Loads Acting on the Mine Conveyance Attachments and Tail Ropes during the Emergency Braking in the Event of an Overtravel

Abstract

It has now become the common practice among the design engineers that in dimensioning of structural components of conveyances, particularly the load bearing elements, they mostly use methods that do not enable the predictions of their service life, instead they rely on determining the safety factor related to the static loads exclusively.In order to solve the problem, i.e. to derive and verify the key relationships needed to determine the fatigue endurance of structural elements of conveyances expressed in the function of time and taking into account the type of hoisting gear, it is required that the values of all loads acting upon the conveyance should be determined, including those experienced under the emergency conditions, for instance during the braking phase in the event of overtravel.This study relies on the results of dynamic analysis of a hoisting installation during the braking phase when the conveyance approaches the topmost or lowermost levels.For the assumed model of the system, the equations of motion are derived for the hoisting and tail rope elements and for the elastic strings. The section of the hoisting rope between the full conveyance approaching the top station and the Keope pulley is substituted by a spring with the constant elasticity coefficient, equal to that of the rope section at the instant the conveyance begins the underwind travel.Recalling the solution to the wave equation, analytical formulas are provided expressing the displacements of any cross-profiles of hoisting and tail ropes, including the conveyance attachments and tail ropes, in the function of braking forces applied to conveyances in the overtravel path and operational parameters of the hoisting gear. Besides, approximate formulas are provided yielding:-loading of the hoisting rope segment between the conveyance braking in the headgear tower and the Keope pulley -deceleration of the conveyance during the braking phase.The results will be utilised to derive the function governing the conveyance load variations during the emergency braking, depending on the parameters of the hoisting installations and the braking systems. These relationships are required for adequate design of the frictional contact between the ropes and the pulley and will become the basic criteria for dimensioning and design of load-bearing components of conveyances in the context of improving their reliability and safety features.

Emergency Braking of a Mine Hoist in the Context of the Braking System Selection

“…The work by (Wolny, 2016) provides analytical formulas to derive the displacements of any cross-profiles of hoisting and tail ropes during an emergency braking phase, i.e. whilst the braking force is applied to act on the conveyance.…”

“…Recalling (Wolny, 2016), these formulas can be given in a simplified form, following an assumption that:…”

“…Loads acting upon this section of the hoisting rope in the first stage of the emergency braking phase (until the return of the elastic deformation wave) can be obtained from the formula (Wolny, 2016): The extreme value of the expression (4) is found for the time t, given by the formula: …”

“…The solutions are underpinned by theoretical backgrounds and use the hoist model provided in the work by (Wolny, 2016).…”

Health Monitoring for Balancing Tail Ropes of a Hoisting System Using a Convolutional Neural Network

“…It is set up to balance the gravity of the hoisting rope and to obtain equal moments in the mine hoisting system [3]. Hence, the working state and mechanical properties of the tail rope directly affect the safety of mine production [4].…”