GB2204717A

GB2204717A - Packaging machine control

Info

Publication number: GB2204717A
Application number: GB08810558A
Authority: GB
Inventors: Francesco Gatteschi
Original assignee: OCM SpA
Current assignee: OCM SpA
Priority date: 1987-05-13
Filing date: 1988-05-05
Publication date: 1988-11-16
Also published as: FR2615169B1; IT8720507A0; IT1215486B; FR2615169A1; GB8810558D0

Abstract

A packaging machine has a motor 31 which drives feed rolls and a cutting blade for heat-shrinkable wrapping film, and a motor 42 which drives a wrapping unit. When the speed of motor 42 is varied by an adjuster 49, an encoder 44 detects the new speed and devices 51, 52, 53 adjust the speed of motor 31 as a (preferably Gaussian) function thereof. <IMAGE>

Description

"EQUIPMENT FOR FILM FEEDING AND CUTTING INTO FILM SHEETS ON A PACKAGING MACHINE" The present invention relates to an equipment for feeding the film, and cutting it into film sheets on 3 packaging machine.

In the packaging machines, which carry out the packaging of products, or of product groups, such as bottles, boxes, cans, and sorth, which constitute packs, inside sheets of films of heat-shrinking material, both devices which promote the selection of the products, or of the product groups to be packaged, and make them advance, bringing the on the film sheets, and further devices which wrap the individual film sheet around the products or product group, are present.

The devices, or equipment units, known from the prior art for feeding these individual sheets are based on a mechanisal-transmission device, or on self-braking motors, capable of indexing, which limit the versatility of the packaging machine in coping with the various format changes, i . e., wr,en the need arises of cutting sheets with a different length, when the product, or product group, to be wrapped, changes.

Furthermore, the devices equipped with self-braking motors, show speed limits, beyond which a correct operation of the mechanisms they drive - and, as a consequence, of the whole packaging machine - cannot be obtained any longer.

The purpose of the present invention is, above all, to overcome the above-said problems, by providing an equipment for feeding a film, or, better, film sheets obtained from a continuous film, which is capable of supplying an extremely high versatility in the film sheet format change, according to the operating requirements, within very short times, while simultaneously allowing the machine to operate at very high steady-state running speeds.

This, and still further purposes according to the present invention are achieved by providing an equipment for feeding the film, and cutting same film into sheets on a packaging machine of the type wherein products, or product groups, are fed, suitably spaced apart from each other, to a positioning unit, above individual sheets, and are wrapped inside individual sheets, of a heatshrinking material sequentially fed after each other by said feeding equipment, with said packaging machine being equipped with a main motor, and said feeding equipment being equipped with a central motor of its own, characterized in that said feeding equipment comprises a unit for driving, and cutting said individual sheets from, a continuous film supplied by a film-roll, and a conveyor means for transferring said individual cut film sheets to said positioning and wrapping unit of said packaging machine, with said main motor and said central motor being operatively connected with an electronic device which determines, with varying sizes of said products -or product groups, and with varying packaging speeds, -a consequent change in the revolving speed of said central motor according to a predetermined speed law.

Features and advantages of the instant invention will be made clear by the following detailed disclosure of a preferred form or practical embodiment thereof, shown for me rely exemplifying, non-limitative purposes in the hereto attached drawings, wherein: Figure 1 shows a schematic perspective view of a packaging machine equipped with an equipment according to the present invention; Figure 2 shows a magnified cross sectional view of a detail of the equipment according to the invention, Figure 3 shows a side view according to arrow A of Figure 2, Figure 4 is a side view according to arrow B of Figure 2, and Figure 5 is a block diagram showing the connections, the driving motors and the electronic control unit governing the feeding equipment according to the invention.

Referring first to Figure 1, with a generic packaging machine, a diagram of which is shown in the top portion of the figure, and is generally indicated by the reference nuneral 11, a feeding equipment is associated, for feeding a film 12 supplied by a bobbin 13, or, better, film sheets 14 cut from a film of heat-shrinking material for the packaging of products, e.g., gathered as product groups, and indicated by the reference numeral 15.The products, fed in a known way, are selected by means of a selector 16, are separated from one another in order to form said product groups 15, and, suitably spaced apart from one another, are transferred, in an aswell known way, by means of a transversal-bar conveyor means, a diagram of which is indicated by the reference numeral 17 and running above a guide plane, towards a positioning and wrapping unit, indicated by the reference numeral 18, inside individual sheets 14 made from a heatshrinking material. Finally, when the wrapping step is finished, the product group 15 completely wrapped inside the film sheet 14, with an overlapping of the edges of the same film in the bottom portion thereof, is transferred to an oven, also of a well-known type, wherein the film is heat-shrunk.

It is precisely at the inlet of said positioning and wrapping unit 18, that an equipment for feeding the film, and cutting it into sheets, according to the present invention, is installed.

Said equipment, which receives, as said, in a known way, the continuous film 12 unwound from the bobbin 13, essentially comprises, be sides a set of return rollers 19, as skin in Figures 2, 3 and 4, a driving/cutting unit 20 for driving and cutting the individual film sheets 14, and a means 21 for transferring said cut sheets 14 towards said positioning and wrapping unit 18.

The driving/cutting unit 20 comprises a first couple of rolls 22 which drive the film 12, and a second couple of rolls 23 which drive the film 12, or, better, the film sheet 14 after that it is cut by means of rotary cutting means constituted by a blade 24 and a counter-blade 25.

For example, the blade 24 is formed by a flat bar transversely toothed in 26, which is revolutionary, and operatively enters a counter-channel 27 transversely provided on the counter-blade 25, which, for exemplifying purposes, may be given a roll shape, and is revolutionary too.

The so-produced individual film sheets 14 come, due to the action by the second couple of driving rolls 23, above the transfer means 21. Such a transfer means 21 comprises a box 28 connected with a vacuum pump (not shown in the Figures), above which a plurality of belts 29 are driven, which are parallel to one another, and are provided with a set of holes 30, through which the vacuum accomplished inside the box acts to retain the sheets 14 of heat-shrinking film1 simultaneously transferring them to the positioning/wrapping unit 18.

By referring to Figures 2, 3 and 4, one can observe that a single central motor 31 drives, through a first transmission 32, an intermediate shaft 33 to revolve, which motor constitutes the motion source for both the driving/cutting unit 20 and the plurality of belts 29 of the transfer means 21. More precisely (Figure 4), on an end of said intermediate shaft 33, a second transmission 34 is provided, which, with the interposition of a coupling means 35, controls the revolution through a further, third, transmission 36, of both the blade 24 and the counter-blade 25. The coupling means 35 is controlled for engagement and disengagement by means of a microswitch 37 acting as a function of the length of the sheet 14, predetermined on the basis of the size of the product group 15.

At the other end of the intermediate shaft 33 (Figure 3), a fourth transmission 38 drives both said first couple of rolls 22 and said second couple of rolls 23. The speed of the first couple of rolls 22 is lower than the speed of the second couple of rollers 23, e.g., by approximately 10%, so that the film 12 between the two couples of rolls 22, 23 is tensioned, thus supporting the cutting action; in order that such a cutting action may be performed correctly, the speed of the blade 26 and of the counter-blade 27 shall result higher, e.g., by approximately 30%, than the speed of the first couple of rolls 22.

A fifth transmission 39, also branching from the intermediate shaft 33, promotes the revolution of a roll 40 which is positioned at the inlet end of the box 28, and through which the plurality of belts 29 are driven.

Associated with the central motor 31, a speedometer dynamo 41 is provided, which monitors the speed moment by moment. Such a correlation is secured by the fact that with said central motor 42 both a second speedometer dynamo 43 and an encoder 44 are associated. The encoder 44 is operatively connected with the revolution of the main motor 42 and is, e.g., driven by a main shaft 45 (partially shown) of the packaging machine, so as to be also capable of detecting, moment by moment, the position of the product groups 15.From said main shaft 45, through a generic sixth transmission 46, the positioning/wrapping unit 18 derives its motion; said positionins/wrapping unit 18 may be essentially constituted by a closed-loop conveyor belt 47, as well as by a set of transversal bars 48 spaced apart from each other, and on board of a couple of closed-loop parallel chains longitudinally positioned relatively to said belt conveyor 47. The bars 48, rising from under the belt conveyor 47, meet the sheet 14 and cooperate to wrap said individual sheet of film 14 above, and around the product group 15 received from said belt conveyor 47.

The interdependence between the central motor 31 of the equipment according to the invention, and the main motor 42 of the packaging machine 11 can be schematically shown as depicted in Figure 5. One can thus see that by acting on a speed adjustment means 49, operatively connected with an inverter - i.e., a drive means for a.c.

motors - 50, an action is exerted on the main motor 42, e.g., an a.c. motor. The encoder 44 monitors the position moment by moment, and transmits a relevant signal to an electronic device 51. The electronic device 51 also contains, among its other functions, a determined speed law, which is such as to vary the motion of the feed equipment according to the present invention according to a substantially "omega"-shaped, or substantially Gaussshaped curve. As a consequence, with a varying signal from the encoder 44, the electronic device emits a determined signal, as a function of said predetermined curve, which is sent to a multiplier block 52, so as to be multiplied by a respective signal coming from the speedometer dynamo 43 operatively connected with the main motor 42.The resulting signal is sent to a drive 53 connected with the central motor 31 of the same equipment. The speedometer dynamo 41 associated with the central motor 31 verifies the speed of said central motor 31 under strict connection with the drive 53, so as to correct and remove any possible errors.

Also the microswitch 37 is operatively controlled by the encoder 44 to selectively act as a function of the group of products 15 under packaging, so as to provide the desired length of the sheet 14 which must wrap the same group 15.

Thus, an equipment according to the present invention makes it possible an extremely high flexibility to be achieved in the size, or in the format, of the film sheets fed towards the positioning and wrapping unit of the packaging machine with varying steady-state operating speeds of this latter. In fact, the presetting of an electronic equipment 51 which, according to a predetermined law, controls the speed of the transfer means which transfer said sheets, and, consequently, the speed of the drive and cutting unit, makes it possible the packaging machine to be advantageously run at high speeds, because it is capable of feeding the leading edge of the. individual film sheet to the positioning and wrapping unit when this latter receives products, or product groups.All the above, making due allowance for the fact that the total length of an individual film sheet 14 is much longer than the distance between two products, or product groups fed by a transfer unit, e.g., 17, to said positioning and wrapping unit. Thus, the individual film sheets 14, and, consequently, the film 12, undergo sudden accelerations and decelerations which are correlated with the constant operating speed of the packaging machine, even if the same speed of this latter may be selected more or less high.

Of course, on the equipment according to the present invention, as well as on the packaging machine, electrical cams are preferably provided, which monitor the correct operation of the individual parts and the correct presence of the products, or product groups, and of the relevant film sheets of a heat-shrinking material, having a length correlated with the length of the products being fed.

Claims

1. Equipment for feeding the film, and cutting same film into sheets on a packaging machine of the type wherein products, or product groups, are fed, suitably spaced apart from each other, to a positioning unit, above individual sheets, and are wrapped inside individual sheets, of a heat-shrinking material sequentially fed after each other by said feeding equipment, with said packaging machine being equipped with a main motor, and said feeding equipment being equipped with a central motor of its own, characterized in that said feeding device comprises a unit for driving, and cutting said individual sheets from, a continuous film supplied by a film-roll, and a conveyor means for transferring said individual cut film sheets to said positioning and wrapping unit of said packaging machine, with said main motor and said central motor being operatively connected with an electronic device which determines, with varying sizes of said products or product groups, and with varying packaging speeds, a consequent change in the revolving speed of said central motor according to a predetermined speed law.

2 Equipment according to claim 1, characterized in that said speed law is defined by a Gauss curve.

3. Equipment according to claim 1, characterized in that between said main motor and said electronic equipment a position encoder is interposed.

4. Equipment according to claim 1 or 3, characterized in that the signal output generated by said electronic equipment is sent to a multiplier block, in order to be correlated with a relevant signal coming from a first speedometer dynamo associated with said main motor, and to be subsequently sent to contol a drive for said central motor.

5. Equipment according to claim 4, characterized in that with said central motor a second speedometer dynamo is associated, which is operatively connected with said drive of said central motor.

6. Equipment according to claim 1, characterized in that the drive unit is composed by a first couple of rolls and a second couple of rolls, revolving at different speeds, so that the film coming from said bobin in maintained under tension.

7. Equipment according to claim 1, characterized in that said cutting unit comprises a blade and a counterblade, both revolving and driven by said central motor, with the interposition of a coupling.

8. Equipment according to claim 7, characterized in that said cutting unit is actuated by a position encoder operatively connected with said main motor.

9. Equipment according to claim 1, characterized in that between said central motor and said driving and cutting unit, a return shaft is interposed, and relevant transmissions are present, which branch off from said return shaft in order to drive said drive/cutting unit.

10. Equipment according to claim 9, characterized in that said transfer means is operatively Linked through a relevant transmission.

11. Equipment according to claim 1, characterized in that said transfer means comprises a box connected with a vacuum pump, above which a plurality of tapes parallel to each other are driven, which are provided with a set of holes through which the vacuum provided inside said box acts, so as to retain said film sheets and transfer them towards said positioning and wrapping unit of said packaging machine.

12. Equipment for feeding film and cutting it into sheets constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.