한국공작기계학회:학술대회논문집 (Proceedings of the Korean Society of Machine Tool Engineers Conference) (Proceedings of the Korean Society of Machine Tool Engineers Conference)
한국생산제조학회 (The Korean Society of Manufacturing Technology Engineers)
- 기타
한국공작기계학회 1998년도 추계학술대회 논문집
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The assessment of machined surface is difficult because the freeform surface must be evaluated by surface fairness as well as dimensional accuracy. In this paper, the methodology of freeform surface generation using measured data on the machine tool is presented. The reliability of measured points data is obtained by measuring error compensation. The compensated data are formulated through Non-uniform G-spline surface modeling. In order to improve the surface fairness, the generated model si smoothened by parameterization The validity and usefulness of the proposed method are examined through computer simulation and experiments on the machine tool.
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This paper discuss to structure analysis of manufactured goods with DNC. DNC procedure is using CAD, CAM software and CNC machining center. CAM software is purpose of G-code generation for CNC programming. For structure analysis used to result from FEM code and the object of analysis is thincylinder.
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The effect of tool angles on the surface roughness in face milling is studied. First, the relation between tool angles and rotation angles is identified. Using this relationship, it is obtained that the projection of insert nose shape on cutting profile, which is a part of ellipse. The effect of spindle tilt is also considered for the tool angles. It si shown that tool angles along with nose radius and feed rate have an effect on surface roughness.
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The object of this study is DNC application of progressive die production process. DNC systems are consis of Auto CAD, CAM software and CNC milling machine. CAM software is purpose of G-code generation for CNC programming. Then CAM software and CNC milling machine are connect to RS-232C cable.
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Magneto Electrolytic Polishing (MEP) is a process in which metal ions are removed from a abrasive through a combination of magnetic electric current and chemical solution. The substrate is immersed into the magnetic effect, chemical solution, and DC crunt is applied. Several factors affect the rate at which the metal ions are removed from the substrate. Three of the most significant are the amount of time in which the substrate is immersed I the solution, and the amount of direct current applied in magnetic field. In this study, the surface finishing characteristics and optical finishing condition for the stainless steel were experimented upon and analyzed.
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In this paper, the new electrochemical machining method is proposed for the micro unit fabrication by using the point electrode tools. The precision shape control capacity is improved by using the point electrode method. It was observed that an electric discharge phenomenon occurs during the electrochemical machining process by using the spraying and torrent type electrolyte supply method.
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In order to minimize straightness error of deflected shafts, a automatically bending process control system is designed, fabricated, and studied. The multi-step straightening process and the three-point bending process are developed for the geometric adaptive straightness control. Load-deflection relationship, on-line identification of variations of material properties, on-line springback prediction, and studied for the three-point bending processes. Selection of a loading point supporting condition are derved form fuzzy inference and fuzzy self-learning method in the multi-step straighternign process. Automatic straightening machine is fabricated by using the develped ideas. Validity of the proposed system si verified through experiments.
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Recently, It is gradually raised necessity that thickness of thin film is measured accuracy and managed in industrial circles and medical world. Ultrasonic Signal processing method is likely to become a very powerful method for NDE method of detection of microdefects and thickness measurement of thin film below the limit of Ultrasonic distance resolution in the opaque materials, provides useful information that cannot be obtained by a conventional measuring system. In the present research, considering a thin film below the limit of Ultrasonic distance resolution sandwiched between three substances as acoustical analysis model, demonstrated the usefulness of ultrasonic Signal processing technique using information of ultrasonic frequency for NDE of measurements of thin film thickness, sound velocity, and step height, regardless of interference phenomenon
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The adaptive skill of the human operator is now being simulated and reproduced by computer that have become more powerful and less expensive. This paper is concerned with an investigation of the effects of dynamic load of hydraulic oil on pressures with three different circuit(meter-in, meter-out and bleed-off). The experimental results showed that pressures increase with an increase in dynamic load in bleed-off circuit, but there is no variation of pressure in meter-in and meter-out circuits.
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This study is object to thermal analysis of continuous casting mold. A two-dimensional transient finite element model was developed to compute the temperature distribution and stress behavior for continuous casting mold. For thermal analysis using analysis result from FEM code. In other to thermal analysis of continuous casting mold, many variables such as casting speed, cooling condition, film coefficient, convection and load condition re considered.
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BTA drilling among the deep hole drilling is using for the improvement of productivity and the high-efficient working. As the deep hole drilling with BTA drill is satisfied with the required quality by one-pass processing, more deeper hole depth, the accuracy of materials is affected by bending vibration and cutting speed. This paper is studied that the shapes of material (surface roughness, roundness) is affected by cutting condition compared actual roundness with lobe shape with modeling of computer through the experiments in the BTA drilling system with BTA drill.
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There are various noises generated by friction. Among the rest, eliminating squeal noise generated during braking is an important task for the improvement of vehicle passengers' comfort. The parameters affecting brake squeal noise are the material properties of the braking pad, the dynamic properties of the brake parts and the dimensions of the brake assemble etc. Also, the squeal noise changes its inherent form(i.e. its sound pressure level and its frequency) with the normal load and sliding speed. In this study, the characteristics of brake squeal noise generated by friction is analyzed experimentally. The experiment focused on the analysis of friction self-excited vibrationand squeal noise level. Friction self-excited vibration is caused by the dry friction between pads and rotor, and occurs as a function of their relative sliding speeds. And Friction self-excited vibration is raised the brake squeal noise.
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항공기 개발단계에서의 RAM(Reliability, Availability, Maintainability) 예측은 진행중인 설계개념이 RAM 개발 목표값을 달성할 수 있는지를 판단하여 이를 설계에 반영하기 위한 것이다. 본 연구에서 신뢰도 예측 모델은 항공기의 임무에 초점을 둔 임무신뢰도와 시스템신뢰도를 산출하고, 정비도 예측 모델은 군수지원분석자료(LSAR)와의 호환성을 유지할 수 있도록 하였으며, 가용도 예측 모델은 신뢰도와 정비도 자료를 활용한 운용가용도를 예측하는 데에 기준을 두었다. 본 연구는 기존의 RAM 예측이 각각 독립적으로 수행된 점을 보완하여 서로간의 상호관계를 반영한 통합 예측 모델을 개발하는 데에 초점을 두었으며, 실제적인 운용개념을 반영한 모델링으로서 항공기 개발단계에서 뿐만 아니라 실제 운용단계에서의 RAM 분석에 효과적이라 판단된다.
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This paper is especially concerned with the weldment between support beam and square bar that plays important roles in control box of Expansion Joint as a bridge structure. Fatigue strength of the weldment is dependent on notch radius from welding defects and material properties. From which, tensile strength(
$\sigma$ ult) and fatigue notch factor(Kf) become important factors to predict fatigue life. The fatigue notch sensitivity(η) for metals can be divided into two types : high and low notch sensitivity. In this work, the Expansion Joint weldment was found to have low notch sensitivity. Fatigue test of real structure was performed up to 106cycles to be compared with predicted endurance limit. -
It is well known that during the oxygen cutting residual thermal stresses are produced in weldment. Surface compressive residual stress is one of reasons for improvement on fatigue durability. To reduce the residual stress and improve the fatigue strength applied the impact loading in oxygen cutting frame. After applying the impact loading, redistribution of residual stress was measured by cutting method and tested fatigue tests.
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Nine tubes with trapezoidal integral-fins having fin densities from 748 to 1654fpm and 10,30 grooves and finned tubes with caves of 0.55 and 0.64mm height respectively are tested. A plain tube having same diameter as the finned tubes is also tested for comparison. In case of condensation CFC-11 condensates at saturation state of 32
$^{\circ}C$ on the outside surface cooled by inside cooling water flows. And in case of boiling the refrigerant evaporates at a saturation state of 1bar on the outside tube surface and heat is supplied by hot water which circulates inside of the tube. The tube having fin density of 1299fpm and 30grooves has the best condensation overall heat transfer coefficient. However, as far as boiling heat transfer coefficient concerns, fin tubes with cave show higher value than low fin tube having fin density of 1299fpm and 30 grooves. -
The objective of this study is to estimate and to compensate for the volumetric error of a machine tool. In this paper, the volumetric error is defined and error synthesis model is presented. Then, the volumetric error of workpiece is compared through the virtual machining and a new tool-path is generated to compensate for the error in the post-processor of CAM system using the error synthesis model. By this method, the error is compensated without modification or replacement of a machine tool being in use.
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In this study, analysis for fatigue crack propagation behavior of interface and aroud interface under rotary bending stress. Though K values are nearly the same in around interface by BEM 2-D, fatigue crack propagated H.A.Z. Around Interface crack propagation speed is m=0.678 in H.A.Z by Paris' law. In this case(friction welded materials: STS304, SM15C), fatigue crack growth is considered SM15C metal microstructure and elastic flow from this result. Result is more metal microstructute dependence than stress dependence by analysis (BEM 3-D, BEM 2-D) and fatigue crack propagation
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In this study, a machining error estimation system for vertical lathes with structural deformation and geometric errors, is realized based on the virtual manufacturing technologies. The positional and directional errors of cutting tool are determined by considering the geometric errors and dimensions of machine components and by introducing the equilibrium condition between the cutting force and structural deformation. specially, the machining errors of vertical lathes are estimated by using the prescribed cutting test(JIS B 6331). The system can be implemented to evaluate the machining accuracies of vertical lathes at the design process and to design the high precision vertical lathes.
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In this paper, the cutting characteristics and cutting mechanism of polystyrene foam was experimentally investigated. It was found that polystyrene foam has different cutting characteristics and cutting mechanism comparing with that of normal metal materials. By using the experimental results, the optimal cutting tool was designed and examined for approving the cuttingability of polystyrene foam.
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This paper deals with condition monitoring for tool wear during tuning operation. To develop economic sensing and identification methods for turning processes, sound pressure measurement and digital signal processing technique are proposed. To identify noise sources of tool wear and reject background noise, noise rejection methodology is proposed. features to represent condition of tool wear are obtained through analysis using adaptive filter and FFT in time and frequency domain. By using fuzzy pattern recognition, we extract features, which are sensitive to condition of tool wear, from several features and make a decision on tool wear. The validity of the proposed system is condirmed through the large number of cutting tests in two cutting conditions.
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In general, machining time by electrical discharge machining (EDM) process is much longer than that of cutting process, so rough-cut has done for the purpose of reducing machining time prior to EDM Nowadays EDM speed is improving due to the advance of EDM capacity. Therefore a new method, machining a raw material directly by EDM without rough-cut, is used widely. EDM area is varies according to the EDM position in three-dimensional EDM process, so EDM parameters should be determined adaptively based on the EDM area to increase productivity. However it is difficult to calculate EDM area corresponding to the EDM position the EDM workers who have experience in shop floor determine machining parameters by experience. This paper proposes a method for determining EDM parameters based on EDM area corresponding to EDM position.
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Electropolishing is the anodic dissolution process in the transpassive state. It removes non-metallic inclusions and improves mechanical and corrosion resistance of stainless steel. If there is a Bailby layer, it will be recovered again. Electropolishing is normally used to remove a very thin layer of material on the surface of a metal component. The aim of this study is to determine the tendencies of electropolishing STS316L tubes in terms of current density, machining time, temperature, electrode gap and surface roughness.
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Abrasive flow machining is useful to abrasive polish a internal or external surface of the free shape dimensional parts, which are used in many fields such as machine tool parts, semi-conductor, and medical component industries. The machining process is that two hydraulic cylinders, which are located surface to surface, are enforce media to the passage between workpiece and tooling part alternately, and then the abrasives included in the media pass the passage and polish the surface of workpiece. The media which is made of polymer and abrasive plays complex have workpiece by its viscoelastic characteristics. In this study, the media for AMF was made by mixing viscoelastic polymer with alumina and silicon carbide abrasive respectively. As a result, alumina include media is also the experiments of deburring the inside burr of in order to analyse the deburring machinability of abrasive flow machining according to various machining parameters which were media flow rate extrusion pressure, passage gap, media viscosity, abrasive content, and abrasive grain size.
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To acquire the high precision of profile for standard electrode of loss angle, it is needed ultraprecision machining technology like MEAP(Magnetic Electronic Abrasive Polishing) and the very high profile measurement technology which can measure a micro unit about the workpiece. So, in this paper, it was developed the measurement system of precision of profile using non-contactable sensor that was approximate sensor of capacitance type, because that is better than others in the electrical characteristics. And standard electrode of loss angle was machined by the MEAP machining technology. In this study, it was development of precision measurement system. This system could be used measure the workpiece of roundness and straightness much more precise and faster than general mechanical measurement system done before. And it could be helped to minimize machining time and planning by very fast and precise measurement about the workpiece.
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The acceleration of the performance of machine tools influences the development of the semi-conductor and optical technology as the development of NC and measurement technology. We can mention that a traction role of the acceleration for the development like that depends on the development of the measurement technics Stylus instrument method, STM, SEM, Laser interferometer method which are used for measuring the quasi-static error of machine tools. Because the measurement has been done to unload condition without considering of mechanical stiffness in the case of machining center as we measure the quasi-static error of machine tools on general studies, people who works on the spot has many problems on the data value. Therefor we will help working more accurately on the spot by measuring, analyzing, displaying the deflection of the table and support shaft when we load on the table and the support shaft of machining center using laser interferometer. Also we try to settle new conception of the measurement method and more accurate grasp of the deflection tendency by verifing the tendency of the error measured through the comparison of the simulated error using ANSYS, a common finite element analysis program, which is able to measure heat deformation, material deformation, and error resulted form this study.
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In this paper, systemaic approach is studied about assembility and disassemblility of parts of the gear system in order to reduce the assembly cost, and to disassemble products easily which is possible to recycle the parts. That is, an estimation of disassembly and assembly with considering of reliability life. In this study, we use symbolic chart method for an economic model for optimal disassembly and assembly.
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dynamic modelling method is applied to the driving simulation which has the calculable model of engine, transmission, vehicle. And driving pattern is used for database by actual tests and analyzed in neural network system. The simulation is compared to real test results and structures to the tracked vehicle powertrain.
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The paper proposes a new method for measuring the flow ripple generated by an axial piston pump and motor in a hydrostatic transmission. The method is based on dynamic characteristics between pressure and flow ripple in the pipeline. Also, the self-checking functions develop for the evaluation of accuracy and dynamic response of estimated results by the method proposed here. The experiment carry out open circuit type hydrostatic transmission. By using the self-checking functions, the validity of the method is investigated by comparison with the measured and estimated flow and pressure ripples, and good agreement is achieved.
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This study is object to process improvement of continuous casting mold. For process improvement of continuous casting mold using CAD, CAM software and CNC machining center. CAM software is purpose of G-code generation for CNC programming. Then CAM software and CNC machining center are connect to RS-232C cable.
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Flow characteristics of a compressible gas flow through a rotating disc-type rotary valve are investigated experimentally under various conditions. It is known that the mass flow rate through poppet valves of 4-stroke cycle engines and through piston valves of 2-stroke cycle engines decrease with increase in engine speed. Rotary valve is one means by which air maybe made to flow intermittently through a pipe. In this paper a exhaust system simulator of engine was used to experimentally analyzer the decrease inflow rate at high rotation speeds and to determine what variables, other than rotational speed, give rise to the observed behaviour. These variables have been included in an empirical equation which is representative of the measured flow characteristics.
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The conventional closed-die forging processes had been applied to forging of the spur gears. But this type process requires high pressure. The commercial finite element analysis code ANSYS for the stress and elastic deformation of non-axisymmetric die was adopted in this study. In the non-axisymmetric die such as gear forging, maximum stresses were imposed on the tip of the gear tooth. When the stress exceeds yield strength of insert die, many approaches were attemped to prevent the die failure. Good shaped products are forged successfully. This type process could by used as an advanced technique to replace conventional hobbing process of gear.
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Recently, the uses of Ceramic/metal bonded joints, resin/metal joints, adhesive joints, composite materials which are composed of dissimiliar materials have increased in various industry fields. Since the ceramic/metal bonded joints material is made at a high temperature, residual stress distributions due to differences in material properties were investigated by varying material parameters. The two dimensional finite element analysis was performed to study residual stress distribution in Si3N4/SM45C bonded joint with a copper interlayer between the silicon nitride(Si3N4) and the structural carbon steel(SM45C) and 4-point bending tests were carried out under room temperature. Fracture surface and crack propagation path were observed using scanning electron microscope and characteristics of its fracture was discussed.
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Application of bonded dissimilar materials in various industries are increasing. When these materials are used in structures, it needs to investigate strength evolution applying fracture mechanics. Al/Epoxy bonded dissimilar materials with an interface crack and an interface crack emanating from an edge semicircular hole were prepared for the static tests so that experiment of fracture toughness were carried out. Stress intensity factors of interface cracks in bonded dissimilar materials were computed with boundary element method(BEM) and the fracture criterion of mixed mode crack were analyzed. From the results, the fracture criterion and the method of strength evolution by the fracture toughness in Al/Epoxy bonded dissimilar materials were proposed.
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In this study, crush characteristics of thin-walled rectangular tube is investigated. The stiffness of the element is obtained from analytical moment-rotation relationship and approximated load-deflection relationship of thin-walled rectangular tube. A computer program is developed for the large deformation analysis of frame. An incremental displacement method is used in the program and at each incremental stage, the stiffness matrix of the total structure is checked with the state each element for bending and compression.
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In this paper, basic micro-mechanical properties of unidirectional CFRP composite shell such as bonding strength, fiber volume fraction and void fraction are measured and tensile strength test is performed with a fixture. And then fracture surfaces are observed by SEM. In case of basic micro-mechanical properties, bonding strength is reduce with decreasing of radius of each ply in a shell for the effect of residual stress, fiber volume fraction is smaller than plate, and void fraction is vise versa. For these reason, tensile strength of shell is smaller than plate fabricated with same prepreg. For failure mode shell has many splitted part along its length, and it is assumed that this phenomenon is caused by the difference of bonding strength for residual stress.
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Fatigue crack propagation behavior for variable load in high strength aluminum alloys was investigated in this study. The materials used in this study are aluminum 7075-T651 and 5052-H32 alloys. Crack length was measured from calibration curve, which was plotted by known crack length and resistance of standard specimens. Load was obtained from linear regression formula. Unloading elastic compliance method was ap;ied to check the crack closure and cracked area.
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In particle or short-fiber reinforced composites. cracking of the reinforcements is a significant damage mode because the broken reinforcements lose load carrying capacity. This paper deals with the load carrying capacity of intact and broken ellipsoidal inhomogeneities embedded in an infinite body and a damage theory of particle or short-fiber reinforce composites. The average stress in the inhomogeneity represents its load carrying capacity. and the difference between the average stresses of the intact t and broken inhomogeneities indicates the loss of load carrying capacity due to cracking damage. The composite in damage process contains intact and broken reinforcements in a matrix. An incremental constitutive relation of particle or short-fiber reinforced composites including the progressive cracking damage of the reinforcements have been developed based on the Eshelby's equivalent inclusion method and Mori and Tanaka's mean field concept. Influence of the cracking damage on the stress-strain response of the composites is demonstrated.
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In surface grinding, the conditions of the grinding wheel give a significant effect on the ground workpieces comparing with other metal removal processes. In this paper, to assist the development, a non-contacting optical method is introduced to make in-process measurements of scattering intensities from laser beam during surface grinding processes. This show indications of changes in surface texture of wheel working surfaces. Also, in order to determine the dressing time monitoring method of grinding wheel in surface grinding, a three-dimensional computer simulation of the grinding operation has been attempted based on the contact mechanism and surface-shaping system between the grinding wheel and the workpiece. The optical dressing time is determined based on the amount of the grain wear and work surface roughness.
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이경섭;조수영;오재한;이우선;최충석 97.1
We studied on the ultra thin L-$\alpha$ -DLPC by LB method. The$\pi$ -A isotherm of the L- e -DLPC was measured at the air-water interface varying with the compressing speed and amounts of solutions for spreading. The molecular arrangement of deposited films were evaluated by measuring the absorption with the UV spectrometer. And we made structures of metal(Au)/L-$\alpha$ -DLPC/Metal(Au) and examined electron through L-$\alpha$ -DLPC LB films by means of current-voltage(I- V) measurement -
Machining process introduces thermal deformation of a cutter, which affects the surface finish of the workpieces. By measuring the temperature distribution of the cutter, thermal stress and deformation of the cutter are simulated. In addition, surface roughness of workpiece is simulated by the surface-shaping system. The result shows that thermal deformation deteriorates the surface roughness.
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김재윤;김부근;김강언;정수태 267.1
We measured the dielectric properties with YMnO$_3$ ceramics using solution method based procedure via by citrate. The crystalline phases were determined using XRD. Also we observed morphologies of YMnO$_3$ ceramics using SEM. We proved the structure of YMnO$_3$ ceramics which is hexagonal. But lots of pores were observed the microstructure. It would be considered as volatile organic. The maximum density of YMn03 ceramics is obtained sintering temperature 135$0^{\circ}C$ and the ratio 0.95/1.05 of Y/Mn. But even though the density we obtained is the highest, that is lower than theoretical density because of remaining organics by citric acid. Dielectric constant and dissipation factor were improved as increasing sintering temperature and the Y/Mn ratio (0.95/1.05) -
The fine blanking is a process of press-working which makes possible to produce thick sheet metal parts of finished sheared surface and close dimensional accuracy over whole material thickness in single blanking operation. Fineblanked parts in general are characterized by their cleanly sheared surface over the whole stock thickness and accurate size for the specific functions. The fine blanking technology is urgently needed to remove secondary operations which are necessary in conventional blanking operation and cost reduction. In this study, the effect of material texture and vee-ring on parts for automobile is investigated by experimental observation and analysis.