This invention relates to the production of building elements such for example as wall blocks, tiles, paving, decorative panels etc., from a semi-dry mix of material.

It is kno^from the speci ication of British Patent 1^6 635 ■ to compress a semi-dry mix of a cement/sand mix¬ ture in a mould box which is located upon a base board or other surface. The compression of the material is effected by a tamper plate which is lowered into the mould box after a quantity of the material has been placed therein. The tamper plate has mounted thereon elements which project in front of the front surface of the tamper plate and during the compression process the elements become surrounded with compacted material. When the compression process is complete the tamper plate is held agains movement and the mould box lifted away from the surface so that the compacted building element or block is ejected therefrom. Finally the tamper plate is moved away from the surface and the building block fractures along a plane of weakness defined by the elements. The building block is then allowed to cure and its front or upper surface as it rests on the base board or other surface has a random split appearance.

Before the process can be repeated the compacted mat¬ erial must be removed from the tamper plate and this is achieved by a vibrator attached to the tamper plate or the tamper head of the machine which carries the plate. The material which is dislodged falls into the mould box and when some more material has been placed therein the process can be repeated. In most moulding machines the fresh material is contained within a hopper which has a feed box which is moved laterally across the top of the mould box. Material falls into the mould box whilst the feed box lies over the mould box but as the feed box is moved laterally so as to be out of the way of the descending tamper plate, the material in the mould box tends to be moved by the movement of the feed unit, towards one side of the mould

box. As a result when the tamper plate moves into the mould box there is a greater degree of compaction of material at the one side of the box. In order to try to achieve a more uniform degree of compaction it is known to mount the tamper plate on resilient mountings so that it can tilt slightly within the mould box. Whilst this makes the degree of compaction more uniform it does cause problems, one of which is the fact that after fracturing has taken place the thickness of the building element may not be uniform.

The object of the present invention is to provide a method andqg aratus for producing building elements of aforesaid type in a simple and convenient form.

According to the invention a method of producing a building element comprises closing the bottom of a mould box by means of a suitable surface, loweringinto the mouldbox a frame which has side members complementary to the sides of the mould box and spaced therefrom by an amount sufficient to allow relative movement of the mould box and frame, said frame carrying elements at or adjacent its lower edge and the frame being lowered into the mould box so that the elements are spaced from said surface by a distance substantially equal to the required thickness of the building element,placing a semi-dry mix of the material from which the building element is to be formed into said frame and the mould box, compacting the material in the mould box and the frame, ejecting part of the compressed mass of material from the mould box by moving said ^' surface relative to the mould box until the lower edge of the mould box is slightly above the lower edge of the frame and lifting the frame away from said surface to cause fracture of the compacted mass of material along a plane of weakness defined by said elements and removing the ejected mass of material.

According to a further feature of the invention a tamper plate is lowered inτo the frame to assist or effect

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the compaction process, the tamper plate and the frame being held against movement whilst the mould box and surface are moved relative to each other.

According to another aspect of the invention apparatus for use in the production of a building element comprises a mould box having an open top and open bottom and which in use, can be placed upon a surface, a frame which can be moved into the mould box, the frame having sides complemen¬ tary to the sides of the mould box and elements carried by the frame at or adjacent its lower edge, adjustable means for determining the extent of movement of the frame towards said surface, means for compacting material in the mould box and said frame, means for separating the mould box from said surface after the material has been compacted whereby the compacted material is ejected from the mould box and means for moving the frame away from said surface to fracture the mass of compacted material along a plane of weakness defined at least in part by said elements.

An example of the invention will now be described with reference to the accompanying drawings in which:-

Figure 1 is a sectional side elevation of the impor¬ tant parts of the apparatus.

Figure 2 is a similar view showing a modification to part of the apparatus of Figure 1.

Figure 3 is a perspective view of a modification of the apparatus of Figure 1.

Figure is a sectional side elevation of part of another example of the apparatus.

With reference to Figure 1, the apparatus comprises a base board 10 which is supported on a suitable support surface for example a table 11 incorporating a vibrator 12, of a commercial block moulding machine. The apparatus also includes a mould box 13 which has an open top and bottom and which as shown, can rest with its lower edges on the upper surface of the base board 10. Also provided is a frame lk which has sides complementary in shape to the sides of the mould box but which are slightly shorter

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in length so that the frame can slide within the mould bo As shown, the upper edges of the sides of the frame are secured to the edge of an aperture formed in a plate 15.

The depth of the frame 1 is greater than the depth of the mould box 13 -*~-d the latter can be raised by lifti devices l6 forming part of the machine, relative to the frame l so that the lower edge of the mould box can lie above the lower edge of the frame. Moreover, the extent of movement of the frame 1 towards the base board can be determined by a pair of adjustable stops 17 which are preferably mounted on the plate 15, or on part of the moulding machine to which the plate is connected.

The frame carries elements which in the example of Figure 1 are in the form of bars 18 secured at the lower, edge of the frame. The bars 19 are disposed in substan¬ tially parallel and spaced relationship across the frame although they can be recessed into the frame, i.e. they c lie slightly above the lower edge of the frame. The bars are preferably round but other sections can be employed. In the alternative arrangement seen in Figure 2 the eleme are in the form of rods 19 which are mounted on cross members 20 supported in the frame. The cross members are again mounted in spaced relationship and as shown in Figure 2 the ends of the rods 19 are cut obliquely, their ends being in a common plane at oar slightly above the lowe edge of the frame 14.

In a further example the elements may be defined by projections 21 formed for example of weld material deposited on the internal surface of the sides of the frame as seen in Figure 3 -

The apparatus also includes a tamper plate 22 which is mounted on the tamper head 23 of the machine by rubber or like resilient blocks 2-i . The tamper plate 22 can be vibrated by means of inbuilt vibrators 25, the tamper head and plate being raised by means of an hydraulic devic

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forming part of the machine.

A further part of the apparatus may comprise a vibrator not shown, which in operation, is able to vibrate at least the mould box and the frame together with any material therein.

The operation of the apparatus will now be described. First the mould box 13 is lowered onto the upper surface of the base board and the frame ih lowered onto the stops 17. A semi-dry mix of material from which the building element or block is to be formed is then placed in the frame and during this time the vibrator or vibrators operated. The vibration and downward movement of the tamper plate, causes the material to pass between the bars 18 or cross members 20 if such are provided, into the mould box and the vibration also causes compaction of the material so that all voids are filled. Sufficient material is loaded into the frame so that there is surplus αf material which becomes compacted, but-, which, remains above the bars 18 or projections 21 and preferably the cross members 20. The vibration is then stopped and the mould box 13 is lifted whilst the tamper plate and the frame are held against movement until the lower edge of the mould box lies above the lower edge of the frame 14. During this movement the compacted mass of material is in effect ejected from the mould box. Finally the frame lk and tamper plate are lifted away from the surface and fracture of the compacted mass occurs generally along a plane of weakness defined by the bars 18 or the ends of the rods 19 or the projections 21.

The finished element or block can then be removed with the base board and set aside to cure. A new base board is placed in position, the mould box and frame lowered and the process repeated. The compacted material held in the frame by the bars 18, the rods 20 or projections 21, is dislodged by the vibration and falls into the mould box followed by fresh material loaded into the frame after

the tamper plate has been moved out of the frame.

As will be appreciated the building block formed using the frame shown in Figure 1 will have lines on its upper surface as defined by the bars 18. The surface of the block between the lines will have the desired random split appearance. If the bars are disposed slightly above the lower edge of the frame the block will tend to have a front surface which curves towards the sides of the block but it will still have the random split appearance. In the case of the block formed using the frame shown in Figure 2, the upper surface of the block will have the random split appearance all over the surface with slight markings only due to the ends of the rods 19. Ii" desired however, the shapes of the ends of the rods can be changed in order to provide a pattern. Moreover the disposition of the bars and rods can be altered to vary the pattern. It is desirable that the bars 18 and also the cross members and rods should be detachably mounted in the frame so that they can be readily removed for cleaning purposes and for changing the pattern produced by the bars.

The thickness of the resulting block can be varied by adjusting the height of the stops 17. commercial machine for producing blocks includes a feed arrangement for the material forming the block. The feed arrangement in many machines includes a feed box 27 which is loaded with the semi-dry mix of material whilst it is in a retracted position and which is then advanced by a general horizontal movement over the frame and mould box to deposi the material therein. It is essential therefore that the upper surface of the plate 15 should be flush or slightly below the surface of the feed plate 28 of the machine before the feed box is allowed to move. Whilst on its return movement the feed box may tend to cause material to pack against one side of the frame . the intense vibration to which the mould box and frame are subjected, tends to dislodge the packed material so that the tamper

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plate 22 is not moved from its horizontal position and even compaction of the material takes place. In any case even if the aforesaid packing of the material does remain, the fact that the thickness of the block is determined by the relative position of the frame Ik and board which is fixed before the tamper plate is brought into operation, means that the thickness of the block will be uniform. The tamper plate can still be allowed to tilt to achieve more uniform compaction of the material because of the blocks 2k .

One problem has been experienced in the use of the apparatus and particularly where the frame 1 is provided with the projections 21 rather than the bars. As described when a new board 10 has been placed in position and the mould box 13 lowered onto the board, the frame is vibrated either directly or indirectly, with the result that the previously compacted material contained within the frame falls into the mould box. The upper surface of this material is by virtue of the flat face of the tamper plate 22, also flat. It has been found that a substantial proportion of this face remains unbroken in the mould box and that when fresh material is placed in the mould box and compacted, the fresh material does not key with the previously compacted material. As a result the building block has weakness planes. _^ in it. This phenomenon is less likely to occur in the cases where the frame is provided with the bars 18 or cross members 20 since in passing between these components the surface of the naterial tends to be ^' broken. In order to minimise this difficulty the tamper plate 22 is modified by the addition of a skirt 29 which projects downwardly ' from the lower surface and which may include division walls.

In operation, after the main fracture of the compacted mass has taken place and after a new base board has been placed in position, the tamper plate is moved upwardly relative to the frame and a further fracture of the material within the frame takes place. This is caused by the skirt on the tamper plate. Again a random split surface is

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obtained which in the event that is largely undisturbed as it falls unto the base board, provides a better surface against which the fresh material can key when the next compaction stage is carried out.. The material held by the tamper plate can be dislodged by operation of the vibrator 25 and will fall into the mould box and frame either with fresh material or just before or just after the fresh material. Because of the distance it has to fall and the vibration it is broken down into small pieces.

Some machines are not provided with vibrators on the tamper head or plate and in this case the tamper plate is provided with pins on the lower surface of the tamper plat and which incline relative thereto. In this case the tamp plate is allowed to remain in the frame whilst the latter vibrated and the effect of the pins is to break up the surface of the compacted material as it separates from the tamper plate.

The various movements of the mould box, the frame and the tamper plate may be effected by hydraulic mechanisms well known in the art. It is possible to arrange for the actuating mechanism 16 of the mould box 13 to also raise the frame lk to achieve the spliting of the ejected block by providing lugs on the frame which are engaged by the mould box. It is essential, to ensure that the frame is lowered to the stops so that plate 15 does not lie in the path of the feed box.

In a modification of the apparatus shown in Figure k , the plate 0 over which the feed box is moved is secured to the upper edge of the mould box 31« As before the frame 32 is located within the mould box and is provided with lugs 33 on at least two of its opposite sides, which extend through vertical slots 3^ respectively formed in th sides of the mould box. Mounted on the lugs 33 are depend adjustable stops 35 which determine the distance the lower edge of the frame can move towards the surface of the base board. The stops 35 are shown diagrammatically in Figure

The slots are of such a length that the mould box can be moved upwardly so that its lower edge lies above the ^• lower edge of the frame during the process of ejecting the block from the mould box and preferably the mould box and frame are dimensioned so that the slots are covered by the frame during the compaction process.

The frame extends upwardly by an amount such that when the mould box 31 and frame 3 are in their lowermost positions the upper edge of the frame 3 lies below the upper surface of the plate 30. It is essential that this should be the case and this can be arranged by careful positioning of the upper edges of the slots 3^ in the mould box and which engage with the lugs to hold the frame against upward movement. It is desirable however that the ^• frame 32 should be positively located by the aforesaid stops 35 to ensure the correct thickness of the finished block. This can be achieved by upstanding adjustable devices also mounted on the lugs and which are engaged by the under surface of the plate 30 on the mould box, to positively move the frame downwardly as the mould box is moved down¬ wardly. Careful adjustments of the upstanding devices 36 can ensure that the depending stops 35 engage the surface of the base board to provide the required thickness of block and that they also hold the frame against vertical movement in conjunction with the stops during the compaction process.

During the upward movement of the mould box after the compaction process the frame is held against upward movement by the tamper plate 37 which is mounted upon the tamper head of the machine. When the lugs engage the lower edges of the slots k in the mould box, the frame will be lifted away from the base board and fracture of the compacted block will take place. It is essential hoiever that the tamper plate 37 and also the tamper head of the machine should be able to move at the instant the upward movement of the frame 32 takes place. One way in which this can be arranged is by ensuring that the hydraulic mechanism

which actuates the tamper plate, is free to move when the upward movement of the mould box takes place so that it is the weight of the tamper plate and the tamper head of the machine which holds the frame against movement during the ejection process. This can lead to unwanted fracture of the block or to unwanted compression of the compacted block after the lower edge of the mould box has just cleared the lower edge of the frame. It is preferable therefore to lock the hydraulic system of the tamper head so that the tamper plate is unable to move either up or down during th upward movement of the mould box but to unlock the system just as the upward movement of the frame is about to take place. This can be arranged using a suitable valve which is responsive to the movement of the mould box. Alternatively a pressure relief valve system can be employed so that the upward movement of the frame can take place against a resistance imposed by the relief valve which is however set so that the tamper plate is held against movement during the process of ejection. As a further modification the mould box may effect the movement of the tamper head of the machine directly using rods which depend from the tamper head and pass through apertures in the plate for engagement by the mould box or a part connected thereto just as the upward movement of the frame takes place. In this manner most of the force required to raise the tampe plate and the tamper head is transmitted directly to the tamper head rather than through the compacted material beneath the tamper plate.

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