
B-63943EN-1/02 7.FEEDRATE CONTROL/ACCELERATION AND DECELERATION CONTROL
- 791 -
0
20
40
60
80
100
0 1000 2000 3000 4000
Speed(min
-1
)
Torque(Nm)
Fig. 7.2.5 (e) Torque for Acc/Dec with consideration of friction
Let the torque be x (Nm), the inertia be y(Kgm
2
), and the ball screw
pitch p(mm), then the acceleration A is calculated as follows:
]sec/[
2
][
2
][
])][sec/([
][
2
][
][
2
2
2
2
mm
y
px
mm
p
mkgy
mmkgx
mm
p
mkgy
mNx
A
×
×
=
×
⋅
⋅
=×
⋅
⋅
=
π
ππ
Machine specification is assumed as follows,
Ball screw pitch : 16 (mm)
Inertia : The machine inertia is to be 2.0 times higher than
that of the rotor.
(Rotor inertia: 0.0099 (Kgm
2
))
The acceleration at maximum torque is,
]sec/[7717
0099.00.32
1690
2
mm=
××
×
π
The acceleration at rapid traverse is,
]sec/[5916
0099.00.32
1669
2
mm=
××
×
π
From the above data, the parameters related to acceleration pattern is
given in the table below.
The example assumes that the acceleration is the same regardless of
whether acceleration or deceleration is in progress or whether the
movement is in the plus or minus direction.
- When setting the speed at P1, use the following value as a rough
guide:
If a bell-shaped acceleration change time (parameter No. 1672) is
set, use as a rough guide the ratio of the following speed to the
rapid traverse rate:
Reference acceleration × T2/4
where T2 is the bell-shaped acceleration change time (msec).
For example, assume T2 to be 40 msec, then the speed at P1
should be approximately
4124 [mm/sec
2
]×40 [msec]/4
=4124 [mm/sec
2
]×602×40 [msec]/60000/4
=2474 [mm/min]
- If no bell-shaped acceleration change time (parameter No. 1672)
is set, use about 5% of the rapid traverse rate as a rough guide.