EP0453845B1 - Sheet-fed offset printing machine with at least one printing unit - Google Patents

Abstract

In a sheet-fed offset press having at least one printing unit in which the blanket cylinder can be thrown on and off the impression cylinder and plate cylinder by a pressure-medium-energized actuating arrangement, the pressure medium energization is triggered by a control unit in accordance with the position of grip edge zones of the cylinders being in registration. In order to ensure that throwing on and throwing off take place when the grip edge zones of the cylinders are positioned immediately opposite one another, the control unit detects the position of the printing unit cylinders relatively to one another by way of an angular position sensor and also detects the actual speed of the press via a speed sensor. The control unit forms speed-dependent throw-on and throw-off actuating times which are advanced in the direction of rotation of the printing unit cylinders so that the reaction time is outside the time slot for grip edge zone registration. The invention reduces the very substantial constructional outlay needed in the case of pressure-medium-energized actuating arrangements to ensure reliable throw-on and throw-off at high printing speeds.

Description

The invention relates to a sheet-fed offset printing machine according to the preamble of the first claim.

From DE-AS 1 098 963, DD-PS 86 631 and DE 3 232 171 A1 it is known to actuate the rubber cylinder of the printing unit of a sheet-fed offset printing press for printing on and off by actuating means which become effective when pressure medium is applied. As can be seen from the last two writings, the turning on and off of the rubber and plate cylinders or the rubber and pressure cylinders must take place in succession and in the area of the cylinder channels opposite each other. This is necessary so that when the blanket cylinder is removed from the impression cylinder, the last sheet still to be printed is printed out, or when the blanket cylinder is removed from the plate cylinder, there is no ink drop on the blanket cylinder. The same applies to the hiring processes.

From the first of the documents mentioned at the outset, it is known to provide timer devices for switching the printing unit cylinders on and off at specific times and in a specific sequence, which are driven in a machine-synchronized manner and have so-called time cams which in turn control the various shuttle valves for pressurizing the pressure medium. If pressure is to be switched on or off, the point in time of actuation, ie the point in time at which the working cylinders (actuating means) are pressurized, is always at a certain position of the printing unit cylinders relative to one another.

With increasing printing speed (speed of the printing couple cylinders) the time interval of the channel correspondence shortens, i.e. the period in which the channels of the plate and blanket cylinders as well as of the blanket and impression cylinders lie opposite one another. So that the time at which the blanket cylinder is switched on or off with respect to the printing and plate cylinder is within the respective opposite channels for a printing machine running at any speed, the triggering times can be set within and at the beginning of the channel correspondence, depending on the machine position. located within the channel area and towards the end of the print. The disadvantage of a switching point of time that is firmly dependent on the machine position and within the channel area is that, especially when the printing machine is running at high speed, only a very short time interval between the point in time at which the actuating means is pressurized and the point in time at which the rubber cylinder is completely supplied to or from the printing or plate cylinder - or is turned off, is available. In order for these starting and stopping processes to be completely completed even at the highest machine speeds within the area of the opposing cylinder ports, it is necessary to design the actuating means (double-acting working cylinders) that become effective when pressurized by pressure, for the highest forces, according to pressure medium (compressed air, oil) at high working pressures switch and also provide this with high pressure.

The object of the present invention is therefore to improve a sheet-fed offset printing machine in accordance with the preamble of claim 1 in such a way that the structural outlay for the actuating means which become effective when pressurized with pressurized medium can be reduced as far as possible, and in particular the use of actuating means which become effective when pressurized with compressed air is used at a structurally justifiable cost for printing on and off at the highest printing speeds.

This object is achieved by the characterizing features of the first claim. Advantageous configurations result from the subclaims in connection with the description and the drawings.

Fig. 1 a,b,c

das Druckwerk einer Offsetdruckmaschine,

Fig. 2

ein Diagramm zur Kanalkorrespondenz,

Fig. 3

die Vorverlegung der drehzahlabhängig ermittelten Schaltzeitpunkte,

Fig. 4

ein Blockschaltbild einer Steuereinrichtung,

Fig. 5

eine vorteilhafte Ausgestaltung einer Druckan- und - abstellvorrichtung mit doppelt wirkenden Pneumatikzylindern.

Fig. 6 a, b

Sensoranordnungen an einem Pneumatikzylinder.

An embodiment of the invention is explained in more detail below using an example. The accompanying drawing shows:

Fig. 1 a, b, c

the printing unit of an offset printing machine,

Fig. 2

a diagram of channel correspondence,

Fig. 3

advance the switching times determined depending on the speed,

Fig. 4

2 shows a block diagram of a control device,

Fig. 5

an advantageous embodiment of a pressure on and off device with double-acting pneumatic cylinders.

Fig. 6 a, b

Sensor arrangements on a pneumatic cylinder.

1 a, b, c shows the printing unit of a sheet-fed offset printing press, in which a plate cylinder 1, a blanket cylinder 2 and a printing cylinder 3 interact. For pressure switching on and off, as is well known from the prior art, the rubber cylinder 2 is mounted eccentrically on both sides, for example, and can be turned on and off both with respect to the pressure cylinder 2 and with respect to the plate cylinder 1 by means of double-acting working cylinders which are each articulated thereon (e.g. DE-AS 1 098 963).

DD-PS 86 631 and DE 3 232 171 A1 disclose and Parking devices with actuating means that become effective when pressure medium is applied, which switch the rubber cylinder 2 with respect to the plate cylinder 1 and printing cylinder 3 on or off. In addition to eccentric bearings for the rubber cylinder 2, there are also bearing levers for at least the rubber cylinder 2. By applying pressure to the corresponding actuating means (double-acting working cylinders), starting from the pressure adjustment (FIG. 1 a), the rubber cylinder 2 can initially only be switched off by the pressure cylinder 3. In the position according to FIG. 1 b, rubber and plate cylinders 2, 1 continue to have contact. If the pressure is to be turned off completely, the blanket cylinder 2 is also turned off from the plate cylinder 1 by the application of pressure medium to a further adjusting means (FIG. 1c).

As already mentioned in the introduction to the description, the rubber cylinder 2 is turned on and off with respect to the printing and plate cylinders 3, 1 in each case within the time interval in which the channels 1.1, 2.1, 3.1 of plate and rubber cylinders 1, 2 or rubber and printing cylinders 2, 3 correspond to each other.

The command for the print shutdown can be triggered either manually by the printer or by a monitoring device on the system (photo cell, double sheet control). In both cases, the system is locked (no bow on pre-gripper) and, if the machine is in the appropriate position, the blanket cylinder 2 is turned off from the pressure cylinder 3 and then, after any number of further rotations, the blanket cylinder 2 is turned off from the plate cylinder 1.

The process for printing is done accordingly. If the Druckan command is given, after the first sheet is correctly positioned on the system, the rubber cylinder 2 is positioned on plate cylinder 1 (channel correspondence). After any number of freely selectable revolutions (pre-inking of the blanket cylinder 2), the sheet is transferred from the pre-gripper to the printing unit. If channels 2.1 and 3.1 correspond to each other, the blanket cylinder 2 is placed against the impression cylinder 3, this first sheet is thus printed out in full. If there is more than one printing unit, the other printing units switch off or on in succession. A control device that performs the functions described above, in particular in more than one printing unit, is known, for example, from DE 2 607 808 A1. A timer device, which provides the switch-on and switch-off signals for certain machine positions, corresponds in its effect to a logical AND combination of an external command signal (pressure on / pressure off) and the machine position, ie a signal that indicates that to at this point the switching on and off can take place.

2 shows, over three revolutions, the mutual correspondence of the printing areas or the channels of blanket cylinder 2 and printing cylinder 3 as a horizontal program GD. According to these three turns, three arcs, i.e. Sheet n - 1, sheet n and sheet n + 1 printed. Above diagram GD, the correspondence of the pressure areas or channels of blanket cylinder 2 and plate cylinder 1 is shown in diagram GP. The shift of GP with respect to GD corresponds to the arrangement of the printing couple cylinders according to FIGS. 1 a, b, c. The image which is printed on sheet n was correspondingly earlier, i.e. a certain machine position previously, transferred from plate cylinder 1 to rubber cylinder 2. In the diagrams GD and GP, the beginning of the print and the end of the print of the respective print zone correspondence are shown with DA. In diagrams GD and GP, phase DE / DA thus corresponds to a channel correspondence between rubber and impression cylinders 2, 3 or rubber and plate cylinders 2, 1.

In diagram GD according to FIG. 2, an angle scale for the machine position is also drawn for sheet n-1, with a zero point which by definition lies in the correspondence between the start of printing of blanket cylinder 2 and impression cylinder 3. This zero point is arbitrary. According to the above definition, the printing unit assumes the 0 ° position when the printing starts DA of the rubber and printing cylinders 2, 3 face each other. Furthermore, it is assumed that the width of the channels (with a single large printing cylinder 2) is 90 °. This value is also chosen purely as an example. According to the above definition, the position 270 ° of the printing unit corresponds to the position of the rubber and impression cylinders 2, 3 if their printing ends DE correspond to one another. Positions between 270 ° and 360 ° correspond to positions of rubber and impression cylinders 2, 3, in which their channels 2.1, 3.1 lie opposite one another. The machine position or the correspondence of the pressure areas of plate and blanket cylinders 1, 2 can also be read from the diagram GP according to FIG. 2. With a machine position between 150 ° and 240 °, the channels 1.1 and 2.1 of the plate and blanket cylinders 1, 2 correspond to one another.

If the blanket cylinder 2 is to be turned off from the impression cylinder 3 after the sheet n-1 (sheet n = missing sheet), a timer device forms a signal at the switching time SGD in a known manner, which triggers the pressure medium acting on the adjusting means provided for this shut-off movement (diagram GD). If, in addition, the blanket cylinder 2 is then to be shut off from the plate cylinder 1, the timer device triggers the pressure medium applied to the actuating means leading to the blanking cylinder 2 from the plate cylinder 1 when the machine position is marked SGP. The same applies to the pressure adjustment, only that the switching time SGP for the activation of the rubber cylinder 2 on the plate cylinder 1 is at least one complete machine revolution before the switching time SGD.

• An- bzw. Abstellen des Gummizylinders 2 mit einer Kraft gegen Platten- und Druckzylinder 1, 3 (Beistellung),
• die Trägheit des Gummizylinders 2 nebst dessen Lager bei der zur An- bzw. Abstellung führenden Bewegung von der Ausgangslage in die Endlage.

2, the switching times SGD, SGP are set at the beginning of the channel correspondence, ie shortly after the pressure end areas DE of the corresponding cylinders faced each other. Setting the switching times SGD, SGP in this way ensures that almost the entire channel width is available for turning the rubber cylinder 2 on and off. In this angular range, i.e. in one of the Time dependent on the printing speed, the actuating means or actuators must bring the blanket cylinder 2 completely into contact with the plate or printing cylinder 1, 3 or release it completely from the latter. There are basically two types of forces to be overcome by the actuating means:

• Turning the rubber cylinder 2 on and off with a force against the plate and pressure cylinders 1, 3 (provided),
• the inertia of the rubber cylinder 2 along with its bearing during the movement leading to the starting and stopping from the starting position to the end position.

The first-mentioned force component is approximately independent of the printing speed, but the second component increases sharply with increasing printing speed, since the period of the channel correspondence is shortened, but the path of the rubber cylinder 2 to be adjusted remains the same. The maximum distance between the blanket cylinder 2 from the plate cylinder 1 and impression cylinder 3 should be reached within the channel area, especially when it is parked. A simple calculation shows that the forces to be applied by the adjusting means increase with the square of the printing speed.

However, the time available for reducing or adjusting the pressure is additionally shortened by a so-called reaction time, from the triggering of the pressure medium (switching times SGD, SGP) to the reaction of the actuating means (pressure build-up, retraction or extension of a piston rod of a double-acting one Working cylinder) passes. Also, the actuating means only reaches its maximum working speed after a certain time (piston speed of the working cylinder) and also, especially in double-acting working cylinders with high piston speed, the latter is braked before reaching its end position (end position braking, for example by reducing the cross section of an outlet opening).

For the reasons described above, pressure and - shutdown by means of actuating means that become effective when pressurized by pressurization is possible at the high printing speeds that can be achieved today (up to 20,000 sheets / h) only through very high constructional expenditure with regard to the actuating means (working cylinder) and the pressure medium at high Print-providing system (pressure pumps, pressure accumulator) possible. A pressure activation and deactivation by means of actuating means that can be actuated with compressed air (double-acting pneumatic cylinders) is therefore hardly possible, particularly because of the very high pressures required, with a constructionally justifiable effort.

According to the invention, in order to limit the structural complexity, in particular to enable the use of pneumatic actuating means, it is provided that the control device 4 does not form the switching signals SGD, SGP for printing on and off independently of the printing speed (speed of the printing unit), but additionally the speed of the printing unit (printing speed) is also detected and the switching times SGD, SGP are accordingly made available from the machine position and the printing speed.

According to FIG. 3, the switching times SGD, SGP for turning the rubber cylinder 2 on and off with respect to the pressure cylinder 3 (diagram GD) and with respect to the plate cylinder 1 (diagram GP) are advanced depending on the speed. The abscissas of the diagrams GD and GP show, as in FIG. 2, the machine position, on the ordinate the printing speed in sheets / h is also plotted. 3, the speed-dependent position of the switching times SGD, SGP can now be seen from the characteristic curves shown. In the simplest case, the switching times SGD, SGP are brought forward in proportion to the speed. Of course, a different advance (characteristic shape) depending on the machine speed can also be selected, for example one determined empirically or by model calculation. Provision can also be made to advance the switching times in stages with respect to the speed. This means that in a first speed range an advance by a certain amount Angle amount takes place in the next speed range by a correspondingly larger, etc. This corresponds to a characteristic curve with step shape.

The size of this advance depends primarily on the size of the response time interval already described, i.e. the period of time that elapses between the time of switching (triggering of the pressure medium) and a first forceful reaction of the actuator (s) by the pressure medium acting (pressure build-up in the working chambers). Within this reaction time is also the switching time, for example the valves controlled by the control device, i.e. the time that the valves need to open or close. Furthermore, the switching times SGD, SGP should be advanced depending on the speed so that at each printing unit speed the blanket cylinder 2 already has its end position with respect to the printing cylinder 3 or plate cylinder 1 when printing off at the beginning of the printing start DA. has taken the greatest intended distance. It also applies to the pressure adjustment that the switching times SGP, SGD, i.e. the switching times, which trigger the placement of the blanket cylinder 2 on the plate cylinder 1 or the placement of the blanket cylinder 2 on the printing cylinder 3, as far as can be brought forward that the blanket cylinder 2 at the beginning of the start of printing DA is already fully engaged with the intended provision of the corresponding cylinder is.

Since within the reaction time of the rubber cylinder 2 there is no movement for starting or stopping, the entire channel width is available for the starting and stopping movement of the rubber cylinder 2 when the switch-off time SGD, SGP is brought forward depending on the speed. The reaction time laid out of the channel area by bringing the switching times SGD, SGP forward does not therefore shorten the time available for the movement of the rubber cylinder 2.

According to a further variant of the invention, the reaction time and / or the stroke time, i.e. to measure the period of time which the actuating means or actuators require in order to carry out the movements causing the turning on or turning off. With a sensor attached to the actuating means in connection with a time recording device 4 ', the length of the time span is then recorded, which is from the output of the switching signals (switching times SGD, SGP; actuation of the solenoid valves) to a first forceful reaction of the actuating means or actuating means by the pressure medium passes. If the actuating means is designed as a double-acting working cylinder, the reaction time corresponds to the time period between the delivery switching signal and the start of the lifting movement of a working piston (beginning of the extension or immersion of a piston rod).

For a double-acting working cylinder, the lifting time stated above corresponds to the time span that a piston rod needs to fully retract or extend. In both cases, it is provided to use these measured times in addition to the speed-dependent advance of the switching times SGD, SGP. The speed-dependent advance is then carried out not only by an angular amount that depends on the speed of the machine, but by an angular amount that corresponds to the reaction time that occurred, for example, during the last start-up or shutdown process. This angular amount then simply results from the product of the angular velocity (actual rotational speed) with a reaction time determined during a previous activation or deactivation process.

If the stroke time of the actuator (s) is detected, the speed-dependent advance of the switching time SGD, SGP can additionally take place as a function of the stroke speed determined during an earlier (the last) starting or stopping process. If high lifting speeds are determined, a lower advance of the switching times SGD, SGP (smaller angular amount) than with a lower lifting speed may be sufficient. Advancing the switching times SGD, SGP is thus adapted to the lifting speed. It can also be determined whether the lifting time (lifting speed) of the actuating means increases due to aging or wear or other influences. This means that necessary maintenance and repair work can be identified at an early stage.

Fig. 4 shows a control device 4 for a printing unit according to the invention. The print on / off command is fed to the latter via a command line 5, and the control device 4 also receives a position signal from a rotary angle encoder 6 running synchronously with the machine speed, which corresponds to the position of the printing unit cylinders (angular position) relative to one another. If the control device 4 is designed according to the state of the art, it outputs the switching signals for pressurizing the actuating means when the pressure command or pressure command is given, when the actual position of the printing unit (rotary encoder 5) or correspond to the desired positions for the pressure activation or pressure deactivation process of the blanket cylinder 2 (switching times SGD, SGP according to FIG. 2). Such a provision of switching signals depending on the machine position is known from DE 2 607 808 A1.

According to the invention, it is now provided that the control device 4 forms the desired positions leading to the pressure switching on and off depending on the machine speed, that is to say it forms forward shift signals. For this purpose, control device 4 is supplied with the actual speed of the printing unit (machine speed), in particular already in digital form, via a further signal line 9. This speed signal can advantageously be taken from the control of the main drive 10, since an actual speed signal is present there anyway for regulating the machine speed. This then only has to be modified according to the main drive ratio. In general, the actual speed signal can be any signal that represents the value of the machine speed.

The rotary encoder 6, which is connected synchronously with the sheet-fed offset printing machine, is designed, for example, as a high-resolution 12-bit rotary encoder and is mounted, for example, on a so-called single-speed shaft of the system. Of course, it can also be located on any shaft that moves synchronously with the machine.

The control device 4 according to the invention is designed as a computer and is designed to calculate and provide the switching signals in accordance with the desired positions in real-time processing. Control device 4 also contains the necessary input / output modules for the command line 5, the signal from the rotary encoder 6, the actual speed signal of the signal line 9 and for the provision of the switching signals on the control lines 7 and 8. Then via control lines 7 and 8 the pressurization of the actuating means is triggered, for example, by means of electrically switchable valves (solenoid valves) for switching the pressure on and off. As will be described further below, provision is made to provide two double-acting pneumatic cylinders for switching the pressure on and off. There are therefore four working chambers per printing unit for printing on and off. These four working chambers can be pressurized with compressed air via electrically switchable solenoid valves, which, as indicated in FIG. 4, can then be controlled by four control lines 7, 8.

According to the embodiment variant described above, control device 4 can be connected to the sensors on the actuating means via signal lines RZ / HZ. A signal (pulse) is present on the signal line RZ / HZ, for example, precisely when the actuating means begins to perform a lifting movement. A time recording device 4 ', for example implemented in the control device 4, can thus determine the time period from the transmission of the switching signals (switching times SGD, SGP; actuation of the valves via control line 7 or 8) to the reaction of the actuating means (retraction or extension of a Piston rod) passes. As already described above, the reaction time determined in this way is then used in a later one To determine the speed-dependent advance of the switching times SGD, SGP (angular amounts) depending on these reaction times.

If the stroke time of the actuator or actuators is to be detected, the control device 4 is supplied, for example, with two signals via signal line RZ / HZ, the first then coinciding with the start and the second with the end of the stroke movement. The stroke time of the adjusting means can thus be determined by the time recording device 4 '.

The shift-dependent switching time SGD, which triggers the turning on or turning off of the blanket cylinder 2 from the pressure cylinder 3, can be brought forward by an amount of rotation angle which corresponds to the sum of the reaction time and the stroke time. It is thus achieved that the rubber cylinder 2 is always completely turned on or off before the end of the channel correspondence with the pressure cylinder 3.

A control device 4, which causes the switching times SGD, SGP to be advanced depending on the speed in conjunction with the sensors attached to the actuating means and the reaction and / or stroke times determined by the time recording device 4 ', can be referred to as a self-learning control system since the pressure medium is triggered depending on previously determined reaction and / or stroke times.

In a simple embodiment, control device 4 calculates the necessary switching times SGD, SGP for the point in time, that is to say the target positions of the machine at which the switching signals are to be applied to control lines 7, 8 after the pressure command has been given via command line 5. However, it is particularly advantageous if control device 4 calculates the required target positions, ie switching times SGD, SGP for printing on and off for the different speeds, for example once when the printing press is started up, and each target position for a specific one Speed range in its own memory cell. Each of these memory cells can then be addressed with the appropriate preparation via the speed signal of the signal line 9, ie the value written there and thus also the value corresponding to the speed is available after simple addressing. The target position for the necessary switching operations is thus directly available. As soon as the actual positions of the machine correspond to the target positions, the corresponding switching signals are provided on the control lines 7, 8, as already described.

An above determination of the switching times SGD, SGP, i.e. the target positions of the corresponding switching signals, the speed of the machine being used as the address, saves computing time and ensures that the necessary switching signals can be provided within a very short time.

The number of speed classes or speed ranges in which the entire speed range of the machine (standstill to maximum speed) is divided or quantized depends on the digital resolution of the speed signal, ie the maximum number of memory units that can be addressed by the speed signal. Accordingly, a large number of precalculated switching times SGD and SGP can be stored. This type of provision of target positions (angular position of the printing unit cylinders to one another) can be used in a simple manner to use a non-linear characteristic curve for the speed-dependent shifting timing advance. The quantization of the speed range can also be used in a targeted manner in order to reduce the number of switching times SGD, SGP and accordingly to provide only a few storage locations. With a small amount of memory, the memory access time is shortened, the switching times SGD, SGP according to the speed class in which the respective actual speed is located can be provided in the shortest possible time.

As already indicated, it is provided that the actuating means causing the pressure to be switched on or off are designed in the form of two double-acting pneumatic cylinders. The total of four working chambers of this actuating means can then be pressurized with compressed air by the control device 4 via signal lines 7, 8 and corresponding electrically switchable valves (solenoid valves). FIG. 5 shows an advantageous embodiment of an actuating means for switching the pressure on and off, which is not derived in a simple manner from the prior art, and which has two double-acting pneumatic cylinders 2.1 B, 2.1 C. The rubber cylinder 2 is mounted in a known manner on both sides in eccentric bushings 11 and can be adjusted by means of two-stage pivoting of the eccentric bushings 11 on the plate and printing cylinder 1, 3, can be switched off by the printing cylinder 3, while it remains on the plate cylinder 1 and can be completely switched off by both printing unit cylinders. 1 a, b, c result from the pivoting of the eccentric bushes 11 into the positions a, b, c in FIG. 5. The pivoting of the eccentric bushes 11 takes place via tabs 12 and release lever 13, which sit on a moving-off shaft 14 which extends across the machine width. Rotation of the detaching shaft 14 thus pivots the two eccentric bushes 11 into the pressure on or pressure stops according to a, b, c according to FIG. 1 and FIG. 5. The rotation of the detaching shaft 14 causes one on the machine side and out of the tabs 15 and 16 formed toggle lever gear with a frame-fixed abutment 17. Tab 15 is articulated on a further lever arm 18 of the release shaft 14. A link 19 is also articulated on the plate 15, which connects the piston rods 20B, 20C of two parallel-acting, double-acting pneumatic cylinders 21.b, 21.c, which are fixed to the frame and which are fixed to the frame. In the extended state, the piston rods 20.b 21.C bring the toggle lever mechanism of the tabs 15, 16 into an extended position, in which case rubber cylinders 2 are in contact with plate and pressure cylinders 1, 3.

The four working chambers of the pneumatic cylinders 21.8, 21.C are, for example, via solenoid valves from the control device 4 Compressed air can be applied via the control lines 7, 8. To turn off the rubber cylinder 2 from the pressure cylinder 3, the pneumatic cylinder 21.B is switched in such a way that the piston rod 20.B is immersed and thus brings the toggle lever mechanism of the tabs 15, 16 into a folded position via a coupling 19. If the pressure is to be switched off completely, the pneumatic cylinder 21.C is switched so that the piston rod 21.C retracts and, in a force-enhancing manner, also sets the toggle lever mechanism of the plates 15, 16 into a completely kinked position via coupling 19. The eccentric bushes 11 are now pivoted to position c (FIG. 5) and the rubber cylinder 2 is turned off from the plate cylinder 1. The pressure adjustment now also takes place in two phases by correspondingly actuating the working chambers of the pneumatic cylinders 21.B, 21.C, in which case first the piston rod 20.C extends (instead of the rubber cylinder 2 on the plate cylinder 1) and then the piston rod 20.B moves out and thus the Rubber cylinder 2 is placed on the pressure cylinder 1. Such a design of an adjusting means consisting of two pneumatic cylinders 21.B, 21.C combines the advantages of a parallel connection (addition of the lifting forces) with the advantages of a connection in series (addition of the stroke distance e) double-acting working cylinders. Since the pneumatic cylinders 21.B, 21.C can be switched individually by the control device 4 at the switching times SGD, SGP, the three positions of the rubber cylinder 2 described with respect to the plate cylinder 1 and pressure cylinder 3 can be approached. It is also possible to switch both pneumatic cylinders 21.B, 21.C at the same time for spontaneous pressure shutdown, that is to say to turn off the rubber cylinder 2 entirely from the pressure cylinder 3 and also the plate cylinder 1.

6a shows an embodiment of the sensor system on the pneumatic cylinder 21.B. The design of the sensors on the pneumatic cylinder 21.C is the same. Accordingly, a sensor 22 is arranged in the region of the piston rod 20.B, so that two markings 23 attached to the piston rod 20.B can be scanned through it. If the piston rod 20.B is almost completely extended (almost the upper end position), thus, as shown, the lower marking 23 corresponds to the sensor 22. When the piston rod 20.B is almost completely retracted, the upper marking 23 corresponds accordingly (not shown) to the sensor 22. In accordance with its principle of operation, the sensor 22 is designed to emit a signal precisely then when one of the two markings 23 faces it.

If pneumatic cylinder 21.B is switched in such a way that piston rod 20.B plunges from the extended end position (FIG. 6) into the retracted end position, sensor 22 gives a pulse at the beginning of the movement of piston rod 20.B and one at the end of the movement of Piston rod 20.B from. The arrangement of the sensors 22 described in conjunction with the markings 23 enables both the stroke time and the reaction time of the pneumatic cylinder 21b to be recorded (time recording device 4 '). Since there are sensors 22 and markings 23 on both pneumatic cylinders 21.B, 21.C, the signals (eg pulses) supplied by the two sensors 22 are fed to the control device 4 or the time recording device 4 'via two signal lines RZ / HZ (FIG 4).

The sensors 22 can be designed as optical reflex scanners or as Hall sensors or so-called reed contacts. Accordingly, the markings 23 are optically scannable marks (blackening) or a small, permanently magnetic area in the piston rod 20.B or 20.C. The last-mentioned design of the sensors 22 together with the marking 23 is considered to be particularly advantageous since this type of scanning is largely independent of the degree of contamination of the piston rod 20.B, 20.C. Of course, other sensor arrangements or a sensor system operating according to a different operating principle can also be used, only one signal (pulse) having to be provided by the sensor system at the beginning and at the end of the piston movement.

Another variant of the sensor system is shown in FIG. 6b. Two sensors 22 (Hall sensors) are provided here, which are arranged on the pneumatic cylinder 21.B in the region of the end positions of its working piston (dashed lines). The piston has, for example, a permanent magnetic area for the sensors 22.

Reference list

1

Plate cylinder

1.1

Channel plate cylinder

2nd

Rubber cylinder

2.1

Channel rubber cylinder

3rd

Impression cylinder

3.1

Duct pressure cylinder

4th

Control device

4 '

Time recording facility

5

Command management

6

Angle of rotation encoder

7

Control line

8th

Control line

9

Signal line speed

10th

Main drive control

11

Eccentric bushing

12th

Tab

13

Release lever

14

Breakaway wave

15

Tab

16

Tab

17th

Abutment

18th

Lever arm

19th

Paddock

20.B

Piston rod

20.C

Piston rod

21.B

Pneumatic cylinder

21.C

Penmatic cylinder

22

sensor

23

mark

THERE

Start of printing

DE

End of printing

SGD

Switching point (machine position) for switching rubber cylinder 2 on and off with respect to pressure cylinder 3,

SGP

Switching point (machine position) for switching the rubber cylinder on and off with respect to the plate cylinder 1

RZ / HZ

Signal line

Claims (11)

1. Sheet printing press with at least one printing unit in which at least the blanket cylinder is actuatable for print throw on and off by adjusting means which become active on application of pressure medium, wherein the triggering of the application of pressure medium takes place controlled by a control unit sensing the angular position of the printing unit cylinders, characterised in that the actual rotational speed of the printing unit can also be fed to the control unit (4) and that the control unit (4) is so constructed to advance the release points in time (switching time points SGD, SGP) for the application of the pressure medium in such a fashion in dependence upon the actual rotational speed of the printing unit in the rotational direction of the printing cylinders so that the adjusting means for each actual rotational speed of the printing unit become effective exclusively in the region of the oppositely lying cylinder channels (1.1, 2.1, 3.1).
2. Offset sheet printing press according to Claim 1, characterised in that for determining the angular position of the printing unit cylinders, a high resolution angular position sensor (6) is fixed on a shaft turning synchronously with the printing unit (one turn shaft) and that the angular position of the printing unit cylinders can be fed to the control unit (4) in digital form.
3. Offset sheet printing press according to Claim 1 or 2, characterised in that to sense the actual rotational speed of the printing unit, a rotational speed signal can be extracted from the control of the main drive (10) and this can be fed to the control unit 4.
4. Offset sheet printing press according to one of the preceding Claims, characterised in that the application of pressure medium to the positioning means takes place via electrically switchable valves (magnet valves) which are in operational connection with the control unit 4.
5. Offset sheet printing press according to one of the preceding Claims, characterised in that with sensors (22) fixed to the adjusting means in combination with a time sensing unit (4'), the periods of time between the release time points (switching time points SGD, SGP; application of pressure medium) at the beginning of a movement carried out as a result by the adjusting means can be sensed (reaction time) and that the control unit (4) is so constructed that it prepares advance release points in time (switching time points SGD, SGP) for desired print throw on and throw off processes additionally also in dependence on these determined time periods (reaction times).
6. Offset sheet printing press according to one of the preceding Claims, characterised in that with sensors (22) fixed on the adjusting means in combination with a time sensing unit (4'), the periods of time which the adjusting means require in order to carry out the movements effecting the throwing on and throwing off processes can be sensed (stroke time) and that the control unit (4) is so constructed that it can prepare advanced release points of time (switching time points SGD, SGP) for future print throw on and throw off procedures additionally also in dependence on these determined time periods (stroke times).
7. Offset sheet printing press according to one of the preceding Claims, characterised in that the adjusting means are constructed in each printing unit as double acting working cylinders which become active on being subjected to compressed air.
8. Offset sheet printing press according to Claim 7, characterised in that the piston rods (20.B, 20.C) of two double acting pneumatic cylinders (21.B, 21.C) are connected pivotally with a yoke (19), this is pivoted to one link (15) of a toggle lever drive formed from the links (15, 16) which is supported on a counterbearing (17) fixed to the frame and that the eccentric bushes (11) bearing the blanket cylinder (2) are swivellable via links (12) and throw off levers (13) seated on a throw off shaft (14), in which link (15) of the toggle lever drive constituted by links (15, 16) is pivoted to a lever arm (18) of the throw off shaft (14).
9. Offset sheet printing press according to Claim 5 and/or 6 and Claim 8, characterised in that the pneumatic cylinders (21.B, 21.C) in the region of their piston rods (20.B, 20.C) have, in each case, a sensor (22) by which two markings (23) applied to each piston rod (20.B, 20.C) can be sensed.
10. Offset sheet printing press according to Claim 9, characterised in that the markings (23) are constructed as optically sensable markings and that the sensors (22) are constructed as optical reflex sensors.
11. Offset sheet printing press according to Claim 9, characterised in that the markings (23) are constructed as permanent magnetic regions and that the sensors (22) are constructed as Hall effect sensors or as reed contacts.

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