图 上海久通大学 h人口 LECTURE 12-I ME371/ME337 DESIGN AND MANUFACTURING Gear design Covered Cha5 and Cha6 in Design of Machinery 图上涤夫廷大学 Outline Failure types of gears ▣Forces on Gears Fundamental theories for gearing strength Design of gear transmission 1
1 Gear design LECTURE 12-III ME371/ME337 DESIGN AND MANUFACTURING Covered Cha5 and Cha6 in Design of Machinery Outline Failure types of gears Forces on Gears Fundamental theories for gearing strength Design of gear transmission
公 上海通大学 Failure types of gears ▣Tooth fracture due to bending stresses (either Light scuffing static or under fatigue cyclic load)轮齿断裂 国上清通大学 Failure types of gears ▣Pitting点蚀 Occurs at dedendum near pitch circle 2
2 Failure types of gears Tooth fracture due to bending stresses (either static or under fatigue cyclic load) 轮齿断裂 Occurs at dedendum near pitch circle Pitting点蚀 Failure types of gears
图 上海久通大学 Failure types of gears 口Scuffing damage(齿面胶合) occurs on gear teeth if they are operated with an inadequate lubricant film between the teeth.High surface temperatures then arise from the frictional heating and local welding and surface dragging and scoring tend to occur. 国上清通大学 Failure types of gears ▣surface wear(齿面磨损) When hard abrasive material is present in the lubricant the teeth may show embedding damage or abrasive scoring sometimes leading to major surface wear 3
3 occurs on gear teeth if they are operated with an inadequate lubricant film between the teeth. High surface temperatures then arise from the frictional heating and local welding and surface dragging and scoring tend to occur. Failure types of gears Scuffing damage(齿面胶合) When hard abrasive material is present in the lubricant the teeth may show embedding damage or abrasive scoring sometimes leading to major surface wear Failure types of gears surface wear (齿面磨损)
公 上游充通大学 Failure types of gears ▣Teeth deformed When unhardened teeth are subjected to very high loads,and particularly shock loads,the surfaces of the teeth can become deformed.so that the surface material is squeezed out at the ends and towards the tips of the teeth(塑性变形) 图上涤夫廷大学 Outline Failure types of gears ▣Forces on Gears Fundamental theories for gearing strength Design of gear transmission 4
4 When unhardened teeth are subjected to very high loads, and particularly shock loads, the surfaces of the teeth can become deformed, so that the surface material is squeezed out at the ends and towards the tips of the teeth (塑性变形) Failure types of gears Teeth deformed Outline Failure types of gears Forces on Gears Fundamental theories for gearing strength Design of gear transmission
公 上酒我廷大峰 Forces on gears ▣Forces on spur gears Forces on helical gears ▣Forces on bevel gears 圆上游夫大学 H +3+31+ W,=33000 P where W,=transmitted load.Ibf H=power.hp V=pitch-line velocity,ft/min 60000H W,= πdn where W,transmitted load,kN H=power.kW d=gear diameter,mm n=speed,rev/min 31 5
5 Forces on spur gears Forces on helical gears Forces on bevel gears Forces on gears