Abstract of thesis of master's degree dissertation

by Panas Alexandr

theme of dissertation:

«Mathematical modeling process of moving coal combine with taken away system of moving»

Leader of work: Kondrakhin Vitaliy, professor of department «Mining machines», d.t.s.

Problem and its connection with scientific and practical tasks

  An important problem at creation and perfection of coal combines for mining out of thin layers is the grounded type selection and parameters of mechanism of moving. Presently perspective are electric mechanisms of moving of two types: 1) taken away, with chain hauling organ, 2) built-in, with a hard hauling organ.
    One of lacks of the existent taken away systems of moving is the use as variator of speed of electromagnetic sliding muffs, possessing small reliability, low coefficient of efficiency and requiring the difficult control system. These failings can be removed due to the use for the taken away systems of moving of the frequency-managed electric drive, that substantially will promote potential possibilities of this type of mechanisms of moving in his competition with built-in mechanisms as it applies to combines for the mining of thin layers.
     Development of the taken away mechanism of moving with the frequency-managed drive puts before designers the row of tasks, related to the choice of rational parameters of mechanism, structure and parameters of the control system and basic data for a solid calculation. The most effective method of decision of these tasks is a mathematical design of workings processes of machines in the set and transient regime with the use of the developed models, adequated to the real system.
    The taken away and built-in mechanisms of moving are accepted the institute of Dongiprouglemash at creation of combines of new generation for the mining of thin declivous layers (accordingly, УКД 200-250 and УКД 300). Experience of exploitation of these combines shows that both types of mechanisms of moving can provide effective work of machines in representative mountain terms, including in lavas long 200-300 meters. In this connection there is a necessity to carry out the kinematics analysis of layout charts of combines for the mining of thin layers and define a rational areas of use of combines with the taken away and built-in systems of moving.

Analysis of researches and publications

  To the questions of design of workings processes and parameters ground of coal combines, equipped with the mechanisms of moving with a chain and hard hauling organ, is devoted plenty of works, by M.G. Bojko, V.G. Gulyaev, K.V. Zhukov, V.P. Kondrakhin[4].
    In the indicated works are resulted the mathematical models of process moving of combine, taking into account resiliently-dissipative properties of hauling organ, dynamic descriptions of drive of moving (hydraulic or electric), features of forming of resistances to moving of coal combine.
    In works, devoted to the taken away systems of moving (SOM) by M.G. Bojko[9], a hauling organ is examined as a weightless resilient filament. Such assumption is acceptable during the work in short lavas, however for lavas long 300-350 meters his legitimacy causes doubting, as mass of chain becomes commensurable with mass of combine.

Raising of task

  The purpose of work is an increase of technical level of coal combines for the mining of thin declivous layers on the basis of choice of rational parameters of the system of moving and ground of rational areas of machines use with taken away and built-in of the frequency-managed electric drive.

     For achieving the put purpose it is necessary to decide the followings basic tasks:
        1) To develop the mathematical model of workings processes of coal combine with the taken away system of moving;
        2) To execute the design of transient and set regime of work of coal combine of type УКД200-250 with SOM;
        3) To ground a structure and parameters of mechanism of moving, requirement to its control system and basic data for a calculation on durability;
        4) To ground a rational application domain of coal combines for the mining of thin layers with the different types of electric mechanisms of moving.

Exposition of material and results

Mathematical model of the taken away system of moving of coal combine.

  To compose of the system of differential equations, describing the moving of mechanical system, we use the second sort Lagrange's equations.
  The system of differential equations, describing dynamic processes in SOM, is done on the basis the second sort Lagrange's equations, can be given:

  For evidentness of design results, we will consider the case of combine moving on idle motion.
For this purpose we will consider the simplest case a system with one degree of freedom.

Picture 2. The simplified calculation chart with one degree of freedom

  The done equations solved by a mathematical package method using the function of Rkadapt, which decides the system of differential equalizations by the Runge – Kutta of fourth range with the automatic choice of step. To solve the system needed only D vector is a vector of right parts of the system of equations.

Picture 3. Change of moving speed of coal combine on idle motion.

Picture 4. Change of tractive force of coal combine on idle motion.

  In dependence on the size of middle speed time of motion and time of stop are changed. At the increasing of middle speed t₁ is increased, and t₂ is diminished. Accordingly at diminishing of middle speed t₁ is diminished, and t₂is increased.

Conclusions and direction of further researches

  The analysis of scientific and technical literature on question of research of moving mechanisms of coal combines, showed, that existent mathematical models are not suitable for correct description of dynamic processes in the elements of the taken away systems of moving with the frequency-managed drive at the work in long lavas.

   In this connection it is actual a task of development of correct mathematical models of workings processes of coal combine with the taken away system of moving on the basis of the frequency-managed drive and use of these models, and also the developed criteria for the ground of structure and parameters of the system of moving of new technical level. A rational area of use of combines with SOM are thin declivous layers (angles of incidence to 9°) with small violations of layer. In this case it is possible effective combine work in lavas long to 300 meters and achieving the indexes of resource, comparable with a resource combines with the built-in system of moving.

   The developed mathematical model of functioning process of coal combine with the taken away system of moving is taken into account all basic factors, determining the intensive operating conditions of combine. The done model is a model basis for CAD – systems of coal combines with taken away system of moving and will be used for optimization of structure and mechanisms parameters of moving and other subsystems of machine.