EP2844596B1 - Device for braking a sheet-like planar element and method for cleaning such a device - Google Patents

Description

The present invention relates to a device for braking the rear portion of a flat sheet-shaped member when the latter is moved by being pulled by its front portion.

The invention also relates to methods for cleaning such a braking device.

The invention finds a particularly advantageous, but not exclusive, application in the field of the manufacture of cardboard packaging.

In industry, the manufacture of a package from a cardboard sheet generally takes place in several stages. This is why the forming machines known in the state of the art are traditionally composed of several successive workstations, between which each sheet is moved sequentially. Concretely, each sheet is transported individually from one work station to another by pulling it by its front edge, leaving the rest of the sheet without particular maintenance.

In order for the sheet to retain a certain flatness when it decelerates when arriving at a work station, it is known to brake its rear portion during the introduction phase. Usually, it uses for this purpose a suction braking device which as its name suggests, performs its function retaining the rear portion of the sheet by suction, while allowing it to slide gradually as its front portion is driven in displacement. In practice, such a device for braking is generally in the form of a tablet which is provided with a plurality of holes through which a Venturi suction is generated, and which is implanted transversely at the entrance of the work station itself.

This type of suction braking device, however, has the disadvantage of clogging quickly. With the humidity of the air, cardboard dust, anti-caking powder and other residues have a natural tendency to accumulate in compact aggregates at the various orifices and channels of air circulation of the suction pad.

The solution that is usually used to remedy this problem is somehow to sweep the various ducts of the suction pad with a scraper shaped soft tongue. This tool has dimensions that are adapted to the lengths and sections of said ducts. In fact, the scraper is inserted through each suction hole, while the residues are discharged through the corresponding exhaust port.

The disadvantage of such a cleaning technique is that its implementation can operate only manually, which makes it particularly tedious. But the most serious is that this technique is sometimes simply impossible to implement, because the braking device is almost inaccessible. This is the case whenever the device in question is implanted in a particularly congested environment, such as for example at the entrance of a forming machine platen press.

Of course, attempts have been made to develop suction braking devices with a self-cleaning function. In this respect, the document EP1935820 discloses a device which conventionally comprises a plurality of suction holes connected to a plurality of exhaust ports by a network of air circulation channels, as well as a main pneumatic circuit for injecting pressurized air into the chamber. the most downstream portion of said network and towards the various exhaust ports. The assembly is arranged so that the circulation of this pulsed air flow generates by Venturi effect in the most upstream portion of the circulation channels, a depression which will in turn generate a flow of air sucked through all the suction holes. In any case, the cleaning of the various ducts is effected by blowing, by injecting pressurized air towards the suction holes by means of a secondary pneumatic circuit.

This type of braking device, however, has the disadvantage of integrating a self-cleaning system which leads to evacuate residues through the suction holes, and thus to reject them in the direction of the path of movement of the sheets. that is to say in the very heart of the shaping machine. This has the harmful consequences of defiling the sheets of cardboard, but also to foul the mechanisms that are present in the direct vicinity of the braking device.

Also, the technical problem to be solved by the object of the present invention is to propose a braking device for braking the rear portion of a flat sheet-shaped element when the latter is moved while being pulled by its front portion. comprising at least one suction hole which communicates with an exhaust port via a suction channel air circulation, as well as main means of pressurized air injection which are able to generate in each circulation channel and in the direction of the corresponding exhaust port, a main pulsed air flow capable of generating, by the venturi effect, an intake of braked air through the corresponding suction hole, a braking device which would make it possible to avoid the problems of the state of the art by offering a much greater self-cleaning capacity efficient.

The solution to the technical problem posed consists, according to the present invention, in that the braking device furthermore comprises secondary means for injecting pressurized air which are able to generate in each circulation channel and in the direction of the corresponding exhaust port, a secondary pulsed air stream capable of generating by venturi effect a flow of air sucked cleaning through the corresponding suction hole.

It is important to specify that the fact that the braking device according to the invention comprises at least one suction hole which communicates with an exhaust port via an air circulation channel means that said device may comprise a or more suction holes, one or more exhaust ports, all connected by a more or less complex network of air flow channels.

It may also be pointed out that, in the context of the invention, the main means of air injection are destined to operate in a substantially continuous manner, since braking is a function which must be ensured almost continuously in order to be in adequacy. with the high rates that are transported the leaves in modern processing machines. Conversely, the secondary means of air injection are for their part intended to be implemented more punctually, given that the cleaning is an operation that must be as short as possible so as not to penalize the performance of the processing machine to which the braking device is associated.

In any event, the invention as thus defined has the advantage of being free from the problems of soiling and fouling of the state of the art, insofar as the evacuation of residues performed integrally through the exhaust ports, which by definition are rotated in a direction substantially opposite to the path of movement of the sheets. Here indeed, and unlike its counterpart of the prior art initially described, there is absolutely no question of cleaning the suction holes by blowing, generating a pulsed air flow which is oriented from the inside towards the outside of the braking device, and rejecting the residues directly through the suction holes.

In a braking device according to the invention, the cleaning of the various suction holes is advantageously effected by suction, using a suction air flow which is oriented from the outside to the inside of the braking device, with tailings evacuation only through the exhaust ports. This sucked-in cleaning airflow is generated identically to the sucked-in braking air flow, that is to say indirectly because it also results from a depression created by the Venturi effect as a result of the flow of air. a flow of air pulsed through a pipe of non-constant section. The airflow However, the cleaning suction is distinguished from the intake air flow of braking by the fact that it is produced for a limited period of time and that it enjoys a relatively high pressure, with the aim that its action is similar to a kind of gunshot effect.

• La figure 1 illustre une machine de traitement dans laquelle est intégrée une station de découpage qui est équipée d'un dispositif de freinage conforme à l'invention.
• La figure 2 montre l'implantation du dispositif de freinage au sein de la station de découpage.
• La figure 3 est une en coupe transversale qui fait apparaître le dispositif de freinage en phase de fonctionnement.
• La figure 4 constitue une vue similaire à la figure 3, mais avec le dispositif de freinage en phase de nettoyage.

The present invention further relates to the features which will emerge from the following description, which should be considered in isolation or in all their possible technical combinations. This description, given by way of non-limiting example, is intended to better understand what the invention is and how it can be achieved. The description is further given with reference to the accompanying drawings in which:

• The figure 1 illustrates a processing machine in which is integrated a cutting station which is equipped with a braking device according to the invention.
• The figure 2 shows the implementation of the braking device within the cutting station.
• The figure 3 is a cross section which shows the braking device in the operating phase.
• The figure 4 is a view similar to the figure 3 but with the braking device in the cleaning phase.

For the sake of clarity, the same elements have been designated by identical references. Likewise, only the essential elements for understanding the invention have been represented, and this without regard to the scale and in a schematic manner.

The figure 1 represents a processing machine 100 whose main function is to cut out a succession of flat elements, in this case sheets of cardboard, to obtain poses to be subsequently folded and glued to make folding boxes. Such a cutting machine 100 being perfectly known from the state of the art, it will not be described in detail here, both in terms of its structure and its operation.

It will simply be recalled that it is conventionally composed of several work stations 110, 120, 130, 140, 150, 160 which are juxtaposed to form a unitary unit capable of processing a succession of sheets. Thus, there is a feeder 110 responsible for feeding the sheet-fed machine, then a margin table 120 on which the sheets are tabled before being accurately positioned individually, and a station cutting 130 which performs its function via a platen press 131. There is then the presence of an ejection station 140 for removing the waste that is directly produced during the cutting of the leaves, a receiving station 150 with separation of poses whose role is to break the attachment points that unite the poses together to separate them and then repackage them in piles to make them directly usable in a folder-gluer, and finally an evacuation station 160 where the waste is evacuated. Transport means 170 are naturally provided for moving each sheet individually from the output of the margin table 120 to the receiving station 150 by pulling it by its front edge. In a very conventional manner, these means of transport 170 use a series of gripper bars 171 which are mounted to move in transverse translation, by means of two gear trains. chains 172 arranged laterally on each side of the cutting machine 100.

The figure 2 shows more precisely that the cutting station 130 is equipped with a platen press 131 in which the cutting of the sheets is effected between an upper platen 132 which is static, and a lower platen 133 which is mounted to move in motion according to a movement vertical back and forth. It is also observed that the cutting station 130 includes a braking device 1 which is responsible for braking by suction the quarry portion of each sheet when the latter enters the platen press 131 being pulled via its front edge by a bar clamps 171. The combined action of pulling and braking then advantageously makes it possible to maintain the sheet in a perfectly extended position during the entire deceleration phase.

In this particular embodiment, chosen solely by way of example, the braking device 1 is in the form of a suction pad 2 which is implanted transversely to the inlet of the platen press 131, underneath it. but as close to the path of movement of the leaves 134 in order to be able to act on the underside of the latter.

As can be seen from the Figures 3 and 4 , the braking device 1 is first provided with at least one suction hole 10 which opens at the upper surface of the tablet 2, and which communicates with an exhaust port 30 via a circulation channel of 20, both formed in the lower part of said tablet 2. But the braking device 1 is also provided with main means for injecting pressurized air 40 which are able to generate in each circulation channel 20, a forced air flow main (arrow f1) which is directed to the corresponding exhaust port 30 (arrow f2). The assembly is arranged so that the circulation of this main pulsed air flow generates, by venturi effect, a suction airflow braking (arrow f3) through each suction hole 10.

The braking device 1 has a self-cleaning capability. For this, and in accordance with the object of the present invention, it further comprises secondary means for injecting pressurized air 50 which are able to generate in each circulation channel 20 a secondary pulsed air stream ( arrow f4) which is directed to the corresponding exhaust port 30 (arrow f5). The assembly is here designed so that the circulation of this secondary pulsed air flow generates, by venturi effect, a suction air flow cleaning (arrow f6) through the suction each 10.

In this exemplary embodiment, the main injection means 40 are concretely provided with a source of compressed air 41 which supplies an air supply line 42 formed longitudinally through the suction pad 2. air supply 42 communicates with a plurality of air supply channels 43 which open respectively into the various air circulation channels 20.

Similarly, the secondary injection means 50 are in turn provided with a source of compressed air 51 which supplies an air supply line 52 arranged longitudinally through the suction pad 2. air supply 52 communicates with a plurality of air supply channels 53 which open respectively into the various air circulation channels 20.

In practice, the sucked air cleaning flow serves to detach the residues that are present in each suction hole 10, and then transport them to the associated air circulation channel. Here, it is the secondary pulsed air flow that takes the relay to convey them to the corresponding exhaust port 30. Concomitantly, this same secondary forced air flow is used to remove the residues that have accumulated along the air circulation channel 20, and to evacuate them through the exhaust port 30.

According to a feature of the invention, the secondary injection means 50 are capable of generating a secondary pulsed air flow temporarily.

Preferably, the secondary injection means 50 are able to generate a secondary pulsed air flow for a time lapse of between 0.5 and 2 seconds.

According to another particularity of the invention, the secondary injection means 50 are able to generate a secondary pulsed air flow whose pressure is substantially greater than that of the main pulsed air flow, and consequently to generate a flow of sucked cleaning air whose pressure is substantially greater than that of the sucked airflow of braking.

Preferably, the secondary injection means () are able to generate a secondary pulsed air flow whose pressure is between 8 and 12 bar.

Of course, the invention also relates to any workstation intended to be integrated in a workstation of flat sheet-shaped elements, and comprising at least one braking device 1 as previously described. One thinks for example of a cutting station 130 as in the particular embodiment chosen to illustrate the invention, but also to a waste ejection station 140 or to a receiving station 150.

But even more generally, the invention is furthermore related to any processing machine of a succession of flat elements in the form of sheets, having at least one such braking device 1. cutting machine as in the embodiment of the Figures 1 to 4 , or to a printing machine by stamping metallized strips.

The invention finally relates to methods for cleaning any suction braking device 1 as previously described.

• désactiver si nécessaire les moyens principaux d'injection 40,
• activer temporairement les moyens secondaires d'injection 50.

Thus, a first cleaning method is characterized in that it comprises the steps of:

• disable, if necessary, the main injection means 40,
• temporarily activate the secondary means of injection 50.

In this first cleaning method, the main injection means 40 and the secondary injection means 50 are dedicated to operate alternately. This means that the main injection means 40 are exclusively dedicated to the braking function, while only the secondary injection means 50 participate in the cleaning function.

Particularly advantageously, prior to the deactivation step of the main injection means 40, the first cleaning method may be provided with an additional step of controlling the activation state of said main injection means 40.

According to another advantageous characteristic, after the temporary activation step of the secondary injection means 50, the first cleaning method may be provided with an additional step of reactivating the main injection means 40.

A second cleaning method is remarkable in that it comprises a step of temporarily activating the main injection means 40 and the secondary injection means 50 simultaneously.

In this second cleaning method, the braking function remains ensured by only the main injection means 40, while the cleaning function is filled by the combined action of the main injection means 40 and the secondary means of injection. injection 50.

Other features of the invention are applicable regardless of the cleaning method considered.

Thus, the activation of the secondary injection means 50 is preferably carried out for a period of time of between 0.5 and 2 seconds.

Likewise, the activation of the secondary injection means 50 is preferably performed with a secondary pulsed air flow pressure, which is between 8 and 12 bar.

Particularly advantageously, the cleaning process is carried out periodically. The objective here is to exercise a preventive action to avoid any risk of clogging the ducts. However, it is understood that if this implementation is regular, its periodicity can vary from one to braking device to another. In practice, this periodicity will generally be a function of the quality of the treated sheets, the nature of the mechanical work performed in the station, the manner in which the individual transport of each sheet takes place.

• interrompre le transport des objets plats en amont du dispositif de freinage 1,
• contrôler la présence d'objet plat à proximité directe du dispositif de freinage 1,
• autoriser la mise en oeuvre du procédé de nettoyage si aucun objet plat n'est présent en regard dudit dispositif de freinage 1.

According to another advantageous characteristic, prior to its implementation, the cleaning method comprises the steps of:

• interrupt the transport of the flat objects upstream of the braking device 1,
• check the presence of flat objects in the direct vicinity of the braking device 1,
• authorize the implementation of the cleaning process if no flat object is present opposite said braking device 1.

Claims (15)

1. Braking device (1) for braking the rear portion of a flat element in sheet form when said latter is displaced by being pulled by means of its front portion, said braking device comprising at least one suction hole (10) which communicates with an exhaust orifice (30) via an air circulation duct (20), as well as principal compressed air injection means (40) which, in each circulation duct (20) and in the direction of the corresponding exhaust orifice (30), are able to generate a principal pulsed air flow capable, by means of the Venturi effect, of generating a braking suction air flow through the corresponding suction hole (10), characterized in that said braking device furthermore comprises secondary compressed air injection means (50) which are suitable for generating, in each circulation duct (20) and in the direction of the corresponding exhaust orifice (30), a secondary pulsed air flow capable, by means of the Venturi effect, of generating a cleaning suction air flow through the corresponding suction hole (10).
2. Braking device (1) according to Claim 1, characterized in that the secondary injection means (50) are suitable for generating a secondary pulsed air flow in a temporary manner.
3. Braking device (1) according to Claim 2, characterized in that the secondary injection means (50) are suitable for generating a secondary pulsed air flow during a lapse of time of between 0.5 and 2 seconds inclusive.
4. Braking device (1) according to one of Claims 1 to 3, characterized in that the secondary injection means (50) are suitable for generating a secondary pulsed air flow where the pressure is appreciably superior to that of the principal pulsed air flow, and, as a consequence, are suitable for generating a cleaning suction air flow where the pressure is appreciably superior to that of the braking suction air flow.
5. Braking device (1) according to Claim 4, characterized in that the secondary injection means (50) are suitable for generating a secondary pulsed air flow where the pressure is between 8 and 12 bar inclusive.
6. Operating station (130) for a succession of flat elements in sheet form, characterized in that said operating station comprises at least one braking device (1) according to any one of the preceding claims.
7. Processing machine (100) for a succession of flat elements in sheet form, characterized in that said processing machine comprises at least one braking device (1) according to any one of Claims 1 to 5.
8. Method for cleaning a braking device by suction (1) in accordance with any one of Claims 1 to 5, characterized in that said method comprises the stages consisting in:

   - deactivating the principal injection means (40) if necessary,

   - temporarily activating the secondary injection means (50).
9. Method for cleaning according to Claim 8, characterized in that said method includes a stage consisting in controlling the activation state of said principal injection means (40) prior to the stage of deactivating the principal injection means (40).
10. Method for cleaning according to either of Claims 8 and 9, characterized in that said method includes a stage consisting in reactivating the principal injection means (40) after the stage of temporarily activating the secondary injection means (50).
11. Method for cleaning a braking device by means of suction (1) in accordance with any one of Claims 1 to 5, characterized in that said method comprises a stage consisting in temporarily activating the principal injection means (40) and the secondary injection means (50) in a simultaneous manner.
12. Method for cleaning according to any one of Claims 8 to 11, characterized in that activation of the secondary injection means (50) takes place during a lapse of time of between 0.5 and 2 seconds inclusive.
13. Method for cleaning according to any one of Claims 8 to 12, characterized in that activation of the secondary injection means (50) takes place at a secondary pulsed air flow pressure which is between 8 and 12 bar inclusive.
14. Method for cleaning according to any one of Claims 8 to 13, characterized in that said method is implemented in a periodic manner.
15. Method for cleaning according to any one of Claims 8 to 14, characterized in that prior to its implementation, said method comprises the stages consisting in:

    - interrupting the conveyance of flat objects upstream of the braking device (1),

    - checking the presence of flat objects in the direct vicinity of the braking device (1),

    - authorizing the implementation of the method of cleaning if no flat object is present in the vicinity of said braking device (1).

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