JP2005275596A - Cad model abnormal part detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CAD model abnormal part detection method for detecting abnormal parts on a CAD model, in advance prior to the manufacturing a product. <P>SOLUTION: The CAD model abnormal part detection method successively execute the processing of face element output processing for outputting a plurality of face elements by using a conversion tool for converting a data format from CAD model data; a vector generation processing for designating a measurement range from each face element, and for generating a normal vector toward the outside of a CAD model; a decision processing for deciding whether or not normal vectors cross each other in the measurement range; a coloring processing for, when the normal vectors cross each other, coloring the face elements generating the crossing normal vectors; an extraction processing for extracting only the colored face elements; and an overlapping processing for overlapping the extracted face elements with the respective face elements outputted from the CAD model data. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a CAD model abnormal location detection method for detecting whether or not an abnormal location exists in a CAD model.

  For example, in order to design a product, it is common to use a CAD (Computer Aided Design) system and model the product shape with the CAD system. For a modeled CAD model, rotate the CAD model in any direction on the monitor, determine whether there is an abnormal part with the naked eye, and if there is an abnormal part, change the design of that part. Has been done.

  In addition, the abnormal part defined here is a sharp convex part or a concave part, and it is a part that is difficult to process when a mold is created from this CAD model, or when it is actually a product. , Points that are not suitable as a product, such as easy to break.

Further, there is disclosed a method for analyzing data based on shape data generated by a CAD system, instead of finding an abnormal portion with the naked eye by rotating a CAD model on a monitor (for example, Patent Document 1). reference).
JP 2002-207777 (pages 5 to 7, FIG. 9)

  However, if the CAD model is a simple three-dimensional shape, the CAD model on the monitor can be rotated in an arbitrary direction to find an abnormal part with the naked eye, but the more complicated the three-dimensional shape is, It is difficult to find details that are difficult to see with the naked eye.

  When a mold is created based on a CAD model having an abnormal part without noticing the presence of such an abnormal part, an acute convex part or concave part is formed in the mold. Such acute convex portions or concave portions not only deteriorate the mold life, but are likely to be damaged by the molding pressure.

  In addition, when machining such a mold, since a cutting bit for machining does not enter a sharp recess, it is not possible to perform machining, so it is necessary to create an expensive electrode and perform electric discharge machining, which increases the cost of the mold. Result.

  In addition, since the molded product has burrs in the above-described abnormal portions, there is a risk that secondary processing to remove the burrs is necessary, or that there is a sharp portion as it is distributed in the market.

  Therefore, the present invention has been made to solve the above-described problems, and provides a CAD model abnormal part detection method that detects an abnormal part at the stage of the CAD model and does not affect subsequent processes. Objective.

  According to the first aspect of the present invention, there is provided a surface element output process for outputting a plurality of surface elements using a conversion tool for converting a data format from CAD model data, and an outside of the CAD model by specifying a measurement range from each surface element. A vector generation process for generating a normal vector in a direction toward the direction, a determination process for determining whether or not the normal vectors cross within the measurement range, and the normal vectors cross each other. In this case, a coloring process for coloring the surface element that generates the intersecting normal vector, an extraction process for extracting only the colored surface element, and the extracted surface element are output from the CAD model data. In addition, the overlapping process for superimposing each surface element is sequentially performed.

  A second aspect of the present invention is the CAD model abnormal portion detection method according to the first aspect, wherein after the extraction process, a mark providing process for marking each extracted surface element is performed.

  A third aspect of the present invention is the CAD model abnormal part detecting method according to the first or second aspect, wherein the surface element is a polygon, an FEM mesh, or a patch.

  According to the first aspect of the present invention, the surface element at the point where the normal vectors generated in the direction toward the outside of the CAD model by designating the measurement range are abnormal points. By coloring and overlaying each surface element output from the original CAD model data, it is possible to find an abnormal part that is difficult to see with the naked eye. By using this method, it is possible to easily find the abnormal part of any complex shape before creating the actual product, which is useful for the subsequent processes such as the mold making process and the product manufacturing process. Can be made.

  According to the second aspect of the present invention, if a mark is attached to a surface element that is an abnormal place, anyone can easily detect the abnormal place.

  According to the third aspect of the present invention, since polygons, FEM meshes, or patches are used as the surface elements, a plurality of CAD model surface data is obtained by a conversion tool generally used in this type of image processing technology. It can be converted to the surface element.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  FIG. 1 is a flowchart showing detection processing of a CAD model abnormal part detection method according to the present invention, and FIGS. 2 to 7 are schematic views showing processing states in each processing step.

  This detection process starts by executing a computer program. In the process of step S1, first, a product (three-dimensional part) to be manufactured is created as CAD model data. The CAD model data here is mainly composed of points and lines that define a shape, and a surface.

  In the present embodiment, for example, a model having a three-dimensional shape as shown in FIG. In this CAD model 1, a small protrusion 2 is formed on the side surface, and the base portion of the protrusion 2 is an abnormal portion having an acute concave portion.

  Next, in step S2, a surface element output process for outputting a plurality of surface elements is performed using a conversion tool that converts the data format from CAD model data. That is, the conversion tool converts the original CAD model data into another data format, and divides the surface of the CAD model 1 into a plurality of surface elements 1a as shown in FIG. Specifically, a translator, a converter, or the like is used as a conversion tool, and a plurality of polygons, FEM (finite element method) meshes, or patches are output as surface elements. In FIG. 3, a triangular polygon is output as the surface element 1a.

  Next, the detection process proceeds to step S3, and as shown in FIGS. 4 and 5, a vector generation process for generating a normal vector V in a direction toward the outside of the CAD model by designating a measurement range from each surface element 1a. I do. The measurement range refers to a range from each surface element 1a to a position separated by a certain distance toward the outside of the CAD model 1 as indicated by a two-dot chain line in FIG. This measurement range is determined as a range width in which sharp convex portions or concave portions that are not suitable as a mold or a product are to be formed.

  Next, in step S4, determination processing is performed in which determination is performed using the normal vector V generated from each surface element 1a. That is, it is determined whether or not the normal vectors V generated by designating the measurement ranges from the surface elements 1a intersect each other. If the normal vectors V do not intersect with each other, it is determined that there is no abnormal part in the process of step S5. Then, the detection process proceeds to step S6. In step S6, since there is no abnormal part, no subsequent process is performed.

  If the normal vectors V intersect, the detection process proceeds to step S7, and it is determined that there is an abnormal part in the CAD model 1 in the process of step S7. As shown in FIG. 5, the abnormal part is found at the base of the protrusion 2 where the normal vectors V intersect.

  Next, in step S8, a coloring process for coloring the surface element 1a that has generated the intersecting normal vector V is performed. Specifically, the target polygon, FEM mesh, or patch is colored so that it can be easily judged visually.

  In the next step S9, an extraction process for extracting only the colored surface element 1a is performed. FIG. 6 shows a state in which only the colored surface element 1a is extracted.

  Next, in step S10, a mark providing process for marking each extracted surface element 1a is performed. Specifically, an annotation is added to each extracted polygon, FEM mesh, or patch. For example, as an annotation, an arrow or a circle is attached in the vicinity of the colored surface element 1a.

  Finally, the detection process proceeds to step S11. In step S11, a superimposition process for superimposing the colored surface element 1a on each surface element 1a output from the CAD model data is performed. That is, the extracted polygon, FEM mesh, or patch is superimposed on the polygon, FEM mesh, or patch output from the CAD model 1 using a translator or converter.

  Here, in order to indicate which part of the CAD model 1 the extracted surface element 1a corresponds to, the extracted polygon and the polygon output from the CAD model 1 are overlapped.

  FIG. 7 is a schematic diagram showing a state in which the extracted surface element 1a is superimposed on each surface element 1a output from the CAD model data. As can be seen from this figure, it can be visually determined that the base portion of the protrusion 2 is colored as compared with other portions. Normally, such intricate details cannot be determined whether or not there is an abnormal part E even if the CAD model 1 is rotated in an arbitrary direction on the monitor. However, the abnormal part E can be easily detected.

  As described above, if the CAD model abnormal part detection method according to the present invention is used, an intricately detailed abnormal part E that cannot be seen from the outer surface with the naked eye is detected on the CAD model 1 before the actual product is manufactured. can do. If this abnormal part E can be detected on the CAD model 1, the abnormal part E is corrected from an acute angle shape to a normal part S such as an obtuse angle shape (R shape) as shown in FIG. A mold 3 can be created based on the CAD model 1.

  By doing so, since a sharp convex part and a recessed part are not formed in the metal mold | die 3, it can prevent that the metal mold | die 3 is damaged with a shaping | molding pressure, and can prolong the mold life. Further, there is no need to process a part of the mold 3 by electric discharge machining, and the mold cost can be reduced. Furthermore, since a burr or the like is not generated in the product manufactured by the mold 3, troublesome deburring and removal processing can be omitted.

  In this way, by adopting the CAD model abnormal part detection method according to the present invention, the abnormal part E can be detected on the CAD model 1 in advance before manufacturing the product, so that the post process is advantageous. And its industrial value is very high. Further, the method of the present invention is a very effective technique for all products that use a mold to produce products.

  Although specific embodiments to which the present invention is applied have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  The CAD model 1 shown in FIG. 2 has a simple shape to make the contents of the invention easy to understand. However, even if the shape is more complicated than this, it is possible to easily detect the abnormal part E. Needless to say.

It is a flowchart which shows the detection process of the CAD model abnormal location detection method concerning this invention. It is a schematic diagram of a CAD model. It is a schematic diagram which shows the state which divided | segmented the surface of the CAD model into several surface element. It is a schematic diagram which shows the state which designated the measurement range from each surface element, and generated the normal vector in the direction which goes outside a CAD model. It is a principal part enlarged view of the base part of the projection part of FIG. It is a schematic diagram which shows the state which extracted only the colored surface element. It is a schematic diagram which shows the state which overlap | superposed the extracted surface element with each surface element output from CAD model data. It is a perspective view which shows the example which correct | amended the abnormal location from the acute angle shape to the normal location like obtuse angle shape (R shape), and created the metal mold | die based on the CAD model which eliminated the abnormal location.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... CAD model 2 ... Protruding part 3 ... Mold V ... Normal vector E ... Abnormal part

Claims (3)

A surface element output process for outputting a plurality of surface elements using a conversion tool for converting a data format from CAD model data;
A vector generation process for generating a normal vector in a direction toward the outside of the CAD model by designating a measurement range from each surface element;
A determination process for determining whether or not the normal vectors intersect within the measurement range;
A coloring process for coloring a surface element that generates the intersecting normal vectors when the normal vectors intersect;
An extraction process for extracting only the colored surface elements;
A CAD model abnormality location detection method, comprising: sequentially performing a superimposition process of superimposing the extracted surface elements on each surface element output from the CAD model data. The CAD model abnormality location detection method according to claim 1,
After the extraction process, a CAD model abnormal part detection method, wherein a mark providing process for marking each extracted surface element is performed. The CAD model abnormality location detection method according to claim 1 or 2,
A CAD model abnormal part detection method, wherein the surface element is a polygon, FEM mesh, or patch.