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.

볼엔드밀 가공시 이송변화에 따른 가공형상 특성

왕덕현,김원일,이윤경,임채열,우정윤,박창수 한국공작기계학회 2002 한국생산제조학회지 Vol.11 No.2

Due to the development of the CNC machine tool and CAM software, sculptured surface machining can be broadly used in die and mold industries and ball end milling process is often used for the sculptured surface machining. It is found out how feedrate affects the precision of the machining and also tried to study the most suitable feedrate in specific cutting condition. Two eddy current sensors were used for measuring tool deflections of X, Y axis, dynamometer for cutting force and roundness tester for roundness. It was found that the tool deflection is getting better as tool path is going to farther from the center of convex surface. The reason is that the cutting force is increased as the tool approaches to the center. Examining the roundness, cutting force and tool deflection characteristics, it was found that the most suitable feedrate is 90mm/min in convex surface and 120mm/min in concave surface.

전극선 성분 변화에 따른 냉간금형용강의 와이어방전가공 특성

왕덕현,정순성,Wang, Duck-Hyun,Jeong, Sun-Sung 한국기계가공학회 2003 한국기계가공학회지 Vol.2 No.2

In the experimental study, wire EDM was conducted for cold die steel by changing the Wire electrode, peak discharge current and number of finish cut. From the micro structure analysis of SEM photographs, the size of irregular welded and added component on the EDMed surface is decreasing and size of EDMed plane surface is increasing as the decreasing peak current and increasing number of finish cut. From the analysis of coating effect, Zn component is highly contained in Br and Zn Wire EDMed surface and copper component is highly contained in Br and Al wire EDMed surface. Hardness values are Increasing as the increasing peak current and decreasing the number of finish cut The value of hardness is decreasing as Cu, Al, Zn and Br wire electrode because of the residual austenite effect of solid solution copper on solidification, and finally EDMed surface has the highest hardness values for every wire electrode. Yield strength values becomes larger and bending strength values become smaller due to the increasing the hardness. These results are increased as increasing brittleness with hardness.

볼엔드밀가공에 의한 구면형상의 가공특성

왕덕현,김원일,이윤경,Wang, Duck Hyun,Kim, Won Il,Lee, Yun Kyeong 한국기계가공학회 2002 한국기계가공학회지 Vol.1 No.1

Hemisphere shapes were machined for different tool paths and machining conditions with ball endmill cutters. It was also found out how feedrate affect the precision of the machining and also tried to study the most suitable feedrate in specific cutting condition. 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. For down-milling, the cutting resistance of the side wall direction is larger than that of feed direction. It was found that the tool deflection is getting better as tool path is going to far from the center for convex surface.

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.

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.

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.

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.

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.

미세 볼엔드밀가공시 절삭력과 음향방출신호에 의한 공구 파손 검출 및 메커니즘

왕덕현,김원일,임정숙,Wang, Duck-Hyun,Kim, Won-Il,Lim, Jeong-Suk 한국기계가공학회 2004 한국기계가공학회지 Vol.3 No.3

A successful on-line monitoring system for conventional machining operations has the potential to reduce cost, guarantee consistency of product quality, improve productivity and provide a safer environment for the operator. In fine-shape machining, typical signs of tool problems such as vibration, noise, chip flow characteristics and visual signs are almost unnoticeable without the use of special equipment. These characteristics increase the importance of automatic monitoring in fine-shape machining, however, sensing and interpretation of signals ar more complex. In addition, the shafts of the mini-tools break before the typical extensive cutting edge of the tool gets damaged. In this study, the existence of a relationship between the characteristics of the cutting force and tool usage was investigated, and tool breakage detection algorithm by LabVIEW was developed and the following results are obtained. It was possible to use a relative error compare which mainly used in established experiment and investigated tool breakage detection algorithm in time domain which can detect AE and cutting force signals more effective and accurate.