Injection molding production monitoring method and system based on mold motion sensing, storage medium

Abstract

The present invention discloses an injection molding production monitoring method, system, and storage medium based on mold motion sensing, including: Step S1, obtaining the opening and closing state of the mold through a differential induction circuit; Step S2, calculating the average production cycle according to the opening and closing state of the mold; Step S3, performing product quality monitoring, production output monitoring, mold life, and health status monitoring according to the average production cycle. By adopting the technical solution of the present invention, the efficiency and quality control of injection molding production are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of injection molding, and particularly relates to an injection production monitoring method and system based on mold motion sensing, and a storage medium. Background Art

[0002] The automatic monitoring of the injection production process in each injection molding factory is mainly divided into two methods: monitoring based on injection molding machine data and monitoring based on mold motion. Among them, the monitoring method based on injection molding machine data has obvious advantages in terms of the variety and accuracy of monitoring functions because it can usually obtain relatively rich signals and data. However, due to the wide variety of injection molding machine brands and models, the signal types, communication interfaces, and data formats of each injection molding machine system are different, resulting in a large amount of work in implementing the monitoring system. Moreover, the monitoring system based on injection molding machine data has no direct relationship with the mold itself. When counting the production output of the mold and conducting mold health management, it is necessary to first match and associate with the mold through the production scheduling and work reporting system, which requires a relatively complete function of the injection MES management system and is costly, with low applicability to small and medium-sized enterprises.

[0003] Currently, the injection production monitoring method based on mold motion is mainly used for the statistics of production output, and the maintenance plan of the mold is carried out based on the output data. Currently, the monitoring devices used in this monitoring method are mainly divided into two categories: mechanical counters and magnetic induction counters. The mechanical counter is used to record the number of mold openings and closings, which serves as the basis for production output statistics, mold maintenance, and scrapping. The mechanical counter is usually installed on the fixed mold. When the mold is closed, the moving mold pushes the ejector rod of the counter, driving the cam to rotate and count. The main disadvantages of the mechanical counter mainly include: single function, only used for counting, unable to calculate the production cycle and quality monitoring based on it; no communication function, large manual data collection workload, and data lag; large mechanical wear and short counter life. The magnetic induction counter can realize functions such as production output statistics, production cycle calculation, and data communication. The magnetic induction counter body is installed on the fixed mold of the mold, and a magnet needs to be installed on the moving mold. The installation workload is large, the cost is high, and there are risks such as magnet damage caused by vibration, demagnetization of the magnet caused by factors such as high temperature, strong magnetic interference, and natural demagnetization. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an injection production monitoring method and system based on mold motion sensing, and a storage medium, to realize the statistics of injection production output, product quality monitoring, and mold health status and mold life management, and improve the efficiency and quality control of injection production.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An injection molding production monitoring method based on mold motion sensing, comprising:

[0007] Step S1: Obtain the opening and closing state of the mold through a differential induction circuit; wherein, the differential induction circuit includes: an induction module and a reference module, both the induction module and the reference module include an inductor, a resonance circuit, and a frequency-voltage conversion circuit, and the output signals of the induction module and the reference module are processed by a differential amplifier;

[0008] Step S2: Calculate the average production cycle according to the opening and closing state of the mold;

[0009] Step S3: Perform product quality monitoring, production output monitoring, mold life and health status monitoring according to the average production cycle.

[0010] Preferably, step S2 includes:

[0011] Obtain the opening and closing action time of the mold according to the opening and closing state of the mold, and calculate the duration data of each molding cycle;

[0012] Use the bubble sort algorithm to process the duration data of the molding cycle to exclude outliers and calculate the average production cycle.

[0013] The present invention also provides an injection molding production monitoring system based on mold motion sensing, comprising:

[0014] The first processing module is used to obtain the opening and closing state of the mold through a differential induction circuit; wherein, the differential induction circuit includes: an induction module and a reference module, both the induction module and the reference module include an inductor, a resonance circuit, and a frequency-voltage conversion circuit, and the output signals of the induction module and the reference module are processed by a differential amplifier;

[0015] The second processing module is used to calculate the average production cycle according to the opening and closing state of the mold;

[0016] The third processing module is used to perform product quality monitoring, production output monitoring, mold life and health status monitoring according to the average production cycle.

[0017] Preferably, the second processing module includes:

[0018] The first processing unit is used to obtain the opening and closing action time of the mold according to the opening and closing state of the mold, and calculate the duration data of each molding cycle;

[0019] The second processing unit is used to use the bubble sort algorithm to process the duration data of the molding cycle to exclude outliers and calculate the average production cycle.

[0020] The present invention also provides a storage medium, on which a computer program is stored, and the computer program executes an injection molding production monitoring method based on mold movement sensing when running.

[0021] The present invention monitors the opening and closing state of the mold in real time through inductive metal sensing technology. The differential circuit design can improve the anti-interference ability of the circuit and accurately record the production action time data. The bubble sort algorithm is used to process the data to eliminate outliers and calculate the average production cycle. Through standard deviation calculation and numerical deviation comparison, abnormal production actions are excluded to statistically count the effective production output. Furthermore, based on the real-time monitoring of the production cycle, the monitoring and early warning of product quality are realized. Based on the statistics of the number of mold openings and closings and the tracking of the standard deviation of the production cycle, the health status and service life of the mold are evaluated. All the collected and calculated data, as well as the real-time monitoring and early warning information, etc., are sent to the industrial Internet platform through 5G communication technology, which is convenient for the expansion and optimization of system functions and further improves the intelligent level of production management.

[0022] Based on the non-contact electromagnetic induction principle of inductance, the present invention does not have the possible fault problems of magnetic reed switches, mechanical switches, contact switches, etc. It does not require the use of magnets, has less installation work and lower costs, and is not affected by a constant magnetic field, with stronger anti-interference ability, and can work reliably in environments such as dusty, humid, and oily. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only the embodiments of the present invention. For those of ordinary skill in the art, without creative work, other drawings can also be obtained according to the provided drawings.

[0024] Figure 1 It is a flowchart of the injection molding production monitoring method based on mold movement sensing in the embodiments of the present invention;

[0025] Figure 2 It is a principle block diagram of a differential inductive metal sensing circuit;

[0026] Figure 3 It is a schematic diagram of the signal output curve of the mold movement process sensing circuit;

[0027] Figure 4 It is a schematic diagram of the arrangement of inductance coils;

[0028] Figure 5 It is a schematic diagram of the stacking of inductance coils. Detailed Embodiments

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0030] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0031] Embodiment 1:

[0032] As Figure 1 shown, the embodiment of the present invention provides an injection molding production monitoring method based on mold movement sensing, including:

[0033] Step S1: Obtain the opening and closing state of the mold through a differential induction circuit;

[0034] Step S2: Calculate the average production cycle according to the opening and closing state of the mold;

[0035] Step S3: Perform product quality monitoring, production output monitoring, mold life and health status monitoring according to the average production cycle.

[0036] As an implementation manner of the embodiment of the present invention, in step S1, based on the metal property of the mold, the present invention uses inductive metal sensing technology to monitor the opening and closing state of the mold in real time. This method only needs to install induction equipment on the fixed mold of the mold, and no device needs to be installed on the moving mold. The induction equipment can accurately capture the opening and closing actions of the mold and convert these actions into electrical signals for recording and analysis.

[0037] The induction equipment of the present invention internally includes a resonant circuit. When metal approaches the inductor of the resonant circuit, eddy currents will be generated around the inductor, causing an increase in the equivalent inductance and forcing the resonant frequency to decrease. The calculation formula of the resonant frequency is as follows:

[0038]

[0039] Among them, L is the inductance and C is the capacitance. When L increases, the resonant frequency f decreases. The change in the resonant frequency directly reflects the opening and closing actions of the mold.

[0040] In order to monitor the change of the resonant frequency in real time, the present invention designs a frequency-voltage (F / V) conversion circuit to convert the frequency signal into an analog voltage signal that is more suitable for subsequent circuit processing. The frequency-voltage conversion circuit can linearly convert the input frequency signal into a corresponding voltage output. When the input resonant frequency increases, the voltage output by the conversion circuit will increase accordingly; when the input resonant frequency decreases, the output voltage will decrease accordingly. This linear relationship enables the change of frequency to be intuitively reflected in the form of voltage, facilitating further processing by the circuit.

[0041] To enhance the anti-interference performance of the system, the present invention designs a differential induction circuit. By introducing a differential structure, this circuit can effectively suppress common-mode interference and improve the stability and measurement accuracy of the system. The differential induction circuit includes: an induction module, a reference module, a differential amplifier, and a reference bias adjustment circuit. The induction module includes: a first induction inductor, a first resonant circuit, and a first frequency-voltage conversion circuit. The reference module includes: a second induction inductor, a second resonant circuit, and a second frequency-voltage conversion circuit. The first induction inductor, the first resonant circuit, and the first frequency-voltage conversion circuit are connected in sequence. The second induction inductor, the second resonant circuit, and the second frequency-voltage conversion circuit are connected in sequence. The first frequency-voltage conversion circuit and the second frequency-voltage conversion circuit are connected to the differential amplifier. The reference bias adjustment circuit is connected to the output terminal of the second frequency-voltage conversion circuit and the input terminal of the differential amplifier. The output signals of the induction module and the reference module are processed by the differential amplifier. By comparing the output signals of the two modules, the influence of interference factors such as environmental noise and temperature drift is eliminated. The principle block diagram of the differential induction circuit is as Figure 2 shown:

[0042] The induction module is as follows:

[0043] The first induction inductor L sense : used to sense the change in the mold opening and closing state, and its inductance value will change with the position of the moving mold.

[0044] The first resonant circuit: used to convert the inductance change into a change in the resonant frequency. The resonant frequency is inversely proportional to the inductance value.

[0045] The first frequency-voltage conversion circuit: converts the resonant frequency signal into an analog voltage signal and outputs a voltage value proportional to the frequency.

[0046] The reference module is as follows:

[0047] The second reference inductor L ref : The inductor in the reference module has the same structure as the inductor in the induction module. However, in terms of the installation position, the reference inductor L ref is at a position farther from the moving mold induction surface than the induction inductor L sense such asFigure 3 As shown, to achieve the difference in the decreasing rate of the inductance values of the two during the same period of mold clamping.

[0048] Second resonance circuit: The same as the resonance circuit in the induction module, used to generate a reference frequency signal.

[0049] Second frequency-voltage conversion circuit: Converts the reference frequency signal into an analog voltage signal and outputs a reference voltage value.

[0050] The reference bias adjustment circuit is as follows:

[0051] Used to adjust the static output voltage value of the reference module to ensure that when the mold is in the open state, the output voltage of the reference module is slightly lower than the output voltage of the induction module, ensuring that the differential circuit does not operate at the output switching point and preventing frequent output switching.

[0052] The reference bias shifts the reference inductance curve downward. Combining with the difference in the installation position, the reference inductance curve is shifted to the right at the same time, achieving the intersection of the reference curve and the induction curve at a certain point, and this point is the action switching point, as Figure 3 shown.

[0053] Adjusting the bias can achieve the adjustment of the position of the action switching point (induction distance).

[0054] The differential signal processing is as follows:

[0055] The output signals of the induction module and the reference module are processed by a differential amplifier to compare the magnitudes of the voltages of the two.

[0056] Through the differential circuit, common-mode interferences such as environmental noise and temperature drift can be effectively eliminated, and the effective signals related to mold opening and closing can be extracted.

[0057] The induction inductor and the reference inductor are designed as two PCB coil inductors with exactly the same structure. The induction inductor is located on the top layer, closer to the moving mold, and the reference inductor is located on the bottom layer, and the two are arranged staggeredly, as Figure 4 and Figure 5 shown.

[0058] To obtain a more appropriate induction distance, the vertical distance between the induction inductor and the reference inductor should be maximized as much as possible. It is recommended that the PCB use a board with a thickness of 2.0 mm or more. The stacking schematic diagram is as Figure 5 shown.

[0059] When the mold is in the open state, the moving mold is far away from the induction device, and both the induction inductor and the reference inductor are not affected. The two have the same inductance value, the same resonance frequency, and both F / Vs output the same voltage. However, the reference module's negative bias is adjusted to make the output voltage of the reference module slightly lower than the output voltage of the induction module. At this time, the differential amplifier outputs a high level.

[0060] When the moving mold approaches the induction device, both the induction inductance and the reference inductance will be affected. However, since the induction inductance is closer to the target, its inductance value will decrease more, resulting in a lower voltage output by the F / V of the induction module.

[0061] When the moving mold continuously approaches the fixed mold to a certain position, the F / V output voltage of the induction module is lower than the F / V output voltage of the reference module. At this time, the differential amplifier outputs a low level, indicating that the mold has entered the mold closing state, such as Figure 3 the intersection point of the voltage curves in.

[0062] As an implementation manner of the embodiment of the present invention, in step S2, the production cycle duration is an important indicator reflecting the stability of the injection molding process, and there is a close relationship between it and the product quality. The average production cycle provides a calculation basis for quality monitoring, output statistics, and mold health management based on the production cycle.

[0063] The present invention defines the production cycle duration as the time interval from the closing of the mold this time to the opening of the mold this time, that is, it represents the molding time required to produce one mold of products.

[0064] Based on the mold opening and closing motion induction method, this system monitors the opening and closing state of the mold in real time, records the opening and closing motion time of the mold, and calculates the duration of each molding cycle.

[0065] The present invention continuously collects the real-time molding cycle of the mold through the induction method, and uses the molding cycle durations of the latest 50 molds as the data basis for calculating and updating the average production cycle. When a new duration data is collected, the earliest duration data in the original data sequence will be removed, and the new duration data will be moved in. The first-in, first-out data input method always keeps the duration data of 50 molds as the latest data.

[0066] The bubble sort algorithm is a simple and intuitive sorting algorithm, suitable for sorting small-scale data. By traversing the data multiple times, the larger elements are gradually "bubbled" to the end of the data sequence. In the present invention, the bubble sort algorithm is used to sort the duration data of 50 molds collected, and the possible abnormal data is arranged at both ends of the data sequence for subsequent data processing. The specific steps are as follows:

[0067] (1). Starting from the first data, compare two adjacent data in turn. If the previous data is greater than the latter data, exchange their positions.

[0068] (2). Repeat the above steps until all data is arranged in ascending order.

[0069] Through the bubble sort algorithm, the system can arrange the outliers (such as values that are too large or too small) in the duration data to both ends of the sequence, thus facilitating subsequent data processing.

[0070] After completing the bubble sort algorithm for sorting, the system takes the duration data of the middle 30 modules (modules 11 to 40), and calculates its average value as the latest average production cycle. The specific calculation formula is as follows:

[0071]

[0072] Among them, is the average production cycle, is the i-th duration data after sorting.

[0073] The algorithms of bubble sort and averaging the middle data can effectively eliminate the interference of extreme values on the calculation of the average production cycle and improve the reliability of the data. At the same time, the first-in, first-out data input method can ensure that after the actual production cycle changes, the calculated average production cycle can gradually approach the actual value as the latest 50-module data is input.

[0074] As an implementation manner of the embodiment of the present invention, in step S3, the product quality monitoring is specifically as follows:

[0075] During the injection molding production process, the production cycle duration is an important indicator reflecting production efficiency and product quality. An abnormal production cycle often means equipment failure, process parameter fluctuations, or raw material problems, ultimately leading to a decline in product quality. Therefore, real-time monitoring of the production cycle duration and its effective analysis are of great significance for improving the quality and efficiency of injection molding production.

[0076] The present invention monitors the production cycle fluctuations, timely identifies abnormal production cycle states, and sends quality warnings by processing real-time production cycle duration data.

[0077] Based on statistical methods, the present invention uses the standard deviation principle to identify abnormal production cycle data. The steps are as follows:

[0078] (1). Based on the calculation result of the average production cycle, calculate the overall standard deviation of the middle 30-module data, as shown in the following formula:

[0079]

[0080] (2). Set the identification threshold for abnormal data. When the deviation between the data point (real-time production cycle) and the mean value (average production cycle) exceeds 2 times the standard deviation, it is considered abnormal data, and it is determined that there is a quality problem in the current production. The formula is as follows:

[0081]

[0082] As an implementation manner of an embodiment of the present invention, in step S3, the production output monitoring is specifically as follows:

[0083] Output monitoring is an important link in production management, which is directly related to the execution of production plans and the optimal allocation of resources. The present invention records the number of times the mold opens and closes during the current production process, identifies abnormal production actions, and statistically calculates the effective production output in real time.

[0084] Adopt a production output statistical method based on the number of times the mold opens and closes. Each time the mold closes and completes an injection molding until it opens, the equipment will automatically record a production action, calculate the output during the current production process, and accumulate and calculate the total production output of the mold.

[0085] During the actual use of the mold, in addition to the normal production mode, the working state of the mold also includes abnormal working modes such as trial molding, machine adjustment, and mold repair. The number of times the mold opens and closes collected under abnormal production modes is not valid production output data, so it cannot be used as injection production output monitoring data. The present invention processes the real-time production cycle duration data to identify abnormal data, discovers abnormal production states in a timely manner, and avoids the influence of invalid production action output statistics. The present invention is based on statistical methods and uses the standard deviation principle to identify abnormal data.

[0086] Based on the calculation of the standard deviation, set the identification threshold for abnormal data. When the deviation between the data point (real-time production cycle) and the mean value (average production cycle) exceeds 3 times the standard deviation, it is considered abnormal data, and the number of times the mold opens and closes data of this mold is not included in the actual output. The formula is as follows:

[0087]

[0088] As an implementation manner of an embodiment of the present invention, in step S3, the mold life and health status monitoring are as follows:

[0089] The monitoring of the mold life and health status is of great significance for reducing production costs and improving production efficiency. The present invention records the number of times the mold is used and monitors the standard deviation of the production cycle to evaluate the service life and health status of the mold in real time.

[0090] The number of times the mold is used is an important indicator for evaluating its life. The present invention monitors the opening and closing state of the mold and records the number of times the mold is used in real time. Each time the mold closes and completes an injection molding, the number of times of use will be automatically incremented by one. By accumulating the number of times of use, the usage situation of the mold can be monitored in real time, and the remaining life of the mold can be predicted according to the preset life threshold in combination with the mold health status data.

[0091] The standard deviation of the production cycle is a statistical indicator that measures the degree of fluctuation in the production cycle. The larger the standard deviation, the greater the fluctuation in the production cycle, and the worse the health condition of the mold may be. Based on the standard deviation calculation method, by monitoring and analyzing the change trend of the standard deviation of the production cycle, potential health problems of the mold can be detected in a timely manner, maintenance reminders can be sent, and the abnormal status and occurrence time of the mold can be recorded, providing data support for subsequent maintenance and replacement.

[0092] The present invention defines the mold health status coefficient h as:

[0093]

[0094] Where is the average production cycle, is the standard deviation. When is 0, it means that the production cycle of each mold is the same, which is an ideal state. At this time, h = 100% indicates that the mold is in the best health state.

[0095] Under ideal conditions, the remaining life of the mold is equal to the total life of the mold (the maximum allowable number of uses) minus the consumed life (the number of times already used). However, during the use of the mold, usually due to improper use of the mold, untimely maintenance, etc., the health state of the mold cannot reach the ideal value. Therefore, in the actual production process, the remaining life of the mold needs to be multiplied by the health state coefficient of the ideal remaining value. The specific life prediction formula is as follows:

[0096]

[0097] Where, is the remaining life of the mold, is the total life of the mold, is the number of times the mold has been used, and h is the mold health state coefficient. When the mold is not well maintained or the mold operates with problems, the mold health state coefficient h will be less than 1, and the remaining life of the mold will be less than the ideal remaining number of uses of the mold.

[0098] The embodiment of the present invention adopts differential inductive mold motion sensing to monitor the opening and closing motion of the mold in real time, calculate the production cycle of the mold, and processes the production cycle time data using the bubble sort algorithm and the standard deviation statistical algorithm, which can effectively identify product quality problems, accurately count the production output, and accurately predict the health state and service life of the mold. This method has the characteristics of low cost, high reliability, simple installation and implementation, wide applicability, etc. It is an efficient injection molding production process monitoring method and has broad application prospects.

[0099] Example 2:

[0100] The embodiment of the present invention also provides an injection molding production monitoring system based on mold motion sensing, including:

[0101] The first processing module is used to obtain the opening and closing state of the mold through a differential induction circuit; wherein, the differential induction circuit includes: an induction module and a reference module, both the induction module and the reference module include an inductor, a resonant circuit and a frequency-voltage conversion circuit, and the output signals of the induction module and the reference module are processed by a differential amplifier;

[0102] The second processing module is used to calculate the average production cycle according to the opening and closing state of the mold;

[0103] The third processing module is used to monitor product quality, production output, mold life and health status according to the average production cycle.

[0104] As an implementation manner of the embodiment of the present invention, the second processing module includes:

[0105] The first processing unit is used to obtain the opening and closing action time of the mold according to the opening and closing state of the mold, and calculate the duration data of each molding cycle;

[0106] The second processing unit is used to process the duration data of the molding cycle by using the bubble sort algorithm to exclude outliers and calculate the average production cycle.

[0107] Embodiment 3:

[0108] The embodiment of the present invention also provides a storage medium, on which a computer program is stored, and the computer program executes the injection molding production monitoring method based on mold action induction when running.

[0109] The above embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An injection molding production monitoring method based on mold motion sensing, characterized in that Including: Step S1: Obtain the opening and closing state of the mold through a differential induction circuit; wherein, the differential induction circuit includes an induction module and a reference module, both the induction module and the reference module include an inductor, a resonant circuit and a frequency-voltage conversion circuit, and the output signals of the induction module and the reference module are processed by a differential amplifier; Step S2: Calculate the average production cycle according to the opening and closing state of the mold; Step S3: Monitor product quality, production output, mold life and health status according to the average production cycle; Step S2 includes: Obtain the opening and closing action time of the mold according to the opening and closing state of the mold, and calculate the duration data of each molding cycle; Use the bubble sort algorithm to process the duration data of the molding cycle to exclude outliers and calculate the average production cycle.

2. An injection molding production monitoring system based on mold motion sensing, characterized in that, Including: A first processing module for obtaining the opening and closing state of the mold through a differential induction circuit; wherein, the differential induction circuit includes an induction module and a reference module, both the induction module and the reference module include an inductor, a resonant circuit and a frequency-voltage conversion circuit, and the output signals of the induction module and the reference module are processed by a differential amplifier; A second processing module for calculating the average production cycle according to the opening and closing state of the mold; A third processing module for monitoring product quality, production output, mold life and health status according to the average production cycle; The second processing module includes: A first processing unit for obtaining the opening and closing action time of the mold according to the opening and closing state of the mold, and calculating the duration data of each molding cycle; A second processing unit for using the bubble sort algorithm to process the duration data of the molding cycle to exclude outliers and calculate the average production cycle.

3. A storage medium, characterized in that, A computer program is stored on the storage medium, and the computer program executes the injection molding production monitoring method based on mold action induction as described in claim 1 when running.

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