莲仁钻削去心过程力学特性及减损工艺参数优化

Mechanical properties and optimization of process parameters for loss reduction during removing lotus core by drilling

为降低莲仁在钻削去心过程中的加工损耗,找出去心工艺参数对莲仁崩碎的影响规律,该文对莲仁钻削去心过程进行了力学分析、切削过程摸拟、试验测试和工艺参数优化研究。1)对莲仁钻削去心时的受力状态进行了力学分析,建立了莲仁钻削加工的力学模型,分析了莲仁钻削崩碎的主要因素为压辊夹紧力、钻头直径、钻头转速、钻头进给量和莲仁含水率等;2)应用 DEFORM 3D软件对莲仁钻削加工过程进行了切削仿真,获得了不同工艺参数条件下钻削轴向力变化曲线以及莲仁应变云图,得到了各工艺参数对莲仁崩碎的影响规律,并找出了莲仁剥落的薄弱位置;3)用Kistler测力仪对莲仁钻削去心过程进行了钻削力测试,得到了莲仁在钻削过程中轴向力-时间曲线,以及切削速度、进给量、钻头直径等工艺参数对钻削轴向力的影响曲线,测试结果与仿真结果基本一致;4)基于所设计的莲仁去心试验台,用单因素试验法测试了含水率、压辊夹紧力、钻头速度、钻头进给量及钻头直径等工艺参数对莲仁崩碎率的影响规律,并在单因素试验结果的基础上,用正交优化试验法获得最优参数组合为莲仁含水率 7.78%、钻头直径 2.2 mm、压辊夹紧力 38 N、钻头进给速度 20 mm/s、钻头转速 3 000 r/min。研究结果可为莲仁钻削去心设备的设计提供参考。

Removal of lotus core is one of the important processes in lotus kernel processing. Mechanical removal of lotus core is to use rotating drill to break up and break out lotus core along the axial direction of lotus kernel. The so-called crumbling of lotus kernel refers to the phenomenon of spalling and crushing of lotus kernel. In order to minimize the processing losses and reduce the processing costs of lotus kernel in the process of drilling lotus core, and find out the influence law of the related process parameters on the crumbling of lotus kernel during the process of drilling core, in this paper, the mechanical analysis, simulation, test and process parameter optimization on the process of drilling lotus core were carried out. 1) The stress state of lotus kernel during core removal was analyzed, including the overall stress analysis of lotus kernel and the drilling force analysis. And the mechanical model of lotus kernel in drilling was established. The main factors affecting the crumbling of lotus kernel during core removal were analyzed, such as the clamping force of press roller, the drill diameter, the drill speed, the feeding rate of drill and the water content of lotus kernel. 2) Based on the related physical parameters of lotus kernel in other literatures, the DEFORM 3D finite element method was used to simulate the core removal process. Through the corresponding post-processing of the simulation results, the variation curve of axial drilling force with time and strain contours of lotus kernel under different process parameters were obtained. By analyzing curves and strain contours,the influence law of each process parameter about the crumbling of lotus kernel was obtained. And we found out the most vulnerable place to peel off in the process of core removal. 3) The drilling force was tested by Kistler dynamometer in the process of core removal. The actual axial force-time curve in the drilling process was obtained, as well as the influence curve of drill speed, feeding speed of drill and drill diameter on the axial drilling force was obtained by test. By comparison, it was found that the test results were basically consistent with the simulation results. 4) Based on the designed lotus kernel coring test bench, the influence of water content, clamping force of press roller, drill speed, feeding speed of drill, drill diameter and other process parameters on the crumbling rate of lotus kernel was tested by single factor test method. And on the basic of the single factor test results, the optimum technological parameters were obtained by orthogonal optimization test. The optimum technological parameters were as follows: The water content was 7.78%,the drill diameter was 2.2 mm, the clamping force of the press roller was 38 N, the feeding speed of drill was 20 mm/s, and the drill speed was 3 000 r/min. The result of this study can provide a reference for the design of equipment of lotus core removal by drilling.