Detailed Explanation; Electronic Gear - Mitsubishi melservo-j2 series Instruction Manual

5. PARAMETERS

5.2 Detailed Explanation

CAUTION

5.2.1 Electronic gear

(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
n
CDV
S
Hence, set 1024 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 2048 to CMX and 20944 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.
• Always make electronic gear setting in the servo off status to prevent
runaway due to false setting.
POINT
• The following specification symbols are needed for electronic gear
calculation:
Pb : Ballscrew lead [mm]
n : Reduction ratio
Pt : Servo motor resolution [pulse/rev]
S : Travel per servo motor revolution [mm/rev]
10 [mm]
1/2
8192 [pulse/rev]
p
8192
t
p
1000
1/2 10 1000
b
10 [mm]
1/3
16384 [pulse/rev]
p
t
n r 1000 1/3 160
+
CMX
CDV -
Electronic gear
Parameters No. 4, 5
n=NL/NM=1/2
NL
Servo motor
8192[pulse/rev]
8192 1024
5000
625
r=160[mm]
n
NL
n=NL/NM=1/3
16384 16384
1000 167551.61
5 - 13
1
CMX
20
CDV
Motor
Deviation
counter
Encoder feedback pulses
Encoder
n
Pb=10[mm]
NM
Servo motor
16384[pulse/rev]
NM
4096 2048
41888
20944
20.