JP2023054897A - Method, system and program for designing casting, and recording medium - Google Patents

Abstract

To provide a method for designing a casting that can be carried out with accuracy and simplicity with the occurrence of galling suppressed.SOLUTION: A method for designing a casting, for designing a shape of a casting having a first portion using computer simulation, comprises: a first step of creating an analysis model; a second step of acquiring temperature information of a melt and mold in a solidification shrinkage process of the melt; a third step of computing a shape change of a work-piece in the solidification shrinkage process of the melt and reproducing a sticking state of the work-piece to the mold; a fourth step of computing surface pressure to occur at a contact surface with the work-piece on a plurality of release strokes in a release process based on a result of the structural analysis and a resisting force to act on the mold; a fifth step of outputting a distribution of surface pressure exceeding a predetermined threshold; a sixth step of specifying a second portion where galling possibly may occur based on the distribution of surface pressure; and a seventh step of setting up a required gradient angle of the second portion relative to a release direction so as not to cause galling in the first portion.SELECTED DRAWING: Figure 5

Description

The present disclosure relates to a molded product design method, design system, design program, and recording medium.

2. Description of the Related Art Conventionally, in the field of casting such as the die casting method, it is known that solidification and shrinkage of a work within a mold generates a strong gripping force of the work against the mold.

For example, when forming a molding surface that is substantially parallel to the mold release direction, if the inclination angle of the cavity surface with respect to the mold release direction is small, there is a possibility that the gripping force will continue to act during the mold release of the workpiece. There is a growing concern that scratches (galling) will occur due to strong contact between the mold and the workpiece. Therefore, in order to suppress the occurrence of galling, the shape of the molded product is designed by increasing the inclination angle of the cavity surface so that the mold and the work can be separated quickly and the work can be released smoothly. .

However, if the inclination angle is increased to suppress the occurrence of galling, if it is necessary to finally obtain a molding surface with a smaller inclination angle, post-processing such as machining is required after the casting process to machine the workpiece surface. However, it is necessary to ensure the accuracy of the molding surface. When a post-process is provided, equipment, man-hours, etc. for the post-process are required, which leads to lengthening, complicating, and increasing the cost of the manufacturing process of the molded product.

Therefore, it is desired to develop a method for easily designing the shape of a molded product with high accuracy so that a desired molding surface can be obtained at the casting stage while suppressing the occurrence of galling.

In recent years, CAE (Computer Aided Engineering) analysis has been used as a method for designing molded products (see, for example, Patent Document 1).

In Patent Document 1, (A) a process of analyzing the temperature of the product to calculate the stress distribution based on the mold restraint of the product and extracting the frictional surface elements, and (B) performing the stress distribution calculation based on the mold release force. Step (C) A step of determining the state of static/kinetic friction from the physical property values of each friction surface element using a database constructed based on actual measurements for each friction surface element; (E) Repeating the series of steps (B) to (D) while increasing the release force each time. , a method of designing a mold comprising a step of extracting the maximum load of the mold release force and a portion where a crack occurs. Further, based on the information indicating the relationship between the friction force and the temperature, which corresponds to the stress value of each friction surface element in the stress distribution obtained in the step (B), the calculation means calculates the total friction surface element It is disclosed that a step of determining whether galling occurs or not may be further provided. In addition, according to the mold design method, it is possible to optimize the arrangement position and the number of arrangement of the release pins, improve the analysis accuracy, and prevent galling defects that occur when the product is released from the mold. It is disclosed that it can be predicted.

JP-A-2005-46892

In the technique of Patent Document 1, galling is finally predicted based on a predetermined release force applied to the product by the release pin. Although this mold release force is gradually increased by repeated calculations, this method performs an evaluation based on the mold release force at a point in time immediately before the mold release.

As described above, galling occurs due to strong contact between the mold and the workpiece during the mold release operation. Prediction accuracy may be insufficient.

Therefore, in the present disclosure, a molded product design method, design system, and design program that can accurately and simply design a molded product that suppresses the occurrence of galling and forms a desired molding surface in the casting stage. , and a recording medium.

In order to solve the above problems, the method of designing a molded product disclosed herein is to pour a molten metal into a mold cavity, and release the workpiece obtained by solidifying and shrinking the molten metal from the mold. A method of designing the shape of a molded product using a computer simulation in a casting method for obtaining a molded product having one part, wherein the shape data of the cavity is divided to create an analysis model consisting of a plurality of elements. a step B of obtaining temperature information of the molten metal and the mold during the solidification and contraction process of the molten metal by performing a casting analysis using the analysis model; and a structural analysis based on the temperature information. Thus, a step C of calculating a change in the shape of the work in the process of solidification and contraction of the molten metal and reproducing the state of the work clinging to the mold, the result of the structural analysis, and the resistance acting on the mold. Step D of calculating the surface pressure generated at the contact surface between the mold and the work in a plurality of mold release strokes in the process from the start of mold release of the work until the work is separated from the mold, based on Step E of outputting the surface pressure distribution exceeding a predetermined threshold in the plurality of mold release strokes; and Step F of specifying a second portion where galling may occur based on the surface pressure distribution. and a step G of setting the necessary inclination angle of the second portion with respect to the release direction so that galling does not occur at least in the first portion.

When the molten metal solidifies and shrinks due to cooling, the metallic material of the molten metal, which has a larger coefficient of thermal expansion than the mold, clings to the mold. As a result, an engaging force acting from the work surface to the cavity surface is generated on the contact surface between the work and the mold. The clinging force can be expressed as a surface pressure corresponding to the clinging force per unit area. The surface pressure continues to be generated on the contact surface between the workpiece and the mold even during the mold release process. At locations where the surface pressure exceeds a predetermined threshold value, the work surface and the cavity surface come into strong contact, causing galling. In this configuration, of the surface pressure generated on the contact surface between the mold and the workpiece during the mold release process, the distribution of surface pressure exceeding a predetermined threshold value in a plurality of mold release strokes (hereinafter also referred to as "surface pressure distribution"). to output As a result, the mold release process can be divided into a plurality of parts and changes in the surface pressure distribution can be evaluated, so that the second part where galling may occur can be specified with high accuracy. Then, by setting the necessary inclination angle of the second portion with respect to the mold release direction so that galling does not occur in the first portion of the molded product, the molded product in which the occurrence of galling is suppressed at least in the first portion can be obtained. A suitable final shape can be designed.

If a part or all of the second portion overlaps the first portion, the required gradient angle of the second portion may be set to a gradient angle that does not cause galling. Further, when the second portion and the first portion do not overlap, the required gradient angle of the second portion may be a gradient angle at which galling occurs. The inclination angle of the second portion is set so that galling does not occur at the portion as well.

As used herein, the term "mold release direction" refers to a direction parallel to the moving direction of one mold relative to the other mold when the mold is opened and/or the ejector pin extrusion direction when the mold has an ejector mechanism. parallel direction. "Mold release stroke" means the distance in the mold release direction from the cavity surface to the work surface at a location where galling does not occur. Further, when the mold has an ejector mechanism, the "mold release stroke" can be represented by the length of ejection of the ejector pin from the cavity surface. The "release stroke" is sometimes referred to as "release amount" or "St". Furthermore, the term "tilt angle" refers to the tilt angle of the cavity surface, work surface and molding surface with respect to the release direction. Further, the "required inclination angle" is the minimum inclination angle at which galling does not occur or the occurrence of galling is suppressed within a predetermined range.

The identification of the second portion in the step F is performed by calculating the range of release strokes in which the distribution of the contact pressure occurs based on the distribution of the contact pressure for each of the plurality of release strokes. in the release direction.

The range of the mold release stroke in which the surface pressure distribution occurs corresponds to the length of continuous strong contact between the work surface and the cavity surface, that is, the length of galling in the mold release direction. Therefore, according to this configuration, the accuracy of specifying the second portion is improved by specifying the length of the galling in the releasing direction.

The predetermined threshold value is preferably determined based on the relationship between the surface pressure and the actual occurrence of galling in a molded product having a predetermined inclination angle, which is obtained in advance by an experimental method.

According to this configuration, since the threshold value is set based on the relationship between the surface pressure and the actual galling occurrence state, it is possible to ensure consistency with the actual machine in the computer simulation and improve the accuracy of the analysis.

A step H of determining whether or not the shape data of the cavity needs to be changed is further provided after the step G, and when it is determined in the step H that the shape data of the cavity needs to be changed, the step G Reflecting the required gradient angle set in the analysis model, the step A to the step H are repeated until it is determined that the shape data of the cavity does not need to be changed in the step H, and the cavity It is preferable to determine the final shape of

By repeating the desk study while adjusting the inclination angle, the number of prototype molds can be reduced, and the optimum final shape of the cavity can be determined more quickly and at a lower cost.

In the final shape, an inclination angle of at least a portion of the cavity surface forming the portion other than the second portion may be set smaller than the inclination angle of the cavity surface forming the second portion.

Parts other than the second part have a low possibility of galling. Therefore, by setting the inclination angle of at least a part of the cavity surface forming the part other than the second part to be smaller than the inclination angle of the cavity surface forming the second part, excessive thickening is suppressed. As a result, the weight of the molded product can be reduced.

The first portion and the second portion do not overlap, and in the final shape, the inclination angle of the cavity surface forming the first portion is greater than the inclination angle of the cavity surface forming the second portion. It may be set smaller.

The first portion may have to be formed as a plane substantially parallel to the release direction. In this case, the inclination angle with respect to the releasing direction must be, for example, a predetermined value or less, and galling may occur as described above, but the occurrence of galling is not allowed at the first portion. Therefore, in the conventional method, for example, the inclination angle of the cavity surface forming the first portion is set to an inclination angle that does not cause galling exceeding a predetermined value, the work is manufactured, and post-processes such as machining are provided to obtain the desired result. formed the first part of However, in the conventional method, since it is necessary to provide a post-process, the manufacturing process of the molded article may be complicated.

In this configuration, by setting the slope angle of the cavity surface forming the first portion to a desired slope angle smaller than the slope angle of the second portion, in the casting stage, the surface substantially parallel to the mold release direction can be formed into the first parts can be formed. In this way, the occurrence of galling at the first portion can be suppressed, and the post-casting process can be omitted, thereby simplifying the method of manufacturing the molded product.

The first portion is, for example, a seat surface or the like to which other parts are fastened.

According to this configuration, the bearing surface to which other parts are fastened can be formed in the casting stage while suppressing the occurrence of galling, so that the manufacturing method of the molded product can be simplified.

The molded product design system disclosed herein is a casting method in which a molded product having a first part is obtained by releasing a work formed by solidifying and shrinking a molten metal poured into a mold cavity from the mold. A system for designing the shape of the molded product using computer simulation, comprising model creation means for creating an analysis model consisting of a plurality of elements by dividing the shape data of the cavity, and using the analysis model. A casting analysis means for obtaining temperature information of the molten metal and the mold in the solidification and shrinkage process of the molten metal by performing a casting analysis by performing a casting analysis, and a solidification and shrinkage process of the molten metal by performing structural analysis based on the temperature information based on structural analysis means for calculating the shape change of the work in and reproducing the state of the work clinging to the mold, the result of the structural analysis, and the resistance acting on the mold, surface pressure calculation means for calculating surface pressure generated on a contact surface between the mold and the work in a plurality of mold release strokes in a process from the start of mold release until the work separates from the mold; and the plurality of mold release strokes. a surface pressure distribution output means for outputting the distribution of the surface pressure exceeding a predetermined threshold; and a second part identification means for identifying a second part where galling may occur based on the distribution of the surface pressure. and gradient angle setting means for setting a necessary gradient angle of the second portion with respect to the release direction so that galling does not occur at least in the first portion.

Further, the molded product design program disclosed herein is a casting method for obtaining a molded product having a first portion by releasing a work formed by solidifying and contracting a molten metal poured into a mold cavity from the mold. 3, a program for designing the shape of the molded product using a computer simulation, wherein the computer divides the shape data of the cavity to create an analysis model consisting of a plurality of elements; A procedure B for acquiring temperature information of the molten metal and the mold in the process of solidification and shrinkage of the molten metal by performing casting analysis using an analysis model, and performing structural analysis based on the temperature information to obtain the temperature information of the molten metal. Based on the procedure C of calculating the shape change of the work in the solidification shrinkage process and reproducing the state of the work being held against the mold, the result of the structural analysis, and the resistance acting on the mold, A procedure D for calculating the surface pressure generated at the contact surface between the mold and the work in a plurality of mold release strokes in the process from the start of releasing the work until the work separates from the mold; and the plurality of mold release strokes. 3, a procedure E of outputting the distribution of the surface pressure exceeding a predetermined threshold; a procedure F of specifying a second portion where galling may occur based on the distribution of the surface pressure; and at least the first and a step G of setting the necessary inclination angle of the second portion with respect to the release direction so that galling does not occur at the portion.

Further, a recording medium disclosed herein is a computer-readable recording medium recording the design program for the molded product.

As described above, according to the present disclosure, it is possible to design a suitable final shape of a molded product in which galling is suppressed at least at the first portion.

1 is a block diagram illustrating a molded product design system according to an embodiment of the present disclosure; FIG. 1 schematically shows a die casting machine for manufacturing molded articles; FIG. It is a figure for demonstrating an example of the manufacturing method of a molded article. FIG. 4 is a diagram for explaining the mechanism of galling. 4 is a flow chart illustrating a method for designing a molded product according to an embodiment of the present disclosure; 1 is a perspective view of a suspension tower, which is an example of a molded product; FIG. It is a cross-sectional perspective view which shows the seat surface by the side of a front. It is a cross-sectional perspective view which shows the seat surface by the side of the rear. It is a figure which shows an example of the output result of surface pressure distribution of the seat surface of the front side and the rear side. It is the graph which plotted the surface pressure in each measurement point of the seat surface of the front side. It is the graph which plotted the surface pressure in each measurement point of the seat surface of the rear side. FIG. 5 is a diagram showing an example of output results of surface pressure distributions on the front and rear seat surfaces at different inclination angles; FIG. 11 is a graph for explaining a method of examining conditions for setting a slope angle; FIG. FIG. 4 is a cross-sectional perspective view showing part of the optimal final shape of the suspension tower.

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

(one embodiment)
<Molded product design system>
The molded product design system 21 according to the present disclosure is a CAE (Computer Aided Engineering) system for designing the shape of a molded product obtained by casting using computer simulation. The design system 21 includes a control device 22, an input device 23, an output device 24, a storage device 25, and an arithmetic device 26, as shown in FIG.

As will be described later, a molded product is produced by injecting a molten metal into the cavity of the mold, releasing the work obtained by solidifying and shrinking the molten metal from the mold by opening the mold and pushing out an ejector pin, cutting the gate, and releasing the work. It is obtained through processes such as cooling and optional machining. The molded product is not particularly limited, and includes parts and products in general obtained by casting, such as vehicle parts, industrial parts, industrial products, building materials, electronic equipment, home electric appliances, furniture, and daily necessities. Examples of the molten metal include aluminum, magnesium, zinc and alloys thereof, preferably aluminum alloys. Examples of aluminum alloys include general casting materials such as ADC12, ADC10, and ADC5. The casting method includes die casting, high pressure casting, low pressure casting, semi-solid casting, etc., preferably die casting. The mold is a mold, a sand mold or the like, preferably a mold.

In addition, a molded article is provided with the 1st site|part. The first portion may be a part of the surface of the molded article, or may be the entire surface. The first portion is preferably a surface on which galling is not allowed, and specifically, for example, a bearing surface to which other parts are fastened. Also, the first portion is preferably a surface substantially parallel to the release direction. In this specification, "substantially parallel to the release direction" includes the case of being completely parallel to the release direction, and the gradient angle with the release direction is less than 5°, preferably less than 2°, more preferably Less than 0.5°.

As shown in FIG. 1, 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 is composed of a keyboard and a mouse connected to the computer, and inputs numerical values, instructions, and the like to the arithmetic device 26 . The output device 24 is configured by a display or the like connected to the computer, and displays various data based on the results of computation by the computing device 26 and the like. As the storage device 25, a storage unit such as a RAM or ROM in a computer or a network server or the like is used. As the arithmetic unit 26, an arithmetic processing unit or the like composed of a CPU of a computer is used. As the control device 22, a control section or the like comprising a CPU of a computer is used.

The storage device 25 stores an analysis model, molten metal and mold temperature information, surface pressure data, galling risk area data, and the like, which will be described later. The storage device 25 also stores information on casting plans including molds, information on casting conditions, thermophysical properties and mechanical properties of molds, ejector pins, and molten metal, release plans such as the arrangement, diameter, and length of ejector pins, and mold opening. Resistance force acting on the fixed mold during operation, mold release force during mold release operation due to ejector pin extrusion (resistance force acting on the ejector pin during mold release operation), mold release timing, mold release stroke, mold It stores the coefficient of friction of the molten metal and the ejector pin, information related to calculations in the calculation device 26, programs for executing calculation processing for various analyzes such as casting analysis and structural analysis, and the like.

The calculation device 26 performs calculation processing according to the calculation program stored in the storage device 25 based on the data stored in the storage device 25 and the numerical values and instructions input from the input device 23 . The computing device 26 constitutes model creation means, casting analysis means, structure analysis means, surface pressure calculation means, surface pressure distribution output means, second portion identification means, and gradient angle setting means.

The model creation means divides the casting plan 3D CAD model, which is the shape data of the cavity created in the mold design stage, to create an analysis model for CAE analysis consisting of a plurality of elements.

The casting analysis means performs casting analysis using an analysis model and a calculation program for casting analysis, and acquires temperature information of the molten metal and the mold during the solidification and shrinkage process of the molten metal.

The structural analysis means performs structural analysis based on the temperature information to calculate the change in shape of the workpiece during the process of solidification and contraction of the molten metal, and reproduces the state of the workpiece clinging to the mold.

Based on the results of the structural analysis and the resistance acting on the ejector pin (the resistance acting on the mold), the surface pressure calculation means calculates the distance from the start of extrusion of the ejector pin (start of release of the workpiece) from the mold. Calculate the surface pressure generated at the contact surface between the mold and the workpiece in a plurality of mold release strokes in the process of separation.

The surface pressure distribution output means outputs surface pressure distributions exceeding a predetermined threshold value in a plurality of mold release strokes and displays them on the output device 24 .

The second portion identifying means identifies a second portion where galling may occur based on the obtained surface pressure distribution.

The gradient angle setting means sets the gradient angle of the second portion with respect to the release direction so that galling does not occur at least in the first portion.

<Method of designing molded product>
Hereinafter, the method for designing a molded product according to the present embodiment will be described by exemplifying the case where the die casting method is used as the casting method. The molded product design method according to the present embodiment can be performed using the above-described molded product design system 21 .

≪Manufacturing method of molded product≫
First, with reference to FIGS. 2 and 3, an example of a method for manufacturing a molded product by die casting will be described. FIG. 2 is a schematic diagram showing the configuration of a die casting machine 100 for manufacturing molded products. FIG. 3 is a diagram for explaining the outline of the procedure of the manufacturing process.

The die casting machine 100 includes a movable mold 110 (mold), a fixed mold 120 (mold), a cavity 101 , a plunger sleeve 130 , a plunger tip 132 and an ejector pin 114 . First, when the movable mold 110 is moved to the fixed mold 120 side by mold closing, the movable mold 110 and the fixed mold 120 are brought into a state where the mating surfaces of the movable mold 110 and the fixed mold 120 are aligned, and a cavity 101 is formed between the two molds. be. Then, the molten metal 103 in the plunger sleeve 130 is injected into the cavity 101 by pushing the plunger tip 132 . The molten metal 103 is cooled in the mold to solidify and shrink, and the workpiece W is obtained. Then, the movable mold 110 is separated from the fixed mold 120 by mold opening, and the workpiece W clinging to the movable mold 110 is pushed out by the ejector pins 114 to be separated from the mold. Then, the molded product P is obtained through processes such as gate cutting, cooling, and optional machining.

Note that the tip surface of the ejector pin 114 on the cavity 101 side reaches the cavity 101 through a through hole provided in the movable mold 110 and constitutes a part of the cavity surface.

In the manufacturing method described above, both the release of the workpiece W from the fixed mold 120 by opening the mold and the release of the workpiece W from the movable mold 110 by pushing out the ejector pin 114 are referred to as a release process or a release operation. However, the present embodiment particularly targets the latter. That is, in the present embodiment, the term "mold release process" or "mold release operation" refers to the process from the start of ejection of the ejector pin 114 (the start of release of the workpiece) to the separation of the workpiece W from the cavity surface of the movable mold 110 (that is, process from the mold release stroke of 0 mm to the mold release stroke when mold release is completed).

<<Occurrence of Galling>>
FIG. 4 is a diagram for explaining an example of a galling mechanism and countermeasures. 4, the ejector pin 114 is pushed out in the direction of the arrow indicated by symbol E. As shown in FIG.

As shown in the left diagram of FIG. 4, when forming the molding surface P1 substantially parallel to the mold release direction, if the inclination angle θ of the cavity surface 111 with respect to the mold release direction is small, the mold release of the work W will occur as described above. There is a possibility that a strong clinging force F continues to act inside. Then, galling X may occur on the molding surface P1 due to strong contact between the cavity surface 111 and the workpiece W during the mold release operation.

As shown in the diagram on the right side of FIG. 4, when the inclination angle θ of the cavity surface 111 is increased, the holding force F becomes smaller than when the inclination angle θ is small. The occurrence of galling X can be suppressed. Then, if necessary, after the casting process, a post-process such as machining is provided to process the work surface W1 to ensure the accuracy of the molding surface P1.

However, even when the inclination angle θ is small, galling X does not occur over the entire molding surface P1. That is, the galling X can occur in the vicinity of the joint with the work surface W1, which is substantially parallel to the release direction, and has an inclination angle θ of, for example, 10° or more, preferably 45° or more. Since the cavity surface 111 that forms such a connecting portion is a corner portion, there is a high possibility that stress will concentrate and the holding force F will increase.

Then, the inclination angle θ is set to the inclination angle θ at which galling X does not occur only at locations where galling X may occur, and at locations where galling X does not occur, the inclination angle θ is decreased and the casting stage is performed. If the molding surface P1 is formed by , it is possible to simplify the post-process by omitting the post-process or reducing the processed parts, and shortening the manufacturing process of the molded product, simplifying it, and reducing the cost.

The method for designing a molded product according to the present embodiment accurately identifies locations where galling X may occur, and adjusts the inclination angle θ of the location and other locations to prevent the occurrence of galling X. This is a method for proposing, at the design stage, a mold cavity shape that can simplify post-processes as much as possible while suppressing it.

≪Design of molded products≫
The method of designing a molded product according to the present embodiment is a method of designing the shape of the cavity 101 using computer simulation, and as shown in FIG. It comprises a step S8 and an optional ninth step S9.

-First step S1-
A first step S1 (step A, procedure A) is a step of dividing the shape data of the cavity 101 to create an analysis model composed of a plurality of elements. The analysis model is created by the computing device 26 as model creating means (see FIG. 1).

Specifically, the movable mold 110, the fixed mold 120, the ejector pin 114, and casting plan 3D CAD model data (hereinafter also referred to as "CAD data") regarding these materials are read. CAD data includes shape data of the cavity 101 . In this specification, the term “shape data of the cavity 101” includes shape data of the movable mold 110, the fixed mold 120, and the ejector pin 114 that constitute the cavity 101. FIG.

Then, the CAD data is divided to create an analysis model for CAE analysis consisting of a plurality of elements. The analysis model is a 3D mesh model, and can be created using, for example, commercially available automatic mesh creation software.

The size and shape of the element are not particularly limited, and are appropriately set according to the shape of the molded product, the material, and the level of calculation efficiency and calculation accuracy.

In this embodiment, a first analysis model for casting analysis and a second analysis model for structural analysis, which will be described later, are created.

Note that the first analysis model and the second analysis model may be the same 3D mesh model. Thereby, casting analysis and structural analysis can be performed by coupled analysis using the same 3D mesh model.

-Second step S2-
In the second step S2 (step B, procedure B), first, casting analysis including melt flow analysis, solidification analysis, etc. is performed using the first analysis model. Then, temperature information including temperature changes of each element of the movable mold 110, the fixed mold 120, the ejector pin 114, and the molten metal during the solidification and contraction process of the molten metal is acquired.

Casting analysis is performed using general-purpose casting simulation software.

Specifically, for example, in the software described above, the first analysis model is read, and the initial temperature of the molten metal, the casting conditions such as the inflow conditions, and the boundary conditions are set. Then, melt flow analysis and solidification analysis are performed. Specifically, the time from the start of pouring of the molten metal to the end of the aging treatment (the completion of the molded product) is divided into a plurality of time steps. Then, in each element of the first analysis model, the calculation is repeatedly performed for each time step from the start of pouring of the molten metal to the end of the aging treatment, and the temperature of each element at each time step is calculated. Thus, temperature information for each time step in each element of the first analysis model is obtained.

The elapsed time of each time step is not particularly limited, and can be appropriately set according to the type and shape of the molded product, mold material, alloy material, casting conditions, required design accuracy, and the like. Also, for example, in the manufacturing process of one type of molded product, the elapsed time of a different time step may be set for each stage. In particular, it is desirable to make the elapsed time of the solidification shrinkage process of the molten metal and the time steps before and after it shorter than the elapsed time of the time steps of other processes. As a result, the surface pressure can be calculated with higher accuracy. In addition, the amount of temperature information that is not related to the calculation of the surface pressure can be suppressed to improve calculation efficiency.

Next, the temperature information of each element of the first analysis model obtained as described above is used as the temperature information for each time step at the node of each element of the second analysis model, that is, the temperature information of each node of the second analysis model. set. Temperature information of each node of the second analysis model is written as text data and stored in the storage device 25 .

-Third step S3-
In the third step S3 (step C, procedure C), structural analysis is performed using the second analysis model based on the temperature information acquired in the second step S2. Then, the change in shape of the work W during the solidification and contraction process of the molten metal is calculated, and the state of the work W clinging to the cavity surface 111 of the movable mold 110 is reproduced.

Structural analysis can be performed by a general CAE analysis method.

-Fourth step S4-
In the fourth step S4 (step D, procedure D), during the mold release operation for pushing out the workpiece W, that is, during a plurality of mold release strokes from the start of extrusion of the ejector pin 114 to the separation of the workpiece W from the cavity surface 111, the cavity A surface pressure generated at the contact surface between the surface 111 and the work surface W1 is calculated.

Specifically, the surface pressure is calculated based on the structural analysis result obtained in the third step S3 and the resistance acting on the ejector pin 114 during the mold release operation (resistance acting on the mold). do. The resisting force acting on the ejector pin 114 is determined by using the results of an actual test obtained by actually measuring the load acting on the ejector pin 114 during the mold release process using, for example, a strain gauge type sensor attached to the ejector pin 114. good too. Also, the resistance may be set using, for example, a database accumulated so far by various CAE analyses.

In addition, the surface pressure changes according to the release amount. In other words, different mold releasing strokes have different values of the nodes where the surface pressure is generated and the surface pressure. Therefore, in a plurality of mold release strokes during the mold release operation, the shape of the work W is traced, preferably at each fixed mold release stroke, and the surface pressure generated at the contact surface between the cavity surface 111 and the work surface W1 is measured. calculate. When the surface pressure is calculated for each predetermined mold release stroke, it is not intended to be limited, but from the viewpoint of suppressing the amount of calculation while ensuring sufficient calculation accuracy, it is possible to calculate, for example, every 0.5 mm to 2 mm. can.

- Fifth step S5 -
Next, in the fifth step S5 (step E, procedure E), the distribution of surface pressures exceeding a predetermined threshold among the surface pressures obtained in the plurality of mold release strokes in the fourth step S4 is output.

At nodes where the surface pressure is zero, the cavity surface 111 and the work surface W1 are not in contact, and at nodes where the surface pressure is generated, the cavity surface 111 and the work surface W1 are in contact. can. Even when surface pressure is generated, that is, when the cavity surface 111 and the work surface W1 are in contact with each other, it is considered that scuffing does not occur if the surface pressure value is equal to or less than a predetermined threshold value. That is, it is considered that galling occurs when the surface pressure exceeds a predetermined threshold value.

The predetermined threshold value can be determined, for example, based on the relationship between the surface pressure and the actual occurrence of galling in a molded product having a predetermined inclination angle, which is obtained in advance by an experimental method. Specifically, for example, the information on the surface pressure calculated by the CAE analysis as described above and the information on the external appearance of the work for verification manufactured using the actual machine are compared to obtain the correlation between the two in advance. Then, a predetermined threshold value is set based on the correlation. As a result, consistency with the actual machine can be ensured in the CAE analysis, and analysis accuracy can be improved.

-Sixth step S6-
In a sixth step S6 (step F, procedure F), a galling risk area (second portion) where galling may occur is specified based on the surface pressure distribution output in the fifth step S5.

The surface pressure distribution changes with the release amount. Some parts come into contact at the beginning of the mold release operation, and some parts come into contact midway due to shrinkage during the mold release operation, changes in workpiece posture, and the like. A change in surface pressure distribution indicates a region where galling is likely to occur among such locations.

Since the surface pressure distribution changes with the release amount, it is preferable to calculate the range of the release strokes in which the surface pressure distribution occurs in that region based on the surface pressure distribution for each of a plurality of release strokes. . Since the range of the release stroke is a range in which the surface pressure exceeding the predetermined threshold continues to act, it corresponds to the length of galling in the release direction. Therefore, by determining the range of the mold release stroke, the length of the galling in the mold release direction can be specified, and the accuracy of specifying the galling risk area is improved.

-Seventh step S7-
In the seventh step S7 (step G, procedure G), the required gradient angle of the galling risk area is set so that galling does not occur at least at the first portion. Specifically, the required gradient angle of the galling risk area is set so that galling does not occur or is suppressed within a predetermined range in the galling risk area. Note that "galling is suppressed within a predetermined range" refers to a state in which galling occurs in the galling risk area within a range in which galling does not occur in the first portion.

As described above, by going through the first step S1 to the seventh step S7, the surface pressure generated on the contact surface between the mold and the workpiece during the mold release process exceeds a predetermined threshold in a plurality of mold release strokes. Output the surface pressure distribution. As a result, the mold release process can be divided into a plurality of parts, and changes in the surface pressure distribution in the corresponding areas can be evaluated. Further, by setting the inclination angle of the galling-probable region so that galling does not occur in the first portion, it is possible to obtain a molded product in which galling is suppressed at least in the first portion. If the first portion is the entire surface of the molded product, the gradient angle of the galling-probable region must be set to a gradient angle that does not cause galling.

- Eighth step S8 and ninth step S9 -
It is preferable that the method for designing a molded product according to the present embodiment further includes an eighth step S8 (step H) of determining whether or not the shape data of the cavity needs to be changed after the seventh step S7.

If it is determined in the eighth step S8 that it is not necessary to change the shape data of the cavity, the optimum final shape of the cavity 101 has already been obtained, so the method of designing the molded product ends.

If it is determined in the eighth step S8 that it is necessary to change the shape data of the cavity, the process proceeds to the ninth step S9, and the inclination angle of the galling risk area set in the seventh step S7 is reflected in the analysis model. . Then, the first step S1 to the eighth step S8 are repeated until it is determined in the eighth step S8 that the shape data of the cavity need not be changed. Thus, the optimum final shape of cavity 101 is determined.

In this way, by repeating the desk study while adjusting the inclination angle, the number of prototype molds can be reduced, and the optimum final shape of the cavity 101 can be determined more quickly and at a lower cost.

In the final shape, the inclination angle of at least a part of the cavity surface 111 forming the part other than the galling risk area may be set smaller than the inclination angle of the cavity surface 111 forming the galling risk area.

Galling is less likely to occur in areas other than the galling risk area. Therefore, by setting the inclination angle of at least a part of the cavity surface 111 forming the part other than the galling risk area to be smaller than the inclination angle of the cavity surface forming the galling risk area, excessive thickening is prevented. It is possible to contribute to weight reduction of the molded product by suppressing it.

Further, when the first part and the galling risk area do not overlap, in the final shape, the inclination angle of the cavity surface 111 forming the first part is the inclination of the cavity surface 111 forming the galling risk area. It may be set smaller than the angle.

The first portion may have to be formed as a plane substantially parallel to the release direction. In this configuration, the inclination angle of the cavity surface 111 forming the first portion is set to a desired inclination angle smaller than the inclination angle of the cavity surface 111 in the galling-prone area, so that the desired first portion can be obtained in the casting stage. can be formed. In this way, the occurrence of galling at the first portion can be suppressed, and the post-casting process can be omitted, thereby simplifying the method of manufacturing the molded product.

<Molded product design program and its recording medium>
Each step of the above molded product design method may be programmed as a molded product design program. That is, the molded product design program according to the present embodiment can be a program that causes a computer to execute at least the steps S1 to S7, preferably the steps S1 to S9. This design program can be executed by the control device 22 and the arithmetic device 26 while being stored in the storage device 25 . In addition, the design program is not limited to being stored in the storage device 25, but can be recorded in various well-known computer-readable recording media such as an optical disc medium and a magnetic tape medium. The design program can be executed by loading such a recording medium in the reading device of the control device 22 and reading the design program.

<Example>
Next, specific examples will be described.

Using the method of designing a molded product according to the present disclosure, a molded product was designed in the case of manufacturing the suspension tower 200 shown in FIGS. 6 to 8 by a die casting method. Incidentally, when referring to the direction of the suspension tower 200, it is as shown in FIG. 6 for the sake of convenience. The suspension tower 200 is a molded product whose main material is an aluminum alloy.

As shown in FIGS. 6 to 8, the suspension tower 200 has a first seat surface 201, a second seat surface 202, a third seat surface 203, a fourth seat surface 204, and a fifth seat surface. A surface 205 and a sixth seating surface 206 are provided. Since upper links (other parts) are fastened to these bearing surfaces, the occurrence of galling is not allowed from the viewpoint of ensuring surface accuracy. In the following description, the first seat surface 201 may be referred to as the front side seat surface, and the sixth seat surface 206 may be referred to as the rear side seat surface.

As shown in FIG. 7, the first seat surface 201 includes a first main body portion 201A formed of a circular or partially circular surface, a first peripheral portion 201B, and surrounding the first main body portion 201A and the first peripheral portion 201B. and a first outer peripheral portion 201C. The first outer peripheral portion 201C has an R shape in a cross section perpendicular to the first main body portion 201A.

Further, as shown in FIG. 8, the sixth seat surface 206 includes a sixth main body portion 206A and a sixth peripheral portion 206B, which are circular or partially circular surfaces, and the sixth main body portion 206A and the sixth peripheral portion 206B. and a sixth outer peripheral portion 206C that surrounds the The sixth outer peripheral portion 206C has an R shape in a cross section perpendicular to the sixth main body portion 206A.

The second seat surface 202 to the fifth seat surface 205 also have the same configuration as the first seat surface 201 and the sixth seat surface 206 . The first body portion 201A of the first seat surface 201, the sixth body portion 206A of the sixth seat surface 206, and the body portions of the second to fifth seat surfaces 202 to 205 may be collectively referred to simply as the body portion. The first peripheral portion 201B of the first seat surface 201, the sixth peripheral portion 206B of the sixth seat surface 206, and the peripheral portions of the second to fifth seat surfaces 202 to 205 may be collectively referred to simply as peripheral portions. The first outer peripheral portion 201C of the first seat surface 201, the sixth outer peripheral portion 206C of the sixth seat surface 206, and the outer peripheral portions of the second to fifth seat surfaces 202 to 205 may be collectively referred to simply as outer peripheral portions.

The optimum final shape of the suspension tower 200 was examined by executing the above-described steps with the suspension tower 200 as a target. The results of the analysis are shown in FIGS. 9-12.

9 and 12 show output results of surface pressure distribution. Then, at the nodes (sometimes referred to as "measurement points") denoted by symbols A1 to A14 and symbols B1 to B10 on the front side seat surface and the rear side seat surface shown in FIG. FIG. 10 and FIG. 11 show changes in the surface pressure when changed. Note that the analysis of FIGS. 9 to 11 was performed at an inclination angle of 2°.

As shown in FIGS. 10 and 11, when comparing the radius of the R shape of 3 mm and 5 mm on both the front seat surface and the rear seat surface, the radius of 5 mm It was found that the contact pressure generally tends to decrease compared to the case of 3 mm. Therefore, it was decided to set the radius of the rounded shape at the outer peripheral portion of the first seat surface 201 to the sixth seat surface 206 to 5 mm. The results shown in FIGS. 12 and 14 were obtained by setting the radius of the R shape at the outer peripheral portion to 5 mm.

FIG. 12 shows the output results of the surface pressure distribution when the slope angles of the main body and the peripheral portion are the same for the front side seat surface and the rear side seat surface, and are set to 2° or 0.5°. there is Note that the inclination angle was changed with the center of the circle of the main body as the starting point.

As indicated by the dashed line in the output results of FIG. 12 (with a mold release stroke of 10 mm), there is a tendency that the position of high surface pressure moves toward the main body by reducing the inclination angle from 2° to 0.5°. was taken. It should be noted that, for example, the area indicated by symbol X1 in FIG. 12 as an example has a high surface pressure, so it can be determined as an area where scuffing is likely to occur.

Although not shown in the figure, a comparison of the output results of the surface pressure distribution at each release stroke of 1 mm from St 1 mm to 10 mm shows that the smaller the inclination angle, the better for both the front side seat surface and the rear side seat surface. There was a tendency for positions with high contact pressure to remain over a long St.

When the slope angle is small compared to when the slope angle is large, both the front side seat surface and the rear side seat surface move toward the main body from the boundary between the outer peripheral portion and the peripheral portion. , there was a tendency for a region with high surface pressure to be seen in a longer range. Based on the surface pressure distribution output results for each mold release stroke, areas where galling is likely to occur were identified.

13A and 13B are graphs for explaining a method of examining conditions for setting a slope angle. For example, consider a node that is not in the galling risk area when the gradient angle is 2°, but is in the galling risk region when the gradient angle is 0.5°. In the case of an inclination angle of 0.5°, the length of galling that occurs can be considered to be Q, assuming that the potential galling occurrence area exists within the mold release stroke Q at the node.

In this case, when the inclination angle is 2°, the surface pressure at the node is equal to or less than the threshold regardless of the release amount. On the other hand, when the inclination angle is 0.5°, the surface pressure at the contact exceeds the threshold within the mold releasing stroke Q or less. In other words, on the work surface W1, it is considered that galling does not occur in the area beyond the release stroke Q, that is, in the area on the main body side in the release direction with respect to the area where galling with the galling length Q occurs.

Therefore, since there is a high possibility that galling will not occur in areas other than the galling risk area, galling can be effectively suppressed simply by setting the required angle for the galling risk area in consideration of the galling length. .

FIG. 14 shows some of the optimal final shapes. As shown in FIG. 14, in the first peripheral portion 201B of the first seating surface 201 and the third peripheral portion 203B of the third seating surface 203, when the inclination angle is set to at least 0.5°, the result including the galling-probable area is obtained. Therefore, these inclination angles were set to 2° which does not cause galling. On the other hand, in the case of the first main body portion 201A of the first bearing surface 201 and the third main body portion 203A of the third bearing surface 203, even when the inclination angle is 0.5°, the result is obtained that the galling risk region is not included. , their slope angles were set to 0.5°.

When a mold was actually produced with the above-described setting of the inclination angle and a prototype of the suspension tower 200 was produced, galling occurred in the first main body portion 201A of the first bearing surface 201 and the third main body portion 203A of the third bearing surface 203. could not be seen. In addition, since the first body portion 201A of the first seat surface 201 and the third body portion 203A of the third seat surface 203 are manufactured with an inclination angle of 0.5°, the required surface accuracy must be secured at the casting stage. can be done, eliminating the need for a post-process.

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

In the above-described embodiment, the movable mold 110 has an ejector mechanism, and the work W is released from the cavity surface 111 of the movable mold 110 by ejecting the ejector pin 114 . The present disclosure is not limited to the above configuration, and is also applicable to the release operation of the work W from a general mold that does not have an ejector mechanism, such as the release operation of the work W from the fixed mold when the mold is opened. Applicable. For example, when the release operation of the work W from the fixed mold 120 at the time of mold opening is targeted, the time from the start of mold opening (start of release of the work) to the separation of the work W from the cavity surface of the fixed mold 120 The configuration of the above embodiment may be applied with the process being a mold release process or a mold release operation. In this case, the resistance acting on the fixed mold 120 may be used to calculate the surface pressure in the fourth step S4.

The present disclosure provides a molded product design method, a design system, a design program, and a molded product that can accurately and easily design a molded product that suppresses the occurrence of galling and forms a desired molding surface in the casting stage. It is extremely useful because it can provide a recording medium.

21 Design system 26 Arithmetic device (model creation means, casting analysis means, structural analysis means, surface pressure calculation means, surface pressure distribution output means, second part identification means, gradient angle setting means)
101 cavity 103 molten metal 110 movable mold (mold)
111 cavity surface (of movable mold) 114 ejector pin (mold)
120 fixed mold (mold)
200 Sustower (molded product)
201 first bearing surface (first part)
202 Second bearing surface (first part)
203 Third bearing surface (first part)
204 Fourth seating surface (first part)
205 5th bearing surface (1st part)
206 No. 6 bearing surface (first part)
F Holding force W Work W1 Work surface P Molded product P1 Molded surface S1 First process (step A, procedure A)
S2 second step (step B, procedure B)
S3 Third step (step C, procedure C)
S4 Fourth step (step D, procedure D)
S5 Fifth step (step E, procedure E)
S6 sixth step (step F, procedure F)
S7 7th step (step G, procedure G)
S8 Eighth step (step H)
S9 Ninth process X Galling X1 Galling risk area (second part)
θ slope angle

Claims (10)

In a casting method in which a molten metal is injected into a cavity of a mold, and the workpiece obtained by solidifying and shrinking the molten metal is released from the mold to obtain a molded product having a first part, the shape of the molded product is A method of designing using computer simulation, comprising:
Step A of creating an analysis model consisting of a plurality of elements by dividing the shape data of the cavity;
A step B of obtaining temperature information of the molten metal and the mold during the solidification and shrinkage process of the molten metal by performing casting analysis using the analysis model;
a step C of calculating a change in the shape of the workpiece during the process of solidification and shrinkage of the molten metal by performing structural analysis based on the temperature information, and reproducing a state in which the workpiece clings to the mold;
Based on the results of the structural analysis and the resistance acting on the mold, the mold and the workpiece are separated from the mold during a plurality of mold release strokes from the start of releasing the workpiece to the separation of the workpiece from the mold. A step D of calculating the surface pressure generated on the contact surface of
a step E of outputting the surface pressure distribution exceeding a predetermined threshold in the plurality of mold release strokes;
a step F of identifying a second portion where galling may occur based on the distribution of the surface pressure;
A method for designing a molded product, comprising a step G of setting a necessary inclination angle with respect to the release direction of the second portion so that galling does not occur at least in the first portion. In claim 1,
The identification of the second portion in the step F is performed by calculating the range of release strokes in which the distribution of the contact pressure occurs based on the distribution of the contact pressure for each of the plurality of release strokes. A method for designing a molded product, comprising specifying the length of the mold release direction. In claim 1 or claim 2,
The predetermined threshold value is determined based on the relationship between the surface pressure and the actual occurrence of galling in the molded product having a predetermined inclination angle, which is obtained in advance by an experimental method. design method. In any one of claims 1 to 3,
After the step G, further comprising a step H of determining whether or not the shape data of the cavity needs to be changed,
When it is determined in the step H that the shape data of the cavity needs to be changed, the necessary slope angle set in the step G is reflected in the analysis model, and the steps A to H are performed. 3. A method of designing a molded product, wherein the final shape of the cavity is repeatedly determined in step H until it is determined that the shape data of the cavity need not be changed. In claim 4,
In the final shape, the inclination angle of at least a part of the cavity surface forming the part other than the second part is set smaller than the inclination angle of the cavity surface forming the second part. product design method. In claim 4 or claim 5,
The first portion and the second portion do not overlap,
A method of designing a molded product, wherein, in the final shape, a slope angle of a cavity surface forming the first portion is set smaller than a slope angle of a cavity surface forming the second portion. In claim 6,
A method for designing a molded product, wherein the first portion is a seat surface to which another part is fastened. In a casting method for obtaining a molded product having a first part by releasing a workpiece formed by solidifying and contracting a molten metal injected into a mold cavity from the mold, the shape of the molded product is simulated using a computer. A system for designing
model creation means for creating an analysis model consisting of a plurality of elements by dividing the shape data of the cavity;
Casting analysis means for acquiring temperature information of the molten metal and the mold during the solidification and shrinkage process of the molten metal by performing casting analysis using the analysis model;
Structural analysis means for calculating a shape change of the work in the process of solidification and shrinkage of the molten metal by performing a structural analysis based on the temperature information, and reproducing a state in which the work is clinging to the mold;
Based on the results of the structural analysis and the resistance acting on the mold, the mold and the workpiece are separated from the mold during a plurality of mold release strokes from the start of releasing the workpiece to the separation of the workpiece from the mold. a surface pressure calculation means for calculating the surface pressure generated on the contact surface of the
surface pressure distribution output means for outputting the surface pressure distribution exceeding a predetermined threshold in the plurality of mold release strokes;
a second portion identifying means for identifying a second portion where galling may occur based on the surface pressure distribution;
and a gradient angle setting means for setting a necessary gradient angle with respect to the release direction of the second portion so that galling does not occur at least in the first portion. In a casting method for obtaining a molded product having a first part by releasing a workpiece formed by solidifying and contracting a molten metal injected into a mold cavity from the mold, the shape of the molded product is simulated using a computer. A program for designing a
to the computer,
A procedure A for creating an analysis model consisting of a plurality of elements by dividing the shape data of the cavity;
A procedure B for acquiring temperature information of the molten metal and the mold during the solidification and shrinkage process of the molten metal by performing casting analysis using the analysis model;
A procedure C of calculating a shape change of the work in the process of solidification and contraction of the molten metal by performing structural analysis based on the temperature information, and reproducing a state of the work clinging to the mold;
Based on the results of the structural analysis and the resistance acting on the mold, the mold and the workpiece are separated from the mold during a plurality of mold release strokes from the start of releasing the workpiece to the separation of the workpiece from the mold. A procedure D for calculating the surface pressure generated on the contact surface of
a step E of outputting the surface pressure distribution exceeding a predetermined threshold in the plurality of mold release strokes;
a step F of identifying a second portion where galling may occur based on the surface pressure distribution;
A program for designing a molded product, characterized by executing a procedure G of setting a necessary inclination angle with respect to a release direction of the second portion so that galling does not occur at least in the first portion. A computer-readable recording medium recording the molded product design program according to claim 9 .

Images