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南华大学机械工程学院毕业设计（论文）Study and Improvement for Slice Smoothness in Slicing Machine of Lotus Root De-yong YANG ,Jian-ping HU , En-zhu WEI , Heng-qun LEI ,and Xiang-ci KONG Key Laboratory of Modern Agricultural Equipment and Technology Ministry of Education Jiangsu Province Jiangsu University . Zhenjiang .Jiangsu Province .P.R.China212013Tel.: +86-511-8;Fax:+86-511-8Jinhu Agricultural Mechanization Technology Extension Station . Jinhu countyJiangsu Province .P.R.China 211600Abstract: Concerning the problem of the low cutting quality and the bevel edge in the piece of lotus root, the reason was analyzed and the method of improvement was to reduce the force in the vertical direction of link to knife. 3D parts and assemblies of cutting mechanism in slicing machine of lotus were created under PRO/E circumstance. Based on virtual prototype technology, the kinematics and dynamics analysis of cutting mechanism was simulated with ADAMS software, the best slice of time that is 0.2s0.3s was obtained，and the curve of the force in the vertical direction of link to knife was obtained. The vertical force of knife was changed according with the change of the offset distance of crank. Optimization results of the offest distance of crank showed the vertical force in slice time almost is zero when the offset distance of crank is -80mm. Tests show that relative error of thickness of slicing is less than 10% after improved design, which is able to fully meet the technical requirements. Keywords: lotus root; cutting mechanism; smoothness; optimization 1 Introduction China is a country of producing lotus toot, lotus root system of semi-finished products of domestic consumption and external demand for exports is relatively large. In order to improve efficiency, reduce labor intensity, the group work, drawing on the principle of the artificial slice based on the design and development of a new type of lotus root slice (Bi Wei and Hu Jianping, 2006). This new type of slice solved easily broken cutting, stick knives, hard to clean up and other issues, but the process appears less smooth cutting, and some have a problem of hypotenuse piece of root. In this paper, analyzing cutting through the course of slice knife, the reasons causing hypotenuse was found, and the corresponding improvement of methods was proposed and was verified by the experiments.2 Structure of Cutting Mechanism of Slicing Machine Cutting mechanism of the quality of slice lotus root is the core of the machine, the performance of its direct impact on the quality of slice. Virtual prototyping of cutting mechanism of slice lotus root (Fig.1) was built by using PRO/E, and mechanism diagram of the body is shown in Fig.2. Cutting principle of lotus slicer adopted in the cardiac type of slider-crank mechanism was to add materials inside, which can be stacked several lotus root, lotus root to rely on the upper part of the self and the lower part of the lotus press down, so that it arrives in the material under the surface of the baffle. While slider-crank mechanism was driven by motor, the knife installed on the slider cut lotus root. In the slice-cutting process it was found that parallelism of the surface at both ends of part of piece lotus was not enough, which can not meet the technical requirements for processing.Fig.1 Virtual prototyping of cutting mechanismFig.2 Diagram of cutting mechanism Study and improvement for slice smoothness in slicing machine of lotus root.3 The Cause of the Bevel Edge Uneven thickness and bevel edge of cutting were related with forces on the slice knife in the process of cutting. In accordance with cutting mechanism (Fig.2), without taking into account the friction and weight, the direction of force F of point C was along the link. Force F may be decomposed with a horizontal direction force component and a vertical direction force component. The horizontal force component pushed the knife moving for cutting, but the vertical force component caused the knife moving along the vertical direction. Because of the gap between the slider and the rail, the vertical force component made the blade deforming during the movement, and knife could not move along the horizontal direction to cut lotus root, which caused the emergence of bevel edge. Thus, to reduce or eliminate the vertical force component in the cutting-chip was key to solve the problem of bevel edge and improve the quality of cutting.When crank speed was 6990r/min, the horizontal and vertical direction of the force curve of point C connecting link and the blade hinge are shown in Fig.3 and Fig.4 respectively. As can be seen from the chart, with the crank speed improvement the horizontal and vertical direction of the force in point C also increased. The horizontal force changed relatively stable during 0s0.2s, which was conducive to cutting lotus, but the vertical force increased gradually. The more the vertical force was, the more detrimental to the quality cutting. Fig.3 Horizontal force of CFig.4 Vertical force of C4 Simulation and Optimization If improving flatness of the slicer, the structure was optimized to reduce the vertical force component, so as far as possible the level of cutting blade.When crank speed was 6090r/min the velocity curve and acceleration curve of the knife center of mass are shown in Fig.5 and Fig.6 respectively. According to the speed curve, the speed of the knife center of mass was relatively large in a period of 0.2s0.3s. In accordance with the requirements that the knife should have a higher speed during cutting lotus, so this period time was more advantageous to cutting than other terms. According to acceleration curve. When calculates by one cycle, the acceleration value was relatively quite small in the period of time, 0.15s0.3s compared with other time section. Which indicated that the change of velocity was relatively small, simultaneously the force of inertia was small, and the influence of vibration caused by the force was small to the slicer. Therefore,this period of time, 0.2s0.3s, to cut root piece was advantageous in enhances the cutting quality of lotus root piece.Fig.5 Velocity curve of center of mass of knife Fig.6 Acceleration curve of center of mass of knife Based on the above analysis, the vertical force component between link and the knife was the main reason for bevel edge. According to the characteristics of slider-crank mechanism, reducing the vertical force on the knife in the period of cutting time by altering crank offest was tried to enhance the quality of the cutting. When crank speed was 60r/min, the crank eccentricity was optimized. When the offest of the crank was 40mm, 20mm, 0mm, -20mm, -40mm, -80mm, -120mm respectively, the mechanism was simulated and the vertical force curves under different crank eccentricity were obtained, as shown in Fig.7.Fig.7 vertical force curves in different offest Fig.7 indicates that: When the eccentricity was positive, the vertical force on point C increased gradually in 0.2s0.3s with the increase of crank oddest: When the eccentricity was negative, the force decreased gradually first and then begun to increase along with -80mm. So when the offest was -80mm, the numerical of the force in 0.2s0.3s achieved the minimum and the quality of cutting was the best.When the crank rotated in the other speed, there were the same optimization results. Fig.8 show the curve of vertical force in the offest of 0mm and -80mm when the speed of crank was 80r/min. From the Fig.8 it is obvious that vertical direction of the force of point C in 0.2s0.3s reduced a lot when the eccentricity is -80mm. Therefore, the vertical force could be reduced by optimizing the slider-crank mechanism of eccentricity.Fig.8 Vertical force of C5 Experimental AnalysisThe relative error of thickness of lotus root piece reflects the quality of cutting. Which is generally controlled of 10%. There always existed bevel edge phenomenon and the relative error of thickness was about 15% before structural optimization and improvement, which was difficult to meet the technical requirements. The offset in the slider-crank mechanism was optimized, and its structure was improved according to the results of optimization. After improvement cutting test were done in the conditions of crank speed for 80110r/min and statistical data about the relative error of thickness was shown in Table.1. Four levels were separated in the experiment, three times for each level.Table 1 Relative error of thickness of slicingNOCrank speed (r/min)809010011016.6%6.4% 8.2%9.5%25.3%6.1%8.5%9.2%26.4%7.9%7.9%9.4%Average6.1%6.8%8.2%9.4% It is derived from Table.1 that the relative error of the thickness of slices could meet the technical indicators when the crank speed was 80110r/min, especially in the crank rotation speed 80r/min, 90r/min the relative error of thickness was less than 7%,and high quality was achieved.6 ConclusionThe vertical force component acted on the knife in the process of cutting was the main reason for surface formation and bevel edge, so the key of improving the quality was to reduce the vertical force. Through slice knife and velocity acceleration simulation analysis the best time for slicing, 0.2s0.3s, was obtained. By optimizing the offset of the crank the vertical force during cutting time was greatly reduced when the offset was -80mm. Experiments were made after improving the design of lotus root slicer, which results showed that by changing the offset of the crank, the relative error of the thickness could fully meet the requirements of less than 10%. So the problem was basically solved that the flatness was not ideal and was the issue of bevel edge.1References 1 Wei,B . jianping,H.: Study of lotus root slicing techniques and design of new model,Journal of agricultural mechanization research (12),112-114(2006)(in Chinese)2 Enzhu, w.:the simulation and optimization on the new slicing machine of lotus root based on virtual prototype technology .jiangsu university 2008)in Chinese)3 Ce ,Z .:mechanical dynamics .higher education press1999)4Xiuning ,C.:optimal design of machinery .zhejiang university press1999)5Liping,C.,yunqing,Z.,weiqun,R.: dynamic analysis of mechanical systems and application Guide ADAMS . Tsinghua university press ,Beijing(2005)Page 8 of 8南华大学机械工程学院毕业设计（论文）莲藕切片机切片平滑度的研究和改进杨德勇 胡建平 韦恩铸 雷恒群 孔祥次农业设备和现代技术的国家重点实验室江苏省教育部 江苏大学.江苏.镇江中国 江苏省 212013电话 +86-511-8:传真+86-511-8金湖农业机械化技术推广站中国 江苏省 211600摘要：针对莲藕切削质量不高和莲藕片的斜边问题，通过分析原因，改进的方法就是减少刀在垂直方向的力。在Pro/E的环境下创建了莲藕切片机的3D零件和装配体。基于虚拟样机技术，切片机的运动学和动力学分析是在ADAMS软件模拟实验下实现的，获得最佳的切削时间为0.2s0.3s，并且得到了刀在垂直方向上的力的曲线。刀在垂直方向上的力随着曲柄偏移量的变化而改变。曲柄的偏移量优化结果表明，当曲柄的偏移量为-80mm时，在切削时间里的垂直方向上的力几乎为零。测试结果表明，经过改进设计后，切片厚度的相对误差小于10，这是能够完全满足技术要求的。关键词：莲藕；切削机制；平滑度；优化1前言 中国是一个生产莲藕的大国，莲藕半成品系列食品的国内消费和外部的出口需求量比较大，为了提高工作效率，减轻劳动强度，设计工作组，在借鉴人工切莲藕片原理的基础上设计和开发一个新型的切片机（毕伟，胡建平，2006年）。这种新型的切片机容易解决切片易断，粘刀，难清理等问题，但过程中还是出现不平滑切削和一些斜边的现象。本文通过对切削时刀片的分析，发现了一些造成斜边现象的原因，并提出了相应的改进方法，并通过实验得到了验证。2 切片机切削结构原理莲藕切片的切削原理是机器的核心，性能直接影响切片的质量。在使用PRO / E平台下建立了莲藕切削原理的虚拟样机（图1），结构本身的原理图如图2所示。莲藕切片机的切削原理是通过核心的曲柄滑块机构往里面添加材料，它可以堆叠许多莲藕，莲藕依靠自己本身上部和下部的莲藕，以便它能够到达挡板的表面。曲柄滑块机构是由电机驱动，在滑块上安装刀片切莲藕。但在切削过程中，发现在一块莲藕两端面的平行度是不足够的，这不能满足加工的技术要求。图1 莲藕切削原理的虚拟样机图2 切片原理结构图切片机的莲藕片平滑度的研究和提高。3 斜边的原因厚薄不均匀和斜边问题与刀片在切削过程中的力量有关。按照结构原理（图2），不考虑相互间摩擦和重量的因素，C点的力F的方向是沿链接方向。力F可以分解为一个水平方向的分力和一个垂直方向的分力。水平分力造成的刀沿垂直方向移动切削，但垂直方向上的力造成的刀沿垂直方向移动。由于滑块和导轨之间的差距，垂直分力会使叶片在运动时变形，刀不能沿水平方向切莲藕，导致出现斜边。因此，解决斜边的问题和提高切削质量的关键是减少或消除切片时的垂直分力。 当曲轴转速为6090转/分钟，C点和刀片连接部位的水平和垂直方向的力曲线如图3和图4所示。从图上可以看出，当曲柄的速度提高后，C点水平和垂直方向的力也增加了，相对稳定的水平力有利于切削莲藕期间，但垂直方向上的力也逐渐增加。越多的垂直方向上的力，越不利于切削的质量。图3 C点的水平力图4 C点的垂直方向上的力4 仿真和优化如果提高切片的平整度，结构优化可以减少垂直分力，所以尽可能的要刀片保持水平。当曲柄速度6090转/分钟时，刀质量中心的速度曲线和加速度曲线分别如图5和图6所示。根据速度曲线，在0.2s0.3s时间里，刀质量中心的速度是比较大的。按照刀应该有更高的速度来切削莲藕的要求，这期间的时间切削比其他时间更有利。根据加速度曲线，一个周期计算，在0.15s0.3s的时间里，相比其他的时间段加速度值是相对比较小。这表明速度的变化相对较小，同时惯性产生的力小，切片机受力引起的振动影响小。因此，在0.2s0.3s里来切莲藕有利于