Study On Key Technology Of Shearer With Variable Speed Cutting

The shearer is the main equipment for mechanization coal mining with high production and efficiency, it is widely used for coal mining under different geological conditions. At present, existing principal problems are low rate of lump coal and more coal dust. Therefore, this dissertation conducts a study on the key technology of shearer with variable speed cutting.Based on the analysis of physical mechanical property of coal and cutting mechanism of drum pick, the expressions of relation between installation angles are calculated. The mathematical model of optimizing installing angleβis established. Analyzing the arrangement and cutting pattern of picks in vane and plate, the optimal arrangement of picks in plate is put forward for high lump coal rate.In order to increase lump coal rate, studying the influence of cutting parameters on cutting pattern area A and squareness rateξ, the optimization mathematical model is established taking the maximum of cutting pattern area as objective function. Using Genetic Algorithm of direct comparison-proportion method, the optimization calculation is carried out and the corresponding optimal values of structure and cutting parameters are obtained under the different pick arrangements,and the optimal arrangement of picks in vane is also obtained for high lump coal rate.The structure optimization of shearer drum is conducted under a certain coal property for high lump coal rate. In order to meet the needs for different coal seam properties, the optimization of variable cutting and traction speed is studied. At the same time, the method of recognizing cutting impedance roughly with measured cutting load of shearer is put forward, and adjusting cutting parameters according to this.Aim at the adverse working status and environment condition in mining face underground, the dissertation selects micro-controller S3C44B0X, high speed A/D transformer 40kSPS and Compact Flash (CF) card to constitute an embedded system for measuring cutting load of shearer, and completes the hardware design, software design, anti-detonation design and inherence safety design. The developed system is used in coal mine underground to measure the load spectrum for shearer, the results indicate the system is feasible and practical.The Switched Reluctance Motor (SRM), with the advantages of simple and strong structure, rotor maintenance-free and large torque in low speed, is selected as the power source for variable speed cutting of shearer. The magnetic circuit characteristic of SRM is analyzed by use of the finite element method, providing the theoretical basis for optimization design of SRM structure. The dissertation gives modeling methods of the flux linkage model which can correctly reflect the nonlinear electrical-magnetic characteristics of SRM, and conducts the comparison analysis between optimal and measured flux linkage curves, laying a foundation for selection of SRM modeling methods.In order to increase running reliability of Switched Reluctance Motor Drive (SRD) system, the position sensorless control strategy is proposed and the correlative hardware and software of SRD system are completed. By use of the exciting voltage pulse method to select the start-up phase of SRM, the motor start with non-reversal is solved in practical production field. The experimental platform of 18.5kW SRM is set up. The experimental results verify the correctness of position sensorless control strategy proposed, and the feasibility and reliability of the position sensorless SRD system for shearer are also proved...