EVALUATION OF QUALITY OF STEEL WIRE ROPES FROM POINT OF VIEW MECHANICAL PROPERTIES OF WIRE
Abstract
Steel wire ropes, after having been produced, are tested. By the tests the strength and number of bending and torsion’s of individual wires are being determined. In standards there are stated minimum values of these mechanical parameters. By using a program created at our working place, from protocols on tests of wires, we have calculated some mathematical-statistical parameters, first of all average values of the strength, bending and torsion’s and on the basis of this we have determined also deviations from nominal strength of wires or minimum number of bending and torsion’s required by standards.
On the basis of randomly chosen 5 protocols on tests of ropes of various producers, above mentioned deviations have been evaluated. Acquired results show that producers use, for the production of steel ropes, relatively heterogeneous wires from the point of view of the diameter of wires used in case of strength, as well as wires of the same diameter with a large scatter of bending and torsion’s. Different are also strengths of wires in individual strands of the rope. Results are shown both in tables and graphically.
Using mathematical-statistical methods for evaluating the quality of a steel rope shows to be as a very suitable. Comparing achieved values results to the knowledge that individual producers in most cases do not pay attention to the selection of wires with the same parameters of mechanical properties or at least with their minimum scatter. The standard of well-known producers - the scatter in limits of ± 10 % - the producers evaluated have reached only with a few steel wires.
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