DE2756507A1 - METHOD AND DEVICE FOR TURNING A SHEET IN A SHEET PRINTING MACHINE, BOOKBINDING MACHINE OR THE LIKE. - Google Patents

Description

DR.-ING. EUGEN MAIER DR.-ING. ECKHARD WOLF PATENT LAWYERS

DRCSPNEP * BANK AO TELEPHONE: (0711) 34 3781/3 STUTTGART NtJ. 1930934

TELEORAMME: mentor 7 STUTTGART 1, PISCHEKSTR. 19 postal check stqt. ssaoo-7oe

A 12 139 f - kt December 16, 1977

SOLNA OFFSET AB

Knistavägen 21

S-I91 47 Sollentuna / Sweden

Method and device for turning a sheet in a sheet-fed printing machine, Book binding machine or the like.

In offset printing, the printing form consists of a thin plate, the surface of which is chemically prepared so that it is water-accepting at the non-printing areas and printing-ink-accepting at the printing areas. the Plate is attached to a plate cylinder, which is constantly filled with ink and during the printing process Fountain solution is applied. The print image is transferred from the printing plate to a blanket cylinder, which in turn transfers the print image to the paper.

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The printing paper is transported from the paper stack into the printing unit and is there by the printing cylinder detected, which presses it against the blanket cylinder when it unrolls. The use of pressure cylinders is above all Common for sheet-fed offset presses. Instead of one-sided printing, there is also a double-sided printing with two opposing forces Blanket cylinders possible. This process is mainly used in web offset machines, but can also be used with sheet-fed presses.

There are basically two different types of machine construction for multi-color printing, the so-called series construction and the construction with a common pressure cylinder.

In the case of series construction, the individual printing units, which are intended for printing one color each, are arranged one behind the other. The sheet is first removed individually from a stack of paper by means of a suction head taken by blowing air under the overhead arch, and then on a conveyor belt to the To be transported to the feed table, on which he can rest at the front lay and from a laterally acting pull lay is trimmed. The sheet is then adjusted to the speed of the impression cylinder accelerated and pulled into the printing unit by its grippers. From the impression cylinder, the sheet is sent to a

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Intermediate drum is passed and is momentarily held both by the grippers of the printing cylinder and by the grippers of the intermediate drum. Ever Depending on the design of the machine, one or three intermediate drums are arranged between each printing unit. Particularly in machines with several intermediate drums between the printing units occur during the passage of the Sheet of paper a larger number of gripper changes.

During a gripper change, the grippers of one cylinder press the sheet against their abutment, while the grippers of the other cylinder grasp the sheet between the first two grippers and against theirs Press abutment. The gripper mechanism is controlled by an exact cam control designed with low tolerances actuated. Usually, the sheet of paper is moved over a distance of about 3 mm from both Gripper sets held.

In the case of multi-color printing with a common printing cylinder for two printing units, the Sheets to and from the relevant printing units in the same way as with the serial printing machines with the only one Difference, that the sheet for printing with the first and the second color against and the same impression cylinder

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is held. The sheet transfer from the second to the the third and from the fourth to the fifth color is carried out by means of a gripper carriage driven by chains.

By reducing the number of gripper changes, there is a risk of deformation of the paper during the gripper change prevented; on the other hand, problems arise in the preparation of the gripper carriage, which the sheet of transports one printing unit to the other.

All of these difficulties do not arise with web offset machines; on the other hand, there are problems with keeping the paper tension constant in the paper web, as when printing with several consecutive colors high demands are placed on the uniformity of the web tension.

After the printing process, the sheets or web are taken out of the printing machine for drying and post-processing.

It is often desirable to turn the sheet over while it is being transported, e.g. for front and back printing (two-sided Printing) in a two-color printing machine. When printing on the reverse side, the sheet is prepared on the Trailing edge, so that certain inaccuracies result, but which do not interfere with normal black and white printing.

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The invention has for its object to develop a method for turning a printed sheet, which in a Printing machine or bookbinding machine with several printing units or printing units connected to one another via intermediate drums. Processing stations can be used. Another object is to provide a device for carrying out to create this procedure.

The method steps specified in claim 1 and those specified in claim 5 are used to achieve this object Precautions suggested.

Further advantageous refinements and developments of the method according to the invention and the method according to the invention Device emerge from the subclaims.

The invention is explained in more detail below with reference to the drawing. Show it

1 is a schematic side view of a four-color sheet-fed offset printing machine;

FIG. 2 shows a detail from FIG. 1 in a perspective representation to illustrate a gripper change; FIG.

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3a to f show a schematic side view of a

Sheet turner in different working conditions;

4 shows an intermediate drum with pivotable drum segments in a perspective illustration.

The sheet-fed offset press shown in Fig. 1 includes four printing unit units 1, 2, 3, 4 arranged one behind the other. The paper sheet 6 arrives from the stack 5 via the feed table to the first printing unit 1, where it is printed between the impression cylinder 8 and the blanket cylinder 9. Of the Plate cylinder 10 is acted upon by an inking unit 10a with ink and by a dampening unit 10b with water.

After printing with the first color, the paper sheet is fed via the intermediate drums 11, 12 and 13 to the next printing unit 2 and is there printed with the second color between the printing cylinder 18 and the blanket cylinder 19. The printed sheet then reaches the printing unit 3, etc. via the intermediate drums 21, 22 and 23, etc. After passing through the last printing unit 4, the printed sheets are deposited on the stack 14.

In Fig. 2 is a schematic of the transfer of a printed sheet from one drum to another, for example from the Intermediate drum 13 for printing cylinder 18 is shown. Of the

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Sheet is held by the grippers 15 of the intermediate drum 13 and into the grippers 16 of the printing cylinder moved in. Over a very short distance of about 3 mm, the sheet is simultaneously picked up by both sets of grippers 15 and 16 recorded. Then the grippers 15 are opened so that the sheet of the grippers 16 of the printing cylinder 18 can be taken.

The grippers are operated via a mechanical cam control, not shown, which work very precisely and must be synchronized with the cylinder movement.

If the print sheet is to be turned, between two intermediate drums a sheet turner arranged. In the case of the exemplary embodiment shown in FIGS. 3a to 3f the turning of the sheet takes place between the second intermediate drum 22 and the third intermediate drum 23, which are located in turn located between the two printing units 2 and. With such an arrangement there is a 2 + 2 color print possible in a four-color printing machine.

A printed sheet 6 located on the first intermediate drum 21 is held by the grippers 24 of the second intermediate drum detected and brought into the position shown in Fig. 3a by the rotating drum. In this position

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the pivot arm 25 connected to the axle shaft 26 in the direction of arrow 27 and comes into engagement with the Trailing edge of the sheet 6, the movable part 28 of the gripper being opposite the stationary part 29 takes off. The speed of the swivel arm is initially greater than the peripheral speed of the intermediate drum and is then reduced to the speed of the sheet when it is gripped by the gripper. The gripper opening 28,29 closes at the same time or a few millimeters before when the opening of the gripper 24 on the intermediate drum 22 takes place (Fig. 3b). In Fig. 3c the operating state is shown in which the now open Gripper 24 of the intermediate drum 22 from the gripper 25, which has now reached its bottom dead center only The held sheet 6 is moved forward and the next sheet 6a held by the gripper 24a is transported downwards will.

At the bottom dead center, the swivel gripper 25 reverses its direction of movement around and swings upwards with increasing speed, as shown in Fig. 3d. The grapple the intermediate drum 23 are open and ready to take over the sheet from the swivel gripper 25.

Between the drums 22, 23 and the swivel gripper 25,

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there is a bow guide 41 corresponding to the German one Patent application P 27 54 082.5 (Swedish patent application 7613743-9), which is temporarily or continuously acted upon with compressed air. This device guides the bow in a certain Trajectory and prevents it from fluttering and possibly smearing.

The grippers 24 on the intermediate drum 22 are in turn ready again to take over a new sheet from the intermediate drum.

In Fig. 3e the state is shown in which the sheet from both the swivel gripper 25 and the gripper 40 is held after the speed of the swivel gripper 25 and thus the sheet on the peripheral speed of the cylinder 23 has been reduced. The guide device 41 continues to ensure that the bow on the prescribed Railway is guided. The swivel gripper sets its movement up to the upper one while transferring the sheet Dead center (Fig. 3f) continues while the gripper 28 opens and its speed gradually decreases to zero. Then the direction of movement of the swivel gripper conversely, the movable gripper part 28 is closed and the speed gradually increases on the way back.

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The cycle thus begins anew, in that the swivel gripper 25 rests on the intermediate drum 22 while adapting

themselves

moved to the speed and / the movable gripper part 28 opens to take over a new sheet 6 from the intermediate drum 22, as shown in Fig. 3a.

When the swivel gripper is moved back and forth, there is a risk that the gripper will touch the intermediate drum from which it is removing the sheet and thereby be damaged. With the present proposal, this is avoided in that the radius of the intermediate drum 22 is reduced over a certain time segment of the movement sequence in order to maintain a sufficient distance from the swivel gripper. A corresponding result is obtained in that the axle shaft of the swivel gripper performs an eccentric movement which is synchronized with the rotational movement of the relevant intermediate cylinder. In this case, the axle shaft of the swinging gripper leads during the passage swing of the gripper on the respective intermediate drum, an eccentric movement, and when it has two claws, three times when it has namely twice per revolution of the Zwisehentrorarae1 three grippers, etc.

In order to transfer a sheet from the grippers of one drum to the grippers of the next drum without collision

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To be able to lead, the grippers are arranged recessed in open-edged recesses 17. The movement of the Intermediate drums take place synchronously with each other. This construction has been used for the usual bow handover without Turning well proven.

When gripping the rear edge of the sheet 6 located on the intermediate drum 22, the swivel gripper 25 performs a reciprocating motion. Since the printed sheets can be of different lengths, the aforementioned gripper recess are not provided in the relevant intermediate drum when the sheet turner is present.

In order nevertheless to enable the swivel gripper to swing past the intermediate drum 22 with the gripper part 28 open can to get to the trailing edge of the sheet, the drum consists of different segments, at least one of which is movable and is provided with the grippers, while the other segments are fixed and define a constant drum radius that corresponds to the radius of the two other intermediate drums 21 and 23 match.

The grippers 24 and 24 a of the intermediate drum 22 each consist of a movable gripper part 50, which against a stationary gripper part 51 acts. The movable one

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Gripper part is pivotably mounted on the axle shaft 52, which in turn is in the recess 55 of the drum arranged axle shaft 54 is pivotable. In their outwardly pivoted position, the movable segments point the same radius as the fixed segments, so that the intermediate drum 22 when the pivot mechanism is switched off can be used for normal sheet transport without turning. In the perspective shown in FIG The illustration of the intermediate drum 22 is the drum segment 53 with the grippers 54 open in the recess 55 withdrawn. This corresponds to a situation in which a sheet has just been transferred to the swivel gripper.

Further difficulties can arise when turning the sheet that there are also collisions between the Grippers 24 of the intermediate drum 22 and the grippers of Drum 23 can come. The movement of the swivel gripper is synchronized with the rotation of the drum 22, so that corresponding motion cycles run. Because of the variable length of the sheet 6, however, the motion cycles must be mutually displaceable, so that the achievement of the bottom dead center of the swivel gripper coincides with the passage of the trailing edge of the sheet. Correspondingly, the movement sequence of the drum must also be coordinated with the movement cycle of the swivel gripper

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be, so that the drum gripper in question and the swivel gripper are in the area of the top dead center Hit swivel gripper. This means that the movement cycles of the drums 2, 2 and 23 depending on the Arc length are shifted considerably against each other, so that the Qäfahr an unauthorized contact between Consists of grippers and sheets.

This difficulty does not occur with normal sheet transport, only when turning the sheet. In the normal sheet transfer is only gripped by the grippers the leading edge of the sheet, so that the length of the The arc and the position of the trailing edge do not play a role in the sequence of movements. If the segment 53 is in position A the gripper in question is withdrawn into the recess and moved outwards again in position B. a contact between the grippers of the drum 22 and the surface of the drum 23 avoided, as well as a Contact between the grippers of the drum 23 and the segment 53 of the drum 22 is avoided.

By using the swivel gripper described in a two-color printing machine, in addition to the one-sided Two-color printing two sides of a sheet can be printed with one color in a four-color printing machine the two sides of the sheet are printed with 2 + 2, 2 + 1 or 3 + 1 colors, etc.

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When using the sheet turner, the drive of the The swivel gripper is coupled to the synchronized intermediate drums via a common gear unit. Usually becomes a mechanical cam mechanism to control the speed, direction of movement as well as opening and Closing of the gripper members used. Such mechanical Controls are known in printing technology and therefore do not need to be described in more detail. This relatively simply constructed mechanical controls can be produced with very high accuracy; to a simple this engagement or non-engagement of the swivel gripper To enable, the gear can be fixed in the printing machine, so that only the swivel gripper itself must be removed if the sheets are not to be turned.

In addition to the mechanical, electronic or hydraulic control of the swivel gripper is also possible, and Tests with pneumatic controls have also shown good results.

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Claims (9)

A 12 139 f - kt 12/16/1977 claims 1.J method for turning a sheet in a sheet-fed printing press, Book binding machine or the like., Characterized in that the on a first rotating intermediate drum located sheet of a Pivot gripper detected at its rear edge and with this edge as a front edge to a second rotating Intermediate drum is passed. 2. The method according to claim 1, characterized that the sheet grasped by the swivel gripper at the peripheral speed of the intermediate drum decelerated to zero speed, its direction of movement reversed, to the peripheral speed of the second The intermediate drum is accelerated, inserted into the gripper there and released by the opening swivel gripper is that then the again closing swivel gripper braked to a standstill and after Reversal of its direction of movement to the peripheral speed of the first intermediate drum and accelerated before Capturing the trailing edge of the next sheet is reopened. 809825/0969 ORIGINAL INSPECTED A 12 139 f - kt - 2 - December 16, 1977 3. The method according to claim 2, characterized in that the radius of the first intermediate drum during the swinging past of the swivel gripper and while the rotating past the second intermediate drum located gripper is reduced. 4. The method according to any one of claims 1 to 3, characterized characterized in that the movement of the swivel gripper mechanically by means of a cam control, controlled electronically or hydraulically. 5. Device for turning a sheet in a sheet-fed printing machine, Book binding machine or the like. with two rotating intermediate drums equipped with grippers for transport of the sheet between two printing or processing stations, characterized in that im Area between the two intermediate drums (22,23) a swivel gripper (25) is arranged and controlled so that it detects the trailing edge of a sheet (6) held by the grippers (24) of the first intermediate drum (22), of which Reverses the direction of movement and feeds it to the grippers (40) of the second intermediate drum (23). 6. Apparatus according to claim 5, characterized in that the gripper (24) of the first 809825/0969 A 12 139 f - kt - 3 - December 16, 1977 Intermediate drum on one, pivotable or radially displaceable Drum segment (53) are arranged, which out of the path of movement of the swivel gripper (25) is retractable into the drum (22). 7. Apparatus according to claim 6, characterized in that the drum segment (53) in one Open-edged recess (55) of the drum (22) is arranged. 8. Device according to one of claims 5 to 7, characterized in that the swivel gripper (25) can be controlled by means of a mechanical, electronic or hydraulic control device. 9. Device according to one of claims 5 to 8, g e τ characterized by a tronune in the area between the intermediate (22,23) and the swivel gripper (25) arranged device (41) for guiding the sheet. 809825/0969