EP0899095B1 - Rotary sheet-fed press - Google Patents

Description

The invention relates to a sheet-fed rotary printing press according to claim 1, which e.g. in the DE-C-432853. From DE-PS 435 592 is a three-cylinder rotary rubber printing machine known at the plate and Rubber cylinder at least two printing surfaces each own and a printing cylinder a printing area more than the rubber cylinder has.

The disadvantage of this printing press is that Registration problems can occur because of a printable Sheet already from a gripper system from the impression cylinder is removed before this sheet is completely printed is.

DE 43 03 797 A1 and FR-A-564 212 show Sheetfed offset printing presses, where a sheet only after a printing process between Rubber cylinder and impression cylinder from one sheet-removing gripper system is taken over.

WO 90/02044 describes a rotary printing press with one arranged on a forme cylinder, laser-writable printing plate. The forme cylinder is assigned an axially movable laser writing system.

By GB-A-10 154 A.D. 1915 is one Sheet-fed rotary printing machine for multi-color printing with known a central pressure cylinder. this Printing cylinders are two with several printing areas Assigned forme cylinders.

EP 0 359 957 A2 shows a printing press with a Short inking unit. The short inking unit essentially exists from a doctor blade, an anilox roller and one Inking roller.

DE-PS 521 874 and DE-C-238264 describe one Sheet-fed rotary printing machine for direct multi-color printing with a forme cylinder and an impression cylinder. there the forme cylinder has four printing surfaces and the Printing cylinder five gripper systems.

US-A-19 19 462 shows one Sheet-fed rotary printing machine for direct Multi-color printing, with a central printing cylinder five forme cylinders are assigned.

The invention has for its object a To create sheet-fed rotary printing press.

This object is achieved by a Sheet-fed rotary printing press with the features of the Claim 1 solved.

Advantageously, the inventive Sheet-fed rotary printing press with a multi-color print a register of the highest accuracy, because the to printing sheet during all printing processes in one single gripper system held on a pressure cylinder become. The printed sheets are only made by one Another gripper system taken over and from the pressure cylinder removed after the sheet has been fully printed.

By using a sheet feed device that is synchronized with the printing cylinder and accelerates the sheets to be fed from standstill to the peripheral speed of the printing cylinder, a safe sheet feed is achieved with a very precise feed register even at high speeds (e.g. 12,000 sheets per hour).
It is particularly advantageous that laser-writing systems are assigned to the forme cylinders and thus laser-imageable plates are imaged directly in the printing press (computer-to-press). This means that there are no registration problems due to the plate mounting on the forme cylinder or due to errors during the production of the plates. This means that circumferential, side or inclined register setting devices can be dispensed with.
The short inking units without ink zones minimize makeready times and simplify operation of the printing press. In particular, the short inking units enable a very small overall size of the entire printing press. The short inking units are only in contact with one printing surface of the forme cylinder, so that, when parked, they are rolled over only against an anilox roller. An existing color relief in the circumferential direction is reduced by different diameters of applicator roller and anilox roller. The anilox roller interacts with a chambered doctor blade, which completely removes the remains of the ink relief and creates a completely even ink film on the anilox roller.
Damping units are not required when using plates suitable for dry offset, so that known problems caused by dampening solutions, such as, for example, emulsification or increased stenciling, cannot arise.
The investment pile and delivery pile are on one side, which improves usability. In addition, the side to be printed of the sheets to be fed is at the bottom, while the printed side is at the top of the discharged sheets of the delivery stack. As a result, it is not necessary to turn the stacks after the straight printing in order to reprint the sheets.

The sheet-fed rotary printing press according to the invention is compact, minimizes set-up times, simplifies Operation and still guarantees multi-colored, stencil-free quality prints with excellent Passer. This makes it suitable Sheet-fed rotary printing machine, especially for small ones Print runs in a range from 100 to 20,000 sheets.

In addition, at least double coloring of the Ink application roller achieved in that the circumferential length the printing area to be inked is less than or equal to one Circumferential length of the assigned inking roller is.

The sheet-fed rotary printing press according to the invention is in shown in the drawing and is described in more detail below described.

Fig. 1

eine schematische Seitenansicht der Bogenrotationsdruckmaschine;

Fig. 2

eine schematische Darstellung eines Nockengetriebes zur Steuerung von Farbauftragwalzen.

Show it

Fig. 1

a schematic side view of the sheet-fed rotary printing press;

Fig. 2

is a schematic representation of a cam gear for controlling inking rollers.

This patent application does not seek protection for a sheetfed offset press, but only for one Sheet printing machine for direct printing, d. H. without Blanket cylinders.

A shed feeder 1 is a sheet feeder 2 Upstream sheet-fed rotary printing press. This Sheet system 2 is in side frames 3, 4 of Sheet offset rotary printing machine stored and exists essentially from a side alignment device, for example a suction mark 6, one Sheet feeder 7 and front marks 8, 9. For example, the sheet feeder 7 is as rotating stop drum 7 running on the circumference two offset by 180 °, towards one Axis of rotation 11 of the stop drum 7 extending Gripper systems 12, 13 is provided. In the area of this Gripper systems 12, 13 are each a row, i. H. at least two, front marks 8, 9 arranged. The The stop drum 7 is driven, for example synchronized to the machine cycle by means of a electric drive, not shown, each within 180 ° of the stop drum 7 this from standstill to peripheral speed Printing cylinder 14 accelerated and then again brakes to a standstill. The sheet feeder 7 can also be designed as a vibrator or suction drum be or multi-stage from combinations of Suction drum and stop drum or vibrator work and is arranged below the sheet to be fed.

The central pressure cylinder 14 with a diameter d14, z. B. d14 = 396 mm, which corresponds to a triple nominal diameter dn = 132 mm, is provided with three gripper systems 17, 18, 19, each offset by 120 ° and extending parallel to its axis of rotation 16. These controllable gripper systems 17, 18, 19, which interact with gripper supports 103, 104, 106, are actuated to open and close by means of cam rollers which interact with variable control cams.
With this pressure cylinder 14 act two double nominal diameter dn rubber cylinders 21, 22 with a diameter d21 and d22, z. B. d21 = 264 mm or d22 = 264 mm together, which each have two equal, opposite pressure surfaces 23, 24 and 26, 27. The respective rubber cylinder 21, 22 can be covered with two rubber blankets 28, 29 or 31, 32 corresponding to the assigned printing surfaces 23, 24 or 26, 27 or with a single rubber blanket corresponding to the two printing surfaces 23, 24 or 26, 27 become.
Corresponding forme cylinders 33, 34 are assigned to these rubber cylinders 21, 22. The double-sized forme cylinders 33, 34 with a diameter d33 or d34, z. B. d33 = 264 mm or d34 = 264 mm, also have two pressure surfaces 36, 37 or 38, 39 assigned to the pressure surfaces 23, 24 or 26, 27 of the rubber cylinders 21, 22. These pressure surfaces 36, 37 and 38, 39 are formed, for example, by printing plate plates 41, 42 and 43, 44, each of these pressure surfaces 36, 37 and 38, 39 of the forme cylinders 33, 34 having its own plate 41, 42 and 43, 44 or both printing surfaces 36, 37 or 38, 39 can be provided with a common plate which then carries two printing forms. Special plates 41, 42, 43, 44 suitable for waterless offset printing are preferably used, so that dampening units can be dispensed with. The sheet offset rotary machine described works with planographic printing plates. But it is also possible to use high pressure plates (letterset). In direct high pressure, ie for direct multi-color printing, the rubber cylinders 21, 22 can be omitted.
Each forme cylinder 33, 34 is assigned its own laser writing system 46, 47 for direct imaging of suitable plates 41, 42, 43, 44. These plates 41, 42, 43, 44 are located on the forme cylinders 33, 34 before the imaging and can be fed to the forme cylinders 33, 34 individually. However, it is also possible to provide the forme cylinder 33, 34 with a cavity and to arrange a supply and holding spindle of a laser-inscribable film there.
Rubber and forme cylinders 21, 22 and 33, 34 can each be equipped with more than two printing surfaces, the printing cylinder 14 then z. B. a gripper system carries more or less than the number of printing surfaces of a forme cylinder 33, 34. The number of gripper systems 17, 18, 19 of the printing cylinder 14 is not equal to the number of printing surfaces 36, 37 of the forme cylinder 33.
In the exemplary embodiment, the two laser writing systems 46, 47 are mounted together on a traverse 48 which extends parallel to the axis of rotation 16 of the printing cylinder 14. For example, a large number of independent laser diodes are located at a fixed location and are each connected to one end of an optical fiber. The other ends of the light guides are arranged close to one another on a slide, a large number (for example 64) of the light guides being aligned with each forme cylinder 33, 34. The carriage can be moved axially parallel to the longitudinal direction of the forme cylinders 33, 34 on the crossmember 48. The two forme cylinders 33, 34 can thus be imaged at the same time. It is also possible to dispense with the axially displaceable carriage and to arrange the light guides in a stationary manner, aligned with the respective forme cylinders 33, 34, in which case a number of light guides corresponding to the desired resolution of the printed image is provided over an entire length of the forme cylinders 33, 34. A single imaging system can also be arranged, which can optionally be assigned to both forme cylinders 33, 34, for example by means of a swiveling device, or whose rays are deflected such that both forme cylinders 33, 34 can be imaged.

Each of the printing surfaces 36, 37, 38, 39 of the two Forme cylinder 33, 34% is operated by its own inking unit 49, 51, 52, 53 colored. The inking units 49, 51, 52, 53 to the forme cylinders 33, 34 alternately on and adjustable, so that only the associated one Printing area 36, 37, 38, 39 is colored. This as Short inking units executed inking units 49, 51, 52, 53 consist essentially of one each Printing area 36, 37, 38, 39 inking inking roller 54, 56, 57, 58 of a driven anilox roller 59, 61, 62, 63 a chambered doctor blade 64, 66, 67, 68 and one Collecting pan 69. The respective inking roller 54, 56, 57, 58 can also be designed to be driven, wherein a with the Anilox roller 59, 61, 62, 63 common drive or a own independent, for example controllable drive can be provided. A diameter d54, d56, d57, d58, e.g. B. = 123 mm, the inking rollers 54, 56, 57, 58 is of a diameter d59, d61, d62, d63, z. B. = 117 mm, the anilox rollers 59, 61, 62, 63 different. So that is a circumferential length of to be inked printing area 36, 37, 38, 39 smaller or equal to the circumferential length of the assigned Ink application roller 54, 56, 57, 58. The one working and Closing doctor blade 71, 72 having chamber doctor blade 64, 66, 67, 68 guides the anilox roller 59, 61, 62, 63 printing ink to, which is metered by means of the doctor blade 71. excess, from the anilox roller 59, 61, 62, 63 doctored by means of the respective doctor blade 72 Ink is received by the drip pan 69 and fed back into a color cycle. Anilox roller 59, 61, 62, 63 and rubberized inking roller 54, 56, 57, 58 are in constant contact with each other while the Ink application roller 54, 56, 57, 58 synchronized to respective forme cylinders 33, 34 to the associated Printing area 36, 37, 38, 39 is adjustable. Is to the inking roller 54, 56, 57, 58 on both sides in pivotable about the anilox roller 59, 61, 62, 63, one-armed lever 72, 73, 74, 76 mounted. These levers 72, 73, 74, 76 can be mechanically, e.g. B. by means of a Cam gear, or electrical, e.g. B. by means of a working cylinder can be pressurized 78, 79, 81, 82 cooperating solenoid valve actuated become.

In the direction of production is after the two Rubber cylinders 21, 22 having a sprocket 83 Sprocket shaft 84 arranged with the pressure cylinder 14 cooperates. A length l, e.g. B. 414 mm, one of two centers 85, 90 of the blanket cylinder 22 and Printing cylinder 14 or sprocket shaft 8 and Printing cylinder 14 limited circular arc 95 on the The outer surface of the printing cylinder 14 is larger than one Length, e.g. B. 360 mm, the arch at maximum, for this Machine allowed format. One of the central 90 of the Printing cylinder 14 and the sprocket shaft 84 and from the Central 100 of the printing cylinder 14 and the stop drum 7 included angle alpha, e.g. B. Alpha = 60 ° smaller than an angle beta, e.g. B. Beta = 120 °, that of two successive gripper systems 17, 18 is formed. The sprocket shaft 84 guides a chain 86 a chain grab arm 87. This chain 86 is with z. B. four chain gripper systems 88, 89, 91, 92 equipped, with a distance a, z. B. 829 mm, two Chain gripper systems 88, 89, 91, 92 to each other stretched chain 86 of a circumferential length of a rubber or. Plate cylinder 21, 22 or 33, 34 corresponds. This endless chain 86 designed in this way is operated by a second sprocket shaft 93 deflected and runs to Printing cylinder 14 back. This distance a can also then be made smaller when the chain non-uniform, e.g. B. slows down to sheet storage, circulates.

The functioning of the sheetfed offset printing machine not according to the invention is as follows:
The scale feeder 1 separates sheets from a stack 94 and feeds them via a suction belt table 96 to the stationary stop drum 7. There, a front edge of a first sheet 97 applied is aligned on the front marks 8 parallel to the axis of rotation 11 of the stop drum 7. Then the suction mark 6 detects the sheet 97 and aligns it laterally. After aligning the sheet 97, the gripper system 12 closes the stop drum 7 and the stop drum 7 accelerates the sheet 97 from standstill to the circumferential speed of the printing cylinder 14. After reaching the circumferential speed, the gripper system 12 transfers the sheet 97 to the first gripper system 17 Printing cylinder 14. This conveys the sheet 97 to the first blanket cylinder 21 and
the sheet 97 is printed by the printing surface 23 of the blanket cylinder 21. Before that, the plate 41 of the forme cylinder 33 inked by the inking unit 49, for example with black printing ink, has transferred its printed image to the printing surface 23 of the blanket cylinder 21. The sheet 97 thus provided with a first printed image and the sheet 97 held by the gripper system 17 are transported to the second rubber cylinder 22. There, the sheet 97 is printed with the second printing image from the printing surface 26 previously provided by the inking unit 52 and the plate 43 of the second forme cylinder 34 with a second printing image (for example in the printing ink “cyan”).
Meanwhile, the second gripper system 18 of the printing cylinder 14 passed the stop drum 7 without picking up a sheet.
The third gripper system 19 now takes over a second sheet 98 from the second gripper system 13 of the stop drum 7, which was fed and aligned in the same way as the first sheet 97 of the stop drum 7. This sheet 98 is also printed first by the printing surface 23 of the first blanket cylinder 21 bearing the printed image of the plate 41 and then by the printing surface 26 of the second blanket cylinder 22 bearing the printed image of the plate 43.
In the meantime, the first sheet 97 was conveyed past the sprocket shaft 84 and the stop drum 7 without opening the gripper system 17. The sheet 97 now reaches the rubber cylinders 21 and 22 for the second time. However, on the first rubber cylinder 21, the sheet 97 is now printed by the second printing surface 24 with the third printing image, which is colored by the inking unit 51, for example with the printing ink "magenta" Plate 42 was transferred to the printing surface 24. The fourth printed image was transferred from the plate 44 inked, for example, with yellow printing ink by means of the inking unit 53 to the second printing surface 27 of the second blanket cylinder 22. This printing surface 44 prints the sheet 97 with the fourth print image.
The second gripper system 18 in the meantime took over a third sheet 99 from the first gripper system 12 of the stop drum 7, which, like the first and second sheets 97, 98, is now being printed for the first time by the printing surfaces 23 and 26 of the rubber cylinders 21 and 22, respectively. The completely printed, provided with four printed images first sheet 97 is after the end of the fourth printing process even at maximum format length, z. B. 360 mm, taken from the chain gripper system 91 in the area of the sprocket shaft 84. Here, the gripper system 17 opens for the first time after the unprinted sheet 97 has been taken over from the first gripper system 12 of the stop drum 7, the sheet 97 has thus been printed with four printed images in a gripper closure. This chain gripper system 91 transports the sheet 97 in the chain gripper arm 87 to the area of a stack 101. There the chain gripper system 91 opens and the sheet 97 is placed on the stack 101.
The now empty gripper system 17 then takes over a fourth sheet 102 from the gripper system 12 of the stop drum 7.
The second gripper system 18 transports the third sheet 99 printed with two printed images past the sprocket shaft 84, while the second sheet 98, which has now been provided with four printed images, is transferred to the chain gripper system 92 and transported to the stack 101.
These described processes are repeated periodically, so that each revolution of the forme cylinders 33, 34 and the rubber cylinders 21, 22, respectively, one sheet printed with four printed images reaches the chain gripper arm 87 and is deposited there on the stack 101.

The aforementioned cam gear 75 for the start and Parking the inking rollers 54, 56, 57, 58 can on each page, for example, essentially from a pair of cams 106, 107 and two with these cooperating cam rollers 108, 109 exist and are exemplified using a cam gear 75 of the forme cylinder 33 described. The cams 106, 107 are rigid on a pin 111 of the respective associated forme cylinder 33 attached and run with this around. An outer surface of each cam 106, 107 is in the circumferential direction with an arcuate, adapted to the associated printing surface 36, 37 Recess 112, 113 and an opposite, arcuate elevation 114, 116 which means more gently, in the area of a channel of the forme cylinder 33 horizontal transition curves are connected. The Cam rollers 108, 109 are for example on one Pins 117 and 118 of the inking roller 54 and 56 rotatably mounted. The cam rollers 108, 109 both with a forme cylinder 33 spring cooperating Ink application rollers 54, 56 are in the axial direction offset from one another so that each cam roller 108, 109 a cam plate 106, 107 is assigned. Through the Rotation of the cam disks 106, 107 with the Forme cylinder 33 acts alternately with elevation 114, 116 and the recess 112, 113 of the respective cam 106, 107 together in such a way that during the Interaction of the recess 112, 113 with the Cam roller 108, 109 starting and during the Interaction of the increase 114, 116 with the Cam roller 108, 109 lifting the inking roller 54, 56 from the forme cylinder 33.

LIST OF REFERENCE NUMBERS

1

Stream feeder

2

sheet feeder

3

side frame

4

side frame

5

-

6

suction pull

7

Sheet feeding device, stop drum

8th

front lay

9

front lay

10

-

11

Axis of rotation (7)

12

Gripper system (7)

13

Gripper system (7)

14

pressure cylinder

15

-

16

axis of rotation

17

Gripper system (14)

18

Gripper system (14)

19

Gripper system (14)

20

-

21

rubber cylinder

22

rubber cylinder

23

Printing area (21)

24

Printing area (21)

25

-

26

Printing area (22)

27

Printing area (22)

28

Rubber blanket (21)

29

Rubber blanket (21)

30

-

31

Rubber blanket (22)

32

Rubber blanket (22)

33

form cylinder

34

form cylinder

35

-

36

Printing area (33)

37

Printing area (33)

38

Printing area (34)

39

Printing area (34)

40

-

41

Plate (33)

42

Plate (33)

43

Plate (34)

44

Plate (34)

45

-

46

Laser writing system

47

Laser writing system

48

traverse

49

inking

50

-

51

inking

52

inking

53

inking

54

Inking roller

55

-

56

Inking roller

57

Inking roller

58

Inking roller

59

anilox roller

60

-

61

anilox roller

62

anilox roller

63

anilox roller

64

chambered doctor blade

65

-

66

chambered doctor blade

67

chambered doctor blade

68

chambered doctor blade

69

drip tray

70

-

71

Working doctor blade

72

Closing doctor blade

73

lever

74

lever

75

cam gear

76

lever

77

lever

78

working cylinder

79

working cylinder

80

-

81

working cylinder

82

working cylinder

83

Sprocket

84

sprocket

85

Head office (22; 14)

86

Chain

87

Gripper chain Leger

88

Chain gripper system

89

Chain gripper system

90

Head Office (84; 94)

91

Chain gripper system

92

Chain gripper system

93

Sprocket shaft, second

94

Stack (1)

95

Circular arc (14)

96

feed table

97

Bow, first

98

Bow, second

99

Bow, third

100

Head Office (7; 14)

101

Staoel (87)

102

Bow, fourth

103

Gripper pad (14)

104

Gripper pad (14)

105

Gripper pad (14)

106

Cam (75)

107

Cam (75)

108

Cam roller (75)

109

Cam roller (75)

110

-

111

Cone (33)

112

Recess (106)

113

Recess (107)

114

Elevation (106)

115

-

116

Elevation (107)

117

Cone (54)

118

Cone (56)

a

Distance between chain gripper systems (88; 89; 91; 92)

d14

Diameter of the impression cylinder (14)

d21

Rubber cylinder diameter (21)

d22

Rubber cylinder diameter (22)

d33

Diameter of the forme cylinder (33)

d34

Diameter of the forme cylinder (34)

d54

Ink roller diameter (54)

d56

Ink roller diameter (56)

d57

Ink roller diameter (57)

d58

Ink roller diameter (58)

d59

Diameter of the grid rollers (59)

d61

Anilox roller diameter (61)

d62

Anilox roller diameter (62)

d63

Anilox roller diameter (63)

l

Length of the arc (95)

alpha

Angle between the centers (90; 100)

beta

Angle between two gripper systems (17; 18)

Claims (13)

1. Sheet-fed rotary printing machine for direct multi-colour printing, consisting of a form cylinder (33) and of a central impression cylinder (14) provided with a plurality of controlled gripper systems (17; 18; 19), the form cylinder (33) having at least two printing surfaces (36; 37), and the number of gripper systems (17; 18; 19) of the impression cylinder (14) being unequal to the number of printing surfaces (36; 37) of the form cylinder (33), and a stack (94) of sheets (97; 98; 99) to be supplied and a stack (101) of discharged sheets (97; 98; 99) being arranged on one side of the sheet-fed rotary printing machine, the impression cylinder being assigned at least one second form cylinder (34) and the impression cylinder (14) being assigned a sheet-discharging gripper system (88; 89; 91; 92), in such a way that a sheet (97; 98; 99) with a maximum format length is taken over by this gripper system (88; 89; 91; 92) only after the end of a printing operation between the form cylinder (34) and the impression cylinder (14), each printing surface (36; 37) of the form cylinders (33; 34) being assigned at least one short inking unit (49; 51; 52; 53), the short inking unit (49; 51; 52; 53) having in each case a chamber-type doctor blade (64; 66; 67; 68), an engraved roller (59; 61; 62; 63) and at least one ink applicator roller (54; 56; 57; 58), and laser-inscribable plates (41; 42; 43; 44) being arranged on the form cylinder (33; 34).
2. Sheet-fed rotary printing machine according to Claim 1, characterized in that each form cylinder (33; 34) is assigned its own laser writing system (46; 47).
3. Sheet-fed rotary printing machine according to Claim 1, characterized in that a single laser writing system (46; 47) is provided for the selective imaging of both form cylinders (33; 34).
4. Sheet-fed rotary printing machine according to Claims 2 and 3, characterized in that the laser writing system (46; 47) is arranged so as to be axially movable parallel to its associated form cylinder (33; 34).
5. Sheet-fed rotary printing machine according to Claims 2 and 3, characterized in that the laser writing system (46; 47) is arranged fixedly in the axial direction and is provided with a multiplicity of lasers such that the respective associated form cylinder (33; 34) is simultaneously imaged along its entire length.
6. Sheet-fed rotary printing machine according to Claim 1, characterized in that the central impression cylinder (14) is assigned a sheet supply device (7), in that this sheet supply device (7) is capable of being driven in such a way that a sheet (97; 98; 99; 102) is supplied only to every second controllable gripper system (17; 18; 19) of the impression cylinder (14) and the sheets (97; 98; 99; 102) to be supplied are accelerated from standstill to the circumferential speed of the impression cylinder (14) in a single-stage or multi-stage manner.
7. Sheet-fed rotary printing machine according to Claim 6, characterized in that this sheet supply device (7) is designed as a stop drum (7).
8. Sheet-fed rotary printing machine according to Claim 7, characterized in that the stop drum (7) is provided on the circumference with two gripper systems (12; 13) offset at 180°.
9. Sheet-fed rotary printing machine according to Claim 6, characterized in that a specific electric drive is provided for driving this sheet supply device (7).
10. Sheet-fed rotary printing machine according to Claim 1, characterized in that the ink applicator roller (54; 56; 57; 58) is arranged in constant contact with the associated engraved roller (61; 62; 63; 64) and so as to be capable of being alternately thrown onto and off the form cylinder (33; 34), at the same time inking only the respective associated printing surface (36; 37; 38; 39).
11. Sheet-fed rotary printing machine according to Claim 1, characterized in that the short inking unit has only a single ink applicator roller (54; 56; 57; 58).
12. Sheet-fed rotary printing machine according to Claim 1, characterized in that this ink applicator roller (54; 56; 57; 58) is arranged so as to cooperate directly with the engraved roller (59; 61; 62; 63) and the associated printing surface (36; 37; 38; 39).
13. Sheet-fed rotary printing machine according to Claim 1, characterized in that the respective ink applicator roller (54; 56; 57; 58) is arranged so as to be mounted in levers (73; 74; 76; 77) pivotable about the associated engraved roller (61; 62; 63; 64).

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