山核桃破壳机加载锤头设计与试验  

Design and Test on Hammerhead of Pecan Shell-breaking Machine

作　　者：曹成茂[1] 蒋兰 吴崇友[2] 李正 汪天宇 丁冉[1] CAO Chengmao JIANG Lan WU Chongyou LI Zheng WANG Tianyu DING Ran(School of Engineering, Anhui Agricultural University, Hefei 230036, China Nanjing Research Institute for Agricultural Mechanization, Ministry of Agriculture, Nanjing 210014, China)

机构地区：[1]安徽农业大学工学院,合肥230036 [2]农业部南京农业机械化研究所,南京210014

出　　处：《农业机械学报》2017年第10期307-315,共9页Transactions of the Chinese Society for Agricultural Machinery

基　　金：国家自然科学基金项目(51475002)

摘　　要：针对现有的山核桃破壳机多采用点、线等单一的加载接触形式进行破壳,使得工作过程中山核桃受力大小分布不均,从而导致低破壳率、高果仁损伤率的现象,设计了多种不同加载接触形式的锤头类型,以山核桃破壳后破壳率、果仁损伤率、露仁率、裂纹分布为评价指标,通过试验探究了不同加载接触形式下的破壳效果。通过有限元分析探究了不同窝眼个数的锤头对破壳过程中裂纹分布和扩展的影响,并以锤头结构参数和加载方向为试验因素进行了正交试验,确定了最佳锤头结构参数组合。试验结果表明,凹槽式锤头结构能够降低加载方向因素对破壳效果影响的显著性;凹槽中附加的窝眼能够使破壳后的果壳产生大量局部裂纹点,并沿窝眼棱线扩展产生裂纹,具有裂纹引导作用;窝眼个数增加,山核桃破壳后的裂纹数增加且裂纹分布均匀、范围广,有效提高了山核桃的破壳质量;当凹槽直径为28 mm,窝眼个数为7时,破壳效果最理想,破壳率、一露仁率、二露仁率、果仁损伤率的均值分别为98.88%、37.05%、57.24%、5.71%。At present, it is universally acknowledged that the mechanical shell-breaking method is regarded as the main research strategies in the process of pecan shell-breaking equipment design. The design and improvement of shell-breaking method and principle had been studied extensively. However, in each kind of shell-breaking method, the research on the loading contact form between the broken shell mechanism and the pecan was neglected. Whether in the study of pecan shell-breaking principle and method or the design of mechanical equipment, the load which was provided with a single contact form was bore for pecan, such as point load or line load. In the course of processing, the size of the shell- breaking force was prone tO cause the partial breakage of the shell or the serious damage of the nut, which led to the phenomenon of low shell-breaking rate and high nut damage rate. Therefore, the groove shape hammerhead with sockets was developed. The hammerhead structures of different loading contact form were designed. And the shell-breaking effect on different loading contact form was researched by test. When the pecan was broken, the shell-breaking rate, nut damage rate and exposure nut rate of pecan were deemed as evaluation index. The crack distributions which were formed of three hammerheads in different loading directions were compared and analyzed. The finite element analysis software Abaqus was used to research the distribution and propagation of crack in the process of the shell-breaking, which considered the structure of the hammerhead with four different numbers of sockets as the variable. The orthogonal test which considered the structure parameters of the hammerhead and the loading direction as experimental factors was designed and used to determine the optimum combination. The results showed that the structure of the hammerhead in the groove shape can reduce the influence of the loading direction factor on the shell-breaking effect. Containing a plurality of sockets can make the pecan shell generate a large n

关 键 词：山核桃 破壳 加载锤头 窝眼凹槽式 裂纹引导 

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]