• Title, Summary, Keyword: 급속조형

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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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The Application of Delaunay Triangulation on RP (Delaunay 삼각형 분합법의 RP에의 응용)

  • 김대원
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.129-134
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    • 1998
  • STL which is used in Rapid Prototyping is composed of a lot of triangular facets. The number of triangles and the shapes of these triangles determine the quality of STL. Therefore, proper algorithm is necessary to enhance the quality of triangular patch. In this paper we used the Delaunay triangulation method to apply to following processes. 1) On processing for reducing sharp triangles which cause errors on intersection. 2) On processing for connecting two or more collinear edges. 3) On processing for deleting unnecessarily inserted points in coplanar polygon.

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Reverse Engineering을 이용한 신속 시제품 제작

  • 송용억;박세형;하성도;박태권;김무중
    • CDE review
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    • v.2 no.2
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    • pp.50-51
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    • 1996
  • 본 과제에서는 point data를 사용하여 CAD에서 모델링된 프로펠러를 LOM 공정으로 제작한 후 LOM 모델을 master pattern으로 사용하여 주조까지 실행하는 작업을 실시하였다. 주조공정시 알루미늄을 소재로 사용하였으며, 주조된 프로펠러는 기능테스트에 사용할 수 있는 성능을 지니고 있다. 이 결과는 현재까지 프로펠러 제작용으로 주로 사용하던 5축 가공을 rapid prototyping과 주조방법을 통해 대처할 수 있는 가능성을 제시하고 있다. 그러나 아직 제품의 정확도가 부족하여 오차 발생원인 및 누적과정을 분석하여 정확도를 향상시키는 작업이 향후 연구과제로 남아있다. 본 연구는 현재 수행중인 국제공동과제 "동시공학 구현을 위한 형상설계 및 급속조형 기술 개발"의 일부이며 알피 코리아사와 삼성중공업의 기술적 도움으로 진행되었다.

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Rapid Tooling : Challenge to Net Shape by Powder Casting (급속금형제작 (1): 분말주조에 의한 정형(正形)에의 도전)

  • 임용관;김범수;정해도;배원병
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.7
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    • pp.85-90
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    • 1998
  • The business of manufacturing is increasingly becoming time-compressing, precise and long-life oriented, owing to various needs from the consumers and harsh global competition. With the emergence of the layer laminate manufacturing method, it is possible to produce prototypes directly from 3D CAD and additive process, the production time and cost have shortened dramatically. However there are some problems like surface-step, dimensional deviation and warp. A newly developed powder casting is suitable for rapid-manufacturing metallic tools. Powder casting can serve as a promising rapid tooling method because of high density characteristics and low dimensional shrinkage below 0.1% during sintering and infiltration. By this process, we have realized significant time savings bypassing the wait for prototype tooling and cost savings eliminating the expense of conventional prototype tooling process.

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A Study on DB Construction for Error Modification of STL Format and Efficiency by Shape Restoration (STL 포맷의 오류수정을 위한 DB 구축과 형상복구에 의한 효율성 연구)

  • 손영지;박정보;김순경;김중완;전언찬
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.12
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    • pp.21-27
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    • 1998
  • This paper recommends the database construction for STL data and the new method of Delaunay's triangulation method in order to decrease volume errors by verifying STL file errors and modifying hole errors. Each vertex for the boundary coordinates of the verified hole errors was analyzed according to the following cases: planes or slow curves, edges, apexes, and rapid curves. In each case, a different modification process was adopted. With this method, most errors resulting from the conversion into the STL data as well as lots of volume errors arising from error modification were decreased.

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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 the Boolean Operation Of STL Format (STL 포맷의 BOOLEAN 연산에 대한 연구)

  • Son, Beom-Soo;Jeon, Eon-Chan
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.9
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    • pp.194-201
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    • 2005
  • Recently, as Rapid Prototyping is attracting people's attention, many peoples are actively participating in the research on STL format. The STL files are transformed to be input for RP after modeling in CAD system. When the shape, however, needs to be changed or edited, it is impossible without the original data. So, if the original data is lost, new modeling is required. Therefore, this study suggests a way to edit the shape in STL format and to make the Boolean operation possible between the original and edited shapes. In addition, the reliability was confirmed after going over the errors of the edited data.

A Study on the Solidification Structure of Al-Si Alloy by the Continuous Casting with the Heated Mold (가열주형식 연속주조법에 의한 Al-Si합금의 응고조직에 관한 연구)

  • Kim, Won-Tae;Moon, Jeong-Tak;Kim, Myung-Han;Jo, Hyung-Ho
    • Journal of Korea Foundry Society
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    • v.14 no.5
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    • pp.464-470
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    • 1994
  • The horizontal continuous casting method with the heated mold was applied to study the solidification structures of the pure Al and Al-0.5wt%Si and Al-1.0wt%Si alloy rods. The results could be summarized as follows: 1. The S/L interface structures of pure Al represented the hexagonal cells at the casting speed of 590 and 350mm/min, respectively. However, the hexagonal cells became irregular as the casting speed and(or) Si amount increased. 2. The striation increased as the Si amount and casting speed increased and was found to result from the occurrence of growth twin crystals by XRD analysis. 3. The striation did not affect the mechanical and electrical property of the drawn wire from the casted rod. This means the striation is not a serious defect which has to consider in the production of micro-sized fine wire in the drawing process.

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A Study on the Occurrence of the Striation Defect during the Continuous Casting with the Heated Mold (가열주형 연속주조시 발생되는 줄무늬 결함에 관한 연구)

  • An, Ki-Sung;Song, Tae-Seck;Ji, Tae-Gu;Jo, Hyung-Ho;Kim, Myung-Han
    • Journal of Korea Foundry Society
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    • v.17 no.2
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    • pp.145-150
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    • 1997
  • The striations parallel to the casting direction are the characteristic defects occurring during the unidirectional solidification of nonferrous metals such as pure Al and Sn. It has been known that the defects affect the recrystallization temperature as well as the mechanical and electrical properties of Al. However, it has not been still known about the effect of casting factors such as the casting speed, rod diameter of cast metals, and alloying elements on the occurrence of striations. In the present study, these casting factors affecting the occurrence of striation were investigated by adopting the quantitative examination of striations. Also, the relation between striation defects and feathery grain, which are very similar to the striation defects, was studied.

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A Study on the Superplastic Characteristics of Sn-38%Pb Eutectic Alloy Produced by Continuous Casting Process (연속주조법에 의한 Sn-38%Pb 공정합금의 초소성특성)

  • Song, Tae-Seok;Jo, Hyung-Ho;Choi, Jae-Ha;Ji, Tae-Gu;Kim, Myung-Han
    • Journal of Korea Foundry Society
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    • v.17 no.3
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    • pp.252-257
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    • 1997
  • The 8 mm dia: Sn-38%Pb eutectic alloy rods were produced by use of the horizontal continuous casting process with the heated mold and chill cast process. The cast rods were rolled into 2.0${\sim}$0.5 mm thick plates and structural and mechanical properties were examined. The results revealed that the plates produced by the continuous casting process with the heated mold show much higher superplasticity at ambient temperature (1550% elongation at 0.5mm thick plate and 0.5mm/min strain rate) than the plates procuced by chill cast process (630% elongation). Such a high superplasticity of the continuous cast plates is due to the high-quality plates free from any inside and surface defects with fine and uniform distribution of eutectic phases.

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