JPH09295121A - Method for predicting occurrence of boundary defect in injection molding material and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply predict the boundary defect caused in a molding process. SOLUTION: The adjacent part of surface elements of injection molding material to be allowed to flow is obtained from a mold, and a relative velocity RV of the injection molding material in the adjacent part is obtd. The relative velocity RV is raised to the (a)-th power to obtain a press-contacting parameter CP showing the degree of press-contacting of the surface elements and the sum of solid phases FS of the surface elements is raised to the (b)-th power to obtain a solidifying parameter SP showing the progressing degree of the solidification of the injection molding material. A boundary predicting parameter DP is obtd. from the product of the press-contacting parameter CP by the solidifying parameter SP. Then the value of the boundary predicting parameter DP is compared with a reference value, when the boundary predicting parameter DP is larger than this reference value, it is predicted that the boundary is caused at the adjacent part of the surface elements. On the other hand. When the boundary predicting parameter DP is smaller than this reference value, it is predicted that the boundary is not caused at the adjacent part of the surface elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for predicting a boundary defect of an injection material, such as a boundary defect in an aluminum melt material, which occurs in an injection molding process.

[0002]

2. Description of the Related Art For example, in an injection molding process such as aluminum die casting, the state of the flow at the time of injection or filling has a great influence on the quality, so that the process in which the melt flows into the cavity and solidifies, Applying a filling simulation considering both flow analysis and solidification analysis is being considered.

Since the result of the calculation of this filling simulation is the filling process and the time change of temperature, speed and pressure, changes in the injection conditions and mold design for the purpose of quality improvement, etc. Considered based on the calculation results of.

[0004]

However, in such a conventional filling simulation, the injection process is performed based on the empirical rule from the filling process obtained as a result of calculation and each value of temperature, speed, and pressure with time. Although it is possible to study changes in the mold design and mold design, it was extremely difficult to predict even the boundary defects that occur in the injection molding process.

For example, in order to predict a boundary defect from the result of this simulation, it is inevitable to make a filling process diagram and a vector diagram and visually judge from these created diagrams. And requires skill. In particular, it is difficult to make a prediction for a complicated three-dimensional structure.

The present invention has been made in order to solve the above-mentioned conventional problems. For example, it occurs in a confluent portion of fluids having different solidification states and different speeds, such as a molten metal boundary in aluminum die casting. An object of the present invention is to provide a method and apparatus for predicting the occurrence of a boundary defect in an injection material that can easily and quantitatively predict a defect.

[0007]

The present invention for achieving the above object has the following constitution.

A first aspect of the present invention is a method of predicting a boundary defect that occurs when an injection material is poured into a mold to form a desired shape, and the adjacent portions of surface elements of the injection material poured from the mold are adjacent to each other. Then, the relative velocity RV of the injection material in the adjacent portion is obtained, and the relative velocity RV is used as a crimping parameter CP indicating the degree of crimping of the surface elements, and the sum of the solid phase ratios FS of the surface elements is injected. A boundary defect prediction parameter DP is obtained from the product of the pressure bonding parameter CP and the solidification parameter SP, and the value of the boundary defect prediction parameter DP is compared with a reference value to determine the boundary. If the defect prediction parameter DP is larger than the reference value, it is predicted that a boundary will occur in the adjacent portion between the surface elements, while the boundary defect prediction is performed. If the parameter DP is smaller than the reference value, the adjacent portions between said surface element is generated prediction method of a boundary defect of the injection material, characterized by predicting a boundary defect does not occur.

According to such a method, as in the conventional case,
It is no longer necessary to predict the occurrence of defects from the distribution of pressure, velocity, and temperature obtained from the filling simulation by empirical rules, and it becomes possible to easily and quantitatively predict the occurrence of boundary defects directly from the calculation results.

This makes it easy to reset the initial temperature condition and the injection speed at which boundary defects do not occur, and
For example, it will be possible to reduce the thickness of aluminum die cast parts and shorten the time from mold design to part manufacture.

A second aspect of the present invention is a boundary defect occurrence predicting device for an injection material, which predicts a boundary defect that occurs when the injection material is poured into a mold to form a desired shape. Means for determining the adjacent portions of the surface elements of the injection material, means for determining the relative speed RV of the injection material in the adjacent portions, and means for determining the relative speed RV as a crimping parameter CP indicating the degree of crimping of the surface elements. And a solidification parameter SP indicating the degree of solidification of the injection material, which is the sum of the solid fractions FS of the surface elements.
Boundary defect prediction parameter DP from the product of the pressure bonding parameter CP and the solidification parameter SP
And a value of the boundary defect prediction parameter DP is compared with a reference value to calculate the boundary defect prediction parameter DP.
Is larger than the reference value, it is predicted that a boundary will occur in the adjacent portions of the surface elements, while if the boundary defect prediction parameter DP is smaller than the reference value, a boundary is formed in the adjacent portions of the surface elements. A device for predicting the occurrence of a boundary defect in an injection material, comprising: a device for predicting that no defect will occur.

According to this apparatus, it is not necessary to predict the occurrence of a defect by an empirical rule from the distribution of pressure, velocity and temperature obtained from the filling simulation as in the conventional case, and the occurrence of a boundary defect can be directly calculated from the calculation result. You will be able to predict easily and quantitatively.

This makes it easy to reset the initial temperature condition and the injection speed so that no boundary defect occurs, and
For example, it will be possible to reduce the thickness of aluminum die cast parts and shorten the time from mold design to part manufacture.

According to a third aspect of the present invention, there is provided a method of predicting a boundary defect that occurs when a material is injected into a mold to form a desired shape, and adjacent portions of surface elements of the material injected from the mold are adjacent to each other. Then, the relative velocity RV of the injection material in the adjacent portion is obtained, the relative velocity RV is raised to the power a to obtain the pressure bonding parameter CP indicating the degree of pressure bonding between the surface elements, and the solid phase ratio FS between the surface elements is calculated. To the b-th power to obtain a solidification parameter SP indicating the degree of solidification of the injection material, and a boundary defect prediction parameter DP is obtained from the product of the pressure bonding parameter CP and the solidification parameter SP. A value is compared with a reference value, and if the boundary defect prediction parameter DP is larger than the reference value, it is predicted that a boundary will occur in the adjacent portion between the surface elements. On the other hand, if the boundary defect prediction parameter DP is smaller than the reference value, it is predicted that a boundary defect will not occur in the adjacent portions of the surface elements, which is a method of predicting the occurrence of a boundary defect in an injection material. .

According to a fourth aspect of the present invention, there is provided a boundary defect occurrence predicting device for an injection material, which predicts a boundary defect that occurs when the injection material is poured into a mold to form a desired shape. Means for determining the adjacent portions of the surface elements of the injection material, means for determining the relative velocity RV of the injection material in the adjacent portions, and crimping parameters indicating the degree of crimping of the surface elements by raising the relative velocity RV to the power a. C
Means for obtaining P, means for obtaining the solidification parameter SP indicating the degree of progress of solidification of the injection material by raising the sum of the solid fractions FS of the surface elements to the power of b, and the pressure bonding parameter CP
And a means for obtaining the boundary defect prediction parameter DP from the product of the solidification parameter SP and the value of the boundary defect prediction parameter DP with a reference value, and if the boundary defect prediction parameter DP is larger than the reference value, While predicting that a boundary will occur in the adjacent parts of the surface elements, if the boundary defect prediction parameter DP is smaller than the reference value, means for predicting that no boundary defect will occur in the adjacent parts of the surface elements. It is a device for predicting the occurrence of a boundary defect in an injection material having the above.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for predicting the occurrence of a boundary defect according to the present invention will be described on the assumption that the method is applied to the manufacture of aluminum die casting parts for automobiles.

First, as a result of examining the generation principle of the boundary defect by experiments and empirical rules, the boundary defect may occur when the injection materials whose temperatures have lowered and solidified proceed to collide with each other and are not sufficiently welded. Was found to be high.

Therefore, in order to quantitatively evaluate the occurrence of boundary defects, it was considered that the occurrence of boundary defects occurred when the following three conditions were met.

These three conditions mean that the calculated surface elements are adjacent to each other.

The solidification at the confluence is progressing.

The relative velocity of the surface elements is small in the approaching direction.

When any one of these three conditions is satisfied, the possibility of occurrence of a boundary defect comes out. Of course, when all three conditions are met, a boundary defect will occur.

Boundary defect prediction parameters representing these three conditions are calculated based on the numerical values obtained from the filling simulation.

The surface element, which is one of the boundary defect prediction parameters, is an element whose filling factor F obtained as a result of calculation of the filling process is 0 <F ≦ 1 and F = 0 (empty element). ) Is in contact with, and corresponds to the surface of the fluid (injection material).

Next, the procedure for predicting the occurrence of boundary defects by the method of the present invention will be described with reference to FIG.

First, in order to specify the collision portion of the injection material coming from different directions which is the cause of the boundary defect, the portion where the surface elements are adjacent to each other is extracted by a logical operation.

It should be noted that this can be calculated by a commonly used known method depending on the shape of the article to be ejected, the injection speed (gate speed) of the material at the time of injection, the physical properties of the material and the direction of gravity.

Next, in order to evaluate the strength of crimping of the injection material, the relative velocity RV of the injection material in the adjacent portion is evaluated.
Ask for.

The relative velocity RV is obtained by the following calculation formula.

When the adjacent direction is the + X direction, RV = U
(I) -U (j) When the adjacent direction is the -X direction, RV = U (j) -U
(I) When the adjacent direction is the + Y direction, RV = V (i) -V
(J) When the adjacent direction is the -Y direction, RV = V (j) -V
(I) When the adjacent direction is the + Z direction, RV = W (i) −W
(J) When the adjacent direction is the -Z direction, RV = W (j) -W
(I) In the above equation, the + direction means that the injection material is approaching, and U, V, and W mean the element center velocities in the x, y, and z directions.

That is, U (i) is the element center velocity of the relevant element in the X direction, and U (j) is the element center velocity of the adjacent element in the X direction. V (i), V (j), W
Similarly, (i) and W (j) represent the element center velocities in the Y and Z directions, respectively.

In the present invention, the mesh used for analysis is FD
M (Finite Difference Metho)
Since d), the relative speed in the x, y, z directions of a cube or a rectangular parallelepiped can be obtained. In the calculation, the relative speed in the direction connecting the element centers depends on which direction the adjacent elements are. Is selected and used for calculation, and the direction in which the injection material approaches from the adjacent element is positive.

Next, the obtained relative velocity RV is raised to the power a, and a crimping parameter C indicating the degree of crimping of the surface elements is obtained.
Find P. That is, CP = RV ^a . In addition, this a
The optimum value of is determined by experiment.

Further, the sum of the solid fractions FS of the surface elements is raised to the power of b to obtain a solidification parameter SP indicating the degree of solidification of the injection material. This solidification parameter SP represents the degree to which the temperature of the injected material has dropped at the collision portion and solidification has progressed. The solidification parameter SP is calculated by the following equation.

[0035] When an element fraction solid and FS, coagulation parameters SP = (FS (i) + FS (j)) b The optimum value of the b is determined by experimentation.

The crimping parameter CP calculated by the above procedure is multiplied by the solidification parameter SP (D
P = CP × SP) A boundary defect prediction parameter DP is obtained. If there are multiple adjacent surface cells, the maximum value is used.

As described above, the boundary defect prediction parameter DP is calculated by the product of the pressure bonding parameter CP and the solidification parameter SP when the molten metal 1 and the molten metal 2 contact each other from different directions as shown in FIG. This is because the solidified state at the time of contact of the contact portion and the strength of pressure bonding have a causal relationship as shown in the same table. That is, the greater the degree of pressure bonding, the greater the degree of fusion, and the smaller the solidified state, the greater the degree of fusion.

This is because the cause of defects due to the shape and material of the article to be ejected is not influenced by how the solidification state and the relative velocity are concerned, but by either one of them, there is a case where the influence is greatly influenced. Means that. Therefore, it is more desirable to set a and b as the correction values by experiments as in the present embodiment.

Next, the obtained boundary defect prediction parameter DP is compared with a reference value to determine the boundary defect prediction parameter DP.
Is compared with a reference value (critical value), and if the boundary defect prediction parameter DP is larger than the reference value, it is predicted that a boundary will occur in the adjacent portion between the surface elements, and the boundary defect prediction parameter DP is If it is smaller than the reference value, it is predicted that no boundary will occur in the adjacent portions of the surface elements.

As described above, according to the present invention, it is not necessary to predict the occurrence of defects by the empirical rule from the pressure, velocity, and temperature distributions obtained from the filling simulation, as in the conventional case, and the calculation results directly determine the boundary. The occurrence of defects can be predicted easily and quantitatively.

This prediction is calculated by a device as shown in FIG.

This will be explained because it is necessary to make preparations for predicting this defect before operating this device.

First, an analytical model to be stored in the analytical model database 10 is created. In other words, using a mainframe terminal or workstation 12 (not shown),
The shape data of the analysis object is created using AD software. The analysis database 10 also stores data about other articles.

Next, the created shape data is
The data is transferred to the workstation 12 for heat filling analysis connected to N, the shape data is converted into analysis element data, and necessary initial conditions, boundary conditions, and analysis control data are input from the keyboard 14.

By the above processing, the preparation for predicting the defect is completed.

In FIG. 3, the boundary defect occurrence candidate position estimation unit 16 uses the data of the transmission case stored in the analysis result database 18 based on, for example, the conventional analysis method, and the positions where the surface elements are in contact with each other. Is selected as a boundary defect occurrence candidate position.

The boundary defect occurrence estimation unit 20 performs a crimping determination and a solidification determination from the boundary defect occurrence candidate position estimated by the boundary defect occurrence candidate position estimation unit 16 and calculates a parameter.

Defect occurrence prediction result display data creation unit 22
Displays a three-dimensional image or the like that makes it easy to determine a portion where a boundary defect is likely to occur from the calculated parameters and shape data in order to evaluate and judge the occurrence result of the boundary defect and study a solution in production technology. Data for use.

The display 24 displays an image based on this display data.

The prediction of the occurrence of boundary defects is performed as follows.

First, the boundary defect occurrence candidate position estimation unit 16
Retrieves the data related to the transmission data by the conventional method from the analysis model database 10,
A boundary defect occurrence candidate position is estimated. By this estimation,
The position where a boundary defect is likely to occur is estimated. In the present embodiment, in order to ensure the accuracy of this result, the boundary defect occurrence estimation unit 20 performs the boundary defect prediction calculation.

Specifically, velocity distribution data is extracted from the analysis result database 18 and is applied to the above calculation formula to first obtain the crimping parameter CP. Then, the solid fraction distribution data is extracted and the coagulation parameter SP is obtained. The boundary defect occurrence candidate position estimation unit 16 multiplies each of these and predicts a boundary defect occurrence from the result.

In this embodiment, the parameter, that is, DP, is set to 0.1 as a reference, as shown in FIG.
If is smaller than this, it is assumed that no boundary defect will occur. In addition, the reference value of the parameter here is calculated | required from the experiment which is explained in full detail below, for example. This is not limited to this experiment, and may be any experiment as long as it is an experiment with an apparatus that can obtain the pressure bonding speed and the solid phase ratio.

Based on the above results, it becomes possible to more accurately estimate the occurrence position of the boundary defect.

After the above processing, analytical element data (three-dimensionally divided mesh shape of the analytical article) is extracted from the analytical model database 10 and which part thereof becomes the position where the boundary defect occurs is determined. Specific data processing is performed by the defect occurrence prediction result display data creation unit 22 and displayed on the display 24.

In the present embodiment, in order to facilitate the determination, the coefficients a and b are obtained by trial calculation and examination of parameters based on the experimental results as shown in FIG.

Next, how the optimum value of the variable a used for obtaining the crimping parameter CP and the optimum value of the variable b used for obtaining the solidification parameter SP are obtained will be described.

This experiment was carried out in order to examine the relationship between the presence / absence of the occurrence of a boundary defect and the parameters by preparing an experimental apparatus in which the flows of molten aluminum having different speeds and solidified states were made to collide. The experimental setup used is shown in FIG.

As shown in the drawing, the experimental apparatus is provided with one sprue and two gates for injecting the injection material. The cavity formed by the upper mold and the lower mold has a rectangular parallelepiped shape.

In the experiment, molten aluminum was poured from the sprue,
It was performed by solidifying molten aluminum into the cavity from two gates, and observing the appearance of the test piece to determine the presence or absence of a boundary defect. The solidification state of molten aluminum is represented by the solid phase ratio estimated proportionally from the molten aluminum temperature measured at the gate position with the liquidus temperature 627 ° C. as the solid phase ratio of 0 and the solidus temperature 520 ° C. as the solid phase ratio of 1. did. The table below shows the experimental conditions and the occurrence of boundary defects.

Flow 1 Flow 2 Bonding speed Temperature Solid fraction Solid temperature Solid fraction Boundary defect experiment NO (cm / s) (° C) (° C) 1 100 600 0.25 600 0.25 None 2 100 580 0.44 580 0.44 None 3 10 580 0.44 580 0.44 Yes 4 100 550 0.72 550 0.72 Yes 5 300 550 0.72 550 0.72 None None Shown in FIGS. 5 (a) and 5 (b) The photograph shows the above experiment N
It is a photograph which shows the metal structure of the test piece respectively obtained by O1 and NO3.

Next, the optimum values of the variables a and b are obtained from the experimental results thus obtained.

In FIG. 6, variable a and variable b are changed to
It is the figure which plotted the value of the boundary defect prediction parameter DP obtained from each variable a and variable b for every experiment NO.

As is apparent from this figure, when the values of the selected variables are a = 0.5 and b = 1, it is possible to obtain a graph with a large difference in the parameter values as shown in the figure. You can
When the value of the boundary defect prediction parameter DP is 0.1, that is, when the reference value (critical value) is 0.1, the experimental result and the boundary defect prediction result are extremely consistent.

Therefore, the variable a thus obtained
= 0.5 and the variable b = 1 is used to perform the calculation of the method of the present invention, it is possible to reliably predict the occurrence of a boundary defect, which allows, for example, thinning of aluminum die cast parts,
It becomes possible to shorten the time from the mold design to the part manufacturing.

FIGS. 7 and 8 show the inconvenient parts analyzed in the injection molding of the transmission case by this method. With this method, in the transmission case shown in FIG. 7, it is possible to predict the occurrence of defects in the circles shown in FIG. 8 (the occurrence portions are displayed in white).

[0067]

According to the method and apparatus for predicting the occurrence of boundary defects of the present invention according to claims 1 to 4, the occurrence of boundary defects in the step of casting an injection material from a mold to produce a product can be easily and quantitatively determined. Will be able to predict.

[Brief description of drawings]

FIG. 1 is a diagram showing a procedure for predicting the occurrence of a boundary defect by the method of the present invention.

FIG. 2 is a diagram for explaining calculation of a boundary defect prediction parameter.

FIG. 3 is a schematic configuration diagram of an apparatus for carrying out the method of the present invention.

FIG. 4 is a schematic configuration diagram of a mold used in an experiment.

5 (a) and 5 (b) are photographs showing a metallographic structure of a test piece obtained as a result of the experiment.

FIG. 6 is a diagram for explaining a process of calculating variables a and b.

FIG. 7 is an external view of a transmission case to which an analysis by this method is applied.

FIG. 8 is a state diagram when an analysis is performed by this method.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masa Yamabe 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd.

Claims (4)

[Claims] 1. A method of predicting a boundary defect that occurs when an injection material is cast into a mold to form a desired shape, wherein adjacent parts of surface elements of the injection material poured from the mold are determined, The relative velocity RV of the injection material is obtained, and the relative velocity RV is used as a pressure bonding parameter CP indicating the degree of pressure bonding of the surface elements, and the sum of the solid fractions FS of the surface elements is defined as the progress of solidification of the injection material. The boundary defect prediction parameter DP is obtained from the product of the pressure bonding parameter CP and the solidification parameter SP, and the value of the boundary defect prediction parameter DP is compared with a reference value. If it is larger than the value, it is predicted that a boundary will occur in the adjacent portion between the surface elements, while the boundary defect prediction parameter DP is It is smaller than the serial reference value, generating prediction method of a boundary defect of the injection material in the adjacent portion between the surface element and wherein the predicting a boundary defect does not occur. 2. A boundary defect occurrence predicting device for an injection material, which predicts a boundary defect that occurs when an injection material is poured into a mold to form a desired shape. Means for determining the adjacent portion, means for determining the relative velocity RV of the injection material in the adjacent portion, means for determining the relative velocity RV as a crimping parameter CP indicating the degree of crimping of the surface elements, and between the surface elements. Means for obtaining the sum of the solid fractions FS as a solidification parameter SP indicating the degree of solidification of the injection material; means for obtaining a boundary defect prediction parameter DP from the product of the pressure bonding parameter CP and the solidification parameter SP; The value of the prediction parameter DP is compared with a reference value, and if the boundary defect prediction parameter DP is larger than the reference value, the table While predicting that a boundary will occur in the adjacent portion of the surface elements, the boundary defect prediction parameter D
A device for predicting the occurrence of a boundary defect in an injection material, comprising: means for predicting that a boundary defect will not occur in the adjacent portions of the surface elements if P is smaller than the reference value. 3. A method of predicting a boundary defect that occurs when an injection material is cast into a mold to form a desired shape, wherein adjacent parts of surface elements of the injection material poured from the mold are determined, The relative velocity RV of the injection material is obtained, the relative velocity RV is raised to the power a to obtain the pressure bonding parameter CP indicating the degree of pressure bonding between the surface elements, and the sum of the solid fractions FS between the surface elements is raised to the power b. A solidification parameter SP indicating the degree of solidification of the injection material is obtained, a boundary defect prediction parameter DP is obtained from the product of the pressure bonding parameter CP and the solidification parameter SP, and the value of the boundary defect prediction parameter DP is compared with a reference value. If the boundary defect prediction parameter DP is larger than the reference value, it is predicted that a boundary will occur in the adjacent portion of the surface elements, while the boundary defect If measurement parameter DP is smaller than the reference value, generating prediction method of a boundary defect of the injection material in the adjacent portion between the surface element and wherein the predicting a boundary defect does not occur. 4. A boundary defect occurrence predicting device for an injection material, which predicts a boundary defect that occurs when an injection material is poured into a mold to form a desired shape, wherein the surface elements of the injection material are poured from the mold. A means for obtaining an adjacent portion, a means for obtaining a relative speed RV of the injection material in the adjacent portion, a means for obtaining a crimping parameter CP indicating the degree of crimping between the surface elements by raising the relative speed RV to the power a, Means for obtaining the solidification parameter SP indicating the progress of solidification of the injection material by raising the sum of the solid fractions FS of the surface elements to the power of b, and the boundary defect prediction parameter DP from the product of the pressure bonding parameter CP and the solidification parameter SP. And a value of the boundary defect prediction parameter DP is compared with a reference value, and if the boundary defect prediction parameter DP is larger than the reference value. , While predicting that a boundary will occur in the adjacent portion of the surface elements, the boundary defect prediction parameter D
A device for predicting the occurrence of a boundary defect in an injection material, comprising: means for predicting that a boundary defect will not occur in the adjacent portions of the surface elements if P is smaller than the reference value.