A simulation method for temperature and stress fields of molds with additive manufacturing conformal temperature-controlled runners based on the finite element method.

Abstract

This invention provides a simulation method for the temperature and stress fields of a mold containing additive manufacturing conformal temperature-controlled flow channels based on the finite element method. The method includes: 1) designing an internal temperature-controlled flow channel model using 3D modeling software to establish an overall mold model; 2) importing the overall mold model established in step 1) into simulation analysis software, setting material parameters, and meshing; 3) setting the contact conditions of the material surface and the internal temperature-controlled flow channels, simulating and calculating the overall temperature distribution of the mold during use, and obtaining temperature field data; 4) importing the temperature field distribution data obtained in step 3) into the simulation analysis software, modifying parameters, simulating and calculating the overall stress distribution of the mold during use, and obtaining stress field data; 5) analyzing the temperature field data obtained in step 3) and the stress field data obtained in step 4) to determine whether the internal temperature-controlled flow channel model needs optimization, thereby obtaining a qualified mold model containing temperature-controlled flow channels.

Description

Technical Field

[0001] This invention belongs to the field of die casting mold technology, specifically relating to a simulation method for the temperature and stress fields of a mold containing additively manufactured conformal temperature-controlled flow channels based on the finite element method. Background Technology

[0002] China is a manufacturing powerhouse, and molds, as the "mother of industry," have played and continue to play a significant role in its journey towards becoming a "manufacturing superpower." In everyday electronic products and the rapidly developing automotive industry, 60% to 90% of the parts rely on molds for forming. The level of mold manufacturing has become an important indicator of a country's product manufacturing level, largely determining product quality and R&D capabilities. Since the beginning of the 21st century, my country's mold industry has experienced robust growth, with its total domestic mold output ranking second in the world, second only to the United States, making it a veritable mold superpower.

[0003] When a mold is in use, molten metal enters the mold and fills the cavity under gravity. During the forming process, the cavity surface is in direct contact with the molten metal, with instantaneous temperatures reaching over 600°C and maintained for 5-10 seconds. The mold then cools down along with the molten metal until the metal solidifies to form the product. During its service life, the mold undergoes tens of thousands of thermal cycles. Rapid heating and cooling generate stress within the mold, and this accumulated stress leads to fatigue cracks. Crack propagation causes mold failure, significantly reducing its lifespan. Therefore, the key to improving mold lifespan lies in controlling the product cooling rate and mold temperature during production. Adding temperature-controlled runners inside the mold can increase the cooling rate of the molten metal while simultaneously reducing the mold surface temperature. Traditional temperature-controlled runner designs, limited by processing methods, often use simple point cooling and straight runners, which are ineffective in reducing mold surface temperature, resulting in minimal improvement in mold lifespan. Additive manufacturing, however, allows for the direct forming of complex solids. This process allows for the creation of complex, conformal temperature-controlled runners within the mold, achieving efficient surface cooling and significantly extending mold lifespan. However, due to the complexity of conformal temperature control channels, if the temperature control channel design of the mold is unreasonable, the following problems will occur during the continuous production of the mold: if the distance between the temperature control channel and the mold surface is too close, the mold will fail due to impact during service; if the distance between the temperature control channel and the mold surface is too far, the cooling effect of the temperature control channel will decrease, and the long-term service life of the mold will be reduced; if there are design defects inside the temperature control channel, the temperature control channel will be the first to be damaged during the service of the mold, reducing the overall life of the mold.

[0004] In conclusion, a new approach is urgently needed to address the shortcomings of existing technologies for developing internal temperature-controlled flow channels in die-casting molds. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies for developing internal temperature-controlled flow channels in die-casting molds, and to provide a simulation method for the temperature and stress fields of molds containing additively manufactured conformal temperature-controlled flow channels based on the finite element method, namely, a method for analyzing the temperature and stress fields during cold and hot cycling.

[0006] To achieve the above objectives, the technical solution provided by this invention is:

[0007] A method for simulating the temperature and stress fields of a mold containing an additively manufactured conformal temperature-controlled flow channel, based on the finite element method, is characterized by comprising the following steps:

[0008] 1) Use 3D modeling software to design the internal temperature control flow channel model of the mold and establish the overall mold model;

[0009] 2) Import the overall mold model established in step 1) into the simulation analysis software Abaqus, set the material parameters, and generate the mesh;

[0010] 3) Set the contact conditions between the material surface and the internal temperature-controlled flow channel, simulate and calculate the overall temperature distribution during mold use, and obtain temperature field data;

[0011] 4) Import the temperature field data obtained in step 3) into the Load module of the simulation analysis software, set it as the loading condition of the mold, modify the parameters, transfer the temperature data into stress simulation, simulate and calculate the overall stress distribution of the mold when it is in use, and obtain stress field data.

[0012] 5) Analyze the temperature field data obtained in step 3) and the stress field data obtained in step 4), observe whether the model shows a temperature exceeding the allowable temperature range of the material and whether the model as a whole shows stress concentration, and determine whether it is necessary to optimize the internal temperature control flow channel model of the mold.

[0013] If the requirements are met, a qualified mold model containing a temperature-controlled flow channel will be obtained;

[0014] If the requirements are not met, return to step 1) to further adjust the internal temperature control channel model of the mold, rebuild the overall mold model, perform joint simulation of temperature field and stress field, and perform iterative analysis and inspection of the mold until the requirements are met, and obtain a qualified mold model containing temperature control channels.

[0015] If the temperature exceeds the allowable temperature of the material or the stress exceeds the allowable stress requirement of the material, the 3D model of the product needs to be modified and the 3D model of the temperature control channel inside the mold needs to be reconstructed. After recalculation, check whether the temperature control channel meets the cooling requirements and whether the model stress is lower than the allowable stress. Repeat the cyclic analysis and inspection of the mold until a qualified mold model containing the temperature control channel is obtained.

[0016] The obtained qualified mold model containing temperature-controlled flow channels is exported for mold development.

[0017] As can be seen, this invention performs joint simulation of temperature and stress fields, starting with the design of a mold model containing an internal temperature-controlled flow channel based on these fields. After the temperature field calculation is completed, the temperature field data is saved, and the mold parameter settings are modified. The temperature field data is then imported into the mold, and the mesh properties and analysis steps are modified to convert the temperature field into a stress field simulation, exporting the stress field data. After modifying the parameters, the simulation is submitted to the software. After the stress field calculation is completed, the changes in mold temperature and stress over time are observed. If there are multiple hot spots in the mold, or excessive stress points in the temperature-controlled flow channel and the mold, the design of the internal temperature-controlled flow channel needs to be adjusted to ensure that the mold surface temperature is within a controllable range after the simulation.

[0018] Furthermore, in step 1), 3D modeling software is used to determine the arrangement, shape, and size of the temperature control channels based on product requirements and the shape and size of the mold (or the product digital model structure provided by the customer), to ensure that the temperature control channels in the mold are efficient in cooling and have a reasonable structure, so as to achieve a better cooling effect on the mold.

[0019] Furthermore, step 2) specifically involves:

[0020] Import the overall mold model established in step 1) into the simulation analysis software (Abaqus CAE), set the material parameters, set the heat transfer analysis step, and divide the mesh in the software (i.e., establish a simulation mesh model). Set the mesh output parameters to temperature-related data. The material parameters include the material's density, Young's modulus, Poisson's ratio, specific heat capacity, thermal conductivity, and coefficient of thermal expansion.

[0021] Furthermore, step 3) specifically involves:

[0022] 3.1) Set the contact conditions between the material surface and the internal temperature-controlled flow channel to simulate the temperature field of the molten metal and the temperature-controlled flow channel. The contact conditions are surface temperature field data, internal temperature-controlled flow channel temperature data, and heat transfer coefficient.

[0023] 3.2) Before performing product temperature field simulation, check whether the set material parameters, contact conditions, heat transfer analysis step settings, and mesh output parameters are temperature field related parameters; set the analysis step to first output mold temperature field data, and after the parameters are set, proceed to the next step and submit to the software for simulation calculation;

[0024] This check includes a full-process check and optimization of the material properties of the mold during use, analysis step settings, mesh properties, temperature field data, and application time.

[0025] 3.3) Submit the simulation analysis software to perform mold simulation, simulate the overall temperature distribution of the mold when the mold surface heats up and the temperature-controlled flow channel cools down, and obtain temperature field data.

[0026] Furthermore, in 3.1), the surface temperature field data is set to gradually decrease from the highest temperature and then decrease again after returning to the highest temperature, so as to realize the cyclic heating and cooling process of the mold during use.

[0027] Further, step 4) specifically involves:

[0028] 4.1) Import the temperature field data obtained in step 3) into the Load module of the simulation analysis software and set it as the temperature of the mold (i.e., the loading condition). Modify the calculation analysis step, adjust the mesh output parameters (i.e., mesh properties), and set the export stress field data.

[0029] This check includes a full-process check and optimization of the import of temperature field data, stress analysis step settings, and mesh output parameters;

[0030] 4.2) Before performing product stress field simulation, check whether the set material parameters, calculation analysis step settings, and mesh output parameters are stress field related data;

[0031] 4.3) Submit the simulation analysis software to perform mold simulation, simulate the overall stress distribution of the mold when the mold surface heats up and the temperature-controlled flow channel cools, and obtain stress field data.

[0032] Furthermore, in step 4.1), the time for recording the calculated temperature field data is ensured to be consistent when setting the stress analysis parameters.

[0033] Furthermore, during steps 3) and 4), the temperature of the mold surface gradually decreases, while the temperature of the temperature-controlled flow channel remains constant to cool the mold. After the simulation is completed, the highest temperature on the mold surface is controlled below the material's allowable service temperature and is evenly distributed, and the maximum stress inside the mold is controlled below the allowable stress.

[0034] Furthermore, in step 5), the temperature and stress changes of the mold are monitored in the result analysis step. If the surface temperature of the mold is too high (exceeding the allowable temperature) or the internal temperature control channel stress is too high (exceeding the allowable stress), it is necessary to optimize the temperature control channel structure design or adjust the water temperature range so that the temperature and stress distribution of the mold after molding are within the required range.

[0035] Furthermore, in step 5), the STEP file of the output temperature control channel model with reasonable structure can be used to adjust the shape and size of the temperature control channel according to the actual mold structure during the temperature control channel design process, and then imported into Abaqus CAE for simulation analysis to verify its feasibility.

[0036] The advantages of this invention are:

[0037] 1. The present invention provides a simulation method for the temperature and stress fields of a mold containing an additively manufactured conformal temperature-controlled runner based on the finite element method. This method can greatly improve the rationality of the internal structure design of the mold, avoid design defects, significantly reduce the overall project development cycle, reduce the trial and error costs of mold and temperature-controlled runner design, improve the design yield of temperature-controlled runner, shorten the delivery time to customers, meet the requirements of high-quality and high-efficiency operation, and have strong market competitiveness.

[0038] 2. This invention uses the finite element method to simulate the cyclic process of continuous heating of the mold and cooling using a temperature-controlled flow channel during production. It analyzes the simulation results of the internal temperature-controlled flow channel of the product, identifies deficiencies in the design of the temperature-controlled flow channel during the product design phase, and optimizes the unstable factors such as stress concentration at local temperature-controlled flow channels to improve product reliability.

[0039] 3. This invention optimizes the design of the temperature control channel without changing the customer's mold, improves the cooling performance of the temperature control channel, and extends the product's lifespan.

[0040] 4. This invention optimizes the structure of the temperature control channel through simulation, avoiding the production of defective products and the occurrence of mold modification processes, thereby minimizing development and manufacturing costs.

[0041] 5. This invention can effectively analyze the changes in temperature and stress of the mold and internal temperature-controlled flow channel during the production process, thereby better optimizing the quality of the early mold design and controlling the stability of the later production.

[0042] 6. The method of this invention provides more accurate stress simulation and is more conducive to the design of water channels in additive manufacturing molds. Attached Figure Description

[0043] Figure 1 The mold model and cooling water channel model are embodiments of the present invention, where a is the mold model and b is the internal temperature control flow channel model of the mold;

[0044] Figure 2 The following are the Abaqus temperature simulation results for this embodiment of the invention: a represents the overall temperature field distribution of the mold, and b represents the temperature field distribution of the mold cross section.

[0045] Figure 3 The following are the Abaqus stress simulation results of the embodiments of the present invention: a is the overall stress field distribution of the mold, and b is the stress field distribution of the mold section.

[0046] Figure 4 A flowchart for the invention of a simulation method. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0048] like Figure 4 As shown, this invention provides a method for simulating the temperature and stress fields of a hot nozzle mold containing an additively manufactured conformal temperature-controlled flow channel based on the finite element method, comprising the following steps:

[0049] Step 1: Design the internal temperature control flow channel model of the hot runner mold using 3D modeling software, such as... Figure 1 As shown in b, the overall model of the mold is established as follows. Figure 1 a;

[0050] It should be specifically noted that in step one, the mold is used in the die-casting field, and the water channels within the mold exchange heat with the mold. The 3D modeling software designs a 3D tool body model based on the product's digital model, and determines the arrangement, shape, and size of the temperature-controlled flow channels based on the mold's shape and dimensions, in order to better cool the mold.

[0051] Step Two: Import the entire 3D model into the simulation analysis software to set the material parameters. After importing, set the material's density, Young's modulus, Poisson's ratio, specific heat capacity, thermal conductivity, and coefficient of thermal expansion. It should be noted that in Step Two, the simulation analysis software is Abaqus CAE analysis software. The 3D tool model is imported into the simulation analysis software in STEP format to improve the accuracy of the 3D tool model during the analysis process.

[0052] Step 3: Set up the heat transfer analysis step, and generate a mesh in the software, setting the mesh output parameters to temperature-related data;

[0053] It should be noted that during the interface conversion process between 3D modeling software and analysis software, software format incompatibility issues may occur, leading to quality problems such as damaged mesh surfaces or even the inability to generate a mesh. Therefore, timely repair of damaged mold surfaces using the software's built-in mesh inspection function can improve mesh reliability and the efficiency and accuracy of analysis. During the format conversion process from modeling software to analysis software, some surface quality may become abnormal. After successful import, the damaged surfaces caused by format conversion can be repaired by adjusting the curve smoothness. In step three, the imported STEP file is checked to see if there are any model surface defects caused by incompatibility between the analysis software and modeling software. When generating the mesh, the mesh density should be appropriately reduced for mesh areas that are not in direct contact with molten metal and cooling water; the mesh density should be appropriately increased for mesh areas involved in material forming and temperature control flow channels. By adjusting the quality of the mesh generation, the quality of the analysis results can be effectively improved, and the time spent on software analysis can be reasonably controlled.

[0054] Step 4: Set the temperature field data of the material surface contact, the temperature data of the temperature control channel, and the heat transfer coefficient;

[0055] It should be noted that the contact area can be precisely selected by hiding part of the plane. The temperature field data can be set to gradually decrease from the highest temperature and then decrease again after returning to the highest temperature, thereby achieving a cyclic heating and cooling process for the mold during use.

[0056] Step 5: Before performing the product temperature field simulation, check whether the parameters are correct and whether the unit conversion is correct. Check whether the set material parameters, contact conditions, analysis step settings and mesh output parameters are temperature field data.

[0057] It should be noted that the inspection includes a full-process inspection and optimization of the material properties, analysis step settings, mesh attributes, temperature field data, and application time during mold use.

[0058] Step Six: Submit the simulation to the software to simulate the mold surface heating and the cooling of the temperature-controlled runner, showing the step-by-step temperature changes of the overall mold. The simulation results are as follows: Figure 2 As shown in a and b, the part of the hot nozzle without a temperature control channel inside has a higher temperature and is shown in red, while the part of the hot nozzle with a temperature control channel at the end has a significantly lower temperature. The temperature control channel has a significant cooling effect on the mold, and the highest temperature on the mold surface does not exceed the allowable temperature.

[0059] Step 7: Import the calculated temperature field data back into the software and set it as the temperature of the mold. Modify the calculation and analysis step, adjust the mesh output parameters, and set the export stress field data.

[0060] It should be specifically noted that the time for recording the calculated temperature field data must be consistent with the time when setting the stress analysis parameters.

[0061] Step 8: Before performing product stress field simulation, check whether the parameters are correct and whether the unit conversion is correct. Check whether the set material parameters, analysis step settings and mesh output parameters are stress field data.

[0062] It should be noted that the check includes a full-process check and optimization of the import of temperature field data, stress analysis step settings, and mesh output parameters.

[0063] Step Nine: Submit the software calculation to simulate the step-by-step simulation results of the overall stress of the mold during the surface heating and cooling of the temperature-controlled flow channel. Figure 3 As shown in a and b, the overall stress inside the mold and the temperature control channel is low. The stress at both ends of the temperature control channel, which has higher stress, does not exceed the allowable stress. It can be judged that the design of the temperature control channel is reasonable.

[0064] Step 10: After the calculation, analyze the stress and temperature field data of the mold to determine whether the temperature-controlled flow channel model inside the mold needs optimization. If the temperature is too high or the stress exceeds the allowable stress requirements of the material, the 3D model of the product needs to be modified, and the 3D model of the temperature-controlled flow channel inside the mold needs to be reconstructed. After another calculation, check whether the temperature-controlled flow channel meets the cooling requirements and the rationality of the design. Repeat the iterative analysis and inspection of the mold until a qualified mold model containing the temperature-controlled flow channel is obtained. The example simulation shows that the highest temperature inside the mold is 152.4℃ and the highest stress is 110MPa, which meets the usage requirements.

[0065] It should be specifically noted that optimizing the temperature-controlled runner model includes adjusting the shape of the runner and adding chamfered transitions at stress concentration points to improve stress distribution in the mold. A STEP file of a structurally sound temperature-controlled runner model is output. During the design process, the shape and size of the runner can be adjusted according to the actual mold structure, and then imported into Abaqus CAE software for simulation analysis to verify its feasibility.

[0066] Step 11: Export the obtained mold model containing the temperature control flow channel for mold development.

[0067] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. A mold temperature field and stress field simulation method based on a finite element method containing an additive manufacturing as-built temperature control runner, characterized in that, The method comprises the following steps: 1) designing an internal temperature control runner model in a three-dimensional modeling software, and establishing a mold overall model; 2) importing the mold overall model established in step 1) into simulation analysis software Abaqus, setting material parameters, and dividing a grid; 3) setting a contact condition of a material surface and the internal temperature control runner, simulating overall temperature distribution of the mold in use, and obtaining temperature field data; specifically: 3.1) setting the contact condition of the material surface and the internal temperature control runner, wherein the contact condition is surface temperature field data, internal temperature control runner temperature data, and a heat exchange coefficient; 3.2) performing a model temperature field simulation pre-check, checking whether the set material parameters, the contact condition, the heat transfer analysis step, and the grid output parameter are related data outputted by the temperature field; the pre-check includes a full program check and optimization of material performance in use of the mold, analysis step setting, grid attribute, temperature field data, and action time; 3.3) submitting simulation analysis software for operation, performing mold simulation, simulating overall temperature distribution of the mold in surface heating and internal temperature control runner cooling, and obtaining temperature field data; 4) importing the temperature field data obtained in step 3) into a Load module of the simulation analysis software, setting mold loading conditions, modifying parameters, simulating overall stress distribution of the mold in use, and obtaining stress field data; 5) analyzing the temperature field data obtained in step 3) and the stress field data obtained in step 4), observing whether the model appears temperature exceeding a material allowable temperature range and whether the model overall appears stress concentration, and judging whether the internal temperature control runner model of the mold needs to be optimized; if the requirements are met, a qualified mold model containing the temperature control runner is obtained; if the requirements are not met, the internal temperature control runner model of the mold is further adjusted in step 1), the mold overall model is re-established, temperature field and stress field simulation are performed, the mold is cyclically analyzed and checked until the requirements are met, and a qualified mold model containing the temperature control runner is obtained.

2. The mold temperature field and stress field simulation method based on the additive manufacturing shape-following temperature control runner and the finite element method according to claim 1, wherein in step 1), a three-dimensional modeling software is used to determine a temperature control runner arrangement mode and a temperature control runner shape according to product requirements and mold shapes and sizes. Step 2) is specifically:

3. The mold temperature field and stress field simulation method based on the finite element method containing the temperature-controllable flow channel with additive manufacturing according to claim 1 or 2, characterized in that, importing the mold overall model established in step 1) into simulation analysis software Abaqus, setting material parameters, setting a heat transfer analysis step, dividing a grid, and setting a grid output parameter as temperature related data; wherein the material parameters include material density, Young's modulus, Poisson's ratio, specific heat capacity, thermal conductivity, and thermal expansion coefficient.

4. The mold temperature field and stress field simulation method based on the additive manufacturing shape-following temperature control runner and the finite element method according to claim 3, wherein in 3.1), the surface temperature field data is set to gradually decay from the highest temperature and then decay again after returning to the highest temperature, so as to realize a cyclic heating and cooling process of the mold in use. Step 4) is specifically: ​ 5. The mold temperature field and stress field simulation method based on the finite element method containing the additive manufacturing conformal temperature control flow channel according to claim 4, characterized in that, ​ 4.1) Import the temperature field data obtained in step 3) into the load module of the simulation analysis software, set it as the loading condition of the mold, modify the operation analysis step, adjust the grid output parameters, and set the stress field data export; The inspection here includes the import of temperature field data, the setting of stress analysis step, and the full-process inspection optimization of grid output parameters; 4.2) Before product stress field simulation, check whether the set material parameters, operation analysis step, and grid output parameters are related to the output stress field data; 4.3) Submit the simulation analysis software operation to perform mold simulation, simulate the overall stress distribution of the mold when the mold surface is heated and the temperature control runner is cooled, and obtain the stress field data.

6. The mold temperature field and stress field simulation method containing additive manufacturing conformal temperature control runners based on the finite element method according to claim 5, characterized in that: In step 4.1), the time of the calculated temperature field data is recorded, and the time is consistent when setting the stress analysis parameters.

7. The mold temperature field and stress field simulation method containing additive manufacturing conformal temperature control runners based on the finite element method according to claim 6, characterized in that: When steps 3) and 4) are performed, the temperature of the mold surface contact gradually decays, the temperature of the temperature control runner remains unchanged to cool the mold, the highest temperature of the mold surface is controlled below the allowable service temperature of the material and is uniformly distributed after the simulation is completed, and the maximum stress of the mold is controlled below the allowable stress.

8. The mold temperature field and stress field simulation method containing additive manufacturing conformal temperature control runners based on the finite element method according to claim 7, characterized in that: In step 5), the temperature and stress changes of the mold are monitored in the result analysis step, and if the mold surface temperature exceeds the allowable temperature or the internal temperature control runner stress exceeds the allowable stress, the temperature control runner structure design needs to be optimized or the water temperature range needs to be adjusted, so that the mold temperature and stress distribution after forming are within the required range.

9. The mold temperature field and stress field simulation method containing additive manufacturing conformal temperature control runners based on the finite element method according to claim 8, characterized in that: In step 5), the STEP file of the output structure reasonable temperature control runner model is imported, and the shape and size of the temperature control runner can be adjusted according to the actual mold structure during the temperature control runner design process, and the CAE simulation analysis verifies the feasibility.

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