JP2020095383A - Simulation device, simulation method, and program - Google Patents

Abstract

To model a region after a die exit and shorten a calculation time, in a simulation device.SOLUTION: A simulation device 100 simulates a flow of a rubber 1 ejected from a die flow channel 12. The simulation device 100 comprises: an input unit 140 which inputs information; a recording unit 160 which records information; a flow channel model creation unit 120 which creates a flow channel model 20 from the data input via the input unit 140 or the data read from the recording unit 160; and an arithmetic operation unit 130 which performs a simulation arithmetic operation of a fluid flow about the flow channel model 20. The flow channel model creation unit 120 comprises: a die flow channel region creation unit 121; an extrusion region creation unit 122; a connection region creation unit 123; a FEM modeling unit 124; and an analysis condition definition unit 125.SELECTED DRAWING: Figure 3

Description

The present invention relates to a simulation method, a simulation method, and a program.

If a problem occurs during the extrusion process of polymeric materials such as rubber, use simulation to identify the cause of the problem and check if there is a problem with the polymeric material flow in the die channel (pipe). It is effective to do. For example, Patent Document 1 discloses a simulation method of acquiring an optimum flow path shape by simulating a fluid flow in a pipeline.

JP, 2015-210776, A

By the way, it is known that when a polymer material is extruded into the atmosphere from an exit of a die, a die swell phenomenon (or a ballast effect) occurs in which a cross section of an extrudate becomes larger than a cross section of an exit of the die. In order to confirm the flow of polymer material in the die channel by simulation, it is important to reproduce the analytical model in a state close to the actual one. Therefore, it is preferable to reproduce the die swell phenomenon by modeling the area after the exit of the die in addition to the model of the die flow path.

In Patent Document 1, the die flow path is modeled to calculate the flow velocity distribution at the outlet, but there is no detailed reference to the die swell phenomenon. If an analysis model is created so as to simply reproduce the die swell phenomenon and a simulation is executed, the calculation time becomes very long.

An object of the present invention is to reduce the calculation time while modeling the area after the exit of a die in a simulation device, a simulation method, and a program.

A first aspect of the present invention is a simulation device for simulating a flow of a fluid extruded from a die flow path, which comprises an input unit for inputting information, a storage unit for recording information, and the input unit. The flow path includes a flow path model creating section that creates a flow path model based on input data or data read from the storage section, and an operation section that performs a simulation operation of a fluid flow for the flow path model. The model creating unit includes a die flow path region creating unit that creates a die flow path region that is a portion of the die flow path on the upstream side in the flow path model, and a final cross-sectional shape at the most downstream side in the flow path model. An extrusion area creation unit that creates an extrusion area formed by extruding the final cross-sectional shape that is defined to be larger than the cross section of the die flow path in the flow path model, and the die flow in the flow path model. A connection area creating unit that creates a connection area that connects the road area and the extrusion area, and the FEM model by dividing the die channel area, the extrusion area, and the connection area into a finite number of elements for analysis. There is provided a simulation apparatus including an FEM modeling unit that creates a model and an analysis condition definition unit that defines an analysis condition in the FEM model.

According to this configuration, since the final cross-sectional shape of the flow channel model is defined to be larger than the cross section of the die flow channel, the die swell phenomenon can be reproduced. Moreover, since the final cross-sectional shape of the most downstream in the fluid flow is defined in advance, it is possible to shorten the time until the calculation converges. Further, since the connection area is provided, it is possible to prevent the presence of discontinuous analysis points from the die flow path area on the upstream side to the extrusion area on the downstream side. Therefore, since a stable simulation can be performed, the behavior of the fluid in the die channel region can be analyzed.

The final cross-sectional shape may be based on the actually measured shape.

According to this configuration, since the final cross-sectional shape is based on the actually measured shape, it is possible to perform highly accurate analysis close to an actual phenomenon.

The outer surface defining the connection area may be a flat surface.

According to this configuration, since a simple shape is set as the connection region, the flow path model can be easily created, and the calculation time required for analysis can be shortened.

The outer surface defining the connection area may be a curved surface.

According to this configuration, since the shape close to the actual phenomenon can be set as the connection region, the analysis accuracy can be improved. Generally, in the die swell phenomenon, the fluid does not expand linearly (primarily) after being extruded from the exit of the die, but rather expands in a higher order. Therefore, preferably, the outer surface shape of the connection region is set to a curved surface shape according to the expansion of the fluid.

The outer surface that defines the connection area has a first curved surface that forms a smooth curved surface that is convex inward without forming a corner at the connection portion with the die flow channel area, and the connection portion between the extrusion area. In (2), a second curved surface that forms a smooth curved surface that is convex outward without forming a corner may be provided.

According to this structure, the connecting portion between the die flow path region and the connecting region is formed by the first curved surface, and the connecting portion between the connecting region and the extruding region is formed by the second curved surface. In particular, since the first curved surface is convex inside the connection region, the die channel region and the connection region are smoothly connected. Similarly, since the second curved surface is convex outward, the connection area and the extrusion area are smoothly connected. Therefore, it is possible to prevent the occurrence of discontinuous points that may make analysis impossible in the portion connecting the regions, and prevent the divergence of calculation.

The first curved surface may have a smaller curvature than the second curved surface.

With this configuration, the die swell phenomenon at the die exit can be reproduced more accurately. Generally, in the die swell phenomenon, a fluid expands largely near the exit of the die after being pushed out from the exit of the die. When the first curved surface near the die exit has a smaller curvature than the second curved surface downstream thereof, the expansion amount near the die exit can be set to be large. Therefore, the expansion state of the die swell phenomenon can be accurately reproduced.

A second aspect of the present invention is a simulation method for simulating a flow of a fluid extruded from a die flow channel, which is a flow channel model based on data input via an input unit or data read from a storage unit. And performing a simulation calculation of a fluid flow with respect to the flow path model, the creation of the flow path model includes a die flow path region that is a portion of the die flow path on the upstream side in the flow path model. An extrusion region formed by extruding the final cross-sectional shape that is the most downstream final cross-sectional shape in the flow path model and is defined to be larger than the cross section of the die flow path in the flow path model to the upstream side. To create a connection area that connects the die flow area and the extrusion area in the flow path model, and a finite number of the die flow area, the extrusion area, and the connection area for analysis. A simulation method is provided that includes dividing into elements to create an FEM model and defining analysis conditions in the FEM model.

The final cross-sectional shape may be based on the actually measured shape.

The outer surface defining the connection area may be a flat surface.

The outer surface defining the connection area may be a curved surface.

The outer surface that defines the connection area has a first curved surface that forms a smooth curved surface that is convex inward without forming a corner at the connection portion with the die flow channel area, and the connection portion between the extrusion area. In (2), a second curved surface that forms a smooth curved surface that is convex outward without forming a corner may be provided.

The first curved surface may have a smaller curvature than the second curved surface.

A third aspect of the present invention provides a program that causes a computer to execute the simulation method when loaded into a control unit of the computer.

According to the present invention, the flow path model defining the final cross-sectional shape is created in the simulation device, the simulation method, and the program, so that the area after the die exit can be modeled and the calculation time can be shortened.

FIG. 3 is a perspective view showing rubber extruded from a die. A flow path model that reproduces the rubber flow path in Fig. 1. The block diagram of the simulation device concerning one embodiment of the present invention. 4 is a flowchart showing a process executed by the simulation device of FIG. The flowchart which shows the subroutine regarding the flow path model creation of FIG. The perspective view of the shape data of a flow path model. The side view of the shape data of a flow path model. Sectional drawing of the shape data of the flow path model in each area|region. The perspective view of a FEM model. The side view of the flow path model of the 1st modification. The side view of the flow path model of the 2nd modification. The side view of the flow path model of the 3rd modification.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

The simulation device of the present embodiment analyzes the flow of rubber (an example of a fluid) that is a material for a tire of an automobile or the like. However, the following description is an exemplification, and the simulation device can be used for analyzing various fluid flows other than the analysis of the rubber flow.

Referring to FIG. 1, a rubber 1 is extruded from an outlet 11 of a die 10 that forms a die flow passage 12 inside after mixing a plurality of kinds of materials by a kneader (not shown), and is used in accordance with each part of a tire. Molded in various thicknesses and widths. In this embodiment, since the outlet 11 of the die 10 has a rectangular shape, the rubber 1 to be extruded has a substantially rectangular cross-sectional shape. However, to be precise, the rubber 1 expands when it exits the outlet 11 of the die 10 due to the die swell phenomenon, and the rectangular shape is not maintained. In this embodiment, the flow of the rubber 1 extruded from the die flow path 12 is analyzed, but the flow path model 20 (see FIG. 2) imitating the flow of the rubber 1 in which the die swell phenomenon is taken into consideration is used for the analysis. .. In addition, in the following part of the description, in order to simplify the illustration and the description, it is assumed that only the upper portion in the thickness direction of the rubber 1 is expanded due to the die swell phenomenon. Expands.

FIG. 2 is a perspective view showing an example of the flow path model 20 used in the analysis. The flow path model 20 of FIG. 2 imitates the flow of the rubber 1 of FIG. The flow channel model 20 has a die flow channel region 21, an extrusion region 22, and a connection region 23 that connects them.

The die flow channel region 21 is a reproduction of the die flow channel 12 (see FIG. 1). The die flow channel region 21 is a region on the upstream side in the flow channel model 20. In the present embodiment, the cross section of the die flow channel 12 perpendicular to the flow direction of the rubber 1 (see arrow A in FIG. 1) is rectangular. The die channel region 21 has a thickness of, for example, about 3 to 40 mm. However, the cross-sectional shape of the die flow channel region 21 is not limited to a rectangular shape, and may be various shapes such as a triangular shape, a rhombic shape, or a trapezoidal shape. Therefore, the thickness of the die flow path region 21 is not necessarily 3 mm or more, and when there is an acute angle portion, a value such as 1 mm can be partially taken.

The extrusion region 22 is a region on the downstream side in the flow path model 20. In the extrusion region 22, the most downstream final cross-sectional shape F in the flow direction of the rubber 1 (see the arrow A in FIG. 1) is defined. The final cross-sectional shape F is shown by hatching in FIG. The final cross-sectional shape F is one in which the dimensions of the cross-sectional shape when the rubber 1 is actually extruded from the die 10 in advance are measured by using a caliper or a laser measuring machine and the shape is reproduced. That is, the final cross-sectional shape F is based on the actually measured shape.

The extrusion region 22 has a constant cross-sectional shape in the flow direction of the rubber 1 (see arrow A in FIG. 1). Therefore, when creating the shape data of the extrusion region 22, the final cross-sectional shape F is extruded toward the upstream side to form the extrusion region 22. The extrusion area 22 is an area outside the die 10 (see FIG. 1). Therefore, the thickness of the extrusion region 22 is set larger than that of the die flow passage region 21 in order to reproduce the die swell phenomenon, and is, for example, about 3 to 80 mm. However, as described above, there may be a portion having a thickness of, for example, about 1 mm depending on the sectional shape. The length of the extruded region 22 is, for example, about 1 to 100 mm.

The connection area 23 is an area that connects the die flow path area 21 and the extrusion area 22. Therefore, the connection region 23 is a region outside the die 10 and is affected by the die swell phenomenon. Therefore, the connection region 23 is formed so that the cross-sectional shape gradually increases from the upstream side to the downstream side in the flow direction of the rubber 1 (see the arrow A in FIG. 1 ). In the present embodiment, the outer surface that defines the connection region 23 is the flat surface 23a. Therefore, the connection region 23 is formed such that the cross-sectional shape linearly increases from the upstream side to the downstream side in the flow direction of the rubber 1 (see the arrow A in FIG. 1 ). However, the outer surface that defines the connection region 23 is not limited to a flat surface, that is, the outer surface is not limited to one having a linearly large cross-sectional shape. The connection area 23 may have an alternative shape as shown in the first to third modified examples described later. The length of the connection region 23 is, for example, about 0.1 to 10 mm.

FIG. 3 is a block diagram of the simulation apparatus 100 of this embodiment. The simulation apparatus 100 includes a control unit (processor) 110, an input unit 140 for inputting information, a display unit 150 for displaying information, and a storage unit 160 for recording information. The control unit 110 performs arithmetic processing and control of the entire device. The input unit 140 is a unit that generates or receives input data for the simulation apparatus 100, and is configured by, for example, a keyboard, a mouse, a touch panel, or the like. The display unit 150 is a unit that displays the processing result and the like by the control unit 110, and is configured by, for example, a liquid crystal display, an organic EL display, a plasma display, or the like. The storage unit 160 stores parameter data and the like necessary for a program running on the control unit 110. The control unit 110, the input unit 140, the display unit 150, and the storage unit 160 are connected to each other. The simulation device 100 is configured by an information processing device such as a desktop personal computer, a notebook computer, a workstation, or a tablet terminal.

The control unit 110 creates the shape of the flow path model 20 and defines the analysis conditions of the flow path model 20, and the flow path model 20 created by the rubber 1 (see FIG. 1). And a calculation unit 130 that performs a simulation calculation of the flow. The flow channel model creation unit 120 creates the flow channel model 20 including the die flow channel 12 based on the data input via the input unit 140 or the data read from the storage unit 160.

The flow channel model creation unit 120 includes a die flow channel region creation unit 121, an extrusion region creation unit 122, a connection region creation unit 123, an FEM modeling unit 124, and an analysis condition definition unit 125. The flow path model creation unit 120 and the calculation unit 130 are realized by cooperation of the control unit 110 as a processor which is a hardware resource and a program which is software stored in the storage unit 160.

The die flow channel region creating unit 121 creates a die flow channel region 21 (see FIG. 2) that reproduces a portion of the upstream die flow channel 12 (see FIG. 1) in the flow channel model 20. The extrusion region creation unit 122 creates the extrusion region 22 (see FIG. 2) from the final cross-sectional shape F at the most downstream side in the flow path model 20 as described above. The connection area creation unit 123 creates the connection area 23 (see FIG. 2) with the outer surface being, for example, a flat surface as described above.

As will be described later with reference to FIG. 9, the FEM modeling unit 124 divides the obtained die channel region 21, extrusion region 22, and connection region 23 into a finite number of elements to create an FEM model for analysis. To do. The conditions for element division are input by the input unit 140 or stored in the storage unit 160 in advance. For example, conditions such as the shape and size of the divided elements are set appropriately.

The analysis condition definition unit 125 defines analysis conditions for the FEM model. The analysis conditions include various boundary conditions and physical property values. For example, as an inflow condition, the mass flow rate and volume flow rate of the rubber 1 at the inlet of the die 10, conditions such as the presence or absence of slip on the wall surface inside the die 10, and the flow The material properties of the rubber 1 and the like are included. These analysis conditions are also input by the input unit 140 or stored in the storage unit 160 in advance.

4 and 5 are flowcharts showing the processing executed by the simulation apparatus 100.

Referring to FIG. 4, when the process is started (step S4-1), first, the flow path model creating unit 120 creates the flow path model 20 (step S4-2). The creation of the flow path model 20 will be described later with reference to FIG. Next, the analysis condition definition unit 125 defines the analysis conditions for the created flow path model 20 (step S4-3). Next, the calculation unit 130 analyzes the flow path model 20 created in this way (step S4-4). The analysis is executed until the calculation result converges, and when the analysis is not completed (NO: step S4-5), the condition is reset as necessary (step S4-6) and the analysis is performed (step S4). -4). In the final sectional shape F, when the atmospheric pressure and the expansion force of rubber are in a balanced relationship, that is, when the calculation result converges and the analysis is completed (YES: step S4-5), the result is output to the display unit 150 (step S4). -7), and the process ends (step S4-8). The results output to the display unit 150 are, for example, the velocity component and pressure value of the flow of the rubber 1 in each part of the flow path model 20. Therefore, the user can confirm the flow and the like in the die flow channel region 21 which cannot be visually recognized from the outside through the display unit 150.

The procedure for creating the flow path model 20 in step S4-2 of FIG. 4 will be described with reference to FIG. First, FIG. 6 shows the shape data of the created flow path model 20. The shape data of the flow path model 20 of FIG. 6 is a shape that is more practical than the schematic flow path model 20 shown in FIG. 2 described above. As described above, the flow channel model 20 includes the die flow channel region 21, the connection region 23, and the extrusion region 22. FIG. 7 shows a side surface of the flow path model 20, and FIG. 8 shows a comparison of sectional shapes of the regions 21 to 23.

As shown in FIG. 7, in the die flow channel region 21 and the extrusion region 22, the flow channel model 20 has a constant thickness. In the connection region 23, the thickness linearly increases. That is, the outer surface that defines the connection region 23 is a flat surface. In each cross-sectional shape shown in FIG. 8, the upper diagram shows the die flow channel region 21, the central diagram shows the connection region 23, and the lower diagram shows the extrusion region 22. The cross-sectional shape is larger in the downstream region, and it can be confirmed that the die swell phenomenon is reproduced. In particular, the die flow path region 21 has a rectangular cross-sectional shape, the connection region 23 has a rectangular cross-sectional shape, and the extrusion region 22 has a rectangular cross-sectional shape in which each side, particularly the central portion, has a shape bulging outward. ing.

Referring again to FIG. 5, when creating the flow path model 20, first, the extrusion region creation unit 122 creates the extrusion region 22 from the final cross-sectional shape F (step S5-1). Next, the die flow channel region creating unit 121 creates the die flow channel region 21 that reproduces the die flow channel 12 (see FIG. 1) (step S5-2). Then, the connection area 23 is created by the connection area creating unit 123 so that the die flow path area 21 and the extrusion area 22 are connected by the flat surface 23a (step S5-3). In this way, the shape data of the flow path model 20 is created. Either the creation of the extrusion area 22 (step S5-1) or the creation of the die channel area 21 (step S5-2) may be performed first.

After the shape data of the flow path model 20 is created as described above, the FEM modeling unit 124 then divides the shape data of the flow path model 20 into a finite number of elements for analysis as shown in FIG. Then, an FEM model is created (step S5-4). The flow path model (FEM model) 20 created in this way is analyzed as described above.

The simulation device 100 of the present embodiment has the following advantageous effects.

Since the final cross-sectional shape F of the flow channel model 20 is defined to be larger than the cross section of the die flow channel 12, the die swell phenomenon can be reproduced. Further, since the final cross-sectional shape F at the most downstream side in the flow of the rubber 1 is defined in advance, it is possible to shorten the time until the calculation converges. Further, since the connection region 23 is provided in the flow path model 20, it is possible to prevent the presence of discontinuous analysis points from the die flow area 21 on the upstream side to the extrusion area 22 on the downstream side. Therefore, since a stable simulation can be executed, the behavior of the fluid in the die flow channel region 21 can be analyzed.

Particularly in the present embodiment, since the final cross-sectional shape F is based on the actually measured shape, it is possible to perform highly accurate analysis close to an actual phenomenon. However, if necessary, the actual measurement may be omitted and the final cross-sectional shape F may be defined by the estimated dimension or the like.

The outer surface that defines the connection area 23 is a flat surface 23a, and the connection area 23 has a simple shape. Therefore, the flow path model 20 can be easily created, and the calculation time required for analysis can be shortened.

(First modification)
FIG. 10 shows a first modified example of the flow path model 20, corresponding to FIG. 7. In particular, a part of the connection region 23 is shown enlarged in a broken line circle. As shown in FIG. 10, the outer surface defining the connection area 23 may be a curved surface. For example, in this modification, the outer surface that defines the connection region 23 is an arc surface.

According to this modified example, the connection region 23 can be set to a shape close to an actual phenomenon, so that the analysis accuracy can be improved. Generally, in the die swell phenomenon, the rubber 1 does not expand linearly (primarily) after being extruded from the outlet 11 of the die 10, but expands in a higher order. Therefore, preferably, the outer surface shape of the connection region 23 is set to a curved surface shape according to the expansion of the rubber 1.

(Second modified example)
FIG. 11 shows a second modified example of the flow path model 20, corresponding to FIG. 7. In particular, a part of the connection region 23 is shown enlarged in a broken line circle. As shown in FIG. 11, the outer surface that defines the connection region 23 is a first curved surface 23b that forms a smooth curved surface that is convex inward without forming a corner at the connection portion with the die flow channel region 21. The second curved surface 23c that forms a smooth curved surface that is convex outward without forming a corner portion at the connection portion with the extrusion region 22 may be provided. In this modification, the first curved surface 23b and the second curved surface 23c are both arcuate surfaces having the same curvature.

According to this modification, the connecting portion between the die flow passage region 21 and the connecting region 23 is formed by the first curved surface 23b, and the connecting portion between the connecting region 23 and the extruding region 22 is formed by the second curved surface 23c. It In particular, since the first curved surface 23b is convex to the inside of the connection region 23, the die flow channel region 21 and the connection region 23 are smoothly connected. Similarly, since the second curved surface 23c is convex outward, the connection area 23 and the extrusion area 22 are smoothly connected. Therefore, it is possible to prevent the occurrence of discontinuous points that may make analysis impossible in the portion connecting the regions 21 to 23, and prevent the divergence of calculation.

(Third modification)
FIG. 12 shows a third modified example of the flow path model 20, corresponding to FIG. 7. In particular, a part of the connection region 23 is shown enlarged in a broken line circle. As shown in FIG. 12, the curvature of the first curved surface 23b may be changed from the connection region 23 (see FIG. 11) of the second modified example, or the curvature of the second curved surface 23c may be changed. For example, in this modification, the curvature of the first curved surface 23b is made smaller and the curvature of the second curved surface 23c is made larger than in the second modification. Therefore, in this modification, the first curved surface 23b has a smaller curvature than the second curved surface 23c.

According to this modification, the die swell phenomenon at the outlet 11 of the die 10 can be reproduced more accurately. Generally, in the die swell phenomenon, the fluid is largely extruded near the outlet 11 of the die 10 after being extruded from the outlet 11 of the die 10. When the first curved surface 23b near the outlet 11 of the die 10 has a smaller curvature than the second curved surface 23c downstream thereof, the expansion amount near the outlet 11 of the die can be set to be large. Therefore, the expansion state of the die swell phenomenon can be accurately reproduced. Further, similarly to the second modified example, since the regions 21 to 23 are smoothly connected, it is possible to prevent calculation divergence.

Although specific embodiments of the present invention and modifications thereof have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention.

1 Rubber 10 Die 11 Outlet 12 Die Channel 20 Channel Model 21 Die Channel Area 22 Extrusion Area 23 Connection Area 23a Flat Surface 23b First Curved Surface 23c Second Curved Surface 100 Simulation Device 110 Control Unit (Processor)
120 flow path model creation unit 121 die flow path area creation unit 122 extrusion area creation unit 123 connection area creation unit 124 FEM modeling unit 125 analysis condition definition unit 130 calculation unit 140 input unit 150 display unit 160 storage unit

Claims (13)

A simulation device for simulating a flow of a fluid pushed out from a die flow channel, comprising: an input unit for inputting information, a storage unit for recording information, and data input via the input unit or the storage unit. A flow path model creation unit that creates a flow path model based on the read data, and a calculation unit that performs a simulation calculation of a fluid flow for the flow path model,
The flow path model creation unit,
In the flow path model, a die flow path area creating unit that creates a die flow path area that is a portion of the die flow path on the upstream side,
A final cross-sectional shape of the most downstream in the flow path model, and an extrusion area creation unit that creates an extrusion area formed by extruding the final cross-sectional shape defined to be larger than the cross section of the die flow path to the upstream side. ,
A connection area creating unit that creates a connection area that connects the die flow area and the extrusion area in the flow path model,
An FEM modeling unit that creates an FEM model by dividing the die channel region, the extrusion region, and the connection region into a finite number of elements for analysis;
An analysis condition definition unit that defines an analysis condition in the FEM model. The simulation device according to claim 1, wherein the final cross-sectional shape is based on an actually measured shape. The simulation device according to claim 1, wherein the outer surface that defines the connection region is a flat surface. The simulation device according to claim 1, wherein the outer surface that defines the connection region is a curved surface. The outer surface defining the connection area is
A first curved surface that forms a smooth curved surface that is convex inward without forming a corner at a connection portion with the die channel region;
The simulation device according to claim 4, further comprising: a second curved surface that forms a smooth curved surface that is convex outward without forming a corner portion at a connection portion with the extrusion region. The simulation device according to claim 5, wherein the first curved surface has a curvature smaller than that of the second curved surface. A simulation method for simulating the flow of fluid extruded from a die channel,
Create a flow path model with data input via the input unit or data read from the storage unit,
Performing a simulation calculation of a fluid flow for the flow channel model,
Creation of the flow path model,
In the flow channel model, create a die flow channel region that is a portion of the die flow channel on the upstream side,
The final cross-sectional shape of the most downstream in the flow path model, to create an extrusion region formed by extruding the final cross-sectional shape is defined to be larger than the cross section of the die flow path to the upstream side,
Create a connection area that connects the die flow area and the extrusion area in the flow path model,
Creating a FEM model by dividing the die channel region, the extrusion region, and the connection region into a finite number of elements for analysis,
A simulation method including defining an analysis condition in the FEM model. The simulation method according to claim 7, wherein the final cross-sectional shape is based on an actually measured shape. The simulation method according to claim 7, wherein the outer surface that defines the connection region is a flat surface. The simulation method according to claim 7, wherein the outer surface that defines the connection region is a curved surface. The outer surface defining the connection area is
A first curved surface that forms a smooth curved surface that is convex inward without forming a corner at a connection portion with the die channel region;
The simulation method according to claim 10, further comprising: a second curved surface that forms a smooth curved surface that is convex outward without forming a corner at a connection portion with the extrusion region. The simulation method according to claim 11, wherein the first curved surface has a curvature smaller than that of the second curved surface. A program that, when loaded into a control unit of a computer, causes the computer to execute the simulation method according to any one of claims 7 to 12.

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