JPH08339396A - Processor for numerical simulation result in deformation process of metal plate - Google Patents

Abstract

PURPOSE: To enhance the efficiency of the corrections of a mold design and a working condition by providing a means outputting the contour line distribution of break/ wrinkle tolerance data concerning the result of numerical simulation of the plastic deformation process of a metal plate by a finite element method. CONSTITUTION: The strain/stress data of each element which is obtained by an FEM (finite element method) analysis is fetched into a data input means 1 and is written in a storage part 2. Next, the material kind and the strength of material are designed and each breaking limit strain/wrinkle limit stress data which is registered in storage parts 3 and 4 is extracted. Further, in the calculation means 5 of break/wrinkle tolerance data, a break/wrinkle tolerance is calculated from the relation of the strain/stress amount of each element, and the degree is made to be written in a storage part 6. Next, in the contour line distribution output means 7 of break/wrinkle tolerance data, the form diagram on which the contour line distribution in which the break tolerance and the wrinkle tolerance are sectioned for every some levels is drawn is outputted to the output device of the display, etc., of a computer. Namely, only if the strain/stress data by the FEM is read, a molding tolerance can be decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data processing device for displaying an analysis result on a screen when a process of plastically deforming a metal plate is numerically simulated by the finite element method.

[0002]

2. Description of the Related Art Generally, in the field of molding processing involving plastic deformation of materials such as forging, rolling and press forming, it is possible to improve the quality of molded products by setting an accurate material shape, mold and processing conditions. It is known that the cost can be reduced. Therefore, at present, in order to determine stable production conditions in a short period, predictability evaluation of workability using numerical simulation by the finite element method (FEM) is widely used.

The finite element method virtually divides an object that is deformed by an external force into a large number of small areas (elements), and determines the entire deformed shape and strain distribution and / or stress from the relationship between displacement and force within each element. The distribution is calculated numerically. By changing the input parameters, it is possible to investigate the deformation state of the molded product under various processing conditions. The method of displaying the simulation result by the finite element method on the display screen of a computer is widely used, and the analysis result can be visually known.

FIG. 4 is a block diagram showing an outline of a conventional data processing apparatus for displaying a result of simulating a plastic deformation process of a metal plate by the finite element method. In FIG. 4, 1 is an input means for inputting strain data and / or stress data obtained by simulation, 2 is a storage unit for the input strain data and / or stress data, and 10 is strain data and / or stress data. The contour distribution output means of is shown. In the conventional method, the strain data and / or stress data input means 1 converts the strain data and / or stress data of each element, which is the result of numerical simulation by the finite element method, into the strain data and / or stress data storage unit 2.
Are typing in. The strain data and / or stress data input to the strain data and / or stress data storage unit is the strain value and / or stress value displayed on the display screen of the strain data and / or stress data contour line distribution output means 10, for example. Is output as a contour line distribution on the transformation diagram by color-coding each level or dividing by lines. From the distribution chart, at any molding stage,
It is possible to know the strain state and / or the stress state of any position of the metal plate. FIG. 12 shows an example of displaying a strain contour line distribution by a conventional display method. The contour lines in this display indicate the positions of the same strain value.

FIG. 18 shows an example of displaying a stress contour line distribution by a conventional display method. The contour lines in this display are
The position of the same stress value is shown.

Since tensile stress is predominant in the actual processing of a metal plate, there are many processing problems such as a rupture phenomenon easily occurring as the processing progresses. When evaluating the breaking limit of a metal plate, the amount of strain at the breaking portion can be used as a standard, and as shown in FIG. 5, a breaking limit line having the principal strain on the coordinate axis is often used. When the strain in the molding process does not reach the fracture limit line, it can be determined that the molding is possible, and when the strain reaches the fracture limit line, it can be determined that the fracture occurs or the risk thereof is high.

Further, in the processing of a metal plate, there are many problems such that when compressive stress is generated in the plate surface due to restraint by a mold, wrinkles are generated as the processing progresses. When evaluating the wrinkle generation limit of the metal plate, the amount of compressive stress in the plate surface can be used as a guide, and as shown in FIG. 6, a wrinkle limit line having the principal stress on the coordinate axis is also created. If the stress in the molding process does not reach the wrinkle limit line, it can be judged that molding is possible,
When the wrinkle limit line is reached, it can be determined that wrinkles are occurring or the risk is high.

[0008]

By the way, as shown by the fracture limit line in FIG. 5, the strain amount at the fracture portion depends on the deformation state, that is, by the ratio ξ of the main strains ε ₁ and ε _2. The limit strain amount ε ₁ * has different values. In addition, FIG.
As shown by the wrinkle limit line, the amount of stress in the wrinkle generation part depends on the deformation state, that is, the limit stress amount σ ₁ * is different depending on the ratio ρ between the principal stresses σ ₁ and σ _2. . Therefore, if the result of analyzing the forming process of a metal plate by the finite element method is used to display the strain distribution or stress distribution using the conventional display method (for example, FIG. 12), the strain of the material becomes the fracture limit strain during the forming. It is not possible to judge whether or not the stress has reached the wrinkle limit stress, and the die designer can see the output result of the analysis result and immediately grasp the quality of workability and make a design change. It was difficult.

Therefore, an object of the present invention is to allow a designer to instantly determine whether or not a machining defect has occurred and where the defect has occurred when displaying the result of numerical simulation of the plastic deformation process of a metal plate by the finite element method. It is to provide a data processing device which can be grasped as described above and which improves the efficiency of the mold design and the process of correcting the processing conditions.

[0010]

In the data processing apparatus of the present invention, strain data of each element obtained by numerically simulating the plastic deformation process of a metal plate by the finite element method is stored in a strain data storage unit. Input means for inputting, fracture limit strain data storage section storing fracture limit strain data, fracture limit strain data in the fracture limit strain data storage section and strain margin of each element from strain data of each element input by the input means Fracture allowance calculation means for calculating, the fracture allowance data storage unit for storing the calculated fracture allowance of each element, and means for outputting the contour line distribution of the fracture allowance data of the fracture allowance data storage unit, Have.

Further, the data processing apparatus of the present invention comprises an input means for inputting stress data of an element obtained by numerically simulating a process of plastic deformation of a metal plate by a finite element method into a stress data storage section, A wrinkle limit stress data storage unit storing wrinkle limit stress data, and a wrinkle margin calculating a wrinkle margin of each element from the wrinkle limit stress data of the wrinkle limit stress data storage unit and the stress data of each element input by the input means. A wrinkle allowance data storage unit that stores the calculated wrinkle allowance of each element, and a unit that outputs the contour line distribution of the wrinkle allowance data of the wrinkle allowance data storage unit.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an outline of a data processing apparatus of the present invention. In FIG. 1, 1 is a strain data and / or stress data input means, 2 is a storage unit for strain data and / or stress data, 3 is a storage unit for fracture limit strain data, 4 is a storage unit for wrinkle limit stress data, and 5 is a storage unit. Break margin data and / or wrinkle margin data calculation means, 6
Is a storage unit for the breakage allowance data and / or the wrinkle allowance data, and 7 is a contour line distribution output unit for the breakage allowance data and / or the wrinkle allowance data. First, the strain data and / or stress data of each element obtained by FEM analysis of the deformation process of the metal plate is taken in by the data input means 1, and the strain data and / or stress data storage unit 2 is loaded.
Write in. Next, the material type, the material strength, the material grade, and the surface treatment information of the material are specified from the storage unit 3 of the fracture limit strain data and / or the storage unit 4 of the wrinkle limit stress data, and the fracture limit strain data and / or the wrinkle limit are specified. Extract stress data. The breaking limit strain data storage unit 3 has the breaking limit strain data 8 (FIG. 2) specified by these pieces of information registered therein. Further, in the wrinkle limit stress data storage unit 4, wrinkle limit stress data 9 (FIG. 3) specified by these pieces of information is registered. These fracture limit strain data and / or wrinkle limit stress data may be experimentally measured or may be obtained by theoretical analysis.

Further, the breaking margin data and / or the wrinkle margin data calculating means 5 extracts the breaking limit strain data and / or the wrinkling limit stress data storing section 4 extracted from the breaking limit strain data storing section 3. From the wrinkle limit stress data, the fracture limit strain amount and / or wrinkle limit stress amount specified by the strain ratio and / or stress ratio of each element of the strain data and / or stress data storage unit 2 is calculated, and each element is calculated. The fracture allowance and / or the wrinkle allowance is calculated from the relationship between the strain amount and / or the stress amount. As a method of calculating the fracture allowance and / or the wrinkle allowance at this time, the fracture limit strain amount and / or the difference between the wrinkle limit stress amount and the strain amount and / or stress amount of each element and the fracture limit strain amount and / or It can be calculated from the ratio of the wrinkle limit stress amount, but other calculation methods may be used. The break allowance data and / or the wrinkle allowance data calculated by the above method is written in the break allowance data and / or the wrinkle allowance data storage unit 6.

Next, in the contour line distribution output means 7 of the breakage allowance data and / or the wrinkle allowance data, the breakage allowance and / or the wrinkle allowance is set to several levels on an output device such as a computer display or a printer. Outputs a shape drawing in which the contour line distribution divided for each is drawn. As a method of displaying for each section, it is sufficient to use color coding or division with a line, and the number of sections may be two or more.

The fracture margin and / or the wrinkle margin can be displayed by this method because there are means for storing the fracture limit strain data and / or the wrinkle limit stress data which differ depending on the material type and surface property in the sheet forming. This is because it has a means for calculating the breakage allowance and / or the wrinkle allowance of the element. Therefore, by simply reading the strain data and / or stress data calculated by the FEM, the size of the forming allowance can be visually confirmed. It can be easily determined.

[0016]

【Example】

[Embodiment 1] An embodiment of a method of displaying an analysis result according to the present invention will be described below. 7 to 9 show examples of FEM analysis for explaining the embodiment of the present invention. Figure 7 is FE
It is a thing which shows the tool shape of the overhang forming test which carried out M analysis. FIG. 8 shows the initial shape of the analysis model. The metal plate to be processed, that is, the analysis target region of the deformable body is divided into 160 elements and 189 nodes. Table 1 shows the classification of the material of the metal plate at this time. FIG. 9 shows a deformed shape obtained by FEM analysis. At this time, as shown in Table 2, the principal strain values ε ₁ and ε ₂ are calculated for each element.
Is obtained.

[0017]

[Table 1]

[0018]

[Table 2]

An embodiment of the present invention will be described below with reference to FIG.

(1) First, the principal strain values ε ₁ and ε ₂ of each element calculated by the FEM shown in Table 2 are input by the strain data input means 1 and stored in the strain data storage unit 2. (2) Call the fracture limit strain data corresponding to the materials of the classification shown in Table 1 from the fracture limit strain data storage unit 3. The breaking limit strain data is represented by a curve in a plane coordinate system having principal strains on both axes, as shown in FIG.

(3) The fracture allowance data calculating means 5 calculates the fracture allowance of each element. Marked on the diagram limit strain curves as in Figure 10 the distortion value of the element number N, when the A _N points, obtaining the intersection B _N of the extension and limits distortion lines A _N-point from the origin O. The distance between OB _N and A _N B _N is calculated, the ratio is calculated, and this is taken as the fracture margin. Specifically, assuming that the strain data of the element number N is (ε _1N , ε _2N ) and the critical strain data is (ε * _1N , ε * _2N ), the forming allowance I _N of the element number _N is as follows. Calculate with.

[0022] I _N (%) = a _{(ε * 1N -ε 1N) /} ε * 1N × 100 above equation is calculated for all elements. This gives Table 3
As shown in, the fracture margin of all elements is obtained. These breakage margin data are stored in the storage unit 6.

(4) The contour distribution distribution means 7 for the fracture margin data outputs the contour distribution of the fracture margin to an output device such as a screen display as shown in FIG. Figure 11
The contour line shown in (1) represents the position of the breakage allowance of the same value, and the numerical value attached to the contour line represents the breakage allowance. The larger this value, the higher the breakage allowance. The contour line with a breakage margin of 0 is the critical strain boundary line.

[0024]

[Table 3]

[Embodiment 2] FIGS. 13 to 15 show examples of FEM analysis for explaining an embodiment of the present invention.
FIG. 13 shows a tool shape of a deep drawing forming test which is FEM-analyzed. FIG. 14 shows the initial shape of the analysis model. The metal plate to be processed, that is, the analysis target area of the deformable body is divided into 900 elements and 961 nodes. Table 1 shows the classification of the material of the metal plate at this time. FIG.
5 shows the deformed shape obtained by FEM analysis. At this time, principal stress values σ ₁ and σ ₂ are obtained for each element as shown in Table 4.

[0026]

[Table 4]

An example of the present invention will be described below according to the flow of FIG.

(1) First, the principal stress values σ ₁ and σ ₂ of each element calculated by the FEM shown in Table 4 are input to the stress data input means 1 and stored in the stress data storage unit 2.

(2) Table 1 from wrinkle limit stress data storage unit 4
Recall the wrinkle limit stress data corresponding to the materials of the classification shown in. It is assumed that the wrinkle limit stress data is represented by a curve in a plane coordinate system having principal stresses on both axes as shown in FIG.

(3) The wrinkle allowance data calculating means 5 calculates the wrinkle allowance of each element. The stress value of the element number N mark on the diagram threshold stress line as in FIG. 16, when the C _N points,
It can be determined intersection D _N between the extended line and the threshold stress line C _N-point from the origin O. The wrinkle margin is calculated by calculating the distance between OD _N and C _N D _N and calculating the ratio. Specifically, _assuming that the stress data of the element number N is (σ _1N , σ _2N ) and the critical stress data is (σ * _1N , σ * _2N ), the wrinkle allowance I _WN of the element number N is given by the following equation. Calculated.

I _WN (%) = (σ * _1N −σ _1N ) / σ * _1N × 100 When the above equation is calculated for all elements, the wrinkle allowance of all elements is calculated as shown in Table 5, and the wrinkle margin is calculated. The margin data is stored in the storage unit 6.

(4) The contour line distribution output means 7 for the wrinkle allowance data outputs the contour line distribution of the wrinkle allowance to an output device such as a screen display as shown in FIG. FIG.
The contour line shown in 7 represents the position of the wrinkle margin having the same value, and the numerical value attached to the contour line represents the wrinkle margin. The larger this value, the higher the wrinkle margin. The contour line with a wrinkle margin of 0 is the critical stress boundary line.

[0033]

[Table 5]

[0034]

According to the present invention, when a result of numerically simulating the process of plastic deformation of a metal plate by the finite element method is displayed on the screen, breakage and / or wrinkle which is a defective processing phenomenon occurs. The danger can be visually grasped instantly, and the mold designer can efficiently perform the mold design even if the mold designer has no experience in the metal plate forming technology.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a data processing apparatus for carrying out the method of the present invention in one aspect.

FIG. 2 is a chart showing the contents of data stored in a fracture limit strain data storage unit 3 shown in FIG.

3 is a chart showing the contents of data stored in a wrinkle limit stress data storage unit 4 shown in FIG.

FIG. 4 is a block diagram showing an outline of a data processing device for implementing a conventional display method.

FIG. 5 is a graph showing a breaking limit line of a metal plate.

FIG. 6 is a graph showing a wrinkle limit line of a metal plate.

FIG. 7 is a vertical cross-sectional view of a main part of a receiving tool for ball head overhang forming.

FIG. 8: Finite element method (FEM) of the metal plate to be formed
It is a perspective view showing an element division for numerical simulation by.

9 is a view of the element section of FIG. 8 of the metal plate after forming,
It is a perspective view which shows the deformation | transformation by shaping.

FIG. 10 is a graph showing a breaking limit line of the material used for the analysis of the example of the present invention.

FIG. 11 is a contour diagram showing several examples of the contour distribution of the fracture allowance obtained by the display method of the present invention.

FIG. 12 is a contour diagram showing several examples of contour contour distribution of strain according to a conventional display method.

13A is a vertical cross-sectional view of a main part of a tool for forming a deep-drawing rectangular tube, and FIG. 13B is a cross-sectional view taken along line BB of FIG. 13A.

FIG. 14 is a finite element method (FE) of a metal plate to be formed.
It is a perspective view which shows the element division for the simulation of the numerical value by M).

FIG. 15 is a perspective view showing a deformation of the metal plate after molding due to the molding of the element section shown in FIG.

FIG. 16 is a graph showing the wrinkle limit line of the material used for the analysis of the example of the present invention.

FIG. 17 is a contour diagram showing several examples of the contour line distribution of the wrinkle allowance obtained by the display method of the present invention.

FIG. 18 is a contour diagram showing several examples of strain contour distributions according to a conventional display method.

[Explanation of symbols]

1: Strain data and / or stress data input means 2: Strain data and / or stress data storage unit 3: Fracture limit strain data storage unit 4: Wrinkle limit stress data storage unit 5: Fracture allowance data and / or wrinkle allowance Data calculation means 6: Fracture allowance data and / or wrinkle allowance data storage unit 7: Contour line distribution output means of break allowance data and / or wrinkle allowance data 8: Internal structure of fracture limit strain data storage unit 9: Wrinkles Internal structure of critical stress data storage unit 10: Contour line distribution output means for strain data and / or stress data

Claims (2)

[Claims] 1. An input means for inputting strain data of each element obtained by numerically simulating a process of plastic deformation of a metal plate by a finite element method into a strain data storage unit, a fracture limit storing fracture data, and a fracture limit. Strain data storage unit, fracture limit strain data of the fracture limit strain data storage unit and fracture margin degree calculating unit for calculating the fracture margin degree of each element from the strain data of each element input by the input unit, and each calculated element And a means for outputting a contour distribution of the break allowance data in the break allowance data storage section, and processing of the numerical simulation result of the deformation process of the metal plate. apparatus. 2. An input means for inputting stress data of an element obtained by numerically simulating a process of plastic deformation of a metal plate by a finite element method, a wrinkle limit stress storing wrinkle limit stress data. Data storage unit, wrinkle margin calculation means for calculating the wrinkle margin degree of each element from the wrinkle limit stress data of the wrinkle limit stress data storage section and stress data of each element input by the input means, and for each calculated element Apparatus for processing numerical simulation result of deformation process of metal plate having wrinkle allowance data storage section for storing wrinkle allowance and means for outputting contour line distribution of wrinkle allowance data of the wrinkle allowance data storage section .