Industrial internet of things based screen printing workshop microenvironment intelligent control system and method

Abstract

This invention discloses an intelligent control system and method for the microenvironment of a screen printing workshop based on the Industrial Internet of Things (IIoT), relating to the field of IIoT environmental control technology. It includes a processing data acquisition module, a release-removal cross-validation module, and a dynamic control module. The processing data acquisition module associates injection molding, gluing, assembly, and screen printing data for the same component, and obtains background release from the empty platform, component-carried release, total screen printing release, and volatile organic compound (VOC) removal responses according to the screen printing actions. The release-removal cross-validation module strips the carried-over response based on the actual attenuation trend of the component, forming a new screen printing release response, and distinguishes between cross-process carried-over release, screen printing process release, exhaust-induced release, and mixed release. The dynamic control module adjusts the pre-collection time, exhaust volume during the screen printing action stage, and branch air volume distribution accordingly, and cancels the corresponding adjustments when the regional concentration decreases while the release response increases, avoiding misjudging a decrease in concentration as a reduction in pollution sources.

Description

Technical Field

[0001] This invention relates to the field of industrial Internet of Things (IoT) environmental control technology, specifically to an intelligent control system and method for the microenvironment of a screen printing workshop based on the Industrial Internet of Things. Background Technology

[0002] Washing machine parts typically undergo injection molding, adhesive application, assembly, and screen printing. Injection-molded parts may retain residual heat, and the adhesive applied after molding may still be in a state of continuous curing and volatilization when entering the screen printing station. This causes the parts to release volatile organic compounds (VOCs) into the surrounding environment even before contacting the screen printing ink. Once in the screen printing process, this cross-process release, combined with the release from ink thinner, cleaning agents, and residues on the screen surface, results in the VOC concentration detected in the screen printing workshop not necessarily corresponding solely to the current screen printing process.

[0003] Current microenvironmental control in screen printing workshops typically relies on the Industrial Internet of Things (IIoT) to collect data on ambient volatile organic compound (VOC) concentrations, temperature, humidity, and equipment operating status, increasing exhaust ventilation when concentrations rise. However, regional concentrations are influenced not only by the rate of pollutant release but also by exhaust air carryover, makeup air dilution, and changes in temporary contamination within the area. While increasing exhaust ventilation near the screen can accelerate VOC carryover, it may also enhance airflow shear and solvent evaporation on the ink surface, causing a simultaneous increase in the pollutant release rate. Therefore, a decrease in detected concentration could indicate effective pollutant removal or simply a temporary excess of exhaust dilution rates over the rate of new release, and cannot directly prove that control actions have reduced pollutant generation.

[0004] Furthermore, existing control methods typically fail to utilize the process interval between component positioning and screen printing, before the screen is pressed down, to separately obtain the release status of the same component brought into the screen printing station. They also fail to decompose the total release after screen printing into cross-process carry-over release and new release from screen printing. Consequently, when concentrations are abnormal, the system struggles to determine whether to extend component pre-collection upon entry, adjust the exhaust intensity during screen printing, or change the airflow distribution between different exhaust branches. This easily leads to a single control method that continuously increases the total exhaust volume, resulting in increased energy consumption, accelerated ink evaporation, and masking of abnormal sources. Therefore, a microenvironment control system and method are needed that can proactively generate release data from different sources during screen printing intervals and cross-validate contaminant release and exhaust removal. Summary of the Invention

[0005] The purpose of this invention is to provide an intelligent control system and method for the microenvironment of a screen printing workshop based on the Industrial Internet of Things, so as to solve the problems mentioned in the background art.

[0006] To address the aforementioned technical problems, this invention provides the following technical solution: an intelligent control system and method for the microenvironment of a screen printing workshop based on the Industrial Internet of Things, comprising a processing data acquisition module, a release and removal cross-validation module, and a dynamic control module, characterized in that: The processing data acquisition module is used to associate the injection molding, gluing, assembly and screen printing data of the same part to be screen printed. The data acquisition window is divided according to the screen printing action time to obtain the empty stage background release response, the part carrying release response, the total screen printing release response and the volatile organic compound removal response respectively. The release and removal cross-validation module is used to obtain the carry-over continuity response of the component during screen printing based on the component carry-over release response, separate the empty stage background release response and the carry-over continuity response from the total screen printing release response to form the new screen printing release response, and cross-validate the component carry-over release response, the new screen printing release response and the volatile organic compound removal response to distinguish cross-process carry-over release, screen printing process release, exhaust-induced release and mixed release. The dynamic control module is used to adjust the pre-collection time of the component entering the station, the exhaust volume of the screen at different action stages, and the air volume distribution between different exhaust branches according to the differentiation results. When the concentration of volatile organic compounds in the area decreases while the component carries the release response or the screen printing adds a new release response, the corresponding control parameter adjustment is canceled. The processing data acquisition module is communicatively connected to the release and removal cross-validation module, and the release and removal cross-validation module is communicatively connected to the dynamic control module.

[0007] According to the above technical solution, the processing data acquisition module includes a component history association unit, an action timing acquisition unit, a phased release acquisition unit, and an exhaust removal acquisition unit; The component history association unit is used to associate the injection molding completion time, demolding temperature, glue application completion time, adhesive type, glue application amount, assembly completion time, screen printing entry time, and waiting time between each adjacent process according to the component identification. The action timing acquisition unit is used to acquire action signals for component entry, positioning completion, screen pressing down, squeegee start, squeegee end, screen lifting up, and component departure. The phased release acquisition unit is used to obtain the empty stage background release response when there are no parts at the screen printing station and the screen is not moving, to obtain the part carrying release response when the part is positioned and the screen has not been pressed down, and to obtain the total screen printing release response from the time the screen is pressed down until the part leaves the station. The exhaust removal acquisition unit is used to simultaneously acquire the exhaust flow rate, the concentration of volatile organic compounds in the exhaust gas, and the concentration of volatile organic compounds in the replenished air of each exhaust branch.

[0008] According to the above technical solution, the release and removal cross-validation module includes a source continuation unit, a new source stripping unit, a removal response forming unit, and a source discrimination unit; The carry source continuation unit is used to select a continuous attenuation data segment from the component carry release response, determine the carry release attenuation parameter of the target component, and obtain the carry continuation response of the target component during screen printing. The newly added source stripping unit is used to subtract the empty stage background release response and the carry-over continuation response from the total release response of the screen printing to form the newly added release response of the screen printing. The removal response forming unit is used to form a volatile organic compound removal response based on the exhaust flow rate of each exhaust branch and the volatile organic compound concentration difference between the exhaust gas and the replenished air. The source determination unit is used to compare the component-carried release response, the screen-printed new release response, and the volatile organic compound removal response with the corresponding reference envelope, and to determine the release source by combining the screen-printing action time and the exhaust parameter change time.

[0009] According to the above technical solution, the dynamic control module includes an in-station pre-capture control unit, a screen phase exhaust control unit, and an exhaust branch distribution unit; The in-station pre-capture control unit is used to extend the pre-capture time between the completion of component positioning and the pressing of the screen when the component's carry-release response exceeds the carry-release threshold, and to increase the exhaust volume of the exhaust branch adjacent to the component. The screen phase exhaust control unit is used to maintain the exhaust branch adjacent to the screen at a limited exhaust volume during screen pressing and squeegee printing, increase the exhaust volume of the exhaust branch adjacent to the screen after the screen is lifted, and determine the upper limit of the exhaust volume of the exhaust branch adjacent to the screen based on whether the screen printing release response increases abnormally with the increase of exhaust volume. The exhaust branch distribution unit is used to distribute the reduced air volume from the exhaust branch adjacent to the screen to the exhaust branch adjacent to the component or the background exhaust branch, under the constraint of total exhaust capacity.

[0010] According to the above technical solution, the dynamic control module further includes a control command recording unit, a response interval corresponding unit, and a parameter cancellation unit; The control command recording unit is used to record the object of the control parameter change, the direction of the change, the time of the change, the parameter before the change, the parameter after the change, and the corresponding component identifier. The corresponding unit of the response interval is used to map the time of change of control parameters to the effective response interval of release response and removal response based on the delivery delay of exhaust duct, gas mixing delay and volatile organic compound sensor response delay. The parameter cancellation unit is used to determine the current control result as an apparent improvement when a decrease in the concentration of volatile organic compounds in the region is detected within the effective response range, and the release response carried by the component or the new release response added by the screen printing increases relative to the corresponding reference envelope. It then restores the exhaust state before the parameter change and prohibits the continued execution of the same direction of the screen printing adjacent exhaust increment during the current component processing.

[0011] A method for intelligent control of the microenvironment in a screen printing workshop based on the Industrial Internet of Things includes the following steps: Step S1: Based on the component identification, associate the injection molding, gluing, assembly, and screen printing data of the same component to be screen printed, and obtain the action times of component entering the station, positioning completion, screen pressing down, squeegee start, squeegee end, screen lifting up, and component leaving the station; in the empty station state, the component positioning completion and screen not yet pressed down state, and the screen pressed down to the component leaving the station state, respectively generate the empty station background release response, component carrying release response, and screen printing total release response, and simultaneously collect the exhaust flow rate and volatile organic compound concentration of each exhaust branch; Step S2: Select a continuous attenuation data segment from the component carry-out release response, determine the carry-out release attenuation parameter of the target component, and obtain the carry-out continuation response of the target component during screen printing; subtract the empty stage background release response and the carry-out continuation response from the total screen printing release response to obtain the newly added screen printing release response, and form a volatile organic compound removal response based on the mass of volatile organic compounds discharged from each exhaust branch. Step S3: Cross-validate the component carry-over release response, screen printing new release response, and volatile organic compound removal response with the regional volatile organic compound concentration, screen printing action time, and exhaust parameter change time to distinguish cross-process carry-over release, screen printing process release, exhaust-induced release, and mixed release. Step S4: In response to the differentiation results, adjust the pre-capture time of the component entering the station, the exhaust volume of the screen at different action stages, and the air volume distribution between the exhaust branch near the component, the exhaust branch near the screen, and the background exhaust branch. Step S5: Align the control parameter change time with the effective response range of the release response and removal response; when the concentration of volatile organic compounds in the effective response range decreases, while the release response carried by the component or the release response newly added by the screen printing increases, the control result is judged as an apparent improvement, and the corresponding control parameter adjustment is cancelled.

[0012] According to the above technical solution, in steps S1 and S2, the acquisition status is... The volatile organic compound release response is as follows: ...(1) In the formula, Data collection status The volatile organic compound release response under the condition of the sampling state This includes the empty stage status, component carrying release acquisition status, and total silkscreen release acquisition status; For the effective mixing volume of the screen printing station; This refers to the regional concentration of volatile organic compounds. Data collection status The collection of exhaust branch lines that are in the open state; and The first The exhaust flow rate of each exhaust branch and the concentration of volatile organic compounds in the exhaust gas after time delay correction; To replenish the concentration of volatile organic compounds in the air; The stable release response obtained in the empty state will be denoted as The data will be obtained and deducted during the period between when the component positioning is completed and before the screen printing plate is pressed down. The subsequent release response is denoted as ;exist Selecting time points from data segments that continuously decrease and are above the detection limit and The carry-on release attenuation parameter is determined according to the following formula: ...(2) The carryover response during screen printing is obtained using the following formula: ... (3) The total release response of the screen printing during the period from screen pressing down to component departure is denoted as . The newly added release response of the silkscreen is obtained according to the following formula: ... (4) when When the fitting residual of the continuously decaying data segment is not greater than zero, exceeds the allowable value, or the calculation result of equation (4) is continuously lower than the lower limit of the measurement error, stop using the current component to carry the release response for extrapolation, extend the acquisition time before the screen is pressed down, and mark the current processing cycle as the release source inseparable cycle.

[0013] According to the above technical solution, the volatile organic compound removal response in step S2 is as follows: ...(5) In the formula, For the removal of volatile organic compounds, This refers to the number of exhaust branch lines; Step S3 further includes: when the component-carried release response exceeds the corresponding reference envelope, and the abnormal start time is earlier than the screen pressing time, it is determined that there is a cross-process carried release; when the screen printing new release response rises after the screen is pressed or scraped, decays after the screen is lifted, and its change is within the corresponding reference envelope, it is determined that there is a screen printing process release; when the volatile organic compound removal response rises after the exhaust volume near the screen increases, and the screen printing new release response exceeds the corresponding reference envelope, and decreases after the exhaust volume near the screen recovers, it is determined that there is an exhaust-induced release; when cross-process carried release and screen printing process release or exhaust-induced release are both established, it is determined that there is a mixed release.

[0014] According to the above technical solution, in step S4, when the carry-on release attenuation parameter is valid, the component's pre-collection time upon entering the station is determined according to the following formula: ... (6) In the formula, The pre-capture time from when the component is positioned until the screen is allowed to be pressed down. For the maximum pre-collection time, The carry-out threshold is set to allow the start of screen printing; When cross-process carryover is determined, increase the exhaust volume of the exhaust branch adjacent to the component and follow the instructions. Delay screen pressing; when screen printing process release is detected, maintain the exhaust volume of the adjacent exhaust branch of the screen at a limited volume during screen pressing and squeegee printing, and increase the exhaust volume of the adjacent exhaust branch of the screen after the screen is lifted; when exhaust-induced release is detected, reduce the exhaust volume of the adjacent exhaust branch of the screen, allocate the reduced volume to the background exhaust branch, and extend the capture time after the screen is lifted; when mixed release is detected, first control cross-process carry-over release before screen pressing, and then control the screen phase exhaust according to the new release response of screen printing.

[0015] According to the above technical solution, step S5 further includes: Record the component identification, exhaust branch, parameters before adjustment, parameters after adjustment, and adjustment time corresponding to each control parameter adjustment, and determine the effective response range based on the exhaust duct delivery delay, gas mixing delay, and volatile organic compound sensor response delay; The regional volatile organic compound concentration, component-carried release response, screen printing new release response, and volatile organic compound removal response within the effective response range were compared with the corresponding data before parameter adjustment. When the concentration of volatile organic compounds in the area decreases, and at least one of the peak value, cumulative amount, or duration of the release response carried by the component or the newly added release response of the screen printing exceeds the corresponding reference envelope, it is judged as an apparent improvement. The exhaust state before the parameter adjustment is restored, and the exhaust adjustment of the adjacent screen printing in the same direction is prohibited during the current component processing. When the exhaust control command increases but the volatile organic compound removal response does not produce a corresponding increase, information such as insufficient air volume, pipe blockage, or capture position deviation is output for the corresponding exhaust branch.

[0016] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: This invention utilizes the action interval of the screen printing equipment to obtain the background release response of the empty stage, the carry-over release response of the same component before the screen is pressed down, and the total release response after the screen printing action. Based on the actual attenuation trend of the component, its carry-over continuation response during screen printing is separated, preventing cross-process carry-over releases from upstream injection molding, gluing, and assembly processes from being incorrectly attributed to the screen printing process. By cross-validating the component carry-over release, newly added screen printing release, and the actual removal response of each exhaust branch, it is possible to identify the apparent improvement where the concentration of volatile organic compounds in the area decreases but the release source strength increases, avoiding further ink volatilization induced by continuously increasing the exhaust volume directly acting on the screen. Therefore, the pre-collection of components entering the station, the exhaust phase of the screen action, and the branch air volume distribution can be adjusted according to the release source, maintaining the pollutant collection boundary while reducing the reverse disturbance of the release process by control actions; and the response deviation during normal processing can be used to further locate upstream component anomalies, exhaust branch blockages, or collection position deviations, linking pollution source differentiation, microenvironment control, and exhaust status checks. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the system module composition of the present invention; Figure 2 This is a schematic diagram of the control method of the present invention. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. The screen printing workshop is used for screen printing on washing machine parts that have undergone injection molding, gluing, and assembly. These washing machine parts include control panels, decorative panels, or plastic shells. The screen printing station is equipped with a part conveying mechanism, a positioning mechanism, a screen, a squeegee, and a micro-environment ventilation mechanism. The micro-environment ventilation mechanism includes exhaust branches near the parts, exhaust branches near the screen, and background exhaust branches.

[0019] Please see Figure 1 This invention provides an intelligent control system for the microenvironment of a screen printing workshop based on the Industrial Internet of Things, including a processing data acquisition module, a release and removal cross-validation module, and a dynamic control module.

[0020] The processing data acquisition module is used to associate the injection molding, gluing, assembly and screen printing data of the same part to be screen printed. The data acquisition window is divided according to the screen printing action time to obtain the empty stage background release response, part carrying release response, total screen printing release response and volatile organic compound removal response respectively.

[0021] The release and removal cross-validation module is used to obtain the carry-over continuation response during screen printing based on the component carry-over release response. It separates the empty stage background release response and the carry-over continuation response from the total screen printing release response to form the new screen printing release response. The component carry-over release response, the new screen printing release response, and the volatile organic compound removal response are cross-validated to distinguish between cross-process carry-over release, screen printing process release, exhaust-induced release, and mixed release.

[0022] The dynamic control module is used to adjust the pre-collection time of the component entering the station, the exhaust volume of the screen at different action stages, and the air volume distribution between different exhaust branches according to the differentiation results. When the concentration of volatile organic compounds in the area decreases while the component carries the release response or the screen print adds a new release response, the corresponding control parameter adjustment is canceled.

[0023] The processing data acquisition module is communicatively connected to the release and removal cross-validation module, which in turn is communicatively connected to the dynamic control module. The dynamic control module is connected to the component conveying mechanism, the screen lifting mechanism, and the airflow actuators of each exhaust branch to perform pre-capture, screen motion control, and exhaust branch adjustment.

[0024] The processing data acquisition module includes a component history association unit, an action timing acquisition unit, a phased release acquisition unit, and an exhaust removal acquisition unit.

[0025] The component history association unit is used to associate injection molding completion time, demolding temperature, adhesive application completion time, adhesive type, adhesive application amount, assembly completion time, screen printing arrival time, and waiting time between adjacent processes based on the component identifier. The component identifier can be a QR code, RFID tag, pallet number, or workpiece serial number in the production execution system. The upstream history data is used to trace the impact of residual injection heat, residual adhesive curing, and process waiting time on the release status when component release anomalies occur, but the release source is still mainly determined by the actual component release response obtained from the screen printing station.

[0026] The motion timing acquisition unit is used to acquire motion signals for component entry, positioning completion, screen pressing, squeegee start, squeegee end, screen lifting, and component departure. Motion signals can be read directly from the equipment controller or obtained through photoelectric position switches, positioning cylinder position switches, screen lifting position sensors, and squeegee motor encoders. All motion signals are written to the timeline according to the same industrial IoT clock to define the effective acquisition window for different release responses.

[0027] The phased release acquisition unit is used to acquire the empty stage background release response when there are no parts at the screen printing station and the screen is not moving; to acquire the part-carrying release response when the part is positioned and the screen has not yet been pressed down; and to acquire the total screen printing release response from the time the screen is pressed down until the part leaves the station. This transforms the positioning interval, which was originally only used to wait for the screen to move, into an independent observation window for the part-carrying source, allowing the release formed before the current part contacts the screen printing ink to be separated from the new release after the screen printing action.

[0028] The exhaust removal acquisition unit is used to simultaneously acquire the exhaust flow rate, volatile organic compound (VOC) concentration in the exhaust gas, and VOC concentration in the make-up air for each exhaust branch. A regional VOC detector is installed in the effective mixing area of ​​the screen printing station. Each exhaust branch is equipped with an airflow detector and an exhaust gas VOC detector, and a make-up air VOC detector is installed at the make-up air inlet.

[0029] The release and removal cross-validation module includes a source continuation unit, a new source stripping unit, a response formation unit, and a source discrimination unit.

[0030] The carry-over source continuation unit is used to select continuously decaying data segments from the component carry-over release response, determine the carry-over release decay parameters of the target component, and obtain the carry-over continuation response of the target component during screen printing. The new source stripping unit is used to subtract the empty stage background release response and the carry-over continuation response from the total screen printing release response to form the new screen printing release response. The removal response forming unit is used to form a volatile organic compound (VOC) removal response based on the exhaust flow rate of each exhaust branch and the concentration difference of VOCs between the exhaust gas and the make-up air.

[0031] The source determination unit compares the component-carried release response, the screen-printed new release response, and the volatile organic compound removal response with the corresponding reference envelope, and determines the release source by combining the screen-printing action time and the time of change in exhaust parameters. The reference envelope is established separately according to component type, upstream processing combination, ink type, screen type, and normal exhaust state, and includes at least the allowable peak value, cumulative amount, start time, and duration range of the corresponding release response in each action stage.

[0032] The dynamic control module includes an inlet pre-capture control unit, a screen phase exhaust control unit, and an exhaust branch distribution unit.

[0033] The inbound pre-capture control unit extends the pre-capture time between component positioning completion and screen pressing when the component's carry-and-release response exceeds the carry-and-release threshold, and increases the exhaust volume of the adjacent exhaust branch. The screen phase exhaust control unit maintains the adjacent exhaust branch at a limited exhaust volume during screen pressing and printing, increases the exhaust volume of the adjacent exhaust branch after the screen is lifted, and determines the upper limit of the exhaust volume of the adjacent exhaust branch based on whether the newly added release response abnormally increases with the increase in exhaust volume.

[0034] The exhaust branch distribution unit is used to distribute the reduced air volume from the exhaust branch adjacent to the screen to the exhaust branch adjacent to the component or the background exhaust branch, under the constraint of total exhaust capacity. The total exhaust capacity constraint means that the sum of the target air volume of each exhaust branch does not exceed the allowable exhaust volume that the total fan can provide under the current operating conditions.

[0035] The dynamic control module also includes a control command recording unit, a response interval corresponding unit, and a parameter cancellation unit.

[0036] The control command recording unit records the object of the control parameter change, the direction of the change, the time of the change, the parameters before the change, the parameters after the change, and the corresponding component identification. The response interval mapping unit maps the control parameter change time to the effective response interval of the release response and the removal response based on the exhaust duct delivery delay, the gas mixing delay, and the volatile organic compound sensor response delay.

[0037] The parameter cancellation unit is used to determine the current control result as an apparent improvement when a decrease in the concentration of volatile organic compounds in the region is detected within the effective response range, and the component carries a release response or the screen print adds a release response relative to the corresponding reference envelope. It restores the exhaust state before the parameter change and prohibits the continued execution of the same direction of the screen print adjacent exhaust increment during the current component processing.

[0038] Please see Figure 2 The intelligent control method for the microenvironment of a screen printing workshop based on the Industrial Internet of Things includes the following steps: Step S1: Based on the component identification, associate the injection molding, gluing, assembly, and screen printing data of the same component to be screen printed, and obtain the action times of component entering the station, positioning completion, screen pressing down, squeegee start, squeegee end, screen lifting up, and component leaving the station; in the empty station state, the component positioning completion and screen not yet pressed down state, and the screen pressed down to the component leaving the station state, respectively generate the empty station background release response, component carrying release response, and screen printing total release response, and simultaneously collect the exhaust flow rate and volatile organic compound concentration of each exhaust branch; Step S2: Select a continuous attenuation data segment from the component carry-out release response, determine the carry-out release attenuation parameter of the target component, and obtain the carry-out continuation response of the target component during screen printing; subtract the empty stage background release response and carry-out continuation response from the total screen printing release response to obtain the newly added screen printing release response, and form a volatile organic compound removal response based on the mass of volatile organic compounds discharged from each exhaust branch. Step S3: Cross-validate the component carry-over release response, screen printing new release response, and volatile organic compound removal response with the regional volatile organic compound concentration, screen printing action time, and exhaust parameter change time to distinguish cross-process carry-over release, screen printing process release, exhaust-induced release, and mixed release. Step S4: In response to the differentiation results, adjust the pre-capture time of the component entering the station, the exhaust volume of the screen at different action stages, and the air volume distribution between the exhaust branch near the component, the exhaust branch near the screen, and the background exhaust branch. Step S5: Align the control parameter change time with the effective response range of the release response and removal response; when the concentration of volatile organic compounds in the effective response range decreases, while the release response carried by the component or the release response newly added by the screen printing increases, the control result is judged as an apparent improvement, and the corresponding control parameter adjustment is cancelled.

[0039] The method for forming the release response in steps S1 and S2 further includes: All volatile organic compound detectors, airflow detectors, and equipment action signals use the same industrial IoT clock. Due to differences in exhaust duct length and sensor response speed, before the system is put into operation, a short-term tracer gas is released at a designated location to obtain the response delays of the area detectors and each exhaust branch detector, and the detection data are corrected to the same time axis according to the corresponding delays.

[0040] Data collection status The volatile organic compound release response is as follows: ...(1) In the formula, Data collection status The response to the release of volatile organic compounds; For the effective mixing volume of the screen printing station; This refers to the regional concentration of volatile organic compounds; Data collection status The collection of exhaust branch lines that are in the open state; and The first The exhaust flow rate of each exhaust branch and the concentration of volatile organic compounds in the exhaust gas after time delay correction; To replenish the concentration of volatile organic compounds in the air.

[0041] The first term of equation (1) represents the change in the temporary amount of volatile organic compounds (VOCs) within the effective mixing volume of the screen printing station, and the second term represents the actual mass of VOCs carried out by each exhaust branch. Therefore, even if the regional concentration decreases after increasing the exhaust volume, it is still necessary to combine the changes in the discharged mass and the temporary amount to determine whether the release of pollutants increases synchronously.

[0042] The effective mixing volume The calibration is achieved using conventional tracer gas calibration methods in the art (e.g., concentration decay method or constant release method). Specifically, as a conventional calibration embodiment, an inert tracer gas (e.g., carbon dioxide or sulfur hexafluoride) with a known rate or mass can be released within the screen printing station. Release is stopped once the gas concentration in the microenvironment reaches a stable distribution. Subsequently, the decay curve of the tracer gas concentration over time is recorded using a regional gas concentration detector. Combined with the known and constant exhaust flow rates of each exhaust branch under the current conditions, the effective mixing volume of the screen printing station under the current physical boundaries is calculated based on a standard concentration decay model. The above-described tracer gas calibration and volume conversion process is common knowledge in the field of industrial ventilation and environmental testing. Those skilled in the art can directly implement it by referring to conventional technical manuals (such as "Industrial Ventilation") or relevant national standards, without requiring any creative effort. When the physical boundaries of the screen printing workshop, such as partial enclosures, make-up air locations, or exhaust hood locations, change, the system will prompt maintenance personnel to recalibrate the effective mixing volume according to the above-described conventional methods. The system parameters were then updated. To reduce the sensitivity of the concentration derivative to measurement noise, local linear fitting was performed on three to seven consecutive sampling points, and the fitting slope was used as the... .

[0043] When there are no parts at the screen printing station, the screen is not moving, and the exhaust is in a reference state, after the regional concentration change rate is lower than the stable threshold and remains below it for a preset duration, the stable release response for that period is recorded as... The stabilizing effects of screen printing residue, cleaning agent residue, and adjacent stations on the screen printing station are thus factored into the empty stage background release response.

[0044] After the component is positioned, the screen pressing is not controlled temporarily. The release response is obtained and deducted within the acquisition window before the screen pressing. The component carries the release response. .from Data on sudden changes in airflow mixing when the component first enters the station, as well as data close to the detection limit, are removed. From the remaining data, data segments showing a continuous decline are selected.

[0045] In satisfying In this case, the carry-on release decay parameter is: ...(2) This indicates the actual release decay rate of the target component under the current demolding temperature, adhesive curing state, and process waiting time, rather than a fixed historical average for components of the same model.

[0046] Based on the actual carry-out attenuation parameters of the target component, its carry-out is extended into the screen printing period: ...(3) In the formula, This refers to the continued response that the target component itself should generate at subsequent moments, even when the web version is inactive.

[0047] The total release response of the screen printing during the period from screen pressing down to component departure is denoted as . The newly added release response for the silkscreen is: ... (4) Equation (4) does not directly regard the concentration after printing as ink release. Instead, it first excludes the continued influence of the empty stage background and the source carried by the same target component during screen printing, so that the newly released response of the screen printing mainly corresponds to the influence of ink, diluent, screen residue and exhaust on its volatilization process.

[0048] when When the value is not greater than zero, it indicates that the component carrying the release is still rising before the screen is pressed down. When the fitting residual of the continuously decaying data segment exceeds the allowable value, it indicates that the data segment may be affected by an external release source or a sudden change in airflow. In the above situations, the newly added release response of the screen printing is not forcibly calculated, but the acquisition time before the screen is pressed down is extended. If a valid continuously decaying data segment cannot be obtained after the maximum allowable waiting time is reached, the current processing cycle is marked as a cycle in which the release source cannot be separated, and the processing is completed using safe exhaust parameters or the component is transferred to a temporary storage station.

[0049] The method for forming the volatile organic compound removal response in step S2 further includes: ... (5) In the formula, For the volatile organic compound removal response, The number of exhaust branches. Equation (5) takes into account both exhaust flow rate and exhaust gas concentration, so the actual removal response cannot be replaced by the fan frequency, valve opening degree or regional concentration decrease alone.

[0050] The method for differentiating the release source in step S3 further includes: When a component's carry-over release response exceeds the corresponding reference envelope, and the anomaly's onset time is earlier than the screen printing plate's downward press, a cross-process carry-over release is determined. Since the anomaly occurred before the screen printing plate's movement, its source cannot be attributed to the current squeegee operation. The system further combines the waiting time from injection molding completion to screen printing entry, the waiting time from glue application completion to screen printing entry, demolding temperature, and glue application amount to generate upstream troubleshooting information.

[0051] When the newly released response of screen printing increases after the screen is pressed down or scraped, and decreases after the screen is lifted, and the peak value, cumulative amount and duration are within the corresponding reference envelope, it is determined to be a screen printing process release.

[0052] When the volatile organic compound (VOC) removal response increases after the exhaust volume near the screen printing plate increases, and the newly released VOC response exceeds the corresponding reference envelope, and then decreases after the exhaust volume near the screen printing plate recovers, exhaust-induced release is determined to exist. This determination indicates that the increased removal amount includes newly induced volatilization due to the increased airflow velocity on the screen printing plate surface, and the control cannot be considered effective solely based on a decrease in regional concentration.

[0053] When the component carries a release response that exceeds the corresponding reference envelope, and at the same time the silkscreened release response also exceeds the corresponding reference envelope, or when cross-process carry-over release and exhaust-induced release occur simultaneously, it is determined to be a mixed release.

[0054] The method for adjusting the pre-collection time and exhaust parameters in step S4 further includes: When the release attenuation parameter is valid, the component's pre-acquisition time upon arrival at the station is: ... (6) In the formula, The pre-capture time from the completion of component positioning to the allowable pressing of the screen; This is the maximum pre-capture duration; The carry-out threshold that allows screen printing to begin.

[0055] when Not higher than When the calculation result exceeds the specified time, the pre-collection time is not increased; when the calculation result exceeds the specified time, the pre-collection time is not increased. At that time, the pre-capture time will be limited to Simultaneously, it outputs abnormal status information of upstream processes. After performing pre-capture, it re-detects the actual component's carry-out response, and only allows the screen to be pressed down if the actual detection result is not higher than the carry-out release threshold.

[0056] When cross-process carryover is determined, increase the exhaust volume of the exhaust branch adjacent to the component, and follow the instructions. Delaying the screen pressing down allows the exhaust airflow to primarily act on the source carried by the component, rather than directly increasing the airflow velocity on the screen surface.

[0057] When the screen printing process is determined to be released, the exhaust branch near the screen is kept at a limited exhaust volume to prevent volatile organic compounds from escaping to the operating area during the screen pressing and squeegeeing process. After the screen is lifted, the exhaust volume of the exhaust branch near the screen is increased to centrally remove the volatile organic compounds that have been formed.

[0058] When exhaust-induced release is detected, the exhaust volume of the exhaust branch near the screen is reduced, the reduced volume is allocated to the background exhaust branch, and the collection time after the screen is raised is extended instead of continuing to increase the exhaust velocity near the screen.

[0059] When a mixed release is determined, the cross-process carry-over release is controlled before the screen is pressed down. After the component carry-over release response drops to the allowable range, the screen is pressed down. The screen phase exhaust is adjusted according to the newly added release response of the screen printing to avoid simultaneously increasing the exhaust volume near the component and the exhaust volume near the screen, which would destroy the source differentiation condition.

[0060] The control result verification and parameter cancellation method in step S5 further includes: The control command recording unit records the component identifier, exhaust branch, parameters before adjustment, parameters after adjustment, adjustment direction, and adjustment time for each parameter adjustment. The response interval corresponding unit adds the exhaust duct delivery delay, the area gas mixing delay, and the sensor response delay to determine the effective response interval corresponding to this parameter adjustment.

[0061] Within the effective response range, the regional volatile organic compound concentration, component-borne release response, screen printing new release response, and volatile organic compound removal response are compared with the corresponding data before parameter adjustment.

[0062] When the concentration of volatile organic compounds in the region decreases, the volatile organic compound removal response increases, and the release response carried by the component and the release response newly added by the screen printing do not exceed the corresponding reference envelope, the current control parameters are retained.

[0063] When the concentration of volatile organic compounds in the area decreases, and at least one of the peak value, cumulative amount, or duration of the release response carried by the component or the newly added release response from the screen printing exceeds the corresponding reference envelope, it is judged as an apparent improvement. The parameter cancellation unit restores the exhaust state before adjustment and prohibits the continued execution of exhaust adjustments for adjacent screen printing plates in the same direction during the current component processing.

[0064] When both the exhaust control command and the detected air volume increase, but the volatile organic compound removal response does not produce a corresponding increase, the result is not directly judged as an increase in the release source. Instead, information such as insufficient air volume in the corresponding exhaust branch, pipe blockage, or capture position deviation is output.

[0065] For example, after a component is positioned, the results are obtained. After 20 seconds, it was obtained According to equation (2), we get The rate is approximately 0.0347 seconds. When the allowable carry-on release threshold for starting screen printing is 2.0 mg / min, the pre-trapping time is approximately 20 seconds according to equation (6). After the pre-trapping is completed, the system still needs to confirm whether the component's carry-on release response is below the threshold based on the actual detection results.

[0066] If raising the screen increases the exhaust volume near the screen by 20%, the concentration of volatile organic compounds in the area decreases by 15%, but the cumulative amount of new release from the screen printing obtained according to formula (4) increases by 25% relative to the reference envelope, then it is judged as an apparent improvement. The system restores the original exhaust volume near the screen, allocates part of the air volume to the background exhaust branch, and extends the collection time after the screen is raised.

[0067] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0068] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0069] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0070] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A micro-environmental intelligent control system for a screen printing workshop based on the Industrial Internet of Things, comprising a processing data acquisition module, a release / removal cross-validation module, and a dynamic control module, characterized in that: The processing data acquisition module is used to associate the injection molding, gluing, assembly and screen printing data of the same part to be screen printed. The data acquisition window is divided according to the screen printing action time to obtain the empty stage background release response, the part carrying release response, the total screen printing release response and the volatile organic compound removal response respectively. The release and removal cross-validation module is used to obtain the carry-over continuity response of the component during screen printing based on the component carry-over release response, separate the empty stage background release response and the carry-over continuity response from the total screen printing release response to form the new screen printing release response, and cross-validate the component carry-over release response, the new screen printing release response and the volatile organic compound removal response to distinguish cross-process carry-over release, screen printing process release, exhaust-induced release and mixed release. The dynamic control module is used to adjust the pre-collection time of the component entering the station, the exhaust volume of the screen at different action stages, and the air volume distribution between different exhaust branches according to the differentiation results. When the concentration of volatile organic compounds in the area decreases while the component carries the release response or the screen printing adds a new release response, the corresponding control parameter adjustment is canceled. The processing data acquisition module is communicatively connected to the release and removal cross-validation module, and the release and removal cross-validation module is communicatively connected to the dynamic control module.

2. The intelligent control system for the microenvironment of a screen printing workshop based on the Industrial Internet of Things as described in claim 1, characterized in that: The processing data acquisition module includes a component history association unit, an action timing acquisition unit, a phased release acquisition unit, and an exhaust removal acquisition unit. The component history association unit is used to associate the injection molding completion time, demolding temperature, glue application completion time, adhesive type, glue application amount, assembly completion time, screen printing entry time, and waiting time between each adjacent process according to the component identification. The action timing acquisition unit is used to acquire action signals for component entry, positioning completion, screen pressing down, squeegee start, squeegee end, screen lifting up, and component departure. The phased release acquisition unit is used to obtain the empty stage background release response when there are no parts at the screen printing station and the screen is not moving, to obtain the part carrying release response when the part is positioned and the screen has not been pressed down, and to obtain the total screen printing release response from the time the screen is pressed down until the part leaves the station. The exhaust removal acquisition unit is used to simultaneously acquire the exhaust flow rate, the concentration of volatile organic compounds in the exhaust gas, and the concentration of volatile organic compounds in the replenished air of each exhaust branch.

3. The intelligent control system for the microenvironment of a screen printing workshop based on the Industrial Internet of Things as described in claim 1, characterized in that: The release and removal cross-validation module includes a source continuation unit, a new source stripping unit, a removal response forming unit, and a source discrimination unit. The carry source continuation unit is used to select a continuous attenuation data segment from the component carry release response, determine the carry release attenuation parameter of the target component, and obtain the carry continuation response of the target component during screen printing. The newly added source stripping unit is used to subtract the empty stage background release response and the carry-over continuation response from the total release response of the screen printing to form the newly added release response of the screen printing. The removal response forming unit is used to form a volatile organic compound removal response based on the exhaust flow rate of each exhaust branch and the volatile organic compound concentration difference between the exhaust gas and the replenished air. The source determination unit is used to compare the component-carried release response, the screen-printed new release response, and the volatile organic compound removal response with the corresponding reference envelope, and to determine the release source by combining the screen-printing action time and the exhaust parameter change time.

4. The intelligent control system for the microenvironment of a screen printing workshop based on the Industrial Internet of Things as described in claim 1, characterized in that: The dynamic control module includes an in-station pre-capture control unit, a screen phase exhaust control unit, and an exhaust branch distribution unit. The in-station pre-capture control unit is used to extend the pre-capture time between the completion of component positioning and the pressing of the screen when the component's carry-release response exceeds the carry-release threshold, and to increase the exhaust volume of the exhaust branch adjacent to the component. The screen phase exhaust control unit is used to maintain the exhaust branch adjacent to the screen at a limited exhaust volume during screen pressing and squeegee printing, increase the exhaust volume of the exhaust branch adjacent to the screen after the screen is lifted, and determine the upper limit of the exhaust volume of the exhaust branch adjacent to the screen based on whether the screen printing release response increases abnormally with the increase of exhaust volume. The exhaust branch distribution unit is used to distribute the reduced air volume from the exhaust branch adjacent to the screen to the exhaust branch adjacent to the component or the background exhaust branch, under the constraint of total exhaust capacity.

5. The intelligent control system for the microenvironment of a screen printing workshop based on the Industrial Internet of Things as described in claim 4, characterized in that: The dynamic control module also includes a control command recording unit, a response interval corresponding unit, and a parameter cancellation unit; The control command recording unit is used to record the object of the control parameter change, the direction of the change, the time of the change, the parameter before the change, the parameter after the change, and the corresponding component identifier. The corresponding unit of the response interval is used to map the time of change of control parameters to the effective response interval of release response and removal response based on the delivery delay of exhaust duct, gas mixing delay and volatile organic compound sensor response delay. The parameter cancellation unit is used to determine the current control result as an apparent improvement when a decrease in the concentration of volatile organic compounds in the region is detected within the effective response range, and the release response carried by the component or the new release response added by the screen printing increases relative to the corresponding reference envelope. It then restores the exhaust state before the parameter change and prohibits the continued execution of the same direction of the screen printing adjacent exhaust increment during the current component processing.

6. A method for intelligent control of the microenvironment in a screen printing workshop based on the Industrial Internet of Things, characterized in that, Includes the following steps: Step S1: Based on the component identification, associate the injection molding, gluing, assembly, and screen printing data of the same component to be screen printed, and obtain the action times of component entering the station, positioning completion, screen pressing down, squeegee start, squeegee end, screen lifting up, and component leaving the station; in the empty station state, the component positioning completion and screen not yet pressed down state, and the screen pressed down to the component leaving the station state, respectively generate the empty station background release response, component carrying release response, and screen printing total release response, and simultaneously collect the exhaust flow rate and volatile organic compound concentration of each exhaust branch; Step S2: Select a continuous attenuation data segment from the component carry-out release response, determine the carry-out release attenuation parameter of the target component, and obtain the carry-out continuation response of the target component during screen printing; subtract the empty stage background release response and the carry-out continuation response from the total screen printing release response to obtain the newly added screen printing release response, and form a volatile organic compound removal response based on the mass of volatile organic compounds discharged from each exhaust branch. Step S3: Cross-validate the component carry-over release response, screen printing new release response, and volatile organic compound removal response with the regional volatile organic compound concentration, screen printing action time, and exhaust parameter change time to distinguish cross-process carry-over release, screen printing process release, exhaust-induced release, and mixed release. Step S4: In response to the differentiation results, adjust the pre-capture time of the component entering the station, the exhaust volume of the screen at different action stages, and the air volume distribution between the exhaust branch near the component, the exhaust branch near the screen, and the background exhaust branch. Step S5: Align the control parameter change time with the effective response range of the release response and removal response; when the concentration of volatile organic compounds in the effective response range decreases, while the release response carried by the component or the release response newly added by the screen printing increases, the control result is judged as an apparent improvement, and the corresponding control parameter adjustment is cancelled.

7. The intelligent control method for the microenvironment of a screen printing workshop based on the Industrial Internet of Things as described in claim 6, characterized in that: In steps S1 and S2, the acquisition status is... The volatile organic compound release response is as follows: ……（1） In the formula, Data collection status The volatile organic compound release response under the condition of the collection state This includes the empty stage status, component carrying release acquisition status, and total silkscreen release acquisition status; For the effective mixing volume of the screen printing station; This refers to the regional concentration of volatile organic compounds; Data collection status The collection of exhaust branch lines that are in the open state; and The first The exhaust flow rate of each exhaust branch and the concentration of volatile organic compounds in the exhaust gas after time delay correction; To replenish the concentration of volatile organic compounds in the air; The stable release response obtained in the empty state will be denoted as The data will be obtained and deducted during the period between when the component positioning is completed and before the screen printing plate is pressed down. The subsequent release response is denoted as ;exist Selecting time points from data segments that continuously decrease and are above the detection limit and The carry-on release attenuation parameter is determined according to the following formula: ……（2） The carryover response during screen printing is obtained using the following formula: ……（3） The total release response of the screen printing during the period from screen pressing down to component departure is denoted as . The newly added release response of the silkscreen is obtained according to the following formula: ……（4） when When the fitting residual of the continuously decaying data segment is not greater than zero, exceeds the allowable value, or the calculation result of equation (4) is continuously lower than the lower limit of the measurement error, stop using the current component to carry the release response for extrapolation, extend the acquisition time before the screen is pressed down, and mark the current processing cycle as the release source inseparable cycle.

8. The intelligent control method for the microenvironment of a screen printing workshop based on the Industrial Internet of Things as described in claim 7, characterized in that: The volatile organic compound removal response in step S2 is as follows: ……（5） In the formula, For the volatile organic compound removal response, This refers to the number of exhaust branch lines; Step S3 further includes: when the component-carried release response exceeds the corresponding reference envelope, and the abnormal start time is earlier than the screen pressing time, it is determined that there is a cross-process carried release; when the screen printing new release response rises after the screen is pressed or scraped, decays after the screen is lifted, and its change is within the corresponding reference envelope, it is determined that there is a screen printing process release; when the volatile organic compound removal response rises after the exhaust volume near the screen increases, and the screen printing new release response exceeds the corresponding reference envelope, and decreases after the exhaust volume near the screen recovers, it is determined that there is an exhaust-induced release; when cross-process carried release and screen printing process release or exhaust-induced release are both established, it is determined that there is a mixed release.

9. The intelligent control method for the microenvironment of a screen printing workshop based on the Industrial Internet of Things as described in claim 8, characterized in that: In step S4, when the carry-on release attenuation parameter is valid, the component's pre-collection time upon arrival at the station is determined according to the following formula: ……（6） In the formula, The pre-capture time from when the component is positioned until the screen is allowed to be pressed down. For the maximum pre-capture time, The carry-out threshold is set to allow the start of screen printing; When cross-process carryover is determined, increase the exhaust volume of the exhaust branch adjacent to the component and follow the instructions. Delayed screen printing compression; When a screen printing process release is detected, the exhaust airflow of the adjacent exhaust airflow branch is kept at a limited exhaust volume during screen pressing and squeegee printing, and the exhaust airflow of the adjacent exhaust airflow branch is increased after the screen is lifted; when an exhaust-induced release is detected, the exhaust airflow of the adjacent exhaust airflow branch is reduced, the reduced airflow is allocated to the background exhaust airflow branch, and the capture time after the screen is lifted is extended. When a mixed release is determined, the cross-process carry-over release is first controlled before the screen is pressed down, and then the screen phase exhaust is controlled according to the newly added release response of the screen printing.

10. The intelligent control method for the microenvironment of a screen printing workshop based on the Industrial Internet of Things as described in claim 9, characterized in that: Step S5 further includes: Record the component identification, exhaust branch, parameters before adjustment, parameters after adjustment, and adjustment time corresponding to each control parameter adjustment, and determine the effective response range based on the exhaust duct delivery delay, gas mixing delay, and volatile organic compound sensor response delay; The regional volatile organic compound concentration, component-carried release response, screen printing new release response, and volatile organic compound removal response within the effective response range were compared with the corresponding data before parameter adjustment. When the concentration of volatile organic compounds in the area decreases, and at least one of the peak value, cumulative amount, or duration of the release response carried by the component or the newly added release response of the screen printing exceeds the corresponding reference envelope, it is judged as an apparent improvement. The exhaust state before the parameter adjustment is restored, and the exhaust adjustment of the adjacent screen printing in the same direction is prohibited during the current component processing. When the exhaust control command increases but the volatile organic compound removal response does not produce a corresponding increase, information such as insufficient air volume, pipe blockage, or capture position deviation is output for the corresponding exhaust branch.

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