178
Pulse row positioncommandDistance: P1 [P]Traveling speed: F [PPS]Command dividing multiplier ratioServo driverD = Pr46 x 2Pr4B
Pr4A
ServomotorEncoderGear MachineRotation speed: N [r/min]Reduction ratio: RNumber of encoder pulses E [P/r] 10000 = (phase A/B 2500 [P/r] x 4)Example of driving ball screw using the servo motorDescription on Dividing/Multiplier Ratio

Relation between Positional Resolution/Moving Speed and Command Dividing Multiplier Ratio

As an example of a machine, we describe a ball screw driving system below:
When lead of a ball screw is L [mm], actual distance of a ball screw M [mm] with respect to the distance command
PI [P] is expressed with formula (1) below:

M = P1 x (D/E) x (1/R) x L................................. (1)

Therefore, position resolution (distance DM per command pulse) is expressed by the following formula (2):
∆∆
∆∆

∆M = (D/E) x (1/R) x L....................................... (2)

Through transformation of formula (2), a command dividing multiplier ratio D is determined by the formula (3):

D = (∆∆

∆∆

∆M x E x R)/L ............................................ (3)

In addition, actual traveling speed V [mm/s] of a ball screw with respect to traveling speed command F [PPS] is
expressed by formula (4), and the corresponding motor rotation speed N is determined by formula (5):

V = F x (D/E) x (1/R) x L ................................... (4)

N = F x (D/E) x 60 ............................................. (5)

Through transformation of formula (5), a command dividing multiplier ratio D is determined by the formula (6):

D = (N x E)/(F x 60) ........................................... (6)

<Remarks>
1. Set the positional resolution (∆M) at approx. 1/5 to 1/10 of the positioning accuracy (∆
ε
), in view of mechanical
errors.
2. Set a value from 1 to 10000 to Pr46 and Pr4B.
3. You can set any value depending on numerator and denominator settings. However, if you specify an extreme
dividing/multiplier ratio, we cannot guarantee proper operation of the motor. We recommend that you set the
dividing/multiplier ratio in the range of 1/50 to 20 times.
4. 2n
20
21
22
23
24
25
26
27
28
29
210
211
212
213
214
215
216
217
Decimal
1
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
32768
65536
131072