GB2068291A - Apparatus for and a method of cleaving laminated material - Google Patents

Abstract

The apparatus comprises two gripper members (11 & 12) relatively movable towards and away from each other by power operated means (14) such that with a plate of laminated material disposed between the gripper members, the latter can be moved towards each other to grip opposing faces of the plate and then can be moved away from each other to apply a splitting strain. A trigger cut at an edge of a desired cleavage plane is formed in the plate by a blade operated by further power operated means (19). Each gripper member comprises a suction device connected to a source of negative pressure, each suction device comprising a rigid plate (20) having an annular seal of compressible, resilient material (21, 22) preferably closed-cell cellular material, on one face thereof i.e. that face adjacent to the other suction device. <IMAGE>

Description

SPECIFICATION Apparatus for and a method of cleaving laminated material This invention relates to apparatus for and a method of cleaving laminated material, e.g.

slate.

A plate of laminated material, e.g. slate is commonly split by manually inserting a blade into the edge of the plate along a cleavage plane and by controlled manual penetration of the blade the plate is separated in two parts along said cleavage plane.

According to one aspect of the present invention, there is provided apparatus for cleaving laminated material, comprising two gripper members, first power operated means for relatively moving the gripper members towards and away from each other, such that, in use, with a plate of laminated material disposed between the gripper members, the latter can be moved towards each other to grip opposing faces of the plate and then can be moved away from each other to apply a splitting strain to the plate, a blade, and second power operated means for causing the blade to apply an impact to the plate in a direction perpendicular to the direction of relative movement of the gripper members to form a trigger cut at an edge of a desired cleavage plane, wherein each gripper member comprises a suction device connected to a source of negative pressure, each suction device comprising a rigid plate having an annular seal of compressible resilient material on one face thereof, i.e. that face adjacent to the other suction device.

Preferably, the annular seal is formed of cellular and advantageously of closed-cell material, such as neoprene foam.

Conveniently, the annular seal comprises two annular sealing members disposed one inside the other. This is of particular advantage if each sealing member is formed from one elongate strip of material joined at its ends, because the joints can be staggered relative to each other to prevent leakage through the two joints.

Preferably, resilient abutments are attached to said one face of each rigid plate within the annular seal to prevent excess bending of the laminated plate. In this case, the resilient abutments are conveniently formed of the same material as the seal.

Conveniently, the first and second power operated means each comprise pneumatically operated means. In this case it is advantageous that a pneumatic control circuit is provided for controlling the pneumatically operated means, the control circuit including a vacuum control valve for sensing the negative pressure in the suction devices and providing a signal to maintain the negative pressure with the suction devices during a gripping operation within predetermined upper and lower limits. Moreover, in this case, it is advantageous that the second power operated means comprises a pneumatic impact piston and cylinder unit.

Conveniently, there is also provided a selfcentering device for positioning the blade means midway between the gripper members prior to said second power operated means causing the blade means to apply an impact to the laminated plate. In this case, the blade means may comprise a blade mounted in a carriage guided for movement in a direction parallel to the direction of relative movement of the gripper members and the self-centering device may comprise a cam fojlower fixed relative to each gripper member, the cam surfaces being convergent and being arranged so as to overlap each other as the gripper members approach each other, a cam follower supported by the carriage and disposed between the cam surfaces, and resilient means for biassing the cam follower into engagement with both cam surfaces at least when the latter overlap each other.

According to another aspect of the invention, there is provided a method of cleaving laminated material using the apparatus of the first aspect of the invention and comprising the steps of: (a) disposing a plate of laminated material between the two gripper members, then (b) relatively moving the gripper members towards each other to grip the plate of laminated material, then (c) relatively moving the gripper members away from each other to apply a splitting strain to the plate of laminated material, then (d) forming a trigger cut at an edge of a desired cleavage plane of the plate of laminated material.

The invention also provides laminated material, particularly slate, split by the above method.

The invention will now be more particularly described with reference to the accompanying drawings, wherein: Figure 1 is a schematic side view of embodiment of apparatus according to the invention, with parts removed for reasons of clarity; Figure 2 is a side view of the self-centering device of Fig. 1; and Figure 3 is a front view of one of the gripper members.

Referring now to Fig. 1, the apparatus shown therein comprises a support structure 10, a first gripper member 11 fixedly mounted on the support structure 10 and a second gripper member 1 2 which is supported on spaced parallel guide rods (one of which is shown at 13) for movement towards and away from the member 11 by a pneumatic piston and cylinder unit 14.

A blade carriage 1 5 is mounted on the spaced parallel guide rods 1 3. The carriage 1 5 is movable thereon in a direction parallel to the direction of movement of the gripper member 1 2 and supports a blade 1 7 (Fig. 2) which is guided for vertical movement, i.e.

movement in a direction perpendicular to the direction of movement of the gripper member 1 2 and carriage 15, in response to an impact applied thereto by a hammer head 1 8 mounted on the free end of the piston rod of a pneumatic impact piston and cylinder unit 1 9. Such impact piston and cylinder units are known and possess the advantage that very rapid acceleration of the piston rod is produced by a differential area arrangement which suddenly exposes the full area of the piston to high pressure air built up in a reservoir in the rear end of the cylinder. The carriage 1 5 may be located at a desired position on the rods 1 3 or may be automatically positioned by a self-centering device which will be described more fully hereinafter.

Referring to Fig. 3, each gripper member is in the form of a suction device which comprises a rigid plate 20 whose outline is selected to substantially match that of a plate of laminated material to be split. The rigid plate 20 has at least one, and as shown two annular sealing members 21 and 22 formed of resilient material which is sufficiently compressible to seal against an irregular surface of a laminated plate. In a preferred embodiment, the sealing members 21 and 22 are formed of cellular preferably closed-cell, material such as neoprene foam.Near to the centre of the plate 20, there is a port 23 which is connected to a source of negative pressure, such as a vacuum pump, and inwardly of the sealing members 21 and 22 there are provided several abutments formed of resilient material, such as neoprene foam, which are so arranged as to prevent excess bending of a laminated plate when negative pressure is applied thereto, since any such excess bending may result in pillaring of the plate.

In operation, the plate of laminated material to be split is located between the gripper members 11 and 1 2 and supported in a vertical position on a horizontal base plate (not shown) mounted above the guide rods 1 3 and just below the gripper member 1 2. A roller (not shown) having its axis extending parallel to the axes of the guide rods 1 3 may be provided to support the plate of material to be split as it is moved into position between the gripper members 11 and 1 2. After the plate of material has been located between the members 11 and 12, the gripper member 1 2 is moved towards the gripper member 11 by the piston and cylinder unit 14 so that the two gripper members engage opposing faces of the laminated plate.Movement of the gripper member 12 is arranged such that the seals 21 and 22 of the two gripper members are sufficiently compressed to seal against the laminated plate which may, as aforesaid, have an irregular surface.

Pneumatic pressure is then applied to the opposite end of the piston of the unit 14 so that a splitting strain is applied to the laminated plate and the impact unit 1 9 is operated to propel the blade 1 7 upwardly to form a trigger cut in the lower edge of the laminated plate along a preselected cleavage plane, the combination of the trigger cut and the gripping strain causing the plate to split into two parts.

At an instance of splitting, dust and other minor particles are released from the plate.

This dust can be injurious to an operator and to safeguard the operator against this dust, the apparatus is provided with a transparent cover 25 (see Fig. 1) which together with the support structure 10 defines a housing which substantially encloses the laminated plate during a splitting operation. The cover has a transparent access door 26 which is arranged to open only after a splitting operation has been completed and which may also operate a microswitch to initiate a splitting operation immediately it has been closed. As shown, a peripheral air inbleed opening is provided between the lower end of the cover 25 and the support structure 10, although this opening may alternatively be formed only in the front wall of the cover 25, that is to say that wall remote from the piston/cylinder unit 14.In any event the opening should be arranged so that air entering the housing has an upward component of flow. The rear wall of the cover, that is to say the wall from which the unit 14 projects, has an outlet opening just below the upper edges of the gripper members 11 and 1 2 to which opening is connected a flexible hose 27. The hose is connected to an extractor fan 1 6 which promotes a flow of air through the cover 25. The arrangement of the air inbleed opening and outlet opening is such as to cause the air to flow at least past the upper edge of the laminated plate where the dust particles are produced. The cover 25 may be pivoted rearwardly about a horizontal axis 25a parallel to and adjacent the rear wall thereof to permit maintenance to be carried out on the apparatus.

An outlet hopper 28 is provided in the base of the support structure to allow heavier elements which fall downwards on the machine base to be conveyed to a waste tip on a conveyor 29 arranged below the hopper 28 which may be provided with an air cylinder operated seal plate. Moreover, a sheet air generator may be provided for blowing a curtain of air across the base plate to convey any heavier particles falling thereon towards the hopper 28.

As previously mentioned, the blade 1 7 is mounted in the carriage 1 5 which is movable along guide rods 1 3. The carriage could be releasably secured to the guide rods 1 3 at the desired position by an operator by means of a releasable fastener or could for instance be moved along the guide rods by a rotatable screw and nut arrangement whereby the position of the carriage 1 5 could be adjusted by rotation of a handwheel located on the outside of the base structure 10. However, when splitting slate it is common to split it into two halves and then depending upon the thickness of each half, to split them each again into a further two halves.For this purpose, the carriage 1 5 is provided with a self-centering device (as shown in Fig. 2) so that the blade 1 7 is automatically located for movement in a plane midway between the gripper members 11 and 1 2. The self-centering device comprises cam surfaces 30 and 31 on arms 32 and 33 which depend respectively from the gripper members 11 and 1 2. The cam surfaces are upwardly convergent and inclined at 45 to the vertical. The cam surface 30 is fixed since the gripper member 11 is fixed and the cam surface 31 moves with the gripper member 1 2 towards and away from the cam surface 30.The carriage 1 5 supports a cam follower which includes a roller 34. the roller 34 is mounted on a slider 35 which is guided for vertical movement in the carriage 1 5 and which is biassed upwardly by a compression spring 36. The roller is arranged to lie between the cam surfaces 30 and 31 so that as the gripper member 1 2 approaches the gripper member 11, the roller is engaged by the cam surface 31. Further movement of the gripper member 1 2 towards the gripper member 11 will result in movement of the roller 34 and thus of the slider 35 and carriage 1 5 along the guide rods 1 3 until the roller abuts the cam surface 30.At this stage, the cam surfaces 30 and 31 will be in overlapping relationship and will define an inverted V-shaped groove. Further movement of the cam surface 31 towards the cam surface 30 will result in downwards movement of the roller 34 along both cam surfaces 30 and 31 with the axis of the roller located directly below the apex of the inverted V-shaped groove. The blade 1 7 is mounted in the carriage 1 5 such that whatever the final spacing between the gripper members 11 and 1 2 the blade will be movable in a vertical plane midway between the gripper members 11 and 1 2. For loose positioning and to provide resilience, at least one and preferably two compression springs 37, 38 act between each end of the carriage 1 5 and the associated gripper member 11 , 1 2 respectively. The springs 37 and 38 are mounted about the guide rods 1 3.

Claims (16)

1. Apparatus for cleaving laminated material, comprising two gripper members, first power operated means for relatively moving the gripper members towards and away from each other such that, in use, with a plate of laminated material disposed between the gripper members, the latter can be moved towards each other to grip opposing faces of the plate and then can be moved away from each other to apply a splitting strain to the plate, a blade, and second power operated means for causing the blade to apply an impact to the plate in a direction perpendicular to the direction of relative movement of the gripper members to form a trigger cut at an edge of a desired cleavage plane, wherein each gripper comprises a suction device connected to a source of negative pressure, each suction device comprising a rigid plate having an annular seal of compressible, resilient material on one face thereof i.e. that face adjacent to the other suction device.

2. The apparatus of claim 1, wherein the annular seal is formed of cellular material.

3. The apparatus of claim 2, wherein the annular seal is formed of closed-cell material.

4. The apparatus of any one of claims 1-3, wherein the annular seal is formed of neoprene foam.

5. The apparatus of any one of claims 1-4, wherein the annular seal comprises two annular sealing members disposed one inside the other.

6. The apparatus of any one of the preceding claims, wherein resilient abutments are attached to said one face of each rigid plate within the annular seal to prevent excess bending of the laminated plate.

7. The apparatus of claim 6, wherein the resilient abutments are formed of the same material as the seal.

8. The apparatus of any one of the preceding claims, wherein the first and second power operated means each comprise pneumatically operated means.

9. The apparatus of claim 8, wherein a pneumatic control circuit is provided for controlling the pneumatically operated means, the control circuit including a vacuum control valve for sensing the negative pressure in the suction devices and providing a signal to maintain the negative pressure within the suction devices during a gripping operation within predetermined upper and lower limits.

1 0. The apparatus of any one of the preceding claims, wherein one of the suction devices is fixed relative to a support and only the other suction device is movable by the power operated means.

11. The apparatus of any one of the preceding claims, wherein the second power operated means comprises a pneumatic impact piston and cylinder unit.

1 2. The apparatus of any one of the preceding claims, further comprising a self-centering device for positioning the blade midway between the gripper members prior to said second power operated means causing the blade to apply an impact to the laminated plate.

1 3. The apparatus of claim 12, wherein the blade is mounted in a carriage guided for movement in a direction parallel to the direction of relative movement of the gripper members and the self-centering device comprises a cam surface fixed relative to each gripper member, the cam surfaces being convergent and being arranged so as to overlap each other as the gripper members approach each other, a cam follower supported by the carriage and disposed between the cam surfaces, and resilient means for biassing the cam follower into engagement with both cam surfaces at least when the latter overlap each other.

14. A method of cleaving laminated material using the apparatus of anyone of the preceding claims and comprising the steps of: (a) disposing a plate of laminated material between the two gripper members, and (b) relatively moving the gripper members towards each other to grip the plate of laminated material, then (c) relatively moving the gripper members away from each other to apply a splitting strain to the plate of laminated material, then (d) forming a trigger cut at an edge of a desired cleavage plane of the plate of laminated material.

1 5. Laminated material split by the method of claim 1 4.

16. Slate split by the method of claim 14.