Laboratory Evaluations of Hoist Rope Diameter-Monitoring System

摘要

The U.S. Bureau of Mines (USBM) has conducted research to improve thenondestructive testing (NDT) of wire hoist ropes. Losses in the diameter of a wire hoist rope are used as one criterion for judging when a rope should be replaced. This is done by periodically measuring the rope diameter and comparing this measurement with the original measured diameter; when the diameter reaches a specified minimum at any point along its length, the rope must be retired. Generally, these measurements are made at randomly selected locations along the length of the rope using a hand caliper. To provide more accurate measurements and to allow measurements to be taken continuously along the length of a hoist rope, an optical diameter-monitoring system was built by the USBM. Continuous measurements are preferable because when combined with continuous electromagnetic NDT results, they can indicate whether losses in metallic cross-sectional area originate from external wear or internal wear and corrosion. Tests of the system by personnel at the Bureau's Spokane Research Center showed that the instrument met specifications when measuring wire rope at low rope speeds but was inaccurate at speeds over about 30 m/min (100 ft/min). This Report of Investigations describes the prototype system, presents the results of the test program, and describes the capabilities of the system.