A whole-process intelligent monitoring and parameter closed-loop system for a blow molding nine-angle plastic tray forming process

Abstract

This invention discloses an intelligent monitoring and parameter closed-loop system for the entire process of blow molding a nine-corner plastic tray, belonging to the field of blow molding control technology. By integrating a preform contour visual monitoring unit, a cavity positioning sensing unit, a central processing unit, an execution adjustment unit, and a closed-loop control unit, it realizes real-time monitoring, accurate calculation, and dynamic adjustment of the alignment deviation between the preform contour and the nine-corner cavity of the mold. Utilizing visual monitoring and sensing positioning technology, it can collect preform contour feature data and mold nine-corner cavity positioning and mold closing accuracy data in real time. The central processing unit constructs a preform contour-cavity alignment deviation correction model, quantifies the alignment deviation, and generates execution adjustment commands. The execution adjustment unit dynamically adjusts the extrusion guide, pre-blowing parameters, and mold closing alignment accuracy according to the commands. The closed-loop control unit realizes closed-loop control of parameter iterative correction to ensure that the preform and the nine-corner cavity achieve precise alignment.

Description

Technical Field

[0001] This invention relates to the field of blow molding control technology, specifically to an intelligent monitoring and parameter closed-loop system for the entire process of blow molding a nine-corner plastic pallet. Background Technology

[0002] Blow molding, as an important plastic processing technology, has been widely used in many fields. Among them, blow-molded nine-corner plastic pallets are formed by extrusion blow molding. With their unique structural advantages, such as strong load-bearing capacity and good stability, they play a key role in logistics transportation and warehousing. In the production process of blow-molded nine-corner plastic pallets, after the preform is extruded and pre-blown, the alignment accuracy of its contour shape and spatial position with the nine-corner cavity of the mold is crucial. This directly determines the integrity of the pallet corner molding and the accuracy of the seam line position, thus affecting the overall quality and performance of the product.

[0003] However, the existing production process of blow-molded nine-corner plastic pallets suffers from numerous problems that severely impact product quality and production efficiency. During extrusion and pre-blowing, the preform is prone to contour distortion, overall offset, and angular deflection due to various factors, leading to spatial alignment deviations between the preform and the nine-corner cavity. These deviations trigger a series of molding defects, such as insufficient corner material, resulting in weak corner strength and easy damage; misaligned seams, affecting the overall structural stability and appearance quality of the pallet; and uneven wall thickness, reducing the pallet's load-bearing capacity and service life. These problems result in low product qualification rates and increased production costs. Traditional production methods rely mainly on manual experience or open-loop preset parameters for adjustment, failing to collect real-time data on the preform contour and cavity positioning, and lacking quantitative deviation calculation models and dynamic correction mechanisms. This makes parameter adjustment lagging and inaccurate, making it difficult to achieve precise matching between the preform and cavity. It fails to address the molding quality issues of nine-corner plastic pallets at their source, severely restricting the automation and stability of blow-molded pallet production and making it difficult to meet the demands of modern industry for large-scale, high-quality production. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an intelligent monitoring and parameter closed-loop system for the entire process of blow molding a nine-corner plastic tray. This system integrates a preform contour visual monitoring unit, a cavity positioning sensing unit, a central processing unit, an execution adjustment unit, and a closed-loop control unit. It achieves real-time monitoring, precise calculation, and dynamic adjustment of the alignment deviation between the preform contour and the nine-corner cavity of the mold. Utilizing visual monitoring and sensing positioning technology, it can collect preform contour feature data and mold nine-corner cavity positioning and mold closing accuracy data in real time. The central processing unit constructs a preform contour-cavity alignment deviation correction model, quantifies the alignment deviation, and generates execution adjustment commands. The execution adjustment unit dynamically adjusts the extrusion guide, pre-blowing parameters, and mold closing alignment accuracy according to the commands. The closed-loop control unit achieves closed-loop control through iterative parameter correction, ensuring precise alignment between the preform and the nine-corner cavity.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a full-process intelligent monitoring and parameter closed-loop system for blow molding of a nine-corner plastic tray, the system comprising: a preform contour visual monitoring unit, a cavity positioning sensing unit, a central processing unit, an execution adjustment unit, and a closed-loop control unit; The blank contour visual monitoring unit adopts a non-contact three-dimensional visual acquisition structure. Acquisition components covering the overall contour and nine-corner feature area of ​​the blank are symmetrically arranged along the circumference of the blank. The pre-formed three-dimensional point cloud data of the blank is acquired according to the forming rhythm. After data processing, the contour feature parameters of the nine-corner area of ​​the blank are extracted and output. The cavity positioning sensing unit establishes a cavity spatial positioning reference coordinate system by using the mold closing reference point and the corner center positioning mark of the nine-corner cavity, and collects the spatial positioning data of the nine-corner cavity and the mold closing accuracy data. The central processing unit synchronously receives the blank contour feature parameters, cavity spatial positioning data and mold closing accuracy data and performs timing matching. Based on the cavity reference coordinate system, it quantitatively calculates the alignment deviation between the blank and the cavity, and generates and executes adjustment commands through the built-in blank contour-cavity alignment deviation correction model. The execution adjustment unit includes a preform extrusion guide adjustment component, a pre-blowing parameter adjustment component, and a mold closing alignment adjustment component. After receiving the adjustment command, it dynamically adjusts the preform extrusion guide, pre-blowing parameters, and mold closing alignment accuracy. The closed-loop control unit, together with the central processing unit and the execution adjustment unit, forms a closed-loop control loop. By iteratively optimizing the control parameters through real-time feedback of adjustment results, the precise alignment of the blank and the nine-corner cavity is achieved.

[0006] Furthermore, in the blank contour visual monitoring unit, the contour feature parameters of the nine corner regions of the blank are extracted and output. The contour feature parameters include the corner contour inflection point, the center reference point, the contour offset, and the contour distortion degree.

[0007] Furthermore, the specific steps for the cavity positioning sensing unit to establish a cavity spatial positioning reference coordinate system through the mold closing reference point and the corner center positioning mark of the nine-corner cavity are as follows: 2-3 fixed mold closing reference points are set at symmetrical positions on the edge of the mold parting surface as the reference for establishing the coordinate system. At the same time, embedded metal positioning marks are set at the center position of the inner wall of each corner of the nine-corner cavity as corner center positioning marks. With one of the mold closing reference points as the origin, the line connecting the reference points is the X-axis, and the direction perpendicular to the mold parting surface is the Z-axis, a three-dimensional right-angled cavity spatial positioning reference coordinate system is constructed.

[0008] Furthermore, in the cavity positioning sensing unit, the spatial positioning data of the nine-corner cavity includes spatial coordinates, coaxiality, and corner spacing parameters, and the mold closing accuracy data includes parallelism, mold closing alignment deviation, and mold closing stroke parameters.

[0009] Furthermore, the central processing unit receives the corner contour inflection point, center reference point, contour offset, and contour distortion parameters output by the blank contour visual monitoring unit, as well as the nine-corner cavity spatial coordinates, coaxiality, corner spacing, mold closing parallelism, mold closing alignment deviation, and mold closing stroke data transmitted by the cavity positioning sensing unit. Using a timestamp synchronization mechanism, a timestamp corresponding to the acquisition time is added to each set of received data. Combined with the blow molding cycle time, a synchronization threshold is set to eliminate abnormal time sequence data that exceeds the threshold range. The blank contour feature parameters, cavity spatial positioning data, and mold closing accuracy data collected within the same molding cycle time are matched one-to-one.

[0010] Furthermore, the central processing unit uses the cavity spatial positioning reference coordinate system as the calculation reference. First, it uniformly transforms the coordinates of the blank contour feature points after time-matching to this reference coordinate system. Then, it compares the spatial coordinates of the inflection points of each corner contour, the center reference point, and the corresponding cavity corner center positioning marks. It uses the spatial distance formula to calculate the linear offset of the feature points in the X, Y, and Z axes, and uses the vector angle formula to calculate the angular deflection deviation of the blank relative to the cavity. It obtains the corner spacing deviation by the difference between the measured value and the theoretical value of each corner spacing. It performs weighted averaging on each single corner deviation and finally obtains the overall alignment deviation of the blank relative to the nine-corner cavity.

[0011] Furthermore, the spatial distance formula is: ,in, It is the spatial linear deviation distance between the feature points of the blank outline and the positioning marks of the cavity corner center. It refers to the measured three-dimensional coordinates of the corner contour inflection point or center reference point of the blank in the cavity reference coordinate system. These are the theoretical standard coordinates of the nine-sided cavity corner center positioning mark in the same reference coordinate system; the vector angle formula is: ,in, It is the deviation of the orientation angle of the preform relative to the nine-corner cavity. It is the actual contour direction vector formed by the inflection points of the bottom contour of the blank. It is a standard contour direction vector composed of cavity corner center positioning marks. It is the dot product of two vectors. , Let be the magnitudes of the two vectors; the weighted average formula is: ,in , It is the combined alignment deviation between the preform and the nine-corner cavity. It is the first in the nine-cornered cavity Each corner , It is the first Local alignment deviations corresponding to each corner It is the first The weighting coefficients for corner deviations are allocated based on the degree of influence of the corners on the pallet forming quality.

[0012] Furthermore, the central processing unit incorporates a preform contour-cavity alignment deviation correction model. This model pre-stores a sample of the correspondence between preform alignment deviation and execution adjustment parameters during the blow molding of a nine-corner plastic tray. Combining the aforementioned quantified comprehensive alignment deviation, local deviations at each corner, and attitude deflection angle deviation, it establishes a mapping relationship between deviation data and preform extrusion guide adjustment amount, pre-blowing parameter adjustment amount, and mold closing alignment adjustment amount. An adaptive PID algorithm is used to complete the deviation correction calculation, automatically calculating the triaxial adjustment parameters of the preform extrusion guide mechanism, the pre-blowing pressure, flow rate, and time adjustment parameters, and the compensation adjustment parameters of the mold closing alignment mechanism that meet the deviation correction requirements. The adjustment parameters are converted into directly executable electrical signal commands, generating preform extrusion guide adjustment commands, pre-blowing parameter adjustment commands, and mold closing alignment adjustment commands, which are synchronously transmitted to the execution adjustment unit.

[0013] Furthermore, the central processing unit employs an adaptive PID algorithm to perform deviation correction calculations, the algorithm formula of which is: ,in, yes The adjustment output of the adjustment unit is executed at all times, including the parison extrusion guide adjustment, the pre-blowing parameter adjustment, and the mold closing alignment adjustment; It is a proportionality coefficient, which is dynamically adjusted according to the real-time changes in the alignment deviation between the blank and the cavity; yes The real-time alignment deviation value at any given moment, i.e., the combined alignment deviation between the preform and the cavity. The difference after subtracting the preset millimeter-level allowable deviation threshold; It is the integration time constant, used to eliminate long-term accumulated alignment errors. It is the differential time constant, used to predict the trend of deviation changes and adjust the adjustment amount in advance to avoid overshoot; It is 0 to The integral term of the alignment deviation value at any given time reflects the degree of accumulation of the deviation. yes The differential term of the alignment deviation value at any given time reflects the rate of change of the deviation.

[0014] Furthermore, the execution adjustment unit includes a preform extrusion guide adjustment component, a pre-expansion parameter adjustment component, and a mold closing alignment adjustment component. The preform extrusion guide adjustment component adopts a servo-driven guide structure, which dynamically adjusts the lateral displacement, longitudinal displacement, and angular posture of the preform extrusion guide mechanism according to the adjustment command, thereby correcting the positional offset generated during the preform conveying process. The pre-expansion parameter adjustment component adjusts the pre-expansion pressure, flow rate, and time parameters in real time through a proportional adjustment structure, optimizes the preform pre-forming contour shape, and eliminates contour distortion problems. The mold closing alignment adjustment component adopts a servo mold adjustment structure, which dynamically compensates for the mold closing parallelism deviation and cavity alignment deviation, and completes the calibration of the spatial positioning accuracy of the nine-corner cavity.

[0015] Compared with existing technologies, this intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallets has the following advantages: This invention achieves real-time quantitative monitoring of the preform outline and the nine-corner cavity positioning data of the mold through the collaborative work of the preform outline visual monitoring unit and the cavity positioning sensing unit. It effectively solves the problem of the difficulty in accurately obtaining the alignment deviation in traditional processes. Based on the dedicated preform outline-cavity alignment deviation correction model and closed-loop algorithm constructed by the central processing unit, it can dynamically adjust the preform extrusion guide, pre-blowing parameters and mold closing alignment in multiple dimensions without hysteresis. It can stably control the alignment deviation between the preform and the nine-corner cavity within the millimeter range, eliminate molding defects such as corner missing material and seam line misalignment of the nine-corner plastic pallet, and significantly improve the product molding qualification rate and consistency. At the same time, the full-process intelligent closed-loop control mode replaces the traditional manual experience adjustment, greatly improves the automation level of blow-molded nine-corner plastic pallet production, reduces production losses, and fully adapts to the needs of continuous and large-scale production.

[0016] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0018] Figure 1 A structural block diagram of a full-process intelligent monitoring and parameter closed-loop system for blow molding nine-cornered plastic pallets; Figure 2 A flowchart of the central processing unit of a fully intelligent monitoring and parameter closed-loop system for the entire process of blow molding a nine-corner plastic pallet. Figure 3 This is a flowchart of a fully intelligent monitoring and parameter closed-loop system for the entire process of blow molding a nine-corner plastic pallet. Detailed Implementation

[0019] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0020] This invention provides an intelligent monitoring and parameter closed-loop system for the entire process of blow molding a nine-corner plastic pallet, such as... Figure 1 As shown, by integrating a preform contour visual monitoring unit, a cavity positioning sensing unit, a central processing unit, an execution adjustment unit, and a closed-loop control unit, real-time monitoring, precise calculation, and dynamic adjustment of the alignment deviation between the preform contour and the nine-corner cavity of the mold are achieved. Utilizing visual monitoring and sensing positioning technology, real-time acquisition of preform contour feature data and mold nine-corner cavity positioning and mold closing accuracy data is possible. The central processing unit constructs a preform contour-cavity alignment deviation correction model, quantifies the alignment deviation, and generates execution adjustment commands. The execution adjustment unit dynamically adjusts the extrusion guide, pre-blowing parameters, and mold closing alignment accuracy according to the commands. The closed-loop control unit realizes closed-loop control of parameter iterative correction to ensure precise alignment between the preform and the nine-corner cavity.

[0021] The preform contour visual monitoring unit adopts a non-contact three-dimensional vision acquisition structure. Multiple sets of three-dimensional vision acquisition components are symmetrically arranged circumferentially along the preform extrusion conveying path. The density and position of the acquisition components are based on completely covering the overall contour of the preform and the nine-corner feature area. The nine-corner feature area is the key part of the preform corresponding to the nine corners of the nine-corner plastic tray after preforming, ensuring that there are no blind spots in the acquisition data.

[0022] The working cycle of the acquisition component is completely synchronized with the blow molding cycle. That is, according to the process nodes of parison extrusion and pre-blowing, acquisition is started immediately after the pre-forming process of each molding cycle is completed to obtain the three-dimensional point cloud data of the parison preform. After acquisition, the original three-dimensional point cloud data is preprocessed, and noise reduction, stitching and smoothing operations are performed in sequence: environmental noise and noise generated by equipment vibration are removed from the point cloud data through filtering algorithms; the partitioned point cloud data of multiple acquisition components are stitched and fused to form a complete overall three-dimensional point cloud model of the parison; the point cloud model is optimized through surface smoothing algorithms to eliminate local protrusions and depressions on the model surface and ensure the accuracy of contour extraction.

[0023] Based on the preprocessed complete 3D point cloud model of the billet, the contour feature parameters of the nine corner regions of the billet are extracted and standardized and quantized. Finally, the parameters are output to the central processing unit. The extracted contour feature parameters specifically include the corner contour inflection points, center reference points, contour offset, and contour distortion. The extraction and quantization methods for each parameter are as follows: Corner contour inflection point: determined by identifying the curvature change point of the nine-corner region contour of the blank, selecting the point whose curvature value exceeds the preset threshold as the effective contour inflection point, and recording its three-dimensional coordinates; Center reference point: Based on all the effective contour inflection points of each corner, the geometric center of the corner contour is obtained through the geometric center calculation method and used as the corner center reference point; Contour offset: Compare the actual extracted blank contour with the preset theoretical standard contour of the nine-corner plastic pallet blank, and calculate the position offset of the actual contour relative to the theoretical contour in the X, Y, and Z axes. Contour distortion degree: The degree of contour distortion in the nine-corner region of the blank is quantified by calculating the deviation rate between the actual contour morphological parameters and the theoretical standard contour morphological parameters. The deviation rate is the contour distortion degree.

[0024] The cavity positioning sensing unit uses a combination of the mold closing reference point and the nine-corner cavity center positioning mark to construct a three-dimensional rectangular cavity spatial positioning reference coordinate system. The specific implementation steps are as follows: Select symmetrical positions in the non-forming area at the edge of the mold parting surface and set 2-3 fixed mold closing reference points. The reference points adopt wear-resistant and displacement-proof fixed marking structures to ensure that their positions remain unchanged during the long-term opening and closing of the mold. Metal positioning marks are embedded at the center of the inner wall of each corner of the nine-cornered cavity as corner center positioning marks. The metal positioning marks are flush with the inner wall of the cavity to avoid affecting the mold closing accuracy and the molding quality of the plastic part due to protrusion. Using one of the mold closing reference points as the origin of the coordinate system, the line connecting any two mold closing reference points as the X-axis, and the direction perpendicular to the mold parting surface as the Z-axis, the Y-axis is determined according to the right-hand coordinate system rule. This completes the construction and calibration of the three-dimensional rectangular cavity spatial positioning reference coordinate system, which provides a unique reference for the calculation of all subsequent positioning data and deviation data.

[0025] After the coordinate system is calibrated, the spatial positioning data of the nine-corner cavity and the mold closing accuracy data are collected in real time through the sensing and acquisition components that match the reference point and corner center positioning marks. During the acquisition process, the data is initially standardized and converted into quantitative parameters under the reference coordinate system before being transmitted to the central processing unit.

[0026] The spatial positioning data of the nine-corner cavity includes the spatial coordinates of each corner center positioning mark in the reference coordinate system, the coaxiality of each corner of the cavity and the corner spacing parameters. The coaxiality is the degree of offset of the center axis of the cavity corner relative to the theoretical axis, and the corner spacing is the actual straight-line distance between two adjacent corner center positioning marks. The mold closing accuracy data includes the parallelism of the mold after mold closing, the mold closing alignment deviation and the mold closing stroke parameters. The parallelism is the degree of parallelism between the moving mold and the fixed mold parting surface. The mold closing alignment deviation is the amount of offset of the actual position of the moving mold after mold closing relative to the theoretical mold closing position. The mold closing stroke is the actual mold closing movement distance of the moving mold.

[0027] The central processing unit is responsible for receiving all process data transmitted from the blank contour visual monitoring unit and the cavity positioning sensing unit, completing data timing matching, quantifying the alignment deviation between the blank and the cavity, and generating execution adjustment commands based on the built-in model and algorithm, which are then transmitted to the execution adjustment unit. Figure 2 As shown, its specific working process is divided into three stages: data timing matching, alignment deviation quantification calculation, and execution of adjustment command generation.

[0028] To ensure the accuracy of subsequent deviation calculations, a timestamp synchronization mechanism is used to perform time-series matching of multi-source data. Specifically, the following steps are taken: A corresponding acquisition time timestamp is added to the received blank contour feature parameters, cavity spatial positioning data, and mold closing accuracy data; based on the actual molding cycle of the blow-molded nine-corner plastic tray, a time-series synchronization threshold is set, which is ±5% of the molding cycle length. Abnormal time-series data exceeding the threshold range are eliminated to ensure that the data used in the calculation are acquired data within the same molding cycle; the three types of data within the same molding cycle are matched one-to-one to form a complete single-cycle molding process data set, providing a data foundation for subsequent deviation calculations.

[0029] Using the cavity spatial positioning reference coordinate system as the sole calculation reference, multi-dimensional alignment deviation quantification calculation is performed on the process data set after time-matching, and finally the overall alignment deviation of the blank relative to the nine-corner cavity is obtained. The specific calculation steps are as follows: Coordinate normalization: The coordinates of the blank contour feature points (corner contour inflection points, center reference points) after time-matched are uniformly transformed to the cavity space positioning reference coordinate system to complete the coordinate normalization process of all feature points. Three-axis linear offset calculation: The spatial coordinates of the corner contour inflection points and center reference points of the blank are compared with the corner center positioning marks of the corresponding cavity. The linear offset of each feature point in the X, Y, and Z axes is calculated using the spatial distance formula: In the formula, It is the spatial linear deviation distance between the feature points of the blank outline and the positioning marks of the cavity corner center. It refers to the measured three-dimensional coordinates of the corner contour inflection point or center reference point of the blank in the cavity reference coordinate system. These are the theoretical standard coordinates of the nine-corner cavity center positioning marks under the same reference coordinate system; Attitude deflection angle deviation calculation: The angle deflection deviation of the blank relative to the cavity is calculated using the vector angle formula to quantify the degree of attitude distortion of the blank. The vector angle formula is as follows: ,in, It is the deviation of the orientation angle of the preform relative to the nine-corner cavity. It is the actual contour direction vector formed by the inflection points of the bottom contour of the blank. It is a standard contour direction vector composed of cavity corner center positioning marks. It is the dot product of two vectors. , Let be the magnitudes of the two vectors, respectively. Corner spacing deviation calculation: Calculate the difference between the actual spacing between each corner of the blank and the theoretical spacing between each corner of the cavity to obtain the corner spacing deviation of the nine corner areas of the blank; Comprehensive alignment deviation calculation: First, the three-axis linear offset, attitude deflection angle deviation, and corner spacing deviation of each single corner are comprehensively quantified to obtain the local alignment deviation corresponding to each corner. Then, a weighted average is applied to the local alignment deviations at the nine corners to obtain the overall alignment deviation of the blank relative to the nine-corner cavity. The weighted average formula is: In the formula, , The first in the nine-cornered cavity Each corner ( ), For the first The weighting coefficients for corner deviations are allocated based on the degree of influence of the corners on the forming quality and load-bearing performance of the nine-corner plastic pallet. The corners, which are critical load-bearing parts of the pallet, are assigned higher weighting coefficients, while the non-critical parts are assigned lower weighting coefficients.

[0030] The central processing unit has a built-in blank contour-cavity alignment deviation correction model. Combining the deviation data obtained from the above quantification, it performs deviation correction calculations through an adaptive algorithm, and finally generates directly executable electrical signal adjustment commands. The specific implementation is as follows: The deviation correction model was pre-tested through a large number of blow molding nine-corner plastic tray molding process experiments, storing the corresponding relationship samples of parison alignment deviation and execution adjustment parameters under different deviation ranges and molding conditions. Based on this sample library, the model, combined with the comprehensive alignment deviation, local deviations of each corner and attitude deflection angle deviation obtained in this quantification, establishes a precise mapping relationship between deviation data and parison extrusion guide adjustment amount, pre-blowing parameter adjustment amount, and mold closing alignment adjustment amount. An adaptive PID algorithm is used to perform deviation correction calculations, automatically calculating various adjustment parameters that meet the deviation correction requirements. The algorithm formula is as follows: In the formula, yes The adjustment output of the adjustment unit is executed at all times, including the parison extrusion guide adjustment, the pre-blowing parameter adjustment, and the mold closing alignment adjustment; It is a proportionality coefficient, which is dynamically adjusted according to the real-time changes in the alignment deviation between the blank and the cavity; yes The real-time alignment deviation value at any given moment, i.e., the combined alignment deviation between the preform and the cavity. The difference after subtracting the preset millimeter-level allowable deviation threshold; It is the integration time constant, used to eliminate long-term accumulated alignment errors. It is the differential time constant, used to predict the trend of deviation changes and adjust the adjustment amount in advance to avoid overshoot; It is 0 to The integral term of the alignment deviation value at any given time reflects the degree of accumulation of the deviation. yes The differential term of the alignment deviation value at any given time reflects the rate of change of the deviation; After calculating the triaxial adjustment parameters of the preform extrusion guiding mechanism, the pre-blowing pressure / flow / time adjustment parameters, and the compensation adjustment parameters of the die closing and alignment mechanism using an adaptive PID algorithm, the above parameters are converted into electrical signal commands that can be directly recognized by the execution adjustment unit. This generates preform extrusion guiding adjustment commands, pre-blowing parameter adjustment commands, and die closing and alignment adjustment commands, which are then synchronously transmitted to the execution adjustment unit.

[0031] The adjustment unit includes a preform extrusion guide adjustment component, a pre-expansion parameter adjustment component, and a mold closing alignment adjustment component. These three components receive corresponding adjustment commands transmitted from the central processing unit and independently and collaboratively complete the adjustment actions, achieving precise adjustment of the preform position, pre-forming shape, and mold closing accuracy. The specific implementation method is as follows: Parison extrusion guide adjustment component: adopts servo-driven guide structure, dynamically adjusts the lateral displacement, longitudinal displacement and angular attitude of parison extrusion guide mechanism according to parison extrusion guide adjustment command, accurately corrects the positional offset of parison in the X, Y and Z axes during the conveying process, so that the spatial position of parison matches the positioning requirements of the cavity; Pre-expansion parameter adjustment component: Through a proportional adjustment structure, the pre-expansion pressure, flow rate, and pre-expansion time parameters are adjusted in real time according to the pre-expansion parameter adjustment command. The degree of expansion of the parison is controlled by adjusting the pre-expansion pressure and flow rate, and the pre-forming time of the parison is controlled by adjusting the pre-expansion time. This optimizes the pre-forming contour shape of the parison, effectively eliminates the contour distortion problem in the nine-corner area of ​​the parison, and ensures that the parison contour features are compatible with the cavity contour. Mold closing alignment adjustment component: Adopting a servo adjustment structure, it performs micro-compensation adjustment on the mold closing position according to the mold closing alignment adjustment command, dynamically compensates for the parallelism deviation and cavity alignment deviation after mold closing, completes real-time calibration of the spatial positioning accuracy of the nine-corner cavity, and ensures that the actual positioning of the cavity matches the theoretical requirements of the cavity spatial positioning reference coordinate system.

[0032] The adjustment actions of the three adjustment components are synchronized with the blow molding cycle. After the adjustment is completed within a single molding cycle, the adjustment state is maintained until the molding process of that cycle is completed, thus avoiding interference with the molding process caused by the adjustment action.

[0033] The closed-loop control unit, central processing unit, and execution adjustment unit work together to form a closed-loop control loop throughout the entire process. The core functionality is real-time feedback of the adjustment results and iterative optimization of control parameters, ensuring that the alignment deviation between the blank and the nine-corner cavity is always controlled within a preset millimeter-level allowable deviation range. The specific implementation process is as follows: After the adjustment unit completes the adjustment action, the closed-loop control unit collects the adjusted blank contour feature parameters, cavity positioning data and mold closing accuracy data in real time through the matching sensing and acquisition components, and transmits them as feedback data to the central processing unit. The central processing unit repeatedly performs data timing matching and alignment deviation quantification calculation steps on the feedback data to determine whether the alignment deviation between the adjusted blank and the cavity reaches the preset millimeter-level allowable deviation threshold. If the adjusted alignment deviation still exceeds the threshold range, the central processing unit iteratively optimizes the proportional coefficient, integral time constant, and derivative time constant of the adaptive PID algorithm based on the feedback data, and regenerates a new execution adjustment instruction, which is then sent to the execution adjustment unit for secondary precise adjustment. If the adjusted alignment deviation reaches the preset threshold requirement, the control of this molding cycle is completed, and the closed-loop control unit enters the monitoring and control process of the next molding cycle with the system. The system continuously executes a closed-loop process during the continuous molding cycle, realizing full-process, uninterrupted intelligent monitoring and closed-loop parameter control of the blow molding nine-corner plastic pallet molding process.

[0034] The intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallets of the present invention, when applied to the blow molding nine-corner plastic pallet process, such as... Figure 3 As shown, the overall workflow is as follows: During the preform extrusion preforming stage, the preform contour visual monitoring unit begins to collect the three-dimensional point cloud data of the preform in real time and extract the contour feature parameters. The cavity positioning sensing unit completes the establishment of the cavity spatial positioning reference coordinate system and collects the cavity spatial positioning data and mold closing accuracy data. The central processing unit simultaneously receives process data from both types of units. After completing the data timing matching, it quantitatively calculates the overall alignment deviation of the preform-cavity and various local deviations. The central processing unit generates corresponding execution adjustment instructions and sends them to the execution adjustment unit through the built-in deviation correction model and adaptive PID algorithm; The execution adjustment unit adjusts the parison extrusion guide, pre-blowing parameters, and mold closing alignment accuracy according to the adjustment instructions, and feeds back the adjustment results to the central processing unit and the closed-loop control unit. The closed-loop control unit compares and analyzes the adjustment effect. If the alignment deviation does not meet the standard, the deviation data is sent back to the central processing unit. The central processing unit iteratively optimizes the adjustment parameters and issues the adjustment command again until the deviation meets the standard. Throughout the molding process, each unit works in close collaboration, and the closed-loop control unit provides real-time feedback and optimization throughout the entire process to ensure precise alignment between the preform and the nine-corner cavity, thus completing the high-precision molding of the nine-corner plastic tray.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A fully intelligent monitoring and parameter closed-loop system for the entire process of blow molding a nine-corner plastic pallet, characterized in that, The system includes: a blank contour visual monitoring unit, a cavity positioning sensing unit, a central processing unit, an execution and adjustment unit, and a closed-loop control unit; The blank contour visual monitoring unit adopts a non-contact three-dimensional visual acquisition structure. Acquisition components covering the overall contour and nine-corner feature area of ​​the blank are symmetrically arranged along the circumference of the blank. The pre-formed three-dimensional point cloud data of the blank is acquired according to the forming rhythm. After data processing, the contour feature parameters of the nine-corner area of ​​the blank are extracted and output. The cavity positioning sensing unit establishes a cavity spatial positioning reference coordinate system by using the mold closing reference point and the corner center positioning mark of the nine-corner cavity, and collects the spatial positioning data of the nine-corner cavity and the mold closing accuracy data. The central processing unit synchronously receives the blank contour feature parameters, cavity spatial positioning data and mold closing accuracy data and performs timing matching. Based on the cavity reference coordinate system, it quantitatively calculates the alignment deviation between the blank and the cavity, and generates and executes adjustment commands through the built-in blank contour-cavity alignment deviation correction model. The execution adjustment unit includes a preform extrusion guide adjustment component, a pre-blowing parameter adjustment component, and a mold closing alignment adjustment component. After receiving the adjustment command, it dynamically adjusts the preform extrusion guide, pre-blowing parameters, and mold closing alignment accuracy. The closed-loop control unit, together with the central processing unit and the execution adjustment unit, forms a closed-loop control loop. By iteratively optimizing the control parameters through real-time feedback of adjustment results, the precise alignment of the blank and the nine-corner cavity is achieved.

2. The intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallet as described in claim 1, characterized in that, In the blank contour visual monitoring unit, the contour feature parameters of the nine corner regions of the blank are extracted and output. The contour feature parameters include the corner contour inflection point, the center reference point, the contour offset, and the contour distortion degree.

3. The intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallet as described in claim 1, characterized in that, The specific steps for the cavity positioning sensing unit to establish a cavity spatial positioning reference coordinate system through the mold closing reference point and the corner center positioning mark of the nine-corner cavity are as follows: 2-3 fixed mold closing reference points are set at symmetrical positions on the edge of the mold parting surface as the reference for establishing the coordinate system. At the same time, embedded metal positioning marks are set at the center position of the inner wall of each corner of the nine-corner cavity as corner center positioning marks. With one of the mold closing reference points as the origin, the line connecting the reference points is the X-axis, and the direction perpendicular to the mold parting surface is the Z-axis, a three-dimensional right-angled cavity spatial positioning reference coordinate system is constructed.

4. The intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallet as described in claim 1, characterized in that, In the cavity positioning sensing unit, the spatial positioning data of the nine-corner cavity includes spatial coordinates, coaxiality and corner spacing parameters, and the mold closing accuracy data includes parallelism, mold closing alignment deviation and mold closing stroke parameters.

5. The intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallet as described in claim 1, characterized in that, The central processing unit receives parameters from the blank contour visual monitoring unit, including the corner contour inflection point, center reference point, contour offset, and contour distortion. It also receives data from the cavity positioning sensing unit, including the nine-corner cavity spatial coordinates, coaxiality, corner spacing, mold closing parallelism, mold closing alignment deviation, and mold closing stroke. Using a timestamp synchronization mechanism, the unit adds a timestamp corresponding to the acquisition time to each set of received data. Combined with the blow molding cycle time, a synchronization threshold is set to eliminate abnormal time-series data that exceeds the threshold range. The blank contour feature parameters, cavity spatial positioning data, and mold closing accuracy data collected within the same molding cycle time are matched one-to-one.

6. The intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallet as described in claim 1, characterized in that, The central processing unit uses the cavity spatial positioning reference coordinate system as the calculation reference. First, it converts the coordinates of the blank contour feature points after time-matching to the reference coordinate system. Then, it compares the spatial coordinates of the inflection points of each corner contour, the center reference point, and the corresponding cavity corner center positioning marks. It uses the spatial distance formula to calculate the linear offset of the feature points in the X, Y, and Z axes, and uses the vector angle formula to calculate the angular deflection deviation of the blank relative to the cavity. It obtains the corner spacing deviation by the difference between the measured value and the theoretical value of the corner spacing. It performs weighted averaging on each single corner deviation and finally obtains the overall alignment deviation of the blank relative to the nine-corner cavity.

7. The intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallet as described in claim 6, characterized in that, The formula for spatial distance is: ,in, It is the spatial linear deviation distance between the feature points of the blank outline and the positioning marks of the cavity corner center. It refers to the measured three-dimensional coordinates of the corner contour inflection point or center reference point of the blank in the cavity reference coordinate system. These are the theoretical standard coordinates of the nine-sided cavity corner center positioning mark in the same reference coordinate system; the vector angle formula is: ,in, It is the deviation of the orientation angle of the preform relative to the nine-corner cavity. It is the actual contour direction vector formed by the inflection points of the bottom contour of the blank. It is a standard contour direction vector composed of cavity corner center positioning marks. It is the dot product of two vectors. , Let be the magnitudes of the two vectors; the weighted average formula is: ,in , It is the combined alignment deviation between the preform and the nine-corner cavity. It is the first in the nine-cornered cavity Each corner , It is the first Local alignment deviations corresponding to each corner It is the first The weighting coefficients for corner deviations are allocated based on the degree of influence of the corners on the pallet forming quality.

8. The intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallet as described in claim 1, characterized in that, The central processing unit has a built-in preform contour-cavity alignment deviation correction model. This model pre-stores a sample of the correspondence between preform alignment deviation and execution adjustment parameters during the blow molding of a nine-corner plastic tray. Combined with the aforementioned quantified comprehensive alignment deviation, local deviations at each corner, and attitude deflection angle deviation, it establishes a mapping relationship between deviation data and preform extrusion guide adjustment amount, pre-blowing parameter adjustment amount, and mold closing alignment adjustment amount. An adaptive PID algorithm is used to complete the deviation correction calculation, automatically calculating the triaxial adjustment parameters of the preform extrusion guide mechanism, the pre-blowing pressure, flow rate, and time adjustment parameters, and the compensation adjustment parameters of the mold closing alignment mechanism that meet the deviation correction requirements. The adjustment parameters are converted into directly executable electrical signal commands, generating preform extrusion guide adjustment commands, pre-blowing parameter adjustment commands, and mold closing alignment adjustment commands, which are synchronously transmitted to the execution adjustment unit.

9. The intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallet as described in claim 8, characterized in that, The central processing unit uses an adaptive PID algorithm to perform deviation correction calculations. The algorithm formula is as follows: ,in, yes The adjustment output of the adjustment unit is executed at all times, including the parison extrusion guide adjustment, the pre-blowing parameter adjustment, and the mold closing alignment adjustment; It is a proportionality coefficient, which is dynamically adjusted according to the real-time changes in the alignment deviation between the blank and the cavity; yes The real-time alignment deviation value at any given moment, i.e., the combined alignment deviation between the preform and the cavity. The difference after subtracting the preset millimeter-level allowable deviation threshold; It is the integration time constant, used to eliminate long-term accumulated alignment errors. It is the differential time constant, used to predict the trend of deviation changes and adjust the adjustment amount in advance to avoid overshoot; It is 0 to The integral term of the alignment deviation value at any given time reflects the degree of accumulation of the deviation. The differential term of the positional deviation value at any given time reflects the rate of change of the deviation.

10. The intelligent monitoring and parameter closed-loop system for the entire process of blow molding nine-corner plastic pallet as described in claim 1, characterized in that, The execution adjustment unit includes a preform extrusion guide adjustment component, a pre-expansion parameter adjustment component, and a mold closing alignment adjustment component. The preform extrusion guide adjustment component adopts a servo-driven guide structure, which dynamically adjusts the lateral displacement, longitudinal displacement, and angular posture of the preform extrusion guide mechanism according to the adjustment command, thereby correcting the positional offset generated during the preform conveying process. The pre-expansion parameter adjustment component adjusts the pre-expansion pressure, flow rate, and time parameters in real time through a proportional adjustment structure, optimizes the preform pre-forming contour shape, and eliminates contour distortion problems. The mold closing alignment adjustment component adopts a servo mold adjustment structure, which dynamically compensates for the mold closing parallelism deviation and cavity alignment deviation, and completes the calibration of the spatial positioning accuracy of the nine-corner cavity.

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