当压力角α=20°的正常齿制渐开线标准外直齿轮,当渐开线标准齿轮的齿根圆与基圆重合时,其齿数z应为多少?又当齿数大于以上求得的齿数时,试问基圆与齿根圆哪个大?
正确答案:
解:rb=mzcos20°/2
rf=mz/2-1.25m
当rb=rf得mzcos20°/2= mz/2-1.25m
Z=2.5/(1-cos20°)=41.45
当rb<rf时得mzcos20°/2<mz/2-1.25m
Z>2.5/(1-cos20°)=41.45
因为齿数为整数,故Z>42时齿根圆大于基圆。
rf=mz/2-1.25m
当rb=rf得mzcos20°/2= mz/2-1.25m
Z=2.5/(1-cos20°)=41.45
当rb<rf时得mzcos20°/2<mz/2-1.25m
Z>2.5/(1-cos20°)=41.45
因为齿数为整数,故Z>42时齿根圆大于基圆。
答案解析:有
微信扫一扫手机做题