FANUC Series 30i/300i/300is-MODEL A. Machining Center System. User's manual - page 87

PROGRAMMING

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20. HIGH-SPEED CUTTING

FUNCTIONS

HIGH-SPEED CUTTING FUNCTIONS

Chapter 20, "HIGH-SPEED CUTTING FUNCTIONS", consists of the
following sections:

20.1 AI CONTOUR CONTROL FUNCTION I AND AI

CONTOUR CONTROL FUNCTION II (G05.1)...................653

20.2 MACHINING CONDITION SELECTING FUNCTION ......670
20.3 JERK

CONTROL...................................................................671

20.4 OPTIMUM TORQUE ACCELERATION/

DECELERATION..................................................................676

20.5 HIGH-SPEED CYCLE MACHINING ..................................689

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FUNCTIONS

20.1

AI CONTOUR CONTROL FUNCTION I AND AI CONTOUR
CONTROL FUNCTION II (G05.1)

Overview

The AI contour control I and AI contour control II functions are
provided for high-speed, high-precision machining. This function
enables suppression of acceleration/deceleration delays and servo
delays that become larger with increases in the feedrate and reduction
of machining profile errors.
There are two types of AI contour control; these two types are referred
to temporarily as AI contour control I and AI contour control II. AI
contour control I is designed mainly for part machining, and AI
contour control II is for machining of successive minute straight lines
such as mold machining and for machining by curve commands in
NURBS and so on.
When a high-speed processing option is used with AI contour control
II, high-speed operation processing is enabled, which reduces the
interpolation cycle, therefore, faster and more precise machining is
enabled. In addition, an option to expand read-ahead blocks to up to
1000 blocks is available.
In the descriptions below that are common to AI contour control I and
AI contour control II, the term "AI contour control" is used.

Format

G05.1 Q_ ;

Q1 : AI contour control mode on
Q0 : AI contour control mode off

NOTE

1 Always specify G05.1 in an independent block.
2 The AI contour control mode is also canceled by a

reset.

3 The AI contour control mode can be turned on at

the start of automatic operation by setting bit 0
(SHP) of parameter No. 1604.

The AI contour control mode can be controlled also with the formats
that have been used for the conventional advanced preview control,
high-precision contour control, and AI high-precision contour control
functions.

G08 P_ ;

P1 :

AI contour control mode on

P0 :

AI contour control mode off

G05 P_ ;

P10000 : AI contour control mode on
P0 :

AI contour control mode off

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NOTE

1 Always specify G08 and G05 in an independent

block.

2 G05 can be specified only for AI contour control II.
3 The AI contour control mode is also canceled by a

reset.

4 Valid functions are limited depending on the

command format. For details, see the description
of "Valid functions".

Valid functions

The functions listed below are valid in the AI contour control mode.

Valid functions are limited depending on the command format and
whether AI contour control I or II is used.

Function

AI contour control I

AI contour control II

AI contour control II with

high-speed processing

Number of blocks read
ahead

(When G8 is specified: 1)

200

(When G8 is specified: 1)

600

(*1)

(When G8 is specified: 1)

Look-ahead
acceleration/deceleration
before interpolation

Linear or bell-shaped

acceleration/deceleration

Linear or bell-shaped

acceleration/deceleration

Linear or bell-shaped

acceleration/deceleration

Speed control with feedrate
difference on each axis

Enabled Enabled Enabled

Speed control with
acceleration in circular
interpolation

Enabled Enabled Enabled

Speed control with
acceleration on each axis

Enabled

(When G8 is specified:

Not enabled)

Enabled

(When G8 is specified:

Not enabled)

Enabled

(When G8 is specified:

Not enabled)

Smooth speed control

Not enabled

Enabled

(When G8 is specified:

Not enabled)

Enabled

(When G8 is specified:

Not enabled)

Speed control with cutting
load

Not enabled

Enabled

Disregard of feedrate
command

Not enabled

Enabled

*1 The number of blocks can optionally be expanded to 1000

blocks.

Explanation
- Look-ahead acceleration/deceleration before interpolation

There are two types of look-ahead acceleration/deceleration before
interpolation, the linear acceleration/deceleration type and the
bell-shaped acceleration/deceleration type.
Look-ahead bell-shaped acceleration/deceleration before interpolation
produces smoother acceleration/deceleration.

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FUNCTIONS

- Setting an acceleration

A permissible acceleration for the linear acceleration/deceleration of
each axis is set in parameter No.1660. For bell-shaped
acceleration/deceleration, acceleration change time (B) (period of
transition from constant speed state (A) to constant acceleration/
deceleration state (C)) is set in parameter No.1772. In the constant
acceleration/deceleration state (C), acceleration/deceleration is
performed with the maximum tangential acceleration not exceeding
the permissible acceleration of each axis specified in parameter
No.1660.
The acceleration change time specified in parameter No.1772 is held
constant, regardless of the tangential acceleration.

Tangential feedrate

An optimum gradient is
automatically calculated from the
setting made in parameter
No.1660.

Time set in parameter No.1772

(A) (B)

(B)

(A)

(C)

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- Method of determining the tangent acceleration

Acceleration/deceleration is performed with the largest tangent
acceleration/deceleration that does not exceed the acceleration set for
each axis.
(Example)
X-axis permissible acceleration: 1000 mm/sec

Y-axis permissible acceleration: 1200 mm/sec

Acceleration change time:

20 msec

Program:

N1 G01 G91 X20. F6000

..Move on the X-axis.

G04 X0.01

N2 Y20.

...........................Move on the Y-axis.

G04 X0.01
N3 X20. Y20.

...................Move in the XY direction (at 45 degrees).

The acceleration in N3 is 1414 mm/sec

. At this point, the

acceleration on the X-axis is equal to the set value (1000 mm/sec

20ms

1000mm/sec

gradient

Tangent feedrate

1200mm/sec

gradient

1414mm/sec

gradient

- Acceleration

Acceleration is performed so that the feedrate programmed for a block
is attained at the beginning of the block.
Acceleration can be performed over several blocks.

Speed control by look-ahead
acceleration/deceleration before
Programmed speed

Feedrate

Time

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- Deceleration

Deceleration starts in advance so that the feedrate programmed for a
block is attained at the beginning of the block.
Deceleration can be performed over several blocks.

Feedrate

Time

Deceleration

start point

Deceleration
start point

Speed control by look-ahead
acceleration/deceleration before

interpolation

Programmed speed

- Deceleration based on a distance

If the total distance of the blocks read ahead becomes shorter than or
equal to the deceleration distance obtained from the current feedrate,
deceleration starts.
If the total distance of the blocks read ahead during deceleration
increases, acceleration is performed.
If the blocks of a small amount of travel are successively specified,
deceleration and acceleration may be performed alternately, making
the feedrate inconsistent.
To avoid this, decrease the programmed feedrate.

- Function for changing time constant of bell-shaped acceleration/deceleration

Bell-shaped acceleration/deceleration before interpolation is
performed using the parameter-set acceleration and acceleration
change time. If a low feedrate is specified, a linear acceleration/
deceleration may not achieve the specified acceleration as shown:

Linear acceleration/deceleration not achieving
specified acceleration/deceleration

Specified
feedrate

Feedrate

Time

T1 : Time obtained from specified feedrate and specified acceleration (specified

feedrate/acceleration (parameter No. 1660))

T2 : Acceleration change time (parameter No. 1772)

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In such a case, set bit 3 (BCG) of parameter No. 7055 to 1. Then, the
internal acceleration and vector time constant of
acceleration/deceleration before interpolation are changed to make the
acceleration/deceleration pattern as close as possible to the optimum
bell-shaped acceleration/deceleration before interpolation based on a
specified acceleration/deceleration reference speed, and so
acceleration/deceleration time is reduced.

Acceleration/deceleration curve

Specified

feedrate

Feedrate

T1'

T2'

There are three methods for specifying the acceleration/deceleration
reference speed.

(1)  Specifying the speed using an F in a G05.1 Q1 block
(2)  Setting the speed on parameter No.7066
(3)  Setting the speed specified with the F command issued at the

start of cutting as the reference speed

When F is specified in a G05.1Q1 block, the specified feedrate is
assumed to be the acceleration/deceleration reference speed. This
command can be used only in the feed per minute mode.
If no F command is specified in a G05.1Q1 block, the feedrate
specified in parameter No. 7066 is assumed to be the
acceleration/deceleration reference speed. If 0 is set in parameter No.
7066, the F command specified in the cutting start block is assumed to
be the acceleration/deceleration reference speed.

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- Automatic feedrate control function

In AI contour control mode, the feedrate is automatically controlled
by the reading-ahead of blocks.
The feedrate is determined using the following conditions. If the
specified feedrate exceeds the determined feedrate, acceleration/
deceleration before interpolation is performed to achieve the
determined feedrate.

<1> Feedrate changes on each axis at a corner and the permissible

feedrate change that has been set

<2> Expected acceleration on each axis and the permissible

acceleration that has been set

<3> Cutting load that is expected from the travel direction on the

Z-axis

Specified tool path

Tool path assumed when
Al contour control is not

used
Tool path assumed when Al

contour control is used

The machining error is decreased
because of the deceleration with

the acceleration.

The machining error is decreased
because of the deceleration by

difference in feedrate.

For details, see the explanation of each function.

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