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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 14, Issue 12 - Dec 1997
Volume 14, Issue 11 - Nov 1997
Volume 14, Issue 10 - Oct 1997
Volume 14, Issue 9 - Sep 1997
Volume 14, Issue 8 - Aug 1997
Volume 14, Issue 7 - Jul 1997
Volume 14, Issue 6 - Jun 1997
Volume 14, Issue 5 - May 1997
Volume 14, Issue 4 - Apr 1997
Volume 14, Issue 3 - Mar 1997
Volume 14, Issue 2 - Feb 1997
Volume 14, Issue 1 - Jan 1997
Selecting the target year
Induction Heating of a Billet for Semi-Solid Forging
Park, J.C. ; Park, H.J. ; Kim, B.M. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 15~20
Semi-solid forging is a compound forging technology to develop conventional forging process. Among several steps of semi-solid forging process, the heating step of a billet prior to semi-solid forging step is necessarily required to obtain globular microstructure. For the forming operation to work properly, it is also important to heat the billet uniformly for the uniformity of solid-liquid distribution. To satisfy these requirements, induction heating has been generally used for a long time. This paper presents the method to find heating condition and the temperature distribution inside a billet with a induction heating apparatus by comparing the computer simulation with experiment for aluminium alloys A12024 and A356.
A Study on the Effects of Process Parameters on Dynamic Behavior Changes of Turning System
Kim, K.H. ; C.Y. Oh ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 21~28
This paper presents the influence of the process parameters on the change in dynamic behavior of a lathe turning system. With variation of feed rate, depth of cut, direction of tool motion, cutting speed and tool location along the workpiece, the dynamic characteristics of stable cutting, chatter transition and fully developed chatter regions are demonstrated. The workpiece vibration during machining is continuously measured at different tool locations along the workpiece and quantitatively analyzed. Complex linear behavior due to change of process parameter values as well as fundamental wystem nonlinearity due to change of process configuration indicated by a tool path dependence of the locations of chatter onset and disappearance are described. Finally, the structural characteristics of the turning system which can have large and nonlinear effects on system behavior are presented.
A Study on the Effect of Preloading in Clamp
Han, D.M. ; Lee, S.S. ; Lee, D.R. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 29~39
The clamp, as the structure which is used for supporting the pipe in the atomic power plant, is produced with a certain degree of anticlastic curvature in the current manufacturing process. In this study, the structural analysis of the clamp and the pipe was performed using ABAQUS. And the finite element modelling for the analysis was made by an HyperMesh. The contact forces which are transferred between the clamp and the pipe for the external force are changed according to the binding force of bolts and keeps the clamp tightly and protects the slipping between the clamp and the pipe. The clamps with the anticlastic curvature and with the flat curvature are considered in order to invest the anticlastic effect. In this study, another case is suggested. The present case does not have the stiffness ring on the end of the clamp but the suggested case has the ring. For the present case, the results showed that the equivalent stress is higher in the anticlastic curvature case than in the flat curvature case and the equivalent stresses on the pipe are almost the same as the binding force increses. For the suggested case, the result showed that the equivalent stress in the anticlastic curvature case decreases until some binding force and increases as the binding forces increase and is lower in some range than in the flat curvature case. From this study, the clamp with the anticlastic curvature in the suggested method is better than the clamp with the flat curvature and the optimal binding force are given.
A Study on Development of the Characteristic Analysis and CAD System for Hydraulic System Using Modular Approach
Lee, Y.J. ; C.S. Song ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 40~48
In this study, an analysis and design for hydraulic control system was developed. By using this system, the operator is able to simulate dynamic performance of the system without possessing special knowledge of software or control engineering. A graphical user interface was adopted in the system and all speration for simulation can be done by using window facilities on the display. The electro-hydraulic servo system is simulated to present the performances of the program and compared with the result of Matlab and experiment.
A Study on Technical Development of Ultrasonic Test for Application of Industrial Fields
W. Yi ; I.S. Yun ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 49~56
In recent years, ultrasonic technics has been widely applied to industrial fields and its application range has been expanded as a result of continuous research and development. This paper is concerned with development of post-processor program for ultrasonic test and two-axis automatic ultrasonic system for application of industrial fields. Test results of ultrasonic test post-processor program and two-axis auto- matic ultrasonic system have a good agreement with results of ultrasonic evaluation for defect detection in industrial fields. Therefore we think that the developed ultrasonic test post-processor program and two- axis automatic ultrasonic system in this work is very useful for application of industrial fields.
Process Design in Cold Forging of the Backward and Forward Extruded Part
G.S. Min ; J.C. Choi ; H.Y. Cho ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 57~64
The process design of backward and forward extrusion of axisymmetric part has been studied in this paper. The important factors of cold forging process with complex geometry are the design of initial billet shape, the possibility of forming by one-stage operation and the determination of preform shapes, etc. Based on the systematic procedure of process sequence design, the forming operation of cold forged part is analyzed by the commercial finite element program, DEFORM. The design criteria are forming load, geo- metrical filling without defect and a sound distribution of effective strain in final product. It is noted that one step of preform operation is required to obtain the final product. Numerical result is compared with experi- mental one. It is found that the analyzed result is in good agreement with actual forming result.
Asymmetrical Contouring Control of Biaxial System
Y.B. Sim ; Y.C. Jung ; Lee, G.B. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 65~72
An asymmetrical cross-coupled compensator to improve the contouring performance is proposed. This is a refinement of the structure suggested by Koren. The position loop is closed with a proportional controller as in the uncoupled system. An additional input term proportional to the component of the contour error along the corresponding axis is included. The controller gains are chosen to give an appropriate frequency response and an optimum range for the damping ratio. The effectiveness of the proposed controller is studied by means of digital simulations of the dynamics of the drives and the controller for 4 types of command trajectories: straight line contour, cornering contour, circular contour, elliptic contour. Substantial improvement in contouring performance is obtained for a range of contouring conditions.
Turning of Hardened Materials Using the Air-oil Cooling System
B.G. Chung ; T.J. Ko ; Kim, H.S. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 73~81
The hard turning process defined as a single point turning of materials harder than
C 58 differs from conventional turning because of hardness of the work materials and cutting toos needed in the process. In hard turning, tool life is very short, of the order of a few minutes, during which the cutting tool is subjected to the extremes of stress and temperature. In this regard, it is well known that CBN tool is proper for this process in spite of expensive cost. In this research, we studied the feasibility of the use of the low cost cutting tool such as a aTiN coated tool. To this end, a new cooling system was designed with an air-oil method for reducing tool temperature, which is based on the principle of air vortex flow. That is, the outlet temperature of the air becomes aver 20 .deg. C lower than atmosphere temperature by entering pressurized air of 5kgf/c
into the inlet. This cooled air ejected to the top of the cutting tool lowered tool temperature, which reduced the wear of a TiN coated tool by the 30% of CBN tool life with respect to the same cutting length.h.
Finite Element Analysis for Forming Process of Semi-Solid Material Considering Induction Heating
Park, W.D. ; Ko, D.C. ; Kim, B.M. ; Park, J.C. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 82~91
The major objective of this study is to establish analytical technique in order to analyze the behaviour of semi-solid material considering induction heating of the billet. Induction heating process is analyzed by using commerical finite element software. ANSYS. The finite element program, SFAC2D, for the simulation of deformation in semi-solid state is developed in the present study. The semi-solid behaviour is described by a viscoplastic model for the solid phase, and by the Darcy's law for the liquid flow. Simple compression and closed-die compression process considering induction heating are analyzed, and also it is found that the distribution of initial solid fraction of the billet has an important effect on deformation behaviour of semi-solid material. In order to verify the effectiveness of proposed analytical technique the simulation result is compared with experimental result.
The Improvement of Bearing-Race Forming Process Using UBET Analysis
Kim, Y.H. ; W.B. Bae ; Park, J.W. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 92~100
An upper-bound elemental technique (UBET) analysis is carried out to improve the material flow and to reduce the load of bearing-race forming process. The UBET analysis, which adapts the advantages of stream function and finite element method, is useful for predicting the profile of complex geometric bound- ary. From the UBET analysis, the forming load, the velocity distribution and the stream line of the deformed billet are determined by minimizing the total power consumption with respect to chosen parameters. The results of present UBET analysis are better than those of previous UBET analysis. Experiments have been carried out with model material plasticine billets at room temperature. The theoretical predictions for forming load and flow pattern(stream line) are in good agreement with the experimental results.
Reducing the Non Grinding Time in Grinding Operations(2nd report) -Decision of Dressing Chance and Depth by the Direct Measurement of Grinding Wheel Surface-
Kim, S.H. ; J.H. Ahn ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 101~107
In general, grinding is one of the final machining processes which determines the surface quality of machined products. Since the ground surface is affected by the states of grains and voids on the grinding wheel surface, the wheel should be dressed before the machined surface deteriorates over a quality limit This paper describes a systematic approach to decide a proper dressing chance and an optimal dressing depth for the working grinding wheel. An eddy current sensor and a laser displacement sensor are used to measure the loading on the working wheel surface and the topography of the dressed wheel surface respec- tively. The dressing chance can be properly decided through the relational locus between the amount of handing and the machined surface roughness. An optimal dressing depth to guarantee the less wheel loss and the higher wheel surface quality is decided through the analysis of the variance of topography for the dressed wheel surface, which decreases at three different rates according to the accumulated dressing depth.
Dynamic Analysis of Interconnected Flexible Beams Having Large Rigid Body Rotations
Lee, K.S. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 108~114
A simple and efficient method is presented for the dynamics of interconnected flexible beams having large rigid body rotations. A simple mass matrix is obtained by interpolating the displacements in the global inertia frame, and the elastic force is also simply computed by using linear finite element technique with the moving frame attached to the beam. For the beams connected by revolute joints, kinematic constraints and relative rotations between the beans are not required and the equations of motions are time integrated by a simple ODE technique. Numerical simulations are conducted to demonstrate the accuracy and efficiency of the present technique.
Flank Wear Estimation Using Dynamic Cutting Force(l)
Kwon, Y.K. ; Oh, S.H. ; Seo, N.S. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 115~121
The in-process detection of the tool wear is one of the most important technologies in completely auto- matic operation of machine tool. In this research, using the tools having flank wear, the dynamic compo- nent of cutting forces is considered to be available for identifying the cutting process. In order to investi- gate this relation in detail, the cutting forces in turning of workpiece made of aluminum were measured by dynamometer of piezoelectric type, and the dynamic components of cutting force were analyzed. The fre- quency analysis, probability density analysis and RMS analysis of the dynamic components were carried out independently. Through the experiments, the characteristics of the tool system have a large effect on the dynamic component of cutting forces. As a result, it is shown that the dynamic cutting force was able to detect flank wear accurately.
Optimal Algorithm of Path in the Part-Matching Process
J.H. Oh ; Y.Y. Cha ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 122~129
In this paper, we propose a Hopfield model for solving the part-matching in case that is the number of parts and positions are changed. The goal of this paper is to minimize part-connection in pairs and total path of part-connections. Therefore, this kind of problem is referred to as a combinatiorial optimization problem. First of all, we review the theoretical basis for Hopfield model and present two optimal algorithms of part-matching. The first algorithm is Traveling Salesman Problem(TSP) which improved the original and the second algorithm is Wdighted Matching Problem (WMP). Finally, we show demonstration through com- puter simulation and analyze the stability and feasibility of the generated solutions for the proposed con- nection methods. Therefore, we prove that the second algorithm is better than the first algorithm.
Basic Characteristics of an Active Controlled Capillary for Compensating the Error Motion of Hydrostatic Guideways
Song, Y.C. ; Park, C.H. ; Kim, S.T. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 130~136
For compensating the error motion of hydrostatic guideways, we introduce a way that the clearance of table is actively controlled corresponding to the amount of error with the variable capillary. The structure and the theoretical design method of active controlled capillary using piezo actuator, named ACC, are proposed in this paper. Basic characteristics such as the maximum controllable range, micro step response and available dynamic bandwidth are tested for confirmation of structural suitability of ACC, and these characteristics are also tested on the table mounted with ACC for verifying the availability. The experimental result showed that by the use of ACC, the error motion within 2.7 .mu. m of a hydrostatic guideway can be compensated with the resolution of 2.7nm, 1/100 contollable range, and the frequency bandwidth of 5.5 Hz. From these results, it is confirmed that the ACC is very effective to improve the motion accuracy of high or ultra precision hydrostatic guideways.
A Study for Mutual Interference between Symmetric Circular Inclusion and Crack in Finite Width Plate by Boundary Element Method
Park, S.O. ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 137~145
A two-dimensional program for the analysis of bimaterial inclusion has been developed using the bound- ary element method. In order to study the effects of circular inclusion on the stress field of the crack tip, numerical analysis was performed for the straight crack of finite length around the symmetric circular inclusion whose modulus of elasticity was different from that of the matrix material. In the case of inclusion whose stiffness was smaller than that of the matrix material, the stress intensity factor was found to increase as the crack enamated. The stress intensity factor was uninfluenced from the radial change in inclusion and remained constant for the stiffness equivalent to the matrix materials, where as it decreased for the inclusion with larger stiffness. For the vareation in the distance of the inclusion, a small increase in the stress intensity factor was observed for the case with small or equal stiffness compared with the matrix materials. The inclusion with larger stiffness showed a gradual decrease in the strss intensity factor as the crack emanated.
Braking Pressure Characteristics of Solenoid-Flow Control Type ABS by PWM Control
C.S. Song ; H.J. Yang ;
Journal of the Korean Society for Precision Engineering, volume 14, issue 8, 1997, Pages 146~154
Solenoid-folw control type ABS is used with a 'dump and reapply' pressure control arrangement instead of using 2/2 (normal open/close) solenoid valves in convensional systems(sol. -sol. control type), a flow control valve is used which replaces the (no) inlet valve. The flow control valve controls fluid flow providing a nearly constant reapply rate( .theta. ) after the dump plase of ABS operation. In this study, to investigate a characteristics of brake pressure by PWM control, test rig was consisted of ABS hydraulic modulator, digital controller, pneumatic power supply and brake master cylinder. For comparison with experi- mental results, system modelling and computer simulation were performed. As a result, experiment results showed fairly agreement with the simulation. Also, it is shown that the pressure gradient (tan .theta. ) is affected by pressure, frequency, duty ratio and expressed with an exponential funtion.