This article discusses a vision method of measuring the geometric parameters of ropes and evaluating their wear based on measurements made in a three-dimensional projection of rope surface. The purposes of this method include assessment of the condition of all kinds of ropes working in the mining industry. The proposed method is novel, eliminates the shortcomings of previously used mandatory visual methods, removes their constraints, and is an important complement to magnetic methods. The article discusses the method of construction of a three-dimensional image based on mapping of the actual dimensions of the rope and on algorithms that allow determination of the parameters describing its basic geometrical dimensions and surface condition. The article discusses issues related to resolution of the vision system, resolution of laser beam analysis, and resolution relating to the measurement of the height profile on the surface of the rope. Based on the image constructed in such a way, measurements are presented in order to assess the dimensional parameters and surface defects in sample rope structures. Based on tests and analyses of the three-dimensional image, a range of inspection tasks using 3D vision systems is indicated.
This article discusses a completely new concept for the diagnostics of sheaves in rope hoisting equipment used in deep mining, where excavated material, consumables, and people are transported via shafts. Rope sheaves involve shafting, guide sheaves, and support rollers on which ropes reel in special grooves. Those grooves may be made directly in the material of the sheave rim or in a specially installed plastic liner. Those grooves are made in the appropriate dimensions. Any change to those dimensions is due to a number of phenomena that occur in life cycle processes and significantly affects the condition of ropes. Measurement of the geometrical parameters of rope grooves for diagnostic purposes provides information about the condition of the rope system and guidance on the appropriate corrective actions. This article presents a solution that permits continuous measurement of selected geometrical parameters of the grooves using a non-contact method of scanning sheave rims with a laser beam. The basic geometric parameters of grooves and sheave rims were defined. The system was shown to be useful in the determination of axial and radial run-out of rope sheaves.
In most rope transport devices, the used steel wire ropes are replaced with new ones after working for a certain period of time, or after reaching the acceptable level of wear. The operational safety of the entire system depends on the correct diagnosis of the condition of the working wire rope. This is not easy, because the working lives of the ropes are varied, and their wear depends on many factors, including random ones. This article presents three different aspects of the work of steel ropes in mining-shaft hoists. What they have in common is a stochastic approach to interpreting the level of rope wear. The process of progressive wear due to fatigue breaking of wires is presented as the first example. This process is non-linear with a strong upward trend, which, in the final stage, turns into a phase often referred to as “explosive”. The rate at which subsequent wire breaks appear is influenced by numerous random factors, e.g., in the form of different methods and materials from which a given rope is constructed. However, the character of the progressing wear process is most affected by the random distribution of stresses experienced by individual wires and the randomly variable nature of the working environment. The second aspect presented in this article is an attempt to determine the probability of wire breaks of the rope. This was presented on the example of wear of the hoisting rope of a mining-shaft hoist. The last aspect of a stochastic nature, which is discussed in the article, is the issue of separating individual components of this distribution from the multimodal distribution describing the tensile strength of the rope wires, possibly of a normal character. Modern methods of analysis allow such distributions to be assigned to specific structural elements of the wire rope. This gives information about which structural elements of the rope wear faster or unusually and, consequently, determine its strength. This was presented on the basis of the results of strength tests of the wires of the mining-shaft hoist rope, which broke due to excessive corrosion wear of the inner strands. The presented examples explain only a short part of randomness in the description of working ropes, but the intention of the authors is to draw the attention of the personnel responsible for their safe operation to unavoidable random factors.
3 November 2021 in Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology
Steel ropes are widely used in material handling machines. The excessive wear of wires is often presented as a type of rope degradation. One of many indicators of the wear is abrasion, corrosion and fatigue cracks. Within this class of rope degradation, the main representation of wear is wire abrasion in the layers of the external wires. This is especially noticeable at the steel ropes which are operating in the drum devices with multilayer winding and in hoists of mining shafts. Over performed work cycles, the estimation of losses in rope cross-section is important for the calculation of the rope capacity. Abrasive wear of external wires is a relatively easy phenomenon to detect with a qualitative interpretation. However, it is a very difficult phenomenon to quantify. The aim of this article is to address this issue. A brief survey of usual methods for rope inspections is given, which can serve as practical guidance for the engineers in this field. With accompanying case study, it presented the advantages of magnetic method in rope inspections oriented towards measuring the changes of wires within the wear assessment.
As the reserves of these raw materials continue to dwindle, their extraction is becoming increasingly difficult, with shaft depth increasing and sometimes exceeding three kilometres. As shaft depths increase, the costs, as well as the risks of mining and other shaft operations, increase non-linearly. There is also a significant increase in the costs associated with condition assessment, which depend on the inspection and testing method used and increase with the lifetime of the facility. New technical and organisational solutions are emerging to meet these requirements. This paper addresses the operation of steel ropes. This article analyses the results of strength tests on two selected modern hoisting rope designs that have recently come into service. These structures are relatively unknown to users in terms of their wear. In their operation, significant problems of condition assessment and safety, as well as disqualification due to the level of wear reached, arise. Strength tests were performed using classic non-destructive methods (tensile test, torsion test, bending test) to assess the technical condition of ropes after their replacement. The tests on two rope structures carried out before and after they were put down by expert decision were analyzed. The results of these tests were statistically processed and presented graphically to determine similarities and differences. Statistical analyses were used to evaluate the results by examining the distribution of variable strength parameters. All results were commented on, and specific and general conclusions were drawn. The article presents the conclusions, the most important of which is that new and complex ropes exhibit varying degrees of wear across the layers. This is due to their compaction process. These should be useful to users of similar rope designs, personnel carrying out the obligatory tests imposed by the legislation, and those making strategic decisions regarding the operation of entire mining plants. The analyses may contribute to the subsequent assessment of the technical condition of new ropes, which in many cases have wear parameters (corrosion, strength loss, etc.) assessed in a subjective, not quantitative, manner.
1 October 2019 in New Trends in Production Engineering
Basic opencast mining machines belong to the group of devices used to perform specific technological operations through mining, loading, transport up to the dumping of mining heaps. Machines work in EBD systems (Excavator-Belt-Dumping) and require high reliability. Multi-bucket excavators that require the use of rope systems in order to maintain stability and the possibility of mining at different levels. The paper focuses on issues related to rope work in multi-buckets excavators. On the basis of studies to assess the technical condition of the ropes identifies the causes of damage to ropes these machines. As a result of the research, final conclusions were formulated.