PACKAGING LINE

Abstract: A packaging line for packaging sliced foodstuffs such as meat, meat products and cheese which are cut from logs of product by a slicing machine (1) comprises a first conveyor (11) to convey slices sliced by a slicing machine towards a packaging machine, sensor means (17, 18) arranged transversely equidistant from the centre line of the first conveyor (11) to detect the edges of the slices on the first conveyor and output a signal representative of the transverse location of the slices on the first conveyor, and a multi-element strip conveyor (14) downstream of the first conveyor (11) and arranged to receive the slices from the first conveyor. The second conveyor includes a transversely movable roller (16) at its upstream or downstream end, and means responsive to the output of the sensor means (17, 18) to move the transversely movable roller of the second conveyor a distance to centralise the slices on the packaging line. The sensor means (17, 18) or another sensor means (21, 22) is arranged to detect any angular displacement of slices on the packaging line. Means responsive to the output of the sensor means (17, 18, 21, 22) drives the different elements of the multi-element conveyor (14) or another multi-element conveyor (23) at different speeds to correct any angular misalignment of the slices.

Description: Packaging Line This invention relates to packaging lines for packaging sliced foodstuffs such as meat, meat products and cheese which are cut from logs of product by a slicing machine. The slices are often marshalled into groups by a jump conveyor immediately downstream of the slicing machine and then the weight of the groups of slices is checked by a check weigher to ensure that they are of the correct weight. At the downstream end of the packaging line the groups of slices are usually packaged by a vacuum packaging machine. Our earlier Patent specifications EP-A-0274229 and WO 89/10318 describe such packaging lines for sliced foodstuffs. Particularly when the packaging line is slicing a natural product such as meat or bacon the dimensions of the product vary from one log to the next. Frequently the logs are aligned with a kerb so that one end of the slices are usually located in a particular transverse location on the packaging line, but the spread of the product across the pack varies from one log to the next. This leads to the groups of slices not being centrally located in the final packages produced by the vacuum packaging machine and can lead to the appearance of some packs appearing to be only partly full and the packs possibly not being correctly sealed. Other problems that occur are an angular displacement of the product by an upstream check weigher or initial misalignment of the slices during their fall from having been cut from the log by the slicing machine onto the jump conveyor. Any angular displacement of the slices leads to the slices being misaligned in a final package which is unappealing to the consumer as well as, if the misalignment is extreme, preventing the formation of an adequate seal around the edges of the package in the vacuum packaging machine. According to this invention a packaging line for sliced foodstuffs comprises a first conveyor to convey slices sliced by a slicing machine towards a packaging machine, sensor means arranged transversely equidistant from the centre line of the first conveyor to detect the edges of the slices on the first conveyor and output a signal representative of the transverse location of the slices on the first conveyor, a multi-element strip conveyor downstream of the first conveyor and arranged to receive the slices from the first conveyor, the multi-element conveyor including a transversely movable roller at its upstream or downstream end, means responsive to the output of the sensor means to move the transversely movable roller of the multi-element conveyor a distance to centralise the slices on the packaging line, the sensor means or another sensor means being arranged to detect any angular displacement of slices on the packaging line, and means responsive to the output of the sensor means to drive different elements of the or another multi-element conveyor at different speeds to correct any detected angular misalignment of the slices. When the slices of product are not located centrally on the first conveyor so that the transversely movable roller of the multi-element strip conveyor is moved transversely to correct for this, an angular misalignment of the slices occurs with the extent of the misalignment being dependent on the extent of transverse movement of the transversely movable roller. Accordingly the angular misalignment resulting from centralising the slices of product can be predicted and a correction made automatically for the misalignment that will be induced by the centralising operation. Accordingly it is possible for the sensor means on the first conveyor to detect both the off centreness of the product and any misalignment and for the multi-element strip conveyor to correct for both of these as well as taking account of any angular misalignment it will itself induce. Preferably however the packaging line includes two bank of sensors arranged over the first conveyor, a first multi-element strip conveyor downstream of the first conveyor, a pair of sensors to detect any angular misalignment of products after they have been conveyed by the first multi-element conveyor, and a second multi-element conveyor downstream of the pair of sensors to correct any angular misalignment of the products. In the field of paper handling it is know to arranged to deposit standard size regular sheets of paper into their correct position in a stack by moving the individual sheets with a conveyor which has a transverse component of movement and the downstream end of which is transversely movable. One edge of the sheet is moved into an edge detector and as soon as this one edge is in its correct location the transverse location of the downstream end of the conveyor is controlled to keep the one edge in its correct position. Such a system is described in DD-A-126585. It is also know from GB-A-2186252 optionally to convey bundles of paper sheets along a pair of belt conveyors so that their orientation remains the same throughout, or, by speeding up one belt, so that their orientation is changed by 90°. Preferably the first conveyor is formed in two parts with the downstream part hinged so that the downstream end of the first conveyor can be moved upwards or downwards to reject slices from its downstream end. The slices may be rejected from the downstream end of the first conveyor when the output of the sensors shows that they are so far off the central position that their position cannot be corrected by the transverse movement of the transversely movable roller of the second conveyor, when they are so much out of angular alignment that this cannot be corrected, when as a result of an off weight signal from an upstream check-weigher the slices should be rejected or, for example, when a butt end detector located on the slicing machine such as is described in detail in European Patent Application 90305138.1 indicates that the slices are commercially unacceptable. When the packing line is arranged to be able to reject slices not of the correct weight or orientation the resulting packaging line is particularly advantageous since it can be guaranteed that all slices passing along the line are either rejected or placed in the correct orientation and position and are commercially acceptable having, for example the correct weight. In this way it can be ensured that all products fed to the vacuum packaging machine are of the correct merchantable presentation. Preferably the transversely movable roller on the multi-element conveyor is not the driven roller of the second conveyor. It is further preferred that the transversely movable roller is the upstream roller of the multi-element conveyor. The or the other multi-element conveyor preferably includes three elements with the centre element being driven at the packaging line speed and the outer two elements being driven at different speeds to correct any detected misalignments in the slices. The or the other multi-element conveyor may be driven from a single drive via, for example, a differential gearbox with means being provided to drive the "cage" of a differential gearbox so as to get a speed difference between the outer two elements of the multi-element conveyor. Alternatively the elements of the or the other multi-element conveyor may each have an individual drive which, may, for example, include a stepper motor. More than three elements may be included in the multi-element conveyor and, in this case, it is preferred that each element includes its own individual drive. A particular example of a packaging line in accordance with this invention will now be briefly described with reference to the accompanying drawings, in which:- Figure 1 is a side elevation of the upstream end of a packaging line; Figure 2 is a plan of the upstream end of the packaging line; Figure 3 is a diagrammatic side elevation of the centraliser; Figure 4 is a diagram showing products in various different transverse locations and showing how these are corrected; and. Figure 5 is a plan of the angular aligner, with diagrams illustrating the range of correction which is possible. The example in accordance with this invention includes a slicing machine 1 such as that known by the trade name of "Polyslicer" and manufactured by the applicants which slices a block of product, a jump conveyor 2 which groups a number of consecutive slices together, a check weigher 3 which weighs each group, a centraliser 4, an angular aligner 5, and a reject conveyor 6. The angular aligner 5 leads to a further conveyor 7 which leads to the remainder of the packaging line to synchronizers (not shown) to arrange groups of slices in the correct format for a downstream vacuum packaging machine, also not shown. The centraliser 4 portion comprises a first conveyor 11 formed in two parts 12 and 13, and a second conveyor 14. The downstream part 13 of the first conveyor 11 is hinged so that its downstream end 15 is movable upwards and downwards to align it with the downstream conveyor 14 or with the reject conveyor 6 which receives rejected products. When the check weigher 3 indicates that a product group is not the correct weight the downstream end 15 of the first conveyor 11 is lowered to reject that group of slices. The idle rollers 16 forming the upstream end of the second conveyor 14 are mounted for movement in a transverse direction. This conveyor may be formed in a similar fashion to that described in our earlier EP-A-0274229. Two banks of detectors 17 and 18 extend transversely across the upstream end of the first conveyor 11 as shown most clearly in Figure 4. The detectors in each bank are typically co-sited photoe itters and photodetectors with a retro-reflector mounted beneath the conveyor 12. The presence of a product on the conveyor 12 blocks the light beam from the photoemitter to photodetector to provide a change in output of the detectors which indicates the presence of a product at that location. By comparing the numbers of sensors obscured in each bank 17 and 18 any off-centreness of the products on the first conveyor 1 is detected. AS shown in the diagram on the right hand side of Figure 4 when a product is correctly centred on the conveyor 11 the same number of sensors in the banks 17 and 18 are obscured. (Obscured sensors are shown by black circles in Figure 4) . When the product is correctly centred the input roller 16 of the second conveyor 14 is aligned with the output roller so that no change is made to the location of the product on the packaging line. When the product is displaced to the left as considered in its direction of conveyance as shown in the second diagram from the right in Figure 4 three sensors of the left hand bank 18 are obscured whilst only one sensor of the right hand bank 17 is obscured. Thus, by monitoring the difference between the numbers of sensors obscured it can be seen that the group of slices needs to be moved one sensor pitch to the right. Thus, the input roller 16 of the second conveyor 14 is moved one sensor pitch to the left so that when this group of slices moves onto the second conveyor 14 it is then located centrally on the second conveyor 14. The third diagram from the right in Figure 4 illustrates a longer product than the previous two examples which is offset to the right with respect to its direction of conveyance. Thus, three sensors of the right hand bank 17 are obscured whilst two sensors of the left hand bank of sensors 18 are obscured. Thus, the product should be shifted by half the pitch of the sensors to the left. To do this the transverse roller 16 of the second conveyor 14 is shifted by half a pitch of the sensors to the right before that group of products are transferred from the first conveyor 11 to the second conveyor 14. Finally, considering the arrangement shown in the left hand diagram of Figure 4 the group of slices is severely displaced to the right with respect to its conveying direction. Thus, the group of slices covers all of the sensors in the bank 17 and covers none of the sensors in the bank 18. Thus, the exact position of the group of slices cannot be determined and, in any event, would be too far to the right to be corrected by the second conveyor 14. Accordingly, the downstream end 15 of the second part 13 of the first conveyor 11 is lowered to reject this group of slices. The packing line also includes an angular aligner portion shown in Figure 5 and located downstream of the centralising portion. In Figure 5 a group of slices 20 is moving to the left down the packaging line. Any misalignment of the group of slices 20 is detected by a pair of detectors 21 and 22. A downstream conveyor 23 is formed by three flat belts 24, 25 and 26. The centre belt 25 has its speed matched to that of the packaging line whilst the speed of the belts 24 and 26 are adjustable in equal and opposite directions with respect to the speed of the packaging line as illustrated by the diagram to the left of the conveyor 23. Assuming that the central belt 25 runs at a fixed speed of 55 metres per minute then the outer belts 24 and 26 can be varied in speed between 50 and 60 metres per minute and so go slower or faster than the central belt 25. upon the detectors 21 and 22 detecting an angular misalignment of a group of slices 20 the speed of the belts 24 and 26 is set in accordance with the extent of the angular misalignment so that, taking the situation as shown in Figure 5 the belt 26 moves slower than the belt 25 and the belt 24 moves faster than the belt 25. The difference in velocity between the belts 24 and 26 is such that their upper surfaces travel a difference in distance equal to the extent of angular misalignment 27 detected by the detectors 21 and 22 whilst the group of slices 10 is conveyed along the conveyor 23. This is illustrated by the diagram at the bottom of Figure 5 which illustrates the range of correction available. The operation of the reject device to lower the end 15 of the conveyor 13, the movement of the roller 16 of the conveyor 14 and the speed control of the belts 24 and 26 are all controlled by a programmed computer (not shown) in response to inputs from the check weigher 3 or the upstream slicing machine 1 and from the sensors 17, 18, 21 and 22.

Claims: CLAIMS 1 A packaging line for sliced foodstuffs comprises a first conveyor (11) to convey slices sliced by a slicing machine (1) towards a packaging machine, sensor means (17,18) arranged transversely equidistant from the centre line of the first conveyor (11) to detect the edges of the slices on the first conveyor (11) and output a signal representative of the transverse location of the slices on the first conveyor (11) , a multi-element strip conveyor (14) downstream of the first conveyor (11) and arranged to receive the slices from the first conveyor (11) , the multi-element conveyor (14) including a transversely movable roller (16) at its upstream or downstream end, means responsive to the output of the sensor means (17,18) to move the transversely movable roller (16) of the multi-element conveyor a distance to centralise the slices on the packaging line, the sensor means (17,18) or another sensor means (21,22) being arranged to detect any angular displacement (27) of slices on the packaging line, and means responsive to the output of the sensor means (17,18,21,22) to drive different elements (24,25,26) of the or another multi-element conveyor (14,23) at different speeds to correct any detected angular misalignment (27) of the slices. 2. A packaging line according to claim 1, in which the first conveyor (11) is formed in two parts (12,13) with the downstream part (13) hinged so that the downstream end (15) of the first conveyor (11) can be moved upwards or downwards to reject slices from its downstream end. 3. A packaging line according to claim 1 or 2, in which the transversely movable roller (16) on the second conveyor (14) is not a driven roller. 4. A packaging line according to any one of the preceding claims, in which the transversely movable roller (16) is the upstream roller of the second conveyor (14). 5. A packaging line according to claim 5 or 6, in which the or the other multi-element conveyor (14,23) includes three elements (24,25,26) with the centre element (25) being driven at the packaging line speed and the outer two elements (24,26) being driven at different speeds to correct any detected misalignments in the slices. 6. A packaging line according to claim 7, in which the or the other multi-element conveyor (14,23) driven from a single drive via a differential gearbox with means being provided to drive the cage of a differential gearbox so as to get a speed difference between the outer two elements (24,26) of the multi-element conveyor (23) .

Inventors: HOYLAND TREVOR BARRIE, HOYLAND, TREVOR, BARRIE
Applicants: THURNE ENG CO LTD, THURNE ENGINEERING COMPANY LIMITED
Application year: 1990
Main classification: B65G47
IPC codes: B65G21, B65G43, B65G47