• 제목/요약/키워드: Dead Zone

검색결과 249건 처리시간 0.028초

유동제어에 의한 피스톤 핀의 전${\cdot}$후방압출 공정 개발 (Forward-Backward Extrusion Process Development of Piston-Pin by Flow Control)

  • 박종남;박태준;김병민
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2001년도 제4회 압출 및 인발가공 심포지엄
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    • pp.1-12
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    • 2001
  • In cold forging of piston-pin for automobile parts, the flow defect appears by the dead metal zone. This appearance evidently happens in products with a thin piercing thickness for the dimension accuracy and the decrease of material loss. The best method that can prevent flow defect is removing dead metal zone. The purpose of this study is to investigate the material flow behavior of forward-backward extruded piston-pin through the relative velocity ratio and the stroke control of upper moving punch & container using the flow control forming technique. The finite element simulations are applied to analyse the flow defect, then the results are compared with the plasticine model material experiments. Finally, the model experiment results are in good agreement with the FE simulation ones.

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반용융 재료의 물성치 평가에 관한 연구(I) -후방압출의 상계해석을 위한 동적 가용 속도장의 제안- (A Study on Material Characterization of Semi-Solid Materials (I) -Proposal of New Velocity Field for Upper Bound Analysis of Backward Extrusion-)

  • 이주영;김낙수
    • 소성∙가공
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    • 제8권4호
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    • pp.364-373
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    • 1999
  • For material characterization of semi-solid materials, backward extrusion process, which has been used in forming of hollow-sectioned products, was analyzed by the upper bound analysis in the current study. The existing kinematically admissible velocity field was applied to steady state at which there was no change in the assumed regions of velocity field. For unsteady state, new velocity field, as a function of dead zone angle, was proposed. Through the whole analysis, fiction between die and workpiece was also considered. It has been studied how the process variables, such as friction factor and punch velocity, and material parameters, such as strength coefficient, strain rate sensitivity could affect on analysis results. Finally, by the comparison with the finite element analysis, the reliability and efficiency of the proposed velocity field were discussed.

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사대종확산 모형에 의한 유출해석 (RUNOFF ANALYSIS BY DEAD ZONE LONGITUDINAL DISPERSION ANALOGY)

  • 윤용남;차영기
    • 물과 미래
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    • 제12권1호
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    • pp.56-59
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    • 1979
  • 직접유출 수문곡선의 감수부를 유발하는 지표하류출 과정이 사대종확산모형기법에 의하여 모의되었다. 유출과정은 필시곡선도에 의한 소유역을 대표하는 개급적 선형 수로를 통하여 상류선형수로의 유출과 핵심 소유역의 유효강우량을 추적하여 수행된다. 유출 속도, 확산인자, 침투와 지표하흐름 영역에 관한 매개변수의 산출과정이 기록된다.

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견비선형을 갖는 제어시스템에 대한 기준모델 피드백제어 및 안정성평가 (Reference Model Feedback Control and Stability Evaluation for Control System with Hard Non-linearities)

  • 정유철;이건복
    • 한국공작기계학회논문집
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    • 제15권5호
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    • pp.72-78
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    • 2006
  • The paper proposes reference model error feedback control scheme for motion control system with hard non-linear components as like saturation and dead-zone in plant input part. Additionally, the plant has the system uncertainty effected by plant model parameter deviation and disturbance. The control algorithm uses the reference model to apply additional feedback loop with the error between reference model output and actual output effected by disturbance and non-linear components. And the stability evaluation based on Popov stability and controller design method are formulated to be performed. The effectiveness of the proposed scheme is examined by simulations. The results are proven by reasonable performances following reference model responses with good disturbance rejection performance without over-tuning of controller.

탄성 변형 영역을 고려한 비정상 평면 변형 이상 공정 이론 (Nonsteady Plane-strain ideal forming with elastic dead zone)

  • 이원오;정관수
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2004년도 춘계학술대회 논문집
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    • pp.190-193
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    • 2004
  • Ever since the ideal forming theory has been developed fur process design purposes, application has been limited to sheet forming and, for bulk forming, to two-dimensional steady flow. Here, application for the non-steady case was performed under the plane-strain condition based on the theory previously developed. In the ideal flow, material elements deform following the minimum plastic work path (or mostly proportional true strain path) so that the ideal plane-strain flow can be effectively described using the two-dimensional orthogonal convective coordinate system. Besides kinematics, for a prescribed final part shape, schemes to optimize a preform shape out of a class of initial configurations and also to define the evolution of shapes and boundary tractions were developed. Discussions include the two problematic issues on internal tractions and the non-monotonous straining. For demonstration purposes, numerical calculations were made for a bulk part under forging.

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자동차용 피스톤 핀의 전.후방압출에서 유동제어에 관한 실험적 연구 (Experimental Investigation on the Flow Control in Forward-Backward Extrusion of Piston-Pin for Automobile)

  • 박종남;박태준;김동환;김병민
    • 대한기계학회논문집A
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    • 제26권7호
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    • pp.1366-1375
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    • 2002
  • In cold forging of piston-pin for automobile parts, the flow defect appears by the dead metal zone. This appearance evidently happens in products with a thin piercing thickness for the dimension accuracy and the decrease of material loss. The best method that can prevent flow defect is removing dead metal zone. The purpose of this study is to investigate the material flow behavior of forward-backward extruded piston-pin through the relative velocity ratio and the stroke control of upper moving punch & container using the flow control forming technique. The finite element simulations are applied to analyse the flow defect, then the results are compared with the plasticine model material experiments. The model experiment results are in good agreement with the FE simulation ones.

주파수역 성능을 고려한 유압 위치시스템의 강인 적응 제어 (Robust Adaptive Control of Hydraulic Positioning System Considering Frequency Domain Performance)

  • 김기범;김인수
    • 한국생산제조학회지
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    • 제23권2호
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    • pp.157-163
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    • 2014
  • In this paper, a robust MRAC (model reference adaptive control) scheme is applied to control an electrohydraulic positioning system under various loads. The inverse dead-zone compensator in the control system cancels out the dead-zone response, and an integrator added to the controller provides good position-tracking ability. LQG/LTR (linear quadratic Gaussian control with loop transfer recovery) closed-loop model is used as the reference model for learning the MRAC system. LQG/LTR provides a systematic technique to design the linear controller that optimizes the objective function using some compromise between the control effort and the system performance in the frequency domain. Different external load tests are performed to investigate the effectiveness of the designed MRAC system in real time. The experimental results show that the tracking performance of the proposed system is highly accurate, which offers considerable robustness even with a large change in the load.

Characteristics Analysis of Short Flux-path 4/3 SRM

  • Ahn, Jin-Woo
    • Journal of international Conference on Electrical Machines and Systems
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    • 제2권1호
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    • pp.40-44
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    • 2013
  • This paper presents a design and characteristics analysis of novel 2-phase 4/3 switched reluctance motor (SRM) with short flux path for an air-blower application. The desired air-blower is unidirectional application, and requires a wide positive torque region without torque dead-zone. In order to get a wide positive torque region without torque dead-zone during phase commutation, asymmetric inductance characteristic with non-uniform air-gap is considered. The proposed motor could be started at any rotor position with high efficiency drive. The proposed 2-phase 4/3 SRM is verified by finite element method analysis.

정현파형 브러시리스 직류전동기의 속도 제어를 위한 채터링 저감 특성을 갖는 가변구조 제어기 설계 (Design of a Variable Structure Controller having Chattering Alleviation Characteristics for the Speed Control of Sinusoidal type Brushless DC Motor)

  • 김세일;최중경;박승엽
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 1999년도 하계종합학술대회 논문집
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    • pp.805-808
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    • 1999
  • In this paper, a chattering alleviation ISM speed controller for the sinusoidal type BIDC motor is designed. Dead Zone function is proposed to change the chattering occurring in the transient state form high frequency to low frequency and time-varying gains are applied for the control input to eliminate the steady state excessive chattering in the conventional ISM. The proposed Dead Zone function represents the sliding layer composed of two switching surfaces and if a state vector exists in this layer, the chattering don’t occur. Simulation and experimental results confirm the useful effects of the above algorithm.

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개폐식 밸브를 사용한 공기압 서보 시스템의 효율적 밸브 개폐 방법에 관한 연구 (Study on the Effective Operating Method of on-off Valves for a Pneumatic Servo System)

  • 황웅태;최서호;이정오
    • 한국정밀공학회지
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    • 제15권1호
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    • pp.109-116
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    • 1998
  • This paper is concerned with effective operating method of pneumatic on-off valves for improving position control accuracy, valve life-time and position settling time using modified pulse width modulation with dead-zone (MPWMD). The pneumatic system using on-off valves has advantage of simple construction and low cost compared with a system with servo-valves. The performance of the proposed control method is investigated experimentally for the position control of a pneumatic cylinder using on-off valves. Experimental results show that the proposed algorithm for valve operation can be used to obtain fast and accurate position control compared to the conventional PWMD algorithm. It is also shown that the use of the proposed MPWMD algorithm for the position control significantly reduces the number of valve switching and noise.

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