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

The traditional vertical single-helix mixer for silage straw feed was replaced with a double-helix total mixed ration preparation mixer, which aims to address the issues of uneven mixing and low production efficiency of domestic silage mixers. This preparation machine was used for the performance tests and parameter optimization. The main elements influencing the range and mixing performance were identified by dissecting the diets’ mechanism and mixing process inside the mixing chamber. The more the churn’s stirring speed and material lift angle, the more favorable it was discovered that the churn device was for increasing its capacity to lift materials. Using a simulation software, the preparation machine’s mixing properties and material movement were numerically simulated, and the preparation machine’s mixing effect was confirmed. The prototype’s threefactor and five-level central composite design center combination orthogonal rotary test was conducted using the following evaluation metrics: ton material energy consumption, roughage particle size, mixing uniformity, and filling coefficient as evaluation indices; stirring speed of the churn, mixing time, and filling coefficient as influencing factors. The test results demonstrated that the filling coefficient, stirring speed, and mixing time contributed descending order to mixing uniformity; the stirring speed, mixing time, and filling coefficient contributed descending order to roughage particle size; and the filling coefficient, mixing time, and stirring speed contributed descending order to the ton material energy consumption. 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%. As can be observed, the double-helix TMR preparation mixer can effectively meet the demand for silage straw feed mixing. This, in turn, offers technical support and data references for the design and selection of TMR preparation machine operating parameters.