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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 12, Issue 12 - Dec 1995
Volume 12, Issue 11 - Nov 1995
Volume 12, Issue 10 - Oct 1995
Volume 12, Issue 9 - Sep 1995
Volume 12, Issue 8 - Aug 1995
Volume 12, Issue 7 - Jul 1995
Volume 12, Issue 6 - Jun 1995
Volume 12, Issue 5 - May 1995
Volume 12, Issue 4 - Apr 1995
Volume 12, Issue 3 - Mar 1995
Volume 12, Issue 2 - Feb 1995
Volume 12, Issue 1 - Jan 1995
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A Study on Tool Wear and AE Signal Characteristics in Face Milling of SUS304
Oh, S.H. ; Kim, S.I. ; Kim, T.Y. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 5~14
In recent years, the automization of cutting machine tools has been developed very fast. Hance, the in-process detection of cutting condition is very important for automatic manufacturing system in factory. Acoustic Emission(AE) has been widely used in monitoring the cutting conditions, because of high sensitivity of AE signal and low cost of AE equipment. This experimental study deals with the relations between AE signal, cutting force charcteristics and tool wear in the machining of SUS304. Face milling operation is used for the analysis between tool wear and AE signal.
Effect of Assistant Gas Pressure on Laser Cutting of STS304
Lee, H.J. ; Y.M. Cho ; Kim, J.D. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 15~22
This paper presents the effects of assistant gas pressure on laser cutting. To investigate the effects of assistant gas pressure, pressure measuring system was constructed with good handling and precision at low price. The measured results discussed compare with that of laser cutting of STS304. The assistant gas pressure varied with the variation of distance between nozzle and workpiece. The peak pressure existed at some distance and could be known by using the deviced pressure measuring system. The higher assistant gas pressure helps to remove the dross and the exothermic energy out of the material. The quantity of dross beneath the workpiece decreases and the kerf width narrows at measured peak pressure.
A Study on the Measurement Characteristics of Cylindrical Type Capacitive Transducers to the Roundness Errors of Rotor for Magnetic Bearing
Lee, S.H. ; Jung, S.C. ; Han, D.C. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 23~31
The sending characteristics of the non-contact type displacement transducers can affect the performances of the magnetic bearing systems when they support the rotating shaft. The probe type displacement sensor detects not only the displacement of the rotor at the sensing position but also the surface irregularitis of the rotor such as surface roughnessand roundness errors. If there exist such measuring errors, the magnetic bearing can not apply proper force against the rotor displacements for the detected signal is the input to the magnetic bearing controllers. The cylindrical shape capacitive transducer can detect the rotor displacement by the integral sum of the charges which are formed between the sensor plates and rotor so that it can reduce the detecting errors induced by the surface irregularities of the rotor. By theore- tical analysis, we compared the sensing characteristics of the cylindrical shape capacitive transducers for the rotors that have some sinusoidal irregularities with that of the ideal probe type displacement transducers.
Improvement of Element Stability using Adaptive Directional Reduced Integration and its Application to Rigid-Plastic Finite Element Method
Park, K. ; Lee, Y.K. ; Yang, D.Y. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 32~41
In the analysis of metal forming processes by the finite element method, there are many numerical instabilities such as element locking, hourglass mode and shear locking. These instabilities may have a bad effect upon accuracy and convergence. The present work is concerned with improvement of stability and efficiency in two-dimensional rigid-plastic finite element method using various type of elemenmts and numerical intergration schemes. As metal forming examples, upsetting and backward extrusion are taken for comparison among the methods: various element types and numerical integration schemes. Comparison is made in terms of stability and efficiency in element behavior and computational efficiency and a new scheme of adaptive directional reduced integration is introduced. As a result, the finite element computation has been stabilized from the viewpoint of computational time, convergency, and numerical instability.
A Study on Flashless Non-Axisymmetric Forging
W.B. Bae ; Y.H. Kim ; J.H. Lee ; K.Y. Kim ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 42~52
An UBET(Upper Bound Elemental Techniquel) program has been developed to analyze forging load, die-cavity filling and effective strain distribution for flashless non-axisymmetric forging. To analyze the process easily, it is suggested that the deforma- tion is divided into two different parts. Those are axisymmetric part in corner and plane- strain part in lateral. The total power consumption is minimized through combination of two deformation parts by building block method, form which the upper-bound forging load, the flow pattern, the grid pattern, the velocity distribution and the effective strain are deter- mined. To show the merit of flashless forging, the results of flashless and flash-forging processes are compared through theory and experiment. Experiments have been carried out with plasticine billets at room temperature. The theoretical predictions of the forging load and the flow pattern are in good agrement with the experimental results.
A Study on the Wear Mechanism of the Alumina Ceramics for the Wear of STB2
J.W. Nam ; T.O. Jun ; D.K. Jin ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 62~72
The present study was undertaken to investigate the dry wear mechanism of the alumina ceramics in the purity variation for the wear of STB2. The wear test was carried out under different experimental condition various sliding speed, contact pressure and sliding distance. According as the alumina purity increased, wear volume of the STB2 decreased and minimum value of wear volume was over to high speed side. According as the sliding speed and sliding distance increased, friction coefficient decreased owing to drop of the shear strength, it decresed largely owing to decreased of elastic modulus and thermal conductivity with decrease in alumina purity. Indicative of minimum, value of wear volume, low speed side was abrasive wear, high speed side was wear of heat softening. The friction surface of ceramics protacted by oxide was transfer from STB2.
Establishment of Initial Work Roll Crown in Finishing Plate Mill
Kim, J.T. ; J.H. Seo ; B.W. Jung ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 73~81
To find a way for establishing work roll initial crown according to roll conditions, computer simutation for predicting plate crown in plate mill is done and effects of roll conditions on plate crown is analyzed. Toll gap rorfile and plate crown are measured to be compared to the calculated values. As a result, regression equation to establish work roll initial crown according to roll conditions such as backup roll diameter, backup roll crown and work roll diameter is obtained.
A study for the real-time acquirement of cutting process control limit based on geometrical relations
J.H. Hong ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 82~91
The purpose of this research is to develop a new real-time process control system. In this paper, a theoretical method for acquiring the control limit of cutting process(cutting surface) according to the required value(geometric tolerance) based on geometrical relations was propsed. In particular, the three following points are amphasized. Firstly, the process control was based on the cutting process, and the control limit was determined from the analysis of geometrical relations. Secondly, AMGD(Actual Measured Geometrical Deviation) was used as a new substitute value in process analysis. Thirdly, fuzzy reasoning was introduced to get the control limit flexibility according to the variations in the required value and general consideration of each measurememnt items.
An Experimental Study on the Tool Failure Detection in the Machining by Face Milling
J.H. Seo ; Kim, S.I. ; Kim, T.Y. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 92~100
This experimental study is mainly investigated on the mean cutting forces and AE(acoustic emission) parameters in order to detect and estimate the tool failure in the pachinig of SUS304 by face milling Mean cutting forces and AE parameters can detect the tool failure in face milling. Effective detection parameters are AE RMS, AE energy, AE count, AE duration, and z-direction mean cutting force. From the analysis of cutting tool failure detection, the tool failure of face milling is caused by sudden increasing of the cutting force.
A Study on the Finite Element Analysis of Tire under Rolling and Loading Conditions
J. Hang ; S. Namgung ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 101~109
Axisymmetric and quasi-static finite element analysis of an inflated tire rotating with constant angular velocity and contact to road has been performed. Centrifugal force effect was added to load stiffness matrix and equation of effective material properties were calculated by the Halpin-Tsai formulation. In this report, radial truck/bus tire was analyzed. It was inflated and rotated at speeds up to 140 km/h. Then, contact problem was performed to calculate stress-strain field of tire wiht flat rigid road under the load due to the self-weight of a vehicle. Significant changes of stress-strain field of tire were observed in the finite element analysis. Shear stress, strain and strain energy density were rapidly increased at the dege of #2 belt at freely rotating state. This concentrated stress and strain made belt edge sparation. Under the condition of flat riged road contact, strain energy density of #2 belt, carcass turn-up part were concentrated and bigger values than only freely rotation state. Therefore, dynamic behaivor of tire has to considered as design factors which are affected to belt edge separation and bead breakage.
A study of estimation of filling phase condition in injection molding process
Jo, Y.M. ; Kwon, O.J. ; Kim, J.D. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 110~118
The filling phase analysis of the injection molding process for thermoplastics was applied to predict pressure, themperature and shear stress in the test mold, and the results were compared with the experiment using 30% glass fiber added ABS resin. The finite difference method was used in the analysis considering the effects of heat transfer between molten polymer and mold wall, and also frictional heating by shear flow. The analysis results were considered as a method to improve the quality and the productivity of injection molding process. Using the analysis results, the molding factors such as mold-ability of polymers, performance of injection molding machine, positioning of gate and dimendsioning of runner in the injection molding process can be estimated at the design stage of mold for good quality and productivity.
Analysis of the Machinability of a Precision Machining of Molds/Dies by Using Jig and 3-Axis M/C
Kim, B.H. ; C.N. Chu ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 119~129
In this paper, the inclined endmilling process with a 3-axis machining center using inclined jigs is introduced for the purpose of reducing overall Dies/Molds machining time and improving the machining accuracies. In order to analyze the cutting mechanism of a given endmill more accurately, the unification of the cutting mechanism model of 3-different- kind endmills is carried out by using a nose radius as a parameter. By adding radial runouts as a parameter which influences on surface roughness, the superposition method which defines the effective cusp height superposing the cutter mark height and the conventional cusp height is advanced. And 3-D suface topography predicted in this paper looks like the surface normally observed in practice. Through machining experiments, the adequacy of the superposition method was confirmed.
A Study on Real-time Monitoing of Tool Fracture in Turning
Park, D.K. ; C.N. Chu ; Lee, J.M. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 130~143
This paper presents a new methodology for on-line tool breadage detection by sensor fusion of an acoustic emission (AE) sensor and a built-in force sensor. A built-in piezoelectric force sensor, instead of a tool dynamometer, was used to measure the cutting force without altering the machine tool dynamics. The sensor was inserted in the tool turret housing of an NC lathe. FEM analysis was carried out to locate the most sensitive position for the sensor. A burst of AE signal was used as a triggering signal to inspect the cutting force. A sighificant drop of cutting force was utilized to detect tool breakage. The algorithm was implemented on a DSP board for in-process tool breakage detection. Experiental works showed an excellent monitoring capability of the proposed tool breakage detection system.
A Simulation of TV microphonic phenomenon due to Shadow mask Vibration
J.S. Lim ; S.H. Lim ; Lee, J.E. ;
Journal of the Korean Society for Precision Engineering, volume 12, issue 3, 1995, Pages 144~152
TV microphonic phenomenon (black patterns overlapped on the image when TV sound is set too high) was studied experimentally. It was found that this phenomenon was due to the vibration generated at speakers, and transmitted to the CRT through the TV cabinet structure. Based on this fact, a simulative study was carried out on the assumption that the vibratory motion of the shadow mask located in the CRT could cause the landing error of electronic beam. The result of the simulation corresponded qualitatively with experi- mentally observed facts.