GB2029311A - Apparatus for incorporating networks in a matrix - Google Patents

Abstract

The apparatus includes three or more rotary vacuum drums 16 mounted on an indexable spider 18 movable between three stations. At station A network is wound in layers on to a drum at that station while vacuum is applied thereto and at station B a matrix of cementitious material is sprayed on to the network while vacuum is still applied to the drum. At a third station C the green sheet of matrix and network is stripped and removed on a pallet 36. The apparatus is continuously operable. <IMAGE>

Description

SPECIFICATION Apparatus for incorporating networks in a matrix This invention relates to apparatus for incorporating a network of reinforcing material in a matrix of material which is initially in a fluid or semi-fluid condition.

Many attempts have been made to reinforce cementicious materials with plastics fibres but in practice the degree of success has been limited because plastics fibres key to only a limited extent in cementicious matrices and because, in general, there is no chemical bonding between the plastics fibres and the matrix. It has also been proposed to use glass fibres in cement matrices; again the improvement in properties has not been as great as is desirable and moreover composites of this kind are costly.

It has now been proposed to incorporate in a water-hardenable mass such as a cemenilsand mixture a network of fibrillated plastics film in the form either of a woven mesh or an expanded fibrillated film. Incorporation of such networks appreciably improve the properties of the composite in comparison with previously proposed plastics-reinforced composites and if polypropylene is used as the reinforcing fibrillated film the cost of the resulting composite is comparable for many purposes with the cost of asbestos-cement products which are used extensively in the building industry because of their low costs.

The materials now proposed incorporating networks of fibrillated film have properties which in some respects are preferable to other low cost building products.

While these newly proposed materials are satisfactory in many respects, they cannot be manufactured by conventional methods involving rotary mixers because the networks are essentially continuous. The expected demand for such products is such, however, that it is essential to provide apparatus which will enable high production rates without at the same time increasing the cost of the final product so that it is no longer competitive with the lowest cost building materials presently on the market.

According to the present invention there is provided apparatus for the incorporation of a network in a matrix comprising means at a first station for supplying the network in appropriate configuration to one of a plurality of vacuum drums mounted on an indexable structure, means at a second station for supplying matrix material in a fluid or semi-fluid condition to network on the said vacuum drum and means at a third station for detaching the resultant matrix and network combihàtion.

Further according to the present invention there is provided apparatus for the incorporation of a plurality of layers of a network in a matrix comprising the rotary vacuum drum, means for supplying a web of the network for winding on to the drum, means for severing the web when a required number of layers of the network has been wound on the drum and means for applying the matrix material to said layers.

Still further according to the present invention there is provided apparatus for the incorporation of a network in a matrix comprising an indexable, rotary structure carrying a plurality of vacuum drums, means at one station for supplying tthe network to the drums, means at a second station for applying matrix material in a fluid or semi-fluid condition to network on the drum at that station and means at a third station for stripping the combined network and matrix from the drum at that station.

Apparatus for manufacturing sheets of cementicious material reinforced with continuous fibre networks of fibrillated film will now be described, by way of example, with reference to the accompanying drawing, the sole figure of which illustrates a diagram of apparatus in accordance with the invention.

Referring now to the drawing, a reel 10 of network material which may be in the form of a ribbon, a mesh or a woven material is mounted upstream of a spreader device 12 which serves, if necessary, to open out the network ready for incorporation in the cementicious matrix. The mesh spreader 12 will be essential if the network is initially in the form of a web of fibrillated material which has not been opened out laterally but in the event that a woven material is used, already in an opened out condition on the reel, the mesh spreader 1 2 can be omitted.

Immediately downstream of the mesh spreader 12 a conventional guillotine, 14 is incorporated in the apparatus which is controlled to operate at predetermined intervals and thus to cut off lengths of the mesh or other opened out network. When the required number of layers have been wound on to a drum 1 6 of appropriate circumferential dimension the spool 10 is stopped. The drum 16 is one of three vacuum drums rotatably drivably mounted on a spider structure 18. At the first station A the drum at that station co-operates with a guide and fixing device 20 to ensure that the mesh is appropriately guided on to the drum. The spider structure 1 8 has passages for the communication of vacuum from a vacuum source 22 to each of the three vacuum drums.At the station A vacuum serves to hold the network in position and the vacuum drum 16 is driven in rotation in the sense indicated by the arrow. The vacuum drum at the station A will continue to rotate until the required number of layers has been built up from the web and because the materials is highly porous the vacuum will be active even after a large numbers of layers has been built up to hold the wound web in position but the end of the web will also be mechanically fixed as the web is cut to complete the location Of the web on the drum. The guillotine device 14 serves to sever the web once the required layers have been applied to the drum 16.

A control arrangement (not shown) will serve once the necessary numbers of layers has been built up at the station A to rotate the spider structure 18 to the station B in an anticlockwise sense, as illustrated. At station B a nozzle or plurality of nozzles and/or spreaders 26 extending widthwise of the suction drum 1 6 serves to spray from a pressure tank 28 a slurry of the materials of the matrix which will normally be cement and sand but which can be cement and pulverized fly ash or possibly gypsum or other form of waterhardening material. The vacuum drum 16 is continuously rotated whilst at the station B until a uniform iayer of the matrix has been built up by the nozzles and/or spreaders 26.This uniformity is assisted by a plurality of rollers 30 which extend across the complete width of the vacuum drum and by a spring-loaded pressure pad 32 disposed downstream of the rollers in the sense of rotation of the vacuum drum. Preferably, the time required to spray the matrix is matched to the time required to build up the requisite number of layers of network on the vacuum drum at the station A.

Once the matrix has been applied to the networks during which time the application of vacuum is continued for a dewatering purpose the spider structure is again indexed through 1 20C in an anti-clockwise sence (as shown) and the vacuum drum under consideration is brought to the station C. A knife 34 then engages against the green composite of cementicious matrix and reinforcing material and the vacuum drum is rotated and with the aid of the knife which acts in the manner of a doctor blade the green composite is stripped from the drum and laid out on to a pallet 36 which is moved along a conveyor 38 during the stripping process.

The pallet 36 is moved along the conveyor 38 to a stacker 40 and is then mounted in the stacker and the green sheets are then allowed a sufficient amount of time for proper curing which, in certain circumstances, may involve autoclaving. The pallets 36 are finally retumed to the inlet of the conveyor for re-use.

In a modification, not illustrated, the green sheets of the composite may be subjected to a pressing or forming process before curing to give them a desired shape which may be of corrugated form.

While the apparatus is particularly suitable for the incorporation of networks in a cementicious matrix, it will be understood that it is also applicable to the manufacture of plasterboards of gypsum and other gypsum products and indeed any other product which involves the incorporation of networks of reinforcement in a matrix.

It is also possible that apparatus in accordance with the invention could be used for the manufacture of pipes. In this modification the knife 34 would be omitted and green composite pipes removed axially from the rollers 16.

It is believed that the mode of operation will be clearly apparent from the description hereinbefore set forth of the operations taking place at each of the stations A, B and C. The control system will ensure that vacuum is applied to vacuum drums 1 6 only when they are at stations A and B.

Although only three stations have been shown it is possible for certain matrices that a longer period will be necessary for initial drying of the green composite, in which event a fourth or possibly a fifth station will be provided thus providing an additional period for de-watering of the slurry.

It will be understood that the drums 1 6 will be subjected to different operations simultaneously at each of the three (or more) stations and that their speed of rotation will be variable.

The pallets 36 may themselves be of corrugated form so that the green composites are immediately shaped after stripping at station C.

Claims (14)

1. Apparatus for the incorporation of a network in a matrix comprising means at a first station for supplying the network in appropriate configuration to one of a plurality of vacuum drums mounted on an indexable structure, means at a second station of the indexable structure for applying matrix material in a fluid or semi-fluid condition to the network on the said vacuum drum and means at a third station of the indexable structure for detaching the resultant matrix and network combination form the said vacuum drum.

2. Apparatus for the incorporation of a plurality of layers of a network in a matrix, said apparatus comprising a rotary vacuum drum, means for supplying a web of the network for winding on to the drum, means for severing the web when a required number of layers of the network has been wound on to the drum and means for applying the matrix material to said layers.

3. Apparatus for the incorporation of a network in a matrix comprising an indexable, rotary structure carrying rotary vacuum drums, means at one station of the structure for winding the network on to a said drum at that station, means at a second station for applying matrix material in a fluid or semi-fluid condition and network on a said drum at that station and means at a third station for stripping the combined network and matrix from a said drum at that station.

4. Apparatus according to any one of claims 1 to 3, comprising means upstream of the network supplying means for opening the network out laterally.

5. Apparatus according to any one of the preceding claims for severing the network adjacent said first station.

6. Apparatus according to any one of the preceding claims wherein the means for applying the matrix material includes a spray nozzle or nozzles.

7. Apparatus according to any one of the preceding claims comprising means for applying pressure to the network and matrix on the vacuum drum at the second station.

8. Apparatus according to any one of the preceding claims comprising pallet support means at the third station, pallets being provided to receive sheets of the green network and matrix combination at the third station.

9. Apparatus according to any one of the preceding claims comprising means for applying vacuum to the vacuum drums and means for controlling the application of vacuum so that vacuum is applied at both the first and second stations.

10. Apparatus according to any one of claims 3 to 9 wherein the stripping means comprises a doctor blade.

11. Apparatus according to claim 8 wherein the pallets have corrugated surface whereby to impart a corrugated form to the green sheets.

1 2. Apparatus according to any one of the preceding claims including a fourth station betwesn the second and third stations at which vacuum is applied to a said drum at that station.

1 3. Apparatus according to any one of the preceding claims comprising means for varying the speed of rotation of the rotary vacuum drums.

14. Apparatus for the incorporation of a network in a matrix substantially as hereinbifore described with reference to the accompanying drawing.