DE9421352U1 - Device for fastening and tensioning printing plates with "Z" -shaped ends - Google Patents

Description

Description

Device for fastening and clamping printing plates with "Z"-shaped bent ends

The invention relates to a device for fastening and clamping printing plates with "Z"-shaped bent ends according to the preamble of claim 1.

Devices for fastening and clamping printing plates with bevelled ends for rotogravure printing machines are well known.

EP 01 24 008 A2 describes a forme cylinder with a device for clamping flexible printing plates with clamping means for bent ends of a printing plate. These clamping means are arranged in a pit and are designed as triangular segment bodies with a hanging edge, the outer surface of which covers the pit gap when the plate is clamped and corresponds to the contour of the forme cylinder.

There is no guarantee that the plate will lie exactly on the cylinder periphery in the area of the hanging edge. Even the smallest deviations in the shape of the plate bevel to the hanging edge of the cylinder cannot be compensated for, especially in the case of metal gravure plates, which are particularly rigid.

A printing plate lock is known from DE-PS 11 21 073, with which "Z"-shaped bent printing plates are secured and clamped. In order to clamp them, clamping jaws press against bent legs of the printing plate, whereby a hollow space is created on the cylinder periphery between the printing plate and the clamping jaws.

Both devices lead to an unacceptable increase in the area in which deviations in the shape of the plate from the cylinder contour can occur, i.e. the plate lies hollow on the gravure cylinder.

Particularly in gravure printing processes, rigid metal printing plates are used, where the shape deviations are particularly pronounced.

These shape deviations cause the squeegee to be applied unevenly, which leads to disruptions in the application of ink (e.g. ink splashing) during gravure printing.

In order to achieve the smoothest possible guidance of the doctor blade, possibilities have been created to interlace the edges of the doctor blade and the pit gap, which normally run parallel to the cylinder axis (e.g. by tilting the doctor blade). This interlacing is limited by the fact that if the interlacing is strong, the pressure of the doctor blade on the plate

changes in the axial direction of the cylinder to an unacceptable extent (the uneven contact also causes the wear of the doctor blade to be unacceptably large).

The invention is based on the object of creating a device for fastening and clamping printing plates, in particular gravure printing plates, with "Z"-shaped bent ends and in doing so adapting the shape of the printing plate in the area of the printing plate ends exactly to the cylinder contour.

This object is achieved by the features of the characterizing part of claim 1.

The advantages that can be achieved with the invention are in particular that the device according to the invention minimizes deviations in the shape of a printing plate from a form cylinder contour in the area of the hanging edges, i.e. the hollowing of the printing plate ends. The device according to the invention prevents paint splashing during the gravure printing process, which occurs due to the uneven contact of the squeegee with the gravure plate. In addition, wear on both the sealing compound that closes the pit gap and on the squeegee is significantly reduced. When the hanging edges are opened, the sealing compound is automatically removed.

The device according to the invention is shown in the drawing and is described in more detail below.

Show it

Fig. 1 is a radial section of the device according to the invention with opened clamping elements;

Fig. 2 is an axial section corresponding to Fig. 1;

Fig. 3 shows a radial section of the device according to the invention with partially closed clamping elements;

Fig. 4 shows a radial section of the device according to the invention with half-closed clamping elements;

Fig. 5 shows a radial section of the device according to the invention with closed clamping elements.

A gravure printing form cylinder 1 shown in Fig. 1 has a left 2 and right 3 pivoting, acute-angled suspension edge, the respective outer surface 5 of which is adapted to a curvature of a form cylinder contour and thus continues the form cylinder contour without a step in the clamping state, continuously. These pivoting suspension edges 2, 3 run parallel to the cylinder axis and laterally delimit a cylinder pit 7. A beveled end 4, β of a gravure printing plate is inserted into the suspension edges 2, 3.

8. An opening angle Alpha of the ends 4, 6 can be 45°, but preferably less than 45°, e.g. 35°. Legs 9, 11 of the bent ends 4, 6 extending into the interior of a cylinder pit 7 are each connected to a curve 12, 13, into which a non-bent part of the gravure plate 8 merges. Legs 14, 16 continue from the first legs 9, 11, which form a second bevel 17, 18 with the first legs 9, 11 with an opening angle Beta. This opening angle Beta can also be 45°, but preferably less than 45°, e.g. 35°. This second bevel 17, 18 is directed towards the opposite end 6, 4 of the gravure plate 8. In a flat gravure plate 8, the two ends 4, 6 and the two bevels 17, 18 have approximately the shape of a "Z".

On a base 19 of the cylinder pit 7', which is bordered on the right and left by the suspension edges 2, 3, a strip 21 approximately as long as the cylinder pit is arranged.

A right and left side surface 22, 23 and a base surface 24 form an approximately trapezoidal cross-section of the strip 21. The side surfaces 22, 23 each enclose an angle Gamma with the base surface 24 of the strip 21, which is approximately 0.5° to 5° smaller than the opening angle Beta, which the legs 9, 11 form with the legs 14, 16 of the bent

Ends 4, 6 of the gravure printing plate 8 are formed by the side surfaces 22, 23 and the base surface 24. Corner edges 26, 27 are formed. A distance al between the corner edges 26, 27 is the same or slightly longer than a distance a2 between the bevels 17, 18 of the suspended gravure printing plate 8 when the suspension edges 2, 3 are closed. The base surface 24 runs parallel to the base 19 of the cylinder pit 7 and when the suspension edges 2, 3 are closed, the legs 14, 16 of the gravure printing plate 8 run parallel to the base surface 24.

Cuboid guide pieces 31, 32 are attached to both ends 28, 29 of this strip 21 and run in grooves 33, 34. The groove 33 or 34 in the base 19 of the cylinder recess 7 is wider than the cuboid guide piece 31 or 32, so that the strip 21 can be moved in the direction of the hanging edges 2, 3, i.e. in the direction of the bevel 17, 18. The guide pieces 31, 32 enable a radial movement of the strip 21 along the groove 33, 34 (Fig. 2).

This radial movement is limited, for example, by a cylinder-fixed bolt 36, which engages in an elongated hole 37 with the length of the path of the bar 21 in the radial direction. Between the guide pieces 31, 32, compression springs 38 are arranged under the bar, which are supported in the base 19 of the cylinder pit 7 and on the base surface 24 of the bar 21 (Fig. 1 and Fig. 2).

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The clamping process of the gravure plate is as follows:

In order to tension the gravure plate 8, the hanging edges 2, 3 with the hanging, bent ends 4, 6 of the gravure plate 8 are pivoted in the direction of the cylinder pit 7. In doing so, the legs 9, 11 of the bent ends 4, 6 of the gravure plate 8 are pressed against the side surfaces 22, 23 of the trapezoidal strip 21, whereby the strip 21 is moved against the compression springs 3 8 in the direction of the base 19 of the cylinder pit 7. The legs 14, 16 of the gravure plate 8 are guided under the base surface 24 of the trapezoidal strip 21 during this movement (Fig. 3 and Fig. 4).

Shortly before the end of the pivoting movement of the hanging edges 2, 3 - i.e. before the end position of the hanging edges 2, 3 is reached - the bevels 17, 18 enclose the corner edges 26, 27 of the trapezoidal strip 21 near the pit. Due to the positive connection thus formed, these ends 4, 6 are now pulled exactly onto the hanging edges 2, 3 by further pivoting the hanging edges 2, 3 with the hinged, beveled ends 4, 6 of the gravure plate 8. As a result, the gravure plate 8 also adapts exactly to the cylinder contour in the area of the hanging edges 2, 3 (Fig. 5).

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Parts list

1 gravure form cylinder

2 hanging edge, left (swivelling)

3 Hanging edge, right (swivelling)

4 End, bevelled

5 Surface, outer (2, 3)

6 End, bevelled

7 Cylinder pit

8 Gravure plate

9 legs

11 legs

12 Rounding

13 Rounding

14 legs

16 legs

17 Bending

18 Bending

19 Reason (7)

21 Strip, trapezoidal

22 Side surface, right (21)

23 Side surface, left (21)

24 Floor area (21)

26 Corner edge, right (21)

27 Corner edge, left (21)

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28 End, first (21)

29 End, second (21)

30 -

31 Guide piece, first (21)

32 Guide piece, second (21)

33 groove, first (19)

34 groove, second (19)

36 bolts

37 Long hole (28, 29)

38 compression spring

al Distance between corner edges (26, 27) of the strip (21) a2 Distance between the bend (17, 18)

Alpha opening angle (4, 6) Beta opening angle (17, 18) Gamma angle (21)

Claims (4)

..<Pj.fci021DE Claims 1. Device for fastening and clamping gravure printing plates (8) with "Z"-shaped bent ends (4; 6) on a gravure printing form cylinder (1), characterized in that pivotable hanging edges (2; 3) adapted to the "Z"-shaped bent ends (4; 6), the respective outer surfaces (5) of which have a curvature. a cylinder contour, running parallel to the gravure cylinder axis, are arranged to delimit a cylinder pit (8), that outer surfaces (5) of the pivotable suspension edges (2; 3) are provided in the clamping position to continue the cylinder contour without a step, that a strip (21) with a trapezoidal cross-section that is spring-loaded in the radial direction of the gravure form cylinder (1) and movable in the direction of both suspension edges (2; 3) is arranged along the cylinder pit (7), that corner edges (26; 27) of the strip (21) formed by side surfaces (22; 23) and base surface (24) are arranged to engage in bevels (17; 18) of the gravure plate (8). 2. Device according to claim 1, characterized in that an angle (gamma) of the strip (21), which is formed by the side surface (22) or (23) and the base surface (24), is smaller than an opening angle (beta) of the bevel (17) or (18) of the intaglio plate (8), which the legs (9) and (14) or (11) and (16) enclose. 934-06-07
Pl. 1.021DE 3. Device according to claim 1, characterized in that a distance a1 of the corner edges (26, 27) of the strip (21) is equal to or slightly longer than the distance a2 of the bevels (17, 18) of the suspended gravure plate (8) when the suspension edges (2, 3) are closed. 4. Device according to claim 1, characterized in that guide pieces (31, 32) are attached to the strip (21), with which the strip (21) is mounted in grooves (33, 34) in the base (19) of the cylinder pit (7) so as to be movable radially with respect to the gravure form cylinder (1) and in the direction of the bends (17, 18).