Hürner HWT 400–WeldControl Bedienungsanleitung Seite 59

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P + P
P
1 t
P
2
t t
1
The nominal temperature, at which the hydraulic and control unit
should keep the heating element, can be changed using the ñ and ò
cursor keys. After such a change, the display shows the actual tem-
perature changing slowly to the new nominal temperature.
The welder must wait for the display to show the new nominal
temperature before using the machine!
Important
The welding proper has the four stages in the diagram below that are
explained in the following sections. It is under the welder's responsi-
bility to verify the correct welding pressures and times.
As a preparation to the welding process and prior to it, the applicable
welding pressures P and welding times t have to be looked up in the
tables in the appendix (see Sect. 4.4.1 ff. below).
All pressure values P in the tables in the appendix are for
a straight joint. In angled joints, all values are identical,
excepting forces, to which apply other values, P
Important
depending on the planned angle α according to the following
equation (α = the angle at which the components are bevel-
cut, i. e., half of the angle of the intended joint):
where the following applies for the coefficient:
α = 11.25 deg.
α = 15 deg.
α = 22.5 deg.
α = 45 deg.
Sample calculation:
Material PE 80, d. 90 mm, SDR 11, α = 45 deg. for a 90 deg.
joint, bead build-up
P
P =
=
α
coeff
α
Do not neglect that every welding operation performed for the pro-
duction of tees, crosspieces, and Y branch-offs (refer to Sect. 5.2) is
an angled joint that requires computing as above the pressure values
from the values in the tables in the appendix, depending on the angle.
Before the welding process starts, the drag pressure has to be deter-
mined with care. Move the movable carriage apart, turn the pressure
regulator counter-clockwise as far as it will go, then bring to mover
lever to the close-in position and gradually turn the pressure regula-
tor clockwise. Watch the display and note the pressure that "drags"
the carriage sufficiently to set it in motion. This is the drag pressure
P for this welding.
t
Version January 2020
P + P
5
+ P
t
t t
2 3 4
— coeff = 0.981
α
— coeff = 0.966
α
— coeff = 0.924
α
— coeff = 0.707
α
5.0 bar
P =
45°
0.707
HÜRNER HWT 400–WeldControl User's Manual
t
t t
5 6
, computed
α
P
P =
α
coeff
=
7.0 bar
t
α
25
EN