Design And Experiment Of A Self-propelled Total Mixed Rations Mixer

A total mixed ration（TMR）is a nutrient-balanced diet based on the physiological needs of ruminants（cattle,sheep,deer,etc.）at different growth stages.The formula for a TMR is designed by animal nutrition experts and includes roughage chopped to an appropriate length,concentrates,and various additives that are fully mixed in certain proportions.There are two main methods currently utilized for silage storage:in a silage pit and in silage bales.A self-propelled mixing machine for TMR was designed,the self-propelled TMR mixer realized the combined functions of reclaiming and conveying of material in the silage pit,mixing of roughage and concentrate,transporting and discharging of rations,bale cutting,and film removal.Self-propelled TMR mixers like that that considered here have played an important role in speeding up the utilisation of crop straw as feed.This constitutes one component of the implementation of a policy of‘grain to feed’with the aim of alleviating the problems arising when people and livestock compete for grain.In this paper,the specific research contents were as follows:（1）On the basis of the existing vertical feed mixer,the self-propelled TMR mixer with the loader and conveyor was developed,the scheme of this designed self-propelled TMR mixer was put forward,the practicability of the prototype was verified.Silage bales wrapped with a stretchable film have been widely used in the animal husbandry industry to remove the bottleneck when preparing silage straw feed.The current methods to manually remove the stretchable films or the use of machines with a plurality of single functions are time-consuming.Therefore,a bale splitter matched with a self-propelled TMR mixer that provides the functions of bale gripping and cutting,material loading,and film removal was designed to realize integrated feeding in the pasture with high efficiency.（2）To reveal the three-dimensional movement of silage material under the action of the reclaiming cutter roller,LS-DYNA software is used to simulate the process of silage cutting,which is modelled using smoothed particle hydrodynamics（SPH）coupled with the finite element method（FEM）.Under the double action of internal extrusion and shearing by the spiral blade of the reclaiming cutter roller,the deformation and displacement of the silage material are concentrated in the contact area between the silage and the roller.The characteristics of the gas flow field in the conveying chamber had an important influence on the smooth loading,conveying and throwing of silage materials,the feasibility of simulation using the finite volume discretization method of Fluent was verified.（3）The structural parameters of the cutter（edge angle A,the bale cutting angle B,and the number of cutting teeth C）were taken as the three experimental factors.The cutting force was used as the experimental evaluation index,it was found that the optimal parameter combination scheme for each experimental factor level was B₃A₁C₃.That is,within the scope of the bale cutting simulation experiment,an edge angle of 110°,bale cutting angle of 90°,and 10 cutting teeth minimized the cutting force produced by the bale splitter.Using virtual prototype software ADAMS,the dynamic simulation analysis of the movement performance of the splitter mechanism was completed,in the absence of a physical prototype,whether the design scheme of the splitter mechanism met the range of operation and caused body interference can be effectively judged.（4）The mixing device was the volume of the hopper 16 m³,the taper angle 106°,the critical speed range of the auger was preliminarily determined 15 r/min～32 r/min.To study the mixing performance and obtain the optimum parameters of the mixing device,the Hertz–Mindlin model is used for the interaction between material particles and mixing device.A three-factor,five-level method is used to optimise the mixing performance.Material mixing time,fullness coefficient,and auger speed are chosen as experimental factors and mixing uniformity as an evaluation index.Simulations of mixing performance have shown that the auger speed,mixing time,and fullness coefficient have a descending order of influence on the mixing performance and that an auger speed of 22 r/min～26 r/min,a mixing time of 6 min～8min,and a fullness coefficient of 70%～75%give a mixing uniformity greater than 90%.The ANSYS Workbench was used to analyze the first 6 modal frequencies and modes of the auger structure to ensure that resonance can be avoided,through the finite element stress analysis of the auger blade,it was concluded that the stiffness and strength of the auger were sufficient.（5）The overall design was determined and the physical prototype was developed based on the reliability analysis from the simulations.The results of the prototype performance test showed that the mixing uniformity 91.1%,the production efficiency of TMR 29.6 m³/h,the residual rate of unloading 0.7%,and the removal rate of the waste film 98.4%,which met the stipulated requirements and provided a reference for further design of the equipment.