Abstract:
A process for encapsulating assemblies ( 21,41 ) from a plurality of sub-assemblies ( 1, 10; 32 ) is disclosed. Each sub-assembly is in turn formed by at least partial encapsulation thereby avoiding the need to glue, nail or otherwise secure the individual components ( 2 - 4, 11-12, 15; 31 ) of the sub-assemblies in place. The subassemblies can be easily stored and/or manipulated prior to the subsequent encapsulation step. The fabrication of a cable tray ( 21 ) including a number of wiring harness ( 1, 10 ) and a multi-tiered pallet ( 41 ) is specifically disclosed.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a multi-part articles fabricated using the ARMACEL (Registered Trade Mark) process. That process basically involves partially, or substantially completely, encapsulating an article with a layer, or a plurality of layers, of thermoformable plastics material.  
       BACKGROUND ART  
       [0002]     The ARMACEL process and apparatus for forming structural articles, especially from weak substrates such as polystyrene and cardboard, and articles so formed, are disclosed in the applicant&#39;s International PCT Patent Application No. PCT/AU95/00100 entitled “A method and apparatus for forming structural articles” (WO 95/23682), International PCT Patent Application No. PCT/AU96/00541 entitled “Layered Structural Article” (WO 97/09166) and International PCT Patent Application No. PCT/AU00/00250 (WO 00/59709)—the contents of all three of which are hereby incorporated into the present specification by cross reference. A further, presently unpublished specification is that of International Patent Application No. PCT/AU2004/00086 (which claims priority of Australian Patent Application No. 2003 903 211 lodged 25 Jun. 2003) which discloses the encapsulation of an interior member which is neither at least partially fluid permeable nor is perforated to become so. The disclosure of that specification is also hereby incorporated by cross-reference.  
         [0003]     These specifications disclose forming structural articles from a shape defining interior member and at least one external skin. The basic steps of the method comprise: 
        1. heating a thermoformable sheet intended to form the external skin,     2. bringing the heated sheet alongside the interior member,     3. applying a fluid pressure differential between opposite surfaces of the interior member and the sheet to conform the sheet to the shape of the interior member and mutually engage same, and     4. maintaining the fluid pressure differential until the sheet has cooled.        
 
         [0008]     The present invention arises as an unexpected further development of the ARMACEL process and arises in the following way. Where a single piece article is intended to be so encapsulated (whether partially or substantially completely) that article is able to be handled prior to encapsulation and, in particular, loaded into the apparatus and placed on a platen ready to be subjected to the encapsulating process.  
         [0009]     However, where the article to be encapsulated was itself formed from several pieces, then those pieces had to be held in their intended final configuration on the platen. This could be done in two ways. One way was to form the multi-piece article into its intended final configuration before it was placed on the platen and hold the pieces together in an at least semi-permanent fashion which was sufficiently robust to enable the platen placement to be carried out. For example, articles fabricated from polystyrene or cardboard pieces would be tacked or glued together so as to form the intended final assembly. Similarly, articles fabricated from timber pieces would be nailed or possibly screwed together so as to enable the assembled article to be placed on the platen. This use of fasteners and/or gluing was relatively time consuming (particularly waiting for some glues to dry) and the fasteners and/or glue did not contribute much to the strength of the finished product (instead this was fundamentally determined by the strength arising from the encapsulation).  
         [0010]     The other way was to assemble the multi-piece article on the platen itself. Depending upon the shape of the pieces, it was sometimes possible to allow the pieces to simply rest against each other and be held in their intended final configuration under the influence of gravity. Although this method can be successful, this course of action is fraught with the danger that the pieces may move during the application of the heated plastics skin, in which case the encapsulated article would not have the desired final configuration and would be ruined. Alternatively, the pieces could be tacked, nailed, or glued together as they were assembled on the platen. However, this was essentially not very different from the above described first way.  
       OBJECT OF THE INVENTION  
       [0011]     The object of the present invention is to find a way of increasing the rate of production of encapsulated multi-piece articles and, in particular, to avoid the disadvantages of nailing and/or gluing the various pieces together.  
         [0012]     Unexpectedly, it has been found advantageous to utilise the ARMACEL process itself in an intermediate or preliminary step in the overall process to hold together the component pieces of some assembly or sub-assembly.  
       SUMMARY OF THE INVENTION  
       [0013]     In accordance with a first aspect of the present invention there is disclosed a process of partially, or substantially completely, encapsulating a multi-part article with one or more sheets of thermoformable plastics, said process including, as an intermediate or preliminary step, the step of at least partially encapsulating at least two of said parts with a sheet of thermoformable plastics so as to maintain said at least two parts in a predetermined relationship or configuration, and said process further including, as a step subsequent to said intermediate or preliminary step, the step of further at least partially encapsulating said at least two parts together with a further part.  
         [0014]     In accordance with a second aspect of the present invention there is disclosed articles fabricated in accordance with the above disclosed method. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     Embodiments of the present invention will now be described with reference to the drawings in which:  
         [0016]      FIG. 1  is a perspective view of a first sub-assembly in the form of a wiring harness held in its final desired configuration prior to assembly,  
         [0017]      FIG. 2  is a perspective view of a second sub-assembly (again a wiring harness) also held in its final desired configuration prior to assembly,  
         [0018]      FIG. 3  is a side elevational view of a cable tray incorporating two of the first wiring harness sub-assemblies and a single one of the second wiring harness sub-assemblies,  
         [0019]      FIG. 4  is a cross sectional view through the cable tray of  FIG. 3 ,  
         [0020]      FIG. 5  is a perspective view of four individual pieces used to construct a modular height pallet cage,  
         [0021]      FIG. 6  is a perspective view showing the pieces of  FIG. 5  in their desired final assembly configuration and immediately prior to being partially encapsulated,  
         [0022]      FIG. 7  is a perspective view showing the completed partially encapsulated modular pallet cage prior to trimming,  
         [0023]      FIG. 8  is an exploded perspective view showing three of the partially encapsulated modular pallet cages stacked one above the other immediately prior to being fully encapsulated, and  
         [0024]      FIG. 9  is a cross sectional view showing a three tier encapsulated pallet cage. 
     
    
     DETAILED DESCRIPTION  
       [0025]     As seen in  FIG. 1 , a first wiring harness  1  is illustrated having two male plugs  2 ,  3  and a single male plug  4 . The plugs  2 ,  3  and  4  are interconnected by means of six wires  5  which are arranged in a generally Y-shaped configuration. Whilst in the desired Y-shaped configuration the wires  5  are subjected to the ARMACEL process and thus are partially encapsulated by a sheet of plastics  7  which bonds with the wires  5  and maintains them in the desired Y-shaped configuration.  
         [0026]     Similarly, as seen in  FIG. 2 , a second wiring harness  10  has two female plugs  11 ,  12  between which extend six wires  15  arranged in a generally U-shaped configuration. Again the wires  15  whilst in their desired U-shaped configuration are subjected to the ARMACEL process so as to be partially encapsulated by a sheet  17  of plastics material which bonds with the wires  15 . After the ARMACEL process is finished the sheet  17  is trimmed so as to create a circular aperture  19  indicated by broken lines in  FIG. 2 .  
         [0027]     It will be appreciated by those skilled in the wiring harness arts that the two harnesses  1 ,  2  can be inexpensively and easily fabricated using the ARMACEL process. In this way permanent sub-assemblies are fabricated which can be stored for later use and handled at will.  
         [0028]     Turning now to  FIG. 3 , a cable tray  21  having a central aperture  29  is provided with two of the first wiring harnesses  1  and single one of the second wiring harness  10  interposed therebetween. As illustrated in  FIG. 3 , a desired arrangement of interconnections and layout of wires  25  is achieved. Once the harnesses  1  and  10  are laid above the cable tray  21  which is in turn located on the platen of the apparatus to carry out the ARMACEL process, and the plugs  4 ,  11  and  12 ,  4  interconnected, the entire cable tray  21  can be subjected to the ARMACEL process. This is done firstly with a sheet  271  ( FIG. 4 ) from the side illustrated in  FIG. 3  so as to partially encapsulate the wires  5 ,  15  and  25  and the plugs  4 ,  11 ,  12  and  4  and bond the three harnesses  1 ,  1  and  10  to the cable tray  21 . Then the rear side (ie the side not seen in  FIG. 3 ) of the cable tray  21  is subjected to the ARMACEL process with a sheet  272  so as to produce the final completely encapsulated cable tray as illustrated in  FIG. 4 .  
         [0029]     In relation to  FIG. 4 , it is to be understood that the gap drawn between the individual sheets  271 ,  272  of plastics material is only so drawn for the purposes of illustration and does not exist in practice. Instead, the individual sheets  271 ,  272  are tightly drawn against, and bonded to, the adjacent objects.  
         [0030]     It will be apparent to those skilled in the wiring arts that the cable tray  21  offers a number of various substantial advantages. Firstly, it can be made in any configuration so as to, for example, adapt to those circumstances where the central aperture  29  in the cable tray  21  is required to mate with, or allow passage through of, some other object or protrusion. In addition, the wires  5 ,  15  and  25  are substantially entirely encapsulated and therefore protected against any vibration, the chaffing of insulation, and like problems which beset conventional cable trays. Furthermore, the inter-engaged plugs  4 ,  11  and  12 ,  4  are likewise fully encapsulated and thus remain permanently connected with no possibility of the electrical interconnection becoming dislodged as a result of vibration. In addition, the interconnected plugs are also effectively hermetically sealed and thus their contacts are not subject to corrosion. This is a particular advantage in marine environments since many conventional electrical insulation materials are permeable to water vapour whilst the plastic sheets  7 ,  17 ,  271  and  272  are, in general, completely impermeable to moisture.  
         [0031]     A second embodiment is illustrated in  FIGS. 5-9 . Here four individual rectangular slabs  31 , for example of polystyrene or cardboard, are arranged to form a wall unit or tier  32  of a modular pallet cage. As illustrated in  FIG. 6 , the slabs  31  are placed in their final position and a sheet  37  of plastics material used to partially encapsulate the slabs  31  and retain same in their final desired position. The result of this initial application of the ARMACEL process is illustrated in  FIG. 1  where the plastic sheet  37  is intended to be trimmed along the broken line  38 . In this way, the four individual slabs  31  are retained in their final desired configuration as an individual wall unit or tier  32 .  
         [0032]     As seen in  FIG. 8 , three of the individual tiers  32  can be positioned one above the other to create a pallet cage having three times the individual tier height. Once again a plastics sheet  471  is used to initially partially encapsulate the pallet cage  41 . The pallet cage  41  is then inverted and a second plastics sheet  472  used to partially encapsulate the pallet cage  41  in the opposite direction thereby leading to the final encapsulated pallet cage  41  as illustrated in  FIG. 9 .  
         [0033]     It will be apparent to those skilled in the art that the use of the ARMACEL process as an intermediate or preliminary step in assembling the final object confers a number of various substantial advantages over the prior art methods of gluing or nailing a sub-assembly together. In particular, the ARMACEL process is both speedy and inexpensive and thus considerable savings in time, in particular, are able to be achieved.  
         [0034]     The foregoing describes only some embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope of the present invention. For example, with certain configurations, assembly of the pieces of a multi-piece article without any glue, fasteners or pre-encapsulation is possible using the ARMACEL process, one embodiment of which is a nail-less pallet assembled from its constituent pieces utilising the process.  
         [0035]     The term “comprising” (and its grammatical variations) as used herein is used in the inclusive sense of “having” or “including” and not in the exclusive sense of “consisting only of”.