| The major braking mode of mine includes service braking and safety braking. The service braking means that the winder disc can achieve brake when the raiser reaches the parking position or the hoist is checked under normal working condition. But the safety braking means that the winder disc can achieve brake to prevent accidents further expand when the hoist goes wrong. So the safety braking is the fundamental guarantee of safe, reliable and efficient operation for hoist.The common safety braking includes one-period braking, two-period braking and constant decelerating braking. The braking operation distance of one-period braking and two-period braking are determined under the condition of the full load. The determined value will not change. According to the features of a little change of loading of hoist, one-period braking and two-period braking can basically meet the requirements. By contrast, according to the features of a bigger extent of loading of hoist, one-period braking and two-period braking can not meet the requirements, which creates to large deceleration. Mine hoist constant deceleration braking system will not influenced by hoist load. It can take smooth braking deceleration at a given predetermined range to avoid steel wire ropes sliding. Currently, the best safety is the constant deceleration system in the case of mine emergency.At present, the many domestic mine hoist system with constant deceleration is manufactured by the SIEMAG of Germany and the ABB in Sweden. The price of the hydraulic station with constant deceleration brake is higher than the price of the main lift system and it brings great risk to enterprise because of the higher transportation costs and maintenance costs. Although many domestic enterprises are able to produce the hoist, Very few companies are able to produce constant deceleration braking system. There are wide gaps between China and other countries in the advanced technology and braking of the constant deceleration. Many domestic researchers have done research to shorten the gap. The working principles and hardware of the constant deceleration system of the SIEMAG of Germany and the ABB in Sweden are analyzed. The ABB company meets requirements of the variety brake way through the valve cooperate with each other and the SIEMAG company ensures the system reliable through increasing the loop Target against the exiting constant deceleration braking system, the structure and parameters of the fuzzy controller is designed and the braking process is emulated. Proportional valve and servo valve are compared. Servo valve has more excellent characteristics than the proportional valve.From these discussions, it is known that the contents optimize the algorithms first. Second the constant deceleration system, which used in coal mine, includes analogue control way. Finally, the constant deceleration hydraulic station includes one brake circuit.To resolve the problems mentioned above, the analog control mode for mine hoist constant deceleration braking system and two-period braking way which replaces constant deceleration brake creates to some problems which has the poor stationary and low lifting speed and restricts the production efficiency. A fully digital control method with software and hardware redundant and a full-time constant deceleration control strategy are presented in this paper. To achieve this control strategy this article sets one operation one or more standby program on the basis of analyzing hydraulic braking principle. In electrical control, two set of PLC300are chosen to realize software and hardware redundancy and two set of PLC1200are adopted to control electro-hydraulic serve proportional valve respectively. The hydraulic and electrical simulation models are established with the simulationX in the process of research. By combined simulation the structure and parameters of controllers are determined. A prototype is manufactured and tested on site. Test results show:One novel implementation has high tracking accuracy and high security. |
PDF Full Text Request