Die cutting positioning deviation rectifying system and deviation rectifying method thereof

Abstract

The invention discloses a die cutting positioning and deviation rectifying system and method, and the system comprises a material conveying module which is used for bearing and conveying coiled materials or sheets to be subjected to die cutting along a preset path; the multi-dimensional vision acquisition module is arranged at the front end of the die cutting station and is used for capturing image data of material surface feature marks in real time; the deviation correction execution module is located between the material conveying module and the die cutting die and comprises a UVW three-axis linkage alignment platform used for adjusting the position of the material or the position of the die; the central control unit is respectively in signal connection with the multi-dimensional vision acquisition module and the deviation correction execution module; according to the invention, the problem that the traditional equipment cannot correct the angle deviation can be solved, the device is particularly suitable for die cutting of angle-sensitive FPC (Flexible Printed Circuit) flat cables and special-shaped labels, and the alignment precision can reach + / -0.03 mm; the low inertia characteristic of the UVW parallel mechanism is utilized, and the FPGA hardware is combined to accelerate image processing, so that the system can adapt to the high-speed die cutting rhythm of more than 300 times per minute.

Description

Technical Field

[0001] This invention relates to the field of automated die-cutting technology, and in particular to a die-cutting positioning and correction system and its correction method. Background Technology

[0002] During the die-cutting process of roll or sheet materials, due to the elastic stretching of the material itself, the jump distance error accumulated in the printing process, and the serpentine deviation during the conveying process, the die-cutting die often has difficulty accurately aligning with the outline of the printed lines or patterns.

[0003] Existing die-cutting positioning technologies mainly rely on mechanical gauges or photoelectric sensors for simple edge alignment. This approach has significant drawbacks: Low precision: It can only correct lateral (X-axis) deviations, cannot solve longitudinal (Y-axis) stretching accumulation errors, and cannot handle angular (θ-axis) deviations caused by material skewing.

[0004] Poor flexibility: Once the product model is changed, the sensor position needs to be mechanically adjusted in a cumbersome manner, resulting in a long changeover time.

[0005] Lack of feedback mechanism: This is a "blind cutting" process, which cannot perceive the actual effect after die cutting in real time and make closed-loop corrections, resulting in a high scrap rate.

[0006] In recent years, although machine vision-based die-cutting machines have emerged, most of them use static photography and XY platform movement. The problem is that if the material rotates, simple XY movement cannot correct the angle, and forced die-cutting will result in too much blank space on one side of the product and damage to the pattern on the other side; moreover, traditional vision algorithms are not stable enough in recognizing reflective materials or blurred mark points, which can easily lead to false corrections. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the existing technology. The proposed die-cutting positioning and correction system and its correction method achieve comprehensive and high-precision dynamic compensation for material position deviation by adopting a UVW three-axis linkage mechanism and a multi-level vision matching algorithm.

[0008] Firstly, to solve the aforementioned technical problems, this application adopts a technical solution as follows: a die-cutting positioning and correction system, the system comprising: The material conveying module is used to carry and convey the rolls or sheets to be die-cut along a preset path; A multi-dimensional vision acquisition module is installed at the front end of the die-cutting station to capture image data of material surface feature marks in real time. The correction execution module is located between the material conveying module and the die-cutting mold, and includes a UVW three-axis linkage alignment platform for adjusting the material position or the mold position. The central control unit is connected to the multi-dimensional vision acquisition module and the correction execution module respectively; The central control unit has a built-in coordinate mapping algorithm engine, which is configured to convert the pixel coordinate system in the image data into the physical pulse coordinate system of the correction execution module, and calculate the current lateral deviation, longitudinal deviation and angular rotation deviation of the material, and drive the UVW three-axis linkage alignment platform to perform reverse compensation motion.

[0009] More preferably, the multi-dimensional vision acquisition module includes at least two sets of high-speed industrial cameras arranged in a linear manner, each set of cameras being equipped with a telecentric lens and an adjustable coaxial composite light source. The exposure trigger signal of the high-speed industrial camera is synchronized with the encoder signal of the material conveying module to achieve fixed-distance trigger acquisition and eliminate the influence of conveying speed fluctuations on image stretching.

[0010] More preferably, the UVW three-axis linkage alignment platform of the correction execution module consists of a base, a movable table and a drive mechanism; The drive mechanism includes three sets of servo motors arranged in a circular or parallel pattern. Each set of servo motors is connected to the movable table through a precision ball screw and a cam follower. Through the differential motion of the three axes, the X-axis translation, Y-axis translation, and θ-axis rotation in the plane are realized simultaneously.

[0011] More preferably, the central control unit includes an FPGA image preprocessing unit and an ARM motion control unit; The FPGA image preprocessing unit is used to perform Gaussian filtering noise reduction and Sobel edge detection on the original image, and extract sub-pixel level contour features of the Mark points; The ARM motion control unit is used to receive the processed contour coordinates and calculate the geometric center of the Mark point based on the least squares fitting method.

[0012] Further preferred options include a secondary vision inspection module located at the rear end of the die-cutting station; The secondary vision inspection module is used to acquire images of the waste skeleton or finished product after die-cutting, calculate the residual deviation value between the die-cutting line and the printing texture, and send the residual deviation value as a feedback signal to the central control unit, which then corrects the compensation parameters for the next cycle through a PID algorithm.

[0013] Secondly, this invention provides a die-cutting positioning and correction method, comprising the following steps: S1. Reference calibration: During the system initialization phase, establish the affine transformation matrix between the visual pixel coordinate system and the UVW alignment platform physical coordinate system. S2, Feature Acquisition: When the material moves to the detection area, the multi-dimensional vision acquisition module is triggered to acquire a local image containing the Mark points; S3. Deviation Calculation: Identify the actual coordinates of the Mark points in the image, compare them with the preset standard die-cutting coordinates, and calculate the current deviation vector (ΔX, ΔY and Δθ). S4. Motion Compensation: Based on the affine transformation matrix, the deviation vector is converted into the target pulse increment of the UVW triaxial motor, driving the alignment platform to complete the reverse displacement before the die-cutting action occurs. S5. Die-cutting execution: After the alignment platform stabilizes, the die-cutting mold is triggered to press down or close.

[0014] More preferably, in step S1, the process of establishing the affine transformation matrix is ​​as follows: the UVW alignment platform is controlled to move along the X-axis and Y-axis and rotate along the θ-axis by a preset distance, the vision module records the displacement change of the Mark point in the image, and the rotation center coordinates and scaling factor are solved by linear regression equation.

[0015] More preferably, in step S3, the deviation calculation employs a multi-level matching strategy: First, perform a downsampling pyramid search to coarsely locate the Mark points; Then, fine positioning is achieved by performing gray-level matching based on normalized cross-correlation within the coarse positioning area; If a Mark point is obscured or damaged, causing the matching degree to fall below the preset threshold, the relative position relationship of neighboring Mark points will be automatically used for interpolation estimation.

[0016] More preferably, in step S4, the motion compensation employs a feedforward and predictive control strategy: The system collects real-time speed and tension fluctuation data of material conveying and establishes a material elastic deformation model; Based on the calculated geometric deviation, the elastic deformation compensation caused by tension fluctuation is superimposed to correct the final motor pulse output.

[0017] Further preferably, the method also includes an anomaly handling mechanism: if the calculation deviation exceeds the system's maximum correction stroke for N consecutive cycles, the system determines that the printing jump distance or joint is abnormal, and automatically triggers a shutdown alarm or executes a jump-cut command, where N is a preset positive integer.

[0018] Advantages of this invention: 1. This invention solves the problem that traditional equipment cannot correct angular deviations, and is particularly suitable for angle-sensitive FPC cables and die-cutting of irregularly shaped labels, with an alignment accuracy of ±0.03mm; 2. This invention utilizes the low inertia characteristics of the UVW parallel mechanism and combines it with FPGA hardware to accelerate image processing, enabling the system to adapt to high-speed die-cutting cycles of over 300 times per minute.

[0019] 3. This invention effectively addresses material tensile deformation and poor Mark point printing by using interpolation estimation and an elastic deformation model, thus ensuring the continuity and stability of production. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the die-cutting positioning and correction system of the present invention; Figure 2 This is a schematic flowchart of the die-cutting positioning and correction method of the present invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Figure 1 This is a schematic flowchart of a die-cutting positioning and correction system according to an embodiment of the present invention. It should be noted that if substantially the same result is achieved, the method of this application is not based on... Figure 1 The sequence of processes shown is limited. Example

[0024] like Figures 1-2 The die-cutting positioning and correction system shown includes a material conveying module, a multi-dimensional vision acquisition module, a correction execution module, and a central control unit.

[0025] The core improvement lies in the adoption of the UVW three-axis linkage alignment platform in the correction execution module. Unlike the traditional XY stacked platform, the UVW platform adopts the principle of planar parallel mechanism. Through the differential cooperation of three sets of motors, it can simultaneously realize X-axis movement, Y-axis movement, and θ-axis micro-rotation around the geometric center in one plane. It has stronger structural rigidity and faster response speed (typically <50ms).

[0026] The central control unit is equipped with a specific coordinate mapping algorithm, which can convert the deviation (pixel domain) collected by the vision system into motor pulses (physical domain) of the UVW platform in real time.

[0027] In this embodiment, specifically: the correction method of the present invention includes: Calibration phase: Establish the mapping relationship between vision and mechanism, especially determine the coordinates of the rotation center.

[0028] Recognition stage: The algorithm of "coarse positioning and sub-pixel fine positioning" is adopted, which can ensure a detection accuracy of more than 0.01mm even if the edge of the Mark point is blurred.

[0029] Compensation phase: Calculate the deviation vector, superimpose the material deformation compensation model, and drive the UVW platform to move in reverse.

[0030] Closed-loop stage: Two-level visual inspection is used to statistically analyze the residuals after die-cutting and dynamically adjust the PID parameters.

[0031] In this embodiment, specifically: the material conveying module: The material conveying module is used to achieve continuous and stable conveying of FPC flexible circuit boards, preventing the FPC from being stretched, wrinkled, or shifted during the conveying process. The specific configuration is as follows: The conveyor belt is made of polyurethane material, with a thickness of 3 mm and a width of 800 mm. The surface of the conveyor belt is treated with anti-slip and anti-stick properties, and the surface roughness is Ra0.8 to prevent the FPC flexible circuit board from slipping or sticking during the conveying process. The conveying speed of the conveyor belt is adjustable, with an adjustment range of 1-3 meters / minute, to meet the needs of FPC die-cutting cycle (200-300 times / minute). The drive motor is a 1.5 kW AC servo motor with a speed range of 0-3000 rpm and a positioning accuracy of ±0.001 rpm. The drive motor and the conveyor belt are connected by a synchronous belt drive. The synchronous belt is a polyurethane synchronous belt with 60 teeth and a transmission efficiency of ≥98%, ensuring that the conveyor belt conveys a stable and accurate speed with no speed fluctuation, and the speed fluctuation is ≤±0.01 m / min. The tension adjustment mechanism includes a tension sensor, an adjustment cylinder, and a tension adjustment roller. The tension sensor is a high-precision tensile sensor with a detection accuracy of ±0.2 N and a range of 0-50 N. It is used to detect the tension of the FPC in real time during the conveying process and transmit the tension data to the central control unit. The appropriate tension for the FPC is 5-10 N to avoid excessive tension causing the FPC to stretch and deform, and insufficient tension causing the FPC to wrinkle. The adjustable cylinder has a stroke of ±10 mm and a working pressure of 0.5 MPa. It is used to drive the tension adjusting roller to move up and down to adjust the tension of the FPC. When the tension sensor detects that the tension is greater than 10 N, the adjustable cylinder drives the tension adjusting roller to move upward to reduce the tension; when the tension is less than 5 N, the adjustable cylinder drives the tension adjusting roller to move downward to increase the tension, thus realizing automatic tension adjustment. The tension adjusting roller is made of stainless steel with a diameter of 50 mm and a Teflon coating. The surface roughness is Ra0.4 to prevent scratching the FPC surface. The parallelism error of the tension adjusting roller is ≤0.01 mm / m to ensure uniform tension during FPC conveying. The guiding mechanism includes guide rollers and limiting blocks. The guide rollers are made of aluminum alloy with a diameter of 40 mm and an anodized surface. The parallelism error of the guide rollers is ≤0.01 mm / m. There are 4 guide rollers, which are respectively arranged at the feed end, the middle position and the discharge end of the conveyor belt to guide the FPC and prevent the FPC from shifting laterally during the conveying process. The limiting blocks are made of nylon to avoid scratching the FPC surface. The spacing of the limiting blocks is adjustable, with an adjustment range of 100-800 mm. In this embodiment, the spacing is adjusted to 500 mm to match the width of the FPC, ensuring that the FPC remains in the center position during transportation.

[0032] Multidimensional visual acquisition module: The multi-dimensional vision acquisition module is used to acquire real-time image information of the Mark points on the FPC surface and capture the positional deviation data of the FPC. Because the FPC surface has copper foil, it is prone to reflection, and the Mark points are printed relatively lightly, making the edges easily blurred. Therefore, the multi-dimensional vision acquisition module in this embodiment is specifically configured as follows: The CCD camera uses two 5-megapixel global shutter cameras, model Baslerac A2440-75um, with a resolution of 2448×2048 pixels, a frame rate of 30 frames / second, and an adjustable exposure time ranging from 1 to 100 microseconds. In this embodiment, the exposure time is set to 20 microseconds, which can quickly capture the Mark point image of the moving FPC and avoid image blurring and ghosting caused by FPC movement. Two CCD cameras are symmetrically arranged 200 mm in front of the die-cutting base. The camera shooting direction is perpendicular to the FPC surface, and the shooting range completely covers the two Mark point areas on the FPC surface. The two Mark points are 200 mm apart and are located at both ends of the FPC. They are used to calculate the translational deviation and angular deviation of the FPC. The dual telecentric lens uses a high-precision optical lens, model OPT-2014-50, with a distortion rate of <0.1%, a focal length of 25 mm, and a working distance of 200 mm. It can effectively eliminate lens distortion and perspective error, ensuring the authenticity and accuracy of Mark point imaging. Even if there is a slight height difference (≤0.05 mm) on the FPC surface, it can still guarantee the detection accuracy of the Mark point center coordinates. The high-brightness coaxial light source uses a red LED light source with a wavelength of 650 nanometers. The brightness is adjustable, with an adjustment range of 100-1000 candela / square meter. In this embodiment, the brightness is set to 500 candela / square meter. The light source is arranged coaxially with the camera and lens, which can effectively filter out the reflective interference of the copper foil on the FPC surface, enhance the contrast between the Mark point and the background, and make the Mark point edge clearer, which is convenient for subsequent identification and positioning. The image acquisition card uses a high-speed PCIe interface, model Matrox Soliose A / 4, with a transmission rate of ≥10 gigabits per second. It supports simultaneous acquisition from two cameras with an acquisition latency of <10 milliseconds, enabling it to quickly and losslessly transmit image information acquired by two CCD cameras to the central control unit, ensuring the real-time performance of deviation detection. The vision support adopts an adjustable aluminum alloy bracket with a height adjustment range of 300-800 mm. In this embodiment, the height adjustment is 500 mm, and the angle adjustment range is ±15°. The bracket has strong structural rigidity and vibration error ≤0.001 mm. It is used to fix the CCD camera, lens and light source. After installation, it is calibrated by a level and calibration tools to ensure that the camera shooting direction is perpendicular to the FPC surface. The color mark sensor uses a high-precision fiber optic color mark sensor, model KeyenceIV2 series, with a detection accuracy of ±0.01 mm and a response speed of <10 milliseconds. It is installed 120 mm in front of the CCD camera to detect whether the Mark point area on the FPC has reached the camera's shooting position. When the Mark point area is detected to be in place, a trigger signal is sent to the central control unit to control the CCD camera to take pictures synchronously, ensuring accurate timing of image acquisition and avoiding recognition errors caused by deviations in shooting timing.

[0033] Correction execution module: The alignment module is the core execution component of the system. It adopts a UVW three-axis linkage alignment platform, which is specifically selected and debugged to address the characteristics of FPC flexible circuit boards, such as easy stretching and high positioning accuracy requirements. The specific configuration is as follows: The UVW three-axis linkage alignment platform uses the UVW-XXL type alignment platform, which includes a platform base, motion table, three sets of servo motors, three sets of ball screws, sliding unit and protective mechanism. The platform adopts a planar parallel mechanism design, which is compact and rigid, and is suitable for high-speed and high-precision alignment requirements. The platform base is made of rigid cast iron with a thickness of 60 mm. The surface of the base has undergone aging treatment and precision grinding, with a flatness error of ≤0.005 mm / m. The bottom of the base is equipped with shock-absorbing pads made of rubber with a thickness of 10 mm, which are used to reduce the impact of vibration on positioning accuracy during equipment operation. The motion table is made of high-strength aluminum alloy with an anodized surface. The flatness error is ≤0.005 mm / m. The table size is 500×500 mm, which is compatible with the size of the FPC. The motion table is equipped with a vacuum adsorption material fixing mechanism, which uses vacuum suction cups to adsorb the FPC. The adsorption pressure is 0.03-0.05 MPa, which can fix the FPC and prevent it from shifting during the correction movement, while also avoiding excessive adsorption pressure that could cause the FPC to deform. The three servo motors are 0.75 kW AC servo motors, model Panasonic MSME082G1U, with a speed range of 0-5000 rpm, a positioning accuracy of ±1 pulse, and a pulse equivalent of 0.001 mm / pulse. The three motors are arranged symmetrically at 120° on the platform base and connected to the ball screw via couplings. The couplings are flexible couplings, model LK25, which can effectively buffer the impact during motor start-up and shutdown, protecting the ball screw and motor. The three sets of ball screws are high-precision ball screws, model THKBK12, with a lead of 5 mm, a precision class of C3, and a repeatability of ±0.002 mm. The ball screw surface is coated with high-temperature lubricating grease, model Molykote3402, to reduce wear and extend service life. The ball screws work in conjunction with the sliding unit to convert the rotational motion of the motor into linear motion. The sliding unit uses a cross roller guide, model THKVR3-600X16Z. The parallelism error of the guide is ≤0.001 mm / m, the coefficient of friction is ≤0.001, it has strong load-bearing capacity, smooth movement, and no jamming. It is used to guide the movement direction of the motion table and ensure the accuracy of three-way movement. The protective mechanism adopts an accordion-style dust cover with an IP65 protection rating, which can effectively prevent dust, debris and cutting fluid from entering the platform and affecting the motion accuracy of the ball screw and guide rail. The dust cover can extend and retract synchronously with the moving table surface without affecting the platform's motion range. In this embodiment, the maximum travel of the UVW three-axis linkage alignment platform is ±5 mm in the X direction and ±5 mm in the Y direction, the maximum rotation angle in the θ direction is ±5°, the response speed is <50 milliseconds, and the repeatability is ±0.003 mm. It can quickly and accurately complete the deviation compensation action of FPC and meet the high precision and high speed requirements of FPC die cutting.

[0034] Central control unit: The central control unit is the core of the system and is electrically connected to the material conveying module, multi-dimensional vision acquisition module, deviation correction execution module, human-machine interaction module, alarm module, and safety protection module. It is used to achieve coordinated control and closed-loop regulation of the various modules. Considering the high-speed and high-precision requirements of FPC die-cutting, the specific configuration is as follows: The hardware module includes an FPGA chip, motion controller, CPU processor, memory, hard disk, EtherCAT bus module, and input / output module; The FPGA chip used is the EP4CE15F23C8N model, with an operation speed of ≥100 MHz. It is used to accelerate the image processing algorithm, reduce the image processing time, and ensure the real-time performance of deviation detection, especially the fast operation of the "coarse positioning and sub-pixel fine positioning" algorithm. The motion controller adopts a high-precision motion controller based on the EtherCAT bus, model Beckhoff CX5140, with a communication cycle set to 1 millisecond. It supports multi-axis linkage control and can accurately control the motion of the UVW three-axis linkage alignment platform to achieve synchronous coordination of three-way motion and ensure the accuracy of deviation compensation. The CPU processor is an Intel Core i5-12400 model with a clock speed of ≥2.5 GHz and a cache of ≥18 megabytes. It is used for overall system control and scheduling, running system software and applications, and processing data transmitted by various modules. The system uses DDR4 memory with a capacity of 16 gigabytes to store temporary data, image data, and deviation data during system operation, ensuring smooth system operation and avoiding lag caused by insufficient memory. The hard drive uses a 512 gigabyte SSD solid-state drive, model Samsung 870EVO, which is used to store system programs, algorithm models, calibration data, production data and fault logs. It has fast read and write speeds, and the data storage is safe and stable, which facilitates subsequent data traceability and analysis. The EtherCAT bus module uses an industrial-grade bus interface, model Beckhoff EK1100, with a communication rate of ≥100 Mbps. It supports high-speed communication with devices such as servo drives, image acquisition cards, and sensors, with a communication latency of <1 millisecond, ensuring fast and accurate command transmission. The input / output module adopts an industrial-grade I / O module, model Beckhoff EL1088, with 32 input / output interfaces. It supports digital and analog input / output and is used to connect external devices such as color mark sensors, tension sensors, alarms, operation panels, and safety light curtains to realize signal input and output. The software modules include operating system, image processing software, motion control software, human-computer interaction software, data storage software, and fault diagnosis software. These software modules work together to realize the various control functions of the system. The operating system uses Windows 10 IoT Enterprise, which is highly stable, supports real-time control, and can meet the real-time requirements of high-speed die-cutting. The image processing software uses a dedicated image processing software developed based on OpenCV, which integrates algorithms such as image noise reduction, image enhancement, image binarization, edge extraction, template matching, and subpixel localization. It can quickly process Mark point images acquired by CCD cameras, calculate deviation data, and has a processing speed of ≥30 frames / second. The motion control software is used to control the motion of the UVW three-axis linkage alignment platform and material conveying module. It integrates coordinate mapping algorithm, material deformation compensation model and PID adjustment algorithm. It can calculate motor pulse commands based on deviation data, drive servo motor to move, and realize deviation compensation. Human-computer interaction software is used to enable operators to interact with the system, control the display and operation of the industrial touch screen, display information such as system operating status, die-cutting parameters, and deviation data in real time, and support operators to input parameters and modify settings. Data storage software is used to store calibration data, production data, fault logs, alarm information, etc., and supports data querying, exporting and deleting, which facilitates subsequent traceability and analysis; The fault diagnosis software is used to monitor the operating status of each module of the system in real time, identify equipment faults, analyze the causes of faults, generate fault diagnosis reports, and prompt operators to handle the faults. The fault diagnosis accuracy rate is ≥95%.

[0035] Human-computer interaction module and alarm module: The human-machine interface module includes a 12-inch high-definition industrial touch screen and physical operation buttons. The industrial touch screen has a resolution of 1920×1080 pixels, supports multi-touch, and has a response speed of <50 milliseconds. The touch screen displays the system's operating status (running, stopping, alarm), die-cutting parameters (die-cutting cycle time, conveying speed, tension), deviation data (X-axis, Y-axis, θ-axis deviation), residual statistics, and other information in real time. Operators can input parameters such as the material, thickness, and width of the FPC through the touch screen, modify die-cutting parameters such as die-cutting cycle time and conveying speed, and call up calibration data, fault logs, etc. The physical operation buttons include start, stop, emergency stop, reset, and calibration buttons. They are industrial-grade waterproof buttons with a lifespan of ≥1 million presses. The emergency stop button is a red mushroom-shaped button that can immediately cut off the system power and stop all equipment operation when pressed, for use in emergency equipment shutdown. The alarm module includes an audible and visual alarm and an alarm indicator light. The alarm volume of the audible and visual alarm is adjustable to 80 decibels, and the alarm light is a red flashing light with a flashing frequency of 1 time / second. When the system malfunctions (such as Mark point recognition failure, compensation failure, equipment failure, etc.), the audible and visual alarm will immediately issue an alarm signal, and the alarm indicator light will light up at the same time. The alarm information will be displayed on the industrial touch screen simultaneously, making it easy for operators to quickly understand the abnormal situation. In addition, the alarm module supports remote transmission of alarm signals, transmitting alarm information to the operator's mobile terminal via Ethernet, prompting the operator to handle abnormal situations in a timely manner. The alarm information includes detailed information such as the type of abnormality, the time of occurrence of the abnormality, and the location of the abnormality.

[0036] Security protection module: The safety protection module includes a protective shell, safety light curtain, emergency stop circuit, and leakage protection device. The protective shell is made of cold-rolled steel plate with a thickness of 2.5 mm and the surface is treated with electrostatic powder coating, making it corrosion-resistant and wear-resistant. The protective shell encloses moving parts such as the material conveying module and the correction execution module, preventing operators from coming into contact with the moving parts and getting injured. The protective shell is equipped with a transparent observation window made of tempered glass with a thickness of 6 mm and a light transmittance of ≥90%, which allows operators to observe the real-time status of FPC conveying, die-cutting, and correction. The safety light curtain is an infrared safety light curtain, model SICKC40S-090303A11, which is installed on both sides of the feed inlet and discharge outlet of the die-cutting machine. The detection height of the light curtain is 800 mm, the detection accuracy is 15 mm, and the response speed is <10 milliseconds. When the operator's hand or other body parts enter the detection area, the safety light curtain immediately sends a signal to the central control unit. The central control unit immediately cuts off the power to the die-cutting machine and the material conveying module, stopping all operations. The emergency stop circuit adopts a dual redundancy design. In addition to the physical emergency stop button, emergency stop buttons are also set at the feed end, discharge end and operation panel of the protective shell to ensure that the operator can quickly press the emergency stop button from any position to stop the equipment. The response time of the emergency stop circuit is less than 5 milliseconds. The leakage current protection device adopts an industrial-grade leakage current protector, model Schneider E823 series, with a leakage current of ≤30 mA and a leakage action time of ≤0.1 seconds. When leakage occurs in the equipment, the leakage current protection device immediately cuts off the system power supply to prevent leakage from causing equipment damage or electric shock to operators. Example

[0037] This system is applied to an FPC flexible circuit board die-cutting production line.

[0038] Hardware Architecture: Vision Unit: Two 5-megapixel global shutter CCD cameras are mounted 200mm in front of the die-cutting unit. The lenses are dual telecentric lenses with a distortion rate of <0.1%. High-brightness red coaxial light is used as the light source to filter out glare interference from the copper foil on the FPC surface. Actuation Mechanism: The alignment platform is a UVW-XXL type, driven by three 750W AC servo motors. The platform's maximum travel is ±5mm, and the maximum rotation angle is ±5°. Controller: An EtherCAT bus-based motion controller is used, with a communication cycle set to 1ms.

[0039] Correction Process: Image Acquisition: When the color mark sensor on the material detects the arrival of the Mark point area, it triggers the camera to take a picture. Algorithm Processing: The FPGA module in the controller first performs a 5x5 Gaussian filter on the image to remove noise. The Sobel operator is used to extract edges and perform sub-pixel fitting to obtain the center coordinates (x_1, y_1) and (x_2, y_2) of the Mark point. The slope k of the line connecting the two points is calculated and compared with the slope k_0 of the standard template to obtain the angle deviation Δθ. The coordinates of the midpoints of the two points are calculated and compared with the standard center to obtain the translational deviations ΔX and ΔY. Coordinate Transformation and Execution: The controller calls the pre-stored affine transformation matrix.

[0040] The pulse increments of the three motors are calculated and sent to the servo driver via the EtherCAT bus.

[0041] Action execution: The servo motor drives the UVW platform to complete the displacement adjustment of the supporting mesh plate within 20ms.

[0042] Die-cutting: The spindle of the die-cutting machine presses down to complete high-precision die-cutting.

[0043] Anomaly Handling: During the production process, if the vision system detects that a Mark point is missing during printing, the system will automatically call the data from the previous die as a reference and combine it with the count value of the traction shaft encoder to calculate (interpolation logic), and command the platform to move to the theoretical position for die cutting. At the same time, a yellow alarm will be issued to avoid machine stoppage and scrapping of the entire roll of material. Example

[0044] Building upon the aforementioned hardware, the software algorithm incorporates Electronic Cam (E-CAM) functionality. While the conveyor belt remains running, the UVW platform not only performs correction actions but also superimposes an X-axis speed component synchronized with the conveyor belt speed. The die closes as it "chases" the material, at which point the material and die are relatively stationary. After die-cutting, the platform quickly returns to its origin to await the next cycle. This mode increases production efficiency by 40%.

[0045] In summary, this invention achieves high-precision die-cutting positioning and correction under complex working conditions through deep coupling of hardware and software, and has extremely high industrial application value. Example

[0046] The calibration stage steps in the correction method described in this invention are performed as follows: Step 1.1: Equipment installation and calibration. Adjust the relative positions of the material conveying module, multi-dimensional vision acquisition module, deviation correction execution module, and die-cutting machine to ensure that the FPC conveying direction is parallel to the die-cutting direction of the die-cutting machine, with a parallelism error ≤0.01 mm / m; adjust the positions of the two CCD cameras to ensure that the camera's shooting range completely covers the two Mark point areas on the FPC, and the shooting direction is perpendicular to the FPC surface, with a perpendicularity error ≤0.01°; adjust the position of the UVW three-axis linkage alignment platform to ensure that the platform's movement range matches the FPC's deviation range, and that the platform surface is parallel to the die-cutting blade of the die-cutting machine, with a parallelism error ≤0.005 mm / m. Step 1.2: Vision system calibration. A standard checkerboard calibration board (checkerboard size 10×10 mm) is used. The calibration board is fixed on the motion table of the UVW platform. The platform is controlled to move the calibration board at different positions and angles, and four images of the calibration board are taken at each position, for a total of 80 images. The captured images are transmitted to the central control unit. The image processing software calculates the camera's intrinsic parameters (focal length, principal point coordinates) and extrinsic parameters (relative position of the camera and the platform), eliminates the influence of lens distortion, and establishes a visual coordinate system. After calibration, the camera's intrinsic parameters are: focal length 25 mm, principal point coordinates (1224, 1024) pixels; extrinsic parameters: vertical distance between the camera and the platform 200 mm, horizontal offset 0 mm. Step 1.3: Mechanism Calibration. Place a high-precision calibration block (with two standard Mark points on the calibration block, the center coordinates of which are known, namely (100.000 mm, 100.000 mm) and (300.000 mm, 100.000 mm)) on the motion table of the UVW platform. Control the platform to move in the X direction, Y direction, and rotate in the θ direction, with each movement or rotation increment being 0.001 mm or 0.01°. Record the pixel coordinates of the calibration block Mark points acquired by the CCD camera at different positions. Match the acquired pixel coordinates with the actual physical coordinates of the platform's movement. Use the least squares method to fit and establish the mapping relationship between the visual coordinate system and the mechanism coordinate system. Determine the geometric rotation center coordinates of the UVW three-axis linkage alignment platform as (200.000 mm, 200.000 mm). Record the corresponding parameters of the rotation center in the visual coordinate system and the mechanism coordinate system. Step 1.4: Error calibration. Collect 15 sets of calibration data at different positions and angles, calculate visual detection error and mechanism motion error, and correct the error by fitting the error compensation curve. Store the correction coefficient in the memory of the central control unit. After correction, the system error is ≤0.005 mm. Step 1.5: Calibration data storage. The calibration data, such as the intrinsic and extrinsic parameters of the vision system, the mapping relationship between vision and mechanism, the coordinates of the rotation center, and the error correction coefficient, are uniformly stored in the SSD solid-state drive of the central control unit to establish a calibration data archive, and the calibration time, calibration personnel, calibration environment (temperature 20℃, humidity 50%RH) are marked. Step 1.6: Calibration and Verification. Control the UVW platform to move the calibration block randomly in the X and Y directions and rotate it in the θ direction. The movement and rotation range is within the normal operating range of the platform. Acquire images of the Mark points of the calibration block through the CCD camera, calculate the pixel coordinate deviation of the Mark points, convert it into physical domain deviation by combining the calibration data, and compare it with the deviation of the actual movement of the platform to verify the calibration accuracy. After verification, the calibration accuracy is 0.003 mm, which meets the requirements. The calibration stage is completed, and the system enters the standby state.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A die-cutting positioning and correction system, characterized in that, The system includes: The material conveying module is used to carry and convey the rolls or sheets to be die-cut along a preset path; A multi-dimensional vision acquisition module is installed at the front end of the die-cutting station to capture image data of material surface feature marks in real time. The correction execution module is located between the material conveying module and the die-cutting mold, and includes a UVW three-axis linkage alignment platform for adjusting the material position or the mold position. The central control unit is connected to the multi-dimensional vision acquisition module and the correction execution module respectively; The central control unit has a built-in coordinate mapping algorithm engine, which is configured to convert the pixel coordinate system in the image data into the physical pulse coordinate system of the correction execution module, and calculate the current lateral deviation, longitudinal deviation and angular rotation deviation of the material, and drive the UVW three-axis linkage alignment platform to perform reverse compensation motion.

2. The die-cutting positioning and correction system according to claim 1, characterized in that, The multidimensional vision acquisition module includes at least two sets of high-speed industrial cameras arranged in a linear fashion. Each set of cameras is equipped with a telecentric lens and an adjustable coaxial composite light source. The exposure trigger signal of the high-speed industrial camera is synchronized with the encoder signal of the material conveying module to achieve fixed-distance trigger acquisition and eliminate the influence of conveying speed fluctuations on image stretching.

3. The die-cutting positioning and correction system according to claim 1, characterized in that, The UVW three-axis linkage alignment platform of the correction execution module consists of a base, a movable table and a drive mechanism. The drive mechanism includes three sets of servo motors arranged in a circular or parallel pattern. Each set of servo motors is connected to the movable table through a precision ball screw and a cam follower. Through the differential motion of the three axes, the X-axis translation, Y-axis translation, and θ-axis rotation in the plane are realized simultaneously.

4. The die-cutting positioning and correction system according to claim 1, characterized in that, The central control unit includes an FPGA image preprocessing unit and an ARM motion control unit; The FPGA image preprocessing unit is used to perform Gaussian filtering noise reduction and Sobel edge detection on the original image, and extract the sub-pixel level contour features of the Mark points; The ARM motion control unit is used to receive the processed contour coordinates and calculate the geometric center of the Mark point based on the least squares fitting method.

5. The die-cutting positioning and correction system according to claim 1, characterized in that, It also includes a secondary vision inspection module located at the rear of the die-cutting station; The secondary vision inspection module is used to acquire images of the waste skeleton or finished product after die-cutting, calculate the residual deviation value between the die-cutting line and the printing texture, and send the residual deviation value as a feedback signal to the central control unit, which then corrects the compensation parameters for the next cycle through a PID algorithm.

6. A die-cutting positioning and correction method for the system as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Reference calibration: During the system initialization phase, establish the affine transformation matrix between the visual pixel coordinate system and the UVW alignment platform physical coordinate system. S2, Feature Acquisition: When the material moves to the detection area, the multi-dimensional vision acquisition module is triggered to acquire a local image containing the Mark points; S3. Deviation Calculation: Identify the actual coordinates of the Mark points in the image, compare them with the preset standard die-cutting coordinates, and calculate the current deviation vector (ΔX, ΔY and Δθ). S4. Motion Compensation: Based on the affine transformation matrix, the deviation vector is converted into the target pulse increment of the UVW triaxial motor, driving the alignment platform to complete the reverse displacement before the die-cutting action occurs. S5. Die-cutting execution: After the alignment platform stabilizes, the die-cutting mold is triggered to press down or close.

7. The die-cutting positioning and correction method according to claim 6, characterized in that, In step S1, the process of establishing the affine transformation matrix is ​​as follows: the UVW alignment platform is controlled to move along the X-axis and Y-axis and rotate along the θ-axis by a preset distance, the vision module records the displacement change of the Mark point in the image, and the rotation center coordinates and scaling factor are solved by linear regression equation.

8. The die-cutting positioning and correction method according to claim 6, characterized in that, In step S3, the deviation calculation employs a multi-level matching strategy: First, perform a downsampling pyramid search to coarsely locate the Mark points; Then, fine positioning is achieved by performing gray-level matching based on normalized cross-correlation within the coarse positioning area; If a Mark point is obscured or damaged, causing the matching degree to fall below the preset threshold, the relative position relationship of neighboring Mark points will be automatically used for interpolation estimation.

9. The die-cutting positioning and correction method according to claim 6, characterized in that, In step S4, the motion compensation employs a feedforward and predictive control strategy: The system collects real-time speed and tension fluctuation data of material conveying and establishes a material elastic deformation model; Based on the calculated geometric deviation, the elastic deformation compensation caused by tension fluctuation is superimposed to correct the final motor pulse output.

10. The die-cutting positioning and correction method according to claim 6, characterized in that, The method also includes an anomaly handling mechanism: if the calculation deviation exceeds the system's maximum correction stroke for N consecutive cycles, the system determines that the printing jump distance or joint is abnormal, and automatically triggers a shutdown alarm or executes a jump-cut command, where N is a preset positive integer.

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