GB2175836A - Slitting machine - Google Patents

Abstract

A slitting machine for separating carrier-mounted packs of produce which are sealed in film or film and moulded sheet comprises wheel cutters 28 for slitting the film and a guide-way 14 for guiding the carrier 16 during slitting whereby the packs are slit in a direction parallel to the guide-way 14 during relative movement between the cutters 28 and the carrier 16 caused by pushers 10 on chains 6. The slit packs may then pass through a similar slitter 30-38 at right angles to the original feed direction. In an alternative construction, vertically-disposed plates (50, Fig. 3) support a plurality of shafts carrying differently spaced wheel cutters. There may be a turntable (74, Fig. 3) for positioning the carrier. <IMAGE>

Description

SPECIFICATION Slitting machine FIELD OF INVENTION This invention concerns slitting machines for separating packs of vacuum sealed products and a method of processing such packs.

BACKGROUND OF THE INVENTION Although packs of produce can be evacuated and sealed separately, process economies require that whole batches be processed in one cycle of the packing machine. As the trays are flimsy we prefer to load them into a rigid frame which is able to support from perhaps six to thirty six trays during the filling sealing operation. The filled sealed packs can then be conveniently lifted from the packing machine by an operator who checks visually that the sealing operation has proceeded satisfactorily whereafter they are transferred to a slitting machine.

In our co-pending application no: 212197 we describe a magazine which is the rigid lattice with intersecting grooves in one face thereof for use with the slitting machine of this invention. In our co-pending application no: 213316 we describe a process of differential vacuum packaging. The contents of both these specifications are incorporated herein by way of reference.

Although the trays are normally manufactured in single rows for convenience of handling, two, three or even four rows of trays are placed side by side to fill a magazine and a sheet of transparent film is superimposed over the whole array of filled trays. After the imposition of a vacuum the film is heat sealed to the borders of each tray and the whole array is united by the film and the trays must be separated for individual stacking in a carton, in our copening application no: 213316 we describe such a process of vacuum packaging, the contents of which specification are hereby incorporated by way of reference. Some packers have no need of moulded trays. Instead they utilise skin to skin packaging wherein multiple items such as individual leg chops are sandwiched between two layers of film by a process as described in our copending application no: 213316.In that specification use is made of a carrier board upon which the packs remain while the packaging process ensues.

These packs are untied by the sheets of film and must be slit if they are to be separated for shipment in a carton.

Both the magazine and the carrier board have slots in the upper surface thereof to allow cutters to pass through the film without contacting the carrier board or magazine itself.

SUMMARY OF THE INVENTION The method aspect of the invention provides a method of processing vacuum sealed produce portions comprising; (a) performing a vacuum sealing operation upon a plurality of separate portions loaded into a magazine in order to produce a plurality of individually sealed portions united by two sealing plies, (b) subjecting the plies to a slitting operation while still in the magazine in which one or more series of cuts separate the portions into individual packs which are thereafter strippable from the magazine.

The wheel cutters may move through the stationery magazine. Alternatively the cutters may occupy a fixed position and the magazine fed between the cutters and a guideway.

The apparatus aspect of this invention provides a slitting apparatus for separating carrier-mounted packs of produce which are sealed in film sheets or film and moulded sheet packs comprising a guideway for the carrier, two or more wheel cutters spaced from the guideway and arranged to make a corresponding number of mutually parallel cuts through the film or sheet, parallel to the guideway and drive means to produce the necessary feed motion in either the cutter or the carrier to produce the cuts as the packs pass between the cutters and the guideway.

Thus in the simplest form of the machine a first set of wheel cutters is arranged to sever the film or sheet of an array of packs into strips along a first plurality af mutually parallel axes and a second set of wheel cutters is arranged to sever the strips along a second plurality of mutually parallel axes, the first axes being normal to the second axes and each set of wheel cutters is positioned above the guideway. This results in a machine the table of which is L-shape in plan.

Each cutter may be a rotatable disc. Each set of cutters may comprise a shaft with two or more cutters fixed thereto. The drive means may be a first feed mechanism activated by intermittent motion which feeds the trays into the path of the first cutters delivering the trays into the path of a second feed mechanism also actuated by an intermittent motion which feeds the trays at 90 degrees into the path of the second cutters.

In practice the slitting machine must accept trays of different dimensions so that the spacings between the slits in one batch of trays may differ from the next. Accordingly it is advantageous if one or both of the sets of cutters are exchangeable for cutters of different spacing. In order to preserve the settings of the machine the cutter exchangeability is preferably provided by arranging sets of cutters in a turret so that the sets of cutters can be indexed as required.

DESCRIPTION OF THE DRA WINGS Certain embodiments of the invention are now described with reference to the accompanying drawings in which: Figure 1: is a diagrammatic plan of the machine, and Figure 2: is a diagrammatic plan of a part of the machine showing a turret modification, and Figure 3: is an alternative form of the machine shown in perspective.

DESCRIPTION OF SPECIFIC EMBODIMENTS Referring firstly to Fig. 1 the machine has a table 2 which is L-shaped in plan. The infeed area 4 has a pair of slots 6 in the table through which a pair of endless chains 8 project. The chains each carry a magazine pusher 10 which projects above the level of the elevated platform 12 lying between the slots 6.

The upstanding flange 14 acts as a surface against which the magazine 16 can be positioned to ensure that the trays are cut accurately and rollers 18 project slightly through apertures in the flange so as to reduce friction with the flange.

The drive chains feed the magazine 16 to the left of the drawing. The magazine is described in our co-pending application for patent no: 212197 and has slots (not shown) in its upper face in order to allow the film to be slit without simultaneous cutting of the magazine directly beneath the film.

The table has a pair of uprights 20, 22 which support a cutter shaft and electric motor 26. The shaft 24 carries a pair of cutter discs 28 which are spaced adjacent to run in the centre of the slits in the magazine. A single pass through the cutters suffices to divide the trays into three rows of triple units. The end unit of these rows advance until they reach flange 30 which stops the magazine in a feed position on elevated platform 32 ready to be fed at 90 degrees to its previous feed direction by pushers 34 to collection table 36 beneath cutter discs 38 which divide the three rows of trays into nine separate trays. The trays are lifted out of the magazine by an operator and stacked in a cardboard carton for shipment.The motors 26, 40 work in sequence as do the pushers 10, 34, the latter merely rotating intermittently and then passing beneath the table to return to their starting positions all of which movements are synchronised by known circuitry.

Referring now to Fig. 2 the machine has a flat table 12 with a pair of plates 44 which support a turret 46. The plates each have slots for height adjustment above the table 12. The turret is mounted on control shaft 48. A pair of indexing plates 50 revolve on the plates until one or other indexing bores register with a spring loaded pin 52. The indexing plates each have a pair of bearings 54 which support drivable shaft 56. The shaft has a pair of cutting discs 28 each equipped with a lockable boss 58 such that the distance between the discs can be adjusted. The operating end of the shaft carries a pinion 60 which can by rotation of the indexing plate, be moved in and out of engagement with a fixed axes pinion 62 rotated by motor 64.A like shaft 66 has a pair of cutters 38 much closer together than the alternative pair and these are then driven by overhung pinion 68 from the same motor pinion 62.

Referring now to Fig. 3, the turret 46 is centrally mounted above the table 12 and has three cutter wheel shafts. A pair of parallel slots 70 house a pair of drive chains protruding through the slots and forward magazine pusher 72 extends from each chain for engaging the magazines trailing edge. A similar pusher (not shown) provides return motion. A turntable 74 rotates the magazine through 90 degrees and guides 76 move towards an away from each other synchronously with the rotation of the turntable. Thus the magazine is moved beneath the cutters in one direction, the turret 46 is indexed while the turntable rotates through 90 degrees. The magazine direction is reversed in order to receive a second pair of cuts.

This machine is of particular application in the food industry for sealing fruit, meat, nuts, yoghurt, cheese and the like. We have found the advantages of the Fig. 1 embodiment to be A. Reliable and precise cutting leading to packs of uniform area and regular shape B. Clean cut edges of good appearance.

We have found the advantages of the Fig. 2 embodiment to be C. The distance between the cutters once set, may be left undisturbed.

D. One machine can cope with several different pack sizes thereby avoiding the need to ground batches of packs into economic runs of uniform size.

Claims (16)

1. A slitting machine for separating carriermounted packs of produce which are sealed in film or film and moulded sheet comprising a guide way for the carrier, two or more wheel cutters spaced from the guideway and arranged to make a corresponding number of mutually parallel cuts through the film or sheet in a direction parallel to the guideway and drive means to produce the necessary feed motion in either the cutters or carrier to produce the cuts as the packs lie between the cutters and the guideway.

2. A slitting machine as claimed in claim 1 wherein a first set of wheel cutters as arranged to sever the film or sheet of an array of packs into strips along a first plurality of mutually parallel axes, a second set of wheel cutters is arranged to sever the strips along a second plurality of mutually parallel axes, the first axes being normal to the second axes and each set of wheel cutters is positioned above the guideway.

3. A slitting machine as claimed in claim 1 of 2 wherein two or more wheel cutters form part of a slitter assembly comprising an indexable turret with two or more cutter shafts, each shaft having cutters separated by a different distance.

4. A slitting machine as claimed in claim 3 wherein the turret comprises a pair of turret mounts which are rotatable about a turret axes, a first and second shafts carried by the turret mounts, two or more wheel cutters mounted on the first shaft each spaced from the other by a first pack width, two or more wheel cutters mounted on the second shaft each spaced from the other by a second pack width which is different from the first, a wheel cutter drive, each shaft being indexable to a cutting position where the drive is engaged to rotate the wheel cutters.

5. A slitting machine as claimed in claim 4 wherein the guideway has an infeed area on one side of the turret and a means for rotating the carrier and packs through 90" in order to prepare the carrier and packs for a return pass through the cutters.

6. A slitting machine as claimed in any one of the preceding claims wherein the or each guideway has a conveyor drive which propels the carrier along the guideway through the cutters.

7. A slitting machine as claimed in anyone of the preceding claims wherein the cutter wheel comprises a thin metal disc with a ground cutting edge and a boss with a set screw for adjusting the position of the cutter on the cutter shaft.

8. A slitting apparatus for separating packs of film sealed produce comprising a first set of wheel cutters arranged to sever the packaging film of an array of packs along the first plurality of mutually parallel axes, a second set of wheel cutters arranged to sever the packaging film of the array of packs along a second plurality of mutually parallel axes, the first axes being normal to the second axes, drive means arranged to convey the packs in the path of the first set of wheel cutters and then in the path of the second set of wheel cutters in order to subject the packs to intersecting cuts.

9. A slitting machine as claimed in anyone of claims 4 to 8 wherein the turret shafts each have an overhung pinion which meshes with a static, motor driven gear when the shaft is in the cutting position.

10. A slitting machine substantially as herein described with reference to Figs. 1 and 2 or as modified by Fig. 3.

11. A method of processing vacuum sealed produce portions comprising; (a) performing a vacuum sealing operation upon a plurality of separate portions loaded into a magazine in order to produce a plurality of individually sealed portions united by two sealing plies, (b) subjecting the plies of a slitting operation while still in the magazine in which one or more series of cuts separate the portions into individual packs which are thereafter strippable from the magazine.

12. A method as claimed in claim 11 wherein wheel cutters advance through the magazine and the stationary plies thereon.

13. A method as claimed in claim 11 wherein the cutters revolve but remain static while the magazine and plies thereon progress through the cutters.

14. A method as claimed in claim 13 wherein the magazine and plies are advanced along a guideway which aligns grooves in the upper face of the magazine with the cutters and the cutters are spaced from the guideway such that the cutters slit the plies without contacting the magazine.

15. A method as claimed in claim 14 wherein the magazine receives a series of cuts in one direction, the magazines direction is changed then the magazine receives a second series of intersecting cuts.

16. A method of processing vacuum sealed produce substantially as herein described.