표제지
ABSTRACT
요약
목차
1. 서론 13
1.1. 연구 배경 13
1.2. 연구 동향 16
1.3. 연구 목적 및 내용 19
2. 링 롤링 공정 조건의 이론 모델 20
2.1. 구동 롤 이송 조건 20
2.2. 가이드 롤 접촉 조건 25
3. 링 소재 물성 평가 30
3.1. 고온 인장 및 압축 시험 30
3.2. 가공 경화 모델 평가 36
4. 수직 링 롤링 공정의 유한요소해석 37
4.1. 2 차원 유한요소 모델 37
4.2. 구동 롤 이송 속도 영향 분석 40
4.3. 가이드 롤 접촉 조건 영향 분석 47
4.4. 3 차원 유한요소 해석 적용 54
5. 결과 및 고찰 56
6. 결론 58
참고문헌 59
Table.1. Mechanical properties of SUJ2 at tensile test 35
Table.2. Mechanical properties of SUJ2 at compression test 35
Table.3. Material parameter of the Voce hardening laws at tensile test 36
Table.4. Material parameter of the Voce hardening laws at compression test 36
Table.5. Geometric parameters of ring rolling process 39
Table.6. Outer diameter of the ring at the end of the ring rolling process 53
Table.7. Process parameters used in the 3D model FE simulation 54
Fig.1. Global share of bearing manufacturing industry. (2013) 14
Fig.2. Vertical ring rolling machine 15
Fig.3. Mechanical model of ring rolling 21
Fig.4. Geometrical model of FUGM 26
Fig.5. Geometrical model of GGM 28
Fig.6. Tensile and compression testing machine 30
Fig.7. Test specimen (a) tensile test specimen and (b) compression test specimen 31
Fig.8. Temperature during the test 31
Fig.9. Gleeble3500-DIC setting 32
Fig.10. Comparison of strain rates according to equipment control (a) strain rate 0.01/sec and (b) stain rate 1/sec 32
Fig.11. True stress-strain curves at different strain-rates (a) strain-rate 0.01/s, (b) strain-rate 0.1/s and (c) strain rate 1/s 33
Fig.12. True stress-strain curves at different strain-rates (a) strain-rate 0.01/s, (b) strain-rate 0.1/s and (c) strain rate 1/s 34
Fig.13. Ring rolling process modeling 38
Fig.14. Deformation zone 38
Fig.15. Comparison of mass scaling factor (a) value 1000, (b) value 500 (c) value 100 and (d) value 10 40
Fig.16. Growth rate of ring outer diameter 41
Fig.17. Feed speed of main roll each growth rate 41
Fig.18. Ring rolling analysis results by each growth rates (a) growth rate 0.20mm/sec, (b) growth rate 0.75mm/sec,... 42
Fig.19. Main roll feed speed of each condition 43
Fig.20. Plastic deformation of the ring during the ring rolling simulation (a) growth rate 1.3 mm/s condition and (b) constant speed 1.3 mm/s condition 45
Fig.21. Center coordinate of x-direction ring 46
Fig.22. Ring rolling process modeling with different guide roll angles 47
Fig.23. Ring rolling process for each contact angle (a) contact angle 0° (b) contact angle 5°... 48
Fig.24. Ring rolling process for each contact angle (e) contact angle 0° (f) contact angle 5°... 48
Fig.25. Result of the ring rolling process for each contact angle with symmetric (a) contact angle 0°, (b) contact angle 5°, (c) contact angle 10°... 50
Fig.26. Result of the ring rolling process for each contact angle with asymmetric (e) contact angle 0°, (f) contact angle 5°, (g) contact angle 10°... 51
Fig.27. Circularity of the ring formed by VRR process with different contact angles using (a) symmetric and (b) asymmetric guide rollers 52
Fig.28. Progressive shapes of deformed ring during process 55