EP0667238B1 - Adjusting cam in a control device for the ink supply of an offset printing machine - Google Patents

Abstract

The ink blade (14) is differently bendable against the cylindrical surface of the ink ductor and has positioning devices for bending its edges (36), which comprise axially displaceable thrusters in a guide and a positioning eccentric (62) with an axis parallel to the ink ductor axis. The thrusters are pressed with springs (100) against the peripheral surface (72) of the positioning eccentric. The self-restricting, positionable positioning eccentrics are arranged on an installation strip (56) as control unit directly or with an adaptor for exchangeable fixture on the offset printing machine. The peripheral surfaces of the positioning eccentrics are located in a longitudinal groove (89) of the control unit (58).

Description

The invention relates to an eccentric according to the preamble of claim 1.

DE, A1 2550720 describes an ink supply control, in the inking unit the adjusting means have tappets which can be displaced in the direction of their longitudinal axis by an eccentric. All eccentrics have a detent mark that ensures a uniform position of these eccentrics and thus the ink knife connected to the eccentric by means of zone screws can be adjusted evenly towards the ductor by means of a fine adjustment on the zone screws.

According to all known embodiments, two circular lateral surfaces are displaced relative to one another for the production of eccentrics for ink fountains.

These known control devices for zone-by-zone adjustment of color meters each require mechanisms for supporting the positioning eccentrics which consist of a large number of individual parts.

The inventor has set himself the task of creating positioning eccentrics in a control device of the type mentioned at the outset, which can be supported without play with precise, reproducible setting.

The object is achieved according to the characterizing part according to patent claim 1. Special and further developing embodiments of the positioning eccentric are the subject of dependent patent claims.

• bei einer Verschiebung des Stellhebels auf der Skala von Position 0 auf 15 der Stössel um 0,05 mm verschoben wird,
• bei einem weiteren Verschieben des Stellhebels von Position 15 auf 25 auf der Skala der Stössel um weitere 0,10 mm verschoben wird, uns
• bei einer nochmaligen Verstellung des Stellhebels von Position 25 auf 35 auf der Skala der Stössel nochmals um 0,15 mm verschoben wird.

The design of the peripheral surface of the locating eccentric is of importance for the invention, in other words the surface on which the plunger or the slide piece guiding the plunger rests directly. The peripheral surfaces have the greatest distance in the direction of the extension of the adjusting lever from the axis of rotation to which it runs parallel. On at least one side, the peripheral surface is designed such that the distance is progressive up to a certain angle decreases. This decreasing distance causes a targeted displacement of the plunger when the adjusting eccentric is rotated and thus an opening of the gap between the color knife and the color duct, which allows more color to flow through. This means that e.g.

• when moving the adjusting lever on the scale from position 0 to 15, the plunger is moved by 0.05 mm,
• if the adjusting lever is moved further from position 15 to 25 on the scale of the tappet, another 0.10 mm, us
• if the adjustment lever is adjusted again from position 25 to 35 on the scale of the tappet, it is moved again by 0.15 mm.

The progressively curved peripheral surface of the positioning eccentric must be worked out with the highest precision. The setting of the ink gap is more sensitive the closer the ink knife edge is pressed to the ink duct. The circumferential surface of the positioning eccentric and the position of its bore for receiving the bearing bolts are calculated using known parameters for the progression using known mathematical methods.

The positioning eccentrics rotatably mounted on at least one fixed bearing pin preferably have a self-locking braking element which is pressed onto the bearing pin (s). The operational safety and reliability of the relative deflection from the eccentric to the bearing pin is essential, the adjustment is usually carried out several times a day, with each print job.

For the basic setting or calibration, all eccentric cams are brought into the stop position with the ink knife attached to the duct roller in all zones, with manual setting levers on the zero position or electronically adjustable positioning eccentrics indicate a zero position. An optimal setting of the positioning eccentric for a specific work step can be read from the printer, noted and re-set for a later same job. With electronic eccentric actuation, registration, storage and readjustment are carried out fully automatically using a processor.

According to a first variant for setting the self-locking of the actuating eccentric, the actuating lever is screwed into a bore that extends up to the guide pin. Here, directly or via an intermediate piece, e.g. a spring, exerted a force on a brake element lying on the guide pin. This is designed, for example, as a rondelle or is adapted on one side to the surface of the guide bolt. The braking element consists, for example, of aluminum or a plastic. It must not leave scratch marks on the guide pin and / or not seize.

According to a further, the preferred variant, the bore for the braking element of an actuating cam does not lie on the extension of its actuating lever, but is angled to it. The braking element is in turn pressed onto the guide pin by a force exerted directly or expediently by a spring by means of a screw.

The manufacture of the positioning eccentric, in particular of its progressively curved peripheral surface, requires the highest precision and is therefore relatively expensive. According to a particularly advantageous further development of the invention, the positioning eccentrics are therefore produced in a uniform standard width and with a few standardized curvature characteristics for their peripheral surface. Depending on the make, the slats of a color knife are of different widths. The distances from the center of the slats to the center of the slats vary, for example, from 28 to 35 mm. In order to If a control unit according to the invention with standardized positioning eccentrics can be installed on all makes, the width of the positioning eccentrics is produced according to the smallest distance from the center of the plate to the center of the plate, minus the width of a bearing jaw. Wider distances can be compensated for by making the bearing jaws correspondingly wider. So that the bearing jaws can also be held uniformly in stock, correspondingly wide washers are preferably inserted on both sides of the positioning eccentric for larger widths.

The standardized positioning eccentrics preferably have a step-like narrowing of the circumferential surface on both end faces. The circumferential surface, which is reduced in width, corresponds to a groove in the associated sliding piece, which also results in perfect guidance in the axial direction of the bearing bolts.

A control unit is built on the modular principle, it is particularly suitable for retrofitting all makes of offset printing machines. Depending on the desired comfort level, it can act on simple color meters, which are the rule in the basic equipment, or on a zone color meter. The eccentrics can be adjusted fully automatically, either manually or at the highest comfort level in a manner known per se, using electronically controlled actuators.

Suitable control units with the same, standardized positioning eccentrics can be installed for each make using a mounting bar or a simple adapter, for example an angle profile.

Standardized eccentric cam with high-precision, progressively curved circumferential surfaces are essential because the manufacturing and storage costs can be significantly reduced.

Progressively curved circumferential surfaces on a positioning eccentric allow the precision of the setting to be specified as required. If the gap between the ink knife edge and the ink ductor is narrow, a much higher setting precision is desired than with a wider ink flow gap.

Finally, the necessary self-locking of the positioning eccentric and the length adjustment of the bolts for the transmission of the force from the positioning eccentric to the color knife are solved in a simpler, more secure manner.

- Fig. 1

eine teilweise aufgeschnittene Seitenansicht eines an sich bekannten Farbkastens mit Farbduktor, in Arbeitsposition,

- Fig. 2

einen teilweisen Längsschnitt durch ein Lamellenfarbmesser,

- Fig. 3

eine teilweise abgedeckte Ansicht einer Steuereinheit,

- Fig. 4

einen Schnitt durch eine an einem Farbkasten befestigte Steuereinheit,

- Fig. 5

einen Schnitt durch einen Stellexzenter,

- Fig. 6

eine Ansicht eines Stellexzenters in dessen Axialrichtung,

- Fig. 7

eine Draufsicht auf einen Stellexzenter gemäss Fig. 6,

- Fig. 8

eine Ansicht eines Gleitstücks, und

- Fig. 9

eine Seitenansicht eines Gleitstücks gemäss Fig. 8.

The invention is explained in more detail with reference to exemplary embodiments shown in the drawing, which are also the subject of dependent claims. They show schematically:

- Fig. 1

a partially cut side view of a known ink fountain with ink duct, in working position,

- Fig. 2

a partial longitudinal section through a slat color knife,

- Fig. 3

a partially covered view of a control unit,

- Fig. 4

a section through a control unit attached to an ink fountain,

- Fig. 5

a section through an eccentric,

- Fig. 6

2 shows a view of an eccentric in its axial direction,

- Fig. 7

6 shows a plan view of a positioning eccentric according to FIG. 6,

- Fig. 8

a view of a slider, and

- Fig. 9

8 shows a side view of a slider according to FIG. 8.

A paint box 10 shown in FIG. 1, known per se, with a color duct 12 comprises a color knife 14 made of a flexible metal plate and side jaws 16 arranged on both sides. In the example shown, these side jaws 16 consist of a metal jaw connected to a knife carrier 18 via countersunk screws 20 and a plastic plate spring-mounted on the metal jaw via hook clips 22 and hold-down clips 24. The brackets 22, 24 are connected to the metal jaw by means of screws 26. In the present case, four resilient ball screws 28 press the plastic plate against the end face of the ink ductor 12 with a total force of approximately 10 N.

The side jaw 16 has free space in the region of the roll neck 30 of the ink duct 12 with the longitudinal axis A. Only a partial segment 32 of the plastic plate of the side jaw 16 is visible, which rests on the end face 34 of the ink duct 12 and ensures the lateral sealing. Wear of the partial segment 32 is compensated for by the resilient ball screws 28 pressing on the plastic plate.

In the area of the ink knife edge 36, the plastic plate of the side jaw 16 has a groove with a sealing compound 38 on which the ink knife 14 rests.

In the lowest area of the ink fountain 10, a dye bath 40 is indicated, which is sealed properly.

The color knife 14 is expediently divided into slats 46 in the region of the knife edge 36 which is placed against the running surface 42 of the color ductor 12 or pressed in the vicinity thereof, by cuts 44 of equal length running at right angles to it (FIG. 2). The individual, preferably equally wide, slats 46, symbolized by an arrow 48, can be bent elastically parallel to the duct axis A by the action of adjusting means. Known adjusting means are, for example, simple adjusting screws, eccentrics or further developed, also automatic adjusting means.

As already mentioned, FIG. 2 shows part of a slat color meter 14. The spaces b between the slats 46 are also sealed so that no color really runs out. This can be done in a manner known per se. In the present case, a thin, flexible metal strip 50 is applied in a sealing manner on the top side of the generally 1 - 3 mm, in particular 1.5 - 2.5 mm thick slats 46, preferably by means of an adhesive 52. Each slat 46 is attached by means of a an actuating means indicated by a lamella, in the present case a bolt 54, pressed against the running surface 42 of the ink ductor 12 (FIG. 1), so that the flow of ink can be reduced or even prevented zone by zone if the lamella 46 in question is bent accordingly. The flexible, for example about 0.2 mm thick, band 50 made of spring steel can compensate for this displacement without any significant effect on the adjacent slats 46 and absolutely prevents any color leakage between the slats 46.

The control unit 58 shown in FIG. 3, which can be mounted on each offset printing machine by means of a mounting bar 56, which is bevelled at the top, comprises in Substantially alternately pivoting eccentric 62 and bearing jaws 64 on at least one bearing pin 60.

The bearing pin (s) 60 are arranged coaxially on a longitudinal axis L running parallel to the duct axis A. The bearing bolts 60 are formed separately for each eccentric 62. Of course, a bearing pin 60 can also extend over several bearing jaws 64 or over the entire length of the control unit 58.

The bearing jaws 64 are individually screwed to the mounting bar 56, a countersunk screw 66 is visible in FIG. 3. Each bearing jaw comprises a threaded bore 68 for a screw for fixing the bearing bolt 60.

In the present case, the bearing jaws 64 are 32 mm apart, measured from center to center. The width of the standard eccentric 62 is 28 mm. To fix the eccentric 62 in the direction of the longitudinal axis L, a washer 70 of 2 mm thickness is inserted on both sides. The positioning eccentric 62 can thus be pivoted practically without play.

In the longitudinal direction L, the circumferential surface 72 of the actuating eccentric 62 is stepped on both sides, whereby a groove 74 is created in each case. The gradations are shown in FIGS. 6 and 7 in detail. When the control unit is mounted, a sliding piece 90, indicated by dashed lines and later shown in detail, is placed on the peripheral surface 72.

On the right side of Fig. 3, a rounded cover plate 76 is drawn, which has rectangular opening slots (77 in Fig. 4) for the actuating lever 78 of the eccentric. A scale from 0 to 35 is printed or applied next to each opening slot, with which the setting levers 78 can be pivoted into a predetermined position in a self-locking manner.

4 shows the lower region of a color box 10 with the color knife 14. A control unit 58 is fastened to the ink fountain 10 via the mounting bar 56. This is done by means of countersunk screws 82 arranged at regular intervals.

The bearing jaws 64 are fastened to the mounting bar 56 with one screw 66 each. A square profile 86 is inserted into a corresponding groove in the mounting bar 56 and bearing jaws 64, which prevents the bearing jaws 64 from rotating.

A bottom plate 88 projecting on one side is screwed onto bearing jaws 64 at regular intervals. Mounting strip 56, bearing jaws 64 and the protruding base plate 88 form a groove with a rectangular cross section, into which sliding pieces 90 are fitted. These lie on the peripheral surface 72 of the eccentric 62.

The eccentric 62 is drawn in the uppermost position and indicated in the lowest position. When adjusting the adjusting eccentric 62, the slider is displaced in the direction of the longitudinal axis S of a plunger 92 anchored in the slider. This plunger 92 is mounted in a stepped bore 84 in the ink fountain 10 and lies with the slightly rounded front end 94 in the area of the knife edge 36 on the ink knife 14. The slider 90 has a bore 96 with an internal thread 95, into which an external thread 114 of the plunger 92 is screwed. A hexagon 97 of the plunger 92, which is easily accessible from the outside, permits problem-free turning and thus a finely tuned and precise length adjustment of the plunger 92. The hexagon 96 can be replaced by analog means, for example radial bores in the outer casing, into which a pin can be inserted.

A plastic screw 98 acting directly on the external thread 114 of the plunger 92 fixes it. The plunger 92 is only adjusted at larger intervals, the continuous distance control is carried out with the adjusting eccentric 62.

The plunger is always pressed in the direction of the slider 90 by means of a spring 100. The spring 100 is supported at one end on a step 103 in the bore 84 and at the other end on a snap ring 104.

The adjusting eccentric 62 shown in FIGS. 5 to 7 has a bore 102 angled with respect to the adjusting lever 78 for receiving means for forming a self-locking device (FIG. 5).

The bore 102 in the eccentric 62 according to FIG. 5, offset from the flat actuating lever 78 by an angle γ of approximately 15 °, is directed towards the bearing pin 60. A disk-shaped brake element 106 is inserted into this bore 102, which, after a screw 108 has been screwed in, is pressed onto the fixed bearing pin 60 by the force of a spring 110 and the aforementioned adjustable self-locking is effected.

The curved circumferential surface 72 of the positioning eccentric 62, which is produced with the highest precision, can be seen from FIG. The distance a of the circumferential surface 72 from the axis L is greatest on the longitudinal center plane M of the actuating lever 78, on which the longitudinal axis L of the bearing pin 60 is preferably located. This distance a gradually decreases over an angle α or β, for example by a total of 0.3 mm. In other words, the distance a initially decreases slowly in the area of the longitudinal center plane M, then progressively faster.

6,7 further show that the peripheral surface 72 of the positioning eccentric 62 is stepped on both ends. The two tiered Surfaces 112 run in a circle, they have nothing to do with the eccentric effect, but serve to create a guide groove for the slide 90 (FIGS. 3, 8, 9).

The slider 90 with the bore 96 for the plunger 92 (FIG. 4) and a further bore 116 arranged perpendicularly thereto for the locking screw 98 (FIG. 4) is shown in FIGS. 8.9. A continuous groove 118 of depth t can also be seen from these figures, which groove serves to accommodate the peripheral surface 72 of the positioning eccentric 62 (FIGS. 5-7). As a result, the plunger held in the slider 90 is also fixed in the direction of the longitudinal axis L (FIG. 3). The slider 90 can only move in the direction of the longitudinal axis S of the plunger 92 (FIG. 4). In the other two directions it is fixed practically without play.

Claims (6)

1. Adjustment cams (62) in a control device for the ink supply to an offset printing machine with at least one flexible ink blade (14) which, inclined towards an ink roller (12), borders an ink bath (40) and can be bent in zones to different degrees against the cylindrical surface of the ink roller (12), where adjustment means are arranged to bend the ink blade edge (36), the said means having tappets (92) axially displaceable in a guide with an adjustment cam (62) alocated to each, with the longitudinal axis (L) of the bearing bolts (60) parallel to the ink roller axis (A), and the tappets (92) pressed by springs (100) against the peripheral surface (72) of the adjustment cams (62),
   characterised in that
   the distance (a) of the peripheral surface (72) of the adjustment cams (62) from the longitudinal axis (L) of the bearing bolts (60) is at its greatest at the longitudinal centre plane (M) of their adjustment levers (78), and decreases progressively to at least one side.
2. Adjustment cams (62) according to claim 1, characterised in that the distance (a) decreases progressively up to an angle (α, β) of maximum approximately 60° on both sides of the longitudinal centre plane (M) in relation to the longitudinal axis (L).
3. Adjustment cams (62) according to claim 1 or 2, characterised in that they are self-locking and are positioned alternating with bearing blocks (64) for their rotationally fixed coaxial bearing bolts (60), where the peripheral surface (72) of the adjustment cams (62) lies freely in a longitudinal groove (89) of a control unit (58).
4. Adjustment cams (62) according to any of claims 1 to 3, characterised in that a tappet (92), or a slider (90) guided by this, is guided under contact pressure on the peripheral surface (72) of an adjustment cam (62).
5. Adjustment cams (62) according to claim 3, characterised in that within these a braking element (106) causing self-locking is pressed on the bearing bolts (60).
6. Adjustment cams (62) according to claim 4, characterised in that the adjustment cams (62) have on both sides a step-like constriction (112) of the peripheral surface (72), and the reduced width peripheral surface (72) fits in a groove (118) of the allocated slider (90).

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