EP2620281B1 - A printing assembly comprising a device for loading printing plates onto a plate cylinder of a rotary offset printing press - Google Patents

Description

The present invention relates to a device for loading printing plates on a plate cylinder of an offset rotary press.

An offset rotary press comprises printing units, for example for printing a web of continuous material. Each printing group is intended to print a pattern on one side of the tape.

Each printing unit comprises a plate cylinder (or forme cylinder) carrying printing plates on which patterns to be printed are drawn and a blanket cylinder (or transfer cylinder) carrying a blanket. The blanket cylinder and the plate cylinder rotate against each other, the blanket being in contact with the printing plates. The blanket is also in contact with the strip of material. The blank takes the ink from the plates and transfers it onto the strip of material by printing the patterns.

The printing plates are removably attached to the plate cylinder. Each printing plate is flexible so as to be wound on the plate cylinder. Each printing plate comprises a front edge and a rear edge parallel to the axis of the plate cylinder and side edges provided to extend along the circumference of the plate cylinder. Each printing plate is fixed on the plate cylinder by its front edge and its rear edge.

Printing plates are loaded onto the plate cylinder for each print job. It is possible to load the printing plates by means of an automatic loading device guiding the printing plates by their lateral edges by means of lateral guides during the winding on the circumference of the printing plate. plate cylinder.

Nevertheless, with such a device for loading printing plates, the lateral edges of the printing plates must have a precise geometry and, when using printing plates of different widths, for example in case of change of width, it is necessary to adapt the position of the lateral guides.

EP 1 787 813 discloses a printing plate loading device.

One of the objects of the invention is to provide a printing assembly comprising a simple plate loading device and which allow the loading of plates of different widths.

For this purpose, the invention provides a printing assembly according to claim 1. Optional features are in claims 2 to 10.

The invention also relates to an offset rotary press according to claim 11 and a method for loading a printing plate according to claim 12.

• la Figure 1 est une vue schématique en perspective d'une plaque d'impression ;
• la Figure 2 est une vue schématique partielle en coupe d'un cylindre porte-plaque sur lequel est fixée une plaque d'impression ;
• la Figure 3 est une vue schématique partielle en perspective du cylindre porte-plaque de la Figure 2 et d'un dispositif de chargement des plaques d'impression sur le cylindre porte-plaque ;
• la Figure 4 est une vue schématique partielle en coupe illustrant le chargement d'une plaque d'impression sur le cylindre porte-plaque à l'aide du dispositif de chargement ;
• la Figure 5 est une vue schématique de dessus du cylindre porte-plaque, du dispositif de chargement et de jeux de plaques d'impression prévues pour être chargés sur le cylindre porte plaque à l'aide du dispositif de chargement.

The invention and its advantages will be better understood on reading the description which follows, given solely by way of example and with reference to the appended drawings, in which:

• the Figure 1 is a schematic perspective view of a printing plate;
• the Figure 2 is a partial schematic sectional view of a plate cylinder on which is fixed a printing plate;
• the Figure 3 is a partial schematic perspective view of the plate cylinder of the Figure 2 and a device for loading the printing plates on the plate cylinder;
• the Figure 4 is a partial schematic sectional view illustrating the loading of a printing plate on the plate cylinder with the aid of the loading device;
• the Figure 5 is a schematic top view of the plate cylinder, loading device and sets of printing plates intended to be loaded on the plate cylinder with the aid of the loading device.

The printing plate 2 shown on the Figure 1 extends in a direction of extension L and comprises a front edge 6 folded and a rear edge 8 folded. The leading edge 6 and the trailing edge 8 extend transversely to the extension direction L. The printing plate 2 comprises two opposite parallel side edges 10. The lateral edges 10 extend in the direction of extension L.

The front edge 6 is provided with a front notch 12. The rear edge 8 is provided with a rear notch 14. The rear notch 14 is aligned with the front notch 12 in the direction of extension L.

As illustrated on the Figure 2 the flexible printing plate 2 is wound and fixed on a plate cylinder 16 of a rotary press 18.

The printing plate 2 is fixed on the plate cylinder 16 by inserting each of the front edge 6 and the rear edge 8 into a groove 20 of the plate cylinder 16 extending along the axis XX of the cylinder holder. plate 16.

The printing plate 2 is positioned laterally along the X-X axis of the plate cylinder 16 by engaging the front notch 12 with an indexing pin 22 in the groove 20.

The leading edge 6 is hooked on an edge of the groove 20 and the trailing edge 8 is inserted into the groove 20 by being retained by a locking device 24 to lock the printing plate 2 on the plate cylinder 16.

The locking device 24 comprises at least one hook 26 mounted on a clamping bar 28 rotatable about a bar axis YY parallel to the axis XX of the plate cylinder 16. The rotation of the locking bar 28 makes it possible to release the hook 28 from the rear edge 8 to release the printing plate 2 or engage the hook 28 with the rear edge 8 to lock the printing plate 2. On the Figure 2 the hook 26 is set back from the cutting plane and offset from the rear notch 14

In a plate cylinder to a printing plate per turn, the plate cylinder comprises a single fixing groove and the leading edge and the trailing edge are fixed in the same groove. In a plate cylinder having N plates per revolution, N being greater than or equal to 2, the plate cylinder comprises N grooves, and the leading edge and the trailing edge of each printing plate are fixed in a respective groove.

As illustrated on Figures 3 and 4 , the loading device 30 comprises a magazine 32 for receiving printing plates 2 and transferring the printing plates 2 to the plate cylinder 16. The magazine 32 can receive several printing plates 2 side by side along of the plate cylinder 16.

The magazine 32 includes an outlet 34 extending along the plate cylinder 16 along the axis XX of the plate cylinder 16. The magazine 32 is configured such that printing plates 2 received in the magazine 32 are placed in simple support in the magazine 32 and can slide from the magazine 32 in a loading direction C, through the outlet 34, and wind up on the plate cylinder 16.

The loading direction C is substantially orthogonal to the X-X axis of the plate cylinder 16.

The magazine 32 comprises guide rails 36. The guide rails 36 are parallel to each other and to the loading direction C. They are rectilinear and extend towards the outlet 34.

The guide rails 36 are configured to cooperate with the notches 12 and rear 14 ( Figure 4 ) respectively front 6 and rear 8 edges of printing plates 2 received in the magazine 32 to guide the printing plates 2 laterally during their transfer to the plate cylinder 16.

The height of the guide rails 36 is less than the height of the notches 12, 14. When the printing plate is placed in the magazine in the standby position, the guide rails 36 do not interfere with the bottom of the notches 12 , 14 and the printing plate 2 rests in linear contact by its front edges 6 and rear 8. This preserves the printing plate 2 possible damage.

Each guide rail 36 is aligned with a respective relative indexing pin 22 of the plate cylinder 16 so that the front notch 12 of a leading edge 6 of a printing plate 2 guided by the guide rail 36 and coming out of the magazine 32 comes into engagement with the indexing pin 22. A pin 22 is in alignment with each guide rail 36. Each guide rail 36 and the corresponding pin 22 are located in the same plane perpendicular to the axis XX of the plate cylinder 16.

The loading device 30 comprises pushers 38 movable to push printing plates received in the magazine 32 along the guide rails 36 to the outlet 34.

In the illustrated example, the magazine 32 comprises a horizontal support plate 40 adapted to receive the printing plates placed on an upper face 40A of the support plate 40. The support plate 40 has an output edge 42 which extending along the outlet 34 of the magazine 32.

The guide rails 36 are in the form of bars fixed on the upper face 40A and extending perpendicularly to the front edge 42. A printing plate 2 placed on the support plate 40 with its front notches 12 and rear 14 engaged on a guide rail 36 can slide towards the output edge 42.

The pushers 38 are movable through slots 44 ( Figure 3 ) of the support plate 40 to push the printing plates 2 received on the support plate 40 towards the output edge 42.

As illustrated on the Figure 4 the magazine 32 comprises at least one actuator 48 for controlling the movement of the pushers 38. Each actuator controls the movement of one or more pushers 38.

The operation of the loading device 30 is described below with reference to the Figure 4 .

In operation, initially printing plates are placed in the magazine 32 side by side. Each printing plate 2 is placed in such a way that its front notch 12 is engaged on the guide rail 36 opposite the pin 22 intended to engage in the notch before 12. The corresponding rear notch 14 is also engaged. on the same guide rail 36.

The plate cylinder 16 is oriented such that the groove 20 is substantially vertically below the outlet 34 of the magazine 32. The hooks 26 are initially in the unobstructed position to avoid interfering with the insertion of the front edge 6 and the rear edge 8 in the fixing groove 20.

To load the printing plate 2 on the plate cylinder 16, the pushers 38 are advanced (arrow F1) so as to push the printing plate 2 from the rear towards the front towards the exit 34.

When the leading edge 6 of the printing plate 2 leaves the magazine 32, it falls by gravity and fits into the groove 20 by engaging the edge of the groove 20. The notch before 12 goes into taken with the corresponding indexing pin 22 which is aligned with the guide rail 36. The printing plate 2 is positioned laterally along the plate cylinder 16 precisely.

The plate cylinder 16 is rotated (Arrow F2). The plate cylinder 16 drives the printing plate 2 until the trailing edge 8 leaves the magazine 32 and in turn falls into the fixing groove 20.

The hooks 26, initially in the disengaged position, are moved into the engaged position to lock the printing plate on the plate cylinder 16.

Thus, according to a method of loading a printing plate on a plate cylinder, the printing plate 2, transferring the printing plate 2 from the magazine 32 to the plate cylinder 16 by guiding the plate printing 2 along a guide rail 36 cooperating with the front notch 12 of the leading edge 6, the guide rail 36 being aligned with a pin 22 for indexing the plate cylinder 16.

Different sets of printing plates can be loaded onto the plate cylinder 12 by means of the loading device 30.

The Figure 5 schematically shows a top view of the plate cylinder 16, the loading device 30, and sets of printing plates A, B, C, D adapted to be loaded on the plate cylinder 16 with the aid of FIG. loading device 30.

Each set of printing plates A, B, C, D comprises a plurality of printing plates provided to be arranged side by side on the plate cylinder 16. Each printing plate has at least one front notch 12 intended to cooperate with each other. with a pin 22 for indexing the plate cylinder 16 and with the corresponding rail 36 of the loading device 30 for guiding the printing plate when it is loaded on the plate cylinder 16.

Each set of printing plates A, B, C, D comprises printing plates of the same width or printing plates of variable width from one printing plate to another.

The first set of printing plates A comprises four printing plates A1, A2, A3, A4 of the same width. Each printing plate A1, A2, A3, A4 comprises a front notch 12. The front notches 12 are positioned identically along the front edges of the printing plates A1, A2, A3, A4. More specifically, each front notch 12 is centered laterally along the leading edge.

The first set of printing plates A is shown loaded in the magazine 32.

The second set of printing plates B comprises four printing plates B1, B2, B3, B4 of the same width. The width of the printing plates B1, B2, B3, B4 is greater than that of the printing plates A1, A2, A3, A4, for printing on an upper web of paper. Each printing plate B1, B2, B3, B4 comprises a front notch 12 offset laterally along the front edge. The position of the front notch 12 differs between the printing plates so that the printing plates B1, B2, B3, B4 can be arranged side by side along the plate cylinder 16, the indexing pegs 22 being received in the notches before 12.

The third set of printing plates C comprises two printing plates C1, C2 of the same width. Each printing plate C1, C2 comprises two notches before 12 along its front edge.

The printing plates A1, A2, A3, A4 and the printing plates B1, B2, B3 and B4 are, for example, printing plates on one page, and the printing plates C1, C2 of the printing plates. two-page printing.

The fourth set of printing plates D comprises printing plates D1, D2, D3 of different widths. It more specifically comprises a two-page printing plate D1 and two printing plates on a page D2, D3, the width of the printing plate D1 being twice that of the printing plates D2, D3. The printing plate D1 comprises two front notches 12 spaced along its front edge, and each of the printing plates D2, D3 on one page comprises a single front notch 12.

Preferably, a single front notch 12 of a printing plate provides lateral guidance by cooperation with a guide rail 36. When the leading edge 6 of a printing plate comprises two front notches 12 (eg plates C1, C2 and D1), preferably a single front notch receives the corresponding guide rail with a narrower lateral clearance between this front notch and the corresponding rail than the lateral play between the or each other notch and the rail corresponding to the or each other notch. Thus, the lateral guidance is provided only by said notch having the closest lateral clearance with the corresponding rail. The or each other front notch with a greater lateral clearance facilitates the installation of the printing plate in the magazine and avoids a blockage during the sliding of the plate along the guide rails 36.

The loading device 30 allows the loading of printing plates of different widths, without adaptation of the magazine 32 during a change of width of printing plate. It is possible to alternate between the first set of printing plates A, the second set of printing plates B, the third set of printing plates C and / or the fourth set of printing plates D without adaptation intermediate magazine 32. In a loading device in which the guiding of the printing plates is performed by guiding the lateral edges of the printing plates, a change in the position of the lateral guides would be necessary in case of change of plate width printing.

The loading device 30 provides simple and efficient guidance without the need for precise cutting of the side edges of the printing plates. In a lateral guide loading device, the cutting of the lateral edges of the printing plates must be very precise, which increases their manufacturing cost.

The loading device 30 is used for automatic operation, in which the pushers 38 are actuated to push the printing plates. It is possible to use a semi-automatic operation (plate edge 6 engaged in the groove 20 by the operator) without using the loading device 30.

The positioning of the printing plates on the plate cylinder by notching plates with indexing pins in the grooves of the plate cylinder allows the manual loading of the printing plates, without the loading device, since the positioning function of the printing plates is ensured on the plate cylinder.

In the case of plates of a set of printing plates having front notches positioned differently along their front edge, the front notches provide a mechanical physical coding function and avoid errors of misplacement or plate reversal. when removing the printing plates in the magazine 32.

For the loading of N sets of printing plates on a plate cylinder with N printing plates per revolution, it is possible to provide a loading assembly comprising N loading devices as illustrated in FIG. Figure 3 and 4 vertically stacked, each for loading a set of respective printing plates on the circumference of the plate cylinder.

Claims (12)

1. A printing assembly for a rotary offset press, comprising a plate cylinder (16) and a loading device (30) for loading a printing plate (2) on the plate cylinder (16),
   wherein the loading device (30) comprises a magazine (32) for receiving at least one printing plate (2) and transferring it from the magazine (32) to the plate cylinder (16), the loading device comprising at least one guide rail (36) to guide a printing plate (2) during transfer thereof by cooperation with a notch (12) of a front edge of the printing plate (2), the notch sliding along the guide rail (36) during the transfer,
   characterized in that the plate cylinder (16) comprises at least one fastening slot (20) for inserting and fastening front and rear edges of printing plates (2), each fastening slot (20) comprising indexing slugs (22) arranged in the fastening slot (20), each to be inserted into a notch of a front edge of the printing plate (2) for lateral positioning of the printing plate (2) along the plate cylinder, each guide rail (36) being provided to engage with a notch (12) of a front edge (6) designed to engage with an indexing slug (22) provided on the plate cylinder, the magazine (32) being arranged such that the outlet (34) of the magazine (32) extends along the plate cylinder (16) and each guide rail (36) is aligned with a respective indexing slug (22).
2. The printing assembly according to claim 1, comprising at least one push-piece (38) to push the or each printing plate received in a magazine (32) toward the outlet (34) of the magazine (32).
3. The printing assembly according to claim 1 or 2, the magazine (32) comprising several parallel guide rails (36) laterally spaced apart.
4. The printing assembly according to claim 3, wherein the guide rails (36) are in a fixed position.
5. The printing assembly according to any one of the preceding claims, wherein the magazine (32) comprises a support plate (40) configured to receive at least one printing plate (2) placed on one surface (40A) of the support plate (40), the guide rails (36) being fixed on said surface (40A).
6. The printing assembly according to any one of the preceding claims, comprising at least two sets (A, B, C) of printing plates, the printing plates of each set being capable of being arranged and fixed side-by-side along the plate cylinder, the set comprising at least one printing plate with a width different from that of at least one printing plate of the other set.
7. The printing assembly according to claim 6, each of the two sets of printing plates having printing plates with the same width different from that of the printing plates of the other set.
8. A printing assembly according to any one of the preceding claims, comprising a set of printing plates capable of being arranged and fixed side-by-side along the plate cylinder, the set of printing plates comprising at least two printing plates having different widths (D1, D2, D3), in particular at least one printing plate (D1) having a width twice the size of that of another printing plate (D2, D3) of the set.
9. The printing assembly according to claim 8, wherein the set of printing plates comprises at least two one-page printing plates (D2, D3) and at least one two-page printing plate (D1) with a width twice that of the one-page printing plates.
10. The printing assembly according to any one of the preceding claims, comprising a set of printing plates provided to be fixed side-by-side along the plate cylinder (16), at least two printing plates having the same width and comprising notches formed in their folded front edges (12), the lateral positioning of the notches along the front edge of their respective printing plates being different.
11. A rotary offset press (18) comprising at least one assembly according to any one of the preceding claims.
12. A method for loading a printing plate (2) on a plate cylinder (16) of a printing assembly for a rotary offset press according to claim 1, the printing plate (2) comprising a front edge (6) designed to be inserted into a fastening slot (20) of the plate cylinder (16) to fasten the printing plate (2) on the plate cylinder (16), characterized in that the front edge (6) has a notch (12) provided to be engaged with an indexing slug (22) in the slot (20), the printing plate (2) is transferred from a magazine (32) to the plate cylinder by guiding the printing plate (2) along a guide rail (36) cooperating with the notch (12) of the front edge (6), the guide rail (36) being aligned with the indexing slug (22).

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