定量变距螺旋结构设计与试验

Design and Experiment of Quantitative Variable Pitch Screw

针对等径变距螺旋喂料结构出料量不稳的问题,在等距螺旋结构流量计算式的基础上,提出一种变距螺旋结构流量的计算方法,并推导出流量计算式。根据流量计算式,采用响应面法对变距螺旋结构进行螺距设计,以流量作为响应值,应用Design-Expert软件设计试验,得到螺旋喂料结构进料段最佳螺距组合为S 1=0.35D,S 2=0.60D,S 3=0.85D,S 4=D。根据所得的最佳参数组合,用SolidWorks软件建立螺旋喂料结构三维模型并导入EDEM软件,以小米物料进行离散元分析,仿真质量流量平均值为0.321 kg/s,与变距实际计算流量值0.319 kg/s的误差为0.627%,与实际要求流量值误差为3.7%,验证了变距流量式的可靠性和响应面设计的可行性,可为定量变距螺旋结构的设计计算提供参考。

To face challenges of unstable discharge for feed structure with equal diameter variable pitch screw,a theoretical analysis for variable pitch screw capacity was presented under some simplification assumption,which was compared with the equal pitch one,and resulted in a flow calculation formula by reasonable mathematical derivation.Furthermore,design of variable pitch screw was optimized by using response surface method which a flow rate was set as the response value in accordance with the above calculation formula.The Box-Behnken test analysis was performed with the help of Design-Expert software,turning out that the optimal pitch combination for the smallest target flow error was S 1=0.35D,S 2=0.60D,S 3=0.85D,and S 4=D.After all,movement simulation for millet as transport medium were performed in the screw with obtained optimum design,which the 3D model was built with SolidWorks software and the EDEM software was imported for discrete element analysis.After calibration,the result indicated that the simulative mass flow was 0.321 kg/s,compared with calculation flow value of 0.319 kg/s and the difference rate of 0.627%,relative error of which was measured to the actual required flow was 3.7%.The reliability of the flow formula was verified while the feasibility of the response surface method to design the screw structure was proven,which provided a reference for the design of the quantitative variable pitch screw.