Delivery of a sheet-fed rotary printing press

Abstract

Delivery of a sheet-fed rotary printing press with a sheet-transporting sheet conveyor system which transports the sheets (2) to a delivery pile (6), wherein the sheet conveyor system is designed as a chain conveyor system with two delivery chains each guided laterally on the frame, between which gripper carriages (1) are arranged, and with a sheet brake with circumferentially guided brake bands (5), wherein each brake band (5) is guided by deflection rollers, wherein the deflection roller facing the delivery pile (6) is displaceable and the further deflection roller spanning a brake strand is arranged in a fixed position or both deflection rollers spanning a brake strand of a brake band (5) are displaceable, wherein the brake bands (5) are assigned suction means in some areas to form suction areas on the side of the brake bands (5) facing away from the suction means, wherein the suction means are movable intermittently by a drive in and against the sheet travel direction (BLR),wherein the suction means of at least one brake band (5) is movable back and forth between a position in which the suction area formed on the brake band (5) extends at least partially into the layout of the delivery stack (6) and a position in which the suction area does not extend into the layout of the delivery stack (6), wherein the suction means of the brake band (5) is movable in the sheet travel direction (BLR) during the sheet contact and counter to the sheet travel direction (BLR) between the sheet contacts, and wherein the suction means is formed by a suction plate between the deflection rollers spanning a brake strand and / or a deflection roller designed as a suction ring.

Description

[0001] The invention relates to a delivery of a sheet-fed rotary printing press with a sheet-transporting sheet conveyor system and with a sheet brake with circumferentially guided brake bands.

[0002] In the deliveries of sheet-fed rotary printing presses, the sheets are guided by their leading edge by gripper carriages from the last printing cylinder over various sheet guide plates that ensure the required sheet guidance quality, all the way to the stack. There, the opening gripper releases the leading edge, allowing the pneumatic sheet brake on the underside of the sheet to initiate sheet deceleration. Once the deceleration is complete, the sheet moves at a residual speed until it reaches the stack outline. Problems arise from the contact between the sheet being deposited and the following sheet on the sheet brake.Since the braking must be completed within the area of ​​the suction plate before the deflection roller, i.e. where a braking force is still present, there is a considerable remaining distance to the pile footprint, which, divided by the residual speed, leads to a considerable remaining time, so that the sheet brake is still covered by the sheet to be deposited when the following sheet is already overlapping and has to be sucked in.

[0003] DE 36 34 400 A1 discloses a sheet delivery device for rotary printing presses. This device features sheet brakes with drive and deflection rollers over which conveyor belts are guided. The drive and deflection rollers are mounted on the journals of crank arms, which are driven in synchronization with the sheet sequence in such a way that the trailing sheet end is sucked in when the crank is in the upper position, and after a partial rotation of the crank arms, the sheet is slowed down and lowered onto the stack of the sheet delivery device. The disadvantage of this solution is that the sheets cannot be fully decelerated, and the release of the trailing edges of the sheets must occur well before the stack.

[0004] DE 103 92 231 T5 shows a method and a device for laying veneer.

[0005] DE 42 39 561 C2 shows a chain conveyor of a sheet-fed printing press.

[0006] DE 102 24 299 A1 shows a delivery of a machine processing flat printing materials, wherein sheet brakes are arranged in such a way that a take-over level and a delivery level can be changed.

[0007] DE 10 2006 035 559 A1 shows a sheet brake system for braking printed sheets, wherein a roller axis is arranged eccentrically offset relative to one or each rotation axis of each brake element.

[0008] The invention is therefore based on the object of creating an improved sheet brake for depositing sheets on a delivery stack.

[0009] According to the invention, the object is achieved by a device having the features of the first claim.

[0010] The invention largely eliminates the overlap of the sheet being deposited with the following sheet, with its damaging contact effects. The cyclical restriction, especially for the suction process, is largely eliminated. The following sheet can be sucked in in a timely manner. Advantageously, the delayed sheet is almost completely within the stack footprint at the moment the braking action ends. This ensures that, on the one hand, the sheets are sufficiently braked and deposited, and, on the other hand, the following sheets are sucked in in a timely manner.

[0011] The invention will be explained below by way of example. The accompanying drawings illustrate this schematically: Fig. 1: Side view of the delivery of a sheet-fed rotary printing press with a sheet brake arranged in front of the delivery stack; Fig. 2: Delivery with a sheet brake arranged in front of the delivery stack, which contains pre-suction rings that can be raised intermittently; Fig. 3: Boom with sheet brake pivoting around a drive roller.

[0012] The Fig. 1 shows, in a preferred embodiment of the invention, a delivery of a sheet-processing machine, in this case a sheet-fed rotary printing press operating according to the offset process. The delivery comprises a sheet conveyor system which transports the sheets 2 that have been printed, varnished, processed, etc., in the printing press to a delivery stack 6. This sheet conveyor system is designed as a chain conveyor system with two delivery chains, each guided laterally on the frame, between which gripper carriages 1 are arranged. The gripper carriages 1 contain sheet fixing systems with which the sheets 2 to be transported are gripped at the leading edge. The delivery chains guide the gripper carriages 1 on a gripper carriage track 1.1 in the sheet travel direction BLR up to above the delivery stack 6, where the gripper carriages 1 release the sheets 2 for deposit.Sheet guide plates 3 are preferably arranged on the sheet conveyor path to guide the sheets 2 on their way to the delivery pile 6. An air cushion can be formed between the sheet guide plate 3 and the sheets 2. A sheet brake is arranged in front of the delivery pile 6. This brake takes the sheets 2 to be deposited from the gripper carriages 1 and slows them down from press speed to delivery speed. After this deceleration by the sheet brake, the sheets 2 are aligned at leading edge stops 6.1 and neatly deposited on the delivery pile 6. The printing press can be switched between straight printing and perfecting printing modes.

[0013] The sheet brake arranged upstream of the delivery pile 6 in the sheet travel direction BLR contains at least two braking stations, which are placed on the lateral edge of the sheets 2 or on pressure-free corridors. Preferably, however, several braking stations are arranged across the sheet width, preferably placed parallel to the sheet travel direction BLR on narrow, pressure-free corridors. Each braking station contains a braking band 5 running over at least two deflection rollers and interacting with a suction means, which forms a braking strand between the deflection rollers. The suction means is preferably designed as a suction plate arranged between the deflection rollers, which is connected to an adjustable suction air connection. The suction means forms a suction area on the upper side of the braking band 5. The braking band 5 is driven by a braking drive 5.1 such that the braking strand always moves in the sheet travel direction BLR. The braking force connected to the braking drive 5.The deflection roller cooperating with the first pulley is designed as a drive roller, which is preferably arranged in a fixed position. A band or belt with openings can be used as the brake band 5. However, it could also have two seals forming a suction channel, which could, for example, be designed as two narrow round cords. In the . Fig. 1, the brake bands 5 are shown interacting with four pulleys.

[0014] The brake bands 5 are driven dynamically and periodically between the machine speed and the depositing speed. The depositing speed is preferably selected to be close to zero. In this preferred dynamic operation, the brake drive 5.1 of the brake bands 5 is synchronized with the machine cycle. This is achieved by a control unit (not shown). In alternative embodiments, a constant speed below the machine speed can also be selected for the brake bands 5. In further embodiments, the brake bands 5 can assume a slight inclination with respect to the sheet travel direction BLR in order to create transverse sheet tightening. This inclination can be adjustable so that it is only used when necessary. The inclination of the brake bands 5 can also be periodically coordinated with the sheet sequence.Furthermore, the brake bands 5 can be designed to be adjustable in inclination by cyclically lowering the deflection rollers adjacent to the boom stack 6.

[0015] The sheet brake contains a further drive (not shown) with which the deflection roller of a brake band 5, which is assigned adjacent to the delivery stack 6, can be displaced in and against the sheet travel direction BLR. The displacement of a deflection roller takes place by displacing its axis of rotation. When the deflection roller is displaced, the suction plate is also displaced. Preferably, at least one further deflection roller is provided, which is also designed to be displaceable and serves as a band storage device. This further deflection roller is displaced in such a way that the brake band tension is kept constant when the brake strand is extended. Alternatively, the band storage device can also be designed differently, for example as a spring element. The deflection rollers facing the delivery stack 6 can also be designed as suction rings and thus, as suction means, extend the suction area of ​​the suction plate in the sheet travel direction BLR.

[0016] The relocation of the two in the Fig. 1 is approximately parallel to the surface of the delivery pile 6 and thus preferably in a horizontal direction. This simultaneous parallel horizontal displacement of the two deflection rollers results in a horizontal return of the braking band 5 and thus a low drop height of the sheets 2, which is thus only determined by the diameter of the deflection roller displaced over the delivery pile 6. The displacement of the deflection rollers can be achieved by one or by separate drives. The drive(s) are synchronized with the machine control system so that the displacement of the deflection rollers occurs in time with the sheet sequence. The drives can also be controlled or regulated according to sensor values. Other devices determining the sheet delivery can be monitored by sensors and adjusted as required.For example, a position sensor can be used to detect the trailing edge of the sheet on the sheet brake, which, depending on the position of the trailing edge, controls or regulates the gripper opening point of the gripper carriage 1 at a predetermined time. The displacement path and the speed of the displacement of the deflection rollers can be adjustable. In embodiments not shown, both deflection rollers spanning a braking strand can also be designed to be displaceable in and against the sheet travel direction BLR. The braking distance, which is primarily determined by the suction plate, can also be extended in the sheet travel direction BLR by a suction air duct extended into the deflection roller. Alternatively, the belt can also be guided around other deflection elements, for example in a sliding manner.

[0017] The Fig. 2 shows, in a preferred development of the invention, a delivery with a sheet brake that includes pre-suction rings 4. These pre-suction rings 4, which act as a pneumatic catcher arrangement, are arranged upstream of the brake bands 5 in the sheet travel direction BLR and are arranged diverging with respect to the sheet travel direction BLR for transverse sheet tensioning. In a preferred embodiment, the outward inclination of the pre-suction rings 4 is more than 10°, whereby this angle can be adjusted according to requirements. The pre-suction rings 4, like the brake bands 5, are placed on pressure-free corridors and are constantly driven in rotation by a rotary drive 4.1 at at least approximately the machine speed. The rotation speed of the pre-suction rings 4 is preferably between 95% and 100% the machine speed. If the rotary drive 4.1 is to be omitted, the pre-suction rings 4 can alternatively be driven by the sheet contact.In addition, this further development provides for the pre-suction rings 4 to be designed so that they can be raised intermittently by a separate lifting drive 4.2. The lifting drive 4.2 allows the pre-suction rings 4 to be moved at least between a sheet take-over position and a sheet transfer position. In the sheet take-over position, the distance between the pre-suction rings 4 and the gripper carriage track 1.1 of the gripper carriage 1 is minimized so that the pre-suction rings 4 come into contact with the sheets 2 transported by the gripper carriage 1. The suction air from the pre-suction rings 4 ensures secure contact between the sheets 2. Due to the subsequent lowering movement of the pre-suction rings 4, the sheet 2 is taken downwards so that the sheet 2 is applied safely and quickly to the brake bands 5.

[0018] The Fig.3 shows a further embodiment of the invention, a sheet brake which is pivotally mounted about a rotational axis for displacing the suction means between a position in front of the delivery stack 6 and a position in plan view above the delivery stack 6. This rotational axis, about which the sheet brake is pivotable, is spaced from the deflection rollers of the brake belt 5 spanning a braking strand. Preferably, the sheet brake is pivoted back and forth about the rotational axis of one of the drive rollers. This drive roller is thus fixedly mounted. During the pivoting movement of the sheet brake, the suction means is pivoted at least partially into the plan view of the delivery stack 6. Alternatively, the pivoting movement could occur about a different drive roller or any desired rotational axis.

[0019] How it works: The underside of the sheets 2 transported by the gripper carriages 1 over the delivery pile 6 rests on the brake bands 5 of the sheet brake, which are driven by the brake drive 5.1 at at least approximately machine speed. If upstream suction rings 4 are present, the sheets 2 are first caught, stretched laterally and / or braked before the sheets 2 come into contact with the brake bands 5. The negative pressure applied to the suction plates of the braking stations causes the sheets 2 to be sucked onto the brake strand of the brake bands 5. The deflection rollers facing the delivery pile 6 and the suction plates of the brake bands 5 are moved along with the sheet 2 in the sheet travel direction BLR shortly before or during the subsequent deceleration process. The displacement of the suction means can take place evenly in the sheet travel direction BLR or according to a desired characteristic curve.It may also be provided that the deflection rollers and the suction plates are only moved with the rear end of the sheet 2 into the floor plan above the delivery stack 6.

[0020] Preferably, the braking section formed by the suction means and the braking belt 5 is moved predominantly horizontally into the pile footprint before the gripper opening of the gripper carriage 1, so that the sheet 2 is almost completely within the pile footprint at the moment the braking process ends. The suction element, which is guided over the pile footprint, decelerates each sheet 2 almost to a standstill. The deflection roller with suction plate is then moved back to its starting position at a significantly higher speed than the residual speed of the sheets 2. After the deflection roller has been moved back to its starting position against the sheet travel direction BLR, the sheet 2 can sink down onto the delivery pile 6. The movable deflection rollers are preferably designed to be low-mass.

[0021] A braking section is created that is designed so that, on the one hand, the sheets 2 are sufficiently braked and deposited, and, on the other hand, the subsequent sheets can be sucked in in a timely manner. The device according to the invention largely eliminates the residual time required for the sheets 2 to be deposited after the braking process has ended. List of reference symbols used 1 gripper trolley 1.1 Gripper carriage track 2 sheets 3 sheet guide plate 4 pre-suction rings 4.1 Rotation drive 4.2 Lifting drive 5 brake band 5.1 Brake drive 6 boom stacks 6.1 Leading edge stops BLR sheet running direction

Claims

[1] Delivery of a sheet-fed rotary printing press with a sheet conveyor system transporting sheets (2) which transports the sheets (2) to a delivery pile (6), wherein the sheet conveyor system is designed as a chain conveyor system with two delivery chains each guided laterally on the frame, between which gripper carriages (1) are arranged, and with a sheet brake with circumferentially guided brake bands (5), wherein each brake band (5) is guided by deflection rollers, wherein the deflection roller facing the delivery pile (6) is displaceable and the further deflection roller spanning a brake strand is arranged in a fixed position or both deflection rollers spanning a brake strand of a brake band (5) are displaceable, wherein the brake bands (5) are assigned suction means in some areas to form suction areas on the side of the brake bands (5) facing away from the suction means, wherein the suction means are movable in cycles in and against the sheet travel direction (BLR) by a drive,wherein the suction means of at least one brake band (5) is movable back and forth between a position in which the suction area formed on the brake band (5) extends at least partially into the layout of the delivery stack (6) and a position in which the suction area does not extend into the layout of the delivery stack (6), wherein the suction means of the brake band (5) is movable in the sheet travel direction (BLR) during the sheet contact and counter to the sheet travel direction (BLR) between the sheet contacts, and wherein the suction means is formed by a suction plate between the deflection rollers spanning a brake strand and / or a deflection roller designed as a suction ring. [2] Boom according to claim 1, characterized by that the displacement of the deflection rollers takes place at least approximately parallel to the surface of the delivery stack (6). [3] Boom according to claim 1, characterized bythat a band storage device is provided when a deflection roller of a brake band (5) is displaced. [4] Boom according to one of the preceding claims, characterized by that the brake bands (5) can be driven discontinuously by a brake drive (5.1). [5] Boom according to one of the preceding claims, characterized by that the brake bands (5) are arranged so that their inclination can be adjusted to the direction of sheet travel (BLR). [6] Boom according to one of the preceding claims, characterized by that the brake bands (5) are arranged so that their inclination can be adjusted to the horizontal. [7] Boom according to claim 1 or 6, characterized by that the displacement of the suction means of a brake band (5) takes place by a pivoting movement about a rotation axis spaced from the rotation axes of the deflection rollers. [8] Boom according to claim 1 or 7, characterized bythat the displacement of the suction means of a brake band (5) is effected by a pivoting movement around the rotation axis of a drive roller. [9] Boom according to one of the preceding claims, characterized by that a pneumatic catcher arrangement (4) is arranged upstream of the brake bands (5) in the sheet travel direction (BLR).

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