升運鏈?zhǔn)今R鈴薯播種機(jī)的設(shè)計

升運鏈?zhǔn)今R鈴薯播種機(jī)的設(shè)計,鏈?zhǔn)?馬鈴薯,播種機(jī),設(shè)計 畢業(yè)設(shè)計說明書外文摘要 The Design For The Ladle—chain dispenser of Potato Abstract Potato, which is one of the most important grain crops in our country, is growthing in a rather huge area. In 2007, potato’s planting area and output of China situated in the first place of the whole world. Although the ultimate output is huge, the per unit area yield quantity is at a rather low palce. The tow primary reasons for this situation are that we are behindhand in the way of planting and in the mechanized level. Therefore, the currently primary mission is enhances the per unit area yield quantity. Generally speaking,we could arrive at this aim through two ways: First, improving the way to plant; Second, enhancing the mechanized level of planting. At now, raising the mechanized production level is the most effective way. This will request each kind of potato-planting machine with advanced performance, high efficiency of planting, strong universal property and adaptability, and simple structure that is easy to be produced and maintained to be designed unceasingly and widely promoted and applicated vigorously. Rises to transport the chain potato seeder is one kind of sowing seeds massive potato seed tuber's seeder. With its simple structure, reliable operation, high efficiency, and hurtless to plants, this machine is widely applicated both in domestic and foreign country. Key words Planter Potato Ladle—chain dispenser Fluted roller fertilizer apparatus Hoe opener 山 西 農(nóng) 業(yè) 大 學(xué) 本科生畢業(yè)論文（設(shè)計）選題審批表 畢業(yè)論文（設(shè)計）題目 馬鈴薯播種機(jī)具設(shè)計 指 導(dǎo) 教 師 左月明 職 稱 教授 學(xué)生具備條件 熟練做圖的能力、演算的能力，以及獨立分析問題的能力 選題完成形式 畢業(yè)設(shè)計說明書和圖紙 內(nèi) 容 簡 要： 馬鈴薯是我國主要的糧食作物之一，在我國得到大面積栽種。2007年，我國馬鈴薯種植面積和產(chǎn)量都位居世界首位，然而盡管總產(chǎn)量大，但是單產(chǎn)量卻很低。造成這一原因的主要因素是種植方式和機(jī)械化水平的落后。因此，當(dāng)前的主要任務(wù)就是提高馬鈴薯種植的單產(chǎn)量。提高馬鈴薯單產(chǎn)量有兩個途徑：一是改進(jìn)種植方式；二是提高機(jī)械化種植水平。而提高機(jī)械化生產(chǎn)水平是最有效的方式，這就要求各種性能先進(jìn)，種植效率高，通用性和適應(yīng)性強(qiáng)，結(jié)構(gòu)簡單易于制造與維修的馬鈴薯種植機(jī)不斷被設(shè)計出來并得到大力的推廣與應(yīng)用。升運鏈?zhǔn)今R鈴薯播種機(jī)是一種塊狀馬鈴薯播種機(jī)，其結(jié)構(gòu)簡單，工作可靠，效率高，不傷種，在國內(nèi)外正逐漸得到廣泛的應(yīng)用。 系主任簽字： 年 月 日 院長簽字： 年 月 日 2 山西農(nóng)業(yè)大學(xué) 本科生畢業(yè)論文(設(shè)計) 開題報告 題 目 馬鈴薯播種機(jī)具設(shè)計 學(xué)院名稱 工程技術(shù)學(xué)院 專業(yè)名稱 機(jī)械設(shè)計制造及其自動化 年 級 2005級 學(xué)生姓名 郭小君 學(xué) 號 03 指導(dǎo)教師 左月明 職 稱 教授 2009年6月12日 選題的依據(jù)及意義（包括課題的理論價值和實踐價值；國內(nèi)外的研究概況等）： 馬鈴薯是一種高蛋白農(nóng)作物，在我國得到廣泛地栽種。2007年我國馬鈴薯種植面積約8000萬畝，總產(chǎn)量超過6800萬噸，占世界總產(chǎn)量的22%左右（www.potatoweb.cn ，2007年）。單從總產(chǎn)量來說我國已經(jīng)是世界第一，但是單產(chǎn)量卻遠(yuǎn)遠(yuǎn)低于歐美和澳洲的水平。例如，2003年，我國馬鈴薯的單產(chǎn)量是每公頃14842公斤，低于世界平均水平每公頃16448 公斤，還不到單產(chǎn)量最大的國家新西蘭每公頃44248 公斤的三分之一（www.potatoweb.cn ，2007年）。 我國馬鈴薯種植單產(chǎn)量很低這已是不爭的事實，因此，我國應(yīng)該把提高馬鈴薯的單產(chǎn)作為目前提高馬鈴薯產(chǎn)量的首要任務(wù)。提高馬鈴薯單產(chǎn)的措施除了提高機(jī)械化生產(chǎn)水平外，還應(yīng)該改進(jìn)馬鈴薯的種植方式。 提高單產(chǎn)量，首要任務(wù)就是提高機(jī)械化生產(chǎn)水平。當(dāng)前，除少部分地區(qū)已經(jīng)實現(xiàn)馬鈴薯機(jī)械化或半機(jī)械化種植以外，我國大部分的馬鈴薯種植方式一直停留在傳統(tǒng)種植的水平上，傳統(tǒng)的種植方式主要依靠人力和畜力進(jìn)行生產(chǎn)，從開溝到覆土鎮(zhèn)壓，整個過程勞動強(qiáng)度大，生產(chǎn)效率低，種植效果也遠(yuǎn)遠(yuǎn)低于機(jī)械化種植水平；而且我國地域廣闊，擁有多種地型，因此需要的播種機(jī)的機(jī)型也相對不一，設(shè)計出具有較強(qiáng)適應(yīng)性的播種機(jī)將成為未來播種機(jī)發(fā)展的必然趨勢；播種機(jī)的通用性也是一個不可忽略的重要因素，提高播種機(jī)的通用性有助于提高播種機(jī)的使用性能，使得播種機(jī)得到充分的利用。雖然從當(dāng)前的情況來看，我國在播種機(jī)這塊領(lǐng)域還不能一下子縮小同國外發(fā)達(dá)國家之間的差距，但是正在將這種差距正在不斷縮小。 傳統(tǒng)的馬鈴薯種植方式也是一個制約馬鈴薯單產(chǎn)量提高的重要因素，主要體現(xiàn)在：（1）馬鈴薯種子的質(zhì)量不高，我國種植馬鈴薯的大部分地區(qū)，馬鈴薯種子一般是自留的，沒有經(jīng)過消毒，殺菌以及其它提高種植質(zhì)量的技術(shù)處理，因此種出來的馬鈴薯質(zhì)量和產(chǎn)量不高；（2）種薯的品種不全，不同的地區(qū)，不同的氣候往往需要不同的馬鈴薯種子，在這方面，我國所作的研究還遠(yuǎn)遠(yuǎn)不能滿足其需求，因此，在今后更應(yīng)該加大對馬鈴薯品種的研制；（3）傳統(tǒng)的種植方式主要靠人力和畜力，工作量大而且工作效率低，對土壤的壓實比較嚴(yán)重，這對種子的發(fā)芽和生長極為不利。 本課題研究內(nèi)容 （1）馬鈴薯播種機(jī)具的總體設(shè)計 （2）馬鈴薯播種機(jī)傳動機(jī)構(gòu)的設(shè)計 （3）馬鈴薯播種機(jī)開溝裝置的設(shè)計 （4）馬鈴薯播種機(jī)排種裝置的設(shè)計 （5）馬鈴薯播種機(jī)輸種管、鎮(zhèn)壓裝置以及行走輪的設(shè)計 本課題研究方案 總體方案擬將開溝裝置、施肥裝置、排種裝置、覆土裝置及鎮(zhèn)壓裝置與選用拖拉機(jī)融為一體，使之能一次性順利完成開溝、施肥、播種、覆蓋、鎮(zhèn)壓等功能，懸掛機(jī)構(gòu)要有效的控制工作部件作業(yè)時的播深以及運輸時的通過性，開溝器除了能開出平整的地溝外還具備自動覆土的功能；排種裝置確保在播種過程中出現(xiàn)漏播、重播等現(xiàn)象的幾率不超過3%。鎮(zhèn)壓輪要求鎮(zhèn)壓效果好，作業(yè)后的地面平整。 研究的創(chuàng)新之處 該馬鈴薯播種機(jī)由機(jī)架、開溝器、輸種管、輸肥管、覆土器、種箱、肥箱、排種器以及鎮(zhèn)壓輪構(gòu)成，在機(jī)架的前梁上有上、下懸掛架用于與拖拉機(jī)連接；種、肥箱側(cè)板固定在機(jī)架中間橫梁的上方，前邊為肥箱，后邊為種箱，下邊固定排肥、排種裝置；在肥箱前面有一根安裝開溝器的梁，通過U型螺栓將開溝器的扁鋼鎖住，從而可以調(diào)節(jié)開溝深度，開溝器在橫梁上可根據(jù)需要進(jìn)行橫向移動來調(diào)節(jié)行距；機(jī)架的后梁用來連接鎮(zhèn)壓輪。 地輪隨拖拉機(jī)前進(jìn)而轉(zhuǎn)動，由地輪傳遞動力，在地輪軸的兩端各裝一個傳動鏈輪, 通過鏈條將力矩傳給中間傳動鏈輪，再由中間鏈輪將動力傳給排種排肥裝置,通常情況下地輪直徑較大，工作時不易發(fā)生打滑等現(xiàn)象，并且傳動可靠。 播種機(jī)工作時，拖拉機(jī)通過動力輸出軸將動力傳遞給行走輪，行走輪上的主動軸將動力傳遞給中間軸，行走輪隨拖拉機(jī)前進(jìn)而轉(zhuǎn)動，通過鏈條將動力傳給施肥、播種機(jī)構(gòu)，排出的化肥和種子經(jīng)輸肥管與輸種管進(jìn)入開溝器，先后進(jìn)入開好的地溝中，為了避免燒壞種薯，化肥應(yīng)位于種子下方5 cm 處，覆土器進(jìn)一步覆蓋種溝，鎮(zhèn)壓輪的圓錐滾筒隨即以均勻適當(dāng)?shù)膲毫好芊N床 7 研究過程(含完成期限) 第5周——查閱相關(guān)馬鈴薯播種機(jī)的設(shè)計資料，并進(jìn)行概述和文獻(xiàn)綜合。 第 6周——完成馬鈴薯播種機(jī)排種施肥機(jī)械傳動原理圖。 第7-9周——完成傳動部分的機(jī)械設(shè)計并繪制裝配圖。 第10-12周——完成鎮(zhèn)壓輪及行走輪的機(jī)械設(shè)計并繪制裝配圖和部分零件圖。 第13周——完成所有的圖紙并進(jìn)一步修改。 第14-15周——在以上基礎(chǔ)上完成畢業(yè)論文一篇。 第16周——翻譯一篇與論文相關(guān)的外文資料。 第17周——答辯。 指導(dǎo)教師意見 指導(dǎo)教師簽名： 年 月 日 教研室意見 教研室主任簽名： 年 月 日 院系意見 主管領(lǐng)導(dǎo)簽名： 年 月 日 畢 業(yè) 論 文 論文題目 學(xué) 院 專 業(yè) 年 級  姓 名 指導(dǎo)教師  職 稱  （200 年 月） 山西農(nóng)業(yè)大學(xué)教務(wù)處制 畢業(yè)論文（設(shè)計）指導(dǎo)教師評審標(biāo)準(zhǔn) 序號 評審項目 指 標(biāo) 滿分 1 工作量、工作態(tài)度 按期圓滿完成規(guī)定的任務(wù)，難易程度和工作量符合教學(xué)要求，體現(xiàn)本專業(yè)基本訓(xùn)練的內(nèi)容；工作認(rèn)真，遵守紀(jì)律；作風(fēng)嚴(yán)謹(jǐn)務(wù)實。 20 2 調(diào)查論證 能獨立查閱文獻(xiàn)和調(diào)研；能正確翻譯外文資料；能較好地作出開題報告；有綜合、收集和正確利用各種信息的能力。 15 3 設(shè)計、實驗方案 與實驗技能 設(shè)計、實驗方案科學(xué)合理，方案具體可行；能獨立操作實驗，數(shù)據(jù)采集、計算、處理正確；結(jié)構(gòu)設(shè)計合理、工藝可行、推導(dǎo)正確或程序運行可靠。 20 4 分析與解決 問題的能力 能運用所學(xué)知識和技能及獲取新知識去發(fā)現(xiàn)與解決實際問題；能對課題進(jìn)行理論分析，并得出有價值的結(jié)論 20 5 論文（設(shè)計）質(zhì)量 立論正確，論據(jù)充分，結(jié)論嚴(yán)謹(jǐn)合理；實驗正確，分析、處理問題科學(xué)；綜述簡練完整，結(jié)構(gòu)格式符合論文（設(shè)計）要求；文理通順，技術(shù)用語準(zhǔn)確，規(guī)范；圖表完備、制圖正確。 20 6 創(chuàng) 新 具有創(chuàng)新意識；對前人工作有改進(jìn)、突破、或有獨特見解，有一定應(yīng)用價值。 5 各教學(xué)單位可結(jié)合本專業(yè)特點和要求，制定相應(yīng)的評價標(biāo)準(zhǔn)。 11 畢業(yè)論文（設(shè)計）評閱人評審標(biāo)準(zhǔn) 序號 評審項目 指 標(biāo) 滿分 1 選 題 選題達(dá)到本專業(yè)教學(xué)基本要求，難易程度、工作量大小合適。 20 2 綜述材料 調(diào)查論證 根據(jù)課題任務(wù)，能獨立查閱文獻(xiàn)資料和從事有關(guān)調(diào)研。有綜合歸納、利用各種信息的能力，開題論證較充分。翻譯外文資料的水平較高。 15 3 設(shè)計、推導(dǎo)、 計算、論證 方案設(shè)計合理，具有可操作性；推導(dǎo)正確；計算準(zhǔn)確；結(jié)構(gòu)合理、工藝可行；圖樣繪制與技術(shù)要求符合國家標(biāo)準(zhǔn)及要求。 45 4 論文設(shè)計質(zhì)量 論點明確，論據(jù)充分，結(jié)論正確；條理清楚，文理通順，用語符合技術(shù)規(guī)范；圖表清楚，書寫格式規(guī)范。 15 5 創(chuàng) 新 對前人工作有改進(jìn)、突破、或有獨特見解；有一定應(yīng)用價值。 5 各教學(xué)單位可結(jié)合本專業(yè)特點和要求，制定相應(yīng)的評價標(biāo)準(zhǔn)。 畢業(yè)論文（設(shè)計）答辯評審標(biāo)準(zhǔn) 序號 評審項目 指 標(biāo) 滿分 1 報告內(nèi)容 思路清新；語言表達(dá)準(zhǔn)確，概念清楚，論點正確；實驗方法科學(xué)，分析歸納合理；結(jié)論嚴(yán)謹(jǐn)，論文（設(shè)計）有應(yīng)用價值。 40 2 報告過程 準(zhǔn)備工作充分, 具備必要的報告影像資料；報告在規(guī)定的時間內(nèi)作完。 10 3 答 辯 回答問題有理論依據(jù)，基本概念清楚。主要問題回答簡明準(zhǔn)確。 45 4 創(chuàng) 新 對前人工作有改進(jìn)或突破，或有獨特見解。 5 各教學(xué)單位可結(jié)合本專業(yè)特點和要求，制定相應(yīng)的評價標(biāo)準(zhǔn)。 山 西 農(nóng) 業(yè) 大 學(xué) 畢業(yè)論文（設(shè)計）成績單 院系 專業(yè) 入學(xué)時間 學(xué)號 學(xué)生姓名 班級 周數(shù) 起止日期 指導(dǎo)教師 職稱 論文（設(shè)計）題目 指 導(dǎo) 教 師 評 語 建議成績 指導(dǎo)教師簽名 年 月 日 評 閱 人 評 語 建議成績 評閱人簽名 年 月 日 答辯與評分 綜合成績 答辯小組 負(fù)責(zé)人簽名 年 月 日 本成績單一式二份，一份裝訂在畢業(yè)論文（設(shè)計）中，一份入學(xué)生學(xué)籍檔案。 優(yōu)秀畢業(yè)論文（設(shè)計）推薦表 論文題目 　 學(xué)生姓名 　 學(xué) 號 　 專 業(yè) 　 學(xué) 院 　 　指導(dǎo)教師 　 審稿說明： 1.對論文內(nèi)容、論文質(zhì)量、學(xué)術(shù)水平（含文字、圖表、公式）的評價。 2.對論文具體說明推薦的理由。 3.推薦的論文稿件是否符合編寫規(guī)范要求。 推薦人意見： 推薦人簽字： 年 月 日 院長簽字： 年 月 日 14 山西農(nóng)業(yè)大學(xué)學(xué)士學(xué)位論文（設(shè)計）文獻(xiàn)綜述 馬鈴薯播種機(jī)具的現(xiàn)狀與發(fā)展 摘要：綜述了國內(nèi)外播種機(jī)的發(fā)展現(xiàn)狀，并通過對國內(nèi)外幾種典型播種機(jī)的各種參數(shù)進(jìn)行系統(tǒng)的對比并加以分析，從中發(fā)現(xiàn)國產(chǎn)播種機(jī)與國外播種機(jī)的差距，并在此基礎(chǔ)上去闡述我國播種機(jī)在研發(fā)和應(yīng)用上所存在問題并展望未來播種機(jī)的發(fā)展趨勢，同時明確馬鈴薯播種機(jī)的設(shè)計方向。 關(guān)鍵詞：播種機(jī)具 馬鈴薯 精量播種機(jī) 排種器 1. 馬鈴薯在我國的生產(chǎn)現(xiàn)狀 馬鈴薯是一種高蛋白農(nóng)作物，在我國得到大面積的栽種，盡管我國年產(chǎn)量早已躍居世界第一，然而和世界除非洲以外的其他國家和地區(qū)比起來，單產(chǎn)量卻很低，因此在提高單產(chǎn)的措施上除了提高機(jī)械化生產(chǎn)水平外，還應(yīng)該改進(jìn)馬鈴薯的種子質(zhì)量以及種植方式。 1.1我國馬鈴薯的生產(chǎn)現(xiàn)狀 300多年前，原產(chǎn)自美洲的馬鈴薯被引進(jìn)中國并且逐漸成為僅次于小麥、水稻和玉米的第四大糧食作物。目前，我國的馬鈴薯無論是種植面積還是總產(chǎn)量都處于全球領(lǐng)先地位。從中國馬鈴薯網(wǎng)上獲得的資訊：2007年我國馬鈴薯種植面積約8000萬畝，預(yù)計總產(chǎn)量將超過6800萬噸，占世界總產(chǎn)量的22%左右。單從總產(chǎn)量來說我國已經(jīng)是世界第一，但是單產(chǎn)量卻遠(yuǎn)遠(yuǎn)低于歐美、澳洲的水平。例如，2003年，我國馬鈴薯的單產(chǎn)量是每公頃14842公斤，低于世界平均水平的每公頃16448 公斤，還不到單產(chǎn)量最大的國家新西蘭的每公頃44248 公斤的三分之一。 1.2國外馬鈴薯的生產(chǎn)水平 單產(chǎn)量排名前六位的國家：新西蘭、比利時、丹麥、美國、英國、荷蘭等歐美發(fā)達(dá)國家，他們的單產(chǎn)量都超過了每公頃40000 公斤（中國馬鈴薯網(wǎng)，2007）。除了地域、氣候方面外，更重要的是栽培技術(shù)以及機(jī)械化生產(chǎn)水平的影響。顯然，這些國家的農(nóng)業(yè)生產(chǎn)機(jī)械化水平都遠(yuǎn)遠(yuǎn)高過我國。反觀我國，大部分地區(qū)的馬鈴薯生產(chǎn)都還停留在人工或者半機(jī)械化生產(chǎn)的水平上，因此單產(chǎn)量低也就不足為奇。 1.3目前急需解決的措施以及會遇到的困難 要想提高單產(chǎn)量，首要的就是提高機(jī)械化生產(chǎn)水平。我國地域廣闊，擁有多種地型，因此不可能同時提高生產(chǎn)機(jī)械化，所以應(yīng)該根據(jù)不同的地形，不同的氣候和種植方式，從而設(shè)計符合當(dāng)?shù)氐霓r(nóng)業(yè)生產(chǎn)機(jī)械，盡量推廣播種機(jī)在農(nóng)業(yè)生產(chǎn)中的應(yīng)用。其次應(yīng)該改進(jìn)種植方式，我國的馬鈴薯種植方式一直停留在傳統(tǒng)種植的水平上，這是急需改變的。先進(jìn)的種植方式應(yīng)該從改進(jìn)種子質(zhì)量，改進(jìn)播種方式等方面進(jìn)行，同時在此基礎(chǔ)上設(shè)計相應(yīng)的機(jī)械也就顯得至關(guān)重要。 2. 國內(nèi)外播種機(jī)發(fā)展及應(yīng)用的現(xiàn)狀 2.1我國播種機(jī)發(fā)展現(xiàn)狀 現(xiàn)目前，我國大約有500家播種機(jī)生產(chǎn)企業(yè)，但是這些企業(yè)中能夠生產(chǎn)與大中型拖拉機(jī)配套的播種機(jī)的企業(yè)只有西安農(nóng)業(yè)機(jī)械廠、石家莊市農(nóng)業(yè)機(jī)械廠等區(qū)區(qū)10多家，其余的企業(yè)生產(chǎn)的都是與小型拖拉機(jī)和畜力配套的拖拉機(jī)。這種與小型拖拉機(jī)和畜力配套的播種機(jī)機(jī)的產(chǎn)量占全國播種機(jī)總產(chǎn)量的90%以上（國委文，2007）。由此可以看出當(dāng)前我國已實現(xiàn)機(jī)械化播種的大部分地區(qū)的播種機(jī)仍以小型播種機(jī)進(jìn)行傳統(tǒng)的谷物條播為主，大中型播種機(jī)的發(fā)展遠(yuǎn)遠(yuǎn)跟不上農(nóng)業(yè)生產(chǎn)的需要，而且大中型生產(chǎn)機(jī)械（包括播種機(jī)）的研制和生產(chǎn)水平也遠(yuǎn)遠(yuǎn)落后于發(fā)達(dá)國家的水平。 2.2國外播種機(jī)發(fā)展現(xiàn)狀 相對我國而言，國外許多發(fā)達(dá)國家在第二次世界大戰(zhàn)前后，先后完成了由傳統(tǒng)農(nóng)業(yè)向現(xiàn)代農(nóng)業(yè)的過度和轉(zhuǎn)化，經(jīng)過幾十年的發(fā)展，其農(nóng)業(yè)機(jī)械化水平已經(jīng)相當(dāng)完善，現(xiàn)在正朝著大型化、智能化、精量化以及多功能聯(lián)合型方向發(fā)展（陶衛(wèi)民，2001）。美國，德國，英國等西方發(fā)達(dá)國家的發(fā)展水平已經(jīng)走在世界的前列。 在國外許多發(fā)達(dá)國家，精密播種機(jī)經(jīng)過幾十年的發(fā)展和應(yīng)用，其技術(shù)水平應(yīng)經(jīng)達(dá)到了相當(dāng)完善的程度，無論是工作速度、生產(chǎn)效率、工作性能、播種質(zhì)量以及播種機(jī)具的通用性和適應(yīng)性上都做得比較好。這對減少播種過程中的漏種率、種子損傷率和提高單產(chǎn)量都有很大的促進(jìn)作用?，F(xiàn)在一些發(fā)達(dá)國家正把不斷更新播種機(jī)的工作原理、盡量完善其結(jié)構(gòu)、延長機(jī)具使用壽命、降低制造價格和維護(hù)費用的同時提高其工作效率以及提高播種機(jī)的通用性和適應(yīng)性作為未來更先進(jìn)的播種機(jī)研制的發(fā)展方向。 2.3與國外播種機(jī)相比，我國播種機(jī)存在的不足 和國外如美國、德國、英國等發(fā)達(dá)國家的播種機(jī)比起來，我國的播種機(jī)工作效率低，工作幅寬小，通用性和適應(yīng)性低，使用可靠性不高，生產(chǎn)率也遠(yuǎn)較國外的低。另外，由于我國工業(yè)起步晚，因此在新技術(shù)的研制和在播種機(jī)上的應(yīng)用上依舊落后于國外發(fā)達(dá)國家。下面以我國幾種典型的播種機(jī)和國外的播種機(jī)作一個對比，以便從中發(fā)現(xiàn)我國播種機(jī)和國外先進(jìn)播種機(jī)的不足。 首先，從工作效率方面來看，我國播種機(jī)的工作速度低。國外播種機(jī)的工作速度大都要求達(dá)到15㎞／h，有的甚至達(dá)到20㎞／h，受到土地，氣候和一些其它因素的影響，工作速度大多采用8～12㎞／h，而我國工作速度大約為4～7㎞／h，一般工作速度為5～6㎞／h。比如德國早期生產(chǎn)的GL34T和GL36T兩種機(jī)型的工作速度為7.5㎞／h(韓文鋒等，2006），而我國普遍采用的2BM-2以及2BMF-2型都達(dá)不到德國這兩種機(jī)型的水平。 其次，我國播種機(jī)的工作幅寬小。和國外發(fā)達(dá)國家比起來這個環(huán)節(jié)顯得非常薄弱。例如西歐一些國家的生產(chǎn)的播種機(jī)的工作幅寬一般為5～6m，美國，加拿大等國家的現(xiàn)用機(jī)型大多可以達(dá)到10～15m（陳興田，1999）。而我國所使用的播種機(jī)的工作幅寬絕大多數(shù)低于3.5m，例如較先進(jìn)的2BF-24A谷物條播機(jī)的工作幅寬為3.6m，其余的大都低于這個水平，工作幅寬低這個瓶頸在很大程度上限制了播種機(jī)的工作效率。 再次，排種器的排種效率低。我國很多使用播種機(jī)的地區(qū)在農(nóng)業(yè)生產(chǎn)中依舊使用傳統(tǒng)的排種方式即“一器一行”，一個排種器只能播一行種子，顯然這樣的效率是非常低的，即使有較先進(jìn)的“一器多行”的排種器，但是技術(shù)上也表現(xiàn)得不夠成熟，也沒能進(jìn)行大規(guī)模的推廣及應(yīng)用。國外發(fā)達(dá)國家在這方面的技術(shù)和經(jīng)驗就比我國先進(jìn)得多，而且許多新技術(shù)已經(jīng)得到廣泛的應(yīng)用，許多核心部件尤其是排種器無論是結(jié)構(gòu)還是工作原理都還有很多值得我國學(xué)習(xí)和借鑒的地方。 最后，我國的播種機(jī)的通用性和適應(yīng)性和國外發(fā)達(dá)國家比起來也還有很大的差距。在通用性方面，國外發(fā)展得比較早，技術(shù)也比較成熟，一套設(shè)備只需經(jīng)過簡單的更換即可實現(xiàn)不同種子的播種，而我國大部分播種機(jī)還都是“一機(jī)一種”，一種播種機(jī)只能夠播撒一種種子，這樣既浪費制造材料，又沒能使播種機(jī)得到充分利用。另外，我國地域遼闊，不同的土壤條件和氣候條件嚴(yán)重限制了播種機(jī)的適應(yīng)性，在保證適應(yīng)性方面的技術(shù)還很落后，而且我國研制生產(chǎn)的播種機(jī)很少考慮到適應(yīng)性這一方面的影響。 3. 我國播種機(jī)的發(fā)展趨勢 雖然可以通過引進(jìn)國外先進(jìn)的播種機(jī)可以暫時彌補(bǔ)我國播種機(jī)的不足之處，但是從長遠(yuǎn) 出發(fā)，我國必須走自主研發(fā)的道路，通過不斷吸收國外先進(jìn)技術(shù)的同時再結(jié)合我國的國情走出一條自主創(chuàng)新的路子，研制出具有我國特色的先進(jìn)播種機(jī)。 3.1加大大中型播種機(jī)的研制和開發(fā) 要想盡快縮小我國馬鈴薯等農(nóng)作物的單產(chǎn)與國外水平的差距，大中型播種機(jī)將起到至 關(guān)重要的作用。我國的幾大平原地勢平坦，比較適合大中型播種機(jī)的推廣和應(yīng)用。大中型播種機(jī)械除了可以節(jié)約人力，提高工作效率外還能減少種子的損傷率和漏種率，而且大中型播種機(jī)都是朝著聯(lián)合作業(yè)和直接播種技術(shù)的方向發(fā)展，這種機(jī)械的優(yōu)點在于：一次可以完成多項作業(yè)，作業(yè)效率高；保證及時播種，提高產(chǎn)量；節(jié)約能源，降低成本。 3.2采用新的排種原理和排種裝置 排種裝置是播種機(jī)最關(guān)鍵的部件，先進(jìn)的排種器和排種原理對播種機(jī)的效率的提高有 著很重要的作用，迄今為止，我國學(xué)者幾乎涉獵了世界上所有的排種器：如外槽輪式排種器、離心式排種器、各種圓盤式排種器等，而具有我國獨創(chuàng)特色的窩眼輪式排種器、紋盤式排種器、錐盤式精量排種器也獲得了廣泛的應(yīng)用，但是在馬鈴薯播種機(jī)上，先進(jìn)的排種器和排種方式依然制約播種機(jī)效率的一個瓶頸。因此在已經(jīng)解決種子和播種方式的情況下研制相應(yīng)的播種機(jī)顯得是關(guān)重要。顯然，在排種器方面，我國應(yīng)該朝著氣流輸送式條播排種器、孔帶式精密排種器、氣力式精密排種器以及傾斜圓盤指夾式排種器的方向發(fā)展。新的排種原理包括氣力式排種原理和機(jī)械式排種原理也應(yīng)得到廣泛的采用（陳興田，1999）。 4. 小結(jié) 一個比較先進(jìn)的播種機(jī)主要取決于其幾個關(guān)鍵的部件，如：開溝器、仿形機(jī)構(gòu)、覆土器以及排種器。尤其是排種器在整個播種機(jī)結(jié)構(gòu)中顯得尤為重要，排種器的好壞直接關(guān)系到播種機(jī)的播種效率，因此，現(xiàn)在國內(nèi)外播種機(jī)研制的重點依舊是放在排種器的研制上。我國在這方面也有不少的研究，尤其在氣吸式排種器，窩眼式排種器還有氣力式排種器的研究上有了一定的突破，但是和國外先進(jìn)水平還有一定的差距，因此，我國還必須加大研制的力度。 新型馬鈴薯已經(jīng)研制成功并將實現(xiàn)大力推廣，在將來的幾年內(nèi)，相應(yīng)的馬鈴薯播種機(jī)將對這種新型馬鈴薯的推廣起到極大的推動作用。新型的馬鈴薯將徹底改變傳統(tǒng)的馬鈴薯塊莖式播種方式，其播種方式將和玉米，油菜籽等顆粒的播種方式更為相似，但還是存在很多不同的地方，因此不能直接選用像玉米播種機(jī)或者油菜籽播種機(jī)這些現(xiàn)成的播種機(jī)型。由于現(xiàn)目前新型馬鈴薯還沒有開始實現(xiàn)大面積推廣，相應(yīng)的馬鈴薯播種機(jī)具還是一片空白?；诖?，對現(xiàn)有的馬鈴薯播種機(jī)和其余各類顆粒式播種機(jī)進(jìn)行改進(jìn)優(yōu)化并在此基礎(chǔ)上設(shè)計一種適合新型馬鈴薯的機(jī)械式或者氣吸式播種機(jī)就成了當(dāng)前以及未來相當(dāng)一段時間內(nèi)播種機(jī)的研制方向，同時研制的重點也將放在馬鈴薯播種機(jī)的排種器的研制上。 參考文獻(xiàn)： [1] 李寶筏．農(nóng)業(yè)機(jī)械學(xué)．北京：中國農(nóng)業(yè)出版社， 2003 [2] 朱秉蘭．簡明農(nóng)機(jī)手冊．鄭州：河南科學(xué)技術(shù)出版社，2001 [3] 張波屏．編譯．播種機(jī)械設(shè)計原理．北京：機(jī)械工業(yè)出版社，1982 [4] 馮小靜．精少量播種機(jī)械使用與維修．鄭州：河南科學(xué)技術(shù)出版社，1998 [5] 馬大敏．王俊民，王秀．新型農(nóng)機(jī)具使用與維修．北京：高等教育出版社，1996 [6] 程興田．播種機(jī)械的現(xiàn)狀及發(fā)展前景．農(nóng)機(jī)與食品機(jī)械，1999，6：1～2 [7] 陶衛(wèi)民．國外農(nóng)業(yè)裝備發(fā)展趨勢．新農(nóng)村，2001，7：25 [8] 劉林生．英國農(nóng)業(yè)機(jī)械化與農(nóng)業(yè)現(xiàn)代化．湖南農(nóng)機(jī)，1999，2：25 [9] 姜宗昌．2BMF—2型馬鈴薯研制成功．農(nóng)業(yè)機(jī)械化與電氣化，2000，5：34 [10] 魯濱，薛理，閏洪山等．2BS—5型馬鈴薯播種機(jī)的研制，2004，6：33 [11] 幾種馬鈴薯播種、種植機(jī)械．www.potatoweb.cn ，2007 [12] 聶延輝 江濤．夾持式馬鈴薯播種機(jī)的探討，2007，2：41 [13] 周桂霞，張國慶 ，張義峰等．2CM一2型馬鈴薯播種機(jī)的設(shè)計．黑龍江八一農(nóng)墾大學(xué)報，2004，16（3）：53～56 [14] 趙滿全，趙有杰，竇衛(wèi)國等．2BM—9型免耕播種機(jī)關(guān)鍵部件的設(shè)計與研究．中國農(nóng)機(jī)化，2006，6： [15] 韓文鋒，王淑紅．徐長征．GL3 4T／3 6 T型馬鈴薯播種機(jī)簡介，2007， 1：41 [16] 馮小靜，劉俊峰，楊欣等．排種器排種均勻性分析與研究．河北農(nóng)業(yè)大學(xué)學(xué)報，2003， 1：14～16 [17] 趙滿全，竇衛(wèi)國，趙士杰，等．2BSL一2型馬鈴薯起壟播種機(jī)的研制．內(nèi)蒙古農(nóng)業(yè)學(xué)學(xué)報，2001， (3)：l02～l04 [18] 閏建英，樊文憲，馮占懷．馬鈴薯施肥播種機(jī)的實驗研究．農(nóng)機(jī)科技推廣，2004，4：34 [19] 王廣勝，王玉忠，樊文憲．2BXSM—IB型馬鈴薯施肥播種機(jī)的研究．農(nóng)機(jī)與食品機(jī)械 ，1999，(3)：l5～17． [20] 國委文．播種機(jī)的現(xiàn)狀及發(fā)展趨勢。農(nóng)業(yè)機(jī)械化與電氣化，2007，5：3～4 [21] KACHMAN S D．Acternative Measures of Accuracy in Plant Spacing for Planters Using Single Seed Metering．Translation of the ASAE，1995,38(2),pp.371～375 [22] E．U．Odigboh．a(chǎn)nd．C．O．Akubuo ．A two—row automatic cassava cuttings planter：Development、Design and Prototype construction．Journal of Agricultural Engineering Research，Volume 50，September—December．50(1991),pp.13—18． [23] Tao et al., 1995 Y. Tao, C.T. Morrow, P.H. Heinemann and H.J.S. Ill, Fourier based separation technique for shape grading of potatoes using machine vision, Transactions of the ASAE 38 (1995), pp. 949–957. [24] H． Buitenwerf，W．B．Hoogmoed，P．Lerink and J．Müller Assessment of the Behavior of Potato in a Cup—belt Planter．Biosystems Eigineering，95 (2006),35—41． [25]Siecska et al., 1986 J.B. Sieczka, E.E. Ewing and E.D. Markwardt, Potato planter performance and effects on non-uniform spacing, American Potato Journal 63 (1986), pp. 25–37 4 Biosystems Engineering (2006) 95(1), 3541doi:10.1016/j.biosystemseng.2006.06.007PMPower and MachineryAssessment of the Behaviour of Potatoes in a Cup-belt PlanterH. Buitenwerf1,2; W.B. Hoogmoed1; P. Lerink3; J. Mu ller1,41Farm Technology Group, Wageningen University, P.O Box. 17, 6700 AA Wageningen, The Netherlands;e-mail of corresponding author: willem.hoogmoedwur.nl2Krone GmbH, Heinrich-Krone Strasse 10, 48480 Spelle, Germany3IB-Lerink, Laan van Moerkerken 85, 3271AJ Mijnsheerenland, The Netherlands4Institute of Agricultural Engineering, University of Hohenheim, D-70593 Stuttgart, Germany(Received 27 May 2005; accepted in revised form 20 June 2006; published online 2 August 2006)The functioning of most potato planters is based on transport and placement of the seed potatoes by a cup-belt. The capacity of this process is rather low when planting accuracy has to stay at acceptable levels. Themain limitations are set by the speed of the cup-belt and the number and positioning of the cups. It washypothesised that the inaccuracy in planting distance, that is the deviation from uniform planting distances,mainly is created by the construction of the cup-belt planter.To determine the origin of the deviations in uniformity of placement of the potatoes a theoretical model wasbuilt. The model calculates the time interval between each successive potato touching the ground. Referring tothe results of the model, two hypotheses were posed, one with respect to the effect of belt speed, and one withrespect to the influence of potato shape. A planter unit was installed in a laboratory to test these twohypotheses. A high-speed camera was used to measure the time interval between each successive potato justbefore they reach the soil surface and to visualise the behaviour of the potato.The results showed that: (a) the higher the speed of the cup-belt, the more uniform is the deposition of thepotatoes; and (b) a more regular potato shape did not result in a higher planting accuracy.Major improvements can be achieved by reducing the opening time at the bottom of the duct and byimproving the design of the cups and its position relative to the duct. This will allow more room for changes inthe cup-belt speeds while keeping a high planting accuracy.r 2006 IAgrE. All rights reservedPublished by Elsevier Ltd1. IntroductionThe cup-belt planter (Fig. 1) is the most commonlyused machine to plant potatoes. The seed potatoes aretransferred from a hopper to the conveyor belt with cupssized to hold one tuber. This belt moves upwards to liftthe potatoes out of the hopper and turns over the uppersheave. At this point, the potatoes fall on the back of thenext cup and are confined in a sheet-metal duct. Atthe bottom, the belt turns over the roller, creating theopening for dropping the potato into a furrow in thesoil.Capacity and accuracy of plant spacing are the mainparameters of machine performance. High accuracy ofplant spacing results in high yield and a uniform sortingof the tubers at harvest (McPhee et al., 1996; Pavek &Thornton, 2003). Field measurements (unpublisheddata) of planting distance in The Netherlands revealeda coefficient of variation (CV) of around 20%. Earlierstudies in Canada and the USA showed even higher CVsof up to 69% (Misener, 1982; Entz & LaCroix, 1983;Sieczka et al., 1986), indicating that the accuracy is lowcompared to precision planters for beet or maize.Travelling speed and accuracy of planting show aninverse correlation. Therefore, the present cup-beltplanters are equipped with two parallel rows of cupsper belt instead of one. Doubling the cup row allowsdouble the travel speed without increasing the belt speedand thus, a higher capacity at the same accuracy isexpected.ARTICLE IN PRESS1537-5110/$32.0035r 2006 IAgrE. All rights reservedPublished by Elsevier LtdThe objective of this study was to investigate thereasons for the low accuracy of cup-belt planters and touse this knowledge to derive recommendations fordesign modifications, e.g. in belt speeds or shape andnumber of cups.For better understanding, a model was developed,describing the potato movement from the moment thepotato enters the duct up to the moment it touches theground. Thus, the behaviour of the potato at the bottomof the soil furrow was not taken into account. Asphysical properties strongly influence the efficiency ofagricultural equipment (Kutzbach, 1989), the shape ofthe potatoes was also considered in the model.Two null hypotheses were formulated: (1) the plantingaccuracy is not related to the speed of the cup-belt; and(2) the planting accuracy is not related to the dimensions(expressed by a shape factor) of the potatoes. Thehypotheses were tested both theoretically with the modeland empirically in the laboratory.2. Materials and methods2.1. Plant materialSeed potatoes of the cultivars (cv.) Sante, Arinda andMarfona have been used for testing the cup-belt planter,because they show different shape characteristics. Theshape of the potato tuber is an important characteristicfor handling and transporting. Many shape features,usually combined with size measurements, can bedistinguished (Du & Sun, 2004; Tao et al., 1995; Zo dler,1969). In the Netherlands grading of potatoes is mostlydone by using the square mesh size (Koning de et al.,1994), which is determined only by the width and height(largest and least breadth) of the potato. For thetransport processes inside the planter, the length of thepotato is a decisive factor as well.A shape factor S based on all three dimensions wasintroduced:S 100l2wh(1)where l is the length, w the width and h the height of thepotato in mm, with howol. As a reference, alsospherical golf balls (with about the same density aspotatoes), representing a shape factor S of 100 wereused. Shape characteristics of the potatoes used in thisstudy are given in Table 1.2.2. Mathematical model of the processA mathematical model was built to predict plantingaccuracy and planting capacity of the cup-belt planter.The model took into consideration radius and speed ofthe roller, the dimensions and spacing of the cups, theirpositioning with respect to the duct wall and the heightof the planter above the soil surface (Fig. 2). It wasassumed that the potatoes did not move relative to thecup or rotate during their downward movement.The field speed and cup-belt speed can be set toachieve the aimed plant spacing. The frequency fpotofpotatoes leaving the duct at the bottom is calculated asfpotvcxc(2)where vcis the cup-belt speed in ms?1and xcis thedistance in m between the cups on the belt. The angularspeed of the roller orin rad s?1with radius rrin m iscalculated asorvcrr(3)ARTICLE IN PRESS56789104321Fig. 1. Working components of the cup-belt planter: (1)potatoes in hopper; (2) cup-belt; (3) cup; (4) upper sheave;(5) duct; (6) potato on back of cup; (7) furrower; (8) roller;(9) release opening; (10) ground levelTable 1Shape characteristics of potato cultivars and golf balls used inthe experimentsCultivarSquare mesh size, mmShape factorSante2835146Arinda3545362Marfona3545168Golf balls42?8100H. BUITENWERF ET AL.36The gap in the duct has to be large enough for a potatoto pass and be released. This gap xreleasein m is reachedat a certain angle areleasein rad of a cup passing theroller. This release angle arelease(Fig. 2) is calculated ascos areleaserc xclear? xreleaserc(4)where: rcis the sum in m of the radius of the roller, thethickness of the belt and the length of the cup; and xclearis the clearance in m between the tip of the cup and thewall of the duct.When the parameters of the potatoes are known, theangle required for releasing a potato can be calculated.Apart from its shape and size, the position of the potatoon the back of the cup is determinative. Therefore, themodel distinguishes two positions: (a) minimum re-quired gap, equal to the height of a potato; and (b)maximum required gap equal to the length of a potato.The time treleasein s needed to form a release angle aois calculated astreleaseareleaseor(5)Calculating treleasefor different potatoes and possiblepositions on the cup yields the deviation from theaverage time interval between consecutive potatoes.Combined with the duration of the free fall and the fieldspeed of the planter, this gives the planting accuracy.When the potato is released, it falls towards the soilsurface. As each potato is released on a unique angularposition, it also has a unique height above the soilsurface at that moment (Fig. 2). A small potato will bereleased earlier and thus at a higher point than a largeone.The model calculates the velocity of the potato justbefore it hits the soil surface uendin ms?1. The initialvertical velocity of the potato u0in m s?1is assumed toequal the vertical component of the track speed of thetip of the cup:v0 rcorcosarelease(6)The release height yreleasein m is calculated asyrelease yr? rcsinarelease(7)where yrin m is the distance between the centre of theroller (line A in Fig. 2) and the soil surface.The time of free fall tfallin s is calculated withyrelease vendtfall 0?5gt2fall(8)where g is the gravitational acceleration (9?8ms?2) andthe final velocity vendis calculated asvend v0 2gyrelease(9)with v0in ms?1being the vertical downward speed ofthe potato at the moment of release.The time for the potato to move from Line A to therelease point treleasehas to be added to tfall.The model calculates the time interval between twoconsecutive potatoes that may be positioned in differentways on the cups. The largest deviations in intervals willoccur when a potato positioned lengthwise is followedby one positioned heightwise, and vice versa.2.3. The laboratory arrangementA standard planter unit (Miedema Hassia SL 4(6)was modified by replacing part of the bottom end of thesheet metal duct with similarly shaped transparentacrylic material (Fig. 3). The cup-belt was driven viathe roller (8 in Fig. 1), by a variable speed electric motor.The speed was measured with an infrared revolutionmeter. Only one row of cups was observed in thisarrangement.A high-speed video camera (SpeedCam Pro, Wein-berger AG, Dietikon, Switzerland) was used to visualisethe behaviour of the potatoes in the transparent ductand to measure the time interval between consecutivepotatoes. A sheet with a coordinate system was placedbehind the opening of the duct, the X axis representingthe ground level. Time was registered when the midpointof a potato passed the ground line. Standard deviationARTICLE IN PRESSxclearrc?release?xreleaseLine ALine CFig. 2. Process simulated by model, simulation starting when thecup crosses line A; release time represents time needed to createan opening sufficiently large for a potato to pass; model alsocalculates time between release of the potato and the moment itreaches the soil surface (free fall); rc, sum of the radius of theroller, thickness of the belt and length of the cup; xclear,clearance between cup and duct wall; xrelease, release clearance;arelease, release angle ; o, angular speed of roller; line C, groundlevel, end of simulationASSESSMENT OF THE BEHAVIOUR OF POTATOES37of the time interval between consecutive potatoes wasused as measure for plant spacing accuracy.For the measurements the camera system was set to arecording rate of 1000 frames per second. With anaverage free fall velocity of 2?5ms?1, the potato movesapprox. 2?5mm between two frames, sufficiently smallto allow an accurate placement registration.The feeding rates for the test of the effect of the speedof the belt were set at 300, 400 and 500 potatoes min?1(fpot 5, 6?7 and 8?3s?1) corresponding to belt speedsof 0?33, 0?45 and 0?56ms?1. These speeds would betypical for belts with 3, 2 and 1 rows of cups,respectively. A fixed feeding rate of 400 potatoes min?1(cup-belt speed of 0?45ms?1) was used to assess theeffect of the potato shape.For the assessment of a normal distribution of thetime intervals, 30 potatoes in five repetitions were used.In the other tests, 20 potatoes in three repetitions wereused.2.4. Statistical analysisThe hypotheses were tested using the Fisher test, asanalysis showed that populations were normally dis-tributed. The one-sided upper tail Fisher test was usedand a was set to 5% representing the probability of atype 1 error, where a true null hypothesis is incorrectlyrejected. The confidence interval is equal to (100?a)%.3. Results and discussion3.1. Cup-belt speed3.1.1. Empirical resultsThe measured time intervals between consecutivepotatoes touching ground showed a normal distribution.Standard deviations s for feeding rates 300, 400 and 500potatoes min?1were 33?0, 20?5 and 12?7ms, respectively.ARTICLE IN PRESSFig. 3. Laboratory test-rig; lower rightpart of the bottom end of the sheet metal duct was replaced with transparent acrylic sheet;upper rightsegment faced by the high-speed cameraH. BUITENWERF ET AL.38According to the F-test the differences between feedingrates were significant. The normal distributions for allthree feeding rates are shown in Fig. 4. The accuracy ofthe planter is increasing with the cup-belt speed, withCVs of 8?6%, 7?1% and 5?5%, respectively.3.1.2. Results predicted by the modelFigure 5 shows the effect of the belt speed on the timeneeded to create a certain opening. A linear relationshipwas found between cup-belt speed and the accuracy ofthe deposition of the potatoes expressed as deviationfrom the time interval. The shorter the time needed forcreating the opening, the smaller the deviations. Resultsof these calculations are given in Table 2.The speed of the cup turning away from the duct wallis important. Instead of a higher belt speed, an increaseof the cups circumferential speed can be achieved bydecreasing the radius of the roller. The radius of theroller used in the test is 0?055m, typical for theseplanters. It was calculated what the radius of the rollerhad to be for lower belt speeds, in order to reach thesame circumferential speed of the tip of the cup as foundfor the highest belt speed. This resulted in a radius of0?025m for 300 potatoes min?1and of 0?041m for 400potatoes min?1. Compared to this outcome, a lineartrend line based on the results of the laboratorymeasurements predicts a maximum performance at aradius of around 0?020m.The mathematical model Eqn (5) predicted a linearrelationship between the radius of the roller (forr40?01m) and the accuracy of the deposition of thepotatoes. The model was used to estimate standarddeviations for different radii at a feeding rate of 300potatoes min?1. The results are given in Fig. 6, showingthat the model predicts a more gradual decrease inaccuracy in comparison with the measured data. Aradius of 0?025m, which is probably the smallest radiustechnically possible, should have given a decrease inARTICLE IN PRESS0.0350.030f (x)0.0250.0200.0150.0100.0050.000180260500340Time x, ms420500 pot min1400 pot min1300 pot min1Fig. 4. Normal distribution of the time interval (x, in ms) ofdeposition of the potatoes (pot) for three feeding rates806448Size of opening, mm321600.000.050.100.15Time, s0.200.250.36 m s10.72 m s10.24 m s1Fig. 5. Effect of belt speed on time needed to create openingTable 2Time intervals between consecutive potatoes calculated by themodel (cv. Marfona)Belt speed,m s?1Difference between shortest and longestinterval, s0?7217?60?3629?40?2442?835302520Standard deviation, ms1510500.000.020.04Radius lower roller, m0.060.08y = 262.21 x 15.497R2 = 0.9987y = 922.1 x 17.597R2 = 0.9995Fig. 6. Relationship between the radius of the roller and thestandard deviation of the time interval of deposition of thepotatoes; the relationship is linear for radii r40?01 m, K,measurement data; m, data from mathematical model; ,extended for ro0?01 m; , linear relationship; R2, coefficient ofdeterminationASSESSMENT OF THE BEHAVIOUR OF POTATOES39standard deviation of about 75% compared to theoriginal radius.3.2. Dimension and shape of the potatoesThe results of the laboratory tests are given in Table 3.It shows the standard deviations of the time interval at afixed feeding rate of 400 potatoes min?1. These resultswere contrary to the expectations that higher standarddeviations would be found with increasing shape factors.Especially the poor results of the balls were amazing.The standard deviation of the balls was about 50%higher than the oblong potatoes of cv. Arinda. Thenormal distribution of the time intervals is shown inFig. 7. Significant differences were found between theballs and the potatoes. No significant differences werefound between the two potato varieties.The poor performance of the balls was caused by thefact that these balls could be positioned in many wayson the back of the cup. Thus, different positions of theballs in adjacent cups resulted in a lower accuracy ofdeposition. The three-dimensional drawing of the cup-belt shows the shape of the gap between cup andduct illustrating that different opening sizes are possible(Fig. 8).Arinda tubers were deposited with a higher accuracythan Marfona tubers. Analysis of the recorded framesand the potatoes, demonstrated that the potatoes of cv.Arinda always were positioned with their longest axisparallel to the back of the cup. Thus, apart from theshape factor, a higher ratio width/height will cause agreater deviation. For cv. Arinda, this ratio was 1?09, forcv. Marfona it was 1?15.3.3. Model versus laboratory test-rigThe mathematical model predicted the performanceof the process under different circumstances. The modelsimulated a better performance for spherical ballscompared to potatoes whereas the laboratory testshowed the opposite. An additional laboratory testwas done to check the reliability of the model.In the model, the time interval between two potatoesis calculated. Starting point is the moment the potatocrosses line A and end point is the crossing of line C(Fig. 2). In the laboratory test-rig the time-intervalbetween potatoes moving from line A to C wasmeasured (Fig. 3). The length, width and height of eachpotato was measured and potatoes were numbered.During the measurement it was determined how eachpotato was positioned on the cup. This position and thepotato dimensions were used as input for the model. Themeasurements were done at a feeding rate of 400potatoes min?1with potatoes of cv. Arinda andMarfona. The standard deviations of the measured timeintervals are shown in Table 4. They were slightlydifferent (higher) from the standard deviations calcu-ARTICLE IN PRESS0.0500.0450.0400.0350.0300.0250.020f (x)0.0150.0100.000245255265275285Time x, ms2953053153253350.005Marfonashape factor 168Arindashape factor 362Golf ball (sphere)shape factor 100Fig. 7. Normal distribution of the time interval (x, in ms) ofdeposition of the potatoes for different shape factors at a fixedfeeding rateFig. 8. View from below to the cup at an angle of 45 degrees;position of the potato on the back of the cup is decisive for itsreleaseTable 3Effect of cultivars on the accuracy of plant spacing; CV,coefficient of variationCultivarStandard deviation, msCV, %Arinda8?603?0Marfona9?923?5Golf balls13?244?6H. BUITENWERF ET AL.40lated by the model. Explanations for these differencesare: (1) the model does not take into considerationsituations as shown in Fig. 8, (2) the passing moment atline A and C was disputable. Oblong potatoes such ascv. Arinda may fall with the tip or with the longest sizedown. This may cause up to 6 ms difference for thepotato to reach the bottom line C.4. ConclusionsThe mathematical model simulating the movement ofthe potatoes at the time of their release from the cup-beltwas a very useful tool leading to the hypotheses to betested and to design the laboratory test-rig.Both the model and the laboratory test showed thatthe higher the speed of the belt, the more uniform thedeposition of the potatoes at zero horizontal velocity.This was due to the fact that the opening, allowing thepotato to drop, is created quicker. This leaves less effectof shape of the potato and the positioning of the potatoon