WO2014023945A1

WO2014023945A1 - Filter assembly and method for assembling said filter assembly

Info

Publication number: WO2014023945A1
Application number: PCT/GB2013/052089
Authority: WO
Inventors: Terence Butlin
Original assignee: Eco Filters Limited
Priority date: 2012-08-09
Filing date: 2013-08-05
Publication date: 2014-02-13
Also published as: EP2882578B1; EP2882578A1; EP2882510B1; GB2504848A; GB201311932D0; GB201313470D0; GB2504848B; EP2882510A1; GB2506011B; WO2014023946A1; GB2506011A

Abstract

A filter assembly (22) for a cementitious press mould (2) the filter assembly (22) comprising: a carrier plate (8) comprising a first carrier portion (26) comprising a plurality of perforations (30), and a carrier border (28) surrounding the first portion (26); and a filter (20) comprising a filter sheet (32) mounted on a filter frame (34).

Description

FILTER ASSEMBLY AND METHOD FOR ASSEMBLING SAID FILTER ASSEMBLY

The present invention relates to a filter assembly for use in a cementitious press mould such as a wet concrete, hermetic or semi-dry mix press mould.

A known cementitious press mould comprises a mould cavity having a closed base and side walls. A metered amount of cementitious mix is placed into the mould cavity and a movable press head is then moved towards the closed base to apply a high compressive pressure on to the cementitious mix.

The press head comprises a die head having a head plate that comes into contact with the mixture contained in the mould. The head plate is of a shape and size that corresponds to the cross-sectional shape and size of the mould cavity. The base of the press mould comprises a bottom former that has a shape and size that corresponds to the cross-sectional shape and size of the mould cavity.

Various actions within the cementitious mix occur when the compressive pressure is applied. For example, in a wet concrete press mould, a wet concrete mix is compacted, it is shaped to the shape of the mould, and excess water is squeezed out of the wet mixture.

A result of these actions is the formation of a moulded product, such as a paving slab or kerb, for example.

In a wet concrete press mould, excess water is conducted away from the die head under the assistance of a vacuum, created in the die head and through the bottom former of the mould cavity. It is known that the action of the press head causes the majority of the excess water to be expelled via the die head.

It has been found that during the moulding process, the compressive forces applied by the press head to the concrete mix cause a large proportion of the excess fluid to flow toward the edges of the die head, resulting in high pressure and frictional forces acting on the edges of the die head. In a hermetic press mould, a cementitious mix designed specifically for the press mould is placed in the mould cavity. The cementitious mix usually consists of a face and back mix. The face mix normally comprises expensive aggregates with a high cement content and is generally very wet when discharged into the mould. The back mix is a weak semi-dry cement mix, and is placed on top of the face mix within the cavity.

Due to the fact that a hermetic press mould comprises a sealed base, cement enriched water from the face mix is forced thorough the back mix when under pressure from the press head.

In a semi-dry press mould, a semi dry mix having a higher cement content, and slightly wetter consistency than the back mix of a hermetic press mould, is placed in the mould cavity. The water/cement ratio of the mix is such that on compaction from either pressure or vibration, the mix forms a solid mass to the required strength.

It is known to provide filters which cover the closed base and the moveable head plate in order to provide a release for removal of the moulded product from the mould and also to assist in preventing particulate material (such as cement particles and aggregate fines) from exiting the mould via the closed bottom or the head plate.

Some filters, for example made of paper, are loosely retained in the mould so as to be removed with the moulded product. This is wasteful of filter material and also has the further disadvantage of requiring removal of the filter material from the moulded product.

Some filters are fixed to the head plate and/or to the lower former of the mould so as to remain in the mould / on the die head after the moulding process and removal of the product.

Such filters may be formed from any convenient material, or fabric, that allows liquid to pass through the filter whilst preventing particulate material from passing through.

A suitable filter fabric, which may be knitted or woven is described in our UK Patent No. GB 2 277 536B. However, other materials, such as plastics materials, may also be used. In general, any permeable, woven, non-woven (such as needle felts), knitted or foam material may be used as a suitable filter fabric.

It is known to form perforations in both bottom former and the die head in order to assist the flow of excess fluid out of the mould.

In known cementitious press moulds, the filter fabric is mounted on a support layer which is generally formed from a plastics material to form a filter assembly. The filter assembly must be attached to the carrier plate.

The support layer may be formed with perforations and these perforations may be aligned with the perforations in the carrier plate in order to allow proper drainage of the cementitious mix.

A problem with such known filter assemblies, is that it is generally necessary for a customer to attach the filter assembly to the carrier plate. This is achieved by means of an adhesive layer formed around the edge of the filter. In use, a customer removes a backing sheet from the adhesive layer and then positions the filter onto the carrier plate.

This can result in misalignment of the filter if the customer is not very careful when locating the filter assembly on the carrier plate.

If the filter assembly is misaligned, then the filter assembly will wear more quickly during use of the press mould, and drainage may be impaired. Further, it can be time consuming to have to attach the filter assembly to the carrier plate.

According to a first aspect of the present invention there is provided a filter assembly for a cementitious press mould, the filter assembly comprising: a carrier plate comprising a first carrier portion comprising a plurality of perforations, and a carrier border surrounding the first portion; and a filter comprising a filter sheet mounted on a filter frame.

According to a second aspect of the invention there is provided a filter for use in a cementitious press mould, the filter comprising a filter sheet mounted on a filter border. According to a third aspect of the present invention there is provided a carrier plate forming part of a filter assembly according to the first aspect of the present invention.

By means of the invention it is not necessary to attach the filter sheet to a support plate. Instead, the filter sheet is attached to the filter frame, and the filter is engageable directly with the carrier plate. This means that, in use, the filter sheet is held in place directly over the first carrier portion in which perforations are formed, without needing to support the filter with a support plate. The filter will form a face for contacting and applying compression to a mixture contained in the press mould.

The filter sheet and filter frame may be manufactured to appropriate dimensions to fit a particular carrier plate. The filter sheet may then be attached to the filter frame by any suitable means. These steps may be carried out at any suitable location, and not necessarily in the vicinity of the press mould to which the filter is to be fitted.

In some embodiments of the invention, the filter sheet may be attached to the filter frame by stitching the filter sheet to the filter frame.

In other embodiments, the filter sheet may be adhesively attached to the filter frame.

Other means of attaching the filter sheet to the filter frame may also be used. Ultrasonic techniques may be used in order to cause the fabric to melt onto the filter frame. Alternatively the edges of the filter sheet may be folded around the filter frame and then glued to an underneath surface of the filter frame, for example.

The filter frame may be made from any suitable material, such as a plastics material. In particular, the filter frame may be formed from polypropylene, fibreglass, carbon fibre, metal or wood, for example.

The filter frame may be formed from a single piece of material. Alternatively it may be formed from a plurality of frame sections each of which frame sections is engageable with one or more other frame sections to form the filter frame. In some embodiments of the invention, the filter is engageable with the carrier plate, such that when the filter is placed on the carrier plate, the filter and the carrier plate engage with one another to hold the filter in place on the carrier plate. In some embodiments of the invention, the carrier plate may comprise a carrier engagement portion, and the filter may comprise a corresponding filter engagement portion engageable with the carrier engagement portion.

In some embodiments of the invention, the carrier comprises a plurality of carrier engagement portions each comprising a protrusion, and the filter comprises a plurality of filter engagement portions each shaped to engage with a corresponding protrusion.

In one embodiment, the carrier border comprises a plurality of raised corner portions, and the filter frame is shaped to fit within the raised corners of the carrier border.

The raised corner portions of the carrier border may be detachable in order that they may be replaced. This means that if the corner portions wear down they may be replaced by new corner portions without having to replace the carrier plate entirely. This can be advantageous, since the corners of the carrier plate tend to wear more quickly than the remainder of the carrier plate.

The carrier border may comprise a raised corner portion at each corner of the carrier border, although in some embodiments, there may be a raised corner portion at some, but not all corners of the carrier border.

In such embodiments, the corners of the filter frame that correspond to the raised corner portions of the carrier border may be shaped to abut against the corresponding raised corner portion of the carrier border when the filter is positioned on the carrier plate. In some embodiments the carrier border may be defined only by raised corner portions.

In other embodiments there may be no raised corner portions.

In some embodiments of the invention, the first carrier portion may extend above the carrier border. In such embodiments, the first carrier portion is raised above the carrier border and thus the first carrier portion itself may comprise, either alone, or in conjunction with other components, the carrier engagement portion. The raised carrier portion may be formed integrally with, or separately from, the carrier plate.

In some embodiments of the invention, the raised first carrier portion may comprise a carrier insert shaped to fit within the carrier border, and to extend above the carrier border when the insert is positioned on the carrier plate. The carrier insert may be formed separately from the carrier plate.

This means that in use, the carrier insert will stand proud of the carrier border. When the filter is positioned on the carrier plate, it will fit around the insert and will be held in position by the insert.

In such embodiments, the filter engagement portion comprises an inner surface of the filter frame. The filter frame may be shaped to have an interference fit with the carrier insert or raised first carrier portion respectively. In other embodiments, a clip or other retainer may be used to hold the filter frame against the carrier insert.

In embodiments of the invention comprising one or more raised corner portions, a channel may be defined between the raised first carrier portion or the carrier insert respectively, and each of the one or more raised corner portions. In use, the filter may be positioned on the carrier plate such that the filter frame is located within the at least one channel.

In such embodiments of the invention, the carrier engagement portion comprises the raised first carrier portion or carrier insert, together with the one or more carrier engagement portions.

Other types of carrier protrusions are also possible, and so protrusions may be formed on the sides of the carrier border or carrier plate, for example. The filter will be correspondingly shaped so that the filter and the carrier engage with one another when the filter is placed on the carrier plate. The filter frame may, for example, comprise recesses formed on the frame to engage with protrusions on the carrier border.

In other embodiments, the carrier engagement portions may comprise recesses, and the corresponding filter engagement portions are shaped to engage with the recesses. The carrier insert may be perforated to allow liquid to drain through the carrier insert. In addition, the perforations may be arranged on the carrier insert in such a way that a pattern is created by the perforations. This pattern will be transferred to the product formed in the press mould.

The carrier insert may alternatively or in addition comprise drainage channels on a back surface thereof.

The carrier plate and filter may have any convenient shape, and may be, for example, substantially square or rectangular. Other shapes are also possible.

The carrier plate may comprise the die head or the bottom former or both, and the carrier insert may be a die head insert or a bottom former insert as appropriate. The bottom former may have a particular pattern formed thereon and by use of an appropriate bottom former a variety of patterns may be produced on concrete products formed by the cementations press mould.

The bottom former may be made from any suitable material such as a plastics material, steel, metal alloy, or a composite material.

According to a fourth aspect of the invention, there is provided a method for forming a filter assembly according to the first aspect of the invention, the method comprising the steps of mounting a filter sheet on a filter frame to form a filter; and

attaching the filter to a carrier plate, wherein the carrier plate comprises a first carrier portion comprising a plurality of perforations, and a carrier border surrounding the first portion to thus form the filter assembly.

According to a fifth aspect of the invention, there is provided a method for forming a filter according to the second aspect of the invention.

The invention will now be further described by way of example only with reference to the accompanying drawings in which: Figure 1 is a schematic representation of a press mould incorporating filter assemblies according to embodiments of the invention; Figure 2 is an exploded perspective view of the press mould of Figure 1 ;

Figure 3 is an exploded schematic representation of part of a filter assembly according to an embodiment of the invention wherein the carrier plate is the head plate of the die head;

Figure 4 is a schematic representation of the underside of a filter according to an embodiment of the invention forming part of the filter assembly of Figure 3; Figure 5 is an exploded schematic representation of part of a filter assembly according to an embodiment of the invention wherein the carrier plate is the bottom former of the base of the press mould;

Figure 6 is a schematic representation of the underside of a filter according to an embodiment of the invention forming part of the filter assembly of Figure 5;

Figure 7 is a partial schematic representation showing in more detail how the filter sheet is attached to the filter frame in the embodiment shown in Figures 5 and 6; Figure 8 is a schematic representation showing an embodiment of the invention in which the filter frame is formed from a plurality of filter sections; and

Figure 9 is a partial schematic representation showing a joint between frame sections forming the filter frame of Figure 8.

Referring to Figures 1 and 2, a press mould 2 for making concrete slabs and incorporating filter assemblies in accordance with embodiments of the invention is shown. The mould 2 comprises a mould cavity having a bottom former 4 defining a closed base to the mould cavity, and a moveable press head 6. The press head 6 includes a die plate 8 having a die face. The press head 6 is connected to a ram (not shown) which enables the die face to be moveable toward the bottom former 4 for compressing cementitious material 12 therebetween for forming a concrete slab or kerb or other product. A first filter 20 according to an embodiment of the invention is placed between the cementitious material 12 and the die plate 8. This first filter 20 is described in more detail below with reference to Figures 3 and 4. A second filter 50 according to an embodiment of the invention is placed between the cementitious material 12 and the bottom former 4 and will be described in more detail below with reference to Figures 5 and 6.

In use, the first and second filters 20, 50 overlay a surface of the die plate 8 and bottom former 4 respectively in order to provide a release for removal of the moulded product from the mould and also to assist in preventing particulate material from exiting the mould via the bottom former 4 or die plate 8.

Turning now to Figures 3 and 4, the first filter 20 will be described in more detail.

The first filter 20 forms part of a filter assembly 22 which comprises a carrier plate in the form of the die plate 8, and first filter 20.

The die plate 8 comprises a first carrier portion 26 and a carrier border 28 surrounding the first carrier portion 26. In this embodiment, the first carrier portion 26 is raised relative to the carrier border 28, although in some embodiments, the first carrier portion 26 could be flush with the carrier border 28.

The first carrier portion comprises a plurality of perforations 30 which allow liquid to pass through and out of the press mould. The border does not have any perforations, although in some embodiments it could.

The first filter 20 comprises a filter sheet 32 mounted on a filter frame 34. The filter sheet 32 may be formed from any suitable material such as a knitted or woven material that allows liquid to pass through, but prevents passage of particulate material. The filter frame is made from any suitable material such as a plastics material.

The filter sheet 32 is attached to the filter frame 34 by any suitable means, and in this embodiment it is stitched to the frame 34, as shown in more detail in Figure 3.

The carrier border 28 comprises a plurality of carrier engagement portions each comprising a raised corner portions 36. The filter frame 34 comprises a plurality of corresponding engagement portions 38 (only three of which are shown) which each abut with a respective raised corner portion 36 when the filter is placed on the die plate 8. The engagement portions 36 are in the form of shaped corner portions having an outer substantially flat surface 40 rather than an apex and an inner substantially flat surface 41. The surface 40 will abut with a corresponding corner portion 36. Because the first carrier portion 26 is raised relative to the carrier border 28, a channel 37 is defined between each of the corner portions 36 and the first carrier portion 26. This means that when the filter 20 is in position, the filter frame fits between the raised corner portions 36 and the first carrier portion 26 within the channel 37 and hence is held in position.

In other words, the corner portions of the filter frame 34 defined by surfaces 40, 41 are located within the channels 37.

Turning now to Figures 5 and 6, the second filter 50 will be described in more detail.

The second filter 50 forms part of a filter assembly 51 which comprises a carrier plate in the form of the bottom former 4 and second filter 50.

The bottom former 4 comprises a lower perforated portion 56 and a carrier border 58 surrounding the lower perforated portion 56.

The lower perforated portion comprises a plurality of perforations 60 which allow liquid to pass through and out of the press mould. The border 58 does not have any perforations, although in some embodiments it could.

The bottom former 4 further comprises a first carrier portion comprising a carrier insert in the form of former insert 80. Former insert 80 is shaped to fit on the bottom former 4 within the carrier border 58, and to extend above the carrier border 58 so as to stand proud of the carrier border 58.

The former insert 80 comprises perforations 82, which not only assist in drainage of water, but also transfer a pattern onto the product 14.

The second filter 50 comprises a filter sheet 52 mounted on a filter frame 54. The filter sheet 52 may be formed from any suitable material such as a knitted or woven material that allows liquid to pass through but prevents passage of particulate material. The filter frame 54 is made from any suitable material such as a plastics material. The filter sheet 52 is attached to the filter frame 54 by any suitable means, and in this embodiment it is adhesively attached to the frame 54, as shown in more detail in Figure 5. The second filter 50 fits over the former insert 80 such that the inner surface 62 of the filter frame 54 engages with and/or is in contact with the sides 64 of the former insert when the filter is in position on the bottom former. In this embodiment, the second filter 50 forms an interference fit with the former insert 82, and is thereby held in position during use of the press mould 2. In other embodiments, a clip could be used to retain the second filter 50 in position on the bottom former 82.

In the embodiment illustrated in Figures 5 and 6, the filter sheet is wrapped around the filter frame 54 and is adhesively attached to the frame. This arrangement is shown in more detail in Figure 7.

Although the filter frame shown in the embodiments illustrated in Figures 1 to 7 has been shown being formed from a single piece of material, it is also possible to form the filter frame from frame sections as shown in the embodiment illustrated in Figures 8 and 9. In this embodiment, a filter frame 88 comprises four frame sections 82 which connect together by any suitable means. In the embodiment shown in Figure 8, the frame 82 connect to one another by means of an engagement portion 84 formed at one end of a first frame section, which is engagable with a corresponding engagement recess 86 formed at one end of a second filter section.

In the embodiments shown in Figures 8 and 9, each frame section 82 comprises a first end at which is formed an engaging portion 84, and a second end at which is formed an engagement recess 86. In other embodiments different arrangements may be used. In other embodiments, the frame 88 could be formed from a different number of frame sections, and also the frame sections may be connected to one another by any convenient means.

Claims

1. A filter assembly for a cementitious press mould the filter assembly comprising: a carrier plate comprising a first carrier portion comprising a plurality of perforations, and a carrier border surrounding the first portion; and a filter comprising a filter sheet mounted on a filter frame

2. A filter assembly according to claim 1 wherein the filter sheet is stitched to the filter frame.

3. A filter assembly according to claim 1 or claim 2 wherein the filter sheet is adhesively attached to the filter frame.

4. A filter assembly according to claim 1 or claim 2 wherein the filter frame is formed from a plastics material.

5. A filter assembly according to any one of the preceding claims wherein the filter is engageable with the carrier plate.

6. A filter assembly according to any one of the preceding claims wherein the carrier plate comprises a carrier engagement portion and the filter comprises a corresponding filter engagement portion engageable with the carrier engagement portion.

7. A filter assembly according to claims 6 wherein the carrier plate comprises a plurality of carrier engagement portions each comprising a protrusion and the filter comprises a plurality of corresponding filter engagement portions each shaped to engage with a corresponding protrusion.

8. A filter assembly according to claim 7 wherein the carrier engagement portions each comprise a raised corner portion of the carrier border, and the filter frame is shaped to fit within the raised corner portions of the carrier border.

9. A filter assembly according to claim 6 wherein the carrier plate comprises a plurality of carrier engagement portions each comprising a recess, and the filter comprises a plurality of corresponding filter engagement portions each shaped to engage with a corresponding recess.

10. A filter assembly according to any one of the preceding claims wherein the first carrier portion comprises a carrier insert shaped to fit within the carrier border and to extend above the carrier border when the insert is positioned on the carrier plate.

11. A filter assembly according to any one of the preceding claims wherein the first carrier portion is raised above the carrier border.

12. A filter for forming part of a filter assembly according to any one of claims 1 to 11.

13. A method for assembling a filter assembly according to any one of claims 1 to 11 comprising the steps of mounting a filter sheet on a filter frame; and attaching the filter to a first carrier portion, wherein the carrier portion comprises a plurality of perforations and a carrier border surrounding the first portion.

14. A carrier plate forming part of a filter assembly according to any one of claims 1 to 11.

15. A filter assembly substantially as hereinbefore described with reference to the accompanying drawings.

16. A filter substantially as hereinbefore described with reference with the accompanying drawings.

17. A method substantially as hereinbefore described with reference to the accompanying drawings.

18. A carrier plate substantially as hereinbefore described with reference to the accompanying drawings.