Detailed Explanation; Electronic Gear - Mitsubishi Electric MELSERVO-J2-Super Series Instruction Manual

6. PARAMETERS

6.2 Detailed explanation

6.2.1 Electronic gear

CAUTION
(1) Concept of electronic gear
Use the electronic gear (parameters No.4, 5) to make adjustment so that the servo amplifier setting
matches the moving distance of the machine. Also, by changing the electronic gear value, the machine
can be moved at any multiplication ratio to the moving distance on the servo amplifier.
Parameters No. 4
CMX
CDV Parameters No. 5
The following examples are used to explain how to calculate the electronic gear value:
(a) Ballscrew setting example
Machine specifications
Ballscrew lead: Pb
Reduction ratio: n
Servo motor resolution: Pt
p
CMX
t
CDV
S n
Hence, set 32768 to CMX and 625 to CDV.
(b) Conveyor setting example
Machine specifications
Pulley diameter: r
Reduction ratio: n
Servo motor resolution: Pt
p
CMX
t
CDV
S
Reduce CMX and CDV to the setting range or less, and round off the first decimal place.
Hence, set 32768 to CMX and 41888 to CDV.
False setting will result in unexpected fast rotation, causing injury.
POINT
The guideline for setting the electronic gear is
If you set any value outside this range, noise may be produced during
acceleration/deceleration or operation not performed at the preset speed
or acceleration/deceleration time constant.
After setting the parameter No.4, 5 value, switch power off, then on to
make that setting valid.
POINT
The following specification symbols are needed for electronic gear
calculation:
Pb : Ballscrew lead [mm(in.)]
n : Reduction ratio
Pt : Servo motor resolution [pulse/rev]
S : Travel per servo motor revolution [mm/rev]
10 (0.39) [mm(in.)]
1/2
131072 [pulse/rev]
p
131072
t
p
1/2 10 1000
1000
b
160 (6.30) [mm(in.)]
1/3
131072 [pulse/rev]
p
t
1/3 160
n r 1000
+
CMX
CDV
-
Encoder feedback pulses
Electronic gear
Parameters No. 4, 5
n
n=NL/NM=1/2
NL
Servo motor 131072[pulse/rev]
32768
131072
5000 625
r=160(6.30)[mm(in.)]
n=NL/NM=1/3
131072 131072
1000 167551.61
6 - 24
1
CMX
1000 .
10
CDV
Motor
Deviation
counter
Encoder
Pb=10(0.39)[mm(in.)]
NM
Servo motor
n
131072[pulse/rev]
NL
NM
32768
41888