Abstract:
Disclosed is a post anchor ( 1 ) comprising two final sections ( 11, 12 ), one ( 11 ) of which can be introduced into a post ( 10 ) while the other one ( 12 ) is used for fixing the anchor ( 1 ) to or in another element. The section ( 11 ) that can be introduced into the post represents a drill bit section ( 11 ) which is used for introducing a bore ( 20 ) into the post ( 10 ) in a substantially stress-free manner. The drill bit section ( 11 ) in the bore ( 20 ) is provided with essentially no axial clearance and is preferably embodied as a screw bit. The drill bit section ( 11 ) has a first smaller drill core diameter ( 31 ) in a first zone ( 31 ) bordering the tip thereof while having a larger drill core diameter ( 32 ) in a second zone ( 32 ) located closer to the other section ( 12 ) in the longitudinal direction thereof ( 13 ).

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a post having a post anchor connected with the post and comprising two end sections, where one section extends into the post and the other section is intended for fastening on or in another element. 
       BACKGROUND OF THE INVENTION 
       [0002]    A post anchor of this type is known from the prior art, for example, from DE 36 34 266. In that document, a screw-in threaded rod is adhesively bonded in a corresponding drillhole in a post, a longitudinal groove being provided on the threaded rod so that the glue can accordingly be allowed to enter the drillhole between the threaded rod and the wall of the drillhole. 
         [0003]    Another post anchor is known from DE 199 12 815, in which a threaded spike is provided on a plate which can be placed against the underside of a post, this threaded spike penetrating the post during positioning of the post anchor. Provided on the opposite side of the post anchor is a sleeve with an internal thread so that an anchor bar can be subsequently screwed in outside of the post. 
         [0004]    In all the proposals of the prior art, even when the threaded rods are glued in, there is a problem in terms of the parallelism of the post anchor and post. This means that the post anchor does not usually have its center axis lying exactly parallel to the longitudinal axis of the post. This is an unwanted property of such a system and a disadvantage when assembling such post anchor systems on building sites. 
         [0005]    In practice, the unit consisting of threaded rod and post is therefore not, as in DE 199 12 815, put together once on the building site; instead, this takes place beforehand so that the parallelism can be achieved to the greatest possible degree under industrial production conditions. 
         [0006]    Moreover, the connection of metal anchors in wooden posts usually leaves something to be desired in terms of the force required to extract the anchors, for example. 
       SUMMARY OF THE INVENTION 
       [0007]    Taking this prior art as a starting point, the object on which the invention is based is to provide a post anchor of the type mentioned in the beginning which has better parallelism and in which the fixing is, moreover, better secured against twisting. 
         [0008]    In an embodiment of the present invention a post includes a post anchor connected with the post and includes two end sections, where one section extends into the post and the other section is intended for fastening on or in another element, wherein the post includes a drillhole, wherein one section is a drill bit section, having in a first segment, adjacent to its tip, a smaller drilling core diameter and having in a second segment, arranged nearer to the other section, a larger drilling core diameter, wherein the drillhole has substantially no radial play with the drill bit section for arranging the section introduced in the post in the drillhole in the post in a substantially stress-free manner. 
         [0009]    In another embodiment of the present invention, a post anchor includes two end sections, where one section can be introduced into a post and the other section is intended for fastening on or in another element, wherein the section which can be introduced into the post is a drill bit section for making a drillhole in the post in a substantially stress-free manner, which drillhole has substantially no radial play with the drill bit section, characterized in that the drill bit section has in a first segment, in the longitudinal direction adjacent to its tip, a smaller drilling core diameter and in a second segment, arranged nearer to the other section, a larger drilling core diameter. 
         [0010]    In yet another embodiment of the present invention, a method includes introducing a post anchor into a post, characterized in that it includes the following steps: (a) 
         [0011]    drilling a drillhole in the post with the drill bit section ( 11 ) of the post anchor, (b) introducing adhesive into the drillhole with the drill bit section inserted so as to take up, by filling, any remaining radial play and the axial play of the drill bit section in the drillhole, or, alternatively, withdrawing the drill bit section, introducing adhesive into the drillhole and reinserting the drill bit section into the at least partially adhesive-filled drillhole. 
         [0012]    This object is achieved with a post having a post anchor connected with the post and comprising two end sections, where one section extends into the post and the other section is intended for fastening on or in another element, wherein the post comprises a drillhole, wherein one section is a drill bit section, having in a first segment, adjacent to its tip, a smaller drilling core diameter and having in a second segment, arranged nearer to the other section, a larger drilling core diameter, wherein the drillhole has substantially no radial play with the drill bit section for arranging the section introduced in the post in the drillhole in the post in a substantially stress-free manner. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0013]      FIG. 1  is a perspective view of a post according to an embodiment of the present invention 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    The invention will now be described in more detail with the aid of an exemplary embodiment with reference to the drawing. The single drawing shows a partly sectioned perspective view of a post together with an inserted post entrance. 
         [0015]    The reference number  1  is used to denote a post. The post  1  is made of wood and has a square cross section. Of course, the cross section may also be shaped differently, being for example round or elliptical, rectangular or polygonal. The material of the post  1  may also be chosen from another material only if these materials are similar to wood within the context given below. The similarity in question is in particular important for plastic materials. 
         [0016]    Said post  1  has a longitudinal axis whose orientation here is indicated by the arrow  2  running parallel to it. The post  1  can be fastened on a wall or floor surface (not shown in the FIGURE) with the aid of a post anchor (anchor  10  for short) according to the invention. The FIGURE shows one moment during the production of the connection between anchor  10  and post  1  when the anchor  10  has not yet been fully sunk in the post  1 . 
         [0017]    The anchor  10  is preferably constructed in one piece and as such comprises at least two different regions  11  and  12 . The first region  11  is made up of an auger bit, this region  11  being intended to be set into the post  1 . The second region  12  can be designed according to the particular application of the post anchor; in particular it may thus be a threaded rod section. This threaded rod section  12 , either by itself or by way of a further section (not shown in the drawing), can be positively connected to a drive, for example a drilling machine, to enable the auger bit  11  to be driven into the post  1 . 
         [0018]    The FIGURE shows, in dotted form, the outlines of a drillhole  20  in which the auger bit section  11  has already been advanced more than halfway. Instead of using an auger bit which allows chips cut out of the post to be lifted out, use may also be made of any other drill bit which makes possible the production of a stress-free bore, in particular in wood, in which there is no radial play. Radial play here is to be understood as meaning the distance  21  between the outside of the drill bit  11  and the inner wall of the bore  20 . 
         [0019]    The auger bit  11  extracts chips from the drillhole  20  and at the same time creates a certain free space in the axial direction, i.e., along the longitudinal axis  13  of the anchor  10 , into which free space an adhesive can be passed in through the upper opening  22  of the bore  20  once the drill bit section  11  has been fully inserted. Particularly advantageous adhesives are epoxy resin-based adhesives and polyurethanes. Before the adhesive is introduced, the anchor  10  may preferably be rotated back by an eight to a half of a rotation in order to make it easier to pass in the adhesive. Alternatively, it may be completely withdrawn, the adhesive poured in and the drill bit reinserted. 
         [0020]    A drill bit according to the prior art only supports its own weight and forces are solely applied in the longitudinal direction, i.e., along the axis  13 . The post anchor  10  here receives the bearing pressure. This is true for the threaded rod section  12  as well as for the drill bit section  11 . Therefore the drill bit section  11  according to the invention is divided into two different segments, having received the reference numerals  41  and  42 . The two segments are made in one piece. The drill bit section  11  has first drilling core diameter or central core  31 , followed by a central segment  42  of the drill bit  11 , having a second core diameter  32 , being larger than the diameter of the first drilling core diameter  31 . 
         [0021]    In a preferred embodiment the first drilling core diameter  31  is set between one fourth to one half of the external diameter of the drill bit  11 . The second drilling core diameter  32  is set between one half and ⅘ of the external diameter of the drill bit  11 . This creates between the two segments  41  and  42  a discontinuity between the diameters of the drilling cores  31  and  32 , respectively. The ratio between the axial length of the areas  41  and  42  can be, e.g., between 1:4 and 1:1 preferably around 1:2 for achieving a larger stiffness of the post anchor  10  without impeding the extraction of the chips due to a larger core drill diameter. 
         [0022]    Instead of two segments  41  and  42  it is also possible to provide three segments, wherein the smallest core drill diameter has a value of one fourth, the second central core drill diameter has a value of one half and the third largest core drill diameter has a value of ¾ of the external diameter of the drill bit  11 . It is of course possible to choose different transitions and a higher number of segments. 
         [0023]    Additionally it is possible to use a continuously enlarging drill core for achieving a steady growth of stiffness of the anchor  10  in direction of arrow  2 . 
         [0024]    The threaded rod section  12  comprises two different elements, the threaded rod as such and the drill chuck support. The threaded rod section  12  and the drill chuck support can be positioned one behind the other on an axis  13 , but it is also possible to adapt the side surface of the threaded rod section  12 , e.g., providing a groove, to create a drill chuck support within this section. 
         [0025]    At location  33  the drill head has a slightly larger diameter then the drill core  34 . 
         [0026]    The drill bit according to the invention ensures axially correct fitting, allowing the anchor  10  to be well centered in the post  1 . The prior art according to DE 199 12 815 employing the spike results in a displacement of the material of the post  1  and thus in stresses therein. The auger bit  10  produces a stress-free bore in wood and other comparable materials. 
         [0027]    The length of the anchor  10  depends on its field of application. For a post  1  having a diameter or cross-sectional dimensions of from 5 to 10 centimeters, given a diameter of the auger bit  11  of between 6 and 10 millimeters, a customary total length of the anchor may be between 10 and 70 centimeters. Preferably, this length is divided in half between the drill bit part  11  and the threaded rod part  12 . Of course, it is also possible for the threaded rod  12  or the auger bit  11  to be shorter or longer than the respective other section. It is also possible to provide a connection element (not shown in the drawing) between the auger bit  11  and the threaded rod  12  (or a flat rod without a thread). This may be an outer hexagonal section or a disc which is oriented radially with respect to the longitudinal axis. 
         [0028]    The anchor  10  according to this invention provides a simple, very secure anchor device which is able to be centered and which is correctly aligned axially, this anchor device  10  being driven into the post  1  beforehand within a storage area or during the production of said post. Alternatively, the post anchor  10  may be set into the posts  1  provided on a building site once on site. 
         [0029]    The diameter of the drill bit section  11  of the post anchor  10  can be chosen between 5 and 18 millimeters and the total length of the post anchor  10  can be chosen between 10 and 100 centimeters, wherein said length is preferably divided equally between the drill bit section  11  and the other section  12 . 
         [0030]    The scope of protection is in no way intended to be limited by the preceding description showing an exemplary embodiment and shall apply only to the claims which follow.