Browsing by Author "CHIN, JH"

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A PATH ALGORITHM FOR ROBOTIC MACHINING
(1993-06-01)
CHIN, JH
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TSAI, HC
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機械工程學系
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Department of Mechanical Engineering
A path tracking algorithm for robotic continuous path machining is presented in this paper. The concept is to preadapt the path parameters before path tracking. The path concept itself arises from CNC machines so that a continuous path to be tracked/machined is built up from basic path types such as straight line, circular arc and parabola. Exact curve equations are used as tracking bases and a velocity correction which is created from the actual position error is added to the original desired path velocity. So a kind of cascaded path rate control and computed torque tracking is possible to produce a precise continuous path. An adaptive control is also proposed to support the path regulation with a tracking and an adaptation law. Simulation shows that the proposed algorithms yield better path precision than the pure computed torque method in three-dimensional path tracking/machining. And adaptive path regulation yields even better results.
A STUDY OF STICK SLIP MOTION AND ITS INFLUENCE ON THE CUTTING PROCESS
(1993-05-01)
CHIN, JH
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CHEN, CC
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交大名義發表
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機械工程學系
;
National Chiao Tung University
The stick slip motion of a machine tool has been investigated on the basis of a complete kinematic and kinetic model. The model is a generalized description of stick-slip motion of the machine tool which governs the whole cyclic process of this phenomenon and not just its slipping mode. Using this method some dynamic characteristics of this motion have been clarified. Further, an extended theory for chip-formation dynamics has been suggested to include the variation of feed. The effect of stick-slip motion has been introduced to examine the influence of this variation. Finally an identification technique has been presented to determine the stick-slip parameters of the model.
A STUDY ON THE TOOL EIGENPROPERTIES OF A BTA DEEP HOLE DRILL - THEORY AND EXPERIMENTS
(1995-01-01)
CHIN, JH
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LEE, LW
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交大名義發表
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機械工程學系
;
National Chiao Tung University
The dynamics of a tool shaft are usually simplified to that of a second order lumped mass system for cutting process. This approach does not apply for deep hole drilling because of its extraordinary shaft length. This paper established the equations for lateral and longitudinal shaft motion of a BTA drill based on the Euler beam theory. Free-free boundary conditions are used in order to solve the eigenproperties of the shaft. Experiments to determine properties of the shaft, the shaft with internal static fluid and the shaft with cutting head were performed. The agreements between the theoretical and experimental natural frequencies and mode shapes confirmed the proposed equations. Some effects, including those of static fluid and the cutting head were clarified. This study has shown the existence and importance of the BTA tool shaft dynamics which were often overlooked or oversimplified in the past.
ANALYSIS OF AN ELECTROHYDRAULIC SERVO SYSTEM SUBJECT TO STRIBECK-TYPE FRICTION
(1994-06-01)
CHIN, JH
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FU, WC
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
The main objective of this paper is to study the phenomena of the electrohydraulic servo system under the influence of the Stribeck-type friction. Owing to the nonlinear nature of this friction, a sustained oscillation, or limit cycle, might appear in the system behaviour. The system is first divided into two parts, the linear and the nonlinear. For the nonlinear Stribeck-type friction, a flexible model is proposed to represent the whole friction family, and the describing function of this nonlinear friction is generated. The system characteristic equation is established by correlating the frequency response of the linear part and the describing function of the nonlinear part. The existence and stability of the limit cycle are predicted based on the characteristic equation. Finally, by using the sinusoidal, step and ramp input, respectively, the numerical simulation is adopted to observe the system response. All predicted limit cycles can be verified by the simulation results, and the effects of stable and unstable limit cycles are clarified. The dynamic characteristics obtained in this study help to bring insight into this important engineering configuration and throw some light on the possibilities for improvement.
MATHEMATICAL-MODELS AND EXPERIMENTS FOR CHIP SIGNALS OF SINGLE-EDGE DEEP HOLE DRILLING
(1993-06-01)
CHIN, JH
;
WU, JS
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
Deep hole drilling is applied to holes with depth-diameter ratio larger than 10. The most important prerequisite is the removal of chips because one of the critical problems is chip congestion. This paper presents two models depicting pressure signals that reflect the state of chips. The first model (I), starting from the two-phase slug flow viewpoint, establishes the relationship between the pressure signal and length of the chip. The second model (II), built by considering the fluid force momentum and continuity equation for a control volume, relates the pressure signal with the chip length and radius. The COMputer simulation shows that model I is in good agreement with results from a real cutting process. Experiments conducted in this work also confirms the validity of model II. The proposed models establish fundamental knowledge for the problem of chip state monitoring for deep hole drilling.
STRUCTURAL DESIGN UNDER MULTIOPTIMAL CONSIDERATION
(1994-11-17)
CHIN, JH
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TSENG, GT
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交大名義發表
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機械工程學系
;
National Chiao Tung University
The purpose of this study is to propose a concept which takes both the total weight and the response of a structure into consideration and the critical point is applied to search the equivalent minimum value for the optimization problem. It also used the criteria for the decomposition of the system. By these criteria, optimal design could be performed for any typical structure without having recourse to the entire system. An efficient calculation has been established for a system in an optimal design process.
THE COMPUTER-SIMULATION AND EXPERIMENTAL-ANALYSIS OF CHIP MONITORING FOR DEEP HOLE DRILLING
(1993-05-01)
CHIN, JH
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WU, JS
;
YOUNG, RS
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交大名義發表
;
機械工程學系
Chip congestion is a long time bottleneck in deep hole drilling. This paper addresses the problem of chip state monitoring in single-edge deep hole drilling by computer simulation and experimental analysis. Two phenomenological models were proposed to interpret the physics of chip discharging in normal and congested states, respectively. Length and diameter of the chip are chosen to represent the geometric features of the chip, and the formation of a chip signal is discussed. Based on the two models different types of chips are used to simulate the monitoring process. Computer simulation shows that the normal chip discharging in a real drilling process can be interpreted by the proposed slug flow model. Also, the experiments with cylindrical form chips confirms model II proposed for a congested chip state in which the diametral effect develops due to chip congestion. The experimental analyses also find out the dependence of pressure signals on the various parameters of chips as well as the cutting process.