IE45498B1 - Method and apparatus for manufacturing composite surface elements - Google Patents

Abstract

Method of manufacturing mixed surface elements with natural stone, which have a sheet of stone attached to a support sheet, characterized in that it comprises the steps of: i) cutting a block of natural stone finishing in a certain number of plates. ii) apply and adhere to each of the two opposite faces of each stone plate a support sheet iii) position each plate iv) apply suction to the suction cups to keep the plate rigidly in position between them; v) saw the plate in two.

Description

This invention concerns a method and apparatus for the construction of composite surface elements, such as tiles and panels, having a natur.il stone facing. Such elements are intended for use, for example, in the cladding of walls, ceilings or other -surface, in the manufacture of furniture, and for all purposes where natural stone surfaces are required.

Natural stone, such as marble, is an exquisite surfacing material on account of its hardness and durability, its beauty of structure and the high polish which can usually be imparted to it, but its use is greatly restricted by reason of its weight and expense, since the material is liable to fracture if not of a certain thickness, depending upon the handling and usage to which it may require to be subjected. These drawbacks are overcome by the invention the subject of ' Patent Nos. 30931 and 39053 which describe a method of 1 preparing a stone-faced composite surface element having a lamina of stone bonded to a backing sheet comprising adhesively bonding to the surface of a stone slab a backing sheet of lightweight multicellular material of substantially greater thickness than said lamina, and thereafter sawing off a portion of said slab to leave a thin marble lamina adhered to said sheet of multicellular material. As the backing sheet supports the lamina when it is being cut, the risk of cracking the lamina is reduced and remarkably thin stone laminae of the order of between 2 and 5 mm in thickness, may be obtained. Preferably, in carrying out the aforesaid method a large block of stone is first cut into a number of slabs which are of the order of 20 to 25 mm in thickness. The slabs are dried and a light-weight backing sheet is bonded to each of the two opposite faces of the slab. The slab is then sawn in two along a cutting plane substantially parallel to and midway be tween said faces to leave a thin layer of stone attached to each backing sheet. I one method a plurality of slabs, v/ith backing sheets attached, are firmly clamped together in parallel relation, and the slabs are each cut in two, as described above, using a gang saw. A centra·! planar section of each slab, of a width - 2 45498 greater than half the thickness of the slab, is pulverized by the saw blade during the sawing operation. Thus, it will be appreciated that as the saw moves down through the slabs a gap having a width of between, say 12 and 17 mm in thickness, is left between the partly-cut stone layers. Because of die inward pressure exerted by the clamps the partly-cut stone layers are pushed towards each other which causes cracking of the layers. Furthermore, considerable pressure is exerted on the saw blade which prevents a smooth cut from being obtained.

It is an object of the invention to overcome the aforesaid disadvantage and to provide a method and apparatus for rigidly supporting the slab during the sawing operation without exerting inwardly directed pressure on the partly-cut stone layers or on the saw.

Accordingly, the invention provides slab-gripping apparatus fi rst comprising first gripping means in the form of at least one/vacuum-operated suction cup, second gripping means in the form of at least a second vacuumoperated suction cup disposed in opposed spaced relation to said first suction cup, such that a stone slab may be positioned between said suction cups, and means for applying suction to each of the cups such that said first cup is adapted to grip one face of the slab while said second suction cup is adapted to grip the opposite face of the slab.

The invention also provides a method of manufacturing composite surface elements utilizing the aforesaid slab-gripping apparatus, the method comprising: i) positioning between oppositely arranged vacuum cups a slab of natural facing stone which has bonded to each of two opposed parallel faces of the slab a backing sheet comprising a core of light-weight sheet material which is resistant to compressive forces in a direction substantially normal to'the plane of the sheet; ii) applying suction to the cups to hold the slab rigidly - 3 45493 in position therebetween; iii) sawing the slab in two along a cutting plane substantially parallel to and midway between said faces to leave a thin stone layer adhered to each said backing sheet, and during said sawing step maintaining said suction to inhibit relative movement of the partly-cut stone layers.

The slabs can be cut in well-known manner from a block of natural facing stone. The slabs are cut with two opposite parallel faces and having a thickness greater than twice the thickness of the lamina required. Before bonding the backing sheet thereto, the stone slabs are dried, either by leaving them for a period in racks to dry naturally, or by means of force drying. When thd slabs are,perfectly dry the light-weight backing is attached to the opposed faces of e£ciu§lab, e.g^yjaearis^pf an epoxy resin. The backing preferably comprises a light-weight core material, e.g. a multicellular metal core, which has a skin of sheet material of greater tensile strength than the backing sheet bonded to at least that surface of the core remote from the I I surface to which the stone is attached. Preferably, however, both surfaces of < · the core are reinforced with a skin of sheet material. The reinforcing skins may be attached to the core before or after the sawing step but are preferably attached before. Suitably, the reinforcing skihs each comprises a woven glass fibre mat which is pre-rmpregnated with an epoxy resin which is not fully cured. The mat is thep applied to each of the opposed surfaces of the core material and is cured in position.

One embodiment pf the apparatus of the/invention is described hereinafter with reference to\the accompanying drawings, wherein: Figure 1 is a side elevation of support apparatus; Figure 2 is a front elevation of the apparatus shown in Figure 1, and Figure 3 is a side elevation of a modification of the apparatus shown in Figure 1. - 4 45498 Referring to the drawings, lT.e apparatus cciipri,m upright i'r.i·.;·- : ! i-r supported on a stand 2. Tlie I'r.iiiie member I is provide!' with three tui.-uI..r‘ supports 3, which are arranged vertical ly in tlie frame πίΛ.·ι· and are pare! lei to each other. A vacuum-operated suction cup 4 is mounted on each support 3 and is movable vertically along the- support. A clamp member 5 is provided on each suction cup 4 to lock the suction cup in position at a desired location on the support 3. A tilting'arm 6 is pivotally connected by a pivot 7 to the stand 2 at a position opposite to, but spaced from, the frame member 1. The tilting arm 6 is provided witii a clamp member 8 which serves to lock the arm in a desired > position. A tubular support 9 is hingedly connected to the end of the tilting arm by means of a pivot 10. The pivot 10 is provided with a clamp member by means of which the tubular support 9 can be locked relative to tho arm (>. Λ vacuum-operated suction cup 4a is mounted on the support 9 and is movable vertically along the support, Ihe cup 4a can be locked in position at a desired location by means of a clamp member 12. The suction cups 4 and 4a are connected by suitable tubing 13 to a vacuum pump 14. in operation of the device, a slab of facing stone which has been provided on opposite faces with a backing, as described above, is positioned on its edge in an upright position between the frame member 1 and the tilting arm 6. The suction cups 4 are suitably positioned on the tubular support 3 having regard to the height of the slab. The clamps 8 and IQ are opened and the arm 6 and support 9 are tilted relative to each other until tho suction cup 4a_ is parallel to and in contact with the outer surface of the slab. The cup 4a_ is preferably positioned about midway up the slab. The clamps 5, 8' and 10 are then locked and suction is applied to the cups 4 and 4a. to hold the composite element rigidly in position. The circular saw is then moved into position and cuts the slab down the middle as described above. The clamp 8 may then be opened and the composite element which is left attached to the suction cup 4a. can then be moved from the outer element, which is supported-by the suction cups 4, by tilting the support - 5 45488 9 outwardly until the slab element is held horizontally. Vacuum to the cup 4a may then be disconnected. Preferably, there are separate vacuum controls for all of the cups 4, 4a_ so that they can be disconnected separately from the vacuum source.

The slab of stone before cutting is suitably of a thickness of the order of to 25 mm. About 12 to 17 mm of the stone is lost in the cutting, depending upon the thickness of the sawblade, and so the resultant laminae are each about 4 mm in thickness, and a further 1 mm of each lamina is lost in polishing and grinding so that the final composite surface elements each have a lamina of stone of about 3 mm in thickness.

It will be appreciated that a number of modifications may be made to the gripping device without departing from the scope of the invention. For example, the support arm 9 may be provided with two suction cups 4a^ which may be mounted on a horizontally extending arm so as to provide for horizontal adjustment of the cups. Furthermore, means may be provided for longitudinal adjustment of the tilting arm 6. Furthermore, the number of suction cups on the frame member 1 can be altered to suit the size of panels. Means may also be provided to ensure that the cups 4 are kept co-planar with the. frame 1 so as to prevent bowing,of the panel.

As mentioned previously, the function of the vacuum cups 4, 4a_ is to hold the slab rigidly during sawing without applying any substantial inwardly-directed pressure. Thus, it is important to ensure, when applying and locking the cup 4a_ in position against the slab, that it is not pressed too tightly inwards. This can be avoided by using the modification shown in Figure 3. In this modification the clamp member 8 is dispertsed with. Instead the tilting arm 6 is provided with a nut 16 or the like, which is welded or otherwise secured to the arm 6. The nut 16 receives, in screw engagement, a threaded rod 17 which, when the arm is positioned as shown in Figure 3, rests against a stop 18. Thus the maximum inward - 6 4 S 4 9 8 tilt of the dial (> cun be predetermined by suitably adjusting the projecting length of the rod 1'/- * The red 17 can be secured in a desired position by means of a lock nut 19.

The method and apparatus described above are particularly suitable for 5 use in the manufacture of marble-faced composite surface elements, however, they may also be used in the manufacture of composite elements having other natural stone facings such as granite or onyx. - 7 4549 S

Claims (13)

1. Slab-gripping apparatus comprising first gripping means in the first form of at least one/vacuum-operated suction cup, second gripping means in the form of at least a second vacuum-operated suction cup disposed in opposed spaced relation to said first suction cup, such that a stone slab may be positioned between said suction cups, and means for applying suction to each of the cups such that said first cup is adapted to grip one face of the slab while said second suction cup is adapted to grip the opposite face of the slab.

2. Slab-gripping apparatus as claimed in Claim 1, wherein said first and second vacuum cups are disposed in a substantially vertical plane such that they are adapted to grip the opposite faces of said slab when the slab is stood on its edge, in a substantially upright position, between said vacuum cups.

3. Slab-gripping apparatus as claimed in either of Claims 1 or 2, wherein means are provided for moving said second gripping means towards and away from said first gripping means so as to facilitate positioning of said slab between the opposed vacuum cups.

4. Slab-gripping apparatus as claimed in Claim 3, wherein said second vacuum cup is mounted on an upright support member which is hinged at its lower end to enable the vacuum cup to be moved towards or away from the surface of the slab when the slab is positioned between said first and second gripping means.

5. Slab-gripping apparatus as described in Claim 4, wherein said upright support member is additionally articulated intermediate its length.

6. Slab-gripping apparatus as claimed'in Claims 4 or 5, wherein said second vacuum cup is movable along said support means and means are provided for clamping said vacuum cup at a desired position on said support member.

7. Slab-gripping apparatus as claimed in any of Claims 1 to 6, . first wherein said first gripping means comprises at least one/vacuum cup mounted on an upright frame, means being provided for adjusting the position of the vacuum - 8 45498 cup on the frame.

8. Slab-gripping apparatus as claimed in any of Claims 1 to 7, wherein said first gripping means comprises a plurality of vacuum cups each of which is slidably mounted on an upright support member, which support members are disposed in parallel relation in said frame and means are provided for clamping each said vacuum cup in a desired position on its respective support member.

9. Slab-gripping apparatus as claimed in Claim 4 or 5, wherein said support member is provided with stop means to control the inward movement of said second vacuum cup.

10. Slab-gripping apparatus substantially as hereinbefore described with reference to Figures 1 and 2 or 3 of the accompanying drawings.

11. Slab-gripping apparatus as claimed in any one of the preceding claims in association with a saw which is adapted co cut a stone slab positioned between oppositely arranged vacuum cups of the slab-gripping apparatus.

12. A method of manufacturing composite surface elements utilizing the slab-gripping apparatus as claimed in Claim 11 which comprises: i) positioning between oppositely arranged vacuum cups a slab of natural facing stone which has bonded to each of two opposed parallel faces of the slab a backing sheet comprising a core of light-weight sheet material which is resistant to compressive forces in a direction substantially normal to the plane of the sheet; ii) applying suction to the cups to hold the slab rigidly in position therebetween; iii) sawing the slab in two along a cutting plane substantially parallel to and midway between said faces to leave a thin stone layer adhered to each said backing sheet, and during said sawing step maintaining said suction to inhibit relative'movement of the partly-cut stone layers. _ 9

13. A method as claimed in Claim 12, wherein the slabs are dried before said backing sheet is bonded thereto.· Dated this 11th day of Hay, 1977. BY:- TOMKINS & Applicantfs Acj&nts, (Signed) j fUartmoutn Roady DUBLIN 6. - 10 Patrick Terence Bourke, Earl of Mayo One sheet