Abstract:
An expanding dowel rod structure for coaxially aligning at least 2 separate workpieces having circular apertures therein and/or securely attaching a boss in a circular aperture in a workpiece providing resistance to shearing is provided. The expanding dowel rod structure is comprised of a small number of easily machinable or obtainable pieces, is simple to insert and secure, automatically coaxially aligns the dowel rod structure in a circular aperture with generally even force across substantially all of the contacting surfaces thereof.

Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates generally to a method and apparatus for coaxially aligning at least 2 separate workpieces having circular apertures therein and/or securely attaching a boss in a circular aperture in a workpiece. 
       BACKGROUND 
       [0002]    Sometimes it is desired to align two structures (or more), such as workpieces, having circular apertures therein, coaxially, with a high degree of precision. Additionally, sometimes it is desired to be able to place a boss or protrusion, for various reasons, in a work piece securely and simply, using a device that is relatively cheap to produce. 
         [0003]    One attempt to resolve these issues in the past has included use of standard slotted pins. However, in some applications the shear force on the resulting dowel is too large for such an apparatus and method to be effective. More specifically, since standard slotted pins are generally hollow, they do not contain an inner core and thus are susceptible to shearing at relatively low loads. 
         [0004]    Another apparatus and method disclosed in the prior art is disclosed in U.S. Pat. No. 6,056,489 issued on May 2, 2000 to Keller (the “&#39;489 patent”). The &#39;489 patent discloses an expansion dowel for use in attaching members using a circular bore. Specifically, the &#39;489 patent discloses an expansion dowel including: a cylindrical, expandable dowel body having a plurality of axial slots opening at a front, in a setting direction, of the dowel body, and a bore which tapers in the setting direction in a region of the axial slots; an expansion sleeve arranged inside of the dowel body and tapering in the setting direction, the expansion sleeve having a conical tapering, in the setting direction; the bore having a plurality of slots extending in an axial direction; a plurality of projections projecting from an outer surface of the sleeve and adapted to displace in the axial slots of the dowel body; and an expansion member axially displaceable in the bore of the dowel body. 
         [0005]    While the expansion dowel of the &#39;489 patent may be useful for some applications, it does not serve a general utility for all applications. Specifically, the machined parts necessary to utilize the expansion dowel of the &#39;489 patent are very intricate in design and use, requiring significant machining to achieve. Furthermore, the expansion of the dowel sleeve disclosed in the &#39;489 patent is accomplished by the pounding of an expansion member by a worker. This expansion may be considered undesirable in many applications because the pounding of a hammer is generally not as precise a work movement as may be desired and may create undesirable and imprecise loads being placed on the workpieces in which the expansion dowel disclosed in the &#39;489 patent may be used. Additionally, the use of a hammer can sometimes result in damage to the workpieces themselves. For this reason, it may be desired to have an expanding dowel rod structure that is formed from relatively simple, easy to machine and/or obtain pieces for, which may be simply, easily and precisely used by a worker, which provides the desired force or load on the workpiece it is being used in, and which are not susceptible to shearing at relatively low loads. 
       SUMMARY 
       [0006]    In one aspect, the disclosure involves the use of an expanding dowel rod structure comprised of a dowel sleeve, an inner thrust retainer, and a bolt. More specifically, in an aspect of the disclosure, the thrust retainer is tapered to deform the expanding dowel sleeve in order that the deformation will interfere with and bear force on the bore of the workpieces that are being doweled. In an aspect disclosed herein, both the expanding dowel sleeve and the thrust retainer have tapered inner/outer faces, respectively, that mate, thus causing the desired expansion. As discussed above, the expanding dowel rod structure disclosed herein may be used in connection with workpieces having circular bores that need to be coaxially aligned and secured. In an aspect of the disclosure, in some applications, it may be desirable to be able to vary the force exerted on the bores of the dowel holes without varying the bore size itself, an aspect which may be accomplished by embodiments of the disclosure set forth herein. 
         [0007]    In yet another aspect of the disclosure, an expanding dowel rod structure is disclosed that can be used to securely add a boss to a workpiece having a circular bore therein, thus saving considerably in cost and simplicity over prior art methods of casting a relatively thick workpiece and machining it down to the desired boss height. More specifically, in such an aspect, the dowel sleeve disclosed herein may be placed in a circular bore with a desired portion sticking out of the bore. The bolt may then be tightened in the thrust retainer disclosed herein to a desired torque such that the force acts on the bore of the workpiece allowing the assembly to be rigid in the workpiece and act as a boss. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a partial cutaway isometric view showing an expanding dowel rod structure in accordance with the disclosure in both pre-use and in-use configurations; 
           [0009]      FIG. 2  is an overhead plan view of the expanding dowel rod structure of  FIG. 1  in an in-use (force loading) configuration; 
           [0010]      FIG. 3  is an overhead plan view of the expanding dowel rod structure of  FIG. 1  in a pre-use (non-force loading) configuration; 
           [0011]      FIG. 4  is an isometric view of a dowel sleeve in accordance with the expanding dowel rod structure shown in  FIG. 1 ; 
           [0012]      FIG. 5  is an isometric view of a thrust retainer in accordance with the expanding dowel rod structure shown in  FIG. 1 ; 
           [0013]      FIG. 6  is an isometric view of an alternate embodiment of a thrust retainer operable for use in connection with an expanding dowel rod structure disclosed herein; 
           [0014]      FIG. 7  is a full cutaway isometric view showing the expanding dowel rod structure of  FIG. 1 ; 
           [0015]      FIG. 8  is a partial cutaway, partial phantom isometric view showing the expanding dowel rod structure of  FIG. 1 ; and 
           [0016]      FIG. 9  is an isometric view showing an expanding dowel rod structure in accordance with an embodiment of the present disclosure being used to create a boss in a workpiece having a circular aperture therein. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    As shown best in  FIGS. 1 ,  7  and  8 , an expanding dowel rod structure  10  in accordance with an aspect of the disclosure is generally designated as reference numeral  10 . In accordance therewith, the dowel rod structure  10  may be formed by a dowel sleeve  16 , a thrust retainer  18  and a bolt  12 . The dowel sleeve  16  may have a cylindrical shape defining a circular outer face  11 , and include a shoulder  19  located on a top portion thereof and be provided with an axial bore that is tapered forming a dowel sleeve  16  tapered inner face  26 . Consistent with this aspect of the disclosure, the wide portion of the dowel sleeve  16  tapered inner face  26  is located at the bottom of the dowel sleeve  16  and tapers toward the narrow portion of the dowel sleeve  16  tapered inner face  26  located proximate a top portion of the dowel sleeve  16 . Additionally, the dowel sleeve  16  may preferably include a slot  20  formed on an axial side thereof and which may protrude radially therethrough. In an aspect of the disclosure, the slot  20  imparts to the dowel sleeve  16  the flexibility which is necessary for expansion of the dowel sleeve  16  to occur. In an aspect consistent with the present disclosure, the slot  20  extends the entire length of the dowel sleeve  16  in order to allow uniform expansion of the dowel sleeve  16  by the thrust retainer  18 . 
         [0018]    Consistent with an aspect of the disclosure, the thrust retainer  18  includes a tapered outer face  24 , an axial inner bore  25  having inner threads  30  therein, and a nub  22  on an outer portion thereof. In an aspect of the disclosure, the thrust retainer  18  may include a band portion  21  located on a bottom portion thereof, the band portion  21  being defined by a face having a constant radius. Also in an aspect of the disclosure, the nub  22  may be wedge-shaped in order to facilitate the engagement of the nub  22  within the slot  20  while preventing the nub  22  from sticking out of the slot  20  and thus interfering with the placement of the dowel rod structure  10  in a bore  34  of workpieces  32  in which the dowel rod structure  10  is being utilized. Consistent with this aspect of the disclosure, the nub  22  may be located on or above said band  21  on the tapered outer face  24  on the thrust retainer  18 . Also consistent with the disclosure, the tapered outer face  24  of the thrust retainer  18  may be provided with a taper angle similar or identical to the taper of the tapered inner face  26  of dowel sleeve  16 . Consistent with an aspect of the disclosure the shape of the tapered outer face  24  of the thrust retainer  18  and the tapered inner face  26  of the dowel sleeve  16  may be conical or pyramidal. 
         [0019]    Consistent with an aspect of the disclosure, the bolt  12  may be comprised of a head  13  and shank  15 , and may preferably include a washer  14  positioned under the head  13  and outer threads  28  positioned on the shank  15  of bolt  12 . The washer  14  may be a separate element or may be machined integrally with the head  13  as is known to those of ordinary skill in the art. Conversely, the head  13  may be large enough to preclude the need for a washer  14 . The important aspect of the size of the head  13  and/or washer  14  being that the head  13  or washer  14  should be large enough that an underside thereof may sufficiently engage the shoulder  19  of the dowel sleeve  16  when the expanding dowel rod structure  10  disclosed herein is in use. 
         [0020]    In an aspect consistent with the disclosure, the thrust retainer  18  inner threads  30  are preferably shaped to mate with the outer threads  28  of bolt  12 . Further, in an aspect of the disclosed embodiment, the nub  22  is shaped to be received in slot  20  of dowel sleeve  16  to prevent relative rotational movement between the thrust retainer  18  and the dowel sleeve  16  when the dowel rod structure  10  is being tightened. 
         [0021]    As shown in  FIGS. 1 ,  3 ,  6 ,  7 ,  8  and  9  and as discussed above, the expanding dowel rod structure  10  components may be loosely assembled before being placed in bore  34  in workpieces  32  for expansion. Specifically, the top portion of thrust retainer  18  may be placed in the bottom portion of the dowel sleeve  16  by aligning the slot  20  with the nub  22 . Next bolt  12  may be loosely placed in the axial inner bore  25  of the thrust retainer  18  thereby capturing the shoulder  19  of dowel sleeve  16  between the underside either of the head  13  of the bolt  12  or the underside of washer  14  and the thrust retainer  18 . At this time, bolt  12  head  13  may be turned sufficiently so that just the first few threads  28  of bolt  12  engage the inner threads  30  of the axial inner bore  25  of the thrust retainer  18  thereby capturing the dowel sleeve  16  without expanding it significantly. 
         [0022]    As can be seen in  FIG. 3 , at this time there is no force being exerted by the dowel rod structure  10  against the bore(s)  34  of workpiece(s)  32  as this initial “loose” construction does not cause the tapered outer face  24  of the thrust retainer  18  to press up and against tapered inner face  26  of dowel sleeve  16  and thus does not cause significant expansion of dowel sleeve  16  at this time. As such, the dowel rod structure  10  comprised of the dowel sleeve  16 , thrust retainer  18 , and bolt  12  may be placed in the bores  34  of the workpieces  32  (as shown in  FIGS. 1 ,  3 ,  6  and  7 ) or, in the case of creating a boss (as shown best in  FIG. 8 ), in the bore  34  of a single workpiece  32  while in the initial “loose” configuration. 
         [0023]    Next, consistent with the use of the dowel rod structure  10  as disclosed herein, the bolt  12  head  13  may be tightened to provide the desired expansion of the dowel sleeve  16  and thus be anchored into the work piece(s)  32 . Specifically, the head  13  of the bolt  12  (shown herein as a hex head, but which could be of practically any configuration as is known by those of ordinary skill in the art), could begin being torqued by an operator. Caused thereby, the thrust retainer  18  tapered outer face  24  is driven up and into the similarly-shaped dowel sleeve  16  tapered inner face  26  causing dowel sleeve  16  to expand radially, and generally evenly, across the entire outer face  11  of dowel sleeve  16 . More specifically, upon application of a load by torqueing of bolt  12 , the underside of head  13  or washer  14  engages shoulder  19  of dowel sleeve  16  causing axial relative displacement of the thrust retainer  18  into the dowel sleeve  16 . The interaction of tapered outer face  24  of thrust retainer  18  and tapered inner face  26  of dowel sleeve  16  as thrust retainer  18  is pulled upwardly by bolt  12  results in generally uniform expansion of the dowel sleeve  16  outer face  11 . Upon expansion of the sleeve  16  radially, as shown best in  FIG. 2 , the outer face  11  of the dowel sleeve  16  is pressed into the bore(s)  34  and frictionally engages it/them. The operator may continue torqueing head  13  of bolt  12  to a desired and/or pre-determined torque level until the desired expansion of dowel sleeve  16  has been reached. 
         [0024]    It should be noted that the taper of the inner face  26  of the dowel sleeve  16  need not exactly match the taper of the outer face  24  of the thrust retainer  18  and may be determined in order to provide the desired amount of pressure and displacement of the dowel sleeve  16  depending on the desired application. It should also be noted that the disclosure of the present invention is useful in that the force exerted by the dowel sleeve  16  outer face  11  on the bore(s)  34  may be relatively precisely controlled, compared with some prior art “hammer” methods, by specifying an exact torque to be applied to bolt  12  head  13  by an operator. Further, as discussed above, and as shown best in  FIG. 8 , the expanding dowel rod structure  10  disclosed herein can be used to add a boss to a workpiece  32 . Specifically, rather than tying two (or more) workpieces  32  together, the expanding dowel rod structure  10  can simply be placed in a bore  34  of a single workpiece  32  and expanded as disclosed herein to form the desired boss. 
         [0025]    Consistent with an aspect of the disclosure as disclosed herein, the angle of the outer face  24  of the thrust retainer  18  (and thus the corresponding angles of the inner face  26  of the dowel sleeve  16 ) may vary greatly depending on the geometries and engineering requirements, limitations, tolerances, etc. that are faced for the application in which the expanding dowel rod structure  10  disclosed herein is used. Similarly, the shape, size, length, threading, etc., of the bolt  12  may vary as well. And, in accordance therewith, the exact width, composition, etc., of the dowel sleeve  16 , thrust retainer  18 , and bolt  12  may vary greatly based upon the same variables discussed above as would be recognizable to a person of ordinary skill in the art. 
         [0026]    Accordingly, it should be understood that the disclosure does not require any specific size, tolerance, material of manufacture, etc., for the dowel sleeve  16 , thrust retainer  18 , or any other piece, part, component disclosed herein. However, consistent with the embodiment disclosed herein, the angle of the outer face  24  of the thrust retainer  18  may be about 10 degrees and the angle of the inner face  26  of the dowel sleeve  16  may be similar thereto. A ¾ inch bolt would be operable in accordance with the disclosure and the components disclosed herein could be made of any operable material including carbon steel, such as 0.48-0.66% Carbon, heat treated, 45-55 HRC. 
       INDUSTRIAL APPLICABILITY 
       [0027]    The disclosed expanding dowel rod structure  10  is useful for coaxially aligning and securing at least 2 separate workpieces  32  having circular apertures or bores  34  therein and/or for securely attaching a boss in a circular aperture in a workpiece  32 . Additionally, the disclosed dowel rod structure  10  may be used in almost any application where, for example, add-on parts must be added to and/or secured to workpieces  32  using a through-assembly, and which require, or could utilize, anchorable attachment devices. Non-limiting examples of uses and/or applications in which the dowel rod structure  10  disclosed herein could be used include almost any application where traditional slotted pins and/or coiled spring pins may have been used in the past. Such applications include, but are not limited to: automotive; manufacturing; locomotive; aeronautical; industrial; building; et al. applications. More specifically, the apparatus disclosed herein may be used in applications wherein it is needed to secure two (or more) workpieces  32  together utilizing circular bores  34  in the workpieces  32 , and particularly, wherein it is desired to use an attachment device that is resistant to shear forces in such applications. 
         [0028]    More specifically, it is noted that the use of the dowel rod structure  10  in accordance with the disclosure containing the thrust retainer  18  element as disclosed herein provides significant mass and a core to the dowel sleeve  16  that makes the dowel rod structure  10  of the present disclosure resistant to shearing at relatively low loads. This is particularly useful when the dowel rod structure  10  disclosed herein is used to coaxially secure two or more workpieces  32  through bores  34  as the shear forces against the dowel rod structure  10  in such applications can be relatively high, particularly depending on the applications in which the workpieces  32  are being used. 
         [0029]    Further, consistent with aspects of the disclosure, the dowel rod structure  10  disclosed herein may be used in applications wherein it is desired to use a securing structure that may be formed relatively easily and simply from readily available and relatively inexpensive materials. Additionally, the dowel rod structure  10  disclosed herein is particularly useful in securing two or more workpieces  32 , or providing a boss to a single workpiece  32 , when it is desired to control the force being exerted against the bores  34  of the workpiece(s)  32  with some degree of precision. 
         [0030]    It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed dowel rod structure  10  disclosed herein without departing from the scope of the disclosure. Other embodiments of the dowel rod structure  10  may be apparent to those skilled in the art from consideration of the specification disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.