JP3166252B2 - Pattern design equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern designing apparatus ,
More specifically, the present invention relates to a pattern designing apparatus for automatically designing a pattern from design data using a computer.

[0002]

2. Description of the Related Art As a conventional design method of a pattern paper on which the present invention is based, there is disclosed a Japan Society of Mechanical Engineers Transactions, Vol. 54, No. 498 (1988).
"Plane expansion problem of free-form surface by finite element method" and 55
As described in Vol. 511 (1989-3), "Plane expansion problem of free-form surface by finite element method (2nd report, when there are various design constraints)", an example adapted to shoes, aircraft fuselage, etc. There is.

In this method, a curved surface is formed as follows.
Perform one-dimensional development to design one pattern. First expand
The surface to be divided into many triangular meshes (elements)
You. Then, the triangle corresponding to these triangle meshes
Assume a quadrilateral trial plane with a mesh. next,
The shape of the triangular mesh on the quadrilateral trial plane is
Force equal to the shape of the corresponding triangular mesh of
Is given in the trial plane to deform the trial plane.
The trial plane is evaluated and a pattern is designed. This trial plane
In the evaluation, the finite element method, which is a dynamic method, was used.
The strain energy U caused by the displacement of each node in the trial plane
T is calculated and the strain energy UT is 1 × 10 ^-Ten~^-15When
The deformation and evaluation of the trial plane until a value close to 0 is reached.
The value is repeating. For this reason, patterns with complicated curved shapes
When designing a
There was a problem that time increased.

[0004] Here, the strain energy UT is in the x-axis direction, y
The stress in the axial direction is σ _x , σ _y , and the shear stress is τ _xy
, x, y-axis direction of the strain respectively ε _x, ε _{y, xy} shear strain gamma, if the area of the triangle mesh attempt plane as Ap, it is given by the following equation (1).

[0005]

(Equation 1)

[0006] As described above, in the prior art, since the method of evaluating the shape of the trial plane is performed using the strain energy inside the trial plane, a direct one-to-one relationship between the shape of the trial plane and the strain energy is obtained. When designing a pattern by developing a complex curved shape on a plane,
Inevitably, the convergence condition of the strain energy must be reduced, which requires a considerable amount of time for the calculation, which is a practical problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to design a pattern by shortening the calculation time for evaluating a trial plane and developing a curved surface having a complicated shape in a short time. It is an object of the present invention to provide an apparatus for designing a paper pattern.

[0008]

Means for Solving the Problems The present invention to achieve the above object, as well as dividing the curved surface to be expanded into a mesh, and assuming means for assuming the trial plane having a mesh corresponding to each of the mesh , to evaluate whether the modification means and the shape of the mesh on the curved surface corresponding to the shape and the mesh of the mesh on the trial plane Ru deforms the trial plan to be equal, attempts plane after deformation meets the setting conditions Comment
A value unit, Te design apparatus odor <br/> of paper including, the design means for designing the paper on the basis of the trial plan that satisfies the setting condition, the evaluation means, the mesh of the trial plane was last modified When the ratio of the area of the mesh on the curved surface to the area of the mesh on the curved surface is a first ratio, and the ratio of the area of the mesh on the trial plane deformed this time to the area of the mesh on the curved surface is a second ratio, the first ratio Deformation based on the rate of change of the area ratio obtained by the difference between the second ratio and the second ratio, or the ratio of the area ratio obtained by the ratio of the first ratio and the second ratio It is characterized by evaluating whether the subsequent trial plane satisfies the set conditions.

[0009]

According to the present invention, a curved surface to be developed is divided into meshes, that is, elements, and a trial plane having a mesh corresponding to each of the meshes is assumed. Next, the trial plane is deformed so that the shape of the mesh on the trial plane is equal to the shape of the mesh on the curved surface corresponding to the mesh. Then, whether or not the deformed trial plane satisfies the set conditions is evaluated, and a pattern is designed based on the trial plane that satisfies the set conditions. In this case, the present invention evaluates whether the deformed trial plane satisfies the set conditions based on the rate of change of the area ratio between the trial plane and the curved surface or the ratio of the area ratio.

The change ratio Dr of the area ratio is expressed by: As is the area of the mesh on the curved surface, Ap is the area of the mesh on the trial plane, n
Is given by the following equation (2).

[0011]

(Equation 2)

Here, t represents the number of deformations of the trial plane.
The present inventors examined the relationship between the value of the change rate Dr and the calculation time, and compared the developed shape with a conventional determination method using strain energy. The results are shown in Tables 1, 2, 3 and FIG. In addition, * 1 in Tables 1, 2, and 3 is an evaluation result by a conventional strain energy evaluation method. According to these tables and figures, it is clear that when the trial plane is deformed and evaluated until Dr ≦ 1.0%, a pattern paper substantially equivalent to the conventional determination method can be obtained in less than half of the conventional time. It became.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

By modifying the above equation (2), the following equation (3) is obtained.

[0017]

(Equation 3)

Therefore, instead of the area ratio change ratio Dr, the area of the curved surface with respect to the area of the trial plane deformed at the t-th time with respect to the area ratio between the area of the trial plane deformed at the (t + 1) -th time and the area of the curved surface The trial plane may be evaluated based on whether or not the ratio of the area ratio satisfies 1.01 or less.

In the above description, the ratio of the element of the curved surface, ie, the area of the mesh, to the element of the trial plane, ie, the area of the mesh, is used. However, the reciprocal may be used.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 3 shows hardware for applying the pattern designing method of the present embodiment. The hardware includes a personal computer 10, a keyboard 12 for inputting various data, and a personal computer 1.
A display 14 and a printer 16 are provided for displaying the result of the processing at step S0.

Next, the software of this embodiment will be described with reference to FIG. In step 30, the three-dimensional design determined by CAD or the like is fetched, and
In step 2, convert the surface of the three-dimensional design
Divide into rectangular meshes. FIG. 4 schematically shows an example in which the curved surface 18 is divided into a large number of triangular meshes 20. In this example, the curved surface 18 is divided into 2 (N−1) · (M−1) triangular meshes 20 by N points vertically and M points horizontally. In the next step 34, the divided triangular mesh is converted into three-dimensional point data.

In the next step 36, based on the three-dimensional point-by-point data, the periphery of the curved surface 18 is regarded as a shape composed of four contour lines, and a quadrangle can be formed as an initial trial plane. Whether this pentagon can be formed
Judgment is made based on the length of one contour line. That is, as shown in FIG. 5, the periphery of the curved surface 18 is regarded as being composed of four contour lines A, B, C, and D having the lengths a, b, c, and d.
, The longest side of the contour line A is set as the bottom side.
Next, the contour lines B and D on both sides of the contour line A are compared, and the shorter contour line, in the example of FIG. 5, the contour line B is perpendicular to the end point of the contour line A as shown in FIG. Stand up. Then, the length of the hypotenuse of the triangle formed by the contour lines A and B (a ² +
b ² ) ^1/2 is compared with the sum c + d of the lengths of the remaining contour lines C and D. If (a ² + b ² ) ^1/2 ≧ c + d, a quadrilateral cannot be formed as a trial plane. on the other hand,
In the case of (a ² + b ² ) ^1/2 <c + d, a quadrilateral can be formed as a trial plane. If it is determined in step 36 that a quadrilateral can be formed as a trial plane, a quadrilateral initial trial plane is created in step 38 and step 3
If it is determined in step 6 that a rectangular trial plane cannot be formed, a pentagonal initial trial plane is created in step 40.
In this way, the perimeter of the initial trial plane and the perimeter of the curved surface are matched.

FIG. 7 shows a quadrilateral trial plane 22 corresponding to the curved surface 18 of FIG. This trial plane 22
4 (M−1) · (N−1) triangular meshes 2 in FIG.
There are provided 2 (M−1) · (N−1) triangular meshes 24 corresponding to each of 0. The hatched triangular mesh 26 located around the trial plane 22 indicates a dummy triangular mesh which is a triangular mesh having higher rigidity than the non-hatched triangular mesh inside. These dummy triangular meshes 26 are necessary to make the perimeter of the pattern paper equal to the perimeter of the curved surface, and the details will be described later.

FIG. 8 shows a pentagonal trial plane 22 corresponding to the curved surface 18 of FIG. The pentagonal trial plane 22 forms a point f until a rectangle is formed by the side E having a length e formed by bending the point f near the center of the contour A and the contours B, C, and D. It is created by bending the two sides sandwiched.

In the next step 42, a plane expansion calculation similar to the conventional one is performed based on the initial trial plane. In the next step 46, it is determined whether or not the trial plane created by judging whether or not the rate of change Dr of the area ratio in the above equation (2) is equal to or less than a predetermined value (for example, 1.0%) can be adopted as the reference pattern paper. Judge. If the rate of change of the area ratio exceeds a predetermined value, in step 44 the triangular mesh on the trial plane and the triangular mesh on the curved surface corresponding to the triangular mesh are focused on, and the mesh shape on the trial plane is The trial plane is deformed so that the mesh shape on the curved surface corresponding to this mesh becomes equal. The manner of this deformation is the same as in the prior art, and a detailed description will be omitted. Next, the above-described plane expansion calculation in step 42 and the determination of the magnitude of the change rate Dr in step 46 are performed, and steps 42, 46, and 44 are repeated until the change rate Dr of the area ratio becomes equal to or less than a predetermined value.

If the change ratio Dr of the area ratio is equal to or smaller than the predetermined value, the trial plane at that time is determined as the reference pattern in step 48.

In the next step 50, the physical properties of the personal computer 10 such as Young's modulus E, Poisson's ratio ν, and shear modulus G are input from the keyboard 12 to thereby allow the personal computer 10 to operate.
In step 52, the pattern is evaluated by comparing the shapes based on a free-form surface development method.
That is, in order to evaluate whether or not the standard paper pattern determined in step 48 is appropriate for the material to be used, it is assumed that the standard paper pattern is bonded to a curved surface, and the physical properties of the material to be used are given, and the stress distribution and strain distribution in the paper pattern are given. Etc. are displayed inside the pattern,
If it is equal to or more than the reference value, it is determined that a defect occurs in the material to be used, and the pattern is corrected. In the modification of the pattern, the pattern is reduced in a similar manner in step 54, an external force is applied to the pattern boundary using the physical properties of the material in step 56, and tensile deformation is performed by using the finite element method to perform tensile deformation. Step 58
Then, the reference pattern and the deformed pattern are compared, and if the reduced and tensile-deformed pattern becomes the same as the reference pattern determined in step 48, the reduced pattern becomes a correction pattern for the material to be used. The paper pattern deformed at 60 is determined as the final paper pattern. In step 58, if the shape of the reduced and tensile-deformed paper pattern does not become the same as the shape of the reference paper pattern, the reduced and tensile-deformed paper pattern is again reduced in a similar manner and subjected to tensile deformation. The deformation is calculated and corrected until the value becomes equal to or less than the evaluation value or the rate of change of the area ratio becomes 1% or less. Thus, a defect-free paper pattern in consideration of the material characteristics can be designed. In addition, the pattern can be automatically designed and evaluated from the design drawing, and can be corrected according to the material properties.
High quality can be promoted. Steps 52 to 60 for correcting the pattern for the material to be used.
9 is shown in FIG.

Next, the dummy triangular mesh will be described in detail. In the related art, if the expansion calculation is performed without giving special consideration to the method of creating the trial plane, the perimeter of the deformed trial plane becomes several percent longer than the perimeter of the curved surface to be expanded. It has been difficult to design a pattern that fits well on a curved surface. For example, in the case of automobile seats, when the skin material cut and sewn based on the pattern is covered with the internal cushion material of the seat, the skin material does not wrinkle or the cushion shape itself does not deform, but the internal cushion shape , But it was difficult with the prior art. In order to solve this problem, it is necessary that the perimeter of the trial plane after the deformation does not change with respect to the perimeter of the trial plane before the deformation. Specifically, a highly rigid triangular mesh or the like may be arranged along the periphery of the trial plane to prevent the peripheral length of the trial plane from being deformed.

That is, a curved surface to be developed is divided into meshes, and a trial plane having a mesh corresponding to each of the meshes is assumed, and a mesh shape on the trial plane and a mesh on a curved surface corresponding to the mesh are assumed. The trial plane is deformed so that the shape of the trial plane becomes equal, the trial plane after the deformation satisfies the set conditions is evaluated, and the template is designed based on the trial plane that satisfies the set conditions. Assuming a trial plane whose circumference is within a predetermined range with respect to the circumference of the curved surface to be developed, a dummy mesh having high rigidity may be arranged along the periphery of this trial plane.

The above-mentioned predetermined range is preferably within the range of -2% to + 0.1% with respect to the circumference of the curved surface to be developed. This is because, assuming that the perimeter of the curved surface to be developed is shorter than 2%, the shape of the trial plane after deformation appears, and when the cloth is cut by this effect and covered on the curved surface (laminated This is because, when the appearance is wrinkled and the length is assumed to be more than 0.1% of the circumference of the curved surface to be developed, the appearance of the cloth becomes slack when the cloth is cut and covered with the curved surface. Further, the position at which the dummy mesh is arranged may be inside (FIG. 7), outside (FIG. 10), or both inside and outside (FIG. 11) the trial plane. The rigidity of the dummy mesh is the Young's modulus of one of the meshes other than the dummy mesh.
A ratio of 00 to 10000 is appropriate. Further, the shape of the mesh including the outer peripheral line of the trial plane may be the same as the shape of the corresponding mesh of the curved surface to be developed, and the rigidity of the mesh including the outer peripheral line may be increased as described above.

As described above, by assuming a trial plane having a perimeter within a predetermined range and arranging a highly rigid dummy mesh along the periphery of the trial plane, when the trial plane is deformed, the dummy mesh having a high rigidity is obtained. Thus, a pattern that fits well on a curved surface to be developed can be designed without deformation around the trial plane. When a curved surface is divided into a plurality of patterns and developed in a plane, the peripheral lengths of the adjacent patterns can be matched, and similarly, a pattern group well fitted to the curved surface can be designed.

[0032] To apply the present invention to the above principles, as well as dividing the curved surface to be developed in the mesh, it is assumed attempts plane having a mesh corresponding to each of the mesh virtual
Satisfies a constant means, and deformable means, Ru deform the trial plane as the shape of the mesh on the curved surface corresponding to the shape and the mesh of the mesh on the trial plane are equal, the trial plane after deformation is setting conditions and evaluating means for evaluating whether there, designed hand to design the paper on the basis of the trial plan that satisfies the setting condition
Apparatus for designing a paper containing a stage, the said evaluation means
Is the ratio between the area of the mesh on the trial plane and the area of the mesh on the curved surface that was deformed last time, and the ratio of the area of the mesh on the trial plane and the area of the mesh on the curved surface this time is When the second ratio is set, the difference between the first ratio and the second ratio and the change ratio of the area ratio obtained by the ratio of the second ratio, or the difference between the first ratio and the second ratio Whether or not the trial plane after deformation satisfies the set condition may be evaluated based on the ratio of the area ratio obtained by the ratio.

This makes it possible to reduce the number of repetitions of the calculation of the pattern design, and to design a pattern that is well fitted to the curved surface to be developed.

Next, in the case where the plane development is performed under the same conditions as the circumference of the trial plane and the circumference of the trial plane, as shown in FIG. A method in which a plane on which the mesh 26 is arranged is used as a trial plane (internal dummy triangular mesh method), and a plane in which a highly rigid dummy triangular mesh 26 is arranged around the boundary of the trial plane 22 as shown in FIG. A method of setting a trial plane (external dummy triangular mesh method) and a method of arranging a dummy triangular mesh of an external dummy triangular mesh method only at corners of each side as shown in FIG. A description will be given in comparison with a combined method in which dummy triangular meshes of the rectangular mesh type are arranged. In the external dummy triangular mesh method, the number of elements is increased by the external dummy triangular mesh compared to the internal dummy triangular mesh method. On the other hand, in the internal dummy triangular mesh method, a triangular mesh located around the boundary of the trial plane 22 is used as a dummy triangular mesh as shown in FIG. The dummy triangular mesh 26 having high rigidity is arranged. Comparing the number of elements of the external dummy triangular mesh method and the number of elements of the internal dummy triangular mesh method, the number of elements in FIG. 10 is 2 (MN-1) in the external dummy triangular mesh method, The number of elements is 2 (M−1) · (N−1) as described above. Comparing the numbers of both elements, 2 (MN−1)> 2 (M−1) · (N−1), the number of elements of the internal dummy triangular mesh method is smaller than the number of elements of the external dummy triangular mesh method, This is advantageous for the calculation processing time. Here, M and N> 3. In addition, Table 4 below shows the results obtained by examining the calculation time of the external dummy triangular mesh method and the internal dummy triangular mesh method. Note that the three-dimensional curved surface shapes of * 1 and * 2 in Table 4 are omitted. As can be understood from Table 4, the calculation time of the internal dummy triangular mesh method is equal to the external dummy 3
It can be understood that the calculation time is shorter than the calculation time of the rectangular mesh method, and the calculation processing time is shorter when the number of elements is smaller.

[0035]

[Table 4]

If an external dummy triangular mesh is provided for each of the two triangular meshes at the corners of the trial plane as in the combined system shown in FIG. 11, the corners are more easily deformed than the internal dummy triangular mesh system. Therefore, the shape of the corner portion can be made accurate. The number of elements of this combined method is 2 (N-1). (M-1)
+8, which is eight more than the number of elements of the internal dummy triangular mesh method described above, but less than the number of elements of the external dummy triangular mesh method. However, when comparing the number of elements of the external dummy triangular mesh method, the internal dummy triangular mesh method, and the combination method, 2 (MN-1)> 2 (M-1). (N-1) +8
> 2 (M−1) · (N−1), and it is clear that the calculation processing time is similarly in this order, and the calculation time can be reduced as compared with the external dummy triangular mesh method.
In addition, the combination method is to use external dummy 3 only at the corners described above.
It goes without saying that the rectangular mesh can be arranged at an appropriate position in addition to the arrangement.

Next, the effect of this embodiment will be described in comparison with the prior art. In the related art, since the perimeter of the curved surface is not flattened under the same conditions as the perimeter of the trial plane, when the cloth is cut with the obtained pattern and covered with the curved surface to be developed, the cloth has a lot of slack. Appearance was not obtained and good results were not obtained. On the other hand, in the present embodiment, since a trial plane whose peripheral length is within a predetermined range with respect to the peripheral length of the curved surface to be developed is assumed, it is possible to design a pattern that is well fitted to the curved surface to be developed.

Further, since the convergence determination of the repeated calculation of the plane expansion calculation is performed based on whether or not the area ratio between the curved surface and the plane becomes 1 or a value close to 1, the area and the curved surface which are substantially equal to the area of the curved surface are determined. Can be efficiently obtained in a short calculation time, that is, a pattern having both a perimeter substantially equal to the perimeter of the pattern, that is, a pattern that is well fitted to the shape of the curved surface.

Further, in the prior art, when plane development is performed by making the peripheral length of the curved surface the same as the peripheral length of the quadrilateral as the trial plane, there is a problem that the quadrilateral as the trial plane may not be formed. However, in the above embodiment, it is determined whether a quadrilateral or a pentagon can be formed as a trial plane, and a trial plane suitable for each is created.
Regardless of the values of the four sides constituting the periphery of the curved surface, a trial plane for designing the pattern can be automatically created. Therefore, an efficient and versatile pattern design can be performed.

In the prior art, since the same pattern paper is produced irrespective of the physical property values of the materials, there has been a problem that it is not possible to evaluate whether the properties of the cloth using the pattern paper are appropriate. In the above embodiment, the material characteristics such as Young's modulus and Poisson's ratio are given to the relationship between the triangular mesh which is each element inside the pattern and the triangular mesh which is an element on the curved surface corresponding to this triangular mesh, and finite. The stress applied to each triangular mesh is determined by the element method, and the stress distribution for the material properties is calculated from the stress.
The strain distribution and the like are displayed inside the pattern. Therefore, it is possible to judge and evaluate whether the pattern is appropriate for the material to be used, and it is possible to design an effective and versatile pattern. Further, if it is evaluated that a defect (wrinkle, breakage, etc.) occurs, the pattern is corrected. In this case, the value to be evaluated is a value preset according to the material used. In other words, if it is determined that a defect occurs in the material to be used when it is configured with the designed reference paper pattern, the reference paper pattern is reduced in a similar manner, and the physical properties such as the Young's modulus, Poisson's ratio, and shear rigidity of the material are reduced. Apply the external force to the value and the pattern boundary, respectively, perform the tensile deformation calculation using the finite element method, and when the result becomes the same as the reference pattern, terminate the calculation and use the reduced pattern as a pattern using materials etc. . On the other hand, if the pattern after the tensile deformation calculation does not have the same shape as the reference pattern, the reduced pattern is reduced in a similar manner again, and the tension calculation by the above method is repeated until the pattern has the same shape as the reference pattern. Therefore, it is possible to design a pattern paper having no defect in consideration of the physical property values of the material. In addition, by incorporating this pattern designing method into a pattern designing apparatus, even a pattern evaluation can be corrected, and versatility can be further improved. Therefore, if the designed pattern is not suitable for the material to be used, the pattern can be corrected.

[0041]

As described above, according to the present invention, since the trial plane is evaluated based on the rate of change or the ratio of the area ratio between the trial plane and the curved surface, the shape of the developed plane and the curved surface is evaluated. Are directly associated with each other, so that it is possible to reduce the number of calculation repetitions of the pattern design, thereby obtaining an effect of shortening the calculation time.

In the conventional case, even if the developed shape is the same, if there is a local residual strain, the calculation is repeated to reduce the distortion. Therefore, it takes time to converge and the calculation time increases. In the present invention for comparing the shapes, if the convergence is made, the residual strain as described above can be ignored, so that the convergence can be made faster and the calculation time can be shortened.

[Brief description of the drawings]

FIG. 1 is a flowchart showing software of an embodiment of the present invention.

FIG. 2 is a diagram comparing the developed shapes of the prior art and the present invention.

FIG. 3 is a block diagram illustrating a hardware configuration according to an embodiment of the present invention.

FIG. 4 is a schematic view of a curved surface divided into a triangular mesh.

FIG. 5 is a schematic diagram of a curved surface divided into meshes.

FIG. 6 is a diagram for explaining that a quadrangle is not formed as a trial plane.

FIG. 7 is a schematic diagram showing a quadrilateral trial plane.

FIG. 8 is a schematic diagram showing a pentagonal trial plane.

FIG. 9 is a flowchart for explaining pattern evaluation by material.

FIG. 10 is a schematic diagram of a trial plane in which dummy triangular meshes are arranged on the outer periphery.

FIG. 11 is a schematic diagram of a trial plane in which external dummy triangular meshes are arranged only at corners.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Personal computer 12 Keyboard 14 Display 16 Printer 18 Curved surface 20 Triangular mesh 22 Trial plane 24 Triangular mesh 26 Dummy triangular mesh

Continued on the front page (72) Inventor Kazuyoshi Fujisaka 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Yuji Okamoto 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation (56) Reference References JP-A-63-252725 (JP, A) Tetsuo Shimada et al., "Planning expansion problem of free-form surface by finite element method (2nd report, when there are various design constraints)", Transactions of the Japan Society of Mechanical Engineers (C Ed.), Vol. 55, No. 511, March 1989, p. 810-817 (58) Field surveyed (Int. Cl. ⁷ , DB name) G06F 17/50 JICST file (JOIS)

Claims (4)

(57) [Claims] An estimating means for dividing a curved surface to be developed into meshes and assuming a trial plane having a mesh corresponding to each of the meshes; a mesh shape on the trial plane and a curved surface corresponding to the mesh; and deformable means, and the shape of the upper mesh Ru deform the trial plan to be equal, to assess whether attempts plane after deformation meets the setting conditions
Design a pattern based on the evaluation means and a trial plane that satisfies the set conditions
Apparatus for designing a paper comprising a design unit, wherein the evaluation unit, the previous ratio of first ratio between the area of the mesh on the area of the mesh on the deformed allowed attempts plane and curved, attempts plane deformed current When the ratio of the area of the upper mesh to the area of the mesh on the curved surface is defined as a second ratio, the difference between the first ratio and the second ratio and the area ratio obtained by the ratio of the second ratio A pattern designing apparatus for evaluating whether a trial plane after deformation satisfies a set condition based on a rate of change or a ratio of an area ratio obtained by a ratio of a first ratio to a second ratio. 2. The method according to claim 1 , wherein said estimating means assumes a trial plane having a perimeter within a predetermined range with respect to a perimeter of said curved surface to be developed,
2. The pattern design according to claim 1, wherein a dummy mesh having high rigidity is arranged along the periphery of the trial plane.
Equipment . 3. The pattern designing apparatus according to claim 2, wherein said predetermined range is set to -2% to + 0.1% with respect to the circumference of a curved surface to be developed. 4. A quadrilateral or pentagon is formed as an initial trial plane by determining the periphery of the curved surface as a shape composed of four outlines and determining the length of the four outlines.
The pattern designing apparatus according to any one of claims 1 to 3.