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11.SELECTION
11-9 Selection example
Machine specifications
Servo
motor
Gear ratio 5:8
Servo
amplifier
Pulse train
FX – 1GM
(1) Selection of control parameters
1) Setting of electronic gear (command pulse multiplication numerator, denominator)
There is the following relationship between the multiplication setting and travel per pulse
∆R.
(ball screw lead)
∆R=
8192 x (gear ratio)
When the above machining specifications are substituted in the above equation:
CMX
= 0.005 •
CDV
Acceptable as CMX/CDV is within 1/50 to 20.
2) Input pulse train frequency for rapid feed fo
V
o
f
=
=
O
60 • ∆R
60 • 0.005
Acceptable as f
is not more than 200kpps.
o
(2) Servo motor speed
V
o
N
=
• n = 3000[r/min]
O
P
b
(3) Acceleration/deceleration time constant
T
= T
= to -
psa
psd
V
*ts: settling time. (Here, this is assumed to be 0.15s.)
Speed of moving part during fast feed
Travel per pulse
Travel
Positioning time
Number of feeds
Operation cycle
Gear ratio
Moving part weight
Drive system efficiency
Friction coefficient
Ball screw lead
Ball screw diameter
Ball screw length
Gear diameter (servo motor)
Gear diameter (load shaft)
Gear face width
(
)
CMX
x
CDV
8192 • 8/5
512
=
16
125
30000
=100000 [pps]
R
- ts = 0.05 [s]
/60
o
11– 11
V
= 30000mm/min
o
∆R
= 0.005mm
R
= 400mm
t
= within 1s
o
40 times/min.
t
= 1.5 s
f
n
= 8/5
W
= 60kg
η
= 0.8
µ
= 0.2
P
= 16mm
b
20mm
500mm
25mm
40mm
10mm
11
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