An automatic gluing and intelligent detection system for a packaging box

Abstract

The application discloses a kind of packing box automatic gluing intelligent detection systems, belong to gluing detection field.The method is driven main gluing module to carry out glue discharge operation, and utilize internal probe module to collect the acoustic echo in glue line in real time, and calculate the real-time density parameter reflecting the density degree of colloid accordingly;When density deviates target range, deviation compensation operation based on change trend judgment is executed, and extrusion pressure is adjusted by segmented matching nonlinear pressure compensation step value adjustment.In the extreme working condition that main gluing module reaches pressure limit and density still does not reach standard, collaborative intervention unit activates the auxiliary compensation module output ultrasonic vibration of gun nozzle end, and the mechanical shear force of high-frequency vibration is used to reduce the viscosity of colloid and drive internal micro-bubble migration to escape.The application effectively solves the problem of hidden bubble missed detection in high-speed gluing and high-viscosity fluid extrusion obstruction caused by degumming or glue overflow, and improves the reliability of packaging automation production.

Description

Technical Field

[0001] This invention relates to the field of adhesive coating inspection, and more specifically, to an intelligent inspection system for automatic adhesive coating of packaging boxes. Background Technology

[0002] In the field of modern packaging manufacturing, the quality of adhesive coating on packaging boxes directly determines not only the overall sealing performance and structural compressive strength of the packaging, but also the safety, moisture-proof, and anti-counterfeiting performance of the product during long-distance transportation, stacking and compression, and extreme temperature and humidity environments. With the continuous increase in the operating speed of fully automated packaging lines, the adhesive coating process struggles to meet the requirements of high-speed and stable operation. Under the combined influence of various physical parameters such as high-speed extrusion, frequent machine start-ups and shutdowns, complex changes in spatial trajectories, and dynamic fluctuations in ambient temperature and humidity, the rheological properties of polymer adhesive fluids are prone to transient nonlinear changes.

[0003] For example, Chinese patent application number 202511583215.5 discloses an intelligent detection system and method for automatic glue application on packaging boxes, including a glue application adaptation analysis module, a glue box adaptation module, a glue material adaptation analysis module, and a glue application monitoring and adjustment module. This solution uses sensors such as high-speed industrial cameras, infrared thermal imagers, and laser thickness gauges as stage detection units to collect apparent dynamic parameters of the glue throughout the curing cycle, such as the surface width, edge lifting height of the glued area, and surface thermal radiation temperature field. Simultaneously, this solution correlates glue performance data with the material parameters of the packaging box, constructing a dynamic monitoring model based on a hybrid architecture of time-series prediction and static classification. This allows for the generation of corresponding parameter adjustment instructions when abnormalities in the glued surface dimensions or temperature are detected.

[0004] While the aforementioned inventions, by introducing multi-dimensional monitoring of apparent dynamic features, have to some extent addressed the issues of delayed detection, passive scrapping, and inefficiency, existing visual and thermal radiation sensors cannot penetrate opaque polymer colloids and can only detect surface morphology and temperature. However, during high-speed extrusion or fluctuations in glue supply negative pressure, hidden microbubbles or voids are easily generated inside the glue line. These internal bubbles cannot be visually detected due to surface tension, leading to missed detections and allowing defective products with hidden delamination risks to flow downstream. Because minute internal stresses amplify rapidly at the bubble edges, the glue... The line breaks instantly due to cohesive failure, leading to large-scale delamination and even cracking of the packaging box. Moreover, after discovering poor glue dispensing, the adjustment method only relies on adjusting the extrusion pressure of the main pump. High molecular weight adhesives have strong viscoelasticity. When the low temperature causes the adhesive to thicken or the nozzle to become microscopically blocked, the existing control system can only cope by increasing the pressure of the main pump. When this high pressure finally breaks through the viscous resistance barrier at the front end, the highly compressed adhesive is released instantaneously, causing a surge in the amount of adhesive extruded, exceeding the predetermined coating trajectory and causing glue overflow. This not only wastes the adhesive but also contaminates the packaging box and the production line equipment. Summary of the Invention

[0005] In order to overcome the above-mentioned defects of the prior art, the present invention provides an intelligent detection system for automatic gluing of packaging boxes to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an intelligent detection system for automatic gluing of packaging boxes, comprising: Main coating module: Used to execute the first main control command to drive fluid extrusion for dispensing adhesive; Internal detection module: used to collect the internal acoustic echo of the glue line at the current glue application position, and calculate the real-time density parameter reflecting the internal density of the glue line based on the internal acoustic echo; Status determination unit: used to determine the deviation status based on the real-time density parameter within a preset monitoring period; Control module: used to perform control based on the result of the state determination unit: when the density is within the target range, maintain the current first master control command; when the density deviates from the target range, perform deviation compensation operation and adjust the pressure parameter of the first master control command to guide the density inside the adhesive line to recover to the target range.

[0007] Preferably, the internal detection module is located behind the main adhesive coating module, and its detection center points to the center of the adhesive line that has just been extruded from the main adhesive coating module.

[0008] Preferably, the acquisition frequency of the internal detection module is adjusted synchronously with the adhesive application speed of the main adhesive application module to ensure that multiple sets of internal acoustic echoes are acquired at the same adhesive application point within the preset monitoring period.

[0009] Preferably, the system further includes an auxiliary compensation module, which is disposed at the end of the extrusion nozzle of the main coating module; the auxiliary compensation module is provided with an ultrasonic transducer for receiving vibration frequency commands and converting them into physical ultrasonic excitation, which directly acts on the colloid flowing through the extrusion nozzle.

[0010] Preferably, the deviation compensation operation specifically includes: When the real-time density parameter is continuously lower than the preset lower limit within the preset monitoring period, it is determined that there is a bubble defect inside the adhesive line, and the extrusion pressure parameter is increased. When the real-time density parameter exceeds the preset upper limit and its rate of change is not less than zero, it is determined that there is a risk of glue overflow, and the extrusion pressure parameter is reduced. When the real-time density parameter exceeds the preset upper limit and its rate of change is less than zero, it is determined that the glue line state is recovering on its own, and the current extrusion pressure parameter is maintained.

[0011] Preferably, when the control module increases the extrusion pressure parameter: Based on the deviation of the real-time compaction parameter from the preset lower limit, a corresponding pressure compensation step value is matched in segments; wherein, the deviation is divided into at least three consecutive pressure steps, and the pressure compensation step value increases stepwise as the real-time compaction parameter decreases, so as to achieve nonlinear pressure compensation for defects of different severity.

[0012] Preferably, the system further includes a collaborative intervention unit, which monitors the operating power of the main coating module in real time. When the extrusion pressure increases to the maximum set value and the density is still lower than the preset lower limit, the main coating module is kept running at the maximum set value. At the same time, the collaborative intervention unit activates the auxiliary compensation module to output ultrasonic excitation, using high-frequency vibration to destroy the bubble structure in the colloid and instantly reduce the viscosity of the colloid. The collaborative intervention unit is also used to dynamically adjust the vibration intensity of the auxiliary compensation module according to the density recovery in subsequent monitoring cycles.

[0013] Preferably, the ultrasonic vibration output by the auxiliary compensation module is perpendicular to the extrusion direction of the adhesive, reducing the flow resistance of the adhesive on the wall of the extrusion nozzle through mechanical shearing force; the microfluidic effect generated by the ultrasonic vibration drives the microbubbles in the adhesive to migrate to the surface of the adhesive line and escape.

[0014] Preferably, the collaborative intervention unit includes an exit method for the auxiliary compensation module, specifically: When the density returns to the target range, the extrusion pressure parameter of the main coating module is gradually reduced until it returns to the normal operating range. After the extrusion pressure drops to the normal operating range, the vibration intensity of the auxiliary compensation module is gradually reduced and the auxiliary compensation module is eventually turned off.

[0015] Preferably, the collaborative intervention unit includes: a gain allocation subunit: used to dynamically allocate control weights between adjusting the extrusion pressure increment of the main coating module and adjusting the vibration power increment of the auxiliary compensation module according to the deviation of the real-time density parameter.

[0016] The technical effects and advantages of this invention are as follows: 1. This invention, by configuring an internal detection module, utilizes the significant acoustic characteristic difference between colloids and bubbles to capture the acoustic scattering echo signal inside the adhesive line. This elevates traditional two-dimensional morphology detection, which focuses on the surface, to a three-dimensional assessment reflecting the internal density of the colloid. It can effectively identify hidden microbubbles and continuous voids concealed by the surface tension of the colloid, eliminating the risk of delayed delamination and packaging cracking caused by missed internal defects.

[0017] 2. This invention introduces a density change rate prediction mechanism in the deviation compensation operation. When the real-time density parameter exceeds a preset upper limit but its change rate is negative, the glue line state is determined to be in a self-recovery phase, and the current extrusion pressure is maintained, avoiding glue output oscillations caused by over-adjustment. Simultaneously, when performing pressurization operations to address bubble defects, at least three pressure steps are defined based on the deviation of the density from the preset lower limit, and a non-linear pressure compensation step value that increases stepwise with the deviation magnitude is adopted. This strategy balances smooth micro-adjustment for minor defects with instantaneous strong correction for severe defects, improving the accuracy of glue coating process parameter adjustment.

[0018] 3. In extreme cases where the main coating module's extrusion pressure reaches its maximum set value but the density still fails to meet the target, this invention activates the auxiliary compensation module to output ultrasonic excitation. The mechanical shear force of ultrasonic vibration can instantly reduce the apparent viscosity of high-viscosity colloids, reducing flow resistance on the extrusion nozzle wall; simultaneously, the microfluidic effect induced by ultrasound drives microbubbles inside the colloid to migrate to the surface and escape. This effectively solves the problems of flow channel blockage, extrusion obstruction, and hidden bubble residue caused by low-temperature environments or gel impurities, and smoothly exits after density recovery by first reducing pressure and then turning off vibration, ensuring the continuity and stability of the coating process. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the main adhesive application module, internal detection module, and auxiliary compensation module of the present invention. Figure 2 This is a system architecture diagram of the present invention; Figure 3 This is a flowchart of the deviation detection and pressure compensation logic in this invention.

[0020] In the picture: 1. Main adhesive application module; 2. Internal detection module; 3. Control module; 4. Auxiliary compensation module. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 Existing adhesive coating inspection systems primarily rely on high-speed cameras to capture two-dimensional images of the surface or laser displacement sensors to measure the height of the adhesive line. However, industrial packaging adhesives are typically opaque or semi-transparent after application, preventing light from penetrating their interior. In actual production, when brief cavitation occurs at the suction end of the adhesive pump, or when cavitation occurs as the adhesive flows at high speed through the nozzle slit, numerous tiny air bubbles are easily trapped within the adhesive. These bubbles are trapped inside the adhesive line due to the adhesive's high surface tension, ensuring that the dimensions of the adhesive line still meet the acceptable tolerances set by visual inspection. Consequently, the system classifies these hollow adhesive lines with a significantly reduced effective bonding cross-sectional area as good quality. However, during subsequent processes, when the packaging box experiences temperature fluctuations or slight handling vibrations, these internal voids quickly develop into crack sources, causing large-scale delamination and ultimately leading to cracking at the adhesive joint.

[0023] To resolve the above technical issues, please refer to Figures 1 to 3 As shown, the first embodiment of the present invention provides an intelligent detection system for automatic gluing of packaging boxes, comprising: Main coating module 1: Used to execute the first main control command to drive fluid extrusion for dispensing adhesive; Internal Detection Module 2: Used to collect the internal acoustic echo of the glue line at the current glue application position, and calculate the real-time density parameter reflecting the internal density of the glue line based on the internal acoustic echo; Status determination unit: used to determine the deviation status based on the real-time density parameters within a preset monitoring period; Control module 3: Used to perform control based on the results of the state determination unit: when the density is within the target range, maintain the current first master control command; when the density deviates from the target range, perform deviation compensation operation and adjust the pressure parameter of the first master control command to guide the density inside the adhesive line to recover to the target range.

[0024] The internal detection module 2 is located behind the main glue application module 1, and its detection center points to the center of the glue line that the main glue application module 1 has just extruded. The acquisition frequency of the internal detection module 2 is adjusted synchronously with the glue application speed of the main glue application module 1 to ensure that multiple sets of internal acoustic echoes are obtained at the same glue application point within the preset monitoring period.

[0025] Specifically, this embodiment introduces a detection architecture based on high-frequency acoustic physics into the system. In actual working scenarios, the main adhesive application module 1, under the first master control command, drives molten or liquid adhesive to be evenly applied onto the predetermined bonding trajectory of the packaging box through a precision extrusion nozzle. Simultaneously with the extrusion action, the core sensing process of this invention is activated. To achieve real-time non-destructive testing of internal defects within the adhesive line, an internal detection module 2 is fixedly installed behind the main adhesive application module 1. This internal detection module 2 incorporates a crosshair laser locator to ensure that its detection center always points to the center of the adhesive line just extruded from the main adhesive application module 1. The internal detection module 2 captures the moment when the adhesive has just detached from the nozzle constraint and deposited on the substrate surface, but before the internal polymer chains have fully cross-linked or cooled and solidified. At this time point, the morphology of bubbles is most active, and the physical characteristics of internal defects are most obvious. Early detection of these internal voids provides valuable time for subsequent control system parameter adjustments.

[0026] During the detection process, the internal detection module 2 emits a sequence of high-frequency ultrasonic pulses at a specific frequency into the adhesive line. According to the laws of acoustic physics, sound waves exhibit relatively smooth and stable exponential acoustic attenuation when propagating in a uniform, dense liquid or semi-solid colloidal continuous medium. When the main adhesive application module 1 draws in air, a cluster of tiny gaseous bubbles is generated inside the adhesive line. Since the liquid adhesive and the gas inside the bubbles are two media with different physical properties in terms of physical density and elasticity, there is a significant difference in their acoustic characteristics. When the high-frequency ultrasonic waves travel and are incident on the physical interface between the adhesive and the gas, the sound wave energy that originally penetrated forward will undergo strong scattering and high-energy reflection due to the drastic change in the medium. The ultrasonic receiving array of the internal detection module 2 will capture these multipath internal acoustic echo signals reflected back from inside the colloidal medium.

[0027] After receiving these simulated echo signals containing the physical characteristics of bubbles, control module 3 performs real-time calculations to extract the peak energy curve of the characteristic scattered waves. Subsequently, control module 3 compares and performs a reverse mapping operation on the total integrated energy of all characteristic scattered waves within a unit time window with the acoustic attenuation baseline model of a pre-calibrated pure, bubble-free reference adhesive line. This converts the abstract acoustic scattering cross-section into an intuitive, quantitative physical index: the real-time density parameter. A larger value indicates low attenuation propagation of sound waves internally, indicating a dense and full colloid. A lower value signifies stronger internal scattered echoes, proving that the colloid is filled with microbubbles, or even contains large, continuous voids, indicating a loose, dangerous structure with potential hazards.

[0028] Since modern packaging box gluing is often accompanied by high-speed movement of robotic arms or rapid operation of conveyor belts, this embodiment specifically sets up a spatiotemporal synchronization mechanism for acoustic acquisition to avoid errors caused by sparse spatial sampling points. That is, the acquisition frequency of the internal detection module 2 is not a fixed value, but is adjusted in a closed-loop synchronization with the gluing speed by reading the encoder pulses of the servo motor of the main gluing module 1. When the robotic arm accelerates to perform high-speed gluing along long straight edges, the repetition frequency of the ultrasonic emission pulses of the internal detection module 2 increases proportionally; when the robotic arm decelerates to perform corner gluing, the acquisition frequency decreases accordingly. This dynamic adaptive triggering mechanism ensures that, under any extreme fluctuations in the gluing line speed, the system can continuously acquire multiple sets of internal acoustic echoes at the same physical point on the packaging box within the set preset monitoring period. These continuously acquired echo data sets are sent to a moving average filter for noise reduction and smoothing, eliminating blind spots or false alarms caused by excessively fast mechanical movement, providing more accurate and reliable data for the subsequent control module 3. Based on this real-time density parameter, the status determination unit maintains the current extrusion command when the density is within the safe threshold, and performs compensation once it deviates, thus realizing a precise closed loop from perception to decision-making. When the density parameter is lower than the preset lower limit, the control module 3 simultaneously generates the location coordinates of defective products and sends them to the downstream rejection mechanism for waste removal.

[0029] To achieve precise detection of tiny air bubbles within the colloid, this embodiment defines the ultrasonic testing frequency emitted by the internal detection module 2. The frequency of the high-frequency ultrasonic pulse is set to 1MHz to 10MHz. Considering the viscous decay characteristics of the polymer packaging adhesive and the typical microscopic size distribution of bubbles generated during the coating process, the preferred center frequency range is 2MHz to 5MHz. At this frequency band, the wavelength of the ultrasonic waves matches the micrometer to sub-millimeter size of the hidden bubbles within the adhesive line, inducing significant Rayleigh scattering while possessing sufficient penetration to overcome the acoustic attenuation of the high-viscosity fluid, thereby maximizing the signal-to-noise ratio of the characteristic echo and achieving high-precision detection of deep air bubbles.

[0030] The auxiliary compensation module 4 employs a ring-array piezoelectric ceramic transducer structure. This transducer is rigidly secured to the outer wall of the extrusion nozzle of the main coating module 1 via a rigid mechanical clamp or interference fit, allowing ultrasonic vibration energy to be uniformly focused radially into the internal glue flow channel, avoiding flow field deviation caused by unilateral excitation. Simultaneously, a damping vibration isolation kit is configured between the housing of the auxiliary compensation module 4 and the mounting base of the main coating module 1. This kit absorbs and blocks unintended transmission of ultrasonic waves to the robotic arm or motion axis, physically isolating the high-frequency excitation force from interfering with the end effector's pose accuracy, ensuring that the system's macroscopic coating spatial trajectory maintains high precision and stability even under high-intensity ultrasonic compensation.

[0031] Example 2 As can be seen from the above embodiments, although Embodiment 1 solved the problem of invisible air bubbles inside the glue line through acoustic physical detection, in the traditional closed-loop control system, when insufficient glue application is detected, a simple PID algorithm or threshold judgment logic is usually used to directly and linearly increase the extrusion pressure of the main pump. However, polymer glue has extremely strong viscoelasticity and pressure transmission hysteresis. When the actuator changes the extrusion pressure at the back end, the actual output state of the fluid at the nozzle front end will not change instantaneously, but there is a time lag and inertial impulse. If the density drops briefly, the system continues to pressurize, and the pressure accumulates rapidly in the hose. When the air bubble is suddenly discharged or the fluid resistance decreases, the accumulated high pressure is released instantaneously, which will cause a large amount of glue overflow. This linear compensation control will cause the glue output to fluctuate repeatedly between insufficient glue and excessive glue states.

[0032] To resolve the above technical issues, please refer to Figures 1 to 3 As shown, this embodiment introduces a judgment step based on the changing trend and nonlinear step gain compensation logic in the deviation compensation operation.

[0033] The deviation compensation operation is as follows: When the real-time density parameter remains below the preset lower limit within the preset monitoring period, it is determined that there is a bubble defect inside the glue line, and the extrusion pressure parameter is increased. When the real-time density parameter exceeds the preset upper limit and its rate of change is not less than zero, it is determined that there is a risk of glue overflow, and the extrusion pressure parameter is reduced. When the real-time density parameter exceeds the preset upper limit and its rate of change is less than zero, it is determined that the glue line state is recovering on its own, and the current extrusion pressure parameter is maintained.

[0034] When control module 3 executes the process of increasing extrusion pressure parameters: Based on the deviation of the real-time density parameter from the preset lower limit, the corresponding pressure compensation step value is matched in segments; wherein, the deviation is divided into at least three consecutive pressure steps, and the pressure compensation step value increases stepwise as the real-time density parameter decreases, so as to achieve nonlinear pressure compensation for defects of different severity.

[0035] Specifically, when the system detects that the real-time density parameter remains below the preset lower limit within a preset monitoring period, the status determination unit determines that the main adhesive application module 1 has experienced an irreversible drop in liquid level and insufficient adhesive, or that the main adhesive application module 1 has inhaled air, causing the extruded adhesive line to actually present a semi-hollow tubular or honeycomb structure. At this time, the control module 3 generates an instruction to increase the extrusion pressure parameter. The purpose is to increase the adhesive flow rate per unit time and use mechanical static pressure to forcibly compress the volume of these air bubbles in the pipeline, thereby restoring the macroscopic structural compressive strength of the adhesive line.

[0036] When the system detects that the real-time density parameter exceeds the preset upper limit, this embodiment does not immediately reduce the pressure. Instead, it performs discrete differentiation on the density curve within the preset monitoring period and calculates its tangent slope, i.e., the rate of change. If the rate of change is found to be not less than zero (i.e., the rate of change is ≥0), it indicates that the density is still increasing over time or is in an abnormally high steady state. At this time, the colloid is on the edge of overfilling. If the current pressure is maintained, it will cause the glue to overflow from the coating trajectory. Therefore, the control module 3 generates a negative compensation command to reduce the extrusion pressure parameter, actively reducing the glue supply flow rate and suppressing glue overflow.

[0037] When the real-time density parameter exceeds the preset upper limit, but after algorithmic differentiation, it is found that its rate of change is less than zero (i.e., the rate of change < 0), this indicates that although the current absolute density parameter is still high, the fluid flow trend has reversed. Although the pressure reduction operation command in the early stage of the system has a physical delay on a macroscopic scale due to the flexible expansion of the pipeline, preventing the density from falling back to the safe zone, the internal elastic stress accumulated by the excessive compression of the fluid macromolecular chain segments is gradually being released. The fluid has actually begun to respond to the pressure reduction command and has entered a self-recovery state. If the pressure reduction operation is continued at this time, it is very easy to overcompensate and cause the glue line to become thinner. Therefore, when it is determined that the glue line state is recovering on its own, the control module 3 maintains the current output command and keeps the current extrusion pressure parameter unchanged, allowing the system a short period of stable state to naturally return to equilibrium.

[0038] This embodiment further addresses the quantitative execution problem of adjustment force. When increasing pressure to address low density, using a constant linear ratio for pressurization can easily lead to overcompensation for microbubble defects, while insufficient compensation for severe bubble defects. Therefore, a nonlinear stepped segmented matching compensation logic is introduced. The gain allocation algorithm divides the interval where the density is below a preset lower limit into at least three consecutive pressure steps. When the deviation of the real-time density parameter from the preset lower limit is found to be in a shallow deviation zone, it means that the colloid contains only a very small number of free microbubble clusters. When matching the corresponding pressure compensation step value in segments, the system allocates a small base gain coefficient using a lookup table method, increasing the fluid flow rate slightly to compensate for the internal micro-gaps without compromising the width and smoothness of the macroscopic adhesive lines.

[0039] When the density drops sharply, the detection data falls directly into the severe deviation range, indicating a possible serious cavitation in the adhesive supply line, leading to an impending adhesive failure and shutdown. At this point, the system's control weights immediately undergo a non-linear jump, traversing all linear adjustment zones and invoking the highest-order pressure compensation step value. This non-linear output mode, which rapidly increases in a stepwise manner as the real-time density parameter decreases, can quickly create fluid pressure pulses in the pipeline, injecting a large amount of fresh adhesive into the air chamber. This achieves non-linear pressure compensation for defects of varying severity, significantly expanding the system's survivability under extreme conditions.

[0040] Example 3 While the above embodiments can handle most routine anomalies on the production line through trend prediction and flexible nonlinear pressure regulation strategies, in harsh industrial production environments, such as winter when workshop insulation is lacking, the apparent viscosity of polymer hot melt adhesives or water-based adhesives can increase exponentially due to a sudden drop in ambient temperature. Alternatively, when the adhesive batch is substandard and incompletely dissolved polymer gel agglomerates appear internally, even if the main dispensing module 1 receives the highest-level pressurization command, the adhesive flow rate extruded from the nozzle will still be lower than normal due to the extremely high viscous internal friction resistance of the fluid, failing to meet the requirements. Continuing to forcibly increase pressure could lead to pump overheating and burnout or hose rupture.

[0041] To resolve the above technical issues, please refer to Figures 1 to 3 As shown, this embodiment introduces a collaborative compensation mechanism based on equipment operating load.

[0042] The system also includes an auxiliary compensation module 4, which is located at the end of the extrusion nozzle of the main coating module 1. The auxiliary compensation module 4 is equipped with an ultrasonic transducer, which is used to receive vibration frequency commands and convert them into physical ultrasonic excitation. The ultrasonic excitation directly acts on the colloid flowing through the extrusion nozzle.

[0043] The system also includes a collaborative intervention unit, which monitors the operating power of the main coating module 1 in real time. When the extrusion pressure increases to the maximum set value and the density is still lower than the preset lower limit, the main coating module 1 is kept running at the maximum set value. At the same time, the collaborative intervention unit activates the auxiliary compensation module 4 to output ultrasonic excitation, using high-frequency vibration to destroy the bubble structure in the colloid and instantly reduce the viscosity of the colloid. The collaborative intervention unit is also used to dynamically adjust the vibration intensity of the auxiliary compensation module 4 according to the density recovery in subsequent monitoring cycles.

[0044] The ultrasonic vibration output of auxiliary compensation module 4 is perpendicular to the extrusion direction of the glue, which reduces the flow resistance of the glue on the wall of the extrusion nozzle through mechanical shearing force; the microfluidic effect generated by ultrasonic vibration drives the micro bubbles in the glue to migrate to the glue line surface and escape.

[0045] The collaborative intervention unit has an exit method for the auxiliary compensation module 4, which is as follows: when the density rises back to the target range, the extrusion pressure parameter of the main coating module 1 is gradually reduced until it returns to the normal operating range; after the extrusion pressure drops to the normal operating range, the vibration intensity of the auxiliary compensation module 4 is gradually reduced and the auxiliary compensation module 4 is finally turned off.

[0046] The collaborative intervention unit includes a gain allocation subunit, which dynamically allocates control weights between adjusting the extrusion pressure increment of the main coating module 1 and adjusting the vibration power increment of the auxiliary compensation module 4 based on the deviation of the real-time density parameter.

[0047] Specifically, under normal operating conditions, the collaborative intervention unit monitors the operating power of the main coating module 1 in real time in the background. When a rheological crisis caused by low temperature occurs, the system continuously executes stepwise pressure increase commands according to the logic of Example 2 until the extrusion pressure has increased to the system's maximum set value. However, at this time, the internal detection module 2 reports that the viscosity is still below the preset lower limit. This means that simply increasing the system's macroscopic pressure is no longer sufficient to overcome the high viscosity resistance of the fluid, and further pressurization may even trigger hardware protection. At this time, the collaborative intervention unit activates the multi-module collaborative control strategy and issues a hardware protection command: maintain the main coating module 1 operating at the maximum set value to ensure that the system's hardware is within a safe operating range and stop continuously increasing the pressure command value.

[0048] Subsequently, the collaborative intervention unit sends a high-frequency PWM trigger command to the auxiliary compensation module 4 located at the end of the extrusion nozzle. The ultrasonic transducer built into the auxiliary compensation module 4 utilizes the piezoelectric effect to efficiently convert electrical energy into high-frequency ultrasonic excitation energy waves. This high-frequency mechanical vibration wave is transmitted through the metal tube wall and acts on the colloidal core flow channel flowing through the extrusion nozzle.

[0049] The physical reason for the increased viscosity of the polymer adhesive under this condition lies in the severe physical entanglement and intermolecular hydrogen bonding between the long-chain polymers. When the ultrasonically excited wavefront undergoes tens of thousands of stretching and compressive phase transitions per second within the adhesive, its vibration direction is perpendicular to the extrusion direction of the adhesive. This extremely high-frequency transverse standing wave oscillation generates a powerful mechanical shear force at the interface between the extremely narrow metal inner wall of the nozzle and the boundary layer adhesive. This shear force instantaneously reduces the interaction strength between polymer chain segments, altering the original polymer hydrodynamic structure. The adhesive exhibits significant shear-thinning non-Newtonian fluid characteristics, and its apparent dynamic viscosity decreases sharply in a short period of time, greatly reducing the interfacial flow frictional resistance of the adhesive on the extrusion nozzle wall.

[0050] Furthermore, the microfluidic cavitation effect enables active degassing. For the microbubbles contained in viscous colloids, the alternating positive and negative pressure zones formed by the high-speed propagation of ultrasound in the fluid cause these bubbles to undergo high-frequency volume oscillations and even instantaneous expansion and contraction under the influence of intense acoustic pressure differences. Driven by the physical force of acoustic radiation, these originally scattered and isolated microbubbles collide with each other and merge into larger bubbles under the influence of the acoustic field, and then accelerate their migration towards the surface of the adhesive line under the influence of the standing wave field gradient. At the instant when the adhesive is squeezed out and comes into contact with the surface of the packaging box and instantly loses the constraint of the pipe wall, the apparent viscosity of the colloid has already been greatly reduced by the ultrasound, and the surface tension is insufficient to maintain the bubble shape, causing the bubble to escape and burst.

[0051] After the auxiliary vibration is initiated, the control module 3 extracts the latest density data transmitted back by the internal detection module 2 and dynamically adjusts the vibration intensity of the auxiliary compensation module 4 based on the density recovery during subsequent monitoring periods. When the ambient temperature remains low, the density recovery rate is low, and the gain allocation subunit in the system will actively increase the control weight allocated to the auxiliary compensation module 4, widen the duty cycle of the excitation command, increase the vibration amplitude, and further enhance the degree of shear thinning effect. Conversely, when the density approaches the target value, the output of acoustic energy is actively converged to prevent excessive local temperature rise of the fluid caused by prolonged high-energy ultrasound.

[0052] When the status determination unit confirms that the density has safely returned to the target range, the system enters the exit mechanism. First, the control module 3 gradually reduces the set pressure value of the main coating module 1 until it completely returns to the normal operating range. During this pressure reduction phase, because the auxiliary compensation module 4 continues to output strong shear force to maintain the extremely low viscosity of the fluid, the significant decrease in the output pressure of the main coating module 1 will not cause the extruded glue line to suddenly become thinner or stop flowing; the fluid still maintains a stable flow state at the nozzle tip.

[0053] Once the physical pressure from extrusion has decreased to the normal operating range, control module 3 gradually reduces the vibration intensity of auxiliary compensation module 4. The microscopic shear rate within the adhesive decreases accordingly, the polymer chains reform physical entanglement, and the apparent viscosity of the adhesive begins to rise steadily. Ultimately, a physical rheological equilibrium suitable for stable adhesive application under normal conditions is re-established, ensuring a stable transition in the adhesive application process when the system exits the collaborative intervention mode. This avoids sudden contraction or interruption of the adhesive flow caused by directly shutting down the ultrasound.

[0054] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. An intelligent detection system for automatic glue application on packaging boxes, characterized in that, include: Main coating module: Used to execute the first main control command to drive fluid extrusion for dispensing adhesive; Internal detection module: used to collect the internal acoustic echo of the glue line at the current glue application position, and calculate the real-time density parameter reflecting the internal density of the glue line based on the internal acoustic echo; Status determination unit: used to determine the deviation status based on the real-time density parameter within a preset monitoring period; Control module: used to perform control based on the result of the state determination unit: when the density is within the target range, maintain the current first master control command; when the density deviates from the target range, perform deviation compensation operation and adjust the pressure parameter of the first master control command to guide the density inside the adhesive line to recover to the target range.

2. The intelligent detection system for automatic gluing of packaging boxes according to claim 1, characterized in that, The internal detection module is located behind the main adhesive coating module, and its detection center points to the center of the adhesive line that has just been extruded from the main adhesive coating module.

3. The intelligent detection system for automatic gluing of packaging boxes according to claim 1, characterized in that, The acquisition frequency of the internal detection module is adjusted synchronously with the coating speed of the main coating module to ensure that multiple sets of internal acoustic echoes are acquired at the same coating point within the preset monitoring period.

4. The intelligent detection system for automatic gluing of packaging boxes according to claim 1, characterized in that, It also includes an auxiliary compensation module, which is located at the end of the extrusion nozzle of the main coating module; the auxiliary compensation module is equipped with an ultrasonic transducer for receiving vibration frequency commands and converting them into physical ultrasonic excitation, which directly acts on the colloid flowing through the extrusion nozzle.

5. The intelligent detection system for automatic gluing of packaging boxes according to claim 1, characterized in that, The deviation compensation operation is specifically as follows: When the real-time density parameter is continuously lower than the preset lower limit within the preset monitoring period, it is determined that there is a bubble defect inside the adhesive line, and the extrusion pressure parameter is increased. When the real-time density parameter exceeds the preset upper limit and its rate of change is not less than zero, it is determined that there is a risk of glue overflow, and the extrusion pressure parameter is reduced. When the real-time density parameter exceeds the preset upper limit and its rate of change is less than zero, it is determined that the glue line state is recovering on its own, and the current extrusion pressure parameter is maintained.

6. The intelligent detection system for automatic gluing of packaging boxes according to claim 5, characterized in that, When the control module increases the extrusion pressure parameter: Based on the deviation of the real-time density parameter from the preset lower limit, the corresponding pressure compensation step value is matched in segments; The deviation amplitude is divided into at least three consecutive pressure steps, and the pressure compensation step value increases stepwise as the real-time compaction parameter decreases, so as to achieve nonlinear pressure compensation for defects of different severity.

7. The intelligent detection system for automatic gluing of packaging boxes according to claim 4, characterized in that, It also includes a collaborative intervention unit, which monitors the operating power of the main coating module in real time. When the extrusion pressure increases to the maximum set value and the density is still lower than the preset lower limit, the main coating module is kept running at the maximum set value. At the same time, the collaborative intervention unit activates the auxiliary compensation module to output ultrasonic excitation, using high-frequency vibration to destroy the bubble structure in the colloid and instantly reduce the viscosity of the colloid. The collaborative intervention unit is also used to dynamically adjust the vibration intensity of the auxiliary compensation module according to the density recovery in subsequent monitoring periods.

8. The intelligent detection system for automatic gluing of packaging boxes according to claim 4, characterized in that, The ultrasonic vibration output by the auxiliary compensation module is perpendicular to the extrusion direction of the adhesive, which reduces the flow resistance of the adhesive on the wall of the extrusion nozzle through mechanical shearing force; the microfluidic effect generated by the ultrasonic vibration drives the microbubbles in the adhesive to migrate to the surface of the adhesive line and escape.

9. The intelligent detection system for automatic gluing of packaging boxes according to claim 7, characterized in that, The collaborative intervention unit includes an exit method for the auxiliary compensation module, specifically: When the density returns to the target range, the extrusion pressure parameter of the main coating module is gradually reduced until it returns to the normal operating range. After the extrusion pressure drops to the normal operating range, the vibration intensity of the auxiliary compensation module is gradually reduced and the auxiliary compensation module is eventually turned off.

10. The intelligent detection system for automatic gluing of packaging boxes according to claim 7, characterized in that, The collaborative intervention unit includes a gain allocation subunit, which dynamically allocates control weights between adjusting the extrusion pressure increment of the main coating module and adjusting the vibration power increment of the auxiliary compensation module based on the deviation of the real-time density parameter.

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