8-32
Chapter 8 SXYX
Replacement period
The harmonic drive replacement period is determined by the total number of
wave generator rotations. A calculation example is shown below.
The recommended harmonic drive replacement period is 8.4×108 rotations (at
usage atmospheric temperature range 0°C to +40°C).
The harmonic drive should be replaced earlier if the robot operation duty is high
or if the temperature conditions are poor.
[Replacement period] =8.4×108/(n×60×h×D×N×θ) years
n : Number of robot movements in one minute
θ: Average axis rotation in one movement
N : Deceleration rate (50 for ZRS R-axis)
h : Number of operation hours per day
D : Number of operation days per year
(Example) The YK500X X-axis harmonic drive replacement period when the
axis rotates an average quarter turn every movement and the robot
moves ten times in one minute. (Operation hours: 24 hours/day,
number of operation days: 240 days/year)
n: 10
θ: 0.25
N: 50
h: 24
D : 240
[Replacement period] =8.4×108/(n×60×h×D×N×θ)
=8.4×108/(10×60×24×240×50×0.25)
=19.4 years
Consult with YAMAHA when actually replacing the harmonic drive.