Sheet Processing Machinery

Abstract

The present invention discloses a sheet processing machine (10) having a registration plate (26) at its input. Sheets are stacked against the plate and during each machine cycle the bottommost sheet is extracted and delivered to the gripper bar (24) of the machine. The registration plate can be moved precisely longitudinally and diagonally to adjust the position and distortion of the sheet with respect to correct positioning on the gripper bar. The registration plate is ensured to remain vertical by using a pair of synchronized linear actuators (54a, 54b) on each side of the plate. The machine can accommodate different sheet thicknesses by adjusting the gap (25) below the plate as a result of a motorized gauge. To better position the sheets a set of abutments (28) are provided behind and at a fixed distance to the plate. The abutments pivot out of the way of the gripper bar when required.

Description

[Technical field]

[0001] The present invention relates to sheet converting machines for converting corrugated board, such as die-cutting, creasing and / or printing machines. [Background technology]

[0002] Sheet converting machines typically have a loading station where the corrugated sheets to be converted are stacked before being transferred to a converting mechanism of the sheet converting machine.

[0003] At the loading station, the sheet is roughly aligned by an alignment plate, the position of which is adjustable to accommodate the alignment of the sheet.

[0004] The sheets are individually extracted from the loading station and transferred to a transfer mechanism of the sheet processing machine, where they undergo additional fine adjustments before being transferred to the transfer mechanism.

[0005] Additionally, a gauge is provided, usually incorporated into the registration plate, which ensures that only a single sheet can be extracted from the loading station at a time.

[0006] However, in conventional sheet processing machines, when adjusting the position of the alignment plate, it may happen that the alignment plate pivots about a horizontal axis. This interferes with the alignment of the sheet at the loading station, since the alignment plate no longer provides a consistent level adjustment for the sheet. Furthermore, pivoting the alignment plate affects the gauge setting, since the distance of the gauge to the level of the sheet's support area changes. That is, it may happen that more than a single sheet is extracted from the loading station at one time. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE PRESENT EMBODIMENT It is an object of the present invention, namely, to provide a sheet converting machine in which sheet registration and transport are improved. [Means for solving the problem]

[0008] This object is solved by a sheet processing machine comprising a transport mechanism for moving sheets along a handling direction of the sheet processing machine, a loading station for feeding the sheets to be processed, and an alignment plate adjacent to the loading station for aligning the sheets stacked in the loading station. The alignment plate is movable in the handling direction by at least two linear actuators arranged at a distance from each other in a direction transverse to the handling direction. In particular, one actuator is arranged on or near the operator side and the other actuator is arranged opposite or near the operator side. Furthermore, a support mechanism is provided which prevents the alignment plate from pivoting about a horizontal axis.

[0009] The sheet processing machine according to the invention is improved with regard to fine adjustment and reproducibility. In particular, pivoting of the alignment plate around a horizontal axis is not possible, i.e. no changes in the height of the lower edge of the alignment plate occur and the position of the alignment plate is always upright. The positioning of the sheet at the loading station by the alignment plate is thus particularly precise. By actuating the actuators independently of one another, the sheet at the loading station can be aligned with regard to distortion.

[0010] According to one embodiment, the alignment plate is movable by means of two pairs of linear actuators, the actuators of which are arranged vertically above one another, in other words the actuators are at the same position with respect to a longitudinal direction of the alignment plate transverse to the handling direction of the sheet processing machine, the actuator drives being configured such that the actuators of each pair of actuators are driven synchronously.

[0011] With two pairs of actuators, i.e. four actuators, unwanted tilting of the alignment plate about the vertical axis is substantially avoided, which means that according to one embodiment the support mechanism is implemented by providing two pairs of synchronously driven actuators positioned in the above-mentioned manner.

[0012] In alternative embodiments, the actuators of each pair of actuators may not be arranged vertically above and below each other, but in this case the actuators cannot be driven synchronously but rather must be driven at different rotational speeds, which makes it more difficult to control the movement of the alignment plate.

[0013] In yet another alternative embodiment, the support mechanism may be a guide that maintains the upright position of the alignment plate.

[0014] In yet another alternative embodiment, the support mechanism may include an additional linear actuator disposed between the at least two actuators, specifically on the vertical centerline of the alignment plate.

[0015] The actuator may include a threaded drive having a rotatable element and a rotatable fixed element that are threadedly engaged with each other, whereby the rotatable movement of the rotatable element can be converted into a linear movement in a simple manner.

[0016] The rotatable fixed element is fixed in particular to the machine frame by two vertical axes, which allow a limited play of the rotatable fixed element to avoid over-constraint of the actuator. In particular, the vertical axes provide the actuator with a horizontal rotational degree of freedom and allow vertical play to accommodate the distortion angle of the alignment plate. The horizontal axis provides a transverse translational degree of freedom.

[0017] In yet another embodiment, the rotatable fixed element is fixed by a key and groove connection, which is somewhat simpler in its design and thus provides a cost-effective solution for rotatably fixing the fixed element.

[0018] According to one embodiment, where the alignment plate is movable using two pairs of linear actuators, the actuators of each pair being arranged vertically above each other, the actuators of each pair are driven by a single motor and the rotatable elements of the actuators of each pair are linked by a belt or chain drive. Thereby, synchronization of the two actuators of a pair of actuators is achieved in a simple manner. In particular, the two actuators are mechanically linked by a belt or chain drive such that the actuators are driven at the same rotational speed. Yet another advantage is that by using a single motor to drive the two actuators, a compact and cost-effective design of the sheet processing machine is achieved.

[0019] In an alternative embodiment in which the alignment plate is movable using two pairs of linear actuators, the actuators of each pair being arranged vertically above one another, the rotatable element of each actuator is driven by a motor, and the two motors assigned to one pair of actuators are synchronized, thereby making it possible to omit a mechanical link between the actuators.

[0020] With motors driving the actuators, adjustment of the alignment plates can be accomplished in an automated manner.

[0021] The alignment plate may include a slider at its lower end and together with the slider may rest on a support surface, whereby the weight of the alignment plate rests on a support surface which may be located on the machine frame. That is, the actuator does not need to carry the weight of the alignment plate and therefore does not need to be designed for a weight load. In particular, the actuator only needs to push and pull the alignment plate in a direction along the handling direction of the sheet converting machine. The support surface also defines a fixed vertical position of the alignment plate.

[0022] For example, the travel distance of the alignment plate is limited, so that components that contribute to the adjustability of the alignment plate do not need to be designed for over-travel of the alignment plate.

[0023] According to one embodiment, a limit switch sensor can be provided to stop the motor driving the actuator when the limit switch sensor detects maximum travel of the alignment plate.

[0024] The alignment plate may be guided by at least one linear guide, which keeps the alignment plate laterally centered, thereby limiting tilt of the alignment plate about the vertical axis, and in particular avoiding excessive increases in the tilt angle of the alignment plate, which could cause the actuator elements to become wedged into each other.

[0025] According to one aspect, the sheet processing machine includes an abutment element that may be formed on the edge of a tablet that is arranged behind the alignment plate relative to the handling direction and attached to the alignment plate for fine adjustment of the sheet. The distance between the alignment plate and the abutment element is fixed. The abutment element is parallel to the alignment plate at all times except when it is lowered. This embodiment is particularly advantageous as the abutment element is adjusted simultaneously with the alignment plate, which means that no separate drive is required to adjust the abutment element.

[0026] The tablet may, for example, be pivotally mounted on an alignment plate, the pivot being located below the table level on which the sheet rests, so that the tablet can pivot so that the abutment element is lowered to clear the way for the sheet to pass the abutment element after fine positioning.

[0027] The tablet may have the form of an L, whereby an abutment element with a fixed distance to the alignment plate can be realized in a simple manner, in particular one leg of the L forms the abutment element and projects above the table level when the other leg is on the table level.

[0028] The alignment plate may include an integral gauge plate that is height adjustable relative to the alignment plate. The gauge allows the gap between the table level and the bottom of the alignment plate to be set, i.e. allowing it to accommodate several sheet thicknesses. The gauge plate can thus be adjusted in height independently of the alignment plate. Height adjustment of the alignment plate is not necessary, thereby simplifying the construction of the sheet processing machine.

[0029] For example, the gauge plate may be height adjustable relative to the alignment plate using a further linear actuator, i.e. the gauge plate may be adjusted with sufficient precision.

[0030] An alternative to a gauge would be to adjust the overall plate height.

[0031] The sheet processing machine preferably includes a handling mechanism configured to move sheets from a stack of sheets at a loading station for feeding the sheets to a transfer mechanism, which may be performed in an automated manner.

[0032] Further features and advantages of the present invention will become apparent from the following description and included drawings. [Brief description of the drawings]

[0033] [Figure 1] 1 is a schematic diagram of a sheet processing machine according to the present invention; [Diagram 2] FIG. 2 shows a subassembly of the sheet converting machine of the present invention. [Diagram 3] FIG. 3 is a partial exploded view of the subassembly of FIG. 2. [Figure 4] FIG. 4 illustrates yet another subassembly of the sheet converting machine of the present invention. [Diagram 5] FIG. 5 shows a subassembly of FIG. 4. [Figure 6] FIG. 2 illustrates a linear actuator for a sheet processing machine of the present invention. [Figure 7] FIG. 7 illustrates the linear actuator of FIG. 6. [Figure 8] FIG. 1 illustrates an alternative linear actuator for the sheet processing machine of the present invention. [Figure 9] FIG. 9 illustrates the linear actuator of FIG. 8. [Figure 10] FIG. 10 illustrates the abutment of the linear actuator of FIGS. 8 and 9. [Figure 11] FIG. 4 is a top view of the subassembly of FIGS. 2 and 3 in a first condition. [Figure 12] FIG. 4 shows the subassembly of FIGS. 2 and 3 in a second condition. [Figure 13] FIG. 4 shows the subassembly of FIGS. 2 and 3 in yet another condition. [Figure 14] 11A-11C show alternative actuator arrangements for the sheet processing machine of the present invention; [Figure 15] FIG. 13 illustrates yet another alternative arrangement of an actuator in combination with a guide for the sheet processing machine of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] FIG. 1 shows diagrammatically a sheet processing machine 10 in a simplified manner.

[0035] With reference to FIG. 1, the general structure and operation of a sheet converting machine 10 according to the present invention will now be described.

[0036] The sheet processing machine 10 includes a loading station 12 for supplying a sheet 14 to be processed.

[0037] The sheet processing machine 10 further includes a transport mechanism 16 for moving the sheet 14 along a handling direction of the sheet processing machine 10. The handling direction is indicated by arrow 18 in FIG.

[0038] Additionally, the sheet processing machine 10 includes a handling mechanism 20 configured to move sheets 14 from the stack of sheets 14 at the loading station 12 for feeding the sheets 14 to the transport mechanism 16 .

[0039] Before the sheet 14 is fed into the transport mechanism 16 , it must be properly registered to ensure accurate processing of the sheet 14 in the sheet processing machine 10 .

[0040] To this end, the sheet converting machine 10 includes an alignment plate 26 adjacent the loading station 12 for aligning the sheets 14 stacked at the loading station 12 .

[0041] The handling mechanism 20 includes an extraction element 22 for extracting a single sheet 14 from the loading station 12 and an optional abutment element 28. The abutment element 28 is disposed behind 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 repeatable alignment of the sheet 14 after removal from the loading station 12. The abutment mechanism can compensate for slight inaccuracies caused by the extraction element 22.

[0042] The transport mechanism 16 includes a gripper bar 24 configured to grip the sheets 14 fed by the handling mechanism 20. The gripper bar 24 may be driven by two lateral chain drives (not shown) that circulate through the machine. The gripper bar 24 preferably includes a set of mechanical grippers that hold against the sheets, or may include a vacuum system that holds against the sheets.

[0043] To operate the sheet converting machine 10 , a number of sheets 14 are stacked at the loading station 12 .

[0044] As shown in FIG. 1, sheet 14 abuts and is pre-aligned by alignment plate 26. As shown in FIG.

[0045] An extraction element 22 of the handling mechanism 20 extracts a single sheet 14, particularly the bottom sheet 14, from the loading station 12 and moves it to a gripping position where a gripper bar 24 can grip the sheet.

[0046] The extraction element 22 is, for example, configured to move back and forth with a fixed amplitude of motion.

[0047] Preferably, the extraction element 22 advances with a slight overadvance such that the advance of the extraction element 22 is greater than the distance d between the abutment surface of the alignment plate 26 and the abutment element 28, so that the sheet is realigned with the abutment element 28 after it has been extracted from the stack of sheets.

[0048] For example, the overtravel is less than or equal to 1.5 mm, thereby reducing the risk of damaging the sheet 14 when it is aligned with the abutment element 28.

[0049] When the sheet 14 is in the gripping position, the gripper bars 24 grip the sheet and deliver it to a processing station of the machine for further processing.

[0050] The registration plate 26 is movable in the handling direction, as shown by the arrow in Figure 1, so that the position of the stack of sheets 14 can be adjusted.

[0051] Due to the inventive concept, 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. the operator side and the opposite operator side. However, the alignment plate 26 is only allowed to tilt about a vertical axis and not about a horizontal axis, so that the alignment plate 26 is always in an upright position.

[0052] 2 and 3 show subassemblies of the sheet converting machine 10 in more detailed depictions.

[0053] The subassembly includes a handling mechanism 20 , an alignment plate 26 , and an abutment element 28 .

[0054] In the depicted embodiment, the extraction element 22 of the handling mechanism 20 is a vacuum table having a suction area 30 that grips the sheet 14, which is shown in FIG. 2 by a dashed line.

[0055] The brewing element 22 is mounted on a table 32 on which the sheets 14 are stacked.

[0056] At the loading station 12 lateral guide elements 34 are arranged to further improve the alignment of the sheets 14 .

[0057] The lateral guide element 34 is spaced apart relative to the table 32 to allow the bottommost sheet 14 to advance easily as it is extracted from the stack.

[0058] The alignment plate 26 includes a slider 36 at its lower end and rests together with the slider 36 on a support surface 38. The support surface 38 defines the vertical position of the alignment plate 26.

[0059] The slider 36 is free to move horizontally.

[0060] Additionally, alignment plate 26 is guided by linear guides 40 .

[0061] The linear guide 40 includes a guide element 42 mounted on the machine frame 43 and a corresponding groove 44 in the alignment plate 26 .

[0062] The abutment element 28 is formed on an edge of a tablet 46 that is attached to the alignment plate 26. Thereby, there is a fixed distance between the abutment element 28 and the alignment plate 26.

[0063] In particular, the tablet 46 is pivotally mounted to the alignment plate 26 .

[0064] The tablet 46 has an L-shape.

[0065] When the tablet 46 is in the support position as shown in FIG.

[0066] The pivot 48 of the tablet 46 is located below the table level on which the seat 14 rests.

[0067] The alignment plate 26 includes an integral gauge plate 50 .

[0068] The gauge plate 50 is height adjustable relative to the alignment plate 26 by, inter alia, a linear actuator 52 .

[0069] The gauge plate 50 is configured to set the gap 25 to ensure that only one sheet 14 at a time can be extracted from the stack of sheets at the loading station 12 despite variations in sheet thickness throughout the converting operation.

[0070] The alignment plate 26 is movable in the handling direction by two pairs of linear actuators 54: a pair 54a of actuators 54 on the operator side of the machine and a pair 54b of actuators 54 opposite the operator side of the machine. The actuators 54 of each pair 54a, 54b are arranged vertically above and below each other, respectively.

[0071] The actuator 54 in FIG. 2 is depicted in simplified form and is described in more detail below with reference to FIGS.

[0072] The drives 58a, 58b for the actuators 54, described below with reference to Figures 4 and 5, are arranged such that the actuators 54 in each actuator pair 54a, 54b are driven synchronously.

[0073] By synchronously driving two actuators 54 of actuator pair 54a and by synchronously driving two actuators 54 of actuator pair 54b, alignment plate 26 is held in an upright position. That is, a particular arrangement of synchronously driven actuators 54 is used to implement support mechanism 53.

[0074] As shown in Figures 4 and 5, the two actuators 54 of each actuator pair 54a, 54b, respectively, are linked by a belt drive or chain drive 55.

[0075] The actuators 54 in each pair are driven synchronously by a motor 60 which drives a belt or chain drive 55 .

[0076] In an alternative embodiment, not shown for reasons of simplicity, each actuator 54 can be driven by a motor 60, with each two motors 60 assigned to a pair of actuators 54 being synchronized to result in four motors 60 synchronized in the pair.

[0077] 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.

[0078] 6 and 7 show a linear actuator 54 according to a first embodiment.

[0079] The actuator 54 is mounted on a block 64 which is attached to the machine frame 43 .

[0080] A block 64 designated as the lower actuator 54 has support rollers 66 which support the actuator 54 .

[0081] The actuator 54 shown in Figures 6 and 7 includes a threaded drive having a rotatable element 68 and a rotatable fixed element 70 that are threadedly engaged with each other. In the illustrated embodiment, the rotatable fixed element 70 is a screw and the rotatable element is a threaded shaft.

[0082] The rotatable fixed element 70 is fixed to the machine frame 43 and the rotatable element 68 is coupled to the alignment plate 26 .

[0083] The rotatable fixed element 70 is fixed in particular to the block 64 and thus to the machine frame 43 by means of two vertical axes.

[0084] One of the axes is a horizontal axis x and one of the axes is a vertical axis y.

[0085] The horizontal axis x provides a transverse translation degree of freedom to accommodate small transverse movements of the side edges of the alignment plate as well as slight vertical rotation, as indicated by the arrows in FIG.

[0086] The vertical axis provides a horizontal rotational degree of freedom as well as vertical play, also as indicated by the arrows in FIG.

[0087] The rotatable element 68 is supported by bearings 72 .

[0088] Mechanical play between the rotatable element 68 and the rotatable fixed element is preferably constrained by applying a constraint between the two elements.

[0089] At one end, the rotatable element 68 has a flange 74. The flange 74 is configured to entrain the alignment plate 26 when the rotatable element 68 is moved away from the rotatable stationary element 70.

[0090] As the rotatable element 70 is rotated, i.e., moved linearly along the rotatable stationary element, the flange exerts a force on the alignment plate 26 such that the alignment plate 26 advances with the rotatable element 68, thereby adjusting the horizontal position of the alignment plate 26.

[0091] At the other end, the rotatable element 68 has a pinion 76, which may be formed integrally with the rotatable element 68. The pinion 76 allows a belt drive or chain drive 55 to be coupled to the rotatable element.

[0092] In an alternative embodiment, the positions of the rotatable element 68 and the rotatable fixed element 70 can be swapped such that the rotatable element 68 is mounted to the machine frame 43 and the rotatable fixed element 70 is mounted to the alignment plate 26.

[0093] As shown in FIGS. 4 and 5, the linear actuator 54 is coupled to the alignment plate 26 by a rod 78 connected to the alignment plate 26 .

[0094] Near each actuator 54, a resilient element 80 (see FIG. 5), e.g., a pusher or a spring, acts on the alignment plate 26, in particular through the rod 78. The resilient element 80 provides a resilient force for moving the alignment plate 26 together with the rotatable element 68 when the rotatable element 68 is moved in a direction towards the rotatable fixed element 70.

[0095] Figures 8 to 10 show a linear actuator 54 according to yet another embodiment. Compared to the actuator 54 shown in Figures 6 and 7, the actuator 54 has a simplified design.

[0096] In this embodiment, the rotatable fixed element 70 is fixed by a key and groove connection 82 .

[0097] Likewise, the bearing 72 of the rotatable element 68 is simplified. In particular, the bearing 72 is a cylindrical plain bearing.

[0098] The flange 74 is implemented by a cover 84 that includes a groove 86 for the key and a groove connection 82 .

[0099] One end of the rotatable fixed element 70 , in particular the screw head 88 of the rotatable fixed element 70 , abuts against a static block 64 fixed to the machine frame 43 .

[0100] 8 to 10 biases the linear actuator 54 against the stationary block 64 such that the rotatable fixed element 70 remains in contact with the stationary block 64, thereby maintaining a precise reference.

[0101] The amount of force may be considered to be reduced during longitudinal setting of alignment plate 26 to reduce wear.

[0102] As shown in FIG. 10, the contact surface of the rotatable fixed element 70 with the block 64 is spherical to allow for angular play.

[0103] 11 through 13 further illustrate the operation of the sheet converting machine 10 of the present invention.

[0104] In Figures 11-13, alignment plate 26 is depicted with an exaggerated skew angle in the figures for illustrative purposes.

[0105] The skew angle can be adjusted by actuating the pair of actuators 54a independently of the pair of actuators 54b, particularly at different rotational speeds.

[0106] FIG. 11 shows the sheet converting machine 10 with a sheet 14 positioned at the loading station 12 and in contact with the registration plate 26.

[0107] An extraction element 22 of the handling mechanism 20 is in a position below the sheets 14 to pick up the bottom sheet 14 of the stack.

[0108] FIG. 12 illustrates a condition of the sheet converting machine 10 where the extraction element 22 has advanced to the feed position, whereby the extraction element 22 has already extracted the bottom-most sheet 14 from the stack.

[0109] In this condition, the sheet 14 abuts against the abutment element 28 which is realigned.

[0110] When the sheet 14 is in the position shown in FIG. 12, the gripper bars 24 are capable of gripping the sheet 14 and transporting it through the processing stations of the machine.

[0111] To enable the gripper bar 24 to pull the sheet towards the transport mechanism 16, the tablet 46 is pivoted so that the abutment element 28 is lowered to clear the travel path of the sheet 14 (see FIG. 13).

[0112] FIG. 14 shows an alternative drive for the registration plate 26 which can be incorporated in the sheet converting machine 10 described with reference to FIGS.

[0113] The embodiment according to Figure 14 differs from the embodiment described according to Figures 1 to 13 in the arrangement of the actuators 54. In particular, the alignment plate 26 is movable along the handling direction by means of three actuators 54.

[0114] The actuators 54 are spaced apart transversely to the handling direction of the sheet converting machine 10 .

[0115] One actuator 54 is positioned near the operator side of the alignment plate 26 and the other actuator 54 is positioned near the opposite operator side, i.e., with a distance of less than 20 cm, in particular less than 10 cm, to the operator side, respectively.

[0116] The two actuators 54 are located at the same vertical position.

[0117] The third actuator 54 is disposed between the two actuators on the operator side and opposite the operator side, specifically on the vertical centerline of the alignment plate 26 .

[0118] The third actuator 54 is positioned at a different height than the other two actuators 54 .

[0119] The third actuator 54 supports the alignment plate 26 so as to prevent tilt of the alignment plate 26 around the horizontal axis when the alignment plate 26 moves. That is, the support mechanism 53 is realized by the third actuator 54.

[0120] The rotational speed of the third actuator 54 while moving the alignment plate 26 is adapted to the rotational speed of the further actuator 54, for example to prevent tilting of the alignment plate about a horizontal axis. Figure 15 shows an alternative drive for the alignment plate 26 according to the invention.

[0121] Instead of the third actuator 54 being located on the vertical centerline of the alignment plate 26, the drive includes a rail 90 that maintains the alignment plate 26 in an upright position. [Explanation of symbols]

[0122] 12 Loading Station 14 sheets 20 Handling Mechanism 26 Alignment plate 28 Contact element

Claims

1. A sheet processing machine (10), comprising: a transport mechanism (16) for moving the sheet (14) along a handling direction of the sheet processing machine (10); a loading station (12) for supplying a sheet (14) to be processed; an alignment plate (26) adjacent said loading station (12) for aligning sheets (14) stacked in said loading station (12) at a table level (33); a handling mechanism (20) for extracting a bottom-most sheet (14) from said stack of sheets (14), moving it through a gap (25) between said table level (33) and the bottom of said registration plate (26), and delivering it to said transfer mechanism (16); Including, the alignment plate (26) is movable in the handling direction by means of at least two linear actuators (54) arranged at a distance from each other along a direction transverse to the handling direction; A support mechanism (53) is provided that prevents the alignment plate (26) from pivoting about a horizontal axis. A sheet processing machine (10).

2. The alignment plate (26) is movable using two pairs of linear actuators (54a, 54b); The actuators (54) in each pair of actuators (54a, 54b) are vertically disposed one above the other; the drives (58a, 58b) of the pairs of actuators (54a, 54b) are configured such that the actuators (54) in each pair of actuators (54a, 54b) are driven synchronously; A sheet processing machine (10) according to claim 1.

3. 3. The sheet processing machine (10) of claim 1, wherein the actuator (54) comprises a threaded drive having a rotatable element (68) and a rotatable fixed element (70) in threaded engagement with each other.

4. Sheet processing machine (10) according to claim 3, characterized in that the rotatable fixed element (70) is fixed in particular to the machine frame (43) by two perpendicular axes (x, y).

5. 4. The sheet processing machine (10) of claim 3, wherein the rotatable fixed element (70) is fixed by means of a key and groove connection (82).

6. 6. A sheet processing machine (10) according to claim 3, wherein each pair of actuators (54a, 54b) is driven by a single motor (60) and the rotatable elements (68) of each pair of actuators (54a, 54b) are linked by a belt drive or a chain drive (55).

7. A sheet processing machine (10) according to any one of claims 3 to 5 and in addition to claim 2, wherein the rotatable element (68) of each actuator (54) is driven by a motor (60), the two motors (60) assigned to each pair of actuators (54a, 54b) being synchronized.

8. 8. A sheet converting machine (10) as claimed in any one of claims 1 to 7, wherein the alignment plate (26) includes a slider (36) at its lower end and rests with the slider (36) on a support surface (38).

9. The sheet converting machine (10) of any one of claims 1 to 8, wherein the travel distance of the alignment plate (26) is limited.

10. The sheet converting machine (10) of any one of claims 1 to 9, wherein the alignment plate (26) is guided by at least one linear guide (40).

11. 11. A sheet processing machine (10) according to any one of claims 1 to 10, comprising an abutment element (28) arranged behind the alignment plate (26) and at a fixed distance from the alignment plate (26) in relation to the handling direction for fine adjustment of the sheet (14).

12. 12. The sheet processing machine (10) of claim 11, wherein the abutment elements (28) are formed on edges of tablets (46) mounted on the registration plate (26).

13. 13. The sheet processing machine (10) of claim 12, wherein the tablet (46) is pivotally mounted to the registration plate (26), the pivot (48) being located below the table level (33) on which the sheet (14) rests.

14. A sheet processing machine (10) according to claim 12 or 13, wherein the tablet (46) has an L-shaped configuration.

15. 15. A sheet converting machine (10) as claimed in any one of claims 1 to 14, wherein the alignment plate (26) includes an integral gauge plate (50) that is height adjustable relative to the alignment plate (26) to set the gap (25).

16. 16. The sheet processing machine (10) of claim 1, further comprising a handling mechanism (20) configured to move a sheet (14) from the sheets (14) stacked in the loading station (12) for feeding the sheet (14) to the transfer mechanism (16).

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