Analysis of Impact Characteristics of Hammermill Screen Based on Discrete Element Method and Calibration of Contact Parameters of Crushed Particles

Abstract:

Crushing of raw materials is an important process step in feed processing, and hammermill screen breakage is a common failure. Aiming at problems such as the lack of effective contact parameters of crushed particles and inaccurate numerical simulation in the discrete element simulation of the particle screening process in the screen breakage identification device, maize was used as test material to obtain the impact characteristics of the hammermill screen, and on the basis of the particle size distribution characteristics of crushed maize particles, the characteristic particle diameter of crushed maize particles was selected to make test samples. The collision ramptest and funnel test were combined with discrete element simulation. The polyhedral particle model was used to represent the crushed maize particles. The crushed maize particles contact parameters were calibrated.Results showed that the sum of average impact strength of the upper and lower parts of the screen was great and the impact frequency was high, making it easier to break. The coefficients of restitution between crushed maize particles and between crushed maize particles and carbon steel were 0.14 and 0.44, respectively, simulation verification test indicated that the relative errors were 0.56% and 1.95%. The kinetic friction coefficients between crushed maize particles and between crushed maize particles and carbon steel were 0.77 and 0.85, respectively. The relative errors of the simulation verification test were 3.04% and 3.56%.The research result can provide basic data and theoretical basis for analyzing the impact characteristics of the hammermill screen and optimizing the screen breakage identification device.