Designing high quality steel wire ropes: Design data collected from test results and field experience
During the presentation at the OIPEEC Conference 2003 (Voigt, 2003) it was described why design and manufacturing details lead to large differences in fatigue life results of up to 1 : 30 (if not excluding the 10 % rule the difference would be much larger still). This paper shows which design and calculating criteria are used to optimise the rope geometry to achieve better bending fatigue results and longer service life. Thyssen first developed their computer program for the design of wire ropes in 1976 (Diefenbach and Voigt, 1983). With this program it was possible to design a rope within seconds. Since then, big improvements have been achieved in rope quality. Today standard calculation programs are available and whilst the calculation is made by the computer, the result is only as good as the input (Voigt, no date). The input values are the important part: wire clearance (qW) Strand clearance qS, strand lay length and angle, rope lay length and angle, the relation core - rope lay length and core diameter to strand diameter influence of clearances, fibre core diameter and density factor (elevator ropes), crossing angles of wires etc. These values influence the service life of the rope (examples of values will be presented). The differences in using percentage clearance (design factor method) against an optimum clearance related to rope diameter are explained. It is known that not only the rope quality is responsible for a satisfactory service life but also the dimensioning of the rope drive (equipment), the maintenance of the equipment, operation, handling and environmental influences. Consistency and Repeatability of the rope: it starts with rope design.
Author: P.-G. Voigt