• Title/Summary/Keyword: NC Machining

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Optimal Tool Positions in 5-axis NC Machining of Sculptured Surface (복합곡면의 5축 NC 가공을 위한 공구자세 최척화)

  • 전차수;차경덕
    • Korean Journal of Computational Design and Engineering
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    • v.5 no.4
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    • pp.393-402
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    • 2000
  • Recently 5-axis NC machines are widely used in Korea. Since 5-axis machines have two more degrees of freedom than 3-axis machines, it is very important to find desirable tool positions(locations and orientations) in order to make an efficient use of expensive 5-axis NC machines. In this research an algorithm to determine “optimal” tool positions for 5-axis machining of sculptured surfaces is developed. For given CC(Cutter Contact) points, this algorithm determines the cutter axis vectors which minimize cusp heights and satisfy constraints. To solve the optimal problem, we deal with following major issues: (1) an approximation method of a cusp height as a measure of optimality (2) Identifying some properties of the optimal problem (3) a search method for the optimal points using the properties. By using a polyhedral model as a machining surface, this algorithm applies to sculptured surfaces covering: overhanged surface.

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Calculation of Intersection between Z-map Vectors and Circularly Moving Filleted-end Mills (원호운동 필렛 엔드밀과 Z-맵 벡터의 교점 계산)

  • 맹승렬;백낙훈;신성용;최병규
    • Korean Journal of Computational Design and Engineering
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    • v.8 no.4
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    • pp.278-288
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    • 2003
  • Presented in this paper is a numerical method for calculating the intersection points between Z-map vectors and the tool swept surface for circularly moving filleted-end mills. In numerically controlled(NC) machining simulation for large moulds and dies, a workpiece is frequently approximated as a set of z-axis aligned vectors, called Z-map vectors, and then the machining processes can be simulated through updating the Z-map with the intersection points. Circular motions are typically used for machining the free-form surfaces. For fast computation, we express each of intersection points with a single-variable non-linear equation and calculate the candidate interval in which the unique solution exists. Then, we prove the existence of a solution and its uniqueness in this candidate interval. Based on these properties, we can effectively apply numerical methods to finally calculate the solution of the nonlinear equation within a given precision. Experimental results are given for the case of a TV monitor and the hood of a car.

자유곡면 5축 NC가공에 있어서의 최적 CL data산출

  • 최병규;박정환;김화영
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 1991.10a
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    • pp.124-130
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    • 1991
  • 5-axis NC machining of sculptured surface using non-ballendmill cutters (eg. facemilling cutters) is widely used in the machining of turbine blades and marine propellers. Since there are more degrees of freedom in 5-axis machining than in 3-axis machining, generating "optimum" cutter paths and finding desirable cutter positions become very important in order for an efficient use of 5-axis NC machines. Also critical in 5-axis NC machining are collision avoidance, gouging checking, and efficient kinematic solutions. In this paper we discuss the above issues in generating 5-axis CL data. They are : kinematics modeling of NC machine; inverse kinematics solution; interference between machine component and surface; cutter gouging. A unique search method for obtaining optimal CL data is proposed. The proposed method has been successfully implemented in the machining of marine propellers on a dual 5-axis (ie, 9-axis) NC machine.C machine.

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Automated initial process planning system for three-axis NC machining of sculptured surfaces (자유 곡면의 3축 NC 가공을 위한 초기 공정 계획 기능의 자동화)

  • J.K. Kang
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.3
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    • pp.114-121
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    • 1997
  • In this paper, the automated initial process planning for 3-axis NC machining of sculptured surfaces is persented. The solution algorithms determining three process planning functions, i.e. machining feasibility, setup orientation and feasible machine selection are developed. The machining feasibility is determined by means of BSM(Binary Spherical Map) which derives its solution quickly in algebraic form, and the setup orientation is determined so that the cutting force is minimized. Finally, the feasible machine is determined by computing the minimum motion ranges of each control axisl. The developed algorithms are tested by numerical simulations, convincing they can by readily implemented on the CAD/CAM system as a process planner.

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A study on the system integration for NC machining (NC 기계 가공에서의 시스템 통합화 연구)

  • 강용근;김기엽
    • 제어로봇시스템학회:학술대회논문집
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    • 1990.10a
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    • pp.167-169
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    • 1990
  • This paper describes the DNC technology as a partial approach to a achieving dr system integration of NC machines. The study deals with development of a system to unify NC machines by utilizing a DNC. The system is provided to have the potential of offering ft environment and application fundamentals to construct factory automation.

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A Z-map Update Method for Linearly Moving tools (직선 운동하는 공구에 대한 Z-맵의 갱신 방법)

  • 맹승렬;백낙훈;신성용;최병규
    • Korean Journal of Computational Design and Engineering
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    • v.7 no.4
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    • pp.219-232
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    • 2002
  • In numerically controlled(NC) machining simulation, a Z-map has been used frequently for representing a workpiece. Since the Z-map is usually represented by a set of Z-axis aligned vectors, the machining process can be simulated through calculating the intersection points between the vectors and the surface swept by a machining tool. In this paper, we present an efficient method to calculate those intersection points when an APT-type tool moves along a linear tool path. Each of the intersection points can be expressed as the solution of a system of non-linear equations. We transform this system of equations into a single-variable equation, and calculate the candidate interval in which the unique solution exists. We prove the existence of a solution and its uniqueness in this candidate interval. Based on these characteristics, we can effectively apply numerical methods to finally calculate the solution of the non-linear equations within a given precision. The whole process of NC simulation can be achieved by updating the Z-map properly. Our method can provide more accurate results with a little more processing time, in comparison with the previous closed-form solution.

An approach for machining allowance optimization of complex parts with integrated structure

  • Zhang, Ying;Zhang, Dinghua;Wu, Baohai
    • Journal of Computational Design and Engineering
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    • v.2 no.4
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    • pp.248-252
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    • 2015
  • Currently composite manufacturing process, such as linear friction welding plus NC machining, is the main method for the manufacturing and repairing of complex parts with integrated structure. Due to different datum position and inevitable distortion from different processes, it is important to ensure sufficient machining allowance for complex parts during the NC machining process. In this paper, a workpiece localization approach for machining allowance optimization of complex parts based on CMM inspection is developed. This technique concerns an alignment process to ensure sufficient stock allowance for the single parts as well as the whole integrated parts. The mathematical model of the constrained alignment is firstly established, and then the symmetric block solution strategy is proposed to solve the optimization model. Experiment result shows that the approach is appropriate and feasible to distribute the machining allowance for the single and whole parts for adaptive machining of complex parts.

Effect of Cusp on the Cutting Characteristics and Tool Wear of Semi-finishing in Ball End Milling (볼엔드밀 중삭가공시 커습에 의한 절삭특성과 공구마모)

  • Cho, Chul-Yong;Mun, Sang-Don;Ryu, Shi-Hyoung
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.5
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    • pp.79-84
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    • 2006
  • In modem manufacturing, many products that have geometrically complicated features, including three-dimensional sculptured surfaces, are designed and produced. In the production of these complex-shaped mechanical components, e.g. automobile dies, molds, and various engineering applications, the ball-end milling process is one of the most widely used NC machining processes that consists of roughing, semi-finishing and finishing. In semi-finishing, cusps remained after roughing according to the used tools that have two patterns of stairs and wave shapes. These cusp shapes have air-cut in cutting and instability caused by high cutting speed that affects the cutting characteristics such as cutting force and tool wear. Cutting characteristics are measured and analyzed through cutting force, FFT analysis of cutting force and tool wear along cutting length according to low tool paths with same metal removal rate. As a results of the experiments, this study suggests the optimal conditions of tool path and cutting direction. This approach for the cutting characteristics of semi-finishing provides a useful aid for the productivity and efficiency improvements of NC machining processes.