Mitsubishi Electric MELSERVO-JET MR-JET User Manual page 105

For positioning mode (point table method)
■When setting "3" (pulse) in [Pr. PT01.2 Unit for position data]
Adjust [Pr. PA06 Electronic gear numerator] and [Pr. PA07 Electronic gear denominator] so that the travel distance set in the
servo amplifier matches the travel distance on the machine. [Motor revolutions (Obj. 6091h: 01h)] and [Shaft revolutions (Obj.
6091h: 02h)] can also be used for the setting.
Electronic gear
([Pr. PA06]/[Pr. PA07])
or
([Obj. 6091h: 01h]/[Obj. 6091h: 02h])
CMX
Travel distance
[command unit]
CDV
P : Servo motor encoder resolution [pulse/rev]
t
ΔS: Travel distance per servo motor revolution [command unit/rev]
CMX: Electronic gear numerator
CDV: Electronic gear denominator
CMX/CDV = P /ΔS
t
The following setting example shows how to calculate the electronic gear.
To calculate the electronic gear, the following specification symbols are required.
Pb: Ball screw lead [mm]
1/n: Reduction ratio
P : Servo motor encoder resolution [pulse/rev]
t
ΔS: Travel distance per servo motor revolution [mm/rev]
Ex.
Setting example for a ball screw
Machine specifications
1/n
1/n = Z /Z = 1/2
1 2
Z
2
Z
1
Servo motor encoder resolution
4194304 [pulse/rev]
Ball screw lead Pb = 10 [mm]
Reduction ratio: 1/n = Z /Z = 1/2
1 2
Z : Number of gear teeth on servo motor side
1
Z : Number of gear teeth on load gear
2
Servo motor encoder resolution: P
CMX P P 4194304
t t
= = =
*1
CDV ΔS 1/n • Pb • α 1/2 • 10 • 1000
Therefore, set CMX = 524288 and CDV = 625.
*1 When the command unit is "mm", convert as α = 1000. When the command unit is "inch", convert as α = 10000. When the command
unit is "pulse", convert as α = 1.
Servo motor
+
Deviation counter
-
Pb = 10 [mm]
= 4194304 [pulse/rev]
t
4194304 524288
= =
5000 625
M
Encoder
3 BASIC FUNCTION
3.5 Electronic gear function
3
103