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Precision-controlled process
The KFLOW system from Klingel relies on
the interaction between the servo motor
and two compact cylinders for inserting
the screws into the material to be joined.
The process is continuously monitored by
displacement encoders which check the
strokes of the pneumatic cylinders, their
position and thus the screw-in depth. The
holding stroke fixes the component in place
and positions the screw.The main stroke
transmits the process force to the screw
and the material. While the cylinder ADN is
sufficient for the maximum holding stroke
of 1.4 kN, the higher force of the main
stroke of up to 3 kN requires the cylinder
ADNH, which has a higher flow rate. Both
are controlled using Festo proportional
valves VPPM – VPPM-8 for the main stroke
and VPPM-6 for the holding stroke. Propor
tional valves are ideal for the high level of
flexibility required for the screw-in param
eters. The KFLOW joining tool initially oper
ates at a lower speed and with a lower
force for position detection with displace
ment encoder. Subsequent penetration
requires a higher main force and speed.
Forming the thread needs a lower force
and spin. To tighten the screw with the
correct torque, both parameters are
reduced further.
Flexible regulation of the lifting force
The art of flow drilling lies in achieving the
right combination of force and speed for
every screw. “In automotive manufacturing,
Always to the point:
thanks to the proportional valve VPPM,
the screw-in parameters can be adapted flexibly and precisely.
“Working with a flow
drill is almost like an art
form. Flexibility and pre
cision require a great
deal of experience and
expertise. Festo is there
fore the perfect partner.”
Reinhard Totzauer, Project Manager at Klingel GmbH
if we use our systems to insert 20 flow
drilling screws in parallel, we generally
need to have different force and speed
parameters for each individual screw,” ex
plains Reinhard Totzauer, Project Manager
at Klingel GmbH. “If there is a weld next to
a connection point or the material tem
perature changes during the screwing-in
process, the processing parameters have
to be adapted accordingly.” Different ma
terials also demand different parameters.
High-quality steel requires a lower speed
and high joining force to minimise heat
generation, while aluminium requires high
speeds with a lower joining force. Pre-drill
ing is useful for reducing the number of
influencing variables.