Harmonic Drive FHA Mini Series, Manual

Page: 26 / 50

Chapter 2 Guidelines for sizing
FHA-mini
26
•
Calculating average loads:
average radial and axial loads, average output speed
When the radial and/or axial loads vary during motion, calculate and verify the life of the cross roller
bearing converting the loads to their average values.
• Average radial load: Frav
(2)
Note: "Fr
1
" is the maximum radial load in "t
1
" range,
and "Fr
3
" is the maximum radial load in "t
3
"
range.
• Average axial load: Faav
(3)
Note: "Fa
1
" is the maximum axial load in "t
1
" range,
and "Fa
3
" is the maximum axial load in "t
3
"
range.
• Average output speed: Nav
(4)
•
Calculating radial load factor and axial load factor
Both load factors are different with average loads as follows:
• When the right formula is satisfied, (5)
X=1.0, and Y=0.45
• When the formula below is satisfied, (5')
X=0.67, and Y=0.67
Where, the variables of the formulas are:
M max : Maximum torsional moment in N•m(kgf•m); obtained by the formula (1).
Fr max : Maximum radial load in N(kgf); See Fig.1.
Fa max : Maximum axial load in N(kgf); See Fig.1.
Lr, La: Loading point in mm; See Fig.1.
R: Offset; See Fig.1 and Table 1.
dp: Circular pitch of roller: See Fig.1 and Table 1.
Fig.2: Load/speed-time charts
Time
－
R
a
d
ia
l l
o
a
d
＋
Fr
1
Fr
2
Fr
3
Time
－
A
xi
a
l l
o
a
d
＋
Fa
1
Fa
2
Fa
3
Time
－
O
u
tp
u
t
sp
e
e
d
＋
n
1
n
2
n
3
t
1
t
2
t
3