GP44 Semi-Automatic Strapping Machine
OPERATION -21-
CONROLLED TENSION
The primary tension complete switch (PLC input X06) disengages the strap feed solenoid (Sol 4) (PLC output
Y04) and starts the cam shaft motor M1 (PLC output Y01). As the cam motor turns the camshaft, the bearing
on the Roller Bracket Assembly (High Tension Arm falls into the large detent of the end cam, which pulls
controlled tension on the strap. The tension is controlled by the spring setting on the high tension arm (overall
setting should not be adjusted frequently) and the slip clutch (fine tune setting) on the tension wheel.
RELEASE TENSION, CUT AND WELD. RELEASE STRAP
As the cam shaft continues to turn, the grippers and heater element are activated by bearings that are riding
on the cam. The left gripper extends to grip the trailing end of the strap to maintain the tension that has been
established, and create a gap between the two layers of strap at the overlap which is to be welded. Since
both ends of the strap are now gripped, the tension between the left gripper and the Roller Bracket Assembly
can be released as the Roller Bracket Assembly drops out of the large detent in the end cam. The heater
element enters the gap that has just been created between the two strap layers. The middle gripper then
goes up to the 1
st
compression position to wedge the two layers of strap against the heater element in the
middle, the slide plate on the top and the middle gripper on the bottom. As the middle gripper extends, it cuts
the strap against the right gripper. The heater element retracts out from between the straps. The middle
gripper then extends fully to compress the two layers of heated strap together and holds them for a short
period of time against the slide plate to solidify the weld. As the cam shaft continues to rotate, all the grippers
go down to the home position due to spring pressure and the seal anvil retracts snapping the tensioned,
sealed strap against the package.
NOTE: There must be sufficient tension to allow this to happen.
As the camshaft turns, the cam proximity switch (B switch) (PLC input X05) turns off. It then starts a short timer
in the PLC, which stops the camshaft (by applying a brake), in the home position. When, the cam proximity
switch (B switch) (PLC input X05) turns off, the cycle starts over again with operation #1.
AUTO FEED CYCLE
With no strap in the machine, when the machine is turned on, the Auto Load Switch (PLC input X20) should be
off. This makes sure that the auto load solenoid (Sol 7) (PLC output Y22) is extended which creates a track
into the head.
NOTE: If the auto load solenoid (Sol 7) (PLC output Y22) is not engaged, a track to the head is not created
and the strap runs directly into the accumulator box.
The end of the strap must be fed until it is between the two initial load rollers. When the Auto Load Switch
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