SHEET PROCESSING MACHINE

Abstract

The invention discloses a sheet processing machine with an alignment plate at the input. The sheets are piled against the plate, and during each machine cycle, the bottommost sheet is extracted and delivered to a gripper bar of the machine. The alignment plate can move precisely longitudinally and diagonally to adjust the position and the skew of the sheet for correct positioning in the gripper bar. The alignment plate is guaranteed to be kept vertical by using a pair of synchronized linear actuators on each side of the plate. The machine can adapt to varying sheet thickness by adjusting the gap below that plate thanks to a motorized gauge. To even better position the sheets, a set of abutments is provided after the plate, and at a fixed distance to the plate. The abutments are pivoting to get out of the way of the gripper bar when needed.

Claims

1. A sheet processing machine comprising: a transfer mechanism for moving sheets along a handling direction of the sheet processing machine, a loading station for supplying sheets to be processed, an alignment plate adjoining the loading station for aligning sheets piled in the loading station at a table level, and a handling mechanism for extracting the bottommost sheet from the pile of sheets, moving it through a gap between the table level and the bottom of the alignment plate and handing it over to the transfer mechanism, wherein the alignment plate is moveable in the handling direction by means of at least two linear actuators which are arranged at a distance to each other along a direction transverse to the handling direction, and wherein a support mechanism is provided that prevents the alignment plate from pivoting around a horizontal axis.

2. The sheet processing machine according to claim 1, wherein the alignment plate is moveable by means of two pairs of linear actuators, wherein the actuators within each pair of actuators are arranged vertically one above the other, and wherein a drive of the pair of actuators is configured such that the actuators within each pair of actuators are driven synchronously.

3. The sheet processing machine according claim 1, wherein the actuators comprise a threaded drive with a rotatable element and a rotatably fixed element which are in threaded engagement with each other.

4. The sheet processing machine according to claim 3, wherein the rotatably fixed element is fixed by means of two perpendicular axes, in particular to a machine frame.

5. The sheet processing machine according to claim 3, wherein the rotatably fixed element is fixed by means of a key and groove connection.

6. The sheet processing machine according to claim 3, wherein each pair of actuators is driven by a single motor and the rotatable elements of each pair of actuators are linked by a belt drive or a chain drive.

7. The sheet processing machine according to claim 3, wherein the rotatable element of each actuator is driven by a motor and the two motors assigned to each pair of actuators are synchronized.

8. The sheet processing machine according to claim 1, wherein the alignment plate comprises sliders at its lower end and rests with the sliders on a supporting surface.

9. The sheet processing machine according to claim 1, wherein a travel distance of the alignment plate is limited.

10. The sheet processing machine according to claim 1, wherein the alignment plate is guided by at least one linear guide.

11. The sheet processing machine according to claim 1, wherein the sheet processing machine comprises an abutment element which is arranged after the alignment plate and at a fixed distance from the alignment plate with respect to the handling direction for fine adjustment of a sheet.

12. The sheet processing machine according to claim 11, wherein the abutment element is formed at an edge of a tablet which is mounted at the alignment plate.

13. The sheet processing machine according to claim 12, wherein the tablet is pivotably mounted to the alignment plate and the pivots are arranged below the table level on which the sheets are placed.

14. The sheet processing machine according to claim 12, wherein the tablet has the form of an L.

15. The sheet processing machine according to claim 1, wherein the alignment plate comprises an integrated gauge plate that is height adjustable with respect to the alignment plate for setting the gap.

16. The sheet processing machine according to claim 1, wherein the sheet processing machine comprises a handling mechanism configured to move a sheet from the sheets piled in the loading station to feed a sheet to the transfer mechanism.

Description

[0032] Further features and advantages of the invention become apparent from the following description and the enclosed figures. In the figures:

[0033] FIG. 1 shows a sheet processing machine according to the invention in a schematic view,

[0034] FIG. 2 shows a sub-assembly of an example of the inventive sheet processing machine,

[0035] FIG. 3 shows the subassembly of FIG. 2 in a partially exploded view,

[0036] FIG. 4 shows a further subassembly of an example of the inventive sheet processing machine,

[0037] FIG. 5 shows the subassembly of FIG. 4,

[0038] FIG. 6 shows a linear actuator for the inventive sheet processing machine,

[0039] FIG. 7 shows the linear actuator of FIG. 6,

[0040] FIG. 8 shows an alternative linear actuator for the inventive sheet processing machine,

[0041] FIG. 9 shows the linear actuator of FIG. 8,

[0042] FIG. 10 shows an abutment of the linear actuator of FIGS. 8 and 9,

[0043] FIG. 11 shows the subassembly of FIGS. 2 and 3 in a top view in a first condition,

[0044] FIG. 12 shows the subassembly of FIGS. 2 and 3 in a second condition,

[0045] FIG. 13 shows the subassembly of FIGS. 2 and 3 in a further condition,

[0046] FIG. 14 shows an alternative arrangement of actuators for the inventive sheet processing machine, and

[0047] FIG. 15 shows a further alternative arrangement of actuators in combination with a guide for the inventive sheet processing machine.

[0048] FIG. 1 schematically shows a sheet processing machine 10 in a simplified manner.

[0049] With reference to FIG. 1, the general structure and operation of the sheet processing machine 10 according to the invention will be explained.

[0050] The sheet processing machine 10 comprises a loading station 12 for supplying sheets 14 to be processed.

[0051] The sheet processing machine 10 further comprises a transfer mechanism 16 for moving sheets 14 along a handling direction of the sheet processing machine 10. The handling direction is indicated in FIG. 1 by arrow 18.

[0052] Moreover, the sheet processing machine 10 comprises a handling mechanism 20 configured to move a sheet 14 from the sheets 14 piled in the loading station 12 to feed a sheet 14 to the transfer mechanism 16.

[0053] Before being fed to the transfer mechanism 16, the sheets 14 must be properly aligned to ensure accurate processing of the sheets 14 in the sheet processing machine 10.

[0054] For this purpose, the sheet processing machine 10 has an alignment plate 26 adjoining the loading station 12 for aligning sheets 14 piled in the loading station 12.

[0055] The handling mechanism 20 comprises an extraction element 22 for extracting a single sheet 14 from the loading station 12 and optionally an abutment element 28. The abutment element 28 is arranged after the alignment plate 26 with respect to the handling direction. The abutment element 28 is positioned at a fixed distance from the plate 26 and facilitates a repeated alignment of the sheets 14 after removing the sheets 14 form the loading station 12. The abutment mechanism may compensate for a slight imprecision caused by the extraction element 22.

[0056] The transfer mechanism 16 comprises a gripper bar 24 configured to grip the sheets 14 provided by the handling mechanism 20. The gripper bar 24 may be driven by two lateral chain drives (not shown) that cycle through the machine. The gripper bar 24 preferably comprises a set of mechanical grippers that grip to the sheet or may comprise a vacuum system to hold on to the sheet.

[0057] For operating the sheet processing machine 10, several sheets 14 are piled in the loading station 12.

[0058] As shown in FIG. 1, the sheets 14 abut the alignment plate 26 and are thereby pre-aligned.

[0059] The extraction element 22 of the handling mechanism 20 extracts a single sheet 14 from the loading station 12, in particular, the bottom sheet 14, and moves it to a gripping position in which the gripper bar 24 may grip the sheet.

[0060] The extraction element 22 is for example configured to move back and forth with a fixed motion amplitude.

[0061] Preferably, the extraction element 22 travels with a slight over-travel such that the travel of the extraction element 22 is larger than a distance d between an abutment surface the alignment plate 26 and the abutment element 28. Thereby, the sheet is realigned at the abutment element 28 after being extracted from the pile of sheets.

[0062] For example, the over-travel is 1,5 mm or less. Thereby, the risk of damaging the sheet 14 upon aligning the sheet 14 at the abutment element 28 is reduced.

[0063] When the sheet 14 is in the gripping position, the gripper bar 24 grabs the sheet and feeds it to the processing stations of the machine for further processing.

[0064] The alignment plate 26 is moveable in the handling direction, as indicated by arrows in FIG. 1. Thereby, the position of the pile of sheets 14 can be adjusted.

[0065] According to the inventive idea, the position of the alignment plate 26 along the handling direction can be set independently for both lateral sides of the alignment plate 26, i.e., for an operator side and an opposite operator side. However, the alignment plate 26 is only allowed to tilt around a vertical axis, but not around a horizontal axis. Thereby, the alignment plate 26 is always in an upright position.

[0066] FIGS. 2 and 3 show a subassembly of the sheet processing machine 10 in a more detailed depiction.

[0067] The subassembly includes the handling mechanism 20 and the alignment plate 26 as well as the abutment element 28.

[0068] In the depicted embodiment, the extraction element 22 of the handling mechanism 20 is a vacuum table having suction areas 30 to grab a sheet 14, which is visualized in FIG. 2 by dashed lines.

[0069] The extraction element 22 is integrated into a table 32 on which the sheets 14 are piled.

[0070] In the loading station 12, lateral guiding elements 34 are arranged for further improving the alignment of the sheets 14.

[0071] The lateral guiding elements 34 are arranged with a distance to the table 32 to allow the bottommost sheet 14 to travel easily when it is extracted from the pile.

[0072] The alignment plate 26 comprises sliders 36 at its lower end and rests with the sliders 36 on a supporting surface 38. The supporting surface 38 defines a vertical position of the alignment plate 26.

[0073] The sliders 36 can move freely in a horizontal direction.

[0074] Furthermore, the alignment plate 26 is guided by a linear guide 40.

[0075] The linear guide 40 comprises a guide element 42 that is attached to a machine frame 43 and a corresponding groove 44 in the alignment plate 26.

[0076] The abutment element 28 is formed at an edge of a tablet 46 which is mounted at the alignment plate 26. Thereby, there is a fixed distance between the abutment element 28 and the alignment plate 26.

[0077] In particular, the tablet 46 is pivotably mounted to the alignment plate 26.

[0078] The tablet 46 has the form of an L.

[0079] When the tablet 46 is in a supporting position as shown in FIG. 2, the tablet 46 forms an extension of the table 32.

[0080] The pivots 48 of the tablet 46 are arranged below a table level on which the sheets 14 are placed.

[0081] The alignment plate 26 comprises an integrated gauge plate 50.

[0082] The gauge plate 50 is height adjustable with respect to the alignment plate 26, in particular by means of a linear actuator 52.

[0083] The gauge plate 50 is configured to set the gap 25 and ensure that only one sheet 14 at a time can be extracted from the pile of sheets in the loading station 12, despite a varying sheet thickness across processing jobs.

[0084] The alignment plate 26 is moveable in the handling direction by means of two pairs of linear actuators 54: The pair 54a of actuators 54 on the operator side of the machine and the pair 54b of actuators 54 on the opposite operator side of the machine. The actuators 54 of each pair 54a,54b of actuators are arranged vertically one above the other, respectively.

[0085] The actuators 54 in FIG. 2 are depicted in a simplified form, but will be described in more detail with reference to FIGS. 6 to 10.

[0086] A drive 58a, 58b of the actuators 54, which will be explained with reference to FIGS. 4 and 5, is configured such that the actuators 54 within each pair 54a, 54b of actuators are driven synchronously.

[0087] By synchronously driving the two actuators 54 of a pair 54a of actuators, and by synchronously driving the two actuators 54 of pair 54b of actuators, the alignment plate 26 is held in an upright position. Thus, a support mechanism 53 is implemented by means of the specific arrangement of synchronously driven actuators 54.

[0088] As shown in FIGS. 4 and 5, the two actuators 54 of each pair 54a, 54b of actuators are linked by a belt drive or a chain drive 55, respectively.

[0089] The actuators 54 within each pair are synchronously driven by a motor 60 which drives the belt drive or chain drive 55.

[0090] In an alternative embodiment, which is not shown for reasons of simplicity, each actuator 54 may be driven by a motor 60 and each two motors 60 assigned to a pair of actuators 54 are synchronized, resulting in four motors 60 synchronized in pairs.

[0091] The travel distance of the alignment plate 26 may be limited. For this purpose, a sensor 62, in particular a limit switch sensor may be provided.

[0092] FIGS. 6 and 7 show a linear actuator 54 according to a first embodiment.

[0093] The actuators 54 are attached to blocks 64 that are attached to the machine frame 43.

[0094] The blocks 64 which are designated to the lower actuators 54 have a supporting roller 66 to support the actuator 54.

[0095] The actuator 54 shown in FIGS. 6 and 7 comprises a threaded drive with a rotatable element 68 and a rotatably fixed element 70 which are in threaded engagement with each other. In the shown embodiment, the rotatably fixed element 70 is a screw and the rotatable element is a threaded shaft.

[0096] The rotatably fixed element 70 is fixed to the machine frame 43 and the rotatable element 68 is coupled to the alignment plate 26.

[0097] The rotatably fixed element 70 is fixed by means of two perpendicular axes, in particular to the block 64 and thus to the machine frame 43.

[0098] One of the axes is a horizontal axis x and one of the axes is a vertical axis y.

[0099] The horizontal axis x provides a transversal translation freedom to accommodate with the small transversal movement of a lateral edge of the alignment plate as well as a slight vertical rotation, as indicated by arrows in FIG. 7.

[0100] The vertical axis provides a horizontal rotation freedom as well as a vertical play, as also indicated by arrows in FIG. 7.

[0101] The rotatable element 68 is supported by means of a bearing 72.

[0102] A mechanical play between the rotatable element 68 and the rotatably fixed element is preferably suppressed by applying a constraint between the two elements.

[0103] At one end, the rotatable element 68 has a flange 74. The flange 74 is configured to take along the alignment plate 26 when the rotatable element 68 is moved in a direction away from the rotatably fixed element 70.

[0104] When the rotatable element 68 is rotated and thus linearly moved along the rotatable fixed element, the flange exerts a force on the alignment plate 26 such that the alignment plate 26 travels with the rotatable element 68. Thereby, a horizontal position of the alignment plate 26 is adjusted.

[0105] At the other end, the rotatable element 68 has a pinion 76 which may be integrally formed with the rotatable element 68. By means of the pinion 76 the belt drive or chain drive 55 may be coupled to the rotatable element.

[0106] In an alternative embodiment, the position of the rotatable element 68 and the rotatably fixed element 70 may be switched, such that the rotatable element 68 is mounted to the machine frame 43 and the rotatably fixed element 70 is mounted at the alignment plate 26.

[0107] As shown in FIGS. 4 and 5, the linear actuators 54 are coupled to the alignment plate 26 by means of rods 78 that are connected to the alignment plate 26.

[0108] Close to each actuator 54, an elastic element 80 (see FIG. 5), for example a pusher or a spring, acts on the alignment plate 26, in particular via the rods 78. The elastic elements 80 provide an elastic force for moving the alignment plate 26 with the rotatable element 68 when the rotatable element 68 is moved in a direction towards the rotatably fixed element 70.

[0109] FIGS. 8 to 10 show a linear actuator 54 according to a further embodiment. Compared to the actuator 54 shown in FIGS. 6 and 7, the actuator 54 has a simplified design.

[0110] In this embodiment, the rotatably fixed element 70 is fixed by means of a key and groove connection 82.

[0111] Also, the bearing 72 of the rotatable element 68 is simplified. In particular, the bearing 72 is a cylindrical plain bearing.

[0112] The flange 74 is implemented by means of a cover 84 which comprises a groove 86 for the key and groove connection 82.

[0113] One end of the rotatably fixed element 70, in particular a screw head 88 of the rotatably fixed element 70 abuts the static block 64 fixed to the machine frame 43.

[0114] The elastic elements 80, which are not show in FIGS. 8 to 10, urge the linear actuator 54 against the block 64 such that the rotatably fixed element 70 stays in contact with the static block 64. Thereby, a precise reference is maintained.

[0115] It is thinkable that the amount of force is lowered during the longitudinal setting of the alignment plate 26 to reduce wear.

[0116] As shown in FIG. 10, the contact surface of the rotatably fixed element 70 with the block 64 is spherical to allow angular play.

[0117] FIGS. 11 to 13 further illustrate the operation of the inventive sheet processing machine 10.

[0118] In FIGS. 11 to 13, the alignment plate 26 is depicted with a skewing angle which is exaggerated in the Figures for exemplification.

[0119] The skewing angle can be adjusted by operating the pair of actuators 54a independently from the pair of actuators 54b, in particular with different numbers of revolutions.

[0120] FIG. 11 shows the sheet processing machine 10 in a condition where a sheet 14 is placed in the loading station 12 and is in abutment with the alignment plate 26.

[0121] The extraction element 22 of the handling mechanism 20 is in a position below the sheet 14 for picking up the bottommost sheet 14 of a pile.

[0122] FIG. 12 shows a condition of the sheet processing machine 10 in which the extraction element 22 has traveled to a supplying position, wherein upon traveling the extraction element 22 has extracted the bottommost sheet 14 from the pile.

[0123] In this condition, the sheet 14 abuts the abutment element 28 to be realigned.

[0124] When the sheet 14 is in the position as shown in FIG. 12, the gripper bar 24 is able to grip the sheet 14 and transport the sheet through the processing stations of the machine.

[0125] To enable the gripper bar 24 to pull the sheet towards the transfer mechanism 16, the tablet 46 is pivoted such that the abutment element 28 is lowered and a travel path of the sheet 14 is cleared (see FIG. 13).

[0126] FIG. 14 illustrate an alternative drive for the alignment plate 26 that can be integrated in the sheet processing machine 10 which has been described with reference to FIGS. 1 to 13.

[0127] The embodiment according to FIG. 14 differs from the embodiment described in accordance to FIGS. 1 to 13 in the arrangement of the actuators 54. In particular, the alignment plate 26 is moveable along a handling direction by means of three actuators 54.

[0128] The actuators 54 are arranged with a distance to each other in a direction transverse to a handling direction of the sheet processing machine 10.

[0129] One actuator 54 is arranged close to an operator side of the alignment plate 26 and the other actuator 54 is arranged close to an opposite operator side, i. e with a distance of less than 20 cm, in particular less than 10 cm to the operator side respectively the opposite operator side.

[0130] The two actuators 54 are arranged at the same vertical position.

[0131] A third actuator 54 is arranged between the two actuators at the operator side and the opposite operator side, in particular on a vertical center line of the alignment plate 26.

[0132] The third actuator 54 is arranged at a different height than the other two actuators 54.

[0133] The third actuator 54 supports the alignment plate 26 in such a way that tilting of the alignment plate 26 around a horizontal axis upon movement of the alignment plate 26 is prevented. Thus, by means of the third actuator 54, the support mechanism 53 is realized.

[0134] A turning rate of the third actuator 54 while moving the alignment plate 26 is for example adapted to the turning rate of the further actuators 54 to prevent tilting of the alignment plate around a horizontal axis. FIG. 15 illustrates an alternative drive for the alignment plate 26 which is in accordance with the invention.

[0135] Instead of a third actuator 54 that is arranged on a vertical center line of the alignment plate 26, the drive comprises a rail 90 that maintains an upright position of the alignment plate 26.