Heating Stage; Change-Over Stage - Hürner HWT 400–WeldControl Manuel Utilisateur

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height is not indicated on the screen during an automode-managed
bead build-up stage.
When the welding is performed with steel master clamps,
using an optional additional cylinder that adds stability to
the master clamps is recommended if the size of the welded
components is 250 mm or larger. Install it, if you use it, on
Info
top of the clamps per the manual that ships with it. Keep in
mind that the additional, reinforcing cylinder, when it
is used, has to be enabled for the upcoming welding
operation in the Configuration Menu, under Settings
(see Sect. 4.1.2), or the machine will compute incorrect
welding pressures and the satisfactory quality of the
joint cannot be guaranteed.

4.3.5 Heating Stage

After the bead build-up stage (t
Sect. 4.4 below) was completed, pressure must be reduced. The lower
pressure will then be applied for the entire duration of the heat-
soaking stage (t in the diagram), in which the pipe butts continue to
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soak heat from the plate.
When the bead build-up stage is not automode-managed, the pressure
is decreased either with the manual pressure release regulateur or the
full pressure release valve, and the decrease has to be observed on the
display. When the full release valve is used, the hydraulic and control
unit keeps the heating pressure below the required maximum through-
out the heating stage by re-opening the release valve as needed if the
pressure rises. If the welder uses the release regulator, this automatic
control is not available. In this case, it is under the operator's respon-
sibility to compensate for potential pressure fluctuations.
The machine also moves on to the heating stage if the welder decreases
the pressure to a level below the heat-soaking maximum before the
countdown of the bead build-up stage is completely over – which
may happen if the bead is o.k. earlier than expected. However, such
a pressure decrease has to be quick. In these cases, the bead build-up
time shortened by the early decrease is saved to memory as the build-
up time for this welding and will be used as a reference for possible
automode-managed build-up stages at a later time.
Full contact has to be continuously established between the
heating plate and the bead, even with lower pressure. While
Important
heating, if contact between them is lost somewhere along
the circumference, welding has to be aborted and repeated.
If the control unit detects an error (such as insufficient pres-
sure not readjusted by the welder or excessive heating time),
it also aborts welding and displays an error message.

4.3.6 Change-over Stage

An audible signal indicates the imminent change-over
d u r i n g t h e l a s t 1 0 s e c o n d s o f t h e h e a t - s o a k i n g
stage.
Info
At the end of the heating stage, push the mover lever on the hydraulic
unit to its move-apart position in order to move the carriage apart.
Then remove the heating plate from in-between the pipes.
In the change-over stage, too, all relevant parameters are shown on
the screen.
Version January 2020
in the welding process diagram in
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HÜRNER HWT 400–WeldControl User's Manual
HEAT SOAK PHASE
Heat Soak Time :148s
230°C MAX 5.0bar
229°C ACT. 3.5bar
Display 25
Remove plate
Change-over : 8 s
230°C MAX 5.0bar
229°C ACT. 3.5bar
Display 26
Build Joining Press.
230°C NOM. 16.5bar
229°C ACT. 14.5bar
Display 27
EN
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