AU2013100109B4

AU2013100109B4 - Plinth rail

Info

Publication number: AU2013100109B4
Application number: AU2013100109A
Authority: AU
Inventors: Jack Leighton Fitzgerald; Louis Thomas Ross Fitzgerald
Original assignee: THINK FENCING Pty Ltd
Current assignee: THINK FENCING Pty Ltd
Priority date: 2013-01-31
Filing date: 2013-01-31
Publication date: 2018-09-20
Anticipated expiration: 2021-01-31
Also published as: AU2013100109A4

Abstract

A plinth rail 20 including an elongate hollow plastic extrusion 23 which is generally rectangular in cross-section and which defines an outer surface 25. The plinth rail 20 5 further includes a thin substrate 24 which is applied to substantially the outer surface 25 of the extrusion 23 to form an outer skin.

Description

PLINTH RAIL

FIELD OF THE INVENTION

The present invention relates to rails, commonly known as “plinth rails”, which form the bottom or base rail of certain types of fence installations. A plinth rail typically is installed substantially horizontally along the ground surface along which a fence is installed, and the plinth rail forms the base rail from which the fence palings or metal sheets extend upwardly.

BACKGROUND OF THE INVENTION

The following discussion of the background to the invention is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of the application.

Plinth rails are used in fencing installations to form the base rail of a fence, and while the plinth rails have aesthetic properties to improve the appearance of the fence, they also have practical advantages in containing weeds, plants and small animals from passing under the fence.

Plinth rails have traditionally been made from timber, although in more recent years, metal plinth rails have been employed is some fence installations, particularly with metal fence installations.

Timber plinth rails have been popular in the past, as timber has been readily available, is easily sawn to size on site and has generally favourable characteristics for the use to which the plinth rail is put. That is, timber plinth rails generally will last the life of the fence and will often outlast the fence palings and fence supports. Moreover, timber can be easily painted and will readily accept nails and screws.

However, disadvantages of timber plinth rails include that when painted they can fade, sometimes rapidly. Accordingly painted plinth rails often need re-painting as frequently as every 24 months to return to their original appearance. Timber plinth rails are also prone to distort and can facilitate the spread of grass fires from one property to another. Most timber rails are also treated using carcinogenic CCA. When used with metal fencing, timber plinth rails can void manufacturing warranties because of the propensity of the timber rail to absorb moisture and to thus facilitate rusting of the metal fence sheeting.

In more recent times, metal sheet fencing has become more popular, and in this fencing, metal plinth rails are often used. Such plinth rails are less easy to work on site, but despite this, they are still relatively popular, particularly when used with a metal fence. Metal plinth rails can be painted once the fence is formed, although it is more popular to use pre-painted plinth rails, such as manufactured out of ColorBond ® by BlueScope Steel.

While metal plinth rails offer advantages over timber plinth rails, mainly in terms of longevity, metal plinth rails are generally more expensive than timber rails, and they can also be of greater weight, which can be a disadvantage for fence installers and can add to transport costs. In addition, metal plinth rails scratch and dent easily, can have sharp edges, which can present a hazard to installation personnel and residents in the vicinity of the fence, and can rust, sometimes rapidly, due to the close contact of the plinth rail with the ground surface which is often moist.

Applicant has recognised that an improved or at least alternative plinth rail, which has one or more of the characteristics of long life, aesthetic appearance and ease of use for installation, would be desirable.

SUMMARY OF THE INVENTION

The present invention provides a plinth rail which includes an elongate hollow plastic extrusion, which is generally rectangular in cross-section. The plastic extrusion defines an outer surface and the plinth rail further includes a thin substrate which is applied to substantially the full outer surface of the extrusion to form an outer skin, the substrate being stretched about the outer surface of the extrusion. A plinth rail according to the present invention advantageously is formed at least substantially of plastic, which makes the plinth rail relatively light weight and depending on the plastic selected, robust. A plastic plinth rail can have properties which enable it to outlive prior art timber and metal plinth rails, while the use of a plastic material enables the plinth rail to be readily formed and worked on site with the same ease as a timber plinth rail, as the plastic material is readily cut by a saw, and is readily drilled. It will be appreciated that the use of plastic for the plinth rail of the invention means that the plinth rail will not rot like timber plinth rails, and will not rust i like metal plinth rails. A further advantage is that the plastic material of the plinth rail can be at least partly or fully recycled, thus providing a use for recycled plastic components and contributing to sustainable practices.

Moreover, the use of a thin substrate applied to substantially the full outer surface of the plastic extrusion enables the plinth rail to be coloured and/or textured to suit the particular fence installation being constructed. Thus, for example, the outer substrate could have a timber look, so that the plinth rail of the invention appears to have a traditional timber appearance. Alternatively, the plinth rail could have the look of a metal plinth rail, or it could be coloured in a variety of different colours for selection by the consumer. The application of a coloured substrate overcomes a drawback with the use of polyvinylchloride (PVC) which is difficult to paint in a manner in which the paint has a long life. Typically, PVC is not painted as the paint does not normally last very long so the aesthetic appeal of PVC is not high.

The substrate can additionally be UV stabilised and can have other properties such as for weather protection and scratch resistance, while flame retardants can be included to make the plinth rail self extinguishing. The extrusions can be prefabricated to particular lengths and can include textured surfaces and openings or slots for the receipt of screw fasteners, or pickets or other forms of screening made of either metal, timber or plastic so that the installation procedure is simplified.

The plastic extrusion of the plinth rail according to the invention is likely to be formed from a PVC composite, although other plastics can be employed. For example, the plastic extrusion could be formed from any one of the following: PVC(Poly Vinyl Chloride), ASA (Acrylonitrile Styrene Acrylate), ABS (Acrylonitrile Butadiene Styrene), j PMMA (Poly Methyl Methacrylate), HIPS (High Impact Styrene), PC (Poly 1

Carbonate), PP (Polypropylene), PE ( Polyethylene), Nylon, WPC (Wood Plastic Composite), SAN ( Styrene and Acrylonitrile)

The plinth rail is generally rectangular in cross-section and in some arrangements of the invention, the height of the plinth rail is about three times the width. However, the plinth rail can be of any generally rectangular dimensions and could for example have a height which is about twice the width, or alternatively about four times the width.

The wall thickness of the plastic extrusion can be of any suitable thickness, but in ! some forms of the invention, the wall thickness is between 1mm and 4mm, or between 2mm and 3mm, or is about 2mm. The thickness of the wall of the plastic extrusion can effect the strength and stiffness of the plinth rail, although, as will be described later herein, the use of strengthening ribs and webs can be employed to impart strength and stiffness without needing to increase the wall thickness.

The substrate which is applied to the outer surface of the extrusion to form an outer layer or skin can be made of any suitable material, although in some forms of the invention, the substrate is formed from ASA (Acrylonitrile Styrene Acrylate), ABS (Acrylonitrile Butadiene Styrene) , PMMA (Poly Methyl Methacrylate) Nylon, SAN (

Styrene and Acrylonitrile) or Polycarbonate. The substrate can have a thickness of about 0.5 > 1.0mm.

Application of the substrate to the outer surface of the extrusion can be achieved in any suitable manner such as by stretching the substrate about the extrusion and allowing the substrate to shrink into firm and close contact with the outer surface.

Heat can be used to assist the shrinking process or the material of the substrate and its dimensions can be selected so that the substrate naturally shrinks about the plastic extrusion.

Alternatively, the substrate can be adhered to the outer surface of the extrusion by any suitable adhesive.

In one form of the invention, application of the substrate to the outer surface of the extrusion can also be completed in a single process called “co-extrusion” whereby two or more extruders force molten polymer into a single die and the polymer is

I diverted into cavities in the die that regulate the flow and placement into the crude shape of the composite plinth rail (“composite” meaning the combination of the plastic ! extrusion and substrate). The composite plinth rail then enters a forming/cooling j calibration chamber, in which vacuum and pressure are used to form the polymer into ! the final shape of the plinth rail. In this co-extrusion process, continuous production of a plinth rail according to the invention can take place, with the continuous rail being separated into sections once it exits the die and is sufficiently rigid for engagement by a suitable guillotine or saw. j

As indicated earlier, a plinth rail according to the invention can include webs or ribs for stiffening and strengthening purposes. In some forms of the invention, the plastic extrusion has a pair of generally parallel long sides and a pair of generally parallel short ends which define the generally rectangular cross-section of the plinth rail and which define an interior between the sides and ends. In that construction, the plastic extrusion can include a web extending across the interior from one of the pair of long sides to the other of the pair of long sides. The web can be formed integrally as part of the plastic extrusion.

The web described above can extend substantially parallel to the short ends and can separate the interior into a pair of chambers on either side of the web which can be of substantially the same dimensions.

Alternatively, the plinth rail can include more than a single web and for example, can include a pair of webs which extend across the interior of the plastic extrusion from one of the pair of long sides to the other of the pair of long sides, with the webs being spaced apart from each other.

Where a pair of webs is provided, those webs can both be substantially parallel to the short ends of the plastic extrusion and the pair of webs can separate the interior into three chambers.

Additional webs or ribs can be provided as required, so that in other forms of the invention, three or more webs can be provided bridging the interior of the plastic extrusion between the pair of long sides.

I

The present invention further includes a method of forming a plinth rail, which includes extruding a plastic material in a first extrusion stage into a generally rectangular cross-section and defining an outer surface. The method can further include extruding a thin substrate in a second extrusion stage and applying the thin substrate to substantially the full outer surface of the extrusion to form an outer skin.

The method described above can further include extruding webs or ribs within the interior of the plastic extrusion and can include the other features of a plinth rail as described above. BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be more fully understood, some embodiments will now

I be described with reference to the figures in which: i

Figure 1 illustrates a portion of a fence construction according to the prior art. i

Figure 2 illustrates in perspective view a plinth rail according to the invention.

I

Figure 3 is a cross-sectional view through III - III of Figure 2.

Figure 4 is an enlarged sectional view through the top circled corner of the plinth rail of Figure 3. DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 is a view of a prior art fencing arrangement 10 and shows upright supports 11, which are normally secured to the ground surface below the fencing arrangement 10 within concrete filled holes formed in the ground. Upright supports 11 include notches 12 to support horizontal beams 13. A plurality of upright palings 14 are secured by nail or screw (not shown) to the beams 13 and the palings are normally secured in slightly overlapping relationship to form a solid wall. The section of fencing arrangement 10 shown in Figure 1 would be repeated for the length required to fence a particular area.

The fencing arrangement 10 further includes a plinth rail 15 which extends horizontally to form the base of the arrangement 10 and which is received in base notches 16 of the supports 11. The bottom ends of the palings 14 either rest on the top surface 17 of the plinth rail 15, or extend to a position in front of the front face (the opposite face of that shown in Figure 1) of the plinth rail 15.

The plinth rail shown in Figure 1 typically would be of a timber material as would each of the other components illustrated in the fencing arrangement 10. Metal fencing arrangements are of different construction to the fencing arrangement 10, but have the same basic function and often include a metal plinth rail which extends horizontally substantially in the manner shown in Figure 1.

Figures 2 to 4 illustrate a plinth rail 20 according to the invention. The plinth rail 20 is formed to have a generally rectangular cross-section, defined by a pair of generally parallel long sides 21 and a pair of generally parallel short ends 22. The plinth rail 20 can be formed to any length that is required and can include openings, notches and other fabricated additions for the purposes of installing the plinth rail in a fencing arrangement.

In the form of plinth rail illustrated in Figures 2 and 3, the length L of the cross-section is approximately three times the width W. As indicated earlier, other relative dimensions of the cross-sectional shape of the plinth rail 20 can be adopted.

Figure 3 illustrates the wall thickness T and as indicated earlier, this can be in the region of from 1mm to 4mm, although in the arrangement illustrated, the preference is for the thickness T to be about 2mm.

The plinth rail 20 is formed from a plastic extrusion and a thin substrate which is applied to the outer surface of the extrusion. Figure 4 illustrates this arrangement most clearly, whereby the circled top right hand corner section of the plinth rail 20 of Figure 3 is shown and illustrates a plastic extrusion portion 23 along with a thin substrate portion 24. For clarity, the portions 23 and 24 are shown slightly separated, but in practice, there would be no gap between the outer surface 25 of the portion 23 and the facing surface of the substrate portion 24, but rather, the portions 23 and 24 would be in contact. The portion 23 can be applied to the portion 24 in any suitable manner, such as by stretching the portion 23 over the portion 24, or by adhering the two portions together. As discussed above, the extrusion process for forming the

I plastic extrusion can be modified to include a second stage in which the substrate is formed and the process can include application of the substrate to the outer surface of the extrusion.

The substrate 24 of Figure 4 completely encircles the outer surface of the plastic extrusion 23, so that with reference to Figure 2, the entire exterior of the plinth rail 20 is formed by the substrate 24. Effectively, the substrate forms a sheath about the plastic extrusion and is a tight or close fit against the outer surface of the plastic extrusion.

The plinth rail 20 further includes ribs or webs 25 and in the figures, a pair of webs 25 is provided which extend substantially parallel to each other and substantially parallel to the short ends 22 between the long sides 21. The webs 25 are formed as part of the extrusion process of the plastic extrusion and are formed integrally with the long sides 21. The webs 25 separate the interior 26 of the plinth rail 20 into three equal chambers 27.

The plinth rail 20 is relatively lightweight compared to timber and metal plinth rails but has necessary strength and stiffness required for proper performance. Moreover, the substrate 24 applied to the plastic extrusion 23 can protect the plastic extrusion from deterioration and can allow the plinth rail to have a range of different surface finishes and colours. The plinth rail 20 is easy to cut and drill and has a long life to the extent that it would likely outlast other components of a fence it is used with. Of particular importance is that the use of plastic in the plinth rail allows the use of recycled materials and thus provides a use for those materials.

The invention described herein is susceptible to variations, modifications and/or additions other than those specifically described and it is to be understood that the invention includes all such variations, modifications and/or additions which fall within the spirit and scope of the present disclosure. i j

Claims

1. A plinth rail, including an elongate hollow plastic extrusion, which is generally rectangular in cross-section, the plastic extrusion defining an outer surface and the plinth rail further including a thin substrate which is applied to substantially the full outer surface of the extrusion to form an outer skin, the substrate being stretched about the outer surface of the extrusion.

2. A plinth rail according to claim 1, the substrate being formed from ASA (Acrylonitrile Styrene Acrylate), ABS (Acrylonitrile Butadiene Styrene), PMMA (Poly Methyl Methacrylate), Nylon, SAN (Styrene and Acrylonitrile) or Polycarbonate

3. A plinth rail according to claim 2 or 3, the substrate being adhered to the outer surface of the extrusion.

4. A plinth rail according to any one of claims 1 to 3, the substrate being applied to the outer surface of the plastic extrusion within the extrusion process such that the plastic extrusion is formed in a first stage of the extrusion process and the substrate is formed in a second stage of the extrusion process and is applied to the outer surface of the extrusion following the second stage of the extrusion process.

5. A plinth rail according to any one of claims 1 to 4, the plastic extrusion having a pair of generally parallel long sides and a pair of generally parallel short ends defining the generally rectangular cross-section and defining an interior between the sides and ends, the plastic extrusion including a web extending across the interior from one of the pair of long sides to the other of the pair of long sides.