颗粒饲料不同加工工段流变特性的研究

Study on rheological properties of different processing sections of pellet feed

试验旨在研究颗粒饲料加工过程中不同加工工段的物料流变特性。试验以4种不同配方颗粒饲料为研究对象,分别测定物料在混合、调质、制粒的休止角、压缩系数、回弹系数和抗剪切强度等流变指标。结果表明,制粒后的休止角显著小于混合、调质工段(P<0.05);混合后的压缩系数显著小于调质、制粒工段,不同配方调质、制粒的压缩系数间差异不同,但压缩系数整体趋势是混合<调质<制粒;混合后的回弹系数显著小于调质、制粒工段(P<0.05);从整个工艺阶段来看,回弹系数整体呈增大趋势;制粒后物料的内摩擦角显著(P<0.05)低于混合、调质工段,制粒后物料的黏聚力显著大于混合、调质工段(P<0.05)。结果提示,饲料经过混合、调质、制粒后休止角呈降低趋势,有利于改善物料堆积型、流动性,饲料经过混合、调质、制粒后压缩系数升高,说明制粒后物料成型率差,饲料在3个加工工段中制粒的物料内摩擦角最小,黏聚力最大,说明制粒过程需要对物料施加更大的剪应力。

The experiment studied the rheological properties in different processing sections of pellet feed.Four kinds of pellet feed with different formula were used as the research object,the rheological indexes such as rest angle,compression coefficient,springback coefficient and shear strength were measured.The results showed that the rest angle after pelleting was significantly smaller than those of mixing and tempering section(P<0.05),and the compression coefficient after mixing was significantly smaller than those of tempering and pelleting section,the internal friction angle of the material after pelleting was significantly(P<0.05)lower than those of the mixing and tempering section,and the cohesion of the material after pelleting was significantly larger than those of the mixing and tempering section(P<0.05).The results showed that the rest angle of feed was reduced after mixing,tempering and granulation,which was beneficial to improve the material accumulation and fluidity.The compression coefficient of feed was increased after mixing,tempering and granulation.It showed that the material had bad molding rate after pelleting,the internal friction angle after pelleting in three processing sections was the smallest,and the cohesive force was the largest,which indicated that greater shear stress to the material was need in pelleting process.