86 kW급 트랙터 변속기 기어의 피로 손상 분석 및 기어 재질 변경을 통한 내구성 개선

다국어 초록 (Multilingual Abstract)

This study was conducted to secure the durability of the tractor transmission as a basic study on the development and optimal design of tractor transmissions. A field test was conducted using an 86 kW agricultural tractor for plow and rotary tillage, which are typical agricultural operations. The plow and rotary tillage were performed at F10 (7 km/h) and F8 (4 km/h) gear stages, respectively. The field operation was completed after around 107 hours due to transmission noise and operational problems such as forward and reverse. As a result of disassembling the transmission, it was found that range shift A and B gears were damaged. In the case of range shift A gear, it is judged that plastic deformation occurred due to low contact stress, and in case of range shift B gear, the bending stress was low and thus gear tooth breakage occurred. The simulation results showed that the contact safety factor of the range shift A gear was the lowest, and the bending safety factor of the range shift B gear was the lowest. Accordingly, it was judged that the simulation and field test results appeared the similar trend to each other. In order to secure durability of the transmission, four materials of alloy steel for machine structural use such as SCr420, SNCM220, SCM822, and SNC815 were selected, and the safety factor and service life of the damaged range shift gears were analyzed according to gear materials. As a result of simulation analysis, SCM822 material satisfied the design target life and was selected as a material for change. The range shift A and B gears were changed to SCM822, and an axle dynamometer test was performed for verification of the modified transmission. After conducting the axle dynamometer test, the transmission was disassembled and it was confirmed that the range shift A and B gears were in normal condition. Therefore, it is determined that the durability of the transmission has been secured by satisfying the target life. In the future, the simulation model of transmission for 86 kW class agricultural tactor is expected to be utilized for development of tractor transmission, cost reduction, and optimal design.

목차 (Table of Contents)

• 목차
• LIST OF TABLES
• LIST OF FIGURES
• Ⅰ. 서론
• 1.1 연구 배경
• 1.2 연구 목적
• 1.3 이론적 배경
• 1.3.1 트랙터 변속기
• 1.3.2 기어 강도 설계
• 1.3.3 기어 손상 유형
• 1.3.4 기어 강도 해석
• Ⅱ. 재료 및 방법
• 2.1 공시 트랙터
• 2.2 포장시험
• 2.3 기어 손상 분석
• 2.3.1 부변속 A단
• 2.3.2 부변속 B단
• 2.4 기어 재질 변경
• 2.5 시뮬레이션 해석
• 2.5.1 시뮬레이션 모델링
• 2.5.2 시뮬레이션 해석 조건
• 2.6 차축 부하 다이나모 시험
• 2.6.1 가속 수명 시험
• 2.6.2 차축 다이나모 시험 장치 구성
• 2.6.3 차축 다이나모 시험 조건
• Ⅲ. 결과 및 고찰
• 3.1 시뮬레이션 모델 개발 및 검증
• 3.2 재질 변경에 따른 시뮬레이션 해석 결과
• 3.2.1 부변속 A단
• 3.2.2 부변속 B단
• 3.3 차축 다이나모 시험 결과
• 3.3.1 부변속 A단
• 3.3.2 부변속 B단
• 3.4 기어 수명 해석 결과 비교
• Ⅳ. 결론 및 요약
• LIST OF REFERENCES
• ABSTRACT