Adaptive humidity conditioning carton printing apparatus and method of carton printing thereof

Abstract

The application discloses a self-adaptive humidity adjusting carton printing device and a carton printing method thereof, and belongs to the technical field of carton printing equipment and printing process, and aims to solve the problems of high printing waste rate, high labor cost and raw material waste caused by the response lag and low precision of manual judgment and adjustment. The application triggers the partition compensation through full-width scanning of 3 groups or more sensors and a humidity difference of ±0.5%, avoids the problems of dirty image in high-humidity areas, ink layer falling off in low-humidity areas and brittle cracking of paperboard, and ensures that the full-width printing consistency deviation is less than or equal to 2%. The closed-loop correction mechanism is used to ensure that the ink viscosity, cylinder pressure, drying temperature, paper feeding speed and ink layer adhesion force meet the standards, and the paperboard exceeding the standards is automatically removed when the humidity is greater than 14% or less than 6%, and the production is restored after re-inspection, so that the printing quality is significantly improved, and the defect rate is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of cardboard box printing equipment and printing technology, and more specifically, to an adaptive humidity-controlled cardboard box printing apparatus and a cardboard box printing method thereof. Background Technology

[0002] In cardboard printing production, cardboard humidity is one of the key factors affecting print quality. During the conventional cardboard printing process, cardboard is easily affected by ambient temperature and humidity during production, storage, and transportation, leading to fluctuations in humidity within the same batch or even the same sheet of cardboard, typically ranging from 5% to 15%. When the cardboard humidity is too high, the cardboard is prone to softening, paper feeding misalignment, and misregistration, while the ink drying speed slows down, easily causing "smudges" and "ink layer adhesion." When the cardboard humidity is too low, the cardboard becomes brittle and prone to cracking, and surface static electricity increases, making it easier to attract ink dust, resulting in "dirty printing," and ink adhesion also decreases significantly.

[0003] Existing cardboard box printing equipment typically employs a "fixed parameter printing" mode, meaning that parameters such as ink viscosity, pressure, and drying temperature are preset based on experience, making it impossible to adjust in real time according to fluctuations in cardboard humidity. While some equipment is equipped with simple humidity detection functions, these can only detect a single point, failing to cover the entire surface, and lack closed-loop feedback control. They rely on manual judgment and adjustment, resulting in lag and low accuracy, leading to a high rate of printing rejects, while also increasing labor costs and wasting raw materials.

[0004] Therefore, a new solution is needed to address this problem. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to solve the problems of poor printing quality, high scrap rate, and low automation caused by fluctuations in cardboard humidity in existing cardboard printing. It provides an adaptive humidity-regulating cardboard printing device and a cardboard printing process based on the device. The two are deeply coupled, with the device providing hardware support for the process and the process achieving parameter control through the device.

[0006] The present invention achieves the above objectives through the following technical solution: an adaptive humidity-adjustable carton printing device, comprising a front-end humidity detection module, a central control module, a printing execution adjustment module, and a human-machine interaction module, wherein each module is communicatively connected to the central control module and is integrated as a whole on the frame of the carton printing machine;

[0007] The front-end humidity detection module is fixed to the front end of the paper feeding table of the printing press and is used to collect the humidity data of the entire paperboard in real time and transmit it to the central control module.

[0008] The central control module is used to receive humidity data from the front-end humidity detection module and generate adjustment instructions based on the preset "humidity-printing parameter" mapping algorithm. At the same time, it corrects the parameter deviation of the printing execution adjustment module through closed-loop control logic.

[0009] The core feature of the mapping algorithm is: dividing the paperboard into at least three intervals based on the average humidity of the entire surface, matching the corresponding ink viscosity, printing plate-rubber blanket pressure, drying temperature and paper feeding speed for each interval, and when the deviation of the humidity of each area from the average humidity exceeds a preset threshold, the printing parameters of the deviation area are locally compensated.

[0010] The printing execution adjustment module includes:

[0011] An automatic ink adjustment subsystem, integrated into the ink tank of a printing press, is used to adjust the viscosity of the ink;

[0012] The pressure regulation subsystem is installed between the printing plate cylinder and the blanket cylinder of the printing press and is used to adjust the cylinder contact pressure.

[0013] The intelligent drying subsystem is installed in the drying channel at the paper delivery end of the printing press to adjust the drying temperature and airflow.

[0014] The paper feed speed control subsystem is adapted to the paper feed motor of the printing press and is used to adjust the paper feed speed and eliminate static electricity.

[0015] Each subsystem is connected to the central control module to receive target parameter instructions and automatically perform adjustments;

[0016] The human-machine interaction module communicates with the central control module and is used for process status monitoring, abnormal alarms, and data storage.

[0017] During operation, the cardboard enters the paper feeding table from the stacking table. The front-end humidity detection module first collects full-width humidity data, the central control module generates target parameters based on the data, the printing execution adjustment module adjusts the printing parameters according to the instructions, and the human-machine interaction module monitors the status synchronously.

[0018] The present invention is further configured such that: the front-end humidity detection module includes three or more sets of humidity sensors evenly distributed along the width direction of the paper feed table, and the humidity sensor probes are perpendicularly oriented toward the paperboard surface;

[0019] The humidity data of the cardboard is collected in real time and transmitted to the central control module through the front-end humidity detection module.

[0020] The present invention is further configured such that the central control module includes:

[0021] The PLC main control unit is used for filtering, calibration, and parameter matching logic operations of humidity data.

[0022] The parameter database unit pre-stores the "humidity-printing parameter" mapping algorithm, the threshold parameters of the local humidity compensation logic, and the response time parameters of the closed-loop correction.

[0023] The closed-loop control unit is an eight-channel analog input module used to collect the actual operating parameters of each system fed back by the printing execution adjustment module in real time. The analog channels of the closed-loop control unit are respectively connected to the parameter detection sensor signals in different subsystems of the printing execution adjustment module to receive the analog signals output by the sensors.

[0024] The present invention is further configured such that the "humidity-printing parameter" mapping algorithm pre-stored in the parameter database unit is specifically:

[0025] When the average humidity of the entire paperboard surface is between 7% and 8%, it is considered a low humidity range, corresponding to an ink viscosity of 3000 mPa·s, a printing plate-rubber blanket pressure of 10 kN / m, a drying temperature of 50℃, and a paper feeding speed of 10,000 sheets / hour.

[0026] The optimal humidity range is when the average humidity of the entire paperboard surface is between 9% and 11%, which corresponds to an ink viscosity of 2800 mPa·s, a printing plate-rubber blanket pressure of 9 kN / m, a drying temperature of 55℃, and a paper feeding speed of 12000 sheets / hour.

[0027] When the average humidity of the entire paperboard surface is between 12% and 13%, it is considered a high humidity range, corresponding to an ink viscosity of 2500 mPa·s, a printing plate-rubber blanket pressure of 8 kN / m, a drying temperature of 65℃, and a paper feeding speed of 11,000 sheets / hour.

[0028] The "humidity-printing parameter" mapping algorithm supports manual updates via the touchscreen of the human-computer interaction module or importing optimized parameters via the cloud interface.

[0029] The present invention is further configured such that the automatic ink adjustment system includes:

[0030] A miniature diluent pump is installed on top of the ink tank of a printing press and connected to the ink tank via a silicone tube;

[0031] A viscosity sensor, whose probe is inserted into the ink tank, is used to provide real-time feedback of ink viscosity data to the central control module;

[0032] This forms a closed loop for viscosity control, consisting of "detection-adjustment-feedback".

[0033] The present invention is further configured such that the pressure regulating subsystem includes:

[0034] A pneumatic pressure valve is installed in a bracket between the printing plate cylinder and the blanket cylinder, and is connected to the original air source of the printing press through a pressure-resistant air pipe. The pneumatic pressure valve is also connected to the central control module.

[0035] The pressure sensor, fixed to the side of the roller bearing housing, detects the contact pressure between the printing plate cylinder and the blanket cylinder in real time and feeds it back to the central control module.

[0036] The present invention is further configured such that the intelligent drying subsystem includes:

[0037] Several electric heating tubes are provided and are evenly distributed along the top and both sides of the drying channel at the paper receiving end of the printing press.

[0038] Variable frequency fans are symmetrically installed on both sides of the drying channel to adjust the hot air speed;

[0039] Temperature and humidity sensors are installed at both the inlet and outlet of the drying channel at the paper receiving end of the printing press to feed back environmental data to the central control module.

[0040] The present invention is further configured such that: the paper feeding speed control subsystem includes:

[0041] Servo motor driver, adapted to the power of the paper feeding motor in the paper feeding system of a printing press, controls the speed of the paper feeding motor through pulse signals;

[0042] An antistatic eliminator is used to eliminate static electricity generated by low-humidity cardboard and is installed at the end of the paper feed table.

[0043] An incremental encoder is installed on the shaft end of the paper feed motor via a coupling to collect the actual speed of the paper feed motor in real time and to feed the actual speed of the motor back to the central control module.

[0044] The pneumatic pusher plate, installed on the side of the paper feeding table, is connected to the central control module and is used to push cardboard with excessive moisture to the waste collection tank.

[0045] The present invention is further configured such that the human-computer interaction module includes:

[0046] The touchscreen is connected to the central control module and is used to display real-time humidity, current printing parameters, and device operating status.

[0047] The alarm unit is an audible and visual alarm that automatically activates when the front-end humidity detection module detects that the paperboard humidity is >14% or <6%, and then links the paper feeding system to pause via the central control module.

[0048] The data storage unit stores the humidity data, matching printing parameters, closed-loop correction records, and scrap rate data of each batch of cardboard in real time, and is equipped with a cloud interface.

[0049] A carton printing process using the above-mentioned adaptive humidity-controlled carton printing apparatus includes the following steps:

[0050] S1: The cardboard to be printed is conveyed to the printing operation area through the paper feeding table of the printing press. Before the cardboard enters the printing unit, multiple humidity sensors of the front-end humidity detection module are activated to scan and detect the cardboard across the width of the cardboard, collect humidity data of each area of ​​the cardboard in real time, and transmit the detection data to the PLC main control unit of the central control module.

[0051] S2: After receiving the humidity detection data from S1, the central control module's main control unit first filters and calibrates the data, calculates the average humidity value of the entire paperboard surface and the maximum humidity deviation value of each area, and then calls the "humidity-printing parameter" mapping algorithm of the parameter database unit to match the parameters.

[0052] If the maximum humidity deviation is ≤ ±0.5%, directly match the target printing parameters corresponding to the average humidity value;

[0053] If the maximum humidity deviation is greater than ±0.5%, the local humidity compensation logic is invoked. The width of the cardboard is divided into multiple detection areas according to the humidity sensor layout. The target printing parameters for each area are matched separately based on the humidity difference. Specifically:

[0054] If the difference between the humidity value of a certain detection area and the average humidity value of the entire paperboard is ≥0.8%, the central control module sends an instruction to the intelligent drying subsystem corresponding to that area to increase the drying temperature by 5-8℃. At the same time, it sends an instruction to the pressure regulation subsystem to reduce the printing plate-rubber blanket pressure by 0.5-1kN / m, while keeping the ink viscosity and paper feeding speed unchanged.

[0055] If the difference between the humidity value of a certain detection area and the average humidity value of the entire paperboard is ≤-0.8%, the drying temperature remains unchanged, the printing plate-rubber blanket pressure remains unchanged, the central control module sends an instruction to the automatic ink adjustment subsystem to increase the ink viscosity by 100-200 mPa·s, and at the same time sends an instruction to the paper feeding speed adjustment subsystem to reduce the paper feeding speed by 500-800 sheets / hour.

[0056] If the difference between the humidity value of a certain detection area and the average humidity value of the entire paperboard surface is within ±0.8%, the drying temperature, printing plate-rubber blanket pressure, ink viscosity and paper feeding speed remain unchanged.

[0057] S3: The central control module sends the target parameter instruction matched in S2 to the printing execution adjustment module, and each subsystem synchronously performs the adjustment.

[0058] S3a: Start the micro-diluent pump of the automatic ink adjustment system to inject diluent into the ink tank. The viscosity sensor collects the actual viscosity of the ink in real time and feeds it back to the central control module until the actual viscosity reaches the target value.

[0059] S3b: The contact pressure between the printing plate cylinder and the blanket cylinder is adjusted by the pneumatic pressure valve of the pressure regulation subsystem. The pressure sensor provides real-time feedback of the actual pressure until the pressure reaches the target value.

[0060] S3c: Controls the heating element of the intelligent drying subsystem to raise the temperature and the variable frequency fan to adjust the speed. Temperature and humidity sensors monitor the actual temperature and humidity data at the inlet and outlet of the drying channel in real time until the temperature of the drying channel reaches the target drying temperature.

[0061] S3d: Adjust the paper feeding speed through the servo driver of the paper feeding speed control subsystem, and the encoder feeds back the motor speed until the paper feeding speed reaches the target value. If the paperboard humidity is <8%, the static eliminator (11) is started synchronously to eliminate the static electricity of the paperboard.

[0062] S4: During the printing process, the central control module's closed-loop control unit continuously collects feedback from the printing execution adjustment module on ink viscosity, roller pressure, drying temperature, and paper feed speed, and compares the deviation with the target parameters.

[0063] If the deviation is ≤3%, maintain the current parameters;

[0064] If the deviation is greater than 3%, a correction command will be generated within 0.5 seconds. The correction command is as follows:

[0065] Ink viscosity deviation > ±3%: Adjust the thinner pump flow rate; for every 1% deviation exceeding the deviation, increase the flow rate by ±2%.

[0066] If the roller pressure deviation is > ±3%, adjust the pneumatic pressure valve output; for every 1% deviation exceeding the deviation, adjust the pressure by ±1%.

[0067] If the drying temperature deviation is > ±3℃: Adjust the heating element power; for every 1℃ deviation, adjust the power by ±3% or the fan speed by ±5%.

[0068] Paper feed speed deviation > ±1%: Adjust the servo drive frequency; for every 0.5% deviation, adjust the frequency by ±0.3Hz.

[0069] Correct the response time to ≤0.5 seconds, until the deviation is ≤3%;

[0070] S5: If S1 detects that the paperboard humidity is >14% or <6%, the central control module triggers an alarm and controls the paper feeding system to stop. The paperboard exceeding the standard is pushed to the waste bin by a pneumatic pusher. After the paperboard exceeding the standard is removed, the front-end humidity detection module re-inspects the subsequent paperboard. After confirming that the humidity is 8-12%, the paper feeding is resumed.

[0071] Compared with the prior art, the beneficial effects of the present invention are:

[0072] Firstly, by using three or more sensors to scan the entire surface and triggering zone compensation based on a humidity difference of ±0.5%, the system avoids issues such as image smudging in high humidity areas, ink layer peeling in low humidity areas, and paperboard brittleness. The overall printing consistency deviation is ≤2%. Furthermore, a closed-loop correction mechanism ensures that ink viscosity, roller pressure, drying temperature, paper feeding speed, and ink layer adhesion meet the standards. Additionally, the system automatically rejects paperboard with humidity >14% or <6%, and resumes production after re-inspection to prevent substandard paperboard from entering the printing process. This significantly improves printing quality and greatly reduces the defect rate.

[0073] Secondly, from humidity detection, parameter matching, zoning adjustment to closed-loop correction, there is no need for manual adjustment of printing parameters, reducing manual intervention time and adapting to high-speed production lines. At the same time, through automatic alarm + rejection + re-inspection recovery anomaly handling, there is no need for overall shutdown for troubleshooting, thus reducing downtime.

[0074] Third, the process is compatible with existing carton printing machines and is integrated with dedicated devices, avoiding the need for complete equipment replacement or large-scale modification, thus reducing production costs. Furthermore, combined with triple control of zone compensation, closed-loop correction, and anomaly rejection, the overall scrap rate is reduced from 3% to 5% in traditional processes to 0.5% to 1%, significantly reducing the waste of resources such as cardboard and ink. Attached Figure Description

[0075] Figure 1 A schematic diagram of an adaptive humidity-controlled carton printing device;

[0076] Figure 2 This is a schematic diagram of the pressure regulation subsystem;

[0077] Figure 3 This is a schematic diagram of the paper feeding speed control subsystem;

[0078] Figure 4 This is a process flow diagram of the present invention.

[0079] Reference numerals: 1. Humidity sensor; 2. Miniature diluent pump; 3. Viscosity sensor; 4. Pressure regulation subsystem; 5. Pneumatic pressure valve; 6. Pressure sensor; 7. Electric heating element; 8. Variable frequency fan; 9. Temperature and humidity sensor; 10. Servo motor driver; 11. Static eliminator; 12. Incremental encoder; 13. Pneumatic pusher. Detailed Implementation

[0080] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. In this description, it should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Obviously, the described embodiments are only some embodiments of the present invention, 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. Example

[0081] Adaptive humidity control carton printing equipment, such as Figures 1-3 As shown, the machine frame is integrated into the existing carton printing machine without modifying the main structure of the printing machine. It includes a front-end humidity detection module, a central control module, a printing execution adjustment module, and a human-machine interaction module. Each module is connected to the central control module via a Belden 3071F shielded cable. Through the coordinated operation of each module, a complete workflow of "data acquisition → data processing → parameter execution → closed-loop correction → status monitoring → anomaly handling" is formed, realizing the adaptive matching of "humidity-printing parameters" during the carton printing process, and ultimately ensuring stable printing quality under different humidity conditions.

[0082] The front-end humidity detection module serves as the data source for the process humidity. Fixed at the front of the printing press's paper feed table, it ensures data accuracy by activating detection when the cardboard is transported individually from the stacking table to the feed table, just as it is detached from the stacking constraints and its humidity is unaffected by the printing environment. Consequently, as the cardboard exits the stacking table, real-time humidity data across the entire cardboard surface is collected and transmitted to the central control module.

[0083] The front-end humidity detection module includes three or more humidity sensors 1 evenly distributed along the width of the paper feed table, avoiding the error of "local humidity representing the whole area" caused by single-point detection. The humidity sensor 1 uses an NDCCM710e multi-wavelength infrared moisture sensor with a detection accuracy of ±0.1% and a detection range of 0.1% to 40%. It can penetrate the surface of the cardboard to detect internal humidity, avoiding interference from surface dust and color. Furthermore, the probe of the humidity sensor 1 is perpendicular to the cardboard surface, with a spacing controlled between 28mm and 32mm to ensure unobstructed detection. It is also equipped with a dustproof and waterproof housing to enclose the humidity sensor 1. This housing is made of IP65-grade stainless steel and has a built-in air-cooling structure, adapting to the high dust and ink evaporation environment of the printing workshop and ensuring the effective use of the humidity sensor 1.

[0084] The collected full-width humidity data, including humidity values ​​for the left, center, and right areas, is transmitted to the central control module via an RS485 bus. The bus transmission rate is 115200bps with a delay of <0.1 seconds, which can match a high-speed printing production line with a capacity of 12,000 sheets per hour, ensuring that data transmission is synchronized with the board feeding rhythm without any lag.

[0085] The central control module is the core of the device and process. It is installed in the electrical control cabinet on the operating side of the printing press. It receives humidity data from the front-end humidity detection module and generates adjustment instructions based on the preset "humidity-printing parameter" mapping algorithm. At the same time, it corrects the parameter deviation of the printing execution adjustment module through closed-loop control logic.

[0086] The core feature of the mapping algorithm is: dividing the paperboard into at least three intervals based on the average humidity of the entire surface, matching the corresponding ink viscosity, printing plate-rubber blanket pressure, drying temperature and paper feeding speed for each interval, and when the deviation of the humidity of each area from the average humidity exceeds the preset threshold, the printing parameters of the deviation area are locally compensated.

[0087] The core feature of the closed-loop control logic is: to collect the actual parameters of the printing execution adjustment module in real time at a preset frequency, calculate the deviation from the target parameters, and generate a correction command within a limited time when the deviation exceeds a preset threshold, until the deviation drops to within the threshold.

[0088] The humidity range division rules, the parameter types corresponding to each range, the deviation threshold for local compensation, the closed-loop sampling frequency, the deviation threshold and the correction time are all pre-stored in the parameter database unit of the central control module, and are compatible with the sensor accuracy of the front-end humidity detection module and the execution accuracy of the printing execution adjustment module.

[0089] The central control module includes a PLC main control unit, a parameter database unit, and a closed-loop control unit. The PLC main control unit adopts a Siemens S7-1214C with an operation speed of 0.1μs / instruction. It can simultaneously process 3 sets of sensor data and 4 execution module instructions to realize the filtering, calibration, and parameter matching logic operations of humidity data.

[0090] The parameter database unit uses an 8GB embedded storage chip to pre-store the "humidity-printing parameter" mapping algorithm and local humidity compensation logic parameters. It supports manual updates via the human-computer interaction module or import of optimized parameters via the cloud interface. The optimized parameters must follow the core logic of "cardboard humidity range division + ink viscosity / pressure / temperature / speed linkage matching", mainly playing the role of algorithm storage and retrieval.

[0091] The closed-loop control unit uses an eight-channel analog input module of Siemens SM1231. It receives the "parameter signals" output by the sensors of each subsystem of the printing execution adjustment module through the eight-channel analog input module, and provides a matching signal interface for different types of sensors to collect the actual operating parameters of each system fed back by the printing execution adjustment module in real time.

[0092] The analog input module has a sampling frequency of 10Hz for parameters such as viscosity, pressure, and temperature, which means it samples 10 times per second. This is much higher than the parameter change rate of the printing press. For example, the ink viscosity change cycle is ≥1 second and the temperature change cycle is ≥5 seconds, which ensures that it can capture small fluctuations in parameters, such as viscosity changes of ±50mPa・s.

[0093] The encoder's pulse signal sampling frequency is set to 100kHz, which can accurately capture the speed changes of the paper feeding motor, such as a fluctuation of ±10 rpm. The converted paper feeding speed error is ≤50 sheets / hour, which meets the speed adjustment accuracy requirement of ±100 sheets / hour.

[0094] Each analog signal channel corresponds to one sensor, and the channels are independent of each other. For example, channel one is connected to viscosity sensor 3 and channel two is connected to pressure sensor 6 to avoid signal crosstalk. In addition, all sensor cables are twisted-pair shielded cables with single-end grounding of the shielding layer and grounding resistance ≤4Ω to avoid electromagnetic interference generated by workshop motors and frequency converters. The analog signal module and the central control module are installed in a metal electrical control cabinet, and the cabinet is grounded to further shield external interference.

[0095] The central control module performs "moving average filtering" on the collected raw data, such as taking the average of 5 consecutive sample values ​​as the final data, removing accidental signal spikes, such as false data caused by instantaneous current fluctuations, to ensure the authenticity of the data.

[0096] The working logic of the central control module is as follows: receive front-end data → Kalman filter to remove interference → temperature compensation calibration → calculate the average humidity of the entire area + the maximum deviation of each area. The humidity deviation is calculated as: humidity deviation = (actual humidity parameter - target humidity parameter) / target humidity parameter × 100%.

[0097] Meanwhile, the specific parameters for the central control module are matched as follows:

[0098] Humidity deviation ≤ ±0.5%: Invoke the "humidity-printing parameter" mapping algorithm to generate global target parameters:

[0099] When the average humidity of the entire paperboard surface is between 7% and 8%, it is considered a low humidity range, corresponding to an ink viscosity of 3000 mPa·s, a printing plate-rubber blanket pressure of 10 kN / m, a drying temperature of 50℃, and a paper feeding speed of 10,000 sheets / hour.

[0100] The optimal humidity range is when the average humidity of the entire paperboard surface is between 9% and 11%, which corresponds to an ink viscosity of 2800 mPa·s, a printing plate-rubber blanket pressure of 9 kN / m, a drying temperature of 55℃, and a paper feeding speed of 12000 sheets / hour.

[0101] When the average humidity of the entire paperboard surface is between 12% and 13%, it is considered a high humidity range, corresponding to an ink viscosity of 2500 mPa·s, a printing plate-rubber blanket pressure of 8 kN / m, a drying temperature of 65℃, and a paper feeding speed of 11,000 sheets / hour.

[0102] The ink viscosity was set to 3000 mPa·s in the low humidity range, based on the following key criteria:

[0103] Paperboard characteristics: Low-humidity paperboard has a dense fiber structure, weak ink absorption, and is prone to static electricity on the surface. If the ink viscosity is too low, such as <2800mPa・s, the ink layer will have too strong fluidity, resulting in 'floating ink' and 'smearing'. In addition, the ink layer has insufficient adhesion to the paperboard fibers, which will easily lead to peeling off later.

[0104] Ink rheology: In low humidity environments, the ink solvent evaporates faster and the viscosity tends to increase naturally. The setting of 3000 mPa·s not only allows for viscosity redundancy due to solvent evaporation, but also maintains dynamic balance through fine-tuning of the micro-diluent pump, ensuring uniform ink transfer on the printing cylinder.

[0105] Print quality matching: The thixotropy of the ink corresponding to this viscosity value can be adapted to a paper feed speed of 10,000 sheets / hour. During printing, the ink flows and spreads under pressure, and quickly recovers its viscosity after the machine stops, avoiding ink dripping and contamination, while ensuring the clarity of the image edges.

[0106] The "humidity-printing parameter" mapping algorithm supports manual updates via the touchscreen of the human-computer interaction module or import of optimized parameters via the cloud interface.

[0107] When the humidity deviation is greater than ±0.5%, the local humidity compensation logic is triggered.

[0108] High humidity area: temperature +5~8℃, pressure -0.5~1kN / m;

[0109] Low humidity range: viscosity +100~200mPa・s, speed -500~800 sheets / hour).

[0110] Generate partition target parameters;

[0111] Closed-loop correction: Collect the actual printing parameters of the execution module every 0.1 seconds → calculate the deviation, where the printing parameter deviation is calculated as: Printing parameter deviation = (Actual printing execution value parameter - Target printing execution value parameter) / Target printing execution value parameter × 100% → When the printing parameter deviation > 3% (paper feed speed > 1%), generate a correction command within 0.5 seconds → until the printing parameter deviation ≤ 3%.

[0112] The selection of ±0.5% as the trigger threshold for local humidity compensation is based on the following technical balance:

[0113] Quality sensitivity threshold: Experimental verification shows that when the humidity difference between different areas of the same cardboard is ≤0.5%, the local differences in ink absorption and stiffness of the cardboard can be offset by the natural diffusion of ink, and the consistency deviation of the entire printing area is ≤0.3%; if the difference is >0.5%, obvious defects such as ink layer accumulation in high humidity areas and ink layer floating in low humidity areas will appear.

[0114] Sensor accuracy support: The front-end humidity sensor 1 has a detection accuracy of ±0.1%, which is far higher than the threshold requirement of ±0.5%. It can accurately identify the actual humidity difference and avoid false triggering caused by sensor error.

[0115] Balance of performance stability: If the threshold is set too small, such as ±0.3%, it will cause the actuators such as pumps, valves and motors to start and stop frequently for adjustment, shortening the life of the components and causing parameter fluctuations; if the threshold is too large, such as ±0.8%, it will miss quality problems caused by slight humidity unevenness. Therefore, ±0.5% is the optimal balance point between 'quality sensitivity' and 'performance stability'.

[0116] The printing execution adjustment module is a parameter execution layer, which is embedded in the printing press's ink system, pressure system, drying system, and paper feeding system. It includes four subsystems: automatic ink adjustment subsystem, pressure regulation subsystem, intelligent drying subsystem, and paper feeding speed regulation subsystem. It receives target parameter instructions from the central control module and adjusts ink viscosity, roller pressure, drying temperature and humidity, and paper feeding speed synchronously through the four subsystems to achieve precise parameter implementation.

[0117] The automatic ink adjustment system consists of a miniature thinner pump 2 (model IWAKIEW-60) made of 304 stainless steel and a viscosity sensor 3 (model AntonPaarSVM3000). The flow rate of the thinner pump is adjustable from 0.1L / h to 1L / h. It is installed on the top of the ink tank of the printing press and connected to the ink tank through a silicone tube with an inner diameter of 6mm. The viscosity sensor 3 has an accuracy of ±5mPa・s, and the probe is inserted into the ink tank to a depth of 50mm. The viscosity sensor 3 outputs a corresponding current signal according to the ink viscosity. The conversion logic between ink viscosity and the corresponding current signal is: viscosity value / 5000mPa・s) × 16mA + 4mA. For example, 2500mPa・s corresponds to 12mA, and 3000mPa・s corresponds to 14.4mA.

[0118] The current signal is transmitted to channel one of the analog module through an ink-resistant shielded cable. The analog module has a built-in AD converter that converts the current signal into a digital value. With 12-bit precision, 4-20mA corresponds to a digital value of 0-27648, and 12mA corresponds to a digital value of 13824. The digital value is transmitted to the PLC main control unit through the Profinet bus.

[0119] Execution logic: The central control module issues the viscosity target value → Viscosity sensor 3 detects in real time → A 4-20mA signal is generated according to (viscosity value / 5000mPa・s)×16mA+4mA → Transmitted to closed-loop control unit channel 1 → The analog module converts the signal into a digital value (12-bit precision, 4-20mA corresponds to 0-27648) → The central control module performs reverse conversion according to "digital value → current value → viscosity value" → Adjusts the diluent pump injection volume by comparing with the target value → Forming a "detection-adjustment-feedback" closed loop. The response time of this closed loop is ≤0.5 seconds, and the viscosity deviation is ≤3%.

[0120] like Figure 2 As shown, the pressure regulation subsystem 4 is equipped with a set of pneumatic pressure valves 5 (model FestoVPPM-6L-L-1-G18-0L6H-A4P) and pressure sensors 6 (model HBMU9C) between the printing plate cylinder and the blanket cylinder for each color printing. The pneumatic pressure valve 5 has an output range of 0 to 0.8 MPa and an accuracy of ±0.01 MPa. It is connected to the original air source of the printing press through a pressure-resistant air pipe and communicates with the central control module. It is installed on the bracket between the printing plate and blanket cylinders. The pressure sensor 6 has a range of 0 to 20 kN / m and an accuracy of ±0.1 kN / m. It is fixed to the side of the cylinder bearing seat and uses a pressure strain gauge to detect the contact pressure between the cylinders in real time.

[0121] Pressure sensor 6 outputs a current signal based on the actual pressure. The pressure conversion logic is: (pressure value / 20kN / m) × 16mA + 4mA. For example, 8kN / m corresponds to 8.8mA, and 10kN / m corresponds to 12mA. The signal is transmitted to channel two of the analog module via a shielded cable. Each color-coated roller corresponds to one channel; for example, a 4-color printing press requires 4 channels. Here, a single channel is used as an example. The analog module converts the current signal into a digital value, such as 8.8mA corresponding to the digital value 12205, which is then transmitted to the central control module and converted into the actual pressure.

[0122] Execution logic: The central control module sends out the pressure target value → Pressure sensor 6 detects the actual pressure through the strain gauge → Generates a 4-20mA signal according to (pressure value / 20kN / m)×16mA+4mA → Transmits it to the closed-loop control unit channel 2 → The analog module converts it into a digital value → The central control module calculates the actual pressure → Adjusts the output of pneumatic pressure valve 5 by comparing it with the target value → Dynamically corrects the roller contact pressure.

[0123] The intelligent drying subsystem includes an electric heating element 7 (model SINCOHT-1000), a variable frequency fan 8 (model EBMPAPSTR2E133-AA44-30), and a temperature and humidity sensor 9 (model SensirionSHT31). The electric heating element 7 has a power of 1kW and is arranged in 6 sets along the top and sides of the drying channel at the paper receiving end. It is also equipped with a stainless steel protective mesh with a 10mm aperture on the outside for protection.

[0124] Variable frequency fans 8 are symmetrically installed on both sides of the drying channel, with an air volume adjustment range of 500m³ / h to 1500m³ / h. They are used to adjust the hot air velocity. At the same time, one set of temperature and humidity sensors 9 are installed at the inlet and outlet of the drying channel at the paper receiving end, with a temperature accuracy of ±1℃ and a humidity accuracy of ±2%RH, to control the drying temperature in real time.

[0125] The temperature sensor detects the actual temperature inside the drying channel and outputs a corresponding current signal. The temperature conversion logic is: current signal (mA) = (temperature value T + 40℃) / 165℃ × 16mA + 4mA.

[0126] Derivation basis: The temperature range of the temperature and humidity sensor 9 (SensirionSHT31) is -40℃ to 125℃, and the range span is 125 - (-40) = 165℃; the range corresponding to the 4-20mA signal is that -40℃ corresponds to 4mA and 125℃ corresponds to 20mA. Therefore, the current signal of the intermediate temperature T is "(T-(-40)) / 165×(20-4)+4", which is simplified to the above formula.

[0127] Execution logic: The central control module issues the target drying temperature value → the temperature and humidity sensor 9 detects the actual temperature → a 4-20mA signal is generated by (temperature value + 40℃) / 165℃ × 16mA + 4mA → transmitted to the closed-loop control unit channel three → the central control module converts the actual temperature and compares the inlet / outlet temperature difference (normal ≤ 3℃) → the power of the electric heating tube 7 is adjusted (±3% for every 1℃ deviation) or the fan speed is adjusted (±5% for every 1℃ deviation) → to ensure uniform drying.

[0128] like Figure 3As shown, the paper feeding speed control subsystem includes a Schneider LXM32AD18M2 servo motor driver 10, a Simco-IonTopGun ionizer nozzle-type static eliminator 11, and a Pepperl+Fuchs RVI58N incremental encoder 12.

[0129] The servo motor driver 10 is adapted to a 5.5kW paper feeding motor, controlled by pulse signals, with a speed adjustment accuracy of ±100 sheets / hour. The ionizer nozzle-type static eliminator 11 is installed at the end of the paper feeding table, with a length of 500mm and a distance of 100mm from the paperboard surface. It outputs 5kV and eliminates static electricity on low-humidity paperboard. The incremental encoder 12 is installed on the paper feeding motor shaft, calculating the motor speed based on the number of pulses, and then converting this into the paper feeding speed. Its speed detection accuracy is ±10 rpm.

[0130] Execution logic: The central control module sends the target paper speed value → converts it into the target motor speed value → the servo driver controls the motor speed through pulse + direction signal (pulse equivalent 1000 pulses / revolution) → the encoder outputs A / B phase pulse signal (1000 rpm corresponds to 17067Hz) → transmits it to the high-speed counter interface of the PLC main control unit → the central control module converts it according to "pulse frequency → motor speed → paper feeding speed" → compares it with the target value and adjusts the driver frequency; when the humidity is <8%, the static eliminator 11 is started synchronously.

[0131] The human-computer interaction module serves as a status monitoring and data storage layer. It includes a touch screen, an audible and visual alarm unit, and a data storage unit. The touch screen is a 7-inch Weintek TK6071iQ color touch screen with a resolution of 800×480. It displays real-time humidity, target parameters, actual parameters, and device operating status, and supports manual parameter modification and algorithm updates.

[0132] The audible and visual alarm unit uses a buzzer with a decibel level of ≥85dB and a red LED light with a diameter of 20mm. It automatically starts when the paperboard moisture content is >14% or <6%, and at the same time, the paper feeding system is paused.

[0133] The data storage unit uses a Kingston Industrial 32GB SD card to store the corresponding data of "humidity data - target parameters - correction records - scrap rate" for 3 months. It supports exporting Excel format reports via Ethernet interface or uploading to the cloud platform via Alibaba Cloud interface.

[0134] Working Logic

[0135] Status display: The central control module pushes data to the touch screen in real time, visually presenting the full-area humidity distribution, target / actual parameters, and equipment operating status;

[0136] Data storage: Each batch of data is automatically stored, and it supports exporting Excel reports via Ethernet interface (TCP / IP protocol) or accessing Alibaba Cloud IoT platform via MQTT protocol.

[0137] The paper feeding speed control subsystem also includes a FestoDGSL-25-50-PA cylinder with a guide rod installed on the side of the paper feeding table and a pneumatic pusher plate 13 installed at the output end. The cylinder with the guide rod is connected to the central control module. When the front-end humidity detection module detects that the paperboard humidity is >14% or <6%, the human-machine interface module links the paper feeding system to pause. At the same time, the cylinder with the guide rod is activated to push the pneumatic pusher plate 13 to move in the vertical paper feeding direction, pushing the paperboard with excessive humidity to the waste collection trough. After the pneumatic pusher plate 13 is reset, the front-end humidity detection module re-inspects the first paperboard. If the humidity of the re-inspection is 8% to 12%, which is within the acceptable range, the central control module controls the paper feeding system to resume operation. If the re-inspection still exceeds the standard, the "alarm-rejection" step is repeated until a qualified paperboard is detected.

[0138] All module wiring uses Belden 3071F twisted-pair shielded cable, which is resistant to ink and temperature from -20℃ to 80℃, and is grounded. The cable shield is grounded at one end (grounding resistance ≤ 4Ω), and the metal control cabinet is grounded to avoid electromagnetic interference.

[0139] A carton printing process for the above-mentioned adaptive humidity-controlled carton printing apparatus, such as Figure 4 As shown, it includes the following steps:

[0140] S1: The cardboard to be printed is conveyed to the printing operation area through the paper feeding table of the printing press. Before the cardboard enters the printing press unit, three or more NDCCM710e humidity sensors are activated to scan and detect along the width direction at a frequency of 10 times / second, and transmit the humidity data of each area to the PLC main control unit through the RS485 bus.

[0141] S2: After receiving the humidity detection data from S1, the central control module main control unit first filters and calibrates the data, and calculates the average humidity value of the entire paperboard surface and the maximum humidity deviation value of each area.

[0142] Then, the "humidity-printing parameter" mapping algorithm in the parameter database cell is called to match the parameters:

[0143] If the maximum humidity deviation is ≤ ±0.5%, directly match the target printing parameters corresponding to the average humidity value;

[0144] If the maximum humidity deviation is > ±0.5%, the local humidity compensation logic is invoked. The width of the cardboard is divided into multiple detection areas according to the layout of humidity sensor 1. The target printing parameters for each area are matched separately for the humidity difference. Specifically:

[0145] If the difference between the humidity value of a certain detection area and the average humidity value of the entire paperboard is ≥0.8%, the central control module sends an instruction to the intelligent drying subsystem corresponding to that area to increase the drying temperature by 5-8℃. At the same time, it sends an instruction to the pressure regulation subsystem 4 to reduce the printing plate-rubber blanket pressure by 0.5-1kN / m, while keeping the ink viscosity and paper feeding speed unchanged.

[0146] If the difference between the humidity value of a certain detection area and the average humidity value of the entire paperboard is ≤-0.8%, the drying temperature remains unchanged, the printing plate-rubber blanket pressure remains unchanged, the central control module sends an instruction to the automatic ink adjustment subsystem to increase the ink viscosity by 100-200 mPa·s, and at the same time sends an instruction to the paper feeding speed adjustment subsystem to reduce the paper feeding speed by 500-800 sheets / hour.

[0147] If the difference between the humidity value of a certain detection area and the average humidity value of the entire paperboard surface is within ±0.8%, the drying temperature, printing plate-rubber blanket pressure, ink viscosity and paper feeding speed remain unchanged.

[0148] S3: The central control module sends the target parameter instruction matched in S2 to the printing execution adjustment module, and each subsystem synchronously performs the adjustment:

[0149] S3a: Start the micro-diluent pump 2 of the automatic ink adjustment system to inject diluent into the ink tank. Viscosity sensor 3 collects the actual viscosity of the ink in real time and feeds it back to the central control module until the actual viscosity deviates from the target value printing parameter by ≤3%.

[0150] S3b: The contact pressure between the printing plate cylinder and the blanket cylinder is adjusted by the pneumatic pressure valve 5 of the pressure regulation subsystem 4, and the pressure sensor 6 provides real-time feedback of the actual pressure until the pressure deviation is ≤ ±0.1kN / m;

[0151] S3c: Controls the heating element 7 of the intelligent drying subsystem to raise the temperature and the variable frequency fan 8 to adjust the speed. Temperature and humidity sensor 9 monitors the actual temperature and humidity data at the inlet and outlet of the drying channel in real time until the temperature uniformity deviation of the drying channel is ≤ ±2℃.

[0152] S3d: Adjust the paper feeding speed through the servo driver of the paper feeding speed control subsystem, and the encoder feeds back the motor speed until the paper feeding speed deviation is ≤±1%. If the paperboard humidity is <8%, the static eliminator 11 is started synchronously to eliminate static electricity on the paperboard.

[0153] S4: During the printing process, the central control module's closed-loop control unit continuously collects feedback from the printing execution adjustment module on ink viscosity, roller pressure, drying temperature, and paper feed speed, and compares the deviation with the target parameters. Specifically, the actual parameters of viscosity, pressure, temperature, and speed are collected every 0.1 seconds. The deviation is calculated as: Deviation = (Actual value - Target value) / Target value × 100%. The correction logic is as follows:

[0154] If the deviation is ≤3%, maintain the current parameters;

[0155] If the deviation is greater than 3%, a correction command will be generated within 0.5 seconds. The correction command is as follows:

[0156] Ink viscosity deviation > ±3%: Adjust the thinner pump flow rate; for every 1% deviation exceeding the deviation, increase the flow rate by ±2%.

[0157] If the roller pressure deviation is > ±3%, adjust the output of pneumatic pressure valve 5. For every 1% deviation exceeding the deviation, adjust the pressure by ±1%.

[0158] If the drying temperature deviation is > ±3℃: Adjust the heating element power; for every 1℃ deviation, adjust the power by ±3% or the fan speed by ±5%.

[0159] Paper feed speed deviation > ±1%: Adjust the servo drive frequency; for every 0.5% deviation, adjust the frequency by ±0.3Hz.

[0160] Correct the response time to ≤0.5 seconds until the deviation is ≤3%. If the deviation still fails to meet the standard after 5 consecutive corrections, trigger the parameter abnormality alarm, suspend printing, and manually check for problems such as sensor failure and execution component jamming. After resetting the alarm through the human-machine interaction module, production can be resumed to avoid the mass production of unqualified products.

[0161] S5: If S1 detects that the paperboard humidity is >14% or <6%, the central control module triggers an alarm and simultaneously controls the paper feeding system to pause. The paper feeding system restarts within 0.2 seconds after the pause and uses the pneumatic pusher 13 to push the paperboard in the vertical feeding direction. The stroke is 50~100mm and the action time is 0.3 seconds. This pushes the paperboard that exceeds the standard to the waste trough. After the paperboard that exceeds the standard is rejected, it immediately resets after the push is completed and waits for the re-inspection instruction. The front-end humidity detection module re-inspects the subsequent paperboard. After confirming that the humidity is 8-12%, the paper feeding resumes. If the re-inspection fails, the "alarm-rejection" continues until the inspection is qualified.

[0162] In S2, the filtering is: Kalman filtering + moving average filtering (averaging of 5 consecutive sample values) to remove false data; the calibration is: for every 5°C deviation in ambient temperature, the humidity value is corrected by ±0.05%; the analysis is: removing out-of-range data (0.1%~40%), and calculating the average humidity value of the entire area + the maximum humidity deviation value of each area.

[0163] The difference between the humidity value of the detection area in S2 and the average humidity value of the entire paperboard surface is selected as ±0.8% as the zoning adjustment threshold, based on the following:

[0164] When the difference between the regional humidity and the average humidity is ≤ ±0.8%, the printing consistency requirement can be met through the natural adaptation of global parameters, i.e., the deviation is ≤ 0.5%. If the difference is > ±0.8%, the local ink absorption difference cannot be offset, and the parameters need to be adjusted accordingly. Therefore, this threshold is the optimal balance between 'compensation effect' and 'execution efficiency'.

[0165] The definitions and coordination logic for the synchronous execution of adjustments by each subsystem in S3 are as follows:

[0166] Synchronization standard: After the central control module issues the target parameter command, each subsystem must start the adjustment action within 0.3 seconds, and the time difference between the adjustment completion of all subsystems shall be ≤0.2 seconds to ensure the compatibility of parameters such as ink viscosity, roller pressure, drying temperature and paper feeding speed;

[0167] Priority settings: sorted by 'criticality to printing quality', with the following priority: automatic ink adjustment subsystem (viscosity) > pressure regulation subsystem (pressure) > intelligent drying subsystem (temperature) > paper feed speed control subsystem (speed); after the preceding priority subsystems are adjusted to meet the standards (deviation ≤3%), the subsequent subsystems will complete the final calibration to avoid parameter superposition deviations;

[0168] Feedback and linkage: Each subsystem provides real-time feedback on its adjustment progress through sensors. If a subsystem's adjustment timeout exceeds 1 second (failure to meet the target), the central control module suspends the adjustment actions of other subsystems and restarts the synchronization process once the target subsystem is met.

[0169] Response speed adaptation: Preset response compensation for the hardware characteristics of different subsystems: the micro-diluent pump response time in the automatic ink adjustment subsystem is 0.1 seconds, the pneumatic pressure valve response time in the pressure regulation subsystem is 0.08 seconds, the electric heating tube in the intelligent drying subsystem has a 0.2-second delay in heating and a 0.1-second advance in starting time, and the servo driver response time in the paper feeding speed regulation subsystem is 0.05 seconds. Dynamic synchronization is achieved through time compensation.

[0170] In S5, the alarm priority is: abnormal parameter alarm > excessive humidity alarm. When both are triggered simultaneously, the 'pause production' action of the abnormal parameter alarm is executed first. After the investigation is completed, the excessive humidity problem is addressed. After the alarm is cleared, the central control module automatically restores the target printing parameters before the alarm, without the need for rematching, ensuring production continuity.

[0171] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0172] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An adaptive humidity-controlled carton printing device, characterized in that: It includes a front-end humidity detection module, a central control module, a printing execution adjustment module, and a human-machine interaction module. Each module is connected to the central control module and is integrated into the machine frame of the carton printing machine. The front-end humidity detection module is fixed to the front end of the paper feeding table of the printing press and is used to collect the humidity data of the entire paperboard in real time and transmit it to the central control module. The central control module is used to receive humidity data from the front-end humidity detection module and generate adjustment instructions based on the preset "humidity-printing parameter" mapping algorithm. At the same time, it corrects the parameter deviation of the printing execution adjustment module through closed-loop control logic. The core feature of the mapping algorithm is: dividing the paperboard into at least three intervals based on the average humidity of the entire surface, matching the corresponding ink viscosity, printing plate-rubber blanket pressure, drying temperature and paper feeding speed for each interval, and when the deviation of the humidity of each area from the average humidity exceeds a preset threshold, the printing parameters of the deviation area are locally compensated. The printing execution adjustment module includes: An automatic ink adjustment subsystem, integrated into the ink tank of a printing press, is used to adjust the viscosity of the ink; The pressure regulation subsystem (4) is installed between the printing plate cylinder and the blanket cylinder of the printing press and is used to adjust the cylinder contact pressure. The intelligent drying subsystem is installed in the drying channel at the paper delivery end of the printing press to adjust the drying temperature and airflow. The paper feed speed control subsystem is adapted to the paper feed motor of the printing press and is used to adjust the paper feed speed and eliminate static electricity. Each subsystem is connected to the central control module to receive target parameter instructions and automatically perform adjustments; The human-machine interaction module communicates with the central control module and is used for process status monitoring, abnormal alarms, and data storage. During operation, the cardboard enters the paper feeding table from the stacking table. The front-end humidity detection module first collects full-width humidity data, the central control module generates target parameters based on the data, the printing execution adjustment module adjusts the printing parameters according to the instructions, and the human-machine interaction module monitors the status synchronously.

2. The adaptive humidity-controlled carton printing device according to claim 1, characterized in that: The front-end humidity detection module includes three or more humidity sensors (1) evenly distributed along the width of the paper feed table, with the probes of the humidity sensors (1) facing the paperboard surface vertically. The humidity data of the cardboard is collected in real time and transmitted to the central control module through the front-end humidity detection module.

3. The adaptive humidity-controlled carton printing device according to claim 1, characterized in that: The central control module includes: The PLC main control unit is used for filtering, calibration, and parameter matching logic operations of humidity data. The parameter database unit pre-stores the "humidity-printing parameter" mapping algorithm, the threshold parameters of the local humidity compensation logic, and the response time parameters of the closed-loop correction. The closed-loop control unit is an eight-channel analog input module used to collect the actual operating parameters of each system fed back by the printing execution adjustment module in real time. The analog channels of the closed-loop control unit are respectively connected to the parameter detection sensor signals in different subsystems of the printing execution adjustment module to receive the analog signals output by the sensors.

4. The adaptive humidity-controlled carton printing device according to claim 3, characterized in that: The "humidity-printing parameter" mapping algorithm pre-stored in the parameter database unit is as follows: When the average humidity of the entire paperboard surface is between 7% and 8%, it is considered a low humidity range, corresponding to an ink viscosity of 3000 mPa·s, a printing plate-rubber blanket pressure of 10 kN / m, a drying temperature of 50℃, and a paper feeding speed of 10,000 sheets / hour. The optimal humidity range is when the average humidity of the entire paperboard surface is between 9% and 11%, which corresponds to an ink viscosity of 2800 mPa·s, a printing plate-rubber blanket pressure of 9 kN / m, a drying temperature of 55℃, and a paper feeding speed of 12000 sheets / hour. When the average humidity of the entire paperboard surface is between 12% and 13%, it is considered a high humidity range, corresponding to an ink viscosity of 2500 mPa·s, a printing plate-rubber blanket pressure of 8 kN / m, a drying temperature of 65℃, and a paper feeding speed of 11,000 sheets / hour. The "humidity-printing parameter" mapping algorithm supports manual updates via the touchscreen of the human-computer interaction module or importing optimized parameters via the cloud interface.

5. The adaptive humidity-controlled carton printing device according to claim 1, characterized in that: The automatic ink adjustment subsystem includes: A miniature diluent pump (2) is installed on the top of the ink tank of the printing press and is connected to the ink tank through a silicone tube; Viscosity sensor (3), whose probe is inserted into the ink tank, is used to feed back ink viscosity data to the central control module in real time; This forms a closed loop for viscosity control, consisting of "detection-adjustment-feedback".

6. The adaptive humidity-controlled carton printing device according to claim 1, characterized in that: The pressure regulation subsystem (4) includes: The pneumatic pressure valve (5) is installed on the bracket between the printing plate cylinder and the blanket cylinder, and is connected to the original air source of the printing press through a pressure-resistant air pipe. The pneumatic pressure valve (5) is connected to the central control module. The pressure sensor (6) is fixed to the side of the roller bearing seat to detect the contact pressure between the printing plate cylinder and the blanket cylinder in real time and feed it back to the central control module.

7. The adaptive humidity-controlled carton printing device according to claim 1, characterized in that: The intelligent drying subsystem includes: Several electric heating tubes (7) are provided and are evenly distributed along the top and sides of the drying channel at the paper receiving end of the printing press; Variable frequency fans (8) are symmetrically installed on both sides of the drying channel to adjust the hot air speed; Temperature and humidity sensors (9) are installed at both the inlet and outlet of the drying channel at the paper receiving end of the printing press to provide feedback of environmental data to the central control module.

8. The adaptive humidity-controlled carton printing device according to claim 1, characterized in that: The paper feeding speed control subsystem includes: Servo motor driver (10) is adapted to the power of the paper feeding motor of the printing press paper feeding system, and controls the speed of the paper feeding motor through pulse signals; An electrostatic eliminator (11) is used to eliminate static electricity generated by low-humidity cardboard and is installed at the end of the paper feeder. An incremental encoder (12) is installed on the end of the paper feeding motor shaft via a coupling to collect the actual speed of the paper feeding motor in real time and to collect the actual speed of the motor in real time and feed it back to the central control module. A pneumatic pusher (13) is installed on the side of the paper feeding table and is connected to the central control module for pushing paperboard with excessive humidity to the waste collection trough.

9. The adaptive humidity-controlled carton printing device according to claim 1, characterized in that: The human-computer interaction module includes: The touchscreen is connected to the central control module and is used to display real-time humidity, current printing parameters, and device operating status. The alarm unit is an audible and visual alarm that automatically activates when the front-end humidity detection module detects that the paperboard humidity is >14% or <6%, and then links the paper feeding system to pause via the central control module. The data storage unit stores the humidity data, matching printing parameters, closed-loop correction records, and scrap rate data of each batch of cardboard in real time, and is equipped with a cloud interface.

10. A carton printing process based on the adaptive humidity-regulating carton printing apparatus according to any one of claims 1-9, characterized in that, Includes the following steps: S1: The cardboard to be printed is transported to the printing operation area through the paper feeding table of the printing machine. Before the cardboard enters the printing unit, multiple humidity sensors (1) of the front-end humidity detection module are activated to scan and detect the cardboard across the width of the cardboard, collect humidity data of each area of ​​the cardboard in real time, and transmit the detection data to the PLC main control unit of the central control module. S2: After receiving the humidity detection data from S1, the central control module's main control unit first filters and calibrates the data, calculates the average humidity value of the entire paperboard surface and the maximum humidity deviation value of each area, and then calls the "humidity-printing parameter" mapping algorithm of the parameter database unit to match the parameters. If the maximum humidity deviation is ≤ ±0.5%, directly match the target printing parameters corresponding to the average humidity value; If the maximum humidity deviation value is > ±0.5%, the local humidity compensation logic is invoked, and the width of the cardboard is divided into multiple detection areas according to the humidity sensor (1). The target printing parameters for each area are matched according to the humidity difference. Specifically: If the difference between the humidity value of a certain detection area and the average humidity value of the full width of the paperboard is ≥0.8%, the central control module sends an instruction to the intelligent drying subsystem corresponding to that area to increase the drying temperature by 5-8℃, and at the same time sends an instruction to the pressure regulation subsystem (4) to reduce the printing plate-rubber blanket pressure by 0.5-1kN / m, keep the ink viscosity unchanged, and keep the paper feeding speed unchanged. If the difference between the humidity value of a certain detection area and the average humidity value of the entire paperboard is ≤-0.8%, the drying temperature remains unchanged, the printing plate-rubber blanket pressure remains unchanged, the central control module sends an instruction to the automatic ink adjustment subsystem to increase the ink viscosity by 100-200 mPa·s, and at the same time sends an instruction to the paper feeding speed adjustment subsystem to reduce the paper feeding speed by 500-800 sheets / hour. If the difference between the humidity value of a certain detection area and the average humidity value of the entire paperboard surface is within ±0.8%, the drying temperature, printing plate-rubber blanket pressure, ink viscosity and paper feeding speed remain unchanged. S3: The central control module sends the target parameter instruction matched in S2 to the printing execution adjustment module, and each subsystem synchronously performs the adjustment. S3a: Start the micro diluent pump (2) of the automatic ink adjustment system to inject diluent into the ink tank. The viscosity sensor (3) collects the actual viscosity of the ink in real time and feeds it back to the central control module until the actual viscosity reaches the target value. S3b: The contact pressure between the printing plate cylinder and the blanket cylinder is adjusted by the pneumatic pressure valve (5) of the pressure regulation subsystem (4), and the pressure sensor (6) provides real-time feedback of the actual pressure until the pressure reaches the target value. S3c: Controls the heating element (7) of the intelligent drying subsystem to raise the temperature and the variable frequency fan (8) to adjust the speed. The temperature and humidity sensor (9) monitors the actual temperature and humidity data at the inlet and outlet of the drying channel in real time until the temperature of the drying channel reaches the target drying temperature. S3d: Adjust the paper feeding speed through the servo driver of the paper feeding speed control subsystem, and the encoder feeds back the motor speed until the paper feeding speed reaches the target value. If the paperboard humidity is <8%, the static eliminator (11) is started synchronously to eliminate the static electricity of the paperboard. S4: During the printing process, the central control module's closed-loop control unit continuously collects feedback from the printing execution adjustment module on ink viscosity, roller pressure, drying temperature, and paper feed speed, and compares the deviation with the target parameters. If the deviation is ≤3%, maintain the current parameters; If the deviation is greater than 3%, a correction command will be generated within 0.5 seconds. The correction command is as follows: Ink viscosity deviation > ±3%: Adjust the thinner pump flow rate; for every 1% deviation exceeding the deviation, increase the flow rate by ±2%. If the roller pressure deviation is greater than ±3%, adjust the output of the pneumatic pressure valve (5). For every 1% deviation, the pressure should be adjusted by ±1%. If the drying temperature deviation is > ±3℃: Adjust the heating element power; for every 1℃ deviation, adjust the power by ±3% or the fan speed by ±5%. Paper feed speed deviation > ±1%: Adjust the servo drive frequency; for every 0.5% deviation, adjust the frequency by ±0.3Hz. Correct the response time to ≤0.5 seconds, until the deviation is ≤3%; S5: If S1 detects that the paperboard humidity is >14% or <6%, the central control module triggers an alarm and controls the paper feeding system to stop. The paperboard exceeding the standard is pushed to the waste trough by the pneumatic pusher plate (13). After the paperboard exceeding the standard is removed, the front-end humidity detection module re-inspects the subsequent paperboard. After confirming that the humidity is 8-12%, the paper feeding is resumed.

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