punching machine

Abstract

Punching machine (10) for processing material in sheet form, in particular for processing cardboard sheets (12), with a transport mechanism (20, 36) for transporting sheets (12) one after the other from a feed side of the machine (10) via at least one processing station (22, 26, 30) to an ejection side along a transport path (TP), wherein the machine (10) has a recording system (42) with at least one high-speed camera (44) which is assigned to a section below the blanking tool (32) for recording a plurality of images of blanks falling from the blanking tool, a memory for storing recorded images and a processing system (67) for processing the stored images.

Description

[0001] The invention relates to a die-cutting machine for processing material in sheet form, in particular for processing cardboard sheets, with a transport mechanism for transporting sheets one after the other from a feed side of the machine via at least one processing station to an ejection side along a transport path.

[0002] Die-cutting presses play a crucial role in the printing and packaging industries, serving as essential equipment for die-cutting, creasing, embossing, and other processing operations on sheet-fed materials. These machines are designed to handle materials such as cardboard, cardstock, and various types of paper, transforming flat sheets into the complex shapes and designs required for packaging, promotional materials, and other applications. Operating a die-cutting press involves the sequential processing of sheets, which are transported at high speed through multiple stations. This transport is typically facilitated by gripper bars driven by chains. The gripper bars securely hold the leading edge of each sheet to guide it precisely through the die-cutting and creasing stations.

[0003] In high-speed production environments, ensuring the integrity and precise positioning of each sheet throughout the entire process is crucial. However, a common challenge is the tendency of the sheets to deform as they move through the machine.

[0004] Factors such as rapid acceleration and deceleration, as well as aerodynamic effects, can cause the sheets to bend or become wavy. This deformation affects the sheet's flatness and leads to misalignment when the sheet undergoes punching or creasing operations.

[0005] A deformation of the sheet can have two serious consequences: firstly, premature detachment of pre-cut blanks from the rest of the sheet, and secondly, misalignment of the downstream parts of the sheet in relation to the punching tools or creasing knives.

[0006] Premature separation can occur if the leading edge of a pre-cut blank is caught by the airflow and subjected to such force that the connection between the pre-cut blank and the rest of the sheet (the so-called "holding points," which are narrow material bridges left behind during pre-cutting) breaks. The leading edges of the blanks are exposed to the airflow when the sheet bends and the leading edge is located at the tip of a flute. Should the blank separate from the rest of the sheet at a location other than the intended ejection or collection point, it can fall into the machine and cause blockages, bringing the press to a standstill. Such interruptions reduce productivity.

[0007] Misalignment occurs when a sheet is processed in a processing station while still in a wavy state. The wavy state can result from the sheet slowing down considerably upon reaching the processing station. Due to the wavy shape of the sheet, the contact points between the sheet and the die-cutting tools or creasing knives change. Generally, the overall length of a wavy sheet is less than the length of a flat sheet, causing parts at the trailing end of the sheet to be positioned closer to the leading end than expected. This leads to incomplete cuts or unintended pressure on certain areas.

[0008] Modern die-cutting machines use sensors strategically positioned along the sheet's path to continuously monitor its condition and the desired processing. If a problem occurs, such as a blank unintentionally detaching from the sheet, the machine stops.

[0009] For machine operators, identifying and diagnosing the cause of sheet detachment is a significant challenge. The rapid movement of sheets through the printing press makes it virtually impossible to visually monitor each sheet in real time. Operators often have no choice but to determine the causes of blockages after they occur, which can lead to repeated downtime as they make adjustments through trial and error. Without a clear understanding of when and where the deformation occurs, it is difficult to implement effective countermeasures, thus prolonging the production process interruption.

[0010] Especially with the depaneling tool, a blank can stick to a sheet if a holding point in the depaneling station is not broken.

[0011] The cause could be excessive moisture in the cardboard due to environmental or storage conditions, which makes the sticking point more resistant. It could also be due to a blanking tool whose ejectors are not ideally positioned. It could also be due to misalignment of the entire sheet.

[0012] In most cases, a photocell located directly below the lower separator detects the absence of blanks. However, not all missing blanks are detected. For example, if the sheet has two blanks across its width and only one is ejected, the ejected blank triggers the signal recorded by the photocell, so the second, missing blank goes unnoticed.

[0013] The invention offers a solution to this problem by providing a system that allows operators to determine the cause of the machine stopping. In particular, the invention is intended to identify the cause of a failure to drop cut pieces.

[0014] For this purpose, the invention provides a machine as described above, wherein the machine has a recording system with at least one high-speed camera assigned to a section below the depaneling tool for recording multiple images of blanks falling from the depaneling tool, a memory for storing recorded images and a processing system for processing the stored images.

[0015] The recording system captures images of a specific location to help identify problems. This real-time data allows for immediate analysis and reveals patterns that may indicate underlying issues. By accurately determining the exact stage at which a problem occurs, operators can quickly identify the necessary adjustments to resolve it.

[0016] Furthermore, the system can be programmed to automatically adjust certain machine parameters in response to detected problems, thereby further improving the efficiency of corrective actions.

[0017] In general, the invention involves mounting a camera near the blanking tool to record below the machine and capture the falling of the blank in the blanking station. The camera(s) record the falling of the blank. The camera is mounted on the side of the blanking tool, with an approximately horizontal optical axis perpendicular to the sheet travel direction. The cameras must cover at least both the operator side and the opposite side of the blanking tool. Ideally, there should be two to three cameras on each side of the blanking tool.Solving potential problems is significantly easier if the operator can identify which cut caused a machine stoppage, allowing them to check whether the part of the tool whose function is to eject the cut is misaligned, worn, or otherwise malfunctioning.

[0018] Preferably, these cameras are supplemented by a camera on the front and one on the back, whose optical axis runs parallel to the direction of the arc travel.

[0019] Another embodiment of the invention comprises a display to provide an operator with an image sequence that is representative of a problem that occurs. Providing the operator with an image sequence representative of the problem improves troubleshooting capabilities. By visualizing the problem as it occurs, operators can diagnose problems more effectively and take appropriate corrective action immediately.

[0020] The recording system can be designed to capture multiple images of a representative section below the blanking tool synchronously with the machine cycles, enabling the analysis or display of a selected image sequence for any sheet in relation to the machine cycle timeline. This reduces the time required by an operator to retrieve the relevant images and also decreases the required storage capacity for the images, as only relevant images are captured.

[0021] Preferably, the display is designed to show a sequence of images in relation to the timeline of the machine cycle, thereby reducing the time required by an operator to understand what caused the machine to stop.

[0022] In one embodiment, the at least one high-speed camera is arranged such that its optical axis is directed into the space below a lower depaneling tool of the machine, so that the camera can record the falling blanks.

[0023] Preferably, several high-speed cameras are used, in particular two or more on opposite sides of the depaneling tool. By using multiple cameras, it is possible for each camera to record only a portion of the top surface of the sheet, so that each camera has a better view of "its" portion of the top surface than in an arrangement with a single camera that has to record the entire surface of the sheet.

[0024] Additional information can be provided if a high-speed camera is also positioned upstream and / or downstream of the depaneling tool.

[0025] In one embodiment, the high-speed camera is arranged above the plane in which the sheet is held in the depaneling tool, with a mirror provided so that the camera can record the sheet. This makes it possible to arrange the camera(s) above the depaneling tool at a location where more space is available than to the side of the depaneling tool.

[0026] The high-speed camera is equipped with a cleaning system to remove dust and dirt from the camera lens.

[0027] To improve the quality of the images recorded by the high-speed camera(s), a lighting system can be assigned to the high-speed cameras.

[0028] In one embodiment, the processing system includes an image evaluation unit for determining a deviation of a recorded drop of cut pieces from a predefined position or design, making it easier for an operator to identify the cause of a problem.

[0029] The processing system is preferably designed to perform a process for assembling the recorded images in order to form a complete image from the individual images that shows all relevant sections.

[0030] Preferably, the machine is designed to To transport the sheet with the gripper bar from the feed side of the machine via at least one processing station to an ejection side, to record several images of at least one representative section of the arc using the recording system, where the recording with the recording system is synchronized with the machine cycle in order to track the position of the image in relation to the timeline of the cycle, to store the recorded images in a buffer of limited size in order to retain a record of the images in relation to the timeline of the cycle for only a limited number of cycles, In the event of a machine stoppage, the recording system should be stopped to preserve the multiple images that were stored in the buffer before the machine stopped. to display a sequence of images selected in relation to the timeline of the cycles.

[0031] By recording an image sequence that depicts a representative section of the sheets synchronously with the machine cycles, synchronization allows the operator to analyze the behavior of a selected subsequence of the processing. For example, the operator can select to visualize the movement and position of the sheet immediately after it is placed in the register. Synchronizing the recording with the machine cycle makes it very easy for the operator to select to visualize the movement of the next or previous sheet (or any other sheet) immediately after it is placed in the register, as it is sufficient to jump to the position of the recorded images separated in time by an integer multiple of the machine cycle.By synchronizing the recording with the machine cycle, some metadata can also be inserted into the recording, for example, by adding the time the register device closes in the feed station or the time of transfer to the gripper bar. This time can be a timestamp if the action takes almost no time, or a time interval indicating the start and end of the action.

[0032] Preferably, the image sequence is selected to show the blanks emerging from the lower blanking tool. The images recorded after the blanking step begins can be used to determine which of the multiple blanks from a sheet was not properly separated.

[0033] The recorded images can be stored in a ring buffer, thus eliminating the need for large storage capacities to hold large amounts of data. In practice, only a limited number of the most recent processing cycles are relevant for identifying a problem. A typical number of recent cycles stored in the ring buffer is ten sheets.

[0034] An embodiment of the invention will now be described with reference to the accompanying drawings. These drawings show... Fig. 1 schematically a punching machine, Fig. 2 the speed of a sheet being advanced from a first to a second processing station, Fig. 3 a bow that is advanced at high speed using a gripper rod, Fig. 4 schematically a utility separation station of the machine Fig. 1 in a front view, Fig. 5 schematically in a top view the cameras arranged under the depaneling tool, Fig. 6 schematically a complete picture that is composed of the individual pictures taken with the camera, Fig. 7 schematically the high-speed camera with a cleaning system provided for it in cross-section, Fig. 8 schematically the high-speed camera from Fig. 6 in a top view and Fig. 9 schematically an image recording system which is an alternative to the embodiment from Fig. 4 represents.

[0035] Fig. Figure 1 schematically shows a die-cutting machine 10, which is designed to transform sheets 12 (usually made of cardboard) into pre-cut flat boxes. These boxes are then folded and glued using another machine.

[0036] The process of producing the pre-cut flat boxes (hereinafter referred to as "cutouts 14") consists of cutting out shapes from flat cardboard sheets 12 in the die-cutting machine 10. The sheets pass through several stations, including an infeed station 16, where sheets 12 are individually removed from a stack; a feed station 18 with a feed table 19, on which sheets 12 are aligned and gripped by a gripper bar 20; a press station 22, where the sheets 12 are punched and scored by a punch press 24; a waste ejection station 26, where unwanted parts of the sheet 12 are removed with an ejection tool 28; a blanking station 30, where the pre-punched blanks 14 are removed and stacked with a blanking tool 32; and an ejection station 34, where the remaining parts of the sheet 12 are released by the gripper bar 20 and removed via a belt 40.

[0037] The transport of the sheets 12 through various processing stations is carried out by a chain drive system and a gripper bar mechanism. The chain drive consists of endless chains 36 that run the length of the machine 10 and ensure synchronized and precise movement of the gripper bars 20 attached to the chains. The gripper bars 20 securely hold the leading edge of each sheet 12.

[0038] On the feed table 19, the sheets 12 are aligned by a register device to ensure correct positioning and then gripped by the gripper bar 20. The gripper bar 20 firmly grasps the leading edge of the sheet 12 so that it can be transported precisely through the subsequent stations of the machine. The movement of the gripper bar 20 is synchronized with the action of the tools in the press station 22, the eject station 26, and the blanking station 30.

[0039] The movement of the arcs 12 from one station to the next comprises several different phases (viewed in direction A, in which the arcs are transported along a transport track TP by the machine 10): acceleration a, constant high-speed travel t, deceleration d and standstill s (see Fig. 2) The entirety of these phases constitutes a complete machine cycle MC.

[0040] To achieve a high throughput of approximately three large sheets 12 per second, the time required to transfer a sheet 12 from one station to the next should be as short as possible. Accordingly, a high transport speed must be achieved, which requires strong acceleration so that the sheet 12 reaches this speed as quickly as possible. Conversely, strong deceleration is also necessary so that the sheet 12 can be transported at this high speed for as long as possible. Two phases of the sheet 12 transport cycle are critical: the high-speed phase and the strong deceleration phase. Furthermore, the transfer of the sheet 12 from the feed table to the gripper bar 20 is critical.

[0041] Due to the high speed at which the sheets 12 are gripped by the gripper bars 20 and then travel through the machine, it is impossible for an operator to visually identify the cause of interruptions. The core idea is to use at least one high-speed camera 44 to monitor specific points where the sheets 12 move within the machine. The camera(s) 44 is / are strategically positioned in the blanking station 30 where deviations of the sheet 12 from the expected path are critical and misaligned or otherwise defective blanking tools are critical. This will now be demonstrated using the Fig. 3 and Fig. 4 explained.

[0042] In Fig. Figure 3 shows a sheet 12 being transported at high speed along a conveyor track by the gripper bar 20 immediately before the panel separation station 30. Due to the high speed, the sheet 12 is wavy.

[0043] The gripper bar 20 transports the sheet 12 with the blanks 14 into the blanking station 30, where the sheet 12 is stopped so that it is positioned between an upper blanking tool 32A and a lower blanking tool 32B. A downward movement of the upper blanking tool 32A severs the remaining holding points connecting the blanks to the rest of the sheet 12 and to adjacent blanks 14, and the blanks 14 are pushed downwards through the lower blanking tool 32B, from which they fall towards a collection area.

[0044] The machine is equipped with a recording system 42 for recording images of the blanks being separated from the sheet 12 in the blanking station 30. The recording system 42 has high-speed cameras 44 arranged to record the blanks falling from the lower blanking tool 32B.

[0045] As in Fig. As can be seen in Figure 4, the high-speed cameras 44 are arranged on opposite sides of the sheet 12 travel path below the blanking tool. The cameras 44 are mounted on a machine frame 49 with a viewing axis oriented horizontally towards the center of the machine. This ensures that the field of view of each camera covers the area through which the blanks fall from the respective side of the sheet 12 towards approximately the center of the blanking tool 32.

[0046] As in Fig. As can be seen in Figure 5, three high-speed cameras 44 are arranged at a distance from each other on each side of the arc 12. These are labelled "OS" for the operator side and "OOS" for the opposite operator side.

[0047] In addition, there is a front-facing camera (“FS”) and a rear-facing camera (“RS”).

[0048] The high-speed cameras 44 record from approximately the time the depaneling tool 32 closes (which pushes the blanks downwards from the lower depaneling tool 32B) until a specific time after the depaneling process is complete, in order to cover the time the blanks typically need to move downwards from the underside of the lower depaneling tool 32B by approximately 10 to 20 cm. During this "free fall" period, the blanks can be recorded by the cameras 44.

[0049] Fig. Figure 6 schematically shows a complete image assembled by the processing system from the individual images recorded by the various high-speed cameras 44. By displaying the complete image as a video sequence, an operator can immediately identify which blank has not ejected properly from the depaneling tool 32.

[0050] As in the Fig. 7 and Fig. As shown in Figure 8, the cameras 44 are combined into a module 45, which can be pre-assembled outside the machine 10 and then installed in the machine 10.

[0051] Module 45 includes a mounting rod 46 in which the cameras 44 are held. The mounting rod 46 can be formed from separate segments arranged one after the other.

[0052] Each camera 44 is positioned so that its lens 48 is directed towards the travel track TP of the arch 12.

[0053] A lighting system 51 is provided to direct light onto the arches 12.

[0054] A cleaning mechanism 52 is provided to maintain the optimal performance of the camera 44 in the dusty environment of the punching machine 10. The cleaning system 52 includes air ducts 54 and air outlets 56.

[0055] An air duct 54 is integrated into the camera mounting rod 46, and each camera lens 48 of the recording system is assigned one of the air outlets 56.

[0056] Each camera 44 has a bypass 60 to supply compressed air to the next downstream air outlet 56.

[0057] Alternatively, the camera mounting rod 46 can have as many air channels as there are cameras 44, in order to supply each outlet 56 with air individually.

[0058] Compressed air from an air supply can be periodically directed from a supply 61 into the air duct 54 and discharged via the air outlet 56 to remove dust and particles from the surface of the camera lenses 48.

[0059] The mounting rod 46 can be designed as a single-piece element, possibly 3D-printed, which integrates the mounting structure for the cameras 44, the air ducts 54, and the air outlets 56. A 3D-printed mounting rod allows for the implementation of complex shapes for the air outlet 56 at the locations of the camera lenses 48.

[0060] The high-speed camera 44 is connected to a memory 62 for storing the recorded images of the arc 12.

[0061] Memory 62 is a ring buffer used to store recordings of a specific number of machine cycles. An example of this specific number is ten. In other words, ring buffer 62 allows the retrieval of images from the last ten machine cycles.

[0062] Additional elements of machine 10 are a control unit 64 and a display 66, which are located in Fig. 4 are shown schematically.

[0063] The control unit 64 includes an image processing system 67.

[0064] When machine 10 is in operation, the high-speed camera 44 records images of the blanks falling from the lower depaneling tool 32B. The images are stored in the ring buffer 62, from which they can be retrieved and shown to an operator in slow motion.

[0065] To reduce the amount of data to be processed, the recording of images is synchronized with the operation of the die-cutting machine. Camera 44 captures a series of images as the blanks are pushed downwards by the lower blanking tool 32B, so that they are within the camera's field of view.

[0066] In general, the image processing system 67 within the controller 64 processes the recorded images so that they are made available to an operator. This processing can include adding a timestamp, a reference to the machine cycle, which allows browsing and / or comparing "identical" images from different machine cycles. The processing can also include extracting an image sequence for different machine cycles, all starting at the same reference point within a machine cycle. Finally, the processing can also include determining whether any sheet is being recorded in the register device at all.

[0067] The processing system can evaluate the video segments and determine if there is a deviation from the expected state. The controller 64 can then retrieve the relevant video segment from the buffer 62 and display the sequence on the screen 66, which consists of the last partial frames of the recorded images, thus showing the operator the state of the last sheet. The extracted video is shown to the operator in slow motion. This slow-motion playback allows the operator to observe the sheet in detail, which is not possible at normal operating speeds.

[0068] The video sequence allows an experienced operator to decide on appropriate adjustments to the die-cutting machine settings to prevent the observed problems. This not only improves output quality but also reduces machine downtime, as problems can be resolved more quickly. Specifically, the operator can adjust the machine's blanking tool 32 once the position of the sheet causing the problem is known.

[0069] There are additional countermeasures that the control unit 64 can either initiate automatically or propose to the operator for approval.

[0070] One of these countermeasures is to reduce the machine's speed. This can be done iteratively. Control unit 64 reduces the transport speed to a level at which the critical condition disappears.

[0071] These automatic adjustments not only improve the quality of the finished products but also increase the efficiency of the stamping process by reducing downtime due to machine jams. The system's ability to react to detected problems in real time enables continuous operation at optimal speeds while maintaining product integrity. Furthermore, by minimizing manual intervention, the system reduces operator workload and the risk of human error.

[0072] An alternative embodiment of the recording system 42 is described in Fig. 9 shown. The difference to recording system 42 from Fig.The feature 4 consists of using a single camera 44 per side of the arch 12, which is positioned at a greater distance from the transport track TP and thus from the edges of the arch 12. The distance is chosen such that the field of view of the camera 44 allows the entire length of an arch 12 to be recorded.

[0073] A mirror 70 is positioned below the lower depaneling tool 32B, near the space into which the blanks fall from the lower depaneling tool 32B. The mirror 70 directs the field of view FW of the camera 44 into the space below the depaneling tool 32, thus allowing the camera 44 to be positioned at a greater distance from the depaneling tool 32. Generally, more free space is available within the punching machine 10 above the transport track TP than below the depaneling tool 32.

[0074] For example, the camera 44 is arranged above the transport track TP, and the mirror 70 is arranged at an angle β of approximately 40°, which results in an inclination of the optical axis by 10° relative to the surface of the arc 12.

[0075] Depending on the available space within the die-cutting machine 10, other angles can also be selected. The relevant condition that must be met is that the camera 44 can record the length of a side section of all sizes of sheets 12 that can be processed with the die-cutting machine 10.

[0076] The second embodiment also includes a cleaning mechanism. This cleaning mechanism is specifically designed for removing dust from the mirror's reflective surface. Compressed air can be used here, similar to the cleaning mechanism of the first embodiment.

Claims

[1] Die-cutting machine (10) for processing material in sheet form, in particular for processing cardboard sheets (12), with a transport mechanism (20, 36) for transporting sheets (12) successively from a feed side of the machine (10) via at least one processing station (22, 26, 30) to an ejection side along a transport track (TP), wherein the machine (10) has a recording system (42) with at least one high-speed camera (44) assigned to a section below the depaneling tool (32) for recording multiple images of blanks falling from the depaneling tool, a memory for storing recorded images and a processing system (67) for processing the stored images. [2] Machine (10) according to claim 1, wherein the processing system (67) comprises a display (66) to provide an operator with a sequence of images that is representative of a problem that has occurred. [3] Machine (10) according to one of the preceding claims, wherein the recording system (42) is designed to record multiple images of a representative section below the blanking tool (32) synchronously with the machine cycles, so that the analysis or display of a selected image sequence for any sheet in relation to the timeline of the machine cycle is possible. [4] Machine according to any of the preceding claims, wherein the display (66) is designed to display an image sequence in relation to the timeline of the machine cycle. [5] Machine (10) according to one of the preceding claims, wherein the at least one high-speed camera (44) is arranged such that its optical axis is directed into the space below a depaneling tool (32B) of the machine (10). [6] Machine (10) according to claim 5, wherein several high-speed cameras (44) are used, in particular two or more on opposite sides of the depaneling tool (32). [7] Machine according to one of the preceding claims, wherein the high-speed camera (44) is arranged upstream and / or downstream of the depaneling tool (32). [8] Machine (10) according to one of claims 5 to 7, wherein the high-speed camera (44) is arranged above the plane in which the sheet (12) is received in the blanking tool (32), wherein a mirror (70) is provided so that the camera (44) can record the blanks. [9] Machine according to one of the preceding claims, wherein the high-speed camera (44) is associated with a cleaning system (52). [10] Machine (10) according to one of the preceding claims, wherein a lighting system (51) is associated with the high-speed camera (44). [11] Machine (10) according to one of the preceding claims, wherein the processing system (67) comprises an image evaluation unit for determining a deviation of a recorded section of the sheet (12) from a predefined position or configuration. [12] Machine (10) according to any of the preceding claims, wherein the processing system (67) is designed to perform a process for assembling the recorded images. [13] Machine (10) according to any of the preceding claims, wherein the machine is designed to - to transport the sheet (12) with the gripper bar (20) from the feed side of the machine (10) via at least one processing station (22, 26, 30) to an ejection side, - to record several images of at least one representative section of sheet (12) using the recording system (42), - wherein the recording with the recording system (42) is synchronized with the machine cycle in order to track the position of the image in relation to the timeline of the cycle, - to store the recorded images in a buffer of limited size in order to retain a record of the images in relation to the timeline of the cycle for only a limited number of cycles, - to stop recording with the recording system (42) in the event of a machine stoppage, in order to retain the multiple images that were stored in the buffer before the machine stopped, - to display a sequence of images selected in relation to the timeline of the cycles. [14] Machine according to claim 13, wherein the image sequence is selected to show the blanks falling from the lower depaneling tool (32B) after the depaneling step. [15] Machine according to claim 13 or 14, wherein at least two different image sequences with the same relationship to the timeline of cycles are displayed.

Images