JP2998596B2 - Fluid flow process analysis device, analysis method, injection molding process analysis device, analysis method, injection molded product, and method for manufacturing injection molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analysis apparatus for determining a pressure or a change in pressure or a distribution of a flow velocity of a fluid in a fluid flow process, and analyzing the fluid flow process thereby.
An analysis method, an analysis apparatus that applies these devices or methods to an injection molding process, a method of determining an injection molding condition by using the analysis method and the analysis method of the injection molding process, and a method of manufacturing an injection molded product, and a method manufactured by such a method. Injection molded articles.

[0002]

2. Description of the Related Art Generally, analysis methods such as an injection molding process for reproducing a fluid flow process including an injection molding process by computer simulation have been widely put into practical use. Hereinafter, as a specific example of the analysis method of the fluid flow process, the analysis method of the injection molding process will be mainly described.

[0003] These methods of analyzing the injection molding process contribute to high quality, efficiency, and low cost in the development of products such as injection molded products. For the method of utilizing the method, see, for example, JP-A-3-224712 and JP-A-4-15.
No. 2,120, JP-A-4-305424, JP-A-4-331125, and the like. All of these methods of analyzing the injection molding process use a two-dimensional model to obtain changes in pressure, temperature, shear stress, and the like of each part.

In these conventional methods of analyzing the injection molding process and the like, a two-dimensional model is used as a model of a cavity into which a fluid flows (a model of a mold having the same shape as an injection molded product). Are divided into a large number of two-dimensional microelements such as triangles or squares, and changes in pressure, temperature, shear stress, and the like in each microelement are obtained using a computer numerical analysis technique. With the conventional analysis method of the injection molding process, when the shape of the cavity can be approximated by a combination of two-dimensional figures, such as when the thickness of the cavity is small relative to the overall dimensions, a highly accurate analysis result can be obtained. Can be.

However, in the case of products having a thickness exceeding 5 mm or small molded products such as connectors having small overall dimensions, the influence of three-dimensional flow such as flow in the thickness direction appears strongly. Could not be analyzed well. Moreover, even in the case of a thin molded product, in order to accurately analyze a local flow state such as a step portion or a corner portion, almost no useful information can be obtained by the conventional method using a planar element. Was.

For example, in the case of a T-shaped molded product, according to the conventional method of analyzing the injection molding process, since the two-dimensional model as shown in FIG. 17 is used, the shape of the intersection can be correctly expressed. Did not.

[0007] Therefore, a method of using a three-dimensional model as shown in FIG. 3 and performing analysis using a general numerical fluid analysis method represented by a finite element method or a difference method is also conceivable. In this case, the target model is divided into three-dimensional small elements such as a hexahedron, a triangular pyramid, and a triangular prism. If an analysis is performed using such a model by a general numerical fluid analysis method, modeling that is faithful to the actual shape can be performed, and the accuracy of the analysis can be improved.

However, when such a general three-dimensional analysis method is applied, the amount of calculation becomes enormous, and the calculation time becomes extremely long, which is not practical. This is for the following reasons. That is, the flow in the injection molding process is
This is a moving boundary problem in which the filling range expands with time. In general, injection molding materials are non-Newtonian fluids whose viscosity, which represents flow characteristics, changes depending on temperature and shear rate.
The temperature that determines this viscosity also changes with time.
In order to analyze such a complicated flow three-dimensionally, an enormous amount of calculation time and computer capacity were required. Therefore, it has been practically difficult to reduce the cost and reduce the efficiency by substituting the prototype with the actual machine by simulation.

Therefore, when an injection molded article is manufactured by determining the injection molding conditions of the injection molded article by the conventional method and apparatus for analyzing the injection molding process as described above, the accuracy of the analysis is insufficient, which is preferable. Either the injection molding cannot be manufactured under the conditions, or the productivity is very low, or both.

[0010] In addition, the injection-molded product manufactured in such a manufacturing process has a problem in strength and the like because it is not manufactured under optimum conditions.

[0011]

SUMMARY OF THE INVENTION A first object of the present invention has been made in view of the above-mentioned problems. In analyzing a fluid flow process, the shape of a fluid flow path is determined using a three-dimensional model. An object of the present invention is to provide an apparatus and method for analyzing a fluid flow process that faithfully reproduces and realizes a precise analysis within a practical calculation time.

A second object of the present invention is to analyze the injection molding process of an injection molded product by faithfully reproducing the shape of the molded product by using a three-dimensional model, and within a practical calculation time. Injection molding condition determination to realize accurate analysis
An object of the present invention is to provide an apparatus and method for analyzing an injection molding process.

Further, a third object of the present invention is to provide a product shape, mold design,
An object of the present invention is to provide a method for efficiently producing a high-quality injection molded product by determining injection molding conditions such as material selection.

A fourth object of the present invention is to provide an injection-molded article manufactured under optimum conditions by using such an injection-molded article manufacturing method.

According to the present invention, a three-dimensional model constructing means for constructing a three-dimensional model in which at least a part of a cavity in which a fluid flows is divided into a large number of microelements, and in each of the microelements, the microelement has a cavity wall surface. A flow conductance determining means for determining the flow conductance κ of the fluid so as to have a small value when located at a position close to, and a flow conductance κ of the fluid so as to have a large value when located at a distant position; An apparatus for analyzing a flow process of a fluid, comprising: pressure calculating means for obtaining the pressure of the fluid in each of the microelements based on the flow conductance κ; and output means for outputting an analysis result .

Further, according to the present invention, a three-dimensional model constructing means for constructing a three-dimensional model in which at least a part of a cavity in which a fluid flows is divided into a number of minute elements, Flow conductance determining means for determining the flow conductance κ of the fluid so as to have a small value when the position is close to the cavity wall surface, and determining the flow conductance κ of the fluid so as to have a large value when the position is far from the cavity wall surface. Pressure change calculating means for obtaining a pressure change of the fluid in each of the microelements based on the flow conductance κ, and an output means for an analysis result
And characterized in that it comprises the door, analyzer flow process of fluid.

Further, according to the present invention, there is provided a three-dimensional model constructing means for constructing a three-dimensional model in which at least a part of a cavity in which a fluid flows is divided into a large number of minute elements. Flow conductance determining means for determining the flow conductance κ of the fluid so as to have a small value when the position is close to the cavity wall surface, and determining the flow conductance κ of the fluid so as to have a large value when the position is far from the cavity wall surface. Flow velocity calculation means for calculating the flow velocity of the fluid in each of the microelements based on the flow conductance κ; and output means for analysis results
And a device for analyzing a fluid flow process.

Further, according to the present invention, to construct a three-dimensional model divided at least a portion of the cavity for fluid flow into a number of microelements, fine small essential to have your the respective microelements
If the element is near the cavity wall,
On the other hand, if it is far away, the value will be large.
The flow conductance κ of the fluid determined in so that, on the basis of the obtained flowable conductance κ determined pressure of the injection molding material in each minute element, the resulting pressure by analyzing the flow process of said fluid And a method of analyzing a flow process of a fluid, which outputs an analysis result.

Further, according to the present invention, to construct a three-dimensional model divided at least in part on a number of infinitesimal elements cavity for fluid flow, the fine small to have you to the each microelement
Small value if the element is close to the cavity wall
On the other hand, if it is far away,
The flow conductance κ of the fluid is determined so as to obtain the pressure change of the fluid in each of the microelements based on the obtained flow conductance κ, and the flow process of the fluid is analyzed based on the obtained pressure change. And a method of analyzing a flow process of a fluid, which outputs an analysis result.

Further, according to the present invention, to construct a three-dimensional model divided at least in part on a number of microelements cavity for fluid flow, and have contact with the respective minute elements of the fluid
If the microelement is located near the cavity wall,
Value, but large when it is far away
The flow conductance κ is determined so as to have a small value, the flow velocity of the fluid in each of the microelements is determined based on the obtained flow conductance κ, and the flow process of the fluid is analyzed based on the obtained flow velocity. And output the analysis result.

Further, according to the present invention, in a preferred embodiment of the method for analyzing a flow process of a fluid, the flow conductance κ in the microelement is increased with an increase in the shortest distance R between each microelement and the cavity wall surface. In addition, a preferred embodiment of a method for analyzing a fluid flow process is provided, which is determined by a function F (R, η) that decreases with an increase in the viscosity η of the fluid.

According to the present invention, the flow conductance κ in the microelement is calculated by the following equation.

(Equation 3) (Where η represents the viscosity of the fluid and x, y and z represent the positions of the microelements).

According to the present invention, there is provided a three-dimensional model construction means for constructing a three-dimensional model in which at least a part of an injection molded article is divided into a large number of microelements; The flow conductance of the injection molding material is determined so as to have a small value when it is at a near position, while the flow conductance is determined to have a large value when it is at a far position. Means, pressure calculation means for obtaining the pressure of the injection molding material in each of the microelements based on the flow conductance κ, and output means for analysis results , for determining injection molding conditions. An analysis apparatus for an injection molding process is provided.

Further, according to the present invention, a three-dimensional model construction means for constructing a three-dimensional model in which at least a part of an injection molded article is divided into a large number of microelements, and in each of the microelements, the microelement is formed by a molding die When located near the surface, the flow conductance of the injection molding material κ
Flow conductance determining means for determining the flow conductance κ of the injection molding material so as to have a large value when the injection molding material is at a distant position, and the injection molding material in each of the microelements based on the flow conductance κ. Pressure change calculation means for calculating the pressure change of the
Injection molding conditions characterized by comprising force means
An apparatus for analyzing the injection molding process for the determination is provided.

Further, according to the present invention, there is provided a three-dimensional model constructing means for constructing a three-dimensional model in which at least a part of an injection molded article is divided into a number of minute elements, and in each minute element, the minute element is formed by a molding die. When located near the surface, the flow conductance of the injection molding material κ
Flow conductance determining means for determining the flow conductance κ of the injection molding material so as to have a large value when the injection molding material is at a distant position, and the injection molding material in each of the microelements based on the flow conductance κ. and flow rate calculation means for calculating a flow rate of, out of the analysis results
Injection molding conditions characterized by comprising force means
An apparatus for analyzing the injection molding process for the determination is provided.

Further, according to the present invention, to construct a three-dimensional model divided at least a portion of the injection molded article to a large number of microelements, fine small elements have contact to the respective microelements cavity
If it is located near the wall, set it to a small value.
On the other hand, when located at a distant position, the flow conductance κ of the injection molding material is determined so as to have a large value, and the pressure of the injection molding material at each of the microelements is determined based on the obtained flow conductance κ. A method for analyzing an injection molding process for determining injection molding conditions, characterized by analyzing an injection molding process of the injection molded article based on the applied pressure and outputting an analysis result.

Further, according to the present invention, to construct a three-dimensional model divided at least a portion of the injection molded article to a large number of microelements, fine small elements have contact to the each microelements Cavity
When it is located near the wall surface, it will be a small value,
On the other hand, when located at a distant position, the flow conductance κ of the injection molding material is determined to be a large value, and the pressure change of the injection molding material in each of the microelements is determined based on the obtained flow conductance κ. An analysis method of the injection molding process for determining injection molding conditions, characterized by analyzing an injection molding process of the injection molded article based on the obtained pressure change and outputting an analysis result.

Further, according to the present invention, to construct a three-dimensional model divided at least a portion of the injection molded article to a large number of microelements, fine small and have contact to each microelements of the injection molding material
Small value if the element is close to the cavity wall
On the other hand, if it is far away,
Is determined so that the flow rate of the injection molding material in each of the microelements is determined based on the obtained flow conductance κ, and the injection molding process of the injection molded article is performed based on the obtained flow rate. And outputting an analysis result. The method for analyzing an injection molding process for determining injection molding conditions is provided.

According to the present invention, the flow conductance κ of the microelements increases with the increase in the shortest distance R between each of the microelements and the surface of a molding die, and the material viscosity of the injection molding material increases. function that decreases with increasing η
A preferred embodiment of a method for analyzing an injection molding process, characterized in that the method is determined by F (R, η), is provided.

According to the present invention, the flow conductance κ in the microelement is calculated by the following equation.

(Equation 4) (Η represents the material viscosity of the injection molding material, and x, y and z represent the positions of the microelements). A preferred embodiment of a method for analyzing an injection molding process is provided.

Further, according to the present invention, the injection molding conditions of the injection molded article are determined, and a three-dimensional model in which at least a part of the injection molded article is divided into a large number of minute elements is constructed. The flow conductance κ of the injection molding material is determined so as to have a small value when the microelement is at a position close to the surface of the mold, while the flow conductance κ of the injection molding material is set to have a large value when the microelement is at a position far from the mold.
Is determined, the pressure of the injection molding material in each of the microelements is determined based on the obtained flow conductance κ,
A method for manufacturing an injection-molded article is provided, wherein injection molding conditions are finally determined based on the obtained pressure distribution, and an injection-molded article is manufactured based on the finally determined injection molding conditions. Is done.

Further, according to the present invention, the injection molding conditions of the injection molded article are determined, and a three-dimensional model is constructed by dividing at least a part of the injection molded article into a large number of microelements. The flow conductance κ of the injection molding material is determined so as to have a small value when the microelement is at a position close to the surface of the mold, while the flow conductance κ of the injection molding material is set to have a large value when the microelement is at a position far from the mold.
The pressure change of the injection molding material in each of the microelements is obtained based on the obtained flow conductance κ, and the injection molding conditions are finally determined based on the obtained distribution of the pressure change, and the final determination is performed. A method for manufacturing an injection-molded article, wherein the method for manufacturing an injection-molded article is performed based on the obtained injection molding conditions.

Further, according to the present invention, the injection molding conditions of the injection molded article are determined, a three-dimensional model in which at least a part of the injection molded article is divided into a large number of microelements is constructed, The flow conductance κ of the injection molding material is determined so as to have a small value when the microelement is at a position close to the surface of the mold, while the flow conductance κ of the injection molding material is set to have a large value when the microelement is at a position far from the mold.
The flow rate distribution of the injection molding material in each of the microelements is determined based on the obtained flow conductance κ, and the injection molding conditions are finally determined based on the obtained flow rate distribution. A method for manufacturing an injection molded article is provided, wherein an injection molded article is manufactured based on the determined injection molding conditions.

According to the present invention, the injection molding conditions include any one of the shape of the injection molded article, the shape of the molding die, the material injection speed, the material temperature, the molding die temperature and the injection molding material. A method for producing an injection molded article is provided. Further, according to the present invention, there is provided an injection-molded article manufactured by any of the above-described methods for manufacturing an injection-molded article.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an analysis apparatus and an analysis method for an injection molding process, which is an example of an analysis apparatus and an analysis method for a fluid flow process according to the present invention, will be described in detail with reference to the drawings. I do. In addition, an example of a preferred embodiment of a method for manufacturing an injection molded product will be described together.

FIG. 1 is a diagram showing an example of a hardware configuration of an apparatus for analyzing an injection molding process according to the present invention. Computer 1
01, an input device 103, a display device 104, and an auxiliary storage device 102 are connected. With the input device 103,
For example, the input of the injection molding conditions of the injection molded article to be analyzed and the data of the three-dimensional model are received, and such data is stored in the auxiliary storage device 102. The computer 101 transmits this data to the internal RA according to the instruction of the operator.
It is read into M (volatile memory that can be randomly accessed) and analyzed. The obtained analysis result is displayed on the display device 104, for example. If necessary, the operator can change the injection molding conditions and perform the analysis again. The output of the analysis result may be performed on a separately prepared printer device, or may be stored in the auxiliary storage device 102. In this case, for example, this output can be used as input data of another analysis device.

FIG. 2 is an apparatus for analyzing an injection molding process according to the present invention.
It is the flowchart which showed the example of the procedure in the analysis method and the manufacturing method of the injection molded article using such an analysis apparatus. In the analysis of the injection molding process, first, the injection molding conditions of the injection molded product (for example, the shape of the injection molded product, the shape of the molding die, the material injection speed, the material temperature, the temperature of the molding die, the injection molding material, etc.) are inputted (step 1). ). Next, the shape is divided into three-dimensional microelements as shown in FIG. 3 to construct a three-dimensional model of the product (step 2). Next, the flow conductance κ of each microelement is determined (step 3). Subsequently, using the flow conductance κ of each micro element determined in step 3, the pressure of the injection molding material in each micro element (hereinafter referred to as “material pressure”) is obtained (step 4). Here, the change in the pressure of each minute element may be obtained. Alternatively, the flow velocity of the injection molding material in each microelement may be obtained from the obtained material pressure distribution or directly. The analysis result thus obtained is subjected to, for example, graphic processing and displayed in the form of a contour line or a graph (step 5). The data may be output to a printer device or the like as described above.

Further, in the case of manufacturing an injection-molded article using the analysis result of the injection molding process, the pressure, the pressure change or the flow velocity obtained as described above are evaluated (step 6). This evaluation is performed, for example, by determining that there is a high possibility that molding failure will occur if there is a region where abnormal pressure, pressure change, or flow velocity is obtained. If a molding defect is predicted from the obtained analysis result, the injection molding conditions are changed (step 7), and the process returns to step 1 to perform the analysis. If these steps are repeated and the result that the injection molding is expected to be performed well is obtained, the injection molding is performed under the injection molding conditions,
An injection molded product is manufactured (Step 8).

Next, a method for obtaining the material pressure, the pressure change, and the flow velocity in each micro element will be described in detail.

As a method of obtaining the material pressure in the injection molding, a generally known continuous equation (1) is used. Equation (1) is an equation representing that the sum of the inflow flow rate and the outflow flow rate into an arbitrary region in the fluid is zero, and is established by assuming that the fluid is incompressible. If the fluid is compressible, the right side will be non-zero, but the following discussion holds true as well.

[0041]

(Equation 5) Here, x, y, and z are three-dimensional spatial coordinates, and U, V
, W is the flow velocity of the injection molding material in each coordinate axis direction. Equation 1 is an equation in which U, V, and W are unknown variables. Generally, it is necessary to solve this equation and a motion equation in which the pressure P and the shear stress derived from the flow velocity are unknown variables. When dealing with dimensional flow, there are four unknown variables.

The present inventor uses the following equation (2) to solve the equation (1), whereby the flow velocity in each direction is obtained.
It has been found that by eliminating U, V, and W from equation (1) and reducing the number of unknown variables from four to one of pressure only, the calculation time can be greatly reduced. In this case, the calculation time when the three-dimensional model is used is reduced to about 1/16, and the required RAM capacity of the computer can be reduced to about 1/4. This made it possible for the first time to analyze a three-dimensional injection molding process with practical speed and accuracy.

[0043]

(Equation 6) In the above equation (2), κ is the flow conductance.
Equation 2 is called the Darcy flow equation, and is an equation representing the permeation flow in the porous material. That is, three-dimensional coordinate axes x, y,
It is assumed that the flow velocities U, V, W in the z direction are proportional to the pressure gradient in each direction.

By substituting equation (2) into equation (1), the following equation is obtained.
(3) is obtained.

[0045]

(Equation 7) Equation (3) has the same form as the equation representing general heat conduction. In the heat conduction problem, if the temperature T or temperature gradient at the boundary of an area is set in advance as a boundary condition for an area divided into arbitrary small elements, the temperature distribution inside the area can be calculated by numerical methods such as the finite element method, the difference method, and the control volume method. It can be obtained by an analysis method. Therefore, if the pressure P or pressure gradient at the region boundary is set as the boundary condition for the region divided into arbitrary small elements, Equation (3) can be solved similarly by using the analysis method and analysis program for the heat conduction problem. It is possible to determine the pressure distribution of the material.

For the method of setting the boundary conditions, for example, an injection pressure value or a pressure gradient value obtained from the injection flow rate is set in the material inflow portion, and since there is no inflow and outflow at the boundary of the region in contact with the surface of the mold, the pressure gradient is zero. Is set, and the pressure at the flow front portion, which is a free surface, is set to atmospheric pressure.

Further, in the injection molding, since the filling portion of the material increases with time, the pressure distribution also changes with time. Such a temporal change in the pressure distribution (distribution of the pressure change) can be obtained by obtaining a change in the shape of the filling region in accordance with the total amount of the newly filled material and solving equation (3) again. As a method of obtaining the change of the filling region shape, the control volume method and the FAN method (Flow Analysis Network Method) used in the conventional analysis method of the injection molding process are used.
d) and the like are used.

The flow velocity can be easily obtained, for example, by obtaining the pressure distribution P as described above and substituting this into the equation (1).

In some cases, an actual injection-molded product has a thin portion so that it is not necessary to consider the flow of the injection molding material in the thickness direction. For such a part, using the two-dimensional model,
It may be used in place of (2) to perform two-dimensional analysis. As a result, the overall calculation speed can be further improved.

[0050]

(Equation 8) Here, H is the thickness of the material flow path, and η is the material viscosity.

Next, the method of determining the flow conductance κ in step 3 of FIG. 2 will be described in detail.

For the part where the injection molding process is analyzed using a two-dimensional model, the flow conductance can be uniquely determined from the flow path shape and the material viscosity as shown in equation (4). It is preferable to use

In the analysis using a three-dimensional model, as a method for determining κ, for example, the following method discovered by the present inventors is preferably used.

According to the knowledge of the present inventors, the fluidity of the injection molding material increases as the distance from the surface of the mold increases, and decreases as the distance from the surface of the mold increases. Therefore, in general, it is preferable to determine the flow conductance such that the flow conductance has a small value when the microelement is close to the mold surface (that is, the cavity wall surface), and has a large value when the microelement is far from the mold surface. Therefore, it is possible to obtain a good approximation to the analysis result by assuming that the flow conductance κ changes according to a function showing such a tendency. That is, it is preferable to use the following equation (5) as the flow conductance κ in such a case.

[0055]

(Equation 9) Here, R is the shortest distance from the center of gravity of each microelement to the surface of the molding die or the shortest distance from the vertex of each microelement to the surface of the molding die, and η is the material viscosity.

As the function F of the equation (5) becomes farther from the mold surface, that is, as R becomes larger, the effect of the frictional force between the mold and the material decreases, so that the flow conductance κ increases,
Also, as the material viscosity η is larger, the fluidity is lower, so that the flow conductance κ is reduced. For example, κ = a
As a function of R / η + b, κ increases as R increases, and κ decreases as η increases. In this case, a is a positive proportional coefficient, and b is a coefficient indicating R = 0, that is, the flow conductance on the surface of the mold. These constants
“a” and “b” are determined, for example, by conducting experiments using typical injection molded products. R / illustrated here
The linear expression relating to η has a feature that the calculation time is completed in a short time as the simplest mode of specifying the function F 2. Also,
Depending on the type of the injection molded product, another type of calculation formula may be used in which the analysis result and the actual molding result match well.

The material viscosity η changes according to the temperature, the shear rate, and the like, and can be represented by an approximate expression as shown in Expression (6). Here, A, B, and C are coefficients specific to the material and can be experimentally obtained by a viscosity measuring device. Equation (6)
By substituting the approximate value of the material viscosity by Eq. (5) into the equation (5), the effect of the change of the material viscosity due to the change of the shear rate and the temperature can be easily included in the flow conductance calculation.

[0058]

(Equation 10) In addition, the flow conductance κ may be obtained as follows.

That is, the present inventor has found a method for obtaining the flow conductance κ by solving the differential equation shown in the equation (7). Here, x, y, and z are three-dimensional spatial coordinate axes, and η is material viscosity.

[0060]

[Equation 11] The present inventor has found that this equation (7) is an equation representing the balance of forces in a flow field where viscous force is dominant,
Equation 1 is substituted to eliminate the flow velocity U, and the pressure P
Have been obtained by omitting the second derivative terms of x, y, and z of. By omitting the second derivative term, it became possible to obtain κ by a simple method described below.

[0061]

(Equation 12) Equation (7) has the same form as the equation representing general heat conduction. In the heat conduction problem, the temperature T
Alternatively, if the temperature gradient is set in advance as a boundary condition, the temperature distribution inside the area can be calculated using the finite element method, the boundary element method, the difference method,
It is known that it can be obtained by a numerical analysis method such as a control volume method. Therefore, the boundary condition where κ is zero at the surface of the mold, which is the region boundary, is set, and by solving equation (7), the distribution of κ becomes smaller as the surface is closer to the mold surface and larger as it is farther from the surface of the mold. It can be obtained by using an analysis method or an analysis program. Note that the boundary condition for κ = 0 is, as is clear from equation (1),
Is equivalent to assuming that Here, when considering the sliding of the material on the mold surface, κ = 0.01 mm ² / (Pa
This can be realized by substituting a small non-zero value such as c).

The approximate value of the material viscosity according to the equation (6) is
By substituting into (7), the effect of changes in material viscosity due to changes in shear rate and temperature can be easily incorporated into the flow conductance calculation.

According to this method, it is necessary to solve the heat conduction equation compared with the method of determining the flow conductance κ using the above equation (5). The flow conductance can be determined well. In addition, as described above, Equation (7) is derived based on Equation (8), which is an equation representing force balance in a flow field where viscous force is dominant. The value obtained is more physically valid than the method.
Therefore, accurate analysis results can always be given without being affected by the shape of the injection molded product, the model of division into minute elements, and the like.

For example, when a microelement having a cross-sectional shape as shown in FIGS. 4 and 5 is used, according to the method for determining the flow conductance using Expression 5, the microconductivity which is regularly divided as shown in FIG. The flow conductance can be accurately and quickly determined in the element shape, but in the case of an irregular micro element shape as shown in FIG. It may be.

In general, microelement division for use in numerical analysis can be automatically performed by software called a preprocessor, and can be easily divided especially for a product having a complicated shape having many projections and holes. can do. When such automatic division is performed, the shape of microelements is generally irregular, but the method using equation (7) can minimize the effect of the shape of microelements, and Even if it is applied to the injection molded article, it is possible to perform highly accurate analysis.

In addition to the above, there are various methods for determining the flow conductance. In particular, a method for achieving high calculation accuracy and calculation speed for a specific shape can be considered.

Next, a method of manufacturing an injection-molded article by analyzing the injection-molding process by the above-described method, determining the injection-molding conditions based on the result, and manufacturing the injection-molded article will be described.

As described above, it is possible to obtain the material pressure, the pressure change, or the distribution of the flow velocity of the injection molding material when the injection molded article is manufactured under the given injection molding conditions. At this time, such a result can be utilized for changing / determining the injection molding conditions as follows.

Generally, in injection molding, in order to obtain a molded product with low stress and small distortion, it is desirable that the material pressure is as low as possible, and the pressure gradient is as uniform as possible without an extremely sharp portion or an extremely small gradient portion. It is preferred that Also, regarding a temporal change in pressure, generation of a peak pressure due to a sudden increase in pressure is not preferable. By applying such a pressure criterion, it is possible to determine the quality of the molded state. It is also preferable to apply a criterion based on the flow velocity obtained as described above.

As a method of judging the molding state, judgment can also be made on the basis of a flow velocity gradient, a shear rate, a stress, a progress pattern of a filling region, and the like. These data can be easily obtained by processing the information of the pressure distribution, pressure change, or flow velocity distribution obtained by the above-described method. For example, the velocity gradient between the microelements is defined as the shear rate, and the shear stress can be obtained by multiplying the shear rate by the material viscosity. Further, by sequentially determining a portion to be filled next from the velocity of the flow front end portion, it is possible to analyze the progress pattern of the filling region.

When a defect is predicted by the above-mentioned determination method, a molding die design, a product design,
By modifying the molding conditions or the materials used, it is possible to manufacture an injection-molded article having no defect.

The first correction method is a method of correcting the shape of a mold and changing a material flow path and the like. Here, the shape of the molding die means a material flow path from a melt injection nozzle of the material to a product shape portion, which is generally called a sprue, a runner or a gate. For example, when it is determined that the pressure loss is too large due to the long flow length from the nozzle to the end of the product, the flow length is reduced by branching the runner and flowing into the product shape portion from a plurality of gates. be able to.

The second correction method is a method of correcting the shape of an injection molded article and changing the material flow path. For example, when a pressure gradient at a product shape portion is large and a large flow strain is expected to occur, the pressure gradient can be reduced by increasing the product wall thickness.

A third correction method is a method of changing molding conditions such as a material injection speed, a material temperature, or a mold temperature. For example, if the pressure in the material injection port at a certain time is so high that molding is expected to be difficult, reduce the material injection speed at this time or increase the material temperature or mold temperature. Can reduce the pressure rise.

The fourth modification is a method of changing the injection molding material. For example, material pressure loss is severe,
If molding is expected to be difficult, pressure loss can be reduced by changing to a good-flowing material having a low viscosity.

The above-mentioned correction methods may be performed separately or in combination.
Further, it is preferable to automatically perform the above-mentioned correction using an expert system or the like.

The injection molding conditions are reexamined as described above, and analysis is again performed by the above-described analyzer of the injection molding process under conditions considered to obtain preferable injection molding results, until the injection molding conditions for obtaining the optimum results are obtained. Repeat this. After finding the injection molding conditions that provide the optimum results, injection molding is performed under those conditions to produce an injection molded product.

The present invention can be applied in principle to any shape of an injection-molded product, but is particularly effective for a product in which a three-dimensional shape effect easily appears.

Products that are likely to exhibit a three-dimensional shape effect include:
A thick molded product whose wall thickness exceeds 5 mm, or 1
The overall product size is 10mm even with a thin wall of ~ 2mm
It refers to a small-sized molded product having a relatively small size, in which the influence of flow in the thickness direction is relatively likely to appear. Also, a three-dimensional analysis is effective for a local flow at a portion where the flow suddenly changes in the thickness direction, such as a flow at a step portion or a corner portion.

Further, the method of analyzing an injection molding process according to the present invention can be used in combination with a conventional two-dimensional method. For a portion where three-dimensional flow does not pose a problem, the conventional two-dimensional method is used. Elements can also be used to improve the efficiency of the analysis.

In the present invention, as a forming die, a metal die processed by a precision processing means such as electric discharge machining or the like is used.

The fluid flow analysis device and method of the present invention can be preferably used not only for the injection molding process but also for the analysis of general fluid flow processes. For example,
In particular, it is suitable for analyzing a flow process involving three-dimensional material flow such as a material flow in an extrusion die, a flow in an extruder screw groove, and a flow in a kneader.

That is, the present invention can be applied to obtaining a pressure distribution, a pressure change distribution, or a material flow velocity distribution during extrusion flow in the flow in a die during the extrusion molding of a round bar or a flat plate or the profile extrusion molding. Pressure gradient and flow velocity
In the portion near 0, the quality of the molded product is deteriorated, such as stagnation of the material or thermal deterioration. Therefore, it is necessary to determine the extrusion molding conditions such as the shape of the die so as not to generate the stagnation portion. The present invention is suitable for such an application.

Similarly, the present invention can be applied to determination of conditions such as a screw design having a small stagnation portion in a screw portion of an injection molding machine or an extrusion molding machine. In addition, it is also possible to calculate the shear stress distribution in the screw groove in the extruder-type kneader and use it for designing to maximize the shear stress value.

[0085]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an example of an apparatus and method for analyzing a flow process of a fluid according to the present invention. Will be described. FIG. 2 is a flowchart showing a procedure of a method for configuring the present invention.

[Embodiment 1] Here, as shown in FIG.
An example of a molded product having a step having a thickness of 5 mm to 10 mm will be described.

First, in step 1 of FIG. 2, injection molding conditions (material used: nylon resin, injection temperature: 280 ° C., mold temperature: 80 ° C., filling time: 1 sec) were input. Subsequently, in step 2, the shape of the injection molded product was divided into a plurality of three-dimensional microelements 14 as shown in FIG. 6, and a three-dimensional model of the injection molded product was constructed. In this embodiment, a hexahedron consisting of eight vertices is used as a small element, and the shape of an injection-molded product is divided into regular lattice-shaped three-dimensional minute elements.

Subsequently, in step 3 of FIG. 2, the flow conductance κ is calculated by the following equation (5) (κ = aR / η + b, a = 0.4 mm, b = 0.0 mm
² / (Pa · sec), η = 100 Pa · sec). In Equation (5), the distance between the forming die and the center of gravity of each microelement was defined as R.

FIG. 7 is a contour diagram showing the distribution of the flow conductance κ in the cross section obtained based on Equation 5 using the microelement division model of FIG. 6, and the flow conductance at the portion 15 close to the mold surface is shown. Is near 0, while the flow conductance is 0.02 mm in the portion 16 near the center of thickness.
² / (Pa · sec) indicates that the flow is large and easy. Thus, a smooth kappa distribution was obtained.

Subsequently, in step 4 of FIG. 2, κ of FIG.
The pressure distribution during injection molding of each microelement was obtained by solving equation (3) based on the distribution using the same numerical calculation program as that for the heat conduction analysis. Further, these results were subjected to graphic processing in step 5 to obtain a pressure distribution as shown in FIG. The pressure range of this pressure distribution was 0.1 to 10 MPa. Here, the pressure of each minute element is displayed as a contour line. A series of calculations from Step 2 on were completed in a very short time of about 90 seconds using an engineering workstation.

Based on the obtained pressure distribution, a pressure change distribution (FIG. 9) and a flow velocity distribution (FIG. 10) were further obtained.
Further, the shear stress distribution and the like were also obtained. According to the obtained analysis results, for example, the flow velocity is 30 to 100 mm / se
c, Since the shear stress was 1000 Pa or less and it was determined that there was no particular problem in injection molding, this injection molded product was manufactured.
Since the manufactured injection-molded product was manufactured under optimal conditions, it had excellent properties such as strength.

If a molding defect is expected, for example, an extreme pressure gradient occurs here, the shape of the molded product, the molding conditions, the material, etc. are changed and the process is repeated from step 1 to obtain an appropriate product. Obtain the design, mold design, and molding conditions.

Example 2 The same injection-molded product as in Example 1 was used, based on the equation (5), under the same conditions as above except that an irregular microelement division model as shown in FIG. 11 was used. When the distribution of the flow conductance κ was determined, as shown in FIG.
Was obtained. It is clear that this result is not physically explainable and is a calculation error.
This is presumably because the distance between the center of gravity of the adjacent elements, which should be substantially the same, and the surface of the mold is not the same because of the method of dividing the minute elements.

In such a case, it may be difficult to obtain a precise analysis result. However, since the irregular minute element division model as described above can be automatically generated from the shape of the injection molded product, it is simple. In addition, since obtaining the flow conductance κ based on the equation (5) has a high calculation speed, it can be effectively used when determining rough conditions in the initial stage of determining injection molding conditions.

[Embodiment 3] For the same injection-molded product as in Embodiments 1 and 2, the flow conductance κ of the flow conductance κ was calculated based on the equation (7) using the same small element division model as shown in FIG. The distribution of the injection molding process was analyzed under the same conditions except that the distribution was determined and the injection molding process was analyzed using the distribution.

FIG. 13 is a contour diagram showing the distribution of the flow conductance κ in the cross section obtained based on Equation 7 using the microelement division model of FIG. Although a relatively long calculation time was required, a smooth κ distribution (distribution range: 0 to 0.02 mm ² / (Pa · sec)) similar to FIG. 7 was obtained.

Subsequently, in step 4 of FIG. 2, the pressure distribution of each microelement during injection molding is obtained based on the κ distribution obtained in FIG. 13, and a pressure distribution of 0.1 to 10 MPa is obtained as shown in FIG. Was. Also in this case, the pressure of each minute element is displayed as a contour line. The obtained pressure distribution was almost the same as that shown in FIG. A series of calculations from Step 2 onward were completed in a slightly longer time of about 160 seconds using the same engineering workstation as above. In addition, when the calculation is performed by using the conventional general numerical calculation method, it takes about 2500 seconds, for example, to obtain the pressure distribution for the same object.

Based on the obtained pressure distribution, a pressure change (FIG. 15) and a flow velocity distribution (FIG. 16) were further obtained. Further, the shear stress distribution and the like were also obtained. These results were almost the same as in Example 1. From the obtained analysis results, it was determined that there was no particular problem in injection molding, and the product was manufactured. Therefore, this injection molded product was manufactured. This injection molded product was manufactured under the same optimum conditions as in Example 1, and thus had excellent properties such as strength.

As in the case of the first embodiment, if a molding defect is expected here, for example, an extreme pressure gradient occurs, the shape of the molded product, the molding conditions, the material, etc. are changed and the steps from step 1 are repeated. By repeating, proper product design, mold design, and molding conditions are obtained.

[0100]

According to the apparatus and method for analyzing an injection molding process of the present invention, a pressure distribution and the like are obtained using the flow conductance κ. The shape of a molded article can be faithfully reproduced by using, and accurate analysis can be performed within a practical calculation time.

Further, according to the apparatus and method for analyzing the injection molding process of the present invention, the flow conductance κ is determined by using a high-speed and accurate equation such as Equations 5 and 7 which is well-established. κ can be easily obtained, and an accurate analysis result can be obtained in a practical calculation time.

Further, according to the method of manufacturing an injection-molded article of the present invention, using the above-described apparatus for analyzing the injection molding process,
By determining injection molding conditions such as product shape, mold design, material selection, etc., a high quality injection molded product can be manufactured efficiently.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a hardware configuration of an analyzer for a fluid flow process (injection molding process) according to the present invention.

FIG. 2 is a flowchart illustrating an example of a procedure of an analysis method of an injection molding process and a method of manufacturing an injection molded product according to the present invention.

FIG. 3 is a diagram showing an example of a three-dimensional minute element division model used in the present invention.

FIG. 4 is a conceptual diagram showing an example of a method for determining a flow conductance used in the present invention.

FIG. 5 is a conceptual diagram showing an example of a method for determining a flow conductance used in the present invention.

FIG. 6 is a diagram showing a state of determination of a target microelement in one embodiment of the present invention.

FIG. 7 is a diagram showing a calculation result of a distribution state of a flow conductance κ in a cross section of an injection molded product according to one embodiment of the present invention.

8 is a contour diagram showing a result of analyzing a pressure distribution inside an injection-molded product based on a distribution of the flow conductance κ in FIG. 7;

9 is a contour diagram showing a result of analyzing a distribution of a pressure change inside an injection molded product based on a distribution of the flow conductance κ in FIG. 7;

10 is a diagram showing a result of analyzing a flow velocity distribution of a material inside an injection-molded article based on the distribution of the flow conductance κ in FIG. 7;

FIG. 11 is a diagram illustrating a state of determination of a target microelement in one embodiment of the present invention.

FIG. 12 is a calculation result showing a distribution state of a flow conductance κ in a cross section of an injection-molded product in one example of the present invention.

FIG. 13 is a calculation result showing a distribution state of a flow conductance κ in a cross section of an injection molded product according to one embodiment of the present invention.

14 is a contour diagram showing a result of analyzing a pressure distribution inside an injection-molded product based on the distribution of the flow conductance κ in FIG.

FIG. 15 is a contour diagram showing a result of analyzing a distribution of a pressure change inside the injection molded product based on the distribution of the flow conductance κ in FIG.

16 is a diagram showing a result of analyzing a flow velocity distribution of a material inside an injection-molded article based on a distribution of the flow conductance κ in FIG.

FIG. 17 is a diagram showing an example of a two-dimensional minute element division model used in analysis of a conventional injection molding process.

[Explanation of symbols]

 1: Two-dimensional quadrilateral microelements 2: Three-dimensional hexahedral microelements 3: Microelement centroid 4: Shortest distance from microelement centroid to molding die surface 5: Contact between product obtained by dividing microelements and molding die surface Part 6: Cross section of microelement 7: Microelement 8: Center of gravity of microelement 9: Shortest distance from the center of gravity of microelement to the surface of the mold 10: Contact portion between the product divided into microelements and the surface of the mold 11: Cross section of microelement 12: Microelement 13: Shape analysis model with steps 14: Microelement 15: κ contour 16: κ contour 17: Microelement 18: κ contour 20: κ contour 21: Pressure contour 22: Pressure contour 101: Computer 102: Auxiliary storage device 103 ： Input device 104 ： Display device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-55597 (JP, A) JP-A-5-57771 (JP, A) JP-A-4-305424 (JP, A) JP-A-5-55724 337999 (JP, A) JP-A-1-67319 (JP, A) JP-A-7-209167 (JP, A) J. Crochet, "NUMERICAL SIMULATION OF FLOW PROCESSES", Chemical Engineering Science, Vol. 42, No. 5, (1987), p. 979-1003 (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 45/76-45/77 B29C 45/17 B29C 45/26-45/37 B29C 33/00 B29C 33/38-33 / 42 B22D 17/32 G06F 17/50

Claims (21)

(57) [Claims] 1. A three-dimensional model construction means for constructing a three-dimensional model in which at least a part of a cavity in which a fluid flows is divided into a large number of microelements, and in each microelement, the microelement is located at a position close to a cavity wall surface. In some cases, the flow conductance κ of the fluid is determined so as to have a small value, while in the case of a distant position, the flow conductance κ of the fluid is determined so as to have a large value, and the flow conductance κ An apparatus for analyzing a flow process of a fluid, comprising: a pressure calculating means for obtaining a pressure of the fluid in each of the microelements based on the pressure and a means for outputting an analysis result . 2. A three-dimensional model construction means for constructing a three-dimensional model in which at least a part of a cavity in which a fluid flows is divided into a large number of microelements, and in each microelement, the microelement is located at a position close to a cavity wall surface. In some cases, the flow conductance κ of the fluid is determined so as to have a small value, while in the case of a distant position, the flow conductance κ of the fluid is determined so as to have a large value, and the flow conductance κ An analysis apparatus for analyzing a fluid flow process, comprising: a pressure change calculating means for obtaining a pressure change of the fluid in each of the microelements based on the pressure information; and an analysis result output means . 3. A three-dimensional model construction means for constructing a three-dimensional model in which at least a part of a cavity in which a fluid flows is divided into a large number of microelements, and in each microelement, the microelement is located at a position close to a cavity wall surface. In some cases, the flow conductance κ of the fluid is determined so as to have a small value, while in the case of a distant position, the flow conductance κ of the fluid is determined so as to have a large value, and the flow conductance κ is determined. A flow velocity calculating means for calculating a flow velocity of the fluid in each of the microelements based on the above, and an analysis result output means, comprising: 4. A three-dimensional model in which at least a part of a cavity in which a fluid flows is divided into a number of small elements,
Fine small elements have you in each of said micro-elements are close to the cavity wall
To a small value when it is located
When it is at the position, the flow conductance κ of the fluid is determined so as to be a large value, the pressure of the fluid in each of the microelements is obtained based on the obtained flow conductance κ, and the fluid is obtained by the obtained pressure. An analysis method of a fluid flow process, comprising analyzing a flow process of a fluid and outputting an analysis result. 5. A three-dimensional model in which at least a part of a cavity in which a fluid flows is divided into a number of small elements,
I said to your stomach fine small element in each micro-element cavity wall
If it is closer, the value will be smaller, while
The flow conductance κ of the fluid is determined so as to be a large value when the position is at a high position, the pressure change of the fluid in each of the microelements is determined based on the obtained flow conductance κ, and the obtained pressure change Analyzing the flow process of the fluid, and outputting an analysis result,
Analysis method of fluid flow process. 6. A three-dimensional model in which at least a part of a cavity in which a fluid flows is divided into a number of small elements,
Fine small element cavity have you to each microelement fluid
If it is located near the wall, set it to a small value.
On the other hand, when located at a distant position, the flow conductance κ is determined so as to have a large value, the flow velocity of the fluid in each of the microelements is determined based on the obtained flow conductance κ, and the obtained flow velocity Analyzing the flow process of the fluid by using the method, and outputting an analysis result. 7. The flow conductance κ in the microelement is determined by the shortest distance R between each microelement and the cavity wall surface.
Characterized by a function F (R, η) that increases with an increase in the material viscosity η of the fluid and decreases with an increase in the material viscosity η of the fluid. Analysis method of flow process. 8. The flow conductance κ in the microelement is calculated by the following equation. 7. The method according to claim 4, wherein η represents the material viscosity of the fluid, and x, y and z represent the positions of the microelements. . 9. A three-dimensional model construction means for constructing a three-dimensional model in which at least a part of an injection molded article is divided into a large number of minute elements, and in each minute element, the minute element is located at a position close to the surface of a molding die. In the case, the flow conductance κ of the injection molding material is determined so as to have a small value, while the flow conductance deciding means for determining the flow conductance κ of the injection molding material so as to have a large value when it is at a distant position. a pressure calculating means for determining the pressure of the injection molding material in each small elements based on the flow conductances kappa, the injection molding conditions determined injection molding process for which is characterized by comprising an output means of the analysis results Analysis device. 10. A three-dimensional model construction means for constructing a three-dimensional model in which at least a part of an injection molded article is divided into a large number of minute elements, and in each minute element, the minute element is located at a position close to the surface of a molding die. In the case, the flow conductance κ of the injection molding material is determined so as to have a small value, while the flow conductance deciding means for determining the flow conductance κ of the injection molding material so as to have a large value when it is at a distant position. injection molding for injection molding condition determination, wherein the pressure change calculating means for determining the pressure variation of the injection molding material in each small elements based on the flow conductances kappa, to become an output means of the analysis results Process analysis equipment. 11. A three-dimensional model construction means for constructing a three-dimensional model obtained by dividing at least a part of an injection-molded article into a large number of microelements, and in each of the microelements, the microelement is located at a position close to a surface of a molding die. In the case, the flow conductance κ of the injection molding material is determined so as to have a small value, while the flow conductance deciding means for determining the flow conductance κ of the injection molding material so as to have a large value when it is at a distant position. injection molding for injection molding condition determination, wherein a flow rate calculation means based on the flow conductances κ determined the flow rate of the injection molding material in each of microelements, to become an output means of the analysis results Process analysis equipment. 12. build a three-dimensional model divided at least a portion of the injection molded article to a large number of microelements, fine small elements have contact to the respective microelements <br/> is positioned close to the cavity wall
In the case of a distant position,
In this case, the flow conductance κ of the injection molding material is determined to be a large value, the pressure of the injection molding material in each of the microelements is determined based on the obtained flow conductance κ, and the obtained pressure An analysis method of an injection molding process for determining injection molding conditions, characterized by analyzing an injection molding process of an injection molded article and outputting an analysis result. 13. build a three-dimensional model divided at least a portion of the injection molded article to a large number of microelements, located near closer said your stomach fine small element cavity walls each microelement
To a small value, while it is far away
In this case, the flow conductance κ of the injection molding material is determined so as to have a large value, and the obtained flow conductance κ is obtained.
A pressure change of the injection molding material in each of the microelements based on the obtained pressure change, analyzing the injection molding process of the injection molded article by the obtained pressure change, and outputting an analysis result. Analysis method of injection molding process for decision. 14. At least a portion of the building a large number of three-dimensional model divided into small elements, the fine small element cavity wall surface have contact to each minute element of the injection molding material injection molded article
If the position is close to, the value will be small, while
When it is located at a distant position, the flow conductance κ is determined so as to have a large value, and the obtained flow conductance κ is obtained.
Injection molding conditions, wherein a flow velocity of the injection molding material in each of the microelements is obtained based on the above, an injection molding process of the injection molded article is analyzed by the obtained flow velocity, and an analysis result is output. Analysis method of injection molding process for decision. 15. The flow conductance κ of said microelements increases with the increase of the shortest distance R between each of said microelements and the surface of a molding die, and with the increase of the material viscosity η of said injection molding material. The method according to any one of claims 12 to 14, wherein the determination is made by a decreasing function F (R, η). 16. The flow conductance κ in the microelement is calculated by the following equation: 15. The method for analyzing an injection molding process according to claim 12, wherein η represents the material viscosity of the injection molding material, and x, y and z represent the positions of the microelements. . 17. A three-dimensional model in which injection molding conditions of an injection molded article are determined, and at least a part of the injection molded article is divided into a large number of microelements, and in each of the microelements, the microelement is formed on the surface of a molding die. If the position is close to, the flow conductance κ of the injection molding material is determined to be a small value,
On the other hand, when located at a distant position, the flow conductance κ of the injection molding material is determined so as to have a large value, and the pressure of the injection molding material in each of the microelements is obtained based on the obtained flow conductance κ. And finally determining an injection molding condition based on the distribution of the pressure, and manufacturing an injection molded product based on the finally determined injection molding condition. 18. A three-dimensional model in which injection molding conditions of an injection molded article are determined, and at least a part of the injection molded article is divided into a large number of microelements, and in each of the microelements, the microelement is a surface of a molding die. If the position is close to, the flow conductance κ of the injection molding material is determined to be a small value,
On the other hand, when located at a distant position, the flow conductance κ of the injection molding material is determined so as to have a large value, and the pressure change of the injection molding material in each of the microelements is determined based on the obtained flow conductance κ. A method for manufacturing an injection-molded article, comprising: finally determining injection molding conditions based on the determined distribution of the pressure change; and manufacturing an injection-molded article based on the finally determined injection molding conditions. 19. A three-dimensional model in which injection molding conditions of an injection molded article are determined, and at least a part of the injection molded article is divided into a large number of microelements, and in each of the microelements, the microelement is a surface of a molding die. If the position is close to, the flow conductance κ of the injection molding material is determined to be a small value,
On the other hand, when located at a distant position, the flow conductance κ of the injection molding material is determined to be a large value, and the flow velocity distribution of the injection molding material in each of the microelements is determined based on the obtained flow conductance κ. A method for producing an injection-molded article, wherein injection molding conditions are finally determined based on the obtained distribution of the flow velocity, and an injection-molded article is produced based on the finally determined injection molding conditions. 20. A method according to claim 20, wherein said injection molding conditions include any one of a shape of said injection molded article, a mold shape, a material injection speed, a material temperature, a mold temperature and an injection molding material. Item 20. The method for producing an injection-molded article according to any one of Items 17 to 19. 21. An injection molded article produced by the method for producing an injection molded article according to claim 17.