Method and apparatus for analyzing shrinkage cracks

Abstract

To quantitatively analyzing the influence degree of shrinkage cracks to occur on a casting and determine, based on the relevant influence degree, whether or not shrinkage cracks can be prevented from occurring by changing conditions of casting for a casting concerned.SOLUTION: A method for analyzing shrinkage cracks, adapted to carry out predetermined analysis using a metal mold model having a cavity divided into a plurality of elements, includes to execute: a maximum principal-stress calculating step (step S101) of calculating a maximum principal stress on elements; a shrinkage-crack occurrence predicting step (step S102) of predicting that shrinkage cracks occur on a casting if the maximum principal stress exceeds a first threshold T1; and an area calculating step (step S201) of preparing, for a casting on which shrinkage cracks are predicted to occur, a two-dimensional graph showing a relationship between the maximum principal stress and the first threshold T1 in a temperature range in a solid-liquid coexistence region and its vicinity and calculates an area S of a region as determined at least by a maximum principal-stress curve and a first threshold curve.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a shrinkage crack analysis method and a shrinkage crack analysis device. [Background technology]

[0002] Shrinkage cracks are one of the defects that occur in castings. Shrinkage cracks occur when the stress generated by thermal contraction of the molten metal that forms the casting exceeds the fracture stress of the casting, and the occurrence of shrinkage cracks leads to a decrease in product yield. For this reason, methods have traditionally been used to predict the occurrence of shrinkage cracks in castings.

[0003] For example, Patent Document 1 listed below discloses a technology for determining whether or not cracks have occurred in an element to be evaluated by performing a melt flow analysis using a mold model in which the cavity in the mold is divided into multiple elements, and comparing the integral value of the flow velocity calculated based on the flow velocity of the molten metal in the element to be evaluated with a predetermined evaluation value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-194414 Summary of the Invention [Problem to be solved by the invention]

[0005] However, although the technology disclosed in Patent Document 1 can determine whether or not a casting will develop shrinkage cracks, it cannot analyze what measures should be taken to prevent the development of shrinkage cracks in a casting predicted to develop shrinkage cracks. In other words, it cannot determine whether the development of shrinkage cracks can be prevented by changing the casting conditions, such as the casting plan or the injection speed of the molten metal, in a casting predicted to develop shrinkage cracks, or whether the development of shrinkage cracks can be prevented without changing the design, such as the shape of the cavity.

[0006] The present invention has been made in consideration of the problems existing in the conventional art described above, and an object of the present invention is to provide a method and an apparatus for quantitatively analyzing the degree of influence of shrinkage cracks occurring in a casting, and determining, based on the degree of influence, whether or not the occurrence of shrinkage cracks can be prevented for a target casting by changing the casting conditions. [Means for solving the problem]

[0007] The present invention will be described below. In order to facilitate understanding of the present invention, reference numbers in the accompanying drawings are added in parentheses, but the present invention is not limited to the illustrated forms.

[0008] The shrinkage crack analysis method according to the present invention is a method for quantitatively analyzing the influence of shrinkage cracks that occur in a casting formed by pouring molten metal into a cavity formed in a pair of openable and closable dies and solidifying the molten metal, and includes a maximum principal stress calculation step (step S101) of performing a predetermined analysis using a die model formed by dividing the cavity into a plurality of elements and calculating maximum principal stresses in the elements; and a shrinkage crack occurrence prediction step ( and an area calculation step (step S201) of creating a two-dimensional graph showing the relationship between the maximum principal stress and the first threshold value (T1) in a solid-liquid coexistence region and a temperature range in the vicinity thereof for a shrinkage crack predicted casting, which is the casting predicted to have shrinkage cracks in the shrinkage crack prediction step (step S102), and calculating an area (S) of a region determined by at least a maximum principal stress curve showing a temperature change of the maximum principal stress and a first threshold value curve showing a temperature change of the first threshold value (T1).

[0009] Furthermore, in the shrinkage crack analysis method according to the present invention, a determination step (step S202) can be executed in which, if the area (S) of the region obtained in the area calculation step (step S201) does not exceed a second threshold value (T2), which is a predetermined threshold value, it is determined that the occurrence of shrinkage cracks in the shrinkage crack occurrence predicted casting can be prevented by changing the casting conditions of the shrinkage crack occurrence predicted casting, and, if the area (S) of the region exceeds the second threshold value (T2), it is determined that the occurrence of shrinkage cracks in the shrinkage crack occurrence predicted casting cannot be prevented even if the casting conditions of the shrinkage crack occurrence predicted casting are changed.

[0010] In addition, in the shrinkage crack analysis method according to the present invention, the area (S) of the region may be an area of ​​a region surrounded by the maximum principal stress curve, the first threshold curve, and a line determined by the solidus temperature of the casting.

[0011] Furthermore, in the shrinkage crack analysis method according to the present invention, when, among past measurement data of the casting, measurement data in which the maximum principal stress is highest near the solidus temperature of the casting in which shrinkage cracks have not occurred is defined as first data, measurement data in which the maximum principal stress is lowest near the solidus temperature of the casting in which shrinkage cracks have occurred is defined as second data, and maximum nominal stress in a solid-liquid coexistence region of the casting and a temperature range in the vicinity of that region is defined as third data, the first threshold value (T1) can be determined based on at least one of the first data, the second data, and the third data.

[0012] Furthermore, in the shrinkage crack analysis method according to the present invention, the predetermined analysis executed in the maximum principal stress calculation step (step S101) can be a solidification analysis and a stress analysis of the molten metal.

[0013] A shrinkage crack analysis device (10) according to the present invention quantitatively analyzes the influence of shrinkage cracks that occur in a casting formed by pouring molten metal into a cavity formed in a pair of openable and closable molds and solidifying the molten metal, and includes a maximum principal stress calculation unit (11) that performs a predetermined analysis using a mold model formed by dividing the cavity into a plurality of elements and calculates maximum principal stress in the elements, and a maximum principal stress calculation unit (12) that predicts that shrinkage cracks will occur in the casting when the maximum principal stress exceeds a first threshold (T1), which is a predetermined threshold. and an area calculation unit (13) that creates a two-dimensional graph showing the relationship between the maximum principal stress and the first threshold value (T1) in a solid-liquid coexistence region and a temperature range in the vicinity thereof for a shrinkage crack predicted casting, which is the casting in which shrinkage cracks are predicted to occur by the shrinkage crack prediction unit (12), and calculates an area (S) of a region determined by at least a maximum principal stress curve that shows a temperature change of the maximum principal stress and a first threshold value curve that shows a temperature change of the first threshold value (T1). [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a method and an apparatus for quantitatively analyzing the influence of shrinkage cracks occurring in a casting and determining, based on the influence, whether or not the occurrence of shrinkage cracks in a target casting can be prevented by changing the casting conditions. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a functional block diagram of a shrinkage crack analysis device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a hardware configuration diagram of a shrinkage crack analysis device according to an embodiment of the present invention. [Figure 3] 1 is a flowchart of a shrinkage crack analysis method according to the present embodiment. [Figure 4] FIG. 1 is a schematic diagram of a casting used in a shrinkage crack analysis method according to an application example. [Figure 5] 10 is a graph showing the relationship between the maximum principal stress of a casting used in a shrinkage crack analysis method according to an application example and the temperature of a molten metal. [Figure 6] FIG. 10 is a diagram showing a method for setting a second threshold value in a shrinkage crack analysis method according to an application example. [Figure 7] 1 is a schematic diagram showing the area of ​​a region surrounded by a maximum principal stress curve, a first threshold curve, and a straight line determined by the solidus temperature of a casting according to an application example. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] Preferred embodiments for carrying out the present invention will be described below with reference to the drawings. Note that the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0017] [Sinkage crack analysis device] First, the configuration of a shrinkage crack analysis device 10 according to this embodiment will be described with reference to Fig. 1 and Fig. 2. Here, Fig. 1 is a functional block diagram of the shrinkage crack analysis device 10 according to this embodiment, and Fig. 2 is a hardware configuration diagram of the shrinkage crack analysis device 10 according to this embodiment.

[0018] As shown in FIG. 1, a shrinkage crack analysis device 10 according to this embodiment includes a maximum principal stress calculation unit 11, a shrinkage crack occurrence prediction unit 12, an area calculation unit 13, and a determination unit 14.

[0019] The maximum principal stress calculation unit 11 calculates the maximum principal stress in the elements of the mold model by performing a predetermined analysis using the mold model. Here, the mold model is a mold mesh model obtained by dividing a cavity formed in a pair of openable and closable molds into a plurality of elements, and is created from design data of the casting, for example, three-dimensional CAD (Computer Aided Design) data. The division size and element shape of the mold model can be determined arbitrarily.

[0020] In the shrinkage crack analysis device 10 according to the present embodiment, a predetermined analysis is performed based on the casting conditions to perform solidification analysis of the molten metal and stress analysis, thereby calculating the maximum principal stress in the elements of the mold model. Here, the casting conditions may include not only information about the temperature and injection speed of the molten metal injected into the cavity and the composition of the molten metal, but also information about the casting plan, such as the design of the runner and feeder. Note that the shrinkage crack analysis device according to the present invention can freely select an analysis method other than solidification analysis of the molten metal and stress analysis, as long as it can calculate the maximum principal stress.

[0021] The shrinkage crack occurrence prediction unit 12 predicts the occurrence of shrinkage cracks in the casting when the maximum principal stress calculated by the maximum principal stress calculation unit 11 exceeds a predetermined threshold value, i.e., a first threshold value T1. In the shrinkage crack analysis device 10 according to this embodiment, the first threshold value T1 can be determined based on at least one of the following data: first data, which is the measurement data showing the highest maximum principal stress near the solidus temperature of a casting in which shrinkage cracks did not occur; second data, which is the measurement data showing the lowest maximum principal stress near the solidus temperature of a casting in which shrinkage cracks occurred; and third data, which is the maximum nominal stress in the solid-liquid coexistence region of the casting and its surrounding temperature range. For example, the first threshold value T1 can be set to the average value of the maximum principal stress of the first data and the maximum principal stress of the second data near the solidus temperature of the casting. Alternatively, the third data can be set to the first threshold value T1.

[0022] The area calculation unit 13 creates a two-dimensional graph showing the relationship between the maximum principal stress and the first threshold value T1 in the solid-liquid coexistence region and a temperature range nearby, for a casting predicted by the shrinkage crack occurrence prediction unit 12 to have shrinkage cracks, i.e., a shrinkage crack predicted casting, and calculates the area S of a region defined by at least a maximum principal stress curve representing a temperature change of the maximum principal stress and a first threshold value curve representing a temperature change of the first threshold value T1. In the shrinkage crack analysis device 10 according to this embodiment, the area S of the region can be defined as the area of ​​a region surrounded by the maximum principal stress curve, the first threshold value curve, and a line defined by the solidus temperature of the casting.

[0023] If the area S of the region obtained by the area calculation unit 13 does not exceed a predetermined second threshold T2, the determination unit 14 determines that the occurrence of shrinkage cracks in the shrinkage crack-predicted cast product can be prevented by changing the casting conditions for the shrinkage crack-predicted cast product. If the area S of the region exceeds the second threshold T2, the determination unit 14 determines that the occurrence of shrinkage cracks in the shrinkage crack-predicted cast product cannot be prevented even by changing the casting conditions for the shrinkage crack-predicted cast product, and that a change in the casting design is necessary. In the shrinkage crack analysis device 10 according to this embodiment, the second threshold T2 can be set using past measurement results for cast products with the same casting conditions and shape. The second threshold T2 may be any value greater than the first threshold T1, and can also be set automatically by multiplying the first threshold T1 by an arbitrary coefficient. Furthermore, the second threshold T2 can also be determined based on the operator's experience, etc.

[0024] 2 shows a hardware configuration diagram of the shrinkage crack analysis device 10 according to this embodiment. The shrinkage crack analysis device 10 is physically implemented in a computer 40, and is configured with an arithmetic unit 41, an input unit 42, a main memory unit 43, an auxiliary memory unit 44, and an output unit 45.

[0025] The operation of each unit in the shrinkage crack analysis device 10 is stored in the form of a program in an auxiliary storage device 44, which is composed of a hard disk drive (HDD) and a solid state drive (SSD). The arithmetic unit 41, which is composed of a central processing unit (CPU) and the like, reads the program from the auxiliary storage device 44, loads it into a main storage device 43, which is composed of a random access memory (RAM) and a read only memory (ROM), and executes the processing of each unit in the shrinkage crack analysis device 10 according to the program. The input device 42, which is composed of a mouse, a keyboard, and the like, can input data related to a mold model and casting conditions to the maximum principal stress calculation unit 11 in the shrinkage crack analysis device 10. The output device 45, which is composed of a display and the like, can display the prediction results of the shrinkage crack occurrence prediction unit 12 and the judgment results output by the judgment unit 14. Note that although the shrinkage crack analysis device 10 according to this embodiment is configured on a single computer 40, it may be configured on multiple computers.

[0026] The configuration of the shrinkage crack analysis device 10 according to this embodiment has been described above with reference to Fig. 1 and Fig. 2. Next, the shrinkage crack analysis method according to this embodiment will be described with reference to Fig. 3. Here, Fig. 3 is a flowchart of the shrinkage crack analysis method according to this embodiment.

[0027] [Shrinkage crack analysis method] As shown in FIG. 3 , the shrinkage crack analysis method according to this embodiment includes a maximum principal stress calculation step (step S101), a shrinkage crack occurrence prediction step (step S102), an area calculation step (step S201), a determination step (step S202), a step (step S211) of notifying the designer that a design change of the casting product is necessary based on the determination result obtained in the determination step (step S202), and a step (step S212) of notifying the designer that the occurrence of shrinkage cracks can be prevented by changing the casting conditions of the casting product based on the determination result obtained in the determination step (step S202), and each step is executed by the shrinkage crack analysis device 10.

[0028] In the shrinkage crack analysis method according to the present invention, first, a maximum principal stress calculation step (step S101) is executed. In the maximum principal stress calculation step (step S101), a predetermined analysis is performed in the maximum principal stress calculation unit 11 based on information on a mold model of a casting product and casting conditions input to the maximum principal stress calculation unit 11 using the input device 42, and the maximum principal stress in the cavity element is calculated.

[0029] Next, in the shrinkage crack occurrence prediction step (step S102), the shrinkage crack occurrence prediction unit 12 compares the maximum principal stress calculated in the maximum principal stress calculation step (step S101) with a first threshold value T1, which is a predetermined threshold value. Here, if the maximum principal stress does not exceed the first threshold value T1, the process proceeds to No in step S102. That is, if the maximum principal stress does not exceed the first threshold value T1, it is predicted that shrinkage cracks will not occur in the casting, and the shrinkage crack analysis method according to this embodiment is terminated. On the other hand, if the maximum principal stress exceeds the first threshold value T1, the process proceeds to Yes in step S102. That is, if the maximum principal stress exceeds the first threshold value T1, it is predicted that shrinkage cracks will occur in the casting.

[0030] Next, an area calculation step (step S201) is performed on a casting determined to have a maximum principal stress exceeding the first threshold value T1 in the shrinkage crack occurrence prediction step (step S102), i.e., a shrinkage crack prediction casting. In the area calculation step (step S201), the area calculation unit 13 creates a two-dimensional graph showing the relationship between the maximum principal stress and the first threshold value T1 in the solid-liquid coexistence region and a temperature range nearby for the shrinkage crack prediction casting, and calculates at least the area S of a region determined by the maximum principal stress curve representing the temperature change of the maximum principal stress and the first threshold value curve representing the temperature change of the first threshold value T1.

[0031] Next, in the determination step (step S202), the determination unit 14 compares the area S of the region obtained in the area calculation step (step S201) with a second threshold T2, which is a predetermined threshold. If the area S of the region exceeds the second threshold T2, the process proceeds to Yes in step S202. That is, if the area S of the region exceeds the second threshold T2, it is determined that the occurrence of shrinkage cracks in the shrinkage crack-predicted cast product cannot be prevented even if the casting conditions for the shrinkage crack-predicted cast product are changed, and a message to the effect that a change in the design of the cast product is necessary is displayed on the output device 45 (step S211). On the other hand, if the area S of the region does not exceed the second threshold T2, the process proceeds to No in step S202. That is, if the area S of the region does not exceed the second threshold T2, it is determined that the occurrence of shrinkage cracks in the shrinkage crack-predicted cast product can be prevented by changing the casting conditions for the shrinkage crack-predicted cast product, and a message to the effect that the occurrence of shrinkage cracks can be prevented by changing the casting conditions for the cast product is displayed on the output device 45 (step S212). Through the above steps, the shrinkage crack analysis method according to this embodiment is completed.

[0032] By executing the above-described shrinkage crack analysis method, the shrinkage crack analysis device 10 of this embodiment can quantitatively analyze the impact of shrinkage cracks on a casting. Specifically, the shrinkage crack occurrence prediction step (step S102) not only predicts whether or not a casting will develop shrinkage cracks, but also performs an area calculation step (step S201) on the shrinkage crack-predicted casting to create a two-dimensional graph showing the relationship between the maximum principal stress and the first threshold T1 in the solid-liquid coexistence region of the shrinkage crack-predicted casting and the temperature range surrounding it. The area S of the region determined by at least the maximum principal stress curve and the first threshold curve can be calculated, thereby quantitatively analyzing the impact of shrinkage cracks. As a result, the designer can be informed of measures to be taken on the shrinkage crack-predicted casting based on the quantified impact, enabling more efficient casting design.

[0033] The shrinkage crack analysis method according to this embodiment has been described above using FIG. 3. Next, application examples of the shrinkage crack analysis method according to this embodiment will be described using FIGS. 4 to 7. Here, FIG. 4 is a schematic diagram of a casting 20 used in the shrinkage crack analysis method according to an application example. FIG. 5 is a graph showing the relationship between the maximum principal stress and the molten metal temperature of the casting 20 used in the shrinkage crack analysis method according to an application example. FIG. 6 is a diagram showing a method for setting the second threshold value T2 in the shrinkage crack analysis method according to an application example. Furthermore, FIG. 7 is a schematic diagram showing the area S of a region surrounded by the maximum principal stress curve, the first threshold value curve, and a line determined by the solidus temperature of the casting 20′ in a casting 20′ according to an application example.

[0034] [Application example] As shown in FIG. 4, the casting 20 is a die-cast product formed by injecting molten metal into a cavity formed in a pair of openable and closable molds and solidifying the molten metal, and is molded from ADC12, an aluminum alloy.

[0035] Next, a first threshold T1 in the shrinkage crack occurrence prediction step (step S102) was set using the data shown in Fig. 5. That is, among past measurement data of the casting 20, the measurement data with the highest maximum principal stress near the solidus temperature of the casting 20 in which shrinkage cracks did not occur was defined as first data, the measurement data with the lowest maximum principal stress near the solidus temperature of the casting 20 in which shrinkage cracks occurred was defined as second data, and the maximum nominal stress in the solid-liquid coexistence region of the casting 20 and its neighboring temperature range was defined as third data. The first threshold T1 was set taking into consideration the first, second, and third data. Specifically, a curve passing through values ​​set in consideration of the first, second, and third data for each temperature set in the temperature range from the solid-liquid coexistence region to the solidus temperature of the casting 20 was defined as a first threshold curve, and a value on the first threshold curve near the solidus temperature of the casting 20 was defined as the first threshold T1.

[0036] Furthermore, based on past measurement results of the casting 20, for those in which the maximum principal stress exceeded the first threshold value T1 (i.e., for shrinkage crack-predictable castings), the area S of the region enclosed by the maximum principal stress curve for each shrinkage crack-predictable casting, the first threshold value curve, and a line determined by the solidus temperature of the casting 20 was calculated. The casting conditions for each shrinkage crack-predictable casting were then changed to investigate whether or not shrinkage cracks would occur in the shrinkage crack-predictable castings. As shown in FIG. 6 , when the value of the area S of the region did not exceed a predetermined value in the past measurement results of the shrinkage crack-predictable castings, changing the casting conditions for the shrinkage crack-predictable castings prevented the occurrence of shrinkage cracks in the shrinkage crack-predictable castings. On the other hand, when the area S of the region exceeded the predetermined value, changing the casting conditions for the shrinkage crack-predictable castings did not prevent the occurrence of shrinkage cracks in the shrinkage crack-predictable castings. Therefore, in this application example, a second threshold value T2 was set as shown in FIG. 6 based on past measurement results of the shrinkage crack-predictable castings.

[0037] Based on the above, the first threshold value T1 and the second threshold value T2 were set for the casting 20. Next, the shrinkage crack analysis method according to the present invention was performed on the casting 20', whose presence or absence of shrinkage cracks was unknown. The shape and casting conditions of the casting 20' were the same as those of the casting 20.

[0038] First, in a maximum principal stress calculation step (step S101), the maximum principal stress in each element of the casting 20' was calculated. Next, in a shrinkage crack occurrence prediction step (step S102), the maximum principal stress in each element of the casting 20' was compared with the first threshold value T1 calculated above. As a result, the maximum principal stress exceeded the first threshold value T1. Therefore, the process proceeded to an area calculation step (step S201).

[0039] In the area calculation step (step S201), as shown in FIG. 7, the area S of the region enclosed by the maximum principal stress curve, the first threshold curve, and a line determined by the solidus temperature of the casting 20′ was calculated for the casting 20′. Next, in the determination step (step S202), the area S of the region was compared with the second threshold T2 calculated above. Since the area S of the region did not exceed the second threshold T2, the output device 45 of the shrinkage crack analysis device 10 displayed a message indicating that the occurrence of shrinkage cracks could be prevented by changing the casting conditions (step S212). Based on this result, the casting conditions, such as the casting plan for the casting 20′, were changed, and it was confirmed that shrinkage cracks would not occur in the casting 20′.

[0040] As described above, the shrinkage crack analysis method according to the present invention can quantitatively analyze not only whether or not a shrinkage crack occurs in a target casting, but also the influence of the shrinkage crack using the area S of the region. Furthermore, it can provide a method for determining whether or not the occurrence of shrinkage cracks can be prevented by changing the casting conditions, etc., based on the influence.

[0041] While the preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the scope described in the above embodiments. Various modifications and improvements can be made to the above embodiments.

[0042] For example, in the above-mentioned application example, the castings 20, 20' are formed from ADC12, which is an aluminum alloy, but in the present invention, various alloys can be used for the castings.

[0043] For example, the castings used in the present invention can be made from aluminum alloys such as RMH-TMH and RX-10 manufactured by Ryobi Co., Ltd.

[0044] It is clear from the claims that such modifications and improvements may also be included within the technical scope of the present invention. [Explanation of symbols]

[0045] 10: shrinkage crack analysis device, 11: maximum principal stress calculation unit, 12: shrinkage crack occurrence prediction unit, 13: area calculation unit, 14: judgment unit, 20, 20': casting, 40: computer, 41: calculation unit, 42: input unit, 43: main memory device, 44: auxiliary memory device, 45: output device, T1: first threshold value, T2: second threshold value, S: area of ​​region.

Claims

1. A method for analyzing a shrinkage crack quantitatively to analyze the influence of a shrinkage crack occurring in a casting formed by injecting molten metal into a cavity formed in a pair of openable and closable molds and solidifying the molten metal, a maximum principal stress calculation step of performing a predetermined analysis using a mold model obtained by dividing the cavity into a plurality of elements and calculating a maximum principal stress in the elements; a shrinkage crack occurrence prediction step of predicting that a shrinkage crack will occur in the casting when the maximum principal stress exceeds a first threshold value that is a predetermined threshold value; an area calculation step of creating a two-dimensional graph showing a relationship between the maximum principal stress and the first threshold value in a solid-liquid coexistence region and a temperature range in the vicinity thereof for a shrinkage crack predicted casting, which is the casting predicted to have shrinkage cracks in the shrinkage crack prediction step, and calculating an area of ​​a region determined by at least a maximum principal stress curve showing a temperature change of the maximum principal stress and a first threshold value curve showing a temperature change of the first threshold value; A shrinkage crack analysis method characterized by executing the above steps.

2. The shrinkage crack analysis method according to claim 1, a determining step of determining that occurrence of shrinkage cracks in the shrinkage crack occurrence predicted casting product can be prevented by changing casting conditions for the shrinkage crack occurrence predicted casting product, when the area of ​​the region obtained in the area calculation step does not exceed a second threshold value that is a predetermined threshold value, and determining that occurrence of shrinkage cracks in the shrinkage crack occurrence predicted casting product cannot be prevented even by changing casting conditions for the shrinkage crack occurrence predicted casting product, when the area of ​​the region exceeds the second threshold value.

3. The shrinkage crack analysis method according to claim 1 or 2, the area of ​​the region is the area of ​​a region surrounded by the maximum principal stress curve, the first threshold curve, and a straight line determined by the solidus temperature of the casting.

4. The shrinkage crack analysis method according to claim 1 or 2, Among past measurement data of the casting, measurement data in which the maximum principal stress is highest near the solidus temperature of the casting in which no shrinkage cracks have occurred is designated as first data; The measurement data in which the maximum principal stress is lowest near the solidus temperature of the casting in which shrinkage cracks have occurred is called second data; When the maximum nominal stress in the solid-liquid coexistence region of the casting and the temperature range therearound is defined as third data, The method for analyzing a shrinkage crack, wherein the first threshold value is determined based on at least one of the first data, the second data, and the third data.

5. The shrinkage crack analysis method according to claim 1 or 2, The shrinkage crack analysis method, wherein the predetermined analysis executed in the maximum principal stress calculation step is a solidification analysis and a stress analysis of the molten metal.

6. A shrinkage crack analysis device that quantitatively analyzes the influence of shrinkage cracks that occur in a casting formed by injecting molten metal into a cavity formed in a pair of openable and closable molds and solidifying the molten metal, a maximum principal stress calculation unit that performs a predetermined analysis using a mold model obtained by dividing the cavity into a plurality of elements and calculates a maximum principal stress in the elements; a shrinkage crack occurrence prediction unit that predicts that a shrinkage crack will occur in the casting when the maximum principal stress exceeds a first threshold value that is a predetermined threshold value; an area calculation unit that creates a two-dimensional graph showing a relationship between the maximum principal stress and the first threshold value in a solid-liquid coexistence region and a temperature range in the vicinity thereof for a shrinkage crack predicted casting, which is the casting predicted by the shrinkage crack prediction unit to have shrinkage cracks, and calculates an area of ​​a region determined by at least a maximum principal stress curve that represents a temperature change of the maximum principal stress and a first threshold value curve that represents a temperature change of the first threshold value; A shrinkage crack analysis device comprising:

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