Analysis method, analysis device, and analysis program for resin molded product, and recording medium

Abstract

To improve an analysis accuracy by taking into account changes in heat transfer coefficients in actual phenomena, in an analysis method, an analysis device, and an analysis program for a resin molded product, and a recording medium.SOLUTION: The method for analyzing resin molded products using computer simulation includes a heat transfer coefficient calculation step that calculates a heat transfer coefficient at an interface between a cavity surface and resin, taking into account a mold pressure. In the heat transfer coefficient calculation step, when the mold pressure is greater than zero, the heat transfer coefficient is calculated based on the following equation (1). h=A+B×ln(C×p+1) ...(1) (In equation (1), h is the heat transfer coefficient, p is the mold pressure, and A, B, and C are coefficients.)SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a method, an apparatus, a program, and a recording medium for analyzing a resin molded product. [Background technology]

[0002] Conventionally, in order to improve the accuracy, efficiency, and cost reduction of product design for resin molded products, CAE (Computer-Aided-Engineering) has been used to analyze the behavior of resin inside a mold and the warpage deformation of the final product.

[0003] For example, when analyzing resin flow and warpage in injection molding, general-purpose CAE software sets the heat transfer coefficient at the interface between the mold cavity surface and the resin injected into the cavity to a constant value. However, in actual injection molding, the heat transfer coefficient changes during each of the injection, pressure-holding, and cooling processes. From the perspective of improving analysis accuracy, analysis methods have been proposed that can take such changes in the heat transfer coefficient into account (see, for example, Patent Documents 1 and 2).

[0004] The resin molding simulation method disclosed in Patent Document 1 includes a step of calculating the heat transfer coefficient at the interface between a mold and resin injected into the mold based on the mold temperature. Patent Document 1 states that this method makes it possible to bring the heat transfer coefficient, which varies depending on the surface roughness of the mold and the like, closer to a more accurate value than in the past, in which the heat transfer coefficient was set to a constant value, and improves the accuracy of the physical behavior of the resin during the molding process, which is predicted based on this heat transfer coefficient.

[0005] The method of analyzing the fluid flow process disclosed in Patent Document 2 is configured to determine the heat transfer coefficient by a function including the thickness of the cavity, and an example of this function is the tanh function (hyperbolic tangent function). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-289076 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-73248 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the technology of Patent Document 1, in the process of calculating the heat transfer coefficient, the heat transfer coefficient is calculated by referring to the results of measurements obtained using a mold with a simple shape as a correlation map between the mold body temperature and the heat transfer coefficient. This method has the problem that it cannot achieve sufficient analytical accuracy when analyzing molded products with complex shapes or thin walls.

[0008] Furthermore, the function that determines the heat transfer coefficient in the technology of Patent Document 2 is set retroactively from the analysis results in order to improve the accuracy of the analysis, and is not derived based on actual phenomena. Therefore, there is room for improvement in terms of improving the accuracy of the analysis.

[0009] Therefore, an object of the present disclosure is to improve the accuracy of analysis by taking into account changes in heat transfer coefficients in actual phenomena in an analysis method, analysis device, analysis program, and recording medium for resin molded products. [Means for solving the problem]

[0010] In order to solve the above problems, one aspect of the analysis method for a resin molded product disclosed herein is to: A method for analyzing a resin molded product by computer simulation, comprising: a heat transfer coefficient calculation step of calculating a heat transfer coefficient at an interface between a cavity surface of the mold and a resin in the mold, taking into account an internal pressure of the mold; In the heat transfer coefficient calculation step, when the in-mold pressure is greater than zero, the heat transfer coefficient is calculated based on the following formula (1): h=A+B×ln(C×p+1) (1) (In equation (1), h is the heat transfer coefficient, p is the pressure inside the mold, and A, B, and C are coefficients.) It is characterized by:

[0011] For example, a method for measuring the heat transfer coefficient at the interface between metals with high thermal conductivity is known, such as that described in JP 2018-8299 A. However, when the object to be measured is a resin material, the region where temperature changes occur is extremely narrow due to the low thermal conductivity of the resin, making it practically difficult to measure the heat transfer coefficient at the interface between the cavity surface and the resin.

[0012] In this regard, the present inventors, through extensive research, have successfully developed a measurement device and method for the heat transfer coefficient at the interface between the cavity surface and the resin (Japanese Patent Application Laid-Open No. 2023-153704). Specifically, a measurement device equipped with a metal punch mold and a pot mold is used, and resin is poured into the pot mold to be molten. Then, when the punch mold is brought into contact with the molten resin, the temperature changes over time of the punch mold and the resin at the interface between the punch mold and the resin and near the interface are measured, i.e., the temperature changes of both the punch mold and the resin as the resin solidifies over time. From the obtained temperature information, the temperature at the interface between the punch mold and the resin and near the interface, i.e., the surface temperature, is calculated using an equation that solves the inverse problem of the unsteady heat conduction equation. The heat flux transmitted from the resin to the punch mold is also measured simultaneously. From this information, the heat transfer coefficient at the interface can be determined.

[0013] Based on the results of the heat transfer coefficient measured by the above method, the inventors of the present application have succeeded in deriving a model equation that takes into account the dependency of the heat transfer coefficient on the pressure inside the mold (the above equation (1)). In this configuration, by using this model equation in an analysis method for resin molded products, the change in the heat transfer coefficient during actual molding is reflected in the analysis. With this configuration, analysis can be performed based on the measurement results under conditions that simulate actual molding, taking into account the dependency of the heat transfer coefficient on the pressure inside the mold during the molding process, thereby improving the accuracy of the analysis.

[0014] In one embodiment, in the heat transfer coefficient calculation step, when the internal mold pressure is zero, the heat transfer coefficient is calculated based on the following formula (2): h=A×e D×s ···(2) (In equation (2), s is the gap between the cavity surface and the resin, and D is a coefficient.) This may be done.

[0015] When the mold pressure is zero, the cavity surface and the resin are considered to be in a non-contact state. In this case, the heat transfer coefficient at the interface between the cavity surface and the resin is considered to depend on the amount of gap between them. This configuration enables analysis that takes into account the dependency of the heat transfer coefficient on the amount of gap, thereby improving analysis accuracy.

[0016] In one embodiment, a contact state calculation step is provided before the heat transfer coefficient calculation step, in which a contact state between the cavity surface of the mold and the resin is calculated, When the contact state calculation step determines that the contact state is a state in which the resin comes into contact with the cavity surface and then contracts, causing the resin to separate from the cavity surface and become non-contact, the heat transfer coefficient calculation step calculates the heat transfer coefficient based on the following formula (2): h=A×e D×s ···(2) (In equation (2), s is the gap between the cavity surface and the resin, and D is a coefficient.) This may be done.

[0017] When the resin shrinks due to cooling or the like, a gap is created between the cavity surface and the resin surface. This configuration enables analysis that takes into account the gap volume dependency of the heat transfer coefficient, thereby improving analysis accuracy. Note that "a state in which the resin comes into contact with the cavity surface and then shrinks, causing the resin to separate from the cavity surface, resulting in a non-contact state" means, for example, in the case of a molding method such as injection molding in which molten resin is injected into a cavity, "a state in which the resin shrinks after the flow front of the resin reaches the cavity surface, causing the resin to separate from the cavity surface, resulting in a non-contact state."

[0018] The gap amount is expressed as the distance from the cavity surface to the surface of the resin in the normal direction based on the cavity surface. It is preferable.

[0019] According to this configuration, the amount of the gap between the cavity surface and the resin surface can be calculated with high accuracy, thereby improving the accuracy of analysis.

[0020] In one embodiment, the time step t n a boundary condition acquisition step of acquiring boundary conditions including the heat transfer coefficient to be used in the calculation of Based on the boundary conditions, the time step t n a resin characteristic calculation step of calculating resin characteristics including the in-mold pressure; The time step t n and a boundary condition correction step of correcting the boundary conditions used in the calculation of the heat transfer coefficient calculation step is performed after the resin characteristic calculation step and before the boundary condition correction step, Next time step t n+1 In the boundary condition acquisition step, the modified boundary conditions are applied to the next time step t n+1 as the boundary conditions used in the calculation of This may be done.

[0021] According to this configuration, the boundary conditions including the heat transfer coefficient are corrected for each time step based on the pressure calculated in the resin property calculation step, and are reflected in the calculation of the next time step, thereby improving calculation accuracy.

[0022] One aspect of the resin molded product analysis device disclosed herein is: An apparatus for analyzing a resin molded product by computer simulation, a heat transfer coefficient calculation unit that calculates a heat transfer coefficient at an interface between a cavity surface of the mold and a resin in the mold, taking into account an internal pressure of the mold; The heat transfer coefficient calculation unit calculates the heat transfer coefficient based on the following formula (1) when the in-mold pressure is greater than zero: h=A+B×ln(C×p+1) (1) (In equation (1), h is the heat transfer coefficient, p is the pressure inside the mold, and A, B, and C are coefficients.) It is characterized by:

[0023] According to this configuration, the analysis is performed based on the measurement results under conditions that simulate actual molding, taking into consideration the dependency of the heat transfer coefficient on the pressure inside the mold during the molding process, thereby improving the accuracy of the analysis.

[0024] One aspect of the program for analyzing a resin molded product disclosed herein is: A program for analyzing a resin molded product by computer simulation, At a minimum, the computer a procedure for calculating a heat transfer coefficient at an interface between a cavity surface of the mold and a resin in the mold, taking into account the pressure inside the mold; In the above procedure, when the mold pressure is greater than zero, the heat transfer coefficient is calculated based on the following formula (1): h=A+B×ln(C×p+1) (1) (In equation (1), h is the heat transfer coefficient, p is the pressure inside the mold, and A, B, and C are coefficients.) It is characterized by:

[0025] According to this configuration, the analysis is performed based on the measurement results under conditions that simulate actual molding, taking into consideration the dependency of the heat transfer coefficient on the pressure inside the mold during the molding process, thereby improving the accuracy of the analysis.

[0026] One aspect of the recording medium disclosed herein is: A computer-readable recording medium storing the above-mentioned program for analyzing resin molded products. [Effects of the Invention]

[0027] As described above, according to the present disclosure, analysis is performed based on measurement results under conditions that simulate actual molding, taking into account the dependency of the heat transfer coefficient on the pressure inside the mold during the molding process, thereby improving the accuracy of the analysis. [Brief explanation of the drawings]

[0028] [Figure 1] 1A to 1C are diagrams for explaining each step in resin injection molding and a graph showing an example of changes in in-mold pressure over time. [Figure 2] FIG. 1 is a diagram showing an example of the configuration of an analysis device for a resin molded product according to a first embodiment. [Figure 3] 3 is a flowchart showing an example of a method for analyzing a resin molded product according to the first embodiment. [Figure 4] 10A and 10B are diagrams for explaining the relationship between the pressure inside the mold, the contact state, and the heat transfer mechanism. [Figure 5] 10 is a graph showing the dependency of the heat transfer coefficient on the pressure inside the mold obtained by measurement experiment 1. [Figure 6] 10 is a graph showing the gap volume dependency of the heat transfer coefficient obtained from measurement experiment 2. [Figure 7] FIG. 10 is a diagram for explaining an example of a method for calculating a gap amount. [Figure 8] 3 and illustrates an example of a method for analyzing a resin molded product according to the second embodiment. [Figure 9] 3 and illustrates an example of a method for analyzing a resin molded product according to a third embodiment. FIG. [Figure 10]10 is a diagram for explaining that warpage deformation of the workpiece causes a part of the workpiece to be pressed against the cavity surface, generating pressure. FIG. [Figure 11] FIG. 1 is a perspective view showing the shape of a mold used in a verification experiment. [Figure 12] FIG. 1 is a front view showing the cavity shape of a mold used in a verification experiment. [Figure 13] 10 is a graph showing the change in the pressure inside the mold over time and the change in the heat transfer coefficient over time for the example and the comparative example, as measured by a pressure sensor 310B. [Figure 14] FIG. 10 is a diagram showing the results of a verification experiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0030] (Embodiment 1) <Resin molding method> The technology of the present disclosure can be applied to general molding methods using molds made from resin materials. Specific examples of molding methods include injection molding, transfer molding, press molding, blow molding, vacuum molding, and pressure molding. Below, an overview of injection molding will be provided as an example of a molding method.

[0031] In this specification, the terms "resin" and "resin material" refer to a resin composition containing a resin raw material and, if necessary, any additives.

[0032] [Resin injection molding] Figure 1 is a diagram for explaining each step in resin injection molding and a graph showing an example of changes in mold pressure over time. Note that a workpiece W is shown in the upper left of Figure 1 as an example of a resin molded product.

[0033] As shown in FIG. 1, the resin injection molding process includes an injection step S51, a pressure holding step S52, and a cooling step S53.

[0034] First, a heated molten resin material is injected through a gate G into a cavity (not shown) formed by clamping a metal mold (casting die, not shown) (time A0 to A1, injection step S51).

[0035] When the entire cavity is filled with resin, in order to reduce the amount of excessive shrinkage of the resin due to the temperature drop, the injection of additional resin to apply pressure to the resin in the cavity is started. Then, while adjusting the amount of additional resin to be filled, the pressure inside the mold is maintained at a predetermined pressure (times A1 to A2, pressure holding step S52).

[0036] After a certain time or a certain amount of additional resin has been added, the addition of additional resin is stopped. As a result, the pressure inside the mold gradually decreases and eventually reaches atmospheric pressure (time A3). After being cooled inside the mold, the workpiece W is removed by opening the mold and then cooled in the air (cooling step S53).

[0037] The workpiece W thus obtained is cooled to room temperature and then goes through post-processing such as deburring to become a finished product.

[0038] 1, in the injection process S51 to the cooling process S53, the in-mold pressure varies depending on the location of the workpiece W. That is, in the first location W1, which is close to the gate G in the resin flow direction (MD direction), the in-mold pressure (solid line) reached in the dwelling process S52 is high, while in the second location W2, which is farther from the gate G, the in-mold pressure (dash-dotted line) reached in the dwelling process S52 is lower than that of the first location W1.

[0039] <Resin molded products> The resin molded product is not particularly limited as long as it is a molded product manufactured by the above-mentioned various molding methods. Specific examples of the resin molded product include automobile parts, rockets, aircraft parts, sporting goods, etc. Preferably, plate-shaped injection molded products such as interior and exterior components of vehicles are used. The resin molded product may also be an insert molded product.

[0040] The resin raw material is not particularly limited and may be any known resin. Specific examples include thermoplastic resins such as polypropylene resin, polyethylene resin, polyacetal resin, polyamide (PA) resin, polycarbonate resin, and polyester resin, and thermosetting resins such as phenol resin, epoxy resin, urethane acrylate resin, and unsaturated polyester resin. These resins may be used alone or in combination of two or more.

[0041] The resin may contain additives such as reinforcing fibers, fillers, pigments, dyes, impact modifiers, and UV absorbers. The reinforcing fibers are not particularly limited, and well-known fibers can be used, including, for example, glass fibers, carbon fibers, and cellulose nanofibers. These fibers can be used alone or in combination of two or more. The fiber diameter, fiber length, and content of the reinforcing fibers, as well as the specifications and content of other additives, are not particularly limited, and can be generally used conditions. These additives can be added alone or in combination.

[0042] <Analysis equipment for resin molded products> FIG. 2 shows a configuration example of an analysis device 100 for resin molded products (hereinafter also referred to as "analysis device 100") according to the present embodiment. The analysis device 100 is a CAE (Computer Aided Engineering) system basically configured with a computer 110. The analysis device 100 is a device that analyzes the behavior of resin during resin molding using a finite element method through computer simulation. In this specification, analysis of resin behavior refers to at least one of flow analysis and structural analysis (also referred to as "warpage analysis"). Flow analysis is a method of analyzing the flow behavior of resin in a molding method such as injection molding in which molten resin is injected into a cavity. Structural analysis is a method of analyzing the solidification behavior of resin in a cavity, regardless of the molding method. The analysis device 100 of FIG. 2 is merely an example of an analysis device for resin molded products according to the present disclosure, and the device configuration is not limited to this example.

[0043] The analysis device 100 includes a storage unit 120, such as a ROM, RAM, and hard disk, and a processor 130, such as a CPU. The analysis device 100 also includes a display unit 140, such as a display, an input unit 150, such as a keyboard, and a reading unit 160 for acquiring information stored on various recording media 170. The storage unit 120 and / or the recording media 170 store information such as programs for arithmetic processing and various analytical data. The processor 130 may function as a model creation unit, an analysis condition setting unit, a boundary condition acquisition unit, a heat transfer coefficient calculation unit, a resin property calculation unit, a contact state calculation unit, a boundary condition correction unit, and the like. The processor 130 performs various arithmetic processing based on the information stored in the storage unit 120, information input via the input unit 150, and information acquired from the recording media 170 via the reading unit 160. The analysis device 100 is configured to communicate with external devices via an interface (not shown).

[0044] The analysis device 100 uses a model creation unit to divide shape data, such as 3D CAD data, that defines the cavity of a mold into multiple tiny elements to create a finite element model for analysis. When both flow analysis and structural analysis are performed, the finite element model for flow analysis and the finite element model for structural analysis may be the same model or different models. A finite element model is also created for the mold and used for analysis. When creating a finite element model of a mold, for example, a finite element model of only the surface that forms the cavity of the mold may be created, or a finite element model of a part of the mold that includes that surface may be created.

[0045] The model creation unit can be a commercially available automatic mesh creation software, etc. Specific examples of the model creation unit that can be used include CAE preprocessors such as 3D TIMON (registered trademark)-Pre / Post manufactured by Toray Engineering D Solutions Co., Ltd., FEMAP (registered trademark) manufactured by NST Corporation, Patran (registered trademark) manufactured by MSC Software Co., Ltd., and Hypermesh (registered trademark) manufactured by Altair. The shape and size of the elements are not particularly limited and are set appropriately depending on the product specifications, material configuration, calculation efficiency, and calculation accuracy level.

[0046] The analysis condition setting unit sets the analysis conditions as prerequisites for the analysis, such as material property data regarding the type of resin, blend, additives, and various physical properties, molding conditions such as the initial resin temperature and, in the case of injection molding, the injection speed of the molten resin, and boundary conditions such as the initial heat transfer coefficient.

[0047] The boundary condition acquisition part is n Obtain the boundary conditions, including the heat transfer coefficient, used to calculate

[0048] The heat transfer coefficient calculation unit calculates the heat transfer coefficient at the interface between the cavity surface of the mold and the resin in the cavity, taking into account the mold pressure inside the mold. The method for calculating the heat transfer coefficient will be described in detail later.

[0049] The resin property calculation unit functions as at least one of a flow analysis unit and a structural analysis unit, and calculates the resin properties during the resin molding process. In this specification, the resin properties refer to physical quantities of the resin, such as the resin pressure (also referred to as "in-mold pressure" or "pressure distribution" in this specification), temperature (also referred to as "temperature distribution" in this specification), shear rate, specific volume, and amount of shrinkage, and include information on changes in these quantities over time.

[0050] For example, if the analysis is a flow analysis, the resin property calculation unit uses the finite element model for flow analysis based on the analysis conditions, the boundary conditions acquired by the boundary condition acquisition unit, and the like to perform resin flow analysis in each process, such as the injection process S51, the pressure holding process S52, and, if necessary, the cooling process S53 in the case of injection molding. The unit then calculates various data including resin property information such as resin pressure information (changes in pressure over time) and temperature information (changes in temperature over time) for each element and for each small time period. The calculated data is stored in the storage unit 120. In this case, the resin property calculation unit can be based on injection molding CAE software such as 3D TIMON (registered trademark) manufactured by Toray Engineering D Solutions, Inc.

[0051] Furthermore, if the analysis is a structural analysis, the resin property calculation unit uses the finite element model for structural analysis to perform structural analysis of the resin during the solidification and shrinkage process, such as the cooling step S53 in the case of injection molding, i.e., shrinkage behavior calculation (in-mold shrinkage behavior calculation and, if necessary, out-mold shrinkage behavior calculation after demolding), based on the analysis conditions, the boundary conditions acquired by the boundary condition acquisition unit, and, if a separate flow analysis or the like has been performed, resin temperature information, pressure information, heat transfer coefficient information, etc. obtained by the flow analysis or the like. The resin shrinkage amount is then calculated, and finally, the deformed shape and deformation amount of the molded product are calculated. In this case, the resin property calculation unit can be based on a solver such as Abaqus by Dassault Systèmes or 3D TIMON®-WARP by Toray Engineering D Solutions, Inc. The specific volume information, shrinkage amount information, deformed shape and deformation amount information, etc. obtained by the structural analysis are also stored in the memory unit 120.

[0052] The minute time is the analysis unit time for flow analysis and structural analysis, and is not particularly limited, but is set appropriately depending on the product specifications, material configuration, calculation efficiency, and calculation accuracy level.

[0053] The contact state calculation unit calculates the contact state between the cavity surface of the mold and the resin.

[0054] The boundary condition correction unit corrects the boundary condition at time step t based on at least the heat transfer coefficient calculated by the heat transfer coefficient calculation unit. n Modify the boundary conditions used in the calculation.

[0055] The details of the functions of each part will be described later in the section on analysis methods.

[0056] <Analysis method for resin molded products> 3 is a flowchart showing an example of a method for analyzing a resin molded product according to the present disclosure (hereinafter also referred to as "the present analysis method"). The present analysis method is a method for analyzing the behavior of resin during resin molding using a finite element method through computer simulation, and is performed using, for example, the above-mentioned analysis device 100.

[0057] 3 shows an example of a flow analysis performed in injection molding. The analysis method according to this embodiment will be described below using injection molding as an example, but as mentioned above, this analysis method can also be applied to other molding methods. Specifically, this analysis method includes, for example, a model creation step S1, an analysis condition setting step S2, a time step setting step S3, a boundary condition acquisition step S4 (heat transfer coefficient acquisition step), a resin property calculation step S5, a contact state calculation step S6, a heat transfer coefficient calculation step S7, a boundary condition correction step S9, and a time step determination step S10. An overview of each step is as follows:

[0058] [Model creation process, analysis condition setting process, time step setting process] First, in the model creation step S1, as described above, the model creation unit divides the shape data of the mold cavity created using 3D CAD or the like into minute elements for numerical analysis to create a flow analysis model. Next, in the analysis condition setting step S2, analysis conditions such as material condition data and boundary condition data are set as initial data. Then, in the time step setting step S3, the time information is set to the previous time step t n-1 The calculation is performed by advancing a small time Δt from the time step t n Set to.

[0059] [Boundary condition acquisition process] In the boundary condition acquisition step S4, the time step t n In the boundary condition acquisition step S4 for the first time step t1, the boundary condition data set in the analysis condition setting step S2 is read as the initial data.

[0060] [Resin property calculation process] In the resin property calculation step S5, the input information includes the initial flow velocity (injection velocity) of the resin, material data such as the dynamic viscosity coefficient of the resin material, shear viscosity, temperature, and specific volume, boundary conditions including the heat transfer coefficient, and specific volume, and the Navier-Stokes equation, continuity equation, etc. are used as governing equations to calculate the pressure and shear velocity of the resin for each element.In addition, the input information includes information such as the shear velocity of the resin, initial temperature (injection temperature) of the resin, specific heat, density, and thermal conductivity of the resin material, and the heat conduction equation, etc. are used as governing equations to calculate the temperature of the resin for each element.

[0061] [Contact state calculation process] In the contact state calculation step S6, the contact state of the resin with the cavity surface of the mold is calculated from the pressure information of the resin, the position of the flow front of the resin, and the like.

[0062] FIG. 4 is a diagram for explaining the relationship between the pressure inside the mold, the contact state at the interface between the mold cavity surface and the resin injected into the cavity, and the heat transfer mechanism described later.

[0063] As shown in Fig. 4, there are three possible contact states: (a) a state in which the flow front has not yet reached the cavity surface and the resin is not in contact with the cavity surface, (b) a state in which the flow front has reached the cavity surface and the resin is in contact with the cavity surface, and (c) a state in which the flow front has reached the cavity surface and the resin has contracted during the cooling process and separated from the cavity surface, resulting in a non-contact state.

[0064] Although not intended to be limiting, the following is a possible example of a method for calculating the contact state in flow analysis, in which a determination is made based on resin pressure information.

[0065] When the pressure p in the element in contact with the mold after the start of flow is in the state of p=0 before p>0, the calculation is performed as (a) above.

[0066] Furthermore, if the pressure p in the element that comes into contact with the mold after the flow starts is in a state of p>0, the calculation is performed as in (b) above.

[0067] Furthermore, if the pressure p in the element in contact with the mold after the start of flow becomes p>0 and then p=0, the calculation is performed as (c) above.

[0068] The contact state calculation step S6 is an optional step that is provided as needed, and may not be provided, for example, if the heat transfer coefficient is calculated using the same model formula when the in-mold pressure is zero (i.e., the above-mentioned (a) and (c)) in the heat transfer coefficient calculation step S7 described later.

[0069] [Heat transfer coefficient calculation process] In the heat transfer coefficient calculation step S7, the heat transfer coefficient at the interface between the cavity surface of the mold and the resin is calculated, taking into account the internal pressure of the mold.

[0070] As shown in Figure 4, in the case of (b) above (when p>0) where the resin is in contact with the cavity surface of the mold, heat transfer occurs from the resin, which is hotter than the mold, to the mold via the interface between the two in contact. As mentioned above, considering that the pressure inside the mold changes depending on the location of the workpiece W as shown in Figure 1, when p>0, it is assumed that the transfer of heat from the resin to the mold is affected by the pressure inside the mold. Q ri is the amount of heat transferred from the resin to the mold, A is the surface area of ​​the contact area between the resin and the mold, T r is the resin temperature, T m is the mold temperature, and the heat transfer coefficient when p>0 is h b Then, the amount of heat transferred from the resin to the mold per unit area is Q ri / A is Qri / A=-h b (T r -T m )

[0071] As a result of extensive research, the inventors of the present application have found that in actual molding, the heat transfer coefficient changes depending on the mold pressure. Specifically, Figure 5 shows the results of measurement experiment 1, which will be described later, to determine the pressure dependency of the heat transfer coefficient. As shown in Figure 5, it was found that the heat transfer coefficient increases as the punch die pressure (= mold pressure) increases. When fitting was performed on the results of Figure 5, the following approximate formula (1) was obtained.

[0072] h=A+B×ln(C×p+1) (1) (In equation (1), h is the heat transfer coefficient, p is the pressure inside the mold, and A, B, and C are coefficients.) Therefore, when the pressure inside the mold is greater than zero, the heat transfer coefficient h in the case of (b) above is calculated based on the above equation (1). b Then, the calculated heat transfer coefficient h b is reflected in the calculation of the next time step.

[0073] This allows analysis to be performed taking into account the pressure dependency of the heat transfer coefficient in the injection to cooling process based on measurement results under conditions that simulate actual molding, thereby improving analysis accuracy.

[0074] When the mold pressure in (a) and (c) above is zero (p=0), h=A in equation (1) and becomes a constant value. When p=0, the heat transfer coefficient may be set to a constant value in this way.

[0075] The coefficient A in formula (1) is not intended to be limited to any particular value, but can take a value of, for example, 0 to 3000, preferably 50 to 2000. The coefficient B in formula (1) is not intended to be limited to any particular value, but can take a value of, for example, 50 to 700, preferably 100 to 500. The coefficient C in formula (1) is not intended to be limited to any particular value, but can take a value of, for example, 1 to 500, preferably 5 to 250.

[0076] Furthermore, for example, as will be described below, the heat transfer coefficient may be made variable even when p=0.

[0077] Specifically, as shown in Figure 4, when the pressure inside the mold p is zero (p=0), it is thought that a gap exists / occurs between the resin and the mold due to the flow front not reaching the mold or due to the shrinkage of the resin. In this case too, the resin temperature is higher than the mold temperature, so heat transfer from the resin to the mold occurs. It is presumed that the amount of heat transferred is affected by the gap. The heat transfer coefficient in the above case (a) is h a Then, the amount of heat transferred from the resin to the mold per unit area is Q ri / A is Q ri / A=-h a (T r -T m ) The heat transfer coefficient in the above case (c) is expressed as h c Then, the amount of heat transferred from the resin to the mold per unit area is Q ri / A is Q ri / A=-h c (T r -T m )

[0078] As a result of extensive research, the inventors of the present application have found that in actual molding, the heat transfer coefficient changes depending on the gap size. Specifically, Figure 6 shows the results of measurement experiment 2, which will be described later, to determine the dependency of the heat transfer coefficient on the gap size. As shown in Figure 6, it was found that the heat transfer coefficient decreases as the tape thickness (= gap size) increases. When fitting was performed on the results of Figure 6, the following approximate formula (2) was obtained.

[0079] h=A×e D×s ···(2) (In equation (2), s is the gap between the cavity surface and the resin, and D is a coefficient.) Therefore, when the pressure inside the mold is zero, the heat transfer coefficient h in the cases (a) and (c) above is calculated based on the above formula (2). a , h c Calculate the heat transfer coefficient h a , h cmay be reflected in the calculation of the next time step.

[0080] This makes it possible to perform an analysis that takes into account the effects of the flow front not reaching the target in actual molding and the effects of resin shrinkage that occurs during the cooling process, etc., in the form of the gap volume dependency of the heat transfer coefficient, thereby further improving the accuracy of the analysis.

[0081] The coefficient D in the formula (2) can take a value of, for example, -20 to -1, preferably -10 to -2, although this is not intended to be limiting.

[0082] The gap volume s in equation (2) is not particularly limited, but can be calculated, for example, by determining the distance from the cavity surface to the surface of the resin in the normal direction based on the cavity surface, i.e., the distance in the plate thickness direction.

[0083] Specifically, the gap volume s can be calculated, for example, by the following formula (3).

[0084]

number

[0085] In equation (3), j is a subscript that indicates the jth element when counting sequentially from the cavity element in contact with the mold surface toward the cavity side in the plate thickness direction, F j is the F value obtained by the VOF (Volume of Fluid) method for the j-th element, and z is the thickness of one element in the plate thickness direction. The VOF method is a type of commonly known analysis method for free surface flow. The F value is expressed as a number between 0 and 1, and indicates the resin filling rate in each element (in other words, "1-F" indicates the void ratio in each element). Also, x is the F j <1 (1≦j≦x) and F j =1(j=x+1).

[0086] Specifically, as shown in Figure 7, consider the case of determining the gap amount s from element M1 on the cavity surface of mold M to resin W. Because no resin is present in the first element C1 to the third element C3 of the cavity that contact element M1, the F value is zero (F1 = F2 = F3 = 0). Resin W is present in a portion of element C4, and the F value F4 of element C4 is 0.4. Furthermore, because resin occupies the entire fifth element C5 where resin W is present, the F value F5 of element C5 is 1. In this case, x in the above formula (3) is 4, and the gap amount s is calculated based on formula (3) as s = 3 × (1 - 0) × z + (1 - 0.4) × z = 3.6z.

[0087] According to this configuration, the amount of the gap between the cavity surface and the resin surface can be calculated with high accuracy, thereby improving the accuracy of analysis.

[0088] In addition, when the mold pressure in (a) and (c) above is zero (p=0), regardless of the difference between (a) and (c), the heat transfer coefficient h can be calculated using equation (1) or (2). a , h c In this case, the contact state calculation step S6 may not be provided.

[0089] In addition, in either case (a) or (c), the heat transfer coefficient may be made constant by applying, for example, formula (1), and in the other case, the heat transfer coefficient may be made variable by applying, for example, formula (2). Specifically, for example, in the case (a), the heat transfer coefficient h a is set to a constant value, and in the case of (c) above, for example, equation (2) is applied to obtain the heat transfer coefficient h c In this case, the contact state calculation step S6 may be provided, and the model formula to be used in the heat transfer coefficient calculation step S7 may be selected based on the calculation results of (a), (b), and (c).

[0090] [Boundary condition modification process] In the boundary condition correction step S9, the time step t nThe value of the heat transfer coefficient acquired in the boundary condition acquisition step S4 is corrected to the value of the heat transfer coefficient calculated in the heat transfer coefficient calculation step S7.

[0091] In the boundary condition correction step S9, boundary conditions other than the heat transfer coefficient may also be corrected. Specifically, boundary conditions other than the heat transfer coefficient may also be corrected at the time step t n The boundary condition information may be calculated by performing internal calculations based on the resin property information such as pressure information and temperature information calculated in the resin property calculation step S5 and the contact state information calculated in the contact state calculation step S6. n The values ​​of the boundary conditions acquired in the boundary condition acquisition step S4 may be corrected to the values ​​of the boundary conditions calculated in the boundary condition correction step S9.

[0092] The modified boundary condition information, including the calculated heat transfer coefficient, is applied to the next time step t n+1 In the boundary condition acquisition step S4, the next time step t n+1 are taken as boundary conditions used in the calculation of

[0093] Although it is preferable to provide the boundary condition correction step S9, it is also possible to configure the system without providing this step, as will be described later in the section on other embodiments.

[0094] [Time step determination process] time step t n If the calculation of converges, the process proceeds to the time step determination step S10. n is set to the end of the analysis at time step t end Determine whether the time step t n t end If it is less than the predetermined value (NO), the process returns to the time step setting step S3, and the time step setting step S3 to the time step determination step S10 are repeated.

[0095] Then, at the next time step t n+1 In the boundary condition acquisition step S4, the time step t nThe modified boundary condition information including the heat transfer coefficient calculated in the heat transfer coefficient calculation step S7 is used for the next time step t n+1 is taken as the boundary condition used in the calculation.

[0096] In the time step determination step S10, the time step t n t end If the answer is YES, the flow analysis is terminated.

[0097] As described above, according to this analysis method, the heat transfer coefficient is calculated taking into account the mold pressure inside the mold, and the calculated heat transfer coefficient is reflected in the calculation for the next time step. This makes it possible to perform an analysis that takes into account changes in the heat transfer coefficient in actual phenomena, thereby improving the accuracy of the flow analysis.

[0098] Although not shown in Fig. 3, structural analysis may be performed using as input information the pressure information, temperature information, contact state information, heat transfer coefficient information, etc. obtained from the flow analysis in Fig. 3. This allows changes in heat transfer coefficients that correspond to actual phenomena to be reflected, improving the accuracy of the structural analysis.

[0099] <Analysis program for resin molded products and its recording medium> At least some of the steps of the present analysis method are programmed as a program for analyzing resin molded products. That is, the analysis program for resin molded products according to this embodiment is a program that causes a computer to execute at least the heat transfer coefficient calculation step among the steps described above. The analysis program may also be configured to execute other steps in addition to the heat transfer coefficient calculation step. Specifically, for example, the analysis program may be configured to execute the steps from the time step setting step S3 to the time step determination step S10, or the steps from the model creation step S1 to the time step determination step S10. This analysis program may be stored in, for example, the storage unit 120 and executed by the processor 130. The analysis program is not limited to being stored in the storage unit 120, but may also be recorded on various well-known computer-readable recording media, such as optical disk media or magnetic tape media. The analysis program can be executed by loading such a recording medium into the reading unit 160 and reading the analysis program.

[0100] (Embodiment 2) Other embodiments of the present disclosure will be described in detail below. In the description of these embodiments, the same parts as those in the first embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

[0101] <Analysis method for resin molded products> In the first embodiment, the present analysis method has been described using an example of flow analysis in injection molding as the analysis, but the present analysis method can also be applied to structural analysis. An example of the present analysis method applied to structural analysis is shown in Figure 8. Note that the following description of the analysis method according to this embodiment will use injection molding as an example, but as mentioned above, the present analysis method can also be applied to other molding methods.

[0102] In this case, the present analysis method is performed, for example, at a time step t nThe method may further comprise a shape and deformation amount calculation step S8, an out-of-mold shrinkage behavior calculation step S9, and a shape and deformation amount calculation step S12.

[0103] The steps other than those described above are generally similar to those of embodiment 1. Below, the steps that differ from embodiment 1 will be described.

[0104] [Model creation process and analysis condition setting process] In the model creation step S1, a model for structural analysis is created, and in the analysis condition setting step S2, analysis conditions for the structural analysis are set.

[0105] [Resin property calculation process] In the resin property calculation step S5, resin property information such as specific volume and shrinkage amount is calculated in addition to the pressure, temperature, etc. of the resin. Specifically, for example, in the heat transfer and stress analysis, which is part of the structural analysis, the temperature distribution of the resin is calculated using the heat conduction equation, etc., and the pressure distribution of the resin is calculated based on the generalized Hooke's law, etc. Furthermore, the specific volume is calculated using the temperature distribution and pressure distribution of the resin as input information and the Tait formula, etc. as the governing equation, and the shrinkage amount of the resin is calculated.

[0106] The information on the temperature and pressure distributions of the resin used to calculate the specific volume in the structural analysis may be information on the pressure and temperature distributions obtained separately by a flow analysis or the like. The flow analysis may be the flow analysis of embodiment 1, or a commonly known ordinary flow analysis. The pressure and temperature information obtained by the flow analysis of embodiment 1 is calculated taking into account changes in the heat transfer coefficient based on actual phenomena, so from the perspective of improving the accuracy of the analysis, it is preferable to use the pressure and temperature information obtained by the flow analysis of embodiment 1. In this case, as will be described later in the section on embodiment 3, the heat transfer coefficient will be calculated by both the flow analysis and the structural analysis.

[0107] [Contact state calculation process] Although not intended to be limiting, the following methods may be considered as examples of methods for calculating the contact state in structural analysis.

[0108] In the structural analysis, the case (a) described in the contact state calculation step of the first embodiment does not exist.

[0109] When the pressure p is in a state where p>0 in the element of the outermost layer of the resin in contact with the mold or the element of the outermost surface layer of the mold, the calculation is as in (b) above.

[0110] When the pressure p is p=0 in the element of the outermost layer of the resin in contact with the mold or the element of the outermost surface layer of the mold, the calculation is as in (c) above.

[0111] [time step t n Shape and deformation calculation process Data such as the shrinkage amount calculated in the resin property calculation step S5, the previous time step t n-1 Based on the shape of the workpiece at time step t n The change in shape and deformation of the workpiece are calculated.

[0112] [Out-of-mold shrinkage behavior calculation process] Although not intended to be limiting, in this embodiment, t end is set at the time of demolding, and the time step t n This calculation corresponds to the calculation of in-mold shrinkage behavior. Once the calculation of all time steps in the mold is completed, the calculation of out-mold shrinkage behavior is performed (out-mold shrinkage behavior calculation step S11). The calculation of out-mold shrinkage behavior is not particularly limited, and can be performed by a general structural analysis (warpage deformation analysis).

[0113] [Shape and deformation calculation process] Then, the final deformed shape and deformation amount are calculated from the shrinkage amount data obtained as a result of the in-mold shrinkage behavior calculation and the out-mold shrinkage behavior calculation (deformed shape and deformation amount calculation step S12).

[0114] According to this configuration, the change in the heat transfer coefficient based on the actual phenomenon can be reflected in the analysis, thereby improving the accuracy of the structural analysis.

[0115] <Analysis program for resin molded products and its recording medium> The analysis program according to this embodiment can be configured in the same manner as in the first embodiment, but may also be configured to execute each of the steps from the model creation step S1 to the shape and deformation amount calculation step S12 described above.

[0116] (Embodiment 3) <Analysis method for resin molded products> 9, the flow analysis of the first embodiment may be combined with the structural analysis of the second embodiment. Specifically, in a flow analysis step S101, the flow analysis of the first embodiment is performed, and the resulting resin property information such as pressure and temperature, contact state, boundary conditions (heat transfer coefficient), and other mold and resin data are stored in the storage unit 120. Then, in an analysis condition setting step S2 of the structural analysis step S102, the information obtained as a result of the flow analysis stored in the storage unit 120 is read, and the structural analysis of the second embodiment is performed.

[0117] The calculation of the heat transfer coefficient may be performed in either the flow analysis step S101 or the structural analysis step S102, or may be performed in both steps. Preferably, the heat transfer coefficient is calculated in both the flow analysis step S101 and the structural analysis step S102 in response to changes in pressure and gap volume.

[0118] Specifically, it is desirable to take into account, for example, gaps caused by resin shrinkage in the structural analysis. Furthermore, as shown in the area enclosed by the dashed line in Figure 10, as the warpage of the workpiece progresses in the cooling step S53, the workpiece W is partially pressed against the mold M inside the mold. This can cause new pressures that cannot be calculated by flow analysis. Therefore, in order to fully consider the pressures generated in the injection step S51 and the pressure holding step S52, as well as the gaps and pressure generation that occur in the cooling step S53, it is desirable to calculate the heat transfer coefficient in both the flow analysis step S101 and the structural analysis step S102.

[0119] Also, for example, the analysis of the first half of the injection process S51 to the cooling process S53 may be performed in the flow analysis process S101, and the analysis of the second half may be performed in the structural analysis process S102. The timing for switching from the flow analysis process S101 to the structural analysis process S102 is not intended to be limited, but examples include when the injection process is completed, when the pressure holding process is completed (when the cooling process starts), and during the pressure holding process. Also, a method of switching between processes for each element by defining thresholds such as the solidification rate of the resin and a value around the maximum pressure may be employed.

[0120] <Analysis program for resin molded products and its recording medium> The analysis program according to this embodiment may have the same configuration as that of the first and second embodiments, and may be configured to execute the procedures of the flow analysis step S101 and the structural analysis step S102.

[0121] (Other embodiments) In the above embodiment, the time step t n The value of the heat transfer coefficient calculated in the heat transfer coefficient calculation step S7 is calculated as the next time step t n For example, in the embodiment 3 including the flow analysis step S101 and the structural analysis step S102, the flow analysis step S101 does not include the boundary condition correction step S9, and the flow analysis step S101 is used for each time step t n The heat transfer coefficient may be calculated and stored in the storage unit 120, and the information on the heat transfer coefficient may be simply used as input information in the structural analysis step S102. [Example]

[0122] The specific experiments that were carried out are explained below. The resin materials used and assumed in Measurement Experiments 1 and 2 and the Verification Experiment, which will be described later, are as follows. In addition, injection molding was assumed and used as the molding method.

[0123] [material] As an actual sample, polypropylene (Prime Polypro (registered trademark) J708UG, manufactured by Prime Polymer Co., Ltd.) was used.

[0124] (Measurement Experiment 1) [Heat transfer coefficient measurement] Using a homemade heat transfer coefficient measuring device (see JP 2023-153704), we investigated the pressure dependence of the heat transfer coefficient of the above materials.

[0125] Specifically, using the heat transfer coefficient measuring device shown in Figs. 8 and 9 of JP 2023-153704 A, and using the measurement method described in the document (resin temperature: 200°C, mold temperature: 25°C), various pressures (0 MPa, 1 MPa, 5 MPa, and 10 MPa) were applied to the resin material by inserting a punch mold, and the mold temperature T r Changes over time and resin temperature T m The change over time in the heat transfer coefficient h was measured. From the results, the change over time in the heat transfer coefficient h was calculated using the following formula (4).

[0126] Q ri / A=-h(T r -T m ) ···(4) However, Q ri is the amount of heat transferred from the resin material to the mold, and A is the contact area between the mold and the resin material.

[0127] The average value of the change in the heat transfer coefficient h over time from 20 seconds to 120 seconds after the start of measurement was taken as the heat transfer coefficient h between the mold and resin at each applied pressure.

[0128] The relationship between pressure and heat transfer coefficient is shown in Fig. 5. As shown in Fig. 5, it was found that the heat transfer coefficient increases as the pressure increases. One of the reasons for this is thought to be that the increase in pressure crushes the microscopic voids between the metal surface and the resin, increasing the actual contact area.

[0129] The above-mentioned formula (1) was obtained as an approximation of the results in Figure 5. The coefficients A, B, and C in formula (1) were 142, 350, and 70, respectively.

[0130] (Measurement experiment 2) Using the same heat transfer coefficient measurement device as in Measurement Experiment 1 (resin temperature: 120°C, mold temperature: 25°C), tapes of various thicknesses were attached to positions between the mold and resin material that would not interfere with heat transfer to the thermocouple position, and the heat transfer coefficient between the mold and resin was calculated in the same way as in Measurement Experiment 1. The thickness of the tape, which corresponds to the amount of gap between the mold and resin, was set to three types: 0.05 mm, 0.1 mm, and 0.15 mm, simulating the amount of shrinkage in actual molding.

[0131] The relationship between the gap between the mold and resin (= tape thickness) and the heat transfer coefficient is shown in Figure 6. As shown in Figure 6, it was found that the heat transfer coefficient decreases as the gap increases.

[0132] Furthermore, since it is believed that the heat transfer coefficient converges to 0 as the gap volume increases, it can be inferred that the results in Figure 6 can be approximated by an exponential function related to the gap volume. From this, the above-mentioned equation (2) was obtained as an approximation of the results in Figure 6. The coefficients A and D in equation (2) were 142 and -4, respectively.

[0133] (Verification experiment) Regarding this analysis method, an experiment was conducted to verify the accuracy of prediction of the temperature and density of the resin.

[0134] <Example> -Analysis conditions- The examples and comparative examples were analyzed using a mold 300 having a spiral flow-shaped cavity 310 shown in FIGS.

[0135] As shown in FIG. 11, resin is poured from a resin inlet 301 and injected into a cavity 310 through a hot runner 302 and a gate 303 .

[0136] The detailed shape of the cavity 310 is as follows.

[0137] Width: 20 mm, plate thickness: 1 mm, pressure sensors 310A, 310B, 310C, 310D are provided at positions 60 mm, 90 mm, 180 mm, and 210 mm from 303. The arrows in Figure 12 indicate the flow direction of the resin (MD direction).

[0138] The analysis was carried out using general-purpose thermal fluid analysis software.

[0139] A layered solid mesh model divided into nine parts in the thickness direction was used as the flow analysis model.

[0140] The inflow and boundary conditions are shown in Table 1.

[0141] [Table 1]

[0142] The pressure dependency of the heat transfer coefficient was taken into consideration using the above-mentioned formula (1). The coefficients A, B, and C in formula (1) were set to 142, 350, and 70, respectively, based on the results in Figure 5.

[0143] -Material Data- For density, the two-domain Tait model expressed by the following equation (5) was used.

[0144]

number

[0145] The specific heat was set to 2800 J / kgK.

[0146] Regarding the solid viscosity, the flow stop temperature was arbitrarily set (130°C), and the solid viscosity below that temperature was 1.0 × 10 9 It was changed to [Pa·s].

[0147] For melt viscosity, the temperature change of the viscosity coefficient was taken into account using the Cross-WLF model formula shown in equation (6) below. The Cross-WLF model formula is a general model formula that can take into account the temperature and shear rate dependency of shear viscosity. Each coefficient with a numerical value is an input parameter that depends on the material.

[0148]

number

[0149] The thermal conductivity was set at an arbitrary time (100°C) when the material changed from molten to solid, and was set to 0.15 [W / mK] when molten and 0.3 [W / mK] when solid.

[0150] <Comparative Example> Heat transfer coefficient 5000W / m 2 The analysis was performed using the same configuration as in the example, except that K was set to a constant value.

[0151] <Reference example> Using the actual molds having the shapes shown in Figs. 11 and 12, actual molding of the reference example was carried out using the above materials and molding conditions.

[0152] <Result> FIG. 13 shows the change over time in the pressure inside the mold actually measured by the pressure sensor 310B, and the change over time in the heat transfer coefficient at the position of the pressure sensor 310B for the example and the comparative example.

[0153] 13, in the comparative example, the heat transfer coefficient was set to a constant value, whereas in the example, based on the above-mentioned formula (1), the heat transfer coefficient was set to a variable value when the in-mold pressure p was p>0. The change over time of the heat transfer coefficient in the example was consistent with the change over time of the in-mold pressure actually measured by pressure sensor 310B, demonstrating the validity of modeling the change in heat transfer coefficient using formula (1).

[0154] Figure 14 is a cross-sectional view taken along line aa in Figure 12, and shows the analysis results of resin temperature and density in the example and comparative example. Note that in Figure 14, the upper part shows the analysis results 2 seconds after the start of injection, and the lower part shows the analysis results 10 seconds after the start of injection, assuming that the injection / holding process occurs after 2 seconds and the cooling process occurs after 10 seconds.

[0155] There was no significant difference in resin temperature between the Examples and Comparative Examples, regardless of time. However, differences were observed in density between the Examples and Comparative Examples. First, it is known that the density distribution of injection-molded products is such that the density is higher on the inner side (core layer side) than on the outer side (skin layer side) in the thickness direction (ND) of the plate (Molding Processing Symposia (Preprints of Seikei-Kakou Autumnal Meeting), Volume: 2003, Pages: 299-300, Publication Year: November 3, 2003). Two seconds after the start of injection, there was a tendency for such a density distribution to be obtained in the Examples compared to the Comparative Examples. Furthermore, 10 seconds after the start of injection, the density distribution was remarkably reproduced in the Examples, while a nearly uniform density distribution in the ND direction was obtained in the Comparative Examples.

[0156] As described above, the analysis results in FIG. 14 show that in the example using this analysis method, the analysis accuracy is improved compared to the comparative example in which the heat transfer coefficient is a constant value. [Industrial Applicability]

[0157] The present disclosure is extremely useful because it can improve analysis accuracy by taking into account changes in heat transfer coefficients in actual phenomena in a method, an analysis device, an analysis program, and a recording medium for analyzing resin molded products. [Explanation of symbols]

[0158] 100 Resin molding analysis device 130 processor (boundary condition acquisition unit, heat transfer coefficient calculation unit, resin property calculation unit, contact state calculation unit, boundary condition correction unit) 170 Recording Media S4 Boundary condition acquisition process S5 Resin property calculation process S6 Contact state calculation process S7 Heat transfer coefficient calculation process S8 Boundary condition correction process

Claims

1. A method for analyzing a resin molded product by computer simulation, comprising: a heat transfer coefficient calculation step of calculating a heat transfer coefficient at an interface between a cavity surface of the mold and a resin in the mold, taking into account an internal pressure of the mold; In the heat transfer coefficient calculation step, when the in-mold pressure is greater than zero, the heat transfer coefficient is calculated based on the following formula (1): h=A+B×ln(C×p+1)...(1) (In equation (1), h is the heat transfer coefficient, p is the pressure inside the mold, and A, B, and C are coefficients.) A method for analyzing a resin molded product, comprising:

2. In claim 1, In the heat transfer coefficient calculation step, when the in-mold pressure is zero, the heat transfer coefficient is calculated based on the following formula (2): h=A×e Ｄ×ｓ ・・・(2) (In equation (2), s is the gap between the cavity surface and the resin, and D is a coefficient.) A method for analyzing a resin molded product, comprising:

3. In claim 1, a contact state calculation step of calculating a contact state between the cavity surface of the mold and the resin before the heat transfer coefficient calculation step; When the contact state calculation step determines that the contact state is a state in which the resin comes into contact with the cavity surface and then contracts, causing the resin to separate from the cavity surface and become non-contact, the heat transfer coefficient calculation step calculates the heat transfer coefficient based on the following formula (2): h=A×e Ｄ×ｓ ・・・(2) (In equation (2), s is the gap between the cavity surface and the resin, and D is a coefficient.) A method for analyzing a resin molded product, comprising:

4. In claim 2 or claim 3, The gap amount is expressed as the distance from the cavity surface to the surface of the resin in the normal direction based on the cavity surface. A method for analyzing a resin molded product, comprising:

5. In claim 1, Time step t ｎ a boundary condition acquisition step of acquiring boundary conditions including the heat transfer coefficient to be used in the calculation of Based on the boundary conditions, the time step t ｎ a resin characteristic calculation step of calculating resin characteristics including the in-mold pressure; The time step t ｎ and a boundary condition correction step of correcting the boundary conditions used in the calculation of the heat transfer coefficient calculation step is performed after the resin characteristic calculation step and before the boundary condition correction step, Next time step t ｎ＋１ In the boundary condition acquisition step, the modified boundary conditions are applied to the next time step t ｎ＋１ as the boundary conditions used in the calculation of A method for analyzing a resin molded product, comprising:

6. An apparatus for analyzing a resin molded product by computer simulation, a heat transfer coefficient calculation unit that calculates a heat transfer coefficient at an interface between a cavity surface of the mold and a resin in the mold, taking into account an internal pressure of the mold; The heat transfer coefficient calculation unit calculates the heat transfer coefficient based on the following formula (1) when the in-mold pressure is greater than zero: h=A+B×ln(C×p+1)...(1) (In equation (1), h is the heat transfer coefficient, p is the pressure inside the mold, and A, B, and C are coefficients.) 1. A resin molding analysis device comprising:

7. A program for analyzing a resin molded product by computer simulation, At a minimum, the computer a procedure for calculating a heat transfer coefficient at an interface between a cavity surface of the mold and a resin in the mold, taking into account the pressure inside the mold; In the above procedure, when the in-mold pressure is greater than zero, the heat transfer coefficient is calculated based on the following formula (1): h=A+B×ln(C×p+1)...(1) (In equation (1), h is the heat transfer coefficient, p is the pressure inside the mold, and A, B, and C are coefficients.) A program for analyzing resin molded products, comprising:

8. A computer-readable recording medium on which the resin molding analysis program according to claim 7 is recorded.

Images