Abstract: In order to improve the cracking performance, this study optimized the operating parameters of key components by analyzing the influence of different operating parameters on the cracking performance for the walnut cracking machine with selfgrading extrusion. Through kinematic analysis of walnuts between the roller and the plate, the key factors affecting shell cracking and kernel extraction were determined, which included the cracking angle and roller speed. The combination experiment of twofactor and fivelevel quadratic orthogonal rotating center was carried out with shell cracking rate, whole kernel rate and energy consumption as the experimental indexes. Data analysis was performed using DesignExpert software to establish regression models between the factors and the test indicators. ANOVA obtained the major and minor factors affecting shell cracking rate, whole kernel rate, and energy consumption. The interaction of the two factors was analyzed using the response surface methodology. The regression model was multiobjectively optimized according to the importance of the optimization objective. The results showed that the optimal combination of working parameters was 0.47° of cracking angle and 108 r/min of roller speed. Under these conditions, it yielded a shell cracking rate of 97.24%, a whole kernel rate of 92.03%, and an energy consumption of 1.88 kJ/kg. The relative error between the validation result and the model prediction  was less than 5%. The results of variety adaptation tests showed that the optimal working parameters were appropriate for the three varieties of walnuts, including Wen185, Xinwen179, and Zha343, showing that the shell cracking rate was greater than 96%, the whole kernel rate was greater than 90%, and the energy consumption was less than 2 kJ/kg. The results of this study can provide theoretical references for the improvement and optimization of related shell cracking equipment and the selection of cracking and processing parameters for different varieties of walnut.

Key words: walnut, crackers, parameter optimization, response surface method (RSM)

摘要： 通过分析不同作业参数对自分级挤压式核桃破壳机破壳性能的影响规律，优化关键部件的作业参数，提高破壳性能。以核桃在辊板间的运动学分析为基础，确定影响核桃破壳取仁的关键因素为破壳角度和轧辊转速，并以破壳率、整仁率和能耗为试验指标，开展两因素五水平二次正交旋转中心组合试验。利用DesignExpert软件进行数据分析，建立各因素和试验指标之间的回归模型并进行方差分析，得到影响破壳率、整仁率和能耗的主次因素。利用响应面法分析两个因素的交互作用，根据优化目标的重要程度对回归模型进行多目标优化。试验结果表明：最优工作参数组合为破壳角度0.47°，轧辊转速108 r/min，在此条件下，得出破壳率为97.24%，整仁率为92.03%，能耗为1.88 kJ/kg，验证试验结果与模型预测值相对误差小于5%。品种适应性试验结果表明：最优工作参数对3个品种核桃(温185、新温179、扎343)的适应性较佳，表现为破壳率均大于96%，整仁率均大于90%，能耗均小于2 kJ/kg。为相关破壳取仁设备改进与优化以及不同品种核桃破壳加工参数的选取提供理论参考。

关键词: 核桃, 破壳机, 参数优化, 响应面法