튜브 프레스핏과 직접 에너지 적층 공정을 이용한 냉각 채널 삽입형 금형 개발에 관한 연구

다국어 초록 (Multilingual Abstract)

The cooling efficiency of molds used in injection molding significantly affects product quality and cycle time. In this study, a hybrid cooling-channel mold was fabricated by embedding a Cu tube and depositing H13 tool steel using the directed energy deposition (DED) process. The Cu tube was press-fitted into the mold to ensure mechanical fixation and thermal continuity at the interface, followed by the DED of H13 powder on the upper region. Due to the large differences in thermal conductivity and coefficient of thermal expansion between Cu and H13, interfacial defects such as cracking, delamination, and lack of fusion occurred. These issues were mitigated by applying an optimized buffer layer and preheating conditions, which stabilized the molten pool and improved metallurgical bonding. The effects of buffer application and process parameters on dilution behavior, hardness distribution, and interfacial microstructure were systematically analyzed. Furthermore, finite element analysis was conducted to evaluate the structural stability during tube press-fitting, and a coolant-circulation experiment was performed to verify cooling performance. As a result, the hybrid Cu–H13 mold exhibited a cooling efficiency improvement of up to 29.5% compared with the conventional H13 mold, along with enhanced interfacial bonding and improved heat-transfer efficiency. This study demonstrates that combining the press-fit and DED processes provides a practical approach for fabricating high-efficiency conformal cooling molds with superior thermal performance. keywords : Direct Energy Deposition, Conformal Cooling Channel, H13, Copper, Buf fer Layer

목차 (Table of Contents)

• List of Tables ⅲ
• List of figures ⅲ
• Abstract ⅵ
• 1. 서론 1
• 1.1 연구배경 1
• 1.2 국내·외 연구 동향 9
• 1.3 연구 목적 14
• 2. 압입 구조해석 및 Tube-embedded 냉각 채널 설계 15
• 2.1 모델링 및 해석 조건 설정 17
• 2.2 압입 해석 결과 19
• 3. 이종소재 직접 에너지 적층의 결함 및 개선방안 23
• 3.1 직접 에너지 적층 공정 23
• 3.2 실험장비 및 재료 26
• 3.3 적층특성 분석 30
• 3.3.1 적층 후 결함 관찰 32
• 3.3.2 중간층 적용 및 예열 통한 결함 개선 효과 36
• 4. 중간층 적용에 따른 미세구조 및 기계적 특성 평가 42
• 4.1 실험준비 및 방법 43
• 4.2 실험 결과 47
• 4.2.1 경도변화 47
• 4.2.2 열전도 시험을 통한 열전달 특성 평가 50
• 4.2.3 굽힘 시험을 통한 접합강도 평가 54
• 5. 냉각 성능 평가 62
• 5.1 냉각수 순환 실험 62
• 5.1.1 온도 측정 방법 및 실험 조건 62
• 5.1.2 냉각 속도 비교 결과 64
• 5.2 전산유체역학(CFD) 기반 열전달 해석 67
• 5.2.1 모델링 및 경계조건 설정 67
• 5.2.2 시간에 따른 온도 분포 70
• 6. 결론 및 향후 계획 74
• 6.1 결론 74
• 6.2 향후 계획 76
• 참고문헌 77