DEVICE FOR FEEDING SHEETS

Abstract

A device is provided for feeding sheets to a sheet-processing machine having at least one processing mechanism. A feeder head is provided for cyclically separating the sheets from a pile of such sheets and has transporting suckers for transporting the sheets to a belt table. The belt table has at least one revolving transport belt which is guided over at least two feed rollers. A first drive is assigned to at least one feed roller and a sheet flap, which is connected to a pivotally mounted shaft, is provided between the transporting suckers and the at least one transport belt. A second drive is assigned to the shaft, for pivoting that shaft. A sheet arrival sensor, which is arranged between the belt table and the processing mechanism, generates first signals representing the arrival of the sheets for a sequence of sheets. A clock generator generates second signals representing the angular position of the at least one processing mechanism, and has a controller, which controls the first drive as a function of the second signals and which controls the second drive as a function of the first and second signals.

Claims

1-10 (canceled)

11. A device for feeding sheets to a sheet-processing machine comprising at least one processing mechanism, comprising a feeder head (7) for cyclically separating the sheets from a pile and comprising transporting suckers for transporting the sheets to a belt table (2), the belt table (2) comprising at least one revolving transport belt (14), which is guided over at least two feed rollers (12.1, 12.2, 12.3, 12.4, 12.5), a first drive (25) being assigned to at least one feed roller (12.1, 12.2, 12.3, 12.4, 12.5), and a sheet flap, which is connected to a pivotably mounted shaft, being provided between the transporting suckers and the at least one transport belt (14), a second drive (24) being assigned to the shaft pivoting the same, comprising a sheet arrival sensor, which is arranged between the belt table (2) and the processing mechanism and generates first signals representing the arrival of the sheets for a sequence of sheets, comprising a clock generator, which generates second signals representing the angular position of the at least one processing mechanism, and comprising a controller, which controls the first drive (25) as a function of the second signals, and which controls the second drive (24) as a function of the first and second signals, characterized in that respective clock-based speed profiles are entered into the controller for controlling the first and second drives.

12. The device for feeding sheets according to claim 11, wherein the speed profiles have a discontinuous speed curve.

13. The device for feeding sheets according to claim 12, wherein the controller is designed to ascertain the phase positions of the first signals in relation to the phase positions of the second signals.

14. The device for feeding sheets according to claim 13, wherein the controller is designed to control the second drive (24) as a function of the phase positions of the first signals in relation to the phase positions of the second signals.

15. The device for feeding sheets according to claim 11, wherein the controller is designed to control the second drive (24) in such a way that, as a function of the phase positions of the first signals in relation to the phase positions of the second signals, the phase positions of the speed profile of the second drive (24) are shifted in a leading or trailing manner with respect to the phase positions of the speed profile of the first drive (25), or that the second drive (24) is driven using a speed profile that has an increased or a decreased average speed.

16. The device for feeding sheets according to claim 11, wherein a pivotably mounted timing roller shaft carrying timing rollers is provided, and the second drive (24) is designed to drive the timing roller shaft and the shaft connected to the sheet flap.

17. The device for feeding sheets according to claim 11, wherein a fifth drive (23) is assigned to the feeder head (7) and/or the transporting suckers, and the controller controls the fifth drive (23) as a function of the first and second signals.

18. The device for feeding sheets according to claim 17, wherein the controller controls the first drive (25) exclusively as a function of the second signals.

19. The device for feeding sheets according to claim 11, wherein the processing mechanism is an offset printing mechanism, a finish coating mechanism, an inkjet printing mechanism or a die-cutting mechanism.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Exemplary embodiments of the invention are illustrated in the set of drawings and will be described in greater detail below.

[0016] The drawings show:

[0017] FIG. 1 a device for feeding sheets, comprising a suction belt table;

[0018] FIG. 2 a detailed side view of the suction belt table; and

[0019] FIG. 3 a schematic illustration of a feed roller configured as a dancer roller.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] The device for feeding sheets can be configured as a feeder 1 of a sheet-processing machine, in particular a sheet printing press or a die-cutting machine, and shall be described hereafter based on this example.

[0021] The device for feeding sheets, in particular the feeder 1, preferably comprises a main pile carrier, in particular a pile board, on which a pile composed of the sheets can be positioned. The pile board is attached to transport means.

[0022] At the rear and at the sides of the pile, blowers can be provided for pre-loosening the sheets on the pile as well as for blowing air beneath the sheets during transport. To be able to form an air cushion carrying the sheets, metal side plates or guide elements that laterally delimit the pile can additionally be arranged next to the pile.

[0023] A feeder head 7 is arranged in the region of the upper side of the pile.

[0024] The feeder head 7 preferably comprises a separating sucker and a transporting sucker. The feeder head 7 is preferably arranged in the feeder 1 so as to be height-adjustable. In addition, the feeder head 7 can be displaceably mounted in or counter to a transport direction 11 to adapt to formats. The feeder head 7, in particular the separating suckers thereof, are used to cyclically separate the sheets from the pile, wherein the transporting sucker picks up the separated sheets and conveys them in the transport direction 11. A sensing device detecting the height of the pile can be arranged in the pile region.

[0025] The transporting sucker transports the sheets to a belt table 2. The belt table 2 has a transport plane in which the sheets are transported by at least one revolving transport belt 14. A respective section of the at least one transport belt 14 is preferably guided over at least two upper feed rollers 12.1, 12.2 in the transport plane. At least one further feed roller 12.3, 12.4, 12.5 is provided next to the upper feed rollers 12.1, 12.2, which guides the at least one transport belt 14 outside, in particular beneath, the transport plane. A first drive 25 is assigned to the at least one further feed roller 12.3, 12.4, 12.5, so that the section of the at least one transport belt 14 which is guided in the transport plane forms the tight run 14.1 of the transport belt 14. The section of the at least one transport belt 14 guided outside the transport plane forms the slack run 14.2 of the at least one transport belt 14.

[0026] The first drive 25 is preferably configured as a motor 25.2. The first drive 25 can be directly assigned to the shaft of a further feed roller 12.3, 12.4, 12.5 or be connected via a gear wheel pair or a belt drive, in particular a toothed belt drive, to the further feed roller 12.3, 12.4, 12.5 in terms of transmission.

[0027] It is also possible for two or three further feed rollers 12.3, 12.4, 12.5 to be arranged outside, in particular beneath, the transport plane, over which the at least one transport belt 14 is guided, wherein, in the case of three further feed rollers 12.3, 12.4, 12.5, the first drive 25 can be assigned to the center one of the three further feed rollers 12.3, 12.4, 12.5. If multiple further feed rollers 12.3, 12.4, 12.5 are provided, over which the at least one transport belt 14 is guided, the first drive 25 can alternatively be assigned to the further feed roller 12.3, 12.4, 12.5 that is arranged the furthest from the feeder head 7. On the sheet-transporting side of the belt table 2, the transport belt 14 is consequently configured as a pulling belt. This has the advantage that the sheets located on the belt table 2 in the form of a sheet series can be transported more smoothly and uniformly, resulting in fewer disruptions.

[0028] The diameters of the feed rollers 12.1, 12.2, 12.3, 12.4, 12.5 can be different in size. The diameter of the feed roller 12.3, 12.4, 12.5 to which the first drive 25 is assigned is preferably larger than the diameter of the upper feed rollers 12.1, 12.2.

[0029] A tensioning device is preferably assigned to one of the further feed rollers 12.3, 12.4, 12.5, by way of which the respective further feed roller 12.3, 12.4, 12.5 can be displaced with respect to the at least one transport belt 14 so as to vary the tension thereof, and can be fixed in the displaced position. The tensioning device can also comprise an energy accumulator, in particular a spring system, the spring force of which is settable and which tightens one of the further feed rollers 12.3, 12.4, 12.5 in a spring-loaded manner against the transport belt 14.

[0030] At least one of the feed rollers 12.1, 12.2, 12.3, 12.4, 12.5, in particular one of the further feed rollers 12.3, 12.4, 12.5, is preferably configured as a dancer roller. A feed roller 12.1, 12.2, 12.3, 12.4, 12.5 configured in this way has a correcting belt guidance function, in particular when force and/or load changes occur in or on the transport belt 14. The feed roller 12.1, 12.2, 12.3, 12.4, 12.5 configured as a dancer roller has two degrees of freedom and corrects belt run errors automatically. Designing a feed roller 12.1, 12.2, 12.3, 12.4, 12.5 in the form of a dancer roller thus enables both a tilting movement thereof, transversely to the transport direction 11, and a rotational movement in the transport direction 11.

[0031] The dancer roller comprises a fixed shaft 26 and a hollow-cylindrical roller body 27 arranged rotatably about the shaft 26, coaxially to the shaft 26. A self-aligning bearing 28 acts between the shaft 26 and the roller body 27. The self-aligning bearing 28 can be configured as a ball joint bearing or as a spherical roller bearing or in another suitable form. The self-aligning bearing 28 is preferably arranged in the center between the two ends of the roller body 27, so that the center of mass of the roller body 27 is located above the self-aligning bearing 28, and the roller body 27 is balanced in relation to the self-aligning bearing 28.

[0032] The self-aligning bearing 28 can comprise an outer ring 29 connected to the roller body 27 and an inner ring 30 connected to the shaft 26. The outer ring 29 is supported with respect to the inner ring 30 by two ball rows 31.1, 31.2 or roller rows 31.1, 31.2 spaced apart from one another. A shared hollow-spherical raceway is preferably formed at the outer ring 29 and/or at the inner ring 30 for both ball rows 31.1, 31.2 or roller rows 31.1, 31.2. The feed roller 12.1, 12.2, 12.3, 12.4, 12.5, in particular the further feed roller 12.3, 12.4, 12.5, to which the first drive 25 is assigned, preferably has a convex shape, while all other feed rollers 12.1, 12.2, 12.3, 12.4, 12.5 can be configured to have a cylindrical shape. The feed roller 12.1, 12.2, 12.3, 12.4, 12.5 configured to have the convex shape and acting as a drive roller also preferably assumes a centering function in the system, in addition to the driving function. The feed roller 12.1, 12.2, 12.3, 12.4, 12.5 to which the first drive 25 is assigned is accordingly preferably different from the feed roller 12.1, 12.2, 12.3, 12.4, 12.5 configured as a dancer roller.

[0033] In a preferred embodiment of the device comprising two or three further feed rollers 12.3, 12.4, 12.5, which are arranged beneath the transport plane of the belt table 2, the first drive 25 can either be assigned to one of the two or to the center one of the three further feed rollers 12.3, 12.4, 12.5, wherein another further feed roller 12.3, 12.4, 12.5 is configured as the dancer roller.

[0034] Instead of a single transport belt 14, it is also possible for two or more transport belts 14 to be provided, which are arranged at a distance from one another and guided over upper feed rollers 12.1, 12.2 and further feed rollers 12.3, 12.4, 12.5.

[0035] The transport belts 14 are preferably configured as suction belts and have openings. The suction belts are preferably supplied with suction air by suction boxes, which can be integrated into the belt table 2. Sheets to be transported are held on a transport belt 14 configured as a suction belt due to the action of the suction air.

[0036] A feed table comprising front lay marks, an infeed and a processing mechanism of a sheet-processing machine can be arranged downstream of the belt table 2.

[0037] The processing mechanism is preferably an offset printing mechanism, a finish coating mechanism, an inkjet printing mechanism, or a die-cutting mechanism.

[0038] A sheet flap, which is connected to a pivotably mounted shaft, is formed between the transporting suckers and the at least one transport belt 14 of the belt table 2. The functional unit comprising the shaft and the sheet flap is also referred to as a flap shaft in technical jargon. The flap shaft extends across the width of the pile. The sheet flap is pivoted for each sheet to be conveyed from a vertical position, in which the sheet flap forms a stop, into a horizontal position, in which the sheet flap forms a guide surface. So-called timing rollers preferably cooperate with the at least one transport belt 14 of the belt table 2. The timing rollers can be assigned to a pivotably mounted timing roller shaft, which is pivoted synchronized with the sheet sequence, so that the timing rollers guide the front region of each sheet against the at least one transport belt 14 of the belt table 2. Multiple individual drives, which can be activated independently of one another, are preferably provided for driving the components inducing the sheet transport. In addition to the first drive 25 assigned to a feed roller 12.1, 12.2, 12.3, 12.4, 12.5, a second drive 24 can be provided, which is assigned to the shaft supporting the sheet flap. The second drive 24 can also be configured to jointly drive the timing roller shaft and the shaft connected to the sheet flap.

[0039] The timing roller shaft and/or the shaft connected to the sheet flap are preferably connected to the second drive 24 by way of a gear mechanism.

[0040] In addition, a third drive 22 can be assigned to the main pile carrier for the vertical displacement thereof. If a non-stop mechanism is provided, the main pile carrier cooperates with an auxiliary pile carrier during pile changing, which can be configured as a rake or roller rack and to which a fourth drive is preferably assigned for the vertical displacement thereof.

[0041] A fifth drive 23 can be provided for driving the feeder head 7 and/or the transporting sucker.

[0042] A sheet arrival sensor, which is preferably arranged at the end of the belt table 2, can be configured to detect the arrival of the sheets. The sheet arrival sensor can be used to detect the position of the sheets at a particular time prior to the sheets entering the processing mechanism. The sheet arrival sensor generates first signals representing the arrival of the sheets for a sequence of sheets.

[0043] A clock generator, which generates second signals representing the angular position of the at least one processing mechanism, is configured to detect the angular position of the at least one processing mechanism.

[0044] It is only possible to feed sheets to the at least one processing mechanism when the at least one processing mechanism, in particular the sheet-guiding cylinder thereof, is in a particular angular position. To achieve this, the individual drives 22, 23, 24, 25 have to be activated accordingly.

[0045] The drives 22, 23, 24, 25 as well as the clock generator and the sheet arrival sensor are connected to a controller.

[0046] The controller preferably controls the first drive 25 of a further feed roller 12.3, 12.4, 12.5 as a function of the signals of the clock generator, in particular the second signals. In other words, the movement of the transport belt or belts 14 of the belt table 2 exclusively follows the movement of the at least one processing mechanism.

[0047] In contrast to the first drive 25, the second drive 24 is not only controlled by the controller according to the second signals of the clock generator, but additionally also according to the first signals of the sheet arrival sensor.

[0048] Respective clock-based speed profiles can be entered into the controller for controlling the first and second drives 25, 24. The speed profiles can have a discontinuous speed curve.

[0049] The controller preferably ascertains the phase positions of the first signals in relation to the phase positions of the second signals and controls the second drive 24 as a function of the ascertained phase positions of the first signals in relation to the phase positions of the second signals. In this way, the occurrence of sheets arriving too early (early sheets) or the occurrence of sheets arriving too late (late sheets) can be inferred, and appropriate counter measures can be taken.

[0050] The controller is, in particular, configured to control the second drive 24 so as to shift, as a function of the phase positions of the first signals in relation to the phase positions of the second signals, the phase positions of the speed profile of the second drive 24 in a leading or trailing manner with respect to the phase positions of the speed profile of the first drive 25, or to activate the second drive 24 using a speed profile that has an increased or a decreased average speed.

[0051] If, for example, a late sheet is established as a result of the ascertainment of the phase positions, it is possible through an increased speed of the fifth drive 23 of the feeder head 7 and/or of the transporting sucker, and through an increased speed of the second drive 24 at the sheet flap with respect to the transport belt 14, to induce the leading sheet edge of succeeding sheets to arrive earlier at the processing mechanism. The imbrication length between the sheets is thereby reduced.

[0052] The controller can respond to an early sheet in a corresponding manner, with the difference that the speed of the fifth drive 23 and of the second drive 24 is reduced, and the imbrication length, that is, the distance between the leading edges of the sheets, is increased.

[0053] It is also possible to provide multiple sheet arrival sensors monitoring the sheets. The invention is not limited to the above-described exemplary embodiment. It is also possible for other components of the feeder 1 that are not mentioned in the exemplary embodiment and equipped with drives to be provided.

[0054] While a preferred embodiment of a device for feeding sheets, in accordance with the present invention, has been set forth fully and completely hereinabove, it will be apparent to one of skill in the art that various changes could be made thereto, without departing from the true spirit and scope of the present invention, which is accordingly to be limited only by the appended claims.