GB2115848A - On-line production of mineral wool blocks and strips - Google Patents

Abstract

Mineral wool, especially rock wool, blocks suitable for use in horticulture, are made by feeding a slab of bonded mineral wool (10) to a sitting machine so as to slit the slab into a plurality of bands (12), turning each individual band (12) through 90 DEG , bunching together a plurality of such bands, spraying them on two opposite side faces with an elastomeric material, drying the elastomeric material so that the bands are bonded together along two faces of the bands extending normal to the planes or layers of fibres which make up the slab, and slitting the mat of bonded bands at right angles to the longitudinal axis of the bands into strips of blocks held together by the elastomeric films. <IMAGE>

Description

SPECIFICATION On-line production of mineral wool blocks and strips This invention relates to the on-line production of mineral wool blocks, preferably cubes, and strips of such blocks, from slabs of mineral wool. Such slabs may be made of rock, glass or slag wool, but are preferably of rock wool, which is resin bonded and produced using conventional equipment. In order to make the mineral wool material suitable for horticultural applications, i.e. so that liquid nutrients can penetrate the material due to capillary action, the resin, which may be a phenol-formaldehyde polymer, preferably contains a surfactant to improve the capillary action.

Cubes of mineral wool for horticultural applications are known, but these have been expensive to manufacture, in that the manufacturing process has been labour intensive.

Best results are obtained in horticulture if the seeds or cuttings to be grown in the cubes can be inserted into the cube, between adjacent planes of fibres. This then provides the best paths for root growth, and allows the cubes to be laid on a horizontal surface in a plant nutrient with the planes of fibres extending away from the surface at right angles, thus allowing capillary action between the planes of fibres to occur.

Traditionally, slabs of mineral wool are made up of many superimposed layers or planes of fibres, the exact quantity of layers dictating the thickness of the slab. To turn this slab into blocks, e.g. cubes, having dimensions corresponding to the thickness of the slab, the slab has to be slit normal to the planes of the layers of fibres first into strips, and these strips then have to be slit again, at right angles to their length (and to the said planes) to form the cubes. To the best of our knowledge, no one has been able to achieve this in the past using on-line apparatus and an on-line process.

The present invention makes on-line manufacture of blocks, i.e. cubes of mineral wool, possible and also allows us to produce cubes of mineral wool, preferably in strips, from which the cubes can be torn off as desired.

According to the broadest aspect of this invention, we provide a block of resin bonded mineral wool wherein a film of elastomeric material, e.g. natural or synthetic polymeric material, is provided on two opposite sides of the block which extend at right angles to the planes or layers of fibres in the block.

According to a preferred feature of the invention, we provide a strip of resin bonded mineral wool blocks, preferably having a width equal to their thickness, wherein two opposite faces of the strip extending normal to the layers of fibres in the strip have a film of elastomeric material, e.g. natural or synthetic polymeric material, thereon, the mineral wool being separated into distinct blocks throughout the length of the strip, the blocks being held together solely by the two films of elastomeric material.

Preferably, the length of each block in the strip corresponds to the thickness of the slab of mineral wool from which the strips are formed.

Also according to the present invention, we provide apparatus for forming blocks of bonded mineral wool linked together by a film of elastomeric material from a slab of mineral wool, comprising first conveyor means for feeding a slab of bonded mineral wool to a first slitting machine so as to slit the slab into a plurality of bands, further conveyor means to convey the bands in a direction extending at right angles to their longitudinal axis to a band orientation change device which turns the bands one at a time through 90 about their longitudinal axis, correlator means to cause said bands to be slowed down and bunched together without a gap between adjacent bands, spraying means to spray a film of elastomeric material onto two opposite side faces of the adjacent bands, means to dry said elastomeric material so that the bands are bonded together along two faces of the bands extending normal to the planes or layers of fibres which make up the slab, so as effectively to provide a mat of interconnected bands, and a second slitting machine downstream of the drying means for slitting the mat at right angles to the longitudinal axis of the bands into strips of blocks held together by the films.

Preferably, each of the slitting machines incorporate a plurality of spaced slitting devices, the spacing between adjacent ones of which corresponds to the thickness of the original slab, so as to produce a plurality of cubic blocks.

Preferably, second conveyor means is provided downstream of the first slitting machine, operating faster than the first conveyor means, to accelerate the bands of slab in a direction parallel to their longitudinal axis away from the slitting machine to a direction change conveyor. This may comprise a plurality of spaced rollers whose axes extend at right angles to the direction of feed of the bands, and a plurality of conveyor belts which move in a direction parallel to said roller axes to move the bands to the further conveyor means. The top run of the belts may be movable vertically relative to the supporting surfaces of said rollers, or vice-versa, or, alternatively, the belts may have spaced upstanding fingers thereon to feed the bands to the further conveyor means.

Preferably, the orientation change device comprises a plurality of ramp-like prongs located between a plurality of endless belts arranged side by side and forming the further conveyor means, the prongs terminating in a line extending across the further conveyor means, and spaced from its surface by an amount at least equal to half the thickness of the slab, there being spaced upstanding drive pins or the like on the belts which cause the bands to move up and along the fingers, and to tumble off the ends of the fingers, and to rotate through 90t as they do so and land on the belts again, which deliver them to the spraying means.

Preferably, the spraying means comprises two spaced apart spraying stations, and a device for turning over the mat of interconnected bands is provided between the two stations. Said device may comprise a vacuum lift conveyor having a perforated drive belt entrained around a large diameter vacuum drum, superimposed above another conveyor, the arrangement being such that the mat passes into a nip defined by the perforated belt and other conveyor, whereupon it is lifted by the vacuum, carried round the drum and turned over through 180 , ready to be passed through the second spraying station, and subsequently dried.

Drying of the elastomeric material may be achieved by passing the mat through drying ovens; if desired, the layout may be such that the mat is passed twice through a single oven. In a modification of the invention positive drying is not essential, but it will be appreciated that the manufacturing line will have to be sufficiently long to enable drying to take place.

Also according to the present invention, we provide a method of manufacturing blocks, e.g. cubes, of mineral wool, and strips of such blocks, as herein described.

A preferred embodiment of the present invention is now described by way of example with reference to the accompanying drawings, in which: Figure 1 is a partly schematic perspective view showing the layout of the apparatus; Figure 2 is a similar view showing the stages of formation of the blocks and strips on the apparatus of Fig. 1, and Figure 3 is a side elevation illustrating schematically how the band orientation change device operates.

Referring to the drawings, and in particular to Fig. 2, resin bonded material wool slabs 10 are produced in the conventional manner, fully cured, and the slabs, with a thickness equal to the intended length of the cube side, are passed on a first conveyor A through a multiple vertical slitter 1 and cut into bands 1 2 with widths equal to the slab thicknesses.

The cut bands 1 2 are then carried by a further conveyor B away from the slitter 1.

Conveyor B is operated at a faster speed than conveyor A so that when the slab has passed through the slitter 1 it accelerates to a direc siun change conveyor C. &commat;onveyor Colaveyos C has a plurality of parallel spaced rollers 14 whose axes are normal to the longitudinal axes of bands 12, there being a plurality of endless belts 1 6 located between the rollers 14, which move in a direction at right angles to the direction of movement of conveyor B, i.e.

parallel to axes of rollers 14. When all the bands 1 2 of a particular slab 10 have been completely transferred to conveyor C, a "finger" system on the belt 1 6 moves the cut material, i.e. the bands 12, in a direction at right angles to the initial direction of feed. A further set of endless conveyor belts D is then used to change the direction of orientation of the fibres in the bands of the cut slab. This is achieved by lifting the strips through a distance equivalent to half the length of the side of the intended cube by means of raised prongs 1 8 located between the belts. The prongs extend in the form of ramps from the surface of belts D. Their mode of operation is shown diagrammatically in Fig. 3.The bands are allowed to fall back onto the conveyor belts D having been turned through 90 . In order that the bands are aligned at right angles across the belts D it is essential that the tips (ends) of the prongs are themselves completely in a line at right angles to the direction of movement of the conveyor belts D.

The re-orientated bands are then bunched up by a correlator 20, so that there are no gaps between them, and are passed through a conventional spraying station 22 which coats the upper surface of the bunched bands with a solution or a dispersion of a rubber or synthetic elastomer. It is essential that the bands 1 2 are very close together to enable a continuous film of polymer to cover their upper surface. The sprayed bands of mineral wool are then continuously transferred to another endless conveyor which takes them through a drying oven E in Fig. 1. If any curing of the rubber/elastomer is required, it occurs here.

The bands 1 2 emerge from oven E in the form of a mat 24 of slit bands of mineral wool slab held together by a continuous film of flexible polymer on the upper surface. This mat 24 then passes into the nip formed by a further conveyor F and a turn-over device G.

The device G turns the complete mat 24 through 180 so that the polymer film bonded surface becomes the under surface of the mat. This is achieved by means of a vacuum drum 26 around which a perforated belt 28 is entrained as shown in Fig. 1. The mat 24 is then sprayed again with the rubber/elastomer solution or dispersion at a second spraying station 25 and passed through a drying/curing oven. The layout of the equipment may be such that a single oven E may be used, but this is not essential. The mat emerging from the second oven, or from a single oven for the second time, will then be coated on two opposite surfaces with the dried and, if necessary, cured polymer film, and the orientation of the fibres will be such that the plane of fibre lay up will be perpendicular to the films on the two surfaces. The material is then passed through another slicing or slitting device 30 which cuts the mat 24 formed of linked bands 1 2 into strips 32.

These strips are formed of a plurality of blocks of mineral wool, and so long as the spacing of the knives in each slitting device is equal to the depth of the original slab of mineral wool, the blocks are in the form of cubes.

Claims (18)

1. A block of resin-bonded mineral wool wherein a film of elastomeric material is provided on two opposite sides of the block which extend at right angles to the planes or layers of fibres in the block.

2. A strip of resin-bonded mineral wool blocks wherein two opposite faces of the strip extending normal to the layers of fibres in the strip have a film of elastomeric material thereon, the mineral wool being separated into distinct blocks throughout the length of the strip, the blocks being held together solely by the two films of elastomeric material.

3. A strip according to claim 2 wherein the blocks have a width equal to their thickness.

4. A block or strip according to any of claims 1 to 3 wherein the mineral wool is rock wool.

5. A block or strip according to any of claims 1 to 4 wherein the elastomeric material is a rubber or synthetic elastomer.

6. Apparatus for forming blocks of bonded mineral wool linked together by a film of elastomeric material from a slab of mineral wool, comprising first conveyor means for feeding a slab of bonded mineral wool to a first slitting machine so as to slit the slab into a plurality of bands, further conveyor means to convey the bands in a direction extending at right angles to their longitudinal axis to a band orientation change device which turns the bands one at a time through 90 about their longitudinal axis, correlator means to cause said bands to be slowed down and bunched together without a gap between adjacent bands, spraying means to spray a film of elastomeric material onto two opposite side faces of the adjacent bands, means to dry said elestomeric material so that the bands are bonded together along two faces of the bands extending normal to the planes or layers of fibres which make up the slab, and a second slitting machine downstream of the drying means for slitting the mat at a right angles to the longitudinal axis of the bands into strips of blocks held together by the films.

7. Apparatus as claimed in claim 6 wherein each of the slitting meachines incorporates a plurality of spaced slitting devices, the spacing between adjacent ones of which corresponds to the thickness of the original slab.

8. Apparatus as claimed in claim 6 or 7 in which second conveyor means is provided downstream of the first slitting machine, operating faster than the first conveyor means, to accelerate the bands of slab in a direction parallel to their longitudinal axis away from the slitting machine to a direction change conveyor.

9. Apparatus as claimed in claim 8 wherein the direction change conveyor comprises a plurality of spaced rollers whose axes extend at right angles to the direction of feed of the bands, and a plurality of conveyor belts which move in a direction parallel to said roller axes to move the bands to the further conveyor means.

10. Apparatus as claimed in claim 9 wherein the top run of said conveyor belts is movable vertically relative to the supporting surfaces of said rollers.

11. Apparatus as claimed in claim 9 wherein said conveyor belts have spaced upstanding fingers thereon to feed the bands to the further conveyor means.

1 2. Apparatus as claimed in any of claims 6 to 11 wherein the orientation change device comprises a plurality of ramp-like prongs located between a plurality of endless belts arranged side-by-side and forming the further conveyor means, the prongs terminating in a long line extending across the further conveyor means and spaced from its surface by an amount at least equal to half the thickness of the slab, there being spaced upstanding drive pins or the like on the belts which cause the bands to move up and along the fingers, and to tumble off the ends of the fingers, and to rotate through 90 as they do so and land on the belts again, which deliver them to the spraying means.

1 3. Apparatus as claimed in any of claims 6 to 1 2 wherein the spraying means comprises two spaced apart spraying stations, and a device for turning over the mat of interconnected bands is provided between the two stations.

14. Apparatus as claimed in claim 1 3 wherein said device for turning over the mat of interconnected bands comprises a vacuum lift conveyor having a perforated drive belt entrained around a large diameter vacuum drum, superimposed above another conveyor, the arrangement being such that the mat passes into a nip defined by the perforated belt and other conveyor, whereupon it is lifted by the vacuum, carried round the drum and turned over through 180 , ready to be passed through the second spraying station, and subsequently dried.

1 5. Apparatus as claimed in any of claims 6 to 1 4 wherein the means to dry said elastomeric material comprises one or more drying ovens.

16. Apparatus for forming blocks of bonded mineral wool, substantially as described with reference to the drawings.

17. A method of manufacturing blocks of resin bonded mineral wool comprising forming a slab of bonded mineral wool, feeding said slab through a first slitting machine so as to slit the slab into a plurality of bands, conveying said bands in a direction extending at right angles to their longitudinal axes to a band orientation change device which turns the bands one at a time through 90 about their longitudinal axes, bunching said bands together without a gap between adjacent bands, spraying a film of elastomeric material onto two opposite side faces of the adjacent bands, drying said elastomeric material so that the bands are bonded together along two faces of the bands extending normal to the planes or layers of fibres which make up the slab, and slitting the mat at right angles to the longitudinal axis of the bands into strips of blocks held together by the films.

1 8. A method according to claim 17, substantially as described.

1 9. Blocks of mineral wool fibres, whenever made by the method of claim 1 7 or claim

18.