mandrel may be adjusted hydraulically or manually,
There arc two basic types of clamp die installation:
depending on the type of machine used. You should
manual and hydraulically actuated. The manual-
position the tip of the mandrel at approximately the
actuated clamp die is a simple-hinged die holder that is
tangent point of the bend. Once the mandrel is
swung up into place. The holding power is provided by
positioned, do not change its setting during the bending
a yoke assembly and setscrew that is fastened to a
evolution. If using a flexible mandrel, ensure that all
retaining post that is bolted to the bend die. The
segments of the mandrel bend in the directionof the pipe
hydraulically actuated clamp die is also bolted to the
bend. After the machine is set up, you are ready to bend
bend die and uses a series of linkage to operate the
your pipe.
clamp die. A small hydraulic cylinder applies pressure
to the linkage to firmly clamp the pipe to the bend die.
Select your pipe carefully, ensuring that it is free of
When setting up and adjusting the clamp die, use a
noticeable defects and blemishes. The pipe should then
sample piece of pipe of the same diameter as the pipe
be cleaned to remove all grease, oil, scale, and rust. If
to be bent to act as a gauge. Ensure that the face of the
using a mandrel, use a lard- or a lanolin-based lubricant
clamp die is not bottomed against the bend die. If it is
to coat the mandrel before inserting the pipe over the
bottomed, no clamping pressure will be applied to the
mandrel. Never use petroleum-based products to
pipe to be bent.
lubricate the mandrel. Insert the pipe over the mandrel,
The next step is to install the pressure die. The
if used, ensuring that it slides freely, and clamp the pipe
pressure die is mounted to a movable pressure die
in place. Next, bring the pressure die in contact with the
holding bar to allow the pressure die to slide forward
pipe. Before bending, draw a pencil mark around the
with the pipe as it is bent. The die holding bar is mounted
pipe at the face of the clamp die. During the bending
on a slide keyway and is either manually or
operation, watch the pencil mark for signs of slippage.
hydraulically operated. Loosely mount the pressure die
If slippage is allowed, you will get wrinkles in the pipe.
on the holding bar and bring the die up to a sample pipe
Severe wrinkles will break the pipe and damage the
clamped in the clamp die. Align the pressure die to the
mandrels if the bending motion is not stopped
pipe and tighten the pressure die mounting bolts. The
immediately. Set the automatic stop on the machine 2
pressure die is never adjusted with as much pressure as
or 3 degrees over the desired degree of bend (this allows
the clamp die. It is designed to provide support to the
for spring-back in the pipe after the pressure die is
pipe not clamping action. Ensure that there is clearance
removed), and slowly bend the pipe. After bending the
between the pressure die and the bend die.
pipe, back out the mandrel and remove the pipe from
the dies.
The final die to bc installed is the wiper die. The
wiper die is an optional die, and its use is determined
POWER PIPE BENDER SAFETY.--The
by the wall thickness of the pipe, the degree of bend,
following are some of the more common safety
and operator preference. It is mounted in front of the
practices used with power pipe benders:
bend die to guide the pipe into the bend die. There are
Always wear proper safety equipment,
no special adjustments for the wiper die.
especially safety glasses and hearing protection.
If you are bending thin wall pipe or tubing, or
Know your specific equipment and qualify on its
making short radius bends, you may want to USC a
operation.
mandrel to support the wall of the pipe. By supporting
the pipe wall, the mandrel reduces the flattening and
Never exceed equipment capacity.
wrinkling of the pipe during the bending evolution.
Mandrels may either be rigid or flexible. The rigid type
Cycle the machine through a complete cycle
provides support only at the tangent (start) of the bend.
prior to loading the pipe. Check for smooth
The clearance between the rigid mandrel and the pipe
operation and ensure all installed equipment is
should not exceed 20 percent of the wall thickness of
firmly fastened.
the pipe. Flexible mandrels, on the other hand, provide
Never attempt to bend pipe alone, especially on
support throughout the bend area. Clearance for flexible
rotary benders.
mandrels range from 0.001 to 0.095 inch. Choose the
mandrel that best meets the requirements of the job at
When using the portable pipe bender, do not
hand.
stand in front of the ram during the bending
After choosing the proper mandrel, thread the
evolution. If the pipe slips or the frame and pins
mandrel onto the mandrel rod and tighten. Again, the
Fail, you could be seriously hurt.
16-14