
16
16.6 Reference Position Return
842
16.6.2 Dogless reference position setting
When there are no dog nor limit switch for reference position return, this
function enables the tool to return the reference position that is set by MTB.
When compared with the dog–based method, an additional operation for
reference position setting is required. However, when an absolute–position
detector is used, a reference position once set is preserved even if the power
is turned off. So, this function is generally applicable when an
absolute–position detector is used.
Time
JOG
ZRN
+Jα
Speed
Reference position return
FL rate (PRM1425)
GRID . . . . . . . . . . . . . . . . . . . . . . . . . . .
ZP α
D Operation procedure
(1) Move the tool near the reference position using a manual operation.
Even if the tool is located near the reference position on the axis, move
the tool away from the reference position once, then move back the tool
toward the reference position. Otherwise, ALM90 occurs in (3) below.
(2) Select the reference position return mode or switch.
(3) Press a button for an axis–and–direction–select–signal + or –, and the
machine moves to the next grid, then stops.
(This position is set as the reference position).
* After the reference position has been set, select the reference
position return mode(ZRN signal is 1) and turn on an
axis–and–direction– select signal, then the tool returns to the
reference position.
The following figure shows the positional relation between the reference
position and the point to which the tool is positioned by manual continuous
feed.
Grid
– direction
Position
after jog feed
+ direction
Reference position for reference position return in the negative direction
Reference position for reference position return in the positive direction
A
B
A
B
D Grid shift
To shift the reference position, the grid can be shifted by the distance
set in PRM1850. The grid shift to be set in the parameter must not
exceed the reference counter capacity (PRM1821).
NOTE ALM090 is issued when G28 is specified and the reference position
has not yet be established.