1-10 Output Stiffness
49
1
2
3
4
5
6
7
8
9
10
11
付
Ou
tlin
e
Torsional Stiffness
(Ratio 11: HPF)
If a torque is applied to the output shaft of the actuator with the input locked, the output shaft will torsional deflect
roughly in proportion to the torque. When the values for torque are gradually changed in sequence from (1)
Rated output torque in the positive rotation direction
→
(2) zero
→
(3) Rated output torque in the negative rotation
direction
→
(4) zero
→
(5) Rated output torque in the positive rotation direction, the values follow a loop (1)
→
(2)
→
(3)
→
(4)
→
(5) (returns to (1)) shown in Fig.1 [torque vs. torsional angle diagram].
The gradient of the region [Rated output torque] from [0.15
x
rated output torque] is small, and the torsional
stiffness of the HPF series is the average of this gradient. The gradient of the region [0.15 x rated output torque]
from [zero torque] is large. This gradient is caused by semi-partial contact in the meshing region and uneven load
distribution from light loads and so forth on the planet gears.
An explanation is provided below on how to calculate the total torsional quantity on one side from a no-load state
after a load has been applied by the speed reducer.
The zero torque part widths of (2) and (4) in the
figure on the right [torque vs. torsional angle diagram]
is called the hysteresis loss. For the HPF series,
backlash is defined as hysteresis loss [rated output
torque in the negative rotation direction] from
[rated output torque in the positive rotation direction].
The HPF series has a backlash of less than
3 minutes (less than 1 minute with special
products) with factory settings.
Size • ratio
Item
SHA25A
SHA32A
11
11
Backlash
arc-min
3
3
10
-4
rad
8.7
8.7
Rated torque (T
R
)
Nm
21
44
Torsional quantity
on one side given
by T
R
x 0.15 (D)
arc-min
2.0
1.7
10
-4
rad
5.8
4.9
Torsional stiffness
(A/B)
kgf
･
m/arc-min
1.7
3.5
x10
-4
Nm/rad
5.70
11.7
θ＝
D
＋
T
－
TL
A
B
θ
: total torsional quantity
D: torsional quantity on one side given by rated output torque x
0.15 torque
T: load torque
TL: rated output torque x 0.15 torque (= T
R
x 0.15)
A/B: torsional stiffness
Fig. 1 Torque vs. torsional angle diagram
Torsional angle
Torque
Hysteresis loss
= backlash
T
R
: rated output torque
A/B: torsional stiffness
D: torsional quantity on one
side given by T
R
x 0.15
(1) (5)
(2)
(4)
(3)
