robolink
®
Joint kit – Documentation (#4; 2016-12)
igus
®
GmbH | Martin Raak | Tel. +49 (0)2203 9649 409 | mraak@igus.de 15
Draw wires
The construction kit components are generally driven by draw wires. Standard wires are
made from Dyneema
®
, 12-strand braiding, d=2mm, approx. 1.8 g/m, breaking strength >
3.500 N, operating elongation approx. 1%. A special coating ensures the best possible
service life and low friction.
The wires are installed and held in the joints and the drive (see Fig. 30) by means of wire
end nipples (wire end plate assembly instructions at the end of this chapter).
Fig. 30: Wire (2) with nipple (1) Fig.31 : assembled drive wire in a
tensionable drive wheel
The wire tension in an assembled robolink
®
system should be 5-10 N at idle. The joint has
(generally undesirable) play when the wire tension is inadequate. When the wire tension
is too high, the wire friction in the system and the service life of the wires are negatively
impacted. The tensionable drive wheels from igus
®
(see Fig. 25) are ideally suited for
adjusting the pretension in the draw wires. These come in two parts and can be easily
adjusted to the correct pretension by hand or with an igus
®
tensioning tool (instructions at
the end of this chapter). Readjusting the antagonistic draw wires is generally only needed
during initial operation (2-3 times) or after extended down-time.
The wire guidance for rotating motions is accomplished with Bowden cable segments
from igus
®
GmbH. For this application, the Bowden cables fulfill the following
requirements:
• high compressive strength up to max. 1,500 N wire tension force;
• continuous motion possible, because the segments are made from RN54 material;
• low bending radii, optionally as small as 30mm.
Fig. 32: igus
®
Bowden
cable
Fig. 33: Bowden cable segments / schematic
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