JPH086986A - Method for designing press die - Google Patents

Abstract

PURPOSE:To quantitatively evaluate the failure of a press die at a design stage and to easily correct design graphic only by changing the value of a parameter. CONSTITUTION:After the three-dimensional model 60 of a press product to be worked is prepared by using a parametric CAD device, an extrapolation surface (ripple restraint surface) 56 inclining at an inclined angle thetak in the prescribed range of a location being away from the three-dimensional model 60 by an offset dimensional Lj in a press direction is prepared by defining the offset dimension Lj and the inclined angle thetak as parameters. Subsequently, an interpolation surface 70 to be the three-dimensional shape of press stock at the inside of the extrapolation surface 56 is prepared when the press stock is brought into close contact with the extrapolation surface 56 and the propriety of the extrapolation surface 56 is judged from the distribution of the distance Ld in the press direction of the interpolation surface 70 and the three-dimensional model 60. When the extrapolation surface is not judged as a proper surface, the offset dimension Lj and inclined angle thetak are changed the extrapolation surface 56 is prepared again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for designing a press die, and in particular, a defect of the press die can be quantitatively evaluated at a designing stage, and a design figure can be easily made by simply changing a parameter value. The present invention relates to a method of designing a press die that can be modified.

[0002]

2. Description of the Related Art Design of a die face of a press die for drawing a press product having a predetermined shape, that is, a forming surface of a punch and a die and a wrinkle holding surface of a wrinkle holding ring are as follows.
Although it is performed using a CAD (Computer Aided Design) device, there is no quantitative evaluation of whether or not proper press quality can be obtained, and it is performed solely by the empirical judgment of the designer. Is normal. For example, the height and inclination angle of the wrinkle holding surface (inflow angle of the press material) have a great influence on the press quality, but the suitability of the wrinkle holding surface has not been quantitatively evaluated at the design stage. Also,
When the first shape part and the second shape part having different cross-sectional shapes are present close to each other, even if the mold is designed with the target shape, defects such as cracks and wrinkles occur at the boundary portion. A gradual change section is provided between them to smoothly change the cross-sectional shape, but it is necessary to quantitatively evaluate the suitability of the cross-sectional shape change in obtaining the appropriate press quality at the design stage. Has not been done.

[0003]

However, when the die shape is designed only by empirical judgment in this way, defects such as cracks, wrinkles, and surface distortion frequently occur during the tryout (trial punching) stage, and die correction is required. A lot of man-hours and time were required. Further, in the conventional die design, the design graphic is modified by delete (create) and create (create) on the screen of the CAD device, so the graphic modification at the design stage is troublesome and time consuming.

The present invention has been made in view of the above circumstances, and an object of the present invention is to quantitatively evaluate a defect of a press die at a design stage and design it by changing a parameter value. It is to be able to easily modify the figure.

[0005]

[First Means for Solving the Problem] Achieving such an object
In order to achieve this, the first invention squeezes a pressed product of a predetermined shape.
Parametric CAD device for press die for working
A method of designing using, as shown in FIG.
(A) The three-dimensional model of the pressed product is used as the parameter
3D model creation process created with a CAD device,
(B) Offset approximately along the outer peripheral edge of the three-dimensional model
Dimension L_jAnd inclination angle θ_kTo set each
Offset from the 3D model in the press direction
Law L_jAngle of inclination θ_kLeaning on
A wrinkle holding surface creating process for creating a slanted wrinkle holding surface,
(C) When pressing material is closely attached to the wrinkle holding surface
Tertiary of the press material inside the wrinkle holding surface
The original shape is the shape of the wrinkle holding surface and the material of the press material.
Created according to a predetermined arithmetic expression with quality as a parameter.
Material shape creation process to be performed, and (d) 3 of the press material
Of the 3D shape and the 3D model in the press direction
Distance L_dBefore obtaining the proper press quality from the distribution of
Wrinkle hold down judgment process to judge whether the wrinkle hold down surface is appropriate
(E) When it is determined that the wrinkle holding surface is not appropriate
The offset dimension L_jAnd the inclination angle θ _k
Wrinkle to fix wrinkle holding surface by changing at least one of
And a pressing surface correction step.

The above parametric CAD device is
The procedure for creating a figure and the numerical values of the respective parameters are stored, and once the figure is created, it has a function of automatically creating a modified figure by the same procedure simply by changing the numerical value of the parameter.

[0007]

That is, the present invention relates to the design of the wrinkle holding surface. First, a three-dimensional model of a pressed product is created by a parametric CAD device, and the offset dimension L _j and the inclination are set substantially along the outer peripheral edge of the three-dimensional model. by setting the angle theta _k respectively, to create a wrinkle holding surface inclined at an inclination angle theta _k in a predetermined range of positions spaced apart by an offset dimension L _j to the press direction from the 3-dimensional model. The offset dimension L _j and the inclination angle θ _k may be arbitrarily set for each part of the outer peripheral edge in accordance with the shape of the three-dimensional model, that is, the pressed product to be processed, based on past experience.
Offset dimension L _j is intended to determine the position of the blank-holding surface with respect to the punch type during pressing a 3-dimensional model on the assumption that the punch-type (press bottom dead center), the offset dimension L _j
The smaller the value, the shallower the wrinkle holding surface and the higher the material yield. Further, the inclination angle θ _k represents an inflow direction in which the press material is drawn during the press working, and may be determined according to the shape of the three-dimensional model, for example, so that the press material can smoothly flow in. The predetermined range in which the wrinkle holding surface is created can be specified, for example, by designating the inner edge and the outer edge, or by designating the width dimension of one of the inner edge and the outer edge.

After that, the three-dimensional shape of the press material inside the wrinkle holding surface when the press material is brought into close contact with the wrinkle holding surface is predetermined with the shape of the wrinkle holding surface and the material of the press material as parameters. Calculation formula, for example, finite element method (FEM)
The distance L _d between the three-dimensional shape of the press material and the three-dimensional model in the press direction
From the distribution of, it is judged whether or not the wrinkle holding surface is appropriate for obtaining proper press quality. The three-dimensional shape of the press material is the shape when the peripheral edge of the press material is clamped by the wrinkle holding ring and the wrinkle holding surface of the die before drawing, and between the three-dimensional shape and the three-dimensional model. The separation distance L _d of
It shows the progress of the drawing process at the time of press working, that is, the contact timing between the punch and the press material, and the contact timing is earlier at the place where the separation distance L _d is larger. The quality of the press quality in the drawing process is greatly affected by the contact timing of each part of the press material with the punch. From the past experience, the contact timing, that is, the separation distance L _d.
It is possible to judge whether or not an appropriate press quality can be obtained by the distribution of. For example, based on the past results of drawing press products having substantially the same shape, a plurality of locations of the press products are set as evaluation points, and the contact sequence is determined when proper press quality is obtained, and the separation distance L is set. The contact order of each evaluation point can be obtained from _d to judge pass / fail. The order of contact is not limited to the case where they are not always in time,
It may be a case where a plurality of evaluation points are in contact with each other substantially at the same time.

When it is determined from the distribution of the separation distance L _{d that} the wrinkle holding surface is not appropriate, at least one of the offset dimension L _j and the inclination angle θ _k is changed to correct the wrinkle holding surface. Then, an appropriate press quality can be obtained by creating a three-dimensional shape of the press material from the new wrinkle holding surface and judging the suitability of the wrinkle holding surface from the distribution of the separation distance L _d from the three-dimensional model. Correct the wrinkle holding surface until it becomes like this. In that case, since the present invention uses the parametric CAD device,
By simply changing the values of the offset dimension L _j and the tilt angle θ _k, a new wrinkle holding surface is automatically created according to the original procedure.

[0010]

As described above, according to the designing method of the press die of the present invention, whether or not the wrinkle holding surface is appropriate for obtaining the proper press quality is designed by the distribution of the separation distance L _d. Since it can be quantitatively evaluated at the stage, compared to the conventional case where a press die is designed only by the experience of the designer, the number of troubles at the tryout stage is reduced and the number of man-hours and the period required to correct the die are reduced. In addition, since it is possible to objectively judge the quality, even a inexperienced person can relatively easily design the wrinkle holding surface. Further, if the suitability of the wrinkle holding surface is evaluated in this way, the wrinkle holding surface is corrected as many times as necessary, but in the present invention, the wrinkle holding surface is adjusted with the offset dimension L _j and the inclination angle θ _k as parameters. Faces are set and a new wrinkle holding face is automatically created simply by changing those values, so wrinkle holding face can be corrected easily and quickly. This makes it possible to easily design an appropriate wrinkle holding surface.

[0011]

A second aspect of the present invention is the method for designing a press die according to the first aspect of the present invention, wherein it is determined whether or not the wrinkle holding surface has a curvature reversal in the pressing direction in the circumferential direction. However, when there is curvature reversal, a curvature reversal determination step of determining that the wrinkle holding surface is not appropriate is provided.

The curvature reversal in the pressing direction means that the curvature of the curve representing the displacement in the pressing direction is opposite on the way, and specifically, it includes a case where both a convex portion and a concave portion in the pressing direction are included. is there.

[0013]

Operation: That is, when the wrinkle holding surface has a curvature reversal in the pressing direction in the circumferential direction, the inflow resistance of the press material during drawing becomes large and cracks, surface strains, etc. occur, or during blanking (punching). Since problems such as wrinkles are likely to occur, for example, as shown in FIG. 2, after creating the wrinkle holding surface in the wrinkle holding surface creating step,
Before the three-dimensional shape of the press material is created in the material shape creation process, whether or not the wrinkle holding surface has a curvature reversal in the pressing direction in the circumferential direction, specifically, the inner peripheral line and the outer peripheral line of the wrinkle holding surface. It is determined whether or not has a curvature reversal in the pressing direction, and if there is a curvature reversal, it is determined that the wrinkle holding surface is not appropriate. Then, in order to eliminate such curvature reversal, the wrinkle holding surface is corrected by changing the offset dimension L _j and the inclination angle θ _k in the wrinkle holding surface correcting step.

Here, the determination as to the presence or absence of the curvature reversal may be made, for example, by displaying the displacements of the inner peripheral line and the outer peripheral line of the wrinkle pressing surface in the pressing direction as an image, and the designer may visually judge. You may make it calculate the curvature of each part by an arithmetic expression etc. The curvature reversal determination step can also be performed during the wrinkle holding surface creating step. That is, in the wrinkle holding surface creating step, by setting the offset dimension L _j substantially along the outer peripheral edge of the three-dimensional model, the wrinkle holding surface is separated from the three-dimensional model by the offset dimension L _{j in the} pressing direction. When the wrinkle holding surface that is inclined at the inclination angle θ _k from the inner peripheral line to the outer side is created, at the stage when the inner peripheral line is created according to the offset dimension L _j. It is possible to determine whether or not there is curvature inversion on the inner peripheral line. The presence / absence of curvature reversal may be determined before and after the wrinkle hold down determination step after the material shape creation step.

[0015]

According to the method of designing a press die of the second invention, since the wrinkle holding surface is designed so that there is no curvature reversal in the pressing direction, the inflow resistance of the press material is reduced. The occurrence of defects at the tryout stage due to the above is further reduced.

[0016]

A third aspect of the present invention is a press for drawing a pressed product having a first shape portion and a second shape portion, which have different cross-sectional shapes parallel to the pressing direction and are adjacent to each other. A method of designing a mold using a parametric CAD device, comprising: (a) creating a three-dimensional model of the first shape part and the second shape part by the parametric CAD device as shown in FIG. A dimensional model creating step, and (b) a gradual deformation state within a gradual change section between the first shape portion and the second shape portion in the three-dimensional model is predetermined using the gradual change designated value u as a parameter. A gradual-deformation creating step that is created according to an arithmetic expression; (c) a rate-of-change calculating step for obtaining an average cross-section line length change rate α for a plurality of sites in the gradual-change section; Maximum value α _max of A change rate determining step of determining whether or not the slope φ of the surface line length change rate α satisfies a predetermined relationship so as to obtain an appropriate press quality, and (e) the maximum value α _max and the slope When it is determined that φ does not satisfy a predetermined relationship, a gradual deformation state correcting step of changing the gradual change designated value u to correct the gradual deformation state is included.

The average cross-section line length change rate α is defined as the distance from the contact line where material movement does not occur to the contour line of the punch, that is, the wrinkle holding surface during press working, to the corresponding portion of the press blank before press working. 21 is a value obtained by dividing the length by, for example, L _P / L _B in FIG. However, even when the reciprocal of the average cross-section line length change rate α is calculated and the suitability is determined based on the minimum value or the slope of the reciprocal, the maximum value α _max
It is substantially the same as determining the suitability based on and the inclination φ, and is included in the technical scope of the present invention.

[0018]

That is, the third aspect of the invention is such that when the first shape portion and the second shape portion having different cross-sectional shapes are present in close proximity,
It relates to the design of the gradual deformation shape of the gradual change section provided between them so that an appropriate press quality can be obtained.
A three-dimensional model of the first shape portion and the second shape portion is created by a parametric CAD device. Next, a gradual deformation state within the gradual change section between the first shape portion and the second shape portion in this three-dimensional model is created according to a predetermined arithmetic expression using the gradual change specified value u as a parameter. This arithmetic expression is a gradual change specified value u for the gradual deformation between the first shape portion and the second shape portion.
For example, the shape at the intermediate position of the gradual change section is set to approach the first shape section or the second shape section according to the value of the gradual change specified value u. Regarding the first gradual deformation state, a fixed value may be set in advance as the gradual change specified value u, but the designer may be allowed to set an arbitrary value.

After that, the average cross-section line length change rate α is obtained for a plurality of sites in the gradually changing section, and the maximum value α _max of the average cross-section line length change rate α and the slope φ of the average cross-section line length change rate α are It is determined whether or not a predetermined relationship is satisfied so that proper press quality can be obtained. This relationship is determined by past results, experiments, simulations, etc., depending on the material of the press material, plate thickness, etc., or for each type of press product including those press conditions, but in general, the maximum value α _max , The larger the inclination φ, the harder it is to obtain an appropriate press quality, and the smaller the maximum value α _max and the inclination φ, the easier it is to obtain an appropriate press quality.

When it is determined that the maximum value α _max and the slope φ do not satisfy the predetermined relationship, the gradual change designation value u is changed to correct the gradual deformation state, and the new value is newly added. The average cross-section line length change rate α is calculated based on the gradual deformation state, and whether the gradual deformation state is appropriate or not is determined from the maximum value α _max and the inclination φ until the appropriate press quality is obtained. To fix. In that case,
In the present invention, since the parametric CAD device is used, a new gradual deformation state is automatically created according to the original procedure only by changing the value of the gradual change specified value u. here,
The maximum value α _max is determined by the shape of either end of the gradual change section, so it does not change even if the gradual deformation state is changed,
The inclination φ changes with the change of the gradually deformed shape, and it is possible to obtain an appropriate press quality. The inclination φ becomes smaller if the gradual change section is lengthened, but the gradual change section is provided so as to obtain appropriate press quality.
Also, in this gradual change section, the press product has a crease and it is necessary to pull out when blanking, so if the gradual change section becomes large, the press quality deteriorates and a large pulling die is required. However, it is desirable that the gradual change section is as small as possible, and according to the present invention, it is possible to obtain an appropriate press quality while keeping the gradual change section as small as possible. If the maximum value α _max and the slope φ do not satisfy the predetermined relationship even if the specified gradual change value u is changed to correct the gradual deformation state, the gradual change section is enlarged to gradually change the gradual change. The shape will be redesigned.

[0021]

As described above, according to the method for designing a press die of the present invention, whether or not the gradual deformation is appropriate for obtaining an appropriate press quality is determined by the average sectional line length change rate α. Maximum value α
_Since it can be quantitatively evaluated at the design stage from the relationship between _max and inclination φ, the occurrence of defects at the tryout stage is reduced compared to the conventional case where a press die is designed only by the experience of the designer, and the metal mold is reduced. Since the man-hours and the time required to correct the mold are reduced and the quality can be objectively judged, even a inexperienced person can relatively easily design the gradually deformed shape. Further, when the suitability of the gradual deformation state is evaluated in this manner, the gradual deformation state must be corrected many times as necessary, but in the present invention, the gradual deformation state is set with the designated gradual change value u as a parameter. , A new gradual deformation state is automatically created just by changing the value, so the gradual deformation state can be corrected easily and quickly, and in combination with the quantitative evaluation as described above, an appropriate gradual deformation state can be obtained. The shape can be easily designed. Further, in the present invention, by changing the gradual deformation state,
Since the proper press quality is obtained while keeping the gradual change section as small as possible, the desired shape change of the pressed product can be suppressed to the necessary minimum.

[0022]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 4 is a diagram for explaining an example of a press die 10 for performing a drawing process. The press die 10 is used by being installed in a single action type press machine, and includes a die die 12 and a punch die. The die die 12 is mounted on a press slide (not shown) and moved up and down, while the punch die 14 is fixedly mounted on a bolster (not shown). Further, the wrinkle pressing ring 16 is urged upward by a wrinkle pressing load applying means (not shown) having an urging means such as an air cylinder, and the die 12 is moved downward, as shown in (b). The peripheral edge of the flat plate-shaped press material 18 is clamped between the die die 12 and the die die 12 by a predetermined wrinkle pressing load, and in this state, the die material 12 is lowered to form the punching surface 2 of the punch die 14.
Wrinkles are prevented from occurring when the pressed product 22 is drawn following 0. The upper surface of the wrinkle pressing ring 16, that is, the wrinkle pressing surface 24, has a pressing direction from the forming surface 20 at the bottom dead center shown in (c) so that defects such as wrinkles, cracks, and surface strain do not occur in the pressed product 22. The distance L (vertical direction in FIG. 4) and the inclination angle θ with respect to the plane perpendicular to the pressing direction are defined. On the die die 12, a wrinkle holding surface 26 corresponding to the wrinkle holding surface 24 of the wrinkle holding ring 16 and a forming surface 20 having a shape corresponding to the forming surface 20 of the punch die 14 and the press product 22 to be manufactured are formed. Has been done. FIG. 5 shows the punch type 14 at the bottom dead center.
FIG. 2 is a perspective view showing the wrinkle holding ring 16 and the pressed product 2
It is the figure which abbreviated 2 and die type 12.

The molding surfaces 20, 28 and the wrinkle holding surface 24,
26 is designed according to the intended product shape using the parametric CAD device 30 shown in FIG. Figure 6
FIG. 1 is a block diagram illustrating the basic configuration of a parametric CAD device 30, which includes a central processing unit 32 connected by a data bus line, a main storage device 34 such as a ROM, and an auxiliary storage device 36 such as a RAM. The processing device 32 uses the temporary storage function of the auxiliary storage device 36 and the like, and creates, enlarges, reduces, moves, or rotates the three-dimensional model in accordance with a program stored in advance in the main storage device 34.
Various arithmetic processes such as logical operations such as sum, difference, product, etc. are performed, and the procedure of figure creation and the numerical values of each parameter are memorized. It has a function to automatically create a modified figure by the same procedure just by changing. Display device 3
Reference numeral 8 is an image display of a cathode ray tube, a liquid crystal panel, etc., and the above-mentioned three-dimensional model and a selection menu which allows the designer to easily select the processing contents are displayed. The designer has a keyboard 40, a tablet 42, a dial. Using the input device such as 44, input the data required for creating the three-dimensional model, enlarge, reduce, move, rotate the three-dimensional model, change the numerical values of the parameters, and modify the three-dimensional model. Various operations can be performed, such as selecting a desired menu from the selection menu displayed on the display device 38. Further, the printer 46 is for printing the display content of the display device 38, the shape data of the three-dimensional model, NC data for processing the three-dimensional model, and the paper tape puncher 48 is used in a machine tool or the like. The network controller 50 is connected to a work station, a machine tool, or the like to transmit information in order to output NC data.

Next, using the parametric CAD device 30 as described above, the wrinkle holding surface 24 of the press die 10 is used.
A procedure for designing the above according to the invention described in claims 1 and 2 will be described with reference to the flowcharts of FIGS. 7 and 8. Of the steps in the flowcharts of FIGS. 7 and 8, the double-lined frame step relates to the design of the wrinkle holding surface 24, and the other steps relate to the evaluation, correction, etc. of the wrinkle holding surface 24. First, the wrinkle holding surface 2
The design procedure of No. 4 will be described. In step S1, a press product to be machined, for example, a three-dimensional model 60 of a rear quarter panel of an automobile shown in FIGS. 9 and 10 is created based on the shape data of the product designed by the product shape designing unit to display the display device 38. , And in step S2, 3
The pressing direction is determined in consideration of a negative angle, process distribution, etc. while changing the attitude of the dimensional model 60 on the screen of the display device 38. 9 is a plan view seen from the press direction, that is, a plan view seen from the press direction, and FIG. 10 is a cross-sectional view taken along the line XX in FIG. 9. However, this three-dimensional model 60 has a surplus in a tire house portion indicated by a two-dot chain line. The shape of the target product is modified as necessary in consideration of the formability of the press work and the process distribution. 3D model 6 at this time
The surface shape of 0 corresponds to the molding surface 20 of the punch die 14, and can be considered as a step of forming the punch molding surface.

In step S5, assuming the contour of the punch die 14 as viewed from the pressing direction, the constituent points Q _{j of the} temporary punch PF (profile) 62 are substantially along the outer peripheral edge of the three-dimensional model 60.
Is set, and at the next step S6, each constituent point Q _j
A projection point R _j obtained by projecting the image on the three-dimensional model 60 is obtained. The constituent points Q _j are appropriately determined according to the shape of the three-dimensional model 60, and FIG. 9 shows a case where 14 points shown by black circles are set. It is desirable to set in. Further, the constituent point Q _j is
Although it may be set at a position outside the three-dimensional model 60,
The projection point R _{j in} that case may be a projection position on a surface obtained by extending the surface shape of the three-dimensional model 60, for example.

[0026] Each By setting the offset dimension L _j for step S7, the projection point R _j, create a blank holder reference point S _j from the projection point R _j spaced apart by an offset dimension L _j the pressing direction, step S8 Then, a plurality of wrinkle presser reference points S are formed by a predetermined interpolation formula or the like.
_{The j} is smoothly connected to create the temporary punch PF62.
The offset dimension L _j corresponds to the distance L in the pressing direction in FIG. 4, affects the quality of the wrinkle presser, and is set according to the shape of the three-dimensional model 60 based on past experience. The smaller L _j is, the wrinkle holding surface 2
Since 4 is shallow and the yield of the material of the press material 18 is improved, it is desirable that it is as small as possible within a range that does not cause a defect. Further, the provisional punch PF62 is created by the wrinkle pressing reference point S which is located substantially on a straight line when viewed from the pressing direction, for each configuration of the extrapolation surface 56 (corresponding to the wrinkle pressing surface 24) created in step S13. This is performed for each _j , and in the present embodiment, as is apparent from FIG. 9, four trapezoidal sides are created. The temporary punch PF62 constitutes the inner peripheral line of the outer insertion surface 56, that is, the wrinkle holding surface.

In step S11 of FIG. 8, the shapes of the four corner portions of the extrapolation surface 56 outside the temporary punch PF62 are indicated by broken lines in FIG.
Create to include the extension line of F62. Further, in step S12, the inclination angle θ _k is set along the temporary punch PF62, and in step S13, the extrapolation surface 56 inclined at the inclination angle θ _k from the plane perpendicular to the pressing direction is provided from the temporary punch PF62 toward the outside. create. The tilt angle θ
_k corresponds to the inclination angle θ in FIG. 4 and represents the inflow direction into which the press material 18 is drawn during the press working, and may be set according to the shape of the three-dimensional model 60 based on past experience or the like. The upper limit value θ _max is set in consideration of the punching process in the subsequent process. The tilt angle θ _k is
It is determined in the direction perpendicular to the temporary punch PF62 in the pressing direction view shown in FIG. 9, but the inclination angle θ _k is defined by the extension lines of the temporary punch PF62 at the four points at the corners. Further, this inclination angle θ _k is determined by the provisional punch PF6.
2 may be set continuously, but it is set for each wrinkle presser reference point S _j , and the extrapolation surface 56 is created by connecting them smoothly by a predetermined interpolation formula or the like. You can also do it. Further, the outer edge of the outer insertion surface 56, that is, the outer peripheral line 64 is defined by the outer peripheral frame 66 set in advance in the press direction view of FIG. 9, but the outer peripheral line 64 is defined by setting the width dimension from the temporary punch PF62. You can also do it.

Next, a method of evaluating the extrapolation surface 56, that is, the wrinkle holding surface, designed as described above will be described.
The first point of the basic idea of this evaluation method is that the provisional punch PF62 and the outer peripheral line 64, which are the inner peripheral line of the extrapolation surface 56.
Respectively have curvature reversal in the pressing direction. In the case of curvature reversal, the inflow resistance of the press material 18 at the time of drawing becomes large and cracks, strains, etc. occur, and wrinkles occur at the time of blanking. It is easy for problems such as wear and tear to occur. The second point is that the three-dimensional shape of the press material 18 inside the temporary punch PF62 when the press material 18 is brought into close contact with the outer insertion surface 56, that is, the insertion surface 7
0 (see FIG. 10) is obtained by using a predetermined arithmetic expression, for example, the finite element method or the like, with the shape of the extrapolated surface 56 and the material of the press material 18 (Young's modulus, Poisson's ratio, etc.) as parameters. Insertion surface 56 and insertion surface 70 to 3
Separation distance L _d in the press direction up to the dimensional model 60
From this, it is determined whether or not the extrapolation surface 56 is appropriate for obtaining proper press quality. As shown in FIG. 4B, the insertion surface 70 has a shape when the peripheral edge portion of the press material 18 is clamped by the wrinkle holding ring 16 and the die die 12 before drawing, and is shown in FIG. Extrapolation surface 5 at bottom dead center of press
6 and the separation distance L _d from the insertion surface 70 to the three-dimensional model 60 represent the progress of the drawing process during press working, that is, the contact timing between the punch die 14 and the press material 18, and the separation distance L _d is The larger the area, the faster the contact. The quality of the press quality in the drawing process is greatly affected by the contact timing of each part of the press material 18 with the punch die 14, and is it possible to obtain an appropriate press quality from the contact timing, that is, the distribution of the separation distance L _d , from past experience and the like? It is possible to determine whether or not, for example, based on the past results of drawing pressed products having substantially the same shape, a plurality of positions of the three-dimensional model 60 are set as evaluation points, and a contact order when appropriate press quality is obtained is determined. Every
It is possible to determine the quality by determining the order of contact of the evaluation points from the separation distance L _d .

The dashed-dotted line in FIG. 11 represents the distribution of the separation distance L _{d in} the form of contour lines. For example, the extrapolation surface 56 and the interpolation surface 70 in FIG. That is, in FIG. 10, it can be easily created by relatively moving upward by a predetermined distance and obtaining the overlapping portion of the two by a logical operation, and it is possible to judge whether the wrinkle hold is good or bad from the distribution of the separation distance L _d and past data. You can 12 is a sectional view taken along line XII-XII in FIG. Further, FIG. 13 shows a case of designing a press die for pressing a rear quarter panel of a hatchback type vehicle,
In this pressed product, surface strain is likely to occur in the lower rear part 74 of the window part 72, and in order to prevent this, the contact timing between the press material and the punch type is set to the front part 7 of the lower part of the window.
Alignment at 6 and rear 74 has been found to be effective. Therefore, the extrapolation surface (wrinkle holding surface) 7 indicated by the broken line
8a and the extrapolation surface (wrinkle holding surface) 78b shown by the solid line, the three-dimensional shape of the press material is obtained and the distribution of the separation distance L _d is created, as shown in FIG.
The result shown by the alternate long and short dash line in (b) was obtained. Extrapolation surface 78a
Is lower on the rear upper side than the outer insertion surface 78b, that is, when the offset dimension L _j is large, the separation distance L _d is large on the rear 74 side, and the outer distance shown in FIG. As compared with the case of the insertion surface 78b, the separation distance L _d on the rear 74 side is increased, and the contact timing is accelerated.
As shown in FIG. 4A, the distribution of the separation distance L _d becomes substantially parallel to the lower side of the window portion 72, and the front 76 and the rear 7
Pressing is applied to 4 at substantially the same time. In the case of the extrapolation surface 78b shown in FIG. 14B, the contact timing on the rear 74 side is later than that on the front 76 side, and defects such as surface distortion are likely to occur in the rear 74 portion.

A concrete example will be described with reference to the flow charts of FIGS. 7 and 8. In step S3 subsequent to step S2, based on the characteristic point that a defect occurs from the past results of the pressed products having substantially the same shape. A plurality of evaluation points P _i (not shown) for evaluating the contact timing are set, and in step S4, the contact order when appropriate press quality is obtained for these evaluation points P _i is set as past data. Specify based on

Then, after executing steps S5 to S8, it is determined in step S9 whether or not there is curvature reversal in the pressing direction for each of the temporary punches PF62 created by dividing into four sides. The determination as to whether or not the curvature is reversed may be performed by visually recognizing the displacement of the temporary punch PF62 in the pressing direction by an image display, or by calculating the curvature of each portion by an arithmetic expression or the like. If there is no curvature reversal in any of the temporary punches PF62, the above step S1 is performed.
The extrapolation surface 56 is created by setting the inclination angle θ _k by executing steps 1 to S13. If curvature inversion exists, step S10 is executed and the projection point R of the side where the curvature inversion exists exists. any offset dimension L _j of _j the change amount ΔL
Change (increase or decrease) only. When the offset dimension L _j is changed, step S8 is executed again to recreate the temporary punch PF62 according to the new wrinkle presser reference point S _j , and steps S10 and S8 are repeated until the curvature inversion disappears. When the provisional punch PF62 is first created in step S8, the procedure at that time and the numerical values of various parameters such as the offset dimension L _j are stored in the auxiliary storage device 36 or the like.
A new temporary punch PF62 is automatically created only by changing the offset dimension L _j in step S10.

In step S14, whether or not there is a curvature reversal in the pressing direction on the outer peripheral line 64 of the extrapolation surface 56 is determined on a substantially straight line in the pressing direction as in the case of the temporary punch PF62 in step S9. If there is no curvature inversion, step S15 and the following steps are executed, but if there is curvature inversion, step S17 is performed.
The tilt angle θ _k is changed (increased or decreased) by an arbitrary change amount Δθ. Then, the changed tilt angle θ _k is equal to the upper limit value θ _max.
Whether or not it is below is determined in the next step S18, and the upper limit value θ
_{If max is} less than or equal to step S13 and subsequent steps are repeated, θ
_{If k} > θ _max, the process returns to step S10 of FIG. 7 to change the offset dimension L _j , and then step S8 and the subsequent steps are executed. When the determination in step S18 is NO and step S10 is executed, the tilt angle θ _k is
The initial value initially set at 13 is restored. In addition, when the extrapolation surface 56 is first created in step S13, numerical values of various parameters such as the procedure at that time and the tilt angle θ _k are stored in the auxiliary storage device 36 and the like, and the tilt angle θ _k is changed in step S17. A new extrapolation surface 56 is automatically created by simply doing this.

In step S15, the interpolating surface 70 is created according to a predetermined arithmetic expression using the shape of the extrapolating surface 56 and the material of the press blank 18 as parameters. In step S16, the extrapolating surface 56 and the interpolating surface 70 are formed. The separation distance L _d in the press direction from the surface 70 to the three-dimensional model 60 is obtained for each evaluation point P _i , and the order from the larger separation distance L _d and the contact order designated in step S4 are the same or not. The quality of the extrapolation surface 56 is determined depending on whether or not. When calculating the separation distance L _d , a contour line distribution map as shown in FIG. 11 and FIG. 14 may be obtained, but the positions of the extrapolated surface 56 and the interpolated surface 70 and the three-dimensional model 60 may be calculated. It is also possible to calculate geometrically from the relationship.
If the order of the separation distance L _d and the designated order of contact are the same, there is no problem and the series of design operations is ended. However, if they are different, step S17 and subsequent steps are executed, and steps S9 and S14 are executed. Are both YES and the determination in step S16 is OK, the tilt angle θ _k and the offset dimension L _j are changed to correct the extrapolation surface 56. The steps S3 and S4 may be performed at least before the step S16 is executed.

According to the wrinkle holding surface designing method of the present embodiment, whether the wrinkle holding surface, that is, the extrapolation surface 56 is appropriate for obtaining proper press quality is determined by the distribution of the separation distance L _d , Specifically, since it is possible to quantitatively evaluate at the designing stage by the contact order at the evaluation point P _i , a defect occurs at the tryout stage as compared with the conventional case where the wrinkle holding surface is designed only by the experience of the designer. This reduces the man-hours and the time required to correct the mold, and it is possible to objectively judge the quality, so that even an inexperienced person can relatively easily design the wrinkle holding surface.

When the suitability of the extrapolation surface 56 is evaluated in this manner, the extrapolation surface 56 is to be corrected many times as necessary, but in the present embodiment, the offset dimension L _j and the inclination angle θ _k. The extrapolation surface 56 is set by using as a parameter, and a new extrapolation surface 56 is automatically created only by changing those values. Therefore, the extrapolation surface 56 can be easily and quickly corrected. The appropriate extrapolation surface 56, that is, the wrinkle holding surface can be easily designed in combination with the above quantitative evaluation.

Further, in the present embodiment, the outer insertion surface 56 is designed so that there is no curvature reversal in the pressing direction on the inner peripheral line of the outer insertion surface 56, that is, the temporary punch PF62 and the outer peripheral line 64. The occurrence of defects at the tryout stage due to the inflow resistance of the material 18 is further reduced. Moreover, the presence or absence of curvature reversal is determined before the complicated calculation process for creating the interpolated surface 70 that is a three-dimensional curved surface, and the offset dimension L _j and the inclination angle θ _k are changed as necessary to change the extrapolated surface. Since 56 is modified, the interpolation surface 70
Design time is shortened compared with the case of making a judgment after creating. In particular, since the curvature inversion of the temporary punch PF62 is determined before the extrapolation surface 56 is created, there is an advantage that the design time can be further shortened.

In this embodiment, steps S1 and S2 are three-dimensional model creating steps, and steps S7, S8, S11 and S are steps.
12, S13 is a wrinkle holding surface creating step, and steps S9,
S14 is a curvature reversal determination step, step S15 is a material shape creation step, step S16 is a wrinkle holding determination step,
Steps S10 and S17 are the wrinkle holding surface correction process.

Next, the parametric CAD device 30.
A procedure for designing the shape of the gradually changing portion whose sectional shape gradually changes according to the invention of claim 3 will be described with reference to the flowchart of FIG. Of the steps in the flowchart of FIG. 15, the double-lined frame step relates to the mold design including the gradually changing portion, and the other steps relate to the evaluation and correction of the gradually changing portion. The mold design procedure will be described. In steps R1 and R2, the three-dimensional model 60 is created and the pressing direction is determined in the same manner as in steps S1 and S2 of the above embodiment, and in step R3, the wrinkle holding surface 80 (FIG. 17) is formed in the same manner as in the above embodiment. , See FIG. 18).

In step R5, a surplus shape of a constant cross section is created. For example, the three-dimensional model 60 shown in FIG. 16 will be specifically described. The cross-sectional shapes of the glass fitting portion 82 into which the back glass is fitted and the opening portion 84 of the trunk parallel to the pressing direction are shown in FIGS. 17 and 18, respectively. As shown by the solid line, it has a negative angle in the pressing direction and cannot be pressed as it is. Therefore, as shown by the alternate long and short dash line, create extra thicknesses 86 and 88 that open to the outside, and use it for the purpose of post-process bending and bending. And finish the product shape. FIG.
The extra thickness 86 of 7 is, for example, after being extended by a dimension L ₃ = L _{1 in} a direction opened outward by a predetermined angle ψ ₁ from the pressing direction,
Extend the dimension L ₄ = L ₂ + β (β is a predetermined constant) so as to incline downward from the horizontal direction (a plane perpendicular to the pressing direction) by a predetermined angle ψ ₂ , and further from the pressing direction by a predetermined angle ψ _3. It can be created by extending the wrinkle holding surface 80 in the outward opening direction. Further, the extra thickness 88 in FIG. 18 can be created by, for example, extending in a direction opened outward by a predetermined angle ψ ₄ from the pressing direction until it reaches the wrinkle holding surface 80, but the dimension L ₆ > L ₅ −γ (γ is In the case of (predetermined constant), it is desirable to provide a shelving rack as indicated by the chain double-dashed line so that L ₇ ≦ L ₅ −γ.
In the present embodiment, these extra thicknesses 86 and 88 are the first shape parts,
It is a three-dimensional model of a 2nd shape part. In addition, other surpluses will be appropriately created as necessary.

At the next step R6, the start point t _s and the end point t _e of the gradually changing section for smoothly connecting the extra thicknesses 86 and 88 are set so that the drawing process can be properly performed.
In this gradual change section, the relationship such as L ₁ = L ₃ is broken and the product has a crease, and it is difficult to perform punching in the pressing direction, and it is necessary to pull out the product. The press quality deteriorates and a large pulling die is required.Therefore, it is desirable that the gradual change section be as narrow as possible in order to improve the press quality and compact the press equipment. If the width is narrow, the shape changes rapidly, and defects such as cracks, wrinkles, and surface strain are likely to occur. Therefore, the start point t _s and the end point t _e
In this setting, the shape of the extra thicknesses 86 and 88 will be appropriately determined based on past experience and the like. However, for example, it may be set to be relatively small at the beginning and enlarged as necessary. .

In step R7, the gradual change specified value u is set, and in step R8, the gradual deformation state within the gradual change section is created according to a predetermined arithmetic expression using the gradual change specified value u as a parameter. The arithmetic expression, for example by varying depending sectional shape gradually changing the specified value u in Xu midpoint of varying intervals _{(t s + t e) /} 2 as shown in FIG. 19,
The cross-sectional shape of each part between t _s and t _e is determined so as to change as shown by the solid line, the one-dot chain line, and the two-dot chain line. The cross-sectional shape in the gradually changing section is 0 to 0 when the cross-sectional shape of the excess thickness 86 portion is "0" and the cross-sectional shape of the excess thickness 88 portion is "1".
It is determined by the numerical value of 1, and the gradual change specified value u is, for example, 0.
5 may be initially set, or the designer may set an arbitrary value. FIG. 20 is a perspective view showing an example of the gradual deformation of the surplus in such a gradual change section. The one-dot chain line, the two-dot chain line, and the broken line are the starting points t _s ,
The cross-sectional shape at the end point t _e and the intermediate point (t _s + t _e ) / 2 is shown. It should be noted that the position where the cross-sectional shape becomes 0.5 is shifted to the start point t _s side and the end point t _e side according to the gradual change specified value u to change the gradual deformation state, and the gradual change specified value u is used as a parameter. The arithmetic expression for creating the shape can be set appropriately.

Next, a procedure for evaluating whether or not the gradually deformed shape designed as described above is appropriate for obtaining an appropriate press quality will be described. First, in step R4 of FIG. 15, FIG. As shown in the drawing, by contacting the punch die 14 before the drawing work is performed during the press work, the contact line 90 of the portion where the material hardly moves in the drawing work is obtained. FIG. 21 shows the punch type 14 and the die type 12, but in step R4, the three-dimensional model 60 and the wrinkle holding surface 80 are used to form the contact line 9
You'll be looking for zero. Further, although the surplus shape has not yet been determined at the stage of step R4, it is possible to obtain the hatching line 90 independently of the surplus shape. However, if the contact line 90 changes depending on the extra shape,
It is desirable to obtain the contour line 90 after creating the surplus, and for example, step R4 may be executed after step R8.

In step R9, which is executed after step R8, the average sectional line length change rate α is calculated for a plurality of sites in the gradually changing section as shown in FIG. The average sectional line length change rate α is as shown in FIG.
The distance L _P from 0 to the temporary punch PF62 is divided by the length L _B of the corresponding portion of the press blank 18 before press working, and is represented by a value L _P / L _{B. In} the next step R10, this average is calculated. It is determined whether or not the maximum value α _max of the cross-section line length change rate α and the slope φ of the average cross-section line length change rate α satisfy a predetermined relationship so as to obtain appropriate press quality. This relationship is based on past results, experiments, simulations, etc., depending on the material and plate thickness of the press material 18,
Alternatively, it is determined for each type of pressed product including these pressing conditions. Generally, as shown in FIG. 23, the larger the maximum value α _max and the inclination φ, the more difficult it is to obtain appropriate press quality, and the maximum value α _max , The smaller the inclination φ, the easier it is to obtain an appropriate press quality, and it can be judged whether or not the press quality is appropriate, for example, depending on whether or not it is within the range on the lower left of the solid line in FIG. Above inclination φ
Changes depending on the scale of the horizontal axis (position) in FIG. 22, so the scale of the position when the inclination φ is obtained is fixed. The inclination φ may be represented by a ratio Δα / Δt between a change amount Δα of the average sectional line length change rate α and a position displacement amount Δt.

Then, the maximum value α_maxAnd the slope φ is
If the predetermined relationship is satisfied,
If the judgment of R10 is OK, the above steps
Punch type using the three-dimensional model 60 of the pressed product obtained in
Design the molding surfaces 20 and 28 of the mold 14 and the die die 12.
become. However, the maximum value α_maxAnd the slope φ is predetermined
If the relationship is not satisfied, go to step R11.
And whether the gradual change specified value u is greater than 0 and less than 1
If 0 <u <1, gradually change in step R13.
Change (increase or decrease) the specified value u by an arbitrary change amount Δu
If u is 0 or less, or 1 or more, in step R12
Expand the gradually changing section. In step R13, change the specified value u
If changed, immediately execute steps R8 and below to
The gradual deformation is corrected according to the gradual change specified value u after renewal.
If the gradual change section is expanded at step R12, step R7
After returning the gradual change specified value u to the initial setting value with step R8 or later
Run below. Create a gradual deformation shape first in step R8
Then, the procedure at that time and the starting point t _s, End point t_e, Gradual change specified value
The numerical value of u is stored in the auxiliary storage device 36 or the like.
In step R13, the value of the gradual change specified value u is changed,
Start point t at R12_sOr end point t_eThe value of is changed
And a new gradual change with the same procedure depending on those parameters.
The shape is created automatically. And this new gradual deformation
Steps R9 and R10 according to
Repeat step R11 and subsequent steps until the determination of 0 is OK
Then correct the gradual deformation. The expansion of the gradually changing section
Point t_sAnd the end point t_eEven if you change both
It is also possible to change only one of them.

Here, since the maximum value α _max is determined by the shape of one end of the gradual change section, it does not change even if the gradual deformation state is changed, but the inclination φ changes with the gradual deformation state. It can be changed to obtain a proper press quality. The slope φ becomes smaller if the gradual change section is lengthened, but the gradual change section is provided so that proper press quality can be obtained. As the gradual change section becomes large, there is the inconvenience that the press quality deteriorates and a large pull-out die is required because the gradual change section becomes necessary, and it is desirable that the gradual change section be as small as possible. First, in step R13, the gradual change specified value u is dealt with, and when it is not possible to change the gradual change specified value u alone, step R12 is executed to expand the gradual change section, thereby making the gradual change section as small as possible. A gradual deformation state is defined that can maintain proper smallness and obtain proper press quality. If the determination in step R11 is NO, then the gradual change specified value u
Means that the determination in step R10 did not become OK even if the value is changed within the range of 0 <u <1. In step R13, for example, the gradual change designation value u is fixed up and down from the initial setting value “0.5”. It may be changed in increments of values.

As described above, according to the gradual deformation pattern designing method of this embodiment, whether or not the gradual deformation pattern is appropriate for obtaining proper press quality is determined by determining the maximum value α _max of the average sectional line length change rate α. Since it can be quantitatively evaluated at the design stage from the relationship between and the inclination φ,
Compared to the case of designing a press die only by the experience of a designer as in the past, the occurrence of defects at the tryout stage is reduced, the man-hours and time required for die correction are reduced, and the objective Since the quality can be judged, even a inexperienced person can relatively easily design the gradually deformed shape.

When the suitability of the gradual deformation state is evaluated in this way, the gradual deformation state must be corrected many times as necessary, but in this embodiment, the designated gradual change value u, the starting point t _s , and the end point. The gradual deformation state is set with t _e as a parameter, and a new gradual deformation state is automatically created only by changing those values. Therefore, the gradual deformation state can be easily and quickly corrected. In combination with the above quantitative evaluation, it becomes possible to easily design an appropriate gradual deformation pattern.

The correction of the gradual deformation state is dealt with by first changing the gradual change designated value u.
Since it is designed to expand the gradual change section when it is not possible to change only by grading, the gradual deformation state is set so that the proper press quality can be obtained while keeping the gradual change section as small as possible. It is possible to minimize the change in the shape.

In this embodiment, step R5 is a three-dimensional model producing step, steps R7 and R8 are stepwise producing steps, step R9 is a change rate calculating step, and step R10.
Is a change rate determination step, and step R13 is a gradual deformation correction step.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention can be implemented in other modes.

For example, in the above embodiment, the press die 10 arranged in the single action type press machine has been described, but the present invention is also applicable to the design of the press die arranged in the double action type press machine. It can be applied similarly.

Further, in the above-mentioned embodiment, the press die for drawing the rear quarter panel of the automobile has been described as an example, but the present invention is applicable to the press die for drawing not only other panels of the automobile but also products other than the automobile. The invention can be applied as well.

Further, in the first embodiment, the positions separated by the offset dimension L _j are the wrinkle holding surface, that is, the extrapolation surface 56.
However, the outer peripheral line or the center line of the wrinkle holding surface may be set according to the offset dimension L _j .

In the first embodiment, the curvature reversal is judged for both the temporary punch PF62 and the outer circumference 64 which are the inner circumference of the extrapolation surface 56, but the curvature reversal is judged for one of them. You may just judge. In carrying out the first invention, such determination of curvature reversal is not always necessary.

In the second embodiment, the first shape portion and the second shape portion are the margins 86 and 88 that are bent close to each other, but it is necessary to provide a gradually changing portion whose sectional shape gradually changes. The present invention can be similarly applied when designing a press die for other pressed products.

In the second embodiment, the average cross-section line length change rate α at the starting point t _s and the end point t _e is calculated before calculating the average cross-section line length change rate α at a plurality of sites in the gradually changing section. Then, determine the average slope φ _av within the gradual change interval, and determine whether the slope Φ _av and the maximum value α _max satisfy the specified relationship. If not, expand the gradual change interval immediately. It may be done.

In the second embodiment, step R10
Although the gradual change section is expanded until the determination of OK is made, conversely, the gradual change section is set to a large value and is reduced until the determination of step R10 becomes NG, thereby reducing the gradual change as small as possible. An appropriate gradual deformation state may be determined in the variable section.

Although not illustrated one by one, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between respective steps of the invention described in claim 1.

FIG. 2 is a diagram showing the relationship of each step of the invention described in claim 2.

FIG. 3 is a diagram showing a relationship between respective steps of the invention according to claim 3;

FIG. 4 is a sectional view illustrating an example of a press die.

5 is a perspective view showing a punch die and a wrinkle holding ring of the press die of FIG. 4. FIG.

FIG. 6 is a block diagram illustrating an example of a parametric CAD device preferably used in the design method of the present invention.

FIG. 7 is a flowchart illustrating a specific example of designing a wrinkle holding surface according to the design method according to claims 1 and 2.

FIG. 8 is a flowchart showing a continuation of FIG.

9 is a plan view showing an example of a three-dimensional model created according to the flowcharts of FIGS. 7 and 8. FIG.

10 is a cross-sectional view taken along line XX in FIG.

11 is a diagram showing the distribution of the separation distance L _d in FIG. 10 in contour lines.

12 is a sectional view taken along line XII-XII in FIG.

FIG. 13 is a perspective view showing a three-dimensional model and a wrinkle holding surface of another pressed product different from FIG. 9.

FIG. 14 is a diagram showing the distribution of the separation distance L _d between the two types of wrinkle holding surfaces shown in FIG. 13 and the three-dimensional model. (A) shows the case where the wrinkle holding surface is a broken line, and (b) shows the wrinkle holding surface. Is a solid line.

FIG. 15 is a flowchart illustrating a specific example of designing a gradual deformation pattern according to the design method according to claim 3;

16 is a flow chart of 3 created according to the flowchart of FIG.
It is a top view showing an example of a dimensional model.

FIG. 17 is a diagram illustrating a cross-sectional shape and a surplus shape in the glass fitting portion of FIG.

FIG. 18 is a diagram illustrating a cross-sectional shape and a surplus shape in the trunk opening portion of FIG. 16;

19 is a diagram illustrating a relationship between a cross-sectional shape and a gradual change specified value u in a gradual change section between t _s and t _e in FIG.

20 is a perspective view showing an example of a gradually deformed shape created in step R8 of FIG.

FIG. 21 is a diagram for explaining the sloping line obtained in step R4 of FIG. 15 and the dimensions L _P , L _B used when calculating the average sectional line length change rate α in step R9.

22 is a maximum value α obtained in step R10 of FIG.
It is a figure explaining _max and inclination (phi).

FIG. 23 is a diagram illustrating conditions for obtaining appropriate press quality with respect to the maximum value α _max and the inclination φ of FIG. 22.

[Explanation of symbols]

10: Press die 30: Parametric CAD device 56, 78a, 78b: Extrapolation surface (wrinkle pressing surface) 60: Three-dimensional model 70: Interpolation surface (three-dimensional shape) 86: Extra thickness (first shape portion) 88 : Extra thickness (second shape portion) Steps S1, S2: Three-dimensional model creating step Steps S7, S8, S11 to S13: Wrinkle holding surface creating step S9, S14: Curvature reversal determining step Steps S10, S17: Wrinkle holding surface Correction process Step S15: Material shape creation process Step S16: Wrinkle hold down judgment process Step R5: Three-dimensional model creation process Steps R7 and R8: Gradual deformation shape creation process Step R9: Change rate calculation process Step R10: Change rate judgment process Step R13 : Gradual deformation correction process

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noboru Yamada 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (3)

[Claims] 1. A method for designing a press die for drawing a press product having a predetermined shape by using a parametric CAD apparatus, wherein a three-dimensional model of the press product is obtained by the parametric CA.
A three-dimensional model creating process created by the D device, and an offset dimension L substantially along the outer periphery of the three-dimensional model
By setting _j and tilt angle θ _k respectively,
The offset dimension L _{j in the} press direction from the three-dimensional model
A wrinkle holding surface creating step of forming a wrinkle holding surface inclined at the tilt angle θ _k in a predetermined range at a position spaced apart from each other, and a step inside the wrinkle holding surface when a press material is brought into close contact with the wrinkle holding surface. A material shape creating step of creating a three-dimensional shape of the press material according to a predetermined arithmetic expression using the shape of the wrinkle holding surface and the material of the press material as parameters, and the three-dimensional shape of the press material and the three-dimensional model From the distribution of the separation distance L _d in the pressing direction, a wrinkle pressing determination step of determining whether or not the wrinkle pressing surface is appropriate for obtaining appropriate press quality, and a case where it is determined that the wrinkle pressing surface is not appropriate , the press die, characterized in that it comprises a blank-holding surface modifying step of modifying the offset dimension L _j and the inclination angle θ blank-holding surface by changing at least one of the _k Design method. 2. A curvature reversal determining step of determining whether or not the wrinkle holding surface has a curvature reversal in the pressing direction in the circumferential direction, and if it has a curvature reversal, determining that the wrinkle holding surface is not appropriate. 1. The method for designing a press die according to 1. 3. A press die for drawing a press product having a first shape part and a second shape part, which have different cross-sectional shapes parallel to the press direction and are adjacent to each other, is designed by using a parametric CAD device. A method, comprising: a three-dimensional model creating step of creating a three-dimensional model of the first shape part and the second shape part with the parametric CAD device; and the first shape part and the second shape part in the three-dimensional model. And a step of creating a gradual deformation in the gradual change section in accordance with a predetermined arithmetic expression using the gradual change specified value u as a parameter, and an average cross-section line length for a plurality of sites in the gradual change section. A change rate calculation step for obtaining the change rate α, a maximum value α _max of the average cross-section line length change rate α and a slope φ of the average cross-section line length change rate α are predetermined so as to obtain appropriate press quality. Taseki Change rate determining step of determining whether or not the relationship is satisfied, and changing the specified value u of the gradual change when it is determined that the maximum value α _max and the slope φ do not satisfy a predetermined relationship. A method of designing a press die, comprising: a gradual deformation correcting step of correcting the gradual deformation.