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南華大學機械工程學院畢業(yè)設(shè)計（論文）
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.China212013
Tel.: +86-511-8;Fax:+86-511-8
yangdy@163.com
Jinhu Agricultural Mechanization Technology Extension Station . Jinhu county
Jiangsu Province .P.R.China 211600
Abstract: 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 0.2s~0.3s 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 mechanism
Fig.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 69~90r/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 0s~0.2s, 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 C
Fig.4 Vertical force of C
4 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 60~90r/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 0.2s~0.3s. 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, 0.15s~0.3s 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, 0.2s~0.3s, 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 0.2s~0.3s 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 0.2s~0.3s 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 0.2s~0.3s 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 C
5 Experimental Analysis
The 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 80~110r/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 slicing
NO
Crank speed (r/min)
80
90
100
110
1
6.6%
6.4%
8.2%
9.5%
2
5.3%
6.1%
8.5%
9.2%
2
6.4%
7.9%
7.9%
9.4%
Average
6.1%
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 80~110r/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 Conclusion
The 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, 0.2s~0.3s, 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.1
References
[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 press[1999)
[4]Xiuning ,C.:optimal design of machinery .zhejiang university press[1999)
[5]Liping,C.,yunqing,Z.,weiqun,R.: dynamic analysis of mechanical systems and application Guide ADAMS . Tsinghua university press ,Beijing(2005)
Page 8 of 8
南華大學機械工程學院畢業(yè)設(shè)計（論文）
蓮藕切片機切片平滑度的研究和改進
楊德勇 胡建平 韋恩鑄 雷恒群 孔祥次
農(nóng)業(yè)設(shè)備和現(xiàn)代技術(shù)的國家重點實驗室
江蘇省教育部 江蘇大學.江蘇.鎮(zhèn)江
中國 江蘇省 212013
電話 +86-511-8:傳真+86-511-8
yangdy@163.com
金湖農(nóng)業(yè)機械化技術(shù)推廣站
中國 江蘇省 211600
摘要：針對蓮藕切削質(zhì)量不高和蓮藕片的斜邊問題，通過分析原因，改進的方法就是減少刀在垂直方向的力。在Pro/E的環(huán)境下創(chuàng)建了蓮藕切片機的3D零件和裝配體?；谔摂M樣機技術(shù)，切片機的運動學和動力學分析是在ADAMS軟件模擬實驗下實現(xiàn)的，獲得最佳的切削時間為0.2s~0.3s，并且得到了刀在垂直方向上的力的曲線。刀在垂直方向上的力隨著曲柄偏移量的變化而改變。曲柄的偏移量優(yōu)化結(jié)果表明，當曲柄的偏移量為-80mm時，在切削時間里的垂直方向上的力幾乎為零。測試結(jié)果表明，經(jīng)過改進設(shè)計后，切片厚度的相對誤差小于10％，這是能夠完全滿足技術(shù)要求的。
關(guān)鍵詞：蓮藕；切削機制；平滑度；優(yōu)化
1前言
中國是一個生產(chǎn)蓮藕的大國，蓮藕半成品系列食品的國內(nèi)消費和外部的出口需求量比較大，為了提高工作效率，減輕勞動強度，設(shè)計工作組，在借鑒人工切蓮藕片原理的基礎(chǔ)上設(shè)計和開發(fā)一個新型的切片機（畢偉，胡建平，2006年）。這種新型的切片機容易解決切片易斷，粘刀，難清理等問題，但過程中還是出現(xiàn)不平滑切削和一些斜邊的現(xiàn)象。本文通過對切削時刀片的分析，發(fā)現(xiàn)了一些造成斜邊現(xiàn)象的原因，并提出了相應(yīng)的改進方法，并通過實驗得到了驗證。
2 切片機切削結(jié)構(gòu)原理
蓮藕切片的切削原理是機器的核心，性能直接影響切片的質(zhì)量。在使用PRO / E平臺下建立了蓮藕切削原理的虛擬樣機（圖1），結(jié)構(gòu)本身的原理圖如圖2所示。蓮藕切片機的切削原理是通過核心的曲柄滑塊機構(gòu)往里面添加材料，它可以堆疊許多蓮藕，蓮藕依靠自己本身上部和下部的蓮藕，以便它能夠到達擋板的表面。曲柄滑塊機構(gòu)是由電機驅(qū)動，在滑塊上安裝刀片切蓮藕。但在切削過程中，發(fā)現(xiàn)在一塊蓮藕兩端面的平行度是不足夠的，這不能滿足加工的技術(shù)要求。
圖1 蓮藕切削原理的虛擬樣機
圖2 切片原理結(jié)構(gòu)圖
切片機的蓮藕片平滑度的研究和提高。
3 斜邊的原因
厚薄不均勻和斜邊問題與刀片在切削過程中的力量有關(guān)。按照結(jié)構(gòu)原理（圖2），不考慮相互間摩擦和重量的因素，C點的力F的方向是沿鏈接方向。力F可以分解為一個水平方向的分力和一個垂直方向的分力。水平分力造成的刀沿垂直方向移動切削，但垂直方向上的力造成的刀沿垂直方向移動。由于滑塊和導軌之間的差距，垂直分力會使葉片在運動時變形，刀不能沿水平方向切蓮藕，導致出現(xiàn)斜邊。因此，解決斜邊的問題和提高切削質(zhì)量的關(guān)鍵是減少或消除切片時的垂直分力。
當曲軸轉(zhuǎn)速為60~90轉(zhuǎn)/分鐘，C點和刀片連接部位的水平和垂直方向的力曲線如圖3和圖4所示。從圖上可以看出，當曲柄的速度提高后，C點水平和垂直方向的力也增加了，相對穩(wěn)定的水平力有利于切削蓮藕期間，但垂直方向上的力也逐漸增加。越多的垂直方向上的力，越不利于切削的質(zhì)量。
圖3 C點的水平力
圖4 C點的垂直方向上的力
4 仿真和優(yōu)化
如果提高切片的平整度，結(jié)構(gòu)優(yōu)化可以減少垂直分力，所以盡可能的要刀片保持水平。
當曲柄速度60~90轉(zhuǎn)/分鐘時，刀質(zhì)量中心的速度曲線和加速度曲線分別如圖5和圖6所示。根據(jù)速度曲線，在0.2s~0.3s時間里，刀質(zhì)量中心的速度是比較大的。按照刀應(yīng)該有更高的速度來切削蓮藕的要求，這期間的時間切削比其他時間更有利。根據(jù)加速度曲線，一個周期計算，在0.15s~0.3s的時間里，相比其他的時間段加速度值是相對比較小。這表明速度的變化相對較小，同時慣性產(chǎn)生的力小，切片機受力引起的振動影響小。因此，在0.2s~0.3s里來切蓮藕有利于提高蓮藕片的切削質(zhì)量。
圖5 刀片的質(zhì)量中心速度曲線
圖6 刀片的質(zhì)量中心加速度曲線
基于上述分析，刀片和鏈接之間的垂直分力是造成斜邊的主要原因。根據(jù)曲柄滑塊機構(gòu)的特點，在切削時間段通過改變曲柄偏移來減少對刀垂直方向上的力，從而提高切削質(zhì)量。當曲軸轉(zhuǎn)速為60轉(zhuǎn)/分鐘，曲軸偏心率得到了優(yōu)化。當曲柄偏移量分別為40mm，20mm，0mm，-20mm, -40mm, -80mm, -120mm時，在不同的偏移量下模擬其原理，獲得了垂直方向上的力曲線，如圖7所示。
圖7 不同偏移下的垂直方向上的力曲線
圖7表明：偏心率為正值時，在0.2s~0.3s隨著曲柄偏移量增加，C點的垂直方向上的力逐漸增加；當偏心率為負值時，隨著曲柄偏移量的增加，力開始下降，然后在-80mm處開始逐步增加。所以，當偏移量為-80mm，力在0.2s~0.3s的數(shù)值降到最低，這時切削質(zhì)量是最佳的。
當曲柄在其他的速度旋轉(zhuǎn)，有相同的優(yōu)化結(jié)果。圖8顯示的是曲軸轉(zhuǎn)速為80轉(zhuǎn)/分鐘、曲軸偏移量為0mm到-80mm時，垂直方向上的力。從圖8可以看出，當偏移量為-80mm時，C點垂直方向的里在0.2s~0.3s大大減少。因此通過優(yōu)化曲柄偏移量可以減少垂直方向上的力。
圖8 C點的垂直方向上的力
5 實驗分析
蓮藕片的厚度相對誤差反映了切削質(zhì)量，一般控制在10％。在結(jié)構(gòu)的優(yōu)化和改進前，總是存在斜邊現(xiàn)象，厚度相對誤差約為15%左右，這是難以滿足的技術(shù)要求。對曲柄滑塊機構(gòu)的偏移量進行優(yōu)化，并根據(jù)優(yōu)化的結(jié)果，它的結(jié)構(gòu)有了一些改進。改進后的曲柄，在速度的條件為80?110轉(zhuǎn)/分鐘時，切削試驗出來的厚度相對誤差的統(tǒng)計數(shù)據(jù)如表?1所示。從四個速度層次進行分析實驗，每個速度層次進行三次實驗。
表 1 切片厚度相對誤差
序號
曲柄速度(轉(zhuǎn)/分鐘)
80
90
100
110
1
6.6%
6.4%
8.2%
9.5%
2
5.3%
6.1%
8.5%
9.2%
2
6.4%
7.9%
7.9%
9.4%
平均
6.1%
6.8%
8.2%
9.4%
來自表1的數(shù)據(jù)顯示，當曲柄速度為80?110轉(zhuǎn)/分鐘時，切片厚度相對誤差能滿足各項技術(shù)指標，尤其是當曲軸旋轉(zhuǎn)速度為80轉(zhuǎn)/分鐘和90轉(zhuǎn)/分鐘時，厚度相對誤差低于7％，達到了較高的切削質(zhì)量。
6 總結(jié)
切削的過程中，表面不平整和斜邊的主要原因是作用在刀組件上的垂直分力，因此提高質(zhì)量的關(guān)鍵是減小垂直方向上的力。通過刀片質(zhì)量中心速度和加速度模擬分析曲線得到，0.2s?0.3s是切片的最佳時間。通過優(yōu)化曲柄的偏移量，當偏移量為-80mm時，垂直方向上的力在切削時間大大減小。經(jīng)過實驗改進蓮藕切片機后，實驗結(jié)果表明，通過改變曲柄偏移量，厚度相對誤差不到10％，完全能夠滿足要求。因此，平整度不理想和斜邊問題基本解決。
參考文獻
[1] 胡建平.蓮藕切片技術(shù)的學習和新的模型設(shè)計. 中國農(nóng)業(yè)機械化研究（12）,112~114.2006
[2] 韋恩鑄.基于虛擬樣機技術(shù)的新型蓮藕切片機仿真優(yōu)化.江蘇大學,2008
[3] 張 策.機械動力學.高等教育出版社,1999
[4] 陳秀林.機械優(yōu)化設(shè)計.浙江大學出版社,1999.
[5] 陳麗萍,鄭云群,容微群.機械系統(tǒng)的動態(tài)分析和應(yīng)用指南ADAMS.北京:清華大學出版
社,2005
第 7 頁 共 7 頁
本科畢業(yè)設(shè)計任務(wù)書
信息與機電工程系 填寫時間：2015年 1 月 12 日
課題名稱
立式切碎機
學生姓名
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11機械116707011
畢業(yè)設(shè)計
基本要求、重點需要
研究的問題
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2015年 1 月 23 日
1、 本設(shè)計課題的目的意義，主要及擬解決的關(guān)鍵性問題（附參考文獻）
中國是農(nóng)業(yè)大國，因此農(nóng)作物是中國重要的一部分。自古以來，中國的糧食總類很多，其中包括塊根莖物料，如馬鈴薯、地瓜、蘿卜、瓜果。中國人飯桌上或多或少都會出現(xiàn)以上塊根莖物料所制作而成的一道菜。所以如何更合理更簡單方便的處理塊根莖物料成為人們需要研究的一個課題。后來就出現(xiàn)了切碎機。切碎機是將大尺寸的固體原料切碎至要求尺寸或形狀的加工機械，它在農(nóng)品加工、中草藥加工、飼料加工等行業(yè)領(lǐng)域都有廣泛的應(yīng)用。切碎機按所切物料的形態(tài)不同可分為：莖稈類物料切碎機、塊狀類物料切碎機。依照要求，本課題針對塊狀類物料切碎機進行研究。
塊狀類物料切碎機按盤刀的方式不同可分為立式盤刀式切碎機、水平盤刀式切碎機和刀式切碎機。當前的滾刀式切碎機其最主要的形式就是圓錐形滾刀式切碎機，其主要用來切碎青綠物料和塊狀莖，其動刀片一般安裝在圓錐形滾筒上。當滾筒旋轉(zhuǎn)時，料斗內(nèi)的物料就被切碎，成品通過動刀和滾筒之間的空隙進入圓錐滾筒內(nèi)，并沿著圓錐斜面從滾筒的大端排出。由于圓錐僅部分表面和喂料斗接觸，所以生產(chǎn)效率較低，但工作較可靠。根據(jù)簡易程度我們研究立式盤刀式切碎機（簡易式切碎機）。
立式簡易切碎機由喂入斗和裝有4把刀片的圓盤組成.圓盤與地面垂直.工作時,塊根裝在圓盤左的喂入斗內(nèi).當圓盤旋轉(zhuǎn)時,盤上的刀片就將塊根切成薄片,由圓盤下方排出口(出料口)排出.這種型式的切碎機,構(gòu)造簡單,使用方便,易于保養(yǎng)修理.
1. 產(chǎn)品加工機械與設(shè)備,沈再春主編，中國農(nóng)業(yè)出版社。
2.機械設(shè)計手冊。
3.其它相關(guān)參考資料。
二、本設(shè)計課題的主要設(shè)計、預(yù)期設(shè)計結(jié)果
主要設(shè)計內(nèi)容：
按給定的物料和轉(zhuǎn)軸轉(zhuǎn)速，設(shè)計一套切碎系統(tǒng)，切碎機工作完畢后查其切碎的情況。
預(yù)期設(shè)計結(jié)果:
切割系統(tǒng)的設(shè)計要符合手動立式簡易切碎機（設(shè)計）規(guī)范要求，基本滿足使用上的功能要求，兼顧節(jié)能環(huán)保要求，實現(xiàn)經(jīng)濟和功能的統(tǒng)一。
擬解決的關(guān)鍵問題：
1、主動軸和從動軸的協(xié)調(diào)性及剛度要求；
2、滿足給定的切割要求；
3、切割效果分析；
三、設(shè)計方法和步驟
１、收集切碎機的資料，調(diào)查研究，通過分析比較、確定設(shè)計方案；
２、根據(jù)給定要求，進行設(shè)計參數(shù)的計算；
３、運用AutoCAD和Photoshop繪圖等工具進行設(shè)計。
４、進行切碎效果試驗；
５、撰寫設(shè)計說明書
4、 設(shè)計工作的總體安排及進度
第1設(shè)計周：收集資料、知識準備；
第2～3設(shè)計周：方案設(shè)計；
第4設(shè)計周：總體結(jié)構(gòu)草圖；
第5～10設(shè)計周：結(jié)構(gòu)設(shè)計、設(shè)計計算、總體裝配圖、
零件圖設(shè)計；
第11～13設(shè)計周：設(shè)計說明書（論文）編寫。
五、指導教師審查意見：
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六、系(教研室)審查意見：
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七、學院審查意見：
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