柔性带剪切挤压核桃破壳机理分析与性能试验  

Shell Crushing Mechanism Analysis and Performance Test of Flexible-belt Shearing Extrusion for Walnut

作　　者：刘明政[1] 李长河[1] 张彦彬[1] 杨敏[1] 侯亚丽[1] 高连兴[2] 

机构地区：[1]青岛理工大学机械工程学院,青岛266520 [2]沈阳农业大学工程学院,沈阳110866

出　　处：《农业机械学报》2016年第7期266-273,共8页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家自然科学基金项目(50775151;51075284)

摘　　要：传统的核桃破壳取仁装置多采用刚性元件,工作过程中易造成核桃仁过度破碎,同时剥壳率低、适应性差。为提高核桃破壳取仁效果,结合核桃机械破壳原理,设计了柔性带剪切挤压式核桃破壳取仁分离设备。利用弹性力学理论对核桃壳不同部位的刚度进行分析,得到不同部位失稳时的临界力;利用薄壳理论对核桃壳受挤压时的内力和形变进行分析,得出核桃不同部位裂纹产生和破壳时的临界力;利用断裂力学理论分析和计算了核桃破裂后裂纹扩展的条件。采用单因素试验方法分别探究间距A、上下带速度差B及挤入夹角C对核桃破壳效果的影响,然后再通过正交试验确定3种因素的一组最优解。试验结果表明:在间距为23 mm,上下带速度差为0.19 m/s,挤入夹角为45°时破壳效果最为理想,一露仁率、二露仁率、碎仁率、未露仁率分别为75%、18%、5%、2%,即破壳率为98%,整仁率为93%。The rigid components are always used in traditional walnut shell-broken kernel-taken device.During working process,the walnut kernel is easy to be excessively broken. The shell-broken rate and kernel-unbroken rate are also low and the adaptability for different kinds of walnut is poor. In order to improve the walnut shell-broken and kernel-unbroken effect, combining with the current research situation of walnut shell breaking by mechanical approaches,a walnut shearing-extrusion flexible shell crushing,kernel taking and shell-kernel separating device was designed. Stiffness at different positions of walnut shell was analyzed by theory of elastic mechanics,which contributed critical force of unstability of different positions. Critical force of cracking and breakage at different positions of walnut shell was disclosed. Conditions for crack extension after walnut shell breakage were analyzed and calculated by fracture mechanics theory. The results demonstrated that when the mean crack length is 20 mm,the critical external force for crack extension is 19. 1 N. The single-factor experiment was carried out to analyze the impact of the top and low section belt spacing（ A）,top and low section velocity difference（ B） and extrusion included angle（ C） on walnut crushing force. In this way,the optimal combination of three factors（ A,B,C） can be identified through the orthogonal experiment. The experimental results indicated that with A of 23 mm,B of 0. 19 m / s and C of 45°,the most satisfactory shell-broken effects were obtained,which generated the first grade kernel rate of 75%,the second grade kernel rate of 18%,the kernel cracking rate of 5% and the kernel-unseen rate of 2%. In other words,under this condition,the shell-broken rate reached 98% and the kernel-unbroken rate reached 93%.

关 键 词：核桃 柔性带 剪切挤压破壳 机理分析 性能试验 

分 类 号：S226.4[农业科学—农业机械化工程] S664.1[农业科学—农业工程]