GB2041816A - Continuous Production of Reinforced Sheet Material - Google Patents

Abstract

Apparatus for manufacturing a reinforced sheet material on a continuous basis, comprising opposed rollers (16) disposed to define a gap, means for guiding reinforcing networks (10) into the gap, a hopper (12) for feeding a water-hardening mass to the gap and a conveyor (22) for supporting the sheet material downstream of the gap. The conveyor (22) can sandwich the material and be foraminous and associated with suction boxes. Vibrators and a cutter 28 are provided. <IMAGE>

Description

SPECIFICATION Continuous Production of Reinforced Sheet Material This invention relates to the continuous production of sheet material incorporating a 'reinforcement, and relates more particularly to the production of cementitious (or other water hardening mass) sheet having a reinforcement of organic fibrillated networks arranged as layers.

It has been proposed in co-pending application 27371/76 in the names of the University of Surrey and D. J. Hannant, to reinforce a water hardening mass with a plurality of networks arranged as layers in the water-hardening mass, and it has been found that the properties of this material make it suitable for many purposes, including the replacement of asbestos cement products. However, the material cannot be manufactured on conventional machinery, but because of the expected high demand it is necessary that the production should be efficient and preferably on a continuous basis.

According to the present invention there is provided a machine for the manufacture on a continous basis of a reinforced sheet material comprising a pair of opposed rollers disposed at a predetermined distance apart to form a gap of required dimensions corresponding substantally to the thickness of the sheet means for guiding a plurality of reinforcing networks into the gap, and means for feeding a water-hardening mass in plastic form, and a carrier for supporting the green sheet material downstream of the gap. Means may be disposed below the carrier for at least partially de-watering the green sheet, and means may be provided for cleaning the carrier downstream of the de-watering means.

A machine embodying the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing, the sole Figure of which is a side elevation of the machine indicating the essential parts thereof.

The reinforcement for the sheet material may be in the form of a woven network of which the "yarn" is fibrillated organic film material, or alternatively the reinforcement may be in the form of organic film which has been stretched and fibrillated, and is supplied in the form of rolls with the fibrillations is a compacted configuration. In the final sheet material it is necessary that the compacted fibrillated material should be opened out to form a network and depending upon the quality of the final product required a multiplicity of layers of the network or woven fibrillated materials incorporated in the water-hardening mass, which will normally be a cement/sand or cement/PFA mixture.

As shown in the accompanying drawing the opened out fibrillated film 10 is employed and is directly derived from devices such as shown and described in our co-pending application No.

43236/78 Serial No. 2032839 ("Mesh Spreader"), while at the same time a hopper 12 is provided adjacent a gap 14 of predetermined width formed between two rollers 1 6 which rotate in opposite senses indicated by arrows A and define the gap. The cementitious mix 18 introduced to the gap from the hopper 12 will have a consistency such that it flows readily into the gap, and the pressure applied by the rollers causes the fibrillated, opened-out, networks 10 to be incorporated as layers in the cementitious mass so that after leaving the gap the flexible, green, sheet 20 is supported on a continuous foraminous belt 22 which passes around one of the rollers 16, and also ground additional rollers 24 and guides (not shown).At appropriate positions along the underface of the belt a plurality of de-watering means 26 is provided which will normally be in the form of vacuum chambers which together act progressively to draw off surplus water from the cementitious mass.

Downstream of one of the guide rollers 24 the green sheet is passed through two further rollers 28 which together form a rotary knife in order to cut off individual sheets, and downstream of this rotary knife there will be further guide and support means (not shown), such as closely spaced rollers and the sheets are then passed either to conventional corrugating rollers, or directly to a stacking store where curing can take place.

The return run of the belt is subjected to a washing action to ensure that the holes of the foraminous belt do not become blocked by the cement mixture, and the cycle is then recommenced. The linear advance of the sheet along the upper run of the belt is not particularly rapid since it is necessary that at the gap where pressure is applied sufficient time will be available for the cementitious mass to penetrate thoroughly to the fibrillated networks.

The operation of the machine is believed clear without detailed description, the action of the rollers 1 6 being essentially that of an extruding die.

In an unillustrated modification high frequency vibration is applied to the green sheet at some point downstream of the gap 14 in order to ensure good bonding between the cementitious matrix and the reinforcement. It may also be possible to supply such vibration at the gap through the rollers and the vibration is not necessarily applied at right angles to the path of the green sheet.

In a further alternative one of the rollers 1 6 may rotate at higher angular velocity than the one roller.

To assist intimate contact between the cement matrix and the reinforcement, one or other or both of the rollers may be provided with pins extending a short distance radially from the periphery of the roller or rollers.

The plastic cementitious mass may, if necessary, be forced under pressure into the gap 12. It may also be sprayed under pressure into the gap likewise with a view to achieving an intimate mix with the reinforcement.

Although, as illustrated, the hopper is disposed between the in-feed paths of the reinforcing networks, the arrangement may be reversed so that the network paths are central and the hopper is disposed on one side of these paths. Separate hoppers may be provided one on either side and, again the hoppers may be replaced by spray nozzles or extruding nozzles. Particularly if nozzles are employed several may be used interdigitated between the reinforcement paths and directed towards the gap.

It may be necessary to provide at least one further pair of rollers downstream of the rollers 1 6 and it may be desirable to provide a smaller gap.

The rotary knife formed by the rollers 28 will need high quality cutters because of the abrasive nature of the cementitious matrix and the high resistance of the reinforcement. As an alternative therefore it may be possible to use a hot wire or other cutter device which employs heat and thus reduces wear problems.

If desired the machine may incorporate floats or additional rollers to improve the finish of the product.

A further continuous foraminous belt (not shown) may be arranged to cover at least part of the upper surface of the green sheet. Additional de-watering could then be effected. Such a further belt would pass around the right hand roller 16, and also have its own guide rollers including a series which maintain the belt in contact with the upper surface of the green sheet.

It will be understood that the invention is applicable to the incorporation of network reinforcements as layers in other water-hardening masses, such as gypsum.

Claims (8)

Claims

1. Apparatus for manufacturing a reinforced sheet material on a continuous basis, comprising a pair of opposed rollers, disposed at a predetermined distance apart so as to form a gap, means for guiding a plurality of reinforcing networks into the gap, means for feeding a waterhardening mass in plastic form into said gap, and a carrier for supporting the reinforced sheet material downstream of the gap.

2. Apparatus as claimed in claim 1, in which the carrier for supporting the reinforced sheet material downstream of the gap is a foraminous belt, beneath which are placed vacuum chambers which together act progressively to draw surplus water from the reinforced sheet.

3. Apparatus as claimed in claim 2, which further includes means for cleaning the foraminous belt.

4. Apparatus as claimed in claim 2, which further comprises a second foraminous belt, arranged to lie against at least part of the upper surface of the reinforced sheet.

5. Apparatus for manufacturing reinforced sheets on a continuous basis from networks formed from fibriilated film and cementitious material, comprising a pair of opposed rollers which define a gap, means for supplying and guiding a plurality of reinforcing networks into the gap, a hopper for feeding the cementitious material in plastic form into said gap, a continuous formanious belt which passes over one of the said rollers on which the green sheet emerging from the gap is supported, a plurality of vacuum chambers mounted beneath the belt for dewatering the cementitious material and a cutter to cut the sheet into individual lengths.

6. Apparatus as claimed in any one of claims 1 to 5, which further comprises vibratory means tp ensure good bonding between the cementitious material and reinforcing networks.

7. Apparatus as claimed in any one of claims 1 to 6, comprising drive means for the rollers operable to rotate one roller at a higher angular velocity than the other.

8. Apparatus for manufacturing a reinforced sheet material on a continuous basis, substantially as hereinbefore described with reference to the accompanying drawing.

8. Apparatus as claimed in any one of claims 1 to 7, which further comprises a second pair of opposed rollers arranged to receive the green sheet in the gap therebetween.

9. Apparatus for manufacturing a reinforced sheet material on a continuous basis, substantially as hereinbefore described with reference to the accompanying drawing.

New claims or amendments to claims filed on 5 March 1980 Superseded claims 1-9 New or amended Claims:-

1. Apparatus for manufacturing reinforced sheets on a continuous basis from networks formed from fibrillated film and cementitious material, comprising a pair of opposed rollers which define a gap, means for supplying and guiding a plurality of reinforcing networks into the gap, means for feeding the cementitious material in plastic form into said gap, a continuous foraminous belt which passes over one of the said rollers on which the green sheet emerging from the gap is supported, vacuum applying means mounted beneath the belt for de-watering the cementitious material and a cutter to cut the sheet into individual lengths.

2. Apparatus as claimed in claim 1, which further comprises means for cleaning the foraminous belt.

3. Apparatus as claimed in claim 1 or claim 2, which further comprises a second foraminous belt, arranged to lie against at least part of the upper surface of the reinforced sheet.

4. Apparatus as claimed in any one of claims 1 to 3, which further comprises vibratory means to ensure good bonding between the cementitious material and the reinforcing networks.

5. Apparatus as claimed in any one of claims 1 to 4, comprising drive means for the rollers operable to rotate one roller at a higher angular velocity than the other.

6. Apparatus as claimed in any one of claims 1 to 5, which further comprises a second pair of opposed rollers arranged to receive the green sheet in the gap therebetween.

7. Apparatus as claimed in any one of claims 1 to 6 wherein the means for feeding the cementitious material into the gap comprises a hopper.