YASKAWA yasnac lx3 - Page 43

(2) If the position is the reference point, the
return–to–reference lamp lights. The posi–
tion is the reference point in all the axial
directions specified, the automatic operation
is continued further.
If the position is not
the reference point even along one axis,
this constitutes the return-position–error,
and the automatic operation is interrupted.
(Cycle start lamp goes off. )
Notes :
1.
The reference point is an fixed point on the
machine tool to which the tool can return by
the motion under the control of the automatic
reference point return or G28 automatic ref–
erence point return function.
See 6.2.1,
“Automatic Reference Point Return .“
2. If G27 is commanded in the tool position off-
set mode, the tool returns to the position
displaced from the reference point by the
tool offset value. Positioning cannot be made
at the reference point. Before commanding
G27, cancel the tool offset mode.
EXAMPLE
a.
b.
Canceling tool offset in the block pre-
ceding G27.
TEIE]OO ;
G27 U.. . W.. . ;
Canceling in the block containing G 27.
G27 U.. . W.. . TGT.; OO ;
3,
The mirror image function is effective with the
motion commanded by G27. To avoid the
return position error, command G 27 in the
G 69 mode ( Opposite tool post mirror image
off) .
2.8.11
AUTOMATIC RETURN TO REFERENCE POINT
(G 28)
(1) G28 X(U)””” z(w) . . . ;
With this command, the tool can be brought
back to the reference point automatically
after passing througkl an interim point. In
other words, the tool positions to the com-
manded absolute coordinate position (X , Z )
or incremental position (U, W) by moving
simultaneously along the two axes, and then
automatically returns to the reference point
by the reference point return function.
The specified point (X, Z) or (U, W) is
known as “INTERIM POSITIONING POINT ,“
or “INTERIivl POINT. “
(2)
(3)
REFERENCE
INTERIU POSITIONING POINT POINT
,,AR:T’OYcd+---
-x
4+
.-”
POINT z
i’
\i”
z
RETURN TO REFERENCE
x
— +Z
Fig, 2.14
The tool does not move along the axis for
which instruction is omitted.
When the return to reference motion is com–
pleted, Reference Point Return lamp for the
returned axis lights. When the tool returns
to the reference point in both axes, the
automatic operation is resumed.
The series of RETURN TO REFERENCE
motions are as follows, With initialpower
application, the return motions to the
reference point are as shown below in the
low-speed mode as shown below.
APPROACH SPEED 1
,pEE,r-U::j::TER
I
SPEED REDUCTION LI!vIIT SVV
REFERENCE
POINT
Fig, 2.15
Thereafter, the RETURN TO REFERENCE
POINT motion is in rapid traverse as under
the command of GOO.
I
RAPID TRAVERSE
Fig. 2.16
(4) However, when low traverse speed is speci–
fied by parameter #6010D 5 set to 1, the
same law motion speed as in the 1st time is
obtaineci.
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