Optimization design and experiment of double-helix total mixed rations preparation mixer for silage straw feed

Abstract

Aiming at the problems of uneven mixing and low production efficiency of domestic silage mixer, a double- helix TMR (Total Mixed Rations) preparation mixer for silage straw feed was designed to replace the traditional vertical single-helix mixer. The performance tests and parameter optimization were carried out on this preparation machine. By analyzing the mixing process and mechanism of the diets in the mixing chamber, the key factors affecting the mixing performance and the range were determined. It was found that the greater the stirring speed of the churn, the greater the angle of material lift, the more conducive to improving the material lifting capacity of the churn device. The mixing characteristics of the preparation machine and the movement of material were numerically simulated using EDEM simulation software, and the mixing effect of the preparation machine was verified. The three-factor and five-level CCD center combination orthogonal rotary test in the prototype was carried out with stirring speed of the churn, mixing time and filling coefficient as influencing factors, mixing uniformity, roughage particle size and ton material energy consumption as evaluation indexes. The test results showed that the contribution of each factor to the mixing uniformity in descending order was filling coefficient, stirring speed and mixing time, to the roughage particle size was stirring speed, mixing time and filling coefficient, and to the ton material energy consumption was filling coefficient, mixing time and stirring speed. The optimal working parameters for mixing performance by comprehensive optimization could be concluded as stirring speed of 48.59 r/min, mixing time of 14.98 min, and filling coefficient of 70%. In addition, the mixing uniformity, roughage particle size and ton material energy consumption were obtained as 91.11%, 72.13% and 2.99 kW·h/t. The relative error for all evaluation indexes between the experimental results with round parameter combination and the predicted value was verified to be less than 3%. It can be seen the double-helix TMR preparation mixer can meet the demand for efficient mixing of silage straw feed, which obviously provides data reference and technical support for the design and selection of operating parameters of TMR preparation machines.