Sheet processing machine

Abstract

The sheet converting machine (10) has an apparatus (44) for monitoring the sheets (12) and a transport mechanism (26) for moving the sheets (12) along a handle direction through the sheet converting machine (10). The apparatus (44) includes a light emitting element that forms a light barrier in the sheet path between the light emitting element and the light receiving element. A control unit (46) is connected to the light receiving element and is adapted to record each sheet (12) passing through the sheet path.

Description

Technical Field

[0001] The present invention relates to a sheet processing machine having a device for monitoring a sheet.

Background Art

[0002] A sheet processing machine, also known as a converter, is used in the packaging industry to process raw materials such as cardboard, paper, or foil, typically in the form of sheets, into intermediate or final products. The conversion process can include, for example, printing, cutting, folding, punching, stamping, and / or folding and gluing. Typically, the individual steps are performed at successive processing stations of the sheet processing machine while the sheet is transported by a transport mechanism from one processing station to the next. The sheets can be stacked vertically and collected after conversion in a designated stacking area of the sheet processing machine.

[0003] Modern sheet processing machines enable a high throughput of sheets. However, not only the processing speed but also the quality of the processing steps are relevant parameters in the packaging industry. For example, the punching step involves separating a cut in the sheet by a punching tool, and the cut is formed in a previous processing step. If the alignment of the punching tool is not sufficient and / or the cut is not formed in a sufficiently accurate manner, a distorted shape can appear in the blank pushed out from the sheet. Furthermore, there is also the possibility that the blank is not pushed out of the sheet at all. Therefore, there is a need for means to check the state of the processes of the sheet processing machine.

[0004] WO 2018 / 175644 discloses a method of measuring characteristics of a sheet, such as dimensions, position, or orientation, by means of a plurality of sheet sensors.

[0005] European Patent Application Publication No. 2886498 describes a sheet processing apparatus comprising an inspection section for inspecting sheets and a cutting section for cutting sheets based on the inspection results in the inspection section. The apparatus may include a plurality of optical sensors and an array of optical sensors. If the number of sheets detected in the detection section does not match the number of sheets cut, any acquired count value is assumed to be "abnormal" and processing is stopped.

[0006] In U.S. Patent Application Publication No. 2019 / 0144224, a sheet processing converter is configured to measure the forward position of registration marks printed on a sheet, which are used to detect the alignment of the front lateral edge. Furthermore, an additional “pre-correction sensor” is used to detect the passage of the front lateral edge. The alignment information is then used to control an actuator module that moves the grip elements of a grip bar to find the optimal grip position so that any placement errors are corrected. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2018 / 175644 [Patent Document 2] European Patent Application Publication No. 2886498 [Patent Document 3] U.S. Patent Application Publication No. 2019 / 0144224 [Overview of the project] [Problems that the invention aims to solve]

[0008] The object of the present invention is to provide a means for monitoring sheets in a sheet processing machine. [Means for solving the problem]

[0009] The object of the present invention is solved by a sheet processing machine having a device for monitoring sheets and a conveying mechanism for transporting sheets along the handling direction within the sheet processing machine. The device comprises a light-emitting element, which forms a light barrier in the sheet passage between the light-emitting element and a light-receiving element. A control unit is connected to the light-receiving element and controls each sheet passing through the sheet passage. Registration It is configured to do so.

[0010] The present invention is based on the idea that sheets passing through a sheet passage block or at least attenuate the light emitted by light-emitting elements, that is, the sheets block or attenuate a light barrier. This blocking or attenuation is controlled by a control unit that controls each sheet passing through the sheet passage. Registration It can be detected by a light-receiving element, making it possible to draw conclusions about the process of the sheet processing machine.

[0011] Preferably, the light barrier formed within the sheet passage by the light-emitting and light-receiving elements is a light curtain. For example, the light-emitting element may comprise a plurality of individual light sources, and the light-receiving element may comprise a plurality of light-receiving sensors, each of which is associated with one of the light sources.

[0012] Depending on the number of light sources and light-receiving sensors, the dimensions of the seat aisles, and the space between the relevant pairs of light sources and light-receiving sensors, a light curtain can essentially become a continuous light curtain.

[0013] To enhance the reliability of the equipment for monitoring the seats, the light curtain may extend to at least 80% of the width of the seat aisle, and more particularly, to at least 90% of the width of the seat aisle. Preferably, the light curtain is controlled by the control unit. Registration To ensure that the sheets cannot pass through the aisle without being processed, the device essentially extends across the entire width of the aisle. Furthermore, these modifications allow for the use of similar devices to monitor sheets being processed over a wider range of dimensions.

[0014] In one modification, the light-receiving element may be configured to measure light intensity.

[0015] In other words, the light-receiving element can detect any attenuation of the light emitted by the light-emitting element, meaning that the light-receiving element can provide information with subtle differences beyond simple YES / NO detection.

[0016] This modification is particularly useful when the sheet is at least partially transparent, for example, based on the sheet's thickness and / or the type of material it is made of, allowing light to pass through the sheet but attenuating it based on the sheet's transparency.

[0017] In one modification, the light-receiving element and the light-emitting element are mounted on a first rail and a second rail, respectively. The first and second rails can restrict the sheet passage. Furthermore, the first and second rails may have at least one mounting point for incorporating a device for monitoring the sheet within an existing sheet processing machine.

[0018] To provide a simple configuration for aligning light-emitting and light-receiving elements, the first and second rails may be parallel to each other. Such a configuration is particularly advantageous when multiple light-emitting and light-receiving sensors must be carefully aligned.

[0019] The control unit particularly includes a storage module for storing information about the sheet and / or the sheet processing machine.

[0020] For example, the expected number of sheets can be stored in the control unit's memory module, and the expected number is determined based on the number of sheets supplied to the filling station of the sheet processing machine and / or the number of sheets taken from the filling station. In this variation, the control unit is adapted to compare the number of sheets currently passing through the sheet aisle with the expected number of sheets.

[0021] In other words, the control unit can be adapted to be provided at the filling station and to confirm that all sheets that have already been taken from the filling station have each passed through a device for monitoring the sheets.

[0022] The expected number of sheets can be the absolute number of sheets and / or the number of sheets per unit of time, for example, the number of sheets per second. Therefore, the value of the expected number of sheets can be selected to be most appropriate for the type of sheet processing operation currently being performed by the sheet processing machine.

[0023] Additionally, the transparency of the sheet can be stored as information about the sheet in the storage module of the control unit.

[0024] When the light receiving element can measure the light intensity, the transparency of the sheet can be used to determine whether the light barrier is blocked or not based on a threshold value. In other words, when the light intensity detected by the light receiving element is below the threshold value but not zero, the control unit can still count this measurement value as blocked light transmission.

[0025] The threshold value can also be stored in the storage module of the control unit.

[0026] Furthermore, the target shape of the sheet can be stored in the storage module of the control unit.

[0027] The target shape can be determined based on a reference sheet passing through the sheet path. The reference sheet can be passed through the sheet path by the operator of the sheet processing machine before the actual sheet is processed. Thus, the signal sequence received by the control unit corresponds to the shape of the reference sheet for which the target shape can be calculated by the control unit and stored in the storage module.

[0028] Similarly, the reference sheet can be automatically determined to be the last sheet scanned during the sheet processing machine setup before each processing operation begins. Therefore, in this modification, it is not necessary for the reference sheet to be manually passed through the sheet aisle by the operator.

[0029] In further modifications, the reference sheet information may be provided in a file format stored in the control unit's memory module, such as a PDF file. The file may be transmitted to the machine via a remote computer connected to the machine, such as a cloud computer. To perform analysis from the shapes contained in the file, the control unit may determine, for each reading of the light-receiving element, whether the light is completely blocked, partially blocked, or not blocked by a sheet having the expected shape. Blocking means that, regardless of the sheet's transparency, the sheet completely covers the sensor when the reading is taken.

[0030] In other words, as long as the control unit has access to the information necessary to compare the target shape with the sheet, there is no need to actually pass the reference sheet through the sheet aisle and take additional measurements to determine the target shape. In this case, it also allows for the target shape to be substantially designed in advance without actually having to produce the reference sheet.

[0031] The target shape particularly includes the target dimensions and / or target outline of the sheet. The target dimensions particularly include the total length, width, and height of the sheet, while the target outline particularly indicates the transition of the sheet's edges. Furthermore, the outline may include surface information of the sheet, such as cutouts, notches, perforations, and / or folds.

[0032] Furthermore, the target shape may include the transparency of the reference sheet. This makes it possible to set a threshold based on the transparency of the reference sheet.

[0033] To provide the sheet processing machine operator with information about the current status of the sheet processing machine, the sheet processing machine may be equipped with a human-machine interface connected to a control unit, such as a touch-sensitive display.

[0034] The control unit may be adapted to send a warning message to the sheet processing machine's human-machine interface if the current number of sheets is lower than the expected number. Such problems can occur if sheets jam in any processing station of the sheet processing machine and / or if the sheet processing machine does not operate at the intended processing speed. The operator can then be notified by a warning message appearing on the human-machine interface, allowing the operator to intervene as needed.

[0035] In particular, a warning message is sent to the human-machine interface if there are no sheets in the filling station of the sheet processing machine. In this case, the warning message can also become an error message, which is displayed more prominently on the human-machine interface than the warning message. For example, an error message can prevent further operation of the sheet processing machine until it is clearly recognized by the sheet processing machine operator, for example, through operator confirmation.

[0036] Similarly, the control unit may be adapted to send a warning message to the human-machine interface if the target shape of at least one sheet does not match the target shape. Thus, the operator may be notified by a warning message displayed on the human-machine interface that at least one sheet was not obtained in the target shape, for example, if the sheet is damaged and / or at least one blank was not properly extruded from the sheet.

[0037] Furthermore, the control unit can store the count of at least one sheet that does not match the target shape and can transmit this count to a human-machine interface so that the operator can identify the at least one potentially incorrect sheet.

[0038] Furthermore, if a predetermined number of sheets are found not to match the target shape, an error message may be sent to the human-machine interface. This predetermined number may be set to indicate a defective processing station in the sheet processing machine. Therefore, the operator receiving each error message can decide to shut down the sheet processing machine to minimize waste resulting from the delayed use of a malfunctioning sheet processing machine.

[0039] The sheet processing machine can also be automatically stopped when the stop criteria are detected by the control unit.

[0040] The stopping criterion may be a predetermined large deviation from the target shape, for example, a deviation that indicates that there is no longer a blank that should not have been removed at a predetermined position in the device for monitoring the sheet.

[0041] In such cases, the lost material is likely to become lodged inside the sheet processing machine, increasing the risk of damage to the machine and resulting in unwanted downtime. Stopping the machine based on the stopping criteria will at least mitigate the risk of damage to the sheet processing machine.

[0042] In other words, a device for monitoring sheets can serve not only as a security device but also as a quality control device.

[0043] A device for monitoring the sheet may be placed between the waste removal station and the blank separation station of the sheet processing machine. This makes it possible to verify whether the blanks pre-formed in the sheet have been properly prepared in the blank separation station to obtain the blanks, for example, whether any waste portions have been properly removed and whether the blanks are in the correct shape and / or position within the sheet.

[0044] The sheet is preferably made of paper, cardboard, foil, or a composite material thereof.

[0045] Further advantages and features will become apparent from the following description of the present invention and from the accompanying drawings illustrating non-limiting exemplary embodiments of the present invention. [Brief explanation of the drawing]

[0046] [Figure 1] A schematic diagram of the sheet processing machine according to the present invention is shown. [Figure 2] Figure 1 shows a schematic plan view of the sheet processed by the sheet processing machine. [Figure 3] Figure 1 shows a perspective view of the device for monitoring the sheets of the sheet processing machine. [Modes for carrying out the invention]

[0047] Figure 1 schematically shows a sheet processing machine 10 that enables cutting blanks 11 (see Figure 2) from a series of sheets 12. These blanks are then typically intended to be folded and glued to form packaging boxes. However, the sheets 12 may generally be made of, for example, paper, cardboard, foil, composites thereof, or other materials commonly used in the packaging industry.

[0048] The sheet processing machine 10 comprises a series of processing stations that are juxtaposed but independent of each other in order to form a single assembly. The processing machine 10 includes a filling station 14, followed by a cutting station 16 (usually also called a punching station) which includes, for example, a die or platen press 18 into which the sheet 12 is deformed by cutting; a waste removal station 20 from which most of the waste material is removed; a blank separation station 22 (usually also called a receiving station) for separating (or punching) the blank 11 using a punching tool 23; and a removal station 24 for removing the remaining waste sheet 25 (see Figure 2) of the punched sheet 12.

[0049] The number and nature of processing stations may vary depending on the nature and complexity of the conversion process performed on sheet 12.

[0050] The sheet processing machine 10 also has a conveying mechanism 26, which in the shown embodiment is a conveyor that allows each sheet 12 to be moved individually from the outlet of the filling station 14 to the removal station 24.

[0051] The conveyor uses a series of gripper bars 28, which are mounted so as to be movable by two links of a chain 30, one on each side of the sheet processing machine 10, which are positioned laterally. Each link of the chain 30 moves around a link that allows the gripper bar 28 to follow a trajectory that passes through the cutting station 16, the waste removal station 20, the blank separation station 22, and the removal station 24 in succession.

[0052] Each gripper bar 28 travels forward on a substantially horizontal plane in the passage between the drive wheel 32 and the idler wheel 34, and then travels back over the top of the sheeting machine 10. Returning to the drive wheel 32, each gripper bar 28 is then able to grip the new sheet 12 at the leading edge of the sheet 12.

[0053] In Figure 1, each processing station is represented by two rectangles, one representing the top and the other the bottom of the processing machine located on either side of the moving surface of the sheet 12.

[0054] In Figure 1, the horizontal (or left-right), longitudinal, and vertical directions are represented by an orthogonal spatial system (T, L, V).

[0055] The terms "upstream" and "downstream" are defined in relation to the direction of movement of the sheet 12 in the handling direction, as indicated by arrow D in Figure 1.

[0056] Figure 2 shows the current state and shape of the sheet 12 being processed by the sheet processing machine 10 (see Figure 1), and the plan view of the sheet 12 is arranged according to the series of stations of the sheet processing machine 10 in Figure 1.

[0057] At the filling station 14, the sheet 12 is provided as a flat sheet having rectangular or square surfaces.

[0058] At the cutting station 16, the shape of the blank 11 is prepared by forming weakened lines 38 within the sheet 12, for example, by a series of cuts and / or perforations.

[0059] At the waste removal station 20, as shown in the shaded area of ​​Figure 2, the selected portion of the sheet 12 is cut out and discharged from the sheet 12.

[0060] Finally, the blanks 11 are separated from the sheet 12 at the blank separation station 22, and in the shown embodiment, two cross-shaped blanks 11 having a central opening 42 are obtained from the sheet 12.

[0061] The remaining portion of sheet 12, i.e., the remaining waste sheet 25, is removed at the disposal station 24.

[0062] Of course, the order shown in Figure 2 is merely illustrative. Different shapes and dimensions of the sheet 12 and / or blank 11 may be used and formed by the sheet processing machine 10, depending on the type of use of the sheet 12 and the processing station provided by the sheet processing machine 10.

[0063] Returning to Figure 1, the sheet processing machine 10 is further equipped with a device 44 for monitoring the sheets 12 being transported downstream from the waste removal station 20 to the blank separation station 22 by the transport mechanism 26.

[0064] In principle, the device 44 may be positioned between any two processing stations of the sheet processing machine 10, depending on which current condition of the sheet 12 is most important and / or most appropriate, in order to monitor the precise operation of the sheet processing machine 10.

[0065] Device 44 is connected to the control unit 46, for example, by an Ethernet connection. However, device 44 can also be connected to the control unit 46 by any means that provides a sufficiently fast exchange of signals between device 44 and the control unit 46. For example, such a connection can be established wirelessly, such as Wi-Fi.

[0066] The control unit 46 includes a memory module 48 in which the number of sheets 12 provided at the filling station 14 and the processing speed, i.e., the number of sheets 12 processed per second by the sheet processing machine 10, are stored.

[0067] In the shown embodiment, the control unit 46 is further connected to a human-machine interface 50, which is a touch-sensitive display. The human-machine interface 50 allows an operator (not shown) of the sheet processing machine 10 to know the current status of the sheet processing machine 10 and to control the operation of the sheet processing machine 10.

[0068] In Figure 3, the device 44 for monitoring sheet 12 is shown in a perspective view.

[0069] The apparatus 44 comprises a first rail 52 and a second rail 54, the first rail 52 having an integrated (i.e., not clearly shown) light-emitting element and the second rail 54 having an integrated (i.e., not clearly shown) light-receiving element. The light-emitting element has a number of light sources, in particular a number of laser light spots, while the light-receiving element has a number of light-receiving sensors, each of which is associated with one light source. This configuration leads to a basically continuous light curtain 56 between the first rail 52 and the second rail 54.

[0070] The first rail 52 is attached to the frame 58 of the blank separation station 22 by several mounting points 60—only one of which is shown in Figure 3—and the light curtain 56 is positioned within the seat passage 62.

[0071] As can be seen in Figure 3, the light curtain 56 extends along the lateral direction T, covering most of the width of the seat aisle 62. In particular, the light curtain 56 extends to at least 80% or at least 90% of the width of the seat aisle 62. In principle, the light curtain 56 can also extend to the entire width of the seat aisle 62.

[0072] The operating modes of the sheet processing machine 10 with respect to the device 44 will be described in more detail below.

[0073] As described above, the sheet processing machine 10 is used to convert the stacks of sheets 12. More specifically, the sheet processing machine 10 is used to cut blanks 11 from sheets 12.

[0074] The device 44 for monitoring the sheets 12 is used to provide feedback to determine whether the sheet processing machine 10 is functioning correctly, that is, whether all sheets 12 supplied to the filling station 14 are processed and all produced blanks 11 are of the correct shape.

[0075] For this purpose, the filling station 14 is connected to a control unit 46, and the filling station 14 transmits to the control unit 46 the total number of sheets 12 provided into the filling station 14. The total number of sheets 12 can also be provided by the operator of the sheet processing machine 10 via the human-machine interface 50. The control unit 46 stores the total number of sheets 12 in a memory module 48.

[0076] Furthermore, before processing the sheet 12, the operator provides a reference sheet that passes through the sheet passage 62. The reference sheet corresponds to the desired form of the sheet 12 after passing through the waste removal station 20 and before entering the blank separation station 22 (see Figure 3). To provide the reference sheet, the sheet processing machine 10 may have additional (not shown) operator access in the processing station upstream of the sheet monitoring device 44, i.e., within the waste removal station 20 in the shown embodiment.

[0077] The control unit 46 records the signal sequence received from the light-receiving element of the device 44 as the reference sheet passes through the sheet passage 62, and also stores the signal sequence in the memory module 48 for reference. Based on this signal sequence, the control unit 46 calculates the target dimensions and / or target outline of the sheet 12.

[0078] Additionally, the control unit 46 can store machine information about the sheet processing machine 10 in the memory module 48, such as the target processing speed of the sheet processing machine 10 in terms of the number of sheets per second. The machine information can also be set by the operator via the human-machine interface 50.

[0079] As soon as the processing work to convert the sheets 12 begins, the control unit 46 controls each sheet 12 passing through the device 44, more specifically, through the sheet passage 62. Registration do. Registration This includes counting the sheets 12 passing through the device 4 to obtain the current number of sheets 12, and comparing the signal array provided by the light-receiving element of each passing sheet 12, which corresponds to the shape of each sheet 12, with a signal array stored in the memory module 48, i.e., the target shape.

[0080] Alternatively, the control unit 46 may use a reference file to calculate a reference signal sequence received from the light-receiving element of the apparatus 44 as the sheet 12 passes through the sheet passage 62. To do this, based on the target shape of the sheet 12, the control unit determines for each reading of the light-receiving element whether the light is completely blocked, partially blocked, or not blocked at all by the sheet 12 having the correct shape. The transparency level, i.e., the light intensity detected by the light-receiving element when the light is completely blocked by the sheet, may be calculated from the mean, median, or any appropriate statistical value of a set of readings from which the light is completely blocked from the first sheet of the processing operation or from the first few sheets.

[0081] Preferably, during analysis using a reference file, the control unit may ignore readings partially blocked by the sheet and use only readings that are either completely blocked or not blocked at all. Alternatively, the control unit may decide to assign a target value to each reading of an individual light-receiving element, depending on its position and time, and the percentage of light blocked by the sheet. This target value may then be compared to the actual readings during evaluation. This last alternative may preferably be used when the field of view of the light-receiving element is greater than the waste (i.e., the portion of the sheet removed by the machine), thereby enabling quality control despite a coarse arrangement of light-receiving elements.

[0082] The control unit 46 is adapted to calculate the expected number of sheets 12 based on the number of sheets 12 initially supplied to the filling station 14 and the number of sheets 12 already taken from the filling station 14. For this purpose, the filling station 14 transmits the number of sheets 12 already taken from the filling station 14 to the control unit 46.

[0083] The control unit 46 compares the expected number of sheets 12 with the current number of sheets 12 in a essentially continuous manner. If the current number of sheets 12 is less than the expected number of sheets 12, the control unit 46 sends a warning message to the human-machine interface 50 to inform the operator of the sheet processing machine 10 that there may be a problem with the operation of the sheet processing machine 10. For example, one sheet 12 may get stuck inside the waste removal station 20 instead of being delivered to the blank separation station 22.

[0084] If sheet 12 is no longer present in the filling station 14 and the number of sheets 12 is still less than the expected number of sheets 12, the control unit 46 can send an error message to the human-machine interface 50.

[0085] Error messages can be made more visually prominent than warning messages to ensure that operators cannot ignore the discrepancy in the numbers on sheet 12.

[0086] Furthermore, if the control unit 46 claims that the shape of at least one sheet 12 does not match the target shape stored in the memory module 48, the control unit 46 sends a warning message to the human-machine interface 50 to inform the operator that the blank 11 coming from the sheet 12 does not have the desired shape or has not been extruded properly from the sheet 12.

[0087] Furthermore, the control unit 46 can also transmit the current number of sheets 12 in the resulting pile of blanks 11 produced by the sheet processing machine 10 and collected in the blank separation station 22, so that the operator can easily identify the blanks 11.

[0088] Therefore, the sheet processing machine 10 according to the present invention provides a simple and reliable device for monitoring the precise processing of the sheet 12 in the sheet processing machine 10. In this way, any unexpected situations during the production of the blank 11, such as damage to the blank 11 or loss of the sheet 12, can be identified in order to ensure the high quality of the blank 11 and to minimize the waste produced by the sheet processing machine 10 and its downtime.

Claims

1. A sheet processing machine having a device (44) for monitoring the sheet (12) and a transport mechanism (26) for moving the sheet (12) inside the sheet processing machine (10) along the handling direction, The aforementioned device (44) is A light-emitting element and a light-receiving element, wherein the light-receiving element is assigned to the light-emitting element, and the light-emitting element and the light-receiving element form a light barrier within the sheet passage (62) between the light-emitting element and the light-receiving element, The control unit (46) is connected to the light-receiving element and is adapted to align each sheet (12) passing through the sheet passage (62), The control unit (46) includes a storage module (48) for storing information about the sheet (12), The aforementioned information includes a predetermined target shape of the sheet (12), The registration of each sheet includes comparing the signal array provided by the light-receiving element of each sheet (12) passing through with the target shape of the sheet (12) to perform the registration. A sheet processing machine characterized by the following features.

2. The sheet processing machine according to claim 1, wherein the light barrier formed within the sheet passage (62) by the light-emitting element and the light-receiving element is a light curtain (56).

3. The sheet processing machine according to claim 2, wherein the light curtain (56) extends to at least 80% of the width of the sheet passage (62).

4. The sheet processing machine according to claim 1, wherein the light-receiving element and the light-emitting element are attached to the first rail (52) and the second rail (54), respectively.

5. The sheet processing machine according to claim 4, wherein the first rail (52) and the second rail (54) are parallel to each other.

6. A sheet processing machine according to claim 1, wherein an expected number of sheets (12) is stored in the memory module (48) of the control unit (46), the expected number is determined based on the number of sheets (12) provided into the filling station (14) of the sheet processing machine (10) and / or the number of sheets (12) taken from the filling station (14), and the control unit (46) is adapted to compare the current number of sheets (12) that have passed through the sheet passage (62) with the expected number of sheets (12).

7. The sheet processing machine according to claim 1, wherein the target shape of the sheet (12) is determined based on a reference sheet that has passed through the sheet passage (62).

8. The sheet processing machine according to claim 1, wherein the target shape of the sheet (12) is determined by the control unit (46) based on a reference file transmitted from a remote computer to the sheet processing machine.

9. The sheet processing machine according to claim 7 or 8, wherein the target shape includes the target dimensions of the sheet (12) and / or the target outer shape of the sheet (12).

10. The sheet processing machine (10) is further comprising a human-machine interface 50 connected to the control unit (46), as described in claim 1.

11. The sheet processing machine according to claim 10, wherein the control unit (46) is adapted to send a warning message to the human-machine interface (50) of the sheet processing machine (10) if the current number of sheets (12) is less than the expected number of sheets (12) or if there are no more sheets (12) in the filling station (14).

12. The sheet processing machine according to claim 10 or 11, wherein the control unit (46) is configured to send a warning message to the human-machine interface (50) if the target shape of at least one sheet (12) does not match the target shape.

13. The sheet processing machine according to claim 1, wherein the device for monitoring the sheet (12) is located between the waste removal station (20) and the blank separation station (22) of the sheet processing machine (10).

14. The sheet processing machine according to claim 1, wherein the sheet (12) is made of paper, cardboard, foil, or a composite material thereof.

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