GB2108039A

GB2108039A - Making a fibre-reinforced tile

Info

Publication number: GB2108039A
Application number: GB08229823A
Authority: GB
Inventors: Antony Richard Centa
Original assignee: ST JAMES TILE Co Ltd
Current assignee: ST JAMES TILE Co Ltd
Priority date: 1981-10-20
Filing date: 1982-10-19
Publication date: 1983-05-11

Abstract

A method of producing a tile from a wet curable mix uses a filter press, the tiles being the filter cakes formed after feeding a slurry into the filter compartments (3) and dewatering. The method is particularly suitable for producing a tile having fibre reinforcement adjacent its faces. The distribution of fibres in the tile is controlled by selectively draining parts of the mould during filling. <IMAGE>

Description

SPECIFICATION Improvement relating to methods of producing moulded shapes This invention relates to methods of producing moulded shapes from a wet mix.

According to the present invention a moulded shape is produced from a wet mix in a filter press.

The filter press may in its general construction be of conventional kind. It can be of the recessed filter plate type or of the flush filter plate type with intervening filter frames for defining the space in which the moulded shape constituted by the filter cake is formed. The spaces between adjacent plates and the contouring of the surfaces of the filter plates and/or of the filter frames will define the shape and surface pattern of the moulded shape. For example if simple shapes such as tiles are to be produced the spaces will be narrow rectangular spaces. If surface patterns are required on the moulded shapes then the surfaces of the filter plates will be suitably configured.

More particularly but not exclusively the invention relates to a method of producing moulded shapes of curable material such as gypsum reinforced with fibrous material such as glass fibres. In such moulded shapes it is essential to position the fibrous material adjacent one or both faces to improve the tensile strength of the product in bending. However, for reasons of economy it is advantageous to have the minimum amount of fibrous material at the centre of the thickness of the moulded shape where it serves no useful purpose.

In order to produce a moulded shape of curable material reinforced with fibrous material according to the invention, a slurry of the curable material containing fibrous material is initially fed into the filter press and due to the normal action of the filter press this initial slurry will be de-watered with the resultant formation of a filter cake containing the fibrous material adjacent the filter cloths. Thereafter a slurry of curable material not containing fibrous material is fed into the filter press and this will form the core of the moulded shape.

To produce a lightweight core the second slurry feed may be a foamed slurry.

If fibre reinforcement is only required at one face of the moulded shape then in each filter compartment one side of the compartment is blanked off to the flow of filtrate, so that all filtrate removal is effected at the other side of the compartment. Hence during the initial slurry feed the fibrous material concentrates adjacent the filter plate through which filtrate removal is taking place. Alternatively if the fibre reinforcement is only required at certain zones of one or both its surfaces, then certain zones at one or both sides of the compartment are blanked off to the flow of filtrate so that the filtrate only flows through those areas of the filter plate(s) where reinforcement of the moulded shape is required. The blanking off of the flow of filtrate can be achieved by valves in outlet ducts leading from the filter plates or zones thereof.The slurry containing the fibrous material may also contain a retarder to allow time for the slurry to flow into the filter press. After the feed of this slurry an accelerator is advantageously injected into the filter press to solidify the fibre reinforced material and then the second slurry for example of foamed curable material is fed into the filter press. The slurry, accelerator and a washing water are advantageously fed into the filter compartment through respective feed ducts.

If desired instead of only using a foamed slurry for the second feed, this can also be used for the first feed containing the fibre reinforcement since the filter cloths of the filter press will break up the gas bubbles to produce a skin at the surfaces of the moulded shape.

It will be appreciated that in accordance with the invention a single slurry feed containing fibrous material can be used to produce a moulded shape, rather than using two slurry feeds as described above.

The accompanying diagrammatic drawing shows a fragmentary vertical section of one form of conventional filter press of the flush plate and frame type suitably modified for producing moulded shapes in the form of tiles in accordance with the invention. In the drawing the parts of the filter press have been shown slightly spaced apart for clarity.

The filter press comprises a series of plates 1 disposed parallel to each other a filter frame 2 being disposed between each adjacent pair of plates to define between the facing surfaces of the plates 1 a moulding recess 3 to which the slurry is fed under pressure. The facing surfaces of the plates 1 are sealed to the intervening frame 2 around their peripheries. Between each plate 1 and the frame 2 is disposed a backing cloth 4 and a filter cloth 5 which become tightly clamped in position around their edges when the press is closed.

A slurry feed duct 6 leads from one end of the press 1 to the other and branch ducts 7 are provided in the frames 2 leading from the duct 6 into the recess 3. Thus the slurry fed into the filter press via duct 6 flows into the recesses 3. With the pressurised feed, the water is squeezed through the filter cloths 5 and flows along the weave of the backing cloths 4, through an outlet ducts 8 in the plates 1 and into outflow pipe 9.

Each of the outlet ducts has a controllable valve and for the filter compartment shown in the drawing these are designated 10 and 1 Thus at any selected time one or both of the valves 10 and 11 can be open to permit the flow of filtrate through them.

In operation of the press to produce a tile having fibre reinforcement adjacent one face say the right hand face as seen in the drawing, the valve 10 is open and the valve 11 is closed whilst the slurry containing the fibre reinforcement is fed to press. Thereafter the valve 11 is also opened and slurry not containing fibre reinforcement is fed into the filter press.

If it is required to produce a tile which has ribs on one face, the ribs containing the majority of the fibre reinforcement, then the filter plate 1, say the right hand one as seen in the drawings, is provided with a number of grooves, complementary to the ribs to be formed and each of these grooves is provided with an outlet duct parallel to the duct 8 leading to the oufflow pipe 9 and containing a valve. In this case both the valves 10 and 11 are closed and the valves associated with the grooves are open whilst the slurry containing the fibre reinforcement is fed into the filter compartments.

Thereafter the valves 10 and 11 are opened and slurry not containing fibre reinforcement is fed into the filter compartments.

To achieve the flow of accelerator and washing water as mentioned above a total of three feed ducts corresponding to the duct 6 could be provided at three of the corners of the press.

In conventional manner the plates 10 can be hung from slide bars. In order to unload the moulded tiles, suitable handle mechanism can be provided for removing the frames 2 containing the tiles laterally from the press. Preferably the tiles are unloaded in the green state, i.e. before they have completely cured in order to facilitate their removal.

Instead of having the plates 1 and frames 2 extending vertically, the press couid be arranged so that they extend horizontally.

Claims

1. A method of producing a moulded shape from a wet mix, comprising using a filter press, the moulded products comprising the filter cakes formed by feeding the wet mix in the form of a slurry of curable material into the filter compartments of the press.

2. A method according to Claim 1, wherein the slurry contains a retarder, and an accelerator is fed separately into the filter compartments after the slurry feed.

3. A method according to Claim 1 or 2, wherein the moulded products are unloaded from the press in the green state.

4. A method according to any preceding claim for producing a moulded product having fibre reinforcement, wherein a slurry of curable material containing fibrous material is initially fed into the press and then a slurry of curable material not containing fibrous material is fed into the filter press, whereby the fibre reinforcement lies predominantly adjacent the surface of the moulded product.

5. A method according to Claim 4, wherein in order to provide fibre reinforcement adjacent selected areas of the surface of the moulded product, the filtrate flow from the filter compartments is controlled so that it is substantially only permitted out of those areas of the filter compartment adjacent said selected areas of the filter cake during the feed of the slurry containing the fibre reinforcement.