US3507215A

US3507215A - Dampening device for an offset printing press

Info

Publication number: US3507215A
Application number: US664692A
Authority: US
Inventors: Siegfried Schuhmann
Original assignee: Roland Offsetmaschinenfabrik Faber and Schleicher AG
Current assignee: Roland Offsetmaschinenfabrik Faber and Schleicher AG
Priority date: 1966-09-09
Filing date: 1967-08-31
Publication date: 1970-04-21
Anticipated expiration: 1987-04-21
Also published as: GB1167968A; DE1279690B

Description

April 21, 1970 s. SCHUHMANN 3,507,215

DAMPENING DEVICE FOR AN OFFSET PRINTING PRESS 5 Filed Aug. 31, 1967 Inventor.- SlEG-Fm en San uH mam! BY Curl- United States Patent 3,507,215 DAMPENIN G DEVICE FOR AN OFFSET PRINTING PRESS Siegfried Schuhmann, Offenbach am Main, Germany, as-

signor to Roland Ofisetmaschinenfabrik Faber & Schleicher A.G., Offenbach am Main, Germany, a German firm Filed Aug. 31, 1967, Ser. No. 664,692 Claims priority, application Germany, Sept. 9, 1966,

Int. Cl. B41f 25/16, 31/12, 33/10 U.S. Cl. 101-148 6 Claims ABSTRACT OF THE DISCLOSURE A dampening device for an offset printing press in which a supervisory means is activated when the press has completed a predetermined number of operational cycles after feed of moisture to a roller for applying moisture to the plate cylinder of the press has been initiated. Activation of the supervisory means is utilized either to indicate that the roller is ready to be manually moved into engagement with the plate cylinder of the press or to initiate automatically such movement. The dampening device further includes means which reduce for a predetermined number of cycles the moisture feed from the roller to the plate cylinder when the latter is in engagement with the roller but the blanket cylinder is not in engagement with the plate cylinder and the impression cylinder. When during said predetermined number of cycles the blanket cylinder is moved into engagement with the plate cylinder and the impression cylinder to start printing, the moisture feed by the roller to the plate cylinder is restored to normal but if the blanket cylinder is not moved into such position the moisture feed is stopped completely.

The invention relates to dampening devices for offset printing machines with a cylinder trip mechanism, and more particularly, to dampening devices including means for selectively discontinuing moisture feed to rollers which are movable into and out of engagement with the plate cylinder of the press for applying moisture thereto.

There are known dampening devices including a ductor roller dipping into a liquid supply. The moisture is transmitted from the ductor roller to moisture applying rollers by continuous or intermittent contact with intermediate rollers or by means of a lifting roller. The ductor roller feeds the moisture taken up by it to form rollers which, in turn, transfer the moisture to the plate cylinder of the press. Control of the moisture feed is effected by changing the rotational speed of the ductor roller, by changing the frequency of the oscillations of the lifting roller, by changing the mutual pressure between the coacting rollers or by additional squeezing rollers. Moisture applying form rollers as used in dampening devices are generally coated with layers of natural fabric, paper or synthetic fabric, or have a rubber coating.

Depending upon the type of coating on the form rollers and the liquid which is used, the so-called moisture capacity of the form rollers changes and thus also the length of time required for adjusting and stabilizing the moisture content of the form roller and thus of the plate cylinder.

As is evident, as soon as the press is stopped the coating on the form roller begins to dry. The extent of such drying depends, of course, upon the length of the stoppage and the prevailing atmospheric conditions. In any event, the printer must manually supply moisture to the form roller prior to the starting of a printing operation or resumption of a printing operation. It is customary that the printer supplies to fabric covered form rollers an excess of moisture to prevent a smudging of the rotating rollers with ink. When the form rollers are coated with rubber, the available moisture supplying time is so short that a single feed of moisture by the printer is generally not sufficient. Experience shows that there is a danger of dryingout of the surface of rubber coated form rollers even during a short period of stoppage if the moisture feed cannot be maintained during such stoppage. Continuing 10 the supply of the moisture feed without change in quantity is not practical due to the low moisture capacity of rubber coated form rollers and also due to the change in the ratio between supply of moisture and consumption thereof when and while printing is stopped.

To leave dampening of the moisture applying rollers prior to the starting of a printing operation or to the resumption of the printing operation after a stoppage, to the judgment of the printer is risky. Obviously, misjudgment by the printer can result in wrong tones on the plate and also in emulsifying of the ink with the supplied moisture. Either effect is highly undesirable.

It is a broad object of the present invention to eliminate the aforepointed out disadvantages of dampening devices as heretofore known and to provide a novel and improved dampening device which permits an accurate control of the supply of moisture from the moisture applying roller to the plate cylinder in accordance with the actually existing conditions.

A more specific object of the invention is to provide a novel and improved dampening device of the general kind above referred to in which a counting means indicates when the moisture applying roller is ready to be moved into engagement with the plate cylinder.

Another more specific object of the invention is to provide a novel and improved dampening device in which an adjustable counting means signals that the roller is ready for movement into engagement with the plate cylinder when a predetermined number of operational cycles has been completed after starting the supply moisture to the roller. As a result, the moisture applying roller is moved into engagement with the plate cylinder only when the roller is sufficiently moist. The extent of moisture taken up by the roller is variable by varying the number of cycles but a degree of moisture content which has been found to be favorable can be reproduced at any time without difiiculty.

Another more specific object of the invention is to provide a novel and improved dampening device of the general type above referred to in which the counting means automatically initiates movement of the moisture applying roller into engagement with the plate cylinder when a predetermined number of cycles has been completed after starting of the moisture feed to the roller.

It is also an object of the invention to provide a novel and improved dampening device of the general kind above referred to in which a second counting means reduces the feed of moisture to the plate cylinder to a lower value 'for a selected number of cycles when the printing operation has been discontinued but the moisture applying roller remains in engagement with the cylinder. This has the advantage that during short periods of stoppage the dampening device remains operational and that at the same time the reduced consumption of moisture due to the discontinuance of the printing operation is compensated by a correspondingly reduced moisture feed to the plate cylinder.

The reduction in the moisture feed can be effected by various means depending upon the type of dampening device used for instance, reducing the r.p.m. of a ductor roller, by decreasing the oscillation frequency of a swinging lifting roller or by changing the mutual pressure be:

3 tween coacting intermediate rollers. The maximum period of time during which the reduced moisture feed is to be maintained can be readily and accurately adjusted in accordance with the time of the expected stoppage.

The invention also provides that the second counting means effects the disengagement of the moisture applying roller and thus interruption of the moisture feed to the plate cylinder upon completion of the selected number of cycles. The dampening device is thus automatically rendered inoperative after a selected period of time when the printing operation is not resumed within such period. In other words, a continued and undesired operation of the dampening device is avoided.

The counting means according to the invention may be electrically or mechanically operated for instance, electric counters and time relays may be used or mechanical counters.

Other objects, features and advantages of the invention will be pointed out hereinafter and set forth in the appended claims constituting part of the application.

In the accompanying drawing a preferred embodiment of the invention is shown by way of illustration and not by way of limitation.

In the drawing:

FIG. 1 is a diagrammatic elevational view of an offset printing press equipped with a dampening device according to the invention;

FIG. 2 is a diagrammatic elevational view of the dampening device, the form roller being shown in engagement with a plate cylinder of the press;

FIG. 3 is a view similar to FIG. 2 but showing the roller withdrawn from the plate cylinder;

FIG. 4 is a block circuit diagram of the device. Referring now to the figures more in detail, FIG. 1 shows a plate cylinder 2, a blanket cylinder 3 and an impression cylinder 4 rotatably mounted in a conventional manner in side walls 1 of the frame structure of the press. A conventional inker mechanism is diagrammatically indicated at 5 and the dampening device at 6. The blanket cylinder 3 is journalled in eccentric bearings 7 so that it can be moved into and out of engagement with plate cylinder 2 and impression cylinder 4 by being rotated in its bearings. If current is supplied to a solenoid 8 bearings 7 are turned in clockwise direction, thereby moving the blanket cylinder into thrown-in position, shown in full lines. Excitation of solenoid 9 turns the bearings 7 in counterclockwise direction thereby moving the blanket cylinder into the thrown-off position shown in dotted lines. T urning of bearings 7 is limited by

stops

10 and 11.

The shaft of impression cylinder 4 mounts a nose 12 which actuates a switch 13 during each revolution of the cylinder.

As is shown in FIGS. 2 and 3, the dampening device 6 according to the invention comprises a ductor roller or water fountain roller 15 dipping into a receptacle 14 filled with water or another suitable liquid. The ductor roller is rotated by a speed variable electromotor 16 via a gearing 17 and a chain 18. Ductor roller 15 engages with controllable pressure a water vibrator roller 19 which is rotated in a conventional manner by plate cylinder 2 via gears. The vibrator roller 19 is seated on a shaft 45 on which are also seated two-arm levers 20 each of which supports on one arm a form roller 21 for applying moisture to the plate cylinder. Roller 21 is journalled in eccentric bushings 22 the angular position of which controls the pressure between roller 21 and water vibrator roller 19. A spring 23 stationarily mounted on one end and secured with its other end to the second arm of levers 20 urges the levers into engagement with a stop 24 in which position roller 21 is withdrawn from plate cylinder 2 as is shown in FIG. 3.

To move roller 21 into engagement with cylinder 2 a solenoid 25 is energized. A core 25a of this solenoid is linked to the second lever arm so that upon energizetion of the solenoid levers 20' and with its roller 21 are pivoted from the position of FIG. 3 into the position of FIG. 2. A set screw 26 also coacting with levers 20 serves to adjust the maximum pressure with which roller 21 can engage plate cylinder 2.

The operation of the dampening device according to the invention will now be described in connection with the block diagram of FIG. 4.

To start the press, a drive motor 28 thereof is connected to a power line 29 by operating a switch 27. To begin a printing operation, a switch 30 is operated thereby connecting motor 16 to the power line. The motor now turns at its fully working speed. Operation of switch 30 also connects switch 13 into the circuit. As stated before, this switch is once operated by nose 12 during each rotation of impression cylinder 4 and each operation of the switch feeds a pulse to an adjustable counter 31. This counter is set for a predetermined number of rotational cycles of the cylinder and when this number is reached a suitable audible or visual supervising means such as a signal lamp 32 is connected. As has been explained before, activation of the supervising means indicates that the fabric or other layer on roller 21 has absorbed sufficient moisture and that the roller is now ready to be moved into engagement with plate cylinder 2. The roller is moved into such engagement by manual operation of a switch 33 which when operated connects solenoid 25 with the power line.

The dampening device now functions in a conventional manner.

Instead of effecting movement of roller 21 into engagement with plate cylinder 2 by manual operation, the dampening device can also be arranged for automatic operation. To this end the signal lamp 32 is connected by a wire 32a to switch 33 so that simultaneously with connecting lamp 32 to the power line by counter 31 switch 33 is automatically operated. Accordingly, lamp 32 in conjunction with switch 33 constitutes an automatically operated supervising means. Illumination of lamp 32 then indicates that roller 21 is in engagement with plate cy1in der 2 and has started feeding moisture to the same.

The press is now ready for printing.

After the paper feed to the press has been started, solenoid 8 is energized by operating a starter switch 34 for the press. As previously stated, solenoid 8 is part of a cylinder trip mechanism for moving blanket cylinder 3 into engagement with plate cylinder 2 and impression cylinder 4, solenoid 9 being the solenoid of the mechanism for disengaging cylinder 3 from cylinders 2 and 4.

Operation of switch 34 also causes via a wire 35 resetting of counter 31 to its zero position. The counter is thus ready for the next cycle and lamp 32 blinks out. When new a switch 36 is operated either manually or by a conventional detecting device and causes energization of solenoid 9 and thus withdrawal of the blanket cylinder from the two other cylinders, a second adjustable counter 37 is readied for pulses fed to it by switch 13. Moreover, a speed regulator 39 for motor 16 is set via a wire 38 so that motor 16 now rotates with a rotational speed less than its normal working speed. As a result, roller 21 which remains in engagement with plate cylinder 2 will supply to this cylinder less moisture than if motor 16 runs at full speed but with still sufiicient moisture so that the press is immediately ready for resumption of the printing operation, if desired.

Counter 37 is set for a pre-selected number of cycles and if printing is resumed by operation of starter switch 34 before the number of cycles set in counter 37 has been reached, the counter is reset to zero via a wire 40. Moreover, the r.p.m. of motor 16 is brought back to the full working speed via wire 38 and speed regulator 39. However, if printing is not resumed before the number of cycles for which counter 37 is set is reached, solenoid 25 is disconnected via a switch 41 and as a result, roller 21 becomes disengaged from plate cylinder 2. Furthermore, the speed regulator is reset for the full rotational speed of motor 16 via wire 38 and the motor 16 itself is disconnected by switch 30.

The next cycle is initiated as hereinbefore described by again operating starter switch 30. By opening switch 27 motor 28 is stopped and all the circuit components return into the starting position thereof.

Switches

27, 30, 33, 34 and 36 are preferably in the form of heavy current relays which hold contacts for locking-in the circuit components in a conventional manner. Circuit connections suitable for the purpose are well known and are not shown to simplify the circuit diagram.

What is claimed is:

1. A dampening device for an olfset printing press including a blanket cylinder movable into and out of a throw-in position with a plate cylinder and an impression cylinder, and a moisture-applying roller movable into and out of moisture-transmitting engagement with said plate cylinder, said dampening device comprising in combination:

moving means for moving said moisture applying roller into and out of moisture transmitting engagement with the plate cylinder;

means for supplying moisture to said roller;

powder driven actuating means operable for activating said moisture supplying means to supplying moisture to said roller at a predetermined rate;

blanket cylinder moving means for moving the blanket cylinder into and out of the throw-in position;

a supervising means arranged to be operated upon moistening of the roller to a degree selected as being sufficient for movement of the roller into moisture-transmitting engagement with the plate cylinder;

first adjustable counting means counting operational cycles of the printing press and connected in an energizing circuit with said supervising means to operate the same upon completion of a predetermined number of cycles, said first counting means being connected in an energizing circuit with said power driven actuating means to be activated by the same for said predetermined number of cycles when the actuating means are operated for activating the moisture supplying means, said number of cycles being such that the selected degree of moisture is supplied to the roller by the moisture supplying means; and

second adjustable counting means coacting with said power driven actuating means to operate the same for reducing the rate of moisture supplied to the roller by said moisture supplying means below said predetermined rate for a second predetermined number of cycles as counted by the second counting means, said second coutning means being activated when said blanket cylinder moving means is operated to move the blanket cylinder out of the thrownin position, operation of the blanket cylinder moving means for movement of the blanket cylinder into the throw-in position during said predetermined number of cycles as counted by the second counting means operating said actuating means for restarting the predetermined rate of moisture supplied to said roller by said moisture supplying means.

2. The dampening device according to claim 1 wherein said power driven actuating means comprise movable ductor means for feeding moisture from a supply of moisture to said roller and drive means for driving said ductor means for the purpose aforesaid, said second counting means reducing the speed of said drive means when activated by movement of the blanket cylinder out of the thrown-in position with the plate cylinder and the impression cylinder.

3. The dampening device according to claim 1 and comprising means controlled 'by said second counting means for actuating said roller moving means to move the roller out of engagement with the plate cylinder and deactivating said power driven actuating means when the blanket cylinder is not moved into engagement with the plate cylinder and the impression cylinder during said second predetermined number of cycles counted by the second counting means.

4. The dampening device according to claim 1 wherein said supervising means comprises an indicating means, completion of the counting of said first predetermined number of cycles by the first counting means energizing said indicating means thereby indicating that the selected degree of moisture is present on said roller.

5. The dampening device according to claim 1 wherein said supervising means comprises a switch means for controlling said roller moving means, said switch means being connected in circuit with said first counting means, said first counting means upon counting the first predetermined number of cycles operating said switch means for moving the roller into moisture transmitting engagement with the plate cylinder.

6. The dampening device according to claim 1 wherein said supervising means comprises an indicating means and a switch means for controlling said roller moving means, both said means being connected in circuit with said first counting means, said first count ng means upon counting the first predetermined number of cycles energizing said circuit connected to the indicating means and the switch means to operate the indicating means to indicate the presence of the selected degree of moisture present on said roller and the switch means to actuate the roller moving means for moving said roller into moisture transmitting engagement with the plate cylinder.

References Cited UNITED STATES PATENTS 1,254,338 1/1918 Mascord 101-351 1,612,061 12/1926 Sanker 101-148 2,971,461 2/1961 Bradford et al. 101-350 XR 3,191,528 6/1965 Jorgensen 101-148 3,274,932 9/1966 Caza 101-351 ROBERT E. PULFREY, Primary Examiner C. D. CROWDER, Assistant Examiner U.S. Cl. X.R. 101-351