Optimization Design of the Lower Rocker Arm of a Vertical Roller Mill Based on ANSYS Workbench

The lower rocker arm is an important part of the vertical roller mill and its lightweight design is of great significance for reducing the mass and production cost of the roller mill. Firstly, the strength and deformation distribution of the lower rocker arm under working load were analyzed by ANSYS Workbench to determine the maximum stress and maximum deformation. The parts with large strength margin were used as the basis for the optimal design. During the analysis, firstly, the arm body of the lower rocker arm was determined part of the lightweight design. Secondly, the mass of the lower rocker arm was taken as the optimization target, the stress and displacement generated by the load of the lower rocker arm were taken as the constraint conditions, the structural size of the internal cavity of the lower rocker arm was taken as the optimization design parameter, and the mathematical model of the optimization design was established. Finally, the structural size of the internal cavity of the lower rocker arm was optimized by using the response surface optimization module and multi-objective genetic algorithm in ANSYS Workbench. The optimum results show that, compared with the original design model, the lower rocker mass was reduced by 346.3 kg and the decrease was about 5.29%, while the strength and deformation were nearly unchanged. Therefore, by optimizing the design, the material is saved and the cost is reduced, which can provide a reference basis for the design and light weight of the lower rocker arm.

Particle Size Effects on Selectivity in Confined Bed Comminution

Confined bed comminution in high-pressure grinding rollers (HPGRs) and vertical roller mills (VRMs) was previously used preferably for grinding comparably homogeneous materials such as coal or clinker. Meanwhile, it started to complement or even replace tumbling mills in ore beneficiation with ore and gangue particles of rather different breakage behaviors. The selectivity in the comminution of a mixture of particles with different strengths but similar particle size distribution (PSD) of the constituents in a particle bed was investigated earlier. The strength of a material is, however, also a function of particle size. Finer particles tend to be more competent than coarser ones of the same material. In industrial ore processing using confined bed comminution, this effect cannot be neglected but even be exploited to increase efficiency. This paper presents research results on this topic based on experimental investigations with model materials and with natural particles, which were stressed in a piston–die press. It appeared that the comminution result substantially depends on the material characteristics, the composition of the mixture and the PSD of the constituents. Conclusions will be drawn for the future applications of selective comminution in mineral processing.

Capacity of roller mill for cement grinding

Engineering for the cement industry is part of the heavy industry. The cement industry is the main supplier of raw materials for the production of concrete and reinforced concrete. For grinding cement, two types of mills are used - ball and roller. Recent decades have proven the great effectiveness of a vertical roller mill for grinding raw materials. Its effectiveness, combined with the implementation of drying, grinding and separation in one unit, gives it an undeniable advantage over a ball mill. This explains the significant increase in the share of roller mills in the cement mill market. The grinding process in such mills occurs due to abrasion, respectively, in the process of work wear of the rubbing parts of the mill occurs. The work evaluated the performance of a mill with smooth disk rolls. During the study, the cause of the destruction of the sectors of the mill produced by FLSmidth, operating in the Russian Federation, was identified. The study revealed the causes of the destruction of the details of the roller mill: with the simultaneous impact of the workload and the displacement of the sectors resulting from intensive wear, the total equivalent stresses exceed the value of the endurance limit under cyclic loading. Therefore, the accumulation of fatigue damage to the material, the formation and growth of cracks, which adversely affects the performance of the mill. A number of measures have been proposed to increase the operability of mills of this design.

Effects of Blade Parameters on the Flow Field and Classification Performance of the Vertical Roller Mill via Numerical Investigations

The vertical roller mill is an important crushing and grading screening device widely used in many industries. Its classification efficiency and the pressure difference determine the entire producing capacity and power consumption, respectively, which makes them the two key indicators describing the mill performance. Based on the DPM (Discrete Phase Model) and continuous phase coupling model, the flow field characteristics in the vertical roller mill including the velocity and pressure fields and the discrete phase distributions had been analyzed. The influence of blade parameters like the shape, number, and rotating speed on the flow field and classification performance had also been comprehensively explored. The numerical simulations showed that there are vortices in many zones in the mill and the blades are of great significance to the mill performance. The blade IV not only results in high classification efficiency but also reduces effectively the pressure difference in the separator and also the whole machine. The conclusions of the flow field analysis and the blade effects on the classification efficiency and the pressure difference could guide designing and optimizing the equipment structure and the milling process, which is of great importance to obtain better overall performance of the vertical roller mill.