GB2289250A

GB2289250A - Heating continuous conveyors

Info

Publication number: GB2289250A
Application number: GB9509450A
Authority: GB
Inventors: Maurizio Rosa; Mario Turra; Armando Neri
Original assignee: GD SpA
Current assignee: GD SpA
Priority date: 1994-05-11
Filing date: 1995-05-10
Publication date: 1995-11-15
Anticipated expiration: 2015-05-10
Also published as: ITBO940206A1; DE19517131A1; GB2289250B; ITBO940206A0; GB9509450D0

Abstract

In a device for heating continuous conveyors (9), particularly as in a wrapping machine (3) designed to fashion packets (8) with parts overlapping and glued together which are then transferred to and taken up by the continuous conveyors (9), use is made of radiant heaters (14) positioned in close proximity to one branch (9b) of each conveyor (9); in operation, the radiant heaters (14) are governed by a control unit (13) capable of monitoring the temperature of the continuous conveyors (9) and maintaining it at a predetermined value. <IMAGE>

Description

is 1 2289250 A device for heating continuous conveyors, in particular, in

wrapping machines The present invention relates to a device for heating continuous conveyors, in particular, in wrapping machines. Machines of the type in question comprise one or more wrapping wheels by which products, consisting for example in groups of cigarettes, are enveloped in respective flat die-cuts folded in such a way as to form rigid packets, each with parts overlapping and glued together. The folded packets emerge from a wrapping wheel and are transferred to a feeder-drier, of which the, function is to cure the adhesive material uniting the overlapped parts; the feeder consists normally in a pair of continuous conveyors, typically belts, disposed parallel one with another. The packets are restrained and advanced by the conveyors, gripped by way of the faces coinciding with the overlapping parts in such a manner that these same parts are held in the correct position while the interposed adhesive material dries out.

2 is The adhesive material is dried by the application of heat to the continuous conveyors. Currently, the method most widely employed for the purpose of heating the aforementioned continuous conveyors is to invest them with a stream of hot air produced by suitable blowers; alternatively, there is the expedient of looping the continuous conveyors around a heater device that consists in a reservoir containing the oil utilized to lubricate the wrapping machine of which the conveyors form a part. Importantly, the folded packets must be heated to a temperature that can vary only within a relatively limited range of values, in order to prevent the risk of the packets being scorched through exposure to high temperatures, or of the adhesive material failing to dry when the temperature is too low. In practice, the conveyors in question may indeed be heated to a theoretically optimum temperature, or a temperature marginally higher than optimum, and yet the adhesive material will not always dry properly: it can therefore happen, as a result of the incomplete drying action, that the overlapping parts come adrift from the main body of the packet on running out from the conveyors.

9 1 3 is Measuring the temperature of continuous conveyors heated by the methods outlined above, the resulting values reveal that the heat required to dry the adhesive material completely is available only in the surface layer of the conveyors. This being so, it will be evident that the continuous conveyors are in fact unable to warm the packets sufficiently to accomplish the purpose in hand, especially at high operating speeds. The object of the present invention is to provide a device for heating continuous conveyors, from which the drawbacks mentioned above are absent. The stated object is duly realized according to the present invention through the adoption of a device for heating continuous conveyors, particularly in wrapping machines of the type wherein products are enveloped in an outer wrapper folded with parts overlapping and glued together, and taken up thus by the continuous conveyors, characterized in that it comprises radiant heating means positioned and operating in close proximity to a respective branch of each continuous conveyor, thereby raising the temperature and increasing the thermal capacity of the continuous conveyor to a value such that the continuous conveyor can transfer heat to the glued 4 is parts of the products for a period of time and in measure sufficient to dry the selfsame glued parts completely; and, in that it comprises monitoring and control means by which the temperature of each respective continuous conveyor can be sensed and maintained at a predetermined value. The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which: -fig 1 is the schematic side view of a feeder-drier equipped with the heating device according to the present invention and forming part of a wrapping machine of which the only component indicated is a wrapping wheel; -fig 2 illustrates a detail of the feeder-drier as in fig 1, enlarged and in a schematic side view; - fig 3 is the schematic illustration of a further detail of the feeder- drier shown in figs 1 and 2. Referring to the accompanying drawings, 2 denotes a feeder-drier forming part of a wrapping machine 3; such a machine comprises a wrapping wheel 4 from which the feeder-drier 2 is in receipt of packets 8 each consisting in an outer wrapper 6 with parts 7 overlapped and glued together. In the particular case in point, the outer wrapper 6 encloses a given _k number of cigarettes as illustrated schematically in fig 2, where the single cigarettes are indicated in phantom line and denoted 5. The wrapping wheel 4 of the machine 3 is positioned in such a manner that the single packets 8 can be transferred to the feeder-drier 2 correctly formed and ready to undergo a heating action, generated by the selfsame feeder-drier, during which an adhesive material (not indicated) interposed between the overlapping parts 7 of the packet 8 is caused to dry completely. The packet emerges from the wheel 4 with the outer wrapper 6 folded and joined though not completely secured. Accordingly, to prevent the overlapping parts 7 from separating and the entire wrapper 6 from coming undone, the feeder-drier 2 is composed of two continuous conveyors 9 disposed horizontally and in vertical alignment, the one above the other, arranged in mutual opposition on either side of a horizontal plane and set apart at a distance such that the successive packets 8 are taken up between two respective mutually opposed branches denoted 9a in the drawings; these enter into direct contact with the overlapping parts 7, which are located on opposite faces of the wrapper 6, applying a gentle 6 is compression so as to assist in maintaining their correct position. Each continuous conveyor 9 consists in a belt 10 looped arbund respective pulleys 11, of which two are positioned close to the wrapping wheel 4. The branches of the belts 10 not disposed in mutual opposition are routed around tension pulleys 22 and divided as a result into two consecutive portions denoted 9b and 9c. Of these, the portion of each belt denoted 9b is disposed nearer to the wrapping wheel 4 and subjected to the action of a respective heater device 1. Fig 1 shows the directions of movement followed by the various branches and portions 9a, 9b and gc of the continuous conveyors 9, indicated by respective arrows Fa, Fb and Fc. Observing the arrows, it will be seen that the two mutually opposed branches 9a move away from the wrapping wheel 4, and the branch portions denoted 9b toward the wheel 4. In effect, packets 8 are taken up from the wrapping wheel 4 by the mutually opposed branches 9a and fed forward, receiving heat in the process, whilst the adjoining branch portions 9b are heated, each by the relative heater device 1, immediately preceding the point at which the packets 8 are taken up.

A 7 is Each heater device 1 comprises heating means 12, disposed and operating in close proximity to the branch portion 9b of the respective continuous conveyor 9. Such heating means 12 are designed to raise the temperature of the continuous conveyor 9 and increase its thermal capacity to a value such as will result in heat being transferred to the glued parts 7 of the packet 8 for a period of time and in a measure sufficient to dry these same parts completely. Each heater device 1 further comprises respective monitoring and control means 13 by which the temperature of the relative conveyor 9 can be sensed and maintained constant. According to the invention, the heating means 12 incorporate means 14 of generating electromagnetic energy, which make no contact whatsoever with the respective continuous conveyor 9 when in operation. In a preferred embodiment, these means 14 will be radiant heaters, preferably ceramic type infrared radiating elements. The advantage of such heating means 12 consists in the fact that the transmitted energy is not thermal, but electromagnetic, hence able to penetrate the full depth of the belt 10 and thus increase its thermal capacity relative to a given surface temperature; this is in contrast to 8 the effects obtainable using conventional devices, where heat generated by convection warms only the surface layer of the belt 10 whilst the temperature at deeper layers tends to be lower. Nonetheless, the rise in temperature and thermal capacity of the continuous conveyor 9 would not alone be sufficient to ensure that the adhesive material dries out properly, given that the belt 10 may operate at a higher or lower linear velocity, according to the particular operating requirements. To guarantee the continuous and correct operation of the feeder-drier 2, the monitoring and control means 13 comprise temperature sensing means 15, also a monitoring and control unit 16 of which the input side is connected to the temperature sensing means 15 and the output side to regulator means 17 capable of varying the thermal capacity of the continuous conveyor 9. The monitoring and control unit 16 could be a thermostat, whereas temperature sensing means 15 would take the form of infrared type sensors able to detect the temperature of the moving belt 10. The thermal capacity of the belt 10 is controlled by interlocking both the radiant heaters 14 and the regulator means 17 to the monitoring and control 1 9 unit 16: the operating temperature of the radiant heaters 14 is thus governed by the monitoring and control unit 16, and the regulator means 17 ensure a suitably swift adjustment of the temperature when called for. Fig 3 illustrates two possible embodiments of the regulator means 17. In a first solution, the regulator means 17 are shown as a linear actuator 18 of which a first end is connected to a frame 19 supporting the radiant heaters 14, and the remaining end associated with a fixed supporting structure (not illustrated). The function of the linear actuator 18 is to translate the radiant heaters 14 either toward or away from the relative branch portion 9b of the conveyor 9. Naturally, the radiant heaters 14 are moved toward or away from the belt 10 in order respectively to reduce and to increase the thermal capacity of the continuous conveyor 9. In a second solution, still in fig 3, the regulator means 17 are shown as ventilation means consisting in a device 20 able to generate a flow of fluid, typically air, and at least one outlet nozzle 21 positioned in such a way as to direct air into the space that separates the radiant heaters 14 from the relative branch portion 9b of the conveyor 9. It will be observed that the nozzle 21 produces a rapid response whenever a reduction in the thermal capacity of the continuous conveyor 9 is required, due to the fact that the stream of air from the nozzle 21 cools both the conveyor 9 and the radiant heaters 14; thereafter, there will be a relatively lengthy interval before the operating temperature is re-established. In the case of the linear actuator 18, by contrast, the thermal capacity of the continuous conveyor 9 is reduced more slowly, but can also be recovered swiftly, since regulation is applied not through the use of a cooling agent, as with the nozzle 21, but by moving the actual heat source. Distancing the heaters, the thermal capacity of the conveyor will be lowered spontaneously by the resulting dissipation of heat. At the moment the need arises to increase the thermal capacity of the conveyor, it suffices simply to narrow the gap separating the relative branch from the heaters, which will be at the selected operating temperature already. Evidently, the adoption of a device for heating conveyors as described and illustrated will ensure that adhesive materials can be dried successfully, m 11 in the correct manner and without waste. Moreover, this same object is achieved without subjecting the continuous conveyor 9 to unduly high temperatures, as the heat applied in procuring increased thermal capacity penetrates through the full depth of the conveying medium rather than remaining limited to a surface layer only.

1) 12 Claims

A device for heating continuous conveyors in wrapping machines of the type wherein products are enveloped in an outer wrapper folded with parts overlapping and glued together, and taken up thus by the continuous conveyors,, characterized in that it comprises radiant heating means located and operating in close proximity to a respective branch of each continuous conveyor, thereby raising the temperature and increasing the thermal capacity of the continuous conveyor to a value such that the continuous conveyor can transfer heat to the glued parts of the products for a period of time and in measure sufficient to dry the selfsame glued parts completely; and, in that it further comprises monitoring and control means by which the temperature of each respective continuous conveyor is sensed and maintained at a predetermined value.

13 2) 3) 4) 6) A device as in claim 1, wherein the heating means are ceramic type infrared radiating elements.

A device as in claim 1 or 2, wherein monitoring and control means comprise temperature sensing means connected to at least one input of a monitoring and control unit, also regulator means interlocked to the monitoring and control unit and able to vary the thermal capacity of the continuous conveyor.

A device as in claim 3, wherein the heating means are governed directly by the monitoring and control unit, and regulator means consist in actuator means interlocked to the monitoring and control unit and designed to vary the distance of the heating means from the continuous conveyor.

A device as in claim 3, wherein the heating means are governed directly by the monitoring and control unit, and regulator means consist in cooling means interlocked to the monitoring and control unit and designed to cool the continuous conveyor.

A device as in claim 5, wherein cooling means consist in ventilation means by which a stream of 7) 14 fluid is directed toward the continuous conveyor.

A device for heating continuous conveyors, in particular in wrapping machines, substantially as described with reference to the accompanying drawings.

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