Rope testing for deep mining applications
Deep Mining, Rope Service Life and Performance Evaluation
The fatigue performance of a rope installed in a deep shaft and its deterioration process will strongly affect the safety and costs.
Special devices are required for the simulation of the different deterioration mechanisms in the Koepe and the drum winder applications.
M.R.E. developed special fatigue platforms and devices to simulate wire ropes performance under the deep shaft conditions: Koepe and drum winders.
The devices and procedures were developed after a deep studying of the Koepe and drum winder shaft mechanics, participating in maintenance procedures, rope inspection procedures and reviewing South African technical literature with regard to mining ropes and the mechanic of deterioration in ultra deep shafts.
M.R.E. supplies fatigue testing services for two main shaft applications: Koepe and drum winders.
This service may provide the following benefits:
Safety: For a specific rope we will learn the type and characteristics of the deterioraiton process: location of broken wires, symptoms for broken wires and magnetic testing calibration.
Economical: Comparing the performance of different ropes under specific Koepe or drum winder. We will to provide the end user the information which is needed to choose the right and most economical and reliable rope.
Maintenance: We will follow and simulate the maintenance procedures (such as back cutting) of the mining in order to learn on its benefits and influence on rope life.
As a first stage before testing, the rope is statically measured in order to characterize its torque and tension behavior. Accordingly, the test parameters and loading cycle will be determined under the specific shaft depth.
Testing under Koepe shaft conditions
The Koepe application is characterised by dynamical rotation deformations which are acting along a specific rope segment.
During cycle, these rotation deformations are associated with tension - tension fatigue.
In order to simulate these specific laoding cycle, M.R.E. developed a Tension - Torsion fatigue machine.
During testing, the rope will be fatigue loaded under the tension range loads combined with rotation: openning and closing.
The level of rotation in both directions will be determined according to the rope torsion properties, self weight of the rope, depth and dynamic loads.
Test machine capabilities are:
Tension fatigue loading: 0-250 [kN] load range
Up to 250 deg/m rotation deformation to both directions.
Length of rope sample: up to 4.5 m', depends on the level of rotation level.
Rotation actuator will induce rotation deformations, closing and openning combined
with controlled axial loads
Loading cycle to simulate the Koepe application, tension tension fatigue
combined with dynamic rotation:
Simulaiton of the dynamic loads
during skip loading
A specific loading device will induce dynamic loading which intend to simulate the dynamic loads during skip loading.
Testing under Drum Winder conditions
The deterioration process in the drum winder is concetrated at the back end at which the rotation deformation is constant: increase in lay length.
The main loading parameters which characterize the rope deterioration in the drum winder are:
Tension - Tension fatigue loading at the back end section
Radial pressure acting on the first and second layer at the back end associated with slipping of the rope at the first and second layer.
Abrasion at the cross over points.
Laboratory simulation of these deterioration is complicated.
Accordinlgy M.R.E. developed a procedure and devices to simulate the tension- tension loading cycle associated with rope slipping and drum pressure simulator.
The test is conducted under specific lay lenght which represents the lay length at the back end under the specific shaft depth and conisders back cutting operations.
These test capabilities will provide information which considers all influenetial fatigue parameters and may be adopted for the comparison between different ropes under the same conditions.
Determination of the discardign critera for ropes under deep shaft condiitons and magnetic testing device calibration
During fatigue testing under drum or Koepe application the damage as broken wires, abrasion may be recorded and mapped by means of magnetic testing.
We can installl used/discarded ropes which may be tested and fatigue loaded in order to follow the post stage deterioration process and evaluating the calibration of the magnetic testing device under progressive damage.
This test for a fatigue rope may provide usefull informaiton on hte discard criteria, residual breaking load, the remaining service life and the rate of deterioration.
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