EP2838733B1 - Device and method for transporting substrates in a printing machine - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of printing, in particular without contact with the substrates, and more particularly to a device and a method for transporting printable substrates on all the workstations included in a printing machine. the substrates are transported in such a way as to allow their printing under optimal conditions.

BACKGROUND OF THE INVENTION

It is known from the prior art, transportable printable substrates made by suction belts, whose function is to maintain and tension a substrate against said moving belts. This type of solution, well known to those skilled in the art, nevertheless has some disadvantages. In particular, this type of device, causing air movements and pressure gradients, can cause the deformation of the substrates if they are large. The accuracy of printing will therefore be affected. On the other hand, the use of these suction belts with some widely used printing technologies, such as inkjet printing, can cause accidental suctioning of the ink in the print heads and defuse the printheads. This type of incident requires in the best case a reboot of the heads, and in the worst case a replacement of defused heads, become unusable if they are secured to the ink tank.

To overcome these problems, in particular to allow the displacement of substrates accurately, there are in the prior art techniques using cylinders having a plurality of grippers gripping the substrates by the leading edge relative to the direction of movement of the substrate. Suitable for inkjet type printing machines, this type of solution nevertheless has several disadvantages. Indeed, this system requires an arrangement of all orbital inkjet heads around a large cylinder. In addition, this type of system raises the problem of the difficulty of adjusting the position of the printheads. Indeed, for a quality printing, the ink ejected from the print heads must form a jet whose direction is perpendicular to the surface of the substrate. It is understood in this case that the use of a cylinder for transporting and tensioning the substrate, whose surface is by definition not flat, imposes tedious adjustments of the position of the printing heads. For the same reason, it is difficult to use substrates of variable thickness, the change of substrate imposing an adjustment of all the print heads. On the other hand, the printing pitch, that is to say the position of the clamps on the cylinder, is fixed, which means that the print rate remains the same regardless of the size of the substrate.

It is also known in the prior art of substrate transport systems using chains or conveyors on which are arranged grippers for gripping the substrates and transporting them on a transport path of which a portion is flat, which solves the problem of the layout of the print heads, see the document DE102011011396 A1 . However, this type of solution still has the problem of a fixed printing step, which imposes a fixed rate and, in this case, poses the additional problem of not allowing to use substrates of different sizes without stopping the printing and make a tedious adjustment of the position of the clamps. DE10047395 shows a printing machine comprising a variable pitch sheet conveying system.

GENERAL DESCRIPTION OF THE INVENTION

The present invention aims to solve at least one of the problems of the prior art, as outlined above. The invention proposes a new device and a novel method for transporting printable substrates accurately, suitable for substrates of various types, sizes and thicknesses. In particular, the invention makes it possible to produce variable pitch prints. In addition, the invention is adapted to machines non-contact printing with the substrate, such as inkjet printing machines.

To this end, the invention relates to a printing machine comprising a substrate transport system as defined in claim 1. Other features and advantages of the substrate transport system are detailed in the present application. A further object of the invention is to provide a method of transporting and tensioning printable substrates.

To this end, the invention relates to a method for the stressing and transport of substrates along a transport path, implemented by a substrate transport system according to the invention, as defined in claim 22. . Other features and advantages of the method of tensioning and transporting substrates are detailed in the present application.

• La figure 1 illustre de manière schématique une vue tridimensionnelle du système de transport de substrats selon certains modes de réalisation.
• La figure 2 illustre de manière schématique un premier mode de réalisation de l'invention.
• La figure 3 illustre de manière schématique un deuxième mode de réalisation de l'invention.
• La figure 4a illustre une paire de moyen de préhension en position ouverte, la partie mobile assurant l'ouverture étant en vis-à-vis du verso du substrat, le recto étant la face imprimable en vis-à-vis des têtes d'impression.
• La figure 4b illustre une paire de moyen de préhension en position fermée, la partie mobile assurant l'ouverture étant en vis-à-vis du verso du substrat, le recto étant la face imprimable en vis-à-vis des têtes d'impression.
• La figure 4c illustre une paire de moyens de préhension maintenant un substrat par ses bords latéraux.
• La figure 5 illustre de manière schématique un troisième mode de réalisation de l'invention.

The invention, with its features and advantages, will emerge more clearly on reading the description given with reference to the appended drawings in which:

• The figure 1 schematically illustrates a three-dimensional view of the substrate transport system according to some embodiments.
• The figure 2 schematically illustrates a first embodiment of the invention.
• The figure 3 schematically illustrates a second embodiment of the invention.
• The figure 4a illustrates a pair of gripping means in the open position, the movable portion providing the opening being opposite the back of the substrate, the front being the printable face vis-à-vis the printing heads.
• The figure 4b illustrates a pair of gripping means in closed position, the movable portion providing the opening being vis-à-vis the back of the substrate, the front being the printable face vis-à-vis the printheads.
• The figure 4c illustrates a pair of gripping means holding a substrate by its side edges.
• The figure 5 schematically illustrates a third embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The present invention relates to a device or system (here both terms being used interchangeably) for transporting substrates, as well as a method for transporting and tensioning substrates. The substrate transport system is described below with reference to the figures, but it is clear that the figures and examples provided in this application are illustrative and not limiting. Said substrate transport system is included in a printing machine, for example and without limitation an inkjet printing machine. The machine is controlled by computer means which control in particular the various workstations, by controlling, according to configuration parameters (particularly dependent on substrates), their devices, systems or means (motorization, gripping, guiding, detection). The computer means can also collect information from different detection means (sensors for example) to coordinate the operations of the various stations, devices, systems and means of the machine. These computer means do not have to be detailed in the present application and they may for example be integrated in the machine or deported in a device or separate system. The sensors give, for example, position information of the substrates, configuration information of the substrates (3) and / or validation information following a correctly performed operation or not. Some information necessary for the implementation of the invention can also be registered beforehand in the computer means (for example via input on an interface by an operator). Such information may for example relate to the size of the substrates or their thickness, but it is generally preferred that sensors measure or verify such information. The substrates (3) awaiting printing are generally, in a manner known per se, placed in at least one input magazine (30) having a capacity defined according to the nature of the substrate (3) and the needs for the 'impression. In an exemplary embodiment, an input store (30) is provided to accept several thousand substrates (3) of nature, thickness and variable size (for example and without limitation a credit card format up to A0). Once the printing process is complete, the substrates (3) are stored in at least one output store (31) generally having the same capacity as an input store. A substrate gripping device (3) makes it possible to release the substrates (3) from the input magazine (30) and to arrange them on drive means, for example the substrates transport system, the characteristics of which will be detailed in more detail. far in the description, to move them along a working line generally comprising several workstations, for example and without limitation at least one printing station comprising a plurality of controlled inkjet printheads by computer means, followed by a drying station. In general, controls are also performed to detect the presence of a single substrate (3) at each post of the conveyor. The printing machine makes it possible to print from one substrate to another with a variable pitch, thanks to the transport system, as detailed below. This means that the printing machine is able to adapt the use of the print heads and the transport speed of the substrates (3) according to the size of the substrates (3), for example by means of sensors installed on the printing machine. In some embodiments, the printing machine is equipped with a substrate reversing device (3), allowing two-sided printing of said substrates.

In some embodiments, and by way of illustrative and non-limiting reference to Figures 4a to 4c the substrate transport system (3) comprises movable gripping means (2) moving along a transport path oriented along a longitudinal axis, for example between an input magazine (30) providing substrates (3) printable and an output magazine (31) receiving the substrates (3) printed. The transport path is defined by the plane in which the substrates move and oriented along the longitudinal axis. For example, the substrates (3) may be blank, or have patterns already printed. In some embodiments, these means of gripping (2) are pliers, a term that will be used in the following description in an illustrative and non-limiting manner to designate the gripping means (2) in a general manner. Each clamp (2) includes an opening / closing system (22) for gripping or releasing substrates in convoy along the transport path (or print path). This opening / closing system (22) is controlled (23) by the computer means. Each clamp comprises a fixed part (20) and a movable part (21), or two moving parts, the movement of which makes it possible to grasp or release a substrate (3).

In the present description, the substrates, clips or edges of the substrates that are located towards the outlet store are referred to as "front", while those located to the entrance store are referred to as "back". , with reference to the direction of movement of the substrates in the printing machine. On the other hand, the term "lateral" refers to the elements lying on either side of the longitudinal axis of the transport path. Finally, the term "interlayer" refers to grippers gripping a substrate at a level located between the front and the rear of this substrate (thus between the front and rear clamps). It is understood that these designations are conventional and are not limiting. In some embodiments, the forceps (2) controlled by the computer means grip each substrate (3) in an area near the four corners of the substrate. Nevertheless, depending on the configuration (in particular the control carried out by the computer means), various clamps can grip the substrates in different places, in particular on the front and / or rear edges and / or on the lateral edges.

In some embodiments, the movable portion (21) of each gripper (2) is located vis-à-vis the front of each substrate (3), the front being the printable face of the substrates (3) located vis-à-vis the to the print heads. These embodiments generally make it possible to facilitate the release of the substrates, in particular when the clamps move away from the substrate in the direction of the back side when they have released the substrate (for example in the case of a substrate). closed circuit conveyor). In other embodiments, generally preferred, the movable portion (21) of the clamps is located vis-à-vis the back of each substrate (3) convoy. This arrangement makes it possible to limit the risks of contact of the moving part with the print heads. On the other hand, the position of the printheads is generally adjustable at least in the direction of the height (perpendicular to the plane of the transport path), which makes it possible to avoid any contact between the movable part (21) of the clamps. (2) and the print heads. This adjustable height is particularly advantageous in the embodiments where the moving part is on the front side and in the modes where the moving parts are both the front side and the back side. Finally, the opening / closing system (22) of the clamps is for example controlled by an electromagnet, or a system of rods.

In some embodiments, the substrate transport system includes guide means (1) for the grippers (2) disposed along the entire length of the transport path of the substrates (3). By abuse of language, such guide means can be referred to as means for moving motorized grippers, but here the guide designation is preferred, in particular because the grippers may comprise a motor or only a passive motorization part. For example and without limitation, these guide means (1) of the clamps are guides, rails or slides, arranged along the substrate transport path (3). In some embodiments, the guiding means forms a closed circuit of which a "go" part forms the transport path and a "return" portion forms a return path of the clamps to the input magazine. The term "guide" is used in the present description to denote the guide means (1) in an illustrative and non-limiting manner. In some embodiments, each displacement guide (1) forms a closed circuit that may be, for example, oblong, each guide (1) being in a plane parallel to the plane of the substrates (ie, of the transport path). In alternative embodiments, each guide is in a plane perpendicular to the plane of the substrates (3).

In certain preferred embodiments, the substrate transport system (3) comprises two guides (1) comprising a plurality of clamps (2), each guide (1) being disposed on either side of the substrate transport path (3). In some of these embodiments, the substrate transport system may comprise a plurality of guides (1) arranged in pairs, on either side of the transport path, the distance between the guides (1) of each pair being different to allow adaptation of the substrate transport system (3) to substrates (3) of different size, in particular of variable width. In some preferred embodiments, the substrate transport system (3) comprises two guides (1) arranged on either side of the substrate transport path (2), whose transverse spacing is variable and controlled by the computing means, the substrate transport system (3) can thus adapt to any substrate size (3). In some embodiments, a non-limiting example of which is schematically illustrated in the figure 5 , the substrate transport system (3) comprises two guides (1) arranged on either side of the substrate transport path (3), whose transverse spacing is variable and controlled by computer means, the first guide (1) comprising at least one clamp (200) for gripping at least a front portion of a substrate (3), the second guide (1) comprising at least one clamp (210) for gripping at least a rear portion of a same substrate (3).

The present application defines front gripping means and rear gripping means. We speak here of at least one front clamp (200) and at least one rear clamp (210) because, as for example represented on the figure 5 it is possible to have a pair of front grippers (200) and a pair of rear grippers (210), but it is possible to have only one front gripper and one rear gripper. In addition, it is referred to here as part or front and rear portions of the substrate (or portion located at the front or rear) because it is possible to grasp a front edge and a rear edge such as on the figure 5 , but it is possible to capture a portion or portion of the lateral edges located near the front of the substrate and a portion or portion of the lateral edges located near the back of the substrate (the two lateral edges are generally grasped rather than only one lateral edge, depending on the rigidity of the substrate). On the one hand, therefore, reference is made to front gripping means gripping at least one part situated at the front and secondly to rear gripping means gripping at least one part situated at the rear (which it is a front / rear edge or a side edge located at the front / rear). On the other hand, the front and rear gripping means can in fact each grab a substrate, respectively front and rear, that is to say a first substrate (called "before") presenting itself first on the transport path and a second substrate (called "back") which follows the first and may have a size different from the first. For example, a single front gripper grasps a first substrate, said before, for example at its front edge or a side edge, while a single rear gripper grasps a second substrate, said back, for example at the level of its front edge or side edge. It is possible to also capture each of the front and rear substrates by at least two grippers which together form one of the front or rear gripping means,

In some embodiments, the substrate transport system (3) comprises means for detecting the speed and / or the position of the grippers (2) along the transport path, said detection means being controlled by the means computer (eg included in the printing machine). For example and without limitation, each clamp (2) may comprise a position sensor and / or a speed sensor connected to the computer means. In preferred embodiments, said speed and / or position sensors are integrated with the motorization means, said motorization means being controlled by the computer means, and allowing the clamps (2) to move along the guides (1). ), themselves arranged along the transport path.

In some embodiments, the substrate transport system (3) includes substrate detecting means (generally for detecting the leading edge) when the latter enter the transport path, for example as soon as they leave the store. input. These means of detection, controlled by the computer means, are for example and without limitation sensors included in at least one input store (30). For example and without limitation, this sensor is an optical encoder or an optical ruler. These detection means can detect, for example, the speed and / or the position of the substrates. Detection of the front edge may be sufficient insofar as the computer means know the speed of the substrates at the output of the input store, but it will also be possible to detect the speed to optimize the exploitation of this information by the computer means. Thus, the substrate transport system is therefore adapted, in certain embodiments, to detect the speed of the substrates (3) and to allow the clamps (2) moving along the guides (1) to grasp each substrate in such a way that to move it along the transport path oriented along the longitudinal axis.

In some embodiments, the substrate transport system (3) is also configured to tension the substrates (3), the tensioning force being applied by the grippers (2) holding the substrate at least along the longitudinal axis , so as to facilitate their transport and to increase the printing accuracy. For example and in a nonlimiting manner, the clamps (2) comprise a device for applying in a controlled manner a transverse voltage (ie, perpendicular to the longitudinal axis of the transport path) to the substrate, for example at the level of the transmission system. opening / closing (22) to apply the tension at the time of closure of the clamps. Such a transverse tensioning device may for example and without limitation include transversely extending suction pads just before closing said clamps (2) on the substrate (3). The applied voltage is parameterized using computer means as a function of the elasticity of the substrate and its width. In some embodiments not exclusive of those with transverse voltage above, a longitudinal tension (ie, parallel to the longitudinal axis of the transport path) is applied to the substrate, as detailed below.

The substrate transport system (3) comprises at least one guide (1) on which a plurality of gripping means (2) and at least one drive means for moving the gripping means (2) (or grippers) are installed. ). As mentioned above, the gripping means, in particular front and rear, may in fact comprise a single gripper, to grasp the substrates on a single edge. In this case, the substrates are preferably grasped by their front edge, but it is also possible to seize them by a lateral edge, in particular in the case of sufficiently rigid substrates (possibly with respect to their size) in order to be required of the so. In some embodiments, the movement of the grippers (2) is controlled in pairs, each of the grippers of each pair being generally disposed at the same level along the longitudinal axis (since the substrates are generally rectangular). In some of these embodiments, the clamps are independent but their movement is synchronized in pairs. In other embodiments, each clamp (2) is connected to the other clamp of the pair located on the other side of the longitudinal axis of the transport path of the substrates (3). Preferably, the substrate transport system (3) is adapted to capture each substrate so as to tension and / or move substrates (3) of variable sizes (in particular of variable length) along the transport path. Indeed, the transport system comprises at least one motorization means (for example controlled by the computer means, in particular according to the substrates to be printed) ensuring a displacement of the gripping means (2) along the guide means (1). , with an independent movement between at least the front gripping means (2) and the rear gripping means (2). Thus, by controlling the speed of the front and rear clamps, it is possible to tension (longitudinal) the substrates regardless of their size (in length in this case, the tension in width being managed by the transverse tension device) . Such tensioned substrates can be moved on the transport path or held motionless, for example when printing with moving print heads or during drying (which is therefore an example of the tender alternative , without necessarily moving). On the other hand, in the case where the front and rear gripping means each grip a substrate, respectively front and rear, as explained above (by a single clamp each for example), the substrates thus held, without longitudinal tension, can be moved in the machine of printing and the independent movement of the front and rear gripping means makes it possible to move substrates of variable sizes (which is therefore an example of the alternative of moving, without necessarily straining, substrates of variable sizes).

In some embodiments, said at least one motorization means comprises motor means equipping the gripping means (2). For example, a motor can equip the clamps (2), individually or in pairs, to move the clamps along the guide means. Thus, in some of these embodiments, each gripping means (2) comprises at least one motor means ensuring its displacement along the guide means (1).

In some embodiments, said at least one motorization means comprises at least one passive part equipping the gripping means (2) and at least one active part equipping the guiding means (1). In such embodiments, the passive part integrated in the clamps allows the displacement of the latter, for example controlled individually or in pairs, on the guide means which comprise the active part or, possibly, which are parallel to the active part. . Indeed, in some of these embodiments, said active portion of the motorization means comprises at least one linear motor. In addition, in some of these embodiments, said at least one linear motor is installed on at least one rail parallel to the guide means (1). On the other hand, in some embodiments, the transport system comprises at least two guiding means (1) on which the gripping means (2) moves. Thus, it is possible to have several motorization means (eg, linear motors) on the guides. In some of these embodiments, as for example in the case of the figure 5 said at least two guide means (1) comprise at least one guide means on which the front gripping means (2) and at least one guiding means on which the rear gripping means (2) move. Finally, as previously explained, the clamps are preferably controlled in pairs (for better gripping and / or tensioning of the substrates). Thus, in some embodiments, the transport system comprises pairs of gripping means (2), each comprising two gripping means (2) located on the same side, front or rear, of the same substrate, the displacement of a pair of gripping means (2) being provided by the same motorization means, along at least one guide means (1).

In some embodiments, the substrate transport system (3) includes gripper motor means (2). For example and without limitation, the motorization of the clamps (2) is achieved by linear motors. In embodiments, two clips (2), whose coordinates along the longitudinal axis are substantially the same, and which are installed on guides (1) located on either side of the transport path, are connected to the same linear motor. It is obvious, in order not to subject the substrates (3) to shear forces that could induce their deformation or tearing, that the speed of the grippers (2) having gripped the same substrate (3) is synchronized.

In some embodiments, the linear motors are installed on at least one rail parallel to the guides (1) on which the clamps (2) are installed. In some embodiments, the linear motors are integrated with the guides (1). For example and without limitation, only the passive part of the linear motor is associated with at least one clamp (2), the active part being installed on each guide (1) or on a rail parallel to the guides (1), following the embodiments.

In some embodiments, a substrate support (3), adjustable in position along an axis perpendicular to the substrate (3) so as to optimize the distance of the substrate (3) to the printing heads of the machine from printing, is integrated within the printing machine between the shops input (30) and output (31). For example and without limitation a sole disposed along the transport path between the inlet (30) and outlet (31). In order to optimize the distance of the substrate (3) to the printing heads of the printing machine, the substrate support (3) is adjustable in a plane perpendicular to the substrates (3). In some embodiments, the substrate support has a slightly curved profile so as to accentuate the longitudinal tensioning of the substrates (3) in a convoy. In preferred embodiments, the substrate support (3) comprises a plurality of openings, for example and without limitation cavities, so as to avoid the lifting of the moving substrates along the transport path of the aerodynamic effects, well known to those skilled in the art such as the phenomenon of lubrication. In some embodiments, in order to adapt to the different widths of substrates used, the substrate support is transversely adjustable,

The computer means, for example included in the printing machine, control the opening and closing of the clamps (2), evaluate the speed and / or the position of the moving elements, and finally deliver the control and control signals of the motorization means (for example the linear motor or motors).

Another object of the invention is to propose a method of setting and transporting substrates (3) along a transport path, implemented by various embodiments of the substrate transport system (3). previously described. The different successive stages characterizing this process and its possible variants according to various embodiments will now be described, with reference to Figures 1 to 5 illustratively and non-limitatively.

First of all, note that the printable substrate (3) passes successively through all the stations constituting the printing machine, from the input magazine (30) to the reception of the substrates in the output magazine (31). , that the machine comprises only one printing station, preferably with a drying station, or several printing stations or customization known per se. In a general manner, the computer means control the opening and closing of the gripping means (2), evaluate the moving speed of the movable elements, and deliver the control and control signals of the motorization means (for example the linear motors).

It will be noted that in the case of linear motors, the speeds and / or position of the clamps are generally known because they are actively controlled by the latter which are only passive. It is then possible to dispense with clamp detection means, although it is generally preferred to add them to ensure the proper functioning of the system and avoid damaging the elements of the system.

1. a. positionnement dans une zone proche du magasin d'entrée (30), par ledit au moins un moyen de motorisation actionné par les moyens informatiques, d'au moins un premier moyen de préhension (2), dit moyens de préhension avant, suite à une détection du bord transversal avant d'un substrat (3) par rapport au sens de déplacement,
2. b. déplacement des moyens de préhension (2) avant, à une vitesse adaptée à celle du substrat (3), et de positionnement desdits moyens de préhension (2) dans une zone proche de la partie avant du substrat (3), les moyens informatiques exploitant des informations de vitesse et de position du substrat (3) pour contrôler les vitesses et la synchronisation des moyens des préhension (2) en fonction de la position des substrats (3) le long du chemin de transport,
3. c. fermeture des moyens de préhension (2) avant par le système d'ouverture/fermeture (22) sur au moins un bord du substrat (3), lesdits moyens de préhension (2) entrainant désormais le substrat (3),
4. d. positionnement puis déplacement synchronisé à une vitesse adaptée à celle des moyens de préhension (2) avant, et fermeture sur au moins un bord du substrat (3), d'au moins un deuxième moyen de préhension (2), dit moyens de préhension arrière,
5. e. mise en tension du substrat (3) situé entre les moyens de préhension (2) avant et arrière.
6. f. ouverture du système d'ouverture/fermeture (22) des moyens de préhension (2) avant lorsque la position de ces derniers se situe dans une zone proche du magasin de sortie (31) de la machine d'impression,
7. g. ouverture du système d'ouverture/fermeture (22) des moyens de préhension arrière, au bout d'un temps t₁ dépendant de la distance, avant ouverture, entre les moyens de préhension (2) avant et arrière, suivie du ralentissement desdits moyens de préhension (2) afin de libérer le substrat (3),
8. h. retour des moyens de préhension (2) dans une zone de stockage proche du magasin d'entrée (30).

In certain embodiments, the method is characterized in that it comprises the following steps:

1. at. positioning in an area near the input magazine (30), by said at least one drive means actuated by the computer means, at least a first gripping means (2), said front gripping means, following a detecting the front transverse edge of a substrate (3) with respect to the direction of movement,
2. b. moving the gripping means (2) forward, at a speed adapted to that of the substrate (3), and positioning said gripping means (2) in an area close to the front portion of the substrate (3), the computing means exploiting substrate speed and position information (3) for controlling the speeds and timing of the gripping means (2) as a function of the position of the substrates (3) along the transport path,
3. vs. closure of the gripping means (2) before by the opening / closing system (22) on at least one edge of the substrate (3), said gripping means (2) now driving the substrate (3),
4. d. positioning and synchronized movement at a speed adapted to that of the gripping means (2) before, and closing on at least one edge of the substrate (3), at least one second gripping means (2), called rear gripping means,
5. e. tensioning the substrate (3) between the front and rear gripping means (2).
6. f. opening the opening / closing system (22) of the front gripping means (2) when the position of the latter is in an area near the output magazine (31) of the printing machine,
7. boy Wut. opening of the opening / closing system (22) of the rear gripping means, at the end of a distance-dependent time t ₁ , before opening, between the front and rear gripping means (2), followed by the slowing down of said means for gripping (2) to release the substrate (3),
8. h. return of the gripping means (2) in a storage area near the input magazine (30).

• a". positionnement de l'ensemble des moyens de préhension (2) le long d'un même substrat, dans une zone proche du magasin d'entrée (30) simultanément à la détection du bord avant d'un substrat (3) (par exemple détection de la vitesse et/ou de la position),
• b". déplacement synchronisé des moyens de préhension (2) à une vitesse adaptée au substrat (3), contrôlée par les moyens informatiques exploitant (ou relayant) les informations de vitesse et de position du substrat (3),
• c". fermeture des moyens de préhension (2) par le système d'ouverture/fermeture (22), lesdits moyens de préhension (2) entrainant désormais le substrat (3),
• d". une étape de mise en tension des substrats (3) par les moyens de préhension (2).

It is understood from these embodiments that the clamps (2) successively grip the substrate as it enters the transport path. In some embodiments, the clamps can be positioned in advance of each other according to the respective positions to which they must enter the substrate (according to the configuration controlled by the computer means for example). In such embodiments, steps a to e are replaced by the following steps:

• positioning of the set of gripping means (2) along the same substrate, in an area near the input magazine (30) simultaneously with the detection of the front edge of a substrate (3) ( for example detection of speed and / or position),
• b "synchronized movement of the gripping means (2) at a speed adapted to the substrate (3), controlled by the computer means exploiting (or relaying) the speed and position information of the substrate (3),
• c.) closing the gripping means (2) by the opening / closing system (22), said gripping means (2) now driving the substrate (3),
• a step of tensioning the substrates (3) by the gripping means (2).

• f'. ouverture du système d'ouverture/fermeture (22) des moyens de préhension (2) avant, suivi de l'accélération desdits moyens de préhension (2) avant, de manière à ce qu'ils continuent leur déplacement sur les moyens de guidage (1) et retournent dans une zone de stockage proche du magasin d'entrée (30),
• g'. ouverture du système d'ouverture/fermeture (22) des moyens de préhension arrière, au bout d'un temps t₂ dépendant de la distance, avant ouverture, entre les moyens de préhension (2) avant et arrière, suivi du ralentissement des moyens de préhension arrière afin de libérer le substrat (3) puis de l'accélération de manière à ce que les moyens de préhension (2) arrière continuent leur déplacement sur chaque guide (1) et retournent dans une zone de stockage proche du magasin d'entrée (30).

As already mentioned in the present application, the transport system may comprise closed-circuit guidance means. In such embodiments, steps f to h of the method are replaced by the following steps:

• f. opening of the opening / closing system (22) of the gripping means (2) before, followed by the acceleration of said gripping means (2) before, so that they continue their movement on the guiding means ( 1) and return to a storage area near the input store (30),
• boy Wut'. opening of the opening / closing system (22) of the rear gripping means, after a time t ₂ depending on the distance, before opening, between the gripping means (2) front and rear, followed by the slowing down of the means rear gripping device to release the substrate (3) and then the acceleration so that the gripping means (2) rear continue their movement on each guide (1) and return to a storage area near the store entrance (30).

As already mentioned in the present application, the clamps (2) can grasp the substrates by the side edges. The closing steps of the clamps will preferably take place on the lateral edges of the substrates. This is also valid for the front and rear clamps, but these can also grab the substrates by the edges, respectively, front and rear (when it comes to grabbing the same substrate with the front and rear clamps) or grasp respectively an edge (preferably a leading edge or a side edge) of a front substrate and an edge (preferably a leading edge or a side edge) of a rear substrate.

In some embodiments, the transverse distance between two guide means (1) located on either side of the longitudinal axis of the transport path is variable. The method may therefore comprise at least one step of adjusting this distance between the guide means, for example depending on the size of the substrates on the transport path.

In some embodiments, the method comprises a transverse tensioning step of the substrate (3), performed by means of transverse tension included in the gripping means (2) and controlled by the computer means. This step is generally carried out during or after the closure of the gripping means (2).

As already mentioned in the present application, the invention allows a longitudinal tensioning of the substrates, and this, advantageously, regardless of their size. In some embodiments of the method, the step of tensioning the substrate (3) between two consecutive gripping means (2) is performed by the computer means by applying a decrease Δv of the speed of the gripping means (2) located rearmost relative to the direction of movement of the substrate (3), during a time .DELTA.t, to create a Δ gap d = Δ v × Δ t between the gripping means (2) depending on the physical characteristics of the substrate ( 3), the speed of the gripping means (2) being synchronized again after the time Δt. In some embodiments of the method, the step of tensioning the substrate (3) between two consecutive gripping means (2) is performed by the computer means such that the motorization means or means associated with the gripping means (2) located furthest back from the direction of movement of the substrate (3) exert a force directed in the direction opposite to the direction of movement of the substrate (3), the intensity of the force being parameterized according to the physical characteristics of the substrate (3).

It is possible to have only one front clamp per substrate or a pair of front clamps, but it is preferable to have at least one rear clamp, especially to allow a tensioning, but it would be only for better guidance of the substrates on the transport path. In addition, it is often preferable, especially when the substrates are large (for example from the A4 format), to have at least one clamp (preferably a pair of clips). Thus, in various embodiments, the substrate transport system (3) comprises interposing gripping means located between the front and rear gripping means. In such embodiments, the method comprises a repetition, for each of these intermediate gripping means, of steps (d, d ", e, g and g ') relating to the rear gripping means, in particular in certain modes. embodiment, the substrate transport system comprises n pairs of gripping means (2) for each of the transported substrates, n being greater than or equal to 2, the pairs comprising at least one front pair and one back pair, and possibly n The following description of the steps of the method is made with reference to such embodiments comprising intermediate tongs.

During the first step of the method, noted a, when a substrate (3) leaves an input magazine (30) through the gripper, the position at a given instant and the speed of said substrate (3) are measured by means of a sensor, for example installed within an input store (30), said sensor being able for example and without limitation an optical encoder detecting the transverse edge before substrates (30) emerging from a magazine (30), the front term being defined with respect to the direction of movement of the substrates (3). This positron and speed information is sent to the computing means which in response controls the signal actuating at least one linear motor. The linear motor will thus allow the movement of a first pair of clamps (2), said clamps being located on either side of the transport path of the substrates (3) and having substantially equal longitudinal coordinates, in order to position said pair of clamps (2) in an area near an input magazine (30), said area being called an entry zone (ZE). For example and without limitation, a portion of the substrate (3) is considered to be in the input zone (ZE) as long as less than two pairs of grippers (2) have grasped the longitudinal edges of said substrate portion ( 3). In this input area, no printing is planned.

During the second step, noted b, the first pair of pincers (2) positioned in the preceding step adopts a synchronized movement at a speed adapted to that of the substrate (3) leaving the input magazine (30), positioning in an area of the longitudinal edge near the front portion of the substrate (3). For example and without limitation, each clamp (2) of the first pair grips a front corner of the substrate (3). The positioning and the speed of the pair of clamps (2) are adapted according to the information of speed and position of the substrate (3) recorded by the computer means. Said computer means exploit this speed and position information of the substrate (3) to control the speeds and the synchronization of the clamps (2) as a function of the position of the substrate along the transport path. In some embodiments, the speed of the first pair of clips (2) synchronizes with the substrate speed (3) and is positioned at the front corners of said substrate (3). In other embodiments, the speed of the substrate (3) once output from the input store is zero, the motorization of the first pair of clamps (2) positioning the latter at the front corners of the substrate, before stop.

During the third step, noted c, the opening / closing system (22) of each clamp (2) of the first pair is actuated by the computer means. This results in the closing of the first pair of pliers (2) on the longitudinal edges of the substrate (3), said substrate now being driven by the clamps (2).

During the fourth step, denoted d, a second pair of clamps (2), each clamp being located on either side of the transport path and having substantially equal longitudinal coordinates, is positioned in the input zone ( ZE) by actuation of the linear motor by computer means. The speed of the second pair of clamps (2) is then adapted to the speed of the first pair of clamps (2), the second pair of clamps (2) being positioned in an area near the longitudinal edges of said substrate (3) , excluding at least the front corners, so that the opening / closing mechanism (22) actuates the moving parts (21) said grippers (2) so as to grip the substrate (3) on the longitudinal edges of the substrate (3). From the moment when at least two pairs of clamps (2) have gripped the substrate (3) so as to ensure the convoy, the substrate (3) enters the printing zone (ZI), and the substrate portions (3) included between the clamps (2) can be subjected to printing any pattern.

During the fifth step, noted e, the substrate portion (3) between the two pairs of clamps (2) having gripped said substrate (3) is mechanically tensioned. In embodiments, this step of tensioning the substrate (3) between two consecutive pairs of clamps (2) is performed as follows: the computer means sends a signal to the engine of the pair of clamps (2) located the furthest back from the direction of movement of the substrate (3), so that a decrease in the speed noted Δv is applied to the (x) motor (s) of the pair of the forceps (2) the rearmost . This decrease in speed is applied for a time Δt, controlled by the computer means, in order to create a difference Δ d = Δ v × Δ t between the pairs of clamps (2), this distance Δd depending on the physical characteristics of the substrate ( 3) put in tension. After a time Δt, the speed of the two pairs of clamps (2) is synchronized again by a signal sent by the computer means to the motors of said pairs of clamps (2). In other embodiments, the step of tensioning the substrate between two consecutive pairs of clamps (2) is performed in the following manner: the computer means send a signal to the motor (s) of the pair of tongs (2) located furthest from the direction of movement of the substrate (3), so that the motor (s) of said pair of tongs (2) exert a longitudinal force directed in the direction opposed to the direction of displacement of the substrate (3), the intensity of the force being parameterized using the computer means according to the physical characteristics of the substrate (3).

In some embodiments, force sensors included in the clamps (2) can measure the voltage force existing at the gripping area of the substrate (2). So when the force measured reaches the threshold defined for the substrate (3) in question, the computer means send to the motors ensuring the movement of the clamps (2) along the guides (1) a speed synchronization signal.

In order to convoy the substrates (3) along the workstations of the printing machine, the fourth and fifth steps (d and e) are repeated for the n-2 pairs of clamps (2) remaining. The pairs of clamps (2) are equidistant, and the last pair of clamps (2), located furthest back from the direction of movement of the substrate (3), is positioned in an area of the longitudinal edge of the substrate (3) close to the rear part of the substrate (3). For example and without limitation, the last pair of clamps (2) captures the rear corners of the substrate (3). The convoy and the tensioning of the substrate (3) are thus ensured by the n pairs of clamps (2) having grasped the longitudinal edges of said substrate (3) and motorized on the guides (1) arranged on either side of the transport way.

During the seventh step, denoted g, when the substrate (3) in convoy through the guides (1) and the clamps (2) arrives near an outlet store, the computer means send a signal to the system of opening / closing (22) of the first pair of forceps (2), located furthest forward with respect to the direction of movement of the substrate (3), so that said opening / closing system (22) actuates the movement of the mobile part (21) of the clamps (2) of the first pair, thus releasing the substrate (3), for example and without limitation at the front corners. This part of the substrate (3), between the freed front transverse edge and the next pair of clamps (2) still gripping the substrate, is now located in an area called exit zone (ZS). Part of the substrate (3) is in an exit zone (ZS) when there is a maximum of a pair of clamps (2) gripping the substrate portion (3) at the longitudinal edges. In this output area (ZS), no printing is provided. The larger the number n of pairs of clips (2) included in the substrate transport system (3), the smaller the size of the entry (ZE) and exit (ZS) zones is in favor of the area of printing (ZI). In some embodiments, when the substrate (3) is released from the first pair of clamps (2), the motor controlling the latter pair slowed down until said pair of clamps (2) stop in an area close to an outlet magazine (31).

During the eighth step, noted h, the computer means send, after a time t ₁ depending on the speed and / or the length of the substrate (3), a signal to the opening / closing system (22) of the pair of pliers (2) located just behind the first pair of forceps (2) located furthest forward, so that said opening / closing system (22) actuates the movement of the movable part (21) of the tongs (2) of the second pair. The computer means then send a signal to the motor (s) of the second pair of clamps (2) so that the latter slows down, thus releasing the substrate (3).

This eighth step is repeated for the following n-2 pairs of clamps (2), up to the last pair situated furthest behind the substrate (3) with respect to the direction of movement, for example and in a nonlimiting manner at the rear corners of the substrate (3).

During the ninth step, denoted i, the computer means send to the motors n pairs of clamps (2) a return signal clamps (2) in a storage area of the guides (1), near a store area input (30), the motors stopping when the position detecting means detect that the clamps (2) are present in this storage area.

The method of tensioning and transporting substrates is applicable to a substrate transport system comprising guides (1) forming closed circuits. In these particular embodiments, the steps g to i described above are replaced by the following steps.

In a seventh alternative step, noted g, when the substrate (3) in convoy through the guides (1) and the clamps (2) arrive near an outlet store (31), the computer means send a signal to the system opening / closing (22) of the first pair of grippers (2), located most before the direction of movement of the substrate (3), so that said opening / closing system (22) actuates the displacement of the movable portion (21) of the tongs (2) of the first pair, thereby releasing the substrate ( 3), for example and without limitation at the front corners. This part of the substrate, between the freed front transverse edge and the next pair of gripper still grasping the substrate (3), is now located in the exit zone (ZS). When the substrate is released from the first pair of clamps (2), the motor controlling the latter accelerates the pair of clamps (2), so that the pair of clamps (2) continues its movement along the guides (1). and returns to a storage area near an input store (30). In some embodiments, when the guides (1) are in a plane parallel to the plane of the substrate (3), then the clamps deviate from the substrate (3) in a plane parallel to said substrate (3), just after the tongs (2) have released the substrate.

In an eighth alternative step, denoted h, the computing means send at the end of a time t ₂ depending on the speed and / or the length of the substrate (3), a signal to the opening / closing system (22) of the pair of clamps (2) located just behind the first pair of forceps (2) located furthest forward, so that said opening / closing system (22) actuates the movement of the movable part of the clamps (2) of the second pair. The computer means then sends a signal to the motor (s) of the second pair of clamps (2) so that the latter slows down, thus releasing the substrate (3), then an acceleration signal from the pair of clamps ( 2) is sent to the motors via the computer means, so that said pair of clamps (2) continues its movement along the guides (1) and returns to a storage area near an input store (30). ).

These two steps are repeated for the n-2 pairs of clamps (2) remaining, until the last pair located furthest back of the substrate (3) relative to the direction of movement, for example and without limitation at the level rear corners of the substrate (3).

In some embodiments, the first six steps of the method (a-f) are replaced by the following steps.

In a first alternative step, denoted a, the n pairs of clamps (2) are positioned in the entry zone (ZE) along the guides, the clamps (2) of the same pair being installed on each side and another of the transport path, the clamps (2) being positioned following detection by the detection means of the speed and the position of the substrate (3) leaving an input magazine (30), for example and of non-limiting way the detection of the front transverse edge of the substrate (3).

In a second alternative step, denoted b, the n pairs of clamps (2) positioned in the preceding step adopt a synchronized movement at a speed adapted to that of the substrate (3) coming out of the input magazine (30). The positioning and the speed of the pairs of clamps (2) are adapted according to the information of speed and position of the substrate (3) recorded by the computer means. Said computer means exploit this speed and position information of the substrate (3) to control the speeds and the synchronization of the clamps (2) as a function of the position of the substrate (3) along the transport path. In other embodiments, the speed of the substrate (3) once output from the input store is zero, the motorization of the n pairs of clamps (2) adapting accordingly.

In a third alternative step, noted c, the opening / closing system (22) of each clamp (2) of the n pairs is actuated by the computer means. This results in the closure of all the clamps (2) on the longitudinal edges of the substrate (3), said substrate now being driven by the clamps (2).

In a fourth step, noted d, the n-1 substrate parts (3) between the n pairs of clamps (2) are mechanically tensioned.

In an alternative embodiment, each pair of clamps (2) is substituted by a single clamp (2) adapted to grip the substrate (3), by example over all or part of the width of the lateral edge of the substrate (3). In this case, the method of transporting and tensioning the substrate (3) can be carried out using two clamps (2) per substrate (3), each gripping a lateral edge of the substrate. The positioning of the clamps (2), the adaptation of the speed of the clamps (2) to that of the substrate (3), the gripping of the lateral edges of the substrate (3), the tensioning of the substrate (3), the release of the substrate (3) and the return of the clamps (2) in the storage area can then be performed according to the method described above.

The present application describes various technical features and advantages with reference to the figures and / or various embodiments. Those skilled in the art will appreciate that the technical features of a given embodiment may in fact be combined with features of another embodiment unless the reverse is explicitly mentioned or it is evident that these features are incompatible. In addition, the technical features described in a given embodiment can be isolated from the other features of this mode unless the opposite is explicitly mentioned.

It should be obvious to those skilled in the art that the present invention allows embodiments in many other specific forms without departing from the scope of the invention as claimed. Therefore, the present embodiments should be considered by way of illustration, but may be modified within the scope defined by the scope of the appended claims, and the invention should not be limited to the details given above.

Claims (32)

1. Printing machine comprising a system for the transport of substrates (3), along a transport path oriented along a longitudinal axis from at least one input magazine (30) supplying the printable substrates, to at least one output magazine (31) receiving the substrates, and comprising:

   - movable gripping means (2) each comprising an opening/closing system (22) ensuring release or gripping of substrates (3), said gripping means (2) comprising front and rear gripping means, each grasping either a substrate, front and rear respectively, or a part situated to the front and rear respectively of the same substrate, along the transport path,

   - guide means (1), for guiding the gripping means (2) along the transport path,

   - at least one motorisation means ensuring independent displacement between at least the front gripping means (2) and the rear gripping means (2),

   - the guide means (1), the gripping means (2) and their associated opening/closing system (22) are controlled by computer means,

   - said at least one motorisation means ensures displacement of said gripping means along said guide means (1) between the input (30) and output (31) magazines,

   characterised in that the guide means (1) are spaced apart by a variable transverse distance controlled by the computer means, the computer means control the opening and closing of the gripping means, evaluate the speed and/or position of the movable elements, and lastly deliver the signals for command and control of the motorisation means allowing the system for the transport of substrates (3) to grasp each substrate so as to tension and/or displace substrates (3) of variable sizes along the transport path, without stopping printing.
2. Printing machine comprising a system for the transport of substrates (3) according to the preceding claim, characterised in that it comprises means for detecting the speed and/or position of the gripping means (2) on the transport path, these detection means being controlled by the computer means.
3. Printing machine comprising a system for the transport of substrates (3) according to one of the preceding claims, characterised in that said at least one motorisation means comprises motor means equipping the gripping means (2).
4. Printing machine comprising a system for the transport of substrates (3) according to the preceding claim, characterised in that each gripping means (2) comprises at least one motor means ensuring displacement thereof along the guide means (1).
5. Printing machine comprising a system for the transport of substrates (3) according to one of claims 1 and 2, characterised in that said at least one motorisation means comprises at least one passive part equipping the gripping means (2) and at least one active part equipping the guide means (1).
6. Printing machine comprising a system for the transport of substrates (3) according to one of claims 1 to 5, characterised in that it comprises at least two guide means (1) on which the gripping means (2) are displaced.
7. Printing machine comprising a system for the transport of substrates (3) according to the preceding claim, characterised in that said at least two guide means (1) comprise at least one guide means on which the front gripping means (2) are displaced and at least one guide means on which the rear gripping means (2) are displaced.
8. Printing machine comprising a system for the transport of substrates (3) according to one of the preceding claims, characterised in that it comprises pairs of gripping means (2), each comprising two gripping means (2) situated on the same side, front or rear, of the same substrate, the displacement of one pair of gripping means (2) being ensured by the same motorisation means, along at least one guide means (1).
9. Printing machine comprising a system for the transport of substrates (3) according to any one of the preceding claims, characterised in that the gripping means (2) controlled by the computer means grasp each substrate (3) at least in a zone close to the four corners of the substrate (3).
10. Printing machine comprising a system for the transport of substrates (3) according to any one of the preceding claims, characterised in that the gripping means (2) comprise means for transverse tensioning of the substrate (3), said transverse tensioning means being controlled by the computer means.
11. Printing machine comprising a system for the transport of substrates (3) according to any one of the preceding claims, characterised in that a support for substrates (3), with a position adjustable along an axis perpendicular to the substrate (3) so as to optimise the distance from the substrate (3) to the print heads of the printing machine, is integrated within the printing machine between the input magazine (30) and output (31) magazines.
12. Printing machine comprising a system for the transport of substrates (3) according to any one of the preceding claims, characterised in that it comprises means for detecting the speed and/or position of the substrates (3) connected to the computer means.
13. Printing machine comprising a system for the transport of substrates (3) according to any one of the preceding claims, characterised in that the guide means (1) comprise guides disposed on either side of the longitudinal axis of the transport path of the substrates (3).
14. Printing machine comprising a system for the transport of substrates (3) according to claim 13, characterised in that each guide (1) forms a closed circuit.
15. Printing machine comprising a system for the transport of substrates (3) according to the preceding claim, characterised in that the guides (1) are disposed in a plane perpendicular to the plane of the substrates (3).
16. Printing machine comprising a transport system according to claim 14, characterised in that the guides (1) are disposed in a plane parallel to the plane of the substrates (3).
17. Printing machine comprising a system for the transport of substrates (3) according to one of claims 4 to 16, characterised in that said active part of the motorisation means comprises at least one linear motor.
18. Printing machine comprising a system for the transport of substrates (3) according to the preceding claim, characterised in that said at least one linear motor is installed on at least one rail parallel to the guide means (1).
19. Printing machine comprising a system for the transport of substrates (3) according to one of the preceding claims, characterised in that the gripping means (2) comprise a movable part (21) allowing gripping or release of the substrates (3) and situated facing the obverse of the substrate (3), the obverse being the printable face facing the print heads.
20. Printing machine comprising a system for the transport of substrates (3) according to one of claims 1 to 18, characterised in that the gripping means (2) comprise a movable part (21) allowing gripping or release of the substrates (3) and situated facing the reverse of the substrate (3), defined as the face opposite the one facing the print heads.
21. Printing machine comprising a system for the transport of substrates (3) according to one of the preceding claims, characterised in that each gripping means (2) is adapted to grasp a side edge of the substrate (3).
22. Method for the tensioning and transport of substrates (3) along a transport path, implemented by a system for the transport of substrates (3) comprising:

    - movable gripping means (2) each comprising an opening/closing system (32) ensuring release or gripping of substrates (3), said gripping means (2) comprising front and rear gripping means, each grasping either a substrate, front and rear respectively, or a part situated to the front and rear respectively of the same substrate, along the transport path,

    - guide means (1), for guiding the gripping means (2) along the transport path,

    - at least one motorisation means ensuring independent displacement between at least the front gripping means (2) and the rear gripping means (2),

    - the guide means (1), the gripping means (2) and their associated opening/closing system (22) are controlled by computer means,

    - said at least one motorisation means ensures displacement of said gripping means along said guide means (1) between the input (30) and output (31) magazines,

    characterised in that the method comprises the following steps:

    a) positioning in a zone close to the input magazine (30), by said at least one motorisation means actuated by the computer means, of at least one first gripping means (2), called the front gripping means, following detection of the front transverse edge of a substrate (3) relative to the direction of displacement,

    b) displacement of the front gripping means (2), at a speed adapted to that of the substrate (3), and positioning of said gripping means (2) in a zone close to the front part of the substrate (3), the computer means using the data on speed and position of the substrate (3) to control the speeds and synchronisation of the gripping means (2) as a function of the position of the substrates (3) along the transport path,

    c) closing of the front gripping means (2) by the opening/closing system (22) on at least one edge of the substrate (3), said gripping means (2) henceforth driving the substrate (3),

    d) positioning, then synchronised displacement, at a speed adapted to that of the front gripping means (2), and closing on at least one edge of the substrate (3), of at least one second gripping means (2), called the rear gripping means,

    e) tensioning of the substrate (3) situated between the front and rear gripping means (2),

    f) opening of the opening/closing system (22) of the front gripping means (2) when the position of the latter is situated in a zone close to the output magazine (31) of the printing machine,

    g) opening of the opening/closing system (22) of the rear gripping means, at the end of a time t₁ dependent on the distance, before opening, between the front and rear gripping means (2), followed by deceleration of said gripping means (2) in order to release the substrate (3),

    h) return of the gripping means (2) to a storage zone close to the input magazine (30).
23. Method for the tensioning and transport of substrates (3) according to the preceding claim, characterised in that the method is adapted to guide means (1) operating in a closed circuit, the steps f) to h) being replaced by the following steps:

    f) opening of the opening/closing system (22) of the front gripping means (2), followed by acceleration of said front gripping means (2), so that they continue their displacement on the guide means (1) and return to a storage zone close to the input magazine (30),

    g') opening of the opening/closing system (22) of the rear gripping means, at the end of a time t₂ dependent on the distance, before opening, between the front and rear gripping means (2), followed by deceleration of the rear gripping means in order to release the substrate (3), then acceleration so that the rear gripping means (2) continue their displacement on each guide (1) and return to the storage zone.
24. Method for the tensioning and transport of substrates (3) according to one of claims 22 or 23, characterised in that the steps a) to e) are replaced by the following steps:

    a") positioning of all of the gripping means (2) along the same substrate, in a zone close to the input magazine (30) simultaneously with detection of the front edge of a substrate (3),

    b") synchronised displacement of the gripping means (2) at a speed adapted to the substrate (3), controlled by the computer means using the data on speed and position of the substrate (3),

    c") closing of the gripping means (2) by the opening/closing system (22), second gripping means (2) henceforth driving the substrate (3),

    d") tensioning of the substrates (3) by the gripping means (2).
25. Method for the tensioning and transport of substrates (3) according to one of claims 22 to 24, characterised in that at least some of the gripping means (2) grasp the substrates on their side edges.
26. Method for the tensioning and transport of substrates (3) according to the preceding claim, characterised in that the system for the transport of substrates (3) comprises intermediate gripping means situated between the front and rear gripping means, and in that the method comprises a repetition, for each of these intermediate gripping means, of steps (d, d", e, g and g') concerning the rear gripping means.
27. Method for the tensioning and transport of substrates (3) according to one of claims 22 to 26, characterised in that the system for the transport of substrates comprises n pairs of gripping means (2) for each of the substrates transported, n being greater than or equal to 2, the pairs comprising at least one front pair and one rear pair and, if occasion arises, n-2 intermediate pairs.
28. Method for the tensioning and transport of substrates (3) according to one of claims 22 to 27, characterised in that the transverse distance between two guide means (1) situated on either side of the longitudinal axis of the transport path is variable.
29. Method for the tensioning and transport of substrates (3) according to one of claims 22 to 28, characterised in that a step of transverse tensioning of the substrate (3), performed by transverse tensioning means included in the gripping means (2) and controlled by the computer means, is implemented following the closing of the gripping means (2).
30. Method for the tensioning and transport of substrates (3) according to one of claims 22 to 29, characterised in that the step of tensioning the substrate (3) between two consecutive gripping means (2) is performed by the computer means by applying a decrease Δv in the speed of the gripping means (2) situated the furthest to the rear relative to the direction of displacement of the substrate (3), for a time Δt, in order to create a difference Δd = Δv x Δt between the gripping means (2) dependent on the physical characteristics of the substrate (3), the speed of the gripping means (2) being synchronised again at the end of the time Δt.
31. Method for the tensioning and transport of substrates (3) according to one of claims 22 to 30, characterised in that the step of tensioning the substrate (3) between two consecutive gripping means (2) is performed by the computer means in such a way that the motorisation means associated with the gripping means (2) situated the furthest to the rear relative to the direction of displacement of the substrate (3) exert a force directed in the direction opposite the direction of displacement of the substrate (3), the intensity of the force being configured as a function of the physical characteristics of the substrate (3).
32. Method for the tensioning and transport of substrates (3) according to one of claims 22 to 31, characterised in that the computer means control the opening and closing of the gripping means (2), evaluate the speed of displacement of the movable elements, and deliver the signals for command and control of the linear motors.

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