Mitsubishi Electric MR-JE-C, Instruction Manual

Page: 82 / 312

4. PARAMETERS
4 - 45
4.4 How to set the electronic gear
4.4.1 Electronic gear settings in the point table method
Adjust [Pr. PA06] and [Pr. PA07] to match the servo amplifier setting with the travel distance of the machine.
Travel distance
Deviation counter
+
-
Servo motor
Encoder
M
CDV
CMX
Electronic gear
([Pr. PA06] [Pr. PA07])
P
t
: Servo motor encoder resolution: 131072 [pulse/rev]
ΔS: Travel distance per servo motor revolution [mm/rev]/[inch/rev]/[pulse/rev]
CMX/CDV = P
t
/ΔS
Set the electronic gear within the following range. Setting out of the range will trigger [AL. 37 Parameter
error].
Electronic gear setting range
1/27649 < CMX/CDV < 8484
The following setting example shows how to calculate the electronic gear.
POINT
To calculate the electronic gear, the following specifications are required.
Pb: Ball screw lead [mm]
1/n: Reduction ratio
P
t
: Servo motor encoder resolution [pulse/rev]
ΔS: Travel distance per servo motor revolution [mm/rev]
(1) Setting example of a ball screw
Machine specifications
Ball screw lead Pb = 10 [mm]
Reduction ratio: 1/n = Z
1
/Z
2
= 1/2
Z
1
: Number of gear teeth on servo motor side
Z
2
: Number of gear teeth on load side
Servo motor encoder resolution
131072 [pulse/rev]
Pb = 10 [mm]
Z
1
1/n = Z
1
/Z
2
= 1/2
Z
2
1/n
Servo motor encoder resolution: P
t
= 131072 [pulse/rev]
CMX
CDV
P
t
=
Δ
S
P
t
=
n Pb
α
(Note)
131072
=
1/2 10 1000
131072
=
5000
16384
=
625
Note. Because the command unit is "mm", α is 1000. When the unit is "inch", α is 10000. When the unit is "pulse", α is 1.
Therefore, set CMX = 16384 and CDV = 625.