• Title/Summary/Keyword: Pocket Machining

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Generation of Cutting Layers and Tool Selection for 3D Pocket Machining (3차원 포켓가공을 위한 절삭층 형성 및 공구선정)

  • 경영민;조규갑
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.9
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    • pp.101-110
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    • 1998
  • In process planning for 3D pocket machining, the critical issues for the optimal process planning are the generation of cutting layers and the tool selection for each cutting layers as well as the other factors such as the determination of machining types, tool path, etc. This paper describes the optimal tool selection on a single cutting layer for 2D pocket machining, the generation of cutting layers for 3D pocket machining, the determination of the thickness of each cutting layers, the determination of the tool combinations for each cutting layers and also the development of an algorithm for determining the machining sequence which reduces the number of tool exchanges, which are based on the backward approach. The branch and bound method is applied to select the optimal tools for each cutting layer, and an algorithmic procedure is developed to determine the machining sequence consisting of the pairs of the cutting layers and cutting tools to be used in the same operation.

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An Algorithm for Reducing the Tool Retraction Length in Zigzag Pocket Machining (Zigzag 포켓가공에서 공구후퇴 길이를 줄이는 알고리듬)

  • Kim, Byoung Keuk;Park, Joon Young
    • Journal of Korean Institute of Industrial Engineers
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    • v.28 no.2
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    • pp.128-138
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    • 2002
  • In this paper, we address how to reduce the length of tool retraction in a zigzag pocket machining. Tool retraction, in a zigzag pocket machining, is a non-cutting operation in which the tool moves to any remaining regions for machining. We developed an algorithm of generating tool retraction length in convex or concave polygonal shapes including islands. In the algorithm, we consider concave areas of cutting direction in the polygonal shape. Considering concave areas of cutting direction, the polygonal shape is decomposed to subregions which do not need any tool retraction. Using the proposed algorithm, we calculated the shortest length of tool retraction in cutting direction. Examples are shown to verify the validity of the algorithm.

An Optimal Tool Selection Method for Pocket Machining (포켓형상가공을 위한 최적공구 선정방법)

  • Y.M. Kyoung;K.K. Cho;C.S. Jun
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.7
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    • pp.49-58
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    • 1997
  • In process planning for pocket machining, the selection of tool size, tool path, overlap distance, and the calculation of machining time are very important factors to obtain the optimal process planning result. Among those factors, the tool size is the most important one because the others depend on tool size. And also, it is not easy to determine the optimal tool size even though the shape of pocket is simple. Therefore, the optimal selection of tool size is the most essential task in process planning for machining a pocket. This paper presents a method for selecting optimal toos in pocket machining. The branch and bound method is applied to select the optimal tools which minimize the machining time by using the range of feasible tools and the breadth-first search.

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NC Tool Paths Program Development for the Pocket Machining (포켓 가공을 위한 NC 공구경로의 프로그램 개발)

  • Oh, Seon;Kwon, Young-Woong
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.3
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    • pp.75-81
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    • 2003
  • Pocket machining is metal removal operation commonly used for creating depressions in machined parts. Numerically controlled milling is the primary means for machining complex die surface. These complex surfaces are generated by a milling cutter which removes material as it traces out pre-specified tool paths. To machine, a component on a CNC machine, part programs which define the cutting tool path are needed. This tool path is usually planned from CAD, and converted to a CAM machine input format. In this paper I proposed a new method for generating NC tool paths. This method generates automatically NC tool paths with dynamic elimination of machining errors in 2$\frac{1}{2}$ arbitrary shaped pockets. This paper generates a spiral-like tool path by dynamic computing optimal pocket of the pocket boundary contour based on the type and size of the milling cutter, the geometry of the pocket contour and surface finish tolerance requirements. This part programming system is PC based and simultaneously generates a G-code file.

A Partitioning Method Recucing the Number of Tool Retractions in Zigzag Pocket Machining (지그재그 포켓 가공에서 공구후퇴 횟수를 줄이기 위한 영역 분할법)

  • 서경천;김재정
    • Korean Journal of Computational Design and Engineering
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    • v.6 no.4
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    • pp.215-221
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    • 2001
  • In the zigzag milling of a pocket having islands, tool retraction is one of the primary factors that decrease productivity. Therefore, tool path with minimum number of tool retraction has been needed. Most researches about this topic have been concentrated on obtaining the optimum solution formulated through the geometric reasoning off pocket. Recently, several attempts were made to simplify this problem into region partitioning in order to get the numerically expressed minimum solution. In this research, a method reducing the number of tool retractions extended from existing region partitioning is provided. Applying the segment that is normal to the reference direction of zigzag milling, region partitioning is carried out and structural elements of the region are searched via graphs of islands and characteristic points. Through the processes presented, the number of region partitioned is less than that of existing processes.

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The minimum time pocketing cycle for the dialog workshop oriented programming (대화형 작업장 프로그래밍을 위한 최소 시간 포켓 가공 싸이클)

  • 류제석;강성균;전용주
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.848-851
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    • 1996
  • Based on the minimum cutting time criteria, the tool path generation algorithm of a pocket machining is developed as a form of a built-in cycle for the WOP(workshop oriented programming) of a CNC controller. Based on the given CAD database and tool information, an optimal cutting depth and geometric properties can be generated, then six different tool paths will be generated internally and automatically. Finally, the G code which commands tool movements is generated for CNC machining.

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A Study on the Cutting Forces and Tool Deformation when Flat-ended Pocket Machining (평엔드밀 포켓가공시 절삭력과 공구변형에 관한 연구)

  • Choi, Sung-Yun;Kwon, Dae-Gyu;Park, In-Su;Wang, Duck-Hyun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.2
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    • pp.28-33
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    • 2017
  • Recently, the operation of precision pocket machining has been studied for the high speed and accuracy in industry to increase production and quality. Moreover, the demand for products with complex 3D free-curved surface shapes has increasing rapidly in the development of computer systems, CNC machining, and CAM software in various manufacturing fields, especially in automotive engineering. The type of aluminum (Al6061) that is widely used in aerospace fields was used in this study, and end-mill down cutting was conducted in fillet cutting at a corner with end-mill tools for various process conditions. The experimental results may demonstrate that the end mill cutter with four blades is more advantageous than that of the two blades on shape forming in the same condition precise machining conditions. It was also found that cutting forces and tool deformation increased as the cutting speed increased. When the tool was located at $45^{\circ}$ (four locations), the corner was found to conduct the maximum cutting force rather than the start point of the workpiece. The experimental research is expected to increase efficiency when the economical precision machining methods are required for various cutting conditions in industry.

Offsetting a Region Including Islands for Tool-Path Generation (공구 경로 생성을 위한 아일랜드를 포함하는 영역의 오프셋)

  • Park, Sang-Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.12
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    • pp.2009-2018
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    • 2001
  • This paper presents a region offsetting algorithm for tool-path generation. The proposed region offsetting algorithm is developed by expanding the 'PWID offset algorithm [Choi and Park, 1999]'designed to offset a simple polygon. The PWID offset algorithm has three important steps; 1) remove 'local invalid ranges'by invoking a PWID test, 2) construct a raw offset owe and 3) remove 'global invalid ranges'by finding self-intersections of the raw offset cure. To develop a region offsetting algorithm, we modified the PWID offset algorithm by expanding the concept of the 'global invalid range'in the third step. The time complexity of the proposed algorithm is approximately Ο(n), where n is the number of points, and it is free of numerical errors for practical purposes. The proposed algorithm has been implemented and tested with various real regions obtained by intersecting a sculptured surface with a plane.

Cutting Force Prediction in NC Machining Using a ME Z-map Model (ME Z-map 모델을 이용한 NC 가공의 절삭력 예측)

  • 이한울;고정훈;조동우
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.86-89
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    • 2002
  • In NC machining, the ability to automatically generate an optimal process plan is an essential step toward achieving automation, higher productivity, and better accuracy. For this ability, a system that is capable of simulating the actual machining process has to be designed. In this paper, a milling process simulation system for the general NC machining was presented. The system needs first to accurately compute the cutting configuration. ME Z-map(Moving Edge node Z-map) was developed to reduce the entry/exit angle calculation error in cutting force prediction. It was shorn to drastically improve the conventional Z-map model. Experimental results applied to the pocket machining show the accuracy of the milling process simulation system.

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Manufacturing Feature Extraction for Sculptured Pocket Machining (Sculptured 포켓 가공을 위한 가공특징형상 추출)

  • 주재구;조현보
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.04a
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    • pp.455-459
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    • 1997
  • A methodology which supports the feature used from design to manufacturing for sculptured pocket is newly devlored and present. The information contents in a feature can be easily conveyed from one application to another in the manufacturing domain. However, the feature generated in one application may not be directly suitable for another whitout being modified with more information. Theobjective of the paper is to parsent the methodology of decomposing a bulky feature of sculptured pocket to be removed into compact features to be efficiently machined. In particular, the paper focuses on the two task: 1) to segment horizontally a bulky feature into intermediate features by determining the adequate depth of cut and cutter size and to generate the temporal precedence graph of the intermediate features and 2)to further decompose each intermediate feature vertical into smaller manufacturing features and to apply the variable feed rate to each small feature. The proposed method will provid better efficiency in machining time and cost than the classical method which uses a long string of NC codes necessary to remove a bulky fecture.

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