机械设计课程设计说明书

N1?60nⅠjLh?60?546?1??2?8?365?8??1.53?109N11.53?109N?1???4.10?108i123.73 8N2?60nⅡjLh?60?146?1??2?8?365?8??4.09?10N24.09?108N?2???1.43?108i342.87KHN1?0.97,K?HN1?1.05由[1]图10-9,取接触疲劳寿命系数

?KHN2?1.06.KHN2?1.09取安全系数S=1

KHN1?Hlim10.98?550??539MPaS1??H?1??Hlim?KHN1?600?0.97?582MPaS1????H??1??Hlim?KHN1?550?1.05?577.5MPaS1

??H?2??Hlim?KHN2?600?1.06?636MPaS1????H??2??Hlim?KHN2?550?1.09?599.5MPaS1??H?11??582?577.5?579.75MPa2

636?599.5??H?22???617.75MPa2[?H]1?

(b) 计算 (i)

试算小齿轮分度圆直径

43.73?1?2.433?189.8?22?1.3?5.037?10????d1t?3??46.53?1?1.623.73?579.75??2?1.3?18.119?1043.87?2.433?189.8?d2t?3????74.441?1.622.87?617.75?计算圆周速度

?1.33m/s60?100060?1000

?d2tnⅡ??74.44?146v2???0.57m/s60?100060?1000(ii)

计算齿宽及模数

v1??d1tnⅠ???46.53?546 第 11 页

b1??d1t?1?46.53?46.53mm,b2??d2t?1?74.44?74.44mmd1t46.53d2t74.44??2.33,mt2???2.98Z120Z225齿高h1?2.25mt1?2.25?2.33?5.24mmh2?2.25mt2?2.25?2.98?6.71mmb146.53b274.44???8.88,??11.1h15.24h26.71模数mt1?(iii)

计算纵向重合度

??1?0.318?dZ1tan??0.318?1?20?tan14??1.59??2?0.318?dZ2tan??0.318?1?25?tan14?1.98(iv)

计算载荷系数

?使用系数由[1]表10-2,kA?1.00

由[1]图10-8查得根据v1?1.33m/s,v2?0.57m/s动载系数Kv1?1.07,Kv2?1.03 由[1]表10-3查得齿间载荷分配系数KH??KF??1 由[1]表10-4查得齿向载荷分布系数KH?的简化计算公式

用插值法查的7级精度,小齿轮相对非对称布置时KH?1?1.417,KH?2?1.424 由[1]图10-13查得KF?1?1.4,KF?2?1.36。故载荷系数

K1?KAKv1KH?KF?1?1?1.07?1?1.417?1.516

K2?KAKv1KH?KF?2?1?1.08?1?1.424?1.3467(v)

按实际的载荷系数校正所算得的分度圆直径,由[1]式(10-10a)得

d1?d1t3d2?d2t3(vi)

K11.516?46.533?48.976Kt1.3K21.476?74.443?77.5Kt1.3计算模数m

m1?d148.976d277.5??2.45mm,m2???3.10mm Z120Z2254.3按齿根弯曲强度计算

由[1]式(10-17)

i.

确定计算参数 1. 计算载荷系数

K1?KAKv1KF?KF?1?1?1.07?1?1.4?1.498

K2?KAKv2KF?KF?2?1?1.03?1?1.36?1.4008(vii)

根据纵向重合度

??1?0.318?dZ1tan??0.318?1?20?tan14??1.59??2?0.318?dZ2tan??0.318?1?25?tan14?1.98

第 12 页

?

2. 从[1]图0-28查得螺旋角影响参数

Y??0.88

3. 计算当量齿数

Z120Z?175???21.9,ZV1???82cos314?cos314?cos3?cos314?

Z125Z?272?ZV2???27.4,ZV2???78.84cos314?cos314?cos3?cos314?ZV1?

4. 查取齿形系数

YFa1?2.80,Y?Fa1?2.22由[1]表10-5查得,

YFa2?2.62,Y?Fa2?2.335. 由[1]表10-5查得应力校正系数

Ysa1?1.55,Y?sa1?1.77

Ysa2?1.59,Y?sa2?1.766. 确定许用弯曲疲劳应力

由[1]图10-20c查得小齿轮弯曲疲劳强度极限?FE?500MPa由[1]图10-20b查得大齿轮弯曲疲劳强度极限??FE?380MPa 由图10-28取弯曲疲劳寿命系数

KFN1?0.87,K?FN1?0.89

KFN2?0.88,K?FN2?0.9取弯曲疲劳安全系数S=1.4,由式(10-12)得

??F?1?KFN1??FE?0.87?500?310.71MPa,??F??1?KFN1??FE?0.89?380?241.57MPaS????F?2?KFN2??FES

1.4S1.40.88?500K?FN2???FE0.9?380???314.29MPa,??F?2???244.29MPa1.4S1.47. 计算大、小齿轮的

YFaYSa [?F]YFa1?Ysa12.8?1.55?0.01397??F?1310.71Y?Fa1?Y?sa12.22?1.77??0.01627 ?241.57??F?1? 第 13 页

YFa2?Ysa2??F?2??F?2

ii.

设计计算

?Y?Fa2?Y?sa2?

2.62?1.59?0.01325314.29

2.23?1.76??0.01607244.29m1?3m2?32?1.498?50370?0.01627?1.83mm1?2022?1.4008?181190?0.01607?2.35mm225

由[3]表23.2-3取标准模数m1?2,m2?2.5,已可满足弯曲强度,为同时满足接触疲劳强度,需按接触疲劳强度算得的分度圆直径d1?48.976mm,d2?77.5mm来计算应有齿数。因此

d1cos?48.976cos14?Z1???24m12Z?1?3.73?24?90d2cos?77.5cos14??31m22.5Z?2?2.87?31?89Z2?

1) 几何尺寸计算

(a) 计算中心距

?

a1?2cos?2cos?,

?Z2?Z?2?m2?31?89??2.5a2???150mm2cos?2cos?(b) 按圆整后的中心距修正螺旋角

?Z1?Z?1?m1??24?90??2?114mm??arccos?Z1?Z?1?m1?arccos?24?90??2?14?低速轴同理

2a12?125因?值改变不多,故与?有关的参数不必修改。

(c) 计算大、小齿轮的分度圆直径‘齿顶圆直径、齿根圆直径

d1?Z1m1?24?2?48mm,d?1?Z?1m1?90?2?180mm

??d2?Z2m2?31?2.5?78mm.d2?Z2m2?89?2.5?222.5mm

第 14 页

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