Content .. 88 89 90 91 ..

FANUC Series 30i/300i/300is-MODEL A. Machining Center System. User's manual - page 90

PROGRAMMING

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20. HIGH-SPEED CUTTING

FUNCTIONS

20.4

OPTIMUM TORQUE ACCELERATION/DECELERATION

Overview

This function enables execution of acceleration/deceleration adapted
to the torque characteristics of the motor and the characteristics of the
machine due to the friction and gravity of the machine.

Usually, because of the friction of the machine, gravity, the torque
characteristics of the motor, and other factors, the acceleration/
deceleration performance (torque for acceleration/deceleration) is
different with direction of movement, acceleration or deceleration. In
this function, acceleration pattern of rapid traverse for the following
situations, plus movement and acceleration, plus movement and
deceleration, minus movement and acceleration, minus movement and
deceleration can be set into parameters according to the torque for
acceleration/deceleration of each situation.
Acceleration/deceleration can be performed according to these
parameter setting, so that the most of the capability of the motor can
be used and positioning time can be reduced.

T im e

A c c e le r a t io n

A c c / D e c p a tt e r n is t h e s a m e w a y in e a c h c o n d itio n .

S p e e d

A c c e le r a tio n

a n d

+ m o v e

D e c e le r a ti o n

a n d

+ m o v e

A c c e le r a t io n

a n d

- m o v e

D e c e le r a ti o n

a n d

- m o v e

Fig. 20.4 (a) Conventional acceleration/declaration

T im e

S p e e d

T im e

A c c e le r a ti o n

A c c e l e r a ti o n

a n d

+ m o v e

D e c e le r a t io n

a n d

+ m o v e

A c c / D e c p a tt e r n c a n b e c h a n g e d in e a c h c o n d itio n .

A c c e le r a ti o n

a n d

- m o v e

D e c e l e r a t io n

a n d

- m o v e

Fig. 20.4 (b) Acceleration/deceleration with this function

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PROGRAMMING

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20.HIGH-SPEED CUTTING

FUNCTIONS

Explanation

Optimum torque acceleration/deceleration selects the acceleration
pattern set with parameters on the basis of the axial movement
direction and the acceleration/deceleration state, determines the
acceleration for each axis from the current speed, and controls the
tangential acceleration/deceleration for rapid traverse.

- Setting optimum torque acceleration/deceleration

When bit 0 (FAP) of parameter No. 19540 and bit 1 (LRP) of
parameter No. 1401 are set to 1, and a value other than 0 is set for any
one of the axes as the reference acceleration in parameter No. 1671 as
shown below, rapid traverse is accelerated/decelerated by optimum
torque acceleration/deceleration.

Table 20.4 (a) Optimum torque acceleration/deceleration

Parameter

FAP

(Optimum

torque

acc/dec)

Parameter

LRP

(Linear type

positioning)

Reference

acceleration

Bell-shaped

acceleration
change time

Acceleration

pattern

1 1

Parameter

No.1671

Parameter

No.1672

See "Setting an
acceleration
pattern".

To enable bell-shaped acceleration/deceleration in addition to
optimum torque acceleration/declaration, set the bell-shaped accel-
eration change time with parameter No.1672.

- Required conditions in addition to parameter setting

If the conditions for performing AI contour control and for
acceleration/deceleration before interpolation are satisfied, optimum
torque acceleration/deceleration is performed for accelerating and
decelerating rapid traverse. Note, however, that if 1 is set to bit 0
(FAE) of parameter No. 11240, optimum torque
acceleration/deceleration is enabled even if AI contour control is
disabled. If rapid traverse is subject to optimum torque
acceleration/deceleration, after-interpolation acceleration/deceleration
does not apply to rapid traverse.

- Cases in which optimum torque acceleration/ deceleration is disabled

If optimum torque acceleration/deceleration is disabled by parameter
settings, or the required conditions other than parameter settings are
not satisfied, acceleration/deceleration after interpolation is used to
accelerate and decelerate rapid traverse.

PROGRAMMING

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20. HIGH-SPEED CUTTING

FUNCTIONS

- Setting acceleration pattern data

Acceleration

Speed

Acceleration pattern

Fig. 20.4 (c) Setting acceleration pattern

Set the speed and the acceleration at each of the acceleration setting
points P0 to P5 for each condition, plus movement and acceleration,
plus movement and deceleration, minus movement and acceleration,
minus movement and deceleration, and for each axis.
The line joining the acceleration setting points is regarded a
acceleration pattern.
For example, while the speed is between Fa and Fb in the previous
figure, the acceleration is calculated with Aa and Ab. Tangential
acceleration is controlled not to exceed the calculated acceleration for
each axis.

CAUTION

It is not desirable to set an acceleration pattern in
which a large acceleration is set right at a speed of
0, because this will shock the machine. For this
reason,

be sure to set a low acceleration at a

speed of 0

, as in the figure above.

Table 20.4 (b) Parameters for acceleration pattern

Acceleration parameter

During acceleration

During deceleration

Acceleration
setting point

Speed

parameter

During

movement in

plus

direction

During

movement in

minus

direction

During

movement in

plus

direction

During

movement in

minus

direction

P0 (Speed

No.19545

No.19551 No.19557 No.19563

P1 No.19541

No.19546

No.19552 No.19558 No.19564

P2 No.19542

No.19547

No.19553 No.19559 No.19565

P3 No.19543

No.19548

No.19554 No.19560 No.19566

P4 No.19544

No.19549

No.19555 No.19561 No.19567

P5 No.1420

No.19550

No.19556 No.19562 No.19568

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20.HIGH-SPEED CUTTING

FUNCTIONS

The speed at P0 is 0, and the speed at P5 is the rapid traverse rate
specified with parameter No. 1420. The speeds at P1 to P4 are to be
set into speed parameters Nos. 19541 to 19544 as ratio to the rapid
traverse speed (parameter No. 1420).
Any acceleration setting point for which the speed parameters Nos.
19541 to 19544 is set to 0 will be skipped, and the next point whose
speed parameter is set to a non-zero value will be joined together as
acceleration pattern.
The accelerations at P0 to P5 are to be set into acceleration parameters
Nos. 19545 to 19568 as ratio to the reference acceleration. If any of
the acceleration parameters Nos. 19545 to 19568 is set to 0, the
acceleration is assumed 100% (Reference acceleration). Acceleration
parameters should be set to 0 at the acceleration setting point whose
speed parameter is set to 0.
If this function is enabled and parameter No.1671 for an axis are set to
0, the following values are assumed as the reference acceleration for
that axis:
1000.0mm/sec

, 100.0inch/sec

, 100.0 deg/sec

- Example of setting acceleration pattern data

In this example, the machine is equipped with the

S 30/4000.

Motor speed at rapid traverse is 3000 (min

-1

100

150

1000

2000

3000

4000

Speed(min

-1

)

Torque(Nm)

Fig. 20.4 (d) Speed-torque characteristics of model

S 30/4000

Specifications of the motor model

S 30/4000

Rotor inertia

:0.0099(Kgm

)

Maximum torque

:100(Nm)

Speed 0 to 2000(min

-1

)

Torque at rapid traverse

:79(Nm)

Speed 3000(min

-1

)

Minimum torque

:58(Nm)

Speed 4000(min

-1

)

It assumes that 10 (Nm) is needed for the friction torque, so that the
torque for acceleration/deceleration is shown as the following figure.
Because the friction torque is different on each machine, it is
necessary to observe the actual torque output on the machine.
Maximum torque

:90(=100-10)(Nm) Speed 0 to 2000(min

-1

)

Torque at rapid traverse :69(=79-10)(Nm)

Speed 3000(min

-1

)

Minimum torque

:48(=58-10)(Nm)

Speed 4000(min

-1

)

PROGRAMMING

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20. HIGH-SPEED CUTTING

FUNCTIONS

100

1000

2000

3000

4000

Speed(min

-1

)

Torque(Nm)

Fig. 20.4 (e) Torque for Acc/Dec with consideration of friction

Let the torque be x (Nm), the inertia be y (Kgm

), and the ball screw

pitch p (mm), then the acceleration A is calculated as follows:

]

sec

[

]

[

]

[

])

][

sec

([

]

[

]

[

]

[

⋅

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

))

The acceleration at maximum torque 90 (Nm) is,

]

sec

[

7717

0099

The acceleration at torque 69 (Nm) in rapid traverse 3000 (min

-1

) is,

]

sec

[

5916

0099

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

]

40 [msec]/4

=4124

[mm/sec

]

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.

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PROGRAMMING

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20.HIGH-SPEED CUTTING

FUNCTIONS

Table 20.4 (c) Example of setting parameters related to acceleration pattern

Parameter

No.

Setting

Unit

Remarks

Rapid
traverse rate

1420 48000.

mm/
min

The ball screw pitch is assumed 16
mm, so that the rapid traverse rate is
48000 mm/min at the maximum speed
3000 (min

-1

Reference
acceleration

1671

4124.

msec

Reference acceleration is
4124mm/sec

Speed at P1

19541

515

0.01%

- Assuming that parameter No. 1672

(bell-shaped acceleration change
time) is set to 40 (msec), the speed
at P1 will be 2474 mm/min from the
calculation described on the
previous page. Set its ratio to the
rapid traverse rate, or 5.15%.

0.0515=2474/48000

- If parameter No. 1672 (bell-shaped

acceleration change time) is not
set, set about 5.00%.

Speed at P2

19542

6666

0.01%

Since the torque characteristic is
constant (90 Nm) in speeds reaching
2000 min

-1

, set P2 to the ratio of the

speed (32000 mm/min) at 2000 min

-1

to the rapid traverse rate (48000
mm/min).
0.6666=32000 / 48000

Speeds at P3
to P4

19543 to 19544

0.01%

P3 to P4 are skipped because the
torque drops almost linearly from the
speed
2000 (min

-1

) to 3000 (min

-1

Acceleration
at P0

19545,19551,
19557,19563

9356

0.01%

Set half the acceleration at P1, or
9356.

Acceleration
at P1

19546,19552,
19558,19564

18712

0.01%

At P1, 90(Nm) can be used for the
acceleration/deceleration, so set the
ratio 7717 (mm/sec

) to 4124

(mm/sec

(1.8712 = 7717/4124)

Acceleration
at P2

19547,19553
19559,19565

18712

0.01%

At P2, set the same speed as that at
P1.

Acceleration
at P3 to P4

19548 to 19549,
19554 to 19555,
19560 to 19561
19566 to 19567

0.01%

0 is set because P3 to P4 are
skipped.

Acceleration
at P5

19550,19556
19562,19568

14345

0.01%

At P5, 69(Nm) can be used for the
acceleration/deceleration, so set the
ratio 5916 (mm/sec

) to 4124

(mm/sec

(1.4345 = 5916 / 4124)

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20. HIGH-SPEED CUTTING

FUNCTIONS

With the above parameter settings, the acceleration pattern will be
shown as the following figure. From speeds from 0 mm/min to 2474
mm/min, the acceleration as calculated in accordance with the
acceleration pattern is applied; from speeds from 2474 mm/min to
32000 mm/min, an acceleration of 7716 mm/sec

; and from speeds

from 32000 mm/min to 48000 mm/min, the acceleration as calculated
in accordance with the acceleration pattern.

1000

2000

3000

4000

5000

6000

7000

8000

9000

8000

16000

24000

32000

40000

48000

Speed mm/min

Acceleration mm/sec

Fig. 20.4 (f) Acceleration pattern with consideration of friction

NOTE

The values in the model

S 30/4000 speed-torque

characteristic diagram are just typical ones. The
values will change depending on the digital servo
software, parameters, input voltage, and other
factors.

The optimum acceleration will, therefore, change
due to the characteristics of the machine.

- Examples of setting if the acceleration pattern differs depending on whether

acceleration or deceleration is in progress and whether the movement is in the
minus or plus direction

From the effect of gravity and friction, torque for
acceleration/deceleration is different on each condition, such as
acceleration, deceleration or plus move (up), minus move (down).
The following example is for the vertical axis and gravity and friction
torque are assumed as follows.
Torque of gravity : 20 (Nm)
Torque of friction : 10 (Nm)
Because these value are different on each machine, it is necessary to
observe the output torque on the actual machine for deciding
acceleration pattern. The conditions are the same as the previous
example.
(Condition)

Motor speed at rapid traverse

: 3000(min

-1

)

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

)

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20.HIGH-SPEED CUTTING

FUNCTIONS

Maximum torque

: 100(Nm) Speed 0 to 2000(min

-1

)

Torque at rapid traverse : 79(Nm)

Speed 3000(min

-1

)

Minimum torque

: 58(Nm)

Speed 4000(min

-1

)

(1) In case of plus move (up) and acceleration

Because torque of Gravity and friction work against the output
torque of motor, the torque for acceleration/deceleration is as
follows.
Maximum torque

: 70(=100-20-10) (Nm)

Speed 0 to 2000(min

-1

)

Torque at rapid traverse : 49(=79-20-10) (Nm)

Speed

3000(min

-1

)

Minimum torque

: 28(=58-20-10) (Nm)

Speed

4000(min

-1

)

1000

2000

3000

4000

Speed(min

-1

)

Torque(Nm)

Fig. 20.4 (g) Torque for Acc/Dec in case of + move and acceleration

Parameter setting is as follows,

Parameter

No.

Setting

Unit

Remarks

Acceleration
at P0

19545 7277

0.01%

Set half the acceleration at P1, or
7277.

Acceleration
at P1-P2

19546,19547 14554

0.01%

At P1 and P2, 70(Nm) can be used for
the acceleration/ deceleration, so set
the ratio 6002 (mm/sec

) to 4124

(mm/sec

(1.4554 = 6002 / 4124)

Acceleration
at P3-P4

19548 to 19549

0.01%

0 is set because P3 to P4 are
skipped.

Acceleration
at P5

19550 10187

0.01%

At P5, 49(Nm) can be used for the
acceleration/deceleration, so set the
ratio 4201 (mm/sec

) to 4124

(mm/sec

(1.0187 = 4201 / 4124)

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