JPH0899341A - Device and method for analysis of fluid flowing process, device and method for analysis of injection molding process, injection molded product and manufacture of injection molded product - Google Patents

Abstract

PURPOSE: To provide an analysis device and an analysis method for analyzing the flowing process of a fluid including an injection molding process, an analysis device and an analysis method for the injection molding process, an injection molded product and a manufacturing method for the injection molded product by using a three-dimensional model composed of a cavity, in which a fluid is flowed, divided into fine elements and also using the practical computation time. CONSTITUTION: A three-dimensional model composed of a cavity in which a fluid is flowed into a number of very fine elements is constituted, and flowing conductance (k) is determined so that the very fine elements are of small value in the case that they are positioned close to a cavity wall, while the elements are of large value in the case they are positioned far away the cavity wall, and pressure and pressure variation or flowing speed for respective very fine elements are computed based on the flowing conductance.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Generally, an analysis method such as an injection molding process for reproducing a fluid flow process including an injection molding process by computer simulation has 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.

These methods of analyzing the injection molding process have contributed to higher quality, higher efficiency and lower cost in product development of injection molded products and the like. Regarding the utilization method, etc., for example, JP-A-3-224712 and JP-A-4-15.
It is disclosed in Japanese Patent Application Laid-Open No. 2120, Japanese Patent Application Laid-Open No. 4-305424, Japanese Patent Application Laid-Open No. 4-331125 and the like. In each of the injection molding process analysis methods, a change in pressure, temperature, shear stress, or the like at each part is obtained using a two-dimensional model.

In these conventional methods for 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). Each part of is divided into a number of two-dimensional microelements such as triangles or quadrilaterals, and a numerical analysis method by a computer is used to obtain changes in pressure, temperature, or shear stress in each microelement. In the conventional injection molding process analysis method, if the cavity shape can be approximated by a combination of two-dimensional figures, such as when the thickness of the cavity is thin, the highly accurate analysis result can be obtained. You can

However, in the case of a product having a wall thickness of more than 5 mm or a small molded product such as a connector having a small overall size, the influence of the three-dimensional flow such as the flow in the wall thickness direction appears strongly, and therefore the accuracy of the conventional analysis method is high. I couldn't analyze it well. In addition, even in the case of thin-walled molded products, in order to accurately analyze the local flow state such as steps and corners, most useful information cannot be obtained by the conventional method using planar elements. It 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 intersecting portion can be accurately expressed. There wasn't.

Therefore, a method of using a three-dimensional model as shown in FIG. 3 and a general numerical fluid analysis method represented by a finite element method or a difference method may be considered. In this case, the target model is divided into three-dimensional minute elements such as a hexahedron, a triangular pyramid, and a triangular prism. By using such a model and performing an analysis by a general computational fluid dynamics method, it is possible to make a model faithful to the actual shape and improve the accuracy of the analysis.

However, if such a general three-dimensional analysis method is applied, the amount of calculation becomes enormous and the calculation time becomes very 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 affects the viscosity also changes with time.
In order to analyze such complicated flows three-dimensionally, a huge amount of calculation time and computer capacity were required. Therefore, it was practically difficult to substitute trial production with an actual machine by simulation to achieve efficiency and cost reduction.

Therefore, it is preferable to manufacture the injection-molded product by obtaining the injection-molding conditions of the injection-molded product by the conventional method and apparatus for analyzing the injection-molding process as described above, because the accuracy of the analysis is insufficient. There was a problem that the injection molded article could not be manufactured under the conditions, the productivity was very low, or both.

Further, the injection-molded product manufactured by such a manufacturing process has a problem in strength and the like because it is not manufactured under the optimum conditions.

[0011]

The first object of the present invention has been made in view of the above problems, and in the analysis of the fluid flow process, the shape of the flow path of the fluid is determined by using a three-dimensional model. An object of the present invention is to provide an analyzing device and an analyzing method of a fluid flow process which faithfully reproduces and realizes a precise analysis within a practical calculation time.

A second object of the present invention is to faithfully reproduce the shape of the molded product using a three-dimensional model in the analysis of the injection molding process of the injection molded product, and within a practical calculation time. An object of the present invention is to provide an analysis device and an analysis method for an injection molding process that realizes highly accurate analysis.

A third object of the present invention is to analyze the 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 product manufactured under the optimum conditions by using such a method for manufacturing an injection-molded product.

[0015]

According to the present invention, 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 of the microelements. The fluid flow conductance κ is determined to be a small value when the minute element is near the cavity wall surface, and is determined to be a large value when the minute element is distant from the cavity wall surface. An apparatus for analyzing a fluid flow process, comprising: flow conductance determining means; and pressure calculating means for calculating the pressure of the fluid in each of the minute elements based on the flow conductance κ.

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 the cavity in which the fluid flows is divided into a large number of microelements, and the microelements in each microelement are A flow conductance determination means for determining the fluid flow conductance κ so that the fluid flow conductance κ has a small value when the position is close to the cavity wall surface, and has a large value when the position is far from the cavity wall surface. And a pressure change calculation means for calculating the pressure change of the fluid in each of the microelements based on the flow conductance κ.

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 the cavity in which the fluid flows is divided into a large number of microelements, and the microelements in each microelement are A flow conductance determination means for determining the fluid flow conductance κ so that the fluid flow conductance κ has a small value when the position is close to the cavity wall surface, and has a large value when the position is far from the cavity wall surface. And a flow velocity calculation means for calculating the flow velocity of the fluid in each of the minute elements based on the flow conductance κ.

Further, according to the present invention, 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 is constructed, and a fluid flow conductance κ of each minute element is determined and obtained. A method for analyzing a fluid flow process, characterized in that the pressure of the injection molding material in each of the minute elements is obtained based on the obtained flow conductance κ, and the flow process of the fluid is analyzed by the obtained pressure. Will be provided.

Further, according to the present invention, a three-dimensional model in which at least a part of the cavity through which the fluid flows is divided into a large number of minute elements is constructed, and the fluid flow conductance κ of each of the minute elements is determined. A pressure change of the fluid in each of the microelements based on the obtained flow conductance κ, and a flow process of the fluid is analyzed based on the obtained pressure change. An analysis method is provided.

Further, according to the present invention, a three-dimensional model in which at least a part of the cavity in which the fluid flows is divided into a large number of minute elements is constructed, and the flow conductance κ of each of the minute elements of the fluid is determined and obtained. Based on the obtained flow conductance κ, the flow velocity of the fluid in each minute element is obtained, and the flow process of the fluid is analyzed by the obtained flow velocity.

Further, according to the present invention, in a preferable mode of the method for analyzing the fluid flow process, the flow conductance κ in the minute elements is increased as the shortest distance R between each minute element and the cavity wall surface is increased. And a preferred embodiment of the method for analyzing a fluid flow process, characterized in that it is determined by a function F (R, η) that decreases as the viscosity η of the fluid increases.

According to the present invention, the flow conductance κ in the microelement is

[Equation 3] (Η is the viscosity of the fluid, x, y and z are the positions of the microelements), and a preferable embodiment of the method for analyzing the fluid flow process is provided.

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 microelements are formed on the surface of the molding die. Determine the flow conductance κ of the injection molding material so that it will be a small value at a close position, while determining the flow conductance κ of the injection molding material so that it will be a large value at a far position. An analyzer for an injection molding process is provided, which is provided with means and pressure calculating means for calculating the pressure of the injection molding material in each of the minute elements based on the flow conductance κ.

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 an injection-molded article is divided into a large number of microelements, and in each of the microelements, the microelement is a molding die. The flow conductance κ of the injection molding material should be small so that it is close to the surface.
On the other hand, flow conductance determining means for determining the flow conductance κ of the injection molding material such that the flow conductance κ of the injection molding material becomes a large value at a distant position, and the injection molding material in each of the microelements based on the flow conductance κ. And a pressure change calculation means for calculating the pressure change of the injection molding process.

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 a molding die. The flow conductance κ of the injection molding material should be small so that it is close to the surface.
On the other hand, flow conductance determining means for determining the flow conductance κ of the injection molding material such that the flow conductance κ of the injection molding material becomes a large value at a distant position, and the injection molding material in each of the microelements based on the flow conductance κ. An apparatus for analyzing an injection molding process is provided, which comprises:

Further, according to the present invention, a three-dimensional model in which at least a part of an injection-molded product is divided into a large number of minute elements is constructed, and the flow conductance κ of the injection-molding material in each of the minute elements is determined and obtained. Based on the obtained flow conductance κ, the pressure of the injection molding material in each of the microelements is obtained, and the injection molding process of the injection molded article is analyzed by the obtained pressure. An analysis method is provided.

Further, according to the present invention, a three-dimensional model in which at least a part of an injection-molded product is divided into a large number of minute elements is constructed, and the flow conductance κ of the injection-molding material in each of the minute elements is determined and obtained. Characterized in that the pressure change of the injection molding material in each of the minute elements is obtained based on the obtained flow conductance κ, and the injection molding process of the injection molded article is analyzed by the obtained pressure change.
An injection molding process analysis method is provided.

Further, according to the present invention, a three-dimensional model in which at least a part of an injection-molded article is divided into a large number of minute elements is constructed, and the flow conductance κ of each of the minute elements of the injection-molding material is determined and obtained. The flow velocity of the injection molding material in each of the microelements is obtained based on the obtained flow conductance κ, and the injection molding process of the injection molded article is analyzed by the obtained flow velocity.
An injection molding process analysis method is provided.

Further, according to the present invention, the flow conductance κ in each of the minute elements is increased with an increase in the shortest distance R between each of the minute elements and the mold surface, and the material viscosity of the injection molding material is increased. Function that decreases with increasing η
A preferred embodiment of the method of analyzing the injection molding process is provided, characterized in that it is determined by F (R, η).

Further, according to the present invention, the flow conductance κ in the microelement is

[Equation 4] (Η is the material viscosity of the injection molding material, and x, y and z are the positions of the microelements) are solved to solve the above problem, and a preferred embodiment of the method for analyzing the injection molding process is provided.

Further, according to the present invention, the injection molding conditions for the injection molded product are determined, and a three-dimensional model is constructed by dividing at least a part of the injection molded product into a large number of minute elements, and the three-dimensional model is constructed in each of the minute elements. The flow conductance κ of the injection molding material is set to a small value when the minute elements are located close to the surface of the mold, while the flow conductance κ of the injection molding material is set to a large value when the microelements are located far away.
And determine the pressure of the injection molding material in each of the microelements based on the obtained flow conductance κ,
An injection-molded article manufacturing method, characterized in that 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. To be done.

Further, according to the present invention, the injection molding conditions of the injection molded product are determined, a three-dimensional model is constructed by dividing at least a part of the injection molded product into a large number of minute elements, and the three-dimensional model is constructed in each of the minute elements. The flow conductance κ of the injection molding material is set to a small value when the minute elements are located close to the surface of the mold, while the flow conductance κ of the injection molding material is set to a large value when the microelements are located far away.
The pressure change of the injection molding material in each of the microelements is obtained based on the obtained flow conductance κ, the injection molding conditions are finally determined based on the obtained pressure change distribution, and the final determination is made. An injection-molded article manufacturing method is provided, which is characterized in that an injection-molded article is manufactured on the basis of the injection molding conditions.

Further, according to the present invention, the injection molding condition of the injection molded product is determined, and a three-dimensional model is constructed by dividing at least a part of the injection molded product into a large number of minute elements, and the three-dimensional model is constructed in each of the minute elements. The flow conductance κ of the injection molding material is set to a small value when the minute elements are located close to the surface of the mold, while the flow conductance κ of the injection molding material is set to a large value when the microelements are located far away.
Then, the flow velocity distribution of the injection molding material in each of the microelements is determined based on the obtained flow conductance κ, the injection molding conditions are finally determined based on the obtained flow velocity distribution, and the final There is provided a method for producing an injection-molded article, which comprises producing an injection-molded article 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 product, 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 manufacturing an injection-molded article is provided. Further, according to the present invention, there is provided an injection-molded article manufactured by any one of the above-described injection-molded article manufacturing methods.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of a preferred embodiment of an injection molding process analysis apparatus and analysis method, which is an example of a fluid flow process analysis apparatus and analysis method according to the present invention, will be described in detail with reference to the drawings. To do. An example of a preferred embodiment of the method for manufacturing an injection-molded article will be described together.

FIG. 1 is a diagram showing a hardware configuration example of an injection molding process analyzing apparatus of the present invention. Computer 1
An input device 103, a display device 104, and an auxiliary storage device 102 are connected to 01. By the input device 103,
For example, the input of the injection molding condition of the injection molded product to be analyzed and the data of the three-dimensional model are accepted, and such data is stored in the auxiliary storage device 102. The computer 101 stores this data in the internal RA according to the operator's instruction.
It is read into M (random accessible volatile memory) 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. Further, the output of the analysis result may be performed to 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 a view of the injection molding process analyzing apparatus of 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 device. 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 mold shape, the material injection speed, the material temperature, the mold temperature or the injection molding material, etc.) are input (step 1). ). Next, the shape is divided into three-dimensional minute elements as shown in FIG. 3, for example, to construct a three-dimensional model of the product (step 2). Next, the flow conductance κ in each microelement is determined (step 3). Subsequently, the flow conductance κ of each microelement determined in step 3 is used to obtain the pressure of the injection molding material in each microelement (hereinafter referred to as “material pressure”) (step 4). Here, the change in pressure of each minute element may be obtained. Alternatively, the flow velocity of the injection molding material in each minute element may be directly obtained from the obtained material pressure distribution. The analysis result thus obtained is graphically processed, for example, and displayed in the form of contour lines or graphs (step 5). You may output to a printer apparatus etc. as mentioned above.

Further, in the case of manufacturing an injection-molded article by using the analysis result of the injection-molding process, the pressure, pressure change or flow rate obtained as described above is 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 an abnormal pressure, pressure change, or flow velocity is obtained. If molding failure is predicted from the obtained analysis result, the injection molding conditions are changed (step 7), and the procedure returns to step 1 again to perform 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 minute element will be described in detail.

The generally known continuous equation (1) is used as the method for obtaining the material pressure in injection molding. Equation (1) is an equation that expresses that the sum of the inflow rate and the outflow rate to an arbitrary region in the fluid is zero, and is established by assuming that the fluid is incompressible. If the fluid has compressibility, the right side is non-zero, but the following arguments hold in the same way.

[0041]

[Equation 5] Where x, y, z are three-dimensional spatial coordinates, and U, V
, W is the flow velocity of the injection molding material in each coordinate axis direction. This equation 1 is an equation with U, V, and W as unknown variables, and it is generally said that it is necessary to solve this equation and the equation of motion with unknown variables of pressure P and shear stress derived from the flow velocity. When dealing with dimensional flow, there are four unknown variables.

The present inventor uses the following equation (2) in solving this equation (1) to determine the flow velocity in each direction.
It was found that by eliminating U, V, and W from Eq. (1) and reducing the number of unknown variables from four to only one, the calculation time can be significantly reduced. In this case, the calculation time when the three-dimensional model is used can be 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 equation (2) above, κ is the flow conductance.
This equation 2 is called a Darcy flow equation, and is an equation representing the permeation flow in a porous material. That is, the three-dimensional coordinate axes x, y,
The flow velocities U, V and W in the z direction are assumed to be proportional to the pressure gradient in each direction.

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

[0045]

[Equation 7] Equation (3) is isomorphic to the general equation for heat conduction. In the heat conduction problem, if the temperature T or the temperature gradient at the region boundary is set as a boundary condition in advance for a region divided into arbitrary minute elements, the temperature distribution inside the region can be calculated by the finite element method, difference method, control volume method, and other numerical values. It can be obtained by an analytical method. Therefore, if the pressure P or pressure gradient at the region boundary is set as a boundary condition for a region divided into arbitrary minute elements, equation (3) can also be solved by using an analysis method or analysis program for the heat conduction problem. It is possible to determine the pressure distribution of the material.

Regarding the method of setting the boundary conditions, for example, the pressure gradient value obtained from the injection pressure value or the injection flow rate is set in the material inflow portion, and there is no inflow or outflow at the area boundary in contact with the surface of the mold, so that the pressure gradient is zero. And the pressure at the free end of the flow, which is the free surface, is set to atmospheric pressure.

Furthermore, in injection molding, the filling portion of the material increases with time, so the pressure distribution also changes with time. Such a temporal change in the pressure distribution (distribution of pressure change) can be obtained by finding the change in the shape of the filling region according to the total amount of newly filled material and solving the equation (3) again. The control volume method and the FAN method (Flow Analysis Network Method), which are used in the conventional analysis method of the injection molding process, are used to determine the change in the shape of the filling region.
d) etc. are used.

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

In some cases, the actual injection-molded product may have a part that is thin enough that it is not necessary to consider the flow of the injection-molding material in the thickness direction. For such a part, using a two-dimensional model,
You may use it instead of (2) and analyze it two-dimensionally. This can further improve the overall calculation speed.

[0050]

[Equation 8] Here, H is the thickness of the material channel, and η is the material viscosity.

Next, the method for 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 channel shape and the material viscosity as shown in equation (4). Is preferably used.

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

According to the knowledge of the inventor of the present invention, the fluidity of the injection molding material is higher as the distance from the mold surface is higher, and lower as the distance is closer. Therefore, in general, it is preferable to determine the flow conductance to have a small value when the minute element is located close to the surface of the mold (that is, the cavity wall surface), and to have a large value when the minute element is located far away. 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 mold surface or the shortest distance from each microelement vertex to the mold surface, and η is the material viscosity.

As the function F of the equation (5) is farther from the surface of the mold, that is, the larger R is, the effect of the frictional force between the mold and the material is decreased, so that the flow conductance κ is increased.
Also, as the material viscosity η is larger, the fluidity is lower, and therefore the flow conductance κ decreases. For example, κ = a
R / η + b is defined as a function such that κ increases with increasing R and κ decreases with increasing η. In this case, a is a positive proportional coefficient and b is R = 0, that is, a coefficient indicating the flow conductance on the surface of the mold. These constants
a and b are determined, for example, by conducting experiments with a typical injection molded product. R / illustrated here
The linear expression regarding η has a characteristic that the calculation time is completed in a short time as the simplest mode in which the function F 1 is specified. Also,
Depending on the type of injection-molded product, another form of calculation formula in which the analysis result and the actual molding result are in good agreement may be used.

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

[0058]

[Equation 10] Further, the flow conductance κ may be obtained as follows.

That is, the present inventor 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 the material viscosity.

[0060]

[Equation 11] The present inventor has found that this equation (7) is an equation expressing the balance of forces in the flow field where the viscous force is dominant,
Substituting the first equation of, the flow velocity U is eliminated, and the pressure P
It was found that it can be obtained by omitting the second derivative terms with respect to x, y, and z of. By omitting this second-order differential term, κ can be obtained by the simple method described below.

[0061]

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

Further, the approximate value of the material viscosity according to the equation (6) is calculated by
By substituting in (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, as compared with the method of determining the flow conductance κ using the above equation (5), the heat conduction equation needs to be solved, but the calculation time is longer, but the accuracy for an arbitrary shape is higher. It becomes possible to obtain good flow conductance. As mentioned above, since equation (7) is derived based on equation (8), which is an equation expressing the balance of forces in the flow field where the viscous force is dominant, we use equation (5). The physical validity of the obtained value is higher than that of the method.
Therefore, it is possible to always give accurate analysis results without being influenced by the shape of the injection-molded product or the model of division into minute elements.

For example, when a minute element having a cross-sectional shape as shown in FIGS. 4 and 5 is used, according to the method of determining the flow conductance using the equation 5, minute elements regularly divided as shown in FIG. 4 are used. Although the flow conductance can be determined accurately and at high speed with the element shape, the position of the center of gravity of the adjacent elements is not constant with respect to the mold surface in the irregular minute element shape as shown in Fig. 5, so the obtained flow conductance is also inaccurate. May be

Generally, fine element division for use in numerical analysis can be automatically carried out by software called a preprocessor, and particularly division is easily performed even for a product having a complicated shape with many protrusions and holes. can do. When such automatic division is performed, the microelement shape is generally irregular, but the method that uses Eq. (7) can suppress the effect of the microelement shape to a small size, and it can Even if it is applied to the injection-molded product, it is possible to perform highly accurate analysis.

In addition to the above, there are various methods for determining the flow conductance, and a method that realizes high calculation accuracy and calculation speed, especially in the case of a specific shape, can be considered.

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

It is possible to obtain the material pressure, the pressure change or the distribution of the flow velocity of the injection molding material when an injection molded article is manufactured under the injection molding conditions given as described above. At this time, these results 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 little strain, 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. Is preferred. Further, regarding the temporal change of the pressure, it is not preferable that the peak pressure is generated due to the rapid pressure increase. By applying such a pressure determination criterion, it is possible to determine the quality of the molding state. Further, it is preferable to apply the criterion based on the flow velocity obtained as described above.

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

When a defect is expected by the above determination method, the molding die design, product design,
By modifying the molding conditions or the materials used, it is possible to manufacture injection-molded articles without defects.

The first modification method is a method of modifying the shape of the mold to change the material flow path and the like. Here, the molding die shape means a material flow path from a material melt injection nozzle to a product shape portion, which is generally called a sprue, runner, or gate. For example, if it is determined that the pressure loss is too large because the flow length from the nozzle to the end of the product is long, the flow length is reduced by branching the runners and flowing them into the product shape part from multiple gates. be able to.

The second modification method is to modify the shape of the injection-molded product and change the material flow path. For example, when the pressure gradient in the 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.

The 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 it is expected that molding will be difficult due to a sharp rise in pressure at the material inlet at a certain time, decrease the material injection speed at this time, or increase the material temperature or mold temperature. The pressure rise can be reduced by.

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

The above correction methods may be carried out individually or in combination.
Further, it is preferable that the above correction is automatically performed by using an expert system or the like.

The injection molding conditions are re-examined as described above, and again analyzed under the condition that a preferable injection molding result is considered to be obtained, by the above-mentioned analyzer for the injection molding process, until the injection molding condition for obtaining the optimum result is found. Repeat this. When the injection molding conditions that give the optimum result are found, injection molding is carried out under the conditions to manufacture an injection molded product.

The present invention can be applied in principle to all shapes of injection molded products, but is particularly effective for products in which a three-dimensional shape effect is likely to appear.

A product which is likely to exhibit a three-dimensional shape effect is
Thick-walled molded products whose wall thickness exceeds 5 mm, or 1
Even if the wall thickness is ~ 2mm, the overall product size is 10mm.
A small molded product of a certain size, which is relatively susceptible to the influence of flow in the thickness direction. A three-dimensional analysis is also effective for local flow in a portion where the flow suddenly changes in the thickness direction, such as flow in a stepped portion or a corner portion.

Furthermore, the method of analyzing the injection molding process according to the present invention can be used in combination with the conventional two-dimensional method, and the conventional two-dimensional method can be applied to a portion where three-dimensional flow does not matter. It is also possible to use elements to improve the efficiency of the analysis.

In the present invention, as the molding die, a metal mold or the like obtained by processing a metal by a precise machining means such as electric discharge machining is used.

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

That is, it can be applied to obtain the pressure distribution during extrusion flow, the distribution of pressure change or the flow velocity distribution of material in the flow in the die at the time of extrusion molding of a round bar or a flat plate, or profile extrusion molding. Pressure gradient and flow velocity
In a portion close to 0, the quality of the molded product is deteriorated due to retention of material and thermal deterioration, so it is necessary to determine the extrusion molding conditions such as the die shape so as to prevent the retention portion from occurring. The present invention is also suitable for such applications.

Similarly, the screw portion of an injection molding machine or an extrusion molding machine can also be applied to determine conditions such as a screw design with a small amount of staying portion. It is also possible to calculate the shear stress distribution in the screw groove in an extruder-type kneader and use it for the design for maximizing the shear stress value.

[0085]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following is a detailed description with reference to the drawings of an embodiment of a fluid flow process analyzing apparatus and method according to the present invention, which is an injection molding process analyzing apparatus, analysis method and injection molded article manufacturing method. Explained. FIG. 2 is a flow chart showing the procedure of the method constituting the present invention.

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

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 to construct a three-dimensional model of the injection-molded product. In this embodiment, a hexahedron having eight vertices is used as a minute element, and the shape of the injection-molded product is divided into regular lattice-shaped three-dimensional minute elements.

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

FIG. 7 shows the distribution of the flow conductance κ in the cross section obtained based on the equation 5 using the minute element division model of FIG. 6 in contour lines, and the flow conductance at the portion 15 near the mold surface is shown. Is close to 0, while the flow conductance is 0.02 mm in the part 16 near the thickness center.
² / (Pa ・ sec) indicates that the flow is large and easy. In this way, a smooth κ distribution was obtained.

Then, in step 4 of FIG. 2, κ of FIG.
Based on the distribution, equation (3) was solved by a numerical calculation program similar to the heat conduction analysis to obtain the pressure distribution during injection molding of each microelement. Further, in step 5, these results were graphically processed 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 in contour lines. The series of calculations from step 2 onward were completed in a very short time of about 90 seconds using an engineering workstation.

Further, based on the obtained pressure distribution, a pressure change distribution (FIG. 9) and a flow velocity distribution (FIG. 10) were obtained.
Furthermore, the shear stress distribution was also calculated. 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 judged that there was no particular problem in injection molding, this injection molded product was manufactured.
The manufactured injection-molded product was manufactured under optimum conditions, and thus had excellent properties such as strength.

If a defective molding is expected here, for example, an extreme pressure gradient portion is generated, the shape of the molded product, molding conditions, materials, etc. are changed and the process is repeated from step 1 to obtain a proper product. Obtain design, mold design, molding conditions, etc.

Example 2 For the same injection-molded article as in Example 1, under the same conditions as above except that an irregular minute element division model as shown in FIG. 11 was used, based on equation (5). When the distribution of the flow conductance κ was obtained, as shown in FIG. 12, the flow conductance κ was irregular in the vicinity of the mold boundary.
I got the result that changed. This result cannot be explained physically, and it is clear that it is a calculation error.
This is considered to be because the distance between the center of gravity of adjacent elements and the surface of the molding die, which should be essentially the same, is not the same due to the method of dividing the minute elements.

In such a case, it may be difficult to obtain a strict analysis result, but 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 the flow conductance κ is obtained based on the equation (5) at a high calculation speed, it can be effectively used for determining the rough conditions at the initial stage of the injection molding condition determination.

[Embodiment 3] With respect to the same injection-molded products as in Embodiments 1 and 2, the flow element conductance κ of the flow conductance κ is calculated based on the equation (7) using the same fine element division model as shown in FIG. The injection molding process was analyzed under the same conditions except that the distribution was obtained and the injection molding process was analyzed using this distribution.

FIG. 13 is a contour line representation of the distribution of the flow conductance κ in the cross section obtained based on the equation 7 using the minute element division model of FIG. Although a slightly longer calculation time was required, a smooth κ distribution (distribution range: 0 to 0.02 mm ² / (Pa · sec)) similar to that in FIG. 7 was obtained.

Then, in step 4 of FIG. 2, the pressure distribution during injection molding of each microelement 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. It was Here again, the pressure of each minute element is displayed in contour lines. The obtained pressure distribution was almost the same as that shown in FIG. The series of calculations from step 2 onward was completed in a slightly long time of about 160 seconds using the same engineering workstation as above. In addition, when the pressure distribution is calculated with respect to the same object when the calculation is performed using the conventional general numerical calculation method, it takes about 2500 seconds, for example.

Further, based on the obtained pressure distribution, pressure change (FIG. 15) and flow velocity distribution (FIG. 16) were obtained. Furthermore, the shear stress distribution was also calculated. These results were also almost the same as in Example 1. From the obtained analysis results, it was judged that there was no particular problem in injection molding, and the product was manufactured. Therefore, this injection molded product was manufactured. Since this injection-molded product was manufactured under the optimal conditions similar to those of Example 1, the properties such as strength were excellent.

As in the case of the first embodiment, if a defective molding is expected here, for example, an extreme pressure gradient portion occurs, the shape of the molded product, the molding conditions, the material, or the like is changed to start from step 1. By repeating the process, an appropriate product design, mold design, molding conditions, etc. are obtained.

[0100]

According to the analysis apparatus and method of the injection molding process of the present invention, since the pressure distribution and the like are obtained using the flow conductance κ, a three-dimensional model is used in the analysis of the injection molding process of an injection molded product. It is possible to faithfully reproduce the shape of a molded product by using, and to perform accurate analysis within a practical calculation time.

Further, according to the analysis apparatus and the analysis method of the injection molding process of the present invention, since the flow conductance κ is determined by using the equations such as equations 5 and 7 which have established a fast and precise solution method, the flow conductance κ is determined. κ can be easily obtained, and an accurate analysis result can be obtained in a practical calculation time.

Further, according to the method for manufacturing an injection-molded article of the present invention, by using the above-mentioned analyzer for the injection-molding process,
By determining injection molding conditions such as product shape, mold design, and material selection, high quality injection molded products can be efficiently manufactured.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a hardware configuration example of a fluid flow process (injection molding process) analysis device of the present invention.

FIG. 2 is a flow chart showing an example of a procedure of an injection molding process analysis method and an injection molded article manufacturing method of 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 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 how a target minute element is determined in an embodiment of the present invention.

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

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

9 is a contour diagram showing the results of analyzing the distribution of pressure changes inside the injection-molded article based on the distribution of the flow conductance κ of FIG. 7.

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

FIG. 11 is a state of determining a target minute element according to an embodiment of the present invention.

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

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

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

FIG. 15 is a contour diagram showing the result of analyzing the distribution of pressure change inside the injection-molded article based on the distribution of the flow conductance κ shown 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 the distribution of 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 tetragonal microelements 2: Three-dimensional hexahedral microelements 3: Microelement centroids 4: Shortest distance from microelement centroids to mold surface 5: Microelements Divided product and mold surface contact Part 6: Minute element cross section 7: Minute element 8: Minute element center of gravity 9: Shortest distance from minute element center of gravity to mold surface 10: Contact area between minute element divided product and mold surface 11: Minute element cross section 12: Minute element 13: Geometry analysis model with step 14: Minute element 15: κ contour line 16: κ contour line 17: Minute element 18: κ contour line 20: κ contour line 21: Pressure contour line 22: Pressure contour line 101: Computer 102: Auxiliary storage device 103 : Input device 104: display device

Claims (21)

[Claims] 1. 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 microelements are positioned near a cavity wall surface. A flow conductance determining means for determining the fluid flow conductance κ so as to have a small value in a certain case, and a fluid flow conductance κ so as to have a large value at a distant position, and the flow conductance κ. And a pressure calculating means for calculating the pressure of the fluid in each of the microelements based on the above. 2. 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 at each microelement, the microelements are located near a cavity wall surface. A flow conductance determining means for determining the fluid flow conductance κ so as to have a small value in a certain case, and a fluid flow conductance κ so as to have a large value at a distant position, and the flow conductance κ. And a pressure change calculation means for calculating a pressure change of the fluid in each of the microelements based on the above. 3. 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 at each microelement, the microelements are located near a cavity wall surface. A flow conductance determining means for determining the fluid flow conductance κ so as to have a small value in a certain case, and a fluid flow conductance κ so as to have a large value at a distant position, and the flow conductance κ. And a flow velocity calculating means for calculating a flow velocity of the fluid in each of the microelements based on the above. 4. A three-dimensional model in which at least a part of a fluid flowing cavity is divided into a large number of minute elements,
The flow conductance κ of the fluid in each micro element is determined, the pressure of the fluid in each micro element is obtained based on the obtained flow conductance κ, and the flow process of the fluid is analyzed by the obtained pressure. A method for analyzing a fluid flow process, which comprises: 5. A three-dimensional model in which at least a part of a fluid flowing cavity is divided into a large number of minute elements,
The flow conductance κ of the fluid in each of the microelements is determined, the pressure change of the fluid in each of the microelements is obtained based on the obtained flow conductance κ, and the flow process of the fluid is determined by the obtained pressure change. A method for analyzing a fluid flow process, characterized by performing analysis. 6. A three-dimensional model in which at least a part of a fluid flowing cavity is divided into a large number of minute elements,
The flow conductance κ of each of the microelements of the fluid is determined, the flow velocity of the fluid in each of the microelements is obtained based on the obtained flow conductance κ, and the flow process of the fluid is determined by the obtained flow velocity. A method for analyzing a fluid flow process, which is characterized by analysis. 7. A flow conductance κ in each of the minute elements is defined as a shortest distance R between each of the minute elements and a cavity wall surface.
Of the fluid according to any one of claims 4 to 6, characterized in that it is determined by a function F (R, η) which increases with an increase in the material viscosity 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 minute element is calculated by the following equation: 7. A method for analyzing a fluid flow process according to claim 4, wherein (η represents a material viscosity of the fluid, and x, y and z represent a position of the minute element). . 9. 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 large number of microelements, and the microelements in each of the microelements are located near the surface of the mold. And a flow conductance determining means for determining the flow conductance κ of the injection molding material so that the flow conductance κ of the injection molding material has a small value in the case, and the flow conductance κ of the injection molding material has a large value in the case of a distant position. An injection molding process analysis apparatus, comprising: pressure calculation means for calculating a pressure of the injection molding material in each of the minute elements based on a flow conductance κ. 10. 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 large number of microelements, and each microelement is located at a position close to the surface of the mold. And a flow conductance determining means for determining the flow conductance κ of the injection molding material so that the flow conductance κ of the injection molding material has a small value in the case, and the flow conductance κ of the injection molding material has a large value in the case of a distant position. An injection molding process analysis apparatus, comprising: pressure change calculation means for calculating a pressure change of the injection molding material in each of the minute elements based on a flow conductance κ. 11. A three-dimensional model constructing means for constructing a three-dimensional model in which at least a part of an injection-molded product is divided into a large number of microelements, and the microelements in each of the microelements are located near the surface of the mold. And a flow conductance determining means for determining the flow conductance κ of the injection molding material so that the flow conductance κ of the injection molding material has a small value in the case, and the flow conductance κ of the injection molding material has a large value in the case of a distant position. An injection molding process analysis apparatus, comprising: a flow velocity calculating means for determining a flow velocity of the injection molding material in each of the minute elements based on a flow conductance κ. 12. A three-dimensional model in which at least a part of an injection-molded article is divided into a large number of microelements is constructed, a flow conductance κ of an injection molding material in each of the microelements is determined, and the obtained flow conductance κ is obtained. A method for analyzing an injection molding process, characterized in that the pressure of the injection molding material in each of the microelements is obtained based on the above, and the injection molding process of the injection molded product is analyzed by the obtained pressure. 13. A three-dimensional model in which at least a part of an injection-molded article is divided into a large number of minute elements is constructed, a flow conductance κ of an injection molding material in each of the minute elements is determined, and the obtained flow conductance κ is obtained. The pressure change of the injection molding material in each of the microelements based on
An analysis method of an injection molding process, characterized by analyzing the injection molding process of the injection molded product by the obtained pressure change. 14. A three-dimensional model in which at least a part of an injection-molded product is divided into a large number of minute elements is constructed, a flow conductance κ of each of the minute elements of an injection molding material is determined, and the obtained flow conductance κ is obtained. Based on, to determine the flow rate of the injection molding material in each of the microelements,
An analysis method of an injection molding process, characterized in that the injection molding process of the injection molded article is analyzed based on the obtained flow velocity. 15. The flow conductance κ of the microelements increases with an increase in the shortest distance R between each microelement and the surface of the mold, and with the increase of the material viscosity η of the injection molding material. The method for analyzing an injection molding process according to any one of claims 12 to 14, wherein the method is determined by a decreasing function F (R, η). 16. The flow conductance κ in the minute element is calculated by the following equation: 15. The method for analyzing the 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 minute elements). . 17. A three-dimensional model in which at least a part of the injection-molded product is divided into a large number of micro-elements is established by defining the injection-molding conditions of the injection-molded product, and the micro-elements in each of the micro-elements are the mold surface. Determine the flow conductance κ of the injection molding material so that it will be small when it is close to
On the other hand, the flow conductance κ of the injection molding material is set so as to have a large value at a distant position, and the pressure of the injection molding material in each of the microelements is obtained based on the obtained flow conductance κ and obtained. A method for producing an injection-molded article, which comprises finally determining injection-molding conditions based on the pressure distribution and producing an injection-molded article based on the finally-determined injection-molding conditions. 18. A three-dimensional model in which at least a part of the injection-molded product is divided into a large number of micro-elements is defined by defining injection-molding conditions for the injection-molded product, and the micro-elements in each of the micro-elements are the surface of a mold. Determine the flow conductance κ of the injection molding material so that it will be small when it is close to
On the other hand, the flow conductance κ of the injection molding material is set so as to have a large value when it is at a distant position, and the pressure change of the injection molding material in each of the minute elements is obtained based on the obtained flow conductance κ. A method for producing an injection-molded article, comprising finally determining an injection-molding condition based on the distribution of the pressure change thus obtained, and producing an injection-molded article based on the finally-determined injection-molding condition. 19. A three-dimensional model in which at least a part of the injection-molded product is divided into a large number of micro-elements is established by defining the injection-molding conditions of the injection-molded product, and in each of the micro-elements, the micro-elements are the mold surface. Determine the flow conductance κ of the injection molding material so that it will be small when it is close to
On the other hand, when it is 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 obtained based on the obtained flow conductance κ, A method for producing an injection-molded article, which comprises finally determining an injection-molding condition based on the obtained distribution of the flow velocity and producing an injection-molded article based on the finally-determined injection-molding condition. 20. The injection molding condition includes any one of a shape of the injection molded product, a molding die shape, a material injection speed, a material temperature, a molding die temperature and an injection molding material. Item 20. A method for manufacturing an injection-molded article according to any one of Items 17 to 19. 21. An injection-molded article manufactured by the method for manufacturing an injection-molded article according to claim 17.