4. 校核齿根弯曲疲劳强度 NO
当量齿数Zv1=Z1/cos3β=27/cos312036'12''=29
Zv2=Z2/cos3β=81/cos312036'12''=87
图12.21page229 YFa1=2.55
YFa2=2.22
应力修正系数: 图12.22page230
YSa1=1.62 淮阴师范学院
学报 YSa2=1.78
重合度系数Yε:εα=[1.88-3.2(1/Z1+1/Z2)]cosβ
=[1.88-3.2(1/29+1/87)]cos12036'12'' εα=1.69
Yε=0.25+0.75/εα=0.25+0.74/1.69Yε=0.69
螺旋角系数Yβ:Yβ=max(1-εββ0/1200,1-0.25εβ,0.75)
=max(1-1×12.60/1200,1-0.25×1,0.75)
Yβ=0.9
a. 齿间载荷分配系数:表12.10page217
KFα=εα/cos2βb=1.69/cos食品安全质量检测学报212.60 KFα=1.75
b. 齿向载荷分布系数:图12.14page219
b/h=83/(2.25×2.5)=12.3
KFβ=1.36
c. 载荷系数:K=KAKvKFαKFβ=1.5×1.2×1.75×1.36 K=4.28
3) 许用应力: (同直齿轮例题) [σF]=σFlimYNYX/sFmin
a.极限应力:图12.23page231 σFlim1=600Mpa
σFlim2=450Mpa
b.当量应力循环次数:
设3×106<NL<1010 则由表12.15page226 m=49.1
NL1=60γnth [(thi/th)(Ti中国文化遗产日/Tmax)m]
宜万
=60×1×1000×4800[0.2×149.1+0.5×0.549.1+0.3×0.249.1]
=5.76×107(与假设一致)
NL1=5.76×107
NL2=NL1/μ=5.76×107/3 NL2=1.92×107
c.弯曲寿命系数:图12.24page232 YN1=0.95
YN2=0.97
d.尺寸系数:图12.25page232 YX=1.0
e.安全系数:表12.14page225 SFmin=1.25
f.许用应力:[σF1]=σFlim1YN1YX/SFmin=600×0.95×1.0/1.25 [σF1]=456Mpa
[σF2]=σFlim2YN2YX/SFmin=450×0.97×1.0/1.25 [σF1激励理论]=349MPa
4) 校核
σF1=203Mpa
<[σF1]
σF2=σF1YFa2复合矩阵YSa2/YFa1YSa1
=203×2.22×1.78/2.55×1.62 σF2=194Mpa
<[σF2]
安全