JPH08137925A - Method for preparing die face shape - Google Patents

Abstract

PURPOSE: To sharply reduce the manhour of preparation of a die face shape and to prepare a shape capable of obtaining optimum fit without generating dispersion. CONSTITUTION: In the case of preparing a three-dimensional shape for a die face DF from a base curve BC indicating the three-dimensional inner peripheral outline shape of the die face DF prepared by adding excess thickness to the periphery of a product shape by a CAD system to hold a press die blank, an upper model UM and a lower model LM respectively having faces extended along the base curve BC as respective leading parts are prepared, the coordinate values of respective grating points GP of a flat grating RG with a prescribed pitch corresponding to the blank when the grating RG is deformed by holding it between the upper and lower models UM, LM are found out by an elasto- plastic finite element method and the three-dimensional shape of the die face DF is prepared by the CAD system based upon the coordinate values of respective grating points GP.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a CAD (Computer Aided Design) system to add a surplus to the periphery of a product shape previously created to form a blank (a plate-shaped metal material such as a steel plate) into the product shape. When creating a basic curve showing the three-dimensional inner peripheral contour shape of the die face (wrinkle holding surface) that holds the blank of the press die to be formed, and creating the three-dimensional shape of the die face from the basic curve The present invention relates to a die face shape creating method suitable for use in.

[0002]

2. Description of the Related Art When designing a press die for molding a panel product such as an automobile roof panel, an engine hood outer panel, a trunk lid outer panel, etc. by a CAD system, in the conventional method, as shown in FIG. In (a), the product shape previously created by the CAD system is cut at a plurality of vertical cross sections positioned in a grid to create cross-section lines representing the product shape in each cross section, and then the step (b) Then, for each of those cross-section lines, both edge edges of the product shape at the cross-section line are smoothly extended to give a surplus of a shape preferable for draw forming, and draw-drawing is performed for the product shape at the cross-section line. It is preferable to set a die face DF with an appropriate radius of curvature CR that gently extends at a preferred distance L, and obtain the intersection of the die face DF and the surplus. Die face of in determining the position of the die edge DE, then in step (c), in each section
The basic curve BC showing the three-dimensional inner peripheral contour shape of the die face DF by returning the shape of the DF and the die edge DE thereat to the three-dimensional space and then smoothly connecting those die edges DE in step (d). To create.

Next, conventionally, as shown in FIG. 7, step (e)
And two die faces within the above cross section that are adjacent to each other.
A gentle reference plane BS passing through the two curves m, m, which is a portion of the DF located outside the basic curve BC, and the basic curve BC between the curves m, m, is provided between the respective curves m, m. In the step (f), the outer edge of each corner of the basic curve BC is lowered so as to fit the blank well to the surface of the die face DF or the punch for forming in the step (f). Create a floss surface FS (this is called because it resembles the shape of the furoshiki end lifted),
Next, in step (g), a connection surface CS that smoothly connects the floss surface FS and the reference surfaces BS on both sides thereof is created, and then in step (h), the plurality of surfaces created above by shading rendering are created. Check the connection state and the overall shape of the, and if there is a defect, return to the process (e), and if there is no defect, in the process (j), the multiple surfaces BS, FS, and CS created above are treated as one tertiary The original die face DF is used.

Thereafter, as shown in FIG.
In (k), cut the die face DF made in the above step (j) into a plurality of vertical cross sections located in a grid pattern, and check whether the cross-section lines representing the die face shape in each cross section meet the design criteria. It is checked whether or not there is a defect, the process returns to step (e), and if there is no defect, the resin block is shaved based on the data of the die face DF created above and the die face DF is removed. Create a resin model PM with, place a vinyl chloride plate on the die face DF of the resin model PM, and observe the condition, and the designer will experience how the blank deforms when sandwiched with a blank holder. Based on the assumption, the quality of familiarity is judged, and if there is a defect, the process returns to step (e), and if there is no defect, the creation of the die face shape is completed.

[0005]

However, in the above-mentioned conventional die face shape forming method, each reference surface, the floss surface and the connecting surface are respectively formed from the basic curve, and the connection state of the plurality of surfaces and the overall shape are determined. If you check and if there is a defect, the process is re-created, so there is a problem that it takes a lot of man-hours just to create the shape of the die face DF. Is extremely difficult. Even after the creation, since the designer's experience and visual judgment are used to judge the conformity of the created die face DF, the judgment is likely to vary, and if there is a defect, the shape of the die face DF Since it is necessary to start over from the creation, this also increases the man-hours. Moreover, since the resin model is actually created and the quality of the familiarity is determined by using the resin model, there is a problem in that cost and man-hours increase in this respect as well.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a die face shape that advantageously solves the above-mentioned problems of the prior art. The method of the present invention uses a CAD system. When creating the three-dimensional shape of the die face from the basic curve showing the three-dimensional inner peripheral contour shape of the die face that holds the blank of the press die, which is created by adding a surplus to the periphery of the product shape,
An upper mold model and a lower mold model each having a surface extending along the basic curve as a tip portion are created, and a flat lattice having a predetermined pitch corresponding to a blank is sandwiched between the upper mold model and the lower mold model to be deformed. The coordinate values of the respective nodes of the grid in the case of being determined are obtained by using the elasto-plastic finite element method, and the three-dimensional shape of the die face is created by the CAD system based on the obtained coordinate values of the respective nodes. It is a feature.

In the method of the present invention, models having a cylindrical surface of a predetermined radius extending in an annular shape with the basic curve as a ridge at the tip are created as the upper mold model and the lower mold model, and these upper molds are prepared. When creating a model and a lower model, the basic curve is expressed in the form of a point sequence, and each of the points between the adjacent constituent points of the sequence of points is twice the predetermined radius on the horizontal plane in the overall coordinate system. By setting the width of the tool area, the grid corresponding to the blank arranged on the horizontal plane, each node in the tool area, corresponding to the tool area containing the node, in the local coordinate system Projecting on a cylindrical surface, returning the coordinates of the projection point in the local coordinate system to the coordinates in the global coordinate system, and projecting the upper model and the lower model respectively in the global coordinate system. Set of points Therefore, it is also possible to configure.

Further, in the method of the present invention, a model having a gentle surface which extends along the basic curve except for the corner portion of the basic curve and which is continuous with the excess thickness around the product shape is formed at the tip end portion. Is created as the upper mold model and the lower mold model, and the outer peripheral contour shape of the lattice corresponding to the blank is set as a rectangle, and the respective nodes of the lattice when sandwiched and deformed by the upper mold model and the lower mold model are obtained. From the coordinate values, the coordinate values of the respective nodes of the lattice when the tip of the outer peripheral corner portion of the deformed lattice is further forcedly displaced to the blank holder side of the press die by a predetermined amount are calculated by the elasto-plastic finite element method. The three-dimensional shape of the die face may be created based on the obtained coordinate values of each node.

[0009]

According to the method of the present invention, when the three-dimensional shape of the die face is created from the basic curve showing the three-dimensional inner peripheral contour shape of the die face, the surface extending along the basic curve is formed. Create an upper mold model and a lower mold model each having as a tip, and the coordinate values of each node of the grid when deformed by sandwiching a flat grid corresponding to the blank in the upper mold model and the lower mold model, It is obtained by the elasto-plastic finite element method, and the three-dimensional shape of the die face is created based on the obtained coordinate values of each node. Therefore, various surfaces are examined from the basic curve, and they are smoothly connected. Since the work can be made unnecessary and the number of production steps can be greatly reduced, and the three-dimensional shape of the die face corresponding to the deformed state of the blank is produced by using the elasto-plastic finite element method, With a die face shape familiar a suitable obtain variations can be created without creating the resin model for familiar examined after creation of die face shapes may be unnecessary.

In the present invention, a model having a cylindrical surface of a predetermined radius extending in an annular shape with the basic curve as a ridge at the tip is created as the upper mold model and the lower mold model, and the upper mold model and the lower mold model are prepared. When the mold model is created, the basic curve is expressed in the form of a point sequence, and a tool having a width twice the predetermined radius on a horizontal plane in the overall coordinate system is provided for each of the adjacent points of the sequence of points. An area is set, each node of the grid corresponding to the blank arranged on the horizontal plane is located in the tool area, and the node corresponds to the tool area including the node, on the cylindrical surface in the local coordinate system. , The coordinates of the projection point in the local coordinate system are returned to the coordinates in the global coordinate system, and the upper model and the lower model are each a set of the projection points expressed in the global coordinate system. By If it is to be formed, the upper model and lower model used in the calculation process when calculating the coordinate value of each node of the deformed grid by the elasto-plastic finite element method, corresponding to each node of the grid, Since it is composed of projection points on the cylindrical surface of the tip, it is possible to easily obtain appropriate data for those models, so that the coordinate values of each node of the deformed grid can be obtained accurately and reliably. it can.

Further, in the present invention, the model having a gentle surface which extends along the basic curve except the corner portion of the basic curve and which is connected to a surplus of the periphery of the product shape is formed at the tip portion. Created as a mold model and a lower mold model, the outer peripheral contour shape of the lattice corresponding to the blank is a rectangle, and the coordinate values obtained for each node of the lattice when sandwiched and deformed by the upper mold model and the lower mold model From the above, the coordinate values of each node of the grid when the tip of the outer peripheral corner portion of the deformed grid is further displaced by a predetermined amount to the blank holder side of the press die, using the elasto-plastic finite element method. If the three-dimensional shape of the die face is to be created based on the obtained coordinate values of each node, it is possible to calculate the three-dimensional shape of the die face by the elasto-plastic finite element method. Since it is possible to create a shape, it is possible to easily create a die face having a flaky surface, especially when it is desired to give the die face a flaky surface due to the moldability of the product. The connection between the floss surface and the other parts of the die face can be made smoother.

[0012]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an explanatory diagram showing an embodiment of a die face shape creating method of the present invention.
In the step (a), similar to the steps (a) to (d) of the conventional method shown in FIG. 6, from the product shape previously created by the CAD system, the three-dimensional inner peripheral contour shape of the die face DF is obtained. Is created, and then, in step (b), the basic curve BC is represented by a series of points. For example, the CAD system described above is used to create data of each constituent point SP of the series of points, and then the step In (c), using an ordinary EWS (engineering workstation) that performs deformation analysis calculation by, for example, the elastic-plastic finite element method (FEM) described below,
As shown in FIG. 3, the upper mold model UM and the lower mold as tools for FEM analysis calculation, each having a cylindrical surface of a predetermined radius r that extends annularly with the basic curve BC as the ridge line at the upper or lower end, Create model LM data.

The radius r of the cylindrical surface is optimally 30 mm to 40 mm when applied to a molding die for a product having a size of a vehicle roof panel, engine hood outer panel, or trunk lid outer panel. That is why the results of the tests conducted by the present inventors have been made clear.

3 and 4 show the upper model UM and the lower model LM based on the point sequence data representing the basic curve BC.
Is a flowchart showing a procedure for creating data of
Since the shape data of a tool for FEM analysis calculation generally needs to be expressed as grid-shaped point sequence data, here, first, in step 1 in FIG. 3, the entire coordinate system which is a rectangular coordinate system for FEM analysis calculation is used. On the X and Y surfaces corresponding to the horizontal surface of the press die, a flat and square regular grid (finite element mesh) RG of about 5 mm pitch having a size corresponding to the blank is set, and in step 2, the above basic For each line segment connecting adjacent constituent points SP of the point sequence data representing the curve BC, the line segment having a width twice the radius r of the cylindrical surface on the X and Y planes is extended around the line segment as a center. Existing tool area TR
Set.

Next, here, in step 3, the lower model LM is first created, and the lower model LM corresponding to each lattice point (node of the lattice) GP of the regular lattice RG is formed. , Z value Z _P in the global coordinate system is obtained. Therefore, here, for each grid point GP of the above-mentioned regular grid RG, first in step 4, the grid point GP is set to the tool area TR.
Of any of the areas (including on the boundary) or outside the area, and if the grid point GP is outside the area of all tool areas TR, in step 5, the regular grid RG , The Z value Z _P of the constituent point of the lower model LM corresponding to the lattice point is sufficiently small so as not to affect the deformation of the negative predetermined value D, for example, D =
After setting to -1000 etc., return to step 4 and move to the next grid point GP.
Is processed.

On the other hand, the grid point is determined by the judgment in step 4 above.
If GP is in any of the tool regions TR, in step 6, the local coordinate system (ξ, η, ζ) represented by the polar coordinate system is set for the tool region TR including the grid point GP. After setting, in the next step 7, the grid point GP in the tool area TR
The coordinates (X _G , Y _G , Z _G ) in the above global coordinate system (where Z _G = 0) are converted into a normal coordinate conversion matrix as shown in the figure.
Using [T], the coordinates (ξ _G , η _G ,
ζ _G ) (where ζ _G = 0), and then in step 8 in FIG. 4, the grid point GP is on the cylindrical surface of the radius r corresponding to the surface of the lower model LM in the local coordinate system. On the local coordinate system (ξ _P , η
_P , ζ _P ) as shown in the figure, ζ _P = η _P tan (cos ^-1 (η _P
/ r)), ξ _P = ξ _G , η _P = ζ _G , and the coordinates (ξ _P , η _P , ζ _P ) in the local coordinate system of the projection point PP are converted into the coordinate transformation matrix [[ Using the inverse transformation matrix [T] ^-1 of T], the coordinates (X
_P , Y _P , Z _P ) and return the projection point PP to the lower model LM
After setting the constituent points of, return to step 4 and move to the next grid point GP
Is processed.

According to such processing, the lower die model LM can be easily located in the area of the tool area TR and to the set of projection points PP represented by the global coordinate system and outside the area of the tool area TR. Since it can be configured by a certain set of constituent points having a sufficiently small negative value, the shape data of the lower model LM is converted into the above-mentioned regular grid RG so as to be suitable for FEM analysis calculation.
Can be expressed as point group data of points corresponding to each grid point GP, and therefore, the coordinate values of each node of the deformed grid can be obtained accurately and reliably. Then, in this step, the process proceeds to step 10 in FIG. 4, and the data of the upper model UM is created in the same manner as the case of the lower model LM, and at the time of the creation, the judgment corresponding to the step 4 is made. If the grid point GP is outside the area of all tool areas TR,
In order not to affect the deformation of the regular lattice RG, the Z value Z _P of the constituent point of the upper model UM corresponding to the lattice point is set to a sufficiently large positive predetermined value D, for example, D = + 1000, and then Perform processing for the grid point GP of.

After the data of the upper die model UM and the lower die model LM are created in this manner, in this embodiment, in step (c) in FIG. After setting the conditions (such as blank thickness and arrangement for the upper and lower die models), in the next step (d), using the EWS described above, the upper die model UM as a tool.
And the lower model LM sandwiches the regular lattice RG from above and below and elastically deforms the regular lattice RG, the coordinate value of each lattice point GP of the regular lattice RG is calculated by the elastoplastic finite element method, and finally the process (e ), Input the obtained coordinate values of each grid point GP of the deformed regular grid RG to the CAD system described above, for example, and create a die face DF as a smooth three-dimensional curved surface passing through those grid points GP. To do. In addition, in order to carry out the deformation analysis calculation by the elasto-plastic finite element method, in this embodiment, the sheet forming simulation study group installed in the above-mentioned EWS (with Akitake Makinouchi of RIKEN as the secretary,
The FEM software ITAS-3D Version 0.3 (only available to members of the study group) manufactured by automobile manufacturers, steel makers and others) is used, but the deformation analysis calculation by the elasto-plastic finite element method is DYNA3D, P
AM-STAMP, RADIOSS, NIKE, ABA
It is also possible to use known commercial software such as QUSS and MARK.

According to the die face producing method of the embodiment, many faces such as the reference face BS, the furoshiki face FS, and the connecting face CS are examined from the basic curve BC and they are smoothly joined together. Die face DF that can eliminate the conventional work at all and can significantly reduce the number of preparation steps, and that corresponds to the deformed state of the blank by using the elasto-plastic finite element method
Since the three-dimensional shape is created, it is possible to create a die face shape that gives an optimum familiarity without variation. And since it is possible to create a die face shape that gives this optimal familiarity, this method also eliminates the need to create a conventional resin model after creating the die face shape and work to familiarize it with it. can do. The blank of the present embodiment, and the regular grid RG corresponding to the blank, may have an external shape other than the rectangular shape in the above example, such as a circular shape, if necessary, such as a product shape.

By the way, the die face shape prepared by the method of the above-mentioned embodiment is sufficient for the molding die of the product shape having the usual moldability, but in the case of molding a particularly difficult-shaped product. For the above reasons, it may be necessary to provide a floss surface at the corner of the die face. FIG. 5 is an explanatory view showing another embodiment of the die face shape creating method of the present invention, which is suitable for such a case.
In this embodiment, first, step (a) of the conventional method shown in FIG.
Similarly to (d), a basic curve BC indicating the three-dimensional inner peripheral contour shape of the die face DF is created from the product shape created by the CAD system, and then the conventional method shown in FIG. 7 is used. Similar to step (e), extending along the basic curve BC except for the corners of the basic curve BC,
Create a reference surface BS that is a smooth surface that is continuous with the excess thickness around the product shape.

After that, as shown in FIG.
In (a), similar to step 1 in FIG. 3, in the overall coordinate system which is a rectangular coordinate system for FEM analysis calculation, the X and Y planes corresponding to the horizontal plane of the press die have a size corresponding to the blank. A flat and square regular grid RG with an appropriate pitch is set, and then, in step (b), the reference plane BS is arranged above and below the regular grid RG as the tip surfaces of the upper mold model and the lower mold model, respectively. Then, when the upper and lower mold models having the reference plane BS as the tip face and the regular lattice RG sandwiched from above and below for elastic-plastic deformation, the coordinate values of each lattice point GP of the regular lattice RG are elastically deformed. Calculated by the plastic finite element method. The deformation analysis calculation by the elasto-plastic finite element method can also use the FEM software ITAS-3D Version 0.3 installed in the EWS described above. Also, the upper model and the lower model that are used as are expressed and used by a point group of points located above and below each lattice point of the regular lattice RG arranged between the models.

Then, here, as further shown in FIG. 5, in step (c), the floss surface of the above-mentioned regular lattice RG sandwiched from above and below by the upper mold model and the lower mold model and elastically deformed is defined. Further, the tip of the outer peripheral corner portion to be provided is further forced to the blank holder side (downward in the figure) of the press die by a predetermined amount d which is an appropriate amount obtained by the conventional die production and trial of the method of this embodiment. In the same way as when the coordinate values of each grid point GP of the outer peripheral corner portion deformed by the forced displacement of the tip are sandwiched between the upper model and the lower model, the elasto-plastic finite element method is applied. Then, in the next step (d), based on the obtained coordinate values of the respective lattice points, the three-dimensional shape of the floss surface FS of the die face DF, especially the outer peripheral corner portion, is used, for example, using the CAD system described above. hand create.

According to the method of this embodiment, the outer peripheral corner portion deformed by forcibly shifting the outer peripheral corner tip of the regular lattice RG sandwiched by the reference plane BS created previously is obtained by the elasto-plastic finite element method. Since the surface is FS
Especially when you want to have a floss surface on the die face due to the moldability of the product, you can easily create a die face with that floss surface, and in that case,
The connection between the floss surface and the other parts of the die face can be made smoother. Even in the method of this embodiment, since the floss surface FS of the corner portion where the defect is likely to occur if created empirically is created by using the elasto-plastic finite element method, like the previous embodiment, the reference surface BS It is possible to reduce the number of steps involved in repeatedly creating the floss surface FS and the connection surface CS that are smoothly connected to each other, and it is also possible to eliminate the work of creating a resin model and examining the familiarity with it.

Although the present invention has been described above based on the illustrated example, the present invention is not limited to the above-mentioned example, and may be, for example, an FEM.
Software other than the above examples may be used as the software for analysis calculation, and the radius r of the cylindrical surface at the tip of the upper and lower models may be used.
Also, it can be appropriately changed according to the size of the product.

[0025]

As described above, according to the method of the present invention, an upper mold model and a lower mold model are created based on a basic curve, and a flat lattice corresponding to a blank is sandwiched between the upper mold model and the lower mold model. The coordinate values of each node of the grid when deformed are obtained by the elasto-plastic finite element method, and the three-dimensional shape of the die face is created based on the coordinate values of each node, so various surfaces are examined from the basic curve. It is possible to eliminate the work of creating and connecting them smoothly, and it is possible to greatly reduce the number of creation processes. Moreover, the elasto-plastic finite element method is used to create a die face that corresponds to the deformed state of the blank. Since a three-dimensional shape is created, it is possible to create a die face shape that gives the optimum familiarity without variation, and also to create a resin model for examining familiarity after creating the die face shape. It can be eliminated.

In the present invention, models having a cylindrical surface of a predetermined radius extending annularly with the basic curve as a ridge at the tip are created as the upper model and the lower model, and the upper model and the lower model are prepared. When the mold model is created, the basic curve is expressed in the form of a point sequence, and a tool having a width twice the predetermined radius on a horizontal plane in the overall coordinate system is provided for each of the adjacent points of the sequence of points. An area is set, each node of the grid corresponding to the blank arranged on the horizontal plane is located in the tool area, and the node corresponds to the tool area including the node, on the cylindrical surface in the local coordinate system. , The coordinates of the projection point in the local coordinate system are returned to the coordinates in the global coordinate system, and the upper model and the lower model are each a set of the projection points expressed in the global coordinate system. By If it is to be formed, the upper model and lower model used in the calculation process when calculating the coordinate value of each node of the deformed grid by the elasto-plastic finite element method, corresponding to each node of the grid, Since it is composed of projection points on the cylindrical surface of the tip, it is possible to easily obtain appropriate data for those models, so that the coordinate values of each node of the deformed grid can be obtained accurately and reliably. it can.

Further, in the present invention, the model having a gentle surface extending along the basic curve except the corner portion of the basic curve and having a smooth surface continuous with the excess thickness around the product shape is provided at the tip. Created as a mold model and a lower mold model, the outer peripheral contour shape of the lattice corresponding to the blank is a rectangle, and the coordinate values obtained for each node of the lattice when sandwiched and deformed by the upper mold model and the lower mold model From the above, the coordinate values of each node of the grid when the tip of the outer peripheral corner portion of the deformed grid is further displaced by a predetermined amount to the blank holder side of the press die, using the elasto-plastic finite element method. If the three-dimensional shape of the die face is to be created based on the obtained coordinate values of each node, it is possible to calculate the three-dimensional shape of the die face by the elasto-plastic finite element method. Since it is possible to create a shape, it is possible to easily create a die face having a flaky surface, especially when it is desired to give the die face a flaky surface due to the moldability of the product. The connection between the floss surface and the other parts of the die face can be made smoother.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a die face shape creating method of the present invention.

FIG. 2 is an explanatory diagram showing a method of creating an upper mold model UM and a lower mold model LM from a basic curve BC in the method of the above embodiment.

FIG. 3 is a first half of a flow chart showing a method of creating an upper model UM and a lower model LM from a basic curve BC in the method of the above embodiment.

FIG. 4 is the latter half of the flow chart.

FIG. 5 is an explanatory view showing another embodiment of the die face shape creating method of the present invention.

FIG. 6 is an explanatory diagram showing a method of creating a basic curve in a conventional die face shape creating method and the present invention.

FIG. 7 is an explanatory diagram showing a method of creating a die face shape from a basic curve in a conventional die face shape creating method.

FIG. 8 is an explanatory diagram showing a method for checking the created die face shape in the conventional die face shape creating method.

[Explanation of symbols]

 BC Basic curve BS Reference surface CS Connection surface DE Die edge DF Die face FS Frosuki surface GP Lattice point LM Lower model RG Regular lattice SP Point sequence configuration point TR Tool area UM Upper model

Claims (3)

[Claims] 1. From a basic curve showing a three-dimensional inner peripheral contour shape of a die face sandwiching a blank of a press die, which is created by adding a surplus to the periphery of a product shape by a CAD system, In creating a three-dimensional shape, an upper mold model and a lower mold model each having a surface extending along the basic curve as a tip portion are created, and a flat lattice having a predetermined pitch corresponding to a blank is formed in the upper mold model. And the coordinate value of each node of the lattice when sandwiched and deformed by the lower model is obtained by using the elasto-plastic finite element method, and based on the obtained coordinate value of each node, the CAD system performs A method for creating a die face shape, which comprises creating a three-dimensional shape. 2. A model having a cylindrical surface of a predetermined radius extending in an annular shape with the basic curve as a ridgeline at its tip is created as the upper model and the lower model, and the upper model and the lower model are created. In this case, the basic curve is represented in the form of a point sequence, and a tool area having a width twice the predetermined radius is set on the horizontal plane in the overall coordinate system for each of the adjacent constituent points of the point sequence. Of the grid corresponding to the blank arranged on the horizontal plane,
Each node in the tool area is projected onto the cylindrical surface in the local coordinate system corresponding to the tool area including the node, and the coordinates of the projected point in the local coordinate system are set in the global coordinate system. 2. The die face shape creating method according to claim 1, wherein the upper die model and the lower die model are each configured by a set of the projection points represented by the global coordinate system by returning the coordinates to the coordinate of the above. 3. The upper model and the lower model, each of which is a model having a gentle surface, which extends along the basic curve except the corner portion of the basic curve and which is continuous with a surplus of the periphery of the product shape, at the tip portion. As a model model, the outer peripheral contour shape of the grid corresponding to the blank is a rectangle, from the coordinate values obtained for each node of the grid when deformed by sandwiching between the upper model model and the lower model model, the deformation Using the elasto-plastic finite element method, the coordinate values of the nodes of the lattice when the tips of the outer peripheral corners of the lattice are further displaced by a predetermined amount toward the blank holder side of the press die are obtained and obtained. The die face shape creating method according to claim 1, wherein a three-dimensional shape of the die face is created based on the coordinate value of each node.