PROGRAMMING6. REFERENCE POSITION
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Positioning to the intermediate or reference positions are performed at the
rapid traverse rate of each axis.
Therefore, for safety, the cutter compensation, and tool length
compensation should be cancelled before executing this command.
The coordinates for the intermediate position are stored in the CNC only
for the axes for which a value is specified in a G28 block. For the other
axes, the previously specified coordinates are used.
Example N1 G28 X40.0 ; Intermediate position (X40.0)
N2 G28 Y60.0 ; Intermediate position (X40.0, Y60.0)
In a system without an absolute–position detector, the first, third, and
fourth reference position return functions can be used only after the
reference position return (G28) or manual reference position return (see
III–3.1) is made. The G30 command is generally used when the automatic
tool changer (ATC) position differs from the reference position.
In general, it is commanded immediately following the G28 command or
G30. For incremental programming, the command value specifies the
incremental value from the intermediate point.
Positioning to the intermediate or reference points are performed at the
rapid traverse rate of each axis.
When the workpiece coordinate system is changed after the tool reaches
the reference position through the intermediate point by the G28
command, the intermediate point also shifts to a new coordinate system.
If G29 is then commanded, the tool moves to to the commanded position
through the intermediate point which has been shifted to the new
coordinate system.
The same operations are performed also for G30 commands.
G27 command positions the tool at rapid traverse rate. If the tool reaches
the reference position, the reference position return lamp lights up.
However, if the position reached by the tool is not the reference position,
an alarm (No. 092) is displayed.
Before a machine coordinate system is established with the first return to
the reference position after power–on, the manual and automatic
reference position return feedrates and automatic rapid traverse rate
conform to the setting of parameter No. 1428, if any, for each axis. Even
after a machine coordinate system is established upon the completion of
reference position return, the manual reference position return feedrate
conforms to the setting of the parameter. Even after a machine coordinate
system is established upon the completion of reference position return,
the manual reference postiion return feedrate conforms to the setting of
the parameter.
Explanations
D Reference position
return (G28)
D 2nd, 3rd, and 4th
reference position return
(G30)
D Return from the
reference position (G29)
D Reference position
return check (G27)
D Setting of the reference
position return feedrate