Abstract:
Interlocking clips are provided to assemble structures without the need for conventional fasteners. Structures such as fences, which may be assembled in situ, include the cooperating clips designed to provide a controlled amount of “play” between the pickets and rails of the fence to enable adjustment when racking the fences to accommodate sloping terrain. The clips are provided to interlock rails to cross members. The clips are preferably formed of a single sheet of a springy metallic material. The clips may be advantageously used to couple other types of apparatus.

Description:
FIELD OF INVENTION 
     The present invention relates to components for forming assemblies such as interlocked fence structures in situ and more particularly to components configured to interlock to form structures, such as fences assembled in situ and which are configured to interlock without the need for conventional fasteners. 
     BACKGROUND 
     Efforts to simplify assembly and in situ installation of fences and the like are well known. In addition to efforts to achieve simplification and ease of assembly of in situ installations, designs have been developed to eliminate the need for conventional fasteners which add to the labor intensive aspects of assembly and installation and further detract from the esthetics of completed fence installations. For example, see U.S. Pat. Nos. 5,660,378, 6,375,166 and DES 573,019. 
     U.S. Pat. No. 6,375,166, although eliminating the need for conventional fasteners, nevertheless requires tedious and time consuming piercing operations at the installation site. Somewhat similar piercing operations are required in U.S. Pat. No. 5,660,378. 
     In addition, the embodiments described therein lack the adjustability features necessary during racking of fences in that they lack the ability to provide adjustable positioning of the fence components relative to one another to accommodate a sloping terrain, while at the same time, providing rugged, rattle-free and structurally strong fence assemblies while permitting several degrees of relative movement of the components, while eliminating the need for conventional fasteners. 
     SUMMARY 
     It is therefore an object of the embodiments described herein to provide components configured to provide ease of in situ assembly and installation of components which provide a rugged, rattle-free structure without the need for conventional fasteners. 
     The fence of one embodiment utilizes clips having an insertion portion initially inserted into an opening in a picket and a wing-like portion for engaging a face of the picket adjacent to the opening. The picket, with the clip mounted thereto, and aligned at an angle to the longitudinal axis of the picket, is inserted into a region between opposing sides of a channel-shaped rail so that the top of the picket extends through an opening in the web of the channel-shaped rail. The wing-like portion of each clip has a pair of integral, flexible “wings” extending outwardly on opposite sides of the substantially U-shaped insertion portion that extends into an opening arranged along one surface of the picket. The wings are caused to undergo flexing due to being pressed between the picket and an integral, inwardly directed flange provided art an end of one sidewall of the rail. The wings move partially towards their normal, unflexed state as they pass the aforesaid flange but nevertheless remained flexed due to the limited space between the picket and the interior of the adjacent sidewall of the rail. The clip wings firmly presses the picket against the opposite interior wall of the rail assuring a rugged, rattle-free assembly, providing a superior holding force to lock the three components into place. The interior of the opposite sidewall of the channel-shaped member is preferably provided with a pair of projections which are pressed against the adjacent sidewall of the picket and serve to properly align and orient the picket so as to be substantially parallel to the rail, in cooperation with the aforesaid flexed wings. The integral outer edges of the clip wings are curved to enable relative movement between rail and the picket in a clockwise or counter-clockwise direction about a central axis of the picket opening receiving the clip projecting portion to facilitate alignment of the picket relative to the rail, for example, during racking, to accommodate a sloping terrain. 
     The opening in the web of the channel-shaped member has a length which is slightly greater than the thickness of the picket measured in the direction of the length of the opening in the web to provide a second range of movement of the picket relative to the rail to provide still further relative movement between these two components to further facilitate their adjustment and alignment, especially during racking. 
     The clip is preferably made of a suitable springy metal which flexes during insertion into the rail and exerts a strong spring force on the rail, creating a frictional locking force that maintains linear spacing of the picket with respect to the rail, which frictional force may, however, does not impede a racking operation. 
     Opposite edges of the clip wings are of a length measured in the direction of the longitudinal axis of the picket, which is substantially equal to the distance between a supporting surface of the inwardly directed flange and the interior surface of the web of the rail, trapping the clip between these two surfaces, to prevent disengagement of the rail, clip and picket, and to firmly secure the clip to the picket due to the sides of the U-shaped projection being flexed toward one another, by configuring the distance between the sides of the picket opening to be less than the distance between the sides of the U-shaped projection when unflexed. 
     In one clip embodiment, the wings bend over on themselves to form a substantially “R” shaped configuration, whereby the free ends of the wings press against the interior surface of the rail, providing the force for locking the picket and rail together. 
     In another embodiment, the clip, which is also preferably formed of a springy metallic material, is utilized for joining larger size rails and pickets. The central portion of the clip is inserted into an opening in the picket at an angle in a manner similar to the first embodiment. A pair of integral wings are joined to a U-shaped projection at the center of the clip. The wings each have curved end portions bent upwardly in the direction of the projection. The sides of the U-shaped projection are pressed together as the projection is forced into the picket opening. The clip of the second embodiment is likewise oriented at an angle to the longitudinal axis of the picket to clear the integral flange at one end of the adjacent sidewall of the rail. Once clear of the flange, the clip realigns itself with the picket, whereby the bent end portions of the wings press against the interior sidewall of the rail firmly locking the picket and rail to one another. Similar to the first embodiment, the distance between the outermost opposite edges of the integral curved wings is substantially equal to the distance between the inwardly directed integral flange of the rail and the interior surface of the yoke, serving as a positive stop to lock the clip into the rail. The outwardly bent portions of the wings partially snap back toward their normal unflexed state as they pass the flange on the rail. The clip firmly secures the picket to the rail. The sides of the projection portion of the clip configured for insertion into an opening in the picket are bent to substantially form a V-shape. The vertexes of the V-shaped projection extends into the interior of the opening in the picket to aid in retaining the clip in place in the picket. 
     In still another clip embodiment, the wings are joined to the V-shaped portion configured for insertion into an opening in a picket. Inner ends of the wings are integrally joined to the V-shaped projection portion and extend downwardly and away from the V-shaped projection, each forming a first V-shaped bend forming an angle of greater than 90 degrees with the adjacent side of the V-shaped projection portion. The inner ends are bent a spaced distance away from the first V-shaped bend to form a second V-shaped configuration having a vertex which is a given distance below the vertex of the first V-shaped bend. The outer ends of the wings are bent to form a curve about midway over their length and each define an outer section which extends over its associated inner end and curves upwardly and away from its associated inner end. The distance between the tips of the outer ends of the wings and the vertex at the second V-shaped configuration is chosen to accommodate picket and rail designs which create larger gap spaces between a sidewall of the picket and the interior surface of an adjacent sidewall in the rail. In order to accommodate a given gap space created by the pickets and rails used in a given installation, the angle of the first V-shaped bend may be made larger and/or the length of the curved outer ends of the wings may be increased to increase the distance between the vertex of the second V-shaped bend and tip of the adjacent outer end of the wing. 
     Although the above embodiments set forth applications for picket fences, other applications such as ladders and other structural members may utilize the design of the aforesaid embodiment to great advantage. 
     The embodiments described above are preferably formed from a single sheet of a springy metallic material, which is cut, machined or otherwise stamped from the sheet and then bent to form the yieldable central, U-shaped projection having a pair of outwardly extending yieldable wings. The springy material is chosen to provide a superior spring force which is able to retain the picket, rail and clip locked together. As an alternative, the clips of any of the embodiments herein may be produced by molding them from a suitable plastic/resin. The assembly can be performed with ease and eliminates the need for conventional fasteners. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments and objectives of the present invention will be best understood from a consideration of the detailed description and drawings in which: 
         FIGS. 1A and 1B  are perspective views of one embodiment of the present invention viewed from two different angles. 
         FIG. 1C  is a top view of the clip in  FIG. 1A . 
         FIG. 1D  is a view of the clip of  FIGS. 1A and 1B  looking in the direction of arrows  1 D- 1 D in  FIG. 1C . 
         FIG. 1E  is a view of the clip of  FIGS. 1A and 1B  looking in the direction of arrows  1 E- 1 E in  FIG. 1C . 
         FIG. 1F  is a view of the clip of  FIGS. 1A and 1B  looking in the direction of arrows  1 F- 1 F in  FIG. 1C . 
         FIG. 1G  is a view of the clip of  FIGS. 1A and 1B  looking in the direction of arrows  1 G- 1 G in  FIG. 1C . 
         FIGS. 1H and 1I  are plan views showing the manner in which the clip in  FIG. 1A  is produced. 
         FIGS. 1J ,  1 K and  1 L respectively are front elevational, bottom and left-side elevational views of a clip which is a modified version of the clip of  FIGS. 1A-1I . 
         FIG. 1M  is a plan view showing the clip of  FIGS. 1J-1L  before being formed into its final configuration. 
         FIGS. 2A-2D  are perspective views showing another embodiment of the clip of the present invention viewed from various angles. 
         FIG. 2E  is a top view of the clip of  FIG. 2A . 
         FIG. 2F  is a view of the embodiment of  FIGS. 2A-2D  looking in the direction of arrows  2 F- 2 F in  FIG. 2E . 
         FIG. 2G  is a left-side view of the clip of  FIGS. 2A-2D  looking in the direction of arrows  2 G- 2 G of  FIG. 2F . 
         FIG. 2H  is a right-hand view of the clip of  FIGS. 2A-2D  looking in the direction of arrows  2 H- 2 H in  FIG. 2F . 
         FIG. 2I  is a bottom view of the clip of  FIGS. 2A-2D . 
         FIG. 2J  is a view of the clip of  FIGS. 2A-2D  looking in the direction of arrows  2 J- 2 J of  FIG. 2B . 
         FIGS. 2K ,  2 L,  2 M and  2 N are plan views showing the manner in which the clip of  FIG. 2H  is produced. 
         FIGS. 3A and 3B  are exploded perspective views showing the manner in which a picket is assembled to a rail employing the clip embodiment of  FIG. 1A . 
         FIG. 3C  is a sectional view of the assembly of  FIG. 3A  looking in the direction of arrows  3 C- 3 C. 
         FIG. 3D  is a sectional view of the assembly of  FIG. 3A  looking in the direction of arrows  3 D- 3 D. 
         FIG. 4  is an exploded perspective view showing the manner in which a picket is assembled to a rail employing the clip embodiment of  FIG. 2A . 
         FIG. 5  is a plan view showing a fence installation of the present invention on a sloping terrain to facilitate an understanding of “racking”. 
         FIG. 6A  is an exploded perspective view of a fence showing the manner in which multiple clips and rails are mounted to pickets. 
         FIG. 6B  is a sectional view of the fence of  FIG. 6A  taken through one of the pickets. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1A-1G  show the first clip embodiment  10 , which is preferably cut or stamped out of a single sheet of a metallic material having the requisite flexibility and springiness which is, for example, stainless steel. The clip is then bent so that the central portion  10   a  of clip  10  has a substantially U-shaped configuration defined by curved portion  10   b  and sides  10   c  and  10   d  integrally joined to curved portion  10   b . The free ends of the sides  10   c  and  10   d  are respectively bent outwardly and away from the central axis A to provide a pair of wings  10   g  and  10   h  extending outwardly away from one another. Wings  10   g  and  10   h  are then bent at  10   i  and  10   j  to form smoothly curved portions  10   i  and  10   j , the wings  10   g  and  10   h  being further bent at  10   k  and  10   l  providing free ends  10   m  and  10   n  which, in  FIG. 1C  can be seen to form an acute angle with the main wing portions  10   g  and  10   h.    
     The curved portions  10   q - 10   p  of main wing portion  10   g  and the curved portions  10   r  and  10   s  of main wing portion  10   h  are equidistant from an imaginary center C so that the distance measured along an imaginary diameter is substantially constant and equal to a distance D 1 , which design feature will be best understood in consideration of the assembled components, i.e., the assembled picket, rail and cooperating clip, as described below. 
     As was set forth above, the springy metallic clip  10  has the capability of flexing due to the application of force and of returning to its unflexed state upon removal of such force. For example, sides  10   c  and  10   d  of the curved portion  10   a  of clip  10  are designed and configured to flex and move towards one another upon the application of an appropriate force. Similarly, free ends  10   m  and  10   n  will flex and thereby move toward main wing portions  10   g  and  10   h  upon the application of an appropriate force and will likewise return to their relaxed state upon the removal of the said force. 
     In one preferred method for producing clips  10 , a clip pattern P 10  is stamped or otherwise cut from a flat sheet S 10  of a springy metallic material, such as stainless steel, as shown in  FIG. 1H , to provide the planar clip P 10 . The planar clip P 10  is then bent around suitable forming tools to form the desired curvatures at regions R 1 -R 6 , the related curvatures resulting from the bending operations being shown in  FIG. 1I . 
       FIGS. 1J ,  1 K and  1 L show a clip embodiment  10 ′ which is a modification of clip  10 , like portions of clip  10  and clip  10 ′ being identified by like numerals except that portions in  FIGS. 1J-1L  are identified with primes. The angle Ω′ formed between clip portions  10   c ′- 10   g ′ and  10   d ′- 10   h ′ are greater than the angle Ω′ formed between clip portions  10   c - 10   g  and  10   d - 10   h  of clip  10 . The wings of clip  10 ′ are bent to provide vertices  10   t ′- 10   u ′ and the outer ends  10   k ′- 10   l ′ are curved upwardly from curved portions  10   i ′- 10   j ′ of clip  10 ′. It can be seen from a comparison of clips  10  and  10 ′ that the distance D measured from the vertices  10   t ′- 10   u ′ to their associated free ends  10   v - 10   w  is greater than the distances measured from the free ends of the portions  10   k - 10   l  to the portions  10   g - 10   h  of clip  10 , enabling the employment of clip  10 ′ in installations using pickets and rails that create a larger gap space in the region which receives the clip. The distance D can be adjusted by adjusting one or more of: the angle Ω′; the length of clip portions  10   k ′- 10   l ′ and the location of vertices along clip portions  10   g ′- 10   h′.    
     The clip embodiment  10 ′ may be manufactured in a manner similar to the clips  10  and  20 .  FIG. 1M  shows the clip  10 ′ after it has been stamped or cut out of a flat sheet of springy metallic material. The clip is then bent into the proper shape as shown in  FIGS. 1J-1L  employing suitable forming tools. 
       FIG. 3A  is an exploded perspective view of the clip of  FIGS. 1A-1G  showing the manner in which the clip mounts between a rail and a picket. The exploded assembly  100  comprises a channel-shaped mid-rail  120  having a web portion  120   a  and two (2) integral sidewalls  120   b ,  120   c . Sidewall  120   b  has an integral alignment rib  120   d  extending along the length of sidewall  120   b . Sidewall  120   c  has an integral, inwardly directed flange  120   e  along the bottom free end of sidewall  120   c . An opening  120   f  is provided in web portion  120   a  of rail  120 , which conforms to the rectangular, cross-sectional shape of the picket (preferably although not necessarily rectangular). 
     Picket  110  is a hollow, rectangular-shaped, elongated member defined by four (4) sidewalls  110   a ,  110   b ,  110   c  and  110   d . Sidewall  110   a  is provided with an opening  110   e  for receiving the substantially U-shaped projection  10   a  of clip  10 . The dimensional relationship of opening  110   e  relative to the substantially U-shaped projection  10   a  is such that the curved tip is substantially free to enter opening  110   e  and, as the U-shaped projection  10   a  is pressed into the opening, the gradually increased spacing between sides  10   c  and  10   d  in the unstressed state becomes greater than the width of opening  110   e  in the horizontal direction, causing the sides  10   c  and  10   d  of the flexible clip to be pressed toward one another and undergo flexing. 
     Clip  10 , after being at least partially inserted into opening  110   e , is oriented at an angle θ to surface  110   a  of picket  110  as shown in  FIGS. 3B and 3D . Clip  10  is oriented at an angle θ to bring the upward edges  10   q ,  10   r  into engagement with surface  110   a  of picket  110 . 
     The upper end of picket  110  is placed between sidewalls  120   b ,  120   c  of central rail  120  and moved upwardly in the direction shown by arrow A so that the upper end of picket  120  enters into opening  120   f  and moves further in the direction A relative to the rail  120 . It should be understood that the picket may be held stationary and the rail moved downwardly relative to the picket or both picket and rail may be moved during this assembly. There is sufficient clearance between picket surface  110   a  and the free end of flange  120   e  to move the tips  10   q ,  10   r  of clip  10  into the gap region G to enable the clip to be moved upward together with picket  110 . Before the picket  110  enters into gap G, the tips T 1 , T 2  of the free ends  10   m ,  10   n  of clip  10  (Note, also  FIG. 1G ) rest against surface  110   a  of picket  110  and are substantially in the relaxed, i.e., unflexed, state. As clip  10  moves upwardly and tips  10   q ,  10   r  enter into gap G, flange  120   e  slidingly engages the clip causing the bottom end of clip  10  to move toward surface  110   a  of picket  110 , the top edges  10   q ,  10   r  serving as a pivot about which clip  10  rotates. This action moves the U-shaped portion  10   a  of clip  10  more deeply into the opening  110   e , causing clip sidewalls  10   c ,  10   d  (Note, especially  FIGS. 1C and 3C ) to move toward one another and further causing the portions  10   m ,  10   n  of clip  10  to flex in the direction of portions  10   g ,  10   h  respectively, of clip  10 . During this time clip  10  urges picket  110  to move in the horizontal, left-hand direction as shown by arrow B to urge surface  110   c  of picket  110  against alignment rib  120   d  of rail  120 . The angle θ between clip  10  and picket  110  continues to be reduced toward zero degrees as the clip  10  moves further into the interior of rail  120  until the lower edges  10   p ,  10   s  (Note, also  FIG. 1D ) clear flange  120   e , whereupon the clip  10 , due to the spring forces of the U-shaped portion  10   a  and portions  10   m ,  10   n , urge portions  10   g ,  10   h  of clip  10  against the interior surface  120   g  of sidewall  120   b  (see  FIG. 3C ). 
     The distance between the opposing edges  10   q ,  10   s  and  10   r ,  10   p  is substantially equal to the distance between flange  120   e  and the interior surface  120   i  of web portion  120   a  of rail  120  thereby confining clip  10  between flange  120   e  and the interior surface  120   i , preventing the clip  10  and picket  110  from moving upwardly or downwardly relative to rail  120 . The spring force of clip  10  urges picket  110  away from sidewall  120   c  and against the alignment rib  120   d  and the edge  120   f - 1  of opening  120   f  to maintain the picket in parallel with sidewall  120   b  and further to prevent movement of picket  110  either leftwardly or rightwardly in the horizontal direction relative to rail  120 . The springy material of which the clip is formed is chosen to provide a spring force which is more than adequate to achieve the above objectives. 
     As can clearly be seen, rail  120  completely conceals clip  10  from view, when fully assembled. 
     The top rail  130  is mounted to the picket  110  using a clip  10  in a similar fashion to that shown in  FIGS. 3A and 3B , the difference being that the top end of the picket is retained within the top rail  130 . 
     Making reference to  FIGS. 2A-2J , the more rugged clip embodiment  20  shown therein is comprised of a substantially U-shaped portion  20   a  having a curved central portion  20   b  and integral arms  20   c ,  20   d . Clip  20  is bent to form corners  20   f ,  20   t  and  20   g ,  20   e . The outward portions  20   i ,  20   a  extending from corners  20   g ,  20   e  respectively are further bent to form curved portions  20   l ,  20   j  which terminate in end portions  20   m ,  20   k  respectively. 
     In the manner similar to the clip embodiment  10 , clip embodiment  20  which is likewise formed of a suitable springy material, is configured to have its sidewall portions  20   c ,  20   d  flexed inwardly as it is pressed into the opening  120   c ′ have its portions  20   i ,  20   a  curve portions  20   l ,  20   j  are likewise to be flexed from the relaxed position to provide a holding force suitable to retain the picket within the rail to which it is inserted in the manner similar to clip  10  and thereby provide assembly in which picket  120 ′ is locked to rail  110 ′ in a rugged and rattle free manner. 
     Both of the clip embodiments  10  and  20  are further capable of yielding to permit raking of the fence which is described below with reference to  FIG. 5 . 
       FIGS. 2K-2M  show a preferred method for producing clip  20 . Similar to the description of  FIGS. 2H-2I , a clip pattern P 20  is stamped out of sheet S 20  of a springy metallic material. The planar clip P 20  is bent around suitable forming tools to form the desired curvatures at regions R 1 -R 5 , the resulting curvatures being shown in  FIGS. 2L-2M . 
     Making reference to  FIG. 4 , there is shown an assembly  200 , comprised of a rail  120 ′ and a picket  110 ′ which are substantially similar to the assembly  100  of  FIGS. 3A and 3B  but of a larger size and adapted for heavy duty use such as industrial or commercial applications. As a result, the rail and picket are identified with prime numbers to differentiate them from the rail  110  and picket  120  and  120  as shown in  FIGS. 3A and 3B . 
     The heavy-duty clip embodiment  20  shown in  FIG. 4  has its substantially U-shaped projection  20   a  inserted into opening  110   e ′ and aligned at an angle to the picket in a manner substantially similar to that shown in  FIG. 3A , wherein clip  20  is aligned so that its longitudinal axis forms an angle θ with surface  110   a ′ of picket  110 ′. As was described above regarding assembly  100 , as shown in  FIGS. 3A and 3B , opening  110   e  is of a size relative to clip  20  so that the sidewalls of U-shaped portion  20   d  are flexed and moved toward one another as the substantially U-shaped projection  20   a  is inserted more deeply into opening  110   e′.    
     Clip  20  is oriented at an angle θ to surface  110   a ′ of picket  110 ′ so that the upper most edges  20   n ,  20   p  of clip  20  (see also  FIG. 2F ) engage surface  110   a ′ of picket  110 ′ and further so that the bent free ends  20   m ,  20   k  also engage the surface  110   a′.    
     Similar to the embodiment shown in  FIGS. 3A and 3B , the edges  20   n ,  20   p  easily enter the gap region G′ between the outer most edge of flange  120   e ′ and surface  110   a ′ as the picket  120 ′ is moved upwardly between sidewalls  120   b ′ and  120   c ′ of rail  120 ′. The top end of picket  110 ′ passes through opening  120   f ′ and clip  20  changes its orientation relative to surface  110   a ′ whereby the lower end of clip  20  swings towards surface  110   a ′, with edges  20   n ,  20   p  serving as pivots about which clip  20  rotates. 
     As the picket moves more deeply into the region between sidewalls  120   b ′ and  120   c ′ and has its top end extending through opening  120   f ′, curved portions  20   l ,  20   j  are caused to flex so that the tips  20   m ,  20   k  move in a direction toward the lower ends  20   q ,  20   r  of clip  20 . When the lower tips  20   q ,  204  clear flange  120   e ′, clip  20  snaps into position so that its outside corners  20   g ,  20   e  are in intimate engagement with the interior surface  120   g ′ of sidewall  12   c ′ and, similar to the embodiment  100  shown in  FIGS. 3A and 3B , surface  110   c ′ of picket  110 ′ is in intimate engagement with alignment rib  120   d ′ and edge  120   f - 1 ′ of opening  120   f ′, portions  20   l ,  20   j  serving to press surface  110   c ′ of picket  110  into firm engagement with rib  120   d ′ and edge  120   f - 1 ′,  110   e ′ which also serves to press the vertices  20   q ,  20   r  into intimate engagement with the interior surface  120   g ′ of the rail sidewall  120   c′.    
     The distance between upper tips  20   n ,  20   p  and the lower tips  20   q ,  20   r  is substantially equal to the distance between flange  120   e ′ and the interior surface  120   i ′ of web portion  120   a ′, causing the entire length of the outside corners  20   g ,  20   e  to rest against the interior surface  120   g ′ of rail sidewall  120   c ′ and further assuring that clip  20  is locked in place between interior surface  120   g ′ and flange  120   e ′ and that the picket  110 ′ is maintained substantially parallel to the sidewall  120   b ′ of rail  120 ′. The clip embodiment  20  has all of the advantageous features of the clip embodiment  10  with the understanding that the clip embodiment  20  is a more rugged, heavy-duty version which is obtained by virtue of its different configuration as compared with clip embodiment  10 . If desired, clips  20  may be formed of a thicker metallic sheet or be formed of a metallic material providing an increased spring force, or both. 
       FIG. 5  is a view of a portion of a fence employing the clips of the embodiment shown in  FIG. 1A , the fence being installed to extend along a level terrain T 1  and an adjacent sloping terrain T 2 . Adjacent ends of the rails  130 ,  130 ′ are joined to a post P at the location where the level and sloping terrains meet. Although the pickets  110  are maintained in a vertical orientation along both the level and sloping terrains, the rails  130 ,  130 ′ are arranged so as to be substantially parallel to their respective terrains. Nevertheless, the clips  10  are maintained so that their central axes are aligned with the longitudinal axes of their associated pickets  110 , the rail  130 ′ is oriented so that it deviates from being perpendicular to the central axes of the pickets and the clips, which type of installation is referred to as “racking.” By providing the top and bottom edges of the clips with a convex curvature, making reference to  FIG. 1D , the distance measured along imaginary diameters such as D 2  and D 3 , for example, is constant and equal to D 1 , which is substantially the same as the distance between the flange  120   e  and the interior surface of the web portion  120   a , to firmly lock the rails to the pickets and further to prevent rattling of the fence, even when mounted on a sloping terrain. 
     The clip embodiment  20  of  FIG. 2  is provided with similarly curved top and bottom edges to permit racking as well as assuring that the rails are firmly locked to the pickets and to provide a rattle-free fence. 
       FIG. 6A  is a perspective view showing a partial fence assembly employing the clips  10 , each picket  110  receiving two (2) clips to accommodate a mid-fence rail  120  substantially the same as shown in  FIG. 3A , and a top rail  130  also shown in  FIG. 3A . Rectangular slots  110   e  are formed in the pickets (see  FIG. 3A ). The array C 1  of clips  10  for retaining the mid-fence rail  120  are first mounted on the pickets in the tilted manner described above regarding  FIGS. 3A and 3B , after which rail  120  is moved downwardly to receive the pickets through openings  120   f  and then to receive and cover the array C 1  of clips  10  for retaining rail  120  to pickets  110 . The array C 2  of clips  10  for retaining the top rail  130  are then inserted in pickets  110  provided closer to the upper ends of the pickets  110 . The top rail  130  is slid downwardly over the top of the pickets  120  to lock the clips  10  in array C 2  into place. All of the clips in arrays C 1  and C 2  are locked into place in the manner shown in the sectional view of  FIG. 6B .