JP5875255B2 - Cylindrical deep drawing molding simulation method, apparatus and program - Google Patents

Description

  The present invention relates to a cylindrical deep drawing forming simulation of a steel plate having a thickness of 4 mm or more.

  In the manufacturing field of automobile parts, home appliance parts, etc., press forming of steel plates is performed, and drawing molding is often used as a method for manufacturing cylindrical bottomed containers. As shown in FIG. 1, the cylindrical deep drawing is for forming a cylindrical container with a bottom by pushing a punch 4 into a workpiece 3 fixed by a die 1 and a blank holder 2. In recent years, cylindrical bottomed containers with relatively large thickness, which have been manufactured by hot forging using steel bars, cold forging and casting, mainly in the field of automotive parts, have been deep drawn using thick steel plates. It is being manufactured at, and contributes to cost reduction. When deep drawing is performed using a thick steel plate, the absolute value of the plate thickness change is large, and it is important to accurately estimate the plate thickness after forming.

  Conventionally, in FEM analysis of press forming of a thin steel plate, for example, as disclosed in Patent Document 1, FEM analysis considering in-plane anisotropy has been performed. Further, as described in Non-Patent Document 1, there is an example in which in-plane anisotropy is taken into consideration in the FEM analysis of a cylindrical deep drawing, and the cup height after molding is predicted.

  For example, Patent Document 2 discloses performing FEM analysis on a bottomed non-cylindrical drawn product.

JP 2000-107818 A Japanese Patent Laid-Open No. 2006-281281

"Press Forming Difficulty Handbook 2nd Edition", Thin Steel Sheet Forming Technology Study Group, Nikkan Kogyo Shimbun Yoshiaki Yamada, “Plastic / Viscoelasticity”, Baifukan, P216-218 Gennori Terano, Norihiko Kitamura, “Plastic Anisotropy of Plates”, 2006 Plastic Processing Spring Lecture, P337-338

  However, in the FEM analysis of the cylindrical deep drawing of a thick steel plate, the shape prediction accuracy is insufficient in the analysis considering the in-plane anisotropy used for the FEM analysis of the conventional thin plate.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to increase the accuracy of shape prediction when performing a cylindrical deep drawing forming simulation.

In the method for forming a cylindrical deep draw according to the present invention, a steel plate having a thickness of 4 mm or more is disposed on a die having a hollow cylinder, the central cylinder of the die is the same as the central axis, and the inner diameter of the hollow cylinder is determined. When performing a cylindrical deep drawing molding simulation by pushing a cylindrical punch having a small outer diameter, the drawing ratio is 2.0 or more, the ratio of the plate thickness to the shoulder radius of the punch is 0.4 or more, and the thickness and the above When the ratio of the shoulder radius of the die is 0.4 or more, in addition to the in-plane anisotropy, the forming simulation is performed in consideration of the anisotropy in the plate thickness section.
In addition, another feature of the cylindrical deep drawing molding simulation method of the present invention is that in the cylindrical deep drawing, the steel plate is formed by a hollow disc-shaped blank holder having the same central axis as the hollow cylinder of the die. It is in the point pressed against the die.
Another feature of the cylindrical deep drawing molding simulation method according to the present invention is that an anisotropic parameter in Hill's anisotropic yield condition is obtained. In that case, a cube is cut out from each of a plurality of surfaces of a steel plate having a thickness of 4 mm or more with a plurality of inclinations, compressed, and an anisotropic parameter in the Hill anisotropic yield condition formula is obtained based on the strain. .
The cylindrical deep drawing molding simulation apparatus of the present invention has a steel plate having a plate thickness of 4 mm or more disposed on a die having a hollow cylinder, the central cylinder of the die is the same as the central axis, and the inner diameter of the hollow cylinder is When performing a cylindrical deep drawing molding simulation by pushing a cylindrical punch having a small outer diameter, the drawing ratio is 2.0 or more, the ratio of the plate thickness to the shoulder radius of the punch is 0.4 or more, and the thickness and the above In the case where the ratio of the shoulder radius of the die is 0.4 or more, there is provided a means for performing a forming simulation in consideration of the anisotropy in the plate thickness section in addition to the in-plane anisotropy.
According to the program of the present invention, a steel plate having a thickness of 4 mm or more is arranged on a die having a hollow cylinder, the central cylinder of the die is the same as the central axis, and the outer diameter is smaller than the inner diameter of the hollow cylinder. when performing the forming simulation of the diaphragm by that cylinder depth in pushing the punch, drawing ratio of 2.0 or more, the thickness and the punch shoulder radius ratio 0.4 or more, and the thickness and the die shoulder radius When the ratio is 0.4 or more, in addition to the in-plane anisotropy, the computer executes a process of performing a forming simulation in consideration of the anisotropy in the plate thickness section.

  According to the present invention, it is possible to increase the accuracy of shape prediction when performing a cylindrical deep drawing forming simulation.

It is sectional drawing of the die | dye for cylindrical deep drawing, a blank holder, a punch, and a workpiece. It is a figure which shows the cutout direction of a tensile test piece. It is a characteristic view which shows the cup height by experiment and calculation. It is sectional drawing of the draw molded article which shows the measurement location and cup cup height of plate | board thickness. It is a characteristic view which shows the plate | board thickness by experiment and calculation. It is a figure which shows the cutting direction of a cube test piece used in order to obtain | require Z value, a compression direction, and the measurement direction of distortion. It is a figure which shows the cutting direction of a cube test piece used in order to obtain | require Y value, a compression direction, and the measurement direction of distortion. It is a figure which shows the cutting direction of a cube test piece used in order to obtain | require X value, a compression direction, and the measurement direction of distortion. It is a characteristic view which shows the cup height by experiment and calculation in case the initial board thickness of a workpiece is 10 mm. It is a characteristic view which shows the board thickness by experiment and calculation in case the initial board thickness of a workpiece is 10 mm. It is a characteristic view which shows the cup height by experiment and calculation in case the initial board thickness of a workpiece is 3.5 mm. It is a characteristic view which shows the board thickness by experiment and calculation in case the initial stage board thickness of a workpiece is 3.5 mm. It is sectional drawing of the die | dye and punch for cylindrical deep drawing of an Example, and a to-be-processed material. The initial plate thickness of the workpiece was 10 mm. 1, no. FIG. 2 is a characteristic diagram showing cup heights according to 2 and experiments. The initial plate thickness of the workpiece was 10 mm. 1, no. It is a characteristic view which shows the board thickness by 2 and experiment. No. in which the initial plate thickness of the workpiece was 8 mm. 3, no. FIG. 4 is a characteristic diagram showing cup heights according to 4 and experiments. No. in which the initial plate thickness of the workpiece was 8 mm. 3, no. FIG. 4 is a characteristic diagram showing a plate thickness by 4 and experiment. The initial plate thickness of the workpiece was 4 mm. 5, no. 6 is a characteristic diagram showing a cup height by experiment and experiment. The initial plate thickness of the workpiece was 4 mm. 5, no. 6 is a characteristic diagram showing the plate thickness by experiment and experiment.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
A cylinder of SPH590 having a plate thickness of 10 mm was deep drawn by cylinder and analyzed by FEM (Finite Element Method) which is a forming simulation. First, FEM analysis considering only in-plane anisotropy was performed. As the yield conditional expression, Hill's anisotropic yield conditional expression shown in Expression (1) was used.

  In order to consider the in-plane anisotropy, the anisotropy parameters F, G, H, and N in the equation (1) can be obtained as follows, as described in Non-Patent Document 2, for example. As shown in FIG. 2, a test piece 12 having inclination angles α = 0 °, 45 °, and 90 ° with respect to the rolling direction is made from the steel plate 11, a tensile test is performed, and an r value of Rankford represented by Equation (2) is obtained. .

  Anisotropy parameters G, F, and N can be obtained by substituting the r value obtained as described above into Equation (3), Equation (4), and Equation (5), respectively. The values are shown in Table 1.

  In the FEM analysis considering in-plane anisotropy, as shown in FIG. 3, the tendency that the cup height in the 45 ° direction (H shown in FIG. 4) increases from the rolling direction could be reproduced. It became larger than the experimental result. Moreover, as shown in FIG. 4, as a result of investigating the plate thickness at four locations a to d of the drawn product 21 after molding, as shown in FIG. 5, the plate thickness at the punch shoulder is considerably smaller than the experimental result. As a result.

  As a result of intensive studies, the present inventor has found that not only in-plane anisotropy but also anisotropy in the cross section of the plate thickness affects the shape change. In order to consider the anisotropy in the plate thickness cross section in addition to the in-plane anisotropy, the anisotropy parameters F, G, H, L, M and N in the equation (1) are described in Non-Patent Document 3, for example. It asks as follows.

  As shown in FIG. 6, a cube having a side length of 6 mm is processed and compressed in the directions of inclination angles β = 0 °, 45 °, and 90 ° with respect to the rolling direction to obtain the Z value represented by Equation (6). FIG. 6 is a diagram showing the cutting direction, compression direction, and strain measurement direction of a cubic test piece used for obtaining the Z value. 31 is a steel plate. Reference numeral 32 denotes a cubic test piece having a side length of 6 mm and processed so that the compression direction has an inclination angle β = 0 ° with respect to the rolling direction. Reference numeral 33 denotes a cubic test piece having a side length of 6 mm and processed so that the compression direction has an inclination angle β = 45 ° with respect to the rolling direction. Reference numeral 34 denotes a cubic test piece having a side length of 6 mm and processed so that the compression direction has an inclination angle β = 90 ° with respect to the rolling direction.

  Further, as shown in FIG. 7, a cube having a side length of 6 mm is processed and compressed in the directions of the inclination angles γ = 0 °, 45 °, and 90 ° with respect to the rolling direction, and the Y value represented by Expression (7) is obtained. FIG. 7 is a diagram showing the cutting direction, compression direction, and strain measurement direction of a cubic test piece used for obtaining the Y value. 41 is a steel plate. Reference numeral 42 denotes a cubic test piece having a side length of 6 mm and processed so that the compression direction has an inclination angle γ = 0 ° with respect to the rolling direction. Reference numeral 43 denotes a cubic test piece having a side length of 6 mm and processed so that the compression direction has an inclination angle γ = 45 ° with respect to the rolling direction. Reference numeral 44 denotes a cubic test piece having a side length of 6 mm and processed so that the compression direction has an inclination angle γ = 90 ° with respect to the rolling direction.

  Further, as shown in FIG. 8, a cube having a side length of 6 mm is processed and compressed in the directions of inclination angles θ = 0 °, 45 °, and 90 ° with respect to the rolling direction to obtain the X value represented by the equation (8). FIG. 8 is a diagram showing the cutting direction, compression direction, and strain measuring direction of a cubic test piece used for obtaining the X value. 51 is a steel plate. Reference numeral 52 denotes a cubic test piece having a side length of 6 mm processed so that the compression direction has an inclination angle θ = 0 ° with respect to the width direction. Reference numeral 53 denotes a cubic test piece having a side length of 6 mm which is processed so that the compression direction has an inclination angle θ = 45 ° with respect to the width direction. Reference numeral 54 denotes a cubic test piece having a side length of 6 mm which is processed so that the compression direction has an inclination angle θ = 90 ° with respect to the width direction.

  The Z value, the Y value, and the X value obtained as described above are substituted into Equation (9), Equation (10), Equation (11), Equation (12), and Equation (13) to obtain coefficients G and F, respectively. , N, M, and L can be obtained. The values are shown in Table 2.

  9 and 10 show the FEM analysis results in consideration of the anisotropy in the plate thickness section in addition to the in-plane anisotropy. FIG. 9 is a characteristic diagram showing the cup height by experiment and calculation when the initial plate thickness of the workpiece is 10 mm. FIG. 10 is a characteristic diagram showing the plate thickness obtained by experiments and calculations when the initial plate thickness of the workpiece is 10 mm. When the initial plate thickness of the workpiece is 10 mm, the analysis result considering the in-plane anisotropy in addition to the in-plane anisotropy is compared with the analysis result considering only the in-plane anisotropy. The analysis accuracy is close to the experimental results.

  On the other hand, FIG. 11 is a characteristic diagram showing the cup height by experiment and calculation when the initial plate thickness of the workpiece is 3.5 mm. FIG. 12 is a characteristic diagram showing the plate thickness obtained by experiments and calculations when the initial plate thickness of the workpiece is 3.5 mm. As shown in FIGS. 11 and 12, when the plate thickness is less than 4 mm, in addition to the in-plane anisotropy, the analysis result considering the anisotropy in the plate thickness section and the conventional in-plane anisotropy only This is almost the same as the analysis result considering. Therefore, when performing FEM analysis of a cylindrical deep drawing of a steel sheet having a thickness of 4 mm or more, it is preferable to perform an analysis taking into account the anisotropy in the thickness section in addition to the in-plane anisotropy.

  A material obtained by cutting a steel plate of SPH590 having a plate thickness of 10 mm, 8 mm, or 4 mm into a disc was used. Using the mold (punch 61, die 62) shown in FIG. 13, the workpiece 63 was drawn under the conditions shown in Table 3. The wrinkle presser was not used because wrinkles did not occur even if there was no wrinkle presser because the plate thickness was thick.

  Table 3 shows FEM analysis conditions. Reference No. 1 and no. 2 is an FEM analysis with a plate thickness of 10 mm, and the results are shown in FIGS. 14 and 15. 14 shows No. 1 in which the initial plate thickness of the workpiece is 10 mm. 1, no. FIG. 2 is a characteristic diagram showing cup heights according to 2 and experiments. 15 shows No. 1 in which the initial plate thickness of the workpiece is 10 mm. 1, no. It is a characteristic view which shows the board thickness by 2 and experiment. No. to which the present invention is applied. In Comparative Example No. 1 considering only in-plane anisotropy. Compared with 2, analysis accuracy is good.

  No. 3 and no. 4 is an FEM analysis with a plate thickness of 8 mm, and the results are shown in FIGS. 16 and 17. FIG. 16 shows the case where the initial plate thickness of the workpiece is 8 mm. 3, no. FIG. 4 is a characteristic diagram showing cup heights according to 4 and experiments. 17 shows No. 1 in which the initial plate thickness of the workpiece is 8 mm. 3, no. FIG. 4 is a characteristic diagram showing a plate thickness by 4 and experiment. No. to which the present invention is applied. In Comparative Example No. 3 in which only in-plane anisotropy is considered. Compared with 4, analysis accuracy is good.

  No. 5 and no. 6 is an FEM analysis with a plate thickness of 4 mm, and the results are shown in FIGS. 18 shows No. 1 in which the initial plate thickness of the workpiece is 4 mm. 5, no. 6 is a characteristic diagram showing a cup height by experiment and experiment. 19 shows No. 1 in which the initial plate thickness of the workpiece is 4 mm. 5, no. 6 is a characteristic diagram showing the plate thickness by experiment and experiment. No. to which the present invention is applied. In Comparative Example No. 5 considering only in-plane anisotropy. Compared with 6, analysis accuracy is better.

  The FEM analysis of the cylindrical deep drawing as described above can be executed by a molding simulation apparatus including a computer apparatus including a CPU, a ROM, a RAM, and the like. In addition, the above-described software (program) that realizes the FEM analysis of the cylindrical deep drawing is supplied to a system or apparatus via a network or various storage media, and the computer (or CPU, MPU, etc.) of the system or apparatus executes the program. It is also possible to read and execute.

DESCRIPTION OF SYMBOLS 1 ... Die, 2 ... Blank holder, 3: ... Work material, 4 ... Punch, 11 ... Steel plate, 12 ... Tensile test piece, 21 ... Drawing after drawing, 31 ... Steel plate, 32 ... Compression direction with respect to rolling direction A cube test piece with a side length of 6 mm processed to have an inclination angle β = 0 °, 33... A cube test piece with a side length of 6 mm processed so that the compression direction has an inclination angle β = 45 ° with respect to the rolling direction, 34: Cubic specimen having a side length of 6 mm processed so that the compression direction has an inclination angle β = 90 ° with respect to the rolling direction, 41 ... Steel plate, 42 ... The compression direction has an inclination angle γ = 0 ° with respect to the rolling direction A cube test piece with a side length of 6 mm processed to 43 mm, a cube test piece with a side length of 6 mm processed so that the compression direction has an inclination angle γ = 45 ° with respect to the rolling direction, and 44... An inclination with respect to the rolling direction. Angle γ = 90 ° Cubic test piece having a side length of 6 mm, 51 ... steel plate, 52 ... Cubic test piece having a side length of 6mm processed so that the compression direction has an inclination angle θ = 0 ° with respect to the width direction, 53 ... width in the compression direction Cube test piece with a side length of 6 mm processed so as to have an inclination angle θ = 45 ° relative to the direction, 54... Cube test with a side length of 6 mm processed so that the compression direction has an inclination angle θ = 90 ° with respect to the width direction. Piece 61 ... Punch 62 ... Die 63 ... Workpiece

Claims (6)

By placing a steel plate having a plate thickness of 4 mm or more on a die having a hollow cylinder, and pressing a cylindrical punch having the same central axis as the central cylinder of the die and an outer diameter smaller than the inner diameter of the hollow cylinder When forming a deep cylindrical drawing simulation, the drawing ratio is 2.0 or more, the ratio of the plate thickness to the shoulder radius of the punch is 0.4 or more, and the ratio of the plate thickness to the shoulder radius of the die is 0.4 or more. In this case, a forming simulation method for cylindrical deep drawing is characterized in that forming simulation is performed in consideration of anisotropy in a plate thickness section in addition to in-plane anisotropy.   The said cylindrical deep drawing WHEREIN: The said steel plate is pressed between the said dies with the hollow disk-shaped blank holder whose central axis is the same as the hollow cylinder of the said die | dye. Cylindrical deep drawing molding simulation method.   3. The forming simulation method for a cylindrical deep drawing according to claim 1, wherein an anisotropic parameter in Hill's anisotropic yield condition equation is obtained.   A cube is cut out from each of a plurality of faces of a steel plate having a thickness of 4 mm or more with a plurality of inclinations, compressed, and an anisotropic parameter in the Hill anisotropic yield condition formula is obtained based on the strain. The forming simulation method for cylindrical deep drawing according to claim 3. By placing a steel plate having a plate thickness of 4 mm or more on a die having a hollow cylinder, and pressing a cylindrical punch having the same central axis as the central cylinder of the die and an outer diameter smaller than the inner diameter of the hollow cylinder When forming a deep cylindrical drawing simulation, the drawing ratio is 2.0 or more, the ratio of the plate thickness to the shoulder radius of the punch is 0.4 or more, and the ratio of the plate thickness to the shoulder radius of the die is 0.4 or more. In this case, a cylindrical deep drawing molding simulation apparatus comprising means for performing a molding simulation in consideration of anisotropy in a plate thickness section in addition to in-plane anisotropy. Placing a steel plate having a plate thickness of 4 mm or more on a die having a hollow cylinder, and pushing in a cylindrical punch having the same central axis as the central cylinder of the die and an outer diameter smaller than the inner diameter of the hollow cylinder. when performing the forming simulation of Ru cylindrical deep drawing good, drawing ratio of 2.0 or more, the thickness and the punch shoulder radius ratio 0.4 or more, and a thickness between the die shoulder radius ratio 0.4 or more In this case, a program for causing a computer to execute a forming simulation in consideration of anisotropy in a plate thickness section in addition to in-plane anisotropy.

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