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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Precision Engineering
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Journal DOI :
Korean Society of Precision Engineering
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Volume & Issues
Volume 13, Issue 12 - Dec 1996
Volume 13, Issue 11 - Nov 1996
Volume 13, Issue 10 - Oct 1996
Volume 13, Issue 9 - Sep 1996
Volume 13, Issue 8 - Aug 1996
Volume 13, Issue 7 - Jul 1996
Volume 13, Issue 5 - May 1996
Volume 13, Issue 4 - Apr 1996
Volume 13, Issue 3 - Mar 1996
Volume 13, Issue 1 - Jan 1996
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Machine Tool Technology; The Present and the Future(18)
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 13~30
Identification of Tool Breakage Signal Using Wavelet Transform of Feed Motor Current in Milling Operations
Park, H.Y. ; Kim, S.H. ; Lee, M.H. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 31~37
This Paper is concerned with effective signal identification method for tool breakage and micro chipping using discrete wavelet transform of feed motor current in milling operations. The wavelet transform uses an analyzing waveletfunction which is localized in both frequency and time domain to detect subtle time localized changes in input signals. The changing pattern of wavelet coefficient is continuously compared to detect tool breakage and micro chipping over one spindle revolution. The results indicate that the wavelet transform can identify tool failure with much greater sensi- tivity than the time domain monitoring and frequency domain monitoring such as FFT. Experimental results are presented to support the proposed scheme.
A Study on the Measurement of the 3-D Object Shapes by Using Optical Ring Method
Y.J. Kang ; Park, J.H. ; Kim, D.W. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 38~45
The optical triangulation method has been used as a non-contact measuring method of three dimensional object whape. But this measuring method has narrow measuring range, non-linearity on steep slope surface and shadow effect. In this study, we discussed a new optical measurement method to overcome these kinds of demerits. The advantage of this new method is that it is possible to measure precisely the object shape having the steep slope surface without shadow effect. As exper- imental results, maximum displacement error was 200 .mu. m over the whole measuring when the incident angle on the object surface was within 60 degree.
An Automated Process Planning System for Blanking of Stator and Rotor Parts and Irregularly-Shaped Sheet Metal Products
Park, J.C. ; Kim, B.M. ; Kim, J.H. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 46~53
This paper describes some research works of computer-aided design of blanking and piercing for stator and rotor parts and irregularly shaped sheet metal by press. An approach to the system is based on knowledge based rules. The process planning system by considering a blank layout for nesting of irregularly shaped sheet metal and an improved strip layout for stator and rotor parts and irregularly shaped sheet metal is implemented. Using this system, design parameters(utilization ratio, slitting width, pitch, working order, die blank shapes) are determined and output is generated in graphic forms. Knowledges for blank layout and strip layout are extracted from the plasticity theories, handbooks, relevant references and empirical know-hows of experts in blanking companies. The implemented system provides powerful capabilities for process planning of stator and rotor parts and irregularly shaped sheet metal.
Shape Memory Alloy Microactuators
Kim, B.W. ; Kim, K.S. ; K.I. Cho ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 54~61
Because of its high energy density, the use of shape memory alloys(SMA) in designing microactuatiors is gaining much attention in recent years. Shape memory alloys can undergo a shape change at a low temperature with a small applied deformation force, and retain this deformation until they are heated, at which point they return to the original shape. This is called the shape memory effect(SME), and a plethora of alloys show this effect. Among them, TiNi-based alloys have relatively high electrical resistivity, which to develope helical-shape memory springs. These springs are used to develop fast protatonist/antagonist configuration actuators. The developed actuator has an actuation speed of 1 mm per 15 .approx. 20 ms and a minimum operating period of 2 sec.
Study on the Performance Comparision of Software Pulse Interpolators
J.H. Ahn ; H.S. Lim ; Lee, W.K. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 62~69
Interpolator is a very important element in NC machines in that it controls tool path and speed. In this paper, studied were extensive interpolation characteristics of reference pulse method among various interpolation and pulse generation methods. Specifically, processing speed and path error of DDA, SPD and SFG methods were compared and analyzed against line, circle and elipse. As a result, in the point of processing speed, SPD method was found to be the best for line interpolation, SFG method for circle and ellipse, and DDA method was found to be the slowest for all paths. In the point of path error, DDA method was found to have the biggest error for all kinds of paths.
A Study on Algorithm Development of Offset Data Generation in Stereolithography
Kim, J.A. ; S.N. Hong ; Park, I.H. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 70~76
In the Stereolithography process, three-dimensional objects are built by sequentially curing, generated by horizontal slicing of a three-dimensional CAD model. The dimensional accuracy of a menufactured part depends on the accuracy of curing performed by laser beam radius and the half of curing width. When offsetting, some slices have collinear segments, coincident vertices, line jerks and open loops. After remove above issues we have correct offsets data. And in last step, these data are used to scan paths.
Analysis for forging of trochoidal gears
H.Y. Cho ; G.S. Min ; Park, J.U. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 77~83
This paper describes forging of trochoidal gears, which are being widely used in timing belt pulley, pump pulley etc., as a series of development of the simulator for non-axisymmetric elements. Kinematically admissible velocity fields for forging of trochoidal gear were proposed and the loads were calculated by numerical method. When the simulation was carried out, half pith of gear was divided into 6 deformation regions which have different velicity fields by assumptions and boundary conditions. The neutral surface was introduced into forging of trochoidal gears with flat punch and, for each step, it is assumed as a circle with its radius r
. The experimental set-up was installed in 200 ton hydraulic press for forging. The billets, of A1 2218 aluminum alloy, were slightly phosphate-coated. It was shown that thd theoretical solutions, as upper bound, are useful to predict the forging load for forging of trochoidal gears, because thdt give estimates that are substantially higher than experimental loads.s.
Using Geometric Constraints for Feature Positioning
Kim, S.H. ; Lee, K.W. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 84~93
This paper describes the development of new feature positioning method which embedded into the top-down assembly modeling system supporting conceptual design. In this work, the user provides the geometric constraints representing the position and size of features, then the system calculates their proper solution. The use of geometric constraints which are easy to understand intuitively enables the user to represent his design intents about geometric shapes, and enables the system to propagate the changes automatically when some editing occurs. To find the proper solution of given constraints, the Selective Solving Method in which the redundant or conflict equations are detected and discarded is devised. The validity of feature shapes satisfying the constraints can be maintained by this technique, and under or over constrained user-defined constraints can also be estimated. The problems such as getting the initial guess, controlling the multiple solutions, and dealing with objects of rotational symmetry are also resolved. Through this work, the feature based modeling system can support more general and convenient modeling method, and keeps the model being valid during modifying models.
PID-Force Control of a Artificial Finger with Distributed Force Sensor and Piezoelectric Actuator
J.J. Lee ; D.P. Hong ; S. Chonan ; T.S. No ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 94~103
This paper is concerned with the theroretical and experimental study on the force control of a miniature robotic finger that grasps an object at three other positions with the fingertip. The artificial finger is uniform flexible cantilever beam equipped with a distributed set of compact grasping force secnsors. Control action is applied by a qiexoceramic bimorph strip placed at the base of the finger. The mathematical model of the assembled electro-mechanical system is developed. The distributed sensors are described by a set of concentrated mass-spring system. The formulated equations of motion are then applied to a control problem which the finger is commanded to grasp an object The PID-controller is introduced to drive the finger. The usefulness of the proposed control technique is verified by simulation and experiment.
Determination of Object Position Using Robot Vision
Park, K.T. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 104~113
In robot system, the robot manipulation needs the information of task and objects to be handled in possessing a variaty of positions and orientations. In the current industrial robot system, determining position and orientation of objects under industrial environments is one of major problems. In order to pick up an object, the roblt needs the information about the position and orientation of object, and between objects and gripper. When sensing is accomplished by pinhole model camera, the mathematical relationship between object points and their images is expressed in terms of perspective, i.e., central projection. In this paper, a new approach to determine the information of the supporting points related to position and orientation of the object using the robot vision system is developed and testified in experimental setup. The result will be useful for the industrial, agricultural, and autonomous robot.
Performance Evaluation for Several Control Algorithms of the Actuating System Using G/C HILS Technique
W.S. Jeon ; H.J. Cho ; Lee, M.H. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 114~129
This paper describes the whole development phase for the underwater vehicle actuating system with high hydroload torque disturbance. This includes requirement analysis, system modeling, control algorithm design, real time implementation, test and performance evaluations. As for driving control algorithms, fuzzy logic, variable structure and PD(Proportional-Differential) algorithm were designed and implemented on board controller using a single chip microprocessor. Intel 8797. And test and performance evaluation is carried out both single test and wystem integration test. We could confirm the basic performance of actuating system through the single test and gereral developing work of any actuating systems was finished with a single performance test of actuating system without system integration test. But, we suggested that system integration test be needed. System integration test is carried out using G/C HILS(Guidance and Control Hardware-In-the -Loop Simulation) which is constituted flight motion simulator, load simulator, real time host computer and the related subsystems such as inertial navigation system, power supply system and Guidance and Control Computer etc.. The most important practical contribution of this paper is that full system characteristics such as minimal control effort, enhancement of guidance and autopilot performance by the actuating system using G/C HILS technique are investigated. Through full running G/C HILS, in spite of the passing to single tests, some control algorithm resulted in failure as to stability of full system and system time frame.
A Study on the Prediction of the Final Weight for the Injection Molded Rectangular Plates
Lee, C.H. ; K.H. Yoon ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 130~137
In the present paper the effect of various process conditions on the final weight of injection molded rectangular plates has been investigated in detail. The main parameters involved in the simulations were melt temperature, mold temperature, injection speed and packing pressure. The dimensions of the plate used were 100mm long, 2mm of width and polystyrene was used as a molding material. The shear viscosity of the polymeric material was treated as a function of shear rate, temperature and pressure through the whole processes including packing and cooling stages. By increasing a packing pressure the final weight of sample increased linearly. Furthermore, as the melt temperature, the mold temperature and the injection speed increased, the final weight of the injection molded plate decreased within the molding window.
Vibration Control of Moving Structures by Neural Network
Lee, S.Y. ; H.S. Jeong ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 138~148
In moving structures such as robots and feeders of production lines, vibrations may not be ignored. Recently it becomes a big problem to control the vibration in a motion because moving structures are in higher speed, larger size and lighter weight. In this study a nonlinear system was model- led and identified by using neural networks and the vibration in motions was controlled actively by using a neural network controller. To investigate vilidity of this method, an experimental apparatus was made and tested. The model was composed of a DC servomotor, a carrier and a flexible plate. Its motion was measured by a gap sensor and an encoder. Trapezoidal, cycloid and trapecloid type trajectories were used in this exper- riment. Computer simulations and experiments weredone for each trajectory.
A Study on the Monitoring System of the Grinding Troubles Utilizing Neural Networks(l)
M.K. Ha ; J.S. Kwak ; Kim, G.H. ; Kim, H.S. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 149~155
Recent researches in the trouble monitoring system of grinding process have emphasized the use of deep knowledge. Such works include the monitoring and diagnostic systems for cylindrical grinding using sensors on chatter vibration and grinding burn during the process. But, since grinding operations are especially related with a lalrge amount of ambique parameters, it is effectively difficult to detect the grinding troubles occuring during the grinding process. In this paper, monitoring system for grinding utilizes the neural networks based on grinding power signatures. The monitoring system of grinding operations, which makes use of PDP neural networks, is presented. Then, the implementation results by computer simulations and experimental data with respect to chatter vibration and grinding burn are compared.
A Study on the Avoidance of Tool Interference in Analytic Compound Surface Machining
Kang, S.G. ; Cho, S.W. ; Ko, S.L. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 156~164
Tool interference is one of the most critical problems in machining die cavities and punches. When machining concave or convex regions of cavities with large radius tool in rough cutting, the tool easily overcuts or undercuts the portions of the surface, which result in machining inaccuracy. So the generation of interference-free tool path must be required for more efficient rough cutting. In this paper, we present a method for modeling die cavities which consist of simple surface or analytic compoyund surfaces and present an algorithm for checking and removing the tool interference occurred in machining the die cavities. Using these algorithms, we can represent a die cavity, and check the interfer- ence regions, and then remove these interferences. Especially we focus on the side interference in the sides of analytic elements and base surface boundary.
Determination of Elastic Recovery for Axi-Symmetric Forged Products
Kim, T.H. ; Kim, D.J. ; Park, J.C. ;
Journal of the Korean Society for Precision Engineering, volume 13, issue 9, 1996, Pages 165~173
The dimensional accuracy of a final product is mainly affected by elastic die deformation during the forging and elastic recovery after the ejection in cold forging process. The investigations on elastic recovery are not so much as those of elastic die deformation. The elastic recovery can be determined by using the elastic-plalstic finite element analysis, but, this method has some limits such as poor conver- gence and long computational time, etc. In this paper, a theoretical analysis for predicting the elastic recovery of a final product in axi-symmetric forging process by using the rigid-plastic finite element method is presented. The rigid-plastic finite element analysis of a cold forward extrusion process involving loading, ejecting process is accomplished by rigid-plastic FE code, DEFORM. The effect of elastic die deformation on the final product dimenmsion is also considered. The calculated elastic recovery is compared is compared with the analysis result of elastic-plastic FE code. ABAQUS.