JP2017211849A - Constitution point calculation device and constitution point calculation program of spring back shape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a constitution point calculation device capable of accurately calculating constitution points in a spring back shape corresponding to the constitution points of a target shape even in a case when a three-dimensional distortion is generated.SOLUTION: The constitution point calculation device includes: a partial position mating part 15 that carries out an alignment between a die shape and a spring back shape using a mesh and a point group, which are generated from a piece of die shape data for each predetermined divided area; and a line length holding deformation part 16 that, after calculating a rotation of the mesh before and after deformation, and based on the calculated rotation, calculates coordinate values mesh vertexes of the spring back shape after being retained in a line length. By carrying out the alignment using the mesh and the point group, even a case where a three-dimensional distortion is generated can be handled. By carrying out the alignment on each divided area, the line length rarely changes. By correcting a change of line length in a rotation space where no length element is included, coordinate values of the mesh vertices can be calculated with minimum changes inline length.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a composition point calculation device and a composition point calculation program for a post-springback shape, and particularly to a molded product when generating mold shape data in anticipation of a springback of a molded product that occurs when press working. The present invention relates to a technique for calculating a constituent point of a post-springback shape corresponding to a constituent point of a shape.

  In press forming of a metal plate, a spring back (bounce back phenomenon) occurs due to residual stress generated during press forming, and the formed product may not be formed into a target shape. On the other hand, a technique is known in which a mold shape of a molding die is generated in advance in anticipation of a spring back of a molded product so that a desired molded product shape can be obtained after the spring back.

  In this type of technology, after calculating the shape change between the target shape of the molded product and the post-springback shape of the molded product press-molded using an actual molding die having this target shape, this difference is calculated. By multiplying the vector by a coefficient “−1”, a prospective vector for predicting springback is calculated. And the prospective metal mold | die shape which anticipated the spring back is produced | generated by offsetting the target shape of a molded article by the part of the prospective vector in the opposite direction of a spring back (for example, refer patent document 1, 2).

  In particular, Patent Literature 1 discloses generating a springback expected shape while approximately maintaining a geometric constraint having a constant length. Further, in Patent Document 2, after the mold shape and the post-springback shape are aligned, the cross-sectional shape of the post-springback shape is fitted to the cross-sectional shape of the mold shape for each cross section, and the cross section of the mold shape is obtained. Calculate the closest point in the cross-sectional shape after fitting the post-springback shape closest to the evaluation point in the shape, and return the closest point to the cross-sectional shape before fitting in the post-springback shape to correspond to the evaluation point of the mold shape It is described that it is calculated as a corresponding point of the post-springback shape.

JP 2011-164709 A JP 2014-78121 A

  It is not preferable that the product line length (cross-sectional line length) changes when generating a prospective mold shape that anticipates springback. For this reason, it has been desired to generate a prospective mold shape without changing the product line length. The springback expected shape generation method described in Patent Document 1 can be said to be one method that meets this demand.

  However, the method described in Patent Document 1 is a method for obtaining data in which phase correspondence is achieved between a mesh (a set of a plurality of triangular polygons) that represents a target shape of a molded product and a mesh that represents a post-springback shape. There is a problem that it is necessary and cannot be applied to data having no corresponding relationship.

  For example, a CAD data representing the target shape of a molded product and a spring obtained by scanning a molded product (spring-backed) using an actual molding die having the target shape with a non-contact measuring instrument There is no phase correspondence between the measurement data of the back-shaped shape. Therefore, the technique described in Patent Document 1 cannot be applied using such CAD data and measurement data.

  Further, the technique described in Patent Document 1 employs a method of sequentially deriving one springback expected shape mesh one by one with a mesh vertex having zero springback displacement as a starting reference point. For this reason, there is a problem that it takes a lot of time for processing.

  On the other hand, in the mold shape generation system described in Patent Document 2, the evaluation result in the mold shape is obtained by fitting the cross-sectional shape of the post-springback shape to the cross-sectional shape of the mold shape (target shape of the molded product). The closest point in the closest post-springback shape is calculated, and the corresponding point in the post-springback shape before fitting is calculated based on the closest point.

  However, in Patent Document 2, since the above-described processing is performed for each cross section of a three-dimensional shape, if a three-dimensional twist occurs in a direction different from the direction of the cross section, the corresponding point is determined with accuracy. There was a problem that it could not be calculated well. In addition, the technique described in Patent Document 2 has a problem that it is not possible to generate a springback expected mold shape that maintains the product line length.

  The present invention has been made to solve such a problem, and when generating a prospective mold shape in anticipation of a springback of a molded product that occurs when pressing, the target shape of the molded product is determined. Applicable even when the phase relationship between the data represented and the data representing the post-springback shape is not achieved, even in cases where three-dimensional torsion has occurred, it can be used as a constituent point of the target shape. It is an object of the present invention to make it possible to accurately calculate the composing point of the corresponding post-springback shape.

  In order to solve the above problems, in the present invention, mold shape data representing the target shape of the molded product and measurement data representing the shape after the spring back of the molded product are input, and from the mold shape data, Generate mesh and point cloud of mold shape. Then, using the generated mesh and point group, alignment of the mold shape and the post-springback shape is performed for each predetermined divided region, and a displacement vector representing the deformation from the mold shape to the post-springback shape is obtained. Ask. Further, using the generated mesh of the mold shape and a mesh obtained by deforming the mesh with a deformation vector, the rotation of the mesh before and after the deformation is obtained, and the mesh vertex of the post-springback shape that is retained in the line length is obtained from the obtained rotation. The coordinate value of is calculated.

  According to the present invention configured as described above, alignment is performed between the mold shape data representing the target shape of the molded product and the measurement data representing the post-spring back shape of the molded product. Since the correspondence between the two data is required, even if the phase correspondence between the mold shape data and the measurement data of the shape after spring back is not taken, it corresponds from the constituent point of the target shape of the molded product. The constituent points (coordinate values of the mesh vertices) of the post-springback shape can be calculated. Further, in the present invention, such alignment is performed using a mesh and a point cloud that do not depend on a specific direction. Therefore, the present invention is not limited to a twist in a direction along a specific cross section, but in any direction. Even in the case where a dimensional twist occurs, the constituent points of the shape after the spring back can be calculated.

  Further, in the present invention, since the alignment between the mold shape and the post-springback shape is performed for each of the divided areas, it is possible to perform alignment that hardly causes a change in line length. Furthermore, in the present invention, a change in line length that can be caused by partial alignment is corrected in a rotation space that does not have an element of the length of how the mesh vertex rotates, not how the mesh vertex position changes. Therefore, it is possible to calculate the coordinate value of the mesh vertex with the minimum change in line length. Thereby, the composing point of the post-springback shape can be calculated with high accuracy.

It is a block diagram which shows the example of an overall function structure of the constituent point calculation apparatus of the shape after spring back by this embodiment. It is a block diagram which shows the function structural example of the partial position alignment part by this embodiment. It is a block diagram which shows the function structural example of the line length holding | maintenance deformation | transformation part by this embodiment. It is a figure for demonstrating the processing content of the mesh production | generation part and point cloud production | generation part by this embodiment. It is a figure for demonstrating the processing content of the feature point extraction part by this embodiment. It is a figure for demonstrating the processing content of the mesh vertex grouping part by this embodiment. It is a figure for demonstrating the processing content of the matching part by this embodiment. It is a figure for demonstrating the processing content of the displacement vector calculation part classified by group by this embodiment. It is a figure for demonstrating the processing content which replaces a some displacement vector by one displacement vector in the displacement vector calculation part classified by group of this embodiment. It is a figure for demonstrating the processing content of the mesh deformation | transformation part by this embodiment. It is a figure for demonstrating the processing content of the deformation | transformation mesh projection part by this embodiment. It is a figure for demonstrating the processing content of the face rotation calculation part by this embodiment, and a vertex rotation calculation part. It is a figure for demonstrating the processing content of the protrusion vector calculation part by this embodiment. It is a figure for demonstrating the presence or absence of generation | occurrence | production of the bending considered in calculation of the gradient matrix used by the vertex coordinate value calculation part of this embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram illustrating an example of an overall functional configuration of a post-springback shape component point calculation apparatus according to the present embodiment. As shown in FIG. 1, the post-springback shape component point calculation apparatus according to the present embodiment includes a mold shape input unit 11, a post-springback shape input unit 12, a mesh generation unit 13, and point group generation as its functional configuration. A part 14, a partial alignment part 15, a line length holding deformation part 16, and a prospective mold shape generation part 17.

  Each of the functional blocks 11 to 17 can be configured by any of hardware, DSP (Digital Signal Processor), and software. For example, when configured by software, each of the functional blocks 11 to 17 is actually configured by including a CPU, RAM, ROM, and the like of a computer, and is stored in a recording medium such as a RAM, ROM, hard disk, or semiconductor memory. Is realized by operating.

  FIG. 2 is a block diagram illustrating a functional configuration example of the partial alignment unit 15 according to the present embodiment. FIG. 3 is a block diagram illustrating a functional configuration example of the line length holding / deforming unit 16 according to the present embodiment. Hereinafter, after describing the overall configuration based on FIG. 1, each specific configuration will be described based on FIGS. 2 to 3.

<Overall configuration: Fig. 1>
In the constituent point calculation device for the post-springback shape according to the present embodiment, the mold shape data representing the target shape of the molded product and the measurement data representing the post-springback shape of the molded product are input, and the mold shape data Then, a mold-shaped mesh and a point group are generated (mold shape input unit 11, post-springback shape input unit 12, mesh generation unit 13, and point group generation unit 14).

  Then, using the generated mesh and point group, alignment of the mold shape and the post-springback shape is performed for each predetermined divided region, and a displacement vector representing the deformation from the mold shape to the post-springback shape is obtained. Obtain (partial alignment unit 15). Further, using a mesh of a mold shape and a mesh obtained by deforming the mesh with a deformation vector, the rotation of the mesh before and after the deformation is obtained, and the mesh that is the constituent point of the post-springback shape that is retained in the line length from the obtained rotation. The coordinate value of the vertex is calculated (line length holding deformation unit 16).

  The processing by the partial alignment unit 15 and the line length maintaining deformation unit 16 is repeated by gradually reducing the granularity of partial alignment division, thereby improving the correspondence between mesh vertices before and after the deformation, and the spring It is possible to improve the calculation accuracy of the mesh vertex of the back shape.

  Finally, using the mesh of the mold shape generated by the mesh generation unit 13 and the mesh of the post-springback shape calculated by the line length holding deformation unit 16, the rotation of the mesh before and after the deformation was obtained and obtained. From the reverse rotation of the rotation, the coordinate value of the mesh vertex, which is the constituent point of the expected mold shape with the line length maintained, is calculated (expected mold shape generating unit 17).

  As described above, in the present embodiment, the partial alignment unit 15 performs alignment between the mold shape and the post-springback shape for each divided region. When positioning is performed as a whole, the more complicated the mold shape, the more parts that do not match, and the difference between the parts that do not match tends to increase. On the other hand, by dividing the area and performing partial alignment, it is possible to reduce non-matching parts and reduce the difference, so that it is possible to perform alignment that is unlikely to change the line length. It is. However, inconsistencies may occur between the divided areas, and there is no guarantee that the overall line length is maintained.

  Therefore, in the present embodiment, the deformation result by the partial alignment unit 15 is further reconfigured by the line length holding deformation unit 16. That is, instead of looking at how the mesh vertex position has changed as in the partial alignment unit 15, in the rotation space that does not have an element of the length of how the mesh vertex has rotated, by partial alignment Correct any possible line length changes. As a result, the coordinate value of the mesh vertex with the minimum change in line length in the post-springback shape is calculated.

  Below, each functional block 11-17 is demonstrated. The mold shape input unit 11 inputs mold shape data representing the target shape of the molded product. The mold shape data input here is CAD data or mesh data. The post-spring back shape input unit 12 inputs measurement data representing the post-spring back shape of the molded product. The measurement data input here is, for example, data obtained by scanning a molded product (spring-backed product) press-molded using an actual molding die having a target shape with a non-contact measuring instrument or the like.

  The mesh generation unit 13 approximates the CAD mold shape data input by the mold shape input unit 11 to a polyhedron, and generates data of a mold shape mesh (a set of a plurality of triangular polygons). When the input data is mesh data, the mesh generation unit 13 remeshes (or simplifies) the input mesh data, and generates data on the mesh of the mold shape. The mesh is constituted by a set of data of triangle vertices. A known technique can be applied as a method for generating mesh data from CAD data.

  The point cloud generation unit 14 generates point cloud data having a density higher than that of the mesh vertices from CAD or mesh mold shape data input by the mold shape input unit 11. A known technique can also be applied to a method for generating point cloud data from CAD data or mesh data.

  FIG. 4 is a diagram for explaining the processing contents of the mesh generation unit 13 and the point cloud generation unit 14. The mesh generation unit 13 generates the mesh 102 shown in FIG. 4B from the mold shape data 101 shown in FIG. The point cloud generation unit 14 generates a point cloud 103 shown in FIG. 4C from the mold shape data 101 shown in FIG. In FIG. 4, the mold shape data, mesh data, and point cloud data are all illustrated in a simple two-dimensional manner. However, in actuality, the mesh and point cloud data are generated in a three-dimensional shape. Yes.

  The partial alignment unit 15 is input by the mesh shape generated by the mesh generation unit 13 and the mold shape represented by using the point cloud generated by the point cloud generation unit 14 and the post-springback shape input unit 12. Alignment with the post-springback shape represented by the measurement data is performed for each predetermined divided region, and as a result, a displacement vector representing the deformation from the mold shape to the post-springback shape is obtained.

  Here, the partial alignment part 15 calculates | requires each corresponding point of the shape after a springback corresponding to each mesh vertex of a metal mold | die shape, and calculates the displacement vector showing the deformation | transformation from each mesh vertex to each corresponding point. The partial alignment unit 15 executes this displacement vector calculation process by aligning the mold shape and the post-springback shape for each divided area. The detailed operation of the partial alignment unit 15 will be described later with reference to FIG.

  The line length holding deformation unit 16 calculates the rotation of the mesh before and after the deformation using the mesh generated by the mesh generation unit 13 and the mesh obtained by deforming the mesh with the deformation vector, and the line length is held from the calculated rotation. Calculate the coordinate value of the mesh vertex of the post-springback shape. The detailed operation of the line length retaining deformation unit 16 will be described later with reference to FIG.

  The prospective mold shape generation unit 17 uses the mesh of the mold shape generated by the mesh generation unit 13 and the mesh of the post-springback shape calculated by the line length holding deformation unit 16 to determine the mesh before and after the deformation. By calculating the reverse rotation of the rotation and deforming the target shape of the molded product inputted as the die shape data by the die shape input unit 11 based on the obtained reverse rotation, the expected die shape whose line length is maintained. Calculate the coordinate values of the mesh vertices.

<Configuration of Partial Positioning Unit 15: FIG. 2>
Next, the functional configuration of the partial alignment unit 15 will be described in detail. As shown in FIG. 2, the partial alignment unit 15 according to the present embodiment includes a grouping unit 21, a displacement vector calculation unit 22, and a mesh deformation unit 23 as functional configurations. The grouping unit 21 includes a feature point extraction unit 21A and a mesh vertex grouping unit 21B. Further, the displacement vector calculation unit 22 includes an association unit 22A and a group-specific displacement vector calculation unit 22B.

  The grouping unit 21 groups the mold shapes represented by the mesh 102 (hereinafter referred to as a pre-deformation mesh) generated by the mesh generation unit 13 for each region having a predetermined size. In the present embodiment, the entire mold shape may be divided into a plurality of regions, and the shape and size of each region may be arbitrary. In addition, in each region, adjacent ones may or may not overlap.

  In addition, it is preferable to perform grouping so that a relatively large bent portion in the mold shape comes near the center of the region. One feature for realizing this is the feature point extraction unit 21A and the mesh vertex grouping unit 21B.

FIG. 5 is a diagram for explaining the processing content of the feature point extraction unit 21A. As illustrated in FIG. 5, the feature point extraction unit 21A extracts the high curvature portion point sequences 111 _{−1 to} 111 ₋₄ from a plurality of locations of the point group 103 generated by the point group generation unit 14 (FIG. 5 ( a)), representative points are extracted as feature points 112 _{-1 to} 112 _-4 from the plurality of point sequences 111 _{-1 to} 111 _-4 , respectively (FIG. 5B). Representative point, for example, the center point in the point sequence 111 _-1 to 111 _-4 high curvature portions. As a method for extracting the representative points, for example, a known K-average method can be applied.

FIG. 6 is a diagram for explaining the processing contents of the mesh vertex grouping unit 21B. As illustrated in FIG. 6, the mesh vertex grouping unit 21B extracts the feature points extracted by the feature point extraction unit 21A from the vertices 114 _{-1 to} 114 _-10 of the pre-deformation mesh 102 generated by the mesh generation unit 13. Grouping is performed for each vertex included in a region indicated by a sphere having a predetermined radius with 112 _{−1 to} 112 _-4 as the center.

FIG. 6A shows the pre-deformation mesh 102 generated by the mesh generation unit 13 and the point group 103 generated by the point group generation unit 14 in an overlapping manner. Of the point group 103 shown in FIG. 6A, four points 112 _{-1 to} 112 _-4 indicate feature points extracted by the feature point extraction unit 21A. As illustrated in FIG. 6A, the feature points 112 _{−1 to} 112 ₋₄ do not necessarily coincide with the positions of the vertices 114 _{−1 to} 114 ₋₁₀ of the pre-deformation mesh 102.

Mesh vertices grouping unit 21B, as shown in FIG. 6 (b), around the four feature points 112 _-1 to 112 _-4, sets an area 113 _-1 to 113 _-4 are represented by a predetermined radius of the sphere Then, the mesh vertices included in the regions 113 _{-1 to} 113 _-4 are grouped together. In the example of FIG. 6, areas 113 _{-1 to} 113 _-4 that allow overlap between adjacent ones are set, and a plurality of mesh vertices included in each of the areas 113 _{-1 to} 113 _-4 are grouped together. ing.

In the example of FIG. 6, the mesh-shaped pre-deformation mesh 102 has a total of ten mesh vertices 114 _{−1 to} 114 _-10 . Among these, the first group 113 _-1 includes four mesh vertices 114 _{-1 to} 114 _-4 . The second group 113 _-2 includes four mesh vertices 114 _{-3 to} 114 _-6 . The third group 113 _-3 is configured to include four mesh vertices 114 _-5 to 114 _-8. The fourth group 113 _-4 is configured to include four mesh vertices 114 _-7 to 114 _-10.

Note that the predetermined radius of the spheres representing the regions of the groups 113 _{-1 to} 113 _-4 may be a fixed value set in advance or may be a variable value according to the mold shape. In the case of the variable value, for example, a rectangular parallelepiped inscribed in the mold shape is temporarily set, and a value obtained by dividing the length of the middle of the three sides by a predetermined number is set as the radius. In this way, the entire mold shape can be divided into moderately sized regions.

For each group generated by the grouping unit 21, the displacement vector calculation unit 22 is input by the mold shape represented by the point group 103 generated by the point group generation unit 14 and the post-springback shape input unit 12. Alignment with the post-springback shape represented by the measurement data is performed, and points corresponding to the vertices 114 _{-1 to} 114 _-10 of the pre-deformation mesh 102 in the point group 103 (that is, the respective vertices 114 of the pre-deformation mesh 114). _{−1 to} 114 ₋₁₀ ) to obtain a displacement vector from the corresponding point of the post-springback shape.

Specifically, the calculation of the displacement vector as described above is executed by the associating unit 22A and the group-specific displacement vector calculating unit 22B. The associating unit 22A is based on the distance between each vertex 114 _{-1 to} 114 _{-10 of the} pre-deformation mesh 102 generated by the mesh generating unit 13 and each point of the point group 103 generated by the point group generating unit 14. Thus, each point of the point group 103 is associated with the mesh vertices 114 _{-1 to} 114 _-10 having the shortest distance.

FIG. 7 is a diagram for explaining the processing content of the associating unit 22A. FIG. 7A shows the pre-deformation mesh 102 generated by the mesh generation unit 13 and the point group 103 generated by the point group generation unit 14 in an overlapping manner. FIG. 7B shows a state in which the vertices 114 _{−1 to} 114 _{-10 of the} pre-deformation mesh 102 are associated with the points of the point group 103.

For example, three points 115 ₋₁ in the point group 103 are associated with the first mesh vertex 114 ₋₁ . That is, since the three points 115 _-1 in the point group 103 are closer to the first mesh vertex 114 _-1 than the distance to the second mesh vertex 114 _-2 , the first point associated with the mesh vertices 114 _-1.

Further, three points 115 _-2 in the point group 103 are associated with the second mesh vertex 114 _-2 . That is, the three points 115 _-2 of the point group 103 are set to the second mesh vertex 114 ₋ rather than the distance to the first mesh vertex 114 ₋₂ and the distance to the third mesh vertex 114 _{−3. Since} the distance from ₁ is closer, it is associated with the second mesh vertex 114 _-2 . In the same manner, the points 115 _-3 115 _-10 point group 103 is associated also to each of the mesh vertices 114 _-3 to 114 _-10.

The group-specific displacement vector calculation unit 22B has, for each of the groups 113 _{-1 to} 113 _-4 generated by the mesh vertex grouping unit 21B, a partial point group associated with one or more mesh vertices included in the group, Then, alignment with the post-springback shape represented by the measurement data input by the post-springback shape input unit 12 is performed, and a displacement vector from one or more mesh vertices to the corresponding point of the post-springback shape is obtained.

FIG. 8 is a diagram for explaining the processing contents of the group-specific displacement vector calculation unit 22B. Figure 8 is a for the first group 113 _-1 showing a process of calculating the displacement vector. FIG. 8A shows a partial point group associated with the four mesh vertices 114 _{-1 to} 114 _-4 included in the first group 113 _-1 . That is, the four mesh vertices 114 _-1 to 114 _-4 are point sequence 115 _-1 to 115 _-4, respectively point group 103 is associated with the correlated portion 22A. These point sequences 115 _{-1 to} 115 _-4 become a partial point group included in the first group 113 _-1 .

8 (b) is a partial point group included in the first group 113 in _-1, the positioning of the spring-back after the shape 104 as represented by the measured data inputted by spring back after the shape input unit 12 The state that has been performed is shown. Figure 4 entire die shape 101 shown in (a) and instead of being aligned with the overall springback after shape 104, partially aligned taken out only the first group 113 _-1 Therefore, it is possible to perform alignment with high accuracy.

This alignment is performed by calculating the nearest point in the post-springback shape 104 that is closest to the four mesh vertices 114 _{-1 to} 114 _-4 included in the first group 113 _-1 . As a method of calculating the nearest point, for example, a known ICP (Iterative Closest Point) method can be applied.

FIG. 8C shows a displacement vector from points corresponding to the four mesh vertices 114 _{-1 to} 114 _-4 to the corresponding points of the post-springback shape 104 in the partial point group of the first group 113 _-1. Is shown. The corresponding points of the post-springback shape 104 correspond to the four mesh vertices 114 _{-1 to} 114 _-4 in the partial point group aligned with the post-springback shape 104 as shown in FIG. 8B. The point to do.

As a result of the above processing, how the four mesh vertices 114 _{-1 to} 114 _-4 in the mold shape included in the first group 113 _-1 are displaced with respect to the post-springback shape 104 is determined. Four represented displacement vectors are obtained. By performing the same processing for the other groups 113 _-2 to 113 _-4, a displacement vector is determined by four from each of the group 113 _-2 to 113 within _-4.

  In the present embodiment, mesh vertices are grouped by setting an overlapping area between adjacent ones. Therefore, a plurality of displacement vectors are obtained for mesh vertices belonging to both two overlapping groups. Therefore, a process of replacing a plurality of displacement vectors obtained for one mesh vertex with one displacement vector is performed.

FIG. 9 is a diagram for explaining processing contents for replacing a plurality of displacement vectors with one displacement vector. FIG. 9A shows the displacement vectors obtained for the mesh vertices 114 _{-1 to} 114 _-10 by arrows by the group-specific displacement vector calculation unit 22B. Among these, two displacement vectors are obtained for each of the six mesh vertices 114 _{-3 to} 114 _-8 .

FIG. 9B shows the result of replacing two displacement vectors for six mesh vertices 114 _{-3 to} 114 _-8 with one displacement vector. For example, by averaging two displacement vectors, it is possible to replace with one average displacement vector.

  The mesh deformation unit 23 deforms the pre-deformation mesh 102 generated by the mesh generation unit 13 using the displacement vector obtained by the displacement vector calculation unit 22. For example, the deformation process is performed by replacing the displacement vector sequence obtained by the displacement vector calculation unit 22 with a deformation map using a function called RBF (Radial Basis Function) and deforming based on the deformation map. This can be performed by a process of spatially deforming each vertex of the front mesh 102.

  FIG. 10 is a diagram for explaining the processing content of the mesh deformation unit 23. FIG. 10A shows the pre-deformation mesh 102 generated by the mesh generation unit 13 and the displacement vector (indicated by an arrow) obtained by the displacement vector calculation unit 22. FIG. 10B shows a mesh 105 obtained as a result of deforming the pre-deformation mesh 102 by the RBF deformation map using the displacement vector obtained by the displacement vector calculation unit 22.

<Configuration of Line Length Holding Deformation Section 16: FIG. 3>
Next, the functional configuration of the line length holding / deforming unit 16 will be described in detail. As shown in FIG. 3, the line length holding and deforming unit 16 according to the present embodiment includes a rotation calculating unit 31, a protruding vector calculating unit 32, a vertex coordinate value calculating unit 33, and a positioning unit 34 as functional configurations. . The rotation calculation unit 31 includes a deformed mesh projection unit 31A, a face rotation calculation unit 31B, and a vertex rotation calculation unit 31C.

  The rotation calculating unit 31 projects the mesh deformed by the mesh deforming unit 23 (hereinafter referred to as a deformed mesh) onto the post-springback shape represented by the measurement data input by the post-springback shape input unit 12, and The rotation at each vertex of the pre-deformation mesh is obtained based on the difference between the projected mesh (hereinafter referred to as the projection mesh) and the pre-deformation mesh.

  Specifically, the rotation calculation as described above is executed by the deformed mesh projection unit 31A, the face rotation calculation unit 31B, and the vertex rotation calculation unit 31C. The deformed mesh projection unit 31A projects the deformed mesh 105 on the post-springback shape 104 represented by the measurement data.

  FIG. 11 is a diagram for explaining the processing contents of the deformed mesh projection unit 31A. FIG. 11A shows a state in which the deformed mesh 105 is projected onto the post-springback shape 104 represented by the measurement data. The projection destination can be obtained, for example, by nearest point calculation. In addition, as shown in FIG.11 (b), the location from which the nearest point is calculated | required on the outer periphery of the shape 104 after a spring back is excluded. The mesh 106 shown in FIG. 11B is a projection mesh.

  The face rotation calculation unit 31B calculates the rotation of the face from the pre-deformation mesh 102 to the projection mesh 106 based on the difference between the face of the projection mesh 106 and the face of the pre-deformation mesh 102. The vertex rotation calculation unit 31C replaces the rotation of the face obtained by the face rotation calculation unit 21B with the rotation at each vertex of the pre-deformation mesh 102.

  FIG. 12 is a diagram for explaining the processing contents of the face rotation calculation unit 31B and the vertex rotation calculation unit 31C. FIG. 12A shows the projection mesh 106 and the pre-deformation mesh 102 superimposed on each other. FIG. 12B shows a state in which the rotation of the face (indicated by an arrow) is obtained from the difference between the face of the projection mesh 106 and the face of the mesh 102 before deformation. The rotation of the face can be obtained, for example, by calculating a vector connecting the vertices of the mesh as an edge vector and solving the covariance matrix of the edge sequence before and after the mesh deformation. This calculation method is an example, and the present invention is not limited to this.

  FIG. 12C shows a state in which the rotation of the face shown in FIG. 12B is replaced with the rotation of each vertex (indicated by an arrow). The amount of rotation at each vertex is obtained by complementing the rotation of the face by a known exponential mapping method. That is, when one face rotates, the vertexes of the mesh constituting the face also rotate. However, the rotation of one vertex is affected by the rotation of a plurality of faces in contact with the vertex. Therefore, when calculating the rotation of one vertex, it is necessary to consider all the rotations of a plurality of faces in contact with the vertex. For example, an average of rotations of a plurality of faces in contact with one vertex is obtained as the rotation of the vertex.

  The protrusion vector calculation unit 32 obtains a protrusion vector representing the protrusion amount from the center of gravity of the peripheral vertex for each vertex of the pre-deformation mesh 102 generated by the mesh generation unit 13. FIG. 13 is a diagram for explaining the processing content of the protruding vector calculation unit 32. FIG. 13 shows an example of calculating the protrusion vector when attention is paid to one vertex 115 among the vertices of the pre-deformation mesh 102.

In the example of FIG. 13, there are six peripheral vertices 116 _{−1 to} 116 _-6 around the target vertex 115. That is, the six faces of the pre-deformation mesh 102 are in contact with the target vertex 115. The protrusion vector calculation unit 32 calculates the center of gravity 117 of these six peripheral vertices 116 _{-1 to} 116 _-6 , and obtains the protrusion amount with respect to the target vertex 115 from the center of gravity 117 as the protrusion vector 118. The protrusion vector 118 obtained by the protrusion vector calculation unit 32 is a vector representing the protrusion amount with respect to the peripheral vertices 116 _{-1 to} 116 _-6 of the target vertex 115 of the pre-deformation mesh 102.

  The vertex coordinate value calculation unit 33 obtains the protrusion vector obtained by applying the rotation obtained by the vertex rotation calculation unit 31C to the protrusion vector of each vertex of the pre-deformation mesh 102 and the protrusion vector of each vertex of the pre-deformation mesh 102. From the relationship with the vector, the coordinate value of the mesh vertex of the post-springback shape whose line length is maintained is calculated.

In other words, the vertex coordinate value calculation unit 33 holds the line length to be obtained, where D is a protruding vector sequence obtained by applying the rotation obtained by the vertex rotation calculating unit 31C to the protruding vector of each vertex of the pre-deformation mesh 102. The coordinates of the mesh vertices of the post-springback shape retained in line length are obtained by solving the determinant LX = D, where X is the coordinate value matrix of the mesh vertices of the post-springback shape and L is the projection vector calculation operator. A value matrix X is obtained. Note that the protruding vector calculation operator L is specifically a matrix, and its coefficient sequence is represented by the following expression.
L _ii = 1
L _ij = −1 / n (when vertex j is an adjacent vertex of vertex i)
= 0 (other than above)

  The left side of the determinant of LX = D represents a protruding vector sequence at each vertex of the post-springback shape to be obtained. On the other hand, the right side of the determinant represents a protruding vector string of each vertex of the post-deformation mesh obtained when the pre-deformation mesh 102 is deformed by rotation of each vertex. This right side is based on the feature of the protruding vector that “the protruding vector when a certain vertex and its adjacent vertex are rotated is equal to the rotated protruding vector before the rotation”.

  Although it is ideal to obtain a matrix X in which the left side and the right side of the determinant completely match, there is no guarantee that the matrix will completely match. Therefore, in the present embodiment, the matrix X is obtained such that the value on the left side is closest to the value on the right side by solving the determinant based on the least square method.

The protruding vector sequence D on the right side is calculated by the following (Equation 1). Here, e _ij is an edge vector connecting the vertex i of the pre-deformation mesh 102 and the vertex j adjacent thereto. ΔR _ij is a differential rotation between the rotation R _i at the vertex _i and the rotation R _{j at the} vertex j. The item of e _ij R _{i on} the right side of (Expression 1) represents the rotation of the vertex i when the edge vector e _ij is not bent in the positional relationship between the vertex i and the peripheral vertices j and k. . The item e _ij ΔR _ij R _i represents the rotation of the vertex i when the edge vector e _ij is bent in the positional relationship between the vertex i and the peripheral vertices j and k.

  FIG. 14 is a diagram for explaining the presence or absence of occurrence of bending to be considered when calculating the protruding vector sequence D. FIG. 14A shows a state in which no bending occurs before and after deformation from the pre-deformation mesh 102 to the projection mesh 106 in the positional relationship between the vertex i and the peripheral vertices j and k. That is, when no bending occurs in the positional relationship between the vertex i and the peripheral vertices j and k, the protrusion vector 118 representing the protrusion amount from the centroid 117 of the peripheral vertices j and k to the vertex i is the protrusion vector. The direction and the size from the center of gravity 117 are not changed only by 118 itself rotating.

  On the other hand, FIG. 14B shows a state in which bending occurs before and after the deformation from the pre-deformation mesh 102 to the projection mesh 106 in the positional relationship between the vertex i and the peripheral vertices j and k. . That is, when bending occurs in the positional relationship between the vertex i and the peripheral vertices j and k, the protrusion vector 118 representing the protrusion amount from the centroid 117 of the peripheral vertices j and k to the vertex i is calculated from the centroid 117. Direction and size change before and after mesh deformation.

When the deformation from the pre-deformation mesh 102 to the projection mesh 106 is performed, there is a possibility that both the above-described bending occurs and the bending does not occur. Therefore, in the present embodiment, as shown in (Equation 1), the rotation of one vertex (e _ij R _i ) and the bending in the case where no bending occurs in the positional relationship between the one vertex and the surrounding vertices, The protruding vector sequence D is calculated by averaging the rotation of one vertex (e _ij ΔR _ij R _i ) with respect to the case where the above occurs.

  The alignment unit 34 uses the coordinate values of the mesh vertices obtained by the vertex coordinate value calculation unit 33 (coordinate values of the mesh vertices of the post-springback shape indicated by the vertex coordinate value matrix X) as coordinate values in the absolute coordinate system. Align. That is, the coordinate value sequence obtained by the line length holding / deforming unit 16 through the protruding vector space shown in (Expression 1) loses position information on the absolute coordinate system. Therefore, alignment is performed by moving so that the center of gravity position after the conversion is matched with the position of the center of gravity before conversion by the line length holding deformation unit 16. In addition, when the fixed location is instructed in advance, the alignment may be performed so that the fixed location matches.

As described above in detail, in the present embodiment, the mold shape data representing the target shape of the molded product and the measurement data representing the post-spring shape of the molded product are input, and the mold shape data is A mold-shaped mesh 102 and a point group 103 are generated. Then, using the mesh 102 and the point group 103 generated, the mold shape 101 and the post-springback shape 104 are aligned for each of the predetermined divided groups 113 _{-1 to} 113 _-4. A displacement vector representing the deformation to the post-springback shape 104 is obtained. Further, the rotation of the mesh before and after the deformation is obtained by using the generated mesh 102 of the mold shape and the mesh 105 obtained by deforming the mesh 102 with the deformation vector, and the post-spring-back shape having a line length maintained from the obtained rotation. The coordinate values of the mesh vertices are calculated.

According to this embodiment configured as described above, alignment is performed between the mold shape data representing the target shape of the molded product and the measurement data representing the post-spring back shape of the molded product, thereby Correspondence between both data is required. Therefore, even when the phase correspondence between the mold shape data and the measurement data of the shape after the spring back is not taken, the constituent points of the target shape of the molded product (vertices 114 _{-1 to} 114 of the mesh 102 before deformation) ₋₁₀ ), the coordinate value of the corresponding point of the post-springback shape (the vertex of the deformed mesh 105) can be calculated.

  Further, in the present embodiment, such alignment is performed using the mesh 102 and the point group 103 that do not depend on a specific direction. Even in the case where a three-dimensional twist occurs in the direction, the constituent points of the shape after the springback can be calculated.

Moreover, in this embodiment, since the alignment of the mold shape 101 and the post-springback shape 104 is performed for each of the groups 113 _{-1 to} 113 _-4 , the alignment that hardly causes a change in line length is performed. Can do. Furthermore, in this embodiment, in a rotation space (projection vector space) that does not have an element of how long the mesh vertex has rotated, a change in line length that can be caused by partial alignment is corrected. The coordinate values of the mesh vertices with minimal changes can be obtained. Thereby, the composing point of the post-springback shape can be calculated with high accuracy.

  Further, in the present embodiment, since the constituent points (coordinate value sequence of mesh vertices) of the post-springback shape whose line length is maintained are calculated at once by the determinant shown in (Expression 1), Compared with Patent Document 1 in which meshes are sequentially calculated one by one, there is also an advantage that the constituent points of the shape after springback can be obtained in a short time.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be interpreted in a limited manner. That is, the present invention can be implemented in various forms without departing from the gist or the main features thereof.

DESCRIPTION OF SYMBOLS 11 Mold shape input part 12 Post-springback shape input part 13 Mesh production | generation part 14 Point cloud production | generation part 15 Partial alignment part 16 Line length maintenance deformation | transformation part 17 Prospect mold shape generation part 21 Grouping part 21A Feature point extraction part 21B Mesh Vertex grouping unit 22 Displacement vector calculation unit 22A Association unit 22B Displacement vector calculation unit by group 23 Mesh deformation unit 31 Rotation calculation unit 31A Deformed mesh projection unit 31B Face rotation calculation unit 31C Vertex rotation calculation unit 32 Protrusion vector calculation unit 33 Vertex Coordinate value calculation unit 34 Positioning unit

Claims (7)

A mold shape input unit for inputting mold shape data representing a target shape of a molded product;
A post-spring back shape input section for inputting measurement data representing the post-spring back shape of the molded product;
A mesh generation unit that generates a mesh of the mold shape from the mold shape data input by the mold shape input unit;
A point cloud generation unit that generates a point cloud of the mold shape from the mold shape data input by the mold shape input unit;
Represented by the mold generated by the mesh generation unit and the mold shape expressed using the point cloud generated by the point group generation unit, and the measurement data input by the post-springback shape input unit A partial alignment unit that performs alignment with the post-springback shape for each predetermined divided region, and obtains a displacement vector representing the deformation from the mold shape to the post-springback shape;
Using the mesh generated by the mesh generation unit and the mesh obtained by deforming the mesh with the deformation vector, the rotation of the mesh before and after the deformation is obtained, and the mesh vertex of the post-springback shape whose line length is retained from the obtained rotation. And a line length holding / deforming unit for calculating the coordinate value of the post-spring-back shaped component point calculating device. The partial alignment part is
A grouping unit that groups the mold shapes represented by the mesh generated by the mesh generation unit for each region of a predetermined size;
For each group generated by the grouping unit, a mold shape represented by the point group generated by the point group generation unit and a spring represented by the measurement data input by the post-springback shape input unit A displacement vector calculation unit that performs alignment with the post-back shape, and obtains a displacement vector from a point corresponding to each vertex of the mesh in the point group to a corresponding point of the post-spring back shape;
A mesh deforming unit that deforms the mesh generated by the mesh generating unit using the displacement vector obtained by the displacement vector calculating unit; and
A deformed mesh that is a mesh deformed by the mesh deforming unit is projected onto a post-springback shape represented by the measurement data input by the post-springback shape input unit, and a projected mesh that is the projected mesh Based on the difference from the pre-deformation mesh that is the mesh generated by the mesh generation unit, a rotation calculation unit that calculates the rotation at each vertex of the pre-deformation mesh,
For each vertex of the pre-deformation mesh, a protrusion vector calculation unit that calculates a protrusion vector that represents the protrusion amount from the center of gravity of the peripheral vertices;
From the relationship between the protrusion vector of each vertex of the pre-deformation mesh and the protrusion vector obtained by applying the rotation obtained by the rotation calculation unit to the protrusion vector of each vertex of the pre-deformation mesh, the line length A vertex coordinate value calculation unit for obtaining the coordinate value of the mesh vertex of the retained post-springback shape;
The post-springback shape according to claim 1, further comprising: an alignment unit that aligns the coordinate value of the mesh vertex obtained by the vertex coordinate value calculation unit with the coordinate value of the absolute coordinate system. Composition point calculation device.   Using the mold-shaped mesh generated by the mesh generation unit and the post-springback-shaped mesh calculated by the line length retaining deformation unit, the reverse rotation of the mesh before and after deformation is obtained and obtained. Based on the reverse rotation, by deforming the target shape of the molded product input as the mold shape data by the mold shape input unit, the coordinate value of the mesh vertex of the prospective mold shape held in line length is obtained. The constituent point calculation device for the post-springback shape according to claim 2, further comprising a prospective mold shape generation unit for calculation. The grouping part
A feature point extraction unit that extracts a point sequence of a high curvature portion from a plurality of points of the point group generated by the point group generation unit, and extracts representative points as feature points from the point sequence of the plurality of points;
Mesh vertices that group the vertices of the pre-deformation mesh generated by the mesh generation unit for each vertex included in a region indicated by a sphere having a predetermined radius with the feature point extracted by the feature point extraction unit as the center With a grouping department,
The displacement vector calculator is
Based on the distance between each vertex of the pre-deformation mesh generated by the mesh generation unit and each point of the point cloud generated by the point cloud generation unit, each point of the point cloud is the shortest mesh vertex An associating unit that associates with
For each group generated by the mesh vertex grouping unit, a group of partial points associated with one or more mesh vertices included in the group, and the measurement data input by the post-springback shape input unit A displacement vector calculation unit for each group that performs alignment with the post-springback shape represented and obtains a displacement vector from the one or more mesh vertices to the corresponding point of the post-springback shape. The constituent point calculation device for the post-springback shape according to claim 2. The rotation calculation unit
A deformed mesh projection unit that projects the deformed mesh onto a post-springback shape represented by the measurement data;
A face rotation calculation unit that calculates the rotation of the face from the pre-deformation mesh to the projection mesh based on the difference between the face of the projection mesh that is a mesh projected by the deformation mesh projection unit and the face of the pre-deformation mesh When,
The post-springback shape according to claim 2, further comprising: a vertex rotation calculation unit that replaces the rotation of the face obtained by the face rotation calculation unit with a rotation at each vertex of the mesh before deformation. Composition point calculation device.   The protrusion vector of each vertex obtained by the vertex coordinate value calculation unit is the rotation of the one vertex with respect to the case where no bending occurs in the positional relationship between the one vertex and the surrounding vertices, and the bending occurs. The constituent point calculation device for the post-springback shape according to claim 2, characterized in that it is obtained by averaging the rotation of the one vertex with respect to the case. Mold shape input means for inputting mold shape data representing the target shape of a molded product,
Post-springback shape input means for inputting measurement data representing the post-springback shape of the molded product,
Mesh generating means for generating a mesh of the mold shape from the mold shape data input by the mold shape input means;
Point cloud generation means for generating a point cloud of the mold shape from the mold shape data input by the mold shape input means;
Represented by the shape of the mold generated by the mesh generated by the mesh generating means and the point group generated by the point cloud generating means, and the measurement data input by the post-springback shape input means. Positioning with the post-springback shape is performed for each predetermined divided region, and a partial positioning means for obtaining a displacement vector representing a deformation from the mold shape to the post-springback shape is generated by the mesh generation unit. Using the mesh and the mesh deformed with the above deformation vector, the rotation of the mesh before and after the deformation is obtained, and the line length for calculating the coordinate value of the mesh vertex of the post-springback shape that is retained in the line length from the obtained rotation Calculation of the constituent points of the post-springback shape to allow the computer to function as a holding deformation means Program.