EP2512807B1 - Hot-stamping printing device - Google Patents

Description

The present invention relates to a device for printing sheet-shaped elements by hot stamping.

The invention finds a particularly advantageous, but not exclusive, application in the field of packaging for the luxury industry.

It is known to print texts and / or patterns by hot stamping, that is to say to deposit by pressure on a sheet-shaped support, the colored or metallized film from one or more strips to stamp. In the industry, such a transfer operation is usually carried out by means of a vertical platen press, in which the printing media are introduced sheet-by-sheet, while the supply of strips to be stamped is effected in a manner keep on going.

In a standard platen press, stamping takes place between a plate fixed horizontally, and a platen movably mounted in displacement in a back and forth vertical movement. This type of press being generally automated, means of transport are provided to bring one by one each sheet between the plates. In practice, it is usually a series of gripper bars each of which, in turn, grip a sheet at its front edge, before pulling it between the two decks when the latter are sufficiently spaced apart.

However, this type of device has the disadvantage of guaranteeing good print quality only at low speeds, since a wrinkling phenomenon appears as soon as the stamping speed becomes too much. In its deceleration movement before coming to rest between the two plates of the press, the rear portion of the sheet tends to catch up with the front portion which is driven by the clip bar. This has the effect of substantially deform the flatness of the sheet, which increases all the risk of crease when the platen comes to press against the fixed platen.

To overcome this difficulty, it has been thought to use a blower to maintain the sheet substantially flat when it stops between the two plates of the press. The idea is to position this blower downstream of the press, and to direct its air jet under pressure in the plane of the sheet so as to slow it down during the deceleration phase. Such a device is known to EP0739722-A1 . This being so, if such an arrangement actually makes it possible to increase the rate of stamping, the fact remains that it also has its own limits.

Also, the technical problem to be solved by the object of the present invention is to provide a device for printing sheet-shaped elements, comprising on the one hand a platen press able to deposit by hot stamping on each sheet, colored or metallized film from at least one strip to stamp, and secondly means of transport capable of introducing one after another each sheet in the platen press by pulling said sheet by its front edge, printing device that would avoid the problems of the state of the art including providing a significantly increased operating rate.

The solution to the technical problem posed consists, according to the present invention, in that the device printing device further comprises means adapted to partially retain each sheet by its rear portion during the introduction phase of said sheet in the platen press, where the retaining means comprise a suction member, which is positioned upstream platen press, and which is adapted to cooperate by sliding contact with the rear portion of each sheet being introduced into said platen press.

It is understood that throughout this text, the term sheet refers very generally any sheet-like printing medium, such as for example sheets of cardboard, paper, plastic, etc.

It is also important to specify that the fact that the retaining means are able to partially retain each sheet means that they are able to maintain the rear portion of said sheet without immobilizing it, letting it slide gradually as and as the means of transport pulls it.

In any event, the invention as thus defined has the advantage of being able to operate at rates higher than those of its counterparts in the state of the art. The presence of the retaining means makes it possible to control the attitude of the sheet at deceleration, and thus to ensure a virtually permanent retention of said sheet during its entire introduction phase in the platen press. The transport speed of the sheets can thus be increased significantly without the risk of wrinkling, which ultimately allows to achieve unmatched operating rates.

• La figure 1 illustre une machine de dorure utilisant un dispositif d'impression conforme à l'invention.
• La figure 2 montre en détail le dispositif d'impression dont est pourvue la machine de dorure objet de la figure 1.
• La figure 3 est une coupe transversale de l'organe d'aspiration qui équipe le dispositif d'impression de la figure 2.

The following description, given as a non-limiting example, is intended to better understand what the invention is and how it can be done. It is given with reference to the appended drawings in which:

• The figure 1 illustrates a gilding machine using a printing device according to the invention.
• The figure 2 shows in detail the printing device which is provided the gilding machine object of the figure 1 .
• The figure 3 is a cross-section of the suction organ that equips the printing device of the figure 2 .

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

The figure 1 represents a gilding machine 1 for the customization of cardboard packaging for the luxury industry. This processing machine 1 is conventionally composed of several workstations which are juxtaposed but interdependent one by one to form a unitary unit. Thus, there is an introduction station 100, a margin table 200, a printing device 300, a belt stamping and waste disposal station 400, and a receiving station 500.

As can be seen in this first schematic representation, the introduction station 100 is supplied by means of a pallet 110 on which are stacked a plurality of 10. These sheets are successively removed from the top of the stack by a suction gripping member capable of sending them to the directly adjacent margin table 200. To facilitate the intervention of the gripping member, the pallet 110 is placed on a lifting mechanism ensuring that the top of the stack is always positioned at a substantially constant height. It should be noted that the lifting mechanism and the gripping member are quite standard, and it is therefore for the sake of clarity that they have not been represented here.

At the level of the margin table 200, the sheets 10 are webbed directly by the suction grip member, that is to say placed one after the other so as to partially overlap. The entire web is moved along an inclined plate 210 towards the printing device 300. For this purpose, a conventional belt transport system is used which again has not been shown for obvious reasons for clarity. At the end of the web, the head sheet is systematically accurately positioned by means of front and side cleats.

The workstation located immediately after the margin table 200 is therefore the printing device 300 which is the subject of the invention. This is firstly provided with a platen press 310 which is capable of depositing on each sheet 10, by hot stamping, the colored or metallized film which is issued from a single stamping strip 320 in this embodiment. exemplary embodiment. The printing device 300 is also provided with unwinding means 330 which are intended to cause the tape to stamp 320 inside the printer. the platen press 310, then extracting it in order to evacuate it as waste. Finally, the printing device 300 comprises transport means 340 which are responsible for introducing the sheets 10 one by one inside the platen press 310.

Downstream of the printing device 300, there is a station 400 having a dual function, namely the supply of tape to punch 320 and waste disposal. In this extremely schematic representation, the supply aspect is materialized by the simple illustration of a coil 410 serving as support for the stamping strip 320. The disposal of waste is symbolized by a recovery tank 420 which is loaded recovering the used stamping tape 320, that is, the stamped portion of the tape inside the platen press 310.

The process of processing the sheets 10 in the gilding machine 1 is completed in the receiving station 500 whose main function is to repackage the sheets 10 in a stack on a pallet transport 510. For this, the transport means 340 are arranged to automatically release each sheet 10 when the latter is found at the right of this new stack. The sheet 10 then falls squarely on the top of the stack. To facilitate stacking, the pallet 510 is placed on a lifting mechanism ensuring that the top of the stack is always positioned relatively close to the transport means 340. This being said, it is observed here that the stack is shown in the low position, c that is, it is ready to be evacuated.

The gilding machine 1 is relatively large, it is also equipped with a platform 600 working to elevate those responsible for its operation or maintenance.

As can be seen more clearly in the figure 2 , the printing device 300 is first provided with a platen press 310. In this particular embodiment, chosen solely by way of example, the stamping takes place between an upper heating base 311 which is fixed, and a lower bed base 312 which is mounted movably moving in a vertical reciprocating motion. The upper heating base 311 supports a frame 313 under which are fixed pictures not visible here, while the lower bed base 312 carries a stamping plate 314 on which are fixed also not visible stamping counterparts.

The printing device 300 is also provided with unwinding means 330 for feeding the block platen press 310 to stamp 320. In a very conventional manner, these unwinding means 330 comprise a reel holder 331 with respect to which the spool 410 is rotatably mounted, a feed shaft 332 associated with pressing rollers 332a, a mark detector 333, a series of deflection shafts 334a, 334b, 334c, a strip breaking controller 335, a cutting shaft voltage 336 associated with pressure rollers 336a, a belt return 337, a separator guide 338, and exhaust brushes 339.

In addition to these unwinding means 330, introduction means 350 are also provided to ensure the establishment of the band stamp 320, and in particular its passage through the platen press 310. For this, the means of 350 have an insertion bar 351 which is mounted transversely movable in translation between the two springs 311, 312, and more generally around the upper heating bed base 311. Just like the tape unwinding means 330, the band introduction means 350 being perfectly known from the state of the art, their operation will not be described. more here.

Finally, the printing device 300 comprises transport means 340 for individually moving each sheet 10 from the outlet of the margin table 200 to the receiving station 500, including inside the platen press. 310.

As can be seen on the figure 1 , and again very conventional manner, the transport means 340 use a series of clamp bars 341 which are movably mounted in transverse translation by means of two chain trains 342 arranged laterally on each side of the gilding machine 1 Each chain train 342 traverses a loop which allows the gripper bars 341 to follow a path successively passing through the platen press 310, the supply and evacuation station 400 and the receiving station 500.

Specifically, each clamp bar 341 travels a path in a horizontal passage plane between a drive wheel 343 and a return wheel 344, and a return path guided by rollers (not visible) in the upper part of the Gilding machine 1. Once brought to the level of the drive wheel 343, each clamp bar 341 is then able to grip a new sheet 10 in accordance with the figure 2 .

This figure 2 shows, moreover, that each clamp bar 341 consists of a transverse bar 345 on which are mounted a plurality of clamps 346 which are designed to be able to grip the front edge of a same sheet 10 simultaneously. It is also observed that each clamp bar 341 is coupled to the two chain trains 342 via respectively the two ends of its crossbar 345.

According to the object of the present invention, the printing device 300 further comprises means 360 which are able to partially retain each sheet 10 by its rear portion, and throughout the introduction phase of said sheet 10 in the platen press 310.

According to a feature of the invention, the retaining means 360 are able to maintain the rear portion of each sheet 10 substantially in the plane of displacement of its front edge, during the introduction phase of said sheet 10 in the press. platinum 310.

According to the object of the present invention, the retaining means 360 comprise a suction member 361 which is positioned upstream of the platen press 310, and which is able to cooperate by sliding contact with the rear portion of each sheet. 10 being introduced into said platen press 310.

According to a presently preferred embodiment of the invention, the suction member 361 is fixed, and it is positioned closer to the path of movement which is followed by the front edge of each sheet 10 just before its introduction. effective inside the platen press 310. Such an implantation allows the suction member 361 to be systematically at the contact of any sheet 10 being introduced into the platen press 310. It also has the advantage of ensuring a positioning of the sheet substantially parallel to the internal faces of the bed frames 311, 312.

In this exemplary embodiment, each sheet 10 is pulled by a gripper bar 341 when it is introduced into the platen press 310. This concretely means that the suction member 360 is positioned in the direct vicinity of the displacement path which is followed by said clamp bar 341 when approaching the platen press 310.

But according to an alternative embodiment not shown, the suction member 361 could also be mounted movably in displacement between an active position and a passive position. The assembly would then be arranged in such a way that, in the active position, the suction member 361 is positioned as close as possible to the path of movement followed by the front edge of each sheet 10 just before it is introduced into the press. platinum 310, and that in the passive position, it is placed at a distance from said path of movement. Of course, the printing device 300 would then comprise means capable of moving the suction member 361 from the passive position to the active position when the sheet 10 is about to be introduced into the platen press, and vice versa. moving said suction member 361 from the active position to the passive position when said sheet 10 is extracted from said platen press 361.

According to a feature of this embodiment, the platen press 310 being able to stamp each sheet 10 between a fixed plate and a movable plate, the suction member 361 is integral with the movable stage; said movable platen forming displacement means.

According to a particularly advantageous embodiment, the hot stamping of each sheet 10 being formed on a given face, said face to be printed, the suction member 361 is positioned on the opposite side to said face to be printed; said sheet 10 being considered at the approach of the platen press 310. It is however understood that it remains entirely possible that the suction member 361 is implanted on the same side as the face to be printed.

According to a preferred embodiment, the suction member 361 operates continuously. This being the case, it is perfectly possible to operate the suction member 361 in a discontinuous manner. In such a case, the printing device 300 will be arranged in such a way that the suction member 361 is activated as soon as the front edge of a sheet 10 has passed perpendicular thereto, and that it is deactivated when that the back of said sheet 10 is no longer in contact with said suction member 310.

Particularly advantageously, the suction member 361 acts over substantially the entire width of each sheet 10 introduced into the platen press 310.

According to a presently preferred embodiment of the invention, the suction member 361 is of Bernoulli type, that is to say an apparatus provided with at least one suction hole at the level of which one creates a depression (arrow f1) by Venturi effect, by propelling pressurized air into an exhaust duct (arrows f2) which communicates laterally with the hole suction, and which is provided with a constriction upstream of said suction hole.

In the embodiment shown in figure 3 , the suction member 361 is constituted by a shelf 362 through which is formed longitudinally a main channel 363 for supplying air under pressure, which communicates with at least one secondary channel 364 extending transversely and opening to the rear of the shelf 362 via an individual exhaust port 365 (arrow f3). Furthermore, each secondary channel 364 further communicates with a suction port 366 which opens at the tablet face 362 intended to come into contact with each sheet 10 introduced into the platen press 310. Finally, each channel secondary 364 has a constriction 367 which is placed just upstream of the suction port 366. It is understood here that the terms "longitudinally" and "transversely" are related to the body of the tablet 362, while the term "back" is conceived with respect to the direction of movement of the sheets 10 (arrow f4).

Particularly advantageously, each escape orifice 365 is oriented in opposition with respect to the platen press 310, as well as with respect to the plane of movement of each sheet 10 at the approach of said platen press 310. The objective here is to direct each air exhaust stream (arrow f3) in a direction not disturbing the attitude of the sheets 10 when introduced into the platen press 310.

According to another advantageous characteristic, each suction orifice 366 has a conical shape opening on the outside, particularly at the of its portion 367 closest to the platen press 310. The objective here is to prevent any corner of the front edge of the sheet 10 to come into a suction port 366 of the tablet 362 when said sheet 10 approaches the platen press 310.

Of course, the invention more generally relates to any processing machine 1 of sheet-shaped elements 10, which comprises at least one printing device 300 as previously described.

It should be noted that in the context of the invention, the concept of processing machine covers a very large number of embodiments because of the modular structure of these sets. Depending on the number, the nature and the arrangement of the workstations used, it is indeed possible to obtain a multitude of different processing machines.

It is also important to underline that there are other types of workstations than those previously mentioned in the context of the description of the gilding machine 1. For example, here we are thinking of cutting stations, separation stations poses, waste ejection stations, tape loading stations, etc. Finally, it is understood that the same processing machine may very well be equipped with several stations of the same type.

Claims (13)

1. Device (300) for printing sheet elements (10), comprising a platen press (310) capable of applying, by means of hot stamping, coloured or metallised film onto each sheet (10) from at least one stamping strip (320), transport means (340) capable of introducing each sheet (10) into the platen press (310) one after the other by pulling said sheet (10) by its front edge, as well as means (360) capable of partially holding each sheet (10) by its rear portion during the phase of introducing said sheet (10) into the platen press (310), characterised in that the holding means (360) comprise a suction member (361) that is positioned upstream of the platen press (310) and is capable of cooperating by sliding contact with the rear portion of each sheet (10) introduced into said platen press (310).
2. Printing device (300) according to claim 1, characterised in that the holding means (360) are capable of holding the rear portion of each sheet (10) substantially in the plane of movement of the front edge thereof during the phase of introducing said sheet (10) into the platen press (310).
3. Printing device (300) according to either claim 1 or claim 2, characterised in that the suction member (361) is fixed, and in that said member is positioned as close as possible to the movement path followed by the front edge of each sheet (10) immediately before the introduction thereof into the platen press (310).
4. Printing device (300) according to either claim 1 or claim 2, characterised in that the suction member (361) is mounted so as to be movable between an active position in which it is positioned as close as possible to the movement path followed by the front edge of each sheet (10) immediately before the introduction thereof into the platen press (310), and a passive position in which it is positioned at a distance from said movement path, and in that the printing device (300) further comprises means capable of moving the suction member (361) from the passive position to the active position when the sheet (10) is ready to be introduced into the platen press (310) and, conversely, to move said suction member (361) from the active position to the passive position when said sheet (10) is extracted from said platen press (310).
5. Printing device (300) according to claim 4, characterised in that, the platen press (310) being capable of stamping each sheet (10) between a fixed platen and a movable platen, the suction member (361) is rigidly connected to the movable platen, said movable platen forming movement means.
6. Printing device (300) according to any of claims 1 to 5, characterised in that, the hot stamping of each sheet (10) being carried out on a given face, called the printing face, the suction member (361) is positioned on the side opposite said printing face when said sheet (10) is viewed approaching the platen press (310).
7. Printing device (300) according to any of claims 1 to 6, characterised in that the suction member (361) operates continuously.
8. Printing device (300) according to any of claims 1 to 6, characterised in that the suction member (361) operates discontinuously, in that said member is activated as soon as the front edge of a sheet (10) passes its perpendicular line, and in that said member is deactivated as soon as the rear of said sheet (10) is no longer in contact with said suction member (361).
9. Printing device (300) according to any of claims 1 to 8, characterised in that the suction member (361) acts on substantially the entire width of each sheet (10) being introduced into the platen press (310).
10. Printing device (300) according to any of claims 1 to 9, characterised in that the suction member (361) is formed by a tablet (362), through which a main pressurised air supply channel (363) is longitudinally arranged, which channel communicates with at least one secondary channel (364) extending transversely and opening at the rear of the tablet (362) via an individual discharge orifice (365), and in that each secondary channel (364) on the one hand also communicates with a suction orifice (366) that opens at the face of the tablet (362) that is intended to come into contact with each sheet (10) being introduced into the platen press (310) and, on the other hand, comprises a restriction (367) that is positioned immediately upstream of said suction orifice (366).
11. Printing device (300) according to claim 10, characterised in that each discharge orifice (365) is oriented so as to face away from the platen press (310) and the plane of movement of each sheet (10) approaching said platen press (310).
12. Printing device (300) according to either claim 10 or claim 11, characterised in that each suction orifice (366) has a conical shape which opens outwards, particularly at the portion (367) thereof closest to the platen press (310).
13. Machine (1) for processing sheet elements (10), characterised in that it comprises at least one printing device (300) according to any of the preceding claims.

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