MX2013000709A - Metallic pallet with frame and panel support surface. - Google Patents

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 and a cruciform inner frame members (32, 34). The rails (28, 30) and inner frame members (32, 34) establish four bounded interior fields (38) which are filled with die cast aluminum quarter panels (84) the quarter panels (84) are stitch welded about their periphery to the inner edges of the rails (28, 30) and inner frame members (32, 34) to create an integral, rigid top side (22) which is easy to fabricate and exceptionally strong. An RFID tag (58) may be located in a hollow corner piece (56) for tracking purposes.

Description

METALLIC PLATFORM WITH FRAME AND SUPPORT SURFACE PANEL DESCRIPTION OF THE INVENTION The invention relates generally to horizontally supported flat surfaces such as industrial platforms having a supporting surface provided with support means by which a load can be supported relatively close to the floor and which has means to receive handling means below such surface or load and where the support surfaces are made of metal.

Platforms are commonly used to support and transport grouped objects or loads in similar application as 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 hazards, to name a few. More recently, platforms have been constructed of plastics materials which can be more durable than wood and are typically insect resistant, yet still subject to chemical contamination, fire risk and other deficiencies. Although the additives can be used to make a more flame-retardant plastic platform, such additives are costly and generally unfavorable in situations where food handling is required. There is a desire within the material handling industry to identify new materials suitable for manufacturing platforms that carry cargo which would provide a possibility superior to a competitive cost price with other options.

Some examples of platform constructions representative of the teachings of the prior art can be found in U.S. Patent No. 6,622,642 to Ohaneisan issued September 23, 2003, US 2006/0254478 to Kruger et al., Published November 16, 2006. , 'and US 2006/0201400 for Moore, Jr. et al., published September 14, 2006. These prior art examples illustrate various methods and mixed forms of construction 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 a single long integral panel or a panel connected variously 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 resistance of the platforms in terms of resistance to deformation forces. Deformation forces are generated when a platform experiences an impact force from one of its corners. This can happen when the platform is being transported by a forklift, 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 the wooden platform. The cost proposition for a metal platform therefore becomes favorable when the metal platform can be operated in specialized environments (for example, in food handling and other operations that require sterilization) and / or the metal platform can enjoy a life of service substantially longer than typical wooden platforms and other alternatives available. Therefore, with respect to the last consideration, constructing a metal platform that has the capacity to withstand the forces of deformation, rough handling and other conditions under tension are advantageous in the business proposal for this class of products.

With respect to the construction costs of a metal platform, there are two important factors that contribute: the cost of material and the cost of manufacturing. Of these, manufacturing costs are largely a controllable factor. Prior art pallet assemblies may include numerous components that must be assembled together with fasteners or welds at many points of intersection resulting in relatively high costs and efforts. As a result, manufacturing costs for a metal platform assembly can substantially overshadow material costs. Consequently, the metal platform has inherent benefits and is becoming increasingly accepted within an industry accustomed to using cheap wooden platforms. However, there remains an opportunity to further improve the platform designs and constructions with the objectives of reducing construction costs and extending service life.

A metal platform of the type for supporting objects to store and transport 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 first inner upper frame member, and a second inner upper frame member. The outer and inner upper frame members are arranged to form four unlimited inner fields. A generally planar lower side is provided having a substantially rectangular configuration defining four corners. 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 upper side corner in corresponding pairs. Likewise, the outer lower and outer upper frame members are arranged in opposite pairs. Four opposite corner pieces are provided. Each corner piece extends between a respectively aligned pair of corners of the upper and lower sides. The upper side further includes a rigid unitary corner panel fixedly disposed in each of the four delimited inner fields.

The subject invention is distinguished from the prior art platform designs by providing an upper side configured in a frame and panel type construction where four rigid, one-piece unitary panel pieces are set within and fixed to the member of the panel. frame. This design, which represents a departure from previous techniques, allows a metal platform assembly to be manufactured much more quickly and with less effort than required by previous designs. In addition, the unique design substantially increases the ability of a metal platform to resist deformation and other undesirable impact forces, which consequently extends the service life and therefore the cost benefit of a metal platform.

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

Referring 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 1.5240 cm (48 inches x 40 inches by .6 inches), however the specific dimension properties of the platform 20 are subject to alteration depending on the application.

As perhaps best shown in Figures 2-6, the platform 20 includes a generally planar upper side, generally indicated at 22. The upper side 22 establishes a generally horizontal surface to support objects such as cargo for storage and transportation. The upper side 22 rises above the floor or other structure under support 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 is a substantially rectangular configuration as suggested by the dimensions suggested in the foregoing, however, this is also 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 comprised of two long bars 28 and two short bars 30. The long bars 28 and short bars 30 are arranged around the perimeter of the upper side 22 and each extend in the notches 26 thus establishing a generally rectangular shape for the upper side 22. The long bars 28 and short bars 30 are preferably made of extruded aluminum having any desirable and suitable cross-sectional shape such as, for example, shown in the cross section of Figure 4. The upper side 22 further includes a first member 32 of the interior upper frame and a second member 34 of the interior upper frame. The inner upper frame member 32 is fixed parallel to and midway between the long bars 28, while the inner upper frame member 34 is arranged parallel to and midway between the short bars 30. The second interior upper frame member 34 perpendicularly bisects the first interior upper frame member 32 in a joint 36 of upper interior section, thereby establishing a somewhat cruciform construction insert within the perimeter of the bars 28, 30. The bars 28, 30 and the inner upper frame members 32, 34 are all disposed within a common plane, generally, which forms the horizontal supporting surface of the upper side 22. In this arrangement, four delimited interior upper fields 38 are formed. The four delimited inner fields 38 are the openings created by the surrounding frame members 28, 30, 32, 34, are generally equal in size and generally proportional to the general rectangular configuration of the upper side 22, as perhaps best shown in the Figure 2. Preferably, the inner upper frame members 32, 34 are fixed in such a way that when welding together in the joint 36 of upper inner section as well as at their end ends the respective long bars 28 and short 3, providing therefore a rigid matrix and generally fixing the shape of the delimited inner field 38.

Turning now to Figure 5, the platform 20 is shown including a generally flat lower side 40. The lower side 40, like the upper side 22It also has a substantially rectangular configuration having corners defined by the 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 can be directly aligned one over the other. The lower side 40 also includes 4 delimited outer frame members comprised of long bars 44 and short 46. The short bars 46 of the lower side 40 are generally congruent with the short bars 30 of the upper side 22, and likewise the long bars 44 of outer side are generally congruent with the long bars 28 on the upper side 22, unlike the bars 28, 30 on the upper side 22, however, in the preferred embodiment shown in Figures 4 and 5, the bars 44, 46 on the side 40 lower are significantly wider (measured laterally) than their long bar counterparts 28 and short 30 counterparts on the upper side 22. As a result, the long and 46 short bars 44 on the lower side 40 can, in one embodiment, directly connect to each other and at their terminal ends by a truncated miter joint 40. This 48 a-miter joint can be welded to provide a direct fixed connection between the long bars 44 and short 46. The lower side 40 further includes a first interior lower frame member 50 and a second interior lower frame member 52. The second inner lower frame member 52, perpendicularly bisects the first inner lower frame member 50 in a lower intersecting joint 54 which can be welded to secure the frame members 50, 52 to each other. Additionally, the terminal end of each of the first member 50 and second member 52 of the inner underframe can be attached at their respective ends to the inner edges of the long bars 44 and short 46 such as by welding to establish a strong matrix or construction skeleton.

Four generally identical hollow corner pieces are indicated at 56. The corner pieces 56 each extend between a respectively aligned pair of corners of the upper 22 and lower sides 40 as represented by their respective notches 26, 42. In other words, the corner pieces 56 fit into each of the notches 26, 42 and are there securely attached such as by welding so that they rigidly attach to the upper side 22 of the lower side 40 by a corner piece 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 bottom 40 generally flat so that the upper 22 and lower 40 sides do not they 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 configuration of the upper 22 and lower 40 sides.

Various configurations for corner pieces 56 can be found with reference in US 2010/0218705 co-dependent on the applicant, published on September 2, 2010, the full description of which is incorporated herein by reference and is used herein. Figure 7 is an exploded view of a corner piece 56 according to a preferred embodiment of the subject invention which is designed for optimum performance, low cost, ease of construction, as well as the ability to safely contain a RFID tag 58 (Figure 14) or other tracking features. The corner piece 56 shown here comprises an extruded 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, which in this example are made of material of stamped aluminum foil, are fixed respectively to the rear walls 60 such as by welding or by another suitable application technique. 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 load carrying capacity without increasing or decreasing the load stresses. A cover 64 is formed integrally with the rear walls 60 during the extrusion process. The cover 64 is configured to simultaneously engage the rear walls 60 and the lower top plates 62 to provide a secure, solid exposed area for the corner piece 56. The cover 64 includes an outer edge 66 that establishes the main terminal corner for the platform 20. Generous deformation notches 68 can be formed in the cover 64 laterally on either side of the outer edge 66 to provide a controlled collapse in an impact event. The corner pieces 56 may further include an internal framework 70 formed integrally during the extrusion process to join the cover 64 and the rear walls 60 for both resistance and to control the deformation. Through this design, the corner pieces 56 can be absorbed and deformed under the control of substantial impact force without stressing the upper 22 or lower sides 40 and thus helping to maintain their flat nature for the extended surface life of the platform 20. Lower upper plates 22 provide a closed, ie hollow, space in the corner pieces 56 for resistance and filtration by liquids or other unwanted substances. Each plate 62 may include a small hole 72 aligned on a stitch intersection point 74. During the assembly process, the plates 62 are placed on the extruded body section with the holes 72 providing a convenient location through which when a small welding point is placed on the framework 70 and consequently ensures the plates 62 in position.

As mentioned, an RFID tag 58 can be sealed within one or more of the corner pieces 56 to provide platform tracking and tracking capabilities. 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 substantially included for the interior of the corner piece 56. In this manner, the RFID tag 58 can be contained in a protected compartment to provide a long-term service life and functionally for the purpose of tracking the platform 20. If the RFID tag 58 is installed on 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 is preferably retained in a position spaced as far apart as possible from each of the rear walls 60 where the weld occurs during the attachment to the upper 22 and lower 40 sides. This will help protect the RFID tag 58 from damage due to excessive heat that occurs during welding operations. In contrast, the RFID tag 58 is also located as far as possible from the outer edges 66 where the majority of the deformation is expected to be present in use. This will help protect the RFID tag 58 from damage over a longer service life.

Figure 9 shows an exemplary highly schematic method by which the RFID tag 58 can be used to triangulate the position of a platform 20 which has been lost or possibly stolen. Using the known RFID technology, the loose positions of a platform 20 with respect to a digital map 76 can be determined. Of course, the map 76 may be specific to a particular manufacturing facility or warehouse, or be used more generally to track platforms 20 that can be stolen or lost in a much wider geographic area. The additional functionality can be incorporated into the RFID tag 58 according to the known art.

Returning to Figures 6 and 8, the platform 20 is shown including a plurality of extruded aluminum spacing blocks 78, 80. Each spacer block 78, 80 extends perpendicularly between the upper 22 and lower sides 40 to maintain the upper 22 and lower sides 40 in a generally parallel, spaced apart relationship with one another so that the notch corners 26, 42 remain vertically aligned and so that the corresponding pairs of the long bars 28, 44 and short ones 30, 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. Four spacer blocks 78 comprise the outer spacer blocks 70 disposed around the outer periphery of the platform 20. Two outer spacer blocks extend between the respective pairs of long rods 28, 44, while two other outer spacer blocks 78 extend between the two outer spacers 78. 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, outer spacer block 78 has a generally D-shaped profile when viewed in the cross section. This D-shaped profile includes an outer convex portion 82 that faces away from the platform 20. In other words, as perhaps best shown in Figure 2 and 6, the convex portion 82 of the outer spacing blocks 78 face outward and so that if they come into contact with the tips of a forklift 24, they will gently guide the ends to the sides usually with little or no damage. Preferably, although not necessary, at least one spacer block 80 comprises an inner spacer block 80 arranged for direct contact between the main structure 34 and the lower interior section seal 54 to provide a column strength in the center of the platform. The inner spacer block 80 may have a generally rectangular profile in cross section. Similar to the outer spacer block 78, the interior spacer block 80 is preferably also made of extruded aluminum material and welded securely in place at each end.

Referring again to Figure 2-6, the upper side 22 is shown including a rigid, quarter unitary panel, generally indicated at 84, fixedly disposed in each of the four delimited upper inner fields 38. The one-quarter panels 84 are preferably made of aluminum in a die-casting operation. In one embodiment, the top surface of the panels 84 of a room are generally flush with the upper surface of the outer frame members 28, 30 and interior 32, 34 to reduce the edges on the support surface that can engage the load. The outer peripheral edges of each panel 84 of a quarter are preferably welded to the outer frame members 28, 30 in directly adjacent interiors 32, 34. Spot welding is a suitable welding technique. The inner edges of the outer frame members 28, 30 and inner members 32, 34 can be formed with recesses similar to notches to receive the peripheral ends of the panels 84 of a room. The recesses, if used, mechanically strengthen the welded joints. All inner edges of each field 38, either recessed or not, are welded directly to the outer edges of each panel 84 of a quarter thereby substantially fortifying the upper side 22 with a relatively minimal amount of fabrication effort. By welding the outer edges of each panel 84 of a quarter on the bars 28, 30 and the upper and inner frame members 32, 34, an integral upper side 22 is created which has the ability to withstand the forces of expansion and contraction and other impacts that could otherwise deform the planar configuration of the upper side 22. As a result, the object platform 20 is substantially stronger than the design of the prior art and is considerably easier and faster to manufacture. The relatively long welding lines provided in the interconnection between the panels 84 of a quarter and the frame members 28, 32, 34 extending in the lateral longitudinal directions create an upper side 22 easily fabricated even solid able to have a life and Extended service operation when compared to the prior art constructions.

Each panel 84 of a room may include at least one, but as shown there are four handles 86 adjacent the interior upper frame members 32, 34. The handles 86 are formed integrally in the panels 84 of a room near the interior of the platform 20. By doing what is convenient for a person to transport the platform 20. Each panel 84 of a room can also include a plurality of lightening holes 88 for reduce the weight and cost of materials, providing ventilation and multiple drainage trajectories for liquids. The one-quarter panels 84 may further include a plurality of intersecting reinforcement ribs 90 to provide strength and resist deformation.

Figures 10-13 represent a first alternative design for the corner pieces 156, in this alternative embodiment, the previously established reference numbers are reused for convenience displaced by 100. As shown, the corner pieces 156 include the rear walls 160 perpendicular together with the upper and lower plates 162. However, in this embodiment, the rear walls 160 and plates 162 are formed as an integral assembly of aluminum or other suitable material. Here, the cover 164 is formed separately from a plastic or hard rubber material. The lattice 170 is not formed as part of the cover 164, but rather integral with the rear walls 160 and the plates 162. The cover 164 includes notches 192 for receiving or engaging the outer edges of the lattice 170, which is formed as three vertical grooves. The upper and lower plates 162 are also formed with chamfers 194. The outer edge 166 of the cover 164 is configured with short extensions to directly engage the chamfers 194 as perhaps shown in Figure 10. Through this design, the cover 164 and the cast aluminum components become mechanically interlaced so that the corner pieces 156 can partially absorb and collapse in response to the impact phase without deformation of the upper 22 or lower sides 40 and thus help maintain its flat nature for an extended service life of the platform 20. The hollow corner pieces 156, resist filtration by liquids or other unwanted substances.

Figure 14 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 construction of the upper / lower plate 262. A simple horizontal band 270 and the optional vertical intersecting band can be formed therein to improve the crush resistance. The RFID tag 58 can be placed within the hollow corner piece 256 with a suitable adhesive or by other means as previously described.

Figure 15 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 the cover as a whole to present a hollow corner of an open cell for the platform. In all other aspects, the corner piece 356 functions similarly to that described in the foregoing.

The above invention 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 (20)

1. A metallic platform of the type to support objects to store and transport, the platform characterized because it comprises: a generally planar upper side having a substantially rectangular configuration defining four corners, the upper side includes four elongated outer upper frame members, the upper side includes a first inner upper frame member, and a second inner upper frame member, the inner outer upper frame members being arranged to form four delimited inner fields; a generally planar lower side having a substantially rectangular configuration defining four corners, the lower side includes four elongated outer lower frame members, the lower side disposed below the upper side such that the corners of the upper side 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 corner pieces generally hollow each of the corner pieces extending between a respectively aligned pair of the corners of the upper and lower sides; Y the upper side also includes a unitary panel of a rigid room fixedly arranged in each of the four delimited inner fields.

2. The platform according to claim 1, characterized in that each panel of a quarter is made of a cast aluminum material in the mold.

3. The platform according to claim 1, characterized in that each one of the panels of a quarter is fixed on the recessed edges and welded to the directly adjacent outer and inner upper frame members.

4. The platform according to claim 1, characterized in that each panel of a room includes at least one adjacent handle of the upper and inner frame members.

5. The platform according to claim 1, characterized in that each panel of a room includes a plurality of lightening holes.

6. The platform according to claim 1, characterized in that the one-room panel includes at least one reinforcing groove on a lower side thereof.

7. The platform according to claim 1, characterized in that each one-quarter panel includes a plurality of intersecting reinforcement ribs.

8. The platform according to claim 1, characterized in that the four delimited inner fields are generally equal in size and generally proportional to the rectangular configuration of the upper side.

9. The platform according to claim 1, characterized in that each of the corner pieces interrupts the upper and lower sides generally flat in such a way that the upper and lower sides do not overlap the corner pieces.

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

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, further characterized in that it includes a plurality of spacer blocks, each of the spacer blocks extending perpendicularly between the upper and lower sides to maintain the upper and lower sides generally in parallel spaced and aligned in relation to each other. each.

13. The platform according to claim 12, characterized in that the spacer blocks comprise extruded aluminum members.

14. The platform according to claim 12, characterized in that the spacer block includes at least one internal band.

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

16. The platform according to claim 15, characterized in that the outer spacer block has a generally D-shaped profile in cross-section, the D-shaped profile including a convex portion oriented in a direction facing away from the platform.

17. The platform according to claim 12, characterized in that the second inner upper frame member perpendicularly bisects the first inner upper frame member in an upper intersecting joint, the lower side including a first inner lower frame member and a second inner member of inner lower frame, the second inner lower frame member perpendicularly bisects the first inner lower frame member in a lower intersecting joint.

18. The platform according to claim 17, characterized in that one of the spacer blocks comprises an inner spacer block, the inner spacer block extending directly between the upper and lower intersecting joints.

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 to store 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 first inner upper frame member and a second inner upper frame member, the second inner upper frame member perpendicularly bisecting the first inner upper frame member in an upper intersecting joint, the outer and inner upper frame members being arranged to form four delimited upper inner fields, the four delimited inner fields which are generally the same in size and generally proportional to the rectangular configuration of the upper side; 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 in a gasket. truncated miter, the lower side includes a first inner lower frame member and a second inner lower frame member, the second inner lower frame member perpendicular bisecting the first inner lower frame member in a lower intersecting joint; a plurality of 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 upper side are they align vertically on the corners of the lower side in corresponding pairs and the outer outer and lower outer frame members are arranged in opposite pairs, each of the spacer blocks including at least one internal band, at least two of the spacer blocks they comprise exterior spacer blocks that extend directly between two opposites of the outer upper and lower outer frame members, of the outer spacer block having a generally D-shaped profile in cross section, the D-shaped profile of the outer spacer block including a convex portion facing away from the platform, one of the spacer blocks comprising an inner spacer block , the inner spacer block that extends directly between the upper and lower intersecting joints, 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 in such a way that the upper and lower sides do not overlap the corner pieces; Y the upper side also includes a unitary panel of a rigid room fixedly disposed in each of the four delimited upper interior fields, each of the panels of a quarter are made of a material of cast aluminum in shell, each of the panels of a quarter which are welded to the directly adjacent outer and inner upper frame members, each of the panels of a room including at least one handle adjacent to the inner upper frame members, each of the panels of a quarter which include a plurality of lightening holes, each of the panels of a quarter include a plurality of intersecting reinforcing flutes.