EP0620088B1 - Apparatus for cutting paper - Google Patents

Description

The present invention relates to the cutting one by one of semi-rigid sheets, in particular of cardboard and particularly of corrugated cardboard. More specifically, it relates to an improved device, specially adapted to perform this cutting at optimized rates according to the format of the sheet to be cut, and the kinematics of the machine.

The cutting of a semi-rigid sheet, in particular from corrugated cardboard, is carried out on conventional cutters using a cutting tool and a support surface. The cutting tool comprises blades or threads perpendicular to the bearing surface when the sheet is pressed between it and the cutting tool so that the threads pass through the sheet and make the corresponding cut.

In a first type of cutter, the cutting tool is positioned flat on a tool-holder plate and the bearing surface is a flat surface. In this case, the cutting is carried out by applying the bearing surface against the tool-holder plate on which the sheet to be cut has been positioned. The pressure which must be brought into play in a cutting machine of this type is very high, being able to go up to several thousand kilonewton.

In a second type of cutter, the cutting tool is mounted on the periphery of a cylinder and the bearing surface is itself a cylindrical surface. The cutting is carried out by introducing the sheet between the two cylinders driven in rotation. The pressure involved is lower because the cutting is done in a linear fashion along the line of tangency between the two cylinders. However, shaping the cutting tool so that it is adapted to the exterior surface of a cylinder is very delicate. In addition, problems can arise when the sheet to be cut has a large thickness because the cutting threads being mounted radially, there is a difference in peripheral distance between the part upper and lower part of two adjacent nets.

According to a third type of cutter, known for example from document US Pat. No. 3,765,286, the cutting tool is mounted on a tool-holding plate while the bearing surface is a cylindrical surface. This particular arrangement overcomes the drawbacks of the first two types. However, the tool-holder plate must, in this case, be driven in an alternating back-and-forth movement making it possible to move each sheet one after the other under the support cylinder from a feed position of the sheet to be cut to a position for discharging the cut sheet. In addition, since the sheet to be cut comes from a previous station, either a printer or a feeder, the cutter also includes feeding means making it possible to precisely introduce said sheet on the cutting tool during movement of that -this under the support cylinder. Indeed it is necessary on the one hand that the sheet is very precisely positioned on the cutting tool and on the other hand that there is no possible sliding of the sheet during its passage under the cylinder. support. In document FR.2.527.573, these feeding means consist of two sheet transport systems. The first, known as the transfer case, receives the sheet from the upstream machine, which can be a feeder or a printer for example. It has a constant linear speed equal to that of these machines. The second, known as the launching box, receives the sheet from the transfer box and introduces it between the tool holder plate and the support cylinder. At the start, it therefore has a speed equal to that of the transfer case, then it accelerates the sheet in order to give it a speed equal to that of the support cylinder according to the same acceleration law as the tool-holder plate.

In cutters of the third type, the support cylinder has a coating which is either made of steel or of a flexible material of the polyurethane type. The use of one or the other of these coatings depends on the quality which one wishes to obtain for cutting. The cut is more straightforward when the coating is made of steel but this results in a much faster wear of the cutting threads. This wear can quickly cause the formation of what is called angel hair, that is to say strips of very small width, for example of the order of a tenth of a millimeter, corresponding to crushing. of the sheet by the worn cutting blade. The use of a steel-coated support cylinder also requires more precise adjustment of the positioning of the cylinder relative to the tool-holder plate.

The use of a coating of a flexible material for the support cylinder makes it possible to avoid the formation of angel hair and the precision of the adjustment. However, the quality of the cut is less good, the cut edges being less clear, due to the relative penetration of the cutting threads in the coating of the support cylinder.

In conventional installations, the quality of cutting depends on the type of cylinder which equips the cutting machine. The user therefore does not have the possibility of determining his cutting quality according to the batch he has to process.

• a) un châssis et des moyens supports qui sont aptes à recevoir comme surface d'appui soit un revêtement en acier d'épaisseur d ₁, soit un revêtement en un matériau souple d'épaisseur d ₂,
• b) des moyens de déplacement en hauteur du cylindre d'appui entre deux positions de réglage pour la découpe, la première correspondant à l'épaisseur d ₁ et la seconde à l'épaisseur d ₂,
• c) au moins un premier moteur indépendant à asservissement électronique à double sens de rotation, entraînant le plateau porte-outil dans un mouvement alternatif et un second moteur indépendant à asservissement électronique entraînant le caisson de lancement,
• d) et des moyens de contrôle de la rotation du cylindre d'appui; de plus lesdits premier et second moteurs les moyens de contrôle et les moyens de déplacement en hauteur du cylindre d'appui sont connectés à un circuit électronique de commandes avec des moyens d'entrée de paramètres de fonctionnement dont au moins la valeur de l'épaisseur d ₁, d ₂ du revêtement;

enfin ledit circuit est programmé en sorte de commander les moyens de déplacement en hauteur du cylindre d'appui en fonction de la valeur du paramètre d'épaisseur et de commander les premier et second moteurs pour que la vitesse linéaire du caisson de lancement et celle du plateau porte-outil soient égales à la vitesse linéaire périphérique du cylindre d'appui au moment où l'outil de découpe présente la feuille sous le cylindre d'appui , et pour que la vitesse linéaire du plateau porte-outil soit égale à la vitesse linéaire périphérique du cylindre d'appui, tant que l'outil de découpe 16 se trouve en contact avec ledit cylindre d'appui.The first object of the invention is to provide a device for cutting which overcomes the aforementioned drawback. It is a device for cutting semi-rigid sheets one by one, in particular from corrugated cardboard, which comprises a cutting tool fixed on a tool-holding plate and a support cylinder, the tool-holding plate being driven by a reciprocating movement back and forth between a first position where the cutting tool is located in front of the support cylinder and a second position where it is located behind the support cylinder, the sheet being introduced thanks to launching means above the cutting tool when the tool-holder plate has left the first position, being cut during its passage under the support cylinder, then being removed from the cutting tool when the plate tool holder is in the second position. Typically the support cylinder comprises:

• a) a frame and support means which are capable of receiving as support surface either a coating of steel of thickness d ₁ , or a coating in a flexible material of thickness d ₂ ,
• b) means for moving the support cylinder in height between two adjustment positions for cutting, the first corresponding to the thickness d ₁ and the second to the thickness d ₂ ,
• c) at least a first independent motor with electronic servo-control with two directions of rotation, driving the tool-holder plate in a reciprocating motion and a second independent motor with electronic servo-control driving the launching box,
• d) and means for controlling the rotation of the support cylinder; in addition, said first and second motors, the control means and the means for displacing the support cylinder in height are connected to an electronic control circuit with means for entering operating parameters, at least the value of the thickness. d ₁ , d ₂ of the coating;

finally said circuit is programmed so as to control the means of displacement in height of the support cylinder as a function of the value of the thickness parameter and to control the first and second motors so that the linear speed of the launching box and that of the tool-holder plate are equal to the peripheral linear speed of the support cylinder when the cutting tool presents the sheet under the support cylinder, and so that the linear speed of the tool-holder plate is equal to the speed peripheral linear of the support cylinder, as long as the cutting tool 16 is in contact with said support cylinder.

Thus, it becomes possible to interchange the coating of the support cylinder between two lots of cuts. Following this change, the operator need only enter the parameter corresponding to the thickness of the coating chosen in the electronic circuit. In doing so, the support cylinder is automatically placed in the predefined adjustment position and the displacement speeds of the launching box and the tool-holder plate are determined so as to take account of the outside diameter of the coating, which conditions the peripheral linear speed. of the support cylinder, this must always be equal to the linear speed of the plate tool holder and cutting sheet.
Preferably the length l of the cutting tool is an operating parameter of the electronic control circuit and the latter is programmed so that the amplitude of the reciprocating movement of the tool-holder plate is a function of this parameter l .

Thanks to the invention it is therefore possible to reduce the stroke of the tool-holder plate when the format of the sheet to be cut and therefore the length l of the cutting tool are less than the maximum dimension L provided by the manufacturer. This correlatively increases the production rate of the cutter or, keeping the same rate, reduces the electrical power consumed.

In the usual operation of cutters of the third type, there sometimes appear to be some problems when ejecting the cut sheets. The cutting tool includes a system allowing the sheet to be held in place during cutting and then ejecting it when the tool-holding plate is in the second position. This system works using flexible tubing which functions as suction cups during the forward movement and which functions as ejection tubing by sending compressed air when the tool-holder plate is in the second position. The cut sheet, which is ejected, is taken up by a discharge device.

The difficulties encountered are manifested by time lags between the ejection and the resumption of the sheets cut by the evacuation system. This results in poor placement of the sheets to be cut on the recovery system and therefore irregularities in their subsequent stacking.

It is another object of the invention to propose a device for cutting which overcomes the aforementioned drawback. Typically, the electronic control circuit is programmed so that the tool-holder plate can be stopped in its second position for a determined time t which is introduced as an operating parameter in the means of entry.

Thus the ejection operations, by the action of compressed air in the pipes of the cutting tool and of recovery by the evacuation system can take place concomitantly during the downtime t . It is noted that such a stop was impossible in conventional cutters.

Preferably the downtime is of the order of a few hundredths of a second.

Another difficulty encountered in cutters of the third type resides in the premature wear of certain members when the cutter turns idle, that is to say when there is no sheet on the cutting tool during displacement from the first to the second position of the tool-holder plate. In fact, given that the cutting forces cause a slight deformation of the support cylinder and the tool-holder plate, it is usual to compensate for this deformation by ensuring that the space between the tool-holder plate and the cylinder d support is slightly less than the height of the cutting blades. Therefore, when the cutter turns empty, the force generated to cause this deformation is transmitted only to the cutting blades, which causes their wear. In the case where the support cylinder is provided with a flexible coating, it is this which would suffer premature wear due to the action of the cutting blades.

It is another object of the invention to propose a device for cutting which overcomes this drawback.

Typically it includes a sheet presence sensor, disposed in front of the support cylinder, and connected to the electronic control circuit; moreover, it is programmed to maintain the tool-holder plate in its first position in the event that the sensor does not detect a sheet.

Thus, thanks to this particular arrangement, the cutting tool does not come into contact with the support cylinder when no sheet is detected by the sensor in front of said cylinder.

Another difficulty can be encountered in the cutters of the third type when the sheet to be cut, coming from a previous station, thanks to the launching means, is either early or late compared to its normal positioning when entering the cutter. Such a shift is found when positioning the sheet on the cutting tool: the cutting is not positioned correctly relative to the sheet, which can cause customer refusals.

It is another object of the invention to propose a device which overcomes the aforementioned drawback.

Typically, the device comprises a system for locating a position of a predetermined element of the sheet, which is located upstream of the support cylinder of the sheet and equipped with an independent motor with electronic servo-control which is, as is said tracking system, connected to the electronic control circuit; moreover the latter is programmed so that the difference which is noted between the theoretical position and the actual position of the edge of the sheet, detected by the tracking system, is corrected by a correlative variation in the drive of the motor equipping the means of launching.

Thus, thanks to this particular arrangement, the sheet which is either ahead or behind when it leaves the previous station sees its feeding speed reduced or accelerated so that it is introduced onto the cutting tool very precisely in the required conditions. We therefore obtain an automatic correction of the positive or negative difference from the previous item.

According to a first variant, the predetermined element is the front or rear edge of the sheet; in this case the tracking system preferably consists of a position sensor.

According to a second variant, the predetermined element is a given printed area of the sheet; in this case the tracking system preferably consists of a camera, capable of detecting said printed area.

Preferably the means for moving in height are able to move the support cylinder between the low position - depending on the setting, depending on the parameter d ₁ or d ₂ - corresponding to the cutting position and a high position corresponding to the position d 'retraction; in this case the electronic control circuit is programmed so that the support cylinder is in the low position during the forward movement of the tool holder plate, from the first to the second position, and is in the high position the rest of the time.

This arrangement is preferred when the support cylinder has over its entire periphery a flexible material, of the polyurethane type.

Another difficulty may arise when using cutters of the third type, for cutting multi-layered sheets. This term is used to designate sheets in which cuts must be made which, after removal of the cutting waste, leave independent portions of sheets in place. These independent sections are called poses. The difficulty encountered consists in the lack of stability of the stacks of poses at the output of the cutter. This is explained by the fact that their bearing surface is much smaller compared to the size of the starting sheet.

It is another object of the invention to propose a device for cutting which overcomes the drawback noted.

Typically, the electronic control circuit is programmed to periodically maintain the support cylinder in the high position during the forward movement of the tool holder plate, from the first to the second position, according to a frequency which is a parameter. operating, introduced into the input means of the electronic circuit.

By raising the support cylinder, the sheet which is driven on the tool-holder plate is not cut and is positioned on the stack already formed of the different poses. By inserting an uncut sheet in this way, spacers between the different stacks of poses, which helps to improve stabilization.

Cutters of the third type are most often integrated into complete installations comprising a feeder and possibly printers. In this case the cutter drive mechanism is only part of the entire drive mechanism of the complete installation. Therefore it is not currently possible to have in a facility a cutter that would not have been designed to work with the rest of the facility.

It is another object of the invention to propose a device for cutting which overcomes the aforementioned drawback.

Typically, the device which comprises, in a manner known from document FR.2.527.573, not only means for launching the sheet for its positioning on the cutting tool and its introduction under the support cylinder, but also means transfer bringing said sheet from the previous station to the launch means. Typically, the transfer means are equipped with an independent electronic servo motor which is connected to an electronic circuit. In addition, control means are mounted on the sheet movement members at the previous station, said control means being connected to said electronic circuit. The latter is programmed so that on the one hand the speed of the transfer means is constantly equal to the speed of the sheet leaving the displacement members of the previous station and on the other hand the launching means are controlled as a function of said speed. so that the sheet has the same speed as the peripheral linear speed of the support cylinder when it arrives on the cutting tool.

Thus the improved cutter of the invention can be arranged in an existing installation. The cutter receives the sheets at the linear speed which is imposed by the previous station without this affecting the desired rate of the cutter.

Finally, it is another object of the invention to propose a device for cutting in which the change of coating of the support cylinder can be done, automatically, without manual intervention.

Typically, the support cylinder is equipped with two types of coating simultaneously; the first support means capable of receiving the coating constituting the bearing surface during cutting consist of a curved sheet disposed in a first angular portion, at a distance R from the axis of rotation of the cylinder; the second support means capable of receiving the pending coating consist of a curved sheet disposed in a second angular portion, at a distance r from the axis of rotation of the cylinder; the device comprises displacement means able to radially move the two coatings of their respective support means and to angularly move them so as to interchange them.

Preferably, the coverings are secured to each end of the chassis thanks to a plurality of rods terminated by rollers; the end posts of the chassis comprise a concentric rail forming a running track for said rollers; the radial displacement means consist of jacks whose rods are terminated by slides which are two superposed and concentric sections of said rail, the rollers being housed in the sections closest to the axis of rotation of the support cylinder, said cylinders being actuable between a first position where, the rod being retracted, the coatings are applied to their respective support sheets and the sections comprising the rollers retracted under the track while the rails of the sections without rollers are in alignment with the rails of the uprights of the chassis and a second position where, the rods being removed, the coverings are separated from their support sheets and the rails of the sections with rollers are aligned with the rails of the uprights of the chassis. Thus the rollers can move angularly along the raceways, while the coatings are no longer applied to the support sheets. Thanks to this double displacement, it is therefore possible to bring the second coating on hold from the second support means until it takes the place of the first coating on the first support means.

The angular displacement means can consist of an independent motor with electronic servo drive in rotation the support cylinder, and in temporary blocking means of the coatings. To change the coating, it suffices - after the radial displacement in height of the support sheets - to lock the coatings in position so as to keep them fixed relative to the chassis, then rotate the cylinder for example 180 °, the rollers turning on themselves in the raceway.

Preferably the aforementioned independent motor, the locking means and the jacks are connected to the electronic control circuit, and the latter being programmed so as to successively control first the output of the rods of the jacks, then the blocking of the linings, then the rotation of the cylinder, then the release of the coverings and finally the re-entry of the rods of the jacks.

• La figure 1 est une vue schématique d'une installation incluant la découpeuse perfectionnée,
• Les figures 2A à D montrent les différentes étapes de fonctionnement de la découpeuse selon une représentation partielle de la figure 1, la figure 2E montrant l'étape correspondant à la figure 2D avec une découpeuse classique.
• La figure 3 est une vue partielle de la découpeuse quand le plateau porte-outil est en position d'éjection de la feuille découpée.
• La figure 4 est une vue schématique de côté du cylindre d'appui à deux revêtements interchangeables.
• La figure 5 est une vue en coupe partielle du cylindre d'appui illustré à la figure 4 selon la ligne 5-5, et
• La figure 6 est la même représentation qu'à la figure 5 du cylindre d'appui mais le revêtement étant écarté de sa tôle support.

The present invention will be better understood on reading the description which will be given of an exemplary embodiment of an improved cutting machine with automatic operation, illustrated by the appended drawing in which:

• FIG. 1 is a schematic view of an installation including the improved cutting machine,
• Figures 2 A to D show the different stages of operation of the cutter according to a partial representation of Figure 1, Figure 2E showing the step corresponding to Figure 2D with a conventional cutter.
• Figure 3 is a partial view of the cutter when the tool holder plate is in the ejection position of the cut sheet.
• Figure 4 is a schematic side view of the support cylinder with two interchangeable covers.
• FIG. 5 is a partial section view of the support cylinder illustrated in FIG. 4 along the line 5-5, and
• Figure 6 is the same representation as in Figure 5 of the support cylinder but the coating being spaced from its support sheet.

The installation 1 shown in FIG. 1 is a printing and cutting installation one by one of sheets of corrugated cardboard. This installation 1 comprises from upstream to downstream in the direction of movement of the sheet successively a feeder 2, a printer 3, the cutter 4, a box for evacuation of cutting waste 5 and the stacking station and reception 6.

The cutter comprises a transfer box 7 and a launch box 8, a support cylinder 9, a tool holder plate 10, which is driven in an alternating movement back and forth according to arrow F for the forward movement and the arrow F 'for the return movement.

The tool-holder plate 10 has longitudinally racks not shown and its reciprocating movement is obtained by the rotation of toothed wheels meshing in said racks. Said toothed wheels are driven by at least one motor 11 with electronic servo-control, of the brushless type.

The waste evacuation box 5 comprises a suction channel 12 at the immediate outlet of the cylinder 9 and a poses conveyor 13, which is placed beyond the suction channel 12 and which consists of rollers 14 arranged transversely by relative to the direction of movement of the sheet and separated from each other by free spaces. In the casing 5 are provided suction means according to a first circuit opening onto the suction channel 12, said first circuit corresponding to the evacuation of the cutting waste 15, and a second suction circuit opening into the conveyor of poses 13. The rollers 14 are rotated by means not shown. This rotation, as will be explained further in the following description, allows the evacuation of the poses towards the reception and stacking station 6.

FIGS. 2A to 2D illustrate the different stages of the operation of the cutter 4 when the tool-holder plate 10 changes from its first front position (FIG. 2A) to its second rear position (FIG. 2D). On the tool-holder plate 1O is fixed a cutting tool 16. On this cutting tool 16 are vertically mounted cutting threads or blades 17 according to the configuration of the profile to be cut. This cutting tool 16 also includes tubing suction 18 and ejection bellows 19, which are distributed in each of the zones corresponding to a pose 2O. This term denotes each of the sheet portions which result from the cutting of the initial sheet.

When the tool holder plate 1O is in the first position, the most upstream of the cutter, it is located as well as the cutting tool 16 under the transfer box 7 and under the launch box 8. A sheet to be cut 21 has been fed from the previous station, for example the printer 3 in the example illustrated in FIG. 1. This sheet 21 is located astride the transfer box 7 and on the launching mat 8. It is obliquely directed towards the lower surface of the cylinder 9.

In the step illustrated in FIG. 2B, the tool-holder plate 10 has started to move in the direction of the arrow F, the sheet 21 has itself moved under the action of the launch box 8 and the cylinder 9 has itself rotated by a certain angle. All these movements have been synchronized so that the front edge 21a of the sheet 21 comes precisely be applied to the front edge 16a of the cutting tool 16 when said sheet comes into contact with the outer surface of cylinder 9 .

This first step between the first position illustrated in FIG. 2A and this intermediate position in FIG. 2B constitutes the step of launching the tool holder plate 1O. When it arrives in the position of FIG. 2B, the tool-holding plate 10 has to have acquired a speed V ₁ which must be equal to the linear speed of the external surface of the cylinder 9 which comes into contact with the sheet 21. The latter must also have acquired, thanks to the launching box 8, the same speed of movement V ₁ .

The tool-holder plate 1O must keep the same speed of movement V1 up to the position it has in FIG. 2C, that is to say when the rear edge 16b of the cutting tool 16 leaves the outer surface of cylinder 9.

The last step of the forward movement of the tool-holder plate 10 ends with the second position illustrated in FIG. 2D in which the cutting tool 16 is placed under the rollers 14 of the laying conveyor 13 after having passed under the channel d 'suction 12. This phase corresponds to the deceleration of the tool holder plate 1O until it stops and before the return movement in the direction of arrow F'. The height of the cutting tool 16, in line with the cutting blades is equal to the spacing between the outer surface of the support cylinder 9 and the tool-holder plate 10 so that the sheet 21 gradually penetrates the cutting blades when it is aligned with the axis of rotation 22 of the cylinder 9.

The passage of the cutting tool 16 supporting the sheet 21 cut under the suction channel 12 allows the evacuation of cutting waste 15 through said channel 12. The cut sheet which is on the cutting tool 16 when the tool holder plate 1O is in the second position illustrated in FIG. 2D is ejected from said cutting tool 16 by blowing compressed air through the ejection bellows 19 while the suction which was implemented through the pipes 18 is cut. This ejection combined with the suction implemented in the conveyor 13 makes it possible to flatten the poses 2O on the rollers 14. These are rotated so as to evacuate said poses 2O towards the receiving and stacking station 6.

The tool-holder plate 1O is driven in its reciprocating movement by at least one independent servo motor electronic with two directions of rotation 11. In addition, the cutter 4 includes means 23 for controlling the rotation of the support cylinder 9. The motor 11, of the brushless type, and the control means 23 are connected to an electronic circuit of controls 24 which comprises input means 25 being for example in the form of a keyboard.

The control means 23 may for example consist of an encoder mounted on the rotation shaft of the cylinder 9. The operator enters, before the start of its manufacture, the operating parameters in the input means. Among the parameters there is at least the length l of the cutting tool 16, which in fact corresponds to the format of the sheet to be cut.

The electronic control circuit 24 is programmed to meet the following condition. The linear speed of the tool-holder plate must constantly be equal to the peripheral linear speed of the support cylinder 9 as long as the cutting tool 16 is in contact with the support cylinder 9. This condition can be achieved by instant monitoring of the rotation of the support cylinder 9 by the control means 23 and thanks to the knowledge of the length l of the cutting tool.

In addition, the electronic control circuit 24 is programmed so as to vary the amplitude of the round-trip movement of the tool-holder plate 1O as a function of the length l of the cutting tool 16. This amplitude will be all the more small compared to the maximum amplitude for which the machine has been designed, that the length of the cutting sheet will deviate from the maximum cutting length L authorized by the machine.

In traditional cutters, all the moving parts, namely the support cylinder, the tool tray, the transfer casing and the launching casing, were driven from a single drive element using mechanisms such as than cams, pinions and racks. The travel of the tool tray was provided for the maximum format of sheets to be cut. Thus, as illustrated in FIG. 2E, the second position of the tool holder plate was reached only when the rear edge 1Ob of the tool holder plate 1O was placed under the conveyor 13.

From the comparison between FIGS. 2D and 2E, it is clear how the reduction in amplitude of the back-and-forth movement of the tool-holder plate 10 can be carried out, as a function of the length I of the cutting tool 16.

Thanks to this reduction in the amplitude of the movement, it is possible either to keep the same production rate but by reducing the powers involved or on the contrary to increase the production rates.

Preferably the electronic control circuit 24 is programmed so that the drive motor 11 drives the tool-holder plate 10 during the return movement of the latter according to a simple law composed of an acceleration, immediately followed by a deceleration , so that the duration of the return movement is less than that of the outward movement. It is therefore possible to increase the production rate, without modifying the cutting conditions, during the forward movement of the tool holder plate 1O.

The support cylinder 9 is designed to work either with a steel support surface or a support surface made of a flexible material, in particular polyurethane. To do this said support cylinder 9 comprises a chassis which comprises support means capable of receiving, as a support surface, one or the other of the coverings is either steel or flexible material. In the case of a steel covering, its thickness d ₁ will be less than the thickness d ₂ of the covering made of flexible material. The cutting machine 4 includes height displacement means 30 which are connected to the electronic control circuit 24. The operator introduces into the input means 25 the indication that it is one or the other of the coatings or the value of the thickness d ₁ or d ₂ .

It is understood that for the cutting operation to be carried out in good conditions, it is necessary to precisely adjust the surface outside of the support cylinder 9 relative to the cutting tool 16. It is this adjustment which is carried out automatically by the electronic control circuit 24 which controls the means of displacement in height 30 of the support cylinder 9 in function of the value of the parameter which has been entered by the operator. The speed of rotation of the support cylinder 9 and its radius at the support surface determine the peripheral linear speed of the cylinder.

The electronic control circuit takes these parameters into account, depending on the thickness d 1 or d 2 to ensure the launching of the tool-holder plate 1O via the motor 11, and of the sheet 21 via the box. 8 launch so that they have a linear speed equal to that of the support cylinder 9 while remaining in synchronism when the assembly is in the position shown in Figure 2B.

Thanks to this particular command, it is possible to place either of the coverings on the chassis and the cylinder support means, without any particular modification of the settings of the cutter 4.

Preferably, the electronic control circuit 24 is programmed so that a stop for the tool-holder plate 10 is provided when it is in the second position illustrated in FIG. 2D. It is during this stopping time that the stopping of the suction through the pipes 18 will be implemented on the one hand and the supply of compressed air through the ejection bellows 19 on the other hand. The fact that this occurs while the cutting tool 16 is stopped under the rollers 14 of the poses conveyor 13 guarantees perfect ejection of said poses 20 and their resumption by the conveyor 13. Advantageously the downtime t , which is entered by the operator in the input means 25 as an operating parameter is chosen on the order of a few hundredths of a second.

Of course this downtime which does not exist in traditional cutters increases the time taken for a round trip cycle of the plate 1O tool holder. However, thanks to the reduction of the stroke as a function of the format, this increase is hardly detrimental, especially given the guarantee of a perfect resumption of the poses and therefore of their subsequent stacking.

The cutter 4 also includes a sensor 26 for the presence of sheets which is placed upstream of the support cylinder 9, above the transfer casing 7. This sensor 26 is connected to the electronic control circuit 24. In addition, the latter is programmed to maintain the tool holder plate 1O in its first position illustrated in FIG. 2A in the case where the sensor 26 does not detect the presence of a sheet. Thus, when a sheet is missing or when there is a supply break from the printer 3, the tool-holder plate 10 remains in its first position and does not carry out its forward movement. back This avoids an operation of the vacuum cutter, such an operation causing premature wear of the cutting blades or possibly of the flexible material constituting the external surface of the cylinder 9.

The same sensor 26 may also be implemented as the edge detecting means back 21a of the sheet 21 to be cut. In this case, the transfer box 7 as well as the launch box 8 are each driven by a motor 27,28 respectively, with electronic servo-control of the brushless type. The two motors 27, 28 are also connected to the electronic control circuit 24.

In order for the synchronization of movement of the sheet 21, of the transfer case 7, of the launch case 8, of the cylinder 9 and of the tool holder plate 10 to be respected, in accordance with what is illustrated in FIG. 2B, it is important that the front edge 21a of the sheet 21 comes under the sensor 26 at a specific time in the operating cycle. If the electronic control circuit 24 finds, from the information transmitted to it by the sensor 26, that there is a positive or negative difference between the theoretical position of the front edge 21 a and the actual position of said edge, the electronic circuit 24 correlatively controls the actuation of the motor 28 driving the launching belt 8 so as to correct variation on the front edge 21a is perfectly in synchronism with the tool-carrier plate 1O depending on the configuration of Figure 2B.

This makes it possible to guarantee an exact positioning of the sheet 21 on the tool-holder plate 7 and therefore perfect repeatability of the cutting placement.

During the backward movement, in the direction of arrow F ', of the tool-holder plate 10, it is important that the cutting blades 17 do not come into contact with the external surface of the support cylinder 9, otherwise we would have premature wear of the cutting blades, especially when the exterior surface of the cylinder is made of steel or even premature wear of the exterior surface of the support cylinder 9 when the latter is made of a flexible material.

To avoid this contact, the height displacement means 30 of the support cylinder 9 make it possible to raise the cylinder 9 from a low position which corresponds to the cutting position to a high position which corresponds to a retracting position according to which the outer surface of the cylinder 9 is spaced from the cutting tool 16 during the return movement of the tool holder plate 1O.

The electronic control circuit 24 is programmed so that the support cylinder 9 is in the low position during the forward movement of the tool holder plate 10 and in the high position the rest of the time. In this embodiment of the cutting machine 4 in which the support cylinder 9 is equipped with means 3O for displacement in height, the electronic control circuit 24 is preferably programmed to periodically control said means for displacement in height 3O so that the support cylinder 9 remains in the high retraction position during the forward movement of the tool holder plate 1O. This command and the frequency at which it must be carried out, for example every fifty sheets, are operating parameters which are introduced by the operator into the input means 25 of the electronic circuit of controls 24.

This command has the effect that the corresponding sheet which is fed by the transfer box 7 and the launch box 8 is placed on the cutting tool 16 and goes from the first to the second position without the support cylinder 9 compresses it on the cutting blades. Thus the sheet which is ejected from the cutting tool 16 and taken up in the conveyor 13 is a sheet which has not been cut. This is particularly interesting in the case of multi-layered sheets, that is to say sheets which give rise to cuts of several portions inside the same sheet. The uncut sheet which is introduced regularly serves to stabilize the different stacks of 2O poses, playing in a way the role of spacer.

Preferably, the sheet movement members 21 at the station preceding the cutter 4 are provided with control means 31 which are connected to the electronic control circuit 24. The transfer box 7 and the launch box 8 are driven by motors with electronic servo-control, of the brushless type, respectively 27, 28 which are themselves connected to the electronic control circuit 24. Said circuit is programmed so that the speed of the sheet leaving the previous station and which is detected by the control means 31 is constantly equal to the speed of the sheet on the transfer box 7. In addition, the motor 28 driving the launch box 8 is controlled as a function of the aforementioned speed so that the sheet is launched towards the support cylinder 9 of such so that when it reaches the position illustrated in FIG. 2B, it has the same speed as the peripheral linear speed of the cylinder support 9.

In the example illustrated in FIG. 1, the preceding station being a printer 3, the control means 31 consist for example of an encoder mounted on the axis of rotation of the plate cylinder 32.

This particular arrangement makes it possible to make the operation of the cutter 4 completely independent of the feed speed of the sheets 21 from the previous post.

In the case where this speed is not likely to vary over time, it may be sufficient, without the need for control means 31, to introduce into the input means 25 an operating parameter corresponding to a relative indication at the speed of movement of the sheet leaving the previous station. In this case the setting of the speed of the transfer case 7 and of the launch case 8 is done automatically as a function of the value of said parameter.

In the example which is illustrated in FIGS. 4 to 6, the device of the invention makes it possible to carry out the coating change automatically and without manual intervention. To do this, the support cylinder 33 is constantly equipped with two coatings 34, 35, one 34, of thickness d ₁ , is a steel coating; the other, of thickness d ₂ greater than d _1, is a coating made of a flexible material, preferably mounted on a metal sheet.

As shown in FIG. 4, the support cylinder 33 has two distinct angular halves, of radii R and r respectively; r being less than R. On the first angular half of radius R is applied the first coating 34 acting as a cutting surface, while on the second angular half is applied the second coating 35 which is on standby. The support cylinder 33, during the cutting operation, is driven in continuous rotation but only the first coating 34 is implemented in cooperation with the tool holder plate.

The coverings 34 and 35 are by their end edges 36 made integral with the chassis 37 of the support cylinder 33. More specifically, the edges 36 are fixed to several rods 38 whose free ends folded towards said chassis 37 are terminated by rollers 39. These rollers 39 are intended to be housed in a U-shaped rail arranged concentrically with respect to the axis 22 of rotation of the cylinder 33 on the chassis 37, said rail forming a running track.

The rail has portions 40 which are fixed to the chassis 37 and sections 41, of reduced size, and which are fixed to the end of the rods 42 of actuators 43 themselves fixed on the frame 37. More specifically, each rod 42 of an actuator 43 comprises two sections 41 a and 41 b superimposed and concentric. The rollers 39 are housed in the sections 41a closest to the axis 22 of rotation of the cylinder 33. The sections 41a are provided for coming exactly fit between the 4O portions when the rod 42 of the jack 43 is in position output, as shown in Figure 6. the sections 41 b are provided to come exactly fit between the 4O portions when the rod 42 of the jack 43 is in retracted position, as shown in Figure 5. the device of the invention also comprises means for locking in position the covers 34 and 35 when they are in the high position, that is to say when the rods 42 of the jacks 43 are extended, as illustrated in FIG. 6. Furthermore the axis 22 of rotation of the cylinder 33 is driven by an independent electronic servo motor, in particular a brusless motor, which is connected, as well as all of the jacks 43 to the electronic control circuit. The coating change is carried out by the following steps, controlled automatically by the electronic circuit when the coating change is entered as an operating parameter. The arrangement of the different organs of the cylinder 33 is normally in the position which is illustrated in Figure 4, the rods 42 of the jacks 43 being returned and the sections 41 has rails with rollers 39 having slid in the low position, that is that is to say retracted with respect to the raceway, the coatings 34 and 35 being applied to the semicircular sheets 44, 45 acting as support sheets for the coatings 34, 35. It should be noted that the cylinder 33 may include an internal suction system intended to press the coatings 34, 35 on said sheets 44, 45 as described in the document FR.82O97O2.

The first step of the change consists in actuating the jacks 43 so as to take out the rods 42 and to position the rail sections 41 a with rollers 39 in the alignment of the portions 40 so as to constitute a continuous rolling track for the rollers 39. In doing so, the coverings 34, 35 are separated from the curved sheets 44, 45, as illustrated in FIG. 6. Of course, the suction system is then cut.

The second step consists in actuating the means for blocking the coatings 34, 35 so as to keep them fixedly in angular position relative to the axis of rotation 22.

The third step consists in driving the independent motor so that the chassis 37 of the cylinder 33 rotates through an angle of 180 °. During this rotation, the rollers 39 rotate on themselves in the rolling track r, thus allowing the linings 34, 35 to remain in position despite the rotation of the chassis 37.

The fourth step consists in unlocking the coverings 34, 35 and the fifth in actuating the jacks so as to fit the rods 32 as illustrated in FIGS. 4 and 5.

During the 180 ° rotation of the chassis 37, the covering 34 is placed above the angular portion of radius r, while the covering 35 is placed above the angular portion of radius R. After the re-entry of the rods 42 of the jacks 43, the coatings 34 and 35 are again pressed against the corresponding support plates 45, 44. The coating 35 is then positioned as a bearing surface for cutting, while the coating 34 is in the standby position.

This possibility of displacement relative to each other of the coverings 34 and 35 can also be taken advantage of in the event that it turns out to be necessary to make a setting of the coverings 34, 35, that is to say to interpose between the support sheet 44 and the coating 34 of the shims making a fine adjustment compensating for any surface irregularities. For this it suffices that the electronic circuit is programmed to control the only cylinders corresponding to a given angular portion as well as the only blocking means corresponding to a given coating so as to be able to make accessible to the operator, after rotation of the chassis 37 the outer surface of the support sheet 44, stripped of its coating 34.

Claims (14)

1. Apparatus for cutting semi-rigid sheets (21) one by one, in particular corrugated cardboard sheets, the apparatus comprising a cutting tool (16) fixed to the tool-carrier plate (10) and a backing cylinder (9), the tool-carrier plate (10) being driven with forward-and-return reciprocating motion between a first position where the cutting tool (16) is situated in front of the backing cylinder (9) and a second position where it is situated behind the backing cylinder (9), the sheet (21) being inserted by launching means over the cutting tool (16) when the tool-carrier plate (10) has left the first position, the sheet being cut as it passes under the backing cylinder (9) and then being removed from the cutting tool (16) when the tool-carrier plate (10) is in its second position, the apparatus being characterized in that the backing cylinder (9) comprises a chassis and support means suitable for receiving as the backing surface either a steel covering of thickness d₁ or else a covering of flexible material of thickness d₂, in that it comprises vertical displacement means (30) for displacing the backing cylinder (9) between two positions adjusted for cutting purposes, the first corresponding to the thickness d₁, and the second to the thickness d₂, and in that it comprises at least one first independent motor (11) having electronic servo-control and rotatable in either direction, driving the tool-carrier plate (10) in reciprocating motion, and a second independent motor having electronic servo-control driving the launching means (8), and monitoring means (23) for monitoring rotation of the backing cylinder (9), said first and second motors, the monitoring means (23), and the vertical displacement means (30) for the backing cylinder all being connected to a controlling electronic circuit (24) that has input means (25) for receiving operating parameters including at least the thickness (d₁ or d₂) of the covering, and in that said circuit (24) is programmed to control the vertical displacement means (30) for displacing the backing cylinder (9) as a function of the thickness parameter, and for controlling the first and second motors so that the linear speed of the launching belt (8) and that of the tool-carrier plate (10) are equal to the peripheral linear speed of the backing cylinder (9) at the moment when the cutting tool (16) presents the sheet (21) under the backing cylinder (9), and so that the linear speed of the tool-carrier plate (10) is equal to the peripheral linear speed of the backing cylinder (9) so long as the cutting tool (16) is in contact with said backing cylinder (9).
2. Apparatus according to claim 1, characterized in that the length l of the cutting tool (16) is one of the operating parameters, and the electronic circuit (14) is programmed so that the amplitude of the reciprocating motion of the tool-carrier plate (10) is a function of the parameter l.
3. Apparatus according to claim 1 or 2, characterized in that the controlling electronic circuit (24) is programmed so that the tool-carrier plate (16) is stopped in its second position for a determined length of time t which is entered as an operating parameter via the input means.
4. Apparatus according to any one of claims 1 to 3, characterized in that it includes a sensor (26) for sensing the presence of sheets, the sensor being located in front of the backing cylinder (9) and being connected to the controlling electronic circuit (24); and in that the electronic circuit is programmed to keep the tool-carrier plate (10) in its first position whenever the said sensor (26) does not detect a sheet.
5. Apparatus according to any one of claims 1 to 4, characterized in that it includes a system for identifying the position of a predetermined element of the sheet (21) that is situated upstream from the backing cylinder (9) and that is connected to the controlling electronic circuit (24), and in that said circuit is programmed so that any difference observed between the ideal position and the real position of the edge (21a) of the sheet (21) as detected by the sensor (26) is corrected by a compensating variation in the drive of the motor (28) fitted to the launching belt (8).
6. Apparatus according to claim 1, characterized in that the vertical displacement means (30) for the backing cylinder (9) are suitable for moving between a low position corresponding to the cutting position and a high position corresponding to the retracted position, and in that the controlling electronic circuit (24) is programmed so that the backing cylinder (9) is in the low position during the forward motion of the cutting tool (16), as it goes from its first to its second position, and is in the high position the rest of the time.
7. Apparatus according to claim 6, characterized in that the controlling electronic circuit (24) is programmed to keep the backing cylinder (9) periodically in the high position while the tool-carrier plate is performing its forward motion from the first position to the second position, this being done at a frequency that constitutes one of the operating parameters entered via the input means (25) of the electronic circuit (24).
8. Apparatus according to claim 1, characterized in that it includes transfer means (7) bringing the sheet (21) from the preceding station (3) to the launching means (8), in that the transfer means (7) are fitted with an independent motor (27, 28) having electronic servo-control and connected to the electronic circuit (24), in that monitoring means (31) are mounted on the sheet displacement members (32) of the preceding station (3), said monitoring means (31) being connected to said electronic circuit (24), and in that said electronic circuit is programmed so that firstly the speed of the transfer means (7) is constantly equal to the speed of the sheet leaving the displacement members (32) of the preceding station (3), and secondly the launching means (8) are controlled as a function of said speed so that the sheet (21) has the same speed (V₁) as the peripheral linear speed of the backing cylinder on reaching the tool-carrier plate (10).
9. Apparatus according to claim 1, characterized in that the predetermined element is the leading edge (21a) or trailing edge of the sheet, and the position-identifying system is constituted by a position sensor (26).
10. Apparatus according to claim 1, characterized in that the predetermined element is a predetermined printed zone of the sheet, and the position-identifying system is constituted by a camera.
11. Apparatus according to claim 1, characterized in that the backing cylinder (33) is fitted simultaneously with two types of covering (34, 35), in that the first support means suitable for receiving the covering (34) constituting the backing surface during cutting consist in a curved metal sheet (44) disposed at a first angular position at a distance R from the axis of rotation (22) of the cylinder (33) and the second support means are suitable for receiving the standby covering (35) and are constituted by a curved metal sheet (45) disposed at a second angular position at a distance r that is less than R from the axis of rotation (22) of the cylinder, and in that it includes displacement means suitable for displacing the two coverings (34, 35) radially relative to their respective support means (44, 45) and for displacing them angularly so as to interchange them.
12. Apparatus according to claim 11, characterized in that the coverings (34, 35) are secured at each end to the chassis (37) by means of a plurality of rods (38) that are terminated by wheels (39), in that the end members of the chassis (37) include a concentric rail (40) forming a running track for said wheels, in that the radial displacement means are constituted by actuators (43) whose rods (42) are terminated by sliders each constituted by two short lengths (41a, 41b) of the superposed concentric rail, and in that said actuators (43) are operable between:

    a) a first position in which the rods (42) are retracted and the wheels (39) are received in the short lengths (41a) closer to the axis of rotation (22) of the backing cylinder; the coverings (34, 35) are pressed against their respective support sheets (44, 45), and the short lengths (41a) containing the wheels are retracted beneath the track (40b); and

    b) a second position in which the rods (42) are extended, with the coverings (34, 35) being moved away from their support sheets (44, 45) and the short lengths (41a) of rail containing the wheels are in alignment with the rail (40) on the end members of the chassis (37).
13. Apparatus according to claim 11 or 12, characterized in that the angular displacement means are constituted by an independent motor having electronic servo-control that rotates the backing cylinder (33), and means for temporarily locking the coverings.
14. Apparatus according to claim 13, characterized in that the independent motor, the locking means, and the actuators (43) are connected to the controlling electronic circuit, and in that said circuit is programmed so as to cause the following operations to be performed in succession: firstly the rods (42) of the actuators (43) are extended; then the coverings (34, 35) are locked, then the cylinder (33) is rotated, then the coverings (34, 35) are unlocked, and finally the rods (42) of the actuators (43) are retracted.

Images