Calculation Of The Torsion Angle; Accuracy Of The Oldham Coupling - Harmonic Drive HFUS-2A Series Engineering Data

4.2 Calculation of the Torsion Angle

Calculation of the Torsion Angle φ at Torque T:
Equation 24.1
< –
T T
1
T
φ =
K
1
φ = Angle [rad]
T = Torque [Nm]
K = Stiffness [Nm/rad]
Example: HFUC-32-100-2UH
T = 60 Nm
T = 29 Nm
1
T = 108 Nm
2

4.3 Accuracy of the Oldham Coupling

Information concerning the Oldham coupling can be found in section 5.5.
In the region of tooth engagement Harmonic Drive® gears have no backlash. If an Oldham coupling is used for the compen-
sation of eccentricity errors of the motor shaft, a small backlash in the range of a few seconds of arc can occur at the output
shaft, as listed in table 24.5.
Table 24.5
Sizes
30
50
80
Ratio
100
120
160
24
Equation 24.2
= 6.7 . 10
K Nm/rad
4
1
= 1.1 . 10
K 5 Nm/rad
2
= 1.2 . 10
K Nm/rad
5
3
14 17
60 33
36 20
23 13
18 10
– 8
– –
T < T ≤T
1 2
T T - T
φ = 1 1
+
K K
1 2
φ =
6.7 . 10
φ = 7.15 . 10
φ = 2.5 arc min
Equation 24.4
φ [arc min] = φ [rad] .
20 25 32
28 28 23
17 17 14
11 11 9
9 9 7
8 8 6
6 6 5
Equation 24.3
T T
2
T T - T T - T
φ = 1 2 1
+ +
K K K
1 2
29 Nm 60 Nm - 29 Nm
+
11 . 10
4 Nm/rad 4 Nm/rad
rad
-4
180 . 60
�
40 45 50
– – –
14 12 12
9 8 8
7 6 6
6 5 5
5 4 4
1019658
2
3
[arcsec]
58
–
10
6
5
4
3
11/2014