Tweco SC10 - Manual (Page 29)

Manual 0-2479 4-3 OPERATION
3. When the T.O.W. switch opens, the torch down-
ward motion is reversed and it slowly rises until
the T.O.W. switch closes which starts the PIERCE
HT timer. The torch continues upward for the
time required to reach the selected pierce height
setting.
4. A start signal is sent to the Plasma Power Supply
and the Standoff Control PLASMA ON indicator
turns ON. The pilot starts after pre-flow and im-
mediately, if the initial height is correct, the cut-
ting arc is established at which time the Plasma
Power Supply sends an OK-To-Move signal to the
Standoff Control through the Remote Control.
5. Receiving the OK-To-Move signal from the
Plasma Power Supply starts the PIERCE DELAY.
As the PIERCE DELAY ends the OK-To-Move sig-
nal is sent to the cutting machine controller
through the Remote Control starting the horizon-
tal travel.
6. At the same time, the T.H.C. ACTIVE indicator
turns ON and the torch moves to the desired cut-
ting standoff as determined by the pre-selected
ARC VOLTS Control, unless the cutting machine
corner slowdown (CSD) is ON, or the arc voltage
is outside the range of 65 to 195V inhibiting it.
Even if the standoff is inhibited, because the cut
is starting in a corner, the controller is enabled for
1/2 second to position the torch down to the
proper cutting height. Without this feature the
first few inches could be cut at excessive standoff
adversely affecting the quality.
7. The piece is cut then the cutting machine removes
the start signal. The arc goes out removing the
OK-To-Move from the Plasma Power Supply.
8. When both the start and OK-To-Move signals are
removed (allows for current ramp down for sys-
tems that have that feature) the retract timer is
activated to rapidly raise the torch up to clear ob-
structions, such as cut out pieces that tilt up, while
traversing to the next piece to be cut. The amount
of retract is set from zero to 100% by the END OF
CUT RETRACT Control. The torch remains re-
tracted until the sequence repeats with the next
start signal.
B. AUTO HT ON and FIND HT indicators OFF
The operator sets the torch height manually. Refer to
paragraph 'D' for "Starting Off The Plate (Workpiece)".
1. The cutting machine controller sends a start sig-
nal to the Standoff Control through the Remote
Control (RC6010).
2. A start signal is sent to the Plasma Power Supply
and the Standoff Control PLASMA ON indicator
turns ON. The pilot starts after pre-flow and im-
mediately, if the initial height is correct, the cut-
ting arc is established at which time the Plasma
Power Supply sends an OK-To-Move signal to the
Standoff Control through the Remote Control.
3. Receiving the OK-To-Move signal from the
Plasma Power Supply starts the PIERCE DELAY.
As the PIERCE DELAY ends the OK-To-Move sig-
nal is sent to the cutting machine controller
through the Remote Control starting the horizon-
tal travel.
4. At the same time, the T.H.C. ACTIVE indicator
turns ON and the torch moves to the desired cut-
ting standoff as determined by the pre-selected
ARC VOLTS Control, unless the cutting machine
corner slowdown (CSD) or the arc voltage is out-
side the range of 65 to 195v inhibiting it , . Even
if the standoff is inhibited, because the cut is start-
ing in a corner, the controller is enabled for 1/2
second to position the torch down to the proper
cutting height. Without this feature the first few
inches could be cut at excessive standoff adversely
affecting the quality.
5. The piece is cut then the cutting machine removes
the start signal. The arc goes out removing the
OK-To-Move from the Plasma Power Supply.
6. The torch does not retract.
C. AUTO HT Indicator OFF and FIND HT
Indicator ON
NOTE
The standoff height is not controlled during the
cut except manually by the operator using the
TORCH UP/DN switches.
1. The cutting machine controller sends a start sig-
nal to the Standoff Control through the Remote
Control (RC6010).
2. The Standoff Control starts to find height by rap-
idly lowering the torch from the retracted posi-
tion towards the work. When the torch contacts
the work or the bottom of torch travel if not over
the work, it opens the normally closed (NC) torch
on work (T.O.W.) switch in the Lifter Motor As-
sembly.
3. When the T.O.W. switch opens the torch down-
ward motion is reversed and it slowly rises until
the T.O.W. switch closes which starts the PIERCE
HT timer. The torch continues upward for the
time required to reach the selected pierce height
setting.