EP0035428B1 - Device for feeding sheets to a processing machine - Google Patents

Description

The present invention relates to a device "for supplying sheets to a processing machine, such as a feeder intended to equip a machine for shaping corrugated boxes.

Devices of this type are known, such as for example that described in French patent No. 1,568,091, which do not include a margin table. The cardboard sheets are then extracted one by one from the magazine by the bottom thereof, on which they rest using two supports, a front and a rear, of small longitudinal dimensions. The extraction of each sheet is carried out using a rear suction box having a cyclic movement in the vertical plane giving it successively an upward movement associated with a backward movement then a downward movement associated with a forward movement . The sheets thus extracted from the magazine are then driven forward using a pusher. Such devices are complex, difficult to implement, ill-suited to rapid format changes, and ill-suited, for lack of a margin table, to operate with large formats due to the flexing of the plates. They are generally preferred for simpler and more flexible devices of use comprising a margin table constituting the bottom of the magazine and provided with margin knives situated at the height of the front edge of the packet of sheets.

Also known are suction feeders, such as that described in United States patent No. 3226108, in which the sheet to be fed is made integral with a box on which a vacuum is applied cyclically, said box being also animated with a longitudinal back and forth movement in conjunction with a drive of the sheet by rollers placed directly downstream of this box. These devices allow the sheets to pass under the margin knives located downstream of the feeder without the risk of jamming. On the other hand, it happens with such devices, in particular when treating thin, therefore light sheets, that these are put across, or "delta", the lateral edges remaining behind the upstream front of the sheet. , which gives a bad introduction. Conversely, in the case of the treatment of thick, therefore rather heavy, sheets, these have difficulty in being driven exactly to the register, which disturbs the operation of the machine.

Finally, devices are known, such as that described in the applicant's French patent published under the number 2 239 881, in which the sheet to be fed is pushed by a claw ruler animated with a longitudinal movement back and forth. , the sheet being moreover subjected to a low vacuum which presses it and straightens it on a flat structure called the margin table. This type of device provides better thrust of the sheet than the devices mentioned above, but the passage of the latter under the margin knives is difficult, which entails risks of jamming and therefore destruction of sheets.

The feeder according to the invention allows, while not having the drawbacks of the previous devices, to have margin security under the knives inherent in suction feeders of the prior art while having perfect security in the register, whatever whatever the thickness of the carton. It includes a flat and substantially horizontal margin table, a front stop or "margin knife" allowing one sheet to pass at a time, a rear pusher animated by a back and forth movement longitudinal and constituted by a ruler margin or a set of aligned claws, having in all cases a front heel-shaped machining to receive the rear edge of the sheet to be pushed, a rear stopper intended to support the rear of the pack of sheets and placed above of said pusher, and is characterized in that it further comprises one or more suction boxes situated (s) at the front and under said margin table and animated (s) with a longitudinal reciprocating movement by via a transmission linked to that moving said pusher so that their strokes are substantially in agreement during at least a first part of the forward stroke of said pusher corresponding to at least the longitudinal distance of sup carrying of the package by said rear stop, the said box or boxes being connected to a device which puts them in depression during said match of forward strokes and then releasing said depression.

• la figure 1 est une vue d'ensemble latérale et schématique du margeur de l'invention,
• la figure 2 est un graphique représentatif des courses du poussoir et du caisson aspirant.

The invention will be better understood using the following description of an exemplary embodiment of a feeder intended to equip a machine for shaping corrugated boxes, with reference to the accompanying drawings in which:

• FIG. 1 is a side and schematic overview of the feeder of the invention,
• Figure 2 is a representative graph of the strokes of the pusher and the suction box.

• - un magasin 1 pour le paquet de feuilles 2 à distribuer,
• - une structure 4 plate et substantiellement horizontale appelée « table de marge dont une partie englobant partiellement sa moitié amont est mise en dépression faible par un caisson 5 relié à un ventilateur comme dans le cas du brevet précité.

Referring to FIG. 1, the feeder of the invention comprises the following conventional elements of known devices, such as for example that described in the French patent published under the number 2 239 881:

• - a magazine 1 for the package of sheets 2 to be distributed,
• - A flat and substantially horizontal structure 4 called "margin table, a part of which partially encompasses its upstream half is placed in low vacuum by a box 5 connected to a fan as in the case of the aforementioned patent.

• - une butée frontale 3, appelée « couteau •, positionnée en hauteur par rapport à la table 4 de manière à ne laisser passer qu'une seule feuille vers les rouleaux entraîneurs 7,
• - un poussoir constitué par une règle de marge 8 présentant de manière usuelle un talon avant 9 destiné à recevoir le bord arrière de chaque feuille.

In the case under consideration, the casing 5 extends in width over approximately two thirds of the table 4 and in length over approximately three quarters of the latter:

• - a front stop 3, called “knife •, positioned high with respect to the table 4 so as to allow only one sheet to pass towards the driving rollers 7,
• - A pusher constituted by a margin rule 8 usually having a front heel 9 intended to receive the rear edge of each sheet.

• - une butée arrière fixe 10 destinée au support de la partie arrière du paquet 2, placée immédiatement au-dessus de la règle de la marge 8, et munie d'une avancée 11 de longueur L
• - un caisson aspirant mobile 12 semblable à celui décrit dans le brevet U.S. N° 3 226 108, placé sous l'avant de la table de marge 4, et relié à une pompe à vide par l'intermédiaire d'une électrovanne 13 et d'une canalisation 14 ; comme dans le cas du brevet américain précité, le caisson 12 peut être animé d'un mouvement de va-et-vient longitudinal autour de la butée frontale 3, sa position de recul maximal étant celle figurée en traits pleins et sa position d'avancée maximale étant celle figurée en pointillés sur le dessin.

Furthermore, the feeder of the invention further comprises:

• a fixed rear stop 10 intended to support the rear part of the package 2, placed immediately above the margin rule 8, and provided with a projection 11 of length L
• - A mobile suction box 12 similar to that described in US Patent No. 3,226,108, placed under the front of the margin table 4, and connected to a vacuum pump via a solenoid valve 13 and d 'a line 14; as in the case of the aforementioned American patent, the box 12 can be moved in a longitudinal back-and-forth movement around the front stop 3, its position of maximum recoil being that shown in solid lines and its forward position maximum being that shown in dotted lines on the drawing.

According to the invention, the box 12 and the rule 8 are kinematically linked to each other so that their respective longitudinal reciprocating strokes are conjugated according to the graph in Figure 2 where the stroke angle 0 is plotted on the abscissa, the stroke distance c on the ordinate, the curve relating to the box 12 being drawn in a strong line and that relating to the rule 8 in a thin line.

As can be seen in the graph, where zero is the extreme retracted position of the two elements, the strokes are at the start substantially in agreement over a length C greater than the length L of the projection 11 of the stop 10; then the rule 8 continues its course while the box 12 remains substantially stationary, the latter going backwards during the last phase of the backward return of the rule 8.

Furthermore, still in accordance with the invention, the solenoid valve is controlled. 13, for example by a conventional control with photocells sensitive to the longitudinal position of the box 12, so that vacuum is applied to the box. 12, during the first part C of the race corresponding to its advance, then be released thereafter.

As can be seen in FIG. 1, the respective cycles according to the graph in FIG. 2 are carried out using conventional means with a set of connecting rods and connecting rod-crank as follows:

A crank-rod assembly (15, 16) kinematically linked to the driving rollers 7 communicates an oscillating movement to a shaft 17 carrying a lever 18. The lever 18 communicates its oscillation movement on the one hand to the box 12 by 1 'intermediate a first set of connecting rods (19, 20), and secondly to rule 8 via a second set of connecting rods (21, 22), these sets of connecting rods being arranged, for example as in the figure, so as to communicate to the box 12 and to the rule 8 conjugate longitudinal movements in accordance with the graph of FIG. 2.

• La position de départ étant celle représentée sur la figure 1, la règle 8 et le caisson 12 sont en position reculée maximale, la partie arrière des feuilles étant surélevée et supportée par l'avancée 11 de la butée 10, le bord avant du caisson 12 étant sensiblement à la verticale du couteau 3 et le talon 9 de la règle 8 légèrement en arrière de la verticale du bord arrière de la feuille inférieure 23 à introduire.

The operation of the device which has just been described is as follows:

• The starting position being that shown in FIG. 1, the rule 8 and the box 12 are in the maximum retracted position, the rear part of the sheets being raised and supported by the projection 11 of the stop 10, the front edge of the box 12 being substantially vertical to the knife 3 and the heel 9 of the rule 8 slightly behind the vertical of the rear edge of the lower sheet 23 to be introduced.

The vacuum being applied to the box 12 by opening the solenoid valve 13, the latter then drives the lower sheet 23 of the package 2 forward. When the sheet 23 has covered its support distance by the projection 11, at most equal at L, it falls on the table 4 coming to be pressed against it thanks to the light suction due to the box 5, its rear edge coming to be positioned against the heel 9 of thrust from there rule 8 which has meanwhile advanced in accordance with the caisson 12. When the caisson 12 and the rule 8 have traversed the concordance stroke C, the vacuum on the caisson 12 is released so that its action on the sheet 23 is stopped, but on the other hand rule 8 continues its advance by always pushing the sheet 23 until finally introducing it between the rollers 7, which then continue its drive, and turning back according to the graph in FIG. 2.

To stop the introduction without stopping the whole machine, it suffices, by action on the solenoid valve 13, to completely release the vacuum on the box 12. The latter, despite its back-and-forth movement cannot then no longer drive the lower sheet 23 which remains in position on the projection 11, the rule 8 also having no action on the latter, since it then passes continuously below it.

It will be noted that with the device of the invention, the pushing heel 9 can have a height greater than the thickness of a sheet, so that it is thus possible to have the maximum pushing efficiency even with thin sheets, especially without damaging the rear edge. Furthermore, in the case of a lower sheet 23 which would be tiled or curved, therefore unable to pass under the knife 3 which, with the prior devices, would cause a cardboard jam, the box 12 would then only suck air so that the back of the tiled sheet 23 would remain on the projection 11 and the introduction would be stopped without loss of material. Finally, in the event of a register defect, the sheet having for example skated on the box 12, the device of the invention makes it possible to recover this defect, because the sheet will be readjusted in the next cycle on the heel of the rule, thus regaining its good margin position.

Claims (2)

1. Device for feeding a processing machine with sheets, of the type comprising a flat and substantially horizontal feed board (4), a front stop (3), or « feed knife », making it possible to allow one sheet to pass through at a time, a rear push-rod (8) driven with a longitudinal reciprocating motion, and a rear stop (10) intended for supporting the rear of the stack of sheets (2) and placed above the said push-rod, characterised in that It also comprises one or more suction boxes (12) located in front and under the said feed table (4) and driven with a longitudinal reciprocating motion by means of a transmission (19, 20) linked to the transmission (21, 22), which moves the said push-rod (8), so that their strokes substantially match during at least a first part (c) of the forward stroke of the said push-rod, corresponding at least to the longitudinal distance (L) of support of the stack (2) by the said rear stop (11, 10), the said box or boxes (12) being connected to a device (13, 14) creating a partial vacuum therein during the said matching (c) of forward strokes, and then releasing the said partial vacuum.

2. Device according to Claim 1, characterised in that the said box or boxes (12) is/are linked to the said push-rod (8) by a kinematic lever-linkage (18) and a set of connecting rods (20, 19 and 21, 22), and also to the drive rollers (7) located in front of the said device by means of a crank- connecting rod linkage (16, 15).

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