Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B7/00—Moulds; Cores; Mandrels
  • B28B7/40—Moulds; Cores; Mandrels characterised by means for modifying the properties of the moulding material
  • B28B7/46—Moulds; Cores; Mandrels characterised by means for modifying the properties of the moulding material for humidifying or dehumidifying
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B3/00—Producing shaped articles from the material by using presses; Presses specially adapted therefor
  • B28B3/02—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein a ram exerts pressure on the material in a moulding space; Ram heads of special form
  • B28B3/021—Ram heads of special form
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B7/00—Moulds; Cores; Mandrels
  • B28B7/36—Linings or coatings, e.g. removable, absorbent linings, permanent anti-stick coatings; Linings becoming a non-permanent layer of the moulded article
  • B28B7/368—Absorbent linings

Definitions

• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• 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.
• the filter assembly 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.
• a filter assembly for a cementitious press mould 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.
• a filter for use in a cementitious press mould comprising a filter sheet mounted on a filter border.
• a carrier plate forming part of a filter assembly according to the first aspect of the present invention.
• 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.
• the filter sheet may be attached to the filter frame by stitching the filter sheet to the filter frame.
• the filter sheet may be adhesively attached to the filter frame.
• the filter frame may be made from any suitable material, such as a plastics material.
• 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.
• 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 carrier plate may comprise a carrier engagement portion, and the filter may comprise a corresponding filter engagement portion engageable with the carrier engagement portion.
• the carrier comprises a plurality of carrier engagement portions each comprising a protrusion
• the filter comprises a plurality of filter engagement portions each shaped to engage with a corresponding protrusion
• 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.
• 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.
• the carrier border may be defined only by raised corner portions.
• the first carrier portion may extend above the carrier border.
• 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.
• 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.
• the carrier insert will stand proud of the carrier border.
• the filter When the filter is positioned on the carrier plate, it will fit around the insert and will be held in position by the insert.
• 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.
• a clip or other retainer may be used to hold the filter frame against the carrier insert.
• 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.
• the filter may be positioned on the carrier plate such that the filter frame is located within the at least one channel.
• the carrier engagement portion comprises the raised first carrier portion or carrier insert, together with the one or more carrier engagement portions.
• 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.
• 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.
• 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.
• a method for forming a filter assembly comprising the steps of mounting a filter sheet on a filter frame to form a filter;
• 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.
• a method for forming a filter according to the second aspect of the invention there is provided a method for forming a filter according to the second aspect of the invention.
• 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;
• Figure 9 is a partial schematic representation showing a joint between frame sections forming the filter frame of Figure 8.
• 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.
• 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.
• 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.
• 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.
• corner portions of the filter frame 34 defined by surfaces 40, 41 are located within the channels 37.
• 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.
• 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.
• a clip could be used to retain the second filter 50 in position on the bottom former 82.
• 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.
• a filter frame 88 comprises four frame sections 82 which connect together by any suitable means.
• 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.
• 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.
• 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.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Mechanical Engineering (AREA)
• Press-Shaping Or Shaping Using Conveyers (AREA)
• Sink And Installation For Waste Water (AREA)
• Moulds, Cores, Or Mandrels (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 2013
  • 2013-07-03 GB GB1311932.6A patent/GB2504848B/en active Active
  • 2013-07-29 GB GB1313470.5A patent/GB2506011B/en active Active
  • 2013-08-05 EP EP13762200.7A patent/EP2882578B1/de active Active
  • 2013-08-05 WO PCT/GB2013/052089 patent/WO2014023945A1/en active Application Filing
  • 2013-08-05 WO PCT/GB2013/052090 patent/WO2014023946A1/en active Application Filing
  • 2013-08-05 EP EP13762201.5A patent/EP2882510B1/de active Active

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