CFRP 복합소재 곡면가공의 볼엔드밀 가공특성에 관한 연구 = A Study on the Machining Characteristics of Ball End Milling for Curved Surfaces of CFRP Composites

다국어 초록 (Multilingual Abstract)

Carbon Fiber Reinforced Plastic(CFRP) have been widely adopted in aerospace, automotive, wind energy, marine, and sports industries due to their high specific strength, stiffness, low density, and excellent fatigue properties. However, their anisotropic structure, layered configuration, and weak machinability compared to metals lead to severe challenges in cutting processes, including rapid tool wear, delamination, burr formation, fiber pull-out, and matrix smearing. Among various machining methods, end milling is extensively used for CFRP components owing to its capability of machining both planar and curved surfaces. Nevertheless, variations in cutting speed, feed rate, depth of cut, and tool characteristics significantly influence cutting forces, tool wear, and surface quality. Previous studies indicate that higher cutting speeds tend to accelerate tool wear and surface roughness deterioration, while feed rate strongly affects wear progression and defect occurrence. In this study, systematic experiments are conducted by varying cutting speed, feed rate, and depth of cut to comprehensively analyze their effects on cutting force, tool wear, and surface roughness during CFRP end milling. Cutting forces are measured in real-time using a three-axis dynamometer, tool wear is quantitatively evaluated via optical and VMS microscopy, and surface roughness indices (Ra, Rz) are assessed using a contact profilometer with supplemental defect observations. The collected data are used to establish the interrelationships among cutting forces, wear, and surface roughness, enabling the identification of optimal cutting conditions. The outcomes of this research are expected to provide fundamental insights for achieving high-quality CFRP machining, extending tool life, and improving productivity while reducing machining costs in industrial applications.

목차 (Table of Contents)

• 제 1 장 서 론 1
• 1.1 연구배경 1
• 1.2 연구목적 3
• 제 2 장 이론적 배경 4
• 2.1 CFRP 소재특성 4
• 2.1.1 체적분율과 혼합률 법칙(Rule of Mixtures) 4
• 2.1.2 Halpin-Tsai 준경험식 6
• 2.1.3 열탄성 특성 8
• 2.2 절삭역학 1 0
• 2.2.1 CFRP의 절삭력 이론 11
• 2.2.2 힘 구성과 기계적(계수) 모델 14
• 2.2.3 엔드밀 기하, 순간 칩 두께 및 치접각 15
• 2.2.4 좌표계 변환과 치별 힘 합성 16
• 2.2.5 마찰-전단의 질적 해석 및 공구 기하 최적화 17
• 2.3 공구 마모 이론 18
• 2.3.1 공구 마모 종류 18
• 2.3.2 공구 마모 메커니즘 18
• 2.4 표면거칠기 이론 19
• 제 3 장. 실험 장비 및 방법 23
• 3.1 실험 장비 23
• 3.1.1 실험 장치 23
• 3.1.1.1 MachiningCenter 24
• 3.1.1.2 Dynamometer 25
• 3.1.1.3 amplifier 26
• 3.1.1.4 surface tester 27
• 3.1.1.5 vision measuring system 28
• 3.1.2 공구 및 피삭재 30
• 3.1.2.1 피삭재 30
• 3.1.2.2 공구 31
• 3.2 실험 방법 32
• 제 4 장. 실험 결과 및 고찰 34
• 4.1 절삭력 그래프 – 회전속도 34
• 4.2 절삭력 그래프 – 시간 추세 40
• 4.3 표면거칠기 측정 52
• 4.3.1 비코팅 공구의 가공시 표면거칠기 변화 53
• 4.3.2 코팅 공구의 가공시 표면거칠기 변화 56
• 4.3.3 두 공구의 표면 거칠기 비교 60
• 4.4 공구 마모 61
• 제 5 장. 실험 결론 80
• 참고문헌 82