Injection molding control method and system for plastic box body of junction box

Abstract

The invention relates to the technical field of injection molding control, in particular to an injection molding control method and system for a plastic box body of a junction box, and the method comprises the steps: obtaining the injection speed of an injection molding machine and the temperatures of the front, middle and rear positions of a charging barrel in the injection molding process of the plastic box body of the junction box; obtaining the temperature flow deviation of the charging barrel at each moment and the melt time flow fluctuation degree of the charging barrel, obtaining the temperature interference adjustment coefficient of the injection rate of the injection molding machine by combining with the average level of the temperature preset initial values of all positions of the charging barrel, and further obtaining the target quantity of the injection rate of the injection molding machine at the current moment; the injection rate of the injection molding machine in the injection molding process of the plastic box body of the junction box is adjusted. The production quality stability of the plastic box body of the junction box is improved.

Description

Technical Field

[0001] The present application relates to the field of injection molding control technology, and in particular to an injection molding control method and system for a plastic box body of a junction box. Background Art

[0002] The energy metering junction box is an indispensable dedicated component in the energy metering device. During the production process, the temperature, pressure and speed of the injection molding machine need to be precisely controlled to ensure that the polycarbonate material flows evenly during the injection molding process and fully fills the mold, thereby ensuring the dimensional accuracy and structural integrity of the junction box.

[0003] The injection molding machine's injection rate determines the quality of the plastic housing for junction boxes. Currently, most methods adjust the injection rate using a PID controller based on preset values. However, plastic pellets have a geometric structure, and the gaps between them when deposited inside the barrel are uneven, resulting in uneven temperature of the plastic melt inside the barrel. Traditional methods fail to fully consider the impact of the same injection rate on injection molding at different temperatures, making it difficult to precisely control the injection rate during production. This leads to unstable product quality and problems such as insufficient filling, surface defects, and dimensional accuracy deviations. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of this application is to provide a method and system for controlling the injection molding of a plastic box body of a junction box. The technical solutions adopted are as follows: The present invention provides a method for controlling injection molding of a plastic box body of a junction box, comprising the following steps: Obtain the injection speed of the injection molding machine and the temperatures at the front, middle, and back of the barrel during the injection molding process of the plastic box body of the junction box; Analyze the temperature deviation of different positions of the barrel at each moment, as well as the temperature difference between different positions of the barrel, to obtain the temperature flow deviation of the barrel at each moment; According to the degree of synchronization correlation between the temperature flow deviation of the barrel at each moment and the temperature change trend at each moment, combined with the degree of temperature change fluctuation at each moment, the melt flow fluctuation of the barrel is obtained; Based on the melt flow fluctuation of the barrel and the degree of deviation of the temperature at each position of the barrel, combined with the average level of the preset initial values ​​of the temperature at all positions of the barrel, the temperature interference adjustment coefficient of the injection molding machine injection rate is obtained; The injection rate target of the injection molding machine at the current moment is obtained through the temperature interference adjustment coefficient of the injection molding machine's injection rate, so as to adjust the injection rate of the injection molding machine during the injection molding process of the junction box plastic box body.

[0005] Preferably, the method for obtaining the temperature flow deviation of the barrel at each moment is: ; Where, represents the temperature flow deviation of the barrel at the i-th moment, represents the mean value of the distance between each temperature in the temperature flow vector at the i-th moment and the fitting straight line, Indicates the temperature difference between the front and the middle of the barrel at time i, Indicates the temperature difference between the middle and rear parts of the barrel at the i-th moment.

[0006] Preferably, the temperatures at the front, middle and back of the barrel at each moment are arranged in the order of back, middle and front of the barrel position to obtain the temperature flow vector at each moment, and the temperature flow vector is linearly fitted to obtain the fitting straight line of the barrel at each moment.

[0007] Preferably, the method for obtaining the melt flow fluctuation of the barrel is: Where, Indicates the melt flow fluctuation of the barrel. represents the number of elements in the fitted slope sequence, represents the jth element in the fitted slope sequence, represents the discreteness of all elements in the difference sequence, Indicates the preset standard change slope, || indicates the absolute value sign, Represents the normalization function.

[0008] Preferably, the slope of the fitting straight line of the temperature flow vector at each moment and the temperature flow deviation at each moment are arranged in time series to obtain a fitting slope sequence and a temperature flow deviation sequence, and the two sequences are normalized respectively, and the differences at the same position in the two sequences obtained after normalization are combined into a difference sequence.

[0009] Preferably, the method for obtaining the temperature interference adjustment coefficient of the injection rate of the injection molding machine is: Where, Indicates the temperature interference adjustment coefficient of the injection molding machine injection rate, Indicates the melt flow fluctuation of the barrel. Indicates the average value of the temperature preset initial value at all positions of the barrel. Indicates the temperature deviation value in the barrel.

[0010] Preferably, the melt temperature sequence of each position of the barrel is extracted, and the difference between the preset initial value of the temperature at each position of the barrel and all elements in the melt temperature sequence of the corresponding position of the barrel is calculated respectively, and the average of all calculated differences is used as the temperature deviation value in the barrel.

[0011] Preferably, the temperatures collected at each position of the barrel are normalized, and the normalized temperature data are arranged in time sequence to obtain a melt temperature sequence at each position of the barrel.

[0012] Preferably, the method for obtaining the injection rate target value of the injection molding machine at the current moment is: Where, Indicates the injection rate target of the injection molding machine at the current moment, v indicates the injection rate of the current injection molding machine, It is the temperature interference adjustment coefficient of the injection rate of the injection molding machine.

[0013] An embodiment of the present application also provides an injection molding control system for a plastic box body of a junction box, comprising a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of any one of the above-mentioned methods for controlling the injection molding of a plastic box body of a junction box are implemented.

[0014] As can be seen from the above, the injection molding control method and system for a junction box plastic box body provided by the present application have at least the following beneficial effects: This application accurately calculates the temperature interference adjustment coefficient of the injection rate and dynamically adjusts the injection rate of the injection molding machine based on this coefficient. This effectively solves problems such as insufficient filling, surface defects, and dimensional accuracy deviation caused by temperature fluctuations in the barrel. It can improve the production quality stability of the plastic box body of the junction box and ensure the high quality and consistency of the product. In this application, the injection rate is precisely controlled to avoid the problem of excessive or insufficient melt shear heat caused by an injection rate that is too high or too low, thereby reducing unnecessary energy waste. At the same time, stable injection rate and temperature control help to extend the service life of the injection molding machine, reduce equipment maintenance costs, and further optimize energy utilization efficiency in the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 This is a flow chart of the steps of the injection molding control method of the junction box plastic box body provided in this application. DETAILED DESCRIPTION

[0017] To further illustrate the technical means and effectiveness of this application to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail the specific implementation, structure, features, and effectiveness of a method and system for controlling the injection molding of a plastic enclosure for a junction box proposed in this application. In the following description, references to different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0018] Unless otherwise specified and limited, terms such as "comprises", "includes" or any other variants thereof are intended to cover non-exclusive inclusion, so that a circuit structure, article or device comprising a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the article or device comprising the element. In addition, the term "and\or" used herein includes any and all combinations of one or more related listed items. All technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs.

[0019] The following describes in detail a specific solution of an injection molding control method and system for a plastic box body of a junction box provided by the present application with reference to the accompanying drawings.

[0020] See also Figure 1 , which shows a flowchart of a method for controlling injection molding of a plastic box body of a junction box provided by one embodiment of the present application, including the following steps: Step 1: Obtain the injection speed of the injection molding machine and the temperatures at the front, middle, and rear positions of the barrel during the injection molding process of the plastic box body of the junction box.

[0021] In this embodiment, temperature sensors are evenly installed at the front, middle, and rear of the barrel to collect the temperatures at the front, middle, and rear of the barrel. A flow rate sensor is used to collect the injection speed of the injection molding machine. The data collection time is 1 minute and the frequency is 10 Hz.

[0022] In order to avoid the influence of environmental noise on the collected data, in this embodiment, the temperature data collected at each position of the barrel and the injection rate of the injection molding machine are normalized, and after denoising the data using mean filtering, the normalized and denoised data are arranged in the order of collection time, recorded as the melt temperature sequence at the front of the barrel, the melt temperature sequence at the middle of the barrel, the melt temperature sequence at the rear of the barrel, and the injection speed sequence. Among them, the process of mean filtering and normalization is a well-known technology, and the specific calculation steps are not repeated here. In this embodiment, an exponential normalization method is adopted. It should be noted that the preset temperature ranges of the front, middle, and rear of the barrel are 250°C-310°C, 240°C-280°C, and 230°C-250°C, respectively. In this embodiment, the preset initial values ​​of the temperature at the front, middle, and rear positions of the barrel are 280°C, 260°C, and 240°C, respectively.

[0023] Step 2: Analyze the temperature deviation of the barrel at different positions at each moment, as well as the temperature difference between different positions of the barrel, to obtain the temperature flow deviation of the barrel at each moment.

[0024] In the production of the plastic housing for a junction box, plastic granules are first dried and added to a hopper. The plastic is heated and melted in the barrel. The screw then rotates and stirs, evenly plasticizing it. The screw then retracts, pushing the melt into the mold cavity for rapid filling. Therefore, the barrel temperature should generally increase gradually from the rear end to the front end to ensure that the plastic maintains good fluidity upon entering the nozzle. Consequently, the temperature in the barrel is not uniform, but rather increases as it approaches the nozzle.

[0025] Extract temperature data from different locations within the barrel at the same time. Arrange the temperatures at the front, middle, and back of the barrel in that order, obtaining a temperature flow vector at each moment. This vector is used to characterize the temperature change within the barrel at that moment. The temperature at different locations within the barrel at the same moment should increase gradually from back to front. The more similar the temperature increase patterns at different moments, the more stable the melt flow within the barrel of the injection molding machine.

[0026] Therefore, the temperature flow vector at each moment in the barrel is used as the input of the linear least squares method to perform linear fitting to obtain the fitting line and the slope of the fitting line at each moment in the barrel, and the distance between each element in the temperature flow vector and the corresponding fitting line is obtained to characterize the flow state of the temperature in the barrel at each moment. The calculation of the linear least squares method is a well-known technology, and the specific calculation process will not be repeated here. Therefore, the temperature flow deviation of the barrel at each moment is calculated: ; Where, represents the temperature flow deviation of the barrel at the i-th moment, represents the mean value of the distance between each temperature in the temperature flow vector at the i-th moment and the fitting straight line, It represents the temperature difference between the front and the middle of the barrel at the i-th moment, that is, the difference between the third element and the second element in the temperature flow vector. It represents the temperature difference between the middle and rear parts of the barrel at the i-th moment, that is, the difference between the second element and the first element in the temperature flow vector.

[0027] When the temperature difference between the front, middle and back parts of the barrel is greater, it means that the temperature distribution of the molten plastic inside the barrel is more unbalanced, and the fluctuation between the temperature data is greater, which makes the temperature in the temperature flow vector at that moment deviate from the fitting curve. At the same time, the difference in temperature difference at different positions also increases, which makes the temperature flow deviation at that moment greater, indicating that the temperature change difference of the material in the barrel is greater, and the injection rate of the injection molding machine needs to be adjusted to improve the production quality of the plastic box body of the junction box.

[0028] Step 3: According to the degree of synchronization correlation between the temperature flow deviation of the barrel at each moment and the temperature change trend at each moment, combined with the degree of temperature change fluctuation at each moment, the melt flow fluctuation of the barrel is obtained.

[0029] Furthermore, in this embodiment, the calculated temperature flow deviations are arranged in chronological order to obtain a temperature flow deviation sequence. The fitted straight line slopes of the temperature flow vectors at different moments are arranged in chronological order to obtain a fitted slope sequence.

[0030] When the temperature inside the barrel increases evenly from back to front, it indicates that the injection molding machine is relatively balanced in material melting, allowing the plastic particles to flow effectively. The fluidity of the plastic melt at the rear end of the barrel is weak, while the fluidity of the plastic melt at the front end is strong, which helps to form a stable melt flow state during injection. In this case, the difference between the temperature flow deviation at different times is small. At the same time, the temperature difference at different locations at different times is small, that is, the slope of the fitted line of the temperature flow vector at different times is small. At the same time, the more synchronized the slope of the fitted line at different times is with the temperature flow deviation at that time, the more balanced the barrel is.

[0031] In order to eliminate the influence of dimension, a normalization function is used to normalize the temperature flow deviation sequence and the fitting slope sequence respectively. In this embodiment, the maximum-minimum value normalization is used. Furthermore, the difference sequence of the two normalized sequences is calculated to characterize the synchronization between the two sequences. The smaller the difference between the elements in the difference sequence, the higher the stability of the melt inside the barrel. Among them, the maximum-minimum value normalization and the calculation of the difference sequence are both well-known technologies, and the specific calculation steps are not repeated here. Thus, the melt flow fluctuation of the barrel is calculated: ; Where, Indicates the melt flow fluctuation of the barrel. represents the number of elements in the fitted slope sequence, represents the jth element in the fitted slope sequence, Indicates the dispersion of all elements in the difference sequence. Dispersion includes variance, standard deviation, coefficient of dispersion, coefficient of variation, etc. In this embodiment, variance is used as the calculation formula for dispersion; Indicates the preset standard change slope. Ideally, the temperature difference between the front and middle parts should be the same as the temperature difference between the middle and rear parts. Therefore, in this example, the standard change slope a is 1. || indicates the absolute value sign. represents a normalization function. In this embodiment, an exponential normalization function is adopted. The specific calculation of the exponential normalization function is a well-known technology and will not be described in detail in this embodiment.

[0032] When the temperature difference between different locations within the injection molding machine barrel varies significantly, the slope of the melt temperature fitting line at different locations at the same time will deviate from the standard variation slope. This reduces the synchronization between the temperature flow deviation and the data slope at different times, and in turn increases the dispersion of each element in the difference sequence between the normalized temperature flow deviation sequence and the fitted slope sequence. This leads to larger values ​​of the barrel melt flow fluctuation, indicating poor melt flow stability. Therefore, it is necessary to reduce the injection speed of the injection molding machine and reduce the shear heat of the plastic melt within the barrel to ensure a smooth, flawless surface of the injection-molded junction box plastic body and guarantee product quality.

[0033] Step 4: Based on the melt flow fluctuation of the barrel and the degree of deviation of the temperature at each position of the barrel, combined with the average level of the preset initial values ​​of the temperature at all positions of the barrel, the temperature interference adjustment coefficient of the injection molding machine injection rate is obtained.

[0034] Regarding the temperature of the plastic melt in the barrel, the more the temperature in the barrel exceeds the preset temperature value, the stronger the fluidity of the plastic melt, resulting in uneven cooling of the plastic melt in the mold cavity and unstable product dimensional accuracy. Reducing the injection speed can reduce the shear heat of the melt in the barrel and ensure that the temperature of the plastic melt injected into the mold remains at a stable state. Therefore, based on the melt flow fluctuation of the barrel and the degree of deviation of the temperature at each position of the barrel, combined with the average level of the preset initial value of the temperature at all positions of the barrel, the temperature interference adjustment coefficient of the injection molding machine injection rate is calculated: ; Where, Indicates the temperature interference adjustment coefficient of the injection molding machine injection rate, Indicates the melt flow fluctuation of the barrel. Indicates the average value of the temperature preset initial value at all positions of the barrel. Represents the temperature deviation value in the barrel. In this embodiment, the differences between the preset initial temperature value of each position of the barrel and all elements in the melt temperature sequence at the corresponding position of the barrel are calculated respectively, and the average of all calculated differences is used as the temperature deviation value in the barrel, which is used to characterize the deviation direction and amplitude of the temperature at each position of the barrel.

[0035] The more unstable the plastic melt in the barrel needs to be kept at its current position, the greater the difference between the current position and the preset temperature, which makes the melt flow fluctuation value of the barrel greater, and the greater the temperature deviation between the current temperature and the preset temperature, the greater the absolute value of the temperature interference adjustment coefficient of the injection molding machine injection rate, and the greater the adjustment ratio of the injection molding machine injection rate, so as to reduce the impact of temperature fluctuations on product quality, thereby ensuring the stability of the injection molding process and the high quality of the product.

[0036] Step 5: Obtain the injection rate target of the injection molding machine at the current moment through the temperature interference adjustment coefficient of the injection molding machine's injection rate, so as to adjust the injection rate of the injection molding machine during the injection molding process of the junction box plastic box body.

[0037] For the temperature interference adjustment coefficient of the injection molding machine injection rate calculated in the above steps, when it is greater than or equal to 0, it means that the temperature inside the injection molding machine barrel is lower than the preset target. Therefore, it is necessary to increase the injection rate to increase the shear heat of the plastic melt in the barrel, increase the temperature of the plastic melt in the barrel, increase the viscosity of the melt, and reduce insufficient filling or surface defects caused by excessive cooling, and vice versa. Therefore, in this embodiment, the injection rate target of the injection molding machine at the current moment is calculated by the temperature interference adjustment coefficient: Where, Indicates the injection rate target of the injection molding machine at the current moment, v indicates the injection rate of the current injection molding machine, It is the temperature interference adjustment coefficient of the injection rate of the injection molding machine.

[0038] Furthermore, in this embodiment, the injection rate target value of the injection molding machine at the current moment is calculated as the injection rate of the injection molding machine during the injection molding process of the junction box plastic box body, and the PID controller obtains the output signal of the PID controller based on the error between the current injection rate and the injection rate target value, and adjusts the injection rate of the current injection molding machine through the output signal. This allows the injection molding machine to dynamically adjust the injection rate, reduce product defects, optimize the filling effect, and thus improve production efficiency and product quality. It should be noted that the specific process of the PID controller adjusting according to the error is a well-known technology for those skilled in the art, and is not particularly limited in this embodiment and will not be described in detail.

[0039] Based on the same inventive concept as the above method, an embodiment of the present application also provides an injection molding control system for a plastic box body of a junction box, comprising a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of any one of the above-mentioned injection molding control methods for a plastic box body of a junction box are implemented.

[0040] It should be understood that the order in which the embodiments of the present application are presented is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. Furthermore, the foregoing descriptions of specific embodiments of this specification are provided. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order or sequential sequence shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0041] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

[0042] The above content is only an implementation method of the present application and is not intended to limit the scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the scope of protection of the present application.

Claims

1. A method for controlling injection molding of a plastic box body of a junction box, characterized in that: The following steps are involved: Obtain the injection speed of the injection molding machine and the temperatures at the front, middle, and back of the barrel during the injection molding process of the plastic box body of the junction box; Analyze the temperature deviation of different positions of the barrel at each moment, as well as the temperature difference between different positions of the barrel, to obtain the temperature flow deviation of the barrel at each moment; According to the degree of synchronization correlation between the temperature flow deviation of the barrel at each moment and the temperature change trend at each moment, combined with the degree of temperature change fluctuation at each moment, the melt flow fluctuation of the barrel is obtained; Based on the melt flow fluctuation of the barrel and the degree of deviation of the temperature at each position of the barrel, combined with the average level of the preset initial values ​​of the temperature at all positions of the barrel, the temperature interference adjustment coefficient of the injection molding machine injection rate is obtained; The injection rate target of the injection molding machine at the current moment is obtained through the temperature interference adjustment coefficient of the injection molding machine's injection rate, so as to adjust the injection rate of the injection molding machine during the injection molding process of the junction box plastic box body.

2. The method for controlling injection molding of a plastic box body of a junction box according to claim 1, wherein: The method for obtaining the temperature flow deviation of the barrel at each moment is: ； Where, represents the temperature flow deviation of the barrel at the i-th moment, represents the mean value of the distance between each temperature in the temperature flow vector at the i-th moment and the fitting straight line, It represents the temperature difference between the front and the middle of the barrel at the i-th moment, Indicates the temperature difference between the middle and rear parts of the barrel at the i-th moment.

3. The method for controlling injection molding of a plastic box body of a junction box according to claim 2, wherein: The temperatures at the front, middle and back of the barrel at each moment are arranged in the order of back, middle and front of the barrel position to obtain the temperature flow vector at each moment. The temperature flow vector is linearly fitted to obtain the fitting straight line of the barrel at each moment.

4. The method for controlling injection molding of a plastic box body of a junction box according to claim 3, wherein: The method for obtaining the melt flow fluctuation of the barrel is as follows: Where, Indicates the melt flow fluctuation of the barrel. represents the number of elements in the fitted slope sequence, represents the jth element in the fitted slope sequence, represents the discreteness of all elements in the difference sequence, Indicates the preset standard change slope, || indicates the absolute value sign, Represents the normalization function.

5. The method for controlling injection molding of a plastic box body of a junction box according to claim 4, wherein: The slope of the fitting line of the temperature flow vector at each moment and the temperature flow deviation at each moment are arranged in time series to obtain the fitting slope sequence and the temperature flow deviation sequence. The two sequences are normalized respectively, and the differences at the same position in the two sequences obtained after normalization are combined into a difference sequence.

6. The method for controlling injection molding of a plastic box body of a junction box according to claim 1, wherein: The method for obtaining the temperature interference adjustment coefficient of the injection rate of the injection molding machine is as follows: Where, Indicates the temperature interference adjustment coefficient of the injection molding machine injection rate, Indicates the melt flow fluctuation of the barrel. Indicates the average value of the temperature preset initial value at all positions of the barrel. Indicates the temperature deviation value in the barrel.

7. The method for controlling injection molding of a plastic box body of a junction box according to claim 6, wherein: Extract the melt temperature sequence at each position of the barrel, calculate the difference between the preset initial value of the temperature at each position of the barrel and all elements in the melt temperature sequence at the corresponding position of the barrel, and take the average of all calculated differences as the temperature deviation value in the barrel.

8. The method for controlling injection molding of a plastic box body of a junction box according to claim 7, wherein: The temperatures collected at each position of the barrel are normalized, and the normalized temperature data are arranged in time sequence to obtain the melt temperature sequence at each position of the barrel.

9. The method for controlling injection molding of a plastic box body of a junction box according to claim 1, wherein: The method for obtaining the injection rate target value of the injection molding machine at the current moment is: Where, Indicates the injection rate target of the injection molding machine at the current moment, v indicates the injection rate of the current injection molding machine, It is the temperature interference adjustment coefficient of the injection rate of the injection molding machine.

10. An injection molding control system for a plastic box body of a junction box, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the injection molding control method for a plastic box body of a junction box as described in any one of claims 1 to 9 are implemented.

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