Intermediate shape calculation apparatus and intermediate shape calculation method

Abstract

To calculate an intermediate shape of a forged product so as to reduce molding energy which is generated during forging process.SOLUTION: An intermediate shape calculation apparatus 1 calculates molding energy required from an initial shape to a final shape, using design data of the initial shape of a forged product and design data before change of an intermediate shape, and design data of the final shape. The intermediate shape calculation apparatus 1 calculates an amount of change in shape from the initial shape to the final shape. The intermediate shape calculation apparatus 1 determines convergence of an objective function to be determined from the molding energy and the amount of change in shape, calculates, when the objective function is not converged, an intermediate shape so as to reduce the objective function, and updates the design data before change to design data after change of the calculated intermediate shape on the basis of a shape derivative defined by a level set function.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an intermediate shape calculation device and an intermediate shape calculation method. [Background technology]

[0002] Patent Document 1 discloses a method for determining the shape of a forged product, which determines an intermediate shape in a previous process from the final shape of the forged product (or an intermediate shape in an intermediate process). In Patent Document 1, the shapes of a plurality of existing forged products whose shapes corresponding to a predetermined process are known and the shapes of each of them in the previous process are stored in a database.

[0003] In this method, the similarity between a new forging and a previously stored already-forged product is evaluated, and the shape in the previous process of the already-forged product with the highest similarity is selected as the shape in the previous process of the new forging. Patent Document 1 also describes a method for determining the shape in the previous process of the new forging by selecting multiple shapes when selecting the shape in the previous process of the already-forged product and synthesizing the shapes in the previous process of the multiple selected already-forged products. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-234535 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the technology of Patent Document 1, unless data of existing forgings similar to the new forging are stored in the database, it is not possible to determine a good intermediate shape of the new forging in the previous process. Also, a shape obtained by combining the shapes of the previous processes of multiple existing forgings is not necessarily capable of reducing the forming energy generated in the forging process of the new forging.

[0006] The present invention has been made in consideration of the above problems, and one of the objects of the present invention is to calculate an intermediate shape of a forged product that can reduce the forming energy generated in the forging process. [Means for solving the problem]

[0007] An intermediate shape calculation device according to one embodiment is an intermediate shape calculation device that repeatedly calculates design data indicating an intermediate shape of a forged product and specifies design data indicating a final intermediate shape, An acquisition unit that acquires design data of an initial shape of a forged product, design data before the change of the intermediate shape, and design data of a final shape of the forged product; a forming energy calculation unit that calculates a forming energy from the initial shape to the final shape using each acquired design data; a displacement amount calculation unit that calculates a shape displacement amount from the initial shape to the final shape; a determination unit that determines whether an objective function determined from the forming energy and the shape displacement amount has converged depending on whether a change in the objective function is equal to or smaller than a predetermined value; If the objective function has not converged, decrease the objective function. Intermediate shape An intermediate shape calculation unit that calculates an updating unit that updates the pre-modification design data to post-modification design data of a calculated intermediate shape based on a shape derivative defined by a level set function; It is equipped with the following.

[0008] An intermediate shape calculation method according to one embodiment is an intermediate shape calculation method for repeatedly calculating design data indicating an intermediate shape of a forged product and specifying design data indicating a final intermediate shape, The computer Obtaining design data of an initial shape of a forging, design data before the change of the intermediate shape, and design data of a final shape; Calculating a forming energy from the initial shape to the final shape using each acquired design data; Calculating a shape displacement amount from the initial shape to the final shape; determining whether or not a change amount of an objective function calculated from the forming energy and the shape displacement amount is equal to or less than a predetermined value; If the objective function has not converged, decrease the objective function. Intermediate shape and calculating updating the pre-modification design data to post-modification design data of the calculated intermediate shape based on a shape derivative defined by a level set function; Execute. Effect of the Invention

[0009] According to the present invention, it is possible to calculate an intermediate shape of a forged product that can reduce the forming energy generated in the forging process. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a functional configuration of an intermediate shape calculation device according to an embodiment. [Diagram 2] FIG. 4 is a flow diagram illustrating an intermediate shape calculation method according to the embodiment. [Diagram 3] 1A to 1C are diagrams illustrating changes in shape of a forged product during a forging process. [Figure 4] 13 is a diagram for explaining the amount of displacement at points A and B when an optimized intermediate shape is formed. FIG. [Diagram 5] FIG. 13 is a diagram illustrating the forming energy generated in the forging process when an optimized intermediate shape is formed. [Figure 6] FIG. 13 is a diagram illustrating the load generated in the forging process when forming an optimized intermediate shape. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. In addition, in each drawing, the same elements are given the same reference numerals, and duplicate explanations are omitted as necessary.

[0012] Fig. 1 is a block diagram showing a functional configuration of an intermediate shape calculation device 1 according to an embodiment. The intermediate shape calculation device 1 calculates design data of an intermediate shape between an initial shape, which is a shape of a forged product before forging, and a final shape, which is a shape after forging. The intermediate shape calculation device 1 is used, for example, in product design in a forging process of vehicle parts.

[0013] First, the forging process will be described. In the embodiment, the forging process uses hot die forging in which a billet is molded using a die. The billet is a raw material for vehicle parts. For example, a bar-shaped or wire-shaped metal material processed to a predetermined size is used as the billet.

[0014] Usually, when a product is manufactured by forging, the forging process is carried out in stages using a die having an intermediate shape in an intermediate process. The forging process includes, for example, a first intermediate process, a second intermediate process, and a finishing process. The first intermediate process is a so-called crushing process in which a billet having an initial shape is crushed and deformed into a first intermediate shape.

[0015] The second intermediate process is a process in which the crushed billet is deformed into a raw material having a second intermediate shape by preforming using a rough mold. The finishing process is a process in which the raw material is deformed into a final shape using a finishing mold. In this disclosure, the first intermediate process and the second intermediate process are also collectively referred to as "intermediate processes", and the first intermediate shape and the second intermediate shape are also collectively referred to as "intermediate shapes".

[0016] 1, the intermediate shape calculation device 1 includes a processing unit 10, a storage unit 20, and an input / output unit 30. The processing unit 10 includes a shape calculation function and a three-dimensional data generation function. The shape calculation function is a function that uses so-called topology optimization to calculate setting data for an intermediate shape for reducing forming energy generated by forging.

[0017] In this embodiment, the shape calculation function iteratively calculates design data representing intermediate shapes to identify design data representing a final intermediate shape for minimizing the forming energy, which means the average compliance generated by the deformation of the material.

[0018] The input / output unit 30 may include a display device such as a screen, and an input device such as a keyboard. The input / output unit 30 may be a touch panel in which the display device and the input device are integrated. The input / output unit 30 is used to input design values ​​such as production conditions.

[0019] The storage unit 20 includes a non-volatile memory such as a flash memory or an SSD (Solid State Drive). Various programs for implementing the functions provided in the embodiment are stored in the storage unit 20. In addition, a calculation formula 21 for calculating an intermediate shape is stored in a readable / writable area of ​​the storage unit 20.

[0020] The storage unit 20 also includes a volatile memory such as a RAM (Random Access Memory), and temporarily stores information when the processing unit 10 is operating. The processing unit 10 is a processor that controls the hardware of the intermediate shape calculation device 1. The processing unit 10 loads a program from the storage unit 20 into the memory and executes it. In this way, the processing unit 10 realizes some or all of the above-mentioned functions for calculating the intermediate shape.

[0021] The processing unit 10 includes an acquisition unit 11, a forming energy calculation unit 12, a displacement amount calculation unit 13, a judgment unit 14, an intermediate shape calculation unit 15, an update unit 16, and a three-dimensional data generation unit 17. The acquisition unit 11, the forming energy calculation unit 12, the displacement amount calculation unit 13, the judgment unit 14, the intermediate shape calculation unit 15, and the update unit 16 realize a shape calculation function, and the three-dimensional data generation unit 17 realizes a three-dimensional data generation function.

[0022] The acquisition unit 11 acquires design data of the initial shape of the forged product, design data before change of the intermediate shape, and design data of the final shape. The forming energy calculation unit 12 calculates the forming energy required to transform the initial shape into the final shape using each acquired design data. The displacement amount calculation unit 13 calculates the amount of shape displacement from the initial shape to the final shape.

[0023] A determination unit 14 determines the convergence of an objective function calculated from the forming energy and the shape displacement amount depending on whether or not the change amount of the objective function is equal to or less than a predetermined value. An intermediate shape calculation unit 15 calculates an intermediate shape that reduces the objective function when the objective function has not converged. An update unit 16 updates the pre-change design data to post-change design data of the calculated intermediate shape based on a shape derivative defined by a level set function.

[0024] The three-dimensional data generating unit 17 is, for example, three-dimensional CAD software, and draws a three-dimensional model of the forged product. For example, the three-dimensional data generating unit 17 converts design data of an intermediate shape generated by a shape calculation function into a point cloud indicated by three-dimensional coordinates included in the three-dimensional point cloud data. The three-dimensional data generating unit 17 generates three-dimensional CAD data of the forged product by mapping the converted three-dimensional coordinates onto a three-dimensional coordinate system. The generated three-dimensional CAD data is output to a display device of the input / output unit 30, for example.

[0025] Each of the components of the intermediate shape calculation device 1 may be realized by dedicated hardware. Also, some or all of the components may be realized by general-purpose or dedicated circuits, processors, etc., or a combination of these. These may be configured by a single chip, or may be configured by multiple chips connected via a bus. Some or all of the components may be realized by a combination of the above-mentioned circuits, etc., and programs. Also, as the processor, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an FPGA (Field-Programmable Gate Array), a quantum processor (quantum computer control chip), etc. may be used.

[0026] 2 is a flow diagram illustrating an intermediate shape calculation method according to an embodiment. In the following description, in order to facilitate understanding of the technology, a product having an axisymmetric three-dimensional structure, such as a drive pinion, is used as an example.

[0027] In step S11, the acquisition unit 11 sets design data for the initial shape of the forged product, initial design data for the first intermediate shape, initial design data for the second intermediate shape, and design data for the final shape. These design data can be acquired, for example, from a higher-level product design management system that performs product design.

[0028] "Initial design data" refers to design data that is initially provided to start the intermediate shape calculation process. In other words, the initial design data is design data that indicates a shape before the shape is changed by the intermediate shape calculation process executed by the intermediate shape calculation device 1. In this embodiment, the initial design data of the first intermediate shape is provided with design data of a billet shape that is the same as the initial shape, and the initial design data of the second intermediate shape is provided with design data of a shape that is the same as the final shape after the finishing process. However, the present invention is not limited to this, and any shape may be set as the initial design data.

[0029] Next, the forming energy calculation unit 12 calculates the forming energy from the initial shape to the final shape using each acquired design data (step S12). The forming energy calculation unit 12 calculates the surface force t i The forming energy required for each process of the boundary ∂Ω defined in is regarded as the work done by an external force, and the forming energy J from the initial shape to the final shape is calculated by the following formula (1). comp can be calculated.

[0030]

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[0031] The forming energy calculation unit 12 can also calculate the forming energy for each process as follows. In this case, first, the amount of displacement between each shape is calculated. Here, the linear elastic deformation of the three-dimensional shape Ω is expressed by the following formulas (2) and (3) using the displacement field u. Formulas (2) and (3) are also called state equations, elastic equations, Navier-Cauchy equations, etc. The displacement field u is obtained by performing a numerical analysis of formulas (1) and (2) using the finite element method.

[0032]

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[0033]

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[0034] Then, the forming energy calculation unit 12 uses the calculated displacement to calculate the minimum forming energy that can be generated when the three-dimensional shape Ω is deformed. The forming energy calculation unit 12 calculates a first forming energy for deforming from the initial shape to the intermediate shape, and a second forming energy for deforming from the intermediate shape to the final shape. When the forging process includes a plurality of intermediate processes, the forming energy generated when deforming from the initial shape to the shape after the first intermediate process is defined as the first forming energy, and the forming energy generated when deforming from the shape after the last intermediate process to the final shape is defined as the second forming energy.

[0035] In this embodiment, the forming energy calculation unit 12 calculates the forming energy generated when transforming from the initial shape to the first intermediate shape, i.e., from the billet shape to the shape after the squeezing process, as the first forming energy, calculates the forming energy generated when transforming from the second intermediate shape to the final shape, i.e., from the shape after the roughing process to the shape after the finishing process, as the second forming energy, and calculates the forming energy generated when transforming from the first intermediate shape to the second intermediate shape as the third forming energy.

[0036] The objective function of the forming energy J can be expressed by the following formula (4). Here, ε(u)=(∇u+∇uT) / 2. The forming energy calculation unit 12 calculates the first forming energy, the second forming energy, and the third forming energy using the following formula (4).

[0037] The forming energy calculation unit 12 calculates the total value of forming energy generated when changing from the initial shape to the final shape. In this embodiment, the forming energy calculation unit 12 calculates the total value of forming energy by integrating the calculated first forming energy, second forming energy, and third forming energy. When there is one intermediate process, the shape calculation unit 622 calculates the total value of forming energy by integrating the first forming energy and the second forming energy.

[0038]

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[0039] Next, the displacement calculation unit 13 calculates the shape displacement J from the initial shape to the final shape using equation (5). disp is calculated (step S13).

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[0040] In step S14, an objective function is calculated from the calculated forming energy and the amount of displacement. This objective function is the sum of the normalized values ​​of the forming energy and the amount of shape displacement. That is, the objective function J is expressed by the following formula (6).

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[0041] In step S15, the determination unit 14 determines the convergence of the objective function according to whether the change in the objective function J obtained by formula (6) is equal to or less than a predetermined value. In the present disclosure, the processes from step S12 to S15 are also referred to as "convergence determination process." The convergence of the change in the objective function J means the completion of optimization of the intermediate shape. If the change in the objective function J is greater than a predetermined value, the determination unit 14 determines that the forming energy has not converged (S15, NO), and proceeds to step S16. Note that if step S15 is the first time, the determination unit 14 determines that the forming energy has not converged (S15, NO), and proceeds to step S16.

[0042] In step S16, the intermediate shape calculation unit 15 calculates an intermediate shape that reduces the objective function J. In this embodiment, the intermediate shape calculation unit 15 calculates the intermediate shape that reduces the objective function by using a sensitivity calculation based on the adjoint variable method. For the sensitivity calculation, a shape derivative of the following formula (7), which is the design sensitivity of the objective function J, is used. For the design sensitivity of the level set method, the steepest descent direction is used.

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[0043] In step S17, the update unit 16 updates the pre-modification design data to post-modification design data of the calculated intermediate shape based on the shape derivative defined by the level set function. Specifically, the update unit 16 uses the calculated intermediate shape to calculate post-modification design data of the intermediate shape from the shape derivative defined by the level set function. The post-modification shape of the intermediate shape is calculated by a reaction-diffusion equation shown in the following formula (8). The constant K can be expressed by, for example, a stiffness matrix. Furthermore, the constant τ defines the complexity of the shape.

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[0044] When the update unit 16 calculates the modified design data of the intermediate shape, the process proceeds to step S12. The forming energy calculation unit 12 calculates the forming energy and the displacement amount using the modified design data of the intermediate shape, and further executes the convergence determination process. The convergence determination process is repeatedly executed until the objective function J converges.

[0045] In step S15, if the objective function J has converged (step S15, YES), the process proceeds to step S18. In step S18, the intermediate shape when the objective function J has converged is identified as the final intermediate shape. The three-dimensional data generation unit 17 converts the design data of the intermediate shape identified as the final intermediate shape into 3D CAD data, and ends the process.

[0046] The effect of intermediate shape calculation by the intermediate shape calculation device 1 will be described with reference to Figs. 3 to 6. Here, α=0.5 in the above formula (6) and p=3 in formula (5). Fig. 3 is a diagram for explaining the shape change of a forged product in a forging process. The upper part of Fig. 3 shows the shape change of a product including a final intermediate shape obtained by a conventional technique as a comparative example (referred to as a "conventional shape"), and the lower part of Fig. 3 shows the shape change of a product including a final intermediate shape obtained by the intermediate shape calculation device 1 of the present disclosure (referred to as an "optimized shape").

[0047] The shapes of the products shown in Fig. 3 are axially symmetrical. In order to facilitate understanding of the technology, Fig. 3 shows only one side of the cross-sectional shape of each product that is line symmetrical with respect to the central axis.

[0048] As shown in Fig. 3, the shapes FR1 and F1 are given the same billet shape. The shapes FR4 and F4 are given the same final shape. The shapes FR2 and F2 are first intermediate shapes, and the shapes FR3 and F3 are second intermediate shapes. As shown in Fig. 3, the first intermediate shape and the second intermediate shape are different from each other in the conventional shape and the optimized shape.

[0049] FIG. 4 is a diagram for explaining the amount of displacement at points A and B when an optimized intermediate shape is formed. FIG. 5 is a diagram for explaining the forming energy generated in the forging process when an optimized intermediate shape is formed. FIG. 6 is a diagram for explaining the load generated in the forging process when an optimized intermediate shape is formed. In FIGS. 4 to 6, the shaded areas correspond to the crushing process, the white areas correspond to the roughing process, and the hatched areas correspond to the finishing process. That is, the shaded areas correspond to the time when the initial shape is transformed into the first intermediate shape, the white areas correspond to the time when the first intermediate shape is transformed into the second intermediate shape, and the hatched areas correspond to the time when the second intermediate shape is transformed into the final shape.

[0050] As shown in Fig. 4, by changing from the conventional shape to the optimized shape, the amount of displacement in each process is reduced, and it can be seen that a result close to simultaneous filling up of points A and B is obtained. In addition, as shown in Fig. 5, according to the intermediate shape calculation device 1 of the present disclosure, the forming energy related to the forging process can be reduced by 23% by optimizing the intermediate shape. Furthermore, as shown in Fig. 6, it is possible to reduce the total load value related to the forging process by 7%.

[0051] As described above, according to the intermediate shape calculation device 1 of this embodiment, it is possible to calculate the shape of an intermediate process without using a database having data on the forged product, and the configuration of the intermediate shape calculation device 1 can be simplified.

[0052] According to the embodiment, in designing an intermediate shape of a forging process, the total value of the forging forming energy and the amount of displacement is set as an objective function, and the intermediate shape is derived by a topology optimization calculation using a level set method. That is, since the total value (almost equal to the load) of the forming energy and the amount of displacement (almost equal to the friction energy) is minimized, a process that imposes less load on the product and the mold can be designed. That is, according to the embodiment, it is possible to design a process that can suppress forming defects such as scratches on the product and reduce wear on the mold.

[0053] The intermediate shapes include a first intermediate shape that is transformed from the initial shape, and a second intermediate shape before being transformed into the final shape. In the first convergence determination process, the initial design data of the first intermediate shape is given design data of the same shape as the initial shape, and the initial design data of the second intermediate shape is given design data of the same shape as the final shape. Therefore, the initial design data of the convergence determination process can be easily set.

[0054] According to the present embodiment, the intermediate shape is calculated using sensitivity calculation based on the adjoint variable method, in which the sum of the forging energy and the displacement is set as the objective function. By using the adjoint variable method, it is possible to omit calculations for each design variable, thereby reducing calculation costs.

[0055] The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the spirit of the present invention. In the above embodiment, the forging process includes two intermediate processes, the first intermediate process and the second intermediate process, but the forging process may include one intermediate process having only one of the two processes. In the above example, the intermediate shape is calculated using a sensitivity calculation based on the adjoint variable method, but the present invention is not limited to this, and the intermediate shape may be calculated by a sensitivity calculation using, for example, a direct differential method or a difference approximation method. [Explanation of symbols]

[0056] 1. Intermediate shape calculation device 10 Processing section 11 Acquisition Department 12. Forming energy calculation section 13 Displacement calculation section 14 Judgment section 15 Intermediate shape calculation section 16 Update section 17 3D Data Generation Section 20 Memory section 30 Input / output section

Claims

1. An intermediate shape calculation device that repeatedly calculates design data indicating an intermediate shape of a forged product and specifies design data indicating a final intermediate shape, An acquisition unit that acquires design data of an initial shape of a forged product, design data before the change of the intermediate shape, and design data of a final shape of the forged product; a forming energy calculation unit that calculates a forming energy from the initial shape to the final shape by using each acquired design data; a displacement amount calculation unit that calculates a shape displacement amount from the initial shape to the final shape; a determination unit that determines whether an objective function determined from the forming energy and the shape displacement amount has converged depending on whether a change in the objective function is equal to or smaller than a predetermined value; an intermediate shape calculation unit that calculates an intermediate shape that reduces the objective function when the objective function has not converged; an updating unit that updates the pre-modification design data to post-modification design data of a calculated intermediate shape based on a shape derivative defined by a level set function; Equipped with Intermediate shape calculation device.

2. The objective function is a sum of the standardized values ​​of the forming energy and the shape displacement amount, The intermediate shape calculation device according to claim 1 .

3. If the objective function has converged, the pre-change design data is identified as design data representing the final intermediate shape. The intermediate shape calculation device according to claim 1 .

4. the intermediate shape calculation unit calculates an intermediate shape that reduces the objective function by using an adjoint variable method; The intermediate shape calculation device according to claim 1 .

5. An intermediate shape calculation method for repeatedly calculating design data indicating an intermediate shape of a forged product and specifying design data indicating a final intermediate shape, comprising: The computer Obtaining design data of an initial shape of a forging, design data before the change of the intermediate shape, and design data of a final shape; Calculating a forming energy from the initial shape to the final shape using each acquired design data; Calculating a shape displacement amount from the initial shape to the final shape; determining whether an objective function determined from the forming energy and the shape displacement has converged depending on whether a change in the objective function is equal to or smaller than a predetermined value; if the objective function has not converged, calculating an intermediate shape that reduces the objective function; updating the pre-modification design data to post-modification design data of the calculated intermediate shape based on a shape derivative defined by a level set function; Execute Intermediate shape calculation method.

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