EP0232887A1 - Automatic dispenser for plastic bags - Google Patents

Abstract

1. Automatic dispenser for plastic bags (1), which are bundled by means of batch blocks (9) which are partly separated from each bag by means of a tear line (10), which is carried out in such a manner that intermediate pieces remain due to the combination of the batch blocks (9), which offer a certain resistance against being ripped away, such tear line forming the central part of the upper opening (8) of said bags, after being ripped off, said dispenser comprising a holder (31, 51) equipped with a means (15) for attaching or suspending said batches (11) to hocks, and a frame (16, 17; 53) provided with a suitable return-spring means (25, 54) due to which said frame is pressed against the said holder, or also by a respective load, said frame carrying at least one delivering roller (21) which is keyed on a shaft (20) which rotates within the said frame in a position parallel with respect to the tear line (10), having an engaging means (19) disposed upon said roller which completes one full turn each time a bag is dispensed, said roller carrying upon one part of its periphery an engaging means (27) the developed arc length of which corresponds substantially to the contact length (28) between said roller and the first bag up to the tear line (10) of said bag, said engaging arc being coated with a substance which is suitable to develop an engaging force for the first bag under the effect of the applied load, which is higher than the said resistance against ripping up said tear line (10), and on the other hand, a complementary sliding arc (29) is provided, under the effect of which the engaging force applied on the bag is smaller than the said resistance.

Description

The invention relates to the distribution of plastic bags such as those commonly used in supermarkets at exit points.

These bags, practically of a single type, are formed from a thin sheath of blown plastic, which is folded flat with double lateral pleats to form bellows, this sheath thus folded then being welded according to a straight edge transverse constituting the bottom, and along two edges in the extension of the opposite side over the width of the bellows to form the shoulder straps forming handles, then cut to separate the individual bags and to scallop the upper part in a substantially U-shaped cut, including the two edges substantially parallel to the axis of the sheath project beyond the interior fold lines of the bellows in order to open the handles, and the bottom of which intended to constitute the opening of the bag has in its central region an incompletely separated connecting tab of this edge to allow the assembly in a bundle, by welding the legs into a bundle attachment, in order to facilitate handling and counting of the bags s at the end of production. After counting the bundles, the bundle attachments are separated by tearing off to allow a complete rectilinear edge to remain at the opening of each bag.

Due to the particularly deformable and slippery nature of these bags, generally made of ultra-thin polyolefin, their handling at the checkout counter to distribute them to customers can only be done manually, generally by handle, making any counting difficult. In some cases, it has been envisaged to deliver the bags in non-delied bundles, the connecting tabs then being pierced with two orifices or a slot to allow attachment to conventional hooks-supports, so that the person responsible for the distribution can loosen them one by one or in small packages by simply pulling the bag by hand.

In both cases the cashier distributes to customers a quantity of bags determined without any precision and in general superfluous, which necessarily leads to waste.

To avoid this waste, automatic bag dispensers have been imaged using rollers in which the bags are placed end to end and incompletely separated. Such machines are fully efficient, extremely expensive in hand, and moreover they require bags in rolls, the special manufacture of which is itself much more expensive than the standard plastic bags described above.

The object of the invention is to provide an automatic bag dispenser which is in itself simple and economical, which uses only conventional and economical bags, and finally which avoids any waste.

The invention consists in using a support for bundled bags in front of which a frame, movable relative to the support, applies, with a determined application force, at least one roller with an axis parallel to the weakening line separating each tab connecting the edge forming the opening of the bag, this roller being rotated over one complete revolution for each bag distribution cycle, and being circumferentially divided into two sectors, including a drive sector, the development of which is substantially equal to the distance between the contact generator of the roller and the first bag and said line of weakness, and which is coated with a product ensuring proper adhesion with the wall of the bag to produce under the effect of said force d application of a driving force of the bag greater than the tensile strength of this line of weakness, and a sliding sector for which this same force of application of the roller produces a e driving force lower than the pullout resistance of this line of weakness.

• - la figure 1 est une vue de face en élévation d'un premier dispositif;
• - la figure 2 est une vue de dessus de ce même dispositif;
• - la figure 3 représente à plus grande échelle une vue de côté du dispositif;
• - la figure 4 est une schéma de positionnement des arcs d'entraî­nement;
• - la figure 5 est une vue en perspective d'une liaisse de sacs;
• - la figure 6 un schéma de la commande électronique; et
• - les figures 7, 8 et 9 représentent une variante de réalisa­tion, respectivement en coupe verticale, en élévation et en vue de dessus.

Other particular features of the invention will appear in the following description of various embodiments taken as examples and shown in the appended drawing, in which:

• - Figure 1 is a front elevation view of a first device;
• - Figure 2 is a top view of the same device;
• - Figure 3 shows on a larger scale a side view of the device;
• - Figure 4 is a diagram of positioning of the drive arcs;
• - Figure 5 is a perspective view of a wad of bags;
• - Figure 6 a diagram of the electronic control; and
• - Figures 7, 8 and 9 show an alternative embodiment, respectively in vertical section, in elevation and in top view.

We see in particular in Figure 5 the appearance of a bundle, generally grouping 50 bags. Each bag 1 comprises on each side the double lateral pleats 2 of the sheath, with inward the internal pleat 3 of the bellows, a transverse bottom weld 4 and two upper welds 5 closing the bellows at the straps 6 intended to constitute the handles being opened by the lateral edges 7 of the notch which project slightly beyond the internal folds 3. The bottom 8 of the U-shaped notch constitutes the edge of the opening of the bag and comprises, in the vicinity of its central part, a connecting tab 9 which is incompletely separated from the bag 1 by means of a rupture line 10 extending the bottom 8 inside each leg 9. This rupture line 10 is formed of successive slots leaving subsist between them sized reserves to ensure a resistance to tearing determined. All of the connecting tabs 9 of the 50 bags of a bundle are joined together in a single bundle attachment 11 by hot welding, and generally provided with perforations 12 to facilitate its tearing off after handling and stacking of the bundles at the end of manufacture, especially for counting and storing bags in group packaging.

It is therefore possible at no additional cost to obtain delivery of the bags which have not been untied, which is already the case in exceptional cases for manual untying of the various bags.

The invention uses such bundles of bags, which are particularly economical since they are already produced in large quantities by fully automatic means. On the other hand, it proposes to relax the various bags successively and individually from a bundle or a stack of bundles and in an automatic manner.

For this there are many difficulties. On the one hand the thickness of each bundle is twice as large at the side bellows and straps 6 as at the central part, which does not allow regular stacking. On the other hand, the plastic used, generally an ultrathin polyolefin, is extremely deformable and very slippery, so that all the usual means of handling used for example in stationery are ineffective.

To solve these various problems, the invention uses a support 13, which is assumed for the moment to be vertical, with a compensating shim 14 vertically occupying the central region of the bag substantially over the width of the bundle attachment 11 and intended to compensate for the differences in thickness which have just been indicated. At its upper part, this wedge has two hooks 15, visible in particular in FIG. 3, and intended to penetrate through the openings 12 of each bundle attachment 11, so as to thus constitute a suspended reserve of one or more bundles bags. For example, a dozen bundles of 50 bags constitutes a reserve of 500 bags, generally sufficient for one day of operation and nevertheless leading to a relatively reasonable thickness.

To extract the bags 1 successively, the dispenser according to the invention comprises an articulated frame, formed by two lateral arms 16 joined at their upper part by a cross member 17, the two arms being articulated at their lower end by means of two articulations 18 fixed at the bottom of the support 13.

On one of the arms 16 is fixed a geared motor 19 driving in rotation a shaft 20 which rotates in appropriate bearings in each arm 16 and which is mounted parallel to the rupture line 10 of the bags 1, at a certain distance below that -this. On this shaft 20 is wedged a cylindrical roller 21 whose length is substantially equal to or slightly greater than the length of the breaking line 10 of each bag. The device further comprises a locating disc 22, wedged on the shaft 20 or on the other end of the axis of the geared motor 19, and making it possible to locate an angular position determined from this shaft, therefore from the roller 21. This is obtained for example by an optoelectronic detector 23 placed astride the edge of the disc 22, which comprises a perforation or a tooth making it possible to identify the passage through this particular position which is chosen as rest position. An electronic control E which will be examined subsequently makes it possible, from this rest position, to turn the engine exactly one revolution until the same rest position is found. This rotation of the roller 21 takes place in the direction represented by the arrow 24, that is to say in the direction which exerts a traction on the breaking line 10.

A weight or spring device exerts a tilting force on the tilting frame 16-17 to apply the roller 21 against the stack of bags. This device can be constituted for example by a pair of cables 25 returned on pulleys 26 and leading to a counterweight or to a not shown spring reel drum.

As illustrated in particular in FIG. 4, the periphery of the roller 21 comprises a drive sector 27, the development of which, starting from the horizontal generator 28 in contact with the stack of bags in the rest position, corresponds substantially to the distance between this generator 28 and the rupture line 10. This drive sector 27 is coated with an adhesion material allowing, with the effort of application of the roller supplied by the cables 25, to ensure a drive effort of the first bag greater than the resistance to tearing of its breaking line 10. For this, the roller 21 is coated on this arc 27 with an adherent part constituted for example by coarse-grained emery cloth allowing it to hang in the plastic used by micro-penetrations rather than by friction. This adherent part can also be constituted by a rubber coating with surface sculptures, like the product sold under the designation of "flu surface", reference GN 20 of the Balatros brand. The complementary arc 29 of the roller 21 remains on the contrary entirely smooth so that, always with the same application force, it exerts on the bag against which it is in contact only a force less than the resistance to tearing of the breaking line.

As can be seen in the figures, the roller 21 is close to the breaking line 10 so that its grip arc 27 is limited to approximately 90 °, the majority of the circumference therefore remaining smooth.

In this way, each time the electronic control produces a rotation of one revolution of the roller 21 in the direction 24 from the rest position shown in FIG. 4, this produces the uprooting of a bag, then its drive until the rupture line 10, now constituting the edge 8 of the opening of the bag, arrives at the rear end of the grip arc 27. At this moment the roller continues to rotate on the second underlying bag but skating by its smooth part 29 in order to avoid already extracting this second bag.

To prevent the straps 6 from causing discomfort in this movement, a pair of bungee cords 30 hooked to the support 13 hold these straps in position while allowing their escape during traction.

The assembly is naturally enclosed in a protective cover, not shown, leaving an opening slot at the lower end, so that the preceding movement allows the first bag to pass through this slot, then fall entirely, or failing this. be able to be extracted by hand.

As an improvement, to extend this training of each bag, a second roller 31 can be placed below the roller 21 and mounted on a shaft 32 parallel to the previous one, to which it is joined by a carriage formed by two longitudinal members 33 joined by a cross member 33a. The shaft 32 is pressed individually in the direction of the bag stack by a pair of springs 34, and the roller 31, like the roller 21 and as shown in FIG. 4, has a drive sector 27a and a smooth complementary sector 29a, with the same relationship between the development of the grip arc and the distance to the breaking line 10. However, the roller 31 being much lower above this breaking line than the roller 21, the arc 27a occupies, for example, an arc from 300 to 320 °, while the sliding arc 29a occupies the rest, that is to say from 60 to 40 ° C only.

Of course the two rollers 21 and 31 must be rotated in synchronism to return each time to its rest position. In addition, to prevent the first bag from being wrapped around the rollers, in particular the upper roller, it is preferable to make grooves in the two rollers in which endless bands or belts are housed which prevent this winding between the rollers, and in particular allow the device to operate in all positions other than that shown, including in the inverted horizontal position of the support 13.

In this case there is every interest in using these endless belts 35 to also ensure the synchronous drive of the roller 31 by the roller 21, by using for example toothed belts or chains, at least for one of between them if there are several. Thus the doubling of the rollers makes it possible to increase the effectiveness of the adhesion, or conversely to operate with a lower application force for each roller, and at the same time to prolong the extraction of the bag towards the exit, in particular for horizontal use.

To recharge the device, it is naturally enough to tilt the frame 16-17, by pulling for example on the upper cross member 17 against the tensioning device, to replace the desired number of bundles on the hooks 15 after having removed the worn bundle fasteners.

The control of the device according to the invention therefore amounts exclusively to supplying power to the motor 19 to perform these successive complete turns of the shaft 20 under the desired conditions. For this, an electronic device corresponding to the diagram in FIG. 6 is preferably used.

We see in this diagram, in addition to the motor 19 and the device for detecting the rest position associated with the optoelectronic sensor 23, a cash register push button 36 and a customer push button 37. The diagram essentially comprises a binary counter 38, which can comprise only one hexadecimal decade, and a discriminator 39 which, for each pulse received from the push-button 36, determines whether the time t which separates the rising edge of a new pulse from the rising edge of the previous pulse is greater than or equal to a value to, for example 5 seconds. If it does, it sends a reset pulse at 40 to the reset input of counter 38.

In addition, in all cases it sends by 41 an increment pulse to the input INC of the counter 38, the latter however passing through a device 42 for stopping at 9. A decoder 43 coupled to the outputs of the binary counter 38, and which operates for example as a decimal binary decoder, sends by 44 a stop signal to the device 42 if the decimal number N decoded is equal to 9 for example.

Conversely, if the decoder detects a zero value of N, it sends a stop pulse by 45 to a zero stop device 46 inserted on the transmission of the pulses of the button 37 ordered by the client. These pulses, which pass through 46 if N is greater than 0, pass through a shaping device 47 and control by their rising edge the establishment of the output signal 49 of a trigger device 48, which is interrupted when 'it receives the rising edge of a pulse from the device 23 for detecting the rest position. At the same time this last pulse is sent by 50 to the DEC decrement input of counter 38.

The operation is therefore as follows: when the cashier, in view of the volume of purchases made by the customer, presses the button 38 a certain number of times, for example three times to unlock three bags, the device 39 produces the initialization counter to zero, then sending an increment to change it to 1 during the first pulse. The following pulses, successive at an interval of less than 5 seconds, produce successive increments but not reset. If the cashier pushes the button 36 more than nine times, the following pulses have no effect, thanks to the device 42, in order to avoid an unexpected return to zero of the binary counter 38. The figure retained therefore corresponds to the maximum number of bags allocated to the customer. The number 9 seems to answer all practical cases, but it is naturally possible to reduce or increase it, for example up to 16 for a hexadecimal decade, or beyond by using several decades.

When the customer wants a bag, it therefore suffices to press the button 37 to cause the motor 19 to be powered by the command 51 depending on the output signal 49 from the trigger device 48, and this until that the detection by 23 of the rest position interrupts this command. We have seen in the foregoing how each rotation of a revolution of the shaft 20 produces the distribution of a bag. If the button 37 is kept pressed, this nevertheless distributes only one bag since, as we have seen, the triggering device 48 is only sensitive to rising edges of the signal intervening when it is in position rest. At the same time the command 50 decrements the counter 38 each time a bag is dispensed.

In this way when the number of bags allocated by the cashier, for example 3 in the previous example, is exhausted, the pusher 37 remains ineffective due to the device 46 for stopping at zero. Conversely, if a customer does not use the total number of bags allocated by the cashier, the unused number, remaining in memory in the counter 38, is not added to the allocation made by the cashier to the next customer using the device. of discrimination 39 which resets the counter 38 to zero during the first pulse of 36 determining the allocation to the next client, this necessarily occurring after a time t greater than To after the last pulse received.

The device is therefore extremely efficient mechanically, but at the same time relatively simple and easy to use, even in the most complex case envisaged. As a variant, it is possible, if desired, to determine the number of bags to be allocated directly by the amount recorded in the cash register, for example at the rate of one bag for each fraction of a determined amount of turnover, by arranging the checkout to send a pulse instead of the button 36 each time it crosses this amount. Conversely, if one wishes to authorize free order by the customer without restriction, it suffices to delete the upper part of the diagram in FIG. 6 as well as the device 46, or simply to interrupt the link 45.

All of the above also applies to the alternative embodiment of FIGS. 7 to 9, in which the relative effort of applying the drive roller to the stack of bags is obtained by a reverse arrangement. Indeed in this arrangement it is the support 51 of the bags 1 which is movable and pressed in the direction of the drive roller 21, which is in the fixed position.

For this, the support 51 is constituted by a flap articulated at its base at 52 on the fixed frame 53 constituting the frame of the device, while the drive roller, here formed of two rollers 21 spaced wedged on the same shaft 20 , is worn to pivot in the same frame 53, The geared motor 19 and the locating disc 22 are therefore also fixed, which simplifies the production.

Furthermore, the bundle of bags 1 is hooked to the support 51 in the inverted position, that is to say with the bottoms 4 of the bags at the upper part and the bundle attachment 11 in the lower position. For this, the return springs 54, hooked on the frame 53, act on the support 51 by means of a bar or a roller 55 carried by two rods 56 articulated at 57 on the frame 53.

In this way, by lifting the roller 55 and the rods 56 completely by hand, the support 51 is completely freed, which can tilt horizontally, or even in a downward position which facilitates the attachment of new bundles 11 of bags 1 on the hooks 15. Then the support 51 is raised by holding the bottoms of the bags 1 by hand until the stack of bags presses on the rollers 21. We then only have to fold down the link 56 so that the roller 55 exerts its action on the support 51.

To prevent the bag 1 driven n from wrapping around the rollers 21, the entire mechanical part is enclosed in an inner cover 58 leaving the rollers 21 to protrude only through windows 59. The whole device can also, like the previous, be enclosed in an outer cover, not shown, leading to an exit of the bags.

This latter variant is particularly advantageous insofar as it can be placed at the end of the supermarket checkout counter furniture, below the level of the recovery table, the bags then being ejected onto this table without the device being presents an annoying bulk.

Claims (6)

1. Automatic dispenser for plastic bags (1) joined in bundles by connecting tabs (9) partially separated from the bag by a breaking line (10) intended to constitute the central part of the upper opening (8) of the bag in leaving reserves remaining ensuring a determined resistance to tearing, characterized in that it comprises a support (13, 51), provided with a means (15) for hooking or suspending the bundle attachments (11) constituted by the union of the connecting lugs (9), and a frame (16, 17; 53) with an appropriate return means urging this frame towards the support, or vice versa, under a given application force, this bearing frame at least one drive roller (21) wedged on a shaft (20) journalling in the frame parallel to the rupture line (10) with its drive means in rotation on a lathe (19), this roller comprising on its periphery a drive arc (27) whose development corresponds substantially at the length between the contact generator (28) between the roller and the first bag and the rupture line (10) of this bag, this drive arc being coated with a substance capable of ensuring, under the force of application indicated, a driving force of the first bag greater than said determined resistance to tearing of the rupture line (10), and a sliding arc (29) complementary to the previous one and for which, under the same conditions , the driving force of the bag in contact is less than said resistance. 2. Dispenser according to claim 1, characterized in that it comprises two rollers (21, 31) arranged in tandem one behind the other and each provided with its drive means in synchronism and its means of application, being further joined together by at least one endless belt or strip (35). 3. Dispenser according to claim 2, characterized in that the synchronized drive of the second roller (31) by the first (21) is ensured by using for said belt, or at least for one of said belts (35), a belt notched or chain. 4. Dispenser according to one of the preceding claims, characterized in that the frame (53) is in a fixed position, that the support (51) is articulated at its base and carries the bundles of bags (1) in the inverted position, and that the return means (54, 55, 56) biases the support towards the frame and is arranged to allow the complete tilting of the support (51) in a position which facilitates its loading. 5. Dispenser according to one of the preceding claims, characterized in that it comprises a compensating shim (14) opposite the zone of action of the roller (s), so as to be able to use a large load of bags with side bellows. 6. Dispenser according to one of the preceding claims, characterized in that it comprises a counter (38) which can be initialized, then incremented by successive pulses by the cashier or the cash register, and which is decremented each time the engine has made a revolution under the effect of a command (37), this command being inhibited (46) when the counter (38) is returned to zero.

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