JP3574272B2 - Method and apparatus for predicting occurrence of boundary defect in injection material - Google Patents

Description

なお、図５（ａ），（ｂ）に示す写真は、上記の実験ＮＯ１とＮＯ３によってそれぞれ得られた試験片の金属組織を示す写真である。
【００６２】
つぎに、このようにして得られた実験結果から変数ａと変数ｂの最適値を求める。
【００６３】
図６は、変数ａと変数ｂとを変化させて、それぞれの変数ａと変数ｂから得られる境界欠陥予測パラメータＤＰの値を実験ＮＯ毎にプロットした図である。
【００６４】
この図を見れば明らなように、選択した変数の値がａ＝０．５，ｂ＝１である場合に、図のようなパラメータの値の差が大きなグラフを得ることができ、境界欠陥予測パラメータＤＰの値が０．１、すなわち基準値（臨界値）を０．１とすれば、実験結果と境界欠陥の予測結果が極めて一致することになる。
【００６５】
したがって、このようにして求めた変数ａ＝０．５，変数ｂ＝１を用いて本発明方法の演算を行なえば、境界欠陥の発生を確実に予測することができ、これによって、たとえばアルミダイカスト部品の薄肉化、金型設計から部品製造までの時間を短縮することができるようになる。
【００６６】
本手法により、トランスミッションケースの射出成形に当たり、不都合部分の解析を行なったものを図７及び図８に示す。本手法により図７に示すトランスミッションケースにあっては、図８に示す丸印部に欠陥の発生が予測できる（発生部分は白く表示させている）。
【００６７】
【発明の効果】
請求項１乃至請求項４における本発明の境界欠陥の発生予測方法及びその装置によれば、型から射出材料を流し込んで製品を造る工程の境界欠陥の発生を、簡単かつ定量的に予測することができるようになる。
【図面の簡単な説明】
【図１】本発明方法により境界欠陥の発生を予測する手順を示す図である。
【図２】境界欠陥予測パラメータの算出を説明するための図である。
【図３】本発明方法を実施する装置の概略構成図である。
【図４】実験に用いた金型の概略構成図である。
【図５】（ａ），（ｂ）は、実験の結果得られた試験片の金属組織を示す写真である。
【図６】変数ａ，ｂの算出過程の説明に供する図である。
【図７】本手法による解析を適用したトランスミッションケースの外観図である。
【図８】本手法によって解析を行なった際の状態図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for predicting boundary defects of an injection material generated in an injection molding process, for example, a boundary defect in a molten aluminum material.
[0002]
[Prior art]
For example, in the injection molding process such as aluminum die casting, the flow condition during injection and filling has a great effect on the quality. The application of a filling simulation that takes into account both analyzes is under study.
[0003]
The results of this filling simulation are the filling process and the changes over time in temperature, speed, and pressure.Therefore, injection conditions and mold design changes for quality improvement, etc. We are considering based on.
[0004]
[Problems to be solved by the invention]
However, in such conventional filling simulations, the injection process and changes in the mold design are examined based on empirical rules based on the filling process obtained as a result of calculation and the values of temperature, speed, and pressure over time. However, it has been very difficult to predict even the boundary defects generated in the injection molding process.
[0005]
For example, in order to predict boundary defects from the results of this simulation, it is necessary to create a filling process diagram and a vector diagram, and to visually judge from these diagrams, which requires much time and skill. It costs. In particular, it is difficult to predict a complicated three-dimensional structure.
[0006]
The present invention has been made in order to solve the above-mentioned conventional problems. For example, it is possible to easily remove a defect such as a molten metal boundary in an aluminum die-cast, which occurs at a junction of fluids having different solidification states and different velocities. It is another object of the present invention to provide a method and apparatus for predicting the occurrence of boundary defects in an injection material that can be quantitatively predicted.
[0007]
[Means for Solving the Problems]
The present invention for achieving the above object has the following configuration.
[0008]
The invention according to claim 1 is a method for predicting a boundary defect that occurs when an injection material is poured into a mold and has a desired shape, and determines adjacent portions between surface elements of the injection material poured from the mold. The relative speed RV of the injection material in the adjacent portion is obtained, the relative speed RV is used as a compression parameter CP indicating the degree of compression of the surface elements, and the sum of the solid fractions FS of the surface elements is used as the solidification of the injection material. The boundary defect prediction parameter DP is obtained from the product of the crimping parameter CP and the solidification parameter SP, and the value of the boundary defect prediction parameter DP is compared with a reference value. if DP is greater than the reference value, while predicting a boundary defects occur in the adjacent portion between the surface elements, the boundary defect prediction parameters If data 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.
[0009]
According to such a method, unlike the conventional method, it is not necessary to predict the occurrence of a defect by an empirical rule from the pressure, velocity, and temperature distributions obtained from the filling simulation, and the generation of the boundary defect can be simplified directly from the calculation result. And it can predict quantitatively.
[0010]
This facilitates resetting of the initial temperature condition and the injection speed such that boundary defects do not occur, and also enables, for example, a reduction in the thickness of an aluminum die-cast component and a reduction in the time from mold design to component production. Become.
[0011]
The invention according to claim 2 is an apparatus for predicting the occurrence of a boundary defect of an injection material, which predicts a boundary defect generated when the injection material is poured into a mold and has a desired shape. Means for determining an adjacent portion between the surface elements, means for determining a relative speed RV of the injection material in the adjacent portion, means for determining the relative speed RV as a pressing parameter CP indicating a degree of pressing of the surface elements, Means for determining the sum of the solid fractions FS of the surface elements as a solidification parameter SP indicating the degree of progress of solidification of the injection material; means for determining a boundary defect prediction parameter DP from a product of the compression parameter CP and the solidification parameter SP; Comparing 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, The one boundary defects adjacent portions of the surface elements to each other is expected to occur, if the boundary defect prediction parameter DP is smaller than the reference value, means for predicting the in adjacent portions between the surface elements that are not boundaries defect occurs A device for predicting the occurrence of boundary defects in an injection material, comprising:
[0012]
This device eliminates the need for predicting the occurrence of defects by empirical rules from the pressure, velocity, and temperature distributions obtained from the filling simulation, as in the past, and enables simple and quantitative determination of boundary defects directly from the calculation results. Can be predicted.
[0013]
This facilitates resetting of the initial temperature condition and the injection speed such that boundary defects do not occur, and also enables, for example, a reduction in the thickness of an aluminum die-cast component and a reduction in the time from mold design to component production. Become.
[0014]
The invention according to claim 3 is a method for predicting a boundary defect that occurs when an injection material is poured into a mold and has a desired shape, and calculates adjacent portions between surface elements of the injection material poured from the mold, The relative speed RV of the injection material in the adjacent portion is determined, the relative speed RV is raised to the power a, and a pressing parameter CP indicating the degree of pressing of the surface elements is determined, and the sum of the solid fractions FS of the surface elements is calculated. raised to the power b to obtain a solidification parameter SP indicating the degree of solidification of the injection material, a boundary defect prediction parameter DP is obtained from a product of the compression parameter CP and the solidification parameter SP, and the value of the boundary defect prediction parameter DP is used as a reference. compared with the values, the if boundary defect prediction parameter DP is greater than the reference value, while predicting a boundary defects occur in the adjacent portion between the surface elements, before If boundary defect prediction 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.
[0015]
The invention according to claim 4 is a device for predicting a boundary defect of an injection material, which predicts a boundary defect generated when the injection material is poured into a mold and has a desired shape, wherein the injection material is injected from the mold. Means for determining the adjacent portion between the surface elements, means for determining the relative speed RV of the injection material in the adjacent portion, and determining the compression parameter CP indicating the degree of compression between the surface elements by raising the relative speed RV to the power a. Means for calculating a 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 a boundary based on the product of the compression parameter CP and the solidification parameter SP Means for determining the defect prediction parameter DP, and comparing the value of the boundary defect prediction parameter DP with a reference value, so that the boundary defect prediction parameter DP is larger than the reference value. In Kere, while predicting a boundary defect on the adjacent portion between the surface element occurs, if the boundary defect prediction parameter DP is smaller than the reference value, boundary defects in adjacent portions between said surface element if not occur Prediction means for predicting the occurrence of boundary defects in the injection material.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the method for predicting the occurrence of boundary defects according to the present invention will be described on the assumption that the method is applied to the production of aluminum die-cast parts for automobiles.
[0017]
First, as a result of examining the principle of generation of boundary defects by experiments and empirical rules, it was found that boundary defects are likely to occur when injection materials that solidified due to a decrease in temperature collide with each other and are not sufficiently welded. Was found.
[0018]
Therefore, in order to quantitatively evaluate the generation of the boundary defect, it was considered that the generation of the boundary defect occurs when the following three conditions are satisfied.
[0019]
These three conditions are
(1) The calculated surface elements are adjacent.
[0020]
{Circle around (2)} The solidification of the confluence is progressing.
[0021]
(3) The relative speed of the surface element is small in the approaching direction.
[0022]
If any one of these three conditions is satisfied, there is a possibility that a boundary defect will occur. If all three conditions are met, a boundary defect will occur.
[0023]
The boundary defect prediction parameters representing these three conditions are calculated based on numerical values obtained from the filling simulation.
[0024]
The surface element which is one of the boundary defect prediction parameters is in contact with an element (empty element) where the filling factor F of each element obtained as a result of the filling process is 0 <F ≦ 1 and F = 0. And corresponds to the surface of the fluid (injection material).
[0025]
Next, a procedure for predicting the occurrence of a boundary defect by the method of the present invention will be described with reference to FIG.
[0026]
First, in order to specify the collision portion of the injection material coming from different directions, which is the cause of the boundary defect, a portion where the surface elements are adjacent to each other is extracted by a logical operation.
[0027]
This can be calculated by a known method that is generally used, based on the shape of the article to be injected, the injection speed (gate speed) of the material at the time of injection, the physical properties of the material, and the direction of gravity.
[0028]
Next, in order to evaluate the strength of the compression of the injection material, the relative speed RV of the injection material in the adjacent portion is obtained.
[0029]
This relative speed RV is obtained by the following formula.
[0030]
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 comes closer,
U, V, and W mean the element center velocities in the x, y, and z directions.
[0031]
That is, U (i) is the element center speed of the element in the X direction, and U (j) is the element center speed of the adjacent element in the X direction. V (i), V (j), W (i) and W (j) similarly represent the element center velocities in the respective Y and Z directions.
[0032]
In the present invention, the mesh used for the analysis is an FDM (Finite Difference Method), so that the relative velocity in the x, y, and z directions of a cube or a rectangular parallelepiped can be obtained. Depending on the direction, the relative speed in the direction connecting the element centers is selected and used in the calculation, and the direction in which the injection material approaches from the adjacent element is defined as positive.
[0033]
Next, the determined relative speed RV is raised to the power a, and a pressing parameter CP indicating the degree of pressing of the surface elements is determined. That is, the CP = RV ^a. Note that the optimum value of a is obtained by an experiment.
[0034]
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 progress of solidification of the injection material. The solidification parameter SP indicates the degree of solidification progressed by the temperature of the injection material decreasing at the collision portion. This solidification parameter SP is obtained by the following equation.
[0035]
If the element solid fraction is FS,
Coagulation parameter SP = (FS (i) + FS (j)) ^b
Note that the optimum value of b is obtained by an experiment.
[0036]
The crimping parameter CP calculated by the above procedure is multiplied by the solidification parameter SP to obtain a boundary defect prediction parameter DP (DP = CP × SP). When there are a plurality of adjacent surface cells, the maximum value is used.
[0037]
As described above, the reason why the boundary defect prediction parameter DP is calculated by the product of the pressure bonding parameter CP and the solidification parameter SP is that when the molten metal 1 and the molten metal 2 come into contact from different directions as shown in FIG. This is because the solidification state at the time of contact and the pressure bonding strength have a causal relationship as shown in the same table. That is, if the strength of the pressure bonding is large, the degree of fusion is large, and if the solidification state is small, the degree of fusion is large.
[0038]
This means that the factors that cause defects due to the shape and material of the article to be injected are not affected by the solidification state and the relative speed, but may be significantly influenced by either one. I do. Therefore, it is more desirable to set a and b as correction values by experiments and the like as in the present embodiment.
[0039]
Next, the obtained boundary defect prediction parameter DP is compared with a reference value, the value of 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 defect will occur in an adjacent portion between the surface elements, and if the boundary defect prediction parameter DP is smaller than the reference value, it is predicted that no boundary defect will occur in an adjacent portion between the surface elements.
[0040]
As described above, according to the present invention, it is not necessary to predict the occurrence of a defect by an empirical rule based on the distribution of pressure, velocity, and temperature obtained from a filling simulation as in the related art. Can be easily and quantitatively predicted.
[0041]
This prediction is calculated by a device as shown in FIG.
[0042]
Before operating this device, it is necessary to prepare for the prediction of this defect, which will be described.
[0043]
First, an analysis model to be stored in the analysis model database 10 is created. That is, the shape data of the analysis target is created using CAD software using a mainframe terminal or the workstation 12 (not shown). The analysis database 10 also stores data on other articles.
[0044]
Next, the created shape data is transferred to the work station 12 for heat filling analysis connected to the LAN, and the shape data is converted into analysis element data, and necessary initial conditions, boundary conditions, analysis control Data is input from the keyboard 14.
[0045]
With the above processing, preparation for predicting a defect is completed.
[0046]
In FIG. 3, a boundary defect occurrence candidate position estimating unit 16 uses the data of a transmission case based on, for example, a conventional analysis method stored in the analysis result database 18 to determine the position where the surface elements are in contact with each other. It is selected as an occurrence candidate position.
[0047]
The boundary defect occurrence estimating unit 20 performs a compression determination and a solidification determination based on the boundary defect occurrence candidate position estimated by the boundary defect occurrence candidate position estimating unit 16 and calculates parameters.
[0048]
The defect occurrence prediction result display data creation unit 22 evaluates and determines the boundary defect occurrence prediction result to determine a part where a boundary defect is likely to occur from the calculated parameters and the shape data in order to consider a solution in production technology. This is for creating display data such as a three-dimensional image that can be easily displayed.
[0049]
The display 24 displays an image based on the display data.
[0050]
The prediction of the occurrence of the boundary defect is performed as follows.
[0051]
First, the boundary defect occurrence candidate position estimating unit 16 extracts data on transmission data by a conventional method from the analysis model database 10 and estimates a boundary defect occurrence candidate position. By this estimation, a position where a boundary defect is likely to occur is estimated. In the present embodiment, in order to ensure the accuracy of the result, the boundary defect prediction calculation is performed by the boundary defect occurrence estimating unit 20.
[0052]
Specifically, the velocity distribution data is extracted from the analysis result database 18 and applied to the above-mentioned calculation formula to first determine the crimping parameter CP. Next, solid phase fraction distribution data is extracted, and a solidification parameter SP is obtained. The boundary defect occurrence candidate position estimating section 16 multiplies these by each and performs a boundary defect occurrence prediction from the result.
[0053]
In the present embodiment, the parameter, that is, the DP, is set to 0.1 as shown in FIG. 6, and if the DP is smaller than this, no boundary defect occurs. Note that the reference values of the parameters here are obtained, for example, from experiments described in detail below. This is not limited to this experiment, and any experiment may be used as long as the experiment uses a device that requires the pressure bonding rate and the solid fraction.
[0054]
Based on the above result, it is possible to more accurately estimate the position where the boundary defect occurs.
[0055]
After the above-described processing, the analysis element data (the three-dimensionally divided shape of the analysis article) is extracted from the analysis model database 10, and it is specifically determined which part becomes the occurrence position of the boundary defect. The data processing shown is performed by the defect occurrence prediction result display data creation unit 22 and displayed on the display 24.
[0056]
In this embodiment, in order to facilitate the determination, the coefficients a and b are obtained by trial calculation and study of parameters based on the experimental results as shown in FIG.
[0057]
Next, how the optimum value of the variable a used when obtaining the pressure bonding parameter CP and the optimum value of the variable b used when obtaining the solidification parameter SP will be described.
[0058]
This experiment was conducted to create an experimental apparatus for colliding molten aluminum flows having different speeds and solidification states, and to examine the relationship between the presence / absence of boundary defects and the parameters. The experimental apparatus used is shown in FIG.
[0059]
As shown in the drawing, this experimental apparatus is formed with one sprue and two gates for injecting an injection material. The cavity formed by the upper mold and the lower mold has a rectangular parallelepiped shape.
[0060]
The experiment was performed by pouring molten aluminum from a sprue and solidifying the molten aluminum into the cavity from two gates, and observing the appearance of the test piece to determine the presence or absence of boundary defects. The solidification state of the molten aluminum is represented by the solidus fraction estimated in proportion from the molten aluminum temperature measured at the gate position with the liquidus temperature of 627 ° C as the solid fraction of 0 and the solidus temperature of 520 ° C as the solid fraction of 1. did. The experimental conditions and the presence or absence of boundary defects are shown in the table below.
[0061]

The photographs shown in FIGS. 5A and 5B are photographs showing the metal structures of the test pieces obtained by the above-described experiments NO1 and NO3, respectively.
[0062]
Next, the optimum values of the variables a and b are obtained from the experimental results obtained as described above.
[0063]
FIG. 6 is a diagram in which the variable a and the variable b are changed, and the value of the boundary defect prediction parameter DP obtained from each of the variables a and b is plotted for each experiment NO.
[0064]
As is clear from this figure, when the values of the selected variables are a = 0.5 and b = 1, it is possible to obtain a graph having a large difference in parameter values as shown in FIG. Assuming that the value of the defect prediction parameter DP is 0.1, that is, the reference value (critical value) is 0.1, the experimental result and the prediction result of the boundary defect are very similar.
[0065]
Therefore, if the calculation of the method of the present invention is performed using the variables a = 0.5 and b = 1 thus obtained, it is possible to reliably predict the occurrence of a boundary defect. It becomes possible to shorten the time from the thinning of the parts and the mold design to the production of the parts.
[0066]
FIGS. 7 and 8 show the results of analyzing the disadvantageous parts in the injection molding of the transmission case by the present method. According to this method, in the transmission case shown in FIG. 7, the occurrence of a defect can be predicted at the circled portion shown in FIG. 8 (the occurrence portion is displayed in white).
[0067]
【The invention's effect】
According to the method and apparatus for predicting the occurrence of boundary defects of the present invention according to claims 1 to 4, it is possible to easily and quantitatively predict the generation of boundary defects in a process of manufacturing a product by pouring an injection material from a mold. Will be able to
[Brief description of the drawings]
FIG. 1 is a diagram showing a procedure for predicting the occurrence of a boundary defect according to 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 performing the method of the present invention.
FIG. 4 is a schematic configuration diagram of a mold used in an experiment.
FIGS. 5A and 5B are photographs showing a metal structure of a test piece obtained as a result of an experiment.
FIG. 6 is a diagram provided to explain a process of calculating variables a and b.
FIG. 7 is an external view of a transmission case to which analysis according to the present technique is applied.
FIG. 8 is a state diagram when analysis is performed by the present method.

Claims (4)

A method for predicting a boundary defect that occurs when an injection material is poured into a mold and has a desired shape,
Find adjacent parts of the surface elements of the injection material poured from the mold,
The relative velocity RV of the injection material in the adjacent portion is obtained,
The relative speed RV as a crimping parameter CP indicating the degree of crimping of the surface elements,
The sum of the solid fraction FS of the surface elements as a solidification parameter SP indicating the progress of solidification of the injection material,
A boundary defect prediction parameter DP is obtained from a product of the pressing parameter CP and the solidification parameter SP,
Comparing the value of the boundary defect prediction parameter DP with a reference value,
If the boundary defect prediction parameter DP is larger than the reference value, it is predicted that a boundary defect will occur in an adjacent portion between the surface elements. On the other hand, if the boundary defect prediction parameter DP is smaller than the reference value, the surface element A method for predicting occurrence of a boundary defect in an injection material, wherein the method predicts that a boundary defect does not occur in an adjacent portion between the two. A boundary defect occurrence prediction device for the injection material, which predicts a boundary defect generated when the injection material is poured into a mold and has a desired shape,
Means for determining adjacent parts of the surface elements of the injection material poured from the mold,
Means for determining a relative velocity RV of the injection material in the adjacent portion;
Means for determining the relative speed RV as a crimping parameter CP indicating a degree of crimping of the surface elements,
Means for obtaining the sum of the solid fractions FS of the surface elements as a solidification parameter SP indicating the degree of progress of solidification of the injection material;
Means for calculating a boundary defect prediction parameter DP from a product of the pressure bonding parameter CP and the solidification parameter SP;
The 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, it is predicted that a boundary defect will occur in an adjacent portion between the surface elements, while the boundary defect is predicted. Means for predicting that a boundary defect does not occur in an adjacent portion between the surface elements if the defect prediction parameter DP is smaller than the reference value. A method for predicting a boundary defect that occurs when an injection material is poured into a mold and has a desired shape,
Find adjacent parts of the surface elements of the injection material poured from the mold,
The relative velocity RV of the injection material in the adjacent portion is obtained,
The relative speed RV is raised to the power a to obtain a pressing parameter CP indicating a degree of pressing of the surface elements,
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,
A boundary defect prediction parameter DP is obtained from a product of the pressing parameter CP and the solidification parameter SP,
Comparing the value of the boundary defect prediction parameter DP with a reference value,
If the boundary defect prediction parameter DP is larger than the reference value, it is predicted that a boundary defect will occur in an adjacent portion between the surface elements. On the other hand, if the boundary defect prediction parameter DP is smaller than the reference value, the surface element A method for predicting occurrence of a boundary defect in an injection material, wherein the method predicts that a boundary defect does not occur in an adjacent portion between the two. A boundary defect occurrence prediction device for the injection material, which predicts a boundary defect generated when the injection material is poured into a mold and has a desired shape,
Means for determining adjacent parts of the surface elements of the injection material poured from the mold,
Means for determining a relative velocity RV of the injection material in the adjacent portion;
Means for raising the relative speed RV to the power a to determine a crimping parameter CP indicating a degree of crimping of the surface elements;
Means for obtaining a 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;
Means for calculating a boundary defect prediction parameter DP from a product of the pressure bonding parameter CP and the solidification parameter SP;
The 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, it is predicted that a boundary defect will occur in an adjacent portion between the surface elements, while the boundary defect is predicted. Means for predicting that a boundary defect does not occur in an adjacent portion between the surface elements if the defect prediction parameter DP is smaller than the reference value.

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