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RISS 인기검색어
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- 저자 : 서남섭 (검색결과 68 건)
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徐南燮 전북대학교 공업기술연구소 1975 工學硏究 Vol.4 No.-
The mild steel is largely used as machine elements. Even though the tensile stress, compressive stress, shearing stress, and etc, are in the allowable stress, the machine elements are often broken when they are impacted. When they are jointed by welding. the phenomena are severer. Then there are several kinds of welding and i studied on the friction welding. They are almost the same as those of base metal except impact strength. Only Charpy impact strength is largely decreased. This report is published to find out the condition by which the impact strength is increased largely. In the case of carbon steel as welded, the cause of its impact strength decrease is considered the grain growth of structure. S20C mild steel specimens were treated by heating varying the conditions of heating and the impactest were made with Charpy impact tester. The impact strength is largest when the specimens are heated to 870℃ during 1 hour and cooled to 650℃ in the oven and reheated to 870℃, repeating three times in the same way. That is, its strength is 7.217 kg-m/㎠, while the strength of as welded metal is 4.5 kg-m/㎠. And on the above heating condition the structure of the friction welded joints is finest, too.
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徐南燮,鄭寅聖 전북대학교 공업기술연구소 1978 工學硏究 Vol.8 No.-
When friction welding is actually applied to parts of machines their mechanical strength is very important. It has been reported that the tensile, bending and fatique strength are almost equal to that of the base metal, however the impact strength is much smaller by friction welding, which is much brittler at low temperature. This study shows how the impact strength of the friction-welded mild steel at low temperature is affected by the heat treatment. The used welding machine was of conventional type and the experimental range of the welding factors was the following When friction welding is actually applied to parts of machines their mechanical strength is very important. It has been reported that the tensile, bending and fatigue strength are almost equal to that of the base metal, however the impact strength is much smaller by friction welding, which is much brittler at low temperature. This study shows how the impact strength of the friction-welded mild steel at low temperature is affected by the heat treatment. The used welding machine was of conventional type and the experimental range of the welding factors was the following Rotational speed : 3000r.p.m. Heating pressure : 4kg/mm_2 Upsetting pressure : 4kg/mm_2 Heating time : 6sec Upsetting time : 3sec Burn-off distance : 5mm And the condition of the heat treatment was A testpice : exposed 1 hour at 650℃ and then cooled in the oven B testpice : exposed 5 hours at 450℃ and then cooled in the oven C testpice : exposed 1 hour at 450℃ and then cooled to 300℃, reheated to 450℃, exposed 1 hour and then cooled in the oven. The testpices heattreated as the above were impacted at the temperature "25℃, 0℃, -20℃, -40℃, -60℃, -80℃, -100℃, -125℃" with the following results. (1) The impact strength is much increased by the heattreatment. (2) At the transition temperature the effect of the heattreatment is very small, while at the low temperature(below -100℃) the effect is increased.
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徐南燮,梁均懿 전북대학교 공업기술연구소 1984 工學硏究 Vol.15 No.-
The object of the study is to discuss the effect of surface active substances on the mechanism of chip formation in orthogonal cutting. Rehbinder effect has been as a phenomenon that the mechanical strength reduces when the metal is exposed in polar organic environment or the surface of metal is coated with some polar organic substances. In this report, the effect of surface active medium(magic ink)upon the machanism of chip formation on the orthogonal cutting of copper and the mechanical properties of the work material are experimentally discussed with various rake angles. Under the condition of polar organic environment the experimental results are as follows; 1)The smaller the depth of cut is and the smaller the tool rake angle, the reduction ratio of cutting force become more conspicuous. 2)The friction angle on the tool face is not affected by depth of cut and the compositions of polar organic material. 3)The rake angles being increased, the shear strain on the shear plane is decreased. 4)The roughness of cut surface is smaller with the increase of a tool rake angle, but the improvement of a cut surface is greater when the rake angle is smaller.
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서남섭,양균의 대한기계학회 1986 대한기계학회논문집 Vol.10 No.1
Cutting oil cools the chip and a tool as well as lubricates the chip-tool interface, the flank and machined surface. Rehbinder effect has been known as a phenomenon, the reduction of mechanical strength, when the metal is exposed to a polar organic environment or the surface of metal is coated with some polar organic substances. About the cause of Rehbinder effect there have been many different ideas by Rehbinder, Shaw, Barlow, Sakida and etc. In this report, the efect of polar organic substance( $C_{6}$ $H_{5}$C $H_{3}$+ $C_{6}$ $H_{4}$(C $H_{3}$)$_{2}$+ $C_{4}$ $H_{9}$OH+ $C_{6}$ $H_{12}$ $O_{2}$) (magic ink) upon the mechanism of chip formation on the orthogonal cutting of copper and mechanical properties of the work material are experimentally discussed with various rake angles. As expected no lubrication action could be noticed, but the shear angle increased and the cutting force and shear strain on the shear plane decreased, therefore the work material must be embrittled under polar organic substance.substance. 본 논문에서는 도포하기가 용이한 극성유기물질인 magic ink( $C_{6}$ $H_{5-}$ CH/13+ $C_{6}$ $H_{4}$(C $H_{3}$)$_{2}$+ $C_{4}$ $H_{9}$OH+ $C_{6}$ $H_{12}$ $O_{2}$) 를 Rehbinper 효과가 큰 동에 도포하고, 공구경사각을 변화시켜 매 절삭깊이마다 반복 2차원절삭을 실시하여 절삭기구, 절삭저항의 변화, 전단면의 전단변형율, 전단에너지 및 마찰에너지등의 변화를 상호관련시켜 분석하므로서 절삭성의 향상원인을 규명코저 한다.다.
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徐南燮 전북대학교 공업기술연구소 1976 工學硏究 Vol.6 No.-
The steel which contains 2% C is called the mild steel, whose strength is large and so it is used very much to the parts which need high strength. And as weldability of the mild steel is very excellent, it is used for welded joints more. But one of the negative points is that it has brittleness and remained stress. So it has to be heat-treated to decrease or remove them. According to othert' reports, it is said that for the welding joints of mild steel it has to be heat-treated at 625±25℃ for one hour. In this experiment the testpieces were done at 625℃ for one hour, two hours continuously and two hours one by one paroidically. After the heat treatment the tensile, bending, impact strength were compared with one another, and with those of non-heattreated welding joints and parent metals, too. The strength was improved to more than 90% of that of the parent metal, and the hardness was decreased to 92% of that of the parent metal, both of them proportional to the duration of the heat treatment. Especially when it was heat-treated periodically, the improvement of the strength was much higher and so was the hardness.
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徐南燮,李聖哲 全北大學校 1979 論文集 Vol.21 No.-
Weld joints of austenite stainless steel and carbon steel are largely used when corrosion resistance and heat resistance are required, such as motor shaft, engine valve, etc. Dissimilar weld joints are attended with the change of strength owing to the element diffusion at welding. When AISI 303, austenite stainless steel and S20C, carbon steel were welded by friction welding, the movement of carbon element and the fatigue strength of joint were studided for the following cases; 1) as welded, 2) 650℃-7hour heat treatment and air cooled, 3) 650℃-20hour heat treatment and air cooled, with following results. Carbon element is diffused from S20C to AISI 303, being produced the decarburized zone on S20C side and the carburized zone on AISI 303 side. The width of decarburized zone is more than that of carburized zone at same temperature of heat treatment. All the fatigue strength in the above conditions of heat treatment is decreased comparing to as welded. The position of the largest stress concentration ratio and the rupture of test piece is coincided. This is due to the movement of carbon element and the coarse grain zone forming of ferrite.
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徐南燮,金種澤 전북대학교 공업기술연구소 1983 工學硏究 Vol.13 No.-
The objects of the study are to oberve the effects of cutting parameters on the cutting force, establish the experimental equation and compare the experimental equation with theoretical one. Merchant and Lee showed their research results theoretically and experimentally on the milling with one tooth cutter. A Quartz multi-component dynamometer (made in Swiss) with a charge amplifier was used to examine the necessary cutting force. The high speed steel plain cutter was and work material was SS41. Results are following: 1) The cutting force was proportional to the feed. depth of cut and velocity exponentially, and the following equation was developed: F_R = 101 f^0.54d^0.73v^-0.93 2) It is supposed that the experimental value was smaller than the theoretical one owing to the size effect and impact. 3) The cutting force ratio(F_y/F_x)was proportional to the cutting speed and inversely p개portional to the speed.
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수두와 직경을 변수로 한 orifice의 유량계수 측정
서남섭 군산대학교 1969 群山水産專門大學 硏究報告 Vol.3 No.2
The opening which is in the wall or in the bottom of a tank and and through which fluid flows is called an orifice, and the actual velocity is slower than the theoretical velocity and the actual diacharge is smaller than the theoretical discharge. Therefore the theoretical equation must be amended in order that it may be served for the practical use. The velocity is affected by the sectional area, the shape, the head and the position of an orifice. Changing only heads and diameters as variables, I made the experiment. The result of the experiment shows:the larger the heads and the diameters are, the smaller the discharge coefficients are.
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