GB2264891A

GB2264891A - Filled structure

Info

Publication number: GB2264891A
Application number: GB9205032A
Authority: GB
Inventors: Ivan Cattaneo
Original assignee: Burlodge Ltd
Current assignee: Burlodge Ltd
Priority date: 1992-03-07
Filing date: 1992-03-07
Publication date: 1993-09-15
Also published as: GB9205032D0

Abstract

A method of making a structure at least partially filled with a foam comprising the steps of: 1 forming a structural member having at least a first surface and a second surface linked to leave a pressurisable plenum between the first and second surfaces; 2 locating the formed structural member in a pressurisable containment; 3 injecting into the plenum a material providing for the generation of a foamed material in the plenum; and 4 loading the formed structural member by applying a pressurised fluid within the containment to the first surface such as to resist deformation of the first surface arising from loading of the second surface arising from generation of foamed material in the plenum. Claims are also directed to apparatus for carrying out the method.

Description

FILLED STRUCTURE This invention relates to a filled structure and to a method of making such a structure. It is particularly, but not exclusively, concerned with a filled structure for use in an application where a temperature differential has to be maintained across the structure. Typically such a structure is needed in a refrigeration or a heating context commonly occurring in a domestic, commercial or residential catering application. Broadly such a structure is made up of a first region substantially separated from a second region by a third, insulating, region. The usual method of providing such a structure is to establish a first structure defining the first region, a second structure defining the second region and then, to a greater or lesser extent, filling a third region intermediate the first and second regions with an insulating material.

According to a first aspect of the present invention there is provided a method of of making a structure at least partially filled with a foam comprising the steps of: I forming a structural member having at least a first surface and a second surface linked to leave a pressurisable plenum between the first and second surfaces; 2 locating the formed structural member in a pressurisable containment; 3 injecting into the plenum a material providing for the genration of a foamed material in the plenum; and 4 loading the formed structural member by applying a pressurised fluid within the containment to the first surface such as to resist deformation of the first surface arising from loading of the second surface arising from generation of foamed material in the plenum.

According to a first preferred version of the first aspect of the present invention there is provided a method according to the first aspect wherein the step of loading includes varying in time the loading of the first surface substantially in dependence on the loading on the second surface.

According to a second aspect of the present invention there is provided apparatus for undertaking the method of the first aspect or the preferred version thereof comprising: 1 a fluid pressurisible containment; 2 operating means for pressurising fluid in the containment; 3 locating means for supporting a workpiece, containing a plenum volume in which a foamed material is to be generated, within the containment; 4 supply means for transferring material for generating foamed material into the plenum; and 5 regulating means for governing fluid pressure in the containment.

According to a preferred version of the second aspect of the present invention a control linkage is provided between the supply means and the regulating means to provide for the variation of the loading of a workpiece by way of fluid in the containment in dependence on loading arising from generation of foamed material in the plenum.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawing of a manufacturing unit for an insulated food dispensing trolley of which the sole figure is a perspective view part-cut away and part ghosted view.

As shown the tank 11 has walls 13, 14 and 15; lid 17 and base 18. The interior of the tank 11 is pressurised by way of line 19 from an air compressor 20. The maximum pressurisation that can be applied within the tank 11 by way of the compressor 20 is of the order of 1 bar. The actual pressure is regulated by way of a control unit 21 which senses the tank pressure by way of tube 22. The control unit 21 is linked to the operating controls 23 of the compressor 20 so that the control unit 21 can regulate the pressurisation of the tank 11 as will be described hereafter.

Wall 14 of the tank 11 is detachable from the rest of the tank 11 and incorporates a supporting jig 24 which provides for the location of a trolley body 25 which is a double walled structure having an inner wall 26 and an outer wall 27 bounding a plenum 28 extending around all but face 26A of the inner wall 26. Plenum 28 is initially empty when the body 25 is mounted on the jig 24 and the wall 14 is relocated on the tank 11. Interior volume 25A bounded by inner wall 26 communicates freely with the interior of the rest of the tank 11 so that the volume 25A and the rest of the tank are maintained at a common pressure. However the plenum 28 is isolated from the remaining pressure regime within the tank 11. The plenum 28 is coupled by lines 29, 30 to a pressurised foam component dispenser 31 whose output is regulated by a control box 32.

Once the body 25 is in place within tank 11 a predetermined amount of liquid foam constituents are fed into the plenum 28 by way of pipes 29, 30 resulting in the generation of foam throughout the plenum 28. The formation of foam results in loading of the inner surfaces of the outer wall 27 which under such loading would tend cause the walls 27 to bulge outwardly and walls 26 to bulge inwardly.

However a resistive loading is applied to the outer surfaces of the outer wall 27 and the inner side of wall 26 by way of increased air pressure fed to the tank 11 by way of line 19 from the compressor 20. This resistive loading serves to prevent bulging of the trolley wall while foaming is occurring.

A control link 33 between control box 32 of dispenser 31 and control unit 21 of compressor 20 serves to provide for synchronisation of the operations of dispensing and pressurisation. Typically a software program can be used to provide for efficient control of the process so that the minimum amount of foaming constituents are used and the system pressurised for a minimum length of time.

Once the foaming operation is completed the tank 11 is depressurised, the wall 14 is opened and the foamed body 25 is removed from jig 24 and replaced by an empty body to enable the foaming operation to be repeated.

While the exemplary embodiment is directed to the production of a plastic foam filling for a plenum surrounding 5 sides of a cube it will be apparent that the invention provides for the provision of a foam filling in simple shapes (such as a solid cube or sphere) up to elaborate shapes with re-entrant forms, curves and recesses. The main requirement is that the body has a plenum volume into which the foam can be injected, that the plenum volume is bounded by surfaces to which the overpressure can be applied by way of the containment fluid to resist the occurrence of bulging arising from the foaming process.

Claims

CLAIMS 1 A method of making a structure at least partially filled with a foam comprising the steps of: 1 forming a structural member having at least a first surface and a second surface linked to leave a pressurisable plenum between the first and second surfaces; 2 locating the formed structural member in a pressurisable containment; 3 injecting into the plenum a material providing for the genration of a foamed material in the plenum; and 4 loading the formed structural member by applying a pressurised fluid within the containment to the first surface such as to resist deformation of the first surface arising from loading of the second surface arising from generation of foamed material in the plenum. 2 A method as claimed in Claim 1 wherein the step of loading includes varying in time the loading of the first surface substantially in dependence on the loading on the second surface. 3 Apparatus for undertaking the method of Claim 1 or Claim 2 comprising:

1 a fluid pressurisible containment;

2 operating means for pressurising fluid in the containment;

3 locating means for supporting a workpiece, containing a plenum volume in which a foamed material is to be generated, within the containment,;

4 supply means for transferring material for generating foamed material into the plenum; and

5 regulating means for governing fluid pressure in the containment.

4 Apparatus as claimed in Claim 3 wherein a control linkage is provided between the supply means and the regulating means to provide for the variation of the loading of a workpiece by way of fluid in the containment in dependence on loading arising from generation of foamed material in the plenum.

5 A method of making a structure at least partially filled with a foam as hereinbefore described with reference to the accompanying drawing.

6 Apparatus for undertaking the method of Claim 5 as hereinbefore described with reference to the accompanying drawing.