이종강의 마찰압접시 압접시간 변화에 따른 강도거동-SM45C와 SUS304재의 경우

박명과,박명과 대한기계학회 1987 대한기계학회논문집 Vol.11 No.5

본 연구에서는 국산 구조용 강인 SM45C와 SUS304재를 마찰가열압력과 업셋압 력을 서로 변화시키고 업셋시간을 2초로 고정하여 압접시간 10초를 기준으로 하여 변 화시키면서 마찰압접한 후 압접시간 변화에 따른 인장강도의 변화와 업셋량 변화에 따 른 인장강도 및 굽힘강도를 고찰하였다.또 최고 강도치를 나타내는 압접조건을 구 한 후 미소 경도치 및 이종재의 압접부에서 미소하게 변화하는 조직변화도 함께 고찰 하였다. Friction welding is a fusion process in which the necessary heat is generated by clamping one of the two pieces to be welded in a stationary chuck and rotating the other at high speed with an axially applied load. It is essentially a variation of the pressure welding process but utilizes a novel heating method. In addition to the foregoing advantages, it has also been reported excellent for welding dissimilar materials. Therefore, this study reported on investigating the strength behavior for the frictionally welded domestic structural steel SM45C and SUS304. The results obtained by the experiments are as follows. (1) The highest tensile strength of the best friction welded specimen (B4) is about 3% lower than that of SM-45C base metal, and 9% lower than that of SUS304 base metal. The heat treated specimens (850.deg.C 1hr A.C) have almost same value of tensile strength. (2) The strain of SM45C base metal is 27.3% and that of SUS304 is 42%, that of the best friction welded specimen (B4) appeared as 11.9% which is about 50% lower than the base metal, so, this same phenomenon apeared in all the other welding conditions. (3) The bending strength of SM45C base metal is 123kgf/mm$^{2}$ and that of SUS304 is 127kgf/mm$^{2}$. The best specimen (B4) appeared as 121kgf/mm$^{2}$ which is almost same bending strength for both base metals. (4) The friction welded condition involving maximum strength is determined by P$_{1}$=8kgf/mm$_{2}$, P$_{2}$=22kgf/mm$_{2}$, T$_{1}$=10sec, T$_{2}$=2sec, and amount of upset 7.6mm. (5) The interface of two dissimilar materials are mixed strongly, and welded zone is about 1.03mm and also the heat affected zone is about 2.36mm at SM45C while about 1.85mm at SUS304, therefore the welded zone and heat affected zone are very narrow to compare with those of the other welding materials.

尙州地域語의 音韻硏究

朴明淳(박명순) 서원대학교 미래창조연구원 2003 인문과학연구 Vol.12 No.-

尙州地域語의 形態音素的 考察

朴明淳(박명순) 서원대학교 미래창조연구원 2002 인문과학연구 Vol.11 No.-

永同地域語의 形態音素的 考察

朴明淳(박명순) 서원대학교 미래창조연구원 2001 인문과학연구 Vol.10 No.-

摩擦壓接한 國産 異種鋼의 疲勞크랙傳播에 관한 硏究

朴明果 한국항공대학교 1992 論文集 Vol.30 No.-

國産 構造用鋼인 SM45 C와 SUS 304 材를 最高强度値가 나타나는 壓接條件에서 摩擦壓接한 후 兩材料의 熔着金屬部, 熱影響部, 母材部 소정의 장소에 Ø0.3의 人工微小圓孔을 加工한 試驗片을 토대로 疲勞크랙의 發生 및 크랙傳播擧動을 應力레벧의 高低를 고려하여 고찰하였고 應力擴大係數를 구하였다. Domestic dissimilar structural steels, SM 45 C and SUS 304 were friction welded under optimal welding condition and the micro-artificial holes were drilled at SM 45 C base metal, SM 45 C HAZ, welded zone, SUS 304 HAZ, and SUS 304 base metal for fatigue behavior tests. In this study, the fatigue limit and the behavior of micro-crack propagation, crack propagation rate, and its dependency on stress intensity factor under the low stress level and high stress level of bending stress have been investigated. The results obtained are as follows. (1) The fatigue strength of the portion of SM 45 C B. M., SM 45 C HAZ, welded zone, SUS 304 HAZ and SUS 304 B. M. on notched friction welded specimens are 20 ㎏f/f㎟, 32㎏f/㎟, 27㎏f/㎟, 29㎏f/㎟, and 29㎏f/㎟, respectively. (2) The fatigue strength of welded zone of unnotched and notched specimens are 32.5㎏f/㎟, and 27㎏f/㎟, respectively. (3) Micro-crack initiation in the welded zone, HAZ, and each base metals occurrs simultaneously in front and rear of micro-hole tips in the view of the rotational directions. (4) Fatigue crack propagates more slowly in the welded zone than in another portions of specimen, regardless of the magnitude of the stress level. (5) Fatigue crack propagation rates were plotted as a function of stress intensity range. The value of m in the equation da/dN= C(△K)?? was found to range from 2.09 2.55 in this study.

항공기 구조시험

박명과 한국항공대학 항공문제연구소 1992 航空問題硏究所 硏究誌 Vol.2 No.-

Under Cut 齒形을 갖는 小齒車의 應力解析

朴明果 한국항공대학교 1979 論文集 Vol.15 No.-

The measurement of the stress on the root of tooth was made with under cut gear by photo-elastic method in following case. First, in case weight was operated in the tangential direction of the pitch circle in above tooth. The result was as follows 1. When the weight was operated on the end of tooth at normal direction, the experimental value of the stress of under cut tooth root was 41.2% higher than that of the theoritical value (Lewis formula). 2. When the weight was operated in the tangential direction of the pitch circle above tooth, the experimental value of the stress was only 0.7% higher than that of the theoritical value. 3. In case weight was operated on the end of tooth, the stress value was effectively large by the under cut. 4. We can see that there is some danger in designing the under cut gear by Lewis formula because experimental stress value came out to be 41.2% higher than those of the Lewis formula. 5. As there is appeared in 1 to 2, Undercut should be avoided if it is possible, and we can design small value of Z?? to take pressure angle (α) according to ????.

構造用鋼의 摩擦壓接에 關한 硏究

朴明果 한국항공대학교 1984 論文集 Vol.22 No.-

Welding joint of Austenite steel and carbon steel are largely used when corrosion resistance and heat resistance are required, such as moter shaft, engine valve etc. So this study deals with the experimental results of the friction weld Joints and their mechanical properties to Obtain the improved optimum welding condition for Joining the structural SM 45C-SUS304. The Welding parameters ⅰ. e, frictional and upsetting pressure(P₁,P₂) and frictional and upsetting time(t₁,t₂)are varied over wide ranges and the workpiece diameters and rotational speed are kept constant at ø12.5 and 3000r. p. m., recpectively. The results obtained by the experiments are as follows. 1. The thrust-gage Pressure diagram of P₁ξP₂V. S. work-Piece diameters applicable to the practical friction welding operation was made for improving the productivity. 2. The optimum welding condition to attain sufficiently high tensile strength and bend ductility was experimentally determined as the following. Speed=3000r. p. m. P₁=8㎏·f/㎟ P₂=22㎏·f/㎟ t₁=10sec t₂=2sec total upset 7.6㎜ 3. The present test results shows that the tensile strnegth of the friction welded metal is about 6%lower than that of base metal and bending strength is same as alnost base metal. 4. Microscopic examination of the weld joints friction welded under optimum condition revealed that the heat effeeted zone is very narrow and has a fine grained intermixed structure with no melt product or grain growth and without any welding defacts. 5. Hardness of welded interface was more increased according to the radial derection from the center.

電弧熔接한 스프링鋼의 機械的 性質에 關한 硏究

朴明果 한국항공대학교 1980 論文集 Vol.17 No.-

It is seldom to obtain the information of the Arc Welded spring steel, because most of the previous investigators have been used the specimen of other welding method. All specimens were annealed from 750℃ (After 30 Min. Furace Cooled) after welding with electrode and the specimens was tested by hardness, impact, and fatigue test. Therefore the following Conclusions are acquired. 1. The hardness of welded part is the highest as R??=18.9 and the hardness of heat effected part appeared to higher than base metal part. 2. As the impact value is increasing about 28% than base metal, It is Possible to weld spring steel to operate impact load. 3. The fatigue strength is decreasing about 39% than base metal and the section of fatigue fracture appeared in the slewing Phenomenon.

구조용강의 마찰용접시 업셋량 변화에 따른 강도거동

박명과 한국항공대학교 1994 論文集 Vol.32 No.-

마찰용접이란 용접하고자하는 두 재료를 접촉하고 가압하면서 용접면에 상대운동을 부여하여 마찰용접면 근방을 접합가능한 온도에 도달시켜 그 후 상대운동을 정지시키고 용접을 행하는 고온용접법의 일종으로서 가열고상용접법이다. 이 용접법은 특히 이종재료의 접합에 있어서 우수한 용접 이음을 얻을 수 있다. 오오스테나이트계 재료와 탄소강의 용접은 내식성 내열성을 중요시하는 용도에 많이 사용되어 수중모터축이나 엔진밸브, 항고기 부속품에 많이 이용되고 있다. 본 실험에서는 SM45C와 SUS304재를 선택하고 회전수3000rpm으로 SM45C를 회전시켜 마찰 용접하였다. 이때에 업셋량 변화에 대한 강도변화와 열처리 후에 강도변화를 고찰하기 위하여 가열시간 10sec를 기준하여 가열시간을 변화시키면서 업셋량 변화를 고찰하였으며 업셋량 변화에 따라 인장 강도 및 파단며을 조사하였다. 업셋량과 인장강도 밈 굽힘강도와의 관계를 조사하였으며 특히 최고 강도치를 나타내는 용접조건을 함께 검토하였다. Friction welding is a fusion process in which the necessary heat is generated by clamping one of the two pieces to be welded in a stationary shuck and rotating the other at high speed with an axially applied load. It is essentially a variation of the pressure welding process but utiliges a novel heating method. In addition to the foregoing advantages, it has also been reported excellent for welding dissimiar materials. Therefore this study reported on investigating the strength behavior for the frictionally welded structural steel SM45C and SUS304. The results obtained by the experiments are as follows. 1) The highest tensile strength of the best friction welded specimen(B4) is about 3% lower than that of SM45C base metal, and 9% lower than that of SUS304 base metal. The heat treated specimens(850℃ 1hr, A.C) have almost same value of tensile strength. 2) The strain of SM45C base metal is 27.3% and that of SUS304 is 42%, that of the best friction welded specimen(B4) appeared as 11.9% which is about 50% lower than the base metal, so this same phenomenon sppeared in all the other welding conditions. 3) The bending strength of SM45C base metal is 1205MPa and that of SUS304 is 1245MPa. the best specimen(B4) appeared as 1187MPa which is almost same bending strength for both base metals. 4) the friction welded condition involving maximum strength is determined by P?=78MPa, P?=261MPa, T?=10sec, T?=2sec, and amont of upset 7.6mm. 5) The interface of two dissimilar materials are mixed strongly, and welded zone is about 1.03mm and also the heat affected zone is about 2.36mm at SM45C while about 1.85mm at SUS304, therefore the weldee zone and heat affected zone are very narrow to compare with those of the other welding materials.