Mechanical and wear analysis of classifying crusher based on discrete element method
August 20, 2024 Hawk
The relationship between the working speed of the crusher and the hardness of the material directly affects the stress and wear of the tooth roller and wear-resistant lining of the graded crushing equipment. Based on the discrete element simulation software EDEM, the crushing process of the graded crusher was simulated and analyzed for particles of different hardness and the working speed of the tooth roller, and the relationship between the hardness of the particles and the stress and wear of the tooth roller and the wear-resistant lining was obtained, which provides a theoretical basis for the design and actual production of the graded crusher.
Due to the special nature of ore crushing, the grading crusher is in a high-load working state for a long time. Therefore, in the study of the crusher, in addition to the simulation of ore particles and the crushing efficiency of the crushing process, the force analysis and wear problem of the crusher are also very important issues, which is very important for the subsequent repair of the crusher liner. At present, the most efficient metal repair method is to repair it through laser cladding, and the strength after repair can be 5-10 times stronger than the original.
The current analysis and research on the crushing process mainly focuses on the influence of the tooth roller arrangement form, tooth roller speed, and the properties and particle size distribution of the material on the crushing effect. Yang Kangkang et al. used the platform architecture ANSYS/LS-DYNA unit analysis software to perform dynamic analysis of the simulation of the ore vein crushing process and obtained the change of impact stress in the crushing process: at the moment of crushing of the crushing tooth, there is a strong impact force axial stress at the tooth tip, and the deformation increases with the increase of the gear roller speed, but after the crushing tooth penetrates the ore vein, the stress state on the tooth tip immediately decreases and tends to be stable. Wang Baoqiang established a mechanical model of the tooth roller component of the crusher, used a dynamic solution method to solve the impact load of 1,000 kg of coal on the tooth roller component, and obtained the characteristics of the mechanical bearing under the current working conditions. SUN et al. studied the influence of tooth roller spacing, rotation speed and offset angle on the force of the double-tooth roller crusher. SONI et al. established a breakage-agglomeration combined model to characterize the particle behavior of the crushed products of the double-roll crusher, predict the particle size distribution of the crushed products, and the force and wear of the equipment. This model uses a reasonable combination of single models for two different phenomena that occur simultaneously in the double-roll crusher process, namely, crushing and agglomeration.
Taking the grading crushing equipment of Tangshan Tianhe Environmental Protection Technology Co., Ltd. as the analysis object, the crushing process of the grading crusher at different tooth roller speeds was analyzed based on the discrete element simulation software EDEM. The crushing process of the grading crusher was simulated and analyzed for particles of different hardness and the working speed of the tooth roller. The relationship between particle hardness and the force and wear of the tooth roller and wear-resistant liner was obtained, which provides a theoretical basis for the design and actual production of the grading crusher.
1 Establishment of discrete element model
Considering that the working principle of the single-toothed roller crusher is that the material is sandwiched between the toothed roller and the wear-resistant lining, and is crushed by extrusion, bending and shearing, when the three-dimensional modeling software Creo is used to establish the three-dimensional model of the graded crusher, in order to reduce the workload of EDEM during simulation calculation, the bolts and other connection pairs of the graded crusher are ignored, and only the key components such as the toothed roller, wear-resistant lining and baffle are retained. After the modeling is completed, the three-dimensional model is imported into the EDEM software in asm format. The schematic diagram of the graded crusher structure is shown in Figure 1.
Since the crushing process of the graded crusher is the process of breaking large pieces of material into multiple small pieces of material, multiple small particles are bonded into the shape of large particles through bond bonds, and finally the particles are replaced and crushed. Considering the complexity of the particles in the actual crushing process and the maximum feed size of the crusher, multiple large particles with different radii are used for simulation, which are 80 mm, 90 mm, 100 mm, 125 mm and 150 mm respectively. In order to restore the shape of large particles to the greatest extent, after multiple attempts at particle stacking, large particles with radii of 80 mm and 90 mm and small particles with a radius of 10 mm were selected for filling, and the remaining large particles were filled with small particles with a radius of 20 mm. The filling cloud of 100 mm particles is shown in Figure 2.
According to the motor speed and the transmission ratio of the reducer, the gear roller speed is calculated to be 2.2 rad/s, and different gear roller speeds of 1.8 rad/s, 2.0 rad/s, 2.4 rad/s and 2.6 rad/s are set according to this speed to crush the same material, and the influence of the gear roller speed on the crushing effect is analyzed. In the EDEM pre-processing interface, first set the basic parameters of the material and equipment, as shown in Tables 1-3. Then set the contact model, particle factory and particle replacement plug-in, and select the Relative wear contact model in Particle to Geometry (this model qualitatively analyzes the wear of the equipment by calculating the accumulated energy of the particles on the surface of the equipment).
After the pre-processing settings are completed, the time step is set to 1.534 86%, the data saving frequency is set to 0.01 s, and the simulation is started. First, the particles are accumulated. The particles are accumulated at the 3rd second, and the toothed roller starts to rotate at the 3rd second, and the particles of the first batch of particles are replaced at the same time. In order to eliminate the interference of other reasons on the crushing results and make the simulation results closer to the actual crushing production situation, the particles are replaced when the particles contact the toothed roller and the wear-resistant lining at the same time. When the toothed roller speed is 2.2 rad/s, the simulation process is shown in Figure 3.
2 Analysis of simulation results
After the simulation is completed, the curve of the force change of the equipment over time and the cloud map of the equipment wear are output in the post-processing interface. Since the accumulation process in the first 3 seconds does not involve the replacement of particles, all the schematic diagrams output are intercepted after 3 seconds. The simulation screenshots shown in Figures 4 and 5 are all screenshots of working condition 1 and the speed is 2.2 rad/s.
It can be seen from Figures 4 and 5 that the force on the toothed roller and the lining changes intermittently over time.
The force diagrams of the gear roller and liner changing with time at different speeds and hardness are output in the post-processing interface, as shown in Figures 6 and 7. The normal cumulative energy and tangential cumulative energy of the gear roller and liner at different speeds and hardness are shown in Figures 8 to 11, respectively.
3 Conclusions
By simulating the crushing of materials with three hardnesses at different speeds, the following conclusions are drawn: ① For materials with the same hardness, as the speed increases, the force on the tooth roller and liner increases, and the increase is greater when the speed increases to 2.2 rad/s; when the speed is the same, as the hardness of the material increases, the force on the tooth roller and liner increases. ② For materials with the same hardness, as the speed increases, the accumulated energy on the tooth roller and liner increases, and the wear becomes more serious, and the increase is greater when the speed increases to 2.2 rad/s; when the speed is the same, as the hardness of the material increases, the wear on the tooth roller and liner will also become more serious. At the same time, considering the force and wear of the graded crushing equipment, the best comprehensive benefit is when the tooth roller speed is 2.2 rad/s and the hardness of the crushed material is f2.
Taking the above into consideration, and with the cooperation of laser cladding strengthening technology, the life of the vulnerable parts of the crusher is greatly enhanced.