• Title/Summary/Keyword: High Speed Machining Center

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A chord error conforming tool path B-spline fitting method for NC machining based on energy minimization and LSPIA

  • He, Shanshan;Ou, Daojiang;Yan, Changya;Lee, Chen-Han
    • Journal of Computational Design and Engineering
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    • v.2 no.4
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    • pp.218-232
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    • 2015
  • Piecewise linear (G01-based) tool paths generated by CAM systems lack $G_1$ and $G_2$ continuity. The discontinuity causes vibration and unnecessary hesitation during machining. To ensure efficient high-speed machining, a method to improve the continuity of the tool paths is required, such as B-spline fitting that approximates G01 paths with B-spline curves. Conventional B-spline fitting approaches cannot be directly used for tool path B-spline fitting, because they have shortages such as numerical instability, lack of chord error constraint, and lack of assurance of a usable result. Progressive and Iterative Approximation for Least Squares (LSPIA) is an efficient method for data fitting that solves the numerical instability problem. However, it does not consider chord errors and needs more work to ensure ironclad results for commercial applications. In this paper, we use LSPIA method incorporating Energy term (ELSPIA) to avoid the numerical instability, and lower chord errors by using stretching energy term. We implement several algorithm improvements, including (1) an improved technique for initial control point determination over Dominant Point Method, (2) an algorithm that updates foot point parameters as needed, (3) analysis of the degrees of freedom of control points to insert new control points only when needed, (4) chord error refinement using a similar ELSPIA method with the above enhancements. The proposed approach can generate a shape-preserving B-spline curve. Experiments with data analysis and machining tests are presented for verification of quality and efficiency. Comparisons with other known solutions are included to evaluate the worthiness of the proposed solution.

Analysis of Cutting Parameters for $Si_3 N_4$-hBN Machinable Ceramics Using Tungsten Carbide Tool (초경공구를 사용한 $Si_3 N_4$-hBN 머시너블 세라믹 가공에서 절삭 파라미터 분석과 결정)

  • 장성민;조명우;조원승;박동삼
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.12 no.6
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    • pp.36-43
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    • 2003
  • In machining of ceramic materials, they are very difficult-to cut materials because of there high strength and hardness. Machining of ceramics are characterized by cracking and brittle fracture. Generally, ceramics are machined using conventional method such as finding and polishing. However these processes are generally costly and have low MRR(material removal rate). This paper focuses on determining the optimal levels of process parameters for products with CNC machining center. For this purpose, the optimization of cutting parameters is performed based on experimental design method. A design and analysis of experiments is conducted to study the effects of these parameters on the surface roughness by using the S/N ratio, analysis of ANOVA and F-test. Cutting parameters, namely, cutting speed, feed and depth of cut are optimized with consideration of the surface roughness.

Cutting Force Regulation in Milling Process Using Sliding Mode Control (슬라이딩 모드 제어기를 이용한 밀링공정의 절삭력 제어)

  • Lee, Sang-Jo;Lee, Yong-Seok;Go, Jeong-Han
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.25 no.8
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    • pp.1173-1182
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    • 2001
  • Recent noticeable advances of CNC machine tools have considerably improved productivity and precision in manufacturing processes. However, in the respect of productivity some defects still remain because selection of machining conditions entirely depends on the experiences of programmers. Usually, machining conditions such as feed rate and spindle speed have been selected conservatively by considering the worst cases, and it has brought the loss of machining efficiency. Thus, the improvement of cutting force controller has been done to regulate cutting force constantly and to maximize feedrate simultaneously in case that machining conditions change variously. In this study, sliding mode control with boundary layer is applied to milling process for cutting force regulation and in a commercial CNC machining center data transfer between PC and PMC (programmable machine controller) of CNC machine is done using a standard interface method. And in the cutting force measurement, an indirect cutting force measuring system using current signal of AC servo is adopted in order not to use high-priced equipment like tool dynamometer. The purpose of this study is to maximize the productivity in milling process, thus its results can be applied to cases such as rough cutting process.

A Study of th stick-slip by feed of the machining center (공작기계 이송시 스틱슬립에 관한 고찰)

  • 정성택;박종남;조규재
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.420-424
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    • 1997
  • n the ballscrew slide system the ~najor problems in accomplishing the high-speed and high-precision are the friction between elements and the decrease of axial stiffness. Especially the friction on the guide have a bad effect on the precision of slidlng. Furthermore stick-slip occur when the low stiffness of slide system. The sticli-slip have a bad influence on the precision. In this research, the affection of stick-slip friction to the precision of the slide system is studied and the possible solution of the precision is proixjsed.

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A Study on Evaluation of an Automatic Tool Compensation System in CNC Machine Tool (CNC 공작기계에서의 자동공구 보정시스템의 평가에 관한 연구)

  • 정상화;신현성;김현욱
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.04a
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    • pp.371-375
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    • 2001
  • The tool wear that is developed by long-term machining in mold manufacturing with machining center makes a severe influence to the accuracy and the surface roughness. In this reason, tool-wear supervising system which has guaranteed high accuracy and high speed is needed to improve the measurement quality. Touching probe and touch sensor are widely used to measure the tool profile at on-machine measurement. In this paper, using the newly developed electric touch point measuring system, the Automatic Tool Compensation System is developed to correct the error of tool diameter resulted from the wear, and the operating method of this system is also provided.

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Development of an Automatic Tool Compensation System for M/C (머시닝센터용 자동공구보정시스템의 개발)

  • 정상화;신현성;김현욱
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.10 no.4
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    • pp.48-54
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    • 2001
  • The tool wear that is developed by long-term machining in mold manufacturing with machining center makes a severe influence to the accuracy and the surface roughness. in this reason, tool-wear supervising system which has guaranteed high accuracy and high speed is needed to improve the measurement quality. Touching probe and touch sensor are widely used to measure the tool profile at on-machine measurement. In this paper, using the newly developed electric touch point measuring system, the Automatic Tool Compensation System is developed to correct the error of tool diameter resulted from the wear, and the operating method of this system is also provided.

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A Study on Measurement for Endmill Dia. using Electric Contact Method (공구마모보정을 위한 전기접점식 자동공구 보정시스템 개발)

  • 정상화;신형성;나윤철
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.445-449
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    • 2001
  • The tool wear that is developed by long-term machining in mold manufacturing with machining center makes a severe influence to the accuracy and the surface roughness. In this reason, tool-wear supervising system which has guaranteed high accuracy and high speed is needed to improve the measurement quality. Touching probe and touch sensor are widely used to measure the tool profile at on-machine measurement. In this paper, using the newly developed electric touch point measuring system, the Automatic Tool Compensation System is developed to correct the error of tool diameter resulted from the wear, and the operating method of this system is also provided.

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Thermal Characteristics Analysis of a High-Speed HMC Spindle System (초고속 HMC 주축계의 열특성 해석)

  • 김석일;김기상;김기태;나승표
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.04a
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    • pp.441-446
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    • 2001
  • This paper presents the thermal characteristics analysis of a high-speed HMC spindle system with angular contact ball bearings, built-in motor, oil-jet lubrication method, oil jacket cooling method, and so on. The spindle system is composed of the main spindle and sub-spindle which are mechanically connected by a flexible coupling. The spindles are supported by two front and rear bearings, and the built-in motor is located between the front and rear bearings of the sub-spindle. The thermal analysis model of spindle system is constructed by the finite element method, and the thermal characteristics in the design stage are estimated based on temperature distribution and heat flow under the various testing conditions related to material of bearing ball, spindle speed and coolant temperature.

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Application of Linear Motor for the High-Speed Feed System of Machine Tools (초고속 이송 장치로서 리니어 모터의 적용 연구)

  • 신흥철;최종률
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.621-625
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    • 1996
  • The feed system of the machine tools is limited by the mechanical transmission elements. However, thanks to the advanced modern technology, those machines are able to equip with linear motors. In this paper, the types and application aspects of linear motor are discussed and a synchronous type of the linear motors has been applied to X-Y table for machining center. The performance shows an outstanding result in terms of the accuracy, speed and stiffness. Machine tool system with linear motors is expected to be more productive machines using linear motor in the near next years.

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Development of Array-Lens for Multi-Color Chip-LED (Multi-Color Chip-LED용 어레이 렌즈 개발에 관한 연구)

  • Choi, Byung-Ky;Lee, Dong-Gil;Jang, Kyeung-Cheun
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.16 no.3
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    • pp.50-55
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    • 2007
  • The purpose of this research is to enhance the luminance of the LED and to improve the implementation of color by mounting an array lens on the LED without special technology in process. The workmanship of key components considering the economical efficiency and the injection molding technology for high quality of the product are essential to achieve it. In this paper, the mold was computer-aided was designed and manufactured by CAM software (NX4) and high speed machining center. the applied final machining conditions were 3,000-5,000mm/min feed speed, 15,000-25,000rpm and ${\Phi}0.3mm$ ball end-mill. And the Flow analysis was performed using the mold flow software(MPI) in order to get uniformity of resin. Injection conditions acquired by the flow analysis and the injection experiment are as follows. The cylinder temperature is $220-260^{\circ}C$, the mold temperature is $70-80^{\circ}C$, the injection time is about 1.2sec, the injection pressure and velocity is each 7.8-14.7Mpa, and the injection velocity is 0.8-1.2m/sec.