WP4 Drilling Equipment & Roof Supports

Mechanical aids will be researched and developed for providing access to cut-off areas of the mine so that the unmanned exploratory vehicles developed in WP3 can be deployed and, potentially trapped miners can be rescued. These mechanical aids, which are small, portable low-power versions of equipment used in coal production, take the form of drilling equipment utilising a novel electromagnetic torsional generator, and roof supports constructed from lightweight composite materials.

The work is divided into the following tasks:

T4.1 – Drilling Rig: Field Calculations

Although, strictly speaking, this will have an impact not only on the work in T4.1, but also in T4.2, T4.3 and T4.4, a definition of the requirements will be produced as a first priority in this task to provide guidance for the design work in all four of these tasks. Questions to be asked will concern the necessary length and diameter of the tunnels that the rig will be capable of drilling and the material though which drilling will take place (solid rock or rubble).

In the first part of the design work on the electromagnetic torsional vibration generator drilling rig, the geometrical dimensions of the hollow shaft torsion torque generator and the hollow shaft main driving motor will be determined on the basis of electromagnetic field calculations. This involves several actions as detailed below.

Electromagnetic field calculations will be performed for the torsional torque generator, which uses permanent magnets for the generation of torsion torques and the driving torque of the main motor. This will allow the following parameters to be determined: number of winding poles, number of stator and rotor slots, as well as the winding parameters of winding pitch and numbers of coil turns. Checks will also be carried out checks into the distribution of the magnetic field and the validity of the geometry in terms of the height of the stator and rotor yokes, and the width of the air gap.

A verification will be carried out of the calculated speed-frequency characteristics of the generated torsional torques and the torque generated by the hollow shaft driving motor. Heat calculations will be performed for different variants of the torsion torque generator and main driving motor and will investigate methods of stator and rotor cooling.

Strength calculations will be made for all variants of the torsion torque generator and motor. The bearing system will then be designed. Corrections to the geometry will be performed to obtain the desired parameters of speed-frequency characteristics, torsion torques and the desired torque of the main motor.

T4.2 – Drilling Rig: Internal Conveyor and Cutting/Loading Head Design

In this task, the drilling rig’s internal conveyor system and cutting/loading head will be designed. This involves the following steps.

First, the geometric dimensions, active cross-section, pitch of the worm ribs, and the height of the ribs and required rotational speed on the basis of assumed volume of mined material will be determined. Also, a geometric model (worm to inside) will be produced.

The circuit mathematical model of the transportation system will be created, including the vibrational support of material transportation, and will then carry out optimization of the geometric dimensions of the transportation system design.

An analysis will be conducted of the suggested concepts of cutting/loading head and selection of the concept for further research work. This will be followed up with a determination of the cutting head geometry and operational parameters.

T4.3 – Drilling Rig: Induction Torque Converter Design

In this task, a detailed design of the drilling rig torque converter will be developed. This involves the following specific activities.

The dimensions of the torque converter and its operational parameters such as power, gear ratio, torque, and input/output speed will be determined. This will allow the preparation of a geometric model of the torque converter and a determination of the type, number and geometry of the magnets and coils.

Next, a circuit-field model of the electro-magnetic circuit of the torque converter will be formulated. This will allow-field calculations to be calculated, and the operational characteristics of the torque converter, and optimise the geometry to be determined.

Next, the following activities will be carried out. The cooling system for the torque converter will be designed. Analysis of the temperature distribution will be carried out. A model of the cooling system will be created. Air flow and heat transfer will be modelled and analysed. A cooling system, comprising a fan, ribbing and cooling channels, will be designed. A geometric model of torque converter integrated with the cooling system will be developed.

Finally, the following will be performed. Finite Element Method (FEM) strength analysis of the torque converter, cooling fan and bearings design will be performed. Vibrations will be analysed. Detailed technical documentation of the torque converter will be prepared.

T4.4 – Drilling Rig: Power Supply and Control System Design

In this task, the design of the drilling rig’s electric power supply and control system will be developed. This involves the following steps.

A mathematical model will be developed for the power supply and control system for different variants of the torsion torque generator and main motor. This will be implemented as a MatLab program.

Then, the following will be carried out. The mathematical models of variants for controlling the torsion torque generator and driving motor will be integrated and used for (1) developing a master algorithm for the mining system control, (2) development of the control system in the LabView program environment. Guidelines for microprocessor implementation of the control and power supply system will be prepared.

The design of the individual components of the new drilling machine, using novel technologies, is the result of the work in T4.1 – T4.4 and will act as a proof-of-concept, albeit with detailed designs of the major components being finalised and documented. Further documentation will provide guidance on the utilisation of the components as part of a complete assembly.

T4.5 –Composite Material Prop: Development

The aim of this task is to design a prop using composite materials to provide high performance with a lightweight construction. This prop will be an essential rescue aid, and will be used, for example, in conjunction with the drilling rig that will be designed in T4.1 – T4.4. Consideration will also be given to its operational use.

First, the end user requirements and the technical and regulatory constrains will be analysed. The information on user needs which will be gathered comprises: the fields of application of different types of steel props in underground mining with the special consideration of rescue operations, advantages and disadvantages of props, possible improvements and foreseen directions of new developments. For that purpose it is planned to conduct a survey among the mining engineers and rescue teams. Particular attention will be paid to the requirements of the drilling rig and on aspects associated with the use of the props during non-emergency situations in working mines so that these props can serve a multi-functional role. In parallel, the legal regulations for new composite props will be investigated. Also the possibility of using different types of composite materials (GFK, CFK, composite sandwiches and others) will be analysed.

Next, the composite prop concept will be developed and numerical modelling and prototyping will be carried out. The information gathered previously will allow the development of the concept of a new composite material prop for use in underground galleries. It is planned to analyze different technical solutions based on existing types of steel props (e.g. SV, Valent type prop). Then numerical models will be developed and tested utilising the Finite Element Method (FEM) which allows for relatively fast and cheap simulation of different technical solutions and operational conditions including: prop construction, type of composite used, behaviour in given thermal conditions, variation of prop loading and yielding characteristics. Furthermore, in the course of this modelling so called hotspots will be identified. The outcomes of this numerical work will allow both the composite material type and technical construction of the prop to be selected. Finally, design documentation will be produced.

T4.6 – Composite Material Prop: Laboratory Tests and Certification

This task follows on from T4.5 with the aim of building a set of prototypes of the composite material props and testing them under laboratory conditions to quantify their performance.

The first job is to manufacture a set of physical prototypes from the detailed design produced in T4.5.

Then, the physical prototypes of the props will be subjected to a rigorous programme of testing under laboratory conditions and in surface facilities, in preparation for final underground testing in T6.4. The aims of the laboratory tests will be to determine important parameters such as the prop load-yield characteristic and the maximum bearing capacity, and to identify possible failure modes with a view to fine tuning if necessary. This contrasts with the field testing in T6.4 which will rely on real-world conditions that do not necessarily correspond to those in the laboratory environment and which will have much more of an emphasis on ergonomics and usability.

Finally, work will be done to fulfil the legal requirements and acquire the necessary certification for the use of the new prop in underground workings