Sheet material processing machine

Abstract

The sheet material processing machine has a receiving area (38) where a pile of sheet material is collected and a device (36) for determining the height of the pile of sheet material. The device (36) has a manually displaceable first sensor element (46) arranged at a first side (48) of the receiving area (38) and an automatically displaceable second sensor element (50) arranged at an 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 of the receiving area (38). The first sensor element (46) and the second sensor element (50) are displaceable along the length of the sheet material receiving area (38). The first sensor element (46) is one of a light emitting source (54) and a 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). The light emitting source (54) and the light receiving sensor (56) form a light barrier (58) along the width direction when facing each other.

Description

[Technical Field]

[0001] The present invention relates to a sheet material processing machine having a device for determining the height of a sheet material pile. [Background technology]

[0002] Sheet material converting machines, also known as converting machines, are used in the packaging industry to convert raw materials such as cardboard, paper, or foil into intermediate or finished products typically in the form of sheet material. Converting operations may include, for example, printing, cutting, creasing, blanking, foil stamping, and / or folding-gluing. Typically, individual operations are performed in successive converting stations on the sheet material converting machine, with the sheet material being transported from one converting station to the next by a transport mechanism.

[0003] After processing in a designated receiving area of ​​a sheet material processing machine, the processed sheet material may be collected in a sheet material pile, i.e., a vertical stack of sheet material. It is desirable to collect defined batch sizes of processed sheet material in the receiving area to simplify subsequent handling and / or logistics steps.

[0004] Since the sheet material has a defined thickness, the batch size corresponds to the height of the sheet material pile. To measure the height of the sheet material pile, sheet material processing machines known in the art may have a light barrier located at a predetermined height in the receiving area.

[0005] However, the dimensions and shapes of processed sheets, e.g., blanks extruded from the sheets, vary between different sheet processing jobs. Therefore, the positions of the light barrier components, i.e., the light emitting and receiving elements, must be carefully adjusted by a skilled operator of the sheet processing machine. This adjustment process is time-consuming and typically requires complex handling operations, such as opening the corresponding processing station of the sheet processing machine, handling safety mechanisms for the operator, and removing tools used at the processing station.

[0006] Any additional adjustments for different sheet processing jobs, such as more complex detection systems that do not require light curtains consisting of multiple light barriers and monitoring the entire receiving area, are too expensive for most applications.

[0007] U.S. Patent Application Publication No. 2005 / 0077672 discloses a system for controlling the height of a stack of sheet material using a light beam. This system is used in a drawer containing binder sheet material (which helps to store the stack of blanks). Because the position of the light beam is fixed, the stack is raised until it breaks the light beam. German Utility Model No. 20103326(U) uses a similar system applied to a stack of sheet material located at the input of a printer. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US Patent Application Publication No. 2005 / 0077672 [Patent Document 2] German Utility Model No. 20103326(U) Summary of the Invention [Problem to be solved by the invention]

[0009] It is an object of the present invention to provide a simple and inexpensive means for measuring the height of a pile of sheet material, in particular a means suitable for measuring the height of a pile of sheet material with respect to sheets of different shapes and / or sizes. [Means for solving the problem]

[0010] The object of the present invention is achieved by a sheet material processing machine having a receiving area for collecting a pile of sheet material and a device for determining the height of the pile of sheet material. The device has a manually displaceable first sensor element located on a first side of the receiving area and an automatically displaceable second sensor element located on the opposite side of the receiving area, the first and second sensor elements being arranged opposite each other along the width direction of the receiving area. The first and second sensor elements are displaceable along the length direction of the sheet material receiving area, the first sensor element being one of a light emitting source and a light receiving sensor, and the second sensor element being the other of the light emitting source and the light receiving sensor. When the light emitting source and the light receiving sensor are facing each other, they form a light barrier along the width direction.

[0011] The invention is based on the technical idea of ​​combining a first sensor element that is manually handled by an operator with a second sensor element that automatically adapts its position to the first, i.e. the position of the second sensor element does not have to be adjusted manually by the operator as well, thereby making it possible to operate the sheet material processing machine even by less skilled personnel without the need for careful manual adjustment of the first and second sensor elements by the operator.

[0012] Furthermore, the sheet material processing machine of the present invention does not require complex handling procedures for setting up a device to determine the height of the sheet material pile, thereby reducing downtime of the sheet material processing machine between different sheet material processing jobs.

[0013] At the same time, by maintaining a manually adjustable sensor element, the operator can adjust the position of the light barrier to suit the size and / or shape of the sheet material currently available in the receiving bin for the sheet material processing job.

[0014] Furthermore, the device for determining the height of the sheet material pile is simple and inexpensive to construct, since a single light barrier is sufficient to reliably determine whether the sheet material pile has reached the height at which the light barrier is located.

[0015] In order to keep the device for determining the height of the sheet material pile as cheap and simple in construction as possible, preferably only one light emitting element and one light receiving sensor are used.

[0016] The width direction and the length direction are in particular perpendicular to each other.

[0017] The first and second sensor elements may be mounted on a first rail and a second rail, respectively, which are in particular parallel to each other.

[0018] To simplify the height configuration that determines the height of the sheet material pile, the first rail and the second rail may be straight rails.

[0019] In one embodiment, the first sensor element is mounted by a slotted guide slider provided within a slotted guide of the first rail, the slotted guide slider extending from the slotted guide for control by an operator of the sheet material processing machine, and the position of the first sensor element can thus be adjusted by the operator by moving the slotted guide slider within the slotted guide to a desired position.

[0020] The second sensor element may be displaceable by a second sensor element motor, in particular a second sensor element actuator, which may be coupled to the second rail, so that the device for measuring the height of a sheet material pile can automatically adjust the position of the second sensor element.

[0021] Preferably, the device comprises a control unit connected to the first sensor element and to the second sensor element, the control unit being adapted to receive the sensor signal from the light-receiving sensor and to control the movement of the second sensor element, such that the control unit is operable to cause the first sensor element and the second sensor element to face each other to form a light barrier.

[0022] The control unit is particularly adapted to move the second sensor element along the length to a working position in which the sensor signal is non-zero. Preferably, the sensor signal is at a maximum when the second sensor element is in the working position.

[0023] A "non-zero" sensor signal here, and also below, means that the sensor signal is above the noise level of the corresponding light-receiving sensor.

[0024] Unless the first and second sensor elements, and thus the light source and the light receiving sensor, are facing each other, a light barrier cannot be successfully formed, i.e., the light emitted by the light source cannot reach the light receiving sensor. When the alignment is optimal, the sensor signal is expected to be maximum. This allows the control unit to use the sensor signal received from the light receiving sensor as a control variable when searching for the exact position of the second sensor element, i.e., the working position of the second sensor element.

[0025] For this purpose, the control unit may be adapted to move the second sensor element along the entire length of the second rail and then move the second sensor element to a position associated with a maximum sensor signal.

[0026] Alternatively, the control unit may be configured to stop movement of the second sensor element along the second rail as soon as the sensor signal increases by a predetermined second threshold and then decreases by a predetermined first threshold, and return the second sensor element to the position before the sensor signal began to decrease. In other words, the control unit may be configured to stop movement of the second sensor element after first identifying a maximum value of the sensor signal. Preferably, since only a single light source is used, it is not necessary to continue measuring the sensor signal for all subsequent positions of the second sensor element along the second rail.

[0027] The first and second thresholds should be selected so that random fluctuations in the sensor signal, e.g., due to noise, do not falsely 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, e.g., 10 times the noise level. Of course, the first and second thresholds can have the same value or different values.

[0028] Furthermore, the control unit may be adapted to move the second sensor element into its working position each time the first sensor element is moved, so that the second sensor element is automatically aligned to form the light barrier each time an operator manually readjusts the position of the first sensor element to match a new sheet material processing job.

[0029] Additionally, the control unit may be configured to only move the second sensor element to the working position after the first sensor element has moved a distance corresponding to the displacement threshold, thereby avoiding the control unit having to readjust the position of the second sensor element after minimal movement of the first sensor element due to, for example, vibrations of the sheet material processing machine.

[0030] Additionally, the control unit may be adapted to activate the second sensor element only when the sheet material processing machine is in a set-up mode.

[0031] The setup mode can be initiated and terminated by the operator via a human machine interface, which may be used, inter alia, to control the sheet material processing machine and to display information about the current status of the sheet material processing machine.

[0032] Preferably, the first sensor element is located on an operator's side of the sheet material processing machine and the second sensor element is located on an opposite operator's side of the sheet material processing machine, so that the operator of the sheet material processing machine can easily access the first sensor element, which must be handled manually, while the second sensor element, which is more cumbersome and time-consuming for the operator to access, can be handled automatically.

[0033] The receiving area may be part of a blank separation station of a sheet material processing machine and the sheet material pile may be a pile of blanks. The blanks made by processing the sheet material may have a wide range of sizes and / or shapes, so that it is particularly advantageous to have an apparatus for determining the height of the sheet material pile that is adjustable to suit the blanks made in a current sheet material processing job.

[0034] Further advantages and features will become apparent from the following description of the invention and the accompanying drawings, which show non-limiting exemplary embodiments of the invention. [Brief explanation of the drawings]

[0035] [Figure 1] 1 is a diagrammatic view of a sheet material processing machine according to the present invention; [Figure 2] 2 is a perspective view of an apparatus for determining the height of a pile of sheet material in the sheet material processing machine of FIG. 1; FIG. [Figure 3] FIG. 3 is a partial side view of the device of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0036] 1 shows diagrammatically a sheet material processing machine 10 which enables blanks 11 to be cut from a continuous sheet material 12. These blanks 11 are typically intended to be later folded and joined to form a packaging box. However, the sheet material 12 may generally be made of, for example, paper, cardboard, foil, a composite thereof, or any other material routinely used in the packaging industry.

[0037] The sheet material converting machine 10 has a series of juxtaposed but interdependent converting stations to form an integral assembly: the converting machine 10 has a feed station 14, then a cutting station 16 (commonly also called a punching station) including, for example, a die or platen press 18 where the sheet material 12 is transformed by cutting, then a scraping station 20 where most of the scrap is stripped, then a blank separation station 22 (commonly also called a reception station) for separation of the blanks 11 (or blanking operation) by a blanking tool 23, then a discharge station 24 where residual scrap sheet material from the punched sheet material 12 is removed.

[0038] The number and nature of the converting stations may vary depending on the nature and complexity of the converting operations to be performed on the sheet material 12 .

[0039] The sheet material processing machine 10 further includes a transport mechanism 26 that enables each sheet material 12 to be moved individually from the exit of the feed station 14 to the discharge station 24, and in the illustrated embodiment, this transport mechanism is a conveyor.

[0040] The conveyor uses a series of gripper bars 28 that are movably mounted by two loops of chain 30, one laterally located on each side of the sheet material converting machine 10. Each loop of chain 30 travels around a loop that allows the gripper bars 28 to traverse a path that passes through the cutting station 16, the dross removal station 20, the blank separation station 22 and the discharge station 24 in sequence.

[0041] Each gripper bar 28 travels on an outward path in a substantially horizontal passing plane between the driven wheel 32 and the idler wheel 34, and then travels on a return path within the top portion of the sheet material processing machine 10. Once back on the driven wheel 32, each gripper bar 28 is now able to grasp a new sheet of material 12 at the leading edge of the sheet material 12.

[0042] In FIG. 1, each processing station is shown in the form of two rectangles positioned on either side of the plane of motion of the sheet material 12, representing its top and bottom portions, respectively.

[0043] In FIG. 1, the transverse (or lateral), longitudinal and vertical directions are designated in a Cartesian spatial system (T, L, V).

[0044] "Upstream" and "downstream" are defined relative to the direction of movement of the sheet material 12 in the handle direction as indicated by arrow D in FIG.

[0045] The sheet material processing machine 10 further comprises a device 36 for determining the height of the sheet material pile in the receiving area 38 of the blank separating station 22. The sheet material pile is therefore a pile of blanks 11 in the embodiment shown.

[0046] The device 36 is connected to the control unit 40 by, for example, an Ethernet connection, and the control unit 40 is adapted to control the device 36. However, the device 36 may be connected to the control unit 40 by any means that allows for a substantially rapid exchange of signals between the device 36 and the control unit 40. For example, the connection may be established wirelessly, for example by Wi-Fi.

[0047] The control unit 40 further comprises a storage module 42 .

[0048] The sheet material converting machine 10 further includes a human machine interface 44, which in the illustrated embodiment is a touch sensitive display.

[0049] The human machine interface 44 allows an operator (not shown) to control the operation of the sheet material processing machine 10. Additionally, information about the current status of the sheet material processing machine 10 can be displayed on the human machine interface 44 to inform the operator.

[0050] A perspective view of the device 36 is shown in FIG.

[0051] The device 36 has a first sensor element 46 disposed on a first side 48 of the receiving area 38 and a second sensor element 50 disposed on an opposite side 52 of the receiving area 38, the first sensor element 46 and the second sensor element 50 facing each other along the width direction of the receiving area 38, which in the illustrated embodiment coincides with the lateral direction T (see FIG. 1).

[0052] The first sensor element 46 includes a light emitting source 54 and the second sensor element 50 consists of a light receiving sensor 56 .

[0053] In principle, the light emitting source 54 and the light receiving sensor 56 may be interchanged, i.e., the first sensor element 46 may consist of the light receiving sensor 56 and the second sensor element 50 may consist of the light emitting source 54.

[0054] 2, a light barrier 58 is formed between the light source 54 and the light receiving sensor 56. Therefore, the interruption of the light barrier 58 can be recorded based on the sensor signal of the light receiving sensor 56.

[0055] The first sensor element 46 is attached to a first rail 60 and the second sensor element 50 is attached to a second rail 62, which are parallel to each other and perpendicular to the width of the receiving area 38 and parallel to the length of the receiving area 38, which in the illustrated embodiment coincides with the longitudinal direction L.

[0056] The first rail 60 and the second rail 62 are mounted to a first frame 64 and a second frame 66, respectively. The first frame 64 and the second frame 66 are connected to the blank separation station 22. The apparatus 36 is therefore suitable for being retrofittable to existing sheet material processing machines 10.

[0057] In principle, the first frame 64 and the second frame 66 may be part of the blanking separation station 22 rather than being part of the apparatus 36 .

[0058] FIG. 3 is a side view of selected portions of the apparatus 36 of FIG.

[0059] 3, it becomes clear that the first sensor element 46 is mounted by a slotted guide slider 68 provided in a slotted guide 70 of the first rail 60. The first sensor element 46, and thus the light source 54 (see FIG. 2), is therefore displaceable along the length of the receiving area 38 as indicated by the double-headed arrow P1 shown in FIG.

[0060] Specifically, the first sensor element 46 is manually displaceable by the operator along the length of the receiving area 38, i.e., the first side 48 of the receiving area 38 is located on the operator side of the sheet material processing machine 10 where it is easily accessible to the operator.

[0061] The second sensor element 50 has an actuator 72 that enables the second sensor element 50 to be automatically displaceable along the length of the receiving area 38 as indicated by double-headed arrow P2 in FIG.

[0062] The opposite side 52 of the receiving area 38 is located on the opposite operator side of the sheet material processing machine 10 where it is not easily accessible by the operator.

[0063] The mode of operation of the sheet material converting machine 10 relative to the device 36 will now be described in detail.

[0064] To prepare the sheet material processing machine 10 for a sheet material processing job, the operator places the sheet material processing machine in a setup mode via the human-machine interface 44. This change of operating mode is recorded by the control unit 40. In principle, the device 36 can also be used equally well without entering a specific setup mode.

[0065] The operator then manually displaces the first sensor element 46 along the length of the receiving area 38 by shifting the slotted guide slide 68 along the slotted guide 70 to the target position.

[0066] The target position is selected so that when the blanks 11 are gathered in a pile of blanks 11 in the receiving area 38 to the target height during operation of the sheet material processing machine 10, at least a portion of the uppermost blank 11 in the pile of blanks 11 is located at the same position along the length of the receiving area 38 as the light source 54 of the first sensor element 46.

[0067] In other words, if the blanks 11 in the pile of blanks 11 do not extend essentially the entire length of the receiving area 38, the first sensor element 46 is positioned by the operator at the position where the blanks 11 will be present.

[0068] 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 been moved and starts automatically displacing the second sensor element 50 along the second rail 62 by controlling the actuator 72 to find the working position of the second sensor element 50.

[0069] To determine the working position, the light receiving sensor 56 transmits its sensor signal to every position along the second rail 62 to which the second sensor element 50 is moved by the control unit 40 .

[0070] The control unit 40 stores the received sensor signals together with the associated positions along the second rail 62 in the storage module 42 .

[0071] When the light emitting source 54 and the light receiving sensor 56 face each other, a light barrier 58 is formed (see FIG. 2), resulting in a non-zero sensor signal from the light receiving sensor 56. The better the alignment of the light emitting source 54 and the light receiving sensor 56, the higher the resulting sensor signal will be; i.e., a maximum sensor signal represents the best alignment between the light emitting source 54 and the light receiving sensor 56.

[0072] The working position is therefore determined by the control unit 40 by identifying the position of the second sensor element 50 along the second rail 62 where the received associated received signal is greatest. The second sensor element 50 is then moved along the second rail 62 to this position.

[0073] The control unit 40 then transmits a message to the human machine interface 44 informing the operator that the device 36 has been properly set up and that the light barrier 58 has been successfully formed.

[0074] Therefore, the operator may change the sheet material processing machine 10 from the setup mode to an operating mode in which the sheet material 12 is processed to form blanks 11 that are stacked into piles in the receiving area 38 .

[0075] During operation of the sheet material processing machine 10, the first and second sensor elements (46, 50) work in an intermittent manner, i.e., when the sheet material processing machine ejects a blank, the sensor elements are temporarily disabled for the time required for the blank to cross the light barrier. For the rest of the time, the light receiving sensor 56 receives and transmits the current sensor signal to the control unit 40, either constantly or at least once every predetermined time unit, for example once every 50 ms. Advantageously, the light receiving sensor consists of several sensor cells arranged one above the other in order to accurately determine the height of the uppermost blank 11.

[0076] As soon as the pile of blanks 11 reaches a height at which the uppermost blank 11 is located at the same height as the light barrier 58, the light barrier 58 goes into a cut-off state and the sensor signal of the light receiving sensor 56 drops, in particular to a value of zero or at least a value corresponding to the noise level of the light receiving sensor 56.

[0077] This change in the sensor signal is recorded by the control unit 40, which is adapted to transmit a message to the human-machine interface 44 that the height of the pile of blanks 11 has reached the height of the light barrier of the device 36.

[0078] Preferably, this height corresponds to a target number of blanks 11 so that the operator can stop operation of the sheet material processing machine 10 and remove the completed blanks 11 from the blank separation station 22.

[0079] In principle, the control unit 40 may also be adapted to automatically shut down operation of the sheet material processing machine once the light barrier 58 is interrupted.

[0080] For the next sheet material converting job, the operator can again enter the setup mode and manually adjust the position of the first sensor element 46 if necessary, and repeat the process described above.

[0081] In the above-described embodiment, the sheet material pile height determining device 36 is essentially used to detect when a pile of sheet material 12, specifically a pile of blanks 11, has been stacked during operation of the sheet material processing machine 10, which corresponds to determining when a certain number of blanks 11 have been produced.

[0082] However, the device 36 can also be used to detect when the pile of sheets 12 has been lowered, i.e., when so many sheets 12 have been removed from the pile of sheets 12 that the height of the pile of sheets 12 is lower than the height of the light barrier 58.

[0083] The sheet material processing machine of the invention offers a particularly simple and inexpensive possibility for checking the height of a sheet material pile. Furthermore, the operation of the sheet material processing machine can be easily adapted to a wide range of sheet material sizes and / or shapes.

Claims

1. 1. A sheet material processing machine having a receiving area (38) for collecting a pile of sheet material and a device (36) for determining the height of said pile of sheet material, The device (36) has a manually displaceable first sensor element (46) arranged on a first side (48) of the receiving area (38) and an automatically displaceable second sensor element (50) arranged on an opposite side (52) of the receiving area (38), the first and second sensor elements (46, 50) being arranged opposite each other along the width of the receiving area (38); the first sensor element (46) and the second sensor element (50) are displaceable along the length of the receiving area (38); the first sensor element (46) is one of a light emitting source (54) and a 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 source (54) and the light receiving sensor (56) face each other, they form a light barrier (58) along the width direction; The sheet material processing machine, wherein the first sensor element (46) is mounted by a slotted guide slider (68) mounted in a slotted guide (70) of a first rail (60).

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

3. 3. Sheet material processing machine according to claim 1 or 2, wherein the second sensor element (50) is displaceable by a motor of the second sensor element, in particular by an actuator (72) of the second sensor element (50).

4. 4. The sheet material processing machine according to claim 1, wherein the device (36) comprises a control unit (40) connected to the first sensor element (46) and to the second sensor element (50), the control unit (40) receiving a sensor signal from the light receiving sensor (56) and controlling the movement of the second sensor element (50).

5. 5. A sheet material processing machine according to claim 4, wherein the control unit (40) is adapted to move the second sensor element (50) along the length direction to a working position in which the sensor signal is non-zero, preferably in which the sensor signal is at a maximum.

6. 6. A sheet material processing machine according to claim 5, wherein said control unit (40) is adapted to move said second sensor element (50) to said working position each time said first sensor element (46) is moved.

7. 7. A sheet material processing machine according to claim 1, wherein the first sensor element (46) is arranged at an operator side of the sheet material processing machine (10) and the second sensor element (50) is arranged on an opposite side of the operator side of the sheet material processing machine (10).

8. 8. A sheet material processing machine according to claim 1, wherein the receiving area (38) is part of a blank separating station (22) of the sheet material processing machine (10) and the sheet material pile is a pile of blanks (11).

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