• Title/Summary/Keyword: STL Verification

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Verification of STL Using the Triangle Based Geometric Modeling (삼각형기반 형상모델러를 이용한 STL의 검증)

  • 채희창;황동기
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.578-582
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    • 1996
  • Verification of STL is essential in RP. In the study, triangle based non-manifold geometric modeling that can check intersection between triangles was used to vilify STL. The method proposed in this study can be applied at the most general case and very useful, but has a penalty on computing thime of O(n$^2$)

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Verification of STL using the Triangle Based Geometric Modeler (삼각형기반 형상모델러를 이용한 STL의 검증)

  • 채희창
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.6 no.1
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    • pp.51-58
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    • 1997
  • The verification of the STL file is essential to build the confident parts using a RP machine, because the STL file obtained from the CAD software has many errors-the orientation of triangle does not coincide with adjacent triangles or some triangles are omitted, overlpped and so forth. Especially, the STL file translated from the surface model has more errors than those translated from the solid model. In this study, all possible errors were classified with the most general from and the causes of errors were analyzed to verify and correct errors. Using the triangle based non-manifold geometric modeling, these errors were corrected. Especially, this study took the notice of the problem about the intersected triangles and non-manifold properties overlooked in the previous studies. But this study has a penalty on computing time of $O(n^2)$.

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A Study on Error Verification of STL Format for Rapid Prototyping System (급속조형 시스템을 위한 STL 포맷의 오류 검증에 관한 연구)

  • Park, H.T.;Lee, S.H.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.10
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    • pp.46-55
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    • 1996
  • As industrial standard data, the STL format which approximates three dimensional CAD model to triangular facets, is used for RP(Rapid Prototyping) system in recent days. Because most RP system take the only form of two dimensional line segments as an input stream inspite of its imperfectness while converting into STL format, a CAD model is converted into a standard industrial format which is composed of many triangular facets. The error verifying process is composed of four main steps, and these are 1) Remove facets with two or more vertices equal to each other. 2) Fix overlapping error such as more than three facets adjacent to anedge. 3) Fill holes in the mesh by using Delaunay triangulation method. 4) Correct the wrong direction and normal vectors. This paper is concerned with serching the mentioned errors in advance and modifying them.

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A Study on Error Verification of STL format for Rapid Prototyping System (급속조형시스템을 위한 STL 포멧의 오류 검증에 관한 연구)

  • 최홍태;이석희
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.597-601
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    • 1996
  • Nowadays, the STL format, industrial standard data, which approximates three dimensional CAD model to triangular facets, is used for RP(Rapid Prototyping) system. Because most RP machine is accpted to only two dimensional line segments, but some STL translators are sometimes poorly implemented. The error verifying process is as follows. 1) Remove facets with two or more vertices equal to each other. 2) Fix overlapping error such as more than three facets adjacent to an edge. 3) Fill holes in the mesh by using Delaunay triangulation method. 4) Repair wrong direction and value of normal vectors. This paper is concerned with searching the mentioned errors in advance and modifying them.

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Verification of Build Part and Tool Paths for Metal 3-D Printing Process (3차원 금속 프린팅 공정에서의 조형파트 진단 및 조형공구경로 검증)

  • Lee, Kyubok;Jee, Haeseong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.2
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    • pp.103-109
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    • 2017
  • Metal 3D printing, which is an additive metal manufacturing (AMM) process, enables the development of full-density metallic tools and parts using metal powders that are precisely delivered and controlled for deposition with no powder bed. However, some unknown geometric defects and irregular geometric features on an STL model can possibly result in incorrect metal part fabrication after the build. This study first proposes a methodical approach for verifying the build part, including the missing facet problems in an STL model, by defining some irregular features that possibly exist on the part. Second, 2D tool paths on each build layer were investigated for detecting any singular region inside the layer. The method was implemented for building two sample STL models using a direct energy deposition process, and finally, it was visually simulated for diagnosis.

A study on 3D data exchange between IGES and STL format (IGES와 SRL format 사이의 3차원 정보교고한에 관한 연구)

  • 오도근;최홍태;이석희
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.965-969
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    • 1995
  • This paper deals with effective using the IGES file for flexible data exchange among the other CAD/CAM system. If a data exchange between STL file and the neutral IGES file in Stereolithography system is available, a product design becomes more flexible. THere can be many restrictions and difficulties intranslating these data. First, an STL file follows two rules, such as right-hand rule, and vertex-to-vertex rule, thus requires a structural verification. Second, translation should be performed with minmal errors. It becomes very important to translate IGES file of limited kinds of entities fot the purpose of geometric information into STL file with minor data manipulation. The developed system suggests a good approach of translating the sampled B-spline surface of IGES and shows a potential linkage between IGES and STL format file.

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Reconstruction of 3D shape in STL file using slice data for RP (RP를 위한 슬라이스 데이터로부터 STL 포멧의 3차원 형상 재구성)

  • 허민성;최홍식;이석희
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.416-421
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    • 1997
  • This study presents a way to construct 3D shape in STL format from 2D slice data. Nowadays ahape reconstruct has been done in many ares, the application of this method is important especially in Reverse Engineering which reconstructs original shape from cross-section data. Current RP (Rapid Prototyping) is used not only for the verification of a part designed but also for the production and tooling in more effective way. In RP technology, data should be prepared in STL format. In this paper, the way to make 3D shape data in STL format form 2D slice data is described which can be used to reconstruct an original shape in RP equipment.

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Development of Physical Human Bronchial Tree Models from X-ray CT Images (X선 CT영상으로부터 인체의 기관지 모델의 개발)

  • Won, Chul-Ho;Ro, Chul-Kyun
    • Journal of Sensor Science and Technology
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    • v.11 no.5
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    • pp.263-272
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    • 2002
  • In this paper, we investigate the potential for retrieval of morphometric data from three dimensional images of conducting bronchus obtained by X-ray Computerized Tomography (CT) and to explore the potential for the use of rapid prototype machine to produce physical hollow bronchus casts for mathematical modeling and experimental verification of particle deposition models. We segment the bronchus of lung by mathematical morphology method from obtained images by CT. The surface data representing volumetric bronchus data in three dimensions are converted to STL(streolithography) file and three dimensional solid model is created by using input STL file and rapid prototype machine. Two physical hollow cast models are created from the CT images of bronchial tree phantom and living human bronchus. We evaluate the usefulness of the rapid prototype model of bronchial tree by comparing diameters of the cross sectional area bronchus segments of the original CT images and the rapid prototyping-derived models imaged by X-ray CT.

Minimization of Post-processing area for Stereolithography Parts by Selection of Part Orientation (부품방향의 선정을 통한 광조형물의 후가공면적 최소화)

  • Kim, Ho-Chan;Lee, Seok-Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.11
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    • pp.2409-2414
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    • 2002
  • The surfaces of prototypes become rough due to the stair-stepping which is the inevitable phenomenon in the Rapid Prototypes are not used only for the verification of feature. The grinding, coating, or the composition of them is a main operation in post-processing in which lots of costs and long build time are needed. The solution is proposed to increase the efficiency of rapid prototyping by minimizing or removing the composition of them is a main operation in post-processing in which lots of costs and long build time are needed. the solution is proposed to increase the efficiency of rapid prototyping by minimizing or removing the regions for post-processing. the factors to cause the surface roughness and their effects are analyzed through the experiments. Software modules are developed to predict the surface roughness of each face in the prototyping with the result. An experimental compensation method is developed to apply the modules to various RP equipments, materials and build styles. The build direction is searched with use of genetic algorithm to maximize the total areas of the surface of which roughness is better than the user-defined value.

A Study on Laser Scan Path Generation for Improving the Precision of Stereolithographic Parts (광조형물의 정밀도 향상을 위한 Laser주사경로 생성에 관한 연구)

  • Park, H.T.;Lee, S.H.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.12
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    • pp.142-150
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    • 1996
  • Nowadays, as the development paeiod of new products becomes even shorter, the importance of Rapid Prototyping Technology(RPT) has been rapidly increased. The major application of RPT is an early verification of product designs and quick production of prototypes for testing. Moreover, RPT is applied not only as a second tooling process such as mold making and investment casting but also as a creating some physical structure in medical field. Despite the remarkable progress of RPT, it is required to improve various problems resulting from application such as production time, accuracy and materials. This paper presents a laser scan path generation for accuracy of stereolithographicparts The methodology of laser scan path generation is discussed based on the stereolithography, The procedure of this research is as follows : 1) Input laser scanning conditions such as a laser beam diameter and a laser scanning interval, 2) Reconstruct original contours without self intersecting offset, 3) Calculate offset about reconstructed contours, 4) Calculate intersection points between horizontal or vertical lines and offset contours for internal hatch, 5) Decide laser shutter on/off points. The algorithm developed and programmed by C language is verified as an efficient method after testing a number of STL files of mechanical parts.

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