Tweco SC10 - Manual (Page 28)

OPERATION 4-2 Manual 0-2479
5. PIERCE HT (inches) Control
The PIERCE HT (height) controls the starting distance
from torch to workpiece from nearly zero to 1/2
inches.
After receiving a start signal with one of the FIND
HT modes selected, FIND HT indicator ON, the
standoff control equipment lowers the torch from the
retracted position until it contacts the metal to be cut.
The standoff equipment then lifts the torch back up
the distance above the plate set by the adjustable
PIERCE HT control from nearly zero to over 1/2".
When doing a piercing operation it is best to start
from the highest possible position to minimize splat-
ter onto the end of the torch. Splatter onto the torch
shield and tip can block the cutting tip orifice.
6. PIERCE DELAY (sec) Control
The PIERCE DELAY controls the arc transfer (OK-
To-Move) or motion start signals to the cutting ma-
chine. This delay allows time for the arc to pierce
through the material. The delay time is adjustable
from zero to over three seconds.
NOTE
The cutting machine controller may also have a
motion delay which will add to the total delay, if so
it should be set to zero.
Height regulation will be inhibited during the delay
time selected.
7. END OF CUT RETRACT (%) Control
The END OF CUT RETRACT contols the raising (re-
tracting) of the torch from zero to 100% of the selected
setting of the END OF CUT RETRACT (%) Control.
With one of the FIND HT modes selected, FIND HT
indicator ON, the torch is raised at the end of a cut
operation when the start signal is removed. The
amount of time that it takes to raise the torch can be
reduced by not retracting the torch fully, if not re-
quired.
8. T.H.C. ACTIVE Indicator
The T.H.C. (Torch Height Control) ACTIVE indica-
tor turns ON when the height is under active con-
trol. The T.H.C. ACTIVE indicator turns OFF when
no initial arc transfer signal is received, corner slow-
down (CSD) inhibit signal is on, or the voltage is ris-
ing rapidly. When the T.H.C. ACTIVE indicator is
OFF the standoff is not being regulated during that
time.
The voltage rising rapidly can be caused by cutting
over a kerf, other hole, or an arc voltage outside the
regulation limits of 65 to 195 volts
9. TORCH UP/DN Pushbuttons and Indicators
The momentary TORCH UP/DN pushbutton
switches allow setting the torch position manually.
Pressing the TORCH UP switch will cause the UP in-
dicator to turn ON. The DN (Down) indicator turns
ON if the TORCH DN pushbutton is pressed.
The manual control may be used to set initial height
when the FIND HT indicator is OFF. The controls
can also be used to adjust the standoff when the
AUTO HT indicator is OFF.
The manual controls should not be used while cut-
ting if the AUTO HT indicator is ON (see ARC VOLTS
Control).
B. Rear Panel
The Standoff Control rear panel has only one output con-
nector for the lifter motor assembly cable. Signals include
drive (up to +/-20 vdc), tachometer (0 to +/- 15 vdc) and
TORCH ON WORK switch (NC).
4.04 Sequence Of Operations
This Section describes the typical sequences for various
operations. The information is suppied to give the op-
erator an understanding of what is occuring during the
cutting cycle. Each of the following paragraphs describe
a different operation as follows:
• Paragraph ‘A’ - Fully Automatic Mode With Pierce
Start
• Paragraph ‘B’ - AUTO HT ON and FIND HT indi-
cators OFF
• Paragraph ‘C’ - AUTO HT Indicator OFF and FIND
HT Indicator ON
• Paragraph ‘D’ - Fully Manual Mode
• Paragraph ‘E’ - Starting Off The Plate
A. Fully Automatic Mode (AUTO HT and FIND
HT Indicators ON) With Pierce Start
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.