An Algorithm for the Removing of Offset Loop Twists during the Tool Path Generation of FDM 3D Printer

Islam Md. Olioul(올리올 이슬람),Ho-Chan Kim(김호찬) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.3

Tool path generation is a part of process planning in 3D printing. This is done before actual printing by a computer rather than an AM machine. The mesh geometry of the 3D model is sliced layer-by-layer along the Z-axis and tool paths are generated from the sliced layers. Each 2-dimensional layer can have two types of printing paths: (i) shell and (ii) infill. Shell paths are made of offset loops. During shell generation, twists can be produced in offset loops which will cause twisted tool paths. As a twisted tool path cannot be printed, it is necessary to remove these twists during process planning. In this research, An algorithm is presented to remove twists from the offset loops. To do so the path segments are traversed to identify twisted points. Outer offset loops are represented in the counter-clockwise segment order and clockwise rotation for the inner offset loop to decide which twisted loop should be removed. After testing practical 3D models, the proposed algorithm is verified to use in tool path generation for 3D printing.

Introducing a novel mesh following technique for approximation-free robotic tool path trajectories

Carmelo Mineo,Stephen Gareth Pierce,Pascual Ian Nicholson,Ian Cooper 한국CDE학회 2017 Journal of computational design and engineering Vol.4 No.3

Modern tools for designing and manufacturing of large components with complex geometries allow more flexible production with reduced cycle times. This is achieved through a combination of traditional subtractive approaches and new additive manufacturing processes. The problem of generating optimum tool-paths to perform specific actions (e.g. part manufacturing or inspection) on curved surface samples, through numerical control machinery or robotic manipulators, will be increasingly encountered. Part variability often precludes using original design CAD data directly for toolpath generation (especially for composite materials), instead surface mapping software is often used to generate tessellated models. However, such models differ from precise analytical models and are often not suitable to be used in current commercially available path-planning software, since they require formats where the geometrical entities are mathematically represented thus introducing approximation errors which propagate into the generated toolpath. This work adopts a fundamentally different approach to such surface mapping and presents a novel Mesh Following Technique (MFT) for the generation of tool-paths directly from tessellated models. The technique does not introduce any approximation and allows smoother and more accurate surface following tool-paths to be generated. The background mathematics to the new MFT algorithm are introduced and the algorithm is validated by testing through an application example. Comparative metrology experiments were undertaken to assess the tracking performance of the MFT algorithms, compared to tool-paths generated through commercial software. It is shown that the MFT tool-paths produced 40% smaller errors and up to 66% lower dispersion around the mean values.

An Algorithm for the Removing of Offset Loop Twists during the Tool Path Generation of FDM 3D Printer

올리올 이슬람,김호찬 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.3

Tool path generation is a part of process planning in 3D printing. This is done before actual printing by acomputer rather than an AM machine. The mesh geometry of the 3D model is sliced layer-by-layer along theZ-axis and tool paths are generated from the sliced layers. Each 2-dimensional layer can have two types ofprinting paths: (i) shell and (ii) infill. Shell paths are made of offset loops. During shell generation, twists canbe produced in offset loops which will cause twisted tool paths. As a twisted tool path cannot be printed, it isnecessary to remove these twists during process planning. In this research, An algorithm is presented to removetwists from the offset loops. To do so the path segments are traversed to identify twisted points. Outer offsetloops are represented in the counter-clockwise segment order and clockwise rotation for the inner offset loop todecide which twisted loop should be removed. After testing practical 3D models, the proposed algorithm isverified to use in tool path generation for 3D printing.

로봇을 이용한 두개골 천공 시스템의 공구 경로 생성

정연찬(YunChan Chung) (사)한국CDE학회 2013 한국CDE학회 논문집 Vol.18 No.4

This paper presents a tool-path generation methods for an automated robotic system for skull drilling, which is performed to access to some neurosurgical interventions. The path controls of the robotic system are classified as move, probe, cut, and poke motions. The four motions are the basic motion elements of the tool-paths to make a hole on a skull. Probing, rough cutting and fine cutting paths are generated for skull drilling. For the rough cutting path circular paths are projected on the offset surfaces of the outer top and the inner bottom surfaces of the skull. The projected paths become the paths on the top and bottom layers of the rough cutting paths. The two projected paths are blended for the paths on the other layers. Syntax of the motion commands for a file format is also suggested for the tool-paths. Implementation and simulation results show that the possibility of the proposed methods.

Development of an analysis system for geometric contour error evaluation in ultra-precision machining for microlens arrays

유효선,양정삼 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.10

A basic principle for acquiring precisely shaped machined parts is to create dense tool path data. However, as the density of tool pathsincreases, the volume of data increases. The significant increase in data consumes more memory and machining time. Therefore, thecreation of tool path data of unlimited density is impractical. This paper proposes a contour error evaluation system. The system makescorrect decisions based on the expected quality of a workpiece. Specifically, the user creates tool path data by calculating deviations inthe contour in relation to variations in the intervals of the tool path. The user can create tool paths by adjusting the amount of tool pathdata within the desired quality level. Accordingly, before the start of the machining process, the user can predict any machining loss likelyto result from the excessive amount of data created in the creation phase. In addition, the tool path data of the proposed system areexperimentally compared with the actual shape of a part machined with a microlens array machining system.

수직벽 가공을 위한 레이저 밀링 경로생성 알고리즘

김형중(H. J. Kim),위경훈(K. H. Wie),안성훈(S. H. Ahn),전차수(C. S. Kim),김학일(H. I. Kim) 한국정밀공학회 2009 한국정밀공학회 학술발표대회 논문집 Vol.2009 No.6월

2 축 동시구동을 통한 볼바 측정용 원호경로 생성 방법

이동목(Dong-Mok Lee),이훈희(Hoon-Hee Lee),양승한(Seung-Han Yang) 대한기계학회 2013 大韓機械學會論文集A Vol.37 No.6

5 축 공작기계에서 회전축을 포함한 동시 구동에 대한 볼바 측정용 원호 경로 생성 및 NC 데이터 작성은 CAM 소프트웨어를 사용할 경우 공작기계의 구조, 사용되는 동시 구동축 종류 및 볼바 셋업 조건 등 다양한 시스템 구조와 변경된 측정 환경에 따라 매번 많은 시간과 노력을 수반해야 한다. 본 연구는 소프트웨어의 의존 없이 다양한 볼바 측정 조건에서도 항상 사용할 수 있는 두 축 동시 구동을 통한 원호 경로를 생성하는 기법을 소개하며 임의의 공작기계의 구조 및 동시 구동축의 종류, 볼바 셋업 조건 등을 고려한다. 제안한 원호 생성 기술을 이용하여 세 가지의 사례에 대한 원호 경로 생성용 수학식을 제시하며 더불어 볼바 부품간 물리적 간섭을 방지하기 위한 측정 가능성 사전 검사 방법을 제안한다. 제안한 기법의 타당성은 두 개의 회전축을 이용한 볼바 측정 실험을 통해서 검증한다. Circular path generation for ball bar measurement using the simultaneous movement of two axes with at least one rotary axis requires the execution of CAM software. However, a change in the machine type or measurement condition requires a new execution of the CAM software, which is cumbersome. This paper presents a circular path generation technique that does not require CAM software and is applicable to different types of driving axes with an arbitrary structural configuration of machine tools and any ball bar setup condition. Mathematical equations are derived for three cases using the proposed technique. In addition, to inspect the measurement feasibility for avoiding physical interference among the ball bar parts, a tilting angle calculation is proposed. The validity of the proposed technique was verified by performing a ball bar experiment with A and C as the simultaneous axes of a five-axis machine tool.

STL offset을 이용한 다이레스 CNC 포밍용 등고선 공구경로 생성

강재관(Jae-Gwan Kang),최동우(Dong-Woo Choi) Korean Society for Precision Engineering 2006 한국정밀공학회지 Vol.23 No.2

Dieless CNC forming is an innovative technology which can form various materials with complex shape by numerically controlled incremental forming process. In this paper, a method of NC tool path generation based on an STL file for dieless CNC forming is proposed. Tool trajectory adopts the principle of layered manufacturing in rapid prototyping technology, but it is necessary to consider STL offset because of the ball shaped tool with a radius. Vertex offset method which enables to compute offset STL directly is engaged for STL offset. The offseted STL is sliced by cutting planes to generate contouring tool path. Algorithm is implemented on a computer and experimented on a dieless CNC forming machine to show its validity.

이산 환형 방식의 비구면 렌즈 연마 경로에서 체재 시간 계산 알고리듬

이호철,양민양 한국공작기계학회 2005 한국생산제조학회지 Vol.14 No.2

This paper describes a dwell time calculation algorithm for polishing tool path generation in the small tool polishing process of the axis-symmetrical lens. Generally dwell time control in the polishing machines means that small polishing tool stays for a dwell time at the specific surface position to get the expected polishing depth. Polishing depth distribution on an aspherical lens surface consists of the superposition of the local polishing depth at the each dwell position. Therefore, tool path generation needs each dwell time together with tool positioning data during the polishing tool movements on the aspherical lens surface. The linear algebraic equation of removal depth, removal matrix, and dwell time is formulated. Parametric effects such as the dwell grid interval are simulated to validate the dwell time calculation algorithm.

2 축 동시구동을 통한 원호경로 생성 방법

이동목(Dong-Mok LEE),이훈희(Hoon-Hee LEE),양승한(Seung-Han YANG) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

For evaluating the relative motion of two axes under simultaneous movement, the most preferred measurement system is the ball bar system where circular measurement path is required. In this paper, a circular path generation technique during simultaneous two axes movement for the ball bar measurement in a five axis machine tool is presented. The technique is applicable for all machine tools irrespective of their structural configurations. Mathematical equations with measurement conditions and machine information as parameters are derived for two cases following the suggested technique.