BendPak Blue Bullet 1302-BAS, Operation And Service Manual

Page: 32 / 68

NOTE:
Loose hoses and hydraulic components will not always
show a visual sign of leakage, however they can cause
aeration of the system by “sucking” air. It is very
important to tighten all hoses and mounting bolts on
hydraulic components monthly.
PRESSURE SETTINGS
There are three critical pressure settings on your bender
that affect its performance These pressures should be
checked weekly. The following is a brief description of
the pressures and the roles they play.
BACK PRESSURE
Back pressure is actually resistance pressure applied to
the back gates during the bending process. The pressure
is transferred to the back gates via the bottom cylinder
and chain assembly. The setting itself is controlled by the
sequence valve. This “resistance” pressure is required in
order to form the shape of the tubing as the radius die
advances. This pressure is read on the gauge attached
to the sequence valve located near the front left side of
the machine. The pressure reading is taken as the dies
advance through the gates during a bend. The normal
operating back pressure should be set at 1600 P.S.l.
In some cases it may be necessary to adjust this
pressure. (See Three Inch and Stainless Bending
Procedures found on pages 21 & 22.)
If the back pressure needs adjusting, proceed as follows:
1. Turn the machine on.
2. Place a radius die and set of back shoes in position.
Tubing will not be required for this operation.
3. Advance the radius die until it begins to pass through
the gates.
4. At this time read the pressure shown on the gauge
attached to the sequence valve. (See figure 3-B)
5. If an adjustment is required, loosen the locking nut
that secures the adjusting screw.
6. To increase the pressure, turn the adjusting screw
clockwise; to decrease, counterclockwise. Never
exceed 2000 P.S.I.
RETURN PRESSURE
This pressure reading is also taken on the gauge located
near the front left side of the machine. The purpose of this
pressure is to maintain adequate tension on the chain
assemblies during the retract sequence. This is important
so that the gates close in unison with the radius die. Upon
initiating the return sequence, hydraulic fluid is “split” and
redirected, so that an equal portion is transferred to the
top cylinder and bottom cylinder simultaneously. If the
pressure is set too high, the machine will groan and strain
when reversing as the top cylinder tries to overcome the
bottom cylinder. If the pressure is too low, the gates may
hesitate or remain open when the radius die retracts as
the top cylinder receives more fluid than the bottom
cylinder. It is seldom necessary to readjust this pressure
setting. The normal operating return pressure should
be set at 350 P.S.l. This pressure reading is taken as the
radius die retracts just after it releases from the back
shoes. This pressure setting is controlled by the flow
control valve.
(See figure 1-A and 2-A)
32 Bender Operation Manual
CAUTION!
Never exceed 2000 P.S.I. for the back pressure
unless specifically instructed to do so by the
factory for special circumstances. If it is necessary
to increase the back pressure, always remember to
return the pressure back to 1600 P.S.I. before
proceeding with the next bend.
CAUTION!
Improper back pressure settings will cause tubing
to wrinkle and/or collapse and may also damage
machine and/or dies.
Figure 2-A
Figure 3-B
Figure 1-A