The COUPLE Command [L]

The COUPLE command is used to synchronize the linear axes of a lathe with the spindle. This command can be used to machine single or multiple start threads in one pass. It is only valid for lathes but may not be available on a specific lathe.

\textbf{COUPLE /} \begin{pmatrix} \begin{array}{l} \textbf{ON} \\ \textbf{OFF} \end{array} \end{pmatrix}

ON is used to begin synchronization of the linear axes with the spindle. OFF returns the machine to the normal mode of operation. All motions will be synchronized, from the machine’s position when ON is coded to the last position before OFF is coded.

A PITCH command must be specified before the first COUPLE command is coded. The PITCH command indicates the number of threads per CL unit and the number of starts. Once PITCH is coded, it will remain in effect until changed by another PITCH command.

When creating a thread that has multiple starts, only a single pass is needed in the CL file. GENER will repeat the motions between the COUPLE/ON and COUPLE/OFF commands for as many starts as are specified. A maximum of 20 motions may be coded in the CL file between the COUPLE/ ON and COUPLE/OFF commands when machining threads with multiple starts.

The following example cuts a 10 TPu (threads/unit) thread with 2 starts:

RAPID,GOTO/5.25,1.25  $$ Position clear thread
PITCH/10,MULTRD,2
RAPID,GOTO/5.25,1     $$ Start of thread COUPLE/ON $$ Synchronize
GOTO/0.1,1            $$ Cut thread
GODLTA/-0.1,.1        $$ Ramp out
COUPLE/OFF            $$ Disengage

The second start will be cut automatically. The machine will retract in a direction opposite to the feed-in direction, rapid to the initial clearance point, rapid to the startup point offset by one pitch and then cut the second thread to the disengage point.

A THREAD command must not be coded within a COUPLE block. This is because they are both used to synchronize the linear axes with the spindle. An error message will be output if this is attempted.