1、Dr.Liu W8839 2850Chapter 12Updated 13/10/2009,RichardDesign of helical gears斜齿轮传动设计Key pointsForce analysis of helical gears 斜齿轮的受力分析Strength calculation of helical gears 齿轮强度计算公式:应用注意事项、参数意义1 Load on helical gear tooth from power transmitted 斜齿圆柱齿轮传动的受力分析Fn1 in the normal plane(法面)Pabc can be decom
2、posed into 3 components:Ft1,Fr1 and Fa1 Relationship:21rrFF21ttFF21aaFF1 Load on helical gear tooth from power transmitted 斜齿圆柱齿轮传动的受力分析 Direction of forces 各力的方向判断各力的方向判断 Fr,Ft:the same as those of spur gears Fa:Left-and Right-hand rules(左、右手定则)for driving gear Presentation of forces:表示方法 Right-han
3、ded Left-handed Driving gear n1 Fa1 Fa2 22mincos.cos.ZbZbbxLbba2 Contact fatigue strength of helical gear tooth 斜齿圆柱齿轮传动的接触疲劳强度cos112.388.121ZZ端面重合度 Amendments to the parameters:1)Length of contact line L 接触线长度接触线长度Lx：接触线总长度变化系数(0.91)；Z：重合度系数aaZ)1(34-若若1,则取则取=1uubdKTZZZHEH12.:211直齿轮nmbsin纵向重合度2)Heli
4、x angle factor Z 螺旋角系数螺旋角系数 Amendments to the parameters:cosZIncreasing helix angle is good for gear tooth meshing action;this is beneficial for reducing the contact stress because the length of contact line becomes longer,and for decreasing shock load and vibration and noise.uubdKTZZZHEH12.:211直 Am
5、endments to the parameters:uubdKTZZZHEH12.:211直3)Curvature radius at the contact point 接触点曲率半径uutgdttb1.cos.cos211uutgdtt1.cos.211 -spur gear -helical gearCurvature radius of helical gear increases and the contact stress decreases accordingly P222图12.16,按螺旋角查取ZHCalculation formula for contact fatigu
6、e strength 接触疲劳强度的计算公式Notes for the above formula:Contact strength check 接触疲劳强度校核公式校核公式 Design formula 接触疲劳强度设计公式设计公式12.211HHEHuubdKTZZZZ3211).(1.2HHEdZZZZuuKTd How to use?与直齿相同与直齿相同12.211HHEHuubdKTZZZZ3211).(1.2HHEdZZZZuuKTd32111uuTAdHdd 据据查查A Ad d，由材料系数修正，由材料系数修正 P2263 Bending fatigue strength of
7、helical gear tooth斜齿轮弯曲疲劳强度潘存云教授研制潘存云教授研制斜齿轮齿面上的接触线为一斜线。轮齿的失效形式:局部折断 FSaFantFYYYYbmKFBending strength check弯曲强度校核公式校核公式3SaFaF21d21ncos2YYYYZYKTmDesign formula 弯曲强度设计公式设计公式2)YFa and YSacan be obtained from P229-2303cosZZv3)Y helix angle factor 螺旋角系数螺旋角系数Compared with spur gears:FSaFantFYYYYbmKF3SaFaF
8、21d21ncos2YYYYZYKTm1)mnmin1YY120-see P23975.01min0.25-Y.30,30;75.0,75.0;1,1计算则按若计算则按若计算则按若YY3cosZZvCompared with spur gears:FSaFantFYYYYbmKF3SaFaF21d21ncos2YYYYZYKTm4)Y contact ratio factor重合度系数vY75.025.0cos)11(2.388.1 21vvvZZ注意:斜齿轮中，计算接触应力时的重合度系数Z与计算 弯曲应力 时的重合度系数Y不同。前者使用实际齿数Z，后者使用当量齿数Zv。cos112.388.
9、121ZZ端面重合度aaZ)1(34-斜 齿轮 接触应力 计算时使用的重合度系数FSaFantFYYYYbmKF3SaFaF21d21ncos2YYYYZYKTm How to use?与直齿相同与直齿相同FSaFantFYYYYbmKF3SaFaF21d21ncos2YYYYZYKTm How to use?与直齿相同与直齿相同mmA3SaFaF21d1mYYYZTmn P232 Selection of design parameters 设计参数的选择1)m,Z,same as those of spur gears 2)helix angle 螺旋角螺旋角 d Selection of design parameters 设计参数的选择 Selection of design parameters 设计参数的选择THANKSFORLISTENING
