Study On Crushing Mechanism And Impact Dynamic Characteristics Of Large-scale Sieving Crusher

With the continuous development of large-scale open-pit coal mines,the semi-continuous mining process has gradually become the mainstream process for most open-pit mine coal production due to its strong adaptability,and large semi-mobile or full-mobile crushing stations are indispensable in this production process.The core equipment is a large-scale sieving crusher with a capacity of more than 1000t/h.The raw coal of the sieving crusher is directly fed,the crushing process of the mixed granular material is complicated,and the factors affecting the crushing granularity are various.Due to the lack of effective research means,the influence law of the crushing mechanism and the crushing effect is unclear,and under the high energy frequent impact of large-scale feeding,The dynamic characteristics and damage mechanism of the toothed roller structure are not clear,which leads to the lack of theoretical basis for the optimium design of the toothed roller.The traditional large-scale sieving crusher relies on the experience design,which affects its efficient operation and reliable operation.The research is carried out in the background of the 10 million-ton open-pit mine crushing system in Shenhua Baori Hiller area.The DEM method is used to simulate the numerical analysis of the crushing process,and the impact dynamics is utilized.The method reveals the dynamic characteristics of large-scale grading crushing equipment,and provides theoretical basis for the design and application of large-scale grading crusher by means of test prototype verification theory and numerical model.The main work and conclusions of the research obtained are as follows:(1)The bearing characteristics of the particels in the crushing process was studised by establishing the crushing tooth-light roll piercing mechanical model for the the medium and large particle,as well as the tooth-back-indeced milling mechanical model for the small particle.Then,the calculation formula of the particle load were obtained and from which it was found that the crushing process is mainly affected by the particle size and position.In order to carry out the design of the similar model of the crushing model machine,the basic mechanical properties of the coal samples from the actual crushing working environment were tested.And from the perspective of particle bearing property,the working parameters and structural parameters of the sieving crushing process are determined.The basic mechanical properties of the simulated working environment were tested on the coal samples ofthe actual crushing test,and the crushing requirements of the test model machine were clarified.(2)The DEM phenomenological model of the sieving crusher was established.The effect of the working parameters of the sieving crusher on the crushing performance was studied by the method of virtual crushing test.The effect of the rotational speed of the two toothed roller at the constant speed,the rotating form of the toothed roller and the rotating speed error on the the unit time and the complete crushing time was analyzed.The optimum tooth roller speed of the crusher was found,and the processing time per unit time when the tooth roll was reversed was about 1.37 times of the forward rotation.(3)The influence of the structural parameters of the crushing roller(such as the high tooth of the toothed roller,the high tooth density of the toothed roller and the arrangement of the toothed disc)on the unit time capacity and crushing energy consumption of the crushing process was studied.The fluctuation characteristics of the output torque of the toothed roller in the staged crushing process were found.The synergistic optimization design of the structural parameters and working parameters of the toothed roll was carried out by the response surface method.The quantitative relationship between the treatment volume and the complete crushing time and various factors and the significance of the influence were obtained.In order,a method for improving the performance of the sieving crusher was proposed.(4)The bearing characteristics of the crushing teeth in the sieving crushing process under impact were studied,and the strength analysis under the four working conditions of the toothed roller structure was carried out.The torsional vibration model of the toothed roller concentration and the lateral vibration model of the toothed roller were established.According to the dynamic response method,the natural frequency and mode shape of the transverse vibration of the crushing roller are similar to those of the finite element analysis.The discrete element method-finite element method coupling method(DEM-FEM)was used to analyze the bearing characteristics of the crushing roller under working conditions.It is found that the maximum deformation of the toothed roller increases with the increase of the length of the feeding position and the height of the feeding.Based on the principle of fracture mechanics,the local flexibility of the crush tooth was derived.It is found that the local stiffness is greatly reduced as the crack depth of the crush tooth increases.(5)According to the parameter configuration based on optimal crushing effect ofvirtual crushing test,the crushing test system of the experimental model of the sieving crusher was designed.The test results of crushing effects such as treatment volume and crushing time,cumulative yield,over-grinding rate influence characteristics,energy consumption characteristics and crushing effects of different coal types were carried out.The test values were close to theoretical values or numerical simulation values,and the average power of the crushing process at 40 Hz and 50 Hz is 3.0 kW and 2.8 kW,respectively.The fluctuation of the output torque of the toothed roller increases with the reduction of the crushing size.At 74 r/min,the crusher has the smallest particle size and pulverization rate.The breaking rules of various coal samples are robust.