GB2221643A

GB2221643A - Grids and other cellular panels

Info

Publication number: GB2221643A
Application number: GB8819112A
Authority: GB
Inventors: John Coleman; Rodger Twigger
Original assignee: VAC JAX Ltd
Current assignee: VAC JAX Ltd
Priority date: 1988-08-11
Filing date: 1988-08-11
Publication date: 1990-02-14
Anticipated expiration: 2008-08-11
Also published as: GB2221643B; GB8819112D0

Abstract

The panels, particularly for use as access platforms or walk-ways, are moulded from cold-cured phenolic resin which may include glass fibre reinforcement. A method of manufacturing such panels, eg a grid (10), uses a mould (12) shaped to define an open topped cavity complementary to the desired shape of grid, projections (14) of the mould corresponding to the dimensions of the grid apertures; the cavity being filled with the phenolic resin, curing agent and glass fibre or other reinforcement, if required, and the mix being allowed to cure in the mould before removal. Preferably at least the projections (14) of the mould are formed from plastics material eg low linear density polythene having greater thermal volume expansion than the mix during curing so that, on cooling, stripping from the mould is facilitated. A non-slip surface may be provided by rolling grit or the like (22) into the upper surface before curing of the latter has been completed. Cellular panels as defined also include panels having blind end pockets. <IMAGE>

Description

GRIDS #F;E) TZE CELLULF PAWLS This invention relates to trios and other cellular panels and to methods of manufacturing them.

The invention is particularly but not exclusively concerned with cellular panels in the form of grids having regular through apertures defined by criss-cross bar members. Typically the grids are used to form decking, walkways, access platforms and the like e.g. in industrial plant. chemical factories, oil refineries and similar process plants, oil rigs and platforms, cock and quay installations, navy and other shivs, and like environments where high resistance to corrosion and chemical reaction. maximum fire resistance, and hict strength and durability are particularly required.

However, the invention is not confined to crids whether for functional use in such environments or otherwise and the term cellular panels is used herein to include all forms of panel elements having through apertures whether uniform and/or arranged recularly or otherwise and/or having a honeycomb-type structure forme from regular or irregular series of blind ended sockets or pockets whether or not combined with through apertures, forming or serving as functional, structural and/or decorative or other elements, platforms, support surfaces, partitioning, ceiling or other grills, lattice screens or the like.

The object of the invention is to provide cellular panels which are economical and which fullfil the above mentioned requirements of durability and resistance to fire, corrosion and the like; and the provision of a method for their manufacture.

According to one aspect of the invention there is provided a cellular panel as herein defined which is moulded from cold-cured phenolic resin, preferably but not essentially including glassfibre reinforcement; and, where required for use as a walkway or access platform, which may further bE provided with non-slip surfacing of its upper face.

According to a further aspect of the invention there is provided a method of manufacturing cellular panels as herein defined including the steps of (a) providing a mould shaped to define a cavity complementary to the desired panel shape, the mould including a plurality of uniform or non-uniform projections from its floor corresponding to the cells and/or apertures of the panel; (b) filling the cavity with a mix of phenolic cold-cure resin, a com & atible curing agent for reaction therewith, and, if required, glassfibre or other reinforcement, in surrounding relationship to the projections. and (c) allowing the mix to cure in the mould to a solid state prior to stripping the mould therefrom involvinc the withdrawal of the projections out of the cells or apertures.

Preferably the mould, or at least said projections of the mould, are formed from a rigid or semi-rigid plastics material which does not coact with or bond to the curing mix and which has a substantially greater coefficient of thermal volume expansion than that of the mix during its rise in temperature due to the chemical reaction of curing; whereby on cooling following curing the projections release from the cells and/or apertures to facilitate their withdrawal therefrom. Said plastics material may be a low linear density polythene or other thermo-setting plastics material which is itself readily moulded to form the mould or mould components.

Said method may further include the step of providing a non-slip surfacing to an operatively upper face of the finished panel by rolling or otherwise pressing a slip resistant grit or other non-slip material precoated with uncured or part cured phenolic resin on to said upper surface before the curing of the latter has completed to bond said grit or other non-slip material intimately into said surface.

An example of the invention is now more particularly described with reference to the accompanying drawings wherein Figure 1 is a diagrammatic perspective view of a portion of a grid of the invention and a mould used for its manufacture from which it has just been released; and Figure 2 is a diagrammatic sectional view of a manufacturing stage in which a non-slip surfacing is being applied, The drawings show, by way of example, a cellular panel in the form of a grid 10 for use in forming industrial access walkways, decks or platforms, in this example consisting of regularly spaced sets of parallel cross members criss-crossing at right angles to define uniform regular square through apertures. However, it will be appreciated that other arrangements of cross members defining other shapes and sizes of apertures could be provided.

Grid 10 is manufactured in a mould 12 shaped and constructed to define an open topped cavity complementary to the shape of grid 10. Part only of the mould is shown in the drawings, it includes a plurality of uniform (in this example) projections 14 which are square in plan view to correspond substantially to the dimensions of the grid apertures and which taper slightly towards their upper ends to facilitate their withdrawal from the grid apertures.

Projections 14 stand up from a floor 16 of the mould which will be aligned horizontally in this example, the grid 10 being of uniform thickness. Said floor defines the under face of the finished grid.

At least those parts of the mould 12 which define the mould cavity, in particular the projections 14, are formed from low linear density polythene though it is possible that other thermoplastic materials having the properties referred to hereafter could be used.

Grid 10 is produced by fillip the mould cavity with a mix of a phenolic cold-cure resin and the appropriate quantity of curing agent for reaction therewith in known manner to form a solid phenolic plastics material without the necessity for any substantial application of heat or pressure. In this example the mix filling the mould cavity in surrounding relationship to projections 14 includes glassfibre reinforcement disposed to strengthen all the cross members of the finished grid.

The mould cavity is filled with the mix upto or immediately below the level of the tops of the projections 14, i.e. said tops are not covered with the mix in this example though if a cellular panel not having through apertures was required the filling of mix would be deeper so that it did extend over the tops of the projections to provide a continuous upper face of the panel as positioned in the mould, so forming blind ended sockets or pockets defined by bar members in the form of webs.

Curing by chemical reaction between the phenolic resin (which is usually water based) and the curing agent (which is usually acidic) will be initiated as soon as the mix is formed and the mix will remain in mould 12 until it has solidified.

While external heat is not essential to the curing process a warm ambient temperature may be provided for greater speed and thus more efficient use of the moulds in volume production.

It is a characteristic of cold-curing phenolic resins that the curing reaction tends to take place commencing at the interior or the mass of mix progressing to its outer faces, thus a central core of the grid cross members will tend to solidify before the upper and lower edges thereof have set.

In order to provide a non-slip surfacing for the upper face of grid 10 i.e. the upper edges of the cross members the manufacturing process, in this example, includes the further step of applying grit or other non slip granular material which has been precoated with uncured or part cured phenolic resin to said upper edges before the curing has completed i.e.before the upper edge regions of the cross members have solidified. Preferably said coated grit is rolled onto said upper edges as shown in Figure 2 to urge the grit into intimate contact with and so embed it partially in said upper edges as the curing is completed. In Figure 2 a roller 20 is shown passing across the open upper face of the filled mould 12 to effect this process, the grit being shown at 22.When the curing is complete the phenol resin coating of the grit will also fuly cure so that it will be intimately and permanently bonded in place. The rolling also helps in providing a uniform and generally level upper face of the finished grid as the reaction of curing otherwise tends to provide an uneven upper surface as any excess of curing agent may tend to migrate upwards in the mould and there may also be release of trapped air and other gases from the mix.

During the chemical reaction of curing the mix rises substantially in temperature and therefore expands in volume. However, the material selected for the mould, in particular the projections 14, i.e. preferably the low density polythene material, has a greater coefficient of volume thermal expansion than the mix, thus the projections 14 also expand substantially within the mix and, when curing is complete and cooling down has taken place said projections will contract more than the surrounding and now solidified grid cross members thus providing automatic release freeing the mould projections from the grid apertures. Thus the mould can then readily be stripped away from the finished grid withdrawing the projections from the apertures without any difficulty, further aided by the tapering of projections 14 referred to above.

This ensures that the mould is not damaged, distorted or over-stressed in use, the finished panel can be easily and speedily removed therefrom, and the mould is then available ready for immediate reuse so facilitatino continuous high volume manufacture in a particularly economical manner.

The grid 10 thus formed from the phenolic plastics material is non-flammable, is stable as having high integral strength and also being resistant to distortion or loss of strength when heated, and is also substantially inert and unaffected by an extremely wide range of corrosive chemicals and, in particular, petrocarbon and other solvents which would affect grids formed from other types of plastics material.

The phenolic materials are also more economical than many of the petro-chemical based plastics materials which have suffered great increases in price recently in common with world oil prices. There is further economy in that the strength and durability of the material, particularly with glassfibre reinforcement, means that a grid for a given service rating can be less in weight and of thinner section than known types of grid formed from other plastics materials.

There is also increasing concern at the fire hazard from grids formed by conventional processes and from other plastics materials, thus their use has hitherto been precluded in such situations as coal mines. The grids of the invention can be safely employed in such hazardous surroundings and they will also be particularly useful in ships, particularly warships, and in such hostile environments as oil platforms, sewage and effluent treatment plants, chemical factories and the like.

Claims

1. A cellular panel as hereinbefore defined moulded from cold-cured phenloic resin.

2. A panel as in Claim 1 including glass fibre reinforcement.

3. A panel as in claim 1 or 2 provided with a non-slip surfacing of its operatively upper face for use as a walk-way or access platform.

4. A panel as in Claim 3 where said non-slip surfacing comprises a grit or other non-slip material bonded into said upper face.

5. A panel as in any preceding claim in the form of a grid whose structure defines a plurality of through apertures.

6. A cellular panel substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

7. A method of manufacturing cellular panels as herein defined including the steps of: (a) providing a mould shaped to define a cavity complementary to the desired panel shape, the mould including a plurality of uniform or non-uniform projections from its floor corresponding to the cells and/or apertures of the panel; (b) filling the cavity with a mix of phenolic cold-cure resin, a compatible curing agent for reaction therewith, and, if required, glassfibre or other reinforcement, in surrounding relationship to the projections; and (c) allowing the mix to cure in the mould to a solid state prior to stripping the mould therefrom involving the withdrawal of the projections out of the cells or apertures.

B. A method as in Claim 7 wherein at least said projections of the mould are formed from a rigid or semi rigid plastics material which does not coact with or bond to the curing mix and which has a substantially greater coefficient of thermal volume expansion than that of the mix during its rise in temperature due to the chemical reaction of curing.

9. A method as in Claim 8 wherein said plastics material is a low linear density polythene or other thermo-setting plastics material.

10. A method as in claim 7,8 or 9 including the step of providing a non-slip surfacing to an operatively upper face of the finished panel by pressing a slip resistant grit or other non-slip material precoated with uncured or part cured phenolic resin onto said upper surface before the curing of the latter has been completed to bond said material intimately to said surface.

11. A method as in Claim 10 wherein said material is pressed onto said upper surface by rolling.

12. A method of manufacturing cellular panels as herein defined substantially as hereinbefore described with reference to the accompanying drawings.

13. A cellular panel manufactured by the method of any one of claims 7 to 12.