GB2353755A

GB2353755A - Method of manufacturing a hollow product

Info

Publication number: GB2353755A
Application number: GB0015652A
Authority: GB
Inventors: Jolyon Eric Emery
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-07-09
Filing date: 2000-06-28
Publication date: 2001-03-07
Anticipated expiration: 2020-06-28
Also published as: GB0015652D0; GB2353755B; GB9916158D0

Abstract

A hollow product, such as a garden patio fireplace, is made by a method which employs an inflatable member 7 which, when inflated, has an external surface corresponding substantially to the internal shape of the hollow product to be produced. A settable material is applied to the external surface of the inflated inflatable member 7 to form the desired hollow product, the hollow product having at least one aperture 5 therein. After the settable material has set, the inflatable member 7 is deflated and removed through the at least one aperture 5 of the hollow product. A reinforcing mesh 1 may be incorporated between the inflatable member 7 and the settable material.

Description

2353755 - 1 METHOD OF MANUFACTURING A HOLLOW PRODUCT This invention

relates to a method of manufacturing a hollow product such as a garden patio fireplace.

Hollow products are generally manufactured by means of moulding within an external mould or by hand, as by throwing a pot on a potters wheel or the like.

Moulding permits precise replication, but it is difficult to incorporate any form of strengthening into the moulded product or to introduce any individuality into the configuration of the resulting product. Pot throwing also does not permit the incorporation of any form of 15 strengthening into the resulting product and, additionally, it is difficult successfully to throw large pots and to produce products to relatively constant dimensions. It is therefore an object of the present invention to 20 provide a method of manufacturing a hollow product which overcomes. or at least ameliorates, the abovementioned disadvantages. According to the present invention there is provided a 25 method of manufacturing a hollow product comprising the steps of:

providing an inflatable member which, when inflated, has an external surface corresponding substantially to the internal shape of the hollow product to be produced; applying a settable material to the external surf ace of the inflated inflatable member to form the desired hollow product, the hollow product having at least one aperture therein; allowing the settable material to set; and deflating the inflatable member and removing the deflated inflatable member through the at least one aperture of the hollow product. 15 The method may include the further steps of providing a reinforcing support having a shape conforming substantially to the shape of the hollow product and of inflating the inflatable member within the reinforcing support. In this 20 way, when the settable material is applied to the external surface of the inflatable member the reinforcing support is integrated into the hollow product. The reinforcing support may comprise a mesh, such as of a wire or plastics material. 25 The settable material may be selected from clay, fireclay, cement, plaster, resin, plastics and mixtures thereof. The settable material may incorporate a filler such as sand or other silica based materials, aggregate and crushed materials such as crushed house bricks or firebricks. The settable material may incorporate or have applied thereto a waterproofing material, such as an acrylic material, to render the settable material non-porous. The settable material may incorporate or have applied thereto a colouring agent. The colouring agent may comprise the waterproofing material. The settable material may incorporate a filamentary reinforcing -material, such as a plurality of filaments of high-temperature material. The reinforcing filaments may comprise metal filaments, such as mild steel or stainless steel.

The inflatable member may have a layer of a compressible is material on the external surface thereof. The compressible material may comprise a fibrous material, such as a rope.

The inflatable member may comprise a fabric layer and an elastomeric layer.

The method may include the step of positioning the inflatable member within a mould, for example a multi-piece mould, prior to applying the settable material.

The inflatable member may be tethered to a base region of the mould.

The method may include the step of arranging a plurality of stabilising members within the mould for stabilising the location of the inflatable member within the mould. The stabilising members may comprise a disc portion for engaging against the inflatable member and a pin for extending through the mould. The mould may be provided with means for locking the stabilising members in position.

The method may include the step of providing a resilient member, for example of rubber material, adjacent to the internal surface of the mould.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which:

Figure 1 shows a reinforcing support for one embodiment of a hollow product to be made according to the present invention; Figure 2 illustrates an inflatable member in the form of a balloon inflated within the reinforcing support; Figure 3 illustrates the reinforcing support with the balloon therein and with material forming a hollow product being applied to the balloon; Figure 4 illustrates the finished hollow product with the balloon removed; Figure 5 is a partial cross-sectional view illustrating one method by which an inflatable member, or balloon, for use in the present invention can be made; Figure 6 is a partial cross-sectional view illustrating another method by which an inflatable member can be made; Figure 7 is an elevational view, partly cut away, illustrating a further method by which an inflatable member can be made; and Figure 8 is an elevational view, partly cut away, illustrating a further method by which a hollow product according to the present invention may be made.

Figure 1 shows a first step in the manufacture of a hollow product according to the method of the present invention, the hollow product being in the form of a patio warmer (or fireplace). As can be seen from Figure 1, a reinforcing support 1 in the form of wire mesh is made substantially to the shape of the desired hollow product such that the reinforcing support can be incorporated within the wall of the hollow product. Alternatively the reinforcing support may be made from metal bars, wires or even non-metallic materials depending on the intended use of the hollow 1 1 product. As can be seen f rom Figure 1, the reinforcing support is formed with a first aperture 3 (to allow smoke to exit and to create in use a f low of air through the fireplace) at the top thereof and with a second aperture 5 (to allow heat to be radiated through the aperture, to permit fuel to be added to a fire within the fireplace and to create in combination with the first aperture 3 a f low of air through the fireplace) in a side of the reinforcing support.

In a second step shown in Figure 2, an inflatable member 7 in the form of a balloon is inserted into the reinforcing support 1 through one of the apertures 3, 5 (f or example the aperture 5) and is inflated such that the inflatable member is, or at least can be, spaced a short distance within the reinforcing support 1.

In a third step shown in Figure 3, the patio fireplace is formed by moulding a high-temperature-resistant material around the inflatable member 7 so as to incorporate the reinforcing support 1 within the wall 9 of the fireplace.

Thus the inner surface of the wall of the fireplace conforms to the outer surface of the inflatable member 7, while the outer surface of the wall 9 of the fireplace can be given whatever finish is required. Thus, the inner surface may be substantially smooth or may be contoured to a desired configuration, for example to permit one of more grills or shelves to be supported in order that the product 7 can be used as a barbecue or the like. The outer wall can, for example, be left smooth or can be decorated in any way chosen by the manufacturer. For example, the outer wall can be decorated manually or may be decorated by the application of moulds to the outer surface or even by the application of further moulded components thereto.

The material forming the wall of the hollow product may comprise any suitable settable material depending on the intended use of the hollow product. For example, suitable materials may include cold casting materials such as clay, fireclay, cement, plaster, resin, plastics material or the like. Where the hollow product is required to withstand an elevated temperature, such as in the case of a patio fireplace, clearly the material will be able to withstand such elevated temperatures. The settable material may incorporate one or more fillers such as sand or other silica based materials, aggregate and crushed materials such as crushed house bricks or firebricks. A waterproofing material, such as an acrylic material or the like, may be incorporated into or applied to the settable material to render the material, when set, non-porous.

Further, a colouring agent such as a pigment, paint, powder or liquid, may be incorporated into or applied to the settable material in order to produce a desired colour in the final hollow product. The waterproofing material may also comprise the colouring agent. Any material applied to the settable material may, of course, be applied after setting.

Once the settable material has solidified, the inflatable member 7 is deflated and removed through one of the apertures 3, 5. The inflatable member can then be inserted into a further reinforcing support 1 and employed to form a further hollow product.

By manufacturing a hollow product in the manner described it is possible to incorporate a reinforcing support into the wall of the hollow product. Thus, the reinforcing support becomes an integral part of the hollow product, providing additional strength and mechanical stability.

is Thus, even if the wall of the hollow product should crack, the reinforcing support maintains the mechanical integrity of the product and ensures the product does not collapse.

The use of an inflatable member simplifies the manufacture of the hollow product as compared with traditional pot throwing techniques in that the inflatable member supports the material of the wall of the product while ensuring substantial uniformity of internal dimensions between products. On the other hand, the external surface can be shaped by hand giving the possibility of a unique appearance to each product.

Clearly the manufacturing process described is not limited to patio fireplaces, but can be applied to a wide range of 9 products provided, in each case, there is an aperture sufficient to allow the deflated inflatable member to be removed from the hollow product. Indeed, the use of a reinforcing support is not required in all cases. For example, where the resulting hollow product is not intended for use at elevated temperatures the material forming the wall of the hollow product will not be subjected to thermal stresses and is unlikely to crack. It is therefore practicable to manufacture products to substantially constant dimensions while permitting the manufacturer to apply individual configurations to the external surface of the hollow product.

The cross-sectional view shown in Figure 5 illustrates diagrammatically one way in which the inflatable member 7 can be made. A mould is made for the inflatable member, the mould comprising a support 11, such as of wire mesh or the like, having applied thereto a continuous impervious surface layer 13 to render the support and surface layer substantially rigid and having an external configuration conforming substantially to the internal shape of the hollow product to be produced. In practice the impervious surface layer may comprise a layer of papier machd which is coated with varnish or the like. A release layer 15 is then applied to the impervious surface layer, the release layer comprising for example a plastics film such as that known as "cling film". A f lexible support 17 for the inflatable member 7 is then applied to the release layer 15, the flexible support comprising stocking or cr6pe material for example. An elastomeric layer 19 is then applied to the flexible support 17, for example by painting, spraying or dipping, the elastomeric material comprising a rubber-like compound such as latex or silicone rubber. Once the elastomeric layer is continuous and of sufficient thickness, a layer 21 of a compressible material is applied to the external surface of the elastomeric layer 19. The compressible material conveniently comprises a fibrous material such as a rope which is wound around the elastomeric layer and secured thereto, for example by means of a suitable adhesive. The compressible material allows the settable material of the hollow object to pass through the reinforcing support 1 in order that the settable material should best penetrate through the reinforcing support and incorporate the reinforcing support in the wall of the hollow product. A valve mechanism (not shown) is then fitted to the inf latable member to allow it to be inflated and deflated.

The mould is removed from within the inflatable member by making an incision through the inflatable member, crushing the mould into a small ball, and removing the ball through the incision. The incision is then repaired in the same manner as one would repair a puncture.

The inflatable member can then be used repeatedly in the manufacture of the desired hollow products.

Alternatively, as shown in Figure 6, an inflatable member 27 may be made by providing a mould 25 having an impervious surface layer, for example made of a reinforced cured resin material or the like (for example, glass reinforced plastics). A release layer 29 may optionally be applied to the mould. A flexible layer 31 is then applied to the mould, the flexible support comprising a fabric material such as muslin. An elastomeric layer 33 is then applied to the flexible layer 3 1, for example, by painting, spraying or dipping, the elastomeric material comprising a rubber like compound such as latex or a silicone rubber. once the elastomeric layer is continuous and of sufficient thickness, the inflatable member is slit a sufficient extent to allow the inflatable member to be removed from the mould, the inflatable member then being sewn up and sealed and a valve mechanism is inserted to allow the inflatable member to be inflated and deflated.

As a further alternative, as shown in Figure 7, an inflatable member 37 can be made by producing a fabric form 39 tailored (cut and sewn) substantially to the desired shape. The fabric may be, for example, calico. A balloon 41 is then inflated within the fabric form and the fabric form 39 is covered with elastomeric, material 43 as described hereinbefore to produce the desired inflatable member. The balloon 41 can then be burst to deflate the same and can be removed through a small aperture in the inflatable member 37 which can readily be closed and a valve mechanism can be inserted.

As shown in Figure 8, hollow product according to the present invention (in the form of a patio warmer or barbecue) is made by arranging an inflatable member 57 as described hereinbef ore into a multi-piece mould 51 (the mould comprising, for example, a base and two or three upper mould components secured together such as with bolts). No separate reinforcing member is used, but the settable high-temperature-resistant material 53 has added thereto a plurality of reinforcing filaments, for example in the form of metal (e.g. mild steel or stainless steel) strands. of course, the reinforcing filaments can be of any suitable high-temperature-resistant material. Indeed, reinforcing filaments of different dimensions (length and/or diameter) and materials can be employed if desired.

The multi-piece mould 51 may be made, for example of glass reinforced plastics material.

A problem with employing an inflatable member 57 within a mould 51 is that the inflatable member tends to rise within the mould once the settable material has been poured in:

this is simply because the specific gravity of the inflatable member is less than that of the settable material. This problem can be overcome by stabilising the inflatable member within the mould. The inflatable member can be stabilised in a number of ways. For example, the 13 - inflatable member can be tethered to the base of the mould to prevent it rising. Further, the elongate portion of the inflatable member (which forms the chimney of the hollow product) can be stabilised against lateral movement by providing a plurality (for example three) of stabilising members 55 around the circumference of the mould. The stabilising members may comprise means for engaging the inflatable member, such as a disc or the like, and a pin for extending through the mould to the external surface thereof. Means (not shown), such as a locking member, may be provided to urge the pin towards, and therefore the disc into contact with, the inflatable member, or at least to maintain the disc in contact with the inflatable member.

However, the inflatable member 57 still tends to distort and it is therefore desirable additionally to provide further stabilising members 55 around the upper region of the lower (bulbous) part of the hollow product in order to minimise any such distortion. The further stabilising members may be mounted in the same way as the f irst mentioned stabilising members 55. Thus, the stabilising -members ensure the inflatable member is spaced a sufficient distance f rom the inside of the mould.

once the hollow product has been manufactured and removed from the mould and the inflatable member has been deflated and removed, the discs, and thus the pins, can be removed from within the hollow product.

14 - The use of a substantially rigid multi-piece mould allows accurate reproduction of the internal surface of the mould as the external surface of the hollow product. However, in order to ensure release, the internal surface of the mould needs to be substantially smooth and cannot be textured.

Thus, the hollow product requires a further treatment step if the surface thereof is to be textured.

This problem can be overcome if a resilient member (not shown), such as a rubber material (including polyurethane, silicone or latex rubber, for example), is positioned as an interlayer between the hollow product being moulded and the inside surface of the substantially rigid mould. The external surface of the hollow product will then assume the is texture of or applied to the surface of the resilient member. Because it is flexible, the resilient member can readily be removed from the hollow product after moulding.

is -

Claims

1. A method of manufacturing a hollow product comprising the steps of: 5 providing an inflatable member which, when inflated, has an external surface corresponding substantially to the internal shape of the hollow product to be produced; applying a settable material to the external surface of the inflated inflatable member to form the desired hollow product, the hollow product having at least one aperture therein; 15 allowing the settable material to set; and deflating the inflatable member and removing the deflated inflatable member through the at least one aperture of the hollow product. 20

2. A method according to claim 1 and including the further steps of providing a reinforcing support having a shape conforming substantially to the shape of the hollow product and of inflating the inflatable member within the 25 reinforcing support.

3. A method according to claim 2, wherein the reinforcing support comprises a mesh.

4. A method according to claim 3, wherein the mesh is of a wire or plastics material.

5. A method according to any preceding claim, wherein the settable material is selected from clay, fireclay, cement, plaster, resin, plastics and mixtures thereof.

6. A method according to claim 5, wherein the settable material incorporates a filler.

7. A method according to claim 6, wherein the filler is selected from sand and other silica based materials, aggregate and crushed materials such as crushed house bricks or firebricks and mixtures thereof.

8. A method according to claim 5, 6 or 7, wherein the settable material incorporates or has applied thereto a waterproofing material to render the settable material non porous.

9. A method according to claim 8, wherein the waterproofing material comprises an acrylic material.

10. A method according to any one of claims 5 to 9, wherein the settable material incorporates or has applied thereto a colouring agent.

17 -

11. A method according to any one of claims 5 to 10, wherein the settable material incorporates a filamentary reinforcing material.

12. A method according to claim 11, wherein the filamentary material comprises a plurality of filaments of high-temperature-resistant material.

13. A method according to claim 11 or 12, wherein the 10 reinforcing filaments comprise metal filaments, such as mild steel or stainless steel.

14. A method according to any preceding claim, wherein the inflatable member has a layer of a compressible material on 15 the external surface thereof.

15. A method according to claim 14, wherein the compressible material comprises a fibrous material, such as a rope.

16. A method according to any preceding claim, wherein the inflatable member comprises a fabric layer and an elastomeric layer.

17. A method according to any preceding claim and including the step of positioning the inflatable member within a mould prior to applying the settable material.

18 - 18. A method according to claim 17, wherein the mould comprises a multi-piece mould.

19. A method according to claim 17 or 18 and including the step of tethering the inflatable member to a base region of the mould.

20. A method according to claim 17, 18 or 19 and including the step of arranging a plurality of stabilising members within the mould for stabilising the location of the inflatable member within the mould.

2 1. A method according to claim 20, wherein the stabilising members comprise a disc portion for engaging is against the inflatable member and a pin for extending through the mould.

22. A method according to claim 20 or 21, wherein the mould is provided with means for locking the stabilising members in position.

23. A method according to any one of claims 17 to 22 and including the step of providing a resilient member adjacent to the internal surface of the mould.

24. A method according to claim 23, wherein the resilient member comprises a rubber material.

r

25. A method of manufacturing a hollow product substantially as hereinbefore described with reference to the accompanying drawings.