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유전자 알고리즘을 이용한 마이크로밀링공구 수명 최적화에 관한 연구
구준영(Joon-Young Koo),김영준(Young-Jun Kim),장수훈(Su-Hoon Jang),김정석(Jeong-Suk Kim) 한국생산제조학회 2017 한국생산제조학회지 Vol.26 No.5
The micro-scale milling process is suitable for the machining of micro-scale three-dimensional shapes and is particularly effective for the machining of micro-channels and grooved patterns. Tools should be changed at an appropriate point in time to maintain high quality of machined surfaces and to improve productivity. Moreover, machining conditions that are optimized in terms of the tool life are required for the efficient use of micro-milling tools. In this paper, we propose a method for predicting the tool life of a micro-milling tool and establishing optimal machining conditions. Machining conditions are determined using a central composite design. An equation is derived for the tool life, and the effect of variables on the tool life is evaluated by carrying out a regression analysis on experimental results. Genetic algorithm is used to determine optimal machining conditions. The results of this study can be used to enhance machining efficiency in micro-scale milling processes.
인코넬 718의 터닝가공에서 인서트 절입각이 경계마모 억제에 미치는 영향
구준영(Joon-Young Koo),김동규(Dong-Gyu Kim),강익수(Ik-Soo Kang),정윤철(Yun-Chul Jung),김영흠(Young-Heum Kim) 한국생산제조학회 2020 한국생산제조학회지 Vol.29 No.6
Inconel is a representative super-alloy with excellent heat resistance, abrasion resistance, and corrosion resistance, and used as a material for key aerospace components. It is a difficult-to-cut material with a very short tool life owing to its low thermal conductivity, excellent high temperature strength, and excellent work hardening ability. In this study, machining characteristics were identified based on the entering angle in the Inconel 718 turning process. A finite element simulation was performed to derive the effective entering angle range to suppress notch wear, which is the main cause of end-of-tool life. Additionally, cutting temperature, stress, and pressure distribution were analyzed. Through comprehensive analysis of finite element simulations and machining experiments, an effective entering angle range was derived to suppress notch wear in the turning process of Inconel 718.
Al7050-T7451 소재의 밀링가공에서 반응표면법에 의한 가공성평가 및 가공안정화를 위한 절삭조건선정
구준영(Joon-Young Koo),조문호(Mun-Ho Cho),김혁(Hyuk Kim),김정석(Jeong-Suk Kim) 한국생산제조학회 2014 한국생산제조학회지 Vol.23 No.3
Aluminum alloy is a core material for structural parts of aircraft and automobiles to reduce the weight and maintain high specific strength. This study evaluates the machinability and investigates the optimal cutting conditions considering the surface integrity and productivity for Al7050-T7451 milling. The machining variables considered are the feed per tooth, spindle speed, axial depth of the cut, and radial depth of the cut. The machinability evaluation of Al7050-T7451 is conducted by analyzing the cutting force signals, acceleration signals, AE signals, and machined surface conditions. The optimal cutting conditions are determined by analyzing the experimental results using response surface methodology for stable machining considering the productivity and surface integrity.
알루미늄 합금(Al7075-T651)의 얇은 벽 고속밀링 가공 시 가공표면 상태와 가공변형 특성
구준영(Joon-Young Koo),황문창(Moon-Chang Hwang),이종환(Jong-Hwan Lee),김정석(Jeong-Suk Kim) 한국생산제조학회 2016 한국생산제조학회지 Vol.25 No.3
Al alloys are useful materials having high specific strength and are used in machining of parts having thin-walled structures for weight reduction in aircraft, automobiles, and portable devices. In machining of thin-walled structures, it is difficult to maintain dimensional accuracy because machining deformation occurs because of cutting forces and heat in the cutting zone. Thus, cutting conditions and methods need to be investigated and cutting signals need to be analyzed to diagnose and minimize machining deformation and thereby enhance machining quality. In this study, an investigation on cutting conditions to minimize machining deformation and an analysis on characteristics of cutting signals when machining deformation occurs are conducted. Cutting signals for the process are acquired by using an accelerometer and acoustic emission (AE) sensor. Signal characteristics according to the cutting conditions and the relation between machining deformation and cutting signals are analyzed.
티타늄 합금의 얇은 벽 밀링가공에서 가공방법에 따른 진동특성 및 가공품질에 관한 연구
김종민,구준영,전차수,Kim, Jong-Min,Koo, Joon-Young,Jun, Cha-Soo 한국기계가공학회 2022 한국기계가공학회지 Vol.21 No.6
Titanium alloy (Ti-6Al-4V) has excellent mechanical properties and high specific strength; therefore, it is widely used in aerospace, automobile, defense, engine parts, and bio fields. Particularly in the aerospace field, as it has a low specific gravity and rigidity, it is used for the purpose of increasing energy efficiency through weight reduction of parts, and most have a thin-walled structure. However, it is extremely difficult to machine thin-walled shapes owing to vibration and deformation. In the case of thin-walled structures, the cutting forces and vibrations rapidly increase depending on the cutting conditions, significantly affecting the surface integrity and tool life. In this study, machining experiments on thin-wall milling of a titanium alloy (Ti-6Al-4V) were conducted for each experimental condition with different axial depths of cut, radial depth of cut, and machining sequence. The machining characteristics were analyzed, and an effective machining method was derived by a comprehensive analysis of the machined surface conditions and cutting signals.
티타늄 합금의 밀링가공에서 평 엔드밀의 헬릭스각과 경사각의 영향 분석
예동희(Dong-Hee Ye),구준영(Joon-Young Koo),박영군(Young-Koon Park),김정석(Jeong-Suk Kim) 한국생산제조학회 2015 한국생산제조학회지 Vol.24 No.5
In this study, the effect of the helix angle and rake angle of a flat end-mill in the milling of titanium alloy was investigated. Tool shape parameters such as helix angle and rake angle affect the cutting force, cutting zone temperature, vibration, and chip flow mechanism, which in turn determine tool life, surface integrity, and dimensional accuracy of the milling process. To investigate the effect of the helix and rake angles, a certain range of parameters was selected, and three-dimensional tool models were generated for finite element analysis (FEA) for each case. The cutting force and pressure on the tool flank face and rake face were investigated by FEA. Further, several tool models were proposed for machining tests. The cutting force characteristics were investigated by the machining tests.
알루미늄 합금(Al6061-T6)의 마이크로밀링가공에서 버 발생과 신호 특성의 상관관계 분석
김현중(Hyun-Jung Kim),구준영(Joon-Young Koo),윤지찬(Ji-Chan Yoon),이종환(Jong-Hwan Lee),김정석(Jeong-Suk Kim) 한국생산제조학회 2016 한국생산제조학회지 Vol.25 No.6
The formation of micro-burrs in micro-milling processes causes several problems related to productivity and surface integrity. It should be minimized and suppressed by effective monitoring of the cutting conditions. This paper presents the correlation between the micro-burr length and cutting signals in the micro-milling process of an Al alloy (Al6061-T6). The acoustic emission (AE) signals and cutting force signals are acquired during the experiments. The characteristics of the cutting signals are obtained by analyzing the AE root mean square value and resultant cutting force. In addition, the micro-burr length is measured according to the cutting conditions by analyzing a scanning electron microscopy image of the machined surface. The results of this study can be used to enhance the surface quality of micro parts.
티타늄 합금(Ti-6A1-4V)의 밀링가공에서 L자형 얇은 벽 구조의 가공품질 향상
김종민(Jong-Min Kim),구준영(Joon-Young Koo),전차수(Cha-Soo Jun) 한국기계가공학회 2021 한국기계가공학회지 Vol.20 No.11
Titanium alloy (Ti-alloy) is widely used as a material for core parts of aircraft structures and engines that require both lightweight and heat-resistant properties owing to their high specific stiffness. Most parts used in aircraft have I-, L-, and H-shaped thin-walled structures for weight reduction. It is difficult to machine thin-walled structures owing to vibrations and deformations during machining. In particular, cutting tool damage occurs in the corners of thin-walled structures owing to the rapid increase in cutting force and vibration, and machining quality deteriorates because of deep tool marks on machined surfaces. In this study, milling experiments were performed to derive an effective method for machining a L-shaped thin-walled structure with Ti-alloy (Ti–6Al–4V). Three types of machining experiment were performed. The surface quality, tool wear, cutting force, and vibration were analyzed comprehensively, and an effective machining method in terms of tool life and machining quality was derived.
오정규(Jeong Kyu Oh),김평호(Pyeong Ho Kim),구준영(Joon Young Koo),김덕환(Duck Whan Kim),김정석(Jeong Suk Kim) 한국생산제조학회 2014 한국생산제조학회지 Vol.23 No.4
The continuous chip generated in cutting process deteriorates workpiece, tool, and machine tool system. It is necessary to treat this continuous chip in ductile material machining condition for stable cutting. This paper deals with the chip control method using acoustic emission(AE) signal in pure copper turning operation. AE raw signals, root mean square(RMS) signals and wavelet transformed signals measured in turning process are introduced to analysis for chip patterns. With analysis of AE signals, it is obtained that the produced chip patterns are correlated with the specified AE signals which are transformed by fuzzy pattern algorithm. By this experimental investigation, the chip patterns can be classified at significant level in pure copper machining process and controlled from continuous chips to reduced?length stable chips