GB2225556A

GB2225556A - Printing press control system

Info

Publication number: GB2225556A
Application number: GB8923861A
Authority: GB
Inventors: Dieter Hauck; Edmund Schramek
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 1988-10-25
Filing date: 1989-10-24
Publication date: 1990-06-06
Anticipated expiration: 2009-10-24
Also published as: FR2638122B1; GB8923861D0; DE3836310C2; JPH02171246A; GB2225556B; DE3836310A1; FR2638122A1

Description

1 2225556 - 1

DESCRIPTION

PRINTING PRESS CONTROL SYSTEM The invention relates to a process as defined in the main claim.

In printing presses, particularly in multi-colour rotary offset printing presses, it is necessary for various functions to be switched on and off depending on the respective position of the printing press or on the distance that has so far been covered by the printed sheet. Thus, for example, the rubber-covered cylinder and the backpressure cylinder may be operated together only when the sheet is in the printing unit. In known printing presses, scanning discs are provided on the relevant cylinders and shafts in order to control such switching operations, said scanning discs supplying a switching signal when a specified angular position is reached. Furthermore, signals are supplied by optical sensors when the printed sheet is in defined positions. These measures, however, necessitate an elaborate construction and cannot readily be adapted to different printing presses. They require, for example, different forms of realization for printing-press units that are of different developed lengths (printing unit, varnishing unit, drier etc.) as well as for perfecting units (recto-and-verso printing units). In addition, the number of prints is limited by scanning the sheet with optical sensors.

The object of the present invention is to indicate a process for the control of switching operations on a printing press, said process being characterized by simplicity of construction and being able to be adapted in simple manner to different printing presses and different operating conditions.

The process according to the invention, having the characterizing features of the main claim, has the advantage that, in addition to an incremental sensor, no further sensor or only few further sensors are necessary, depending on the particular design of printing press. A further advantage consists in the fact that a printing press controlled by the process according to the invention can be adapted in simple manner to different operating modes, for example to recto printing or recto-and- verso printing, and to different printed-sheet lengths.

The measures enumerated in the subclaims permit advantageous further developments of and improvements to the process indicated in the main claim as well as advantageous arrangements for the implementation thereof.

in particular, in further developments of the invention, the switching operations for recto-and-verso printing are adapted in advantageous manner to the respective printed-sheet length.

Another further development of the invention allows a considerable simplification in the switching of the printing press from recto printing to recto-and-verso printing.

1..

Specimen embodiments of the invention are explained in greater detail in the following description and are represented in the drawings with reference to several Figures, in which:

Fig. 1 shows a schematic representation of an arrangement for the implementation of the process according to the invention; Fig. 2 shows an example of a control circuit provided for the arrangement shown in Fig. 1; Fig. 3 shows timing diagrams of various signals for the arrangement shown in Fig. 1 and Fig. 4 shows a flowchart of a program, said program being provided for the implementation of the process according to the invention.

Identical parts in the Figures are provided with identical reference characters.

In the arrangement according to Fig. 1, switching operations, for example in a sheet-fed offset printing press 1 with two printing units 2, 3, are controlled by the process according to the invention. The printing press 1 further comprises a sheet feeder 4 and a sheet delivery 5, apparatuses 6, 7 for switching printing on and off in the two printing units 2, 3 and apparatuses 8, 9 for engaging and disengaging the forme rollers, likewise in both printing units 2 and 3. In addition, a drier 10 and a dusting unit 11 are provided.

Since the apparatuses 6 to 9 as well as the drier 10 and the dustinq unit 11 are known and their details are not of relevance in connection with the invention, they are represented merely schematically in the drawing. In order to establish the respective position of the printing 1 press, an incremental sensor 12 is provided in the region of the drive of the printing press 1. Furthermore, an optical sensor in the form of a reflected-light barrier 13 is disposed on a turning drum 15, which, together with a storage drum 14, is part of a turning apparatus. Situated in the region of the second printing unit 3 is a scanning disc 17, which interacts with a switch 18, said switch 18 supplying a switching signal at a specified angular position.

The incremental sensor 12, the optical sensor 13 and the switch 18 are connected to inputs of a control apparatus 20, while the apparatuses 6 to 9, the drier 10 and the dusting unit 11 are connected to outputs of the control apparatus 20.

The control apparatus 20 consists basically of a control circuit 21, a format-measuring circuit 22, a keyboard 23 and a selector switch 24. The output pulses of the incremental sensor 12 are supplied both to the control circuit 21 and also to the format-measuring circuit 22. Through the intermediary of the selector switch 24, either the optical sensor 13 or the switch 18 can be connected to the format-measuring circuit, with this making it possible to select one of two different options for measuring the printed-sheet length or the format. Details in this regard will be described later. The printed-sheet length and the format may also be inputted via the keyboard 23. The measured or inputted format is sent by the formatmeasuring circuit to the control circuit and is taken into account in the switching operations that take place after he turning drum 15.

Fig. 2 shows the control circuit 21 (Fig. 1). The incremental sensor consists, for example, of an index disc provided with optical marks, said index disc being scanned by opto-electric receivers. In this connection, one of the opto-electric receivers supplies a pulse 0 during each 1 1 revolution. In addition, angular-speed signals A and B are generated, said angular-speed signals A and B being wave-like in form and being phase-displaced by 900 with respect to one another. In a customary incremental sensor, the angular-speed signals A and B each comprise 1,024 pulses per revolution.

The angular-speed signals A and B are evaluated in order to detect the direction of rotation and the position of the printing press. In order to detect the direction of rotation, the angular-speed signals A and B are supplied to a circuit 31. The circuit 31 comprises two outputs 32, 33, with a signal to identify the direction of rotation being supplied at output 32 and with a pulse being supplied at output 33 if there is a change in the direction of rotation. While the direction-of-rotation identification signal is supplied to a data input of a computer 30, the pulse at output 33 generates a program interrupt (IR).

In order to detect the position, the angular-speed signals A and B and the pulse 0 are supplied to a counter circuit 34. Furthermore, it is provided that the pulse 0 triggers a program interrupt and resets the counter circuit, with the result that the count indicates the position or the angle of rotation with reference to a starting position. In the arrangement according to Fig. 1, this value is supplied as an actual position to a comparator 35, where it is compared with a setpoint position, which was previously written to a register 36 by the computer 30 via a bus system 38. When the printing press has reached the setpoint position, both values are identical and the comparator 35 triggers a program interrupt, whereupon the computer initiates the switching operations intended for the setpoint position. Immediately thereafter, a new setpoint position may be inputted via the register 36. Until the printing press reaches this new setpoint position, it is not necessary for the position of the printing press to be continuously detected in the computer.

Via the bus system 38, the computer 30 is also connected to a memory 39, in which the data of the respective printing press are permanently stored. These data are basically the positions, i.e. the angular positions of the incremental sensor, at which the switching operations, likewise stored, are to be triggered. Depending on the respective distance covered by the printed sheet on its way through the printing press, these angular positions comprise not only values from 00 to 36C, but also higher values.

Furthermore, the computer 30 can be supplied with data via an interface 47 from the format-measuring circuit 22 and via a further interface 48 from the keyboard 23. Finally, an output unit 40 is provided, the outputs of which are connected via power stages 41 to 46 to the apparatuses 6 to 11 (Fig. 1). Via these, the computer is able to trigger the individual switching operations.

When printing is started, a program is started in the computer 30, said program comparing the angular positions previously loaded from the memory 39 into a working memory of the computer with the angular position of the incremental sensor 12. For this purpose, first of all, the smallest of the stored angular positions is written to the register 36. When the counter 34 reaches the same value, the comparator 35 triggers a program interrupt. Thereupon, the computer checks which switching operation belongs to said angular position and sends appropriate data to the output unit 40. Then, the computer 30 loads the next angular position into the register 36, and so on. In this connection, it may well be the case that, at a given angular position, more than one switching operation is triggered. In the case of recto-and-verso printing, the angular positions are converted according to the data received from the format-measuring circuit 22 or from the keyboard 23. This relates merely to the data after the turning drum 15 (Fig. 1). In the case of printing presses with more than two printing units, the format is taken 1 1 1 into account with appropriate frequency in the case of multiple turning of the printed sheeti In the following, the operating principle of the formatmeasuring circuit is explained with reference to the timing diagrams in Fig. 3. Lines a) to c) show the angular-speed signals 0, A and B supplied by the incremental sensor 12. The leading edge of the angularspeed signal 0 identifies the zero position (00) of the printing press. owing to the large number of angularspeed signals A and B occurring during one revolution, these are represented on an enlarged time scale and only in the region of the zero position. Line d) shows a signal generated by the switch 18 (Fiq. 1). The scanning disc 17 is mounted in'such a manner that, in recto printing, the trailing edge of the signal SO coincides precisely with the leading edge of the signal 0.

If the printing press is switched to recto-and-verso printing, there is a rotation of the turning drum 15 with respect to the storage drum 14 by an angle said angle being dependent on the length of the printed sheet. The entire following printing unit is also shifted by this angle with respect to the incremental sensor 12. The signal of the switch 18 is correspondingly phase displaced. Line e) shows a signal S1 in the case of a small printed-sheet length, while line f) represents a signal S2 in the case of a larger printed-sheet length.

The corresponding displacement angle 1 or 2 is measured by counting the angular-speed signals A or B and is communicated to the computer 30 via the interface 47 (Fig.

2).

The determination of the displacement angle according to the length of the printed sheet may, however, also be performed with the aid of an optical sensor 13. In order to explain this process, output signals of the optical sensor 13 for different angular positions are shown in lines g), h) and i) in Fig. 3. Since the optical sensor 1 - 8 13 generates a signal not only when paper passes the optical sensor, but also when metallic parts of the cylinder pass the optical sensor, the signal shown in lines b) to i) consists of a plurality of individual pulses, said pulses forming a signal pattern that is repeated on each revolution. This signal pattern may be stored in known manner such that a comparison is possible between the, in effect, identical, but phase- displaced signal pattern and a stored signal pattern. From the displacement of the two signal patterns with respect to one another, a conclusion is made with regard to the rotation of the printing units.

With the aid of a further development of the invention, the rotation between the storage drum 14 can be performed in simple manner as follows for the respective printedsheet length. After the disengagement of a coupling between the drums 14, 15 that are to be turned and after the locking of the printing unit 3 with a catch 16 (indicated schematically in Fig. 1), the printing unit 2 and with it the storage drum 14 are turned with the aid of the drive until the rotation necessary for the respective format has been reached. This is determined, likewise with the aid of the control circuit 21 (Fig. 1), by comparison with a value that has been inputted via the keyboard 23. The drive is then automatically switched off; the drums are again coupled to one another and the printing unit 3 is unlocked.

In addition, the process according to the invention may also be used to move the printing units to specific angular positions. This is necessary, in particular, for the clamping-inplace and removal of the printing plates, so that the fixing screws for the printing plates are accessible.

Fig. 4a) represents a program that is run through for initialization after switching-on. After the start at 51, a table with switching-degree numbers (stored angular 1 1 1 positions) is loaded at 52 in accordance with the particular type of printing press that is to be controlled. Thereupon, there is a branch 53, at which it is checked whether the printing press is set to verso printing. If this is the case, all switching-degree numbers that stand for switching operations after the turn are corrected in program part 54 in accordance with the length of the printed sheet. After the branch 53 and after the program part 54, the switching-degree numbers are sorted in ascending order at 55. In program part 56, the register 36 (Fig. 2) is loaded with the first switching-degree number. Thereafter, at 57, the interrupt input, to which the comparator 35 is connected, is enabled, whereupon the initialization program 58 is terminated.

Fig. 4b) represents a program that is executed each time an interrupt is initiated by the comparator 35 (Fig. 2). After the interrupt 61, at 62, the switching program intended for the respective angular position or switchingdegree number is called up. Thereafter, at 63, there is a program branch depending on whether the register 36 has been loaded with the highest switching-degree number. If this is not the case, the register with the next-higher switching-degree number is loaded at 64. If the highest switching-degree number is already in the register 36, the register 36 is loaded with the lowest switching-degree number at 65. Thereafter, at 66, the interrupt input for the comparator 35 is again enabled, whereupon, at 67, the interrupt program is terminated and the computer is able to continue to execute the program that has been interrupted.

1 - It will be understood that the invention has been described above purely by way of example, and that various modifications of detail can be made within the ambit of the invention.

-1 1 - 11

Claims

1. Process for the control of switching operations on a printing press in which an angle sensor is provided on a shaft, characterized in that the respective angular position is compared with stored angular positions and, in case of agreement, a switching operation assigned to the respective angular position is triggered.

2. Process according to claim 1, characterized in that, in a printing press, said printing press being switchable between recto printing and recto-and-verso printing, the stored angular positions relating to switching operations after the turning of the respective printed sheet are compared with the respective angular position, taking account of the length of the printed sheet.

3. Process according to claim 2, characterized in that the length of the printed sheet is measured with the aid of an opto-electric apparatus in the region of the printing press after the turning apparatus.

4. Process according to claim 2, characterized in that, in the case of recto-and-verso printing, the length of the printed sheet is established by comparison of the respective angles measured by the angle sensor and the output signal of an angle-of-rotation-dependent switching a 12 apparatus (scanning disc), said switching apparatus being disposed after the turning apparatus.

5. Process according to claim 2, characterized in that the length of the printed sheet is inputted manually.

6. Process according to claim 1, characterized in that the switching on/off of printing and the engagement/ disengagement of the forme rollers are triggered on one or more printing units of a printing press.

7. Process according to claim 6, characterized in that, in addition, a dusting unit is adapted to be switched on/off.

8. Process according to claim 6, characterized in that, in addition, a drier is adapted to be switched on/off or to be set to standby.

9. Arrangement for the implementation of the process according to the invention, characterized in that the angle sensor is formed by an incremental sensor, said incremental sensor being connected to a counter.

10. Arrangement according to claim 9, characterized in that the incremental sensor is disposed on a shaft of the drive train of the printing press.

11. Process according to claim 1, characterized in that, in order to switch the printing press from recto printing to recto-and-verso printing, a coupling is disengaged and that part of the respective printing unit that is consequently no longer connected to the drive of the printing press is locked, in that the drive of the printing press is started while the respectively travelled angle of rotation is compared with an angle of rotation specified for the length of the sheet being used and in 1 1 t a that, in the case of agreement, the drive is stopped and thereafter the coupling is engaged and the locking is cancelled.

12. Process according to claim 1, characterized in that 'ected by a the stopping of the printing press is ef'. switching operation and in that at least one of the stored angular positions corresponds to a position of the printing press suitable for maintenance and/or setting-up work.

13. Process according to claim 12, characterized in that, by the actuation of a certain control element, the drive of the printing press is started, a comparison of the current angular position with a stored angular position assigned to the control element is performed and, in case of agreement, the drive is switched off.

A printing press having at least one shaft on which an angle sensor is provided, and having incorporated in it, or operatively associated with it, components so designed and arranged as to permit, in use, the control of switching operations on the printing press by a process as specified in any of claims 1 to 8 and 11 to 13.

15. A printing press as claimed in claim 14, employing an arrangement as claimed in claims 9 or 10.

16. A printing press as claimed in claim 14, having a switching operation control system substantially as described with reference to any Figure or Figures of the accompanying drawings.

17. Process as claimed in claim 1, substantially as described with reference to any Figure or Figures of the accompanying drawings.

Published 1990al The PatentOffice.stateliOuSla.6e 71 Hi9hHoborn. LcndonWC1R4TP Further copies rnkybe obtained froinThc Pazent Office Sales Branch. St Ma:.-,, Cray, Orpington. Kent BR5 3RD Printed ky Multiplex techniques ltd. St Mary Cray, Kent. Co 1 8'

-111- Amendments to the claims have been filed as follows 1. Process for the control of switching operations on a printing press in which an angle sensor is provided on a shaft, characterized in that the respective angular position is established as a numerical value which represents a multiple of an angular increment, and in that the respective numerical value is compared with predetermined electronically stored numerical values and, in case of agreement, a switching operation assigned to the respective angular position is triggered.

4. Process according to claim 2, characterized in that. in the case of recto-and-verso printing, the length of the printed sheet is established by comparison of the respective angles measured by the angle sensor and the output signal of an angle-of-rotation-dependent switching - Isapparatus (scanning disc), said switching apparatus being disposed after the turning apparatus.

7. Process according to claim 6, characterized in that. in addition, a dusting unit is adapted to be switched on/off.

11. Process according to claim 1, characterized in that, in order to switch the printing press from recto printing to recto-and-verso printing, a coupling is disengaged and that part of the respective printing unit that is consequently no longer connected to the drive of the printing press is locked, in that the drive of the printing press is started while the respectively travelled angle of rotation is compared with an angle of rotation specified for the length of the sheet being used and in that, in the case of agreement, the drive is stopped and thereafter the coupling is engaged and the locking is cancelled.

12. Process according to claim 1, characterized in that the stopping of the printing press is effected by a switching operation and in that at least one of the stored angular positions corresponds to a position of the printing press suitable for maintenance and/or setting-up work.

13. Process according to claim 12, characterized in that. by the actuation of a certain control element, the drive of the printing press is started, a comparison of the current angular position with a stored angular position assigned to the control element is performed and, in case of agreement, the drive is switched off.

14. A printing press having at least one shaft on which an angle sensor is provided, and having incorporated in it, or operatively associated with it, components so designed and arranged as to permit, in use, the control of switching operations on the printing press by a process as specified in any of claims 1 to 8 and 11 to 13.