Patent Publication Number: US-2002000545-A1

Title: Molded picket fence section

Description:
BACKGROUND OF THE INVENTION  
       [0001] The present invention relates to plastic picket fence systems and in particular, relates to a one piece picket fence section.  
       [0002] There are a number of fence products available where the customer purchases a finished fence section of an appropriate length. These fence sections can be made of plastic or wood and are often factory assembled. Many of the components of the plastic fence section are extruded plastic components and these components are then mechanically secured to extruded main support members.  
       [0003] With these products, the end user merely purchases a finished section. Unfortunately, these products still have a very substantial cost with respect to the assembly of the fence section and it would be desirable to produce a lower cost competing product.  
       SUMMARY OF THE INVENTION  
       [0004] The present invention relates to a picket fence section which is manufactured by a blow molding technique to produce a single component of a substantial length defining a number of pickets and integral with horizontal support members. These components are combined during the blow molding process and do not require any assembly of the pickets to the horizontal members. The blow molding manufacturing approach can be used to produce a picket fence section of a length suitable for securing between two end posts.  
       [0005] Preferrably, the picket fence section has been modified to include pinch off areas in both the individual pickets and the horizontal members to add strength to the final product.  
       [0006] A plastic picket fence section according to the present invention comprises an upper hollow horizontal member and a lower horizontal member with both horizontal members extending the length of the fence section and forming the major horizontal support structure. A plurality of vertical extending picket members are spaced in the length of the horizontal members and extend above and below the horizontal members. Each picket member is divided by the horizontal members into a top section, middle section and a base section, with all of these sections being hollow. The top section extends above the upper horizontal member with the middle section extending between the two horizontal members and the base section extending below the lower horizontal member. The middle section of the picket fence connects and maintains the spacing between the two horizontal members.  
       [0007] According to a preferred aspect of the invention, the picket fence section is greater than 30 inches in height and is of a length greater than five feet.  
       [0008] According to a further aspect of the invention, the picket fence section is greater than 30 inches in height and is of a length of about eight feet.  
       [0009] According to yet a further aspect of the invention, the fence section is symmetrical relative to a vertical plane passing through a length of the fence section.  
       [0010] In yet a further aspect of the invention, the fence section is a blow molded component.  
       [0011] According to yet a further aspect of the invention, each horizontal member includes at least one horizontal recess extending the length of the horizontal member and this horizontal recess divides the horizontal member internally into a series of horizontal hollow cavities.  
       [0012] In a different aspect of the invention, each horizontal extending recess is paired with a recess provided in the opposite side of the horizontal member and the paired recesses divide the horizontal member into a series of horizontal extending hollow cavities.  
       [0013] In yet a further preferred aspect of the invention, each horizontal member is divided by paired recesses into an upper horizontal extending chamber, a centrally horizontal extending chamber, and a lower horizontal extending chamber.  
       [0014] In yet a further aspect of the invention, each picket is recessed on opposite sides of the picket to divide the hollow cavity of the picket section into a series of hollow chambers. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0015] Preferred embodiments of the invention are shown in the drawings wherein:  
     [0016]FIG. 1 an exploded partial perspective view showing a picket fence including two end posts and a picket fence section;  
     [0017]FIG. 2 is a front view of a picket fence section;  
     [0018]FIG. 3 is a perspective view of a picket as it would have been had it not been integrally molded with the horizontal members;  
     [0019]FIG. 3 a  is a sectional view taken along line A-A of FIG. 3;  
     [0020]FIG. 4 is a sectional view through one of the horizontal members between pickets showing the various chambers thereof with one picket shown extending above;  
     [0021]FIG. 5 is a sectional view through a picket and through one of the horizontal members showing the inner connection of the picket to the horizontal members;  
     [0022]FIG. 6 is a partial front view showing the picket fence section adjacent a post for connection thereto;  
     [0023]FIG. 6A is a sectional view showing attachment of a horizontal member to a connector;  
     [0024]FIG. 7 is a perspective view of a connector used to secure the picket fence section to a post;  
     [0025]FIG. 8 is a front view of the connector of FIG. 7;  
     [0026]FIG. 9 is a partial perspective view of a blow molded post cover with a pyramid cap integral therewith;  
     [0027]FIG. 10 is a blow molded post cover with a ball cap integral therewith;  
     [0028]FIG. 11 is a blow molded post cover with integral flat cap; and  
     [0029]FIG. 12 is a cut through one of the post covers below the cap showing the wall section of a post cover. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0030] The picket fence  2  shown in FIGS. 1 and 2 includes a picket fence section  6  which is manufactured by blow molding and is a single piece. The picket fence section is supported at either ends by posts  4  and connectors  8 . The connectors  8  engage the horizontal members  22  of the picket fence section and these connectors are mechanically fastened to the post  4 .  
     [0031] The posts  4  are preferrably made of wood and include an outer cover  80  which encloses the wood post. This outer cover is also preferrably manufactured by blow molding and is a single integral piece including the top cap of the post.  
     [0032] The picket fence section  6  as shown in FIG. 2 includes horizontal members  22  and a series of pickets  20 . The pickets in this case are all of the same height, however, it is possible to have pickets of different heights. The component shown in FIG. 2 is a single integral piece manufactured by blow molding. Preferrably, the picket fence section  6  is approximately eight feet long and preferrably of a height of about four feet or less. The height can vary depending upon the particular application and need not be consistent. For example, the pickets can be of different heights to form a scallop pattern between the ends of the section. The most common heights are 36 and 42 inches, as well as the scallop or curved design. For warehousing and ease of distribution, the fence sections all stored on a four foot by eight foot skid. The size is also easily transported and manageable by the consumer. The picket fence sections are also partially nestable by shifting the fence sections such that the horizontal rails are supported on the pickets  20 . This adds stability to the stacked fence sections.  
     [0033] The individual pickets  20  and the horizontal members  22  are hollow and the horizontal members are reinforced by a series of recesses  28 . These recesses are referred to as pinch offs in blow molding and each horizontal member has two horizontal pinch offs  28 . These pinch offs serve to stiffen the horizontal members which provide the primary support for the picket fence section. Each of the horizontal members include end portions  50  with a small depressed area  52  which is used to form part of the connection with the connectors  8 . The pickets  20  are reinforced by pinch offs  29 .  
     [0034]FIG. 4 shows a cross section through one of the horizontal members in the gap between pickets. As can be seen, the horizontal member  22  has been divided into three hollow cavities, namely; the top chamber  40 , the middle chamber  42 , and the bottom chamber  44 . The pickets are generally interrupted by the horizontal members and are centered on these horizontal members. The picket fence section  6  is symmetrical to either side of the section. In this way, the appearance of the fence to the installer&#39;s side is the same as the appearance to the neighbour&#39;s side.  
     [0035] For the purpose of better understanding, a single picket, if not manufactured as part of the fence section, is shown in FIG. 3. As can be seen, the picket has a U-shaped pinched off region  29  to add additional stiffness. This pinched off region is not closed off at the base of the picket as a horizontal pinch off at that point may tend to accumulate dirt. By tapering the recess out, any dirt which is washed down through the recess will pass out and over the bottom surface of the picket.  
     [0036]FIG. 3 a  shows a sectional view taken along line A-A of FIG. 3. The pinch off regions  29  have basically defined a three chamber picket with two side chambers  32  and a central chamber  34 . These chambers cooperate to provide a greater moment of inertia and stiffen the pickets. As can be appreciated, the wall thickness is relatively thin and the stiffness is achieved by the size of the chambers and the particular reinforcing. This is similar to the horizontal rails where the stiffness is increased by the three spaced chambers.  
     [0037] In some cases it may be desirable to merely have horizontal members which generally are sized to correspond to a two-by-four normally associated with a picket fence. In this case there can be a single large chamber and the chamber can be sized to receive a two-by-four through the fence section. This two-by-four can provide additional reinforcing. This has not been found to be necessary for most applications as the stiffening provided by providing multiple chambers and pinch off regions does provide high strength.  
     [0038] This structural strength is somewhat surprising and there is concern that the market will not immediately recognize this strength. In some cases it may be more convenient to accept the markets misconception and provide them with a simple easily understood solution. This easily understood solution would be the mere insertion of a two-by-four or other reinforcing member through the horizontal member or a chamber thereof. The multi-chamber horizontal members can be reinforced with a one inch by one inch metal or wood reinforcing member through the center chamber.  
     [0039] The horizontal members at the various points where the pickets appear to pass through the horizontal members include stiffening portions  56  which are aligned with the pinched offs  29  of each picket. These provide additional bracing between the top, middle, and bottom chambers of each horizontal member. This can be appreciated from the sectional view of FIG. 5 through a non pinch off region of one of the pickets. Basically the reinforcing  56  is achieved by not pinching off entirely between the top chamber  40 , the middle chamber  42  and the bottom chamber  44 .  
     [0040] This reinforcing only occurs at the pickets and the horizontal members will be fully pinched off as shown in FIG. 4 between the pickets. This also serves to provide a visual perception that the pickets are extending through the center of the horizontal members. The fence section preferrably has at least 10 pickets approximately three and one half inches wide. For eight foot nominal sections, there are  13  pickets.  
     [0041]FIG. 6 shows the picket fence section  6  positioned adjacent the post  4 . A small gap is provided between the picket fence section and the post. As can be appreciated, the picket fence is made of a plastic material, preferrably high density polyethylene (HDPE), and accommodation must be made for thermal expansion and contraction. The connectors  8  include a center port  62  which can slide on the end portion of the horizontal members  22 . Each connector includes an outer flange area  63  with securing slots  70  at a bottom edge of the flange and securing ports  72  on the top edge of the flange. The connector includes a projecting collar  64  to provide additional support for engaging the end portion  50  of a horizontal member  22 . Support gussets  60  are provided at the corners of the collar  64  and two additional end gussets are provided along the center line of the connector. The connector is preferrably made by injection molding.  
     [0042] To install a fence section, collars are inserted on the horizontal members and the fence section is brought into place between two posts positioned on eight foot centers. The posts are four-by-four posts and include an outer sleeve as will be subsequently described. Once the fence section has been generally brought into position, it can be appropriately lifted at either end thereof to position the fence section at the appropriate height.  
     [0043] The connectors associated with the upper horizontal member can be secured to the post either by lifting the section into place and supporting it on two screws which were previously located. The slots of the connectors are placed on these screws. These screws can be approximately placed prior to bringing the section into place and the top horizontal member can be hung in place, suspending the picket fence section between the two posts. Once the fence section is generally positioned, the installer can then fine tune the placement of the fence section and accurately secure it by using screws through ports  72  of the connector. Once the top connectors have been appropriately positioned, the screws in the slot openings  70  can be finally secured in place.  
     [0044] It has been found that it is not necessary to prehang the connectors associated with the lower horizontal member. Thus to install a fence section, the installer would normally accurately locate two screws corresponding to each upper connector and effectively hang the fence section in place. Once so positioned, it can be finely tuned without any substantial difficulty. Once the connectors have been installed on the posts, blind screw members can pass through the projecting collar  60  to align with the depressions  52  of the horizontal members  71 . These depressions  52  are not holes and the blind screws do not pierce the horizontal members. They merely engage the horizontal members as generally shown in FIG. 6 a.    
     [0045] Additional details of the gusset supports the projecting collar and the base flange of the connectors are shown in FIG. 8. As can be seen from FIG. 8, the port  62  passes all the way through the connector such that the connector can slide on past the end of the horizontal member. The installer typically drills the holes  79  through which the blind screw members  71  engage the recess  52 . This recess provides for expansion and contraction, and also provides end stops.  
     [0046]FIGS. 9, 10,  11  and  14  show details of the post cover  80 . The post cover  80  is again made by blow molding and is a single integral piece. In the case of FIG. 9, a pyramid cap  81  has been formed at one end of the post cover and the post cover is sized for sliding over the four-by-four wooden post. In FIG. 10, a similar post cover is shown, however, it has a ball cap  83  as a decorative top piece. Again, these caps are integral with the cover. FIG. 11 shows a flat cap  85  variation which again is integral with the cover  80 .  
     [0047]FIG. 12 is a sectional view through the post cover  80  below the decorative top portion. The post cover includes a generally square center section for sliding over the four-by-four post. It is sized to closely correspond with the four-by-four post and as such, has side sections approximately three and one half inches in length. The corners of the post covers do include a projecting end segment  82  which allows for tolerance variations in the post dimensions and in any twisting of the post. Each of these corners provide a small amount of give to allow the cover to slide over the four-by-four post. The post cover can be oversized in length and the bottom of the cover trimmed to the appropriate length.  
     [0048] The beads  82  also serve to center the connector  8  on the post.  
     [0049] Blow molding is a relatively old plastic molding process, however, it has been used for the manufacture of products such as garbage cans. The manufacture of the picket fence section using blow molding has eliminated a large portion of the manufacturing costs associated with the mechanical fastening of extruded components as was previously done with respect to plastic sections. Surprisingly, the picket fence section has considerable strength and has great advantages with respect to ease of assembly, durability and low maintenance characteristics.  
     [0050] The blow molded post sleeves with integral top caps can enclose any wooden parts of the fence section and also provides a finished surface which is difficult to meet with respect to a wooden equivalent.  
     [0051] The blow molded picket fence section requires after blow molding, trimming of material between pickets and at the ends of the fence section. This trimmed material can be recycled.  
     [0052] Although various preferred embodiments of the present invention have been described herein in detail, it will be appreciated by those skilled in the art, that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.