Page 267 - Analysis and Design of Machine Elements

0.2 Wormgear Drives 245

0.18
Tin bronze wormgear, worm surface hardness >= 45 HRC
Tin bronze wormgear, worm surface hardness < 45 HRC
0.16
Cast iron wormgear, worm surface hardness >= 45 HRC
Equivalent coefficient of friction, f v 0.12
Cast iron wormgear, worm surface hardness < 45 HRC
0.14

0.1

0.08

0.06

0.04

0.02

0
0 2 4 6 8 10 12 14 16
Sliding velocity v , m/s
s
Figure 9.5 Equivalent coefficient of friction f versus sliding velocity v in wormgear drives [6].
v s

Figure 9.6 Meshing efficiency as 100
1
a function of lead angle and
coefficient of friction. 90
Meshing efficiency, η 1 , % 70 f = 0.01
80

60

50
f =0.02
40
f =0.04
f =0.05
30 f =0.1
20
0 5 10 15 20 25 30 35 40 45 50
Lead angle, γ, ˚