• Title/Summary/Keyword: STL

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STL mesh based laser scan planning system for complex freeform surfaces (STL 메쉬를 이용한 자유곡면의 레이저 측정경로 생성 연구)

  • 손석배;김승만;이관행
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.595-598
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    • 2002
  • Laser scanners are getting used more and more in reverse engineering and inspection. For CNC-driven laser scanners, it is important to automate the scanning operations to improve the accuracy of capture point data and to reduce scanning time in industry. However, there are few research works on laser scan planning system. In addition, it is difficult to directly analyze multi-patched freeform models. In this paper, we propose an STL (Stereolithography) mesh based laser scan planning system for complex freeform surfaces. The scan planning system consists of three steps and it is assumed that the CAD model of the part exists. Firstly, the surface model is approximated into STL meshes. From the mesh model, normal vector of each node point is estimated. Second, scan directions and regions are determined through the region growing method. Also, scan paths are generated by calculating the minimum-bounding rectangle of points that can be scanned in each scan direction. Finally, the generated scan directions and paths are validated by checking optical constraints and the collision between the laser probe and the part to be scanned.

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An Analysis of the Sound Transmission through a Plate Installed inside an Impedance Tube (임피던스 튜브 내에 설치된 평판의 음파투과해석)

  • Kim, Hyun-Sil;Kim, Bong-Ki;Kim, Sang-Ryul;Lee, Seong-Hyun
    • The Journal of the Acoustical Society of Korea
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    • v.34 no.3
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    • pp.219-226
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    • 2015
  • In this paper, derivation of the STL (Sound Transmission Loss) of a square plate installed in an impedance tube is discussed using an analytic method. Coupled motion of the plate vibration and acoustic field is considered. Vibration of the plate and pressure field inside the tube are expressed in terms of the infinite series of modal functions. Under the plane wave assumption, it is shown that consideration of the first few modes yields sufficiently accurate results. When the boundary of the plate is clamped, vibration mode is assumed as a multiplication of the beam modes corresponding to the crosswise directions. The natural frequencies of the clamped plate are calculated using the Rayleigh-Ritz method. It is found that the STL shows a dip at the lowest natural frequency of the plate, and increases as the frequency decreases below the natural frequency. Comparison of the result in this paper with the STL obtained by measurements and FE computations in the reference shows an excellent agreement.

Sound transmission of multi-layered micro-perforated plates in a cylindrical impedance tube (원통형 임피던스 튜브 내 다중 미세천공 판의 음향투과)

  • Kim, Hyun-Sil;Ma, Pyung-Sik;Kim, Bong-Ki;Lee, Seong-Hyun;Seo, Yun-Ho
    • The Journal of the Acoustical Society of Korea
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    • v.39 no.4
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    • pp.270-278
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    • 2020
  • In this paper, sound transmission of Micro-Perforated Plates (MPPs) installed in an impedance tube with a circular cross-section is described using an analytic method. Vibration of the plates is expressed in terms of an infinite series of modal functions, where modal function in the radial direction is given by the Bessel function. Under the plane wave assumption, a low frequency approximation is derived, and a formula for the sound transmission coefficient of multi-layered MPPs is presented using the transfer matrix method. The Sound Transmission Losses (STLs) of single and double MPPs are computed using the proposed method and compared with those done by the Finite Element Method (FEM), which shows an excellent agreement. As the perforation increases, the STL is degraded, since the STL becomes dominated by the perforation ratio rather than by vibration of the plate. The STL shows dips at natural frequencies as well as at the mass-spring-mass resonance frequency. The proposed model for the STL prediction in this study can be applied to an arbitrary number of MPPs, where each MPP may or may not have a perforation.

A Study on RP Part Production Using Intersecting Circle Approximation Method (교차다각형법에 의한 원 근사 방법을 적용한 RP Part 제작에 관한 연구)

  • 신근하
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.1
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    • pp.68-74
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    • 2000
  • The STL file format is an approximation of 3-D model with triangular facets. STL is a standard input file format of Rapid Prototyping(RP) equipment In computer graphics a circle has been approximated with an inscribed polygon which causes an error between the real and approximated circles. In this study an intersecting polygon has been used to approximate the circle and applied to produce more accurate RP part. The newly proposed method shows it's excellence in part accuracy.

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A Slicer Development for CAFL$^{VM}$System (CAFL$^{VM}$ 시스템을 위한 단면정보 추출기의 개발)

  • 공용해;김기석;엄태준;방재철
    • Proceedings of the Korea Multimedia Society Conference
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    • 2001.06a
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    • pp.3-7
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    • 2001
  • 본 연구에서는 다종재료를 가공할 수 있는 RP(Rapid Prototyping)인 CAFL$^{VM}$의 구현을 위해 반드시 필요한 단면정보 추출기에 대하여 연구하였다. STL 3D 모형에서 단면정보를 추출하기 위해서, 패싯(facet)과 슬라이싱(slicing) 평면이 가질 수 있는 모든 경우를 고려한 알고리즘을 개발하였다. STL 파일의 구조적인 문제점 때문에 모호성과 처리량 증가 문제가 발생하지만, 본 연구에서는 창조 버퍼를 사용하여 이러한 문제점들을 효과적으로 해결하였으며, 이를 많은 STL 3D 샘플로 검증하였다.

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Application of Delaunay Triangulation on RP (Delaunay삼각형 분할법의 RP에의 응용)

  • 명태식;채희창;김옥현
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.8 no.3
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    • pp.35-41
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    • 1999
  • 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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Measurement of sound Insulation of small-size windows (소형 창문의 차음성능 측정에 관한 고찰)

  • Kim, Sang-Ryul;Kang, Hyun-Ju;Kim, Jae-Seung;Kim, Hyun-Sil;Kim, Bong-Ki
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.11a
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    • pp.942-945
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    • 2006
  • In order to measure the sound transmission loss(STL) of a test specimen such as windows, which is smaller than the test opening, a special partition is built into the test opening and the specimen is placed in that partition. This paper discusses how the measured STL is changed by the partition when a small-size window of high sound insulation is mounted. Theoretical and experimental investigations are carried out to quantify the effect of the filler wall. The results reveal that the smaller the window size is, the higher sound insulation performance of the filler wall is required in order to measure the accurate STL of the specimen. It is found that the insufficient sound insulation of the filler wall leads to the lower measured value of the window's STL.

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A Study on the Improvement of Form Accuracy Using the Length Strain of Rapid Prototype (쾌속조형장치의 길이오차를 이용한 형상정밀도 개선에 관한 연구)

  • Kim Tae Ho;Park Jae Duk;Kim Min Ju;Lee Seung-Soo;Lee Jun Hee;Jeon Eon-Chan
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.12
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    • pp.154-159
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    • 2004
  • This study is aimed to diminish the errors which created during transforming from 3D shape created with CAD program to STL file formation. The length strain which created on X-Y axises at STL file transforming is diminished by using the relation between common shape error and shrinkage rate. As the result of study, we have confirmed the length strain in accordance with facetres value. Also, the shape error is compensated with shrinkage rate by error of length strain. so, we could diminish to shape error by several tens micrometer.

The study on the reducing of scanning path creation time using SLC file. (SLC파일을 이용한 주사경로 생성 시간 단축에 관한 연구)

  • 김태호;장성규;박정보;이준희;전언찬
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2004.10a
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    • pp.114-118
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    • 2004
  • This paper is compared the build time of scanning path as to laminate height of the SLC and STL file. The STL file improve the surface roughness according to slicing height. But it have the fault spending long time to the creation of scanning path by being lower slicing height. So we proposed the SLC file to improve this fault. Therefore this paper showed to the build time of scanning path by the increase of peace using the jewellery model.

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A Tool for STL file modeling for 3D Printer (3D 프린터를 위한 STL 파일 모델링 도구)

  • Min, GaYoung;Choi, Sun-Hyeok;Kim, YoungGyun;Yoo, Kwan Hee
    • Proceedings of the Korea Information Processing Society Conference
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    • 2017.04a
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    • pp.966-969
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    • 2017
  • 3D프린터 기술의 발달로 인해 다가오는 3D프린터의 개인화 시대에 맞추어 개인이 자신이 원하는 출력물을 자유롭게 쉽게 디자인하여 물체를 출력할 수 있도록 도와주는 3D모델링 툴이다. 본 논문에서는 3D프린터 사용에 가장 일반적으로 사용되는 STL파일을 사용자가 별도의 변환과정없이 오브젝트를 바로 STL로 만들어 낼 수 있는 모델링 도구를 제시한다.