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WCS-SIF-01
Training & Maintenance Manual
Pneumati
c
Parker Hannifin Corporation
Pneumatic Division
Richland, Michigan
www.parker.com/pneumatics
Description & Operation
General Operation of
Spotwelding Units – 2 and 4 ported guns
Spotwelding systems control both retract (pre-stroke) and
weld stroke motions. When a 4 ported cylinder is used, the
control block functions as follows:
1. The retract (pre-stroke) valve is energized, allowing
the weld cylinder to extend under full line pressure and
moving to its predetermined position prior to welding.
2. The weld stroke valve is then energized using a selected
weld schedule pressure. The closure speed of the weld
tips is controlled by the use of an adjustable flow control,
thus creating “low impact”.
3. Immediately following weld tip contact with the sheet
metal, two actions take place.
a. The proportional / quick dump valve that senses
pressure allows the front end of the cylinder to exhaust
(by-passing the flow control), providing weld schedule
pressure instantly.
b. The proportional / quick dump valve also actuates a
feedback sensor to start the weld cycle.
4.
Once the weld cycle is complete, the weld stroke valve is de-
energized, allowing the weld tips to open under full pressure.
5.
The retract (pre-stroke) valve is then de-energized, allowing
the weld cylinder to open completely under full line pressure.
Note: Dual pressure is provided to the control block. Line
(high) pressure is used for both retract stroke and weld stroke
open. Weld schedule pressure is used for weld stroke close.
Dual pressure provides for weld tips to be closed for tip
dressing using any pressures available, from as low as
5 PSIG to maximum line pressure. 2 ported guns perform
the same steps as above, except that the retract (pre-stroke)
portion of the cylinder does not exist. Steps 2–4 only apply.
W-
Pw
Pr
ANSI (2 Ported Cylinder Option)
Inductive Sensor / Connection: Turck
Connection Diagram Inductive Sensor
1 Brown +24 VDC Power Supply
3 Blue 0 V Power Supply
4 Black Switch Wire
W+
1
pnp
+
3
-
4
W-
ANSI (4 Ported Cylinder Option)
Inductive Sensor / Connection: Turck
Connection Diagram Inductive Sensor
1 Brown +24 VDC Power Supply
3 Blue 0 V Power Supply
4 Black Switch Wire
W+R-
R+
Pw
Pr
1
pnp
+
3
-
4
Front View
Back View
Weld Stroke
Valve
Retract
(Pre-Stroke)
Valve
(4 Ported
Gun Only)
Feedback
Sensor
Flow
Control
Weld Stroke
Valve
Retract
(Pre-Stroke)
Valve
(4 Ported
Gun Only)