摘要
环模制粒成型技术以其高效率、高成型率、低污染等优点广泛应用于饲料机械、生物质能源机械、化工、制药等领域,而环模制粒过程扭矩模型的缺失已成为制约制粒技术发展的瓶颈之一。该文旨在通过理论分析、数值模拟与试验研究,建立粉体旋转挤压制粒成型过程精确扭矩模型,为粉体旋转挤压制粒成型装备的节能降耗及优化设计奠定理论基础。针对各向同性粉体物料,基于微单元受力分析及广义胡克定律,建立了旋转挤压制粒成型过程中模孔不同深度位置挤压压强的计算公式;基于DPC模型及实际辊轧工艺,建立了旋转挤压成型过程有限元分析模型,进行了压紧区应力分析;基于有限元模拟分析结果,设定变形压紧区的压强分布为二次曲线,建立了变形压紧区、挤压区的压强分布模型;最后建立了粉体旋转挤压制粒成型扭矩模型。以无线扭矩测试系统及环模制粒机为试验平台进行了鸡饲料的环模挤压制粒试验,求解得到了所有模型常量。设计了9组扭矩测试试验进行模型验证,测试结果与理论计算对比表明,试验值与计算值差距较小,最大计算误差仅为2.6%,这反映出建立的模型正确有效,对指导环模制粒机结构优化与节能降耗具有重要的意义。
Rotary roll extrusion pelleting technology is a kind of mainstream technology in the area of pellet forming technology, and the pellet mill has been widely used in the biomass-energy industry, feed industry, chemical industry, pharmacy, and so on. The pellet produced by the pellet mill has many advantages, such as a high forming rate, high absorption rate, high calorific value, and low pollution. But because of absence of the torque modeling theory, the existing pelleting technology with high consumption, low productivity, and low service life has been the bottleneck of industrial development. By a mathematical analysis, FEA simulation, and testing research, this paper aimed at developing an accurate torque model in the pelleting process of rotated roll forming. First, based on the unit force analysis and generalized Hooke law, the pressure distribution model along the die hole was founded. Then based on the DPC model and rolling processes, the FEA model of the pelleting process was created, and the stress distribution in the compacted zone was analyzed. Next, based on the results of the FEA, the pressure distribution in the compacting zone was set as aquadratic curve, and the pressure models in the compacting zone and extruding zone were built. Finally, the torque model in the ring-die pelleting process was developed. The experiments were designed to verify the model created, and the wireless torque testing system was used to analysis the torque datum. In order to eliminate the effect of the bending moment of the belt in pelleting process, two strain foils were stuck symmetrically along the same circumference of a shaft. The experimental material was chicken feed and the main components included Zea mays, wheat, bean, fish flour, bone flour, salt, and so on. The structural parameters of the pellet mill were as follows： the ring die radius was 175 mm, the number of rollers was 2, the ring die width was 110 mm, the die hole radius was 1.75 mm, the die hole length L was 35 mm, the percentage of the die opening area was 0.3, the roller radius was 80 mm, and the linear velocity was 6.1 m/s. When the pellet mill was in stability conditions, the torque data were tested in real time, and the average value in one minute was obtained as the torque value. At the same time, the pellets produced in one minute were collected and weighed to compute the volume of production. The tested results were as follows：the torque was 1 518.5 N·m, the production rate was 5.1 t/h, and the constant PN0 was 3.79 kPa. Based on the tested datum, all the model constants were determined and the torque model was developed. In order to verify the torque model, calculations and experiments were carried out in three other different linear velocities. It was shown that the computing datum was very close to the experimental results and the calculation error was less than 3%. The research was helpful to optimizing the structure, reducing energy consumption, and using the pellet mill efficiently.
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2013年第24期33-39,共7页
Transactions of the Chinese Society of Agricultural Engineering
基金
江苏省自然科学基金项目(BK2011706)
江苏省六大人才高峰项目(2010-JXQC-080)
江苏省产学研联合创新资金计划项目(BY2012023)
关键词
建模
试验
制粒
粉体
环模
扭矩
modeling, experiments, pelletizing, powder, ring-die, torque
