Analysis program and casting analysis method

Abstract

Since the multiple layers of mold meshes 15 arranged along the cavity 120 and the cooling structure 121 of the mold 12 are set to the bond-prohibited mesh, the entire cavity 120 and the cooling structure 121 can be covered with the multiple layers of bond-prohibited meshes. Then, the multiple mold meshes 15 excluding the bond-prohibited meshes are bonded to the primary bonded mesh 150, so that multiple layers of relatively fine mold meshes 15 can be left in the heat exchange regions R1 and R2, while the coarse primary bonded mesh 150 can be arranged in the region away from them. Therefore, the heat transfer calculation in the heat exchange regions R1 and R2 can be performed accurately, and the load of the heat transfer calculation in the region away from them can be reduced. Therefore, the temperature change of the mold 12 can be analyzed accurately in a short time.

Description

[Technical field]

[0001] The present invention relates to an analysis program and a casting analysis method, and more particularly to an analysis program and a casting analysis method that can analyze temperature changes in a mold with high accuracy in a short period of time. [Background technology]

[0002] There is a known technique for predicting in advance whether or not a casting defect will occur in a casting by dividing a model of a mold into multiple meshes (elements) and analyzing the flow and solidification process of molten metal in the meshes. In order to accurately analyze the flow of molten metal, it is necessary to perform accurate heat transfer calculations in areas with large temperature gradients (hereinafter referred to as "heat exchange areas") near the mold cavity and cooling structure. Dividing the heat exchange area into fine meshes allows accurate heat transfer calculations in the area, but dividing the entire mold into fine meshes increases the total number of meshes and extends the time required for analysis.

[0003] In particular, in recent years, there has been an increasing demand for large-scale casting equipment such as Giga Press and Giga Cast, and if such large molds, in addition to the casting (cavity), are divided into fine meshes, the analysis time becomes extremely long. Therefore, a technology that uses a so-called non-uniform mesh, in which the mesh size is reduced in the heat exchange region of the mold while the mesh size is increased in the region away from the mold, has attracted attention.

[0004] As an example of a technique using this type of non-uniformly divided mesh, Patent Document 1 describes a technique in which a primary mesh is generated for a model of a substrate having copper wiring 50, and then a secondary mesh is generated by leaving the primary mesh including the copper wiring 50 uncombined, while combining the primary mesh that does not include the copper wiring 50. This technique makes it possible to accurately analyze the warpage of the substrate in the region including the copper wiring 50, while reducing the calculation load in the region away from the copper wiring 50. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-050137 A (for example, paragraphs 0023 to 0043, figures 4 to 6) Summary of the Invention [Problem to be solved by the invention]

[0006] In the technology of Patent Document 1 described above, the mesh on the copper wiring 50 or the mesh adjacent to the mesh on the copper wiring 50 is also combined as a secondary mesh (see FIG. 6 of Patent Document 1). When the technology of Patent Document 1 is applied to a model of a mold, the secondary mesh (combined mesh) is also placed in the heat exchange region, making it impossible to perform accurate heat transfer calculations in the region. This causes a problem in that the temperature change of the mold cannot be analyzed with high accuracy.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide an analysis program and a casting analysis method that can analyze temperature changes in a mold accurately in a short period of time. [Means for solving the problem]

[0008] In order to achieve this object, the analysis program and casting analysis method of the present invention cause a computer to execute the following steps: a model generation step of generating an analysis model of a mold having a heat exchange portion consisting of a cavity or a cooling structure; a mesh generation step of generating a plurality of meshes on the analysis model generated in the model generation step; a setting step of setting the meshes that are not to be combined, among the plurality of meshes generated in the mesh generation step, as combination prohibited meshes; a combining step of generating a combined mesh by combining the meshes located on the mold, excluding the combination prohibited meshes set in the setting step, to generate a non-uniformly divided mesh; and a casting analysis step of performing a casting analysis using the non-uniformly divided mesh generated in the combining step, wherein in the setting step, the meshes in a plurality of layers arranged along the heat exchange portion are combined with each other to generate a non-uniformly divided mesh.The mesh has a plurality of layers overlapping in a direction away from the heat exchange portion. By setting the bond prohibition mesh to the bond prohibition mesh, the heat exchange portion is covered with a plurality of layers of the bond prohibition mesh. Effect of the Invention

[0009] According to the analysis program of claim 1 and the casting analysis method of claim 7, a multi-layer mesh arranged along the heat exchange portion of the mold is A mesh having multiple layers overlapping in a direction away from the heat exchange section. Since the method includes a setting step for setting the mesh to a joining prohibition mesh, the entire heat exchange section can be covered with multiple layers of joining prohibition mesh. In the joining step, the meshes on the mold excluding the joining prohibition mesh are joined together, so that multiple layers of relatively fine mesh can be left in the area adjacent to the heat exchange section (hereinafter referred to as the "heat exchange area"), while a coarse joined mesh can be placed in the area away from there. This makes it possible to perform accurate heat transfer calculations in the heat exchange area, while reducing the load of heat transfer calculations in areas away from there. This has the effect of enabling the temperature change of the mold to be analyzed accurately in a short period of time.

[0010] According to the analysis program of claim 2, in addition to the effects of the analysis program of claim 1, in the combining step, a position away from the heat exchange unit is set as a starting point, and combined meshes are generated sequentially from the starting point toward the heat exchange unit, so that even if fine meshes that cannot be combined as combined meshes remain, the fine meshes can be arranged near the heat exchange area. Therefore, there is an effect that the heat transfer calculation in the heat exchange area can be performed accurately, and the load of the heat transfer calculation in the area away from the heat exchange area can be reduced.

[0011] According to the analysis program of claim 3, in addition to the effects of the analysis program of claim 1, the following effects are achieved. In the setting step and the combining step, a combining mesh adjacent to a combining prohibition mesh is set as a combining prohibition mesh, and the combining meshes excluding the combining prohibition mesh are further combined with each other, and the combining mesh can be gradually coarsened with increasing distance from the heat exchange region. This has the effect of enabling accurate heat transfer calculation in the heat exchange region and reducing the load of heat transfer calculation in regions away from the heat exchange region.

[0012] According to the analysis program of claim 4, in addition to the effects of the analysis program of claim 3, in the setting step, the unmergeable meshes that remain unmerge in the combining step are set as merge prohibited meshes, so that it is easy to search for meshes that should be further merged. Therefore, there is an effect that the processing load associated with the search can be reduced.

[0013] According to the analysis program of claim 5, in addition to the effects of the analysis program of claim 1, the following effects are achieved: When a fine mesh and a coarse mesh that is adjacent to the fine mesh and is coarser than the fine mesh are formed into an unequally divided mesh, the following steps are executed in the casting analysis step.

[0014] That is, in the virtual combining step, fine meshes adjacent to a coarse mesh are virtually combined to define a virtual combined mesh, and in the virtual dividing step, the coarse mesh is virtually divided into meshes of the same size as the fine meshes to define virtual divided meshes. In the temperature calculation step, the temperature of the virtual divided mesh is calculated based on the temperatures of the virtual combined mesh and other coarse meshes arranged around the coarse mesh, and in the heat transfer calculation step, heat transfer calculation between those meshes is performed based on the temperatures of the fine mesh and the virtual divided mesh. This makes it possible to perform more accurate heat transfer calculation between those meshes than when heat transfer calculation is simply performed based on the temperatures of the fine mesh and the coarse mesh. This has the effect of allowing the temperature change of the mold to be analyzed with high accuracy.

[0015] According to the analysis program of claim 6, in addition to the effects of the analysis program of claim 1, the following effects are achieved: Kume The method further includes an adjustment step of adjusting the number of meshes based on the number of meshes, and in this adjustment step, the number of meshes is adjusted so as to reduce the number of meshes that cannot be combined in the combining step. This has the effect of preventing the generation of meshes that cannot be combined in the combining step, thereby enabling appropriate generation of non-uniformly divided meshes. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is an external view of an analysis device showing how a casting analysis of molten metal is performed using an analysis model. [Diagram 2] 1A is a schematic diagram of an analytical model showing a state in which mold meshes other than joining prohibited meshes have begun to be joined to a primary joined mesh, and FIG. 1B is a schematic diagram of an analytical model showing a state in which generation of the primary joined mesh has been completed. [Diagram 3] 1(a) is a schematic diagram of an analysis model showing a state in which non-mergeable meshes and parts of primary connected meshes are designated as merge prohibited meshes, and 1(b) is a schematic diagram of an analysis model showing a state in which the primary connected meshes are merged to generate a secondary connected mesh. [Figure 4] FIG. 1 is a schematic diagram of an analysis model showing a state in which a part of an unmergeable mesh or a secondary merged mesh is designated as a merge-prohibited mesh. [Diagram 5] Graph (a) shows the calculation results of the heat flux when four layers of mold mesh are placed on the outside of the molten metal mesh, and graph (b) shows the calculation results of the heat flux when two layers of mold mesh are placed on the outside of the molten metal mesh. [Figure 6] FIG. 13 is an explanatory diagram for a case where heat transfer calculation between a mold mesh and a primary connection mesh is performed in two dimensions. [Figure 7] FIG. 4A is a block diagram showing the electrical configuration of the analysis device, and FIG. 4B is a flowchart showing an analysis process. [Figure 8]13 is a flowchart of a non-uniform division mesh generation process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. First, the overall configuration of an analysis device 1 will be described with reference to Fig. 1. Fig. 1 is an external view of the analysis device 1, showing how an analysis of the flow and solidification of molten metal 11 (hereinafter referred to as "casting analysis") is performed using an analysis model 10. In Fig. 1, the molten metal 11 flowing within a cavity 120 of a mold 12 and a cooling structure 121 of the mold 12 are indicated by dotted hatching.

[0018] As shown in FIG. 1, the analysis device 1 is an information processing device (personal computer) that divides a mold 12 defined in an analysis model 10 into a molten metal mesh 13, a cooling mesh 14, and a mold mesh 15, and analyzes the temperature changes of the molten metal 11 and the mold 12 in each of these meshes 13-15.

[0019] The analytical model 10 is created based on a casting plan read by a user into the analytical device 1. The casting plan is CAD data or the like of a mold 12 designed by a user, and is data on the mold 12 including information such as the shape of a cavity 120, the presence or absence of a cooling structure 121 (e.g., a cooling pipe), and the position and shape of a gate (dam). The analytical device 1 divides the created analytical model 10 into meshes 13-15. Each of these meshes 13-15 is a solid element of a polyhedron (a hexahedron in this embodiment).

[0020] The analysis device 1 is provided with a mouse 2 and a keyboard 3 (input devices) for a user to input the conditions for casting analysis, etc. The analysis conditions input by the user include the above-mentioned data of the mold 12, as well as information on the casting conditions such as the physical properties of the molten metal 11, the initial temperature, and the pouring speed.

[0021] The analysis device 1 performs casting analysis based on analysis conditions input by the user and temperature changes of the molten metal 11 and the mold 12. The analysis device 1 is provided with a display 4 for displaying the analysis results. The results of the casting analysis displayed on the display 4 make it possible to predict in advance locations where casting defects are likely to occur in a casting manufactured with the mold 12 designed by the user.

[0022] The molten metal mesh 13 located above the cavity 120 of the mold 12 is disposed closer to the inside of the cavity 120 than the wall surface of the mold 12, and the cooling mesh 14 located above the cooling structure 121 is disposed closer to the inside of the cooling structure 121 than the boundary between the mold 12 and the cooling structure 121. In other words, the molten metal mesh 13 and the cooling mesh 14 are meshes that do not include (or are in contact with) the edges of the cavity 120 and the cooling structure 121.

[0023] Meanwhile, the meshes located on the mold 12 other than the molten metal mesh 13 and the cooling mesh 14 are the mold mesh 15. Since the temperature gradient is likely to be large in the heat exchange regions R1, R2 (regions hatched with diagonal lines in FIG. 1) near the molten metal mesh 13 (cavity 120) and the cooling mesh 14 (cooling structure 121), in order to accurately predict defects that will occur on the surface of the casting, it is important to perform accurate heat transfer calculations in the mold mesh 15 located in the regions R1, R2. Meanwhile, the temperature gradient is relatively small in regions away from the heat exchange regions R1, R2, and strict heat transfer calculations are not necessary.

[0024] Therefore, in this embodiment, fine mold meshes 15 are generated in the heat exchange regions R1 and R2, while a primary combined mesh 150 is generated outside the mold meshes 15 by combining the mold meshes 15. Further, a secondary combined mesh 151 is generated outside the primary combined mesh 150 by combining the primary combined meshes 150, and a tertiary combined mesh 152 is generated outside the secondary combined mesh 151 by combining the secondary combined meshes 151.

[0025] Since casting analysis is performed using the mold mesh 15 and each connecting mesh 150-152 unequally divided in this manner, heat transfer calculations can be performed with high accuracy in the heat exchange regions R1, R2 where the temperature gradient is large, while the load of heat transfer calculations can be reduced in regions away from these regions where the temperature gradient is small.

[0026] This method of generating an unequally divided mesh will be described with reference to Fig. 2 to Fig. 4. Fig. 2(a) is a schematic diagram of the analysis model 10 showing a state in which the mold mesh 15 other than the joining prohibited meshes has begun to be joined to the primary joining mesh 150, and Fig. 2(b) is a schematic diagram of the analysis model 10 showing a state in which the generation of the primary joining mesh 150 has been completed.

[0027] Fig. 3(a) is a schematic diagram of the analysis model 10 showing a state in which the uncombinable meshes 153 and parts of the primary combination meshes 150 are designated as combination-prohibited meshes, and Fig. 3(b) is a schematic diagram of the analysis model 10 showing a state in which the primary combination meshes 150 are combined to generate the secondary combination mesh 151. Fig. 4 is a schematic diagram of the analysis model 10 showing a state in which the uncombinable meshes 153 and parts of the secondary combination meshes 151 are designated as combination-prohibited meshes.

[0028] As shown in FIG. 2(a), when generating a non-uniformly divided mesh, first, multiple meshes 13-15 of minute size (for example, 0.5 mm on a side) are generated in a model of the mold 12. These meshes 13-15 are all the same size. Next, among the multiple mold meshes 15, multiple layers of mold meshes 15 arranged in heat exchange regions R1 and R2 are designated as merge-prohibited meshes. In FIG. 2(a), the mold meshes 15 designated as merge-prohibited meshes are hatched with dots that are darker (denser) than the molten metal mesh 13 and cooling mesh 14 (this also applies to the following figures).

[0029] In this embodiment, multiple layers of mold meshes 15 are specified as join-prohibited meshes toward the outside of the mold 12 (in the direction away from each mesh 13, 14), including all of the mold meshes 15 adjacent to the molten metal mesh 13 and the cooling mesh 14. Note that the join-prohibited meshes may have a number of layers other than three.

[0030] After designating the mold meshes 15 on the heat exchange regions R1 and R2 as non-merging meshes, 2x2x2 (total of eight) mold meshes 15 are merged to generate a primary merged mesh 150, as shown in the lower right part of FIG. 2(a) (since FIG. 2(a) illustrates the analysis model 10 in two dimensions, the state in which the 2x2 mold meshes 15 are merged is illustrated).

[0031] Thus, in this embodiment, the multiple layers of mold mesh 15 arranged along the cavity 120 of the mold 12 and the cooling structure 121 (molten metal mesh 13 and cooling mesh 14) are set to a bond-inhibiting mesh, so that the entire cavity 120 and cooling structure 121 can be covered with multiple layers of bond-inhibiting mesh.

[0032] Then, excluding these join-prohibited meshes, the multiple mold meshes 15 are joined to the primary join mesh 150, so that multiple layers of relatively fine mold meshes 15 can be left in the heat exchange regions R1 and R2, while the coarse primary join mesh 150 can be placed in regions away from them. This allows accurate heat transfer calculations in the heat exchange regions R1 and R2, while reducing the load of heat transfer calculations in regions away from them. This allows the temperature change of the mold 12 to be analyzed accurately in a short time.

[0033] While the starting point for starting generation of the primary combined mesh 150 can be set arbitrarily, in this embodiment, generation of the primary combined mesh 150 is started from the starting point P (the end of the analysis model 10) which is the furthest from the heat exchange regions R1, R2. More specifically, after a plurality of mold meshes 15 including the mold mesh 15 in contact with the starting point P are combined with the primary combined mesh 150, a plurality of mold meshes 15 in contact with the combined primary combined mesh 150 are combined with the primary combined mesh 150.

[0034] This type of joining process is performed sequentially in the direction from the starting point P toward the heat exchange regions R1 and R2. Fig. 2(a) illustrates an example in which the primary joining meshes 150 are generated sequentially from the starting point P toward the left side (the heat exchange region R1 side), and after joining of the primary joining meshes 150 arranged in one row on the left and right is completed, the mold meshes 15 positioned in the row above (closest to the starting point P) are sequentially joined to the primary joining mesh 150 from the starting point P toward the left side.

[0035] It is also possible to configure the primary combined mesh 150 to be generated sequentially from the starting point P upward. Alternatively, after the primary combined mesh 150 including the starting point P is generated, all of the mold meshes 15 adjacent to the primary combined mesh 150 are simultaneously combined with the primary combined mesh 150, that is, the primary combined mesh 150 is simultaneously generated at two locations, the left side and the upper side, of the primary combined mesh 150 including the starting point P shown in Fig. 2(a). The state after such generation of the primary combined mesh 150 has been completed is shown in Fig. 2(b).

[0036] As shown in Figure 2(b), depending on the number of mold meshes 15 from the end (start point P) of the analysis model 10 to the heat exchange regions R1 and R2, or the number of mold meshes 15 between the heat exchange regions R1 and R2, unconnectable meshes 153 that cannot be connected as the primary connected mesh 150 will remain.

[0037] For this reason, for example, in a configuration in which the primary connected mesh 150 is generated sequentially starting from the heat exchange areas R1, R2 and moving away from the areas R1, R2, unconnectable meshes 153 will remain in positions away from the heat exchange areas R1, R2.

[0038] In contrast, in this embodiment, a position away from the heat exchange regions R1, R2 is set as the starting point P, and the primary combined mesh 150 is sequentially generated from the starting point P toward the heat exchange regions R1, R2, so that a relatively small uncombined mesh 153 (mold mesh 15) is left in the vicinity of the heat exchange regions R1, R2, while a coarse primary combined mesh 150 can be placed in a location away from the heat exchange regions R1, R2. This allows accurate heat transfer calculation in the heat exchange regions R1, R2, and reduces the load of heat transfer calculation in regions away from those regions.

[0039] Here, among the intermediate regions sandwiched between the heat exchange regions R1 and R2, intermediate region R3 located at the upper end side of Fig. 2(b) has two primary connected meshes 150a arranged side by side and a total of four unconnectable meshes 153a sandwiching the two primary connected meshes 150a. Therefore, before the primary connected meshes 150a are generated in this intermediate region R3, 2 x 6 mold meshes 15 exist in two dimensions, so that it is actually possible to form three primary connected meshes 150 in this intermediate region R3.

[0040] However, when such processing is performed, the central positions of the three primary connected meshes 150 generated in the intermediate region R3 are shifted to the left or right from the central positions of other primary connected meshes 150 adjacent to the three primary connected meshes 150 (located on the lower side of FIG. 2(b)). When such a shift occurs, the heat transfer calculation between the meshes becomes complicated.

[0041] In contrast, in this embodiment, the four mold meshes 15 in the intermediate region R3 are left as uncombinable meshes 153a, so the primary combined mesh 150a located in the intermediate region R3 can be vertically aligned with the other primary combined meshes 150 (the center positions of the primary combined meshes 150 are aligned vertically and horizontally). In this way, by aligning all the primary combined meshes 150 in a lattice pattern, it is possible to easily perform heat transfer calculations between those meshes.

[0042] 3(a), the uncombinable meshes 153 that could not be combined to form the primary combined mesh 150 are designated as combination prohibited meshes. In addition, among the primary combined meshes 150, the primary combined meshes 150 adjacent to combination prohibited meshes (the mold mesh 15 and the uncombinable meshes 153) are also designated as combination prohibited meshes.

[0043] In addition, FIG. 3(a) illustrates an example in which a first-order combined mesh 150 adjacent to a combined mesh is designated as a combined mesh. However, a first-order combined mesh 150 of two or more layers may be designated as a combined mesh (the same applies when generating a tertiary combined mesh 152, which will be described later).

[0044] 3(b), the 2×2×2 (total of eight) primary combined meshes 150 excluding the forbidden meshes are combined to generate a secondary combined mesh 151. Even when generating the secondary combined mesh 151, the secondary combined meshes 151 are generated sequentially starting from a starting point P away from the heat exchange regions R1 and R2, so that the uncombinable meshes 153 that could not be combined as the secondary combined mesh 151 can be positioned close to the heat exchange regions R1 and R2.

[0045] In addition, the 2×2 primary combined meshes 150b surrounded by the thick line in FIG. 3(b) can actually be combined to form the secondary combined mesh 151. However, when these primary combined meshes 150b are combined, a secondary combined mesh is generated whose center is shifted from the other secondary combined meshes 151. Therefore, in this embodiment, these primary combined meshes 150b are intentionally not combined (they are left as uncombinable meshes 153). This allows all the secondary combined meshes 151 to be aligned in a grid pattern.

[0046] Next, as shown in Fig. 4, the uncombinable meshes 153 that could not be combined to form the secondary combined mesh 151 are designated as combination prohibited meshes. In addition, of the secondary combined meshes 151, the secondary combined meshes 151 adjacent to combination prohibited meshes (the primary combined mesh 150 and the uncombinable mesh 153) are designated as combination prohibited meshes. Then, excluding the combination prohibited meshes, the 2 x 2 x 2 (total of eight) secondary combined meshes 151 are combined to generate a tertiary combined mesh 152 (see Fig. 1).

[0047] In this manner, in this embodiment, when a secondary combined mesh 151 is generated, the primary combined mesh 150 adjacent to a combine-prohibited mesh (such as the mold mesh 15 or the uncombinable mesh 153) is designated as a combine-prohibited mesh, and the primary combined mesh 150 excluding the combine-prohibited mesh is combined with the secondary combined mesh 151. Similarly, when a tertiary combined mesh 152 is generated, the secondary combined mesh 151 adjacent to the combine-prohibited mesh is designated as a combine-prohibited mesh.

[0048] By employing such a combining method, the mesh sizes can be gradually increased in the order of mold mesh 15, primary combined mesh 150, secondary combined mesh 151, and tertiary combined mesh 152. More specifically, the primary combined mesh 150 or secondary combined mesh 151 (n-th order combined mesh or n+1-th order combined mesh) is always placed next to every primary combined mesh 150 (when n-th order combined mesh is used, n=1). In other words, the tertiary combined mesh 152 (n+2-th order combined mesh) is not placed next to the primary combined mesh 150.

[0049] In this way, by gradually making the mold mesh 15 coarser as it moves away from the heat exchange regions R1, R2, heat transfer calculations in the heat exchange regions R1, R2 can be performed accurately while reducing the load of heat transfer calculations in regions away from these regions.

[0050] By generating such a non-uniformly divided mesh, the temperature change of the mold 12 can be analyzed with high accuracy in a short time, but the heat transfer calculation between meshes of different sizes (for example, the boundary between the mold mesh 15 and the primary combined mesh 150) tends to become complicated. A method for performing this heat transfer calculation accurately will be described with reference to the enlarged portion of FIG.

[0051] 4, of the mold meshes 15, the one arranged in the third layer counting from the molten metal mesh 13 side will be described as mold mesh 15a, and the one arranged outside of mold mesh 15a will be described as mold mesh 15b. Also, of the primary connecting meshes 150, the one arranged outside of mold mesh 15b will be described as primary connecting mesh 150c, and the one arranged outside of primary connecting mesh 150c will be described as primary connecting mesh 150d.

[0052] First, a case where heat transfer calculation between the mold mesh 15b and the primary connecting mesh 150c is performed in one dimension will be described. In this one-dimensional heat transfer calculation, the two layers of mold meshes 15a and 15b are virtually connected to define a virtual connecting mesh 15e. The boundary between this virtual connecting mesh 15e and the primary connecting mesh 150c is set to ξ=0, and the temperature Te (average temperature; the same applies below) of the virtual connecting mesh and the temperatures Tc and Td of the primary connecting meshes 150c and 150d are approximated by, for example, the following quadratic function Equation 1.

[0053]

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[0054]

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[0055]

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[0056]

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[0057]

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[0058]

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[0059]

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[0060]

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[0061]

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[0062] Fig. 5(a) is a graph showing the calculation result of the heat flux from the mold mesh 15b to the primary connection mesh 150c (virtual division mesh 150f). The vertical axis of Fig. 5(a) shows the magnitude q of the heat flux, and the horizontal axis shows the elapsed time t (s) during the casting analysis (this is also true for Fig. 5(b) described later). The solid line graph in Fig. 5(a) is an exact solution of the heat flux from the mold mesh 15b to the primary connection mesh 150c, and the dashed line graph shows the magnitude of the heat flux qb→f calculated by the above formula 9.

[0063] Moreover, the graph shown by the dashed line in Figure 5(a) is a heat flux qb→c from the mold mesh 15b to the primary connecting mesh 150c, calculated simply based on the temperatures Tb, Tc of those meshes, as shown in the following formula 10.

[0064]

number

[0065] As described above, the temperature gradient of the mold 12 becomes larger closer to the heat exchange regions R1, R2. For this reason, for example, when the two layers of mold meshes 15g, 15h (see FIG. 4) located on the inner side of the mold meshes 15a, 15b are omitted and the mold meshes 15a, 15b are placed adjacent to the molten metal mesh 13 (i.e., when the two layers of mold meshes 15a, 15b are placed on the outer side of the molten metal mesh 13), the temperature Ta of the mold mesh 15a may temporarily become much higher than the temperature Tb of the mold mesh 15b.

[0066] When such a large temperature gradient occurs, if the temperature Te (Te = (Ta + Tb) / 2) of the virtual combination mesh 15e is calculated from the average value of the temperatures Ta, Tb of the mold meshes 15a, 15b, and the temperature Tf of the virtual division mesh 150f is calculated from the temperature Te of the virtual combination mesh 15e, the temperature Tf of the virtual division mesh 150f may be estimated to be higher than the temperature Tb of the mold mesh 15b. In this case, the heat flux qb → f from the mold mesh 15b to the virtual division mesh 150f is calculated as a negative value. Hereinafter, this phenomenon is called undershoot, and this undershoot will be explained with reference to Figures 5 (a) and 5 (b).

[0067] FIG. 5(a) is a graph showing the calculation results of heat flux when four layers of mold meshes 15a, 15b, 15g, and 15h are arranged outside the molten metal mesh 13 as in this embodiment, and FIG. 5(b) is a graph showing the calculation results of heat flux when two layers of mold meshes 15a and 15b are arranged outside the molten metal mesh 13.

[0068] As shown in Fig. 5(b), when two layers of mold meshes 15a and 15b are arranged outside the molten metal mesh 13, the value of the heat flux qb→c shown by the dashed line does not have an undershoot, but the value of the heat flux qb→f shown by the broken line has an undershoot. This undershoot of the heat flux qb→f occurs for an extremely short time in the early stage of the casting analysis (the stage at which heat input from the molten metal mesh 13 side to the mold meshes 15a and 15b begins). Therefore, although the effect of the undershoot of the heat flux qb→f on the accuracy of the casting analysis is small, it is more preferable that such an undershoot does not occur.

[0069] Therefore, as shown in Fig. 4, it is preferable to arrange about four layers of mold meshes 15a, 15b, 15g, and 15h on the outside of the molten metal mesh 13. This allows the heat transfer calculation between the mold mesh 15b and the primary connection mesh 150c to be performed in an area with a relatively small temperature gradient, so that undershooting of the value of the heat flux qb→f can be suppressed as shown in Fig. 5(a). Therefore, the temperature change of the mold 12 can be analyzed with high accuracy.

[0070] Next, a case where heat transfer calculation between the mold mesh 15 and the primary connecting mesh 150c is performed in two dimensions will be described with reference to Fig. 6. Fig. 6 is an explanatory diagram of a case where heat transfer calculation between the mold mesh 15 and the primary connecting mesh 150c is performed in two dimensions.

[0071] 6, the primary combination mesh 150c may have a mold mesh 15 adjacent to its left side or two upper and lower sides (a total of three sides). In this case, when performing a two-dimensional calculation of heat transfer between the mold mesh 15 and the primary combination mesh 150c, the mold mesh 150c is virtually divided (divided into four) into meshes of the same size as the mold mesh 15, and defined as virtual division meshes 150ia to 150id. Then, a corner of the virtual division mesh 150ia (the intersection of two sides adjacent to the mold mesh 15) is set as the origin O, and the temperature distribution of the mesh based on this origin O is assumed to be, for example, the following formula 11.

[0072]

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[0073] Furthermore, the temperatures of the two primary connecting meshes 150 that are in contact with the primary connecting mesh 150c (sharing a corner) are defined as Tn and Tp, and the 2×2 mold mesh 15 that is in contact with the primary connecting mesh 150c (sharing a corner) is virtually connected, and the temperatures of the virtually connected mesh are defined as TО and Tq. When the coefficient cij of the above formula 11 is determined from these temperatures Ti to Tq, it is calculated as shown in the following formula 12.

[0074]

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[0075]

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[0076]

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[0077]

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[0078]

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[0079] As described above, in this embodiment, when performing heat transfer calculations between the mold mesh 15 and the primary combined mesh 150 (fine mesh and coarse mesh), a process is executed in which the mold mesh 15 is virtually combined and defined as a virtually combined mesh (virtual combining step), and a process is executed in which the primary combined mesh 150 (coarse mesh) is virtually divided into meshes of the same size as the mold mesh 15 and defined as a virtually divided mesh (virtual dividing step).

[0080] Also, a process (temperature calculation step) of calculating the temperature of the virtual divided mesh based on the temperatures (temperature distribution) of the virtual combined mesh and the primary combined meshes 150 arranged around the virtual divided mesh, and a process (heat transfer calculation step) of calculating heat transfer between the mold mesh 15 and the virtual divided mesh based on the temperatures of these meshes are executed. This allows for accurate calculation of heat transfer between the meshes 15, 150 of different sizes.

[0081] In the above explanation, a method of performing heat transfer calculations one-dimensionally or two-dimensionally between the mold mesh 15 and the primary connecting mesh 150 has been exemplified, but a similar heat transfer calculation may be performed in three dimensions. Also, a similar heat transfer calculation may be performed between another relatively fine mesh (for example, the primary connecting mesh 150) and a mesh that is coarser than the fine mesh (for example, the secondary connecting mesh 151).

[0082] Next, the analysis process executed by the analysis device 1 will be described with reference to Fig. 7 and Fig. 8. Fig. 7(a) is a block diagram showing the electrical configuration of the analysis device 1, and Fig. 7(b) is a flowchart of the analysis process.

[0083] 7(a), the analysis device 1 has a CPU 5, an HDD (hard disk drive) 6, and a RAM 7, which are connected to an input / output port via a bus line 8. In addition, the above-mentioned mouse 2, keyboard 3, and display 4 are connected to the bus line 8.

[0084] The CPU 5 is a calculation device that controls each part connected by the bus line 8, and the HDD 6 is a rewritable non-volatile storage device that stores programs executed by the CPU 5, fixed value data, etc. When the analysis program 6a stored in the HDD 6 is executed by the CPU 5, an analysis process (see FIG. 7(b)) is performed.

[0085] The RAM 7 is a memory for rewritably storing various workpiece data and flags when the CPU 5 executes the analysis program 6a, and the RAM 7 is provided with a join flag 7a used in the non-uniformly divided mesh generation process (S2). The join flag 7a is a flag provided for each of the mold mesh 15 and each of the joined meshes 150-152, and is a flag for determining whether or not each of the joined meshes is a join-prohibited mesh. When an instruction to execute the analysis program 6a is input from the mouse 2 or keyboard 3, the analysis process is executed by the CPU 5.

[0086] 7(b), in the analysis process, first, various analysis conditions are set (S1). The analysis conditions set here include the physical properties of the molten metal 11 (casting), the pouring speed of the molten metal 11, the gravitational acceleration, data on the mold 12, and the sizes of the meshes 13 to 15. The physical properties of the molten metal 11 include information on the density, specific heat, thermal conductivity, etc. of the molten metal 11, and the data on the mold 12 includes information on the density, specific heat, thermal conductivity, etc. of the mold 12 in addition to the data on the structure of the mold 12 described above.

[0087] The conditions set in this process of S1 are mainly input by the user, but some of the settings may be automatically performed by the analysis program 6a. An analysis model 10 is generated by setting various analysis conditions in the process of S1, and after the generation of this analysis model 10, a non-uniformly divided mesh generation process (S2) is executed. This process will be described with reference to Fig. 8. Fig. 8 is a flowchart of the non-uniformly divided mesh generation process (S2).

[0088] As shown in FIG. 8, in the non-uniform mesh generation process (S2), first, a plurality of meshes 13-15 are generated on the mold 12 of the analysis model 10 (S10). At this time, a member number indicating that the meshes 13-15 are located on the mold 12, the cavity 120, or the cooling structure 121 is set for each of the meshes 13-15. Next, the molten metal mesh 13 and the cooling mesh 14 are identified (searched) based on the member number, and the value of the connection flag 7a of those meshes 13, 14 is set to 0 indicating that they are not connected meshes (S11). Next, the number of connections of the mold mesh 15 is set to N (S12). This number of connections N may be set by the user or automatically by the analysis program 6a.

[0089] In the above embodiment, the mold mesh 15 is connected three times (N=3) and connected up to the tertiary connected mesh 152 (n=1, 2, 3 in the case of an n-th order connected mesh), but the number of connections may be one or more (N is an integer of 1 or more, and n=1, 2, 3, etc. in the case of connecting up to the n-th order connected mesh).

[0090] After the process of S12, the values ​​of the join flags 7a of all the mold meshes 15 are set to 1, indicating that the meshes are to be joined (S13), and the number of layers of the join-prohibited meshes is set (S14). The number of layers of the join-prohibited meshes may also be set by the user or automatically by the analysis program 6a.

[0091] After the process of S14, the value of the join flag 7a of the join-prohibited mesh is set to 0 (S15). Next, the number of layers of the mold mesh 15 is adjusted (S16) so that the number of unjoinable meshes 153 generated in the subsequent join process of S17 is minimized. Specifically, the number of mold meshes 15 excluding the join-prohibited meshes set in S14 is confirmed in three dimensions, and the total number of meshes is adjusted based on the number of meshes to be joined (whether 2x2x2 meshes are joined or 3x3x3 meshes) and the number of times joining is performed (up to how many joined meshes are to be generated), so as to reduce the number of unjoinable meshes 153 generated in the subsequent join process.

[0092] Examples of such processing include a process of adding one or more layers (number of columns) of mold mesh 15 to an end of analysis model 10 (e.g., the right end of FIG. 2(a)), or a process of reducing the number of layers of a combination prohibition mesh. Note that this mesh number adjustment process may be configured to be performed only once before generating the primary combination mesh 150, or may be configured to adjust the number of n-1-order combination meshes (e.g., primary combination mesh 150) when generating an n-order combination mesh (e.g., secondary combination mesh 151).

[0093] By performing the mesh number adjustment process in S16, when mesh joining is started from a starting point P away from the heat exchange regions R1, R2, it is possible to prevent unjoinable meshes 153 from remaining in the vicinity of the heat exchange regions R1, R2. Therefore, the intended number of layers of mold meshes 15 can be arranged on the heat exchange regions R1, R2. Also, when mesh joining is started from the heat exchange regions R1, R2 side as a starting point, it is possible to prevent unjoinable meshes 153 from remaining in regions away from there. In this way, by preventing the generation of unjoinable meshes 153, it is possible to appropriately generate a non-uniformly divided mesh.

[0094] After the process of S16, a search is made for mold meshes 15 for which the combination flag 7a is set to 1, and the searched mold meshes 15 are combined together to generate the primary combined mesh 150 (S17). In the above embodiment, a case has been described in which 2×2×2 mold meshes 15 are combined to the primary combined mesh 150, but 3×3×3 or more mold meshes 15 may be combined to the primary combined mesh 150 (the same applies to the case in which an n-th order combined mesh is combined to an n+1-th order combined mesh).

[0095] Also, the number of meshes to be combined may be different when generating an n-th degree combined mesh and when generating an n+1-th degree combined mesh. An example of such a configuration is a configuration in which 2×2×2 primary combined meshes 150 are combined to generate a secondary combined mesh 151, and 4×4×4 secondary combined meshes 151 are combined to generate a tertiary combined mesh 152.

[0096] After the process of S17, it is confirmed whether the number of times the meshes have been combined has reached N (S18). If the number of times the meshes have been combined has not reached N (S18: No), the combination flag 7a of the uncombinable meshes 153 that could not be combined to form the primary combined mesh 150 is set to 0 (S19), and the process returns to S14.

[0097] In the second processing of S14, the number of layers of the primary combined mesh 150 that are to be merge prohibited meshes is set, and the merge flag 7a of the merge prohibited mesh is set to 0 (S15). Next, the number of layers of the primary combined mesh 150 is adjusted (S16), or the processing of S16 is skipped, and the primary combined meshes 150 whose merge flags 7a are set to 1 are merged together to generate the secondary combined mesh 151 (S17). At this time, since the merge flags 7a of all the merge prohibited meshes that are not to be merged, including the non-mergeable mesh 153, are set to 0, it is possible to easily search for the primary combined meshes 150 that should be merged.

[0098] After the process of S17, it is confirmed whether the number of times the meshes have been combined has reached N (S18). If the number of times the meshes have been combined has not reached N (S18: No), the combination flag 7a of the uncombinable meshes 153 that could not be combined to form the secondary combined mesh 151 is set to 0 (S19), and the process returns to S14. The processes of S14 to S19 are repeated, and the mold mesh 15 is combined N times to generate up to an n-th order combined mesh. As a result, a non-uniformly divided mesh is generated on the mold 12 of the analysis model 10 (see FIG. 1).

[0099] On the other hand, in the process of S18, if the number of mesh combinations reaches N (S18: Yes), the series of processes is terminated, and the casting analysis process (S3) is executed (see FIG. 7(b)). Since a known technique can be adopted as a method for analyzing the flow of the molten metal 11 in this casting analysis process (S3), a detailed description is omitted, but examples of known analysis methods include the techniques disclosed in Japanese Patent Application Laid-Open No. 10-137926 and Japanese Patent Application Laid-Open No. 06-122068.

[0100] In the casting analysis process (S3), the above-mentioned non-uniformly divided mesh (see FIG. 1) is used, so that the heat transfer calculation in the heat exchange regions R1 and R2 can be performed accurately, while the load of the heat transfer calculation in the region away from the heat exchange regions can be reduced. In addition, the above-mentioned formulas 1 to 16 are used for the heat transfer calculation between meshes of different sizes (for example, calculation of heat flux qb→f), so that the heat transfer calculation can be performed accurately.

[0101] The present invention has been described above based on the above embodiment, but the present invention is not limited to the above form in any way, and it can be easily inferred that various modifications and improvements are possible within the scope that does not deviate from the spirit of the present invention.

[0102] In the above embodiment, the case where the combined meshes 150, 151 are generated in sequence from the starting point P away from the heat exchange regions R1, R2 in a direction approaching the heat exchange regions R1, R2 has been described, but this is not necessarily limited to this. For example, the combined meshes 150, 151 may be generated in sequence in a direction away from the heat exchange regions R1, R2.

[0103] Also, when there is an intermediate region sandwiched between heat exchange regions, the center of the intermediate region (the midpoint of each heat exchange region sandwiching the intermediate region) may be set as the starting point, and the combined mesh may be generated sequentially from the starting point toward each heat exchange region. This allows a coarse combined mesh to be placed at the center of the intermediate region, while a fine mesh (uncombinable mesh) that could not be combined can be placed near the heat exchange regions. An example of such an intermediate region is the intermediate region R3 (see FIG. 2(b)) described in the above embodiment. Also, for example, when another heat exchange region R4 exists on the opposite side (right side of FIG. 2) from the heat exchange region R1 across the starting point P, the region between these heat exchange regions R1 and R4 is the intermediate region.

[0104] In the above embodiment, the case where the heat flux qb→f is calculated from the temperatures Tb, Tf of the mold mesh 15b and the virtual divided mesh 150f has been described. However, the heat flux qb→c from the mold mesh 15b to the primary combined mesh 150c may also be calculated from the temperatures Tb, Tc of those meshes. [Explanation of symbols]

[0105] 1. Analysis equipment (computer) 6a Analysis Program 10 Analysis model 11 Molten metal 12 Mold 120 Cavity (heat exchange section) 121 Cooling structure (heat exchange section) 13 Molten metal mesh 14 Cooling Mesh 15,15g,15h Cast mesh 15a Mold mesh (fine mesh) 15b Mold mesh (fine mesh) 15e Virtual Connected Mesh 150, 150a, 150b Primary combined mesh (combined mesh) 150c Primary combined mesh (coarse mesh, combined mesh) 150d Primary combined mesh (coarse mesh, combined mesh) 150f Virtual division mesh 151 Secondary connected mesh (connected mesh) 152 3rd order connected mesh (connected mesh) 153,153a Unconnectable mesh S14,17 Setting steps S15 Binding Step S16 Adjustment step S3 Casting analysis process (Casting analysis step) P Start point

Claims

1. A model generation step of generating an analytical model of a mold having a heat exchange portion formed of a cavity or a cooling structure; a mesh generating step of generating a plurality of meshes on the analysis model generated in the model generating step; a setting step of setting the meshes that are not to be joined as join-prohibited meshes among the plurality of meshes generated in the mesh generating step; a combining step of generating a non-uniformly divided mesh by generating a combined mesh by combining the meshes located on the mold, excluding the combined meshes set in the setting step; a casting analysis step of performing a casting analysis using the non-uniformly divided mesh generated in the combining step, The setting step is an analysis program characterized in that the heat exchange section is covered with multiple layers of the bond-prohibiting mesh by setting multiple layers of the mesh arranged along the heat exchange section and overlapping in a direction away from the heat exchange section as the bond-prohibiting mesh.

2. 2. The analysis program according to claim 1, wherein in the combining step, a position away from the heat exchange portion is set as a starting point, and the combined mesh is generated successively from the starting point toward the heat exchange portion.

3. The setting step and the combining step are repeated a number of times; The setting step sets the joining mesh adjacent to the joining prohibition mesh as a joining prohibition mesh, 2. The analysis program according to claim 1, wherein said combining step further combines said combined meshes with each other except for said combination-prohibited meshes.

4. 4. The analysis program according to claim 3, wherein in said setting step, unmergeable meshes that remain unmerge in said combining step are set as said merge prohibited meshes.

5. The unequally divided mesh includes a fine mesh and a coarse mesh adjacent to the fine mesh and coarser than the fine mesh, In the casting analysis step, a virtually combining step of virtually combining fine meshes adjacent to the coarse mesh to define a virtually combined mesh; a virtual division step of virtually dividing the coarse mesh into meshes of the same size as the fine mesh and defining the meshes as virtual divided meshes; a temperature calculation step of calculating a temperature of the virtual division mesh based on temperatures of the virtual combined mesh and other coarse meshes arranged around the coarse mesh; 2. The analysis program according to claim 1, further comprising a heat transfer calculation step of calculating heat transfer between the fine mesh and the virtual divided mesh based on the temperatures of those meshes.

6. and further causing the computer to execute an adjustment step of adjusting the number of meshes based on the number of meshes excluding the join-prohibited meshes set in the setting step, 2. The analysis program according to claim 1, wherein said adjustment step adjusts said number of meshes so as to reduce the number of uncombinable meshes which cannot be combined in said combining step.

7. A model generation step of generating an analytical model of a mold having a heat exchange portion formed of a cavity or a cooling structure; a mesh generating step of generating a plurality of meshes on the analysis model generated in the model generating step; a setting step of setting the meshes that are not to be joined as join-prohibited meshes among the plurality of meshes generated in the mesh generating step; a combining step of generating a non-uniformly divided mesh by generating a combined mesh by combining the meshes located on the mold, excluding the combined meshes set in the setting step; a casting analysis step of performing a casting analysis using the non-uniformly divided mesh generated in the combining step, The casting analysis method is characterized in that in the setting step, multiple layers of the mesh arranged along the heat exchange section, and multiple layers of the mesh overlapping in a direction away from the heat exchange section, are set as the bond prohibition mesh, thereby covering the heat exchange section with the bond prohibition mesh of multiple layers.

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