Example 11: Tested! Completely turned
But industrial applications and their necessary motion sequences become increasingly complex, so that special cables are more and more required for torsional movements. The service life of the most differing constructions are yet harder to calculate for torsion applications, as no fixed sizes such as radii, travels or the like, are defined. Shielded cables however are very difficult in torsion applications. Braided shields are generally braided in the opposite direction. Whether a cable maintains the torsional demands is very strongly dependent on the application and type of installation.
Unshielded cables, particularly all bundle-stranded chainflex® types, could be successfully used in many torsion applications.
In torsional movements the shield litz wires are therefore drawn in one winding direction, and the other turned in the other winding direction. The woven arrangement and the entailing constriction of each winding direction lead to a quick breakage of the shield from the resulting expansion of the shield litz wires.
Test rig:
The new cable CF ROBOT was tested at the igus® laboratory on a specially developed rig for torsion test. The torsion angle thereby amounts to ± 270° for a total cable length of about 2.5 m (tested in different versions of the triflex® R). Fitted for the test were:
The initial test sample of the CF310 with braided shield and the CF ROBOT were taken after 250,000 movements with a torsion angle of ± 270°.
