GB2504848A

GB2504848A - Press mould filter assembly

Info

Publication number: GB2504848A
Application number: GB1311932.6A
Authority: GB
Inventors: Terence Butlin
Original assignee: Eco Filters Ltd
Current assignee: Eco Filters Ltd
Priority date: 2012-08-09
Filing date: 2013-07-03
Publication date: 2014-02-12
Anticipated expiration: 2032-08-09
Also published as: WO2014023946A1; EP2882510B1; EP2882578B1; GB201311932D0; EP2882510A1; GB201313470D0; GB2506011A; WO2014023945A1; GB2504848B; GB2506011B; EP2882578A1

Abstract

A cementitious press mould filter assembly 51 comprising a carrier plate 8 which has a first carrier portion 56 with a number of perforations 60, a carrier body 58 and a filter 50 comprising a filter sheet 52 mounted on a filter frame 62. The sheet 52 may be attached to the frame 62 by stitching or an adhesive means, and the frame 62 may be formed of a plastics material and may be shaped to fit around a carrier insert. The filter 50 may have carrier engagement portion(s), if so the carrier plate also comprises corresponding filter engagement portion(s) which are engageable with the carrier engagement portion(s). The carrier engagement portion(s) may be protrusion(s) in the form of a shaped corner portion, and the frame 62 may be shaped to fit into these raised corner portions. The first carrier portion may comprise a carrier insert shaped to fit within the carrier border 58 and to extend above the carrier border 58. The first carrier portion 56 may be raised above the carrier border 58. The assembly may comprise a former insert and second filter which engages the frame inner periphery and is held in place through an interference fit.

Description

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.

is 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 io 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 is 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. 3s 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)1 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, 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 and the filter frame is shaped to fit around the carrier insert.

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 io 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. 3D

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.

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 first raised carrier portion may be formed integrally with, or separately from, the carrier plate.

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 io 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.

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 insert may have a particular pattern formed thereon and by use of an appropriate bottom former insert a variety of patterns may be produced on concrete products formed by the cementations press mould.

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

According to a second aspect of the invention, there is provided a method for assembling 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, the method comprising the steps of forming the first carrier portion and the carrier border such the first carrier portion is in the form of 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; io forming the filter frame such that it is shaped to fit around the carrier insert, and mounting the filter sheet on the filter frame.

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 bottom former of the base of the press mould; 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 a partial schematic representation showing in more detail how the filter sheet is attached to the filter frame in the embodiment shown in Figures 3 and 4; Figure 6 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 7 is a partial schematic representation showing a joint between frame sections as forming the filter frame of Figure 6.

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 s 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. 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 3 and 4.

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 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 io embodiment it is adhesively attached to the frame 54, as shown in more detail in Figure 3.

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 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 3 and 4, 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 5.

Although the filter frame shown in the embodiments illustrated in Figures 1 to 5 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 6 and 7.

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 6, the frame section 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 6 and 7, each frame section 82 comprises a first end at which is formed an engagement 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

CLAIMS1. 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, 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 and the filter frame is shaped to fit around the carrier insert.
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 I or Claim 2 claims wherein the filter sheet is is adhesively attached to the filter frame.
4. A filter assembly according to any one of the preceding claims wherein the filter frame is formed from a plastics material.
5. A filter for forming part of a filter assembly according to any one of claims ito 4.
6. A carrier plate forming part of a filter assembly according to any one of claims 1 to 4.
7. A method for assembling 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, the method comprising the steps of forming the first carrier portion and the carrier border such the first carrier portion is in the form of 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; forming the filter frame such that it is shaped to fit around the carrier insert, and mounting the filter sheet on the filter frame.
8. A filter assembly substantially as hereinbefore described with reference to the accompanying drawings.
9. A filter substantially as hereinbefore described with reference to the accompanying drawings.
10-A carrier plate substantially as hereinbefore described with reference to the accompanying drawings.
11. 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 io carrier border surrounding the first portion; and a filter comprising a filter sheet mounted on a filter frame
12. A filter assembly according to claim 11 wherein the filter sheet is stitched to the filter frame.
13. A filter assembly according to claim 11 or claim 12 wherein the filter sheet is adhesively attached to the filter frame.
14. A filter assembly according to claim 11 or claim 12 wherein the filter frame is formed from a plastics material.
15. A filter assembly according to any one of the preceding claims wherein the filter is engageable with the carrier plate.
16. 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.
17. A filter assembly according to claims 16 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.
18. A filter assembly according to claim 17 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.
19. A filter assembly according to claim 16 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.
20. 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.
21. A filter assembly according to any one of the preceding claims wherein the first carrier portion is raised above the carrier border.
22. A filter for forming part of a filter assembly according to any one of claims 11 to 21.
23. A carrier plate forming part of a filter assembly according to any one of claims 11 to 21.
24. A method for assembling a filter assembly according to any one of claims 11 to 21 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.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS:CLAIMS1. 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, 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 and the filter frame is shaped to fit around the carrier insert.2. A filter asèembly 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 claims wherein the filter sheet is adhesively attaàhed to the filter frame.4. A filter aspembly according to any one of the preceding claims wherein the filter frame is formedfrom a plastics material.5. A filter for forming part of a filter assembly according to any one of claims ito 4.6. A carrier late forming part of a filter assembly according to any one of claims 1 to 7. A method for assembling 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 **.*fl * comprising a filter sheet mounted on a filter frame, *:::: the methqd comprising the steps of forming the first carrier portion and the carrier border such the first carrier portion is in the form of 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; S.,.forming the filter frame such that it is shaped to fit around the carrier insert, and mounting the filter sheet on the filter frame.5. A filter assembly substantially as hereinbefore described with reference to Figures 3 and 4, 9. A filter substantially as hereinbefore described with reference to Figures 3 and 4.10. A carrier plate substantially as hereinbefore described with reference to Figures 3 and4. * * . * ***.s.. * * * * * ** S 55S * S S...S 5S5 * S