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.

마이크로 프로세서의 발달

박명순(朴明淳) 대한전기학회 1997 전기의 세계 Vol.46 No.9

低炭素 -W-Ni-Cr-Mo 合金鋼의 表面 硬化處理에 關한 硏究

朴明果 한국항공대학교 1991 論文集 Vol.29 No.-

國內古鐵市場에서 比較的 低價로 쉽게 구입할 수 있는 兵器材 古鐵을 表面硬化 조작을 통하여 SKD-11銅으로 代置하며 使用할 수 있는가 여부를 검토하였다. 炭素함유량이 낮은 관계로 表面層의 高硬度値를 얻기 어려웠다. 表面의 炭素集中增加方法으로 고체침탄 및 액체침탄 방법을 실시한 결과 고체침탄처리온도 925℃ 침탄시간 10Hr이 가장 적당하였으며 이때 Case depth는 2.5mm이었고, 경도치는 HRc-64를 얻었다. 액체침탄처리로서는 Case depth가 0.5mm 이내이므로 工具銅으로 使用하는데 硏磨上의 문제점이 있다. 그러므로 0.12% C, W, Ni, Cr, Mo 강은 고체침탄 및 담금질 처리하므로서 SKS, SKD와 같은 合金工具銅으로 代用하여 使用할 수 있다. Ordnance scrap materials such as tank body parts consisting of low carbon alloy steel(0.21%C, 0.8%W, 0.5%Cr, 1.3%Ni, 0.3%Mo) have great toughness and low hardness. The maximum attainable hardness of any steel depends on carbon content. Therefore the experiment has been carried out to study a hardening process of this alloy in application for manufacturing the high speed rotary shearing tool or similar tools. The important results obtained from the study are summerized as follows. 1. Under the pack carburizing process at 925℃ for 10hrs. We could take the case depth 2.5mm. By the guenching process the hardness of this alloy steel has increased up to H?C 64. 2. The case depth and carbon content could be increased by the carburizing time. When the process time took over 10 hrs, the carbon content of the surface reached to that of the hypereutectoid steel(0.9%c). In this case, the structure of case structure of case surface became a rough net work of brittle cementite. 3. The quenching process must be done by the two step quenching to control the rough austenite structure. The optimum quenching condition was obtained with the first quenching temperature at 900℃ and the second quenching temperature at 770℃.

燒結炭素鋼과 炭素鋼의 摩擦壓接에 關한 硏究

朴明果 한국항공대학교 1986 論文集 Vol.24 No.-

More recently, many reports have been made concerning to friction welding by carbon steel, but there are not a few fields uncultivated concerning the friction welding of carbon steel and Sintered carbon steel. Therefore, this study reported herein was to investigate the friction welding of SM25C and Sintered carbon steel, The materials used to φ12mm steels, and section of materials was finished machinning. The welding conditions controlled to change T₁=0.5~2.0 sec, P₂=9.0~24.0kg, f/mm² and the r.p.m, T₂are fixed 3660 r.p.m, 6.0kg,ㆍf/mm²and 10sec. According above welding conditions, this study was to investigated the mechanical properties and friction welding phenomenon for welding Joints by experimental analysis.

A17075-T651 판재에 변동하중 작용시 피로크랙 전파거동

박명과 한국항공대학교 1999 論文集 Vol.37 No.-

최근에 항공기, 압력용기 등과 같은 높은 신뢰성을 요구하는 기기나 구조물에 작용하는 하중은 일정진폭하중보다 하중진폭이 불규칙하기 변화되는 변동하중과 랜덤하중에 의하여 구조물에 미치는 영향이 크므로 이에 대한 피로크랙 전파거동의 검토는 매우 중요하다. 본 연구에서는 외팔보 굽힘에 대해 Al7075-T651 을 사용하여 초기하중은 일정한 상태에서 크랙이 전파한 후 블럭 하중으로 변동하중을 주어 크랙전파거동을 관찰하고 여러 가지 매개 변수를 이용하여 크랙닫힘거동, 크랙지연거동 등에 대하여 고찰하였다 Only a few of studies about the cantilever beam type of short crack can be found under cyclic tensile and compression load. Fatigue crack propagation behavior for variable load in 7075-T651 aluminum alloy were investigated in this study. The behavior of crack blosure and delay of crack propagation were also studied. Initial crack was made by applying cyclic load to a through crack with chevron notch. Crack length was measured from calibration curve which was area. The stress intensity factor range is independent of stress ratio due to the crack closure. Modified Paris Law can be obtained from stress intensity fator range and applied to design problems. .

마찰 용접한 국산 이종 구조용 강의 피로 크랙 전파에 관한 연구

박명과 한국 항공대학교 항공산업기술연구소 2001 航空宇宙産業技術硏究所 硏究誌 Vol.11 No.-

마찰용접은 두 재료사이에 마찰열을 발생시킨 후 압력을 가하여 두 재료를 강력하게 접합하는 방법이다.또한 단조효과도 있어 새로운 용접방법으로 특히 이종 재질 용접이 잘 된다는 많은 보고서가 있다. 마찰용접재는 마찰 가열시간에 따라 업셋량이 변화하고 강도도 이에 따라 변화한다. 또 하중을 받으면 미소 결함 부분에 슬립이 생기고 미소 크랙이 발생하여 전파하는데, 미소 초기 크랙의 발생 및 전파 과정과 미소 크랙의 전파속도를 관찰하였다. 따라서 두 종류의 국산 이종강을 최적의 조건으로 마찰용접한 후 접착부에서 미소하게 변화하는 조직을 검사하여 SM45C 모재, 열 영향부, 접합 금속부, STS304 열 영향부, 모재부에 φ0.3mm 구멍을 제작한 후 모재와 노치재의 피로한도를 구하였다. 각 미소용접부의 피로한도 값에 200%의 응력(고응력 레벨)을 가하여 구멍에서 발생하는 초기 크랙을 관찰하고 크랙이 전파하는 양상, 크랙 전파속도 및 응력확대계수의 의존성에 대하여 고찰하였다. Friction welding is essentially a variation of the pressure welding process but utilizes a novel heating method. In addition to the forging advantages, it has also been reported excellent for welding dissimilar materials. Therefore, this study reported on investigating fatigue behavior of the frictionally welded domestic structural steel SM45C and STS304 and was selected the optimal welding condition, simultaneously. After the structural steel welded frictionally, the artificial microholes were drilled at SM45C base metal SM45C HAZ welded zone STS304 HAZ and STS304 base metal for fatigue behavior tests. Also this study has been trade to investigate fatigue crack initiation and fatigue crack propagation, crack propagation rate and its dependency on stress intensity factor under high stress level of rotating bending stress.

쌀 두 가마 값의 월급시절

박명자(朴明子) 샘터사 1994 월간 샘터 Vol.25 No.10

"재직 근로자의 직무능력 향상 교육 적극 지원 필요"

박명학,Park, Myeong-Hak 대한기계설비건설협회 2013 기계설비 Vol.276 No.-

한국폴리텍I대학 서울강서캠퍼스 산업설비자동화과 박명학 교수는 산학협력의 중요성을 강조하는 현장교육 전도사다. 지난 5월 31일부터 6월 2일까지 3일간 서울특별시회 회원사 임직원을 대상으로 재직자 직무향상 교육을 실시한 박명학 교수를 만나보았다.

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 ????.

永同地域語의 形態音素的 考察

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