Sheet processing machine

Abstract

A sheet processing machine includes a receiving area (38) for collecting a stack of sheets and means (36) for determining the height of the stack. The means (36) includes a manually movable first sensor element disposed on a first side (48) of the receiving area (38) and an automatically movable second sensor element (50) disposed on an opposite side (52) of the receiving area (38), such that the first and second sensor elements (50) are arranged opposite to each other along the width direction of the receiving area (38). The first and second sensor elements (50) are movable along the length direction of the sheet receiving area (38), wherein the first sensor element is one of a light emitting source and a light receiving sensor (56), and the second sensor element (50) is the other of the light emitting source and the light receiving sensor (56). The light emitting source and the light receiving sensor (56) form a grating (58) along the width direction when facing each other.

Description

Technical Field

[0001] The present invention relates to a sheet processing machine including a means for determining the height of a stack of sheets. Background Technology

[0002] Sheet processing machines, also known as conversion machines, are used in the packaging industry to process raw materials (such as cardboard, paper, or foil) into intermediate or finished products, typically in sheet form. Conversion operations can include, for example, printing, cutting, creasing, blanking, stamping, and / or folding and gluing. These individual operations are usually performed in subsequent processing stations of the sheet processing machine, where the sheet is conveyed from one processing station to the next via a transport mechanism.

[0003] Processed sheets can be collected in a designated receiving area of ​​the sheet processing machine after processing, in the form of sheet stacks (i.e., in the form of vertical stacks of sheets). It is desirable to collect processed sheets of defined batch sizes in the receiving area to streamline subsequent processing and / or logistics steps.

[0004] Because the sheets have a defined thickness, the batch size corresponds to the height of the sheet stack. To measure the height of the sheet stack, sheet processing machines known in the art may include a grating arranged at a predetermined height in the receiving area.

[0005] However, the size and shape of the sheet material being processed (e.g., blanks ejected from the sheet) vary between different sheet processing operations. Therefore, the positions of the grating components (i.e., the light emitting and receiving elements) must be carefully adjusted by the sheet processing machine technician. This adjustment process is time-consuming and typically requires many complex operations, such as opening the appropriate processing station on the sheet processing machine, operating the safety mechanisms for the operator, and removing the tools used in the processing station.

[0006] More complex detection systems (such as light curtains that include multiple gratings and monitor the entire receiving area) that do not require any additional adjustments for different sheet processing operations are too expensive for most applications. Summary of the Invention

[0007] The object of the present invention is to provide a simple and inexpensive apparatus for measuring the height of a stack of sheets, particularly suitable for measuring the height of a stack of sheets with different shapes and / or sizes.

[0008] US2005 / 0077672 discloses a system for controlling the height of a stack of sheets using a light beam. This system is used in a drawer that holds bonded sheets (which helps to hold a stack of blanks). The beam position is fixed, and the stack is raised until it cuts the beam. DE20103326U uses a similar system applied to a stack of sheets at the input of a printer.

[0009] The objective of this invention is achieved by a sheet processing machine comprising a receiving area for collecting a stack of sheets and means for determining the height of the stack. The means includes a manually movable first sensor element disposed on a first side of the receiving area and an automatically movable second sensor element disposed on the opposite side of the receiving area, such that the first and second sensor elements are arranged opposite each other along the width direction of the receiving area. The first and second sensor elements are movable along the length direction of the sheet receiving area, wherein the first sensor element is one of a light emitting source and a light receiving sensor, and the second sensor element is the other of a light emitting source and a light receiving sensor. The light emitting source and the light receiving sensor form a grating along the width direction when facing each other.

[0010] This invention is based on the idea of ​​combining a first sensor element, which is manually operated by an operator, with a second sensor element adapted to automatically adjust its position relative to the first sensor element, meaning the position of the second sensor element also does not need to be manually adjusted by the operator. This eliminates the need for the operator to manually and carefully adjust the first and second sensor elements and allows for the operation of the sheet processing machine with fewer trained personnel.

[0011] Furthermore, the sheet processing machine according to the present invention does not require complex processing operations to set up a device for determining the height of the sheet stack. Therefore, the downtime of the sheet processing machine between different sheet processing operations can be reduced.

[0012] Meanwhile, by maintaining a manually adjustable sensor element, the operator can adjust the position of the grating to suit the size and / or shape of the sheet obtained in the receiving area for sheet processing operations at hand.

[0013] Furthermore, the apparatus for determining the height of the sheet stack is simple and inexpensive, because a single grating is sufficient to reliably determine whether the sheet stack has reached the height where the grating is located.

[0014] To keep the apparatus for determining the height of the sheet stack as inexpensive and simple as possible, it is preferable to use only one light emitting element and only one light receiving sensor.

[0015] The width and length directions are perpendicular to each other.

[0016] The first sensor element and the second sensor element can be mounted on the first track and the second track, respectively. The first track and the second track are parallel to each other.

[0017] To simplify the construction of the device used to determine the height of the sheet stack, the first and second tracks can be linear tracks.

[0018] In one variation, the first sensor element is mounted by a slotted guide slider in the slotted guide of the first track. The slotted guide slider extends beyond the slotted guide so that it can be controlled by the operator of the sheet processing machine. Therefore, the position of the first sensor element can be adjusted by the operator by moving the slotted guide slider in the slotted guide to the desired position.

[0019] The second sensor element can be moved by means of a motor, or more specifically, an actuator. The motor can be connected to a second track, enabling the device for measuring the height of the sheet stack to adjust the position of the second sensor element automatically.

[0020] Preferably, the device includes a control unit connected to the first sensor element and the second sensor element. The control unit is adapted to receive sensor signals from the light receiving sensor and control the movement of the second sensor element. Therefore, the control unit is responsible for ensuring that the first and second sensor elements face each other to form a grating.

[0021] The control unit is particularly suitable for moving the second sensor element along its length to a working position, where the sensor signal is non-zero. Preferably, the sensor signal is at its maximum when the second sensor element is in the working position.

[0022] The “non-zero” sensor signal here and below indicates that the sensor signal is higher than the noise level of the corresponding optical receiving sensor.

[0023] A grating cannot be successfully formed unless the first and second sensor elements, and consequently the light emitting source and the light receiving sensor, are facing each other; that is, the light emitted by the light emitting source cannot reach the light receiving sensor. The sensor signal is expected to be at its maximum when alignment is optimal. This allows the control unit to use the sensor signal received from the light receiving sensor as a control variable when searching for the correct position of the second sensor element (i.e., the operating position for the second sensor element).

[0024] For this purpose, the control unit can be adapted to move the second sensor element along the entire length of the second track, and then move the second sensor element to the position associated with the maximum sensor signal.

[0025] Alternatively, once the sensor signal decreases from a predetermined first threshold after increasing by a predetermined second threshold, the control unit can be adapted to stop the movement of the second sensor element along the second track and to move the second sensor element back to the position before the sensor signal began to decrease. In other words, the control unit can be adapted to stop the movement of the second sensor signal after a first moment when the maximum value of the sensor signal is identified. Preferably, only a single light emission source is used, and it is not necessary to continue measuring the sensor signal at all further positions of the second sensor element along the second track.

[0026] A first threshold and a second threshold need to be selected so that random fluctuations in the sensor signal (e.g., due to noise) do not incorrectly indicate the maximum value of the sensor signal. For example, the first and second thresholds can be determined as multiples of the noise level of the light receiving sensor, such as ten times the noise level. Of course, the first and second thresholds can have the same or different values.

[0027] Furthermore, each time the first sensor element has been moved, the control unit can be adapted to move the second sensor element to the working position. In this way, it can be ensured that each time the operator manually readjusts the position of the first sensor element to conform to a new sheet processing operation, the second sensor element automatically becomes aligned to form a grating.

[0028] Furthermore, the control unit can be configured to move only the second sensor element to the working position after the first sensor element has moved a distance corresponding to a displacement threshold. This ensures that the control unit does not readjust the position of the second sensor element after minimal movement of the first sensor element (e.g., due to vibration from the sheet processing machine).

[0029] Additionally, the control unit can be adapted to move the second sensor element only when the sheet processing machine is in the setting mode.

[0030] The setup mode can be started and stopped by the operator via a human-machine interface (HMI). The HMI is particularly useful for controlling sheet processing machines and displaying information about their current status.

[0031] Preferably, the first sensor element is arranged on the operator side of the sheet processing machine, and the second sensor element is arranged on the opposite side of the operator side of the sheet processing machine. Therefore, the operator of the sheet processing machine can easily access the first sensor element, which requires manual operation, while the second sensor element, which is laborious and time-consuming for the operator to access, can be operated automatically.

[0032] The receiving area can be part of the blank separation station of a sheet processing machine, and the sheet stack can be a stack of blanks. Blanks produced by processing sheets can have a wide variety of sizes and / or shapes, making it particularly advantageous to use a device for determining the height of the sheet stack, which can be adjusted according to the blanks produced in the current sheet processing operation. Attached Figure Description

[0033] Further advantages and features will become apparent from the following description of the invention and the accompanying drawings illustrating non-limiting exemplary embodiments of the invention, wherein:

[0034] - Figure 1 A sheet processing machine according to the present invention is illustrated schematically;

[0035] - Figure 2 It shows the method for determining Figure 1 A perspective view of the device for determining the height of the sheet stack in a sheet processing machine; and

[0036] - Figure 3 It shows Figure 2 A partial side view of the device. Detailed Implementation

[0037] Figure 1 A sheet processing machine 10 is schematically shown, which enables the cutting of blanks 11 from a continuous sheet 12. These blanks 11 are typically intended to be subsequently folded and glued to form packaging boxes. However, the sheet 12 can generally be made of, for example, paper, cardboard, foil, composites thereof, or any other material commonly used in the packaging industry.

[0038] The sheet processing machine 10 includes a series of processing stations arranged in parallel but interdependent to form an integral assembly. The processing machine 10 includes a loading station 14, followed by a cutting station 16 (also commonly referred to as a stamping station), the cutting station 16 including, for example, a molding press or flatbed printing press 18 for converting the sheet 12 by cutting, a waste removal station 20 in which most of the waste portion is stripped off, a blank separation station 22 (also commonly referred to as a receiving station) for separating the blank 11 by means of a blanking tool 23 (or blanking operation), and a discharge station 24 for removing residual waste sheet from the stamped sheet 12.

[0039] The number and nature of the processing stations can vary depending on the nature and complexity of the conversion operations to be performed on sheet 12.

[0040] The sheet processing machine 10 also has a conveying mechanism 26, which in the illustrated embodiment is a conveying device, so that each sheet 12 can be moved individually from the outlet of the loading station 14 to the discharge station 24.

[0041] The conveying device uses a series of gripper bars 28, which are mounted to be movable by means of two-loop chains 30, one of which is placed laterally on each side of the sheet processing machine 10. Each loop of chain 30 travels around a ring that allows the gripper bars 28 to follow a trajectory that passes continuously through the cutting station 16, the waste removal station 20, the blank separation station 22, and the discharge station 24.

[0042] Each gripper lever 28 travels outward along a substantially horizontal plane within the channel between the driven wheel 32 and the idler wheel 34, and then along a return path at the top portion of the sheet processing machine 10. Once back to the driven wheel 32, each gripper lever 28 is then able to grip a new sheet 12 at the leading edge of the sheet 12.

[0043] exist Figure 1 In the diagram, each processing station is shown in the form of two rectangles, which symbolically represent the top and bottom portions of the sheet 12 located on each side of the moving plane.

[0044] exist Figure 1 In this system, the horizontal (or lateral), longitudinal, and vertical directions are indicated by an orthogonal spatial system (T, L, V).

[0045] The terms "upstream" and "downstream" are used in reference to... Figure 1 The direction of movement of sheet 12 in the processing direction, as indicated by the middle arrow D, is defined.

[0046] The sheet processing machine 10 further includes means 36 for determining the height of the sheet stack in the receiving area 38 of the blank separation station 22. Accordingly, in the illustrated embodiment, the sheet stack is a stack of blanks 11.

[0047] Device 36 is connected to control unit 40, for example, via an Ethernet connection, and control unit 40 is adapted to control device 36. However, device 36 can also be connected to control unit 40 via any device that provides sufficiently fast signal exchange between device 36 and control unit 40. For example, the connection can also be established wirelessly (e.g., via Wi-Fi).

[0048] The control unit 40 further includes a storage module 42.

[0049] The sheet processing machine 10 further includes a human-machine interface 44, which, in the illustrated embodiment, is a touch-sensitive display.

[0050] An operator (not shown) can control the operation of the sheet processing machine 10 via the human-machine interface 44. Furthermore, information regarding the current status of the sheet processing machine 10 can be displayed on the human-machine interface 44 to notify the operator.

[0051] exist Figure 2The image shows a perspective view of device 36.

[0052] The device 36 includes a first sensor element 46 disposed on a first side 48 of the receiving region 38 and a second sensor element 50 disposed on the opposite side 52 of the receiving region 38, such that the first sensor element 46 and the second sensor element 50 are opposite to each other along the width direction of the receiving region 38. In the illustrated embodiment, the width direction of the receiving region 38 corresponds to the lateral direction T (see [reference]). Figure 1 ).

[0053] The first sensor element 46 includes a light emitting source 54, and the second sensor element 50 includes a light receiving sensor 56.

[0054] In principle, the light emitting source 54 and the light receiving sensor 56 can also be interchanged. That is, the first sensor element 46 can also include the light receiving sensor 56, and the second sensor element 50 can include the light emitting source 54.

[0055] like Figure 2 As shown, when the light emitting source 54 and the light receiving sensor 56 face each other, a grating 58 is formed between them. Therefore, any interruption of the grating 58 can be recorded based on the sensor signal of the light receiving sensor 56.

[0056] A first sensor element 46 is mounted on a first track 60, and a second sensor element 50 is mounted on a second track 62. The first track 60 and the second track 62 are parallel to each other and parallel to the length direction of the receiving area 38, which is perpendicular to the width direction of the receiving area 38. In the illustrated embodiment, this length direction corresponds to the longitudinal direction L.

[0057] The first track 60 and the second track 62 are respectively mounted to the first frame 64 and the second frame 66. The first frame 64 and the second frame 66 are connected to the blank separation station 22. Therefore, the device 36 is suitable for retrofitting into the existing sheet processing machine 10.

[0058] In principle, the first frame 64 and the second frame 66 can also be part of the blank separation station 22, rather than part of the device 36.

[0059] Figure 3 It shows Figure 2 A side view of a selected portion of the device 36.

[0060] from Figure 3 It is evident that the first sensor element 46 is mounted by a slotted guide slider 68 in the slotted guide 70 of the first track 60. Therefore, the first sensor element 46 and thus the light emitting source 54 (see...) Figure 2 ) can be along as Figure 3The double arrow P1 indicates a shift in the length direction of the receiving area 38.

[0061] More specifically, the first sensor element 46 can be manually moved by the operator along the length of the receiving area 38, i.e., the first side 48 of the receiving area 38 is arranged on the operator side of the sheet processing machine 10, which can be easily accessed by the operator.

[0062] The second sensor element 50 includes an actuator 72, such that the second sensor element 50 moves along... Figure 3 The length direction of the receiving area 38, indicated by the double arrow P2, can be automatically shifted.

[0063] The opposite side 52 of the receiving area 38 is arranged on the operator-opposite side of the sheet processing machine 10, which is not easily accessible to the operator.

[0064] The operating modes of the sheet processing machine 10 with respect to device 36 will be discussed in more detail below.

[0065] To prepare the sheet processing machine 10 for sheet processing operations, the operator sets up the sheet processing machine in a setting mode via the human-machine interface 44. Changes to this operating mode are recorded by the control unit 40. In principle, the device 36 can also be used similarly without entering a specific setting mode.

[0066] Next, the operator manually moves the first sensor element 46 along the length of the receiving area 38 by moving the slotted guide slider 68 along the slotted guide 70 to the target position.

[0067] The target position is selected such that during the operation of the sheet processing machine 10, when the blank 11 is collected in the stack of blanks 11 in the receiving area 38 up to the target height, at least a portion of the uppermost blank 11 in the stack of blanks 11 is in the same position as the light emitting source 54 of the first sensor element 46 along the length direction of the receiving area 38.

[0068] In other words, when the blank 11 in the stack of blanks 11 does not extend substantially along the entire length of the receiving area 38, the first sensor element 46 is placed by the operator at the location where the blank 11 will appear.

[0069] The control unit 40, connected to the first sensor element 46 and the second sensor element 50, records that the first sensor element 46 has moved and begins to automatically move the second sensor element 50 along the second track 62 by controlling the actuator 72 used to find the working position of the second sensor element 50.

[0070] To determine the working position, the light receiving sensor 56 transmits its sensor signal at each position along the second track 62, where the second sensor element 46 has been moved by the control unit 40 to the second track 62.

[0071] The control unit 40 stores the received sensor signals along with their corresponding positions along the second track 62 in the storage module 42.

[0072] When the light emitting source 54 and the light receiving sensor 56 face each other, a grating 58 is formed (see Figure 2 This generates a non-zero sensor signal from the light receiving sensor 56. The better the alignment between the light emitting source 54 and the light receiving sensor 56, the higher the resulting sensor signal will be; that is, the maximum sensor signal indicates the optimal alignment between the light emitting source 54 and the light receiving sensor 56.

[0073] Therefore, the operating position is determined by the control unit 40 by identifying the position of the second sensor element 50 along the second track 62, at which the associated sensor signal received is at its maximum. Consequently, the second sensor element 50 moves to that position along the second track 62.

[0074] Then, the control unit 40 sends a message to the human-machine interface 44 to notify the operator that the device 36 has been correctly set up and the grating 58 has been successfully formed.

[0075] Therefore, the operator can change the sheet processing machine 10 from the setting mode to the operating mode, in which the sheet 12 is processed to form a blank 11, which is stacked in the receiving area 38.

[0076] During the operation of the sheet processing machine 10, the first and second sensor elements (46, 50) operate intermittently: when the sheet processing machine ejects a blank, the sensor elements temporarily stop for the time required for the blank to pass through the light barrier. For the remaining time, the light receiving sensor 56 continuously receives, or at least once every predetermined time unit (e.g., once every 50 ms), transmitting a current sensor signal to the control unit 40. Advantageously, the light receiving sensor comprises multiple sensor units arranged in a stacked manner to accurately determine the height of the uppermost blank 11.

[0077] Once the stack of blanks 11 reaches the same height as the top blank 11 and the grating 58, the grating 58 will be interrupted, and the sensor signal of the light receiving sensor 56 will drop, in particular, drop to zero or at least drop to a value corresponding to the noise level of the light receiving sensor 56.

[0078] This change in the sensor signal is recorded by the control unit 40. The control unit 40 is adapted to transmit a message to the human-machine interface 44 that the stack height of the blank 11 has reached the height of the grating of the device 36.

[0079] Preferably, the height corresponds to the target number of blanks 11, allowing the operator to stop the operation of the sheet processing machine 10 and remove the produced blanks 11 from the blank separation station 22.

[0080] In principle, once the grating 58 is interrupted, the control unit 40 can also be adapted to automatically stop the operation of the sheet processing machine.

[0081] For the next sheet processing operation, the operator can re-enter the setup mode and manually adjust the position of the first sensor element 46 (if necessary) and repeat the above process.

[0082] In the above embodiment, the device 36 for determining the height of the sheet stack is used to detect when the stack of sheet 12, and more specifically the stack of blanks 11, is stacked, which basically corresponds to determining at what point in time a certain number of blanks 11 have been produced during the operation of the sheet processing machine 10.

[0083] However, the device 36 can also be used similarly to detect when the stack of sheets 12 is removed, i.e., to detect when so many sheets 12 have been removed from the stack of sheets 12, the height of the stack of sheets being below the height of the grating 58.

[0084] The sheet processing machine according to the invention provides a particularly simple and inexpensive means of checking the height of sheet stacks. Furthermore, the operation of the sheet processing machine can be easily adjusted according to various sheet sizes and / or shapes.

Claims

1. A sheet processing machine, comprising a receiving area (38) for collecting a stack of sheets and means (36) for determining the height of the stack of sheets. The device (36) includes a manually movable first sensor element (46) disposed on a first side (48) of the receiving area (38) and an automatically movable second sensor element (50) disposed on the opposite side (52) of the receiving area (38), such that the first and second sensor elements (46, 50) are arranged opposite each other along the width direction of the receiving area (38). The first sensor element (46) and the second sensor element (50) are movable along the length of the sheet receiving area (38). The first sensor element (46) is one of the light emitting source (54) and the light receiving sensor (56), and the second sensor element (50) is the other of the light emitting source (54) and the light receiving sensor (56). When the light emitting source (54) and the light receiving sensor (56) face each other, they form a grating (58) along the width direction.

2. The sheet processing machine according to claim 1, wherein the first sensor element (46) and the second sensor element (50) are respectively mounted on the first track (60) and the second track (62).

3. The sheet processing machine according to claim 2, wherein the first sensor element (46) is mounted by a slotted guide slider (68) in a slotted guide (70) of the first track (60).

4. The sheet processing machine according to claim 1 or 2, wherein the second sensor element (50) is movable by means of a motor of the second sensor element.

5. The sheet processing machine according to claim 1 or 2, wherein the second sensor element (50) is displaceable by means of an actuator (72) of the second sensor element (50).

6. The sheet processing machine according to claim 1 or 2, wherein the device (36) includes a control unit (40) connected to the first sensor element (46) and the second sensor element (50), the control unit (40) being adapted to receive sensor signals from the light receiving sensor (56) and control the movement of the second sensor element (50).

7. The sheet processing machine according to claim 6, wherein the control unit (40) is adapted to move the second sensor element (50) along the length direction to a working position, wherein the sensor signal is non-zero in the working position.

8. The sheet processing machine according to claim 7, wherein the sensor signal is at its maximum at the working position.

9. The sheet processing machine according to claim 7, wherein the control unit (40) is adapted to move the second sensor element (50) to the working position each time the first sensor element (46) is moved.

10. The sheet processing machine according to claim 1 or 2, wherein the first sensor element (46) is arranged on the operator side of the sheet processing machine (10), and the second sensor element (50) is arranged on the operator-opposite side of the sheet processing machine (10).

11. The sheet processing machine according to claim 1 or 2, wherein the receiving area (38) is part of the blank separation station (22) of the sheet processing machine (10), and the sheet stack is a stack of blanks (11).

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