GB2100659A - Moulds for concrete or plaster - Google Patents

Abstract

An improved mould for the production of concrete or plaster structures comprises a metal mould 6 with a removable liner 3, the mould being preferably of steel and the liner preferably of vacuum-formed high-impact plastics. When used for the production of patterned concrete or plaster structures, the liner bears the pattern imprint. An object such as a garden urn may also be made by casting upside down between a metal mould and a liner. <IMAGE>

Description

SPECIFICATION Moulds for concrete or plaster.

The invention relates to improvements in moulds for the production of concrete or plaster structures.

Several type of mould are used for producing concrete pillars, posts, slabs or other structures and a variety of plaster structures.

Wooden moulds are cheap to make but give an unsatisfactory finish to the product and must be completely dismantled to release partially dried concrete which adheres to the wood. Moreover the concrete must dry in a mould and release agents, such as oil or paraffin based substances must be applied before the concrete becomes capable of release from the mould. Resin bonded glass fibre moulds are made by a time-consuming and therefore expensive process, their dimensions are often inaccurate so that the concrete products also cannot be of precise dimensions, and the moulds have a limited life span as they are rigid, brittle and often break on impact during demoulding or stripping operations.Resin bonded glass fibre moulds generally do not give a smooth finish to the product because when a filled mould is vibrated to release air bubbles from the concrete the friction set up between the concrete and the abrasive resin bonded glass fibre mould walls gives rise to a roughened surface on the dried product. Again, the concrete must dry in the mould before it becomes capable of release from the mould because the concrete generally adheres to the resin bonded glass fibre even when release agents are applied.

Steel moulds in the form of shallow trays with inclined sides have been proposed for producing slabs or panels of concrete for use for example, in industrial or domestic fencing, the inclined sides allowing rapid release of the concrete. Moulds for concrete pillars or posts cannot be formed with inclined sides as some products would not stack adequately and other products, for example fencing foundations, may be required to have recessed sides.

British Patent Specification No. 80/09756 describes a mould for such thicker concrete articles which also allow rapid release. Such a mould comprises a base with side and end plates hinged thereto along the whole length, and pegs on the side plates projecting through holes in the end plates and pins to project through holes in the pegs to lock the mould in the closed position for filling with concrete, the pins being removed and the side and end plates pivoted to swing open and release the concrete structure once it is sufficiently dried.

These steel moulds are relatively inexpensive to produce, they give a satisfactory smooth finish to the product and they allow releasing or demoulding of the concrete by a quick and easy operation when the concrete has only dried for a short period, for example 24 hours after being filled into a mould.

Steel moulds are, therefore, satisfactory for production of a basic, plain-surfaced concrete structure, but it is impractical to use steel moulds for the production of patterned concrete structures as the tooling required for patterning the steel mould is prohibitively expensive.

It has been proposed to produce patterned concrete structures, such as garden ornaments using a mould vacuum-formed preferably from high-impact plastics. The concrete products thus obtained are of high quality and can be rapidly released or demoulded, but the production of a master former which may be of steel, aluminium, resin, wood or other material, over which the plastics material is vacuum formed, is very expensive, although not as expensive as production of patterned steel moulds.

Wooden or resin bonded glass fibre moulds may be used for production of patterned plaster structures, for example for use in ceiling or wall ornamentation, or for production of patterned concrete structures, but the quality of the finish is generally poor due to adhesion between mould and plaster or concrete, and in the case of concrete other drawbacks associated with drying as have been mentioned above. Plaster generally only takes a few minutes to dry.

An object of the present invention is to provide a mould for the production of patterned concrete or plaster structures which is less expensive than present moulds but allows for equally rapid releasing or demoulding of concrete in terms of both the time from filling the mould to when the concrete is sufficiently dry to be released and the time taken for the releasing or demoulding operation itself, and also gives a product of equally high quality.

According to the invention a mould for the production of concrete or plaster structures comprises a metal mould holder to support the weight of the concrete in combination with a liner or envelope of a vacuum formed high impact plastics material being the pattern or ornament for stripping from the moulded concrete before the concrete is fully dry.

The invention also comprises a method for moulding the concrete structures.

The invention will be described with reference to the accompanying drawings: Figure 1 shows exploded perspective views of a flag stone slab, a mould liner and a metal mould holder for the mould liner.

Figure 2 is a section of the assembled parts shown in Fig. 1.

Figure 3 is a perspective view of a wall slab or panel and mould.

Figure 4 is a perspective view of a mould for a garden urn.

Figure 5 is a detail section on line 5-5 Fig.

4 showing the mounting of the inner and outer sides of the mould.

Figure 6 shows a detailed perspective view of an alternative modification for stacking the holders.

Figure 7 is a vertical section similar to Fig.

6 showing two stacked holders.

A metal mould holder for the production of a patterned concrete panel 4 for domestic or industrial fencing or a flag stone 2 is preferably of steel with a liner 3 preferably of vacuum-formed high-impact plastics. The mould may be in the form of a shallow tray 1 or it may be in the form of a deeper tray with releasable, hinged side and the plates as described in Specification No. 80/09756. The side plates may either be flat or recessed.

The mould is illustrated having a shallow rectangular steel tray of appropriate dimensions and approximately 5cm deep, with sides inclined to the vertical at an angle of 5-10, lined by a shallow liner 3 of substantially the same dimensions of vacuum-formed high-impact plastics in the base of which an appropriate pattern has been imprinted. The plastics liner 3 is approximately 3cm thick. The sides of the liner 3 are approximately 6cm high and turned outwards at the top to form a horizontal rim so that the sides and rim of the liner rise above the sides of the mould tray 1 thereby facilitating removal of the liner from the tray.

In use, the liner 3 is placed inside the mould tray 1 and concrete is poured into an appropriate depth.

The mould tray 1 is vibrated to remove air bubbles from the concrete and the surface of the concrete is levelled. The concrete is subsequently left in the line tray 3 resting in the mould tray 1 for several hours to attain a degree of dryness.

Then the mould tray is overturned and lifted away and the plastics liner 3 is peeled away from the semi-dry concrete slab 2 or 4 which is left to continue drying ready for sale and use.

Vacuum-formed high-impact plastics liners 3 are particularly advantageous as the material is durable, pliable, smooth surfaced and does not adhere to the semi-dry concrete so that the liner can be peeled away from the concrete in a rapid, e.g. 1 5 second, operation only a few hours after the filling of the mould.

The rigidity of the steel tray is required until the concrete has dried to a certain stage.

The mould trays or holders 1 are supported on rails 5 and provided with handles 6.

The metal mould trays or holders 1 may alternatively be stacked after use by the provision of feet 5" welded on the extended end walls of the tray to rest on buffers 5b of rubber or other resilient material on adjacent holders 1 as illustrated in Figs. 6,7 which reduce the noise during stacking.

Both trays 1 and liners 3 are reusable a number of times and liners with differing pattern imprints can be interchanged for the production of concrete structures bearing different patterns. If the sides or ends of the concrete are required to be patterned then the sides or ends of the liner are imprinted appropriately.

A garden urn is moulded upside down in a mould 7 formed with a metal mould holder 7" inside a plastics envelope 7b the equialent of a mould liner 3. The mould holder 7" supports the weight of the concrete as it is fed to the space between the mould holder 7" and the high impact plastics envelope 7b as shown by the arrows in Fig. 7.

The metal mould holder 7" and the envelope 7b are clamped together at their common diameter between rings 8 to prevent the escape of the concrete.

In use the envelope 7b is assembled outside the metal mould holder 7" and the two are clamped together by the rings 8 and concrete is poured into the space between the envelope and the metal mould holder as described with reference to Fig. 1. The concrete is left in the mould to attain a degree of hardness the clamping rings 8 are removed and the envelope is stripped from the concrete. The rigidity of the steel mould holder is required until the concrete has dried and the concrete urn is then removed therefrom. Both the envelope and the mould holders are reusable a number of times.

In further embodiments the moulds and liners or envelopes be of any other suitable dimensions and made of any other suitable material. The moulds may have sides which are flat or recessed and their sides and ends may be collapsible as described in Specification No. 80/09756.

The liner and envelope are preferably of vacuum-formed high-impact plastics, but it may be of any other vacuum-formed plastics, or indeed any other suitable material.

Claims (5)

1. A method for moulding concrete structures in a mould formed in two parts, a first part in the form of a liner or envelope ofa high impact plastics material and a second part in the form of a metal mould holder to support the weight of the concrete comprising applying the liner or envelope to the metal mould holder, supplying liquid concrete to the liner or envelope and mould holder, allowing the concrete to partially dry, stripping the liner or envelope from the concrete and finally removing the moulded concrete structure from the metal mould holder.

2. A method as in Claim 1 for moulding concrete flag stones or panels comprising placing the mould liner in a mould holding tray applying liquid concrete to the mould liner, allowing the concrete to partially dry, overturning the mould and stripping the liner from the moulded flag stones or panels.

3. A method as in claim 1 for moulding garden urns comprising placing the mould envelope over a metal mould holder and clamping the two together on their common diameters applying liquid concrete between the envelope and the metal mould allowing the concrete to partially dry and removing the clamping rings and stripping the envelope from the moulded urn.

4. A mould for carrying out the method of claim 1 comprising a metal mould holder to support the weight of the concrete in combination with a liner or envelope of a vacuum formed high impact plastics material bearing the pattern or ornament for stripping from the moulded concrete before the concrete is fully dry.

5. A mould for moulding concrete structures substantially as described with reference to the accompanying drawings.

5. A mould as in claim 4 for the production of flags or panels in which the mould holder is formed as a metal tray supporting the plastics lining, the lining having a rim for aid in removing the the plastics when partially dry.

6. A mould as in claim 4, for the production of garden urns in which the metal mould holder is in the shape of the urn and the envelope surrounds the mould holder and is clamped thereto on their common diameter.

7. A method for moulding concrete structures substantially as hereinbefore described.

8. A mould for carrying out the methods of claims 1-3 for moulding concrete structures substantially as described with reference to the accompanying drawings.

CLAIMS t6 Jul 1982)

1. A mould for the production of patterned or legend impressed concrete structures comprising a metal mould holder to support the weight of the concrete in combination with a patterned or legend impressed liner or envelope of a vacuum formed high impact plastics material formed with the pattern or legend for stripping from the moulded concrete before the concrete is fully dry to produce a smooth surfaced concrete structure.

2. A mould as in claim 1 for the production of flags or panels in which the mould holder is formed as a metal tray supporting the plastics lining, the lining having a rim for aid in removing the plastics when partially dry.

3. A mould as in claims 1 or 2 in which the liner of a high impact plastics material is formed with a pattern or legent to receive the concrete for the production of pattern slabs or other articles.

4. A mould as in claim 2, for the production of garden urns in which the metal mould holder is in the shape of the urn and the envelope surrounds the mould holder and is clamped thereto on their common diameter.