Method and unit for feeding products to a group-forming unit

A method and unit for feeding products to a group-forming unit for forming groups of products, each containing a given number of products; an orderly succession of products is fed in a first direction by means of a first conveyor; an orderly succession of products is fed in a second direction, parallel to the first direction, by means of a second conveyor parallel to the first conveyor; and the products are transferred from the first conveyor to the second conveyor by means of a transfer device which is permanently integral with an output end of the first conveyor, is moved in the second direction upon detection of a gap along the first conveyor, and is moved in the opposite direction to the second direction to form, along the second conveyor, a number of consecutive gaps equal to the number of products in each group of products.

The present invention relates to a method and unit for feeding products to a group-forming unit.

The present invention may be used to advantage for feeding packets of cigarettes from a cellophaning machine to a cartoning machine, to which the following description refers purely by way of example.

BACKGROUND OF THE INVENTION

Packets of cigarettes are normally fed from a cellophaning machine to a cartoning machine using a single pocket feed conveyor, which feeds the packets directly from the cellophaning machine to the cartoning machine in a single orderly succession, and constitutes both an output conveyor of the cellophaning machine and an input conveyor of the cartoning machine. This solution, on the one hand, has the obvious advantage of maintaining the timing of the two machines and, on the other, has the obvious drawback of allowing no compensation for any gaps, i.e. empty pockets, along the feed conveyor, and so preventing the formation of incomplete groups on the cartoning machine.

To compensate for gaps, it has been proposed to keep the output conveyor of the cellophaning machine and the input conveyor of the cartoning machine separate, and to interpose an interoperational (preferably FIFO) store between the two. The store is fed by the output conveyor of the cellophaning machine with a first orderly succession of packets of cigarettes in time with the cellophaning machine; the packets are brought together inside the store to form queues, are withdrawn from the queues in the store by the input conveyor of the cartoning machine, and are again arranged into a second succession in time with the cartoning machine. Any gaps along the output conveyor of the cellophaning machine are thus compensated for, but the two machines no longer operate in time with each other. Moreover, at relatively high production speeds, withdrawal of the packets from the queues in the store is not easy, and may result in damage to the packets.

Patent Application EP1721844A1 proposes a unit for feeding packets of cigarettes from a cellophaning machine to a cartoning machine. A first output pocket conveyor of the cellophaning machine and a second input pocket conveyor of the cartoning machine move continuously in respective opposite first and second directions, and are connected by a pocket transfer wheel interposed between the first and second conveyor. The pocket transfer conveyor rotates about an axis of rotation crosswise to the first and second conveyor; or translates, together with the second conveyor, crosswise to the axis of rotation to compensate one or more gaps on the first conveyor; or translates, together with the first conveyor, crosswise to the axis of rotation to form a succession of gaps, in time with the cartoning machine, on the second conveyor.

The feed unit described in Patent Application EP1721844A1, however, has several drawbacks, by failing to allow for optimum location of the heat-shrink devices necessary to obtain high-quality plastic overwrappings of the packets, and by failing to effectively handle sharp deceleration (or stoppage) of the cartoning machine, on account of the greater inertia of the cellophaning machine, which prevents the cellophaning machine from decelerating or stopping as fast as the cartoning machine. As a result, in the event of sharp deceleration (o stoppage) of the cartoning machine, a number of packets are invariably fed onto the output conveyor of the cellophaning machine, and, not being feedable to the cartoning machine, must be rejected.

Patent Application EP2007114457 proposes a unit for feeding packets of cigarettes to a cartoning machine which forms groups of packets. An orderly succession of packets is fed in a first direction by a first conveyor; the packets are transferred from the first conveyor to a second conveyor by a first transfer device, and an orderly succession of packets is fed in a second direction by the second conveyor; the packets are transferred from the second conveyor to a third conveyor by a second transfer device, and an orderly succession of packets is fed by the third conveyor in a third direction parallel to the second direction. When a gap is detected along the first transfer device, the second conveyor is stopped and, simultaneously, the second transfer device is moved in the second direction towards the first transfer device.

The feed unit described in Patent Application EP2007114457, however, has several drawbacks: it is fairly complicated mechanically, does not allow easy access to all the areas through which the packets travel, and is not always successful in handling sharp deceleration (or stoppage) of the cartoning machine.

Patent Application DE2618905A1 describes a unit for transferring single cigarettes between two conveyors, and for compensating for any difference in speed between the conveyors. A first output pocket conveyor and a second input pocket conveyor move continuously in respective parallel opposite first and second directions, and are connected by a pocket transfer drum interposed between the first and second conveyor and rotating about an axis of rotation crosswise to the first and second conveyor to transfer cigarettes between the two conveyors. In the event of a difference in speed between the two conveyors, the transfer drum translates in the first or second direction, together with one of the two conveyors.

Patent Application DE1124584A1 describes a unit for transferring products between two belt conveyors moving at different speeds, and for compensating for the difference in speed between the two conveyors. A first belt conveyor and a second belt conveyor move continuously in respective parallel opposite first and second directions, and are connected by a third belt conveyor interposed between the first and second conveyor, and which translates back and forth in the first direction or second direction.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method and unit for feeding products to a group-forming unit, which method and unit are designed to eliminate the above drawbacks, while at the same time being cheap and easy to implement.

According to the present invention, there are provided a method and unit for feeding products to a group-forming unit, as claimed in the attached Claims.

DETAILED DESCRIPTION OF THE INVENTION

Number1inFIG. 1indicates as a whole a feed unit for feeding packets2of cigarettes from a cellophaning machine to a cartoning machine comprising a group-forming unit for forming groups of packets2of cigarettes, each comprising a given number of (normally ten) packets2of cigarettes.

Each packet2of cigarettes has an overwrapping of heat-shrink plastic material applied by the cellophaning machine, is rectangular-parallelepiped-shaped, and comprises two parallel end walls3(only one shown inFIG. 1), two parallel major lateral walls4(only one shown inFIG. 1), and two parallel minor lateral walls5(only one shown inFIG. 1).

Feed unit1comprises a conveyor6which receives packets2of cigarettes from a heat-seal conveyor7of the cellophaning machine, along which the superimposed portions of the plastic overwrapping at the two end walls3of each packet2of cigarettes are heat sealed. Conveyor6feeds an orderly succession of packets2of cigarettes in a horizontal direction8(rightwards inFIG. 1), and comprises a succession of pockets9, each housing a respective packet2of cigarettes. In a preferred embodiment shown inFIG. 1, conveyor6comprises two conveyor belts10located above and below the path of packets2of cigarettes to define a tunnel through which packets2of cigarettes travel. Each conveyor belt10has a number of push members11crosswise to direction8and defining pockets9. In other words, each packet2of cigarettes is inserted inside a pocket9bounded at the rear by two push members11(one for each conveyor belt10), and at the front by another two push members11(one for each conveyor belt10), and each packet2of cigarettes is pushed in direction8by the two rear push members11(one for each conveyor belt10).

In a preferred embodiment, the two conveyor belts10are identical (to reduce the number of component parts) and are offset in direction8, so that packets2of cigarettes are first deposited by heat-seal conveyor7onto the bottom conveyor belt10, and are only later engaged by the top conveyor belt10. Conversely, at the end of conveyor6, packets2of cigarettes leave the bottom conveyor belt10and are pushed in direction8by the top conveyor belt10only; in which case, conveyor6comprises a slide surface forming an extension of bottom conveyor belt10, and along which packets2of cigarettes are pushed by top conveyor belt10.

For easy access to the area through which packets2of cigarettes travel, bottom conveyor belt10is fixed, and top conveyor belt10is movable with respect to bottom conveyor belt10both vertically (by means of a cam which, as it rotates, lifts the end pulleys of top conveyor belt10) and horizontally (by means of a carriage supporting the end pulleys of top conveyor belt10).

Feed unit1comprises a conveyor12which is located beneath and parallel to conveyor6, feeds an orderly succession of packets2of cigarettes in a horizontal direction13(leftwards inFIG. 1) opposite direction8of conveyor6, and comprises a succession of pockets14, each housing a respective packet2of cigarettes. In a preferred embodiment shown inFIG. 1, conveyor12comprises and endless conveyor belt15looped about an output pulley16mounted to move back and forth parallel to direction13.

Conveyor12comprises an initial horizontal branch17followed by a curved end branch18extending900about output pulley16. Along initial horizontal branch17of conveyor12, packets2of cigarettes rest on conveyor belt15, and, along curved end branch18of conveyor12, packets2of cigarettes are guided about output pulley16by an arc-shaped rail19flanking output pulley16between an inlet and an outlet of packets2of cigarettes to prevent packets2of cigarettes from being spun out of pockets14. Rail19is preferably hinged to rotate between a work position (shown in the drawings) and a maintenance position, and is maintained in the work position by a push member (e.g. an air spring).

Conveyor belt15has a number of push members20crosswise to direction13and defining pockets14. In other words, each packet2of cigarettes is inserted inside a pocket14bounded at the rear by a push member20and at the front by another push member20, and each packet2of cigarettes is pushed in direction13by the rear push member20.

As stated, output pulley16is mounted to move back and forth parallel to direction13. For which purpose, a carriage21supports output pulley16and is mounted to run along a rail parallel to direction13; and an endless flexible transmission member22is fixed to the front and back of carriage21and looped about an idle pulley23and a powered pulley24. Half of flexible transmission member22is defined by a toothed belt25extending about powered pulley24which is also toothed; and the other half is defined by a smooth cable26(i.e. with no teeth) extending about idle pulley23which is also smooth.

In a preferred embodiment, toothed belt25forming part of flexible transmission member22supports a number of U-shaped shells27, each having a trapezoidal cross section with the minor base at toothed belt25, and the major base opposite toothed belt25. Shells27as a whole define a flexible supporting body located beneath horizontal initial branch17of conveyor12to provide adequate mechanical support of conveyor belt15and prevent excessive vertical deformation of conveyor belt15under the weight of packets2of cigarettes.

Moving output pulley16parallel to direction13provides for increasing or reducing the length of horizontal initial branch17of conveyor12, i.e. of conveyor belt15. More specifically,FIG. 1shows output pulley16close to a rightward stop, so horizontal initial branch17of conveyor12is almost of minimum length.

As shown inFIG. 2, feed unit1comprises a transfer device28for transferring packets2of cigarettes from conveyor6to conveyor12. Transfer device28comprises a wheel29rotating about a horizontal axis of rotation30perpendicular to theFIG. 2plane, and supporting a number of pockets31, each of which picks up a packet2of cigarettes from the output end of conveyor6, and feeds packet2of cigarettes to the input end of conveyor12. Each pocket31is fitted to an arm32hinged to wheel29to rotate with respect to wheel29about an axis of rotation33parallel to axis of rotation30and under the control of a cam system (not shown). Preferably, each pocket31comprises a gripper with two fixed jaws, i.e. a fixed distance apart; and transfer device28comprises an arc-shaped rail34flanking wheel29between an inlet and an outlet of packets2of cigarettes to prevent packets2of cigarettes from being spun out of pockets31. Rail34is preferably hinged to rotate between a work position (shown in the drawings) and a maintenance position, and is maintained in the work position by a push member (e.g. an air spring).

As shown inFIG. 1, feed unit1comprises a conveyor35parallel to conveyor12, and which feeds an orderly succession of packets2of cigarettes in a horizontal direction36(leftwards inFIG. 1) parallel to and in the same direction as direction13of conveyor12, and comprises a succession of pockets37, each housing a respective packet2of cigarettes.

In a preferred embodiment shown inFIG. 1, conveyor35is L-shaped with a horizontal initial branch38and a following vertical end branch39connected to each other by a curved connecting portion40. Conveyor35comprises two conveyor belts41which are L-shaped like conveyor35, are located side by side, and have respective numbers of push members42defining pockets37. In other words, each packet2of cigarettes is inserted inside a pocket37bounded at the rear by two push members42(one for each conveyor belt41), and at the front by another two push members42(one for each conveyor belt41), and each packet2of cigarettes is pushed in direction36by the two rear push members42(one for each conveyor belt41). Along horizontal initial branch38of conveyor35and along curved connecting portion40, a slide surface43is provided, along which packets2of cigarettes are pushed by conveyor belts41.

Each conveyor belt41extends about a top end pulley44rotating about a horizontal axis of rotation45parallel to theFIG. 1plane, and a bottom end pulley46rotating about a vertical axis of rotation47perpendicular to axis of rotation45. Since each conveyor belt41, to wind about top end pulley44and bottom end pulley46, must be able to rotate about two perpendicular axes, conveyor belt41is defined by a number of links hinged to one another to rotate with respect to one another about two perpendicular axes. For each conveyor belt41, one pulley44or46is idle, and the other pulley46or44is powered to move conveyor belt41.

As shown inFIG. 1, the horizontal initial branch38of conveyor35is aligned vertically with and located beneath conveyor12, so that conveyor12deposits packets2of cigarettes inside respective pockets37of conveyor35. In other words, curved end branch18of conveyor12terminates directly over horizontal initial branch38of conveyor35, so that each packet2of cigarettes coming off conveyor12is inserted inside a respective pocket37of conveyor35. Output pulley16of conveyor12therefore constitutes a transfer device for transferring packets2of cigarettes from pockets14of conveyor12to pockets37of conveyor35.

As stated, moving output pulley16parallel to direction13(i.e. parallel to direction36) provides for increasing or reducing the length of horizontal initial branch17of conveyor12, i.e. of conveyor belt15. In other words, the length of initial branch17of conveyor belt15is physically altered by moving output pulley16parallel to direction13(i.e. parallel to direction36). Similarly, moving output pulley16parallel to direction13(i.e. parallel to direction36) provides for increasing or reducing the length of horizontal initial branch38of conveyor35, by altering the position in which packets2of cigarettes are fed into pockets37of conveyor35. In other words, moving output pulley16parallel to direction13(i.e. parallel to direction36) alters the size of the portion of horizontal initial branch38of conveyor35actually involving packets2of cigarettes, as opposed to physically altering the length of horizontal initial branch38of conveyor35.

Packets2of cigarettes are released from conveyor35to the cartoning machine group-forming unit, which forms groups of packets2of cigarettes, each comprising a given number of (normally ten) packets2of cigarettes. As shown inFIG. 1, the group-forming unit of the cartoning machine comprises a transfer wheel48rotating about a horizontal axis of rotation49perpendicular to theFIG. 1plane, and supporting a number of pockets50, each of which picks up a pair of superimposed packets2of cigarettes off the output end of conveyor35, and feeds the pair of superimposed packets2of cigarettes to a further horizontal conveyor which compacts the pairs of superimposed packets2of cigarettes into groups of packets2of cigarettes.

Each pocket50is fitted to an arm51hinged to transfer wheel48to rotate with respect to transfer wheel48about an axis of rotation52parallel to axis of rotation30, and under the control of a cam system (not shown). Preferably, each pocket50is defined by a gripper with two jaws; and transfer wheel48is fitted with an arc-shaped rail53flanking transfer wheel48between an inlet and an outlet of packets2of cigarettes to prevent packets2of cigarettes from being spun out of pockets50. Rail53is preferably hinged to rotate between a work position (shown in the drawings) and a maintenance position, and is maintained in the work position by a push member (e.g. an air spring).

As shown inFIG. 1, it is important to note that packets2of cigarettes are housed inside pockets9of conveyor6in a first position with respect to direction8(i.e. are laid flat), are housed inside pockets14of conveyor12in the first position with respect to direction13(i.e. are laid flat), and are housed inside pockets37of conveyor35in a second position with respect to direction36(i.e. are positioned on edge). More specifically, in the first position, the major lateral walls4of each packet2of cigarettes are parallel to direction8,13, and the minor lateral walls5are perpendicular to direction8,13; and, in the second position, the major lateral walls4of each packet2of cigarettes are perpendicular to direction36, and the minor lateral walls5are parallel to direction36. The change in the position of packets2of cigarettes is made by output pulley16rotating each packet2of cigarettes900about its central axis of symmetry.

As shown inFIG. 1, a heat-shrink device54subjects each packet2of cigarettes to a first heat-shrink operation along conveyor6; and a further heat-shrink device55subjects each packet2of cigarettes to a second heat-shrink operation along vertical end branch39of conveyor35. By virtue of the change in position of packets2of cigarettes, heat-shrink device54heats major lateral walls4of each packet2of cigarettes, and heat-shrink device55heats minor lateral walls5of each packet2of cigarettes, thus effectively smoothing out the whole lateral surface and achieving a high-quality finish of the heat-shrink plastic overwrapping of each packet2of cigarettes.

Heat-shrink device54is defined by the two conveyor belts10, each of which has a metal belt which rests on a major lateral wall4of each packet2of cigarettes and is heated by conduction by an electric heater with heating resistors.

Heat-shrink device55is defined by two conveyor belts56located on opposite sides of vertical end branch39of conveyor35to form a tunnel through which packets2of cigarettes travel; and each conveyor belt56has a metal belt which rests on a minor lateral wall5of each packet2of cigarettes and is heated by conduction by an electric heater with heating resistors. For easy access to the area in which packets2of cigarettes travel, each conveyor belt56is movable with respect to conveyor35in two perpendicular horizontal directions.

As shown inFIG. 1, along cellophaning machine heat-seal conveyor7, a control station57with optical sensors controls the overwrapping quality of each packet2of cigarettes; and, downstream from control station57, a reject station58is provided where any faulty packets2of cigarettes (i.e. with flawed overwrappings) are expelled from heat-seal conveyor7. More specifically, reject station58comprises a conveyor belt positioned crosswise and obliquely with respect to heat-seal conveyor7, and supporting a number of teeth; and, when the conveyor belt of reject station58is moved forward one step, a tooth moves through heat-seal conveyor7to push a packet2of cigarettes off heat-seal conveyor7.

As shown inFIG. 1, a control device59supervises operation of feed unit1, and is connected to an optical sensor60for detecting the presence of an empty pocket31(i.e. a gap) on transfer device28. In an equivalent embodiment, optical sensor60may be located upstream from transfer device28, along conveyor6, or downstream from transfer device, along conveyor12. It is important to note that, from the operating standpoint, the location of optical sensor60is unimportant, in that a gap along conveyor6is automatically and predictably transmitted to transfer device28and hence conveyor12. The actual location of optical sensor60therefore depends solely on the restrictions posed by the size of optical sensor60, and the desired amount of advance warning of the gap.

Feed unit1comprises a first drive controlled by control device59and for powering conveyor6, conveyor12, and transfer device28; a second drive controlled by control device59and for powering flexible member22to move output pulley16; and a third drive controlled by control device59and for powering conveyor35.

Operation of feed unit1as described above will now be described with particular reference toFIG. 1.

In normal operating conditions of feed unit1, the number of packets2of cigarettes produced on the cellophaning machine equals the number of packets2of cigarettes absorbed by the cartoning machine, so there are no empty pockets9(i.e. gaps) along conveyor6, and output pulley16of conveyor12remains in a fixed position (i.e. is not translated), and transfers packets2of cigarettes from conveyor12to conveyor35, filling all the pockets37on conveyor35.

Upon detection of an empty pocket31(i.e. a gap) on transfer device28and later along conveyor12, control device59shifts output pulley16of conveyor12parallel to direction13and towards conveyor35(i.e. away from transfer device28and leftwards inFIG. 1), while keeping output pulley16in time with conveyors12and35to transfer packets2of cigarettes from pockets14of conveyor12to pockets37of conveyor35, and fill all of pockets37. The gap on transfer device28and later on conveyor12is thus eliminated, so conveyor35has no gaps (i.e. empty pockets37). In the event of a number of consecutive gaps along conveyor12(i.e. on transfer device28), output pulley16of conveyor12is moved consecutively towards conveyor35to cover all the consecutive gaps.

Obviously, the above strategy of eliminating gaps along conveyor12(i.e. on transfer device28) applies until output pulley16of conveyor12reaches a stop at vertical branch39of conveyor35. As output pulley16nears the stop at vertical branch39of conveyor35, control device59stops conveyor35, stops conveyors12,6and transfer device28one after the other, and arrests translation of output pulley16in time with the cartoning machine group-forming unit to allow the group-forming unit to complete the last carton being formed, and so allow the cartoning machine to make a so-called “carton skip”, i.e. cut off packing material supply and perform a no-load cycle to avoid producing rejects.

Alternatively, as output pulley16nears the stop at vertical branch39of conveyor35, control device59controls feed unit1to form, along conveyor35, a number of gaps equal to a multiple of the number of packets2of cigarettes in each group of packets2of cigarettes, thus enabling the cartoning machine, on receiving a number of gaps equal to the number of packets2of cigarettes in each group of packets2of cigarettes, to make a “carton skip”, i.e. cut off packing material supply and perform a no-load cycle to avoid producing rejects. In other words, when the gaps along conveyor12(i.e. on transfer device28) can no longer be compensated, the uncompensated gaps are transferred successively to conveyor35so they always equal a multiple of the number of packets2of cigarettes in each group of packets2of cigarettes, thus enabling the cartoning machine to make even repeated “carton skips” to avoid producing rejects.

On nearing the stop at vertical branch39of conveyor35, output pulley16of conveyor12can be moved into an intermediate position between its two stops by moving it, parallel to direction13, from conveyor35towards transfer device28, so as to form, along conveyor35, a number of consecutive empty pockets37(gaps) equal to the number of packets2of cigarettes in each group of packets2of cigarettes. In which case, the cartoning machine again makes a “carton skip” to avoid producing rejects. In this case too, to avoid forming gaps (i.e. empty pockets37) along conveyor35, conveyor35may be stopped in time with the cartoning machine group-forming unit to allow the group-forming unit to complete the last carton being formed.

In the event of stoppage of the cellophaning machine or cartoning machine, the cartoning machine or cellophaning machine is also stopped automatically; in which case, feed unit1is controlled by control device59in an attempt to avoid forming incomplete groups of packets2of cigarettes in the cartoning machine group-forming unit, or leaving stationary packets2of cigarettes inside heat-shrink devices54and55. Heat-shrink devices54and55, in fact, are designed to heat packets2of cigarettes for at most a few seconds. So, if a packet of cigarettes2is left inside heat-shrink device54or55for longer than this, the overwrapping of packet2of cigarettes is irreparably damaged by overheating.

In a preferred embodiment shown inFIG. 1, feed unit1comprises a loading device61for loading pockets14of conveyor12with a number of packets2of cigarettes inside a removable magazine62. The function of loading device61is to feed back into the packing cycle any cellophane-wrapped packets2of cigarettes previously removed from the packing cycle, but with no flaws. For example, in the event a carton is rejected, the packets2of cigarettes in the carton have no flaws, and can therefore be fed back into the packing cycle.

Magazine62has five vertical channels63, each housing a stack of packets2of cigarettes, which move down vertical channel63by gravity; and loading device61comprises a push device64with five pushers, each of which moves through a vertical channel63to push the last (i.e. bottom) packet2of cigarettes in the stack out of vertical channel63and into a respective pocket of conveyor12.

To empty magazine62, at least five consecutive gaps (i.e. empty pockets14) are formed along conveyor12, and output pulley16of conveyor12is moved into position close to the stop at vertical branch39of conveyor35(so that horizontal branch17of conveyor12is positioned opposite loading device61); and push device64is moved back and forth to transfer five packets2of cigarettes from vertical channels63of magazine62into five empty pockets14of conveyor12.

Loading device61has numerous advantages, by effectively feeding back into the packing cycle, with no assistance whatsoever on the part of the operator, any cellophane-wrapped packets2of cigarettes previously removed from the packing cycle but with no flaws, thus making recovery of such packets2of cigarettes economically feasible.

Feed unit1as described above has numerous advantages: it is fairly straightforward mechanically; allows easy access to all the areas through which packets2of cigarettes travel; allows optimum location of heat-shrink devices54,55necessary to obtain high-quality plastic overwrappings of packets2of cigarettes; and effectively handles sharp deceleration (or stoppage) of the cartoning machine without producing reject packets2of cigarettes.