코팅공구에 의한 원형곡면 선삭가공시 절삭특성

왕덕현,김원일,엄필환,Wang, Duck Hyun,Kim, Won Il,Eom, Phil Hwan 한국기계가공학회 2003 한국기계가공학회지 Vol.2 No.1

The experimental study for turning circular free fanned surface with TiN coated insert tool was conducted for different cutting conditions such as cutting speed, feed rate and depth-of-cut. For the fluctuation of 1.0mm depth-of-cut, the characteristics for machined surface and tool wear were less influenced by the feed rate and cutting speed than those of higher depth of cut. The higher surface roughness and surface precision were obtained in lower cutting speed. For the fluctuation of 1.5mm depth-of-cut, the higher surface roughness was obtained for the case of the lower feed rate of 0.05-10mm/rev and the higher cutting speed of 80m/min. For the fluctuation of 2.0mm depth-of-cut, the surface roughness and surface precision were too worse to machine the specimen And the flank wear on the tool was increased rapidly rather than the crater wear.

전극봉내 방전유 분사시스템에 의한 형조방전가공

왕덕현,우정윤 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.1

Experimental study of die-sinking electrical discharge machining(EDM) was conducted With rotating electrode system including inside hole for increasing the material removal rate(MRR). With the help of dielectric fluid flow through the inside according to the different internal diameter of the hole, the molten workpiece debris could be removed and flushed out during the EDM. Cold die alloy(SKD-11) was executed for different peak current and duty factor. From this study, the MRR was found to be increased with the peak current. The more MRR was obtained for the case of electrode inside diameter of l0mm, but the MRR was decreased as the diameter near at the 4mm and 6mm. The values of surface roughness and roundness were analyzed under various conditions, and these were affected by the inside diameter change of electrode.

곡면가공시 경사위치각 변화에 따른 공구변형과 형상정밀도

왕덕현,박희철 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.4

In this study, hemisphere and cylindrical shapes were machined for different tool paths and machining conditions with ball endmill cutters. Tool deflection, cutting forces and shape accuracy were measured according to the inclination position of the sculptured surface. As the decreasing of inclination position angle, the tool deflection was increased due to the decreased cutting speed when the cutting edge is approaching toward the center. Tool deflection when upward cutting is obtained less than that of downward cutting and down-milling in upward cutting showed the least tool deflection for the sculptured surface. Roundness values were found in the feast roundness error when down-milling in upward cutting. It is obtained the very little difference between 90° and 45° of inclination position angle. The best surface roughness value was obtained in upward up-milling and showed different tendency with tool deflection and cutting force. For down-milling, the cutting resistance of the side wall direction is larger than that of feed direction. Therefore, this phenomenon which is received over cutting resistance can be caused of chatter.

산화알루미늄-탄화티타늄(Al₂O₃-TiC) 세라믹 복합체의 방전가공

왕덕현,우정윤,윤존도,고철호,안영철,정영습 경남대학교 신소재연구소 1996 論文集 Vol.7 No.-

도전성 탄화티타늄 33무게%를 포함하는 산화알루미늄基 세라믹 복합체에 대한 방전가공을 시도하고 최적조건과 방전메카니즘을 조사하였다. 방전조건으로 전류 7-15A, 듀티팩터 0.24-0.45, 인가전압 40V를 사용하여 방전가공을 실시하였는데, 전류가 7A이하, 듀티팩터가 0.30이하일 때 가공이 잘 되었으며, 그 이상에서는 표면 파괴가 일어났다. 방전전류와 듀티팩터가 증가하면 공작물 제거속도는 증가하나 표면 거칠기도 역시 증가하는 것으로 나타났다. 방전가공 표면에 대한 미세구조 분석을 통하여 방전가공 메카니즘은 용융증발기구로 분석이 되었다. Alumina ceramic matrix composite containing electro-conductive titanium carbide of 33 weight % was machined by electrical discharge machining (EDM) method. The machining condition was 7-15A of current, 0.24-0.45 of duty factor, and 40V of applied voltage. When the current and duty factor were 7A and 0.30 or lower, respectively. the specimen were machined successfully. When the current and duty factor were higher. the specimen showed surface damage and fracture after machining. As the current and duty factor increased. the material removal rate(MRR) and maximum surface roughness increased. implying that the machining condition would be selected according to the requirement whether high speed machining or good surface finish is needed. By the microstructure analysis on the machined surface, the mechanism of machining was determined to be melting and evaporation.

와이어 방전가공에 의한 Ti-6AI-4V 합금의 기계적 특성

왕덕현,김종업 慶南大學校 附設 工業技術硏究所 2003 硏究論文集 Vol.21 No.2

티타늄합금 소재는 대개 가공상의 여러 가지 어려움이 따르며 일반 절삭가공에서는 공구의 마멸이 심하다. 이러한 절삭가공상의 난점을 해결하기 위해서는 특수가공법 증 와이어 방전가공이 필요하다. 가공조건인 방전인가전압, 인가전류, 방전시간, 방전휴지시간 및 오프셋량 등을 변화시켜가면서 1차, 2차, 3차 및 4차가공을 각각 수행하여 시편의 기계적 특성에 미치는 영향을 연구하였다. 방전에너지의 크기에 따라 거친가공에서 다듬가공 영역으로 이행함에 따라 변질층은 얇아지는 경향을 나타내었다. Titanium alloy generally has many difficulties in manufacturing and induces severe tool wear in general machining process. In order to solve these difficulties. wire discharge machining among nontraditional processes is possible machining process Different discharging process conditions as discharge voItage. discharge current, discharge time, discharge rest time, and offset value, process times from 1st through 4th out are respectively executed and the effects on the characteristics of each specimen are studied The changed layer showed to be thinner by transferring from rough process area to finishing. according to the magnitude of discharge energy.

가공경사면 위치에 따른 볼엔드밀가공과 회전식 형조방전가공 특성

왕덕현,김원일,박성은,박창수 한국공작기계학회 2002 한국생산제조학회지 Vol.11 No.5

In this study, work materials of the free form surface shape was machined by all ball end mil cutter according to the change of cutting location and depth, and the acquired data force, tool deflection and shape accuracy were analyzed. Cutting force results were obtained with tool dynamometer and tool deflection values were measured by a couple of eddy-current sensors. Shape accuracy was obtained by roundness tester and surface profile measuring machined. As inclination angel was decreased, cutting force was increased. Cutting force showed large value at 105˚ and 150˚. Tool deflection was less at down milling than at up milling, decreased at 45˚ and 120˚, and shown large tool deflection at 150˚. Roughness values were found to be bad in the inside of surface shape tool deflection. Surface accuracy was obtained better precision in down milling than in up milling.

탄화규소/알루미늄 금속계 복합재료의 형상방전가공

왕덕현,이윤경,우정윤,허보영 한국공작기계학회 1998 한국생산제조학회지 Vol.7 No.1

Conductive metal matrix composite(MMC) material of 30% silicon carbide particulate based on aluminum matrix was machined by die sinking electrical discharge machining(EDM) process according to different current and duty factor for reverse polarity of electrode. Material removal rate(MRR) was examined by process under various operating conditions. The surface morphology was evaluated by surface roughness parameter and scanning electron microscopy(SEM) research. The MRR was suddenly increased over 11 ampere of current, and it was slightly changed over 0.3 of duty factor. The maximum surface roughness of EDMed surface was affected by the duty factor. The SEM photographs of EDMed surface showed wide recast distribution region of melting materials as increased of current and duty factor.

주기적 이송속도 변화를 이용한 심공드릴가공

왕덕현,이윤경,김원일,김용제 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.6

Experimental study of drilling for duralumin A2024 was conducted with intermittently accelerated and decelerated fee-drate. It is achieved through a programmed periodic increase and decrease in the feedrate using a machining center. The following experimental results were performed with the objective of solving chip to disposal problems. In conventional drilling of aluminum, long continuous chips are produced with winding around the drill and causing difficulties in elimi-nating chips from the cutting zone. In order to acquire the basic data necessary to regulate the chip profile, the relationship between cutting variables and chip shape was investigated. The following conclusions arc established from the experimen-tal results. At a suitable feed fluctuation ratio. intermittently decelerated feed drilling proved successful in breaking chips to appropriate lengths while maintaining stable cutting. Thus, it is an effective method for improving chip disposal. The amplitude of the dynamic component of cutting force in intermittent feed drilling is influenced by the feed fluctuation ratio.

적층구조 복합재료의 절삭면 형상에 관한 연구

왕덕현,Wang, Duck Hyun 한국정밀공학회 1995 한국정밀공학회지 Vol.12 No.12

Machined graphite/epoxy surfaces were studied by using SEM (Scanning Electron Microscopy), surface profilometry and its analysis to determine suitable surface describing parameters for machined unidirectional and multidirectional laminate composite. The surface roughness and profile are found to be highly depdndent on the fiber layup direction and the measurement direction. It was possible to machine 90 .deg. and -45 .deg. plies due to the adjacent plies, which were holding those plies. It was found that the microgeometrical variations in terms of roughness parameters $R_{a}$ without $D_{y}$(Maximum Damage Depth) region and $D_{y}$are better descriptors of the machined laminate composite surface than commonly used roughness parameters $R_{a}$and $R_{max}$ The characteristics of surface profiles in laminate composite are well represented in CPD (Cumulative Probability Distribution) plot and PPD (Percentage Probability Density) plot. Edge-trimmed multidirectional laminate surfaces are Gaussian and random for profiles measured along the tool movement direction, they are periodic and non-Gaussian in the direction perpendicular to the tool movement.t.ent.t.

숫돌 형상 변화에 따른 연삭가공면 특성

왕덕현,김원일,강신엽,우정윤 경남대학교 신소재연구소 1997 論文集 Vol.9 No.-

숫돌 형상 변화에 따른 연삭가공시 나타나는 온도의 변화를 연삭가공면의 특성으로 파악하는 실험적 연구를 하였다. 숫돌의 형상은 슬롯형태로 폭과 각도의 변화에 의하여 변경시켰으며, 또한 일반숫돌인 경우 특성을 비교 분석하였다. 슬롯형 숫돌인 경우 슬롯의 폭이 10mm이고, 각도가 30°때 낮은 연삭온도를 나타내고 있었다. 표면거칠기 상태는 일반숫돌인 경우보다 슬롯형 숫돌일 경우 대체로 표면상태가 나쁘다는 것을 알았으며, 슬롯의 폭이 6mm이고 각도가 45°인 숫돌과 일반숫돌의 특성을 비교해 볼 때 유사한 경향을 나타내고 있었다. The characteristics of ground surface by different shapes of wheel were found by grinding temperature and surface roughness. The shapes of wheel are changed by slots, which has different width and helical angle, and compared with the case of general one. Lower grinding temperature was obtained for 30°helical angle and width of 10mm. The characteristics of surface roughness of slotted wheels were found to be rough, but the value of roughness for the slotted wheel with 45°helical angel and width of 6mm was similar tendency for the general wheel.