| 适宜核桃壳划口位置改善其破壳特性提高整仁率 |
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| 引用本文： | 郑霞,张恩铭,坎杂,张宏文,李红斌,丑维新.适宜核桃壳划口位置改善其破壳特性提高整仁率[J].农业工程学报,2018,34(19):300-308. |
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| 作者姓名： | 郑霞 张恩铭 坎杂 张宏文 李红斌 丑维新 |
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| 作者单位： | 石河子大学机械电气工程学院;农业部西北农业装备重点试验室;新疆科神农业装备科技开发股份有限公司 |
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| 基金项目： | 新疆兵团工业及高新技术科技攻关与成果转化计划项目（编号：2016AB003） |
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| 摘 要： | 针对目前传统单一的机械破壳方式存在的破壳率和整仁率难以平衡的问题,该文以预处理视角研究了对新疆核桃进行破壳前划口预处理的静态压力试验,试验结果表明,核桃划口预处理相比未处理核桃的破壳力和破壳形变量明显减小,整仁率明显增加;当核桃划口位置和施加载荷位置均在核桃肚部时,核桃破壳力和破壳形变量均明显减小,与未处理的核桃相比破壳力减小了139 N,减幅为38.4%;破壳形变量减小了0.37 mm,减幅为18.2%;利用三维扫描仪对研究对象进行三维建模,使其更接近物料实形,并实施模型核桃划口处理。有限元静力学分析结果表明:未划口处理的核桃,其壳体表面最大应变、应力和形变发生在加载位置;当加载力相同时,划口预处理条件下在核桃划口位置产生的应变、应力和形变量最大;当核桃划口位置和加载位置均在核桃肚部时,核桃壳表面产生的应变、应力和形变量均较大。该研究结果经验证与静态压力试验结果基本吻合。研究结果为核桃划口机和核桃破壳设备的研制提供理论支撑。
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| 关 键 词： | 有限元法 开裂 划口 核桃 预处理 |
| 收稿时间： | 2018/5/5 0:00:00 |
| 修稿时间： | 2018/8/11 0:00:00 |
Improving cracking characteristics and kernel percentage of walnut by optimal position of cutting on shell |
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| Zheng Xi,Zhang Enming,Kan Z,Zhang Hongwen,Li Hongbin and Chou Wenxin.Improving cracking characteristics and kernel percentage of walnut by optimal position of cutting on shell[J].Transactions of the Chinese Society of Agricultural Engineering,2018,34(19):300-308. |
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| Authors: | Zheng Xi Zhang Enming Kan Z Zhang Hongwen Li Hongbin and Chou Wenxin |
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| Institution: | 1. College of Mechanical and Electrical Engineering, Shihezi University, Shihezi 832000, China; 2. Ministry of Agriculture in Northwest China Key Laboratory of agricultural equipment, Shihezi 832000, China;,1. College of Mechanical and Electrical Engineering, Shihezi University, Shihezi 832000, China; 2. Ministry of Agriculture in Northwest China Key Laboratory of agricultural equipment, Shihezi 832000, China;,1. College of Mechanical and Electrical Engineering, Shihezi University, Shihezi 832000, China; 2. Ministry of Agriculture in Northwest China Key Laboratory of agricultural equipment, Shihezi 832000, China;,1. College of Mechanical and Electrical Engineering, Shihezi University, Shihezi 832000, China; 2. Ministry of Agriculture in Northwest China Key Laboratory of agricultural equipment, Shihezi 832000, China;,3. Xinjiang koshen agricultural equipment technology development co. LTD, Shihezi 832000, China and 1. College of Mechanical and Electrical Engineering, Shihezi University, Shihezi 832000, China; 2. Ministry of Agriculture in Northwest China Key Laboratory of agricultural equipment, Shihezi 832000, China; |
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| Abstract: | Abstract: In view of the difficulty of balancing the cracking shell rate and the whole kernel ratio existing in the traditional single mechanical cracking shell method, this paper conducted the static pressure test of cutting treatment of Xinjiang Xinfeng walnut shell before broken from the pretreatment perspective. In order to more fully reflect the main characteristics of walnuts, the physical properties of walnuts were analyzed. The three-dimensional model of walnuts was built as a thin sphere shell, and three-dimensional modeling was performed with a three-dimensional scanner to make it more similar to real walnut shape. And cutting pretreatment of the model of walnut shell was implemented. Through the finite element static analysis of non-pretreated model of walnuts, the effects of the position of the walnuts shell pretreatment, the magnitude of the loading force and the position of the loading force on the strain, stress and deformation were studied. Through the static pressure test study, it is known that shell breaking force for the untreated Xinfeng walnut when loading force is along the transverse diameter is 93 N larger than that along the edge diameter of walnut. The deformation required to break the shell along the transverse diameter is 0.46 mm greater than that required along the edge loading force. Untreated Xinfeng walnuts had a whole kernel rate of 86% when loading force was applied along the transverse diameter, and a whole kernel rate of 78% along the edge diameter. When the loading force was applied for the untreated Xinfeng walnuts along the transverse diameter, the whole kernel rate is 8 percentage point higher than that along the edge diameter. After the belly cut pretreatment, the breaking force and broken shell deformation of Xinfeng walnut were significantly reduced. When the loading position was coincident with the cutting position, the shell breaking force was reduced by 139 N, a decrease of 38.4%, and the breaking shell deformation was reduced by 0.37 mm, a decrease of 18.2%. When the direction of the loading force was perpendicular to the cut direction, the breaking force was decreased by 18 N, a decrease of 6.6%. The shell deformation was reduced by 0.11 mm, a reduction of 7%. When the loading position coincided with the cut position, the whole kernel rate for Xinfeng walnut pretreated was 12 percentage point higher than that for the untreated Xinfeng walnut. When the direction of the loading force was perpendicular to the direction of the cutting, the whole kernel rate of Xinfeng walnut pretreated with cutting belly was 8% higher than that of the untreated Xinfeng walnut. After the suture line cutting pretreatment, the breaking force of the walnut was obviously lower than that of the walnut without pretreatment. When the loading position coincided with the cut position, the breaking force was decreased by 32 N, and the reduction was 11.9%. The shell deformation was decreased by 0.21 mm, a decrease of 13.4%. When the loading force direction was perpendicular to the cut direction, the shell breaking force was reduced by 82 N, a reduction of 22.7%. The broken shell deformation was reduced by 0.16 mm with a reduction of 7.9%. When the direction of the loading force was perpendicular to the cutting direction, the percentage of the entire Xinfeng walnut after the pretreatment of the suture line cutting was 2 percentage point higher than that of the untreated Xinfeng walnut. When the loading position coincided with the cut position, the whole kernel rate of Xinfeng walnuts with the suture line cut pretreatment was 6% higher than that of untreated Xinfeng walnuts. The finite element static analysis was performed using the related parameters of static pressure test. The results showed that when the same force was applied, the cut pretreated walnuts produced larger strain, stress and deformation on the shell surface of the walnut model than the untreated. The large strain, stress and deformation of the shell surface of the walnut model generally occurred at the loading position or at the cut position. And the maximum strain, stress and deformation were generated on the surface of the walnut shell when the walnut cut position and the position of loading force were both at the walnut belly. It is noted that the shells of the walnuts pretreated are easier to be broken, and the broken position is generally at the loading position or the cut position; when the loading position and the cutting position are at the walnut belly, it is most conducive to cracking. Analysis showed that when the walnut shell is cracked from the belly, it is more conducive to cracking the walnut along the large gap, so as to ensure the walnut whole kernel rate. The results of finite element static analysis basically agree with that of the static pressure test. The study can provide effective technical support for the development of walnut cutting machine and walnut cracking machine. |
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| Keywords: | finite element method crack cutting walnut pretreatment |
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