Virtual cloud display method for automated potting process based on digital twin

Abstract

The present invention discloses a method for displaying a virtual cloud map of an automated potting process based on digital twins. The method specifically includes the following steps: Step 1: Collect potting data; Step 2: Calculate the volume fraction of the potting material based on the potting data collected in Step 1; Step 3: Obtain a potting process cloud map based on the volume fraction calculated in Step 2, and monitor the potting process for bubbles based on the potting process cloud map. The present invention can monitor the potting process in real time and reduce the scrap rate.

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 common protection method used in precision electronic products. It protects circuit boards and their components from damage caused by mechanical shock, high temperatures, and high pressures. Current epoxy potting methods typically involve mixing epoxy and a curing agent, then pouring the mixture through a nozzle into the electronic product's housing, enveloping the mounted circuit board and its components. After curing, the material provides protection. However, improper potting parameters can easily lead to the formation of air pockets within the potting material. These air pockets, if located sensitively or large in size, can significantly reduce the potting material's protective properties, hindering the effective functioning of the electronic product. Therefore, real-time monitoring of air bubbles during automated potting processes can effectively prevent the occurrence of large quantities of potting waste and ensure potting quality. However, because the potting material is typically poured into the electronic product's housing, which is opaque, direct observation of the potting material inside is difficult. Summary of the Invention

[0003] The purpose of the present invention is to provide a virtual cloud map display method for the 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 method for displaying a virtual cloud diagram of 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 based on the potting data collected in step 1;

[0007] Step 3: Obtain a cloud map of the potting process based on the volume fraction calculated in step 2, and monitor whether bubbles are generated during the potting process based on the cloud map.

[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 potted 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 the command to start potting, the virtual demonstration system interface of the potting process based on digital twin is displayed on the display screen of the host computer server, and the epoxy material is injected into the potting workpiece shell through the potting head on the virtual demonstration system interface of the potting process based on digital twin. The time of starting 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 twin, 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 network point are combined to form a matrix of the volume fraction of the potting material in the entire flow field. The Python display program SCATTER command is used to display the corresponding potting process cloud map on the potting process virtual demonstration system interface based on digital twins.

[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, and 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] Where, 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 perform approximate reconstruction of the flow field, that is:

[0019]

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

[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] Finding 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 the POD basis, that is:

[0026]

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

[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 eigennormal mode set retained after modal truncation in the original mode set.

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

[0033]

[0034] The present invention has the beneficial effect of using the advanced computer simulation software FLUENT to simulate the potting process under different process parameters, thereby obtaining corresponding potting material volume fraction cloud maps. The developed algorithm discretizes these cloud maps by time and integrates them into corresponding calculation formulas. The current volume fraction values ​​at each point can be obtained in real time based on the collected potting volume. These values ​​are then displayed in the form of a color cloud map using a corresponding method, thereby providing operators with clear visual image data to determine whether potting defects exist, ensuring that the operator makes accurate judgments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a monitoring system diagram based on digital twins used 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 using the calculated instantaneous volume fraction matrix in the virtual cloud map display method of the automated potting process based on digital twins of the present invention;

[0040] Figure 6 It is a cloud map of the potting process obtained by simulation for calculation 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. Host computer server, 2. Slave 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. Potting port, 14. Potting product shell. DETAILED DESCRIPTION

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

[0045] Example 1

[0046] The present invention is based on the virtual cloud map display method of the automated potting process of digital twins, which 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 entire monitoring system consists of three major components: a physical mechanical system 3, a host computer server 1, and a slave computer PLC control system 2. The physical mechanical system 3 includes a potting needle valve 4 and a potting head 5 disposed below the potting needle valve 4. Below the potting head 5 is a potting product 7 to be potted, which is placed on an electronic balance 6. 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 twins 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 includes the following steps:

[0049] Step 1: Data collection. Specifically, in the actual physical system, the host server 1 sends a potting start command to the slave PLC control system 2. The slave PLC control system 2 then controls the potting needle valve 4 in the physical mechanical system 3 to open, causing the potting material to flow through the potting head 5 into the potted product 7. At this point, the electronic balance 6 determines the amount of material poured into the potted product 7 and transmits the corresponding value to the slave PLC control system 2. This value is then transmitted to the host server 1 through the slave PLC control system 2.

[0050] Step 2: Process the data and display it in the virtual system. Specifically: when the host server 1 issues the potting start command, the command is also obtained 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), the epoxy material (potting material 12) is injected into the potting product shell 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 amount data sent by the electronic balance 6 every 0.5 seconds, and records it in the potting amount 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 amount data to determine whether it is still potting. 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; if it is determined that potting is in progress, the volume fraction of the potting material in the time period relative to the potting time start time is calculated, and the coordinate values ​​of each network 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 amount 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 calculation process of the volume fraction 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 diagram of the corresponding potting material poured into the potting product. Figure 6 In order to reduce the number of calculation points and to facilitate observation of the internal potting situation of the potting product, 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 at the time interval to obtain the volume fraction cloud map of material A at that moment, which is hierarchical, t is used i Instead of t to represent different times). The volume fraction snapshots at different times constitute 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 sum of 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 spatially orthogonal basis functions The product of:

[0057]

[0058] Where, 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 to approximate the flow field reconstruction, that is:

[0061]

[0062] Where, represents the approximate deviation matrix of the pulsation volume fraction, and N is the total number of truncated modes.

[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 a set of optimal POD bases (in is a column vector), i = 1 to N, so that the pulsating velocity value at any node of the constructed model at any time is expressed as a linear combination of the POD basis, that is:

[0068]

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

[0070]

[0071] Let R=U′U′ T From the knowledge of linear algebra, 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] Where 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. γ is usually taken as ≥ 99%, and the value of γ can be adjusted according to the specific research question. Therefore, the instantaneous volume fraction matrix of the potting 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 As shown. By performing Fluent's encapsulation process calculation domain modeling, we can obtain Figure 4 The calculation domain is shown, and the corresponding conditions are set. The phase flow model is set to the VOF model, the viscosity model is the k-omega SST model, the potting material density is 1119 kg / m^3, the viscosity is 2.466 kg / (m*s), the pressure inlet is 0.001 MPa, the potting is pulsating, the potting period is 0.4 seconds, the interval is 0.6 seconds, and the potting is cyclic. The solution method is the PISO method, and the potting inlet is set to a cylindrical inlet with a diameter of 1.5 mm. Figure 3 It is the monitoring interface designed. 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 cloud diagrams of the filling process at 10 different time points are shown, 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 by: The specific steps include: Step 1, collecting potting data; Step 2, calculating the volume fraction of the potting material based on the potting data collected in step 1; 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 twin is displayed on the display screen of the host computer server (1), epoxy material is injected into the potting workpiece shell through the potting head (5) on the potting process virtual demonstration system interface based on digital twin, 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 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 potting process virtual demonstration system interface based on digital twin. In the quantity text box, on the other hand, by comparing with the previous potting quantity data, it is determined whether potting is still in progress. If the current potting quantity value is greater than the previous potting quantity value, it indicates that potting is in progress. If the current potting quantity value is equal to the previous potting quantity value, it indicates 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 potting material volume fraction of 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; Step 3: Obtain a cloud map of the potting process based on the volume fraction calculated in step 2, and monitor whether bubbles are generated during the potting process based on the cloud map.

2. The method for displaying a virtual cloud image 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, and 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 image of an automated potting process based on digital twins according to claim 1, characterized in that: In step 2, the volume fraction matrix calculation process of the potting material is as follows: the volume fraction on the potting process cloud at a certain moment Recorded as a set of snapshots, the volume fraction snapshots at different times constitute the instantaneous volume fraction matrix , as shown in the following formula (1): （1） in: represents the position vector, t represents the time, is the average volume fraction matrix, is the pulsation volume fraction matrix.

4. The method for displaying a virtual cloud image of an automated potting process based on digital twins according to claim 3 is characterized in that: In step 2, the separation of variables method is used to convert the pulsation volume fraction matrix It is decomposed into two independent parts in time and space as shown in the following formula (2): （2） Where, is the POD space mode, is the modal coefficient corresponding to each mode, also called the time coefficient.

5. The method for displaying a virtual cloud image of an automated potting process based on digital twins according to claim 4 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, namely: （3） Where, represents the pulsating volume fraction approximation deviation matrix, N is the total number of modes intercepted; Then the instantaneous volume fraction matrix Expressed as: （4） At the same time, the eigenorthogonal decomposition space modes must satisfy the mathematical properties of mutual orthogonality, namely: （5） Finding an optimal set of POD bases ， , , , so that the pulsating velocity value at any node of the construction model at any time can be expressed as a linear combination of POD bases, that is: （6） Formula (6) is written as the following formula (7) in matrix form: （7） in, Indicates the modal coefficient corresponding to the Nth-order mode.

6. The method for displaying a virtual cloud image of an automated potting process based on digital twins according to claim 4 is characterized in that: In step 2, let ，R is a real symmetric matrix, and its eigenvalue is found through R and the corresponding eigenvector : （8） Where M is the number of eigenvalues ​​of the covariance matrix R, The value represents the energy ratio of the eigenvalue set retained after modal truncation in the original modal set.

7. The method for displaying a virtual cloud image of an automated potting process based on digital twins according to claim 5, characterized in that: In step 2, the instantaneous volume fraction matrix of the encapsulating material at time t is determined as: （9） in, is the feature vector.

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