JP7152286B2 - SIMULATION APPARATUS, SIMULATION METHOD, AND PROGRAM - Google Patents

Description

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

When a failure occurs in the extrusion process of polymeric materials such as rubber, simulation is used to check for problems with the flow of polymeric materials in the die channels (pipes) to identify the cause of the failure. It is effective to For example, Patent Literature 1 discloses a simulation method for obtaining an optimum flow path shape by simulating the flow of fluid in a pipeline.

JP 2015-210776 A

By the way, it is known that when a polymeric material is extruded into the atmosphere from a die outlet, a die swell phenomenon (or ballast effect) occurs in which the cross section of the extrudate becomes larger than the cross section of the die outlet. 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 state. Therefore, it is preferable to model the area after the exit of the die in addition to the model of the die flow path to reproduce the die swell phenomenon.

In Patent Document 1, the die flow path is modeled and the flow velocity distribution at the outlet is calculated, but there is no detailed mention of the die swell phenomenon. If an analysis model is simply created to reproduce the die swell phenomenon and a simulation is executed, the calculation time will be extremely long.

An object of the present invention is to model the area after the exit of the die and to shorten the calculation time in a simulation apparatus, simulation method, and program.

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

According to this configuration, the die swell phenomenon can be reproduced because the final cross-sectional shape of the flow path model is defined to be larger than the cross section of the die flow path. In addition, since the final cross-sectional shape of the most downstream of the fluid flow is defined in advance, the time until the calculation converges can be shortened. Moreover, since the connection area is provided, it is possible to prevent the presence of discontinuous analysis points from the upstream die flow path area to the downstream extrusion area. 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 a 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 the 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 area, the flow path model can be easily created, and the calculation time associated with the analysis can be shortened.

The outer surface defining the connection area may be curved.

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

The outer surface that defines the connection region is a first curved surface that forms a smooth curved surface that is convex inward without forming corners at the connection portion with the die flow path region, and the connection portion with the extrusion region. and a second curved surface that forms a smoothly curved surface that is outwardly convex without forming corners.

According to this configuration, 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 extrusion region is formed by the second curved surface. In particular, the die flow path area and the connection area are smoothly connected because the first curved surface is convex toward the inside of the connection area. Similarly, since the second curved surface is outwardly convex, the connection area and the extruded area are smoothly connected. Therefore, it is possible to prevent the occurrence of discontinuous points that may make analysis impossible at the portion connecting the regions, and to prevent the divergence of calculations.

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, the fluid expands greatly near the exit of the die after being pushed out from the exit of the die. If the first curved surface near the die exit has a smaller curvature than the second curved surface downstream therefrom, the amount of expansion near the die exit can be set large. Therefore, the expansion state of the die swell phenomenon can be reproduced accurately.

A second aspect of the present invention is a simulation method for simulating the flow of a fluid extruded from a die channel, wherein a channel model is generated by data input via an input unit or data read from a storage unit. and performing fluid flow simulation calculations on the flow channel model, wherein the creation of the flow channel model includes a die flow channel region that is a portion of the die flow channel on the upstream side in the flow channel model An extruded region formed by extruding the final cross-sectional shape, which is the most downstream final cross-sectional shape in the flow channel model and is defined to be larger than the cross-section of the die flow channel in the flow channel model, to the upstream side. is created, a connection area that connects the die flow path area and the extrusion area in the flow path model is created, and the die flow path area, the extrusion area, and the connection area are a finite number for analysis A simulation method is provided, including 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 a measured shape.

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

The outer surface defining the connection area may be curved.

The outer surface that defines the connection region is a first curved surface that forms a smooth curved surface that is convex inward without forming corners at the connection portion with the die flow path region, and the connection portion with the extrusion region. and a second curved surface that forms a smoothly curved surface that is outwardly convex without forming corners.

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 is loaded into a control unit of a computer to cause the computer to execute the simulation method.

According to the present invention, the simulation apparatus, simulation method, and program create a channel model that defines the final cross-sectional shape, so that the area after the exit of the die can be modeled and the calculation time can be shortened.

The perspective view which shows the rubber|gum extruded from die|dye. A channel model that reproduces the rubber channel in Fig. 1. 1 is a block diagram of a simulation device according to one embodiment of the present invention; FIG. 4 is a flowchart showing processing executed by the simulation apparatus of FIG. 3; FIG. 5 is a flow chart showing a subroutine for channel model creation in FIG. 4 ; FIG. The perspective view of the shape data of a channel model. The side view of the shape data of a channel model. Sectional drawing of the shape data of the flow-path model in each area|region. A perspective view of the FEM model. The side view of the flow-path model of a 1st modification. The side view of the flow-path model of a 2nd modification. The side view of the flow-path model of a 3rd modification.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

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

Referring to FIG. 1, rubber 1 is mixed with a plurality of types of materials by a kneader (not shown), and then extruded from outlet 11 of die 10 forming die flow path 12 therein, and is mixed with each part of the tire. It is molded in various thicknesses and widths. In this embodiment, since the outlet 11 of the die 10 is rectangular, the cross-sectional shape of the extruded rubber 1 is also substantially rectangular. However, to be precise, the rubber 1 expands due to the die swell phenomenon when coming out of the outlet 11 of the die 10, 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, and the analysis is performed using a flow path model 20 (see FIG. 2) that imitates the flow of the rubber 1, especially considering the die swell phenomenon. . In the following description, for the sake of simplicity of illustration and description, it is assumed that only the upper portion of the rubber 1 expands due to the die swell phenomenon in the thickness direction. directionally inflated.

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

Die channel region 21 is a reproduction of die channel 12 (see FIG. 1). The die channel region 21 is an upstream region in the channel model 20 . In this embodiment, the cross section of the die channel 12 perpendicular to the flow direction of the rubber 1 (see arrow A in FIG. 1) is rectangular. The thickness of the die channel region 21 is, for example, about 3 to 40 mm. However, the cross-sectional shape of the die 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 if there is an acute-angled portion, the thickness can be 1 mm, for example.

The extruded region 22 is a downstream region in the channel model 20 . In the extruded region 22, the final cross-sectional shape F of the most downstream in the flow direction of the rubber 1 (see arrow A in FIG. 1) is defined. The final cross-sectional shape F is shown shaded in FIG. The final cross-sectional shape F is obtained by measuring each dimension of the cross-sectional shape in advance by extruding the rubber 1 from the die 10 and conducting an experiment using a vernier caliper, a laser measuring machine, or the like, and reproducing the shape. That is, the final cross-sectional shape F is based on the measured shape.

The extruded region 22 has a constant cross-sectional shape in the direction of flow of the rubber 1 (see arrow A in FIG. 1). Therefore, when creating the shape data of the extruded region 22, the extruded region 22 is formed by extruding the final cross-sectional shape F toward the upstream side. Also, the extrusion area 22 is the area outside the die 10 (see FIG. 1). Therefore, the thickness of the extruded region 22 is set larger than that of the die channel 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 cross-sectional shape. The length of the extruded region 22 is, for example, approximately 1 to 100 mm.

The connection region 23 is a region that connects the die channel region 21 and the extrusion region 22 . Therefore, the connection region 23 is a region outside the die 10 and is subject to die swell phenomena. 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 arrow A in FIG. 1). In this embodiment, the outer surface defining the connection area 23 is a flat surface 23a. Therefore, the connection region 23 is formed so that the cross-sectional shape linearly increases from the upstream side to the downstream side in the flow direction of the rubber 1 (see arrow A in FIG. 1). However, the outer surface that defines the connection region 23 is not limited to a flat surface, that is, it is not limited to one formed so that the cross-sectional shape increases linearly. The connection region 23 may have alternative shapes as shown in the first to third variations described below. The length of the connection region 23 is, for example, approximately 0.1 to 10 mm.

FIG. 3 is a block diagram of the simulation device 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 apparatus. The input unit 140 is a part that generates or receives input data for the simulation apparatus 100, and is configured by, for example, a keyboard, mouse, touch panel, or the like. The display unit 150 is a part that displays processing results 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 the programs that run on the control unit 110 . These control unit 110, input unit 140, display unit 150, and storage unit 160 are interconnected. The simulation device 100 is composed of an information processing device such as a desktop computer, a notebook computer, a workstation, or a tablet terminal.

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

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

The die flow path area creation unit 121 creates a die flow path area 21 (see FIG. 2) that reproduces the portion of the upstream die flow path 12 (see FIG. 1) in the flow path model 20 . The extruded region creating unit 122 creates the extruded region 22 (see FIG. 2) from the final cross-sectional shape F of the most downstream in the flow path model 20 as described above. The connection area creating unit 123 creates the connection area 23 (see FIG. 2) with the outer surface as, 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 flow path region 21, extrusion region 22, and connection region 23 into a finite number of elements to create an FEM model for analysis. do. The conditions for element division are input by the input unit 140 or pre-stored in the storage unit 160 . For example, conditions such as the shape and size of the elements to be divided are preferably set.

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, conditions such as the mass flow rate and volume flow rate of the rubber 1 at the inlet of the die 10 as inflow conditions, the presence or absence of slippage on the wall surface inside the die 10, and the flow It includes material properties of rubber 1, etc. 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 device 100. FIG.

Referring to FIG. 4, when the process starts (step S4-1), first, the flow path model 20 is generated by the flow path model generating unit 120 (step S4-2). Creation of the flow path model 20 will be described later with reference to FIG. Next, analysis conditions are defined by the analysis condition definition unit 125 for the created flow path model 20 (step S4-3). Next, the flow path model 20 created in this manner is analyzed by the calculation unit 130 (step S4-4). The analysis is executed until the calculation result converges, and if the analysis is not completed (NO: step S4-5), the conditions are reset as necessary (step S4-6), and the analysis is performed (step S4 -4). At the final cross-sectional shape F, when the atmospheric pressure and the expansion force of the rubber are balanced, 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), the process ends (step S4-8). The results output to the display unit 150 are, for example, velocity components and pressure values of the flow of the rubber 1 in each portion of the channel model 20 . Therefore, the user can check the flow in the die channel region 21, which cannot be visually recognized from the outside, through the display unit 150. FIG.

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 channel model 20 created. The shape data of the flow path model 20 in FIG. 6 is obtained by making the shape of the flow path model 20 described above and shown in FIG. 2 more realistic. As previously mentioned, channel model 20 includes die channel region 21 , connection region 23 , and extrusion region 22 . FIG. 7 shows a side view of the channel model 20, and FIG. 8 shows a comparison of cross-sectional shapes of the regions 21-23.

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

Referring again to FIG. 5, when creating the flow path model 20, first, the extruded area creating unit 122 creates the extruded area 22 from the final cross-sectional shape F (step S5-1). Next, the die flow path area creating unit 121 creates a die flow path area 21 that reproduces the die flow path 12 (see FIG. 1) (step S5-2). Then, the connection area 23 is created by the connection area creating unit 123 so as to connect the die flow path area 21 and the extrusion area 22 with the flat surface 23a (step S5-3). Thus, 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 flow path area 21 (step S5-2) may come first.

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

According to the simulation device 100 of this embodiment, the following advantageous effects are obtained.

Since the final cross-sectional shape F of the flow path model 20 is defined to be larger than the cross section of the die flow path 12, the die swell phenomenon can be reproduced. Further, since the final cross-sectional shape F of the most downstream in the flow of the rubber 1 is defined in advance, it is possible to shorten the time until the calculation converges. In addition, 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 path 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 channel region 21 can be analyzed.

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

Further, 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 associated with the analysis can be shortened.

(First modification)
FIG. 10 shows a first modification of the channel model 20 corresponding to FIG. In particular, a portion of the connection region 23 is shown enlarged within the dashed circle. As shown in FIG. 10, the outer surface defining the connection area 23 may be curved. For example, in this modified example, the outer surface that defines the connection region 23 is an arcuate surface.

According to this modification, a shape close to the actual phenomenon can be set as the connection region 23, 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 modification)
FIG. 11 shows a second modification of the channel model 20 corresponding to FIG. In particular, a portion of the connection region 23 is shown enlarged within the dashed circle. As shown in FIG. 11 , the outer surface that defines the connection region 23 is a first curved surface 23 b that forms a smoothly curved surface that is convex inward without forming corners at the connection portion with the die flow path region 21 . , and a second curved surface 23c that forms a smoothly curved surface convex outward without forming a corner at the connection portion with the extruded region 22 . In this modification, both the first curved surface 23b and the second curved surface 23c are arcuate surfaces with the same curvature.

According to this modification, the connecting portion between the die flow path 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 extrusion region 22 is formed by the second curved surface 23c. be. In particular, the die flow path region 21 and the connection region 23 are smoothly connected because the first curved surface 23b is convex toward the inside of the connection region 23 . Similarly, since the second curved surface 23c is outwardly convex, the connection region 23 and the extruded region 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, thereby preventing divergence of calculations.

(Third modification)
FIG. 12 shows a third modification of the channel model 20 corresponding to FIG. In particular, a portion of the connection region 23 is shown enlarged within the dashed circle. As shown in FIG. 12, the curvature of the first curved surface 23b may be changed from the connecting 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 modified example, the curvature of the first curved surface 23b is reduced and the curvature of the second curved surface 23c is increased from the second modified example. 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 expands greatly near the outlet 11 of the die 10 after being pushed out from the outlet 11 of the die 10 . If the first curved surface 23b near the exit 11 of the die 10 has a smaller curvature than the second curved surface 23c downstream therefrom, the amount of expansion near the exit 11 of the die can be set large. Therefore, the expansion state of the die swell phenomenon can be reproduced accurately. Also, as in the second modification, the areas 21 to 23 are smoothly connected, so divergence of calculations can be prevented.

As described above, specific embodiments and modifications thereof of the present invention have been described, but the present invention is not limited to the above embodiments, and various changes 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 Region 22 Extrusion Region 23 Connection Region 23a Flat Surface 23b First Curved Surface 23c Second Curved Surface 100 Simulation Device 110 Controller (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 the flow of a fluid extruded from a die channel, comprising an input unit for inputting information, a storage unit for recording information, and data input via the input unit or from the storage unit. a channel model creating unit that creates a channel model based on the read data; and a computing unit that performs fluid flow simulation calculations for the channel model,
The flow path model creation unit
a die channel region creating unit that creates a die channel region that is a portion of the die channel on the upstream side in the channel model;
an extruded region creating unit that creates an extruded region formed by extruding the final cross-sectional shape of the most downstream end in the flow channel model and defined larger than the cross-section of the die flow channel to the upstream side; ,
a connection area creation unit that creates a connection area that connects the die flow path area and the extrusion area in the flow path model;
an FEM modeling section 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;
and an analysis condition definition unit that defines analysis conditions in the FEM model. 2. The simulation apparatus according to claim 1, wherein said final cross-sectional shape is based on an actually measured shape. 3. The simulation device according to claim 1, wherein the outer surface defining said connection area is a flat surface. 3. The simulation device according to claim 1, wherein the outer surface defining said connection area is a curved surface. The outer surface defining the connection area is
a first curved surface forming a smooth curved surface convex inward without forming corners at a connection portion with the die flow path region;
5. The simulation device according to claim 4, further comprising: a second curved surface forming a smoothly curved surface convex outward without forming a corner at a connection portion with the extruded region. 6. The simulation device according to claim 5, wherein said first curved surface has a smaller curvature than said second curved surface. A simulation method for simulating the flow of a fluid extruded from a die channel,
creating a channel model from data input via the input unit or data read from the storage unit;
performing fluid flow simulation calculations on the channel model;
Creating the flow path model includes:
creating a die channel region that is a portion of the die channel on the upstream side in the channel model;
creating an extruded region formed by extruding the final cross-sectional shape, which is the most downstream final cross-sectional shape in the flow channel model and is defined to be larger than the cross-section of the die flow channel, to the upstream side;
creating a connection area that connects the die flow path area and the extrusion area in the flow path model;
creating an 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, comprising defining analysis conditions in the FEM model. 8. The simulation method according to claim 7, wherein said final cross-sectional shape is based on an actually measured shape. The simulation method according to claim 7 or 8, wherein the outer surface defining said connection area is a flat surface. The simulation method according to claim 7 or 8, wherein the outer surface defining said connection area is a curved surface. The outer surface defining the connection area is
a first curved surface forming a smooth curved surface convex inward without forming corners at a connection portion with the die flow path region;
11. The simulation method according to claim 10, further comprising: a second curved surface forming a smooth curved surface convex outward without forming corners at a connection portion with the extruded region. 12. The simulation method according to claim 11, wherein said first curved surface has a smaller curvature than said 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.

Images