JP5318650B2 - Work model creation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly reproduce a physical phenomenon, even when simulating the verification of process precision of a product or the physical phenomenon of distortion or the like due to solidification and thermal contraction or the like, in a group of points remaining after thinning out. <P>SOLUTION: A product model formed by a group of points and a model of an ideal work formed by planes are compared on a three-dimensional virtual space of a computer. A difference from a reference of a measured point is obtained, for each measured point, on the basis of a point that is on the model of an ideal work and corresponds to the measured point. The lines of equal difference with differences, which are virtual lines of equal difference to connect points with equal difference and which have differences being different only by an arbitrary width from the differences of adjacent lines of equal difference, are assumed. A group of points, which are on the line and in which adjacent distances are point-selection distances, is selected for each assumed line of equal difference. A group of points including the product is replaced by the group of points selected at a point selection step, and a work model, in which the group of points is replaced, is stored in a storage medium. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a work model creation method for creating a work model by thinning out a point group constituting a model formed by a work surface in a three-dimensional virtual space of a computer.

  Recently, when it is necessary to manufacture a plurality of the same products, for example, a machining method (NC machining method) by numerical control (NC) is used.

  In the NC machining method, first, a three-dimensional model of a product (a three-dimensional model in a three-dimensional virtual space of a computer) is created, and based on this three-dimensional model, the operation of the cutting edge of a cutting tool is defined by coordinates. This is done by creating a program, installing the created NC program in the NC device, and operating the NC program. That is, in the NC device, a tool or a workpiece operates and machining is performed by driving a servo motor built in the NC device based on the NC program.

  For creating a 3D model of a product, based on the position of a point cloud measured with a non-contact or contact-type displacement sensor, the 3D model is composed of many planes in a computer 3D virtual space. A model is created, or a product is imaged with a camera, and a 3D model composed of a number of surfaces is created based on the captured image (2D image). As the latter method, a three-dimensional model is created by a three-dimensional modeling method based on a two-dimensional image (see, for example, Patent Documents 1 and 2). Further, as a method for restoring the original shape from the position information of the point group in the three-dimensional virtual space of the computer, there is a method according to Patent Document 3.

Japanese Patent No. 3739209 Japanese Patent No. 3805120 JP 2004-30226 A

  By the way, since such a three-dimensional model has a large number of points constituting a point cloud (900,000 or more), an NC program is created from the three-dimensional model by a CAM (Computer Aided Manufacturing) system or the like. In some cases, the computer may be overloaded, and a long calculation time may be required. Also, when CAE (Computer Aided Engineering) system or the like is used to verify processing accuracy, or to simulate distortion such as solidification and heat shrinkage, it may cause excessive load on the computer and may take a long calculation time. . Of course, in Patent Documents 1 to 3 described above, when creating a three-dimensional model based on a two-dimensional image or restoring the original shape from the position information of a point group in a three-dimensional virtual space, An excessive load may be applied, and a long calculation time may be required.

  Therefore, it is required to reduce the amount of information in the 3D model created in the computer's 3D virtual space by thinning out a large number of point clouds. However, when verifying the processing accuracy of products and simulating physical phenomena such as distortion such as solidification and heat shrinkage, there is a possibility that problems may occur that physical phenomena are not reproduced correctly if the points are sparse. is there.

  The present invention has been made in consideration of such a problem, and in the remaining point group after thinning, the points are not distributed sparsely and the density of the points is made almost constant. The work model that can reproduce the physical phenomenon correctly even if the remaining point cloud simulates the physical phenomenon such as distortion of the product processing accuracy verification and solidification / heat shrinkage etc. The purpose is to provide a creation method.

  The work model creation method according to the first aspect of the present invention is an actual measurement of a product that is actually manufactured, and a model formed by a point group constituting the actually measured product and a product formed by a surface. The ideal workpiece model is compared with the computer in a three-dimensional virtual space, and for each of the actually measured points, a point on the ideal workpiece model and corresponding to the actually measured point is used as a reference. Further, a difference calculating step for obtaining a difference from the reference of the actual measured point, and a virtual equidistant line connecting the same difference points, and an arbitrary width from a difference between adjacent equidistant lines An equality line assumption step that assumes an equality line of different differences, and a point selection step that selects a point group that is on the line and whose adjacent distance is a point selection distance for each assumed equality difference line; , The point group constituting the product, the point selection A step replacement point group replaced by a group of points selected in step, and having a workpiece model storage step of storing a workpiece model point group is replaced by step replaced the point group in the storage medium.

  As a result, in the remaining point cloud after thinning, the point density is not sparsely distributed, and the density of the points can be made substantially constant. The physical phenomenon can be correctly reproduced even by simulating a physical phenomenon such as distortion such as solidification and heat shrinkage, and verification of machining accuracy.

  Next, a work model creation method according to a second aspect of the present invention is a product model obtained by actually measuring a product that is actually manufactured and configured by a point group in a three-dimensional virtual space of a computer. A work model creation method for creating a work model by thinning out a point cloud, wherein a reference position setting step for setting a reference position in the three-dimensional virtual space, and a center of gravity position is set to the reference position in the set reference position A reference cube placement step for placing a reference cube that coincides with the reference cube, and a plurality of cubes having the same size as the reference cube, with the reference cube as a starting point, and line segments of each cube aligned in a straight line Are arranged in a three-dimensional manner, and are performed for each cube, and are a point group constituting the three-dimensional model, and among the point groups existing in the cube, A point group selecting step for selecting a point closest to the position, a point group deleting step for deleting a point group other than the selected point group from the point group constituting the three-dimensional model, and the selected point group A first storage step of storing in a storage medium a first work model formed by a plurality of surfaces configured based on the above, and comparing the product model and the first work model in a three-dimensional virtual space of a computer Then, for each of the actually measured points, a difference from the reference of the actually measured point is obtained with reference to a point on the first work model and corresponding to the actually measured point. A difference calculating step and a virtual equality line connecting the same difference points, and an equality line assumption step that assumes an equality difference line that is different by an arbitrary width from the difference between adjacent equality lines; and The assumed equidistant line A point selection step for selecting a point group that is on the line and whose adjacent distance is a point selection distance, and a point group for replacing the point group constituting the product with the point group selected in the point selection step A replacement step; and a second storage step of storing in a storage medium the second work model in which the point group is replaced in the point group replacement step.

  That is, first, a reference cube is set on the three-dimensional virtual space of the computer, and then a number of cubes having the same size as the reference cube are arranged on the product model. It is possible to select the most useful points from the point groups that constitute the cubes and exist in each cube. Therefore, points that exist in the cube and are not selected can be deleted from the product model. Since the work model created based on the selected point cloud naturally has a smaller amount of information than the product model, an excessive load is placed on the computer when creating an NC program using a CAM system, for example. In addition, it can be reduced that the calculation time is long.

  In addition, since the process of arranging three-dimensionally with the reference cube as a starting point and the line segments of each cube arranged in a straight line can be relatively easily performed on a computer, the processing speed can be increased. .

  Further, the pitch of points after deleting unnecessary point groups in the point group deletion step is 5 to 10 times the pitch of points in the product model. In addition, since the points are selected based on the same condition position (here, the center of gravity position) of each cube, the selected point group is composed of points arranged at substantially the same pitch. That is, in the point group remaining after deleting unnecessary points, the points are not sparsely distributed locally, and the density of the points can be made substantially constant. As a result, a work model composed of planes can be created, and the reproducibility of the work model can be improved.

  Furthermore, in the second aspect of the present invention, a plurality of equidistant lines are assumed in a stepwise manner with respect to the work model composed of surfaces, and points on each equidistant line, and Since the point where the adjacent distance is the point selection distance is selected and the selected point cloud is replaced with the point cloud that constitutes the product model, the work model with the replaced point cloud is compared with the product model. Naturally, since the amount of information is small, for example, when creating NC programs with a CAM system, etc., or when verifying machining accuracy with a CAE (Computer Aided Engineering) system or simulating distortions such as solidification and heat shrinkage In addition, it is possible to reduce the fact that it takes a long calculation time without imposing an excessive load on the computer.

  Further, as described above, a plurality of point groups constituting the product model, each of which is based on a work model configured by selecting the most useful points from among the point groups existing in each cube. Since the equidistant lines are assumed step by step, the point group is not sparsely replaced on each surface, and the distance between adjacent points is set to a fixed distance (point selection distance). In the replaced point group, the points are not sparsely distributed locally, and the density of the points can be made substantially constant. As a result, it is possible to create a three-dimensional model composed of faces from the work model of the replaced point group, and to improve the reproducibility of the three-dimensional model.

  In addition, in the workpiece model with the replaced point cloud, since the point cloud arranged on each equidistant line has a certain density, machining accuracy verification and When simulating distortions such as solidification and heat shrinkage, it is possible to obtain highly accurate results (more realistic results) with respect to actual mold thermal expansion and product thermal shrinkage.

  In the first and second aspects of the present invention, the difference in the equidistant line assumption step is a distance corresponding to ½ of the longest distance between two points in the point group constituting the product, and so on. The width between a plurality of virtual equi-difference lines assumed in the difference line assumption step is a distance corresponding to 1 / n (n = 2, 3, 4,...) Of the difference. The point selection distance in the selection step is preferably a distance corresponding to the shortest distance between two points in the point group constituting the product model.

  In the above-mentioned second aspect of the present invention, the reference position setting step may be performed by setting the reference cube at a position that is the origin of each three-dimensional coordinate of the point group constituting the product model, A large number of cubes can be easily arranged.

  As described above, according to the work model creation method according to the present invention, in the remaining point group after thinning, the points are not sparsely distributed locally, and the density of the points is substantially constant. Even if the remaining point cloud is used to verify the processing accuracy of the product and simulate a physical phenomenon such as distortion such as solidification and heat shrinkage, the physical phenomenon can be correctly reproduced.

It is a block diagram which shows an example of the computer system which implement | achieves the work model creation method which concerns on this Embodiment. It is a block diagram which shows the structure of the computer in a computer system. It is a functional block diagram which shows the structure of a 1st work model processing means. It is a flowchart which shows the processing operation in a 1st work model processing means. It is explanatory drawing which shows the state which set the reference position on the three-dimensional virtual space of a computer, and has arrange | positioned the reference | standard cube in which a gravity center position corresponds to a reference position to the set reference position. It is explanatory drawing which shows the state arrange | positioned in three dimensions so that the reference | standard cube may be made into a starting point and the line segment of each cube may be located in a straight line. FIG. 7A is a diagram conceptually showing a process of extracting a point group existing in each cube from among the point groups constituting the product model, and FIG. 7B is for deleting point groups other than the selected point group. It is a figure which shows a process notionally. It is a functional block diagram which shows the structure of a 2nd work model processing means. It is a flowchart (the 1) which shows the processing operation in a 2nd work model processing means. It is a flowchart (the 2) which shows the processing operation in a 2nd work model processing means. It is a conceptual diagram which shows the principle which calculates | requires the difference of the target point and the reference point on the searched surface. A hypothetical equidistant line outside the surface, assuming the equidistant line going away from the surface and approaching the surface, and a virtual equidistant line inside the surface, going away from the surface and approaching the surface, etc. It is explanatory drawing which shows the assumption of a difference line.

  Hereinafter, an embodiment of a work model creation method according to the present invention will be described with reference to FIGS.

  The work model creation method according to the present embodiment is realized by a computer system 10 shown in FIG. As shown in FIG. 1, the computer system 10 is configured by connecting a computer 12 and a database DB storing various work models and the like via a network 14. An input device 16 such as a keyboard or a coordinate input device (such as a mouse) and a display device 18 are connected to the computer 12.

  As shown in FIG. 2, the computer 12 stores a main memory 20 used for operating various programs and transferring data, and image data for display created by the various programs. An input / output port 24 for exchanging data with an external device, and a CPU 26 for executing a program. The main memory 20, the image memory 22, the input / output port 24 and the CPU 26 are connected through a system bus 28.

  The input / output port 24 is connected to at least the input device 16, the display device 18, a hard disk drive (HDD) 32 that accesses the hard disk 30 based on a command from the CPU 26, and the network 14. Yes.

  The hard disk 30 stores an OS, application programs, and various data. In addition to existing document creation programs, spreadsheet programs, and CAD programs, application programs include a work model creation program that implements the work model creation method according to the present embodiment.

  The work model creation program creates a work model composed of a first work model composed of planes and a point group by thinning out the point cloud composing the three-dimensional model in the computer three-dimensional virtual space. It is a program for functioning as a work model creation means.

  Here, the work model creation means according to the present embodiment will be described.

  First, as shown in FIG. 1, the database DB stores information on product models that are actually measured products and formed by point groups that constitute the actually measured products. Specifically, a point group information table 40 in which the three-dimensional coordinates of each point group constituting the product model are registered is stored.

  The work model creation means according to the present embodiment includes first work model processing means 42A shown in FIG. 3 and second work model processing means 42B shown in FIG. The first work model processing means 42A creates a model of an ideal work formed on the surface based on the product model, and the second work model processing means 42B converts the product model and the model of the ideal work formed on the surface. Based on this, a process of efficiently thinning out the point group constituting the product model and replacing it with a product model composed of a point group having a substantially constant point density is performed.

  That is, as shown in FIG. 3, the first work model processing means 42A reads the point cloud information table 40 from the database DB and records it on the hard disk 30 (see FIG. 2), for example, and a computer. Reference position setting means 48 for setting a reference position on 12 three-dimensional virtual spaces (xyz orthogonal coordinates), and a reference cube whose center of gravity coincides with the reference position 50 at the set reference position 50 (see FIG. 5). 52 (reference cube: refer to FIG. 5), a plurality of cubes 52 (see FIG. 6) having the same size as the reference cube 52, the reference cube 52 as a starting point, and each Cube arrangement means 56 arranged three-dimensionally so that the line segments of the cube 52 are arranged in a straight line, and a point group constituting the product model 44 for each cube 52, and Other than the point group selected from the point group selecting means 58 for selecting the closest point from the center of gravity position of the cube 52 and the point group constituting the product model 44 among the point groups existing in the cube 52 Point group deleting means 60 for deleting the point group, first work model creating means 62 for creating a first work model formed of a plurality of surfaces based on the selected point group, and the first work model in the database First work model storage means 64 for storing in the DB.

  The point group selection means 58 is based on the three-dimensional coordinates registered in the point group information table 40 (see FIG. 3) and the three-dimensional coordinates of the vertices of the cube 52 to be selected for the point group. Among the point groups constituting the product model 44, point group extracting means 66 for extracting point groups existing in the cube 52, three-dimensional coordinates of the extracted point groups and the three-dimensional position of the center of gravity of the cube 52 Based on the coordinates, each of the first point selecting means 68 for selecting the closest point from the center of gravity position of the cube 52 and a plurality of points (selected point group) selected by the first point selecting means 68 And table registration means 72 for registering the three-dimensional coordinates in the selected point cloud information table 70.

  Next, a work model creation method according to the present embodiment, particularly a method for creating a first work model formed by a plurality of surfaces (processing by the first work model processing means 42A) will be described with reference to FIGS. The explanation will be made with reference to FIG.

  First, in step S <b> 1 of FIG. 4, the first table reading unit 46 reads the point cloud information table 40 from the database DB and records it on the hard disk 30.

  Thereafter, in step S2 of FIG. 4, the reference position setting means 48 sets the reference position 50 on the three-dimensional virtual space of the computer 12, as shown in FIG. The reference position 50 can be set to an arbitrary position, but in this embodiment, the origin of the three-dimensional coordinates for each point of the point group constituting the product model 44 is used so that the calculation is simple. The reference position 50 is set as the position.

  Thereafter, in step S3 of FIG. 4, the reference cube arrangement means 54 arranges a reference cube 52 (reference cube) whose center of gravity coincides with the reference position 50 at the set reference position 50, as shown in FIG. Then, the three-dimensional coordinates of each vertex of the arranged reference cube 52 and the three-dimensional coordinates of the center of gravity are registered in the reference cube information table 74 (see FIG. 3).

  Thereafter, in step S4 of FIG. 4, the cube arranging means 56, as shown in FIG. 6, uses a plurality of cubes 52 having the same size as the reference cube 52 as a starting point, and each cube 52 Line up three-dimensionally so that the line segments are aligned on a straight line. Then, the three-dimensional coordinates of the vertices of the plurality of cubes 52 arranged three-dimensionally and the three-dimensional coordinates of the positions of the center of gravity are registered in the cube information table 76 (see FIG. 3). The number of arranged cubes 52 is stored in a register.

  Thereafter, the processing in the point group selection means 58 is started. That is, in step S5 of FIG. 4, the point group selection unit 58 stores the initial value “1” in the search index i of the cube 52.

  Thereafter, in step S6 of FIG. 4, the point group selection means 58 reads the three-dimensional coordinates of the centroid position of the i-th cube 52 and the three-dimensional coordinates of each vertex from the i-th record of the cube information table 76.

  Thereafter, in step S7 of FIG. 4, the point group extraction unit 66 is based on the three-dimensional coordinates registered in the point group information table 40 on the hard disk 30 and the three-dimensional coordinates of the vertices of the i-th cube 52. Thus, the point group existing in the i-th cube 52 is extracted from the point group constituting the product model 44. For example, as shown in FIG. 7A, when three cubes (first cube 52a to third cube 52c) are considered, three points Ta1 to Ta3 are extracted in the first cube 52a, and three points in the second cube 52b. Tb1 to Tb3 are extracted, and in the third cube 52c, three points Tc1 to Tc3 are extracted.

  Thereafter, in step S8 of FIG. 4, the first point selection unit 68 determines the i-th cube 52 based on the three-dimensional coordinates of the extracted point group and the three-dimensional coordinates of the centroid position of the i-th cube 52. Select the closest point from the center of gravity. For example, referring to the example of FIG. 7A, in the first cube 52a, one of the extracted points Ta1 to Ta3, the one point Ta1 closest to the center of gravity of the first cube 52a is selected, and the second cube 52b is selected. Then, out of the three extracted points Tb1 to Tb3, one point Tb2 closest to the center of gravity of the second cube 52b is selected, and among the three extracted points Tc1 to Tc3, the third cube 52c is selected. One point Tc3 closest to the center of gravity of the third cube 52c is selected. When there are two or more points closest to the center of gravity of the cube 52 among the point groups existing in the cube 52, one point is selected in consideration of reduction of the point group. It is preferable. As a method for selecting one point, a random number may be used, or a point selected first may be used.

  Thereafter, in step S <b> 9 of FIG. 4, the table registration unit 72 registers the three-dimensional coordinates of one point selected by the first point selection unit 68 in the selected point group information table 70.

  Thereafter, in step S10 of FIG. 4, the search index is updated by +1. Thereafter, in step S11, it is determined whether or not the point selection processing has been completed for all the cubes 52. This determination is made based on whether or not the value of the search index i is equal to or greater than the number of cubes 52 arranged (value stored in the register).

  If the point selection process has not been completed for all the cubes 52, the process returns to step S6 described above, and the processes after step S6 are repeated. Then, when the point selection processing is completed for all the cubes 52, the process proceeds to the next step S 12, and the point group deletion means 60 registers in the selected point group information table 70 among the point groups constituting the product model 44. A point group other than the point group corresponding to the plurality of three-dimensional coordinates is deleted. Specifically, among the three-dimensional coordinates of the point group registered in the point group information table 40 on the hard disk 30, other than the point group corresponding to the plurality of three-dimensional coordinates registered in the selected point group information table 70. Delete the 3D coordinates of the point cloud. Thus, for example, as shown in FIG. 7B, only one point Ta1 remains in the first cube 52a, only one point Tb2 remains in the second cube 52b, and one point Tc3 also in the third cube 52c. Only will remain.

  Thereafter, in step S13 of FIG. 4, the first work model creation unit 62 converts the point group corresponding to the plurality of three-dimensional coordinates registered in the point group information table 40 after being processed by the point group deletion unit 60. Based on this, a first work model formed of a plurality of surfaces is created. Specifically, processing is performed in which each three-dimensional coordinate of a plurality of vertices constituting the surface is obtained for each surface and registered in the corresponding record of the first work model information table 78 (see FIG. 3).

  Thereafter, in step S14 of FIG. 4, the first work model storage means 64 stores the created first work model (first work model information table 78) in the database DB.

  When the process in step S14 is completed, the work model creation method according to the present embodiment, particularly, the method of creating the first work model formed by a plurality of surfaces is finished.

  Thus, in the work model creation method according to the present embodiment, first, the reference cube 52 is set in the three-dimensional virtual space of the computer 12, and then the reference cube is set with respect to the product model 44. Since many cubes 52 having the same size as 52 are arranged, the most useful points are selected from the point groups constituting the product model 44 and existing in each cube 52. be able to. In the example of FIGS. 7A and 7B, a point closest to each gravity center position of the first cube 52a to the third cube 52c is selected from the first cube 52a to the third cube 52c, respectively. Therefore, points that exist in the cube 52 and are not selected can be deleted from the product model 44. The first work model created on the basis of the selected point cloud naturally has a smaller amount of information compared to the product model 44 (for example, the point cloud that was 900,000 points was reduced to 60,000 points). When an NC program is created by a CAM system or the like, it is possible to reduce an excessive load on the computer 12 and a long calculation time.

  In addition, since the process of arranging the cubes three-dimensionally so that the reference cubes 52 are the starting points and the line segments of the cubes 52 are arranged in a straight line can be relatively easily performed on the computer 12, the processing speed can be increased. be able to.

  7A, the point pitch Pa in the product model 44 is 0.1 to 1.0 mm. After the unnecessary point group is deleted by the point group deletion means 60, for example, FIG. As shown, the point pitch Pb is 5 to 10 times the pitch (0.5 to 10.0 mm) of the point pitch Pa in the product model 44. In addition, since the points are selected based on the same condition position (here, the center of gravity position) of each cube 52, the selected point group is composed of points arranged at substantially the same pitch Pb. That is, in the point group remaining after deleting unnecessary points, the points are not sparsely distributed locally, and the density of the points can be made substantially constant. As a result, the first work model creating means 62 can create a three-dimensional model (first work model) composed of faces, and can improve the reproducibility of the first work model.

  Next, the second work model processing means 42B will be described with reference to FIGS. In the second work model processing means 42B, the product model 44 (the point cloud information table 40 stored in the database DB) and the first work model created by the first work model processing means 42A (the first work model stored in the database DB). One work model information table 78) is used.

  That is, as shown in FIG. 8, the second work model processing means 42B reads the point cloud information table 40 and the first work model information table 78 from the database DB and records them on the hard disk 30, for example. 80, the above-described product model 44 and the first work model are compared in the three-dimensional virtual space of the computer 12, and each point actually measured is on the first work model and actually measured. The difference calculation means 82 for obtaining a difference from the reference of the actually measured point on the basis of the point corresponding to the point, and a virtual equal difference line connecting the same difference points, and a difference between adjacent equal difference lines An equality line assumption means 84 that assumes an equality difference line that is different by an arbitrary width from the above, and for each assumed equality difference line, a point group that is on the line and whose adjacent distance is a point selection distance The second point selection means 86 to be selected, the point group replacement means 88 for replacing the point group constituting the product model 44 with the point group selected by the second point selection means 86, and the point group replacement means 88 And a second work model storage unit 92 that stores the second work model (point replacement information table 90) in which is replaced in the database DB.

  Next, a work model creation method according to the present embodiment, in particular, a method of creating a second work model in which the point group constituting the product model 44 is replaced with the selected point group (second work model processing means 42B). Will be described with reference to FIGS.

  First, in step S101 of FIG. 9, the second table reading means 80 reads the point cloud information table 40 and the first work model information table 78 from the database DB and records them on the hard disk 30.

  Thereafter, the processing in the difference calculating means 82 is entered. That is, in step S102 of FIG. 9, the initial value “1” is stored in the point cloud search index j.

  Thereafter, in step S103, the information (three-dimensional coordinates) of the jth point is read from the point group information table 40 of the hard disk DB.

  After that, in step S104, based on the information on each surface registered in the first work model information table 78 (three-dimensional coordinates of vertices constituting the surface) and the information on the j-th point (three-dimensional coordinates), Among the surfaces constituting one work model, the surface corresponding to the jth point is searched.

  Thereafter, in step S105, the information on the surface searched in step S104 (three-dimensional coordinates of the vertices constituting the surface) is read out.

  Thereafter, in step S106, based on the surface information and the j-th point information, a point on the searched surface and corresponding to the j-th point is used as a reference point, and the j-th point Find the difference from the reference point. Specifically, as shown in FIG. 11, a normal line Lm is drawn with respect to the surface S from the j-th point Tj, and the intersection of the surface S and the normal line Lm becomes the reference point ta. Then, the length of the line segment between the jth point Tj on the normal line Lm and the reference point ta, that is, the difference is obtained. This difference can be easily calculated because the information on the surface S (three-dimensional coordinates of the vertices constituting the surface S) and the information on the j-th point Tj (three-dimensional coordinates) are known in advance. By the way, the positional relationship of the j-th point with respect to the surface may be the case where the j-th point Tj is located outside the surface S or the inside as shown in FIG. Therefore, when the j-th point Tj is located outside the surface S, “+” is added as a difference sign, and when the j-th point Tj is located inside the surface S, , “−” Is attached as a sign of the difference. Accordingly, by confirming the difference together with the sign, the positional relationship between the outer side and the inner side of the j-th point Tj with respect to the surface S can be understood, and the difference from the surface S can also be known.

  Thereafter, in step S107 in FIG. 9, the three-dimensional coordinates of the j-th point and the difference (signed) are stored in the j-th record (j-th record) of the difference information table 94 (see FIG. 8).

  Thereafter, in step S109 in FIG. 9, the value of the index j is updated by +1.

  Thereafter, in step S110, it is determined whether or not processing has been performed for all points registered in the point cloud information table 40. This determination is made based on whether the value of the index j is equal to or greater than the total number of point groups. If all the points have not been processed, the process returns to step S103 described above, and the processes after step S103 are repeated.

  And the process in the difference calculation means 82 is complete | finished when the process is complete | finished about all the points.

  Thereafter, the process proceeds to the next step S110, where the equality difference assumption unit 84 stores the initial value “0” in the index k for setting the equality difference line.

  Thereafter, in step S111, the equality line assumption means 84 assumes a virtual equality line outside the surface S and is assumed to be an equality line 100a away from the surface S as shown in FIG. Specifically, a virtual contour line 100a is assumed to be a difference D obtained by adding (information B of an arbitrary width × index k) to preset contour line information A. Here, the contour line information A is set to a distance corresponding to 1/2 of the longest distance between two points in the point group constituting the product model 44. In the present embodiment, since the longest distance between two points is set to 1.0 mm, for example, the contour line information A is 0.5 mm. The arbitrary width information B is a distance corresponding to 1 / n (n = 2, 3, 4,...) Of the contour line information A, and is 0.02 mm, for example. Therefore, when the value of index k is 0, a difference line from which the difference D from the surface corresponds to the contour line information A is assumed, and each time the value of index k is sequentially updated by +1, the difference is calculated. An equality line 100a in which D is added by only information B having an arbitrary width is assumed.

  Thereafter, in step S112 in FIG. 9, the second point selecting means 86 selects a point on the equidistant line 110a assumed in step S111 from the many points registered in the difference information table 94. Search is performed based on the difference information registered in 94, and the information (three-dimensional coordinates) of the corresponding point is stored in the work file 102 (see FIG. 8).

  Thereafter, in step S113, the second point selecting means 86 selects a point whose distance between adjacent points is a point selection distance among the points stored in the work file 102. Examples of the point selection distance include a distance corresponding to the shortest distance between two points in the point group constituting the product model 44, for example, 0.1 mm.

  Thereafter, in step S <b> 114, the point group replacing unit 88 registers the selected point information (three-dimensional coordinates) in the point replacement information table 90 in order.

  Thereafter, in step S115, the value of the index k is updated by +1.

  Thereafter, in step S116, it is determined whether or not the equidistant line processing in the direction outside the surface and away from the surface is completed. This determination is made based on whether the difference (A + B × j) is a specified value, for example, 0.6 mm or more. If the process has not ended, the process returns to step S111 described above, and the processes after step S111 are repeated. If the process has been completed, the process proceeds to the process after the next step S117, and this time, equidistant line processing is performed in the direction outside the surface and approaching the surface. That is, in step S117, the equal difference line assumption unit 84 stores “1” in the index k for setting the equal difference line.

  Thereafter, in step S118, the equality line assumption means 84 assumes a virtual equality line outside the surface S, as shown in FIG. Specifically, a virtual contour line 100b is assumed to be a difference D obtained by subtracting (information B of an arbitrary width × index k) from preset contour line information A. Accordingly, when the value of the index k is 1, a contour line corresponding to the difference D from the surface corresponding to (contour line information A−information B of an arbitrary width) is assumed. Every time +1 is updated, an equality line 100b in which the difference D is subtracted by the information B having an arbitrary width is assumed.

  The processing in step S119 to step S122 is the same as the processing in step S112 to step S115 described above, and for each assumed equality line 100b, a point located on that line is searched, and information on that point is obtained. In the points stored in the work file 102 and further in the points stored in the work file 102, a point group whose adjacent distance is the point selection distance is selected, and the information (three-dimensional coordinates) is sequentially stored in the point replacement information table 90. Registered in

  In step S123, it is determined whether or not the equidistant line processing in the direction outside the surface and approaching the surface is completed. This determination is made based on whether the difference (A−B × j) is 0 or less. If the process has not ended, the process returns to step S118 described above, and the processes after step S118 are repeated. If the process has been completed, the process proceeds to the process from step S124 onward in FIG. 10, and this time, an equality line 100c inward of the surface S and away from the surface S as shown in FIG. As described above, the same processing as described above is performed. That is, the processing in step S124 to step S130 is the same as the processing in step S110 to step S116 of FIG. 9 described above, and a point located on that line is searched for each assumed equality difference line 110c. The point information is stored in the work file 102. Further, at the points stored in the work file 102, a point group whose adjacent distance is the point selection distance is selected, and the information (three-dimensional coordinates) is replaced with a point. The information is registered in the information table 90 in order.

  After the processes in steps S124 to S130 are completed, the process proceeds to the processes in and after step S131 in FIG. 10, and this time, as shown in FIG. The same processing as described above is performed assuming the equal difference line 100d in the approaching direction. That is, the processing in step S131 to step S137 is the same as the processing in step S117 to step S123 of FIG. 9 described above, and a point located on that line is searched for each assumed difference line 100d. The point information is stored in the work file 102. Further, at the points stored in the work file 102, a point group whose adjacent distance is the point selection distance is selected, and the information (three-dimensional coordinates) is replaced with a point. The information is registered in the information table 90 in order.

  At the stage where the processing in step S131 to step S137 is completed, information (three-dimensional coordinates) of points that are each assumed on the equidistant line and whose adjacent distance is the point selection distance is registered. The second work model (point replacement information table 90) will be completed. Then, in step S138 of FIG. 10, the second work model storage unit 92 stores the point replacement information table 90 in the database DB as the second work model.

  At the stage where the processing in step S138 is completed, a work model creation method according to the present embodiment, in particular, a second work model in which the point group constituting the product model 44 is replaced with the selected point group is created. The method ends.

  As described above, in the work model creation method according to the present embodiment, the first work model configured by planes is used as a reference, and a plurality of equidistant lines are assumed in stages with respect to the first work model, Since the points on each equidistant line and the adjacent distance is a point selection distance are selected and the selected point group is replaced with the point group constituting the product model 44, the point is replaced. The second work model based on the point cloud naturally has a smaller amount of information than the product model 44. For example, when creating an NC program with a CAM system or the like, or with a CAE (Computer Aided Engineering) system or the like, the processing accuracy When verifying and simulating distortions such as solidification and heat shrinkage, it does not place excessive load on the computer and takes a long time. This can be reduced.

  Further, as described above, the first work model that is the point group that constitutes the product model 44 and that is configured by selecting the most useful points from the point groups that exist in each cube 52 is used as a reference. In addition, since a plurality of equidistant lines are assumed step by step, the point group is not sparsely replaced on each surface, and the distance between adjacent points is a fixed distance (point selection distance). Therefore, in the replaced point group, the points are not locally distributed sparsely, and the density of the points can be made almost constant. As a result, a three-dimensional model composed of surfaces can be created from the second work model composed of point clouds, and the reproducibility of the three-dimensional model can be improved.

  In the second work model, the point cloud arranged on each equivariance line has a certain density. Therefore, using the second work model, machining accuracy verification and distortion such as solidification and heat shrinkage are performed. When simulating the above, it is possible to obtain highly accurate results (results closer to reality) with respect to actual thermal expansion of the mold and thermal contraction of the product. Of course, verification of machining accuracy, material mechanical verification against various stresses (thermal stress, tensile stress, compressive stress, bending stress, buckling stress, etc.) in addition to strain such as solidification and thermal shrinkage, and fracture mechanics (metal Even in verifications that are assumed to have regularity, such as verifications such as fatigue, simulation results close to actual results can be obtained.

  It should be noted that the work model creation method according to the present invention is not limited to the above-described embodiment, and various configurations can be adopted without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Computer system 12 ... Computer 40 ... Point cloud information table 42A ... 1st work model processing means 42B ... 2nd work model processing means 44 ... Product model 48 ... Reference position setting means 50 ... Reference position 52 ... Cube 54 ... Reference cube Placement means 56 ... Cube arrangement means 58 ... Point group selection means 60 ... Point group deletion means 62 ... First work model creation means 64 ... First work model storage means 66 ... Point group extraction means 68 ... First point selection means 70 ... Selected point group information table 72 ... Table registration means 78 ... First work model information table 82 ... Difference calculation means 84 ... Equal difference line assumption means 86 ... Second point selection means 88 ... Point group replacement means 90 ... Point replacement information table 92 ... second work model storage means 94 ... difference information tables 100a to 100d ... equal difference line

Claims (2)

This is a work model creation method that creates a work model by thinning out the point cloud of a product model that is obtained by actually measuring a manufactured product and that is composed of a cloud of points in a computer three-dimensional virtual space. And
Difference calculation means included in the computer, and the product model, and a model of the ideal work of the product which is formed in the surface, as compared with the three-dimensional virtual space of the computer, each time point was the actual measurement, A difference calculating step for determining a difference from the reference of the actually measured point on the model of the ideal workpiece and corresponding to the actually measured point;
The equidistant line assumption means included in the computer is a virtual equidistant line connecting the same difference points, and assumes an equidistant line of a difference that is different by an arbitrary width from a difference between adjacent equality lines. An equidistant line assumption step;
A point selection step in which the point selection means provided in the computer selects a point group that is on the assumed equality difference line and the adjacent distance is a point selection distance;
Storing means included in the computer, the point group selected in said point selecting step, the workpiece model creation method characterized by having a workpiece model storage step of storing in the storage medium as a work model. In work model creation method according to claim 1 Symbol placement,
The equidistant line assumption step includes
Assuming a reference equidistant line with the distance corresponding to 1/2 of the longest distance between two points in the point group constituting the product as the difference;
Sequentially assuming a plurality of equality lines moving away from the reference equality line,
The width between the adjacent equality lines is a distance corresponding to 1 / n (n = 2, 3, 4,...) Of the difference in the reference equality line .
The work model creation method, wherein the point selection distance in the point selection step is a distance corresponding to a shortest distance between two points in a point group constituting the product model.

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