
B–62073E–1/04 2. INTERFACE BETWEEN CNC AND PMC–NA OR NB
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2.3.59 Tool retraction and recovery (15–M/T)
The tool retraction and recovery function retracts a broken tool from a workpiece so that the tool can be replaced
or the machining checked. The function also returns the replaced tool to the correct location to restart machin-
ing.
If the clearance is specified in the program in advance, a tool is retracted by the specified clearance when a
signal is accepted from the machine. The function can therefore be used for retracting a tool when the tool is
found to be broken.
Basic procedure for tool retraction and recovery
1 When tool retraction signal TRESC input from the PMC goes high while automatic operation is started,
stopped, or held, the tool is retracted by the distance specified in the program. The position to which the
tool retracts is called the retraction position. When TRESC goes high while automatic operation is started,
if a block is being executed, the tool is retracted after the block is suspended. When retraction ends, the
machine enters the automatic operation hold state. The clearance and direction can be specified by the
program. If these values are not specified by the program, the tool is not retracted.
When TRESC goes high, the machine enters the tool retraction mode, and tool retraction mode signal
TRACT goes high to notify the PMC that the machine has entered the tool retraction mode.
2 In the manual mode, when it is necessary to replace the tool or measure workpieces, the tool can be moved
manually, such as by continuous manual feed, incremental feed, or manual handle feed. This operation
is called manual retraction. The path along which the tool retracts is automatically stored in the control unit.
The number of paths which can be stored, however, is limited (refer to the operator’s manual for details).
3 When the control unit has reentered the automatic mode and tool retraction signal TRRTN goes high, the
control unit returns the tool automatically to the retraction position along the same path that the tool was
moved by manual operation. This operation is called recovery. When the tool has been returned to the
retraction position, tool retraction completion signal TRSPS goes high.
4 When the cycle is started at the retraction position, the tool is first returned to the position where TRESC
went high. This operation is called repositioning. When repositioning is complete, TRACT goes low to
notify the PMC of the end of the tool retraction mode. The operations performed differ according to the
status of automatic operation when the machine entered the tool retraction mode.
i) When the machine enters the tool retraction mode while automatic operation is started, the automatic
operation that has been held is resumed after the tool is repositioned.
ii) When the machine enters the tool retraction mode while automatic operation is stopped or held, the
machine returns to the same mode after the tool is repositioned. If the cycle is restarted, automatic
operation is resumed.
X
Y
Z
:ăProgrammed escape position
:ăTool retract position in manual operation
:ăRetract path
:ăManual operation
ă(retract path)
:ăReturn path
:ăRe-positioning
:ăPosition in which the tool escape signal goes to HIGH"