FIELD OF THE INVENTION

THIS INVENTION relates to a method and apparatus for dry-casting blocks to incorporate a groove therein.

BACKGROUND TO THE INVENTION

There are two main manufacturing processes that are used in the production of concrete blocks and paving blocks, commonly referred to in the industry as "pavers", namely: wet-casting and dry-casting.

Wet-casting techniques, using a mould and a vibrating table, are usually used to create decorative blocks in circumstances where high-strength is not essential. For high-strength blocks, using an hydraulic press to compress a mix of cementitious material in the form of concrete (dry-casting) is the preferred method of manufacture.

It is common practice to create indentations or patterns on the surface of the blocks, especially on pavers, to enhance their visual appeal when, for example, they are used to form a driveway or a forecourt. Using the wet-cast technique, the mould, into which the wet concrete is poured, has the pattern formed on its inner surface. A vibrating table is used to settle the concrete in the mould and fill any voids that may have formed therein during the pouring phase. Thus, when the concrete sets, it will have a surface finish that will correspond to the patterns on

the mould's inner surface.

Using the dry-casting technique, a "stamp" or tamper plate with the desired patterns on the lower surface thereof is attached to the hydraulic press. Thus, on contact between the plate and the concrete in the mould, the hydraulic press causes the pattern on the lower surface of the plate to be imprinted onto the upper surface of the concrete.

However, if a deep groove is required in a surface of a block, it has been found to be practically impossible to achieve this result using known dry- casting techniques, although it can be achieved using known wet-casting techniques.

It is thus an object of the present invention to provide a method of dry- casting a block manufactured from cementitious material so that a deep groove, or a plurality of deep grooves, can be created in a surface of the block.

BRIEF DESCRIPTION OF THE INVENTION

According to a first aspect of the present invention there is provided apparatus for producing a block, said apparatus comprising: a mould having side walling which defines a mould cavity; and at least one elongate bar, wherein at least one slot is defined in each of at least two opposed walls of said side walling and said bar is receivable in said slots to extend across the mould

cavity for forming a groove in a block produced in said cavity.

The apparatus may comprise a hydraulic cylinder and a tamper plate attached to the hydraulic cylinder, said tamper plate comprising two sections, each section being configured, during operation of said hydraulic cylinder, to compact a charge of cementitious material within the mould to produce a block.

The opposed walls may define at least one pair of aligned slots in the upper edges thereof and said bar may be receivable in the slots. In one of the preferred embodiments of the present invention, the opposed walls may define two pairs of aligned slots in the upper edges thereof and one of the bars may be receivable in each pair of slots.

According to another aspect of the present invention there is provided a method for producing a block, said method comprising: providing a mould having side walling which defines a mould cavity and wherein at least one slot is defined in each of at least two opposed walls of said side walling; filling the cavity at least in part, with a charge of cementitious material; and positioning at least one elongate bar so that said bar is received in said slots to extend across the mould cavity for forming a groove in said block produced in said cavity.

The method may further comprise compacting the charge of

cementitious material within the mould to produce a block, by operating a hydraulic cylinder with a tamper plate attached to the hydraulic cylinder, said tamper plate comprising two sections, each section being configured, during operation of the hydraulic cylinder, to compact the charge of cementitious material.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Figure 1 is a front elevation of an apparatus for moulding a block in accordance with the present invention;

Figure 2 is an isometric view of a mould forming part of the apparatus of Figure 1 ;

Figures 3 and 4 are front elevations of the apparatus of Figure 1 during production of a block;

Figure 5 is an isometric view of a block produced by the apparatus of Figure

1 ;

Figure 6 is an isometric view of a framework comprising a plurality of the moulds of Figure 2 with the bars removed;

Figure 7 is an isometric view of the framework of Figure 6 showing the location of the bars;

Figure 8 is a top plan view of the framework of Figure 7;

Figure 9 is top plan view of another framework comprising a plurality of the

moulds of Figure 2; and

Figure 10 is top plan view of a still further framework comprising a plurality of the moulds of Figure 2.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Figure 1 , an apparatus for moulding a block (see Figure 5) is generally designated 10. The apparatus 10 comprises a support structure which comprises two vertical walls 12 and a separate base plate 16, a mould 14, located between the walls 12 and resting on the base plate 16 and a tamper plate 18 located above the space occupied by the mould 14. The tamper plate 18 comprises two sections in the form of tamper shoes 18.1 , 18.2, each section 18.1 , 18.2 being attached to vertical pins of a horizontal compaction beam 19, which is connected to a piston rod 20 of an hydraulic cylinder 22.

Referring specifically to Figure 2, the mould 14 is rectangular in cross- section and comprises two side walls 24, 26 and two end walls 28, 30. The walls 24, 26, 28, 30 bound a cavity 32 for receiving a charge of cementitious material in the form of concrete. Two rectangular aligned slots 34, 36 are provided in the upper edges of opposed side walls 24, 26 respectively. The slots 34, 36 are open at their upper ends so that a bar 38, which is rectangular in cross-section, can be inserted into the slots 34, 36 from above. The length of the bar 38 is slightly greater than the width of the mould 14 so that the bar 38 extends across the width of the mould 14 and protrudes slightly therefrom. The lower surface of the bar 38 rests on the bottom surfaces of the slots 34, 36. Alternatively, the bar 38 can be a press-fit within

the slots 34, 36. In the illustrated embodiment, the top .surface of the bar 38 must be at least level with the top surface of the mould 14 (as illustrated in Figure 2), but the bar 38 can be slightly proud of or recessed below the top surface of the mould 14.

As shown in Figure 2, the slots 34 and 36 are centrally located with respect to the end walls 28, 30 and extend downwardly from the upper edges of the side walls 22, 24.

The size and shape of the sections 18.1 , 18.2 of the tamper plate 18 are such that they fit into the open upper end of the mould 14 with the gap between the sections 18.1 , 18.2 corresponding to the width of the bar 38. The sections 18.1,18.2 are interchangeable with other sections or tamper shoes with different shapes and/or dimensions, that fit into correspondingly shaped moulds 14, for moulding different blocks.

Referring now to Figures 3 and 4, in operation, a semi-dry mix of cementitious material 40 is poured into the mould cavity 32. The hydraulic cylinder 22 is activated and, as a result, the piston rod 20 forces the tamper plate 18 into contact with the upper surface of the cementitious material 40, on both sides of the bar 38, and compacts the material 40. When the required degree of compaction has been achieved, the hydraulic cylinder 22 is deactivated and the compacted cementitious material 40, now in the form of a block 42, is allowed to cure.

Thereafter, the mould 14 is separated from the block 42 by manual or

automatic means. In a preferred embodiment, this is done by maintaining the tamper plate 18 in contact with the top of the block 42 and lifting the mould 14, until the tamper plate protrudes below the mould. The block 42 thus remains on the base plate 16, that is typically in the form of a production pallet of wood, steel or plastic, that can be ejected from the apparatus 10 with the block 42. An empty plate 16 is indexed into the apparatus 10 and the mould 14 is lowered onto the plate, to be charged again with cementitious material 40 in the next cycle of operation.

As illustrated in Figure 5, the block 42 is formed with a rectangular section groove 44 located therein as a result of the presence of the rectangular bar 38 in the mould 14. The groove 44 is centrally located with respect to the width of the block 42 and extends from the front face to the rear face thereof.

Referring now to Figures 6 to 8, a framework 46 is depicted which comprises a plurality of moulds 48 in a side-by-side array. Each mould 48 is identical to the mould 14 of Figures 1 to 4. Rectangular bars 50 (not shown in Figure 6), analogous to the bar 38, extend through aligned recesses 52, analogous to the recesses 34, 36 of the moulds 14, of each mould 48. Such a framework 46 can be used in an apparatus (not shown) which is similar to the apparatus 10, but which comprises a plurality of tamper plates 18 attached to at least one hydraulic cylinder 22 to produce a plurality of blocks 42 with grooves therein.

To create blocks (not shown) with grooves 44 offset from the centreline thereof, a framework 54 as illustrated in Figure 9 can be used, wherein the

aligned recesses (not shown) and bars 50 are offset with respect to the centre-lines of the moulds 48. Alternatively, if a plurality of grooves 52 in each resultant block is required then the framework 56 of Figure 10 can be used, where a plurality of aligned recesses (not shown) are provided to receive a plurality of bars 50 extending across each mould 48.

It will be appreciated that Figures 6 to 10 each illustrate an array of nine moulds in a 3x3 array, but that any such array of a plurality of moulds can be used to make a plurality of blocks.