GB2442212A

GB2442212A - Casting mould

Info

Publication number: GB2442212A
Application number: GB0619318A
Authority: GB
Inventors: Lee James Rumley; Dale Jeffries
Original assignee: AIRFORME PRODUCTS Ltd
Current assignee: AIRFORME PRODUCTS Ltd
Priority date: 2006-09-29
Filing date: 2006-09-29
Publication date: 2008-04-02
Also published as: GB0619318D0

Abstract

A mould (10) (figure 1 - not shown) for wet casting a concrete product comprises a rigid base member 14 and a flexible polyurethane upper member 12. The upper member 12 is cast onto the base member 14, and surface features, for example, apertures 18, 20 and a groove 22, are cut into the base member 14. The polyurethane of the upper member is cast into the surface features, which increases the mechanical key between the base member and the flexible upper member 12.

Description

I

TITLE: MOULD The present invention relates to a mould and particularly but not exclusively to a mould for wet casting concrete products.

Concrete products, for example, paving slabs are typically manufactured by casting wet concrete in a mould. The wet concrete is poured into the mould, which has a base and sides. The mould is then vibrated, for example on a vibrating table, in order to displace air pockets in the concrete. As the concrete settles in the mould, the air is forced upwards and out of the concrete through the open side of the mould. The concrete is then allowed to dry. Drying can be accelerated by mixing additives with the concrete aggregate or by heat, as required. Finally, the product is demoulded, either by manually peeling the mould away from the moulded product, or by lifting the product out of the mould using a vacuum lifting head. The invention is concerned with a mould for use with an automatic vacuum demoulder.

The mould is typically made from polyurethane or Acrylonitrile Butadiene Styrene (ABS) plastic. Ideally the mould has to be sufficiently flexible to allow unimpeded removal of the moulded product from the mould, but sufficiently rigid to be retained, substantially un-deformed, on the bed of a wet cast concrete machine whilst the vacuum lifting head of the automatic demoulder lifts the product out of the mould.

ABS plastic moulds are presently preferred over polyurethane moulds because of their greater rigidity. When automatic demoulding, a hold-down frame is placed over the moulds and secured to a carrier frame of the wet cast concrete machine. This ensures that the mould does not lift upwards as the product is demoulded by the vacuum head.

A problem of this method is that each hold-down frame is sized to fit a particular mould.

In a typical working shift, for example over 8 hours, the hold down frame may be changed nine times, in order to allow demoulding of different products from different sized moulds. The hold down frame can take up to ten minutes to change, resulting in typically over an hour of down -time in any one working shift.

According to a first aspect of the present invention there is provided a mould for casting concrete products comprising a rigid base member and a flexible upper member, a moulding area formed in the flexible upper member for receiving material to be moulded, and the flexible upper member being permanently fixed to the rigid base member.

Preferably the flexible upper member is formed from polyurethane.

The rigid base member may be made from wood, and is preferably made from plywood.

The mould is advantageous in that it utilises a flexible material for the moulding area, and a rigid material for the base, giving the mould enhanced flexibility where required, and enhanced rigidity where required. The forming of the flexible upper member onto the base member also provides a stable mould, which is highly durable.

Preferably the rigid base member extends beyond an outer edge of the flexible upper member on at least two opposing sides of the flexible upper member. This enables the mould to be easily handled and restrained without damaging or obscuring the flexible upper member.

Preferably at least one surface feature is cut into the surface of the ngid base member, and the material from which the flexible upper member is made, is formed onto the rigid base member and into the surface feature.

This increases the strength of the fixing between the flexible upper member and the rigid base member.

The surface feature may comprise at least one aperture provided through the rigid base member, and the material of the flexible upper member may be formed through the aperture.

Preferably a plurality of apertures are provided through the rigid base member and the material of the flexible upper member is formed through all of the apertures.

The rigid base member and the flexible upper member may both be substantially rectangular in shape. The flexible upper member may be square.

The rigid base member may be sized to fit a machine, and may be typically larger in both its planar width and length dimensions than the flexible upper member.

Apertures may be provided through the rigid base member adjacent each of the four corners of the flexible upper member.

The surface feature may also comprise at least one recess disposed in the upper surface of the rigid base member and the material of the flexible upper member may be formed into the recess.

The recess is preferably a groove and the sides of the groove are preferably disposed at an angle inclined to the upper surface of the rigid base member.

The sides of the groove are preferably inclined at an angle of between 70 and 85 degrees to the plane of the upper surface of the rigid base member.

This enhances the mechanical connection between the flexible upper member and the rigid base member, because the slot acts as an undercut.

The groove may extend into the base member at a position adjacent the periphery of the flexible upper member.

According to a second aspect of the present invention there is provided a method of manufacturing a mould for casting concrete products comprising forming a flexible upper member onto a rigid base member, the flexible upper member having a moulding area for receiving material to be moulded.

Preferably the flexible upper member is formed from polyurethane.

Preferably at least one surface feature is cut into the surface of the rigid base member.

and the material from which the flexible upper member is made, is formed onto the rigid base member and into the surface feature.

Preferably the surface feature comprises a plurality of apertures provided through the rigid base member and the material of the flexible upper member is formed through all of the apertures.

The surface feature may comprise at least one recess disposed in the upper surface of the rigid base member and the material of the flexible upper member may be formed into the recess.

Preferably the recess is a groove and the sides of the groove are disposed at an angle inclined to an upper surface of the rigid base member.

Ideally, the surface feature comprises both apertures and grooves or slots, but may include undercuts, for example, dovetail undercuts.

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 schematic perspective view of a mould in accordance with the invention; Figure 2 shows a schematic cross-sectional view through the mould of Figure 1, viewed in the direction indicated by the line A-A; Figure 3 shows a schematic cross-sectional view through the mould of Figure 1 viewed in the direction indicated by the line B-B; and Figure 4 shows a schematic plan view from above of a rigid base member prior to forming of a flexible upper member.

Referring firstly to Figure 1, a mould for wet casting concrete paving slabs is indicated generally at 10. The mould 10 includes a flexible upper member 12, which is formed on a rigid base member 14. The base member 14 can be made from any suitably rigid material, but is preferably made from wood, ideally plywood, which is relatively stable.

The flexible upper member 12 has a moulding area 16, shaped for moulding a concrete slab. The moulding area 16 has a base area 17 which is textured for forming the face of a slab and is surrounded by four integral sides 19, joined at the corners, for retaining wet concrete, when poured into the mould 10.

Referring also to Figures 2, 3 and 4, the upper surface of the rigid base member 14 is machined with circular apertures 18,20 and an angled groove 22, which provide an enhanced mechanical key between the material of the flexible upper member 12 and the base member, when the flexible upper member is formed on the base member 14, as explained further below.

Typically, the flexible upper member is substantially square in outline, as shown, for moulding a square paving slab, although the mould may be of any desired shape for any desired concrete product. The circular apertures 18 are provided through the rigid base member 14 at positions corresponding to the positions of the four corners of the flexible upper member 12. The circular apertures 20 are provided at positions corresponding to positions midway along the sides 19 of the flexible upper member 12.

In other words, the apertures 20 are positioned midway between the circular apertures 18.

The groove 22 is provided in the rigid base member 14 at a position corresponding to the perimeter of the lower edge of the sides of the flexible upper member 12. The sides 19 of the flexible upper member 12 are sloped towards the base member 14 and run into the groove 22. The groove 22 has parallel sides, which are also inclined to the planar surfaces of the rigid base member 14 with a similar slope, that is, approximately at an angle a, of between 70 and 85 . The groove 22 extends only part way through the base member 14. The material of the flexible upper member 12 extends into the groove 22, where a reinforcing rib is created around the edge of the flexible upper member 12, where it joins the base member 14.

The flexible upper member 12 is formed from polyurethane, although any other suitable flexible material and associated forming or casting method may be used. The polyurethane is cast as a liquid onto the rigid base member 14 into a further mould, not shown, and flows into the mould, through the apertures 18, 20 and into the groove 22.

When the polyurethane has set, the mould (not shown) is removed, leaving the flexible upper member bonded to the rigid base member 14. The rib of polyurethane formed in the groove 22 of the rigid base member 14 adds strength to the outer edge of the flexible upper member 12. Also, because the groove is inclined, ie does not have sides perpendicular to the surface of the base member 14, the rib prevents the flexible upper member from lifting away from the base member. Plugs 24 of polyurethane are formed in the circular apertures 18, 20 and provide further reinforcement of the polyurethane flexible upper member at its four corners and at positions midway along its side edges 19. The casting of polyurethane into the apertures 18, 20 and groove 20 is sufficient to give the required mechanical properties to the mould, whilst not substantially increasing the amount of polyurethane required for making a mould.

The rigid base member 14 is sized to fit on the hold down frame of a wet cast concrete machine, and can be fastened in position with screw fixings. These screw fixings can be quickly and easily removed as necessary. The mould 10 has more rigidity than known ABS plasticS and polyurethane moulds, and therefore a hold. down frame is not required to retain the mould 10 on the carrier frame of the wet cast concrete machine, for demoulding using a vacuum head.

Furthermore, different sized flexible upper members 12 for different products can be formed on base members 14 of the same size, thereby enabling the same carrier frame and wet cast concrete machine to be used for production of products of many varying sizes. The mould 10 has the advantage of being rigid, but also has the advantage of being flexible in the moulding area 16, for unimpeded removal of a cast product.

Claims

1. A mould for casting concrete products comprising a rigid base member and a flexible upper member, a moulding area formed in the flexible upper member for receiving material to be moulded, and the flexible upper member being permanently fixed to the rigid base member.

2. A mould as claimed in claim I in which the flexible upper member is formed from polyurethane.

3. A mould as claimed in claim 1 or 2, in which the rigid base member is made from

4. A mould as claimed in any one of claims I to 3 in which the rigid base member is made from plywood.

5. A mould as claimed in any one of claims 1 to 4 in which the rigid base member extends beyond an outer edge of the flexible upper member on at least two opposing sides of the flexible upper member.

6. A mould as claimed in any preceding claim in which at least one surface feature is cut into the rigid base member, and the material from which the flexible upper member is made, is formed onto the rigid base member and into the surface feature.

7. A mould as claimed in claim 6 in which the surface feature comprises at least one aperture provided through the rigid base member and the material of the flexible upper member is formed through the aperture.

8. A mould as claimed in claim 7 in which a plurality of apertures are provided through the rigid base member and the material of the flexible upper member is formed through the apertures.

9. A mould as claimed in any preceding claim in which the rigid base member and the flexible upper member are both substantially rectangular in shape.

10. A mould as claimed in claim 9 in which the flexible upper member is square.

11. A mould as claimed in claim 9 or claim 10, when dependent on claim 8, in which the apertures are provided through the rigid base member adjacent each or the four corners of the flexible upper member.

12. A mould as claimed in any one of claims 6 to 11 in which the surface feature comprises at least one recess disposed in the upper surface of the rigid base member and the material of the flexible upper member is formed into the recess.

13. A mould as claimed in claim 12 in which the recess is a groove and the sides of the groove are disposed at an angle inclined to upper surface of the rigid base member.

14. A mould as claimed in claim 13 in which the sides of the groove are inclined at an angIe of between 70 and 85 degrees to the upper surface of the rigid base member.

15. A method of manufacturing a mould for casting concrete products comprising forming a flexible upper member onto a rigid base member, the flexible upper member having a moulding area for receiving material to be moulded.

16. A method as claimed in claim 15 in which the flexible upper member is formed from polyurethane.

17. A method as claimed in 15 or 16 in which at least one surface feature is cut into the rigid base member, and the material from which the flexible upper member is made, is formed onto the rigid base member and into the surface feature.

18. A method as claimed in claim 17 in which the surface feature comprises at least one aperture provided through the rigid base member and the material of the flexible upper member is formed through the aperture.

19. A method as claimed in claim 18 in which the surface feature comprises a plurality of apertures provided through the rigid base member and the material of the flexible upper member is formed through the apertures.

20. A method as claimed in any one of claims 15 to 19 in which the surface feature comprises at least one recess disposed in the upper surface of the rigid base member and the material of the flexible upper member is formed into the recess.

21. A method as claimed in claim 20 in which the recess is a groove and the sides of the groove are disposed at an angle inclined to upper surface of the rigid base member.

22. A mould substantially as described herein with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.

23. A method of manufacturing a mould substantially as described herein with reference to and as illustrated in Figures 1 to 4 of the accompanying drawings.