Performance Research On New Working Mechanism Of Heavy Electric Mining Shovel

Electric shovel (also called cable shovel) is one of the most important largeequipments in open-pit mining (such as open-pit iron, coal, copper and oil-sand). It ismainly used to strip the covering of the mineral and to load the blasted ores. Theelectric shovels in our country have been mainly from abroad for a long time. So it ismeaningful to design our own electric shovel with intellectual property rights. Thiswork analyses the development of electric shovel and its excavating mechanism, andproposes a new type of parallel excavating mechanism. This paper focus on the basictheory and methodology of the design of new excavating mechanism, which include thenew mechanism type design, the soil-tool interaction modeling, mechanics performanceanalysis of the excavating mechanism in working process, driving motor and powermatching model, excavating capability and digging trajectory optimization model. Thisdissertation's main work can be concluded as:(1)Soil-tool interaction model which is the fundamental basis for the design ofexcavating mechanism. A new soil-tool interaction model is proposed with theconsideration of digging depth, excavating angle, excavating velocity, geometries of thedipper, the physical characteristics of the soil being excavated and so on. Also theoperational factor is taken into account and the model to calculate the resistance due tothe squeeze of blade front with the soil. The new model indicates a closer result withthe field test data.(2) Based on the theory that3-DOF mechanism can digging the soil with optimalexcavating angle so to reduce the resistance. A new3-DOF parallel excavatingmechanism for electric shovel is devised. Compared with the traditional2-DOFexcavating mechanism of electric shovel, the new mechanism is capable to rotate thedipper, which makes it possible that the digging process is performed with optimalexcavating angle to reduce the digging resistance and also increase the dipper filldegree. Meanwhile the new mechanism can perform the work of cleaning up on theroad.(3) The model of energy and power matching of new3-DOF excavating mechanism and the dynamic environment. With the dynamic model, the method can beapplied for the selection of motor parameters when the loads of the driving system arecombination of variable torque load and variable inertia load. Also the method for theoptimal transmission ratio is proposed.(4)The output capacity space of excavating mechanism. Two methods to calculateoutput capacity polytope space are proposed and is applied in the calculation of diggingcapacity of the new excavating mechanism. Another method for the motor powermatching is proposed with output force capacity polytope method when the requiredoutput force is a region rather than a point.As mentioned above, this work gets achievements in these aspects: A new type of3-DOF parallel excavating mechanism is obtained which could perform the diggingprocess with optimal digging angle to reduce the resistance and improve the fill-up rate;Considering the soil properties, geometry of the dipper and the digging manners, a newsoil-tool interaction model is proposed with more accuracy performance, whichprovides the fundamentals for the design of excavating mechanism; Considering themulti-DOF mechanism with variable torque load and variable inertia load, a model forthe energy and power matching of the excavating mechanism is proposed, whichprovide a new methods for the power selection of excavating mechanism. To sum up,his work provides theoretic base for the analysis and design of new excavatingmechanism of electric shovel and other similar mechanisms.