Ritmo STARGUN UNO Manual De Uso Y Mantenimiento página 17

5. WELDING CRITERIA
EXTRUDER
WELDING ROD
MINI
EXTRUDER
SHOE
Portable welding extruder is composed by a mini extruder with a plasticizing
unit, operated by an electric MOTOR.
The pre-heating of parts to weld is done with a hot air blower, where the air
is generated independently by the blower.
Welding pressure is given with the no-stick welding shoe directly assembled
on the extruder and corresponding to the outlet of welding rod. According
to the application welding shoe can have different configurations, to
guarantee a correct and homogeneous pressure.
Welding material, supplied in coils, necessary for welding, is positioned in
the special hole to be plasticized in the same extruder. According to
diameter of rod, different quantities of material in Kg will be extruded.
WELDING PRINCIPLES
Surfaces of parts to be welded are heated at welding temperature by hot
air which comes out from special nozzle. Welding material, continuously
coming out from the welder manually operated, is pressed on components
to be welded. Flux of material, pushes forward automatically the apparatus
and determine welding speed. The heating of surfaces to be welded
together must be adapted to welding speed.
MATERIAL REQUIREMENTS
Welding material and material to be welded must be suitable for extrusion
welding.
As far as plastic material, for type and main characteristics of material, a
certificate of the producer should be available, according to DIN 50049.
Welding material and parts to be welded must be in perfect conditions.
Make sure they can be welded according to DVS 2203.
WELDING MATERIALS
Welding material must be chosen according to extruder welder chosen for
the work and kind of material to be welded. Rod used as welding material,
must follow certain characteristics of dimensional precision, of form and
absence of contraction cavities (see Bulletin DVS 2211).
Material of unknown origins should not be welded. Welding of recycled
materials is forbidden.
Welding rod must be dry and clean; also avoid humidity for not risking to
waste the weld.
WELDING GEOMETRY
When choosing welding geometry for containers or other apparatus, refer
to regulations DVS 2205.
In particular general principles of configuration must be taken into
consideration, from a welding technique point of view, as follows.
In the extrusion welding are generally welded joints with only one deposit
of plastic . If in case of very thick materials, "Double V" weld would not be
possible to perform (see following description), it is possible to weld joints
with several welding layers. Welding rod must go about 3 mm beyond joint
to be welded.
Following are the most used and known types of extrusion welds.
TRANSMISSION
HEATING COIL
A "V"weld
Separate joint to be welded
An angle between 45° and 90° must be chosen, according to sheet to be
welded. Width of opening "B" is limited to about 30 mm in case of welds
with only one welding layer, otherwise the operator would not be able to
perform the necessary welding pressure.
To obtain a good heating and welding, it is necessary to prepare, on top part,
a fissure 2 mm wide. If this dimension cannot be respected, it is necessary
to do something, like for example use some more hot air or make another
layer of weld.
B Double "V" weld
Preparation of edges without fissure
Joint to be welded
Welded top part
Preparation of edges with fissure
Top part welded
Down part welded
For instructions on preparation of the edges before welding, see section A.
C "T" joint with corner weld
Joint to be welded
For instructions on preparation of edges before welding, see section A.
Projecting part G is to lay down and drive welding shoe.
D K-weld
Joint to be welded
For instructions on preparation of edges before welding, see section A.
Projecting part G is to lay down and drive welding shoe.
Welded joint
Welded joint G = 10 mm
Schweißnaht
EN 17