Mitsubishi Electric MELSERVO-J5 MR-J5 Series User Manual page 105

Ex.
Setting example for a ball screw
The following shows an example where the ball screw is moved at 10 μm per pulse.
Machine specifications
1/n
1/n = Z /Z = 1/2
1 2
Z
2
Z
1
Servo motor encoder resolution
67108864 [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
t t
= ΔL • = ΔL •
0 0
CDV ΔS 1/n • Pb
Therefore, set CMX = 16777216 and CDV = 125.
Ex.
Setting example for conveyors
The following shows the example of when the conveyor is rotated at 0.01° per pulse.
Machine specifications
Servo motor
67108864 [pulse/rev]
Table
Timing belt: 625/12544
Table: 360°/rev
Reduction ratio: 1/n = 625/12544
Servo motor encoder resolution: P
CMX P 67108864
t
= Δθ° • = 0.01 •
CDV Δθ 625/12544 • 360
At this point, as CMX is outside of the setting range (2147483647 or less), the value needs to be reduced. After reducing CMX
to the setting range or less, round off the value to the nearest whole number.
CMX 26306674688 1753778312.53
= =
CDV 703125 46875
Therefore, set CMX = 1753778313 and CDV = 46875.
If the servo motor rotates in one direction endlessly on systems such as an index table, the error in rounding
off accumulates, resulting in the index position mismatch.
For example, even if 36000 pulses are input for the command in the previous example, the following result is
obtained for the table. Therefore, a positioning to the same position cannot be performed on the table.
1753778313
36000 •
46875
Reduce the value so that the calculated values before and after reduction are as close as possible.
Pb = 10 [mm]
= 67108864 [pulse/rev]
t
67108864 67108864
-3
= 10 × 10 • =
1/2 • 10 500
= 67108864 [pulse/rev]
t
841813590016 26306674688
= =
22500000 703125
1753778313
≈
46875
1 625
• • • • 360° = 360.0000001°
67108864 12544
16777216
=
125
3.9 Electronic gear function [G] [WG]
3 BASIC FUNCTION
103
3