MX2013000710A

MX2013000710A - Metallic pallet with improved corner construction.

Info

Publication number: MX2013000710A
Application number: MX2013000710A
Authority: MX
Inventors: Ayyakannu Mani
Original assignee: Alx Pallet Systems Llc
Priority date: 2010-07-19
Filing date: 2011-07-19
Publication date: 2013-03-08
Also published as: AU2011279801A1; WO2012012363A3; BR112013001348A2; WO2012012363A2; JP2013530900A; KR20130094299A; CA2805429A1

Abstract

A metallic pallet (20) having generally planar top (22) and bottom (40) sides. Corner pieces (56) join the top (22) and bottom (40) sides and provide controlled deformation in the event of corner impacts. Spacer block (78, 80) function as risers to establish a space between top (22) and bottom (40) sides for receiving forklift tines (24). The top side (22) is formed in a rectangular formation with long (28) and short (30) rails establishing a perimeter for a plurality of decking members (32) which are welded at their ends to one another and to the corner pieces (56). Each corner piece (56) includes a separately formed plastic cover (64). The inside of the cover (64) may include vertical notches (92) for engaging vertical ribs (70) formed by structural webbing inside the corner piece (56). The outer edge (66) of the cover may include an outer corner section configured to directly engage a chamfer (94) in the metallic body of the corner piece (56). An RFID tag (58) may be located in a hollow corner piece (56) for tracking purposes.

Description

METALLIC PLATFORM WITH ENHANCED CORNER CONSTRUCTION DESCRIPTION OF THE INVENTION The invention relates generally to flat horizontally supported surfaces such as industrial platforms having a support surface provided with a support means by which a load can be supported relatively close to a floor and which has means for receiving handling means below the surface. surface or load and where the support surface is made of metal.

Platforms are commonly used to support and transport grouped objects or loads in applications similar to those shown in Figure 1. Traditionally, platforms have been constructed of wooden members assembled together. However, wooden platforms are subject to many disadvantages, including relatively short life, chemical contamination, insect infestation, and fire risk, to name a few. More recently, the platforms have been constructed of plastic materials that can be more durable than wood and are typically resistant to insects, however, they still undergo chemical contamination, fire hazards and other deficiencies. Although additives can be used to make a more flame-retardant plastic platform, such additives are costly and generally disadvantaged in situations where food handling is required. There is a desire within the material handling industry to identify new materials suitable for manufacturing cargo transport platforms that will provide superior functionality at a competitive price in cost with other options.

Some examples of platform constructions representative of the teachings of the prior art can be found in U.S. Patent No. 5,367,960 to Schleicher granted on November 29, 1994, U.S. Patent No. 5,522,325 to Knauer issued June 4, 1996, US Pat. 2002/0078863 for Marr et al. published on June 27, 2002 and US 2005/0178299 for Rasmussen et al. published August 18, 2005. These examples of the prior art illustrate various methods in mixed construction forms that include at least some metal components. In these examples, the platforms include an upper cover or load engaging surface which may be composed of parallel or planked top slats connected to a surrounding frame made of plastic or wood.

A disadvantage found in the constructions of the prior art refers to the lack of general strength of the platform in terms of resistance to damage due to rough handling. Excessive damage manifests more typically when a platform experiences a force laterally applied to one of its corners. This can happen during transport such as when a forklift is moving a platform, or when the platform is stationary but some object abuts it. It will be appreciated that metal platforms are substantially more expensive to manufacture than wooden platforms. The cost proposition for a metal platform therefore only becomes favorable when the metal platform can enjoy a substantially longer service life than the typical wooden platform or other available alternatives. Therefore, building a metal platform that has the ability to withstand rough handling and other conditions under pressure is imperative for the business proposition for such objects.

Consequently, metal platforms have inherent benefits and are increasingly being accepted within an industry accustomed to using cheap wooden platforms. However, there remains the opportunity to further improve the designs and platform constructions with the objectives to reduce the severe damage resulting from the impact of the corners and in this way improve their service life.

A metal platform of the type to support objects for storage and transportation is provided. The platform comprises a generally flat upper side having a substantially rectangular configuration defining four corners. The upper side includes four elongated outer upper frame members. The upper side also includes a plurality of decking members arranged parallel to each other and parallel to two of the outer frame members. A generally flat lower side having a substantially rectangular configuration defining four corners is provided. The lower side includes four elongated outer lower frame members. The lower side is arranged below the upper side so that its corners are vertically aligned with the corners of the upper side in corresponding pairs. Also, the upper outer and lower outer frame members are arranged in opposite pairs. Four generally hollow corner pieces are provided. Each corner piece extends between a respective aligned pair of corners of the upper and lower sides. The corner pieces each interrupt the upper and lower sides generally flat in such a way that the upper and lower sides do not overlap the corner pieces. Each of the corner pieces comprises a pair of adjacent perpendicular back walls in direct splice contact with the upper and lower sides. Each corner piece further comprises a top plate and a bottom plate respectively fixed to the back walls. The top plate is generally flat with the top side, and the bottom plate is generally flat with the bottom side. Each corner piece includes a cover formed separately. The cover is configured to simultaneously engage the rear walls and the upper and lower plates.

The subject invention is distinguished from the prior art designs by providing a unique corner construction that is strong and easily manufactured. This design, which represents a separation of the prior art techniques, increases the capacity of a metal platform to resist the damage caused by undesirable impact forces at the corners, which consequently extends service life well and therefore the cost-benefit of a metallic platform.

BRIEF DESCRIPTION OF THE DRAWINGS These and other features and advantages of the present invention will be more readily appreciated when considered in conjunction with the following detailed description and accompanying drawings, wherein: Figure 1 is an environmental view showing a platform constructed in accordance with an embodiment of this invention used to support a load and balanced for transportation by a common forklift vehicle; Figure 2 is a perspective view of the object platform; Figure 3 is a perspective view showing the lower part of the platform according to Figure 2; Figure 4 is a top view of the object platform; Figure 5 is a bottom view of the object platform; Figure 6 is an end view of the target platform; Figure 7 is a cross-sectional view taken generally along lines 7-7 in Figure 6; Figure 8 is a cross-sectional view of an outer spacer block taken generally along lines 8-8 in Figure 6; Figure 9 is a perspective view of a corner piece according to an embodiment of the invention; Figure 10 is an exploded view of the corner piece of Figure 9; Figure 11 is a cross-sectional view taken generally along lines 11-11 of Figure 9; Figure 12 is a perspective view of the cover for the corner piece of Figure 10; Figure 13 is a schematic view illustrating the tracking capabilities for the object platform when it is configured to include an RFID tag; Figure 14 is a perspective view of a first alternative corner piece construction; Figure 15 is a fragmentary perspective view showing a second alternative corner piece in partially exploded form and including an optional RFID tag in the hollow space therein; Y Figure 16 is a perspective view of a third alternative corner piece design.

Reference is made to the figures, where similar numbers indicate similar or corresponding parts in the various views, a platform constructed in accordance with the embodiments of this invention is generally shown at 20. The standard platform dimensions are given as (121.92 cm x 101.60 cm x 14.224 cm (48 inches x 40 inches x 5.6 inches), however, the specific dimension properties of the platform 20 undergo changes to suit any given application.

As perhaps best shown in Figures 2-7, the platform 20 includes a generally flat upper side, generally indicated at 22. The upper side 22 establishes a generally horizontal surface to support objects such as cargo for storage and transport. The upper side 22 is raised above the floor or other supporting structure so that the tips of a forklift 24 (Figure 1) can be inserted under the upper side 22 in the customary manner. The upper side 22 has a substantially rectangular configuration as suggested by the dimensions suggested in the foregoing, however these are subject to variation depending on the design choice. The upper side 22 defines four corners which, in the preferred embodiment, are represented by the notches 26. The upper side 22 also includes four elongated outer upper frame members composed of two long bars 28 and two short bars 30. The long and 30 short bars 28 are arranged around the perimeter of the upper side 22 and each extend into the notches 26 thereby establishing a generally rectangular shape for the upper side 22. The long and short bars 28 are preferably made of extruded aluminum having any desirable and suitable cross-sectional shape such as, for example, shown in the cross section in Figure 7.

A plurality (seven in the examples shown) of boarding members 32 are arranged parallel to each other and parallel to two short bars 30 with generally equal spacing therebetween. The deck members 32 are preferably made of an extruded aluminum material and may have a cross section similar to that shown for example in Figure 7. Each deck member 32 is welded at its ends to the inner edges of the two bars 28 long. The upper side 22 in one embodiment further includes a structure 34 disposed directly below each of the board members 32. The structure member 34, perhaps best seen in Figures 3 and 7, extends parallel to the two long bars 28 to provide a mid-section support for the upper side 22 for increased weight bearing capacity for the platform 20 Returning now to Figures 3 and 5, the platform 20 is shown including a generally flat lower side 40. The lower side 40, similar to the upper side 22, also has a substantially rectangular configuration having corners defined by notches 42. The outer dimensional properties of the lower side 40 are substantially identical to those of the upper side 22 so that the notches 26, 42 they can be aligned directly on top of each other. The lower side 40 also includes four elongate outer frame members comprised of long bars 44 and short ones 46. The short bars 46 of the lower side 40 are generally congruent with the short bars 30 on the upper side 22, and likewise, the long bars 44 of the upper side 22. bottom side are generally congruent with the long bars 28 on the upper side 22. Unlike bars 28, 30 on the upper side 22, however, in the preferred embodiment shown in Figures 5 and 7, the bars 44, 46 on the lower side 40 are significantly wider (measured laterally) than their long bar 28 and short 30 counterparts. side 22 above. As a result, the long bars 44 and short bars 46 of the lower side 40 can, in one embodiment, directly connect to each other at their terminal ends by a truncated miter joint 40. The miter joint 48 can be welded to provide a fixed direct connection between the long bars 44 and short bars 46. The lower side 40 further includes a first inner lower frame member 50 and a second inner lower frame member 52. The second inner frame member 52 perpendicularly bisects the first inner lower frame member 50 into a lower intersecting joint 54 that can be welded to secure the frame members 50, 52 to each other. Additionally, the terminal ends of each of the first 50 and second members 52 of the inner underframe can be joined at their respective ends to the inner edges of the long and short bars 46 such as by welding to establish a strong matrix or construction skeleton.

Four generally identical hollow corner pieces are generally indicated at 56. The corner pieces 56 each extend between a respective aligned pair of the corners of the upper 22 and lower sides 40 as represented by their respective notches 26, 42. In other words, the corner pieces 56 are fixed in each of the notches 26, 42 and are there securely connected such as when welding to rigidly attach the upper side 22 to the lower side 40 by the corner pieces 56. Thus, because the corner pieces 56 are fixed in the notches 26, 42, it can be seen that the corner pieces 56 each interrupt the upper sides 22 and lower sides 40 generally flat. so that the upper 22 and lower 40 sides do not overlap the corner pieces 56. As a result, the corner impacts on the platform 20 can be completely absorbed by the deformation of the hollow corner pieces 56 without distorting the flat configurations of the upper 22 and lower sides 40.

Various configurations for corner pieces 56 can be found for reference in US 2010/0218705 applicant co-pending, published September 2, 2010, the full description of which is incorporated herein by reference and based herein. Figures 9-12 illustrate a preferred embodiment of the corner pieces 56 designed for optimum performance, low cost, ease of construction, as well as the ability to securely contain an RFID tag 58 or other tracking features. Figure 10 is an exploded view of the corner piece 56. The corner piece 56 shown here comprises a cast aluminum body which establishes the perpendicular rear walls 60 in direct splicing contact with the upper 22 and lower sides 40. The upper and lower plates 62 connect upper and lower ends of the rear walls 60 in a structure very similar to a box. As a result, the upper plate 62 is generally flat with the upper side 22 and the lower plate 62 is generally flat with the lower side 40 thereby contributing to the capacity of the load transport. A cover 64 is formed separately from the rear walls 60, and is preferably made of non-metallic materials such as plastic or hard rubber in an injection molding process. The cover 64 is configured to simultaneously engage the rear walls 60 and the upper and lower plates 62 to provide a solid secure exposed area for the corner piece 56. The cover 64 includes an outer edge 66 that establishes the main or terminal corner for the platform 20, which is expected to receive the initial and most frequent impacts during rough handling of the platform 20. The composition of the material selected for the cover 64 therefore it must be impact resistant and durable even somewhat elastic.

The corner pieces 56 can further include an internal framework 70 integrally formed with the rear walls 60 and the plates 62 during the casting process both for strength and for controlling the deformation. The cover 64 may include notches 92 for receiving or engaging the outer edges of the framework 70 which, as shown in Figure 10, is formed as three vertical grooves and a horizontal groove. The upper and lower plates 62 are also formed with chamfers 94. The outer edge 66 of the cover 64 is configured with short extensions to directly engage the chamfers 94 as perhaps best seen in Figure 11. By this design, the cover 64 and the molten aluminum components become mechanically interlocked so that the corner pieces 56 can partially absorb and collapse in response to the impact forces without the tension of the upper 22 or lower sides 40 and consequently help to maintain their flat nature for an extended service life of the shelf 20. The hollow corner pieces 56 resist infiltration by liquids or other unwanted substances.

As mentioned and shown in Figure 15, a small RFID tag 58 can be sealed within one or more of the corner pieces 56 to provide tracking and tracking capabilities of the platform 20. An adhesive can be used to anchor and seal the RFID tag 58 within the corner piece 56. Alternatively, the RFID tag 58 can be securely placed in a cavity or receptacle formed integrally with or subsequently connected within the corner piece 56. In this way, the RFID tag 58 can be contained in a protected enclosure to provide a long-term service life and functionality for tracking purposes of the platform 20. If the RFID tag 58 is installed in the corner piece 56 before of the assembly of that corner piece 56 with the upper 22 and lower 40 sides, the RFID tag 58 will preferably be retained in a separate position as far as possible from each of the rear walls 60 where the weld is presented during connection to the upper 22 and lower 40 sides. This will help protect the RFID tag 58 from damage to the excess heat that occurs during welding operations. In contrast, the RFID tag 58 is also located as far as possible from the outer edge 66 where the majority of the deformation is expected to be present in use. This will help protect the RFID tag 58 from damage for a longer service life.

Figure 13 shows an exemplary highly schematic method by which the RFID tag 58 can be used to triangulate the position of a platform 20 that has been lost or possibly stolen. Using the known RFID technology, the exact position of the platform 20 with respect to the digital map 76 can be determined. Of course, the map 76 can be specified to a particular store or particular manufacturing facility, or used more generally to track the platforms 20 which can be stolen or lost in a wider geographical area. The additional function can be incorporated into the RFID tag 58 according to known techniques.

Returning to Figures 2-8, the platform 20 is shown to include a plurality of extruded aluminum spacing blocks 78, 80. Each spacer block 78, 80 extends perpendicularly between the upper 22 and lower 40 sides to keep the upper 22 and lower sides 40 generally parallel spaced apart and aligned in relation to each other so that the notched corners 26, 42 remain vertically aligned and in this way the corresponding pairs of long bars 44, 44 and 30 short, 46 remain aligned. In addition, the spacer blocks 78, 80 increase the weight force load with which the platform 20 is capable of supporting. Each block 78, 80 spacer may include at least one internal band. The four spacer blocks 78 comprise the outer spacer blocks 70 arranged around the periphery of the platform 20. Two outer spacer blocks 78 extend between the respective pairs of the long rods 28, 44, while two other outer spacer blocks 78 extend between the opposite short bars 30, 46. These outer spacer blocks 78 are preferably made of extruded aluminum materials and welded in place.

As perhaps best shown in Figure 8, the outer spacer blocks 78 have a generally D-shaped profile when viewed in cross section. This D-shaped profile includes an outer convex portion 82 that faces outwardly from the platform 20. In other words, as perhaps best shown in Figures 2 and 6, the convex portions 82 of the outer spacing blocks 78 face outward and so that if they are contacted by the tips of a forklift 24, they will gently steer the tips to the side usually with little or no damage. Preferably, although not necessary, at least one spacer block 80 comprises an interior spacer block 80 arranged for direct contact between the structure 34 and the joint 54 of lower inner section to provide a column force at the center of the platform 20. 80 block interior spacer can have a generally rectangular profile in cross section. Similar to the outer spacer block 78, the inner spacer block 80 is also preferably made of extruded aluminum material and welded securely in place at each end.

Figure 14 shows an exploded view of a first alternative embodiment of the corner piece 156, where similar or corresponding parts are indicated with reference to the reference numbers shifted by 100. In this example, the rear walls 160 are formed of Extruded aluminum and the upper and lower plates 162 are made of stamped aluminum sheet material then subsequently fixed to the rear walls 160 by welding or by another suitable fixing technique. Once assembled the upper plate 162 is generally flat with the upper side 22 and the lower plate 162 is generally flat with the lower side 40. The cover 164 in this example is formed integrally with the rear walls 160 during the extrusion process. The cover 164 is configured to simultaneously engage the rear walls 160 and the upper and lower plates 162 to provide a secure, solid exposed area for the corner piece 156. The cover 164 includes an outer edge 166 that establishes the main or terminal corner for the platform 20. A generous deformation of the grooves 168 in the cover 164 laterally may be formed on either side of the outer edge 166 to provide controlled collapse in the case of impact. The corner pieces 156 may further include internal framework 170 formed integrally during the extrusion process to join the cover 164 and the rear walls 160 for both resistance and to control the deformation. The corner pieces 156 are designed to absorb and deform when impacted without altering the upper 22 or lower sides 40. The upper and lower plates 162 provide a closed, ie hollow, space in the corner pieces 56 to resist infiltration by liquids or other unwanted substances. Each plate 162 may include a small orifice 172 aligned over an intersection point 174 of the framework 170. During the assembly process, the plates 162 are placed over the extruded body sections with the holes 172 which provide a convenient location through the whereby a small welding point is placed in the framework 170 and the plates 162 are thus secured in position.

Figure 15 shows a second alternative embodiment of the corner piece 256, where similar or corresponding parts are indicated with reference numerals displaced by 200. In this example, a simplified version of the corner piece 256 includes a separate cover 264 less sophisticated that can be secured in position to a back wall 260 of cast aluminum and the upper / lower plate construction 262. A single horizontal band 70 and the optional vertical intersecting band can be formed therein to improve its crushing strength. An RFID tag 58 may be placed within the hollow corner piece 256 and secured with a suitable adhesive or by other means as previously described.

Figure 16 shows yet another alternative construction for a corner piece 356, with similar or corresponding parts that are identified with similar reference numbers displaced by 300. In this example, the corner piece 356 is made of cast aluminum and omits the cover completely to present a hollow corner of open cell for the platform. In all other aspects, the corner piece 356 operates in a manner similar to that described in the foregoing.

The above description has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the embodiments described may become apparent to those skilled in the art and fall within the scope of the invention.

Claims

1. A metal platform of the type to support objects for storage and transport, the platform characterized because it comprises: a generally planar upper side having a substantially rectangular configuration defining four corners, the upper side including four elongated outer upper frame members, the upper side including a plurality of planking members arranged parallel to each other and in parallel to two of the outer upper frame members; a generally planar lower side having a substantially rectangular configuration defining four corners, the lower side including four elongated outer lower frame members, the lower side disposed below the upper side such that the upper side corners are vertically aligned on the corners of the lower side in corresponding pairs and the outer upper and lower outer frame members are arranged in opposite pairs; four generally hollow corner pieces, each of the corner pieces extending between a respectively aligned pair of the corners of the upper and lower sides, the corner pieces each interrupting the upper and lower sides generally flat in such a manner that the upper and lower sides do not overlap the corner pieces; Y each corner piece comprising a pair of adjacent perpendicular back walls in direct splice contact with the top and bottom sides, each corner piece further comprising a top plate and a bottom plate respectively fixed to the back walls, the plate upper generally flat with the upper side, the lower generally flat plate with the lower side, each of the corner pieces including a separately formed cover, the cover configured to simultaneously engage the rear walls and the upper and lower plates.

2. The platform according to claim 1, characterized in that the cover is made of a non-metallic material.

3. The platform according to claim 1, characterized in that each corner piece includes at least one vertical groove extending between the upper and lower plates.

4. The platform according to claim 3, characterized in that the cover includes at least one vertical groove to receive at least one vertical groove.

5. The platform according to claim 3, characterized in that each corner piece includes at least one horizontal groove extending between the rear walls and intersecting at least one vertical groove.

6. The platform according to claim 1, characterized in that each of the corner pieces includes a plurality of vertical grooves extending between the upper and lower plates.

7. The platform according to claim 6, characterized in that the cover includes a plurality of vertical notches to receive the plurality of vertical grooves.

8. The platform according to claim 1, characterized in that the upper and lower plates have respective outer edges, the outer edges of the upper and lower plates including a chamfer.

9. The platform according to claim 9, characterized in that the cover includes an outer corner section configured to engage the chamfers in the upper and lower plates.

10. The platform according to claim 1, further characterized in that it includes an RFID tag disposed in the hollow interior space of at least one of the corner pieces.

11. The platform according to claim 1, characterized in that the lower frame member is connected directly to the next adjacent lower frame member along a truncated miter joint.

12. The platform according to claim 1, characterized in that the upper part includes a structure arranged directly below each of the boarding members.

13. The platform according to claim 1, characterized in that the lower side includes a first inner lower frame member and a second inner lower frame member, the second inner lower frame member perpendicularly bisects the first inner lower frame member in a joint of lower intersection.

14. The platform according to claim 1, characterized in that it includes a plurality of spacer blocks, each of the spacer blocks extending perpendicularly between the upper and lower sides to keep the upper and lower sides generally spaced in parallel and aligned in relation to each other. yes.

15. The platform according to claim 14, characterized in that each of a spacer block includes at least one internal band.

16. The platform according to claim 14, characterized in that four of the spacer blocks comprise outer spacer blocks that extend directly between two opposite outer outer and lower outer frame members.

17. The platform according to claim 16, characterized in that the outer spacer blocks having a generally D-shaped profile in cross-section, the D-shaped profile of the outer spacer blocks including a convex portion facing outward from the platform .

18. The platform according to claim 14, characterized in that the upper part includes a structure arranged directly below each of the boarding members, wherein the lower side includes a first inner lower frame member and a second inner lower frame member , the second inner lower frame member perpendicularly bisects the first inner lower frame member in a lower intersecting joint, and wherein one of the spacer blocks comprises an inner spacer block, the inner spacer block extending directly between the structure and the lower intersection board.

19. The platform according to claim 18, characterized in that the inner spacer block has a generally rectangular profile in cross section.

20. A metallic platform of the type to support objects for storage and transport, the platform characterized because it comprises: a generally planar upper side having a substantially rectangular configuration defining four corners, the upper side including four elongated outer upper frame members, the upper side including a plurality of planking members arranged parallel to each other and parallel to two of the outer upper frame members, the upper part including a structure disposed directly below each of the board members; a generally flat lower side having a substantially rectangular configuration defining four corners, the lower side including four elongated outer lower frame members, each of the lower frame members directly connected to the next adjacent lower frame member along of a truncated miter joint, the underside including a first inner lower frame member and a second inner lower frame member, the second inner lower frame member perpendicular bisect the first inner lower frame member in a lower intersection joint; a plurality of extruded aluminum spacer blocks, each of the spacer blocks extending perpendicularly between the upper and lower sides to hold the upper and lower sides generally in parallel spaced apart and aligned in relation to each other such that the corners of the side The upper members are vertically aligned on the corners of the lower side in corresponding pairs and the upper outer and lower outer frame members are arranged in opposite pairs., each of the spacer blocks including at least one inner band, four of the spacer blocks comprise outer spaced blocks extending directly between two opposites of the outer outer and lower outer frame members, the outer spacer blocks having a profile generally in the form of D in cross section, the D-shaped profile of the outer spacer blocks including a convex portion facing outward from the platform, one of the spacer blocks comprises an inner spacer block, the inner spacer block which is extends directly between the structure and the lower intersecting joint, the inner spacer block having a generally rectangular profile in cross section; four generally hollow corner pieces, each of the corner pieces extending between a respective aligned pair of the corners of the upper and lower sides, the corner pieces each interrupting the upper and lower sides generally flat so that the upper and lower sides do not overlap the corner pieces, at least one of the corner pieces including an RFID tag in the hollow interior space thereof; Y each of the corner pieces comprises a pair of adjacent perpendicular back walls in direct splicing contact with the upper and lower sides, each of the corner pieces further comprising an upper plate and a lower plate respectively fixed to the rear walls, the generally flat upper plate with the upper side, the generally flat lower plate with the lower side, in at least one vertical groove arranged in each of the corner pieces and extending between the upper and lower plates, the upper plates and lower having respective outer edges, the outer edges of the upper and lower plates including a chamfer, each of the corner pieces including a cover, the cover configured to simultaneously engage the rear walls and the upper and lower plates, the cover that is made of a non-metallic material, the cover that includes at least one notch for Electing at least one vertical groove, the cover including an outer corner section configured to engage the chamfers in the upper and lower plates.