Laboratory studies of the dynamic state of a rigid sieving surface operating in a vibrational-impact field

Abstract

The article investigates the dynamic behavior of a rigid sieving surface operating within a vibrational-impact field. Granulometric composition is a critical parameter in energy-efficient processes, such as sintering and smelting in metallurgy. Given the increasing costs of energy resources, enhancing the screening process of bulk materials has become a priority. This necessitates the development of advanced machines capable of ensuring effective material preparation for subsequent metallurgical processes. The research highlights limitations of current technologies, including metal sieves with circular or square openings, which offer a low effective screening area (35-40%) and achieve an efficiency of only 55%. Polymer sieves, although advantageous for reducing clogging, fail under high temperatures and suffer from reduced repairability and operational lifespan. The primary objective of the research is to determine the dynamic characteristics of a rigid sieving surface when subjected to vibrational and impact loading. A laboratory-scale vibrational-impact setup was developed, emulating the operational conditions of standard industrial screens. The system consisted of key components, including a manually controlled hopper, vibrating carriage, adjustable sieving frame, and accelerometers for precise measurement. Experiments were conducted across a range of vibration accelerations (18…47 m/s²) at fixed amplitudes, with frequency adjustments ensuring controlled testing conditions. Data from the sieving surface were recorded using high-precision sensors, followed by advanced statistical analysis. Results revealed that the acceleration distribution of the sieving surface deviates from a normal distribution, exhibiting asymmetry. Consequently, the interquartile range was used for outlier detection instead of the standard deviation. Oscillographic analysis of acceleration dynamics highlighted two distinct zones: transient motion and steady-state motion. The study established an empirical power-law relationship between the reduction in transient motion time and increased vibration acceleration. Furthermore, findings demonstrated that higher vibration accelerations increase the average acceleration, velocity, and displacement amplitude of the sieving surface. However, beyond a threshold of 33 m/s², these parameters exhibited a decelerating growth rate, indicating diminishing returns. Additionally, dynamic analysis of motion in the sieving surface revealed that points in the loading and unloading zones move in antiphase, confirming a rotational-oscillatory motion pattern. This motion transforms into a reciprocating linear trajectory as the energy input increases. The empirical results validate earlier theoretical models, with experimental errors averaging 8.5%, proving the reliability of the proposed dynamic model. The research outcomes offer valuable insights into optimizing the design and operation of rigid sieving surfaces for vibrational-impact screening systems. The derived dependencies and dynamic behavior trends can guide the engineering of more efficient screening equipment, improving the energy efficiency of material preparation processes in metallurgical industries