Automatic encapsulation process virtual cloud picture display method based on digital twinning

Abstract

The invention discloses an automatic encapsulation process virtual cloud picture display method based on digital twinning. The method specifically comprises the following steps: step 1, acquiring encapsulation data; 2, calculating the volume fraction of the potting material according to the potting data collected in the step 1; and step 3, obtaining an encapsulation process cloud picture according to the volume fraction calculated in the step 2, and monitoring whether bubbles are generated in the encapsulation process according to the encapsulation process cloud picture. The filling and sealing process can be monitored in real time, and the rejection rate is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of potting material potting process monitoring, and relates to a virtual cloud map display method for an automated potting process based on digital twins. Background Art

[0002] Epoxy potting is a commonly used protection method in precision electronic products. Epoxy potting materials can protect circuit boards and electrical components on them from damage caused by mechanical shock, high temperature and high pressure. The current epoxy potting is generally mixed with epoxy materials and curing agents, and then flows into the shell of electronic products through a nozzle to wrap the circuit board installed in the shell and the electrical components on it. After curing, it plays a protective role. However, during the potting process, if the potting process parameters are improper, it is easy to cause air pockets in the potting materials of electronic products. The existence of these air pockets, if they are position sensitive or large in size, will greatly reduce the protection ability of the potting material, making it difficult for electronic products to effectively realize their functions. Therefore, in the process of automated potting, if it is possible to monitor in real time whether there is a possibility of bubbles in the potting process, it can effectively prevent the occurrence of a large number of potting waste products and ensure the potting quality. However, since the potting material is generally poured into the outer shell of the electronic product, and the outer shell of the electronic product is an opaque shell, it is difficult to directly observe the potting material inside. Summary of the invention

[0003] The purpose of the present invention is to provide a virtual cloud map display method for an automated potting process based on digital twins, which can monitor the potting process in real time and reduce the scrap rate.

[0004] The technical solution adopted by the present invention is a virtual cloud diagram display method for an automated potting process based on digital twins, which specifically includes the following steps:

[0005] Step 1, collecting potting data;

[0006] Step 2, calculating the volume fraction of the potting material according to the potting data collected in step 1;

[0007] Step 3, obtaining a cloud map of the filling process according to the volume fraction calculated in step 2, and monitoring whether bubbles are generated during the filling process according to the cloud map of the filling process.

[0008] The present invention is also characterized in that:

[0009] The specific process of step 1 is: the upper computer server sends a potting start command to the lower computer PLC control system, the lower computer PLC control system controls the potting needle valve to open, and the potting material will flow into the potting product through the potting head. At this time, the electronic balance will obtain the amount of potting material poured into the potting product, and transmit the amount of potting material to the lower computer PLC control system, and then transmit it to the upper computer server through the lower computer PLC control system.

[0010] The specific process of step 2 is as follows: when the host computer server issues a command to start potting, a virtual demonstration system interface of a potting process based on digital twins is displayed on the display screen of the host computer server, and the epoxy material is injected into the shell of the potting workpiece through the potting head on the virtual demonstration system interface of the potting process based on digital twins. The time to start potting is written in the potting start time display text box in the virtual demonstration system. At the same time, the host computer server receives the potting amount data sent by the electronic balance every 0.5 seconds, and records it in the potting amount text box on the potting process virtual demonstration system interface based on digital twins, and on the other hand, On the one hand, by comparing with the previous potting volume data, it is determined whether potting is still in progress. If the current potting volume value is greater than the previous potting volume value, it indicates that potting is in progress. If the current potting volume value is equal to the previous potting volume value, it means that potting is stopped. When potting is in progress, the volume fraction of the potting material in the time period relative to the start time of the potting time is calculated, and the coordinate values ​​of each grid point are combined to form a matrix of the volume fraction of the potting material in the entire flow field. The corresponding potting process cloud map is displayed on the potting process virtual demonstration system interface based on digital twins through the Python display program SCATTER command.

[0011] In step 2, the volume fraction matrix calculation process of the potting material is:

[0012] The volume fraction U(x,t i ) is recorded as a set of snapshots, then the volume fraction snapshots at different times constitute the instantaneous volume fraction matrix U(x,t), as shown in the following formula (1):

[0013]

[0014] Where: x represents the position vector, t represents the time, is the average volume fraction matrix, and U′(x, t) is the pulsating volume fraction matrix.

[0015] In step 2, the separation of variables method is used to decompose the pulsation volume fraction matrix U′(x, t) into two independent parts in time and space as shown in the following formula (2):

[0016]

[0017] In the formula, is the POD spatial mode, a i (t) is the modal coefficient corresponding to each mode, also called the time coefficient.

[0018] In step 2, the first N modes in the infinite series are taken to approximate the flow field reconstruction, that is:

[0019]

[0020] In the formula, represents the approximate deviation matrix of the pulsation volume fraction, and N is the total number of modes intercepted;

[0021] Then the instantaneous volume fraction matrix U(x,t) is expressed as:

[0022]

[0023] At the same time, the eigenorthogonal decomposition space modes must satisfy the mathematical properties of mutual orthogonality, namely:

[0024]

[0025] Find an optimal set of POD bases The pulsating velocity value at any node of the construction model at any time is expressed as a linear combination of POD bases, that is:

[0026]

[0027] Formula (6) is written as the following formula (7) in matrix form:

[0028]

[0029] In step 2, let R = U′U′ T , R is a real symmetric matrix, and its eigenvalue λ is obtained through R i and the corresponding eigenvector

[0030]

[0031] Where M is the number of eigenvalues ​​of the covariance matrix R, and the γ value represents the energy proportion of the eigenvalue set retained after modal truncation in the original modal set.

[0032] In step 2, the instantaneous volume fraction matrix of the encapsulating material at time t is determined as:

[0033]

[0034] The beneficial effect of the present invention is that the present invention uses advanced computer simulation software FLUENT to simulate the potting process under different process parameters to obtain the corresponding potting material volume fraction cloud map. Through the developed algorithm, these cloud maps are discretized by time and integrated into corresponding calculation formulas, and the current volume fraction point values ​​can be obtained in real time through the collected potting amount, and displayed in the form of a color cloud map through a corresponding method, thereby providing obvious visual image data for the operator to judge whether there is a potting defect, ensuring the operator's correct judgment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a monitoring system diagram based on digital twins adopted in the virtual cloud diagram display method of the automated potting process based on digital twins of the present invention;

[0036] Figure 2 It is a three-dimensional image of the shell of the potted product in the virtual cloud image display method of the automated potting process based on digital twin of the present invention;

[0037] Figure 3 It is a virtual demonstration system interface of a potting process based on digital twins in a virtual cloud diagram display method of an automated potting process based on digital twins of the present invention;

[0038] Figure 4 It is the calculation domain of the simulated potting product model in the virtual cloud diagram display method of the automated potting process based on digital twin of the present invention;

[0039] Figure 5 It is a cloud map of the instantaneous volume fraction of the potting material drawn by using the calculated instantaneous volume fraction matrix in the virtual cloud map display method of the automated potting process based on digital twin of the present invention;

[0040] Figure 6 It is a cloud map of the potting process obtained by simulation for calculating in the virtual cloud map display method of the automated potting process based on digital twin of the present invention;

[0041] Figure 7 It is a cloud map of the potting process divided into three sections in the virtual cloud map display method of the automated potting process based on digital twins of the present invention;

[0042] Figure 8(a) to Figure 8(j) These are 10 cloud maps of the filling process arranged according to time steps in the virtual cloud map display method of the automated filling process based on digital twins of the present invention.

[0043] In the figure, 1. upper computer server, 2. lower computer PLC control system, 3. physical mechanical system, 4. potting needle valve, 5. potting head, 6. electronic balance, 7. potting product, 12. potting material, 13. filling port, 14. potting product shell. DETAILED DESCRIPTION

[0044] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] Example 1

[0046] The virtual cloud map display method of the automated potting process based on digital twins is mainly used to monitor the potting process of potting products. It can display the situation of the potting material entering the potting product and the interaction with the gas in the potting process in real time through cloud maps, so that the operator can judge possible problems in real time. Figure 1 As shown, the whole monitoring system includes three parts: physical mechanical system 3, upper computer server 1 and lower computer PLC control system 2. The physical mechanical system 3 includes a potting needle valve 4 and a potting head 5 arranged below the potting needle valve 4. A potting product 7 to be potted is placed below the potting head 5, and the potting product 7 is placed on an electronic balance 6. Figure 2 It is a three-dimensional image of the outer shell of the potted product in the virtual cloud image display method of the automated potting process based on digital twinning of the present invention.

[0047] Example 2

[0048] The present invention provides a virtual cloud diagram display method for an automated potting process based on digital twins, which specifically comprises the following steps:

[0049] Step 1, data collection. Specifically, in the actual physical system, the upper computer server 1 sends a potting start command to the lower computer PLC control system 2, and the lower computer PLC control system 2 controls the potting needle valve 4 in the physical mechanical system 3 to open, and the potting material will flow into the potting product 7 through the potting head 5. At this time, the electronic balance 6 will obtain the amount of material poured into the potting product 7, and transmit the corresponding value to the lower computer PLC control system 2, and then transmit it to the upper computer server 1 through the lower computer PLC control system 2.

[0050] Step 2: Process the data and display it in the virtual system. Specifically, when the host server 1 issues a command to start the potting, the command is also received by the host server 1, so that the virtual demonstration system interface of the potting process based on the digital twin is displayed on the display screen of the host server 1 (such as Figure 3 As shown in FIG. 1 , the epoxy material (potting material 12) is injected into the potting product housing 14 through the filling port 13 in the potting head 5 on the virtual demonstration system interface of the potting process based on the digital twin ( Figure 4is the calculation domain of the simulated potting product model), and the potting start time is written in the potting start time display text box in the virtual demonstration system; at the same time, the upper computer server 1 receives the potting volume data sent by the electronic balance 6 every 0.5 seconds, and records it in the potting volume text box on the potting process virtual demonstration system interface based on the digital twin. On the other hand, it compares it with the previous potting volume data to determine whether it is still potting. If the current potting volume value is greater than the previous potting volume value, it indicates that potting is in progress. If the current potting volume value is equal to the previous potting volume value, it means that potting is stopped; if it is determined that potting is in progress, the volume fraction of the potting material in the time period relative to the start time of the potting time is calculated at this time, and the coordinate values ​​of each grid point are combined to form a matrix of the volume fraction of the potting material in the entire flow field. The corresponding potting process cloud map is displayed on the interface through the Python display program SCATTER (C) command. If the potting volume is compared to the amount to be potted, the potting is stopped, and the end time will also be displayed in the potting end text box of the monitoring interface, see Figure 5 .

[0051] Example 3

[0052] The volume fraction calculation process of the potting material is as follows: the snapshot POD method is used. That is, the potting process under certain potting process parameters is simulated using Fluent software to obtain the volume fraction cloud map of the corresponding potting material poured into the potting product, see Figure 6 In order to reduce the number of calculation points and facilitate observation of the internal potting conditions of the potting products, the potting process cloud map is evenly divided into three sections. Figure 7 .

[0053] Example 4

[0054] The volume fraction U(x,t i ) is recorded as a set of snapshots. Where i represents the time sequence (here, since the cloud map is to be extracted according to the time interval, the volume fraction cloud map of material A at that moment is hierarchical, so t is used i Instead of t to represent different times). The volume fraction snapshots at different times form the instantaneous volume fraction matrix U(x,t). x represents the position vector and t represents the time. The volume fraction snapshot can be expressed as the average volume fraction matrix and the pulsation volume fraction matrix U′(x,t), that is:

[0055]

[0056] Using the separation of variables method, the pulsation volume fraction matrix is ​​decomposed into two parts that are independent of each other in time and space, that is, a series of coefficients a that are only related to time i(t) and a series of spatial orthogonal basis functions The product of:

[0057]

[0058] In the formula, is the POD space mode, also known as the POD basis (vector); a i (t) is the modal coefficient corresponding to each mode, also called the time coefficient.

[0059] Example 5

[0060] The core idea of ​​POD is to extract the main features of the system in the random change process, and use a small number of optimal main features to reconstruct the complex physical process. Therefore, generally only the first N modes in the infinite series are taken for approximate reconstruction of the flow field, that is:

[0061]

[0062] In the formula, represents the pulsation volume fraction approximation deviation matrix, and N is the total number of modes intercepted.

[0063] Then the instantaneous volume fraction matrix is ​​expressed as:

[0064]

[0065] At the same time, the eigenorthogonal decomposition space modes must satisfy the mathematical properties of mutual orthogonality, namely:

[0066]

[0067] Here we can find an optimal set of POD bases (in is a column vector), i = 1~N, so that the pulsation velocity value at any node of the construction model at any time is expressed as a linear combination of POD bases, that is:

[0068]

[0069] Formula (6) is written as the following formula (7) in matrix form:

[0070]

[0071] Let R=U′U′ T From linear algebra knowledge, we know that R is a real symmetric matrix, and its eigenvalue λ can be calculated through R i and its corresponding eigenvector

[0072]

[0073] In the formula, M is the number of eigenvalues ​​of the covariance matrix R, and the γ value represents the energy proportion of the intrinsic orthogonal mode set retained after modal truncation in the original mode set. Usually γ ≥ 99%, and the value of γ can be adjusted according to the specific research problem. Therefore, the instantaneous volume fraction matrix of the encapsulation material at time t can be determined as:

[0074]

[0075] Example 6

[0076] For example Figure 1 The potting method shown in the figure is used for potting simulation, and the potting product parts are as follows Figure 2 By performing Fluent's encapsulation process computational domain modeling, we obtain Figure 4 The calculation domain is shown, and then the corresponding conditions are set. The phase flow model is set as VOF model, the viscosity model is k-omega SST model, the density of the potting material is 1119kg / m^3, the viscosity is 2.466kg / (m*s), the pressure inlet is 0.001MPa, the potting is pulsating, the potting period is 0.4s, the interval is 0.6s, and the potting is cyclic. The solution method adopts the PISO method, and the potting inlet is set as a cylindrical inlet with a diameter of 1.5mm. Figure 3 It is the designed monitoring interface. Figure 5 is the calculation result. Extract the potting process cloud diagram at different time points according to the time step, see Figure 8(a)-Figure 8(j) The smaller the extraction step size, the more accurate it is. Here, the step size is selected as 1 second. Figure 8(a)-Figure 8(j) The figure shows the cloud diagram of the filling process at 10 different time points, that is, FIG8(a) is the filling simulation cloud diagram after 1 second of filling, FIG8(b) is the filling simulation cloud diagram after 2 seconds of filling, and so on. FIG8(j) is the filling simulation cloud diagram after 10 seconds of filling.

Claims

1. A virtual cloud diagram display method for an automated potting process based on digital twins, characterized in that: The specific steps include: Step 1, collecting potting data; Step 2, calculating the volume fraction of the potting material according to the potting data collected in step 1; Step 3, obtaining a cloud map of the filling process according to the volume fraction calculated in step 2, and monitoring whether bubbles are generated during the filling process according to the cloud map of the filling process.

2. The method for displaying a virtual cloud diagram of an automated potting process based on digital twins according to claim 1, characterized in that: The specific process of step 1 is as follows: a potting start command is sent to the lower computer PLC control system (2) through the upper computer server (1), and the lower computer PLC control system (2) controls the potting needle valve (4) to open, so that the potting material flows into the potting product (7) through the potting head (5). At this time, the electronic balance (6) obtains the amount of potting material poured into the potting product (7), and transmits the amount of potting material to the lower computer PLC control system (2), and then transmits it to the upper computer server (1) through the lower computer PLC control system (2).

3. The method for displaying a virtual cloud diagram of an automated potting process based on digital twins according to claim 2 is characterized in that: The specific process of step 2 is as follows: when the host computer server (1) issues a command to start potting, a potting process virtual demonstration system interface based on digital twins is displayed on the display screen of the host computer server (1); the epoxy material is injected into the potting workpiece shell through the potting head (5) on the virtual demonstration system interface based on digital twins; the potting start time is written in the potting start time display text box in the virtual demonstration system; at the same time, the host computer server (1) receives the potting amount data sent by the electronic balance (6) every 0.5 seconds, and records the potting amount on the virtual demonstration system interface based on digital twins. In the sealing amount text box, on the other hand, by comparing with the previous sealing amount data, it is determined whether potting is still in progress. If the current potting amount value is greater than the previous potting amount value, it indicates that potting is in progress. If the current potting amount value is equal to the previous potting amount value, it means that potting is stopped. When potting is in progress, the volume fraction of the potting material in the time period relative to the start time of the potting time is calculated, and the coordinate values ​​of each grid point are combined to form a matrix of the volume fraction of the potting material in the entire flow field. The corresponding potting process cloud map is displayed on the potting process virtual demonstration system interface based on digital twins through the Python display program SCATTER command.

4. The method for displaying a virtual cloud diagram of an automated potting process based on digital twins according to claim 3 is characterized in that: In step 2, the volume fraction matrix calculation process of the potting material is: The volume fraction U(x,t i ) is recorded as a set of snapshots, then the volume fraction snapshots at different times constitute the instantaneous volume fraction matrix U(x,t), as shown in the following formula (1): Where: x represents the position vector, t represents the time, is the average volume fraction matrix, and U′(x, t) is the pulsating volume fraction matrix.

5. The method for displaying virtual cloud images of the automated potting process based on digital twins according to claim 4 is characterized in that: In step 2, the separation of variables method is used to decompose the pulsation volume fraction matrix U′(x, t) into two parts that are independent of each other in time and space as shown in the following formula (2): In the formula, is the POD spatial mode, a i (t) is the modal coefficient corresponding to each mode, also called the time coefficient.

6. The method for displaying virtual cloud images of the automated potting process based on digital twins according to claim 5 is characterized in that: In step 2, the first N modes in the infinite series are taken to perform approximate reconstruction of the flow field, that is: In the formula, represents the approximate deviation matrix of the pulsation volume fraction, and N is the total number of modes intercepted; Then the instantaneous volume fraction matrix U(x,t) is expressed as: At the same time, the eigenorthogonal decomposition space modes must satisfy the mathematical properties of mutual orthogonality, namely: Find an optimal set of POD bases The pulsating velocity value at any node of the construction model at any time is expressed as a linear combination of POD bases, that is: Formula (6) is written as the following formula (7) in matrix form:

7. The method for displaying virtual cloud images of an automated potting process based on digital twins according to claim 5 is characterized in that: In step 2, let R = U′U′ T , R is a real symmetric matrix, and its eigenvalue λ is obtained through R i and the corresponding eigenvector Where M is the number of eigenvalues ​​of the covariance matrix R, and the γ value represents the energy proportion of the eigenvalue set retained after modal truncation in the original modal set.

8. The method for displaying virtual cloud images of an automated potting process based on digital twins according to claim 6 is characterized in that: In step 2, the instantaneous volume fraction matrix of the encapsulation material at time t is determined as:

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