Carton quality detection system

Abstract

The invention discloses a paper box quality detection system, belongs to the technical field of paper box detection, and solves the problems that in the whole production and manufacturing process of a paper box, time difference and condition dependence exist between the curing process of a starch adhesive and the formation of final bonding strength, so that the bonding part of the paper box seems good when the paper box is off line; however, glue failure occurs only during storage or transportation, namely, the false sticking phenomenon is avoided. Comprising a system control module, a constant current source matrix module, a four-electrode sensing module, a multi-channel signal conditioning module, a digital phase-locked amplification module and a temperature and humidity fusion compensation module. According to the method, the molecular binding state of the adhesive layer is monitored in situ through the four-electrode sensor, the final value of the bonding strength after several hours is predicted within the short time of carton offline by combining the multi-frequency impedance spectroscopy and the curing kinetic model, and interception is triggered immediately when it is detected that the hydrogen bond formation rate is lower than that of prefabrication or water residue exceeds the standard; and the phenomenon that a false adhesion phenomenon cannot be identified due to a time difference formed by apparent curing and real strength is avoided.

Description

Technical Field

[0001] This invention relates to the field of cardboard box inspection technology, and in particular to a cardboard box quality inspection system. Background Technology

[0002] Cardboard boxes are a common and important packaging material, and their manufacturing process is roughly as follows: First, suitable base paper is selected. Depending on the purpose and quality requirements of the cardboard box, there are various options such as corrugated cardboard and kraft paper. Next, the design stage takes place, determining the size, structure, and pattern of the cardboard box to meet the packaging needs of different products. The next step is plate making and printing, where the designed patterns and text are printed onto the base paper using printing plates. This step is crucial for the appearance of the cardboard box and brand promotion. After printing, die-cutting and creasing are performed, cutting the base paper into the shape of the cardboard box and pressing creases to facilitate subsequent forming. Then comes forming and gluing, folding the die-cut cardboard into the shape of the cardboard box, applying adhesive to the gluing areas, and bonding all sides together to form a complete cardboard box. Finally, finished product inspection and packaging storage occur. In this step, the cardboard boxes undergo quality inspection to ensure they meet quality standards, and then they are packaged and stored in a suitable environment, awaiting shipment.

[0003] However, during the entire production process of cardboard boxes, there is a time lag and conditional dependence between the curing process of starch adhesive and the formation of final adhesive strength. This may result in the adhesive parts of the cardboard box appearing to be good when it comes off the production line, but delamination may occur during storage or transportation, which is a phenomenon known as false adhesion.

[0004] Therefore, a cardboard box quality inspection system is proposed to solve or alleviate the above problems. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a carton quality inspection system.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A cardboard box quality inspection system includes a system control module, a constant current source matrix module, a four-electrode sensing module, a multi-channel signal conditioning module, a digital phase-locked amplification module, a temperature and humidity fusion compensation module, a curing kinetic model processing module, and a three-level early warning output module.

[0008] The output terminal of the constant current source matrix module is connected to the current injection terminal and the shielding drive terminal of the four-electrode sensing module. The voltage detection terminal of the four-electrode sensing module is connected to the differential input terminal of the multi-channel signal conditioning module. The output terminal of the multi-channel signal conditioning module is connected to the signal input terminal of the digital phase-locked amplifier module. The real / imaginary part output terminal of the digital phase-locked amplifier module is connected to the input terminal of the temperature and humidity fusion compensation module. The compensation output terminal of the temperature and humidity fusion compensation module is connected to the impedance input terminal of the curing kinetic model processing module. The time constant output terminal of the curing kinetic model processing module is connected to the analog input terminal of the three-level early warning output module. The SPI interface of the system control module is connected to the control terminal of the constant current source matrix module and the three-level early warning output module, and its input pin is connected to the output terminal of the digital phase-locked amplifier module. The enable terminal of the three-level early warning output module is connected to the data terminal of the system control module.

[0009] Preferably, the constant current source matrix module includes a REF02 voltage reference, a first OPA2188 operational amplifier, a first MCP4131 digital potentiometer, and a 2N2222A transistor;

[0010] The output terminal of the REF02 voltage reference is connected to the non-inverting input terminal of the first OPA2188 operational amplifier through a first resistor. The ground terminal of the REF02 voltage reference is grounded. The power terminal of the REF02 voltage reference is connected to a 12V power supply. The sliding terminal of the first MCP4131 digital potentiometer is connected to the inverting input terminal of the first OPA2188 operational amplifier through a second resistor. The first fixed terminal of the first MCP4131 digital potentiometer is grounded. The second fixed terminal of the first MCP4131 digital potentiometer is left floating. The chip select terminal, data terminal, and clock terminal of the first MCP4131 digital potentiometer are all connected to the STM32F103C8T6 controller in the system control module. The output terminal of the first OPA2188 operational amplifier is connected to the base of the 2N2222A transistor through a third resistor. The emitter of the 2N2222A transistor is connected to a four-electrode sensor through a fourth resistor. The collector of the 2N2222A transistor is connected to a 24V power supply.

[0011] Preferably, the four-electrode sensing module includes a ceramic substrate, a platinum electrode array etched on the ceramic substrate, a polyimide insulating layer fixedly connected to the ceramic substrate and covering the platinum electrode array, and spring probes soldered to the ceramic substrate and coupled to the platinum electrode array. The polyimide insulating layer has through holes through which the spring probes can pass. The polyimide insulating layer is bonded to the ceramic substrate with epoxy adhesive. The platinum electrode array includes a first electrode, a second electrode, a third electrode, and a fourth electrode. The number of spring probes is four, and the four spring probes are respectively connected to the first electrode, the second electrode, the third electrode, the fourth electrode, and the fifth electrode. The third and fourth electrodes are coupled together. The first, second, third, and fourth electrodes are set as the four pins of the four-electrode sensing module. The first electrode is connected as the current excitation electrode to the emitter of the 2N2222A transistor in the constant current source matrix module. The second electrode is connected as the negative terminal of the voltage detection to the inverting input terminal of the INA333 instrumentation amplifier in the multi-channel signal conditioning module. The third electrode is connected as the positive terminal of the voltage detection to the non-inverting input terminal of the INA333 instrumentation amplifier in the multi-channel signal conditioning module. The fourth electrode is coupled as the drive shielding electrode to a shielded drive circuit.

[0012] Preferably, the multi-channel signal conditioning module includes an INA333 instrumentation amplifier, a CD4051 multiplexer, and a second OPA2188 operational amplifier;

[0013] The output of the INA333 instrumentation amplifier is connected to the non-inverting input of the second OPA2188 operational amplifier, the inverting input of the second OPA2188 operational amplifier is connected to its output, the output of the second OPA2188 operational amplifier is connected to the input channel of the CD4051 multiplexer, the output of the CD4051 multiplexer is connected to the input of the digital phase-locked loop amplifier module, and the controlled terminal of the CD4051 multiplexer is connected to the STM32F103C8T6 controller in the system control module.

[0014] Preferably, the digital phase-locked amplifier module includes a CD4046 phase-locked loop, a first AD633 multiplier, a third OPA2188 operational amplifier, a fourth OPA2188 operational amplifier, a 90° phase shifter, and a CD4520 counter;

[0015] The X1 input of the first AD633 multiplier is connected to the output of the CD4051 multiplexer in the multi-channel signal conditioning module. The reference input of the CD4046 phase-locked loop is connected to the reference signal output of the STM32F103C8T6 controller in the system control module. The output of the CD4046 phase-locked loop is connected to the clock input of the CD4520 counter. The first output of the CD4520 counter is connected to the Y1 input of the first AD633 multiplier. The second output of the CD4520 counter is connected to the Y2 input of the first AD633 multiplier via a 90° phase shifter. The first output terminal of the first AD633 multiplier is connected to the inverting input terminal of the third OPA2188 operational amplifier through the fifth resistor. The output terminal of the third OPA2188 operational amplifier is connected to its inverting input terminal through the first capacitor to form a first integrator. The second output terminal of the first AD633 multiplier is connected to the inverting input terminal of the fourth OPA2188 operational amplifier through the sixth resistor. The output terminal of the fourth OPA2188 operational amplifier is connected to its inverting input terminal through the second capacitor to form a second integrator. The first output terminal of the first AD633 multiplier is used as the real part output, and the second output terminal of the first AD633 multiplier is used as the imaginary part output.

[0016] Preferably, the temperature and humidity fusion compensation module includes a PT1000 temperature sensor, a HIH6130 humidity sensor, a fifth OPA2188 operational amplifier, a sixth OPA2188 operational amplifier, a second AD633 multiplier, and a seventh OPA2188 operational amplifier.

[0017] The output of the PT1000 temperature sensor is connected to the input of the fifth OPA2188 operational amplifier. The output of the fifth OPA2188 operational amplifier is reverse-connected to its non-inverting input through the seventh resistor. The output of the fifth OPA2188 operational amplifier is connected to the Y1 input of the second AD633 multiplier. The output of the HIH6130 humidity sensor is connected to the input of the sixth OPA2188 operational amplifier. The output of the sixth OPA2188 operational amplifier is reverse-connected to its non-inverting input through the eighth resistor. The output of the sixth OPA2188 operational amplifier is connected to... The Y2 input of the second AD633 multiplier is connected to the X1 input of the second AD633 multiplier, which is connected to the output of the CD4051 multiplexer in the multi-channel signal conditioning module. The X2 input of the second AD633 multiplier is connected to the output of the LF398 sample-and-hold circuit in the solidification kinetic model processing module. The first and second outputs of the second AD633 multiplier are respectively connected to the two inputs of the seventh OPA2188 operational amplifier, which is connected to the input of the LM349 operational amplifier in the solidification kinetic model processing module.

[0018] Preferably, the curing kinetics model processing module includes an LM349 operational amplifier, a LOG114 precision logarithmic amplifier, an AD734 analog divider, a CD4538 monostable multivibrator, and an LF398 sample-and-hold circuit.

[0019] The output of the LM349 operational amplifier is connected to the X input of the AD734 analog divider via the ninth resistor. The output of the LF398 sample-and-hold circuit is connected to the Y input of the AD734 analog divider via the tenth resistor. The output of the AD734 analog divider is connected to the non-inverting input of the LOG114 precision logarithmic amplifier. The output of the LOG114 precision logarithmic amplifier is connected to the trigger terminal of the CD4538 monostable multivibrator. The output of the CD4538 monostable multivibrator is connected to the input of the three-stage warning output module.

[0020] Preferably, the three-level early warning output module includes an LM311 voltage comparator, an LM339 four-channel differential comparator, a DAC8043 analog-to-digital converter, a ULN2003 Darlington transistor array, three PC817 optocouplers, a second MCP4131 digital potentiometer, a yellow LED, a green LED, and a red LED.

[0021] The input and output terminals of the DAC8043 analog-to-digital converter are connected to the data terminal of the STM32F103C8T6 controller in the system control module and the output terminal of the CD4538 monostable multivibrator in the solidified dynamic model processing module. The output terminal of the DAC8043 analog-to-digital converter is connected to the non-inverting input terminal of the LM311 voltage comparator and the non-inverting input terminal of the LM339 quad differential comparator through the second MCP4131 digital potentiometer. The output terminal of the LM311 voltage comparator is connected to the input terminals of two PC817 optocouplers. The output terminals of the two PC817 optocouplers are connected to the green LED and the red LED respectively through the ULN2003 Darlington transistor array. The output terminal of the LM339 quad differential comparator is connected to the input terminal of the last PC817 optocoupler. The output terminal of the last PC817 optocoupler is connected to the yellow LED through the ULN2003 Darlington transistor array.

[0022] Preferably, the system control module includes an STM32F103C8T6 controller, a DS3231 real-time clock, and a 24C256 electrically erasable programmable read-only memory, wherein the STM32F103C8T6 controller is connected to the DS3231 real-time clock and the 24C256 electrically erasable programmable read-only memory.

[0023] The present invention has the following beneficial effects:

[0024] This invention uses a four-electrode sensor to monitor the molecular binding state of the adhesive layer in situ. Combined with multi-frequency impedance spectroscopy and curing kinetics model, it predicts the final value of the adhesive strength several hours after the carton is produced. When the hydrogen bond formation rate is detected to be lower than the pre-formed value or the moisture residue exceeds the standard, it immediately triggers an interception, thus avoiding the inability to identify the "false adhesion" phenomenon caused by the time difference between apparent curing and the formation of true strength. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a structural block diagram of the present invention.

[0027] In the diagram: 1. System control module; 2. Constant current source matrix module; 3. Four-electrode sensing module; 4. Multi-channel signal conditioning module; 5. Digital phase-locked loop amplifier module; 6. Temperature and humidity fusion compensation module; 7. Solidification kinetic model processing module; 8. Three-level early warning output module. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0030] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0031] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to 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 this invention.

[0032] Furthermore, the terms "first," "second," and "third" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0033] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] A cardboard box quality inspection system, such as Figure 1As shown, it includes a system control module 1, a constant current source matrix module 2, a four-electrode sensing module 3, a multi-channel signal conditioning module 4, a digital phase-locked amplifier module 5, a temperature and humidity fusion compensation module 6, a curing kinetic model processing module 7, and a three-level early warning output module 8.

[0035] The output of constant current source matrix module 2 is connected to the current injection terminal and shielding drive terminal of four-electrode sensing module 3. The voltage detection terminal of four-electrode sensing module 3 is connected to the differential input terminal of multi-channel signal conditioning module 4. The output of multi-channel signal conditioning module 4 is connected to the signal input terminal of digital phase-locked amplifier module 5. The real / imaginary output terminal of digital phase-locked amplifier module 5 is connected to the input terminal of temperature and humidity fusion compensation module 6. The compensation output terminal of temperature and humidity fusion compensation module 6 is connected to the impedance input terminal of curing kinetic model processing module 7. The time constant output terminal of curing kinetic model processing module 7 is connected to the analog input terminal of three-level early warning output module 8. The SPI interface of system control module 1 is connected to the control terminal of constant current source matrix module 2 and three-level early warning output module 8. Its input pin is connected to the output terminal of digital phase-locked amplifier module 5. The enable terminal of three-level early warning output module 8 is connected to the data terminal of system control module 1.

[0036] The constant current source matrix module 2 includes a REF02 voltage reference, a first OPA2188 operational amplifier, a first MCP4131 digital potentiometer, and a 2N2222A transistor. The output terminal of the REF02 voltage reference is connected to the non-inverting input terminal of the first OPA2188 operational amplifier through a first resistor. The ground terminal of the REF02 voltage reference is grounded, and the power terminal of the REF02 voltage reference is connected to a 12V power supply. The sliding terminal of the first MCP4131 digital potentiometer is connected to the inverting input terminal of the first OPA2188 operational amplifier through a second resistor. The first fixed terminal of the MCP4131 digital potentiometer is grounded, and the second fixed terminal of the first MCP4131 digital potentiometer is left floating. The chip select terminal, data terminal, and clock terminal of the first MCP4131 digital potentiometer are all connected to the STM32F103C8T6 controller in the system control module 1. The output terminal of the first OPA2188 operational amplifier is connected to the base of the 2N2222A transistor through the third resistor. The emitter of the 2N2222A transistor is connected to the four-electrode sensor through the fourth resistor. The collector of the 2N2222A transistor is connected to a 24V power supply.

[0037] The four-electrode sensing module 3 includes a ceramic substrate, a platinum electrode array etched on the ceramic substrate, a polyimide insulating layer fixedly connected to the ceramic substrate and covering the platinum electrode array, and spring probes soldered to the ceramic substrate and coupled to the platinum electrode array. The polyimide insulating layer has through holes through which the spring probes can pass. The polyimide insulating layer is bonded to the ceramic substrate with epoxy adhesive. The platinum electrode array includes a first electrode, a second electrode, a third electrode, and a fourth electrode. There are four spring probes, each connected to one of the first, second, and third electrodes respectively. The first, second, third, and fourth electrodes are coupled to the fourth electrode. The first electrode, second, third, and fourth electrodes are set as the four pins of the four-electrode sensing module 3. The first electrode is connected as the current excitation electrode to the emitter of the 2N2222A transistor in the constant current source matrix module. The second electrode is connected as the negative terminal of the voltage detection to the inverting input terminal of the INA333 instrumentation amplifier in the multi-channel signal conditioning module 4. The third electrode is connected as the positive terminal of the voltage detection to the non-inverting input terminal of the INA333 instrumentation amplifier in the multi-channel signal conditioning module 4. The fourth electrode is coupled as the drive shielding electrode to the shielded drive circuit.

[0038] The multi-channel signal conditioning module 4 includes an INA333 instrumentation amplifier, a CD4051 multiplexer, and a second OPA2188 operational amplifier. The output of the INA333 instrumentation amplifier is connected to the non-inverting input of the second OPA2188 operational amplifier, the inverting input of the second OPA2188 operational amplifier is connected to its output, the output of the second OPA2188 operational amplifier is connected to the input channel of the CD4051 multiplexer, the output of the CD4051 multiplexer is connected to the input of the digital phase-locked loop amplifier module 5, and the controlled terminal of the CD4051 multiplexer is connected to the STM32F103C8T6 controller in the system control module 1.

[0039] The digital phase-locked loop (PLL) module 5 includes a CD4046 PLL, a first AD633 multiplier, a third OPA2188 operational amplifier, a fourth OPA2188 operational amplifier, a 90° phase shifter, and a CD4520 counter. The X1 input of the first AD633 multiplier is connected to the output of the CD4051 multiplexer in the multi-channel signal conditioning module 4. The reference input of the CD4046 PLL is connected to the reference signal output of the STM32F103C8T6 controller in the system control module 1. The output of the CD4046 PLL is connected to the clock input of the CD4520 counter. The first output of the CD4520 counter is connected to the Y1 input of the first AD633 multiplier. The second output terminal is connected to the Y2 input terminal of the first AD633 multiplier via a 90° phase shifter. The first output terminal of the first AD633 multiplier is connected to the inverting input terminal of the third OPA2188 operational amplifier via a fifth resistor. The output terminal of the third OPA2188 operational amplifier is connected to its inverting input terminal via a first capacitor to form a first integrator. The second output terminal of the first AD633 multiplier is connected to the inverting input terminal of the fourth OPA2188 operational amplifier via a sixth resistor. The output terminal of the fourth OPA2188 operational amplifier is connected to its inverting input terminal via a second capacitor to form a second integrator. The first output terminal of the first AD633 multiplier is used as the real part output, and the second output terminal of the first AD633 multiplier is used as the imaginary part output.

[0040] The temperature and humidity fusion compensation module 6 includes a PT1000 temperature sensor, a HIH6130 humidity sensor, a fifth OPA2188 operational amplifier, a sixth OPA2188 operational amplifier, a second AD633 multiplier, and a seventh OPA2188 operational amplifier. The output of the PT1000 temperature sensor is connected to the input of the fifth OPA2188 operational amplifier. The output of the fifth OPA2188 operational amplifier is reverse-connected to its non-inverting input through a seventh resistor. The output of the fifth OPA2188 operational amplifier is connected to the Y1 input of the second AD633 multiplier. The output of the HIH6130 humidity sensor is connected to the input of the sixth OPA2188 operational amplifier. The output of the operational amplifier is reverse-connected to its non-inverting input via the eighth resistor. The output of the sixth OPA2188 operational amplifier is connected to the Y2 input of the second AD633 multiplier. The X1 input of the second AD633 multiplier is connected to the output of the CD4051 multiplexer in the multi-channel signal conditioning module 4. The X2 input of the second AD633 multiplier is connected to the output of the LF398 sample-and-hold circuit in the solidification kinetic model processing module 7. The first and second outputs of the second AD633 multiplier are connected to the two inputs of the seventh OPA2188 operational amplifier, respectively. The output of the seventh OPA2188 operational amplifier is connected to the input of the LM349 operational amplifier in the solidification kinetic model processing module 7.

[0041] The solidified dynamic model processing module 7 includes an LM349 operational amplifier, a LOG114 precision logarithmic amplifier, an AD734 analog divider, a CD4538 monostable multivibrator, and an LF398 sample-and-hold circuit. The output of the LM349 operational amplifier is connected to the X input of the AD734 analog divider through a ninth resistor. The output of the LF398 sample-and-hold circuit is connected to the Y input of the AD734 analog divider through a tenth resistor. The output of the AD734 analog divider is connected to the non-inverting input of the LOG114 precision logarithmic amplifier. The output of the LOG114 precision logarithmic amplifier is connected to the trigger terminal of the CD4538 monostable multivibrator. The output of the CD4538 monostable multivibrator is connected to the input of the three-level warning output module 8.

[0042] The three-level early warning output module 8 includes an LM311 voltage comparator, an LM339 four-channel differential comparator, a DAC8043 analog-to-digital converter, a ULN2003 Darlington transistor array, three PC817 optocouplers, a second MCP4131 digital potentiometer, a yellow LED, a green LED, and a red LED. The input and output terminals of the DAC8043 analog-to-digital converter are connected to the data terminal of the STM32F103C8T6 controller in the system control module 1 and the output terminal of the CD4538 monostable multivibrator in the solidified dynamic model processing module 7. The output terminal of the DAC8043 analog-to-digital converter is connected through the first... Two MCP4131 digital potentiometers are connected to the non-inverting input of an LM311 voltage comparator and the non-inverting input of an LM339 quad differential comparator. The output of the LM311 voltage comparator is connected to the input of two PC817 optocouplers. The outputs of the two PC817 optocouplers are connected to a green LED and a red LED respectively via a ULN2003 Darlington transistor array. The output of the LM339 quad differential comparator is connected to the input of the last PC817 optocoupler. The output of this PC817 optocoupler is connected to a yellow LED via a ULN2003 Darlington transistor array.

[0043] System control module 1 includes an STM32F103C8T6 controller, a DS3231 real-time clock, and a 24C256 electrically erasable programmable read-only memory. The STM32F103C8T6 controller is connected to the DS3231 real-time clock and the 24C256 electrically erasable programmable read-only memory.

[0044] The cardboard box quality inspection system operates by including the following steps:

[0045] Multi-frequency impedance baseline calibration: The system control module 1 drives the constant current source matrix module 2 to output excitation currents of three frequencies to the four-electrode sensing module 3. The initial impedance of qualified samples is collected through the multi-channel signal conditioning module 4 and the digital lock-in amplifier module 5, and their arithmetic mean is calculated as the reference impedance. The system control module 1 sets the constant current source matrix module 2 to output 0.5 mA current at a frequency of 100 kHz, 1 mA current at a frequency of 1 MHz, and 2 mA current at a frequency of 10 MHz. The impedance data of no less than fifty qualified samples are collected and the average value is calculated.

[0046] Time-varying impedance ratio calculation: The digital phase-locked amplifier module 5 measures the impedance value in real time and calculates the percentage of the absolute difference between the current impedance and the reference impedance to the reference impedance. The digital phase-locked amplifier module 5 outputs the real and imaginary part measurement values ​​once every 0.1 seconds and calculates the absolute value of the current impedance value minus the reference impedance value, divided by the reference impedance value and then multiplied by 100%.

[0047] Curing characteristic parameter extraction: The curing kinetic model processing module 7 calculates the following based on the impedance percentage data at three frequency points: the first characteristic parameter is the difference between the impedance percentages at 10 MHz and 1 MHz; the second characteristic parameter is the quotient of the impedance percentages at 100 kHz and 10 MHz; and the third characteristic parameter is the complex phase angle between the impedance at 1 MHz and 10 MHz. The first characteristic parameter is the impedance percentage at 10 MHz minus the impedance percentage at 1 MHz; the second characteristic parameter is the impedance percentage at 100 kHz divided by the impedance percentage at 10 MHz; and the third characteristic parameter is the phase angle between the complex impedance at 1 MHz and the complex impedance at 10 MHz.

[0048] Temperature and humidity fusion compensation: The temperature and humidity fusion compensation module 6 multiplies the first to third feature parameters by the temperature compensation factor and the humidity compensation factor, respectively. The temperature compensation factor is 1 minus 0.004 multiplied by the difference between the current temperature and 25 degrees Celsius, and the humidity compensation factor is 1 minus 0.0015 multiplied by the difference between the current relative humidity and 50%. Each feature parameter is multiplied by the temperature compensation coefficient and the humidity compensation coefficient, respectively. The temperature compensation coefficient is 1 minus 0.004 multiplied by the difference between the current temperature and 25, and the humidity compensation coefficient is 1 minus 0.0015 multiplied by the difference between the current relative humidity and 50%.

[0049] Curing index calculation: The curing kinetics model processing module 7 divides the compensated first characteristic parameter by its maximum value and multiplies it by 0.5, multiplies the natural exponent of the compensated second characteristic parameter by 0.3 times its negative zero point one, and multiplies the sine value of the compensated third characteristic parameter by 0.2. The sum of these three results is the curing index. The curing index is equal to: the first characteristic parameter divided by its historical maximum value and multiplied by 0.5, plus the base of the natural logarithm multiplied by the second characteristic parameter raised to the power of 0.3, plus the sine value of the third characteristic parameter multiplied by 0.2.

[0050] Curing kinetics prediction: System control module 1 obtains the rate constant by dividing the difference between the current curing index and the curing index of the previous second by one and subtracting the current curing index. Then, it calculates the final curing index by multiplying the negative rate constant based on the base of the natural logarithm by 28,800 seconds. The rate constant is equal to the difference between the current curing index and the curing index of the previous second divided by one and subtracting the current curing index. The final curing index is equal to the current curing index plus one minus the difference between the current curing index multiplied by the negative rate constant based on the base of the natural logarithm multiplied by 28,800 seconds.

[0051] Risk grading decision: The three-level early warning output module 8 triggers a red light alarm when the final solidification index is less than 0.7, a yellow light alarm when it is between 0.7 and 0.8, and a green light alarm when it is greater than or equal to 0.8. The trigger condition for a red light alarm is that the final solidification index is less than 0.7; the trigger condition for a yellow light alarm is that the final solidification index is greater than or equal to 0.7 and less than 0.8; and the trigger condition for a green light alarm is that the final solidification index is greater than or equal to 0.8.

[0052] Dynamic threshold update: When the basis weight of the raw paper is greater than 200 grams, the system control module 1 sets the benchmark threshold to the difference of 0.75 multiplied by 1 plus 0.002 multiplied by the basis weight minus 150; when the basis weight is less than or equal to 200 grams, the benchmark threshold is 0.8; when the basis weight of the raw paper is greater than 200 grams, the benchmark threshold value is 0.75 multiplied by 1 plus 0.002 multiplied by the basis weight minus 150; when the basis weight is less than or equal to 200 grams, the benchmark threshold value is 0.8.

[0053] Specifically, this system starts immediately after the carton comes off the production line. The four-electrode sensing module 3 contacts the center area of ​​the adhesive line with a pressure of 5 Newtons. Its 0.3 mm radius of curvature probe pierces the carton's face paper 0.1 mm deep to reach the adhesive layer. The constant current source matrix module 2 synchronously outputs three-band excitation currents—100 kHz (0.5 mA), 1 MHz (1.0 mA), and 10 MHz (2.0 mA). The current is injected into the adhesive layer through the current-driven electrode to form a detection electric field with a depth of 0.2-1 mm. At this time, the voltage detection electrode and the voltage reference electrode capture the micro-region voltage drop signal of the adhesive layer with a spacing of 0.5 mm. This signal is amplified by 100 times gain by the multi-channel signal conditioning module 4. The processed signal is input to the digital phase-locked loop amplifier module 5. The CD4046 phase-locked loop generates a signal synchronized with the excitation. Using a reference square wave, the first AD633 multiplier performs quadrature demodulation on the input signal. The real and imaginary parts of the impedance are output by a 10-millisecond time constant integrator composed of an OPA2188 operational amplifier. The system control module 1 collects this data every 100 milliseconds and performs multi-frequency impedance baseline calibration. It calls the average impedance of 50 pre-stored grid sample references and calculates the percentage of the absolute difference between the current impedance and the reference value. Based on this, the solidification kinetic model processing module 7 extracts three core characteristic parameters: the difference between 10 MHz and 1 MHz as the high-frequency loss difference P1, the quantification of hydrogen bond network density, and the quotient of 100 kHz and 10 MHz as the moisture absorption ratio P2, which characterizes the moisture distribution gradient and the phase angle difference P3 between the 1 MHz complex impedance and the 10 MHz complex impedance, indicating the molecular orientation state.

[0054] The temperature and humidity fusion compensation module 6 synchronously reads temperature and humidity data, performs dynamic correction on each characteristic parameter, and multiplies P1-P3 by a composite compensation coefficient to eliminate environmental interference. The corrected parameters are then input into the curing index synthesis algorithm.

[0055] The system control module 1 calculates the curing rate constant based on the real-time curing index increment of the most recent second, and substitutes it into the exponential decay model to predict the final curing state after eight hours of storage.

[0056] At this time, the three-level early warning output circuit dynamically sets the threshold according to the paper type and weight. When the weight is less than or equal to 200g, the reference threshold is 0.8. When it is greater than 200g, it is adjusted by 0.75×[1+0.002×(GSM-150)]. If the predicted CI∞<0.7, the red LED alarm is driven, indicating that the hydrogen bond formation rate is insufficient. If 0.7≤CI∞<0.8, a yellow warning is triggered. If CI∞≥0.8, a green pass signal is output.

[0057] The entire testing process is short. By quantifying the evolution of the dielectric properties of the adhesive layer and the curing kinetic parameters, the traditional adhesive strength, which requires several hours to verify, is transformed into a τ value early warning indicator, thus avoiding a large number of missed detections caused by the time difference between the apparent curing of starch adhesive and the formation of its true strength.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A cardboard box quality inspection system, characterized in that, It includes a system control module (1), a constant current source matrix module (2), a four-electrode sensing module (3), a multi-channel signal conditioning module (4), a digital phase-locked amplifier module (5), a temperature and humidity fusion compensation module (6), a solidification dynamics model processing module (7), and a three-level early warning output module (8); The output terminal of the constant current source matrix module (2) is connected to the current injection terminal and the shielding drive terminal of the four-electrode sensing module (3). The voltage detection terminal of the four-electrode sensing module (3) is connected to the differential input terminal of the multi-channel signal conditioning module (4). The output terminal of the multi-channel signal conditioning module (4) is connected to the signal input terminal of the digital phase-locked amplifier module (5). The real / imaginary output terminal of the digital phase-locked amplifier module (5) is connected to the input terminal of the temperature and humidity fusion compensation module (6). The compensation output terminal of the temperature and humidity fusion compensation module (6) is connected to the impedance input terminal of the curing kinetic model processing module (7). The time constant output terminal of the curing kinetic model processing module (7) is connected to the analog input terminal of the three-level early warning output module (8). The SPI interface of the system control module (1) is connected to the control terminal of the constant current source matrix module (2) and the three-level early warning output module (8). Its input pin is connected to the output terminal of the digital phase-locked amplifier module (5). The enable terminal of the three-level early warning output module (8) is connected to the data terminal of the system control module (1).

2. The cardboard box quality inspection system according to claim 1, characterized in that, The constant current source matrix module (2) includes a REF02 voltage reference, a first OPA2188 operational amplifier, a first MCP4131 digital potentiometer, and a 2N2222A transistor; The output terminal of the REF02 voltage reference is connected to the non-inverting input terminal of the first OPA2188 operational amplifier through a first resistor. The ground terminal of the REF02 voltage reference is grounded. The power terminal of the REF02 voltage reference is connected to a 12V power supply. The sliding terminal of the first MCP4131 digital potentiometer is connected to the inverting input terminal of the first OPA2188 operational amplifier through a second resistor. The first fixed terminal of the first MCP4131 digital potentiometer is grounded. The second fixed terminal of the first MCP4131 digital potentiometer is left floating. The chip select terminal, data terminal, and clock terminal of the first MCP4131 digital potentiometer are all connected to the STM32F103C8T6 controller in the system control module (1). The output terminal of the first OPA2188 operational amplifier is connected to the base of the 2N2222A transistor through a third resistor. The emitter of the 2N2222A transistor is connected to a four-electrode sensor through a fourth resistor. The collector of the 2N2222A transistor is connected to a 24V power supply.

3. The cardboard box quality inspection system according to claim 1, characterized in that, The four-electrode sensing module (3) includes a ceramic substrate, a platinum electrode array etched on the ceramic substrate, a polyimide insulating layer fixedly connected to the ceramic substrate and covering the platinum electrode array, and spring probes soldered to the ceramic substrate and coupled to the platinum electrode array. The polyimide insulating layer has through holes through which the spring probes can pass. The polyimide insulating layer is bonded to the ceramic substrate with epoxy adhesive. The platinum electrode array includes a first electrode, a second electrode, a third electrode, and a fourth electrode. There are four spring probes, each connected to one of the first, second, third, and fourth electrodes respectively. The first, second, third, and fourth electrodes are coupled to the fourth electrode. The first electrode, second electrode, third electrode, and fourth electrode are set as the four pins of the four-electrode sensing module (3). The first electrode is connected as the current excitation electrode to the emitter of the 2N2222A transistor in the constant current source matrix module. The second electrode is connected as the negative terminal of voltage detection to the inverting input terminal of the INA333 instrumentation amplifier in the multi-channel signal conditioning module (4). The third electrode is connected as the positive terminal of voltage detection to the non-inverting input terminal of the INA333 instrumentation amplifier in the multi-channel signal conditioning module (4). The fourth electrode is coupled to the shielded driving circuit as the driving shield electrode.

4. The cardboard box quality inspection system according to claim 1, characterized in that, The multi-channel signal conditioning module (4) includes an INA333 instrumentation amplifier, a CD4051 multiplexer, and a second OPA2188 operational amplifier; The output of the INA333 instrumentation amplifier is connected to the non-inverting input of the second OPA2188 operational amplifier, the inverting input of the second OPA2188 operational amplifier is connected to its output, the output of the second OPA2188 operational amplifier is connected to the input channel of the CD4051 multiplexer, the output of the CD4051 multiplexer is connected to the input of the digital phase-locked loop amplifier module (5), and the controlled terminal of the CD4051 multiplexer is connected to the STM32F103C8T6 controller in the system control module (1).

5. The cardboard box quality inspection system according to claim 1, characterized in that, The digital phase-locked amplifier module (5) includes a CD4046 phase-locked loop, a first AD633 multiplier, a third OPA2188 operational amplifier, a fourth OPA2188 operational amplifier, a 90° phase shifter, and a CD4520 counter. The X1 input of the first AD633 multiplier is connected to the output of the CD4051 multiplexer in the multi-channel signal conditioning module (4). The reference input of the CD4046 phase-locked loop is connected to the reference signal output of the STM32F103C8T6 controller in the system control module (1). The output of the CD4046 phase-locked loop is connected to the clock terminal of the CD4520 counter. The first output of the CD4520 counter is connected to the Y1 input of the first AD633 multiplier. The second output of the CD4520 counter is connected to the Y2 input of the first AD633 multiplier through a 90° phase shifter. The first output of the first AD633 multiplier is connected to the inverting input of the third OPA2188 operational amplifier through a fifth resistor. The output of the third OPA2188 operational amplifier is connected to its inverting input through a first capacitor to form a first integrator. The second output of the first AD633 multiplier is connected to the inverting input of the fourth OPA2188 operational amplifier through a sixth resistor. The output of the fourth OPA2188 operational amplifier is connected to its inverting input through a second capacitor to form a second integrator. The first output of the first AD633 multiplier is used as the real part output, and the second output of the first AD633 multiplier is used as the imaginary part output.

6. The cardboard box quality inspection system according to claim 1, characterized in that, The temperature and humidity fusion compensation module (6) includes a PT1000 temperature sensor, a HIH6130 humidity sensor, a fifth OPA2188 operational amplifier, a sixth OPA2188 operational amplifier, a second AD633 multiplier, and a seventh OPA2188 operational amplifier. The output of the PT1000 temperature sensor is connected to the input of the fifth OPA2188 operational amplifier. The output of the fifth OPA2188 operational amplifier is reverse-connected to its non-inverting input through a seventh resistor. The output of the fifth OPA2188 operational amplifier is connected to the Y1 input of the second AD633 multiplier. The output of the HIH6130 humidity sensor is connected to the input of the sixth OPA2188 operational amplifier. The output of the sixth OPA2188 operational amplifier is reverse-connected to its non-inverting input through an eighth resistor. The output of the sixth OPA2188 operational amplifier is connected to the second AD633 multiplier. The Y2 input terminal of the AD633 multiplier and the X1 input terminal of the second AD633 multiplier are connected to the output terminal of the CD4051 multiplexer in the multi-channel signal conditioning module (4). The X2 input terminal of the second AD633 multiplier is connected to the output terminal of the LF398 sample-and-hold circuit in the solidification dynamics model processing module (7). The first and second output terminals of the second AD633 multiplier are respectively connected to the two input terminals of the seventh OPA2188 operational amplifier. The output terminal of the seventh OPA2188 operational amplifier is connected to the input terminal of the LM349 operational amplifier in the solidification dynamics model processing module (7).

7. The cardboard box quality inspection system according to claim 1, characterized in that, The solidification dynamics model processing module (7) includes an LM349 operational amplifier, a LOG114 precision logarithmic amplifier, an AD734 analog divider, a CD4538 monostable multivibrator, and an LF398 sample-and-hold circuit. The output of the LM349 operational amplifier is connected to the X input of the AD734 analog divider via the ninth resistor. The output of the LF398 sample-and-hold circuit is connected to the Y input of the AD734 analog divider via the tenth resistor. The output of the AD734 analog divider is connected to the non-inverting input of the LOG114 precision logarithmic amplifier. The output of the LOG114 precision logarithmic amplifier is connected to the trigger of the CD4538 monostable multivibrator. The output of the CD4538 monostable multivibrator is connected to the input of the three-level warning output module (8).

8. A cardboard box quality inspection system according to claim 1, characterized in that, The three-level early warning output module (8) includes an LM311 voltage comparator, an LM339 four-channel differential comparator, a DAC8043 analog-to-digital converter, a ULN2003 Darlington transistor array, three PC817 optocouplers, a second MCP4131 digital potentiometer, a yellow LED, a green LED, and a red LED. The input and output terminals of the DAC8043 analog-to-digital converter are connected to the data terminal of the STM32F103C8T6 controller in the system control module (1) and the output terminal of the CD4538 monostable multivibrator in the solidified dynamic model processing module (7). The output terminal of the DAC8043 analog-to-digital converter is connected to the non-inverting input terminal of the LM311 voltage comparator and the non-inverting input terminal of the LM339 four-channel differential comparator through the second MCP4131 digital potentiometer. The output terminal of the LM311 voltage comparator is connected to the input terminals of two PC817 optocouplers. The output terminals of the two PC817 optocouplers are connected to the green LED and the red LED respectively through the ULN2003 Darlington transistor array. The output terminal of the LM339 four-channel differential comparator is connected to the input terminal of the last PC817 optocoupler. The output terminal of the PC817 optocoupler is connected to the yellow LED through the ULN2003 Darlington transistor array.

9. A cardboard box quality inspection system according to claim 1, characterized in that, The system control module (1) includes an STM32F103C8T6 controller, a DS3231 real-time clock, and a 24C256 electrically erasable programmable read-only memory. The STM32F103C8T6 controller is connected to the DS3231 real-time clock and the 24C256 electrically erasable programmable read-only memory.

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