3 BASIC FUNCTION
3.10 Electronic gear function [A]
113
3
■
Setting example for a ball screw
The following shows an example where the ball screw is moved at 10
μ
m per pulse.
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 gear
Servo motor encoder resolution: P
t
= 67108864 [pulse/rev]
Therefore, set CMX = 16777216 and CDV = 125.
■
Setting example for conveyors
The following shows the example of when the conveyor is rotated at 0.01° per pulse.
Machine specifications
Table: 360°/rev
Reduction ratio: 1/n = 625/12544
Servo motor encoder resolution: P
t
= 67108864 [pulse/rev]
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.
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.
Reduce the value so that the calculated values before and after reduction are as close as possible.
67108864 [pulse/rev]
Pb = 10 [mm]
Z
1
1/n = Z
1
/Z
2
= 1/2
Z
2
1/n
Servo motor encoder resolution
CMX
CDV
=
Δ
L
0
•
=
Δ
L
0
•
P
t
Δ
S
= 10 × 10
-3
•
P
t
1/n • Pb
67108864
1/2 • 10
=
67108864
500
=
16777216
125
67108864 [pulse/rev]
Servo motor
Table
Timing belt: 625/12544
CMX
CDV
=
Δθ
° •
= 0.01 •
P
t
Δθ
67108864
625/12544 • 360
=
841813590016
22500000
=
26306674688
703125
CMX
CDV
=
1753778312.53
46875
=
26306674688
703125
1753778313
46875
≈
36000 •
1753778313
46875
1
67108864
•
•
•
625
12544
• 360° = 360.0000001°