• Title/Summary/Keyword: Workpiece Vibration

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A Study on the Grinding Trouble-Shooting Utilizing the Neural Network (Neural Network을 응용한 연삭가공 트러블 인식.처리에 관한 연구)

  • 하만경;김건희;곽재삼;송지복;이재경;김희술
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.04b
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    • pp.113-117
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    • 1995
  • Grinding operations is accomplished by rotating a gfinding wheel with lots of random abrasive at high speed, and its object is generally obtained the fanal workpiece surface of high quality as well as the maximization of workpiece removal rate. But, especiallysince grinding operations is related with a large amount of functional parameter, it is actually difficult to therapy that the grinding trouble occurs during the grinding process. Therefore, we trytodesign grinding trouble-shooting system utilizing the back-propagation model of neural network. The conceptual method is produced byidentifying the four parameters derived from the grinding power, and we are design te to the grinding trouble-shooting system on the basis of their data. In this paper, cognition and therapy method tothe grinding trouble which utilizes neural network based four identified models are suggested, and implementation results of computer simulation with respect to the grinding burn and chatter vibration is presented.

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Analysis of Characteristic Evaluation of Microdrilling for the Cemented Carbides Materials (초경합금 소재 마이크로드릴의 가공특성 평가)

  • 김건회
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.6
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    • pp.52-59
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    • 2002
  • Resently, reduction of industrial products in size and weight has increased by the application of micro-drill for gadgets of high precision and gave rise to a great interest in a micro-drilling. Due to the lack of tool stiffness and the chip packing, micro-drilling requires not only the robust tool structure which has not affected by the vibration, but also the effective drilling methods designed to prevent tool fracture from cutting troubles. Firstly, this paper presents a optimum characteristic evaluation method of 0.15mm microdrill in consideration of new manufacturing processes for improving the product rate and extend the tool life, and secondly suggest between microdrilling characteristic properties of tool md evaluation of workpiece quality through experiment.

Characteristics of Micro-Machining Using Two-Dimensional Tool Vibration

  • Ahn, Jung-Hwan;Lim, Han-Seok;Son, Seong-Min
    • International Journal of Precision Engineering and Manufacturing
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    • v.2 no.3
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    • pp.41-46
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    • 2001
  • This paper discusses the feasibility of improving micro-machining accuracy by using two-dimensional(2-D) vibration cutting. Vibration cutting is generated by two piezo actuators arranged orthogonally : one is actuated by a sine curve voltage input, and the other is actuated by a phase-shifted sine curve voltage. A tool attached to the vibrator oscillates in a 2-D elliptical motion, depending on the frequencies, amplitudes, and the phase shifts of two input signals and the workpiece feedrate. Along the elliptical tool locus, cutting is done in the lower part, and non-cutting is done in the upper part. By this way a unique feature of 2-D vibration cutting, that is, air lubrication between a tool and chips, is caused. Another unique feature of 2-D vibration cutting was experimentally verified, that is, some negative thrust force occurs as the direction of chip movement on a tool rake face is reversed. Those features not only help chips flow smoothly and continuously but also reduce cutting force, which results in a higher quality machined surface. Through tool path simulations and experiments under several micro-machining conditions, the 2-D vibration cutting, compared to conventional cutting, was found to result in a great decrease in the cutting force, a much smoother surface, and much less burr.

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Micro drilling of multi-layer PCB with the use of ultrasonic vibration (초음파진동을 이용한 다층 PCB 기판의 마이크로 드릴링)

  • 장성훈;이선규;원종률;이석우;최헌종
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1853-1856
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    • 2003
  • Multi-layer printed circuit board(PCB) is being used widely for the product with relatively complex circuits such as TV, VTR and FAX. With the rapid enlargement of electronic and IT industry, the hole machining technology on multi-layer PCB is increasingly required to improve. Thus, the micro drilling with ultrasonic vibration can be a good method for hole machining. Unlike conventional drilling, ultrasonic vibration applied drilling introduces less wear and fracture of not only tool but also internal surface of workpiece due to little cutting resistance, thus, machinability can be improved. The experiment is conducted through the comparison between the results of conventional drilling and ultrasonic micro drilling as well as among each results by the variation according to not only feed rate of drill but also amplitude and frequency of ultrasonic vibration. The multi-layer PCB consists of 6 layers and ${\Phi}$0.3 diameter drill was used. As a result, it was found that the state of internal surfaces of holes on multiple layer PCBs is improved by the application of ultrasonic vibration.

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Design of High frequency Vibration Mechanism with PZT actuator for Ultraprecision Laser Machining (압전구동기를 이용한 초정밀레이저 가공의 고주파진동 장치설계)

  • Kim, Hyun-Uk;Hwang, Dong-Hyun;Park, Jong-Kweon;Cho, Sung-Hak;Lee, Moon-G.
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.19 no.3
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    • pp.419-425
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    • 2010
  • To machine the micro hole, laser machining system is widely used, however, the system cannot fabricate the micro hole with high aspect ratio and good surface finish. To break the obstacles, the high frequency vibration mechanism with PZT (Piezoelectric Transducers) is proposed in this paper. The mechanism will vibrate the laser beam in vertical direction so that the aspect ratio and surface finish may be higher than the conventional. The mechanism vibrates the eyepiece of laser optics. In addition to the benefits, the mechanism enables us to have high precision and flexibility. It decreases burr and debris during machining. And it is able to machine various materials of workpiece. This research include high frequency and large travel range of the proposed mechanism. The PZT motion of mechanism and analysis on the sensitivity of design parameters are extracted from a finite element method (FEM) simulation. In the analysis, the target vibration mode without parasitic motion is designated to have the target frequency and high amplitude.

Micro Milling using High Frequency 2-dimensional Vibration (2차원 고주파 진동을 이용한 미세 밀링가공)

  • Kim, Gi Dae
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.9 no.6
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    • pp.66-70
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    • 2010
  • Using two piezoelectric materials orthogonally arranged, 2-dimensional(2D) vibration in a excitation workpiece table was generated. In this study, micro milling using high frequency 2D vibration was proposed, whose locus of cutting tool is combined with original trochoid locus of milling tool and 2D elliptical locus of excitation table. From the cutting results of 2D vibrational micro milling of nickel alloy, it was observed that the machining quality and the roughness of machined surface were enhanced compared to conventional milling in a side cutting whose immersion ration is relatively low, whereas there was little betterment in a slot cutting.

자동회귀-이동평균(ARMA) 모델에의한 초음파 진동 절삭 공정의 해석

  • 최인휴;김정두
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1993.04b
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    • pp.160-165
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    • 1993
  • The cutting mechanism of ultrasonic vibration machining is characterized as two phases, that is an impact at the cutting edge and a reduction of cutting force due to non-contact interval between tool and workpiece. In this paper, in order to identfy cutting dynamics of a system with ultrasonically vibrated cutting tool, an ARMA modelling is performed on experimental cutting force signals which have a dominant effect on cutting dynamics. The aim of this study is, through Dynamic Data System methodology, to find the inherent characteristics of an ultrasonic vibration cutting process by considering natural frequencyand damping coefficient. Surface roughness and stability of cutting process under ultrasonic vibration are also considered

The Study of Precision measurement by the 3-Point Method (3점식 정도측정에 관한 연구)

  • 전승윤;이영진;정영일;배종일;이만형
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.05a
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    • pp.607-612
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    • 2000
  • Roundness measurement method using three displacement sensors makes in-process roundness measurement possible on the NC machine because it eliminates the vibration signal and eccentricity signal from measured roundness signal from the workpiece. But if measured signals contain noises, high precision measurement of the roundness isn't possible. In this study, a high precision in-process roundness measurement system is developed, which applies a Kalman filter to the roundness measurement method using three displacement sensors and can be used to measure vibration of the spindle.

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Analysis on the Vibration Characteristics of Ultra Precision Machine Tools (초정밀 가공 기계의 진동 특성 해석)

  • Kim, Seong Geol;Park, Young Ii;Kim, Seock Hyun
    • Journal of Industrial Technology
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    • v.14
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    • pp.119-125
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    • 1994
  • Ultra-precision machine tool equipped with the diamond bite tip is used to machine optical products, drums of VTR or computer hard disk. It needs nano technology in the surface roughness of workpiece. To perform the nano scale machining, ultra-precision machine tool must be designed and manufactured in consideration of the vibration characteristics. In this paper, using the finite element analysis, we investigate the modal parameters of the ultra-precision machine tool structures, which use cast iron, granite and alumina ceramic for the bed materials. To verify the numerical results, we manufacture a model of ultra-precision machine tool using granite bed and perform impulse test. Through the theoretical and experimental analyses, we could compare and estimate the vibration characteristics of the three models for the ultra-precision machine tools.

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A study on the characteristics of acoustic emission signal in dynamic cutting process (동적 절삭과정에서 AE 신호의 특성에 관한 연구)

  • Kim, Jeong-Suk;Kang, Myeong-Chang;Kim, Duk-Whan
    • Journal of the Korean Society for Precision Engineering
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    • v.11 no.4
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    • pp.69-76
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    • 1994
  • AE(Acoustic Emission) signal is correlated to workpiece material, cutting conditions and tool geometry during metal cutting. The relationship between AE signal and cutting parameters can be obtained by theoretical model and experiments. The value of CR(Count Rate) is nearly constant in stable cutting, but when the chatter vibration occours, the value of CR is rapidly increased due to the vibration deformation zone. By experimental signal processing of AE, it is more effective than by RMS(Root Mean Square) measurement to detect the threshold of chatter vibration by CR measurement.

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