Display and procedure for placing sheets on a sheet stack

Abstract

Delivery (1) for a sheet-processing machine with a stacking area, wherein blowing means are arranged above a stack of sheets (7) in the stacking area, which support the laying movement of the sheets (2) released by gripper carriage (3), wherein the blowing means are fans of a blowing frame (8), and at least one blowing nozzle arranged above the stacking area between the blowing frame (8) and the stack of sheets (7), wherein a jet of air can be emitted from the nozzle in the direction of the stacking area and wherein the blow nozzle is arranged in a movable manner, characterized by that the blow nozzle is shifted in or against a sheet travel direction (BLR) and / or perpendicular to the sheet travel direction (BLR) when format is set and that the blow nozzle is always directed towards a rear area of ​​the arc (2).

Description

[0001] The invention relates to a delivery for a sheet-processing machine according to the preamble of the first claim and to a method for depositing sheets on a sheet stack in a sheet-processing machine.

[0002] At high machine speeds and / or when processing thin materials, it can happen that the last sheet to be deposited is picked up and carried away by subsequent gripper carriages. This can result in an overshoot that ends up in the delivery area. These sheets must be removed, resulting in downtime. Furthermore, there is a risk that a sheet that is not removed could lead to problems (such as impaired delivery function if, for example, a sheet is positioned above a blower frame, risk of burning sheets in the dryer area, or damage to the sheet guide plate near the sprocket shaft).

[0003] DE 44 34 190 A1 discloses a sheet delivery device on a sheet-processing machine, comprising high-speed fans for a low air volume, which blow a concentrated laminar air jet at high flow velocity, essentially vertically from above, against the incoming sheet. A disadvantage of this solution is that the last sheet to be deposited can lead to malfunctions, such as an overshoot.

[0004] DE 34 13 179 A1 discloses a control and regulation device for a sheet delivery system for sheet-processing machines, particularly for sheet-fed printing presses. Among other things, separate servomotors with feedback of the achieved setting are provided for changing the speed and switching on and off of the fans blowing onto the sheet from above to facilitate the depositing process, or for controlling the pressure of other types of similarly effective, adjustable, and point-acting blowing air sources. The disadvantage of this solution is that continuously operating blowing jets can increase air consumption and also disrupt the depositing process.

[0005] DE 200 19 167 U1 discloses a delivery for a sheet processing machine with a stacking area and at least one blowing nozzle arranged above the stacking area, wherein a blowing jet can be ejected from the blowing nozzle in the direction of the stacking area.

[0006] The invention is therefore based on the object of further improving the stacking process for sheet processing machines.

[0007] According to the invention, this object is achieved by a device having the features of the independent device claim and a method having the features of the independent method claim. Advantageous embodiments emerge from the subclaims, the description, and the drawings.

[0008] The invention has the advantage of further improving the stacking process for sheet-processing machines. In particular, it ensures that the last-sheet blow-out function is independent of the format length.

[0009] Preferably, one embodiment can achieve a reduction in the number of nozzles and / or the air consumption.

[0010] According to one embodiment, blowing devices such as fan, tube and / or blower frames, and in a further development, additional air nozzles such as corner blowers are used above the stack. These blowing devices, possibly in conjunction with the air nozzles for production printing, are sufficient to assist the sheet fall so that the sheets are deposited on the stack quickly enough. However, they are not able to generate the increased forces required for the last sheet in order to prevent this sheet from being dragged along by the vacuum drag of the gripper carriage. Last-sheet blowing presses the last sheet passing through the printing press, for example the last sheet in a feeder stack, the last sheet in a print job, the last sheet after a stopper or the last sheet to be deposited in another way, onto the sheet stack using targeted additional devices or forces, in particular blowing air.

[0011] The last sheet blowing is preferably carried out by several nozzles distributed across the entire maximum stack area and activated only for the last sheet to prevent the last sheet from being dragged along by the aerodynamic forces of the gripper carriages. The last sheet blowing can be carried out independently of the blowing devices or the numerous nozzles above the front stack area. Even with variable sheet lengths, the last sheet blowing nozzles are always positioned exactly opposite the trailing edge of the sheet, ensuring that the trailing edge cannot be dragged along by the gripper carriage(s). Advantageously, a discrete distribution of the nozzles across the stack length is achieved, even with variable stack sizes.

[0012] Particularly preferably, it is ensured that for each format length, at least one blow nozzle, in particular a blow air nozzle, and / or one blow jet, in particular a blow air jet, of the last-sheet blowing device is positioned exactly opposite the area of ​​the trailing edge of the sheet. Tests have shown that it is sufficient to intensively apply air, preferably to blow, only the area of ​​the trailing edge, in particular precisely the trailing edge, of the last sheet. Therefore, the remaining nozzles in the front stacking area can also be omitted.

[0013] In a preferred embodiment, the last sheet blowing is concentrated on the area of ​​the trailing edge of the sheet across the stack, in particular across the entire trailing edge of the last sheet. Preferably, the blowing air nozzles of the last sheet blowing device are connected via at least one connecting element to a format-adjustable element, in particular a sheet brake, in the delivery and can be adjusted to the new format length with the latter. Particularly preferably, the sheet brake and the blowing air nozzles of the last sheet blowing device are adjusted together. This solution takes into account the fact that the trailing edge of the sheet remains the most aerodynamically unstable part during the traversing process by the subsequent gripper carriages.The air nozzles of the last sheet blower, connected to the sheet brake, hold down precisely this trailing edge, ensuring that the entire sheet remains closed above the stack surface and cannot be opened by the gripper carriage. This advantageously allows for safe, fast, and cost-effective adjustment of at least one air nozzle.

[0014] The last sheet blowing can, for example, begin shortly before the last sheet reaches the stack so that sufficient blowing air pressure can build up. For example, the last sheet blowing can begin with the fourth-to-last, third-to-last, or second-to-last sheet so that the last sheet is reliably pressed down onto the stack surface by the applied blowing air. The last sheet blowing can be controlled or regulated via a control device, particularly depending on parameters such as machine speed. Advantageously, both the last sheet and the sheet preceding it receive the precisely measured blowing force. Preferably, the temporarily activated blowing jet is directed regardless of the format and always towards the area of ​​the trailing edge of the sheets to be deposited.

[0015] In a further development, the at least one additional blower nozzle can also be activated during a sample sheet removal in order to secure a sheet located above the sample sheet to be removed and thus prevent it from slipping. For this purpose, the additional blower nozzle or several additional blower nozzles can be controlled, for example, via a control device. Additional elements, such as pivoting leading edge stops and / or retractable separating elements, can be controlled and coordinated via the control device.

[0016] The invention will be explained below by way of example. The accompanying drawings illustrate this schematically: Fig. 1: Delivery with a fan arrangement above a sheet stack and last sheet blowers in standby position; Fig. 2: Display with maximum sheet stack and last sheet blowers activated; Fig. 3: Display with shorter sheet stack and activated last bow blowers.

[0017] The Fig. 1 shows, in the illustrated embodiment, the stacking area of ​​a delivery 1 of a sheet-processing machine, here a sheet-fed printing press, in particular a sheet-fed offset rotary printing press, preferably in a unit and in-line design, in which the freshly printed and / or varnished sheets 2 are deposited. Circulating conveyor systems, for example gripper-carrying gripper carriages 3, are used to transport the sheets 2 from the last processing station of the machine. From these gripper carriages, the sheets 2 are transported, fixed at their leading edges, in the sheet travel direction BLR to the stacking area. A stack support plate 4 is provided in the stacking area. Above the stack support plate 4, the grippers of the gripper carriages 3 open and release the sheets 2, which are braked by a braking device. Suction belts and / or suction rings or suction bars acting on the undersides of the sheets can be used as the braking device, or re-gripper systems can be provided.

[0018] The braked sheets 2 sink under the effect of gravity, for example, onto a pallet 5 arranged on the pile support plate 4. They still have sufficient kinetic energy to rest their leading edges against leading edge stops 6. In this way, a sheet stack 7 is formed on the pallet 5 from the sheets 2 deposited on top of one another with their edges precisely aligned. As a further development, trailing edge and / or side edge stops can be provided, which together form a deposit chute for the falling sheets 2. As the sheet stack 7 on the pallet 5 increases, the pile support plate 4 is lowered by a pile lifting drive (not shown) so that each sheet 2 travels approximately the same falling distance to the pile surface. A sensor that detects the top edge of the sheet stack 7 can be arranged to control the lowering movement of the pile support plate 4.Once the sheet stack 7 has reached its maximum height, the sheet stack 7 is ejected or the stack is changed.

[0019] Blowing means or air generators, in particular a blowing air device, are arranged above the sheet stack 7 in the stacking area, which assist the depositing movement of the sheets 2 released by the gripper carriages 3. The blowing means are arranged here above the sheet stack 7 between the leading and returning runs of the gripper carriages 3. The blowing means preferably have a blowing frame 8, which contains or accommodates fans or groups of fans arranged in the sheet travel direction BLR and / or across the machine width. Shown here, for example, are five fans arranged one behind the other in the sheet travel direction BLR. However, a different number of fans and / or blowing tubes and / or further blowing openings, for example corner blowers, can also be used above the sheet stack 7. The blowing means, for example fans, can also be deactivated individually, particularly for smaller sheet formats.

[0020] For example, the blowing means arranged above the stacking area can be designed as an air generator or fan, for example as an axial fan, in particular as an axial fan, wherein air guiding elements, such as air guiding structures or grid structures, can be assigned to the air generator. An axial fan preferably has a fan wheel rotating about a rotational axis. An air guiding structure or a grid structure can have an extension that directs the air flow in a main flow direction. The main flow direction generated by the air guiding element or by the air guiding structure or grid structure above the sheet stack 7 can be oriented deviating from the vertical. In a further development, the main flow directions generated by the fans or air guiding elements contain a component in the sheet travel direction BLR.The main flow directions of the respective blowing means, in particular fans, generated laterally or at the trailing edge of the sheet can also have a component towards the respective edge.

[0021] Above the stacking area, in addition to the blowing means, here in particular the blowing frame 8, a last-sheet blowing device with at least one blowing nozzle, in particular a blowing air nozzle, is arranged. The blowing nozzle is preferably also arranged between the leading run and the returning run of the circulating gripper carriages 3. This blowing nozzle is particularly preferably arranged below the blowing frame 8 or between the blowing frame 8 and the sheet stack 7. With this additional blowing nozzle, a blowing jet, in particular a blowing air jet, can be ejected in the direction of the stacking area. The ejection of the blowing jet can be initiated or effected in particular by a valve arrangement connected to a control device. The blowing jet can be directed perpendicularly onto the sheet stack 7, in particular perpendicularly onto an area of ​​the trailing edge of the sheet.The blowing nozzle is preferably arranged such that it can be moved and / or offset with a format setting. The blowing nozzle is preferably always moved or offset to the trailing edge of the current sheet format. The last-sheet blowing device preferably has a plurality of blowing air nozzles distributed across the sheet width, which can be moved and / or activated jointly or separately.

[0022] In one embodiment, the last-sheet blower device comprises a plurality of last-sheet blowers 10 arranged one behind the other in the sheet travel direction BLR, which can be jointly adjusted to the area of ​​the trailing edge of the sheet and are preferably jointly assigned to a holder. The holder can be designed, for example, as a connecting plate 12, to which a common or several individual pneumatic connections, in particular one or more blowing air connections, are assigned. The connecting plate 12 is arranged so as to be displaceable in and against the sheet travel direction BLR and can, for example, be guided through an elongated hole in the delivery frame 11. The individual last-sheet blowers 10 are preferably permanently assigned to the connecting plate 12, but can also be designed so as to be adjustable relative to the connecting plate 12.The last sheet blowers 10 can be assigned to the connecting plate 12 such that some or all of the blowing air openings are arranged vertically downwards towards the stacking area.

[0023] The connecting plate 12 is preferably assigned an actuator for displacement so that the last-sheet blowers 10 can be displaced together, particularly during format adjustment, to the area of ​​the trailing edge of the sheet. The connecting plate 12 is preferably connected to another format-adjustable element in the delivery 1 of the sheet-processing machine. Particularly preferably, the connecting plate 12 is mechanically coupled to the format-adjustable sheet brake 9, in particular to a braking station of the sheet brake 9. Provision can be made for laterally arranged blower nozzles to also be axially displaceable in order to displace them axially to the current sheet format during format adjustment, for example, with a braking station of the sheet brake 9. For this purpose, two or more independent connecting plates 12, each coupled, for example, to a braking station, can be provided. Alternatively, blower nozzles located outside the sheet format can be deactivated.

[0024] The at least one additional blowing nozzle of the last-sheet blowing device is preferably pneumatically connected to a compressed air chamber and / or a compressed air line. A fast-acting valve for opening and closing the nozzle opening can be arranged between the compressed air chamber and / or the compressed air line and a nozzle opening of the blowing nozzle. This ensures that the ejected blowing jet is effective quickly and with increased intensity. More preferably, the additional blowing nozzle, here in particular the last-sheet blower 10, is connected to a control device so that it is activated by the control device only, preferably exclusively, during a test sheet removal and / or for the last of a sequence of sheets 2. The control device can be designed separately or integrated into a machine control system. The intensity and / or the blowing time orthe blowing time can be influenced, in particular adjusted or regulated.

[0025] The Fig. 2 shows the delivery 1 with a sheet stack 7 of maximum sheet format and activated last-sheet blowers 10. The last-sheet blowers 10 direct blowing air, in particular blowing air jets, towards the trailing edge of the last sheet 2L to be deposited on the sheet stack 7. A last sheet 2L is a sheet 2 that is transported by a gripper carriage 3, followed by a gripper carriage 3 without a sheet 2 to be deposited. Preferably, the last sheet 2L is a last sheet 2 of a feeder stack, a last sheet 2 of a print job, a last sheet 2 located in the machine after a stopper, or another last sheet 2 that is not immediately followed by another sheet 2. Such a last sheet 2L can be known to the machine control system, for example via a sheet counter, so that information for controlling the last-sheet blowers 10 can be derived. Such information can, for example, be input to the control device orbe supplied to or determined by it.

[0026] The Fig. 3 shows the delivery 1 with a smaller sheet format than the maximum sheet format and activated last-sheet blowers 10. The last-sheet blowers 10 were moved together, here with the braking station of the sheet brake 9, and thus automatically, to the current sheet format. The displacement is carried out by the connecting plate 12 via the drive of the sheet brake 9, in particular the braking station, during format adjustment 13 in the sheet travel direction BLR towards the leading edge stops 6. When adjusting to a larger sheet format, the last-sheet blowers 10 are moved analogously by the connecting plate 12 via the drive of the sheet brake 9, in particular the braking station, during format adjustment 13 accordingly opposite to the sheet travel direction BLR away from the leading edge stops 6.

[0027] How it works: The fans integrated in the blower frame 8 blow the sheets 2 released by the gripper carriages 3 onto the sheet stack 7 during the normal stacking process. The last-sheet blowers 10 are usually deactivated in this case, for example the blower openings are closed by one or more valves. The blower frame 8 can generate a main flow direction directed perpendicularly onto the sheet stack 7. The air exiting the fans is preferably directed in such a way that, at least at the leading edge of the sheet, a speed component directed perpendicularly onto the sheet stack 7 and a speed component oriented in the sheet travel direction BLR is achieved. In a further development, the main flow directions generated laterally and / or upstream can contain a speed component directed towards the respective sheet edge. This ensures that the air applied to a sheet 2 orThe air hitting the sheet stack 7 flows mainly in the sheet travel direction BLR and to the side.

[0028] For the deposit of a last sheet 2L, one or more last-sheet blowers 10 are activated, for example, by the control device so that they direct air jets onto the sheet stack 7. The last-sheet blowers 10 can be activated by the control device shortly before the last sheet 2L reaches the stacking area. For example, the last-sheet blowers 10 can already be activated when the fourth-to-last, third-to-last, or second-to-last sheet 2 has reached the stacking area. This maintains the dead time of the pneumatic system, and the required pressure or intensity or distribution is achieved at the moment when the area of ​​the trailing edge of the last sheet 2L to be blown is located below the last-sheet blowers 10.

[0029] If the last sheet 2L is transported by a gripper carriage 3 to the stacking area in delivery 1, it passes the activated last sheet blowers 10. As soon as the gripper carriage 3 transporting the last sheet 2L has released the last sheet 2L, the last sheet 2L sinks onto the sheet stack 7 under the effect of the blowing air from the blowing devices, for example the fans of the blowing frame 8, possibly with additional blowing frames and / or corner blowers, and the blowing air jets of the last sheet blowers 10. As soon as the last sheet 2L is safely on the sheet stack 7 or is safely in the delivery chute, the blowing devices, for example the fans of the blowing frame 8, can be switched off. The last sheet blowers 10 can also be deactivated. The blowing time of the last bow blowers 10 for depositing the last bow 2L can be up to twenty seconds, for example up to ten seconds, preferably about six seconds.

[0030] The last sheet blowers 10, which are only activated or fully active when a last sheet 2L is being deposited, apply blow air to the area of ​​the trailing edge of the last sheet 2L. This presses the last sheet 2L onto the sheet stack 7 in the area of ​​the trailing edge and securely stabilizes it. The automatic repositioning of the last sheet blowers 10 ensures that they are always preset to the critical trailing edge of a last sheet 2L. The last sheet blower device can also support sample sheet removal. List of reference symbols used 1 display 2 sheets 2L last sheet 3 gripper trolleys 4 stacking support plate 5 pallets 6 Front edge stop 7 stacks of sheets 8 blow frames 9 Bow brake 10 last bow wind instruments 11 Slotted hole in the display frame 12 Connecting plate 13 Format adjustment BLR sheet running direction

Claims

[1] Delivery (1) for a sheet-processing machine with a stacking area, wherein blowing means are arranged above a sheet stack (7) in the stacking area, which assist the depositing movement of the sheets (2) released by gripper carriages (3), wherein the blowing means are fans of a blowing frame (8), and at least one blowing nozzle arranged above the stacking area between the blowing frame (8) and the sheet stack (7), wherein a blowing jet can be ejected from the blowing nozzle in the direction of the stacking area and wherein the blowing nozzle is arranged to be movable, characterized by , that the blowing nozzle is moved in or against a sheet travel direction (BLR) and / or transverse to the sheet travel direction (BLR) when setting the format and that the blowing nozzle is always directed towards a rear area of the sheets (2). [2] Device according to claim 1, characterized bythat the blow nozzle for format adjustment is coupled with another format-adjustable element. [3] Device according to claim 2, characterized by that the further format-adjustable element is designed as a sheet brake (9). [4] Device according to claim 1, 2 or 3, characterized by that the blowing nozzle is connected to a control device, wherein the blowing nozzle is activated by the control device only for a last sheet (2L) of a sequence of sheets (2) and / or during a test sheet removal. [5] Device according to claim 1, 2, 3 or 4, characterized by that the blowing nozzle has a valve arrangement for activating and / or deactivating the blowing jet. [6] Method for depositing sheets (2) on a sheet stack (7) in a sheet-processing machine with at least one blowing nozzle arranged above the sheet stack (7), whereby a blow jet is occasionally ejected from the blow nozzle in the direction of the stacking area, characterized by , that the blowing jet is directed towards the area of the trailing edge of the sheets (2) to be deposited in the stacking area and that the blowing jet is only activated for a last sheet (2L) to be placed on the sheet stack (7) and / or when a test sheet is removed. [7] Method according to claim 6, characterized by that the blowing nozzle is moved to the area of the trailing edge of the sheets (2) in the stacking area when the format is set. [8] Method according to claim 6 or 7, characterized by that the blowing nozzle is moved together with an element to be adjusted in size. [9] Method according to claim 8, characterized by that the blowing nozzle is moved together with a sheet brake (9).

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