JP2020019032A - Prediction method of casting defect position, defect position prediction device, defect position prediction program and recording medium thereof - Google Patents

Abstract

To provide a prediction method of casting defect position by which consistency between analysis result and actual casting result can be improved, a defect position prediction device, a defect position prediction program and a recording medium thereof.SOLUTION: A casting defect position prediction method, which predicts a defect position of casting in pressure casting in which molten metal is injected under pressure into a casting mold, comprises: a casting mold model creation process; a fluidity analysis process in which state quantity of plural elements is calculated; a gas pressure threshold calculation process in which a threshold of a gas pressure in plural elements is calculated on the basis of fluidity analysis result and defect generation condition to be predicted in castings; and a defect position prediction process in which a defect position at the end time of molten metal filling on the basis of a gas pressure, a flow velocity, and a threshold of gas pressure which have been calculated in the fluidity analysis.SELECTED DRAWING: Figure 4A

Description

  The present disclosure relates to a defect position prediction method, a defect position prediction device, a defect position prediction program, and a recording medium thereof for a casting.

  2. Description of the Related Art Conventionally, in order to reduce defects and the like of a cast product, a defect of a cast product is determined by a casting simulation (for example, see Patent Document 1).

  Patent Literature 1 discloses that a filling cavity close to an actual casting process in consideration of gas entrainment during filling of a molten metal is performed by performing a filling analysis of a molten metal and using the obtained gas information in a solidification analysis in consideration of the information. A method for analyzing a porosity of a metal casting that can be analyzed is disclosed.

JP 2010-131607 A

  By the way, there is a problem that there is a deviation in a defect generation position between a conventional casting simulation analysis result and an actual casting, and the consistency between the analysis result and the actual casting result is low.

  In view of the foregoing, an object of the present disclosure is to provide a defect position prediction method, a defect position prediction device, a defect position prediction program, and a recording medium for the defect position prediction of a casting, which can improve the consistency between the analysis result and the actual casting result. I do.

  In order to solve the above-mentioned problems, a method of predicting a defect position of a casting according to a first technique disclosed herein is a method of predicting a defect position of a casting in pressure casting in which a molten metal is injected into a mold under pressure. A mold model creating step of creating a mold model obtained by dividing the cavity of the mold into a plurality of elements; and, for the mold model, under the same casting conditions as in the pressure casting, from the start of filling of the molten metal to the end of filling. A molten metal flow analysis for each predetermined time step until the molten metal flow analysis step of calculating a state quantity of the plurality of elements including a gas pressure of the plurality of elements and a flow velocity of the molten metal at each time step; A gas pressure threshold value calculating step of calculating a threshold value of the gas pressure in the plurality of elements based on a result of the molten metal flow analysis and a defect occurrence condition to be predicted in the casting. A defect position prediction step of predicting a defect position at the end of filling of the molten metal based on the gas pressure, the flow velocity, and the gas pressure threshold value calculated in the analysis. In the result of the melt flow analysis at an arbitrary time step, a defect precursor generation determination step of determining that a defect precursor has occurred in an element where the gas pressure exceeds the threshold, and the defect precursor has occurred A molten metal inflow determining step of determining whether the molten metal has flowed into the element determined as above, and, when it is determined that the molten metal has flowed into the element, the element and / or an element surrounding the element A movement calculation step of calculating the movement of the defect precursor from the flow velocity of the molten metal flowing into the melt to determine a defect movement position; A defect precursor position setting step of setting as a position of a defect precursor in a molten metal flow analysis of a time step subsequent to the time step; and a step of setting the defect precursor position from the defect precursor generation determination step until the filling of the molten metal. A defect position determining step of determining the defect position at the end of the filling of the molten metal by repeating the steps up to the step, wherein in the gas pressure threshold value calculating step, residual air and lubricant generated under the casting conditions of the pressure casting are provided. The threshold value of the gas pressure is calculated in consideration of information on the volatile gas and the release agent volatile gas.

  In the present technology, it is determined that a defect precursor has occurred in an element in which the gas pressure exceeds a threshold value, the movement position of the defect precursor is calculated using the melt flow analysis information, and the final defect position is evaluated. According to this configuration, by setting the gas pressure threshold value in consideration of gas information generated during actual pressure casting, it is possible to more accurately predict a defect position.

  The second technique is the first technique, wherein in the movement calculation step, in the element in which the defect precursor is generated and the melt is determined to have flown, the flow rate of the molten metal flowing into the element is determined by: A moving distance calculating step of calculating a moving distance of the defect precursor, and a moving direction determining step of determining a moving direction of the defect precursor from a flow rate of the molten metal flowing into the element and / or a peripheral element of the element, A one element movement distance calculation step for calculating a movement distance for one element based on the size of each of the elements and the movement direction determined in the movement direction determination step, and a movement calculated in the movement distance calculation step A moving distance determining step of determining a moving destination element of the defect precursor when it is determined that the distance exceeds the moving distance of one element.

  According to the present technology, among the melt flow analysis information, the movement position of the defect precursor is calculated from the flow rate information of the molten metal in the element in which the defect precursor has occurred and elements in the vicinity of the element, and the final defect position is evaluated. I do. According to this configuration, a more accurate defect position can be predicted.

  A third technology is the first or second technology, wherein in the gas pressure threshold value calculation step, the defect occurrence condition includes information on a defect size, and the defect position prediction step includes the step of adding the defect position to the defect position. Further, a defect size at the time of completion of the filling of the molten metal is predicted.

  According to the present technology, it is possible to more accurately predict a defect position and a defect size.

  A defect position predicting device for a casting according to a fourth technique disclosed herein is a device for predicting a defect position of a casting in pressure casting in which a molten metal is injected into a mold under pressure. Mold model creating means for creating a mold model divided into elements; and, for the mold model, a molten metal flow at predetermined time steps from the start to the end of filling of the molten metal under the same casting conditions as in the pressure casting. A flow analysis means for performing an analysis to calculate a state quantity of the plurality of elements including a gas pressure of the plurality of elements and a flow rate of the molten metal at each time step; a result of the flow analysis; Gas pressure threshold value calculating means for calculating the gas pressure threshold values for the plurality of elements based on defect occurrence conditions desired to be predicted in the product; A gas pressure, the flow rate, and a defect position prediction unit that predicts a defect position at the end of the filling of the melt based on the gas pressure threshold value. In the result of the molten metal flow analysis, it is determined that a defect precursor has occurred in an element in which the gas pressure exceeds the threshold, and whether the molten metal has flowed into the element in which it has been determined that the defect precursor has occurred. Determine whether or not, when it is determined that the molten metal has flowed into the element, from the flow rate of the molten metal flowing into the element and / or the element around the element, to perform the movement calculation of the defect precursor, Determining the defect movement position, setting the defect movement position obtained by the movement calculation as the position of the defect precursor in the flow analysis of the next time step after the arbitrary time step, Until the filling of the molten metal is completed, the defect position at the end of the filling of the molten metal is determined by repeating the determination of the occurrence of the defective precursor, the determination of the inflow of the molten metal, the calculation of the movement, and the setting of the position of the defective precursor. Wherein the gas pressure threshold value calculating means calculates the gas pressure threshold value in consideration of information on residual air, lubricant volatile gas, and release agent volatile gas generated under the casting conditions of the pressure casting. It is characterized by.

  A fifth technology is the fourth technology, in the fourth technology, wherein the defect position predicting means has flowed into the element as the movement calculation, where the defect precursor is generated and the molten metal is determined to have flowed. The moving distance of the defect precursor is calculated from the flow velocity of the molten metal, and the moving direction of the defect precursor is determined from the flow velocity of the molten metal flowing into the element and / or an element surrounding the element. The moving distance for one element is calculated based on the size and the moving direction, and when it is determined that the moving distance of the defect precursor exceeds the moving distance for one element, the defect precursor is determined. It is characterized in that the element to which the body moves is determined.

  A sixth technique is the fourth technique or the fifth technique, wherein the defect occurrence condition includes information on a defect size, and the defect position predicting means includes, in addition to the defect position, The method is characterized by estimating a defect size.

  The defect position prediction program for a casting according to the seventh technology disclosed herein is a program for predicting a defect position of a casting in pressure casting in which a molten metal is injected into a mold under pressure. A mold model creation step of creating a mold model divided into a plurality of elements, and, for the mold model, under the same casting conditions as in the pressure casting, at predetermined time steps from the start of filling of the molten metal to the end of filling. Performing a molten metal flow analysis, a molten metal flow analysis step of calculating a state quantity of the plurality of elements including the gas pressure of the plurality of elements and a flow velocity of the molten metal at each time step, and a result of the molten metal flow analysis, A gas pressure threshold value calculating step of calculating the gas pressure threshold value in the plurality of elements based on a defect occurrence condition desired to be predicted in the casting, and The gas pressure, the flow velocity, and the gas pressure calculated based on the threshold value of the gas pressure, the defect position prediction step of predicting the defect position at the end of the filling of the molten metal, the defect position prediction step, In the result of the molten metal flow analysis at an arbitrary time step, a defect precursor generation determining step of determining that a defect precursor has occurred in an element where the gas pressure exceeds the threshold, and determining that the defect precursor has occurred A molten metal inflow determining step of determining whether the molten metal has flowed into the element, and flowing into the element and / or an element surrounding the element when it is determined that the molten metal has flowed into the element. The movement calculation of the defect precursor is performed based on the flow velocity of the molten metal, and a movement calculation step of determining a defect movement position, and the defect movement position obtained by the movement calculation is determined by the arbitrary time. A defect precursor position setting step to be set as the position of the defect precursor in the molten metal flow analysis of the next time step, and from the defect precursor generation determination step to the defect precursor position setting step until the filling of the molten metal is completed. And a defect position determining step of determining the defect position at the end of the filling of the molten metal.In the gas pressure threshold value calculating step, the residual air generated under the casting conditions of the pressure casting, the lubricant volatile gas And the threshold value of the gas pressure is calculated in consideration of the information of the release agent volatile gas.

  An eighth technique is the seventh technique, wherein in the movement calculation step, in the element in which the defect precursor is generated and the melt is determined to have flown, the flow rate of the molten metal flowing into the element is determined by: A moving distance calculating step of calculating a moving distance of the defect precursor, and a moving direction determining step of determining a moving direction of the defect precursor from a flow rate of the molten metal flowing into the element and / or a peripheral element of the element, A one element movement distance calculation step for calculating a movement distance for one element based on the size of each of the elements and the movement direction determined in the movement direction determination step, and a movement calculated in the movement distance calculation step A moving distance determining step of determining a moving destination element of the defect precursor when it is determined that the distance exceeds the moving distance of one element.

  In a ninth technique, in the seventh or eighth technique, in the gas pressure threshold value calculation step, the defect occurrence condition includes information on a defect size, and the defect position prediction step includes adding the defect position to the defect position. Further, a defect size at the time of completion of the filling of the molten metal is predicted.

  The recording medium on which the program for predicting a defect position of a casting according to the tenth technology disclosed herein is recorded with the program for predicting a defect position of a casting according to the seventh to ninth technologies.

  As described above, according to the present disclosure, in an element in which the gas pressure exceeds the threshold value, it is determined that a defect precursor has occurred, and the movement position of the defect precursor is calculated by using the melt flow analysis information. The defect location. According to this configuration, the threshold value of the gas pressure is set in consideration of gas information generated at the time of actual pressure casting, so that a more accurate defect position can be determined.

FIG. 1 is a sectional view schematically showing a die casting machine according to an embodiment of the present disclosure. FIG. 3 is a perspective view of a cylinder block of the engine obtained by the die casting machine. 1 is a block diagram illustrating a defect position prediction device according to an embodiment of the present disclosure. It is a flowchart of the defect position prediction method according to the embodiment. It is a flowchart which shows the defect position prediction process of the defect position prediction method of FIG. 4A. It is a figure which shows an example of the value of the gas pressure obtained in the hot water flow analysis in an arbitrary time step. It is a figure for explaining a defect precursor generation judging process. It is a figure for explaining a molten metal inflow judging process, a movement distance calculation process, and a movement direction decision process. It is a figure for explaining a moving direction decision process. It is a figure for explaining a moving direction decision process. It is a figure for explaining a moving direction decision process. It is a figure for explaining a moving direction decision process. It is a figure for explaining a movement calculation repetition process. FIG. 9 is a diagram for explaining a defect position determination step.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the present disclosure, its applications or uses.

(Embodiment 1)
≪Example of mold≪
As shown in FIG. 1, the mold according to the present embodiment is a mold 1 used for high pressure die casting (pressure casting in which a molten metal is injected into a mold under pressure). It is a die casting die. FIG. 1 schematically illustrates a die casting machine. The mold 1 (mold) includes a core 2 and has a cavity 4 for casting, for example, a cylinder block 3 (cast product) of an engine shown in FIG. A runner 6, a gate 7, and a vent runner 8 are formed on the fixed platen 5. The fixed platen 5 is provided with an injection cylinder 11 having a sleeve 10 and a plunger tip 9 for injecting the molten metal M into the cavity 4 via the runner 6. Further, a vacuum pump (not shown) for reducing the pressure of the cavity 4 via a vent runner 8 which is a vacuum passage is attached to the fixed platen 5.

  2 is a cylinder block of an in-line four-cylinder engine having four cylinder bores 12, and is made of an aluminum alloy. The first to fourth cylinders are denoted by reference numerals # 1 to # 4. Also, in FIG. 2, the direction indicated by the arrow is the left-right direction. The defect position prediction method according to the present embodiment can be applied not only to the cylinder block of the engine but also to various castings.

≪Defect position prediction device≫
In the defect position prediction method according to the embodiment of the present disclosure, for example, a defect position prediction device 21 illustrated in FIG. 3 can be used.

  The defect position prediction device 21 is a CAE (Computer Aided Engineering) system for casting, and includes a control device 22, an input device 23, an output device 24, a storage device 25, and an arithmetic device 26. The input device 23, the output device 24, the storage device 25, and the arithmetic device 26 are connected to the control device 22. The input device 23 includes a keyboard and a mouse connected to a computer. The output device 24 is configured by a display or the like connected to a computer. As the storage device 25, a storage unit such as a RAM or a ROM in a computer is used, and as the arithmetic unit 26, an arithmetic processing unit including a CPU of the computer is used.

  The storage device 25 stores information relating to the mold 1, information relating to the molten metal injection conditions, information relating to computations in the computation device 26, a program for executing computation processing, and the like. In particular, the storage device 25 stores the state quantities, gas pressure thresholds, defect precursor positions, defect positions, and the like of a plurality of elements as a result of the melt flow analysis in the mold model of the cylinder block 3 as described later. ing.

  The arithmetic unit 26 constitutes a mold model creation unit, injection condition setting unit, molten metal flow analysis unit, gas pressure threshold value calculation unit, and defect position prediction unit, which will be described later.

≪Defect location prediction method≫
A defect position prediction method according to an embodiment of the present disclosure will be described with reference to flowcharts illustrated in FIGS. 4A and 4B and FIGS.

  As shown in FIG. 4A, the defect position prediction method according to the embodiment of the present disclosure includes a mold model creation step S1, a molten metal flow analysis step S2, a gas pressure threshold value calculation step S3, and a defect position prediction step SI. .

<Mold model creation process>
In a mold model creation step S1, a mold model is created by dividing the cavity 4 of the mold 1 as a mold for casting the cylinder block 3 into a plurality of elements.

  This mold model creation step S1 is performed by the mold model creation means of the arithmetic unit 26. To create the mold model, a casting plan CAD model created at the stage of designing the mold based on the product CAD model is used. The model creating means creates a mold model (finite element model) in which the cavity 4 is divided into a plurality of elements by dividing the casting plan CAD model into meshes. Although the size and shape of the elements are arbitrary, for example, one element may be a cube having a square of 0.5 mm or more and 2 mm or less. Further, for example, a mold model of a casting can be divided into 100,000 or more and 1 billion or less elements. In this specification, a plurality of elements may be referred to as “mesh”.

<Molten flow analysis process>
In the molten metal flow analysis step S2, a molten metal flow analysis by CAE is performed using the above-described mold model. This step is performed by the hot water flow analysis means of the arithmetic unit 26. Specifically, the molten metal flow analysis is performed under the same molten metal injection conditions as in the pressure casting of the cast product in FIG. The setting of the molten metal injection condition is performed by the injection condition setting means of the arithmetic unit 26. As the molten metal injection conditions, the molten metal temperature, the injection speed, the shape and position of the gate, and the like are set. These injection conditions are automatically selected and set by the injection condition setting means based on the injection conditions stored in the storage device 25. Note that the operator may input the injection condition using the input device 23.

  General-purpose casting analysis software such as “MAGMASOFT” by MAGMA GmbH and “JSCAST” by Qualica can be used as the molten metal flow analysis means. The calculation is repeated for each arbitrarily set time step from the start of filling of the molten metal (filling rate of 0%) to the end of filling (filling rate of 100%) to calculate various state quantities of each element in each time step. can do. The time interval between each time step is not particularly limited, but can be set to, for example, 0.1 seconds or more and 2 seconds or less.

  By this molten metal flow analysis, the gas pressure in each element and the flow velocity of the molten metal reaching each element are calculated as the state quantities in each element of the cavity. Note that the flow velocity of the molten metal that has reached each element can be obtained from vector information.

  Further, in this specification, “gas pressure” refers to pressure information of an element that is not filled with the molten metal among the elements. For example, consider a mesh M1 composed of 16 elements as shown in FIG. The element indicated as 0 in the mesh M1 indicates that 100% of the molten metal is filled, no gas is present, and the gas pressure is 0. Further, for example, an element indicated by 100 indicates that the filling rate of the molten metal is not 100%, but a gas is present, and the gas pressure is 100 mbar.

  FIG. 5 shows the gas pressure values of the respective elements of the mesh M1 obtained by the calculation of the molten metal flow in the time steps TS1 to TS3.

  In the time step TS1, the gas pressure value is 100 mbar in the nine elements, and it is considered that the gas was present in the region including the nine elements. Then, in the time step TS2, it can be seen that the gas pressure has increased to 300 mbar in the three central elements among the nine elements. Furthermore, at time step TS3, it can be seen that the gas pressure has increased to 900 mbar in one of the three elements.

  From the display of these gas pressures, a gas region is generated in the region consisting of the nine elements before the time step TS1, and at each time step, the molten metal flows from the periphery of the gas region into the element of the gas region and the gas flows. It is considered that the volume of the region was reduced and the gas pressure in the elements constituting the gas region was increased.

  Thus, in the above-described general-purpose software, the history of the maximum value of the gas pressure in each element is displayed as a result of the calculation of the molten metal flow in each time step. Then, as described later, when the gas pressure exceeds a predetermined threshold value, it can be determined that a bubble serving as a defect in the casting, that is, a “defect precursor” is generated in the element at some time ( (See the description of the gas pressure threshold value calculation step S3 and the defect position prediction step SI described later.) It should be noted that the above-mentioned general-purpose software cannot accurately display the movement of a defect precursor even if an element having a high gas pressure value is generated at any time step. Further, with the general-purpose software, the gas pressure can calculate only the gas pressure of the residual air, and the gas pressure derived from other gas components is not reflected in the calculation result.

<Gas pressure threshold calculation step>
In the gas pressure threshold value calculation step S3, based on the result of the molten metal flow analysis obtained in the molten metal flow analysis step S2 and the defect generation conditions to be predicted in the cylinder block 3 which is a casting, each element included in the mold model is determined. Calculate the gas pressure threshold. The “gas pressure threshold” refers to the lower limit of the gas pressure at which it can be determined that the above-mentioned defect precursor is generated. The calculation is performed by the arithmetic unit 26 as a gas pressure threshold value calculating unit. Then, the calculated gas pressure threshold value is stored in the storage device 25.

-Gas pressure threshold calculation method-
The threshold value of the gas pressure is calculated, for example, by applying the Boyle-Charles law and using the following equation (1) as follows.

P1 · V0 / T1 ≧ P2 · V2 / T2 (1)
However, in the equation (1), P2, V2, and T2 are values relating to the defect generation conditions for which it is desired to predict the occurrence in the casting, and are a predicted casting pressure, a predicted defect volume, and a predicted molten metal temperature, respectively. The predicted casting pressure P2 is a casting pressure assumed when actually performing casting, the predicted defect volume V2 is a volume of a void that can be determined as a defect in an actual cast product, and the predicted molten metal temperature T2 is an actual casting temperature. The temperature of the molten metal that is assumed when performing the above can be adopted.

  P1 and T1 are the molten metal flow analysis values in the molten metal flow analysis step S2, and are the gas pressure of an arbitrary gas region and the temperature of the gas region, respectively. Note that the gas region is composed of one or more elements. V0 is a value obtained by correcting the volume value V1 of the gas region obtained from the molten metal flow analysis result in the molten metal flow analysis step S2 in consideration of a gas component amount that can actually cause a defect, as described later. is there.

  First, assume that T1 = T2. In this embodiment, an example will be described in which T1 = T2 is assumed, but the relationship between T1 and T2 is not limited to this. That is, during solidification of the molten metal, the temperature of the molten metal generally decreases, so that T1 and T2 can be assumed to be different values as calculation conditions.

  Next, the minimum diameter R (defect size information) of the defect whose occurrence is to be predicted in the cylinder block 3 which is a casting is determined. Then, from the minimum diameter R described above, the defect is regarded as a true sphere, and the volume V2 of the defect is assumed as in the following equation (2).

^{V2 = 4π (R / 2)} 3/3 = πR 3/6 ··· (2)
Next, the volume V1 of the region obtained as a result of the melt flow analysis in the melt flow analysis step S2 is substantively corrected to obtain the value V0. Specifically, the correction is performed as follows.

  That is, in the hot water flow analysis using general-purpose software, only the volume of the residual air can be calculated. Therefore, the volume V1 of the region obtained as a result of the hot water flow analysis indicates the volume of the residual air.

  However, in the cavity 4, in addition to the residual air, the volatile gas of the lubricant for sliding lubrication of the plunger tip 9, the volatile gas of the release agent applied to the cavity surface, Etc. exist.

  In addition, the amount of generated residual gas and the amount of components composed of these components can be analyzed by a known gas analysis, as described later. The inventors of the present application have found that, from the results of gas analysis and the results of analysis of actual castings, among the gas components contained in the residual gas, a component that may cause a defect is a specific component including residual air. I found that.

  Then, since the volume V1 of the region obtained as a result of the hot water flow analysis in step 2 is the volume of the residual air, in addition to the residual air, of the residual gas, the volume of other components that may cause a defect is determined. In consideration of the above, it is appropriate to convert the volume V1 into a volume V0 of a specific component that can cause a defect. Therefore, assuming that the volume of a specific component that can cause a defect is 1 and the ratio of the volume of air in the specific component is t, the volume V0 of the specific component that can cause a defect can be obtained by the following equation (3). .

V0 = V1 × 1 / t = V1 / t (3)
When the above equations (2) and (3) are substituted into the above equation (1) and rearranged, the following equation (4) is obtained.

P1 ≧ (πR ³ · t / 6V1) × P2 (4)
From equation (4), the threshold value of the gas pressure P1 is found to be ^{(πR 3 · t / 6V1)} × P2.

-Example of gas pressure threshold calculation-
For example, the predicted casting pressure P2 = 60 MPa (= 60 × 10 ⁴ mbar), the ratio t = 0.158 of the volume of air in a specific component which may be a cause of defects contained in the gas (Experimental example 16 of gas analysis described later) Calculate the air ratio from the nitrogen ratio of the light boss), assuming that the minimum diameter of the defect whose occurrence is to be predicted is R = 0.5 mm and V1 = 6.6 mm ³ , from equation (4), P2 ≧ 934 mbar, and the gas pressure P1 The threshold can be calculated as 934 mbar.

-Gas analysis in actual casting-
When casting the cylinder block 3, the gas amount and gas components (types: H ₂ , O ₂ , CH) of the cast sample generated in each part of the mold are determined by a known gas chromatography analysis and a visual observation of the structure of the cast sample. ₄ , CO, CO ₂ , C ₂ H ₄ , C ₂ H ₆ ) and the relationship between the defect amount and the defect position were analyzed. Table 1 shows the structure of the cast sample.

  In Table 1, the molten metal in the holding furnace of Experimental Example 1 is a rod-shaped crude casting formed in the holding furnace for the molten metal provided in the fixed platen 5. The sea cucumber of the experimental example 2 or the extruded sea cucumber of the experimental example 3 is a crude cast product obtained as a result of manual dumping (experimental example 2) or automatic dumping (experimental example 3) for preheating the sleeve 10. It is a molten metal that has solidified in a cylindrical shape within 10. Experimental examples 4 to 14 are each part of the cylinder block 3 and include a first cylinder bore exhaust side, a first cylinder bore intake side, a second cylinder bore exhaust side, a second cylinder bore intake side, a third cylinder bore exhaust side, The third cylinder bore intake side, the fourth cylinder bore exhaust side, the fourth cylinder bore intake side, the back metal and the light boss are indicated by reference numerals 121, 122, 123, 124, 125, 126, 31 and 32 in FIG. Part. The left boss of Experimental Example 13 is not shown in FIG. 2, but, like the right boss of Experimental Example 16, is a tubular boss disposed on the left side surface of the cylinder block 3 for assembling auxiliary equipment and the like. Or it is a columnar projection. Experimental Example 15 is a crude casting product solidified in a bent runner indicated by reference numeral 8 in FIG.

The casting conditions are as follows. That is, a 2250 ton high pressure die casting machine (made by UBE) was used. The casting pressure was 60 MPa, the molten metal was an aluminum alloy, the molten metal temperature was about 650 ° C., the molten metal injection speed was 6.0 m / s, and the mold temperature was about 180 ° C. The lubricant for sliding lubrication of the plunger tip 9 is refined mineral vegetable oil graphite dispersion (Plunger Height F-1G, manufactured by Nippon Graphite Industry Co., Ltd.). Water-soluble polysiloxane (Deltacast liquid powder 1 manufactured by Acheson Japan Limited) was used. The application of the lubricant and the release agent was performed by a spray device attached to the high pressure die casting device. The main gas components that can be generated from the lubricant and the release agent are considered to be H ₂ , O ₂ , CH ₄ , CO, CO ₂ , C ₂ H ₄ , and C ₂ H ₆ . The presence or absence of the application of the lubricant and the release agent is shown in Table 1 by ○ (with coating) and X (without coating). The amount of the lubricant applied in Experimental Examples 2 to 15 was 8.0 mL. The amount of the release agent applied in Experimental Examples 4 to 15 was 7.0 mL.

  The structure of the cast sample was visually observed by one observer observing the structure of the cast sample and evaluating the voids having a diameter of about 0.5 mm or more as defects by the following four steps.

× No or almost no defects △ Some defects ○ Some defects ◎ Many defects Tables 1 and 2 show the amounts of residual gas (total amount and per 100 g of cast sample) and components of residual gas for the cast samples of Experimental Examples 1 to 15. The results of ratio analysis and the results of visual observation of cast samples are shown.

  In the molten metal in the holding furnace of Experimental Example 1 and the cast sample of sea cucumber in Example 2, the amount of defects was small, and the hydrogen gas contained in the residual gas was a component that hardly caused defects, based on the result of visual observation of the structure. I understand. However, it is considered that a defect due to residual air (calculated from the nitrogen ratio of the gas components in Table 2 as described later) also occurs in these cast samples.

In the cast sample of the extruded sea cucumber of Experimental Example 3, some defects were observed. In the gas components, the ratio of hydrogen H ₂ decreases, the ratio of carbon dioxide CO ₂ increases, and trace amounts of methane CH ₄ and carbon monoxide CO are also detected. This is considered to be due to the effect of the lubricant applied to the plunger tip 9. It is considered that the lubricant volatilizes before being taken into the molten metal and is taken into the molten metal in a gaseous state, or is taken into the molten metal in a liquid state and volatilizes during casting to cause defects.

In the bores of Experimental Examples 4 to 11, the residual gas amount was increased as compared with those of Experimental Examples 1 to 3, and hydrogen H ₂ , nitrogen N ₂ , methane CH ₄ , carbon monoxide CO, and carbon dioxide CO ₂ were reduced by 10%. About 30% is detected. Further, in Experimental Examples 4 to 11, the defect amount was increased as compared with those in Experimental Examples 1 to 3. This is considered to be due particularly to the influence of the release agent applied to the molding surface. Similarly to the lubricant, the release agent volatilizes before being taken into the molten metal and is taken into the molten metal in a gaseous state, or is taken into the molten state in a liquid state and volatilized at the time of casting, causing defects. Likely to occur.

In the back metal of Experimental Example 12, as compared with the bores of Experimental Examples 4 to 11, the amount of carbon dioxide CO ₂ becomes a trace amount, and the amount of carbon monoxide CO is particularly increased. Little change is seen.

  In the bosses of Experimental Examples 13 and 14, as compared with the bores of Experimental Examples 4 to 11, the types of gas components are almost the same, but the residual gas amount is increased and the defect amount is also increased. Since the boss is provided in a protruding shape on the side surface of the cylinder block 3, it is considered that the filling of the molten metal is more difficult than that of the bore, and a defect due to residual gas is likely to occur.

  In the vent runner of Experimental Example 15, the residual gas amount and the defect amount increased significantly. Since the vent runner is a vacuum evacuation passage, it is considered that the residual gas in the mold tends to concentrate and defects are likely to occur.

-Gas components that can cause defects-
From the results of the gas analysis, it can be seen that among the components of the gas existing in the cavity, components that may cause defects are residual air, release agent volatile gas and lubricant volatile gas. In addition, among the components contained in the gas, hydrogen almost escapes during casting due to the casting pressure, and thus hardly causes defects.

Therefore, when obtaining the threshold value of the gas pressure P1, as one of the defect occurrence conditions of the casting, information on residual air, lubricant volatile gas and release agent volatile gas generated under the casting conditions of pressure casting is considered. The corrected volume V0 can be set. Specifically, in the above formula (4), of the gas components contained in the residual gas, specific components that may cause defects, namely, residual air, release agent volatile gas, and lubricant volatile gas (specifically, Is methane CH ₄ , carbon monoxide CO, carbon dioxide CO ₂ , ethylene C ₂ H ₄ , ethane C ₂ H _{6 and the} like, and the gas component can change depending on the type of the release agent and the lubricant. Assuming that the ratio of the volume is 1 and the ratio of the residual air in the specific component is t, the corrected volume V0 can be calculated. In addition, the ratio of the residual air contained in the residual gas is calculated from the nitrogen ratio of the gas components in Table 2, for example, assuming that the air component ratio is nitrogen N ₂ : oxygen O ₂ : balance = 78: 21: 1. Can be.

-Defect occurrence status of each part of casting-
As shown in the above gas analysis results, the defect position, the size of the defect, and the ratio of the gas component actually occurring in the cast sample generated in each part of the mold for manufacturing the cylinder block 3 are examined. It turns out that ease of use is different.

  Therefore, the threshold value of the gas pressure P1 may be set to a different value for each of the corresponding parts of the mold related to the casting based on the properties of the respective parts of the casting obtained by die casting. Specifically, for example, among the mold models of the cylinder block 3, the bore and the boss differed in the residual gas amount and the defect occurrence rate as described above. Therefore, for the bore and the boss, different values are set as the threshold value of the gas pressure P1 by reflecting the results of Table 2 on the ratio t of the volume of the residual air in the specific component that may cause the defect. Is also good.

<Defect position prediction process>
The defect position prediction step SI shown in FIGS. 4A and 4B obtains a flow analysis result at an arbitrary time step, and calculates the gas pressure, the flow velocity, and the gas pressure threshold calculated in the flow analysis. Is a step of predicting a defect position at the time of completion of the filling of the molten metal based on the above. The defect position prediction step SI is executed by the arithmetic unit 26 as defect position prediction means. The result calculated in the defect position prediction step SI is stored in the storage device 25.

  As shown in FIG. 4B, the defect position prediction step SI includes a defect precursor generation determination step S4, a molten metal inflow determination step S5, a movement calculation step SII, a defect precursor position setting step S11, and a repetition calculation step S12. And a defect position determining step S13.

-Defect precursor generation determination process-
In the defect precursor generation determining step S4, it is determined that a defect precursor has been generated in an element of the mesh of the mold model at an arbitrary time step where the gas pressure exceeds the threshold.

  Specifically, taking the value of an example of the above gas pressure threshold value calculation as an example, when the gas pressure in a certain element exceeds 930 mbar set as a threshold, a sphere having a minimum diameter R in that element is used. It is determined that a defect precursor having the same volume as that of the defect precursor has been generated. When the gas pressure exceeds a threshold value in a plurality of continuous elements, it is determined that a defect precursor having a volume obtained by multiplying the volume of a true sphere having the minimum diameter R by the number of elements has been generated. The volume of the defect precursor is equal to the volume of the defect finally obtained at the end of filling the molten metal. As described above, the volume of the defect precursor is determined by the size of the minimum diameter R and the number of elements, and the size of the finally obtained defect can be predicted based on the setting of the minimum diameter R and the number of elements.

  FIG. 6 is an example of an analysis image of a part of the mold model. The upper left diagram shows the gas pressure, the upper right diagram shows the flow velocity (the direction of the arrow indicates the direction of the vector), and the lower right diagram shows the It is a defect evaluation display. In FIG. 6, the display of each element is omitted for understanding. Although FIG. 6 shows a two-dimensional display, analysis can be performed on a three-dimensional template model.

  As shown in the upper left diagram of FIG. 6, for example, it is assumed that the gas pressure exceeds 930 mbar in one element a1 included in the range indicated by reference numeral A1. Then, as shown in the lower right figure, it is determined that a defect precursor B having the same volume as the volume of a true sphere having the minimum diameter R has been generated in the element a1.

  Since the generation of the defect precursor B is not determined for an element whose gas pressure does not exceed 930 mbar, the flow proceeds to a defect precursor position setting step S11 to be described later in the flow illustrated in FIG. 4B, and the defect position is set. The process proceeds to the defect position prediction process SI in the next time step without any change.

-Determining the flow of molten metal into the element determined to have a defect precursor-
In the molten metal inflow determination step S5, it is determined whether the molten metal has flowed into the element a1 for which it has been determined that the defect precursor B has occurred.

  Specifically, for example, as shown in FIG. 7, when the magnitude of the flow velocity of the molten metal in the element a1 exceeds 0, it is determined that the molten metal has flowed into the element a1. With the inflow of the molten metal, the movement of the defect precursor B generated in the element a1 is started.

  When it is determined that the molten metal has not flowed into the element a1, the process proceeds to the defect precursor position setting step S11, and proceeds to the defect position prediction step SI of the next time step. At this time, in the next time step, the position of the defect precursor B is set to the position of the element a1.

-Movement calculation process-
In the movement calculation step, when it is determined in the melt inflow determination step S5 that the melt has flowed into the element a1, the movement of the defect precursor B is calculated from the flow velocity of the melt flowing into the element a1, and the defect movement position is determined. Is a step of determining

  As shown in FIG. 4B, the movement calculation step SII includes a movement distance calculation step S6, a movement direction determination step S7, a movement distance calculation step S8 for one element, a movement distance determination step S9, and a repetition movement calculation step S10. Is provided.

~ Moving distance calculation process ~
First, in the moving distance calculation step S6, the moving distance of the defect precursor B is calculated from the flow velocity of the molten metal flowing into the element a1.

Specifically, for example, in a time step i shown in FIG. 7, the results of the hot water flow analysis, molten metal flowing into the element a1 is the flow velocity v _{i (vector} quantity) (speed in the direction indicated by the arrow | v _i | ) Is obtained. From the flow rate information is calculated based on the moving distance R _i of the defective precursor B at the current time step i, which we calculated the following equation (6).

_{R i = | v i | ×} (t i + 1 -t i) + △ R i-1 ··· (6)
Here, t _{i + 1} −t _i is the time between the next time step i + 1 and the current time step i, and ΔR _i−1 is the remaining movement amount in the previous time step i−1. t _{i + 1} −t _i is not intended to be limited, but may be, for example, 0.01 mm seconds to 10 seconds. The remaining movement amount △ R _i-1 in the previous time step _i-1 will be described later.

-Defect precursor moving direction determination step-
In the moving direction determination step S7, for example, as shown in FIG. 7, from the direction of the flow velocity v _i of the molten metal that has flowed into the elements a1, determined using the direction of movement, for example, the following method of the defective precursor B.

Specifically, for example, it is assumed that the element a1 is a cube, and the x-axis, the y-axis, and the z-axis each define an orthogonal coordinate system that passes through the center of the element a1 and one center of a square forming the side surface of the element a1. Think. Then, as shown in FIGS. 8 and 9, a cross section of the element a1 in, for example, the xy plane, that is, an xy cross section is considered. Eight elements indicated by reference numerals D1 to D8 exist around the element a1. Component in the xy cross section of the flow velocity _{v i} of the molten metal that has flowed into the elements a1, i.e. xy component _{v xy} of the flow velocity _{v i} is represented by arrows in FIG. 10. Incidentally, each component in the yz cross section, xz cross section of the flow velocity _{v i,} respectively _{v yz, v} is represented by the _xz.

And xy component v _xy of the flow velocity v _i, when the angle between the positive direction of the x-axis and theta, depending on the magnitude of the angle theta, the moving direction of the defect precursor B shown in FIG. 9 arrow varies . From the flow velocity _{v i} elements a1, calculated in each cross section the movement direction of the quadrant of the defective precursor B (xy section, xz cross, yz cross section). The angle θ is the angle between the positive direction of the x axis and v _xy in the _xy section, the angle between the positive direction of the y axis and v _yz in the _yz section, and the positive direction of the z axis and v _{xz in the} xz section. Angle. Table 3 shows the setting of the amount of movement according to θ and the criteria for determining the element in the moving direction.

  Then, regarding the result of the quadrant in the moving direction of the defect precursor B in each section calculated according to Table 3, the result in each section is integrated to determine the element of the moving direction of the defect precursor B. As shown in Table 4, if the result of each section is the same in each axial direction, the amount of movement in each axis direction is the result of the section in the axial direction. Specifically, for example, in the case of the results on the x-axis in Table 4, since the results on the xy section and the xz section are both the same and are the same, the moving amount of the defect precursor B in the x-axis direction is 1.

  In addition, as shown in Table 5, when the results of the respective sections are different in the results of the respective axial directions, the larger of the amounts of movement in the respective axial directions is regarded as the amount of movement in the relevant axial direction. Specifically, for example, in the case of the results on the x-axis in Table 5, the results on the xy section and the xz section differ by 1 and 0, respectively. In this case, the larger the moving amount is adopted, the moving amount of the defect precursor B in the x-axis direction is 1.

  In the moving direction determining step S7, a step of determining whether the material of the peripheral element of the element a1 where the defect precursor B exists is a cast product may be further provided.

  When the material of all peripheral elements of the element a1 is a cast product, that is, a molten metal or a cavity space, the moving direction of the defect precursor B is determined according to, for example, the above-described method.

On the other hand, if the material of at least one of the peripheral elements of the element a1 is a material other than a cast product, specifically, a material such as a molding surface of a mold into which molten metal cannot flow, a material other than the cast product The defect precursor B cannot move to the element having Therefore, when the material of at least one element of the peripheral elements of the element a1 is determined not to be in castings, in addition to the direction of the flow velocity v _i of the molten metal that has flowed into the elements a1, the material of the elements D1~D8 and The moving direction of the defect precursor B is determined in consideration of the flow velocity information, for example, as follows.

For example, as shown in FIG. 10, in the xy cross section, among the peripheral elements of the element a1, the element D3 is assumed to be a material other than the cast product. The xy component v _xy of the flow velocity v of the element a1 is a component in a direction parallel to the straight line L1 passing through the center of the element a1 and the center of the element D3 and in which the direction from the element a1 to the element D3 is positive. It is assumed that v _xy 1 (the component in the y-axis direction in FIG. 10) and its orthogonal component v _xy 2 (the component in the x-axis direction in FIG. 10) are decomposed into two components.

Further, as shown in, for example, an element D7 in FIG. 11, the xy cross-sectional component v _xy Dk of the flow velocity vDk of the molten metal of the element Dk (k = 7 in FIG. 11) is defined by a straight line passing through the center of the element Dk and the center of the element a1. A component v _xy Dk1 in a direction (the y-axis direction in FIG. 11) parallel to L2 and with the direction from the element Dk toward the element a1 being positive, and a component v in the orthogonal direction (x-axis direction in FIG. 11). _{When xy} Dk2 is decomposed into two components, the case where v _xy Dk1> 0 is referred to as “the direction of v _xy of the flow velocity v of the element Dk toward the element a1”, and v _xy Dk1 ≦ 0 Is defined as "the direction of v _xy of the flow velocity v of the element Dk is a direction away from the element a1".

(1) First, among the peripheral elements Dk of the element a1, peripheral elements Dk satisfying the flow velocity component v _xy Dk1> 0 of the molten metal are excluded from the destination candidates. For example, in FIG. 11, the peripheral elements D5 and D7 satisfy v _xy D51> 0 and v _xy D71> 0, and are therefore excluded from the destination candidates.

(2) Next, when v _xy 1> 0 and v _xy 2 ≠ 0, the element in the direction of the orthogonal component v _xy 2 is selected as a candidate for the element in the moving direction. Accordingly, since the example of FIG. 10 corresponds to the case where v _xy 1> 0 and v _xy 2 ≠ 0, the element D1 in the direction of v _xy 2 is selected as a candidate for the element in the movement direction.

(3) If v _xy 1> 0 and v _xy 2 = 0 (see FIG. 11) with respect to the flow velocity of the element a1, the material is cast among the peripheral elements D1, D2, D4, D6, and D8. an article, and the direction of v _xy of the flow velocity v _i to select the elements that are away from the element a1 as a candidate for the moving direction of the element. Also, when an element in the direction of movement there are two or more, and v _{xy Dk} elements Dk, selected as v element movement direction of the element having a larger angle between the _xy candidate elements a1.

(4) If v _xy 1 ≦ 0, a candidate for an element in the moving direction is selected by the method defined in Tables 3 to 5 above.

The processing of (1) to (4) is performed on all of the xy section, the xz section, and the yz section, and the final element in the moving direction is selected. Most angle of when the candidate of the destination element is present 2 or _{more, v} the angle between the _xy and _v xy _{Dk, v} the angle between the _xz and _v xz _{Dk, v} the angle between the _yz and _v yz Dk An element having a large flow velocity component is defined as an element in the movement direction.

  In the mold model creation step S1, if one element is a cube having a square of 0.5 mm or more and 2 mm or less and the mold model of the casting is divided into 100,000 or more and 1 billion or less elements, It is unlikely that only one of the peripheral elements D1 to D8 is a material other than a cast product, and it can be considered that three or more continuous elements are materials other than a cast product. Specifically, for example, in FIG. 11, when the element D3 is made of a material other than the cast product, the elements D2 and D4 adjacent to the element D3 are often made of a material other than the cast product.

移動 Step of calculating moving distance for one element〜
If in the previous moving direction determination step S7 in the elements of the moving direction is determined, in one element moving distance calculation step S8, the element size, based on the said moving direction, the following formula movement distance Q _i of one element It is calculated by (7). The “movement distance Q _{i for} one element” means that the defect precursor B moves from the element a1, which is the current position, to the peripheral element closest to the element a1 in the movement direction. It refers to the required minimum moving distance.

Q _i = movement amount in x-axis direction × mesh width △ movement amount in x + y-axis direction × mesh width △ movement amount in y + z-axis direction × mesh width △ z (7)
However, in equation (7), the movement amount in the x-axis direction, the movement amount in the y-axis direction, and the movement amount in the z-axis direction are calculated in the movement direction determination step S7 as shown in Tables 4 and 5, for example. Value. The mesh widths △ x, △ y, and △ z are the sizes of the elements in the x-axis direction, the y-axis direction, and the z-axis direction, respectively, and can be appropriately changed according to the minimum element size, the element shape, and the like. For example, if the element is a cube and the minimum element size is d, then △ x = △ y = △ z = d.

~ Moving distance judgment process ~
In the moving distance determining step S9, whether the moving distance R _i calculated by the mobile previous distance calculation step S6 is, exceeds the movement distance Q _i of one element calculated in one element of the previous minute moving distance calculation step S8 judge. When the moving distance R _i is determined to exceed the moving distance Q _i of one element (R _{i> Q i),} based on a result of the movement preceding direction determination step S7, the defect precursor B Determines the destination element of.

The moving distance R _i is not greater than the movement distance Q _i of one element (R _i ≦ Q _i) and when it is determined, since the defect precursor B stays elements a1, defect precursors position setting step Proceeding to S11, the position of the defect precursor B is set to the element a1, and the process proceeds to the defect position prediction step SI in the next time step.

~ Movement calculation repetition process ~
In previous travel distance decision step S9 in, if it is determined that the moving distance R _i> 1 moving distance Q _i of element content, move to that determined defective precursor B to move the element element, the moving distance There repeating the steps until the moving distance calculation step S6~ travel distance decision step S9 to almost reach the moving distance R _i.

Specifically, for example, as shown in FIG. 12, the defect precursor B moves from the element a1 in the range A1 to the element a2 in the range A2 by one movement. Then, it is assumed that the second movement moves to the element a3 in the range A3. Thus, until the final movement distance of the defect precursor B is substantially reaches the moving distance R _i, and repeats the above steps.

In the case of moving distance R _i> 1 element content moving distance Q _i of, repeating the movement of the defect precursor B, and reach the case where the moving distance R _i ≦ 1 element content moving distance Q _i of. In this case, the defect precursor B is held in the last movement destination element while maintaining the remaining movement amount ΔR _i represented by the following equation (8), and then the defect precursor B is set in the defect precursor position setting step S11. Then, the process proceeds to a defect position prediction process SI of the next time step.

△ _{R i} = moving distance _R i _-Σ1 element content of the movement distance _Q i ··· (8)
In the formula (8), the movement distance Q _i of Σ1 element content is the sum of the movement distances Q _i of one element just before as the moving distance R _i ≦ one element moving distance Q _i of.

On the other hand, in the case of the moving distance Q _i> moving distance R _i of one element, while retaining the moving distance R _i as the remaining travel △ R _i, the process proceeds to the defect precursors position setting step S11, the defect precursor B The position is set to the element a1, and the process proceeds to the defect position prediction process SI of the next time step.

-Defect precursor position setting process in next time step-
In the defect precursor position setting step S11, the destination element of the defect precursor B obtained in the movement calculation step SII is set as the defect precursor position in the next time step.

  At the stage where the defect precursor position is set in the next time step, the defect precursor position information may be output as a calculation result. Then, by inputting the calculation results again into general-purpose casting analysis software such as “MAGMASOFT” by MAGMA GmbH and “JSCAST” by Qualica, for example, as shown in FIG. 6, FIG. 7, FIG. 12, and FIG. As described above, the defect precursor position information for each time step can be visualized in the flow analysis.

-Iterative calculation process-
In the repetitive calculation step S12, the repetition calculation of the defect precursor generation determination step S4 to the defect precursor position setting step S11 is performed until the filling of the molten metal in the mold model is completed (100% filling).

-Defect position determination process-
Then, in the defect position determination step S13, the finally obtained defect precursor position is determined as the defect position at the end of filling the molten metal.

  For example, as shown in FIG. 13 as a schematic example, after the occurrence of the defect precursor B is determined in the defect precursor occurrence determination step S4, the defect precursor B is calculated in the range A1 → A2 → A3 → A4 → A5 by the above calculation. It is assumed that the objects move sequentially and finally reach the position of the element a5 in the range A5. Thus, the element a5 is determined as the final defect position at the end of the filling of the molten metal.

<Effects>
As described above, according to the defect position prediction method according to the present embodiment, it is determined that a defect precursor has occurred in an element in which the gas pressure exceeds the threshold value in the melt flow analysis information, and the defect precursor The moving position of the defect precursor is calculated from the flow rate information of the molten metal in the element in which the element occurs and the element in the vicinity of the element, and the final defect position is evaluated by repeatedly performing the calculation. In this way, it is possible to more accurately predict the defect position and the defect size, and the consistency between the analysis result of the casting analysis simulation and the defect position with the casting is improved.

  Actually, as an embodiment, for the cylinder block 3 described above, casting analysis software MAGMASOFT (manufactured by MAGMA GmbH) is used as a molten metal flow analysis means, and an example of the gas pressure threshold value calculation in the gas pressure threshold value calculation step S3 is described below. Under the conditions described above, a defect position was predicted. As a comparative example, the flow of the molten metal by MAGMASOFT was analyzed up to 100% filling, and an element having a finally obtained gas pressure value exceeding 930 mbar was determined as a defect position. Then, in the case of the example, the consistency between the analysis result and the defect position in the actual casting was improved from 56% to 83% as compared with the case of the comparative example.

  As described above, by using the defect position prediction method according to the present embodiment and adjusting the casting conditions to perform the analysis, it is possible to calculate the casting conditions of the casting with reduced defects in advance. Thus, it is possible to contribute to an improvement in the yield of the actual cast product at a low cost and in a short time.

<< Defect position prediction program and its recording medium >>
All of the above defect position prediction methods are programmed as a defect position prediction program. This defect position prediction program can be executed by the control device 22 while being stored in the storage device 25. Further, the defect position prediction program is not limited to the state stored in the storage device 25, and can be recorded on various known computer-readable recording media such as an optical disk medium and a magnetic tape medium. The program can be executed by mounting the recording medium on the reading device of the control device 22 and reading the program.

(Other embodiments)
Hereinafter, other embodiments according to the present disclosure will be described in detail. In the description of these embodiments, the same parts as those of the first embodiment are denoted by the same reference numerals, and detailed description will be omitted.

  In the molten metal flow analysis step S2, as the state quantities of the plurality of elements, the temperature of the molten metal, the temperature of the mold, the molten metal age (elapsed time from when the molten metal starts to be injected to the element), and the element reaches the element from the gate. The flow length of the molten metal up to, and the contact time of the molten metal reaching the element with the air may be calculated. Then, in the gas pressure threshold value calculation step S3, these information may be considered when calculating the gas pressure threshold value.

  In the moving direction determining step S7, the orthogonal coordinate system is used as a reference, but the present invention is not limited to this, and another coordinate system such as an oblique coordinate system or a polar coordinate system may be used as a reference.

  The castings are not limited to the cylinder block 3, but high-pressure casting parts such as a transmission case, a clutch housing, a lower block, a suspension housing, a lower arm, low-pressure casting parts such as a cylinder head and a rear hub support, and other various castings. It may be an article.

  Pressure casting is not limited to high pressure die casting, that is, high pressure casting, but also includes low pressure casting, magnesium casting, semi-solid casting, a die casting process having a different molten metal component and casting form, and a pressure casting using cast iron or resin as a raw material. You may.

1 mold (mold)
3 Cylinder block (cast product)
4 Cavity 21 Defect position prediction device 22 Control device 23 Input device 24 Output device 25 Storage device 26 Calculation device (Mold model creation means, injection condition setting means, molten metal flow analysis means, gas pressure threshold value calculation means, defect position prediction means)
S1 mold model creation step S2 molten metal flow analysis step S3 gas pressure threshold value calculation step S4 defect precursor generation determination step S5 molten metal inflow determination step S6 movement distance calculation step S7 movement direction determination step S8 one element movement distance calculation step S9 movement distance determination Step S10 Iterative movement calculation step S11 Defect precursor position setting step S12 Iterative calculation step S13 Defect position determination step SI Defect position prediction step SII Movement calculation step R _i Move distance Q _i Move distance of one element B Defect precursor

Claims (10)

A method for predicting a defect position of a casting in pressure casting in which a molten metal is injected into a mold under pressure,
A mold model creating step of creating a mold model obtained by dividing the mold cavity into a plurality of elements,
For the mold model, under the same casting conditions as in the pressure casting, perform a melt flow analysis for each predetermined time step from the start of filling of the molten metal to the end of filling, and the gas pressure of the plurality of elements in each time step. A molten metal flow analysis step of calculating a state quantity of the plurality of elements including the flow velocity of the molten metal,
A gas pressure threshold value calculating step of calculating a threshold value of the gas pressure in the plurality of elements based on a result of the molten metal flow analysis and a defect occurrence condition to be predicted in the casting.
A defect position prediction step of predicting a defect position at the end of the filling of the molten metal based on the gas pressure, the flow velocity, and the gas pressure threshold calculated in the molten metal flow analysis,
The defect position prediction step includes:
In the result of the molten metal flow analysis at an arbitrary time step, a defect precursor generation determination step of determining that a defect precursor has occurred in an element in which the gas pressure exceeds the threshold,
A molten metal inflow determining step of determining whether the molten metal has flowed into the element determined to have generated the defect precursor,
When it is determined that the molten metal has flowed into the element, the movement of the defect precursor is calculated from the flow velocity of the molten metal flowing into the element and / or an element around the element to determine a defect movement position. Moving calculation process
A defect precursor position setting step of setting the defect movement position obtained by the movement calculation as a position of a defect precursor in the flow analysis of the next time step of the arbitrary time step,
Until the completion of the filling of the molten metal, by repeating from the defect precursor generation determination step to the defect precursor position setting step, a defect position determining step of determining the defect position at the end of the filling of the molten metal,
In the gas pressure threshold value calculation step, the gas pressure threshold value is calculated in consideration of information on residual air, lubricant volatile gas and release agent volatile gas generated under the casting conditions of the pressure casting. Defect location prediction method for castings. In claim 1,
The above movement calculation step
In the element in which the defect precursor is generated and the molten metal is determined to have flowed, a moving distance calculating step of calculating a moving distance of the defect precursor from the flow velocity of the molten metal flowing into the element,
A moving direction determining step of determining a moving direction of the defect precursor from the flow rate of the molten metal flowing into the element and / or an element around the element;
A one element moving distance calculating step of calculating a moving distance of one element based on the size of each element and the moving direction determined in the moving direction determining step;
A moving distance determining step of determining a moving destination element of the defect precursor when it is determined that the moving distance calculated in the moving distance calculating step exceeds the moving distance of the one element. A defect position predicting method for a casting. In claim 1 or claim 2,
In the gas pressure threshold value calculation step, the defect occurrence condition includes information on a defect size,
A defect position prediction method for a casting, wherein the defect position prediction step predicts, in addition to the defect position, a defect size at the end of filling the molten metal. A device for predicting a defect position of a casting in pressure casting in which a molten metal is injected into a mold under pressure,
A mold model creating means for creating a mold model obtained by dividing the mold cavity into a plurality of elements,
For the mold model, under the same casting conditions as in the pressure casting, perform a melt flow analysis for each predetermined time step from the start of filling of the molten metal to the end of filling, and the gas pressure of the plurality of elements in each time step. Molten metal flow analysis means for calculating a state quantity of the plurality of elements including the flow rate of the molten metal,
Gas pressure threshold value calculation means for calculating a threshold value of the gas pressure in the plurality of elements based on a result of the molten metal flow analysis and a defect occurrence condition to be predicted in the casting.
Defect position prediction means for predicting a defect position at the end of filling of the molten metal based on the gas pressure, the flow velocity, and the gas pressure threshold calculated in the molten metal flow analysis,
The defect position prediction means includes:
In the result of the molten metal flow analysis at an arbitrary time step, it is determined that a defect precursor has occurred in an element in which the gas pressure exceeds the threshold,
Determine whether the molten metal has flowed into the element determined that the defect precursor has occurred,
When it is determined that the molten metal has flowed into the element, the movement of the defect precursor is calculated from the flow velocity of the molten metal flowing into the element and / or an element around the element to determine a defect movement position. And
The defect movement position obtained by the movement calculation is set as the position of the defect precursor in the flow analysis of the next time step of the arbitrary time step,
Until the filling of the molten metal is completed, the defect position at the time of completing the filling of the molten metal is determined by repeating the determination of the occurrence of the defective precursor, the determination of the inflow of the molten metal, the calculation of the movement, and the setting of the position of the defective precursor. To do
The gas pressure threshold value calculation means calculates the gas pressure threshold value in consideration of information on residual air, lubricant volatile gas, and release agent volatile gas generated under the casting conditions of the pressure casting. Defect position prediction device for castings. In claim 4,
The defect position predicting means calculates the movement as:
In the element where it is determined that the molten metal has flowed while the defect precursor has been generated, the moving distance of the defect precursor is calculated from the flow velocity of the molten metal flowing into the element,
The moving direction of the defect precursor is determined from the flow rate of the molten metal flowing into the element and / or an element around the element,
A movement distance for one element is calculated based on the size of each element and the movement direction,
When the moving distance of the defect precursor is determined to exceed the moving distance of one element, the element to which the defect precursor is moved is determined. apparatus. In claim 4 or claim 5,
The defect occurrence conditions include information on defect size,
The defect position estimating means for estimating a defect size at the end of filling of the molten metal in addition to the defect position. A program for predicting a defect position of a casting in pressure casting in which a molten metal is injected into a mold under pressure,
A mold model creating step of creating a mold model obtained by dividing the mold cavity into a plurality of elements,
For the mold model, under the same casting conditions as in the pressure casting, perform a melt flow analysis for each predetermined time step from the start of filling of the molten metal to the end of filling, and the gas pressure of the plurality of elements in each time step. A molten metal flow analysis step of calculating a state quantity of the plurality of elements including the flow velocity of the molten metal,
A gas pressure threshold value calculating step of calculating a threshold value of the gas pressure in the plurality of elements based on a result of the molten metal flow analysis and a defect occurrence condition to be predicted in the casting.
A defect position prediction step of predicting a defect position at the end of the filling of the molten metal based on the gas pressure, the flow velocity, and the gas pressure threshold calculated in the molten metal flow analysis,
The defect position prediction step includes:
In the result of the molten metal flow analysis at an arbitrary time step, a defect precursor generation determination step of determining that a defect precursor has occurred in an element in which the gas pressure exceeds the threshold,
A molten metal inflow determining step of determining whether the molten metal has flowed into the element determined to have generated the defect precursor,
When it is determined that the molten metal has flowed into the element, the movement of the defect precursor is calculated from the flow velocity of the molten metal flowing into the element and / or an element around the element to determine a defect movement position. Moving calculation process
A defect precursor position setting step of setting the defect movement position obtained by the movement calculation as a position of a defect precursor in the flow analysis of the next time step of the arbitrary time step,
Until the completion of the filling of the molten metal, by repeating from the defect precursor generation determination step to the defect precursor position setting step, a defect position determining step of determining the defect position at the end of the filling of the molten metal,
In the gas pressure threshold value calculation step, the gas pressure threshold value is calculated in consideration of information on residual air, lubricant volatile gas and release agent volatile gas generated under the casting conditions of the pressure casting. Defect location prediction program for castings. In claim 7,
The above movement calculation step
In the element in which the defect precursor is generated and the molten metal is determined to have flowed, a moving distance calculating step of calculating a moving distance of the defect precursor from the flow velocity of the molten metal flowing into the element,
A moving direction determining step of determining a moving direction of the defect precursor from the flow rate of the molten metal flowing into the element and / or an element around the element;
A one element moving distance calculating step of calculating a moving distance of one element based on the size of each element and the moving direction determined in the moving direction determining step;
A moving distance determining step of determining a moving destination element of the defect precursor when it is determined that the moving distance calculated in the moving distance calculating step exceeds the moving distance of the one element. A defect position prediction program for a casting. In claim 7 or claim 8,
In the gas pressure threshold value calculation step, the defect occurrence condition includes information on a defect size,
The defect position prediction step predicts a defect size at the time of completion of the filling of the molten metal, in addition to the defect position.   A recording medium on which the program for predicting a defect position of a casting according to any one of claims 7 to 9 is recorded.

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