65
Not use electronic gear ratio
Use electronic gear
Calculate the electronic gear ratio (B/A) using the following steps:
Step
Content
Explanation
1
Confirm the machine
specification
Confirm the deceleration ratio, ball screw distance, pulley
diameter
2
Confirm the encoder
pulse
Confirm the servo motor encoder accuracy
3
Set the command unit
Set the actual distance or angle corresponding to 1 pulse of the
controller
4
Calculate the command
pulses the load shaft
rotates 1 circle
Calculate the command pulses per rotation f based on the
command unit
5
Calculate the pulses
per
rotation
(P0-11/P0-12)
For example, the mechanical reduction ratio of motor shaft and
load shaft is m/n (servo motor run m circles while load shaft run
n circles), P0-11/P0-12=(f×m)/n
6
Calculate the electronic
gear
ratio
(P0-13/P0-14)
For example, the mechanical reduction ratio of motor shaft and
load shaft is m/n (servo motor run m circles while load shaft run
n circles), P0-13=encoder accuracy×4×m
P0-14=f×n
Note:
1.
Pulses per rotation and electronic gear ratio can limit the command pulses of motor rotate 1
circle. The priority of pulses per rotation is higher than electronic gear ratio. Only when pulses
per rotation is 0, the electronic gear ratio will be effective. If the pulses per rotation is
fractional, it is better to use electronic gear ratio.
2.
When P0-13 and P0-14 is over the range, please use the integer in the range from the reduction
of the decimal number.
3.
The motor encoder accuracy is 2500P/R.
4.
The command unit is not machine accuracy. Refine the command unit based on machine
accuracy can improve the servo positioning precision. For example: in the application of
screw, the machine precision can up to 0.01mm, so the command unit 0.01mm is more
accurate than 0.1mm.
Workpiece
Ball screw pitch: 6mm
Encoder pulse: 2500
Encoder pulse: 2500
Ball screw pitch: 6mm
Workpiece
1 rotation is 10000 pulses
Workpiece moves 6mm per rotation, so the length per pulse
is 6mm/10000 =0.6um.
The workpiece moves 10mm, so it needs
10mm/0.6um=16666.6666 pulses. The decimal will be
discarded for actual pulse sending.
After setting electronic gear ratio, 1 rotation is 6000 pulses
Workpiece moves 6mm per rotation, so the length per pulse is
6mm/6000=1um.
The workpiece moves 10mm, it needs 10mm/1um=10000
pulses. It will not produce decimal and error.