wedge anchor  200  having a stud or expander member  202  defining a spiral and tapered lower end  204  for receiving a resilient coil or expansion member  206  (e.g. made of hard steel) which, in view of the initial frictional engagement of the coil  206  with the wall of the hole H in the support structure S, climbs along the tapers of the lower stud end  204  as the stud  202  is pulled rotatably outwardly of the hole H, whereby the coil  206  is expanded outwardly radially for further contacting the hole H (as seen in  FIG. 15 ), being firmly wedged between the concrete S and the stud  202 . An object O can thus be firmly held to the support structure S. 
         [0080]    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  FIGS. 1B ,  2 B,  4 B,  6 B,  8 B and  15 ).