A double-temperature-zone gradient temperature control EPP injection molding method based on mold flow analysis

Abstract

This invention relates to a dual-temperature zone gradient temperature control EPP injection molding method based on mold flow analysis, belonging to the field of plastic injection molding technology. The method includes the following steps: S1, mold flow analysis modeling and simulation; S2, dual-temperature zone division and gradient temperature control scheme determination: based on the mold flow analysis results, the mold cavity is divided into a high-temperature zone and a low-temperature zone, and the width and temperature change slope of the gradient transition zone between the high-temperature and low-temperature zones are determined; S3, gradient temperature control mold design and manufacturing; S4, mold trial and process parameter verification; S5, EPP injection molding to obtain the EPP injection molded product. This dual-temperature zone gradient temperature control EPP injection molding method based on mold flow analysis systematically simulates the filling flow, temperature distribution, and wall thickness distribution of the EPP injection molded product through mold flow analysis, scientifically determining the boundary between the high-temperature and low-temperature zones and the width and temperature change slope of the gradient transition zone, thus improving the mechanical properties and dimensional stability of the EPP product in the temperature interface region.

Description

Technical Field

[0001] This invention relates to the field of plastic injection molding technology, specifically to a dual-temperature gradient temperature-controlled EPP injection molding method based on mold flow analysis, which is particularly suitable for precision injection molding of foamed polypropylene (EPP) products. Background Technology

[0002] Foamed polypropylene (EPP) is a lightweight, high-strength foam material made from polypropylene resin through physical foaming. It possesses excellent impact resistance, resilience, heat resistance, and recyclability, and is widely used in automotive parts, packaging materials, building insulation, and sporting goods. However, polypropylene is a linear semi-crystalline material, lacking the tensile rheological properties required to achieve a uniform and controllable cell structure during melt foaming. EPP injection molding places extremely high demands on the uniformity and controllability of the mold temperature field—excessive temperature can lead to particle adhesion and cell rupture; insufficient temperature results in insufficient expansion and weak particle bonding. Achieving precise control of the mold cavity temperature field is the core technology of EPP injection molding.

[0003] The existing EPP injection molding technology has the following main shortcomings:

[0004] Firstly, the temperature field control method for molds is simplistic and lacks the ability to regulate temperatures in different zones. Existing mold temperature control systems mostly adopt overall heating or cooling methods, which cannot regulate temperatures in different zones according to differences in wall thickness, structural complexity, and flow characteristics of different areas of the product. For EPP products with complex geometries, a single temperature field is insufficient to meet the differentiated needs of thin-walled areas (which require higher temperatures to ensure sufficient foaming) and thick-walled areas (which require lower temperatures to prevent over-foaming).

[0005] Secondly, the determination of process parameters relies on experience-based trial and error, lacking scientific mold flow analysis guidance. Current injection molding process parameter settings largely depend on operator experience and repeated trial molding adjustments, lacking scientific quantitative basis based on mold flow analysis. This experience-based approach leads to long mold development cycles, high trial molding costs, and difficulty in ensuring consistent product quality across different batches.

[0006] Third, the lack of gradient temperature control design leads to uncontrollable temperature transitions. In existing processes, temperature switching between different areas of the mold is often abrupt, lacking a gradient transition design from high-temperature to low-temperature zones. Sudden temperature changes can easily cause stress concentration and uneven cell structure in EPP material at temperature interfaces, affecting the mechanical properties and appearance quality of the product.

[0007] Fourth, there is a lack of effective data closure between mold flow analysis data and injection molding process parameters. Existing mold flow analysis is mostly a one-time simulation verification, and the analysis results have not been effectively transformed into executable process parameter control strategies, resulting in a "data gap" between simulation and production.

[0008] Therefore, there is a need for an injection molding method that can achieve precise temperature field zoning control of EPP injection molds, scientific determination of process parameters based on mold flow analysis, and smooth transition of temperature gradient, in order to solve the problems of single temperature field control, reliance on experience-based trial and error for process parameters, and uncontrollable temperature gradient in existing technologies. Summary of the Invention

[0009] To address the shortcomings of existing technologies, this invention provides a dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis. This method has advantages such as scientific mold flow zoning, smooth gradient temperature control, and closed-loop mold trial verification, and solves the problems of difficult zoned temperature control, reliance on experience-based trial and error, and defects caused by sudden temperature changes.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A dual-temperature gradient temperature-controlled EPP injection molding method based on mold flow analysis includes the following steps:

[0012] S1. Mold Flow Analysis Modeling and Simulation: Establish a CAD 3D model of the EPP injection molded product, import it into mold flow analysis software for mesh generation, set the physical property parameters and initial process parameters of the EPP material, and perform mold flow analysis simulation of the filling, holding and cooling processes.

[0013] S2. Dual-temperature zone division and gradient temperature control scheme determination: Based on the mold flow analysis results, the mold cavity is divided into a high-temperature zone and a low-temperature zone, and the width and temperature change slope of the gradient transition zone between the high-temperature zone and the low-temperature zone are determined.

[0014] S3. Gradient temperature control mold design and manufacturing: According to the dual temperature zone division and gradient temperature control scheme, a high temperature heating channel is set in the high temperature zone of the mold, a low temperature cooling channel is set in the low temperature zone, and a temperature regulating channel with interval distribution is set in the gradient transition zone.

[0015] S4. Mold Trial and Process Parameter Verification: Install the mold on the injection molding machine for trial molding, collect the actual temperature data of each temperature zone, and compare and verify it with the simulated temperature data of the mold flow analysis.

[0016] S5. EPP Injection Molding: Perform EPP injection molding according to the verified process parameters. After holding pressure and cooling, demold to obtain EPP injection molded products.

[0017] Furthermore, the dual-temperature zone division method in S2 is as follows: the area with a wall thickness greater than the first threshold is classified as the high-temperature zone, and the area with a wall thickness less than the second threshold is classified as the low-temperature zone; the first threshold is greater than the second threshold; the gradient transition zone is located between the high-temperature zone and the low-temperature zone, and its width is 5% to 25% of the total dimension of the mold cavity in the corresponding direction; the wall thickness area located between the first threshold and the second threshold is classified as the gradient transition zone.

[0018] Furthermore, the temperature change slope of the gradient transition region in S2 is 0.5 to 5℃ / mm, so that the temperature from the high temperature region to the low temperature region decreases continuously rather than abruptly.

[0019] Furthermore, the physical properties of the EPP material in S1 include melting temperature, glass transition temperature, thermal conductivity, specific heat capacity, melt density, viscosity curve, and PVT relationship curve.

[0020] Furthermore, in S3, high-temperature heat transfer oil or steam is introduced into the high-temperature heating channel, with a temperature control range of 140–180°C; cooling water or low-temperature heat transfer oil is introduced into the low-temperature cooling channel, with a temperature control range of 30–80°C; and a medium-temperature medium is introduced into the temperature regulating channel, with a temperature control range of 80–140°C.

[0021] Furthermore, in the gradient transition zone of S3, the temperature regulating channels are distributed with varying spacing along the temperature gradient direction, and the channel spacing near the high temperature zone is smaller than the channel spacing near the low temperature zone.

[0022] Furthermore, the mold flow analysis software in S1 is Moldflow or Moldex3D; the mold flow analysis includes at least filling analysis, holding pressure analysis, cooling analysis, and warpage analysis.

[0023] Furthermore, the verification criteria in S4 are: the deviation between the measured temperature and the simulated temperature in each temperature zone does not exceed ±3℃, and the correlation coefficient of the temperature gradient curve is not less than 0.90.

[0024] Furthermore, in S5, the injection pressure of EPP injection molding is 50-150 MPa, the holding pressure is 30-80 MPa, and the injection speed is 30-80 mm / s.

[0025] Furthermore, the method also includes the step of establishing an injection molding process parameter database based on mold flow analysis data and actual molding quality data from multiple batches, which is used for setting initial parameters for mold flow analysis of subsequent similar products.

[0026] Compared with existing technologies, this invention provides a dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis, which has the following beneficial effects:

[0027] 1. This dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis systematically simulates the filling flow, temperature distribution, and wall thickness distribution of EPP injection molded products through mold flow analysis, scientifically determining the boundary between the high-temperature and low-temperature zones, as well as the width and temperature change slope of the gradient transition zone. Compared with the traditional overall temperature control method, the zoned temperature control strategy of this invention makes the temperature of each region of the mold cavity more matched to the molding requirements of that region—the high-temperature zone ensures sufficient foaming and welding of EPP material in thick-walled areas, while the low-temperature zone prevents over-foaming and deformation in thin-walled areas.

[0028] 2. This dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis sets up a gradient transition zone between the high-temperature and low-temperature zones. A continuous gradient decrease in temperature, rather than abrupt changes, is achieved through spaced temperature-regulating channels, with a temperature change slope of 0.5–5℃ / mm. This gradient transition design effectively eliminates stress concentration, uneven cell structure, and appearance defects caused by abrupt temperature changes, improving the mechanical properties and dimensional stability of EPP products in the temperature interface region.

[0029] 3. This dual-temperature zone gradient temperature control EPP injection molding method based on mold flow analysis directly guides the division of dual temperature zones, the determination of gradient temperature control schemes, and the design of mold temperature control channels through mold flow analysis results. It also establishes a closed-loop feedback between simulation and reality through trial molding verification, which transforms the setting of process parameters from experience-based trial and error to data-driven, significantly shortening the mold development cycle and improving the accuracy and batch consistency of process parameters.

[0030] 4. This dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis achieves optimal foaming temperature and cooling rate for EPP material in different wall thickness regions through a dual-temperature gradient temperature control strategy, resulting in a uniform and dense cell structure and excellent surface quality. Compared with traditional single temperature control methods, the dimensional accuracy of the products is improved, internal stress is reduced, and the scrap rate is significantly reduced. It also reduces material waste caused by trial molding adjustments, resulting in good economic and environmental benefits. Attached Figure Description

[0031] Figure 1 This is an overall flowchart of the EPP injection molding method based on mold flow analysis according to the present invention.

[0032] Figure 2 This is a schematic diagram of the mold temperature field distribution in the dual-temperature zone and gradient transition zone of the EPP injection molding method based on mold flow analysis according to the present invention.

[0033] Figure 3 This is a schematic diagram of the variable spacing arrangement of the temperature regulating channels in the gradient transition zone of the EPP injection molding method based on mold flow analysis according to the present invention. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Please see Figures 1 to 3 .

[0036] Example 1: Dual-temperature zone gradient temperature control molding of automotive interior EPP buffer block

[0037] This embodiment takes a certain car model's door interior EPP buffer block (maximum wall thickness 12mm, minimum wall thickness 3mm, external dimensions 300mm×200mm×80mm) as an example to illustrate the specific implementation process of the present invention.

[0038] S1: Modeling and Simulation of Mold Flow Analysis

[0039] A CAD 3D model of the EPP buffer block was created and imported into Moldflow mold flow analysis software for mesh generation (3D solid mesh, approximately 800,000 elements). The physical properties of the EPP material were set as follows: melt temperature 165℃, glass transition temperature -10℃, thermal conductivity 0.15 W / (m·K), specific heat capacity 2.1 kJ / (kg·K), melt density 0.75 g / cm³. Initial process parameters were set as follows: mold temperature 80℃, melt temperature 190℃, injection pressure 80 MPa, holding pressure 50 MPa, injection speed 50 mm / s. Filling analysis, holding pressure analysis, cooling analysis, and warpage analysis were then performed.

[0040] Mold flow analysis results show that the flow front temperature in the thick-walled area of ​​the product (wall thickness > 8 mm, located in the center of the product) drops below 165°C at the end of filling, posing a risk of insufficient filling; the flow front temperature in the thin-walled area (wall thickness < 5 mm, located at the edge of the product) is higher, and the cooling rate is too fast.

[0041] S2: Determination of Dual Temperature Zone Division and Gradient Temperature Control Scheme

[0042] Based on the mold flow analysis results, with a wall thickness of 8mm as the dividing threshold: the central area with a wall thickness ≥8mm (accounting for approximately 40% of the cavity area) is classified as the high-temperature zone, with a target temperature of 160℃; the edge area with a wall thickness ≤5mm (accounting for approximately 35% of the cavity area) is classified as the low-temperature zone, with a target temperature of 60℃; the transition area between the high-temperature and low-temperature zones (accounting for approximately 25% of the cavity area) is classified as the gradient transition zone, with a width of 30mm and a temperature change slope of 3.3℃ / mm (gradually decreasing from 160℃ to 60℃).

[0043] S3: Gradient Temperature Control Mold Design and Manufacturing

[0044] The injection mold is designed and manufactured according to a dual-temperature zone division scheme: A high-temperature heating channel (φ8mm, 20mm spacing) is set inside the mold core corresponding to the high-temperature zone, through which high-temperature heat transfer oil (temperature 160℃) is circulated; a low-temperature cooling channel (φ8mm, 25mm spacing) is set inside the mold core corresponding to the low-temperature zone, through which cooling water (temperature 60℃) is circulated; a temperature-regulating channel (φ6mm) is set in the gradient transition zone, with a variable spacing distribution along the temperature gradient direction—12mm spacing near the high-temperature zone and 20mm spacing near the low-temperature zone, through which medium-temperature heat transfer oil (temperature 110℃) is circulated. The three temperature control channels are each connected to an independent temperature control unit, and each temperature control unit achieves closed-loop control via a PLC.

[0045] S4: Trial molding and verification of process parameters

[0046] The mold was installed on an injection molding machine for trial molding. Thermocouples were placed in various areas of the mold cavity (3 measuring points in the high-temperature zone, 4 measuring points in the transition zone, and 3 measuring points in the low-temperature zone) to collect actual temperature data. The comparison between the measured data and the mold flow analysis simulation data is as follows: the measured average temperature in the high-temperature zone was 158.5℃ (simulation 160℃, deviation -1.5℃), the measured average temperature in the low-temperature zone was 61.2℃ (simulation 60℃, deviation +1.2℃), and the correlation coefficient between the measured temperature and the simulated temperature curve at each measuring point in the gradient transition zone was 0.94, which meets the verification standard.

[0047] S5: EPP Injection Molding

[0048] EPP injection molding was performed according to the verified process parameters: the EPP raw material was heated to 190℃ to melt and injected into the mold cavity at an injection pressure of 80MPa and an injection speed of 50mm / s; the dual-temperature gradient temperature control system maintained the temperature of the high-temperature zone at 158~162℃ and the low-temperature zone at 59~63℃, with the gradient transition zone showing a continuous gradient decrease; the holding pressure was 50MPa and the holding time was 8s; the cooling time was 25s; and the EPP buffer block product was obtained by demolding.

[0049] Product quality inspection: The product surface is smooth with no obvious shrinkage marks, the cell diameter is uniformly distributed (average cell diameter 120μm, standard deviation 15μm), the density is 0.12g / cm³, the compressive strength is 1.8MPa, and the dimensional tolerances meet the design requirements.

[0050] Example 2: Dual-temperature gradient temperature control molding of EPP packaging liners

[0051] This embodiment uses the EPP packaging liner of an electronic device (maximum wall thickness 10mm, minimum wall thickness 2mm) as an example for illustration.

[0052] S1: Modeling and Simulation of Mold Flow Analysis

[0053] A CAD model of the packaging liner was created and imported into Moldex3D mold flow analysis software for mesh generation. EPP material properties and initial process parameters were set, and mold flow analysis was performed. Analysis results show that the central area of ​​the product (wall thickness 6–10 mm) has a risk of insufficient foaming, while the edge area (wall thickness 2–4 mm) has a risk of over-foaming and mold sticking.

[0054] S2: Determination of Dual Temperature Zone Division and Gradient Temperature Control Scheme

[0055] Using a wall thickness of 6mm as the dividing threshold: the area with a wall thickness ≥ 6mm (accounting for approximately 55% of the cavity area) is classified as the high-temperature zone with a target temperature of 155℃; the area with a wall thickness ≤ 4mm (accounting for approximately 25% of the cavity area) is classified as the low-temperature zone with a target temperature of 50℃; the gradient transition zone width is 25mm, and the temperature change slope is 4.2℃ / mm.

[0056] S3: Gradient Temperature Control Mold Design and Manufacturing

[0057] Steam (155°C) is introduced into the high-temperature zone channel, cooling water (50°C) is introduced into the low-temperature zone channel, and medium-temperature heat transfer oil (100°C) is introduced into the transition zone temperature regulation channel. The variable spacing arrangement is the same as in Example 1.

[0058] S4: Trial molding verification and S5: Molding

[0059] After the trial molding verification is passed, molding is carried out according to the following parameters: melt temperature 185℃, injection pressure 70MPa, holding pressure 40MPa, injection speed 60mm / s, holding time 6s, and cooling time 20s.

[0060] Product quality inspection: No surface defects, uniform cell diameter (average 110μm), density 0.10g / cm³, compressive strength 1.5MPa.

[0061] Example 3: Comparative Experiment with Different Temperature Parameters

[0062] To verify the effectiveness of the dual-temperature gradient temperature control, three sets of comparative experiments were conducted using the product from Example 1 as the subject:

[0063] Control group A (traditional single temperature control): The overall temperature of the mold is controlled at 80℃, without zoned temperature control and gradient transition.

[0064] Control group B (dual temperature zone without gradient): divided into high temperature zone and low temperature zone, but without a gradient transition zone between the two zones, the temperature jumps directly.

[0065] Experimental Group C (this invention): dual temperature zone + gradient transition zone, with a continuous gradient decrease in temperature.

[0066] The results of the comparative experiments with different temperature parameters are shown in Table 1.

[0067] Table 1

[0068] Comparison Projects Control group A Control group B Experimental Group C (This Invention) High-temperature zone foaming quality Poor good good Cooling effect in low temperature zone generally good good Appearance of the temperature boundary zone No boundary Obvious color difference / stress marks No obvious color difference Cell uniformity in the temperature interface zone — Uneven, with a standard deviation of 28 μm in cell size. Uniform, with a standard deviation of 15μm in cell size. Product warpage 0.45mm 0.38mm 0.22mm scrap rate 8.5% 5.2% 1.8%

[0069] Experimental conclusion: The present invention effectively eliminates the quality defects in the interface area caused by the temperature change between the two temperature zones through the design of the gradient transition zone. The warpage and scrap rate of the products are significantly lower than those of the control group.

[0070] Example 4: Comparative Experiment of Different Gradient Transition Zone Widths

[0071] Using the product of Example 1 as the object, comparative tests were conducted with gradient transition zone widths of 10mm, 20mm, 30mm, and 40mm (the slope of the temperature change changed accordingly).

[0072] The comparative test results of different gradient transition zone widths are shown in Table 2.

[0073] Table 2

[0074] Gradient transition width Temperature change slope Border area exterior Uniformity of cells in the boundary zone Overall warpage of the product 10mm 10℃ / mm There is a noticeable color difference. Poor (standard deviation 32μm) 0.35mm 20mm 5℃ / mm Slight color difference Typical (standard deviation 22μm) 0.28mm 30mm 3.3℃ / mm No obvious color difference Good (standard deviation 15μm) 0.22mm 40mm 2.5℃ / mm none Good (standard deviation 16μm) 0.25mm

[0075] Conclusion: A gradient transition zone width of 30 mm (temperature change slope of 3.3℃ / mm) yields the best overall effect. If the transition zone is too narrow, the temperature change will be drastic and the quality of the boundary zone will be poor. If the transition zone is too wide, the effective area of ​​the high temperature zone and the low temperature zone will be reduced and the temperature control efficiency will decrease.

[0076] Comparative Example 1: Traditional experience-based trial molding process

[0077] Traditional experience-based trial molding processes (without mold flow analysis guidance, zoned temperature control, or gradient transition) are used to produce EPP buffer blocks of the same specifications. Process parameters are set by operators based on experience, and it takes eight trial molding adjustments to barely meet quality requirements. The mold development cycle is 15 days, and the material loss during trial molding is approximately 80 kg. This invention, guided by mold flow analysis, requires only two trial molding verifications to finalize the process, shortening the mold development cycle to 7 days and reducing material loss during trial molding to approximately 15 kg.

[0078] Comparative Example 2: Dual-zone temperature control without gradient

[0079] Products of the same specifications are produced using dual-temperature zone control without a gradient transition zone (direct temperature jump). Significant color differences and stress marks appear at the boundary between the high-temperature and low-temperature zones, and the cell structure exhibits abrupt changes at the boundary (one side has fine cells, the other has large cells). After a drop ball impact test at the boundary, cracks appear along the boundary line. This invention eliminates the abrupt quality changes at the boundary by using continuous temperature changes in the gradient transition zone.

[0080] Comparative Example 3: Zoned Temperature Control Guided by Model-Free Flow Analysis

[0081] The high-temperature and low-temperature zones were divided based on experience (without mold flow analysis), with all other conditions the same as in Example 1 of this invention. Because the zoning boundaries were not verified by mold flow analysis, the division of the high-temperature and low-temperature zones did not match the actual temperature distribution requirements—some thick-walled areas that should belong to the high-temperature zone were located outside the zoning boundaries, resulting in insufficient foaming, leading to locally high density and insufficient compressive strength in the product; conversely, some thin-walled areas that should belong to the low-temperature zone were located within the high-temperature zone, resulting in over-foaming and a rough surface. This invention scientifically determines the zoning boundaries through mold flow analysis, avoiding the matching deviations caused by experience-based zoning.

[0082] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0083] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A dual-temperature gradient temperature-controlled EPP injection molding method based on mold flow analysis, characterized in that, Includes the following steps: S1. Mold Flow Analysis Modeling and Simulation: Establish a CAD 3D model of the EPP injection molded product, import it into mold flow analysis software for mesh generation, set the physical property parameters and initial process parameters of the EPP material, and perform mold flow analysis simulation of the filling, holding and cooling processes. S2. Dual-temperature zone division and gradient temperature control scheme determination: Based on the mold flow analysis results, the mold cavity is divided into a high-temperature zone and a low-temperature zone, and the width and temperature change slope of the gradient transition zone between the high-temperature zone and the low-temperature zone are determined. S3. Gradient temperature control mold design and manufacturing: According to the dual temperature zone division and gradient temperature control scheme, a high temperature heating channel is set in the high temperature zone of the mold, a low temperature cooling channel is set in the low temperature zone, and a temperature regulating channel with interval distribution is set in the gradient transition zone. S4. Mold Trial and Process Parameter Verification: Install the mold on the injection molding machine for trial molding, collect the actual temperature data of each temperature zone, and compare and verify it with the simulated temperature data of the mold flow analysis. S5. EPP Injection Molding: Perform EPP injection molding according to the verified process parameters. After holding pressure and cooling, demold to obtain EPP injection molded products.

2. The dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis according to claim 1, characterized in that, The dual-temperature zone division method in S2 is as follows: the area with a wall thickness greater than the first threshold is classified as the high-temperature zone, and the area with a wall thickness less than the second threshold is classified as the low-temperature zone; the first threshold is greater than the second threshold; the gradient transition zone is located between the high-temperature zone and the low-temperature zone, and its width is 5% to 25% of the total dimension of the mold cavity in the corresponding direction; the wall thickness area located between the first threshold and the second threshold is classified as the gradient transition zone.

3. The dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis according to claim 1, characterized in that, The temperature change slope of the gradient transition region in S2 is 0.5 to 5℃ / mm, so that the temperature from the high temperature region to the low temperature region decreases continuously rather than abruptly.

4. The dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis according to claim 1, characterized in that, The physical properties of the EPP material in S1 include melting temperature, glass transition temperature, thermal conductivity, specific heat capacity, melt density, viscosity curve, and PVT relationship curve.

5. The dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis according to claim 1, characterized in that, In S3, high-temperature heat transfer oil or steam is introduced into the high-temperature heating channel, with a temperature control range of 140–180°C; cooling water or low-temperature heat transfer oil is introduced into the low-temperature cooling channel, with a temperature control range of 30–80°C; and a medium-temperature medium is introduced into the temperature regulating channel, with a temperature control range of 80–140°C.

6. The dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis according to claim 1, characterized in that, The temperature-regulating channels in the gradient transition zone of S3 are distributed with varying spacing along the temperature gradient direction, and the channel spacing near the high-temperature zone is smaller than the channel spacing near the low-temperature zone.

7. The dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis according to claim 1, characterized in that, The mold flow analysis software in S1 is Moldflow or Moldex3D; the mold flow analysis includes at least filling analysis, holding pressure analysis, cooling analysis and warpage analysis.

8. The dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis according to claim 1, characterized in that, The verification criteria in S4 are: the deviation between the measured temperature and the simulated temperature in each temperature zone shall not exceed ±3℃, and the correlation coefficient of the temperature gradient curve shall not be less than 0.

90.

9. The dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis according to claim 1, characterized in that, In S5, the injection pressure of EPP injection molding is 50-150MPa, the holding pressure is 30-80MPa, and the injection speed is 30-80mm / s.

10. The dual-temperature gradient temperature control EPP injection molding method based on mold flow analysis according to claim 1, characterized in that, The method also includes the step of establishing an injection molding process parameter database based on mold flow analysis data and actual molding quality data from multiple batches, which is used for setting initial parameters for mold flow analysis of subsequent similar products.

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