SLICING COMPRESSED BLOCKS

Abstract: A block of compressed, stratified material such as a bale (10) of tobacco is placed in a receptacle (40) which executes reciprocating motion. Movement of the receptacle (40) brings the bale (10) into engagement with a fixed blade (46) which splits the bale (10) between strata, the unsupported weight of the slice (48) being separated assisting the splitting. A photodetector (62) initiates the loading of a further bale (10) when uncovered. The further bale (10) is carried by an indexing conveyor (42) mounted on a wheeled chassis (64) which moves the conveyor (42) over the remainder of the bale in the framework (40) then retreats leaving the further bale (10) on top of the remainder.

Description: SLICING COMPRESSED BLOCKS The present invention relates to apparatus for slicing blocks of compressed stratified material by splitting them along planes generally parallel to the strata. One known slicing apparatus is described in EP-A-0159836. A bale of compressed tobacco is brought to the slicer by conveyor and then, by means of a first pusher member, is transferred to a scissor lift. The bale is raised to the desired height at which a driven knife blade, moving in a horizontal plane, cuts a slice from the top of the bale. A second pusher member ejects the cut slice into a chute from where it is transported to a conditioning unit. During cutting of a slice, the scissor lift lowers the bale slightly to cause the bale to split between strata of compressed tobacco in advance of the moving knife blade. Causing the bale to split between the strata is particularly important as this avoids tearing and degradation of the tobacco leaf. The apparatus described above has a number of disadvantages, many arising from the complexity of the control circuitry required to sequence the operation of the first and second pusher members, the scissor lift and the moving blade. The use of a scissor lift increases the control problems as it requires a non-linear control to produce a constant step lift. There is also an enforced discontinuity in the operation; when a bale has been sliced, the scissor lift has to be lowered, a new bale moved onto it, and then be raised again to the required position for cutting the first slice. In accordance with the present invention there is - 1- provided apparatus for slicing blocks of compressed stratified ...aterial, such as bales of tobacco, having a first fixed blade extending in a substantially horizontal plane and means for moving a block having substantially horizontal strata into and out of engagement with the blade to separate a slice from the bottom of the block by splitting the block between strata. The means for moving the block may be a driven receptacle executing controlled reciprocating motion into which a block or stack of blocks may be placed. The apparatus may include means, such as a photocell, for detecting when the thickness of remaining portion of the block yet to be sliced falls below a predetermined value, for initiating a reloading sequence. Since the slices are taken from the bottom of a block, further blocks may simply be stacked on top so that there is no need to stop the slicer to load a new block. The apparatus is preferably open below the fixed blade so that the unsupported weight of the slice being cut assists the splitting of the block between strata. The apparatus may include means for breaking up the slices separated from the bottom of a bale. Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which : Figs 1 to 3 show, in elevation, successive work stations of a tobacco bale-slicing plant; Figs 4 to 7 are schematic side elevational views of the bale slicing plant shown in Figs.l to 3 and showing the slicing and reloading operations; Fig 8 is a view similar to Fig 4 of a modified slicing olant which separates two slices at a time; Fig 9 is a view similar to Fig 4 showing another modified slicing plant which separates a further slice on the return stroke; Fig 10 is a partially cut away side elevation showing a slice breaking device which breaks up slices separated by the slicing plant; Fig 11 is a part sectional view taken on line XI-XI of figure 10; and Fig 12 is a part sectional view taken on line XII-XII of figure 10. Referring initially to Fig.l, the initial stages of a tobacco bale slicing plant are shown. The initial plant stations S.l to S.4 are each based on individual roller belt conveyor sections 12, 14, 16, 20, 24, each section being driven by a separate motor M. A packaged bale 10 of compressed tobacco is loaded onto the roller belt section 12 at station S.l by, for example, a fork lift truck having a case handling attachment. At station S.l the packaging of the tobacco bale, usually consisting of a cardboard box with an inner liner is opened. The motors M of the first and second conveyor sections 14 are then started to index the bale 10 to the second station S.2, where the cardboard top of the packaging is folded down the side of the case and the inner lining is peeled back to expose the top of the bale 10. The third conveyor section 16 is used a holding conveyor from which the bale 10 is transferred to a bale inverter 18, at station S.3. The inverter 18 has two identical conveyor sections 20 mounted in a driven circular frame 22. A bale 10 from the holding conveyor 16 is indexed onto the first inverter conveyor section 20A following which the frame 22 is rotated through 180° thereby depositing the bale 10 on the second inverter conveyor section 20.B from where it is indexed to a further conveyor section 24 at station S.4. The cardboard packaging is now lifted from the bale with the aid of a lifting frame 26 and hoist (figure 2) and the inner lining can be completely removed to leave the exposed bale on the conveyor 24. Indexing of bales 10 through the unpacking stages (stations S.l to S.4) is controlled by foot operated switches activating a timed sequence. The unwrapped bale 10 is indexed to a further conveyor section 28 similar to those of stations S.l to S.4 and mounted in a chain driven lifting frame 30. The lifting frame 30 raises the conveyor section 28 carrying the bale 10 to the desired height for indexing onto the loading conveyor 42 of station S.6, the bale slicer 32. The lifting frame 30 is driven by a fail safe brake motor 31. In .an alternative embodiment (not shown) the lifting frame 30 may carry a number of conveyor sections operating in sequence to minimize delays in loading and unloading and to provide storage capability. From the loading conveyor 42, the bale is deposited in an open bottomed receptacle 40 and supported by a fixed horizontal platform 44 (see fig.4). Under control of a motor driven conveyor chain, the receptable 40 executes reciprocatory motion. As it does so, the bale impinges a fixed blade 46 which splits the bale 10 between the horizontal strata. In this way a slice 34 of a thickness corresponding to the separation of the platform 44 and the fixed blade 46, is separated from the bottom of the bale 10. Slices 34 cut from the bale 10 are deposited onto an inclined conveyor 36 which carries the slices 34 to station S.7 which is a conditioning unit 38 as shown in fig 3. The conditioning unit 38 is an inclined-axis rotating cylinder in which the slices are moisturised and broken up into individual leaf sections for subsequent transfer to, for example, a cigarette manufacturing plant. Referring to fig 4, a bale to be sliced is deposited in the slicer receptacle 40 by the indexing loading conveyor 42. The bale 10 rests on a first horizontal support platform 44, across which it is moved by the receptable 40 into engagement with the fixed blade 46. The slice 48 being cut from the bottom of the bale 10 is unsupported and its weight assists the splitting between strata of compressed tobacco leaf in advance of the fixed blade 46. The remainder of the bale is supported by a second suport platform 50 extending from the fixed blade 46 onto which it is pushed by the advancing receptable 40, as shown in fig 5. When a slice 34 has been cut, it drops onto a broken-back rpnveyor 36 for transport to the conditioning unit 38 as described above. The moving receptacle 40 has a trip block 52 which activates a limit switch 54 at the end of the receptacle travel. This causes control circuitry to reverse the direction of travel. The rear wall 56 of the receptacle 40 then pushes the remainder of the bale off of the second support platform 50 allowing it to drop onto the first platform 44 once clear of the fixed blade 46. A second limit switch 58 is then activated by the trip block 52 to again reverse the direction of receptacle travel. In this way, the receptacle 40 is controlled to execute reciprocatory motion, thereby repeating the bale slicing operation. The receptacle 40 is driven and supported by a heavy-duty roller conveyor chain 60 which is in turn driven, through a shaft mounted gearbox, by a three-phase a.c. electric motor. An a.c. invertor arrangement is provided to give control of the motor speed and torque. Insufficient thickness of the remainder of the bale in the receptacle 40 is detected by a photocell 62. When the photocell 62 is uncovered as a result of the reduction in thickness of the remainder of the bale in the receptacle, as in fig 5, a loading sequence for a new bale is initiated. Following delivery by the lifting frame 30, the new bale 10 is moved onto the indexing loading conveyor assembly 42. The indexing conveyor 42 consists of a roller belt assembly mounted on a driven rolling chassis 64, the movement of which is limited by a trip block 66 and limit switches 68, 70. When the loading sequence is initiated by the photocell 62, the indexing conveyor assembly, with the belt stationary is moved t?wards the slicer until the trip block 66 encounters the forward limit switch 68 and stops the assembly. As the receptacle 40 approaches on a return (non-slicing) stroke, the receptacle trip block 52 activates an intermediate trip switch 72 which starts the indexing conveyor belt. The sequence is timed by control circuitry so that the front face of the new bale 10 meets the rear wall 56 of the receptacle 40 as the receptacle reaches the limit of its travel and the trip block 52 activates limit switch 58, as shown in fig 6. In addition to reversing the direction of travel of the framework 40, activation of the limit switch 58 causes the indexing conveyor assembly 42 to start moving away from the slicer, thereby depositing the new bale on the remainder of the bale in the framework 40, as shown in fig 7. When the trip block 66 activates the limit switch 70, both the assembly movement and indexing conveyor belt movement are stopped. A new bale is then transferred to the indexing conveyor 42 from the lifting frame 30. As a safety feature, there is a further trip switch 154, 158, 168, 170 adjacent each of the limit switches 54, 58, 68, 70 controlling framework and indexing conveyor movement. Each of the further trip switches will shut down the slicer if activated as a result of either the framework or indexing conveyor overrunning due to failure of a limit switch. The modified embodiment of the bale slicer, shown in figure 8, has a further fixed blade 74 mounted forward of the existing fixed blade 46 and at a level intermediate the planes of the first and second support platforms 44,50. Provision of _g-_ the further blade 74 allows the slicer to separate two slices from the bale on each forward stroke of the receptacle. A further modified embodiment, which separates a slice on each of the forward and return strokes, is shown in figure 9. The first support platform 44 carries an additional fixed blade 76 along its rear edge and the first and second support platforms 44,50 are pivotally mounted through links 82 at opposite ends of levers pivoted at their centres to the framework of the slicer. When a slice has been separated by moving the bale 10 from the first platform 44 to the second platform 50, as previously described, the levers 78 pivot due to the repositioned weight of the bale, lowering the second platform 50 and raising the first. As the receptacle 40 begins its return stroke, the bale 10 engages the additional fixed blade 76 and a slice is separated from the bottom of the bale 10. The lever 78 then pivots back to its original position, raising the second platform 50 above the first, and the separation process begins again. During each slice-separating operation, the levers 80 are preferably locked in position for example by suitable clamping means. In both of the alternative embodiments described with reference to figures 8 and 9, the method and apparatus for loading a further bale 10 is as described above. The fixed blade 46 may be of varying design to cope with different materials. Prongs may be provided in advance of the leading edge of the blade to assist in splitting the bale between strata. As described above, the separated slices are fed to a conditioning unit where they are moisturised and broken up into individual leaf sections. The size of the conditioning cylinder should be dictated by weight throughput requirements _ although the large size of the slices may dictate the use of a Jarger (and more expensive) conditioning cylinder than that otherwise required. To avoid such problems, the bale slicer is provided with a slice breaking device 84 which breaks up the slices into smaller pieces prior to feeding to the conditioning cylinder. The slice breaking device, shown in figures 10 to 12 is preferably positioned to receive slices as they are separated from a bale although it will be appreciated that the device may be positioned at an intermediate point in the conveyor transporting slices from the bale slicer to the conditioning cylinder. The slice breaking device 84 comprises a pair of idle rollers 86 and a central fulcrum wheel 88. The axes of the rollers 86 extend in a vertical plane perpendicular to the direction of movement of the slices and are angled downwards from a central pivotal joint 90, in the form of an inverted V. The central wheel 88 is mounted in a further vertical plane perpendicular to the first and aligned with the centre of the path of the bale slices. The central wheel 88 is mounted with the uppermost part of its ridged periphery less than the thickness of a slice below the lowest part of the cylindrical surface of the rollers 86. In operation, a slice 48 separated by the fixed blade 46 is directed between the central wheel 88 and rollers 86 by a guidewheel 92 mounted on a freely rotating horizontal shaft 94. As shown in figure 12, the slice 48 passing between the wheel 88 and rollers 86 is broken in two. The broken pieces of the slice then fall onto a suitably sized conveyor which transports them to a conditioning cylinder. - l c The central wheel 86, mounted on a horizontal shaft 96 driven by a motor 98 under variable speed control, may be a plain profiled wheel as shown or may be fitted with radial pins or prongs to penetrate a slice to improve transmission thereof through the device and/or to generate a break line in the slice passing therethrough. The rollers 86 are rotatably mounted on a support frame 100 on either side of the support frame central pivotal joint 90. The other ends of the support frame 100 are raised or lowered by screw jacks 102 operated manually by rotation of a handle 104, or by other suitable mechanical, electromechanical, hydraulic or pneumatic means, to alter the angular attitude of the rollers 86 to enhance the breaking action. The slice breaking device 84 is adjustable in the vertical plane to accomodation different thicknesses of separated slices. Although the slice breaking device shown is attached to a bale slicer separating a single slice in one direction of motion only, it will be appreciated that more than one such device may be provided for use with the multiple slice separating apparatus shown in figures 8 and 9. It will also be appreciated that the slice breaking device may be used in other orientations, such as an inverted position with the centre wheel 88 above the rollers 86 which would be mounted in a V configuration. Although described with reference to electric motor drives and control circuitry, it will be appreciated that the invention can alternatively be powered from a hydraulic or pneumatic source. -I! - The bale slicer described above is a robust construction having fewer moving parts, and thus simpler control circuitry, than presently known and used slicers. In addition, it is capable of continuous operation to provide an uninterrupted supply of slices of controlled thickness.

Claims: - * 2- - C L I M S : 1. Apparatus for slicing blocks of compressed stratified material, such as bales of tobacco, having a fixed blade extending in a substantially horizontal plane and means for moving a block having substantially horizontal strata over the blade in engagement with the blade to separate a slice from the bottom of the block by splitting the block between strata. 2. Apparatus according to claim 1 having first and second substantially horizontal platforms on the first of which a block is supported and across which the block is moved into engagement with the fixed blade which defines one edge of the second platform. 3. Apparatus according to claim 1 or claim 2 in which a further fixed blade is provided defining the edge of the first platform which faces in the opposite direction to the first m»sntioned blade, and having means for interchanging the heights of the two platforms such that a block being moved out of engagement with the first fixed blade is moved into engagement with the further fixed blade. 4. Apparatus according to claim 3 in which the two platforms are mounted on a pivoted lever at equal and opposite distances from the pivot axis of the lever. 5. Apparatus according to any preceding claim including a receptacle into which the block is placed, the receptacle being controlled to execute reciprocatory motion thereby moving the block into and out of engagement with the or each fixed blade. 6. Apparatus according to any preceding claim including goading means for placing a further block on top of a first block from which slices have been separated as the first block is moved into engagement with the or one of the fixed blades. 7. Apparatus according to claim 6 in which the loading means comprise a conveyor assembly for carrying the further block, the conveyor assembly being movable to partially overlap the path of the first block and operable to deposit the further block on top of the first block when the first block is in a predetermined position relative to the or one of the fixed blades. 8. Apparatus according to claim 6 or claim 7 including means for detecting the thickness of the first block, and control circuitry to operate the loading means when the thickness of the first block is below a preset value. 9. Apparatus according to claim 8 in which the detecting means is a photosensitive device mounted at a fixed height above the plane of the or one of the fixed blades. 10. Apparatus according to any preceding claim having an additional blade parallel to and vertically spaced from the first and/or further fixed blades so that movement of a block into engagement with the first and/or further fixed blade brings the block also into engagement with the additional blade. 11. Apparatus according to any preceding claim including slice breaking apparatus operable to receive a slice separated from the bottom of a block and to break the said slice into two or more pieces. - I f- 12. Apparatus according to claim 11 wherein the slice creaking apparatus includes first and second rollers the rotational axes of which define an included angle there¬ between, and a wheel spaced apart from the rollers, the periphery of the wheel lying in a plane which substantially bisects the said included angle. 13. Apparatus according to claim 12 including a support frame on which the rollers are mounted, the support frame having at least one pivotal joint allowing alteration of the roller rotational axes included angle.

Inventors: GIRLING ALAN MICHAEL, KIRKMAN DOUGLAS, OWEN ROY ARTHUR, GIRLING, ALAN, MICHAEL, KIRKMAN, DOUGLAS, OWEN, ROY, ARTHUR
Applicants: CARDWELL MACH CO UK, THE CARDWELL MACHINE COMPANY (UK) LIMITED
Application year: 1990
Main classification: A24B3
IPC codes: A24B3, B26D1, B26D3