Management in technical systems
Mine hoisting units designed to deliver useful fossil or breed, raising and lowering people, equipment and materials. From reliable uptime and productivity mine hoist depends on the work of the whole mine as a whole, therefore to lifting installations have special requirements for reliability and work safety. Actual lifespan of a lifting installation, like usually coincides with the life of the mining enterprise, however, for maintaining mining competitiveness the company is obliged to constantly improve not only technology and mining technology but also other technological links among which the lifting installation is the most significant.
One way to increase lift efficiency installation is the optimal system setup drive control in order to reduce longitudinal vibrations in ropes, which reduces their wear, as the replacement of ropes in the lifting installation is a time-consuming and expensive operation in which mineral recovery is impossible. Therefore increase operational properties of the lifting installation based on justification and the choice of structures for control systems of electric hoist installations by the criterion of maximum damping of oscillatory processes in elastic elements is an urgent scientific task.
Automation of production processes plays a huge role in modern production. Especially recently, when in the equipment steel automation, the achievements of microprocessor technology will be introduced, the capabilities of this equipment have reached a new technical level.
Increasing the capacity of mining enterprises, intensification of mining work, increasing the depth of the mines determine the growth of energy consumption and increase the unit capacity of mine stationary machines. Is increasing the need for further improvement of their automatic systems management.
To the basic requirements for advanced systems, electric drive, there should be a great need for application adjustable electric drive, which is necessary to increase labor productivity.
As a cargo, as a rule, double-skip lifting installations; single-skid lifting units with counterweight used in mines of small productivity when multi-horizon work or the need for separate issuance of various varieties (brands) of minerals. Cage hoist are applied to mines of small productivity and depth. The largest skip plants have a capacity of more than 1200 t/h (skips with a loading capacity of up to 60 tons, speed of movement up to 25 m/s).
For vertical lifting use single-drum or multi-rope lifting machines with a friction pulley.
As an AC electric drive, depending on power and type of lifting machine are used induction motors with AK and AKN series rotary rotor.
ACN Series Unprotected Electric Motors mounted on two riser, cast, split bearings lubricated slip rings, with two shaft ends: one for connection to the gearbox of the lifting machine with the help of the coupling half, the other is for articulation with a tachogenerator through a V-belt drive. Engine design - open with self-ventilation. The stator winding has six pins for connecting to a 6 or 3 kV network. It is two-layer loopback with isolation of a class A, and rotor - a class B. Temperature control motor stator windings are carried out using a thermal relay, and bearings - thermal alarms.
AKN electric motors are included in the mine hoist kit machines with power from 200 to 1600 kW with a synchronous speed of 250 up to 600 rpm.
The most widespread in the mine ascent was regulation of speed and moment of asynchronous motors with phase rotor change in resistance in the rotor circuit. With metal resistance (metal rheostat) in the rotor circuit, the speed changes stepwise, with a liquid rheostat - steplessly. On the surface hoisting installations are used, in most cases, asynchronous motors with a phase rotor and a metal rheostat in the rotor circuit, on underground - with liquid rheostat.
The purpose of the master's thesis is & ndash; provision of dynamic operating modes of lifting installation due to the development of an automatic control system that will allow you to withstand a given tachogram of the lifting speed at compliance with permissible stresses in the nodes of the lifting machine.
To accomplish this goal, the following tasks research:
Research object: automatic control system for a lifting installation in the conditions of the Komsomolets Donbass mine.
Research subject:Lifting shaft installation.
Over 90% of hoisting machines in operation in coal and mining industry of the CIS countries, are equipped with an electric drive with AC motors, mainly asynchronous electric motors with a phase rotor. This is due to the advantage of this electric drive, namely: low cost of equipment and construction and installation work, ease of maintenance, low cost time for maintenance and failure recovery, ease redundancy, high operational reliability.
As an AC electric drive, depending on power and type of lifting machine are used induction motors with AK and AKN series rotary rotor.
ACN Series Unprotected Electric Motors mounted on two riser, cast, split bearings lubricated slip rings, with two shaft ends: one for connection to the gearbox of the lifting machine with the help of the coupling half, the other is for articulation with a tachogenerator through a V-belt drive. Engine design - open with self-ventilation. The stator winding has six pins for connecting to a 6 or 3 kV network. It is two-layer loopback with isolation of a class A, and rotor - a class B. Temperature control motor stator windings are carried out using a thermal relay, and bearings - thermal alarms.
AKN electric motors are included in the mine hoist kit machines with power from 200 to 1600 kW with a synchronous speed of 250 up to 600 rpm.
Protected AKZ Series Electric Motors designed to drive lifting machines of low power from 55 to 320 kW at a voltage of 220/380, 380, 500 and 3000 V. These motors are more high-speed (600-1000 rpm).
The most widespread in the mine ascent was regulation of speed and moment of asynchronous motors with phase rotor change in resistance in the rotor circuit. With metal resistance (metal rheostat) in the rotor circuit, the speed changes stepwise, with a liquid rheostat - steplessly. On the surface hoisting installations are used, in most cases, asynchronous motors with a phase rotor and a metal rheostat in the rotor circuit, on underground - with liquid rheostat.
For the entire prostate of an AC drive with resistances in the circuit rotor, it has significant disadvantages:
The mine hoist is part of the hoisting equipment and is the main part of the mine lifting installation (Fig. 1). Of all machines used in underground mining in the mining industry, the lifting machine takes the most critical place. Compelled machine shutdown actually stops all mine production, bringing huge losses. This defines high technical requirements. the level of lifting machines and the quality of their manufacture.
The lifting machine (hereinafter referred to as the machine) consists of a main shaft, including the coiling organ, permutation mechanism and indigenous bearings; brake device; couplings; gearbox; electric drive; control equipment, protection and interlocks.
Since the body is winding (drum or traction sheave) plays a dominant role, we give the following definitions hoisting machines according to the type of body winding.
Figure 1 – Mine lifting installation MLI
Single-drum single-end machines - consist of one a cylindrical drum on which one rope is wound with cargo at the end. Such machines are mainly used for sinking of vertical shafts and in inclined workings.
Double-end single-drum machines with a split drum - consist of one cylindrical or bicylindroconic drum. The ends of two unconnected ropes are fixed at opposite flanges, and at the same time one rope is wound on a drum, and the second rolls around at that time, that is, both rise and descent of two vessels. The drum shell near one of the flanges has transverse circular section.In this case, most of the drum is hard connected to the main shaft, and smaller, thanks to the rearrangement mechanism, - can be rotated and rigidly connected to the shaft in any position. These two parts of the drum are called - jammed and permutable parts.
Split drum machines can be effective in serving several work horizons in a vertical mine the trunk. However, in practice, the presence of a permutable part of the drum used, as a rule, only in the process of changing the weight of the ropes and for accurate installation of vessels at the receiving platform of the main served the horizon.
Double-drum double-end machines - consist of two autonomous drums. The ends of two disconnected ropes are fixed at opposite flanges of different drums. In this case, one rope is wound on one drum, and the second at this time is wound off from the second, that is two vessels rise and lower simultaneously, as in the system with one split drum. One of the drums is rigidly connected to the main shaft, and the second, thanks to a special "rearrangement mechanism", can turn and rigidly connect to the shaft in any position. These two Drum and called - jammed and permutable.
Single-rope and multi-rope machines with friction pulleys (traction pulleys) - represent a pulley with one groove under rope or all-welded drum with several annular grooves (by streams) for the same number of ropes. The operation of such machines is based on transfer of traction by friction (clutch) forces on the abutment rope to the pulley rim.