http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
맹민재 한국안전학회 2001 한국안전학회지 Vol.16 No.5
Wire electrical discharge machining experiments in conducted to investigate characteristics of acoustic emission (AE) and electrical discharge energy due to current peak (I$_{p}$), pulse on time($\tau$/on/). The AE signals are obtained with a sensor attached to workpiece side. Machining states are identified with scanning electron microscopy and residual stress analyzer. It is demonstrated that the residual stress provide reliable informations about the machining states. Moreover, machining states can be detected successfully using both the residual stress and AE count rate.e.
유동층 연소로 내에서 수평전열관의 열전달 특성에 관한 연구
맹민재,정준기,정태용 대한기계학회 1995 대한기계학회논문집 Vol.19 No.9
The objective of this study is to get the basic data for the development of fluidized bed combustor. For this purpose, various rake angles(.theta.=20.deg., 25.deg., 30.deg., 35.deg.) of finned tubes and a smooth tube were installed horizontally in the fluidized bed combustor of 410*250mm. The effect of fluidized bed temperature, superficial velocity in bed, size of bed materials, rake angle of finned tubes on the heat transfer coefficient was experimentally investigated. The following results were obtained. (1) Under the fluidized bed temperature(750.deg. C-900.deg. C), and the gas velocity in bed(1.1-2.8m/sec), The highest heat transfer coefficient was measured with the rake angle of finned tubes was .theta.=25.deg. and .theta.=35.deg. for the average fluidized material particle size of 1.22mm and 1.54mm, respectively. Generally, the heat transfer coefficient of finned tubes is 1.4 to 2.4 times larger than that of smooth tubes. (2) The size of bed materials influences the rake angle of finned tubes which can have the highest heat transfer coefficient. As the temperature in bed gets higher, the effect of the rake angle of finned tubes on the heat transfer coefficient becomes greater.
선삭가공에서 공구마멸에 따른 절삭력과 AE 신호의 특성 연구
맹민재,정준기 한국공작기계학회 1995 한국생산제조학회지 Vol.4 No.2
In order to achieve the automation and untended system of manufacturing process, it is necessary that the monitoring system check up the disorder of machine tool or the conditions of tool wear for the maximum use of cutting tool. In the metal cutting process, AE signal is detected by AE sensor, then amplified and transmitted to an Locan-AT. The experiment was performed to SM25C and STS304 steels at uniform feedrate, cutting speed and depth of cut. The results of experimental data apparently showed emission intensity vary due to increasing of tool wear at the 165kHz, 200kHz in SM25C and 140kHz, 165kHz, 200kHz in the STS304 respectively. Therefore, it is possible to predict the tool wear. This study is intended to suggest the way to the automation and untended system of machine tool through the system monitoring tool wear by using AE signal.
맹민재,정준기 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.5
Turning experiments are conducted to investigate characteristics of acoustic emission due to wear of the coated tool. The AE signals are obtained with a sensor attached to tool holder side. Tool states are identified with scanning electron microscopy and optical microscopy. It is demonstrated that the AE signals provide reliable informations about the cutting processes and tool states. Moreover, tool wear can be detected successfully using the AE-RMS.
맹민재,정준기 韓國工作機械學會 2000 한국생산제조학회지 Vol.9 No.4
Even in a fully automated factory, many deburring operations are carried out manually. To remove or minimize the burr effectively or automatically, understanding of the burr formation which occur at the exit stage of machining is necessary. Burrs can be formed on the feed mark ridges and the edges of the machined parts in machining operations. These burrs are undesirable in terms of the surface quality, the precise dimensioning of the machined parts and the safety of operators. This paper demonstrates the effectiveness of using end mill tool on minimizing the exit burr formation in machining. In particular, the experimental relationships between the size of exit bun and the cutting parameters are established in end mill machining. Methods to control the size of exit burr are then explained.