GB2280885A - Applying tension to sheets of wrapping - Google Patents

Description

2280885 1 A device for feeding sheets of wrapping material, in a user

machine

The present invention relates to a device for feeding sheets of wrapping material in a user machine. Reference is made throughout the specification, albeit with no limitation implied, to a device for feeding discrete lengths of foil backed paper in a machine for packaging products, each single product consisting in a group of cigarettes. Conventional cigarette packets, whether the crush type or the rigid type with a hinged lid, comprise not only an outer label or box, respectively, but also an inner wrapping in direct contact with the cigarettes which generally is fashioned from tissue paper backed with silver foil. It is the standard practice in cigarette packaging machines to arrange the cigarettes in groups and then to advance the groups singly and in succession to a revolving infeed unit or feed head, generally embodied with at least two slots each designed to receive a relative group of cigarettes. Once seated

2 is in one of the slots, the single group of cigarettes is transferred, by a rotation of the revolving head about its own axis, into a folding station to which single sheets of the foil backed paper are supplied in ordered succession. The wrapping material is supplied to the folding station by means of a feeder unit comprising pinch rollers such as will advance cut sheets of the foil backed paper singly and in succession through a substantially vertical plane to a standby position, coinciding with the folding station, in which the single sheet effectively bridges one of a plurality of a radial pockets afforded by a wrapping wheel. The sheet comes to rest in the standby position as the free leading end locates against a reference surface, whilst the opposite end continues to be restrained between the pinch rollers. Once rotated into the folding station, the group of cigarettes is ejected from the relative slot of the infeed unit in such a way as to impinge on a respective sheet of the foil backed paper and advance together with the sheet into a pocket of the wrapping wheel. In the course of this transfer operation, the sheet of foil backed paper is caused to wrap around the relative group of cigarettes in a "U" formation.

0 It has been observed in practice that the device thus outlined, and particularly the means by which the sheets are held in the folding position, will neither allow a faultless alignment of the sheets in relation to the respective products nor ensure a precise folding operation, and especially at high operating speeds. Consequently, one has the formation of defective wrappings which do not adhere uniformly to their respective contents. The object of the present invention is to overcone the drawbacks mentioned above in connection with the prior art. The stated object is realized in a device according to the present invention for feeding sheets of wrapping material in a user machine, comprising a feeder unit by which the sheets are advanced along a first predetermined path to a standby position in which the single sheet is positioned substantially bridging the entry passage to a wrapping unit, infeed means by which products are advanced along a second predetermined path extending transversely to the first path, through the standby position and the entry passage to the wrapping unit and in such a manner that the sheet is made to fold around the

4 product in a U formation, also means constituting a part of the feeder unit and serving to restrain the single sheets when occupying the standby position, characterized in that it comprises means by which to tension the sheets, operating in conjunction with the restraint means. The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which: -fig 1 shows a preferred embodiment of the device for feeding sheets of wrapping material according to the present invention, illustrated schematically in a part- sectional side elevation; -fig 2 shows an enlarged detail of the device in fig 1, illustrated schematically and partly in section; -fig 3 shows a possible embodiment of the detail of fig 2, illustrated schematically in the view from letter V in fig 1; -fig 4 is a schematic side elevation illustrating further details of the device as in fig 1. With reference to the accompanying drawings, and in particular fig 1, the present invention relates to a device, denoted 21 in its entirety, for feeding sheets 5 of wrapping material such as foil backed 1 is tissue paper to a user machine 20, and typically a packaging machine designed to envelop products 3 consisting in groups of cigarettes. The device 21 in question is installed between a revolving infeed unit 1, by which the single groups of cigarettes 3 are recieved in succession from a conveyor of conventional embodiment not illustrated in the drawings, and a wrapping unit 7 to which the groups 3 are transferred in succession by way of a folding station 6. At this same folding station 6, each sheet 5 of foil backed paper is forced to bend into a I1Ull formation (fig 4) around the relative group 3 as the group is transferred from the infeed unit 1 to the wrapping unit 7. The device 21 comprises a feeder unit, denoted 4 in its entirety, by which the sheets 5 are advanced into the folding station 6. More particularly, the feeder unit 4 is able to produce the sheets 5 from a continuous strip of material wound onto a roll (not illustrated), and to this end comprises a pair of pinch belts 19 by which the continuous strip is drawn forward, cutting means 18 of conventional embodiment by which the continuous strip is divided into discrete lengths, or sheets 5, and means 9 by which both to advance and to restrain the sheets.

6 Such means 9 consist in a pair of pinch rollers 17 by which the cut sheets 5 are advanced toward the folding station 6 through a predetermined distance, and ultimately to a standby position in which the sheet 5 comes to rest with the free leading edge Sa locating against a reference surface 24. In this situation, the selfsame pinch rollers 17 function as means by which to restrain the sheet 5. The infeed unit 1 comprises a revolving head la mounted in rotation to a fixed shaft 25 supporting a cylindrical sleeve 26, which is connected to a conventional drive device (not illustrated) and capable thus of indexing through angular steps of 1800 about the shaft 25 in the direction of the arrow denoted F1 in fig 1. The sleeve exhibits two appendages 27 extending radially in diametrically opposite directions, each of which carrying a pair of plates 28 disposed substantially parallel one with another and affording a slot 2 to receive a relative group 3. With each step indexed by the sleeve 26, as discernible in fig 1, the slots 2 are brought to rest one in a receiving position 22 and the other in an ejecting position 23, the latter coinciding with the folding station 6. Also carried by the sleeve 26 on opposite sides of each slot 2, 1 7 in a conventional manner not illustrated in the drawings, are two moving arms 29 of a gripper 30, each fitted with a respective transversely disposed tooth 31, of which the function is to retain the groups 3 radially in position during the indexing movement of the infeed unit 1. The wrapping unit 7 consists in a wrapping wheel 7a rotatable about its own axis in the direction of the arrow denoted F2, which affords a plurality of radial pockets 8 and is associated with a coaxially disposed cylindrical case 33, positioned externally of the periphery and extending beyond the folding station 6 in the direction of rotation F2. The folding station 6 consists substantially in a radial entry passage 32 created between one end 33a of the case 33 and a block 34 positioned above this same end which, as will become clear in due course, will also serve to favour the entry of the sheet S. The passage 32 is associated with means by which to advance the groups of cigarettes, comprising a push rod 37 by which each group 3 positioned in turn at the folding station is engaged and ejected radially from the relative slot 2 and directed thus into a corresponding radial socket 8, with the assistance of a radial reaction element 38 afforded by the 7 8 wrapping wheel 7a. During this same transfer step, the group 3 is directed along a feed axis denoted A common to the slots 2 and the pockets 8. With reference to fig 1, a sheet 5 directed by the pinch rollers 17 toward the folding station 6 will advance along a path P substantially perpendicular to the feed axis A, coming to rest in a position substantially symmetrical in relation to this same axis A, in which the top end is restrained between the rollers 17 and the leading edge Sa disposed in contact with the reference surface 24. Importantly, it will be observed that the sheet 5 is constrained during its progress along the feed path P to maintain a straight course, through the agency of two guide elements 39 (fig 4) positioned facing the block 34 and the end 33a of the case 33, respectively. The device 21 disclosed comprises means 10 by which to tension the sheet 5, disposed on the same side as the leading edge 5a of the sheet 5 in relation to the folding station 6, and therefore to the feed axis A followed by the groups 3, and in such a way as to interact with the face 5f contiguous to the leading edge 5a. Such tension means 10 are dynamic in operation, being designed to generate a tensile 9 is force continuously on the sheet 5 as indicated by the arrow denoted F in fig 2. The tension means 10 in question comprise at least one roller 11 which, as will become evident, is disposed tangential to the face 5f of the sheet 5 and able to generate sliding friction with a high coefficient against the relative wrapping material, at least along the line of tangential contact, thus producing the tensile force F. The roller 11 is composed of a fixed central hub 13 and an outer ring 14 rotatably ensheathing the hub. More exactly, the ring 14 is breasted in airtight association with the hub 13 and affords a plurality of through holes 15 distributed uniformly over the entire outer surface 14a tangential to the face 5f of the sheet 5. The hub 13 incorporates a suction chamber 16, positioned in alignment with the point of tangential contact between the ring 14 and the sheet 5, such that with the ring 14 set in rotation by drive means not illustrated in the drawings, the holes 15 passing in succession through the point of tangential contact are connected with suction. The suction chamber 16 and the holes 15 combine to create means, denoted 12 in fig 2, such as will generate the aforementioned sliding friction with is the sheet 5 in continuous fashion. Accordingly, the sheet 5 remains correctly tensioned not only when positioned in readiness to be invested by a group 3 advancing along the feed axis A, but also in the initial stages of the folding operation. As discernible in fig 3, the rollers 11 might be two in number, positioned respectively along the side edges of the sheet S. The operation of the device will now be described, commencing from a position marginally preceding that illustrated in fig 1, that is, the position in which a group of cigarettes 3 is directed into the vacant slot 2. From this position, the revolving infeed unit 1 rotates 1800 to transfer the group 3 to the folding station 6. At the same time, the rollers 17 proceed to advance a sheet 5 into the folding station 6. In the course of this advancing movement, the leading edge 5a of the sheet 5 draws alongside the rotating roller 11 and is "captured" by the latter dynamically as the revolving outer ring 14 enters into contact with the material, whereupon, with suction established through the holes 15, sliding friction is generated at the point of tangential contact; the resulting force includes not only a radial component directed is toward the hub 13, but also a tangential tensioning component generated along the path P followed by the sheet 5. The push rod 37 moves forward, advancing the group of cigarettes 3 toward the wheel 7a, in such a way that the sheet 5 is invested by the group 3 and driven together with the latter into the waiting pocket 8. During this same movement, the sheet 5 is made to wrap tightly around the advancing group 3, being forcibly restrained by the now stationary pinch rollers 17 on the one hand and by the force F generated with the suction roller 11 on the other. Thereafter, the push rod 37 returns to a retracted position and the wrapping wheel 7a is indexed one step, thus bringing a new pocket 8 into a position of readiness alongside the folding station 6 and in alignment with the slot 2. The infeed unit la now rotates one half revolution, and a new sheet 5 is directed forward to the point of being attracted by the suction roller 11 and tensioned. As will be evident from the foregoing description, one of the main advantages afforded by the device disclosed when compared with prior art solutions is that it affords a means, namely the roller 11, by

12 which the sheet 5 is not only restrained, but also tensioned continuously and positioned correctly in relation to the folding station 6 and to the group of cigarettes 3. Likewise to advantage, the sheet 5 of foil backed wrapping paper is tensioned by forces directed along the plane effectively occupied by the paper itself, of which the intensity ensures a smooth release when the sheet is invested by the group of cigarettes. Thus, the finished wrappers remain faultlessly tight around the respective products even at the high operating speeds typical of wrapping machines.

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Claims (1)

1. Claims

   1) A device for feeding sheets of wrapping material in a user machine, comprising a feeder unit by which the sheets are advanced along a first predetermined path toward a standby position in which the single sheet is positioned substantially bridging the entry passage to a wrapping unit, infeed means by which products are advanced singly along a second predetermined path extending transversely to the first path, through the standby position and the entry passage to the wrapping unit and in such a manner that the sheet is made to fold around the product in a U formation, also means constituting a part of the feeder unit and serving to restrain the single sheets when occupying the standby position, characterized in that it comprises means by which to tension the sheets, operating in conjunction with the restraint means.

   1 14 2) 3) 4) 5) A device as in claim 1, wherein the tension means are dynamic in operation, capable of subjecting the sheet continuously to a tensioning force composed of at least one component acting in the direction followed by the sheet along the first predetermined path.

   A device as in claim 2, wherein the tension means comprise means able to generate a sliding friction against the sheet.

   A device as in claim 2 or claim 3, wherein the tension means comprise at least one roller capable of generating suction and rotatable about an axis disposed transversely to the first predetermined path.

   A device as in claim 4, wherein the roller consists in a fixed central hub and an outer ring rotatably encircling and in fluid-tight association with the hub, of which the outer ring affords a plurality of through holes distributed uniformly over the entire outer surface rotating tangential to the sheet and communicating with a suction chamber afforded by the hub in a position of alignment with the point is of tangential association between the ring and the sheet, such that the chamber and the holes together constitute means of generating friction.

   6) 7) A device as in claim 4 or 5, wherein the tension means comprise two rollers positioned to interact with the side edges of the sheet.

   A device for feeding sheets of wrapping material, in a user machine, substantially as described with reference to the accompanying drawings.