Abstract:
A method of securing a bolt to a concrete structure without the necessity of turning the bolt during the installation process. A first set of hardware is provided for use during the forming and casting phases of creating the concrete structure. The first set of hardware is used to embed a bolt retainer in the finished cast concrete with a passage leading from the bolt retainer to the exterior of the cast concrete. A bolt is then placed in this passage and a portion of the bolt is driven through the bolt retainer to secure it.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     MICROFICHE APPENDIX 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of construction. More specifically the invention comprises a method for securing a bolt in concrete and hardware for carrying out the method. 
     2. Description of the Related Art 
     It is often desirable to attach hardware to a cast concrete structure.  FIG. 1  shows a sectional elevation view of one example. Clip  16  needs to be affixed to surface  12  of concrete  10 . Bolt  14  is used to anchor clip  16  in place. The bolt must generally be screwed into a threaded insert that is retained within the concrete. There are two generally accepted methods for securing the insert within the concrete. The first method is to simply place the insert into the form and pour the concrete around it (using appropriate guards to prevent the concrete from flowing into unwanted areas such as the threads). The second approach is to install the insert after the concrete has hardened. In the latter approach, a hole is drilled into the concrete and the insert is secured in the hole by friction, through the use of an adhesive, or often a combination of the two. 
     In either approach, a bolt must be threaded into the insert and turned to draw it tight. The necessity of turning the bolt presents a problem in some circumstances. One of these is illustrated in  FIG. 1 . 
     Clip  16  is typically an extruded aluminum piece which can be placed over the head  25  of a bolt  14  as shown. One channel in the clip attaches to the bolt and the opposite channel (on the right side in the orientation shown in the view) is used to receive a long rectangular rail. From the vantage point depicted in  FIG. 1 , the rail would extend into and out of the page at a right angle. 
     Such clips are typically used to attach a long rail to 10 or more bolts spaced at something like four foot intervals. Clips  16  may be connected to the bolts fairly easily. However, the contractor is then forced to slide a very long rail through a series of clips—an unwieldy process at best. It would be preferable to feed the clips onto the rail before it is attached to the concrete, then offer the rail assembly up to the concrete with the clips and bolts attached and fasten the bolts into the concrete. Of course, in this arrangement, it would not be possible to turn the bolts. The bolts have to be fastened by driving them inward rather than turning a threaded engagement. 
     The reader will thereby appreciate that the prior art methods of securing a bolt—as illustrated by the example of FIG.  1 —do not work well for some items that need to be attached to a concrete structure. The reader should also appreciate the fact that the example given is not unique. Many types of hardware entail the same installation difficulties as the assembly of a long rail to clips  16 . Thus, it would be advantageous to provide a method of securing a bolt to concrete that does not require the turning of the bolt. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention comprises a method of securing a bolt to a concrete structure without the necessity of turning the bolt during the installation process. A first set of hardware is provided for use during the forming and casting phases of creating the concrete structure. The first set of hardware includes a flanged tube, a bolt retainer, and a domed cap. The bolt retainer is a disk including a central through hole. The bolt retainer has an inward facing side (facing the interior of the concrete structure) and an outward facing side. It is sandwiched between the flanged tube and the domed cap. This assembly is then secured to a concrete form using a separate installation bolt, which is passed through the interior of the flanged tube, through the central through hole in the bolt retainer, and threaded into a threaded hole in the domed cap. 
     Concrete is then poured around the assembly and allowed to harden. The flanged tube prevents concrete from covering the outward facing side of the bolt retainer. The domed cap prevents concrete from covering the inward facing side of the bolt retainer. Once the concrete has hardened, the installation bolt is removed. 
     The result is a smooth access passage through the concrete to the outward facing side of the bolt retainer. The domed cap provides a cavity on the inward facing side of the bolt retainer. An anchor bolt is fed into the smooth access passage. The through hole in the bolt retainer is smaller in diameter than the major threads on the anchor bolt. The anchor bolts driven through the through hole in the bolt retainer by forcing it into the concrete structure (rather than by turning). The mechanical interference between the threads on the anchor bolt and the through hole in the bolt retainer then retain the bolt in place. Surface relief features are preferably provided on the bolt retainer proximate the through hole. These allow the material proximate the through hole to more easily deflect in order to allow the passage of the anchor bolt. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a sectional elevation view, showing a prior art clip affixed to a concrete surface by a bolt. 
         FIG. 2  is a perspective view, showing the bolt retainer. 
         FIG. 3  is a plan view, showing the bolt retainer. 
         FIG. 4  is a sectional view, showing the bolt retainer. 
         FIG. 4B  is a sectional elevation view, showing the through hole of the bolt retainer. 
         FIG. 5  is a perspective view, showing the domed cap. 
         FIG. 6  is a sectional elevation view, showing the domed cap. 
         FIG. 7  is a perspective view, showing the flanged tube. 
         FIG. 8  is a sectional elevation view, showing the flanged tube. 
         FIG. 9  is an elevation view, showing the installation bolt. 
         FIG. 10  is an elevation view with a partial section, showing an alternate embodiment of the installation bolt. 
         FIG. 11  is an elevation view, showing the anchor bolt. 
         FIG. 12  is a sectional elevation view, showing an assembly of the domed cap, the bolt retainer, and the flanged tube. 
         FIG. 13  is a sectional elevation view, showing the assembly of  FIG. 12  placed into a concrete form and secured by an installation bolt, with the concrete poured around the assembly. 
         FIG. 14  is a sectional elevation view, showing the assembly of  FIG. 13  after the concrete has hardened and the installation bolt has been removed. 
         FIG. 15  is a sectional elevation view, showing an anchor bolt installed using the present inventive method and hardware. 
     
    
    
     REFERENCE NUMERALS IN THE DRAWINGS 
     
         
         
           
               10  concrete 
               12  surface 
               14  bolt 
               16  clip 
               18  bolt retainer 
               20  bearing face 
               22  through hole 
               24  central axis 
               25  head 
               26  angled perimeter 
               28  retaining edge 
               29  slot 
               30  domed cap 
               32  threaded hole 
               34  dome wall 
               36  cavity 
               38  flanged tube 
               40  bore 
               42  inner flange 
               44  tube 
               46  outer flange 
               48  flange 
               50  threaded portion 
               52  enlarged portion 
               54  unthreaded portion 
               56  alternate installation bolt 
               58  sleeve 
               60  anchor bolt 
               61  threaded portion 
               62  cap retainer 
               64  concrete form 
               65  washer 
               66  form hole 
           
         
       
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention employs an assembly of components to properly locate a bolt retainer within a cast concrete structure. Bolt retainer  18  is shown in  FIG. 2 . The embodiment shown is round, but other shapes may be used as well. Each side of the bolt retainer preferably has a large bearing face  20  to evenly distribute the loads placed by this component on the concrete. A central passage through the bolt retainer is provided. In the embodiment shown the central passage assumes the form of through hole  22 . 
       FIG. 3  shows a plan view of bolt retainer  18 .  FIG. 4  is a sectional view taken through the center of the bolt retainer. The embodiment shown is radially symmetric about central axis  24 . Angled perimeter is provided around through hole  22 . If the first side of the bolt retainer is on the right in  FIG. 4  and the second side is on the left, then angled perimeter  26  protrudes outward from the second side. It preferably includes a retaining edge  28 . Retaining edge  28  defines the smallest part of the passage through the bolt retainer. In the circular embodiment shown, it has a diameter D 3 . 
     Angled perimeter  26  and retaining edge  28  are configured to allow an anchor bolt to be driven through the bolt retainer from right to left in the perspective shown in the view. However, the angled perimeter and retaining edge will prevent the bolt being pulled back out to the right. The engagement between the angled perimeter and an anchor bolt will be described in more detail subsequently, but those skilled in the art will immediately perceive that angled perimeter  26  must deflect somewhat to allow the passage of an anchor bolt which is large enough to bear against retaining edge  28 . 
       FIG. 4A  is a perspective view showing the second side of bolt retainer  18  (from which angled perimeter  26  protrudes. Stress-relieving features are preferably added to allow the angled perimeter to more easily deflect. In the embodiment shown, a plurality of radial slots  29  is provided. These convert the angled perimeter into a radial array of inwardly extending “fingers.” 
     The rest of the components used in the installation process will now be described.  FIG. 5  shows domed cap  30 .  FIG. 6  shows this component in a sectional elevation view. The embodiment illustrated is radially symmetric about central axis  24 . Dome wall  34  creates an open end (to the right in the view) of the cap and a closed end (to the left in the view). Threaded hole  32  passes through the closed end. The outer wall in this embodiment has a diameter “D 2 .” The interior of the cap is hollow, forming cavity  36 . 
       FIG. 7  shows flanged tube  38 . Tube  44  includes an inner flange  42  and an outer flange  46 . Bore  40  passes completely through from the inner flange to the outer flange. It is preferable to have the flanges extend outward a significant distance in order to provide large bearing surfaces. However, those skilled in the art will realize that a tube having sufficient wall thickness could be used without any outwardly extending flanges. In such an embodiment, the inner and outer flanges would simply be the ends of the tubes. 
       FIG. 8  shows a sectional elevation view through the flanged tube of  FIG. 7 . The embodiment shown is radially symmetric about central axis  24 . Inner flange  42  preferably has an outer diameter “D 2 ” to match the outer diameter of the cap. Bore  40  has a diameter “D 5 .” 
       FIG. 9  shows installation bolt  48 . It contains a conventional head  25  connected to a shaft. The shaft includes enlarged portion  52 , which has diameter “D 1 .” D 1  is preferably made slightly smaller than D 5  so that the enlarged portion is a close sliding fit within bore  40  of tube  44 . Unthreaded portion  54  is preferably of a smaller diameter. Threaded portion  50  has a major diameter “D 4 .” D 4  is made small enough to pass through the passage through bolt retainer  18  without interfering with retaining edge  28 . In other words, D 4  is made smaller than D 3 . Threaded portion  50  is also preferably sized to thread into threaded hole  32  in domed cap  30 . 
       FIG. 10  shows alternate installation bolt  56 . In this embodiment, the enlarged portion is created by slipping sleeve  58  (shown sectioned) over the unthreaded portion of a conventional bolt. This may represent a cost savings as the embodiment of  FIG. 9  would likely be a “custom” manufacturing job. Whichever embodiment is used, the function is the same. 
     Finally,  FIG. 11  shows anchor bolt  60 . This is a conventional bolt which will be locked into bolt retainer  18  using the inventive method and other components. Threaded portion  61  has a major diameter “D 6 ” which is large enough to engage retaining edge  28  of angled perimeter  26 . In other words, D 6  is made larger than D 3 . D 6  is preferably also made slightly smaller than D 5 . 
     The process for carrying out the inventive method will now be described in detail. The components described previously are intended to align and fit together.  FIG. 12  shows an assembly of domed cap  30 , bolt retainer  18 , and flanged tube  38 . All the components are aligned with central axis  24 . In the embodiment shown, the bolt retainer is sandwiched between the domed cap and the flanged tube. 
     It is preferable to provide alignment features to facilitate proper alignment. Cap retainer  62  may be provided for this purpose. It encloses the open end of the domed cap to properly locate it. The outer diameter of bolt retainer  18  is sized to slide inside cap retainer  62 . Thus, the cap retainer aids in the alignment of all three components shown. While cap retainer  62  is shown as an integral feature of flanged tube  62 , it may be made as a separate piece as well. The cap retainer may also be configured to hold the cap in place during assembly, thereby simplifying things for the user. 
     It is preferable to make the installation bolt a close sliding fit inside the flanged tube. This will ensure the correct alignment of domed cap  30  with the other components. Thus, the cap retainer is not really necessary to the function of the invention. It is an optional feature which may be omitted entirely. 
     Those skilled in the art will know that concrete structures are typically made by creating a hollow form and pouring liquid concrete into the form. After the concrete hardens, the form is removed. Forms are typically made of wood or metal panels.  FIG. 13  is a sectional elevation view showing concrete form  64 . The portion shown is only one wall, and there will typically be several walls bounding the volume into which the concrete is to be poured. 
     Concrete form  64  has a form hole  66  passing through it. Installation bolt  48  is passed through this form hole, with the head  25  and washer  65  lying against the outward facing side of the concrete form. The assembly of  FIG. 12  is then slid along the inward facing portion of the installation bolt until threaded portion  50  engages threaded hole  32  in domed cap  30 . The bolt is then turned so that the threaded engagement draws domed cap toward concrete form  64 . Once the installation bolt is tightened, the configuration shown in  FIG. 13  will result. 
     The flanged tube, bolt retainer, and domed cap may be installed one at a time onto the installation bolt, or they may be assembled as groups of two or more parts. Those skilled in the art will know that many different mechanical engagement features could be substituted for the threaded engagement depicted between the installation bolt and the domed cap. For example, the hole through the domed cap could simply be an enlarged through hole. A washer and nut could then be secured on the exposed threaded portion  50  protruding beyond the through hole. 
     The assembly is tightened in the position shown before concrete is poured around it. The first side of bolt retainer  18  is covered by flanged tube  38 . The second side of the bolt retainer (facing to the left as shown in the view), is protected by the domed cap, which creates cavity  36 . 
     Liquid concrete is then poured into the form. Concrete  10  will harden around the assembly as shown in  FIG. 13 . After the concrete is set, the user removes installation bolt  48  by turning it to disengage threaded portion  50  and pulling it out. Once the installation bolt is removed, the configuration of  FIG. 14  results. Dome wall  34  creates cavity  36  on the second side of bolt retainer  18 . Flanged tube  38  provides access to the first side of the bolt retainer through bore  40 . 
     Turning now to  FIG. 5 , anchor bolt  60  can be installed by driving threaded portion  61  through the engagement features located on the passage through bolt retainer  18 . Returning briefly to  FIG. 4B , the reader will recall the geometry surrounding through hole  22 . Those skilled in the art will readily appreciate that a bolt can be selected so that the major diameter of its threads will interfere with retaining edge  28 . This bolt could then be forced past retaining edge  28 , since angled perimeter  26  will naturally deflect to allow travel of the bolt in the first direction (which would be upward in the orientation shown in  FIG. 4B ). However, those skilled in the art will also readily appreciate that the angled perimeter would tend to prevent the bolt being pulled back in the opposite direction (downward in the orientation shown in  FIG. 4B ). Thus, the retaining feature or features provided on the perimeter of through hole  22  will allow an anchor bolt to be driven into the concrete structure, but not pulled back out. 
     Returning now to  FIG. 15 , the reader will appreciate that several assemblies such as depicted can be spaced on a line in a concrete structure. The anchor bolts  60  can then be driven into the bolt retainers and secured without having to turn the anchor bolts. 
     It is desirable in some circumstances to permit the removal of anchor bolt  60  by rotating it so that its threads will back it out of bolt retainer  18 . In the assembly shown in  FIG. 15 , the bolt retainer may break free from the surrounding concrete and then begin to rotate with the rotating bolt—making removal impossible. In this instance it is desirable to provide features to prevent the rotation of the bolt retainer. Mechanical interlocking features can be provided to lock the bolt retainer to the domed cap, the flanged tube, or both. A toothed engagement between the components is one example of such a feature. 
     In addition, the surfaces of the bolt retainer, the domed cap, and/or, the flanged tube which contact the surrounding concrete can be provided with perturbations which tend to lock these surfaces to the concrete. Any of these approaches would serve to arrest the rotation of the bolt retainer. 
     Many variations on the embodiment shown will be apparent to those skilled in the art. It is convenient to use an anchor bolt having conventional helical threads—since these are widely available. However, one could use an anchor bolt having a series of ribs instead. One could also—in some circumstances having minimal pull-out forces—use an anchor bolt having just a smooth exterior. 
     The preceding description contains significant detail regarding the novel aspects of the present invention. It should not be construed, however, as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. Thus, the scope of the invention should be fixed by the following claims, rather than by the examples given.