Patent Document

FIELD OF THE INVENTION 
   The present invention relates to an integrated joint assembly fastener for immovably securing two adjoining parts together along mating surfaces thereof. More particular, but not exclusively, the fastener assembly of the present invention is for use in fastening flat furniture board pieces together whereby an article of furniture can be quickly and securely assembled and relatively easy to disassemble, if required. 
   BACKGROUND OF THE INVENTION 
   Fastening devices of the type disclosed in the present application are exemplified, for example, by U.S. Pat. No. 4,693,630 and German Patent 2 546,526. In the U.S. patent there is described a fastening device for releasable interconnection of panels and wherein a pair of resilient projecting clamping arms extend out of a cylindrical housing mounted adjacent a straight edge of one panel whereby to be received in a bore formed in an adjacent panel to be connected thereto. The clamping arms form part of a resilient unitary spring member with the arms being separated to an engaged position by rotating a cam to force them against a wedge. Accordingly, the clamping arms expand and grip into the sidewalls of the bore. When it is necessary to release the clamping arms from the bore one has to rely on the restoring force of the spring element. A disadvantage of this type of a fastening device is that due to metal fatigue and due to the force of engagement of the spring, it may be difficult to release the clamping arms from the sidewall of the bore when one needs to disassemble the panels. The disassembly usually results in damaging the inner sidewall of the bore and accordingly it is no longer possible to reengage the clamping arms to reconnect the panels and the entire piece of furniture that is formed by these panels can no longer be assembled with the fastening devices. Furthermore, the manufacturing of such a fastener is expensive due to machining and assembly. It can also be said that it is unreliable. 
   German Patent 2 546 526 teaches a similar type connector and wherein a split dowel head with gripping head sections project from the housing and is actuated to a gripping position by driving a wedge therebetween. Various types of mechanisms are disclosed for actuating the wedge to cause the gripping head to open. Again, the problem with this type of connector is that it poses difficulty in disengaging the head if adjoining panels need to be disconnected. The problem of damaging the sidewalls of the bore in attempting to disconnect the members also poses another serious problem, as above described. 
   SUMMARY OF THE INVENTION 
   It is a feature of the present invention to provide a fastener assembly for releasably securing two adjoining parts together along flat mating surfaces and which substantially overcomes the above-mentioned disadvantages of the prior art. 
   Another feature of the present invention is to provide a fastener assembly of the above type which uses die-cast parts, which are easy to assemble, easy to actuate and which can be positively disengaged prior to the withdrawal of the dowel head from the connecting hole. 
   Another feature of the present invention is to provide a joint fastener of the above type which is capable of releasably securing two adjoining parts under tension to provide a rigid securement of the parts in flat facial relationship. 
   Another feature of the present invention is to provide a fastener assembly of the above type and wherein the rotatable, screw-like element, provides a wedging action when the dowel head is subjected to tension caused by a turning force applied against the interconnected parts. 
   According to the above features, from a broad aspect, the present provides a fastener assembly for releasably securing two adjoining parts along flat mating surfaces thereof. The fastener assembly comprises a housing having an off-center bore, of circular cross-section, extending from a top wall of the housing. An opening is provided in a rear sidewall of the housing leading to the bore. A rotatable element having a circular sidewall is disposed in close rotational fit in the bore. Means is provided to maintain said rotatable element in said bore. An offset connecting post projects from a lower end of the rotatable element and disposed adjacent the opening when the rotatable element is in the bore. Stationary wedge means project from the front sidewall at a predetermined location adjacent the opening. The fastener assembly is characterized in that a pair of connecting dowel head sections project from the opening and have an engageable end for attachment with the offset connecting post. The dowel head sections have a gripping head section at a free end thereof and an inclined abutment formation for sliding engagement against the wedge means when the dowel head sections are axially displaced by the offset connecting post when the rotatable element is rotated in a predetermined direction to retract the dowel head sections to cause their inclined formations to be displaced against the wedge means and urging the respective gripping head sections outwardly laterally to an engaging position. When the gripping head sections are engaged, and the rotatable element is rotated in opposite direction, it forces the gripping head sections to move forward to a loose disengaged position thereby disconnecting the two adjoining parts from the sidewall of the hole. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiments of the present invention will now be described with reference to the accompanying drawings in which 
       FIG. 1  is a fragmented perspective view showing the fastener assembly of the present invention secured within a flat edge of a board piece whereby to secure an adjacent board piece along the edge by means of a connecting dowel engageable in a hole formed in a flat wall of the adjoining board piece; 
       FIG. 2  is an enlarged side view showing the gripping head sections of the dowel head engaged in the dowel head hole of the adjacent part; 
       FIG. 3  is a fragmented view showing the position of the board pieces prior to being interconnected together along flat mating surfaces and by the use of a tool for rotating a rotatable element which causes engagement of the dowel head; 
       FIG. 4A  is a perspective view showing the construction of the housing; 
       FIG. 4   b  is a different perspective view showing the construction of the housing; 
       FIG. 5  is a top view of the housing; 
       FIG. 6  is a side view of the housing; 
       FIG. 7  is a further rear side view of the housing; 
       FIG. 8  is a perspective top view of the rotatable element; 
       FIG. 9  is a further side perspective view of the rotatable element; 
       FIG. 10  is a cross-section view of the rotatable element; 
       FIG. 11  is a bottom view of the rotatable element; 
       FIG. 12A  is a perspective view as viewed from an outer side of a dowel head sections; 
       FIG. 12B  is a perspective view, as viewed from an inside of the dowel head section; 
       FIG. 13  is an outside side view of the dowel head section; 
       FIG. 14  is a top view of the dowel head section as viewed from the inside surface; 
       FIG. 15  is an outside view of the dowel head section opposite to  FIG. 13 ; 
       FIG. 16  is an underside view of a dowel head section as viewed from the outside surface; 
       FIG. 17  is a fragmented partly sectional side view showing the fastener assembly in an assembled condition; and 
       FIG. 18  is a bottom view of the fastener assembly showing the dowel head sections with their engageable end being retracted by the offset connecting post and the position of the gripping head sections as the rotatable element is rotated towards its engaging position. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring now to the drawings and more particularly to  FIG. 1  there is shown generally at  10  the fastener assembly of the present invention for releasably securing two adjoining parts, herein a flat panel  11  and a transverse vertical panel  12  together along flat mating surfaces  11 ′ and  12 ′. The fastener assembly comprises a housing  13  which is press-fitted within a bore  14  adjacent the flat edge  11 ′ of the bore. 
   The housing  13  has a bore  15  of circular cross-section for receiving in close rotational fit therein a rotatable element  16 . The rotatable element  16  is provided on its top face  37  with tool engaging means in the form of a Phillips head cavity  17  whereby to be rotated by a screw driver  18 , as shown in  FIG. 3 . Rotation of the rotatable element along a predetermined direction causes a dowel head assembly  18  to engage within the dowel head hole  19  formed in the inner flat wall  12 ′ of the adjoining part  12  and draw the two panels together at their mating surfaces whereby to secure the two parts together. 
   Referring now to  FIGS. 2 and 3 , it can be seen that in order to secure the two parts together their flat mating surfaces  11 ′ and  12 ′ are positioned one adjacent to the other with the dowel head assembly  18  being positioned within the dowel head hole  19 . By inserting the screw driver head  18  into the cavity  17  of the rotatable element, the element is rotated and the gripping head sections  20 , one only being shown in  FIG. 3 , are caused to engage within the inner sidewall  19 ′ of the dowel head hole  19  while at the same time applying a pulling force in the direction of arrow  21  to hold the connected part under tension, as will be described in detail later on. 
   With reference now to  FIGS. 4A to 7  there will be described the construction of the housing  13 . As hereinshown the housing as a circular sidewall  22  and an opening, in the form of a rectangular transverse slot  23  is formed adjacent a bottom end  24  of the housing. The bore  15  is hereinshown as a through bore but this is not essential as the bottom end  24  of the bore could have a solid wall. Also, the slot  23  is shown as being formed on opposed diametrical sides of the circular sidewall  22 , as depicted by reference numeral  23 ′, and this is also not essential but it is essential that the slot  23  be disposed transverse to the central longitudinal axis  25  and extend on opposed sides of a flat outer wall section  26  formed within the circular sidewall  22  of the housing and for positioning in the plane of the flat mating surface  11 ′ of the part  11  in which the housing is secured. 
   Stationary wedge means in the form of a pair of wedge arms  27  and  27 ′ extend respectively from opposed sides of the slot  23 , as shown in  FIG. 6 , and project in alignment parallel to one another in a common plane on an axis  28  which is offset from the central longitudinal axis  25  of the through bore  15 , as illustrated in  FIG. 5 . The reason for this will be described later. Each wedge arm  27  and  27 ′ has a wedge shaped free end  29  and is of a predetermined length. 
   As can be seen in  FIG. 1  the housing may have a flat top wall  30 . When boring a hole in wood this could cause chipping in the veneer surface  31  about the bore. In order to conceal any of this chipping it is preferable that a flat transverse flange  32  extend about the bore  15 . The flange is provided with a straight edge  33  coextending with the flat outer wall  26  as better seen in  FIG. 5 . Indicator means in the form of an arrow symbol  34  is stamped in the top wall of the flange  32  to indicate the direction of rotation of the rotatable element to place the dowel head assembly  18  in an engaged position. The flange  32  is also provided with a symbol  35  on one side of the bore  15  and a further symbol  36  on the other side. The rotatable element  16  is also provided with a position indicator mark  37 , as shown in  FIG. 1 , on a top face thereof whereby when this position indicator mark is adjacent the symbol  35  it indicates that the dowel head assembly is not engaged. When the indicator mark is closer to the mark  36  this indicates that the bolt is engaged. To engage the dowel head assembly, the rotatable element  16  is rotated along an arc of approximately 120° to 160° and this distance of rotation depends on the dowel head hole diameter and the type of material the dowel head is engaged into. If the material is hard, it requires less rotation to engage the dowel head. 
   The housing  13  is further provided with opposed projecting axial ribs  38  to prevent rotation of the housing  13  when force fitted in the locating bore  14  formed in the surface  11 ″ and to increase the pulling force and surface against the member  11 . As shown in  FIG. 1  this locating bore  14  extends partly into the flat side edge  11 ′ whereby the flat outer wall section  26  of the housing lies flush with the flat side edge  11 ′ with the wedge arms  27  and  27 ′ and dowel head assembly  18  projecting therefrom. 
   A plurality of gripping ribs  39  are also disposed along the axial ribs  38  which are formed on opposed sides of the sidewall on a transverse diametrical axis of the housing bore  15 . These gripping ribs  39  resist against an outward and upward pulling force exerted on the housing when forces are applied against the adjacent board or part  12  tending to push the housing upwards. Furthermore, a lower outer circumferential wall section of the housing is provided with one or more circumferential wedge formations  40  to again resist against this outward pulling force which may be exerted on the housing. 
   With reference now to  FIGS. 8   10   11  there will be described the construction of the rotatable element  16 . As hereinshown the rotatable element has a circular sidewall  41  for close rotational fit in the bore  15  of the housing  13 . An offset connecting post  42  projects form a lower end  43  of the rotatable element and when fitted into the bore  15  this offset connecting post  42  is disposed adjacent the rectangular slot  23 . The circumferential sidewall  41  is further provided with a circumferential channel  44  whereby to retain the rotatable element captive in the housing  13 , at a predetermined position, by a rib  45  which is punched into a thin sidewall portion  46  of the housing as shown in  FIGS. 7 and 4B . This assembly can be done automatically on a jig and the rib is punched from the outside surface  47  of the insidewall portion  46  as shown in  FIG. 4B . 
   As can be seen from  FIG. 10  the tool engaging formation  17 , herein a Phillips cavity is substantially large whereby a screw driver head  18 , as shown in  FIG. 2 , can engage the rotatable element from an angle thereof due to the fact that the housing is secured in a corner of adjoining interconnected pieces, such as pieces  11  and  12  as illustrated in  FIG. 2 . Of course, the tool engaging formation  17  can have any shape to engage any type of special tool. It could also be an Alan key engaging formation which could be of smaller size as such keys can easily access tight areas from above. 
   The rotation element  16  is further provided with wedging flat sidewall sections  48  which are provided in a circular sidewall and disposed at 90° interval form the position indicator mark  37  to further provide improved wedging of the rotational element  16  when the screw is rotated to a dowel head engaged position. The tension exerted on the bolt, in the direction of arrow  21 , as shown in  FIG. 3 , would be resisted by these wedging flat sidewall sections  48  which are in close fit against the inner sidewall  49  of the bore  15  as illustrated in  FIG. 17 . The wedging flat sidewall sections prevent the rotatable element from disengaging or unscrewing due to tension or vibration. The material surrounding the dowel head hole will destroy before the rotatable element unscrews from its locked position. 
   With reference now to  FIGS. 12A to 16  there will be described the construction of the dowel head assembly  18 . The dowel head assembly is comprised of a pair of connecting dowel head sections  50 , one of these sections being clearly illustrated by  FIGS. 12A to 16 . As hereinshown the dowel head sections  50  have a gripping head  51  at a free end thereof and an engageable end  52  at an opposed end. The dowel head section  50  is a cast section and the engageable end  52  is constituted by a flat ring formation  53  having a through bore  54  for engagement about the offset connecting post  42  of the rotatable element  16 . The flat ring formation merges into the gripping head  51  via a flat connecting body portion  55 . 
   As better seen in  FIGS. 13 to 16  the gripping head  51  is of substantially semi-circular cross-section and defines an arcuate outer wall  56  and a flat inner wall  57 . The head is provided with gripping ribs  58  in the arcuate outer wall  56 . The ribs  58  have a rearwardly sloped front wall  59  and a flat rear wall  60  whereby to define a sharp pointed outer gripping edge  61  to penetrate the sidewall of the bore  19 . 
   An inclined abutment formation is defined by a sloped inner wall portion  62  disposed in a base of the head and extending to the flat inner wall  57  of the head section. The sloped inner wall position  62  extends on both sides of the outer surfaces  55 ′ of the body position  55  and is adapted to lie on the sloped walls  29 ′ of the wedge shaped free end  29  of the wedge arms  27  when two of these dowel head sections  50  are interconnected together about the offset connecting post  42  and project out of the rectangular slot  23  formed in the sidewall of the housing with the gripping head sections  51  located on a respective side of the wedge arms  27  and  27 ′ as more clearly illustrated in  FIG. 18 . As shown in  FIG. 18  the gripping head may be provided with one or two gripping ribs  58 . Also, the ribs  58  may have different sizes depending on their intended use which is particularly dictated by the hardness of the material that the connecting parts are formed of. 
   The gripping head  51  of each pair of connecting dowel head sections  50  is disposed on a respective side of a central longitudinal axis  56  of the dowel head sections  50  whereby the flat ring formations  53  of each dowel head section  50  of a pair of dowel head sections can be disposed in facial contact on a contact face  53 ′ thereof, see  FIG. 17 . The flat ring formations  53  are disposed about the offset connecting post  42  with the gripping head sections  51  lying on a respective side of the wedge arms  27  as clearly illustrated in  FIG. 18 . 
   Each of the flat connecting body portions  55  are provided with an abutment flange  65  projecting outwardly from an edge and extending above the contact face  53 ′ at a predetermined position to arrest an edge, herein edge  66  of the other flat connecting body when the pair of flat connecting body are disposed in facial contact whereby to restrict the angular outer displacement of the gripping head sections  51  and the rotation of the rotatable element  16  or the displacement of the connecting post  42  away from the transverse slot  23  when rotated in the direction of arrow symbol  34 . As shown in  FIG. 18  which is a bottom view of the housing, when the offset connecting post  42  is displaced away from the slot  23  it will exert a pulling force on the flat ring formations  53  thereby drawing the gripping head sections  51  and  51 ′ against the stationary wedge arms  27  and  27 ′. Because the offset post is rotated in one direction which is offset from the central rotational axis  75  of the rotational element  16 , the head formations  51  will be angulated, as hereinshown, with gripping head  51 ′ being pulled further in then gripping head  51  as its flat ring formation  53  will be acted upon by the post  42  before the ring of the other dowel head section but will straighten out as the center axis  67  of the offset connecting post  42  comes closer to the plane  68  of the central axis  75  of the rotatable element  16 . 
   As the rotatable element  16  is rotated and retracts the gripping head sections  51  and  51 ′, the sloped inner wall portions  62  of the gripping head sections cause the gripping heads  51  to separate and move outwardly of one another due to their sliding engagement with the slope walls  29 ′ of the stationary wedge arms  27  and  27 ′ thereby forcing the pointed outer gripping edge  61  of the gripping ribs  58  into the inner sidewall  19 ′ of the dowel head hole  19 , as shown in  FIG. 3 . The gripping ribs pull the flat mating surface  12 ′ of the part  12  against the flat mating surface  11 ′ of the part  11  and places the dowel head sections  50  under tension due to the pulling force exerted in the direction of arrow  21 , as shown in  FIG. 3 . The flat wedge sections  48  of the rotatable element solidly and frictionally engage the inner sidewall of the housing bore  15  providing a wedging action to prevent the rotatable element from being rotatably displaced by the pulling force of the dowel head or by added tension caused by the application of a force against either of the adjoining connected parts  11  and  12 . 
   Although the two adjoining parts  11  and  12  illustrated in the drawings are wooden boards, such as laminated chip or sawdust boards with laminated surfaces, it is to be understood that the fastener assembly may be utilized for fastening various types of elements together having flat mating surfaces. The boards could also be fabricated from certain plastics material. As previously described, depending on the material used the gripping ribs in the head formations may be modified to adapt to such material. In the particular embodiment described the wood pieces are flat boards which are connected at right angles against flat side edges thereof to fabricate furniture pieces. All of the parts forming the fastener assembly are zinc cast metal parts and various types of other metals or materials could be used. It is also conceivable that the fastener may be injection molded from structural plastic materials and again depending on its intended use. It is therefore within the ambit of the present invention to cover any obvious modifications of the preferred embodiment described herein, provided such modifications fall within the scope of the appended claims.

Technology Category: 4