EP2072252B1 - Method and system for compensating for regulated rotation angle asynchronicities - Google Patents

Description

The invention relates to a rotary printing machine for carrying out a method for compensating control-induced Drehwinkel- asynchronisms of two independently driven cylinder, which occur during the feed movement of the cylinder, according to the preamble of the first claim and a corresponding method for the compensation of control-induced rotational angle Asynchronitäten.

Increasingly, printing presses, such as offset printing presses, are used, in which individual cylinders are spun off from the continuous drive wheel train in order to shorten set-up times and are driven individually parallel to the main drive. For example, plate cylinders in offset printing units may have a separate drive motor (single drive), so that, for example, all plate cylinders can be simultaneously rotated to the plate change position in order to be able to perform the plate change on all printing units at the same time (eg DE 196 23 224 C1 ). In the case of printing presses with individual drives of cylinders, the angular positions of the individually and centrally driven cylinders (eg plate and blanket cylinders) must be detected with high precision in order to enable slip-free synchronization with adjacent rolling cylinders. Synchronization is understood to mean the continuous assurance of the correct angular position assignment of the adjacent cylinders.

To synchronize the individual drives with the central drive wheel train, rotary encoders are arranged in the drive wheel train, which specify the rotation angle setpoints for the control of the individual drives. The synchronous rotation of the respectively adjacent cylinders should ensure that the cylinder surfaces always slip on each other slip-free and no relative movements at the contact points of the cylinder surfaces come about, whereby either the print image transfer is impaired or tensile stresses are generated in the substrate. The synchronization of the individual drives, which are assigned to the plate cylinders, with the rubber cylinders driven by the drive wheel train via setpoint specifications, which are derived from the rotary encoders on the rubber cylinder shafts.
Special measures for synchronization are required when one of the synchronized cylinders relative to the other changes the position of its axis of rotation, such as this is the case for example with rubber and plate cylinder pairings (pivotable rubber cylinder).
At the beginning of a printing process, a rubber cylinder involved in the printing process, which is to transfer the printed image from the plate cylinder to the printing material, must be placed against the printing cylinder (print-on-position), during printing interruptions it must be swiveled away from it (print-off position). , For this purpose, the blanket cylinder is mounted in a pivoting device. The pivoting device is formed, for example, by mutual eccentric bearings or rockers. To ensure an optimum and constant contact pressure between rubber and plate cylinder hardened bearer rings are arranged on both sides of the cylinder whose outer diameter is adapted to the cylinder jacket diameters. The rubber cylinder is adjusted to the plate cylinder until the associated bearer rings roll on each other.
Due to the small pivoting paths of the blanket cylinder remains in the pressure-off position in meshing engagement with the gear train, so that the pivoting cylinder always performs a rotation due to the rolling of the tooth flanks at the meshing point. This rotation is superimposed by the translational movement component of the adjusting movement of the rubber cylinder axis of rotation.
In the pressure-off position (tilted position of the blanket cylinder) there is no contact of the surfaces and bearer rings of rubber and plate cylinders. This range is less problematic for the synchronicity of the rotational movement of both cylinders and is not the subject of the invention.
When pivoting the blanket cylinder to the plate cylinder, the translatory pivotal movement of the blanket cylinder after the surface contact is made approximately tangential to the plate cylinder surface, the blanket comes into contact with the pressure plate clamped on the plate cylinder. Also, the rubber and plate cylinders on both sides associated bearer rings come into contact with each other and finally roll off each other in a force-locking, whereby they also cause a mechanical support of the synchronization of the rotational movement of the rolling cylinder rolling on each other in addition to the more uniform pressure between the two cylinders. Synchronization problems when pivoting in the contact area arise from the fact that only the rotation of the blanket cylinder during rolling of the tooth flanks during pivoting detected by the arranged on the rubber cylinder shaft rotary encoder and the rotational position of the plate cylinder can be tracked synchronously via the machine control. In contrast, the detection of the translational movement of the cylinder axis of rotation with a rotary encoder without additional measures is not possible so that the tangential displacement of the blanket cylinder surface relative to the plate cylinder surface is not recognized by the machine control and consequently not with an equivalent additional co-rotation of the individual drive on the adjacent plate cylinder is traced.
The plate cylinder is caused on the one hand by the frictional surface contact between the rubber and pressure plate or between the bearer rings to rotate. On the other hand, this is counteracted by the position control of the plate cylinder drive, which has not detected the displacement of the rubber cylinder axis of rotation. When pivoting the blanket cylinder in the contact area, therefore, the rotational angle-target position of the adjacent, individually driven plate cylinder is lost relative to the blanket cylinder and there is a slip between the blanket and printing plate and thus to an unwanted torque jump on the single drive and a blur of the printed image. Vibrations in the printing press and pressure disturbances are the result.

From the DE 197 20 952 C2 a Drehwinkelkorrektureinrichtung is known for a single-pivoting cylinder, which determines either by means of additional measuring means either the translational movement of the cylinder axis or the pivot angle and feeds a multi-stage controller, which determines therefrom the required correction angle for the single drive for the suppression of relative movements between the adjacent cylinder surfaces. A disadvantage is the economic outlay for additional position sensors and control devices.
Usually, this is achieved by the rotor of the encoder (hollow shaft encoder) is firmly mounted on the cylinder axis and the stator of the encoder (encoder housing) via a torque arm on the frame of the printing press is supported. There are several variants known.
In order to avoid a relative movement of the cylinder surfaces during pivoting of the blanket cylinder in pressure-on position, in a conventional manner the encoder support point of the encoder housing has been placed on the blanket cylinder in the pitch point of the bearer rings, whereby the conventional support point results from a static view of the pivoting movement ( EP 1 593 510 A2 . DE 10 2005 029 968 A1 ). Also possible is a coupling of the rotary encoder housing on the plate and blanket cylinder, wherein each rotary encoder detects half the amount of translational movement and converts it into a corresponding angle of rotation ( DE 196 35 796 C2 . DE 10 2005 029 969 A1 ).

A disadvantage of these solutions is that in the pressure-on delivery movement due to the acceleration of the blanket cylinder during the pivoting movement and the delayed tracking of the compensation rotation of the plate cylinder, a following error occurs, so that the two cylinder surfaces not in the conventional (theoretically resulting) rotational angle position but to offset the following error. This deviation must be compensated in the cylinder and bearer contact, resulting in an undesirable and disturbing moments generating relative movement between the cylinder surfaces and bearer rings.
Another synchronization problem arises from the changing contact pressure of the cylinder combination blanket cylinder / impression cylinder. The blanket cylinder forms with an adjacent impression cylinder on which the sheets are transported by the respective printing unit, the pressure zone, wherein the pressure changes as the passage of the cylinder passages through the pressure zone abruptly. Due to the different bending of the blanket cylinder at full pressure (touch blanket / substrate) and reduced pressure (channel passage) of the rotary encoder detects an apparent rotation, since the rotary encoder, which sits on the bending rubber cylinder leg, moves relative to the frame-fixed support point in Abwälzpunkt. This apparent rotation then attempts to control the drive control for the plate cylinder, whereby an adverse relative movement of the cylinder surfaces is only generated by the angle control itself.

The invention is therefore based on the object to minimize the positional error when pivoting a second cylinder to a first cylinder, especially in the pressure-on circuit of a blanket cylinder to a plate cylinder in an offset printing unit, at the moment of contact of the cylinder.

According to the invention the object is achieved by a rotary printing machine having the features of claim 1 or a method having the features of claim 7.

The invention has the advantage that pressure disturbances causing relative movements of the synchronized cylinders during pivoting in the contact area can be safely avoided.

Figur 1:

eine schematische Darstellung der Drehwinkelgeberabstützung mit qualitativen Lagen des erfindungsgemäßen Geberabstützpunktes.

In the following, the invention will be explained using the example of a rotary encoder on a blanket cylinder of an offset printing unit. The accompanying drawing shows in

FIG. 1:

a schematic representation of the Drehwinkelgeberabstützung with qualitative layers of Geberabstützpunktes invention.

Fig. 1 shows a schematic representation of a printout section of a sheet-fed offset rotary printing press in side view with a simple large plate cylinder 1.P, a pivoting single-sized blanket cylinder 2.G, which is mounted with its shaft 10 on both sides in eccentric bearings 4, and a double-sized impression cylinder 3. The cylinder 1, 2 are stored in side frames of the printing press. The plate cylinder 1.P is associated with a first drive, which may be, for example, a known single drive M, which is associated with the plate cylinder 1.P and of a (not shown) known drive controller with respect to. Rotational angular position, rotational speed and acceleration with the blanket cylinder. G is synchronized. The blanket cylinder 2.G is driven in the embodiment via a central drive wheel train by a second drive, the main press machine drive. Between plate cylinder 1.P and rubber cylinder 2.G there is no positive mechanical drive connection.
The individually driven plate cylinder 1.P are associated with two bearer rings on both sides, which cooperate in a known manner with two other bearer rings on the shaft 10 of the blanket cylinder 2.G. The bearer rings roll in pairs from each other frictionally. For reasons of simplification was in the Fig. 1 not differentiated between the Abwälzpunkt the bearer rings and the contact area of the cylinder surfaces.
On the shaft of the plate cylinder 1.P a first rotary encoder 5 for detecting the absolute angular position (incremental encoder or encoder) is arranged centrally. Analogous to the first rotary encoder 5, a second rotary encoder 6 is mounted centrally on the shaft 10 of the adjacent blanket cylinder 2.G whose rotor 6.R is rotatably connected to the shaft 10 and the stator 6.S (rotary encoder housing) rotatably mounted on the shaft 10 is. The shaft 10 can be pivoted by rotation of the eccentric 4 between a "pressure-on" - position and a "pressure-off" - position.
On the stator 6.S a rigid Statorabstützung 7 is fixed and arranged in the radial direction, which ensures a rotational angle play free storage of the stator 6.S. The Statorabstützung 7 is rotatably supported at its end facing away from the stator 6.S end to a frame-fixed stop, the Geberabstützpunkt 8.1, 8.2 or 8.3, to transform the pivoting movement of the blanket cylinder 2.G in a rotational movement of the stator 6.S. The stator support 7 is designed, for example, as a rod-shaped anti-twist device welded to the rotary encoder housing. At the free end, the Statorabstützung 7 abuts a stop contour, which is aligned so that the extended longitudinal axis of the Statorabstützung 7 points in the direction of the plate cylinder 1.P. The Statorabstützung 7 is non-positively connected for play-free storage on the stop 8, for example via a tension spring 9 with the stopper 8. Since the pivoting movements of the blanket cylinder 2.G also cause a change in the distance to the stop 8, the Statorabstützung 7 is slidably mounted in its longitudinal direction on the stop 8. The Statorabstützung 7 may also be connected in a rotary bearing with the stopper 8. However, this then requires a variable-length design of the stator support 7, which is for this purpose formed in two parts with parts overlapping in the longitudinal direction, which are movable in the longitudinal direction relative to each other.
The solution according to the invention now provides for supporting the rotary encoder housing not at the conventional encoder support point 8.0 but at a remote encoder support point 8.1, 8.2 or 8.3. The proposed new Geberabstützpunkte 8.1, 8.2 or 8.3 are located away from the conventional Geberabstützpunkt 8.0, wherein the direction and the amount of the distance of the Geberabstützpunkte invention 8.1, 8.2, 8.3 from the conventional Geberabstützpunkt 8.0 of the Schwenkgetriebegeometrie or the pivoting curve of the axis of rotation of the blanket cylinder. 2 G and the following error to be compensated for the drive control. The positions of the Geberabstützpunkte 8.1, 8.2 or 8.3 relative to the conventional Geberabstützpunkten 8.0 and the positions relative to the axes of rotation of the blanket cylinder 2.G are variable due to a degree of freedom for the Geberabstützpunkte. The encoder control points 8.1, 8.2 or 8.3 serving to compensate for the control errors are located on a geometric location which can be determined from the geometrical conditions of the pivoting movement of the blanket cylinder 2.G with the aid of CAD programs for the time of the bearer ring contact. In the FIG. 1 are exemplary and not to scale three encoder support points 8.1, 8.2 or 8.3 shown, which were determined so. The generation of a leading setpoint value for the drive controller of the plate cylinder 1.P can therefore be achieved, for example, by changing the lever length of the stator support 7 and / or changing the relative position to the pivoting curve of the axis of rotation of the blanket cylinder 2.G compared to the conventional encoder support point 8.0.
In the FIG. 1 is the conventional Geberabstützpunkt 8.0 located in the rolling point of plate and blanket cylinder 1.P, 2.G or in the rolling point of the associated bearer rings. The further points 8.1, 8.2, 8.3 denote possible encoder support points, in which the Drehwinkelgebergehäuse is rotated in the approach phase of the cylinder surfaces by an additional angle, which compensates the following error .DELTA.α _s and due to the acceleration of the blanket cylinder 2.G and the regulation delay during the pressure -an motion arises.

From the set of possible encoder support points 8 a suitable point 8.3 is preferably selected, which approximately compensates for the following error Δα _s during the pressure-on movement and at the same time for eliminating the influence of the bending vibrations of the blanket cylinder 2.G due to the channel impacts when rolling on the impression cylinder 3 in the direction of the rubber cylinder 2.G (connecting line rubber cylinder 2.G - pressure cylinder 3) is arranged. At the same time, the encoder support point 8 should lie in the region of the cylinder circumference (8.1) in order to reduce the effects of disturbances in the area of the encoder support, in particular concentricity error of the encoder and encoder mounting, by using the largest possible lever length. The finally selected encoder support point will advantageously be a compromise between the two requirements and is exemplified in the drawing as the encoder support point 8.2.

For the operation of the device according to the invention:

In the "print-on" position of the blanket cylinder 2.G is employed in a known manner both to the plate cylinder 1.P and to the impression cylinder 3 and transmits the pressure (partial) image of the plate cylinder 1.P on the printing cylinder 3 guided bows. The second rotary encoder 6 on the shaft 10 of the blanket cylinder 2.G detects the time course of the rotational angle values of the blanket cylinder 2.G and transmits them to the drive control of the single drive M for the plate cylinder 1.P to the rotation of the plate cylinder 1.P with the synchronized by the drive wheel train rubber cylinder 2.G to synchronize. Both cylinders 1, 2 rotate in the ideal case with the same peripheral speed and with a predetermined relative Drehwinkelsynchronlage.
If the blanket cylinder 2.G swiveled by rotating the eccentric 4 of the pressure cylinder 3 and plate cylinder 1.P on a corresponding predetermined by the eccentric bearing 4 curved path to interrupt the pressure (part) image transfer to the bow, the pivoting is in the millimeter range. In this case, the meshing of the drive wheels of rubber and pressure cylinder 2.G, 3 persist. When swinging it is therefore in addition to the displacement of the blanket cylinder 2.G against the plate cylinder 1.P to a rolling movement of the drive gear of the blanket cylinder 2.G on the printing cylinder gear to the tooth engagement point, which causes an additional rotation of the blanket cylinder 2.G. This cylinder rotation is detected by the second rotary encoder 6 and then the plate cylinder 1.P synchronously by the drive control of the single drive M also rotated by this angle, so that it therefore no relative movement comes at the contact points with the plate cylinder 1.P (rubber pressure plate, bearer rings).
For rolling due to meshing with the impression cylinder 3, the translation of the axis of rotation of the blanket cylinder 2.G is approximately tangential to the surface of the plate cylinder 1.P added to avoid schleifißbeförderndem slip at the contact points between plate and blanket cylinder 1.P, 2.G and Deviations from the predetermined rotational angle relative position must be compensated by an additional rotation of the plate cylinder 1.P with a translation of the corresponding circumferential rotation (as shown in DE 103 04 495 A1 known).
With the support of the stator 6.S of the rotary encoder 6 at the conventional support point 8.0 is achieved that when pivoting the blanket cylinder 2.G the stator is rotated 6.S in the direction of rotation of the blanket cylinder 2.G by an angle which corresponds to the pivoting path circumferential path of the plate cylinder 1.P supplies. Since the zero point of the rotational angle measurement is specified by the stator 6.S, the rotation of the zero point in the direction of rotation for the drive control represents a smaller rotation of the rotor 6.R of the rotary encoder 6. The blanket cylinder 2.G thus apparently changes its angular position due to the translational movement. The drive control then corrects the rotational angle position of the plate cylinder 1.P with a delay of the forward rotation.
The correction rotation of the plate cylinder 1.P results in a circumferential path which approximates the translation path of a surface point on the blanket cylinder 2.G. The plate cylinder 1.P carries out with its correction rotation the translational displacement of the blanket cylinder 2.G, whereby there may be no loss of the angular position of the two cylinders 1, 2.
The quality of approach of the circumferential path of the plate cylinder 1.P and translational path of the blanket cylinder 2.G is essential with increasing approach of the blanket cylinder 2.G to its print-on position for the print quality, since the plate cylinder 1.P in restoring the surface contact of the To prevent circumferential register errors or blurring of the printed image, bear in mind that it should rotate synchronously with the blanket cylinder 2.G.
According to the invention, the support point 8 of the rotary encoder 6 of the blanket cylinder 2.G to be pivoted 2.G is not placed in the rolling point of the bearer rings, as it is ideally considered, but deviates so that when the cylinder 1 moves toward one another, 2 of the following error .DELTA.α _{s of} the drive control is compensated and the cylinder surfaces in the desired angular position to each other, ie, each other untwisted meet. After the first touch of the cylinder surfaces is the correction amount during the pressure build-up by the arrangement of the Geberabstützpunktes and due to the inertia of the controller compared to the speed of Druckanstellbewegung balanced again, so that the cylinders 1, 2 are exactly to each other in the end of the pivoting movement.
The control-induced following error .DELTA.α _s in the rotational angle position of the plate cylinder 1.P causes the plate cylinder 1.P to lag in the range from 2 to 80 .mu.m and is compensated by an anticipatory rotation of the rotary encoder housing by a correction angle corresponding to .DELTA.α _s . The lagging of the plate cylinder 1.P compared to the synchronous position (target rotational position) as a result of the control delay is thus compensated with a corrected by the following error .DELTA.α _s rotation angle setpoint, which causes a temporary flow of the plate cylinder 1.P, so that the cylinder surfaces at Swing the blanket cylinder 2.G against the plate cylinder 1.P in synchronizing position.
The resulting additionally in the pressure-off movement error is not critical, since it can be easily compensated by the drive controller after the end of the contact of blanket cylinder 2.G and plate cylinder 1.P.
The inventive compensation of control-related asynchronisms between electronically synchronized via rotary encoders cylinders or other bodies of revolution by shifting the Geberabstützpunktes the setpoint generator is also on other pivotal cylinders, which are in the salaried state in rolling contact with adjacent cylinders used.

List of used reference numbers

1

first cylinder

1.P

plate cylinder

2

second cylinder

2.G

rubber cylinder

3

pressure cylinder

4

eccentric

5

first rotary encoder

6

second rotary encoder

6.R

rotor

6.S

stator

7

stator support

8th

Stop, donor support point

8.0

conventional donor support point

8.1, 8.2, 8.3

Encoder support points for the consideration of the following error

9

mainspring

10

Shaft, shaft of the rubber cylinder

M

Single drive of the plate cylinder

Claims (9)

1. A rotary printing press for carrying out a method for compensating for regulated rotation angle asynchronicities of two cylinders driven independently from each other, said asynchronicities occurring during the advancing movement of one of the cylinders, wherein

   - a first cylinder (1) mounted in a frame, to which an electrical single drive (M) is assigned, is in rolling contact with an adjacent second, pivotable cylinder (2), which is connected to a second drive, during the printing operation,

   - a rotary angle transmitter (6) is arranged on the second cylinder (2), which provides rotary angle target values for a drive regulation of the single drive (M), wherein

   - a rotary angle transmitter housing forms stator (6.S) of the rotary angle transmitter (6) that can be pivoted around the rotational axis of the second cylinder (2) and is supported via a torque support (7) on a fixed transmitter support point (8) and

   - a rotor (6.R) of the rotary angle transmitter (6) is connected for conjoint rotation to the rotational axis of the second cylinder (2),

   characterized
   in that the transmitter support point (8.1, 8.2, 8.3) is arranged in radial and/or circumferential direction from the conventional transmitter support point (8.0) formed by the rolling point of the cylinders (1, 2) or from the assigned bearer rings, wherein direction and amount of the deviation from the conventional transmitter support point (8.0) is determined by the contouring error Δα_s of the drive control to be compensated, such that a regulated lag by the contouring error Δα_s between the target rotation angle position and the actual rotation angle position of the first cylinder (1) during the pivoting of the second cylinder (2) to the first cylinder (1) is compensated, so that the cylinder surfaces meet each other at the moment of touching in a synchronous position.
2. The rotary printing press according to claim 1,
   characterized
   in that the first cylinder (1) is a plate cylinder (1.P) with a single drive (M) in a sheet-fed offset rotary printing press and
   in that the second cylinder (2) is a rubber cylinder (2.G), which can be pivoted from a "Print off" position without surface contact to a "Print on" position, in which bearer rings arranged on the plate cylinder (1.P) and rubber cylinder (2.G) roll onto each other.
3. The rotary printing press according to claim 1 or 2,
   characterized
   in that the transmitter support point (8.1) lies in the region of the cylinder periphery, in order by means of a largest possible lever length to reduce the effects of disturbances in the region of the transmitter support, above all rotational errors from the transmitter and transmitter fastening.
4. The rotary printing press according to claim 2 or 3,
   characterized
   in that the transmitter support point (8.1, 8.2, 8.3) is shifted for elimination of the influence of bending vibrations of the rubber cylinder (2.G) due to rolling over the groove in a printing zone formed between the rubber cylinder (2.G) and a printing cylinder (3) in the direction of the connecting straight line between the axis of the printing cylinder (3) and the axis of the rubber cylinder (2.G).
5. The rotary printing press according to claim 2, 3 or 4,
   characterized
   in that the transmitter support point (8.2) is shifted for elimination of the influence of bending vibrations of the rubber cylinder (2.G) due to rolling over the groove and to reduce disturbances in the region of the transmitter support in radial and circumferential direction with respect to the rubber cylinder (2.G).
6. The rotary printing press according to claim 2, 3, 4 or 5,
   characterized
   in that the direction and the amount of the distance form the conventional transmitter support point (8.0) further depend on the pivoting gear geometry or of the pivoting curve of the rotational axis of the rubber cylinder (2.G).
7. A method for compensating for regulated rotation angle asynchronicities of two cylinders driven independently from each other in rotary printing presses, said asynchronicities occurring during the advancing movement of one of the cylinders, wherein

   - a first cylinder (1) mounted in a frame, to which an electrical single drive (M) is assigned, is in rolling contact with an adjacent second, pivotable cylinder (2), which is connected to a second drive, during the printing operation,

   - a rotary angle transmitter (6) is arranged on the second cylinder (2), which provides rotary angle target values for a drive regulation of the single drive (M), wherein

   - a rotary angle transmitter housing forms stator (6.S) of the rotary angle transmitter (6) that can be pivoted around the rotational axis of the second cylinder (2) and is supported via a torque support (7) on a fixed transmitter support point (8) and

   - a rotor (6.R) of the rotary angle transmitter (6) is connected for conjoint rotation to the rotational axis of the second cylinder (2),

   characterized
   in that a regulated lag by the contouring error Δα_s between the target rotation angle position and the actual rotation angle position of the first cylinder (1) during the pivoting of the second cylinder (2) to the first cylinder (1) by shifting the transmission support point (8.1, 8.2, 8.3) from the conventional transmission support point (8.0), which makes a rotation angle synchronicity in the case of an engaged cylinder (2) is made possible without consideration of regulation errors, is compensated, so that the cylinder surfaces meet each other at the moment of touching in a synchronous position.
8. The method according to claim 7,
   wherein after a first touching of the cylinder surfaces the correction value during the pressing is compensated by the arrangement of the transmitter support point (8.1, 8.2, 8.3) and as a consequence of the inertia of the regulator in comparison to the speed of the pressure application movement, so that the cylinders (1, 2) at the end point of the pivoting movement stay precisely together.
9. The method according to claim 7 or 8,
   wherein the regulated contouring error Δα_s to be compensated in the rotation angle position of a plate cylinder (1.P) causes a lag of the plate cylinder (1.P) in the range of 2 to 80 µm and is compensated by an advance rotation of the rotary angle transmitter housing by a corresponding correction angle Δα_s.

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