茶葉烘干機設計（含5張CAD圖紙和說明書）

資源目錄里展示的全都有預覽可以查看的噢，，下載就有,,請放心下載，原稿可自行編輯修改=【QQ：11970985 可咨詢交流】====================喜歡就充值下載吧。。。資源目錄里展示的全都有，，下載后全都有,,請放心下載，原稿可自行編輯修改=【QQ：197216396 可咨詢交流】==================== XXX大學 本科畢業(yè)設計開題報告 題 目 茶葉烘干機設計 指 導 教 師 院（系、部） 專 業(yè) 班 級 學 號 姓 名 日 期 （一）選題的目的及意義： 茶樹為茶為常綠灌木，適應力極強。但欲求產(chǎn)量高、品質(zhì)好，除具有優(yōu)良的品種、精湛的采制技術(shù)外，還要具備優(yōu)越的氣候環(huán)境。一般亞熱帶及熱帶地區(qū)的氣候為宜；年降雨量1500毫米至2500毫米均適合。溫度以20～25℃生長最旺，海拔自數(shù)十米至2000米，表土深，土質(zhì)疏松，排水良好的砂質(zhì)土壤或砂質(zhì)黏土為佳。我國多數(shù)茶區(qū)通常都種植在南方或者氣候較為濕潤的地區(qū)。例如秦嶺以南的茶區(qū)，因其受季風影響，都無特別干燥期，雨量在1500～3000毫米，祁門茶區(qū)雨量在1700～1900毫米，相對濕度70%～90%，武夷茶區(qū)1900毫米、濕度80%，分布極為均勻。通過茶樹生長的環(huán)境來看，茶葉產(chǎn)地一般都是氣候較為濕潤的地區(qū)，因此對于茶葉采摘后進行及時干燥處理是十分必要的。本文主要旨在設計一種適合茶葉干燥的滾筒式茶葉干燥機，來及時對茶葉進行烘干作業(yè)，以此來減少茶農(nóng)因為氣候原因?qū)е碌牟枞~不能及時干燥所造成的經(jīng)濟損失。 茶葉因為含可以增進人體健康的兒茶素、膽甾烯酮、咖啡堿、肌醇、葉酸、泛酸等成分而被譽為世界三大飲料之一。茶葉始于中國，作為茶葉的故鄉(xiāng)，我國的茶區(qū)主要分布在西南、華南、江南等氣候溫暖濕潤降水充足的區(qū)域。一般茶葉的收獲季節(jié)正值江南的梅雨季節(jié)，這將導致農(nóng)民在收獲后無法干燥使得茶葉發(fā)霉變質(zhì)，這嚴重影響了茶農(nóng)的經(jīng)濟收入，而作為主要的茶葉出口國，這也會對國家經(jīng)濟帶來較大的損失。同時如果這些發(fā)霉了的茶葉流通到市場，勢必也會影響人們的身體健康。因此茶葉烘干機械對于茶葉生產(chǎn)行業(yè)是具有十分重要的意義的。 （二）研究現(xiàn)狀： 茶葉烘干作為影響茶葉品質(zhì)最為重要的因素之一，其工藝性和操作得到了不斷的改進。從原始的手工操作到現(xiàn)在的自動操作，從傳統(tǒng)的熱風干燥到現(xiàn)在的輻射干燥，使這些茶業(yè)的生產(chǎn)效率和品質(zhì)得到了不斷的提高。茶葉烘干機從原始的抽屜式烘干箱，發(fā)展到現(xiàn)在的自動鏈式烘干機，已有多種類型，按照自動化的程度可以分為手動、半自動和自動；按照烘干機的方式可以分為熱風干燥、金屬傳到干燥和輻射干燥等幾種類型。目前中國較為廣泛應用的是自動鏈式茶葉烘干機，與早期的手工茶葉烘干機相比有了很大的改進和優(yōu)點，提高了茶葉的生產(chǎn)效 立手臂、支撐桿、擺動液壓缸、支承工作臺、氣缸、噴槍等部分組成，它的主要功能是配合液壓控制系統(tǒng)完成產(chǎn)品表面的噴漆工作。 一、選題的目的、意義和研究現(xiàn)狀 率和品質(zhì)，對于茶葉行業(yè)的發(fā)展起到了重要的作用。但是該類機型從發(fā)明至今，改進的地方不多，但其基本結(jié)構(gòu)還是20世紀80年代仿照國外樣機制造的，性能和標準也還基本停留在20世紀80年代水平上。 二、研究方案及預期結(jié)果 擬采用方法及手段： 加熱裝置采用熱風加熱方式，具體是在風機前安裝電加熱爐，通過電加熱爐將風加熱，后對桶內(nèi)進行熱風烘干。這樣就避免了茶葉炒焦的現(xiàn)象，同時風的吹動也能夠使得桶內(nèi)的茶葉在拋揚過程中均勻受熱。筒體內(nèi)部用鋼板做成的揚料板取代螺旋槽結(jié)構(gòu)，降低加工難度。主要由風機、變頻器、加熱器、滾筒、滾圈、托輪、電機、減速機構(gòu)、傳動軸、支座等組成。 設計任務： （1）設計總體方案設計，確定總體方案和各部分單元的方案； （2）滾筒整體、滾筒內(nèi)部、電機型號、支撐輪、和其他的傳動軸、支座、傳動裝置等部件設計； （3）零件的三維建模及其裝配等； 主要解決的問題： 第一，減少茶葉的浪費； 第二，在烘干過程中茶葉均勻受熱； 第三，提高生產(chǎn)效率； 第四，減少生產(chǎn)成本。 預期結(jié)果： 在以前的學習中，學習了很多的專業(yè)知識，基本上掌握了制定工藝的方法要點和機器的設計要點，大四上學期進行的專業(yè)方向綜合課程的學習，為這次的課題奠定了一定的基礎(chǔ)，做課題時用到的參考書也了解了都有哪些，對茶葉烘干機通過在網(wǎng)上、圖書館查閱資料也有了一定的認識，對國內(nèi)外先進的方法和新的設計也有了一些了解，這為以后的設計打下了基礎(chǔ)，不會盲目的去做，而且為此也去專門學習了三維建模軟件，受益頗深。 三、研究進度 第三到四周:利用學校圖書館和網(wǎng)絡資源，查閱資料，收集相關(guān)文獻； 第五到六周：撰寫文獻綜述和開題報告，進行方案論證與方案設計，與指導教師討論方案的可行性，請導師提出意見，準備開題報告； 第七到八周：原理方案設計以及機械結(jié)構(gòu)設計計算； 第九到十周：機械結(jié)構(gòu)設計并繪圖； 第十一到十二周：零件的三維建模； 第十三到十四周：各部分三維建模及其裝配； 第十五周：整理論文等文字資料；上交，準備畢業(yè)設計答辯。 四、主要參考文獻 [1]成大先，王德夫.機械設計手冊5版（1~4卷）[M].北京：化學工業(yè)出版社，2007.11 [2]濮良貴，紀名剛.機械設計[M].北京：高等教育出版社，2005 [3]萬鳳嶺， 謝蘇江， 周昭軍． 干燥設備的現(xiàn)狀及發(fā)展趨勢［J］．化工裝備技術(shù)， 2006 [4]潘永康，王喜忠，劉相東． 現(xiàn)代干燥技術(shù)( 2 版) ［M］． 北京: 化學工業(yè)出版社， 2007 [5]王繼煥． 稻谷和油菜籽烘干特性研究［J］． 糧食儲藏， 2002 [6]郭載德．《茶葉初制機械講座》第八講茶葉烘干機［Ｊ］．茶葉，1989 [7]王繼煥.稻谷和油菜籽烘干特性研究[J].糧食儲藏,2003 [8]劉相臣.國內(nèi)外干燥設備的現(xiàn)狀及發(fā)展趨勢[J].化工裝備技術(shù),2000 [9]Da-Wen Sun, Byrne C. Selection of EMC/ERH Isotherm Equations for Rapeseed[J].J.agri.Engng Res. 1998 [10]王喜忠,蕭成基.近三十年來我國干燥技術(shù)的發(fā)展概況[J].干燥技術(shù)與設備,2005,3 [11]楊娜偉.竹筍微波、薄層及其聯(lián)合干燥對比試驗的研究[D].西南大學,2010 [12]謝艷群,蔣蘋,孫松林等.小型可移動式油菜籽烘干機探討[J].湖南農(nóng)機,2010 [13]劉木華,鄭華東,嚴霖元,揭琳鋒.小型可移動式循環(huán)干燥機的試驗研究[J].中國農(nóng)機化,2005,2 [14]Le Van Ban, Bui Naoc Hung , and PhanHieu Hien. A Low -cost I n- store Grain Dryer for Small Farmers. Grain Drying in Asia, ACIAR Proceedings No. [15]李占勇,小林敬幸.日本干燥技術(shù)的最新進展[J].干燥技術(shù)與裝備,2006,4 [16]李國 .連續(xù)式糧食干燥智能控制技術(shù)研究[D].中國農(nóng)業(yè)大學,2006, 5 [17]Seraji H. A new class of nonlinear PID controllers with robotic applications. Journal of Robotic Systems, 1998 五、指導教師意見 指導教師簽字： 附錄A 注塑模具自動裝配造型 X. G. Ye, J. Y. H. Fuh and K. S. Lee (機械和生產(chǎn)工程部，新加坡國立大學，新加坡) 注射模是一種由與塑料制品有關(guān)的和與制品無關(guān)的零部件兩大部分組成的機械裝置。本文提出了（有關(guān)）注射模裝配造型的兩個主要觀點，即描述了在計算機上進行注射模裝配以及確定裝配中與制品無關(guān)的零部件的方向和位置的方法，提出了一個基于特征和面向?qū)ο蟮谋磉_式以描述注射模等級裝配關(guān)系，該論述要求并允許設計者除了考慮零部件的外觀形狀和位置外，還要明確知道什么部份最重要和為什么。因此，它為設計者進行裝配設計（DFA）提供了一個機會。同樣地，為了根據(jù)裝配狀態(tài)推斷出裝配體中裝配對象的結(jié)構(gòu)，一種簡化的特征幾何學方法也誕生了。在提出的表達式和簡化特征幾何學的基礎(chǔ)上，進一步深入探討了自動裝配造型的方法。 關(guān)鍵字：裝配造型；基于特征；注射模；面向?qū)ο蟆? 1、簡介 注射成型是生產(chǎn)塑料模具產(chǎn)品最重要的工藝。需要用到的兩種裝備是：注射成型機和注射模?，F(xiàn)在常用的注射成型機即所謂的通用機，在一定尺寸范圍內(nèi)，可以用于不同形狀的各種塑料模型中，但注射模的設計就必須隨塑料制品的變化而變化。模型的幾何因素不同，它們的構(gòu)造也就不同。注射模的主要任務是把塑料熔體制成塑料制品的最終形狀，這個過程是由型芯、型腔、鑲件、滑塊等與塑料制品有關(guān)的零部件完成的，它們是直接構(gòu)成塑料件形狀及尺寸的各種零件，因此，這些零件稱為成型零件。（在下文，制品指塑料模具制品，部件指注射模的零部件。）除了注射成型外，注射模還必須完成分配熔體、冷卻，開模，傳輸、引導運動等任務，而完成這些任務的注射模組件在結(jié)構(gòu)和形狀上往往都是相似的，它們的結(jié)構(gòu)和形狀并不取決于塑料模具，而是取決于塑料制品。顯示了注射模的結(jié)構(gòu)組成。 成型零件的設計從塑料制品中分離了出來。近幾年，CAD/CAM技術(shù)已經(jīng)成功的應用到成型零件的設計上。成型零件的形狀的自動化生成也引起了很多研究者的興趣，不過很少有人在其上付諸實踐，雖然它也象結(jié)構(gòu)零件一樣重要?，F(xiàn)在，模具工業(yè)在應用計算機輔助設計系統(tǒng)設計成型零件和注射成型機時，遇到了兩個主要困難。第一，在一個模具裝置中，通常都包括有一百多個成型零部件，而這些零部件又相互聯(lián)系，相互限制。對于設計者來說，確定好這些零部件的正確位置是很費時間的。第二，在很多時候，模具設計者已想象出工件的真實形狀，例如螺絲，轉(zhuǎn)盤和銷釘，但是CAD系統(tǒng)只能用于另一種信息的操作。這就需要設計者將他們的想法轉(zhuǎn)化成CAD系統(tǒng)能接受的信息(例如線，面或者實體等)。因此，為了解決這兩個問題，很有必要發(fā)展一種用于注射模的自動裝配成型系統(tǒng)。在此篇文章里，主要講述了兩個觀點：即成型零部件和模具在計算機上的防真裝配以及確定零部件在模具中的結(jié)構(gòu)和位置。 這篇文章概括了關(guān)于注塑成型的相關(guān)研究，并對注射成型機有一個完整的闡述。通過舉例一個注射模的自動裝配造型，提出一種簡化的幾何學符號法，用于確定注射模具零部件的結(jié)構(gòu)和位置。 2、相關(guān)研究 在各種領(lǐng)域的研究中，裝配造型已成為一門學科，就像運動學、人工智能學、模擬幾何學一樣。Libardi作了一個關(guān)于裝配造型的調(diào)查。據(jù)稱，很多研究人員已經(jīng)開始用圖表分析模型會議拓撲。在這個圖里，各個元件由節(jié)點組成的，再將這些點依次連接成線段。然而這些變化矩陣并沒有緊緊的連在一起，這將嚴重影響整體的結(jié)構(gòu)，即，當其中某一部分移動了，其他部分并不能做出相應的移動。Lee and Gossard開發(fā)了一種新的系統(tǒng)，支持包含更多的關(guān)于零部件的基本信息的一種分級的裝配數(shù)據(jù)結(jié)構(gòu)，就像在各元件間的“裝配特征”。變化矩陣自動從實際的線段間的聯(lián)系得到，但是這個分級的拓撲模型只能有效地代表“部分”的關(guān)系。 自動判別裝配組件的結(jié)構(gòu)意味著設計者可避免直接指定變化的矩陣，而且，當它的參考零部件的尺寸和位置被修改的時候，它的位置也將隨之改變?，F(xiàn)在有三種技術(shù)可以推斷組件在模具中的位置和結(jié)構(gòu)：反復數(shù)值技術(shù),象征代數(shù)學技術(shù)，以及象征幾何學技術(shù)。Lee and Gossard提出一項從空間關(guān)系計算每個組成元件的位置和方向的反復數(shù)值技術(shù)。他們的理論由三步組成：產(chǎn)生條件方程式，降低方程式數(shù)量，解答方程式。方程式有：16個滿足未知條件的方程式，18個滿足已知條件的方程式，6個滿足各個矩陣的方程式以及另外的兩個滿足旋轉(zhuǎn)元件的方程式。通常方程式的數(shù)量超過變量的數(shù)量時，應該想辦法去除多余的方程式。牛頓迭代法常用來解決這種方程式。不過這種方法存在兩種缺點：第一，它太依賴初始解；第二：反復的數(shù)值技術(shù)在解決空間內(nèi)不能分清不同的根。因此，在一個完全的空間關(guān)系問題上，有可能解出來的結(jié)果在數(shù)學理論上有效，但實際上卻是行不通的。 Ambler和Popplestone提議分別計算每個零部件的旋轉(zhuǎn)量和轉(zhuǎn)變量以確定它們之間的空間關(guān)系，而解出的每個零部件的6個變量(3個轉(zhuǎn)變量和3旋轉(zhuǎn)量)要和它們的空間關(guān)系一致。這種方法要求大量的編程和計算，才能用可解的形式重寫有關(guān)的方程式。此外，它不能保證每次都能求出結(jié)果，特別是當方程式不能被以可解答的形式重寫時。 為了能確定出滿足一套幾何學限制條件的剛體的位置與方向，Kramer開發(fā)了一種特征幾何學方法。通過產(chǎn)生一連串滿足逐漸增長的限制條件的動作推斷其幾何特征，這樣將減少物體的自由度數(shù)。Kramer使用的基本參考實體稱為一個"標識"，由一個點和兩正交軸構(gòu)成。標識間的7個限制條件（coincident, in-line, in-plane, parallelFz,offsetFz, offsetFx and helical)都被定了義。對于一個包括獨立元件、相互約束的標識和不變的標識的問題來說，可以用動作分析法來解決問題，它將一步一步地最后求出物體的最終的幾何構(gòu)造。在確定物體構(gòu)造的每一個階段，自由度分析將決定什么動作能提供滿足限制物體未加限制部位的自由度。然后計算該動作怎樣能進一步降低物體的自由度數(shù)。在每個階段的最后，給隱喻的裝配計劃加上合適的一步。根據(jù)Shah和Rogers的分析，Kramer的理論代表了注射模具最顯著的發(fā)展，他的特征幾何學方法能解出全部的限制條件。和反復的數(shù)值技術(shù)相比，他的這種方法更具吸引力。不過要實行這種方法，需要大量的編程。 現(xiàn)在雖然已有很多研究者開始研究注射成型機，但仍很少有學者將注意力放在注射模設計上。Kruth開發(fā)了一個注射模的設計支援系統(tǒng)。這個系統(tǒng)通過高級的模具對象(零部件和特征)支持注射模的成型設計。因為系統(tǒng)是在AUTOCAD的基礎(chǔ)上設計的，因此它只適于線和簡單的實體模型操作。 3、注射模裝配概述 主要講述了關(guān)于注射模自動裝配造型的兩個方面：注射模在電腦上的防真裝配和確定結(jié)構(gòu)零件在裝配中的位置和方向。在這個部分，我們基于特征和面向?qū)ο笳撌隽俗⑸淠Ｑb配。 注射模在電腦上的防真裝配包含著注射模零部件在結(jié)構(gòu)上和空間上的聯(lián)系。這種防真必須支持所有給定零部件的裝配、在相互關(guān)聯(lián)的零部件間進行變動以及整體上的操作。而且防真裝配也必須滿足設計者的下列要求： 支持能表達出模具設計者實體造型想象的高級對象。 2）成型防真應該有象現(xiàn)實一樣的操作功能，就如裝入和干擾檢查。 為了滿足這些要求，可用一個基于特征和面向?qū)ο蟮姆旨壞Ｐ蛠泶孀⑸淠?。這樣便將模型分成許多部分，反過來由多段模型和獨立部分組成。因此，一個分級的模型最適合于描述各組成部分之間的結(jié)構(gòu)關(guān)系。一級表明一個裝配順序，另外，一個分級的模型還能說明一個部分相對于另一個部分的確定位置。 與直觀的固體模型操作相比，面向特征設計允許設計者在抽象上進行操作。它可以通過一最小套參數(shù)快速列出模型的特征、尺寸以及其方位。此外，由于特征模型的數(shù)據(jù)結(jié)構(gòu)在幾何實體上的聯(lián)系，設計者更容易更改設計。如果沒有這些特征，設計者在構(gòu)造固體模型幾何特征時就必須考慮到所有需要的細節(jié)。而且面向特征的防真為設計者提供了更高級的成型對象。例如，模具設計者想象出一個澆口的實體形狀，電腦就能將這個澆口造型出來。 面向?qū)ο笤煨头ㄊ且环N參照實物的概念去設計模型的新思維方式?；镜膱D素是能夠?qū)?shù)據(jù)庫和單一圖素的動作聯(lián)系起來的對象。面向?qū)ο蟮脑煨蛯斫鈫栴}并且設計程序和數(shù)據(jù)庫是很有用的。此外，面向?qū)ο蟮难b配體呈現(xiàn)方式使得“子”對象能繼承其“父”對象的信息變得更容易。 參考文獻 [1]. K. H. Shin and K. Lee, “從干涉面的自動檢測注塑模具側(cè)芯的設計”, 雜志設計與制造, 3(3), pp. 225–236, 1993.12. [2]. Y. F. Zhang, K. S. Lee, Y. Wang, J. Y. H. Fuh and A. Y. C. Nee, “自動滑核心創(chuàng)作設計注塑模具的滑塊/升降”, CIRP國際會議在模具設計和制作及展覽, pp. 33–38, 土耳其, 1997.6.19-21. [3]. E. C. Libardi, J. R. Dixon and M. K. Simmon, “研究綜述：為機械組件設計的計算機環(huán)境”, 工程與計算機, 3(3), pp. 121–136, 1988. [4]. K. Lee and D. C. Gossard, “一種表示組件的分層數(shù)據(jù)結(jié)構(gòu)”, 計算機輔助設計, 17(1), pp. 15– 19, 1985.1. [5]. K. Lee and D. Gossard, “組件在組件中的位置推斷”, 計算機輔助設計, 17(1), pp.20–24 , 1985.1. [6]. A. P. Ambler and R. J. Popplestone, “從指定的空間關(guān)系推斷機構(gòu)的位置”,人工智能, 6, pp. 157–174, 1975. [7]. G. Kramer, 解決幾何約束系統(tǒng): 運動學的個案研究,麻省理工學院出版社，劍橋，麻省， 1992. [8]. J. J. Shah and M. T. Rogers, “基于特征設計的裝配建?！? 工程設計研究, 5(3&4), pp. 218–237, 1993. [9]. J. P. Kruth, R. Willems and D. Lecluse, “一種高層次模具設計支持系統(tǒng)”, CIRP國際會議在模具設計和制作及展覽, pp. 39–44, Turkey, 1997.6.19–21. [10]. J. J. Shah, “特征技術(shù)評價”, 計算機輔助設計, 23(5), pp. 331–343, 1991.6. [11]. S. R. Gorti, A. Gupta, G. J. Kim, R. D. Sriram and A. Wong, “面向產(chǎn)品和設計過程的一種面向?qū)ο蟊硎痉椒ā? 計算機輔助設計, 30(7), pp. 489–501, 1998.6. [12]. J. Rumbaugh, M. Blaha, W. Premerlani, et al. 面向?qū)ο蟮慕Ｅc設計, Prentice Hall出版社，黃俊英，新澤西州，1991. [13]. Unigraphics要點用戶手冊, Unigraphics 解決方案有限公司., 馬里蘭高地, MO, 1997. [14]. IMOLD主頁 http:://www.eng.nus.edu.sg/imold, Manusoft塑料私人有限公司新加坡. 附錄B Automated Assembly Modelling for Plastic Injection Moulds X. G. Ye, J. Y. H. Fuh and K. S. Lee Department of Mechanical and Production Engineering, National University of Singapore, Singapore An injection mould is a mechanical assembly that consists of product-dependent parts and product-independent parts. Thispaper addresses the two key issues of assembly modellingfor injection moulds, namely, representing an injection mouldassembly in a computer and determining the position andorientation of a product-independent part in an assembly. Afeature-based and object-oriented representation is proposedto represent the hierarchical assembly of injection moulds.This representation requires and permits a designer to thinkbeyond the mere shape of a part and state explicitly whatportions of a part are important and why. Thus, it providesan opportunity for designers to design for assembly (DFA). Asimplified symbolic geometric approach is also presented toinfer the configurations of assembly objects in an assemblyaccording to the mating conditions. Based on the proposedrepresentation and the simplified symbolic geometric approach,automatic assembly modelling is further discussed. Keywords: Assembly modelling; Feature-based; Injectionmoulds; Object-oriented 1.Introduction Injection moulding is the most important process for manufacturingplastic moulded products. The necessary equipment consistsof two main elements, the injection moulding machineand the injection mould. The injection moulding machines usedtoday are so-called universal machines, onto which variousmoulds for plastic parts with different geometries can bemounted, within certain dimension limits, but the injectionmould design has to change with plastic products. For differentmoulding geometries, different mould configurations are usuallynecessary. The primary task of an injection mould is to shapethe molten material into the final shape of the plastic product.This task is fulfilled by the cavity system that consists of core,cavity, inserts, and slider/lifter heads. The geometrical shapes and sizes of a cavity system are determined directly by theplastic moulded product, so all components of a cavity systemare called product-dependent parts. (Hereinafter, product refersto a plastic moulded product, part refers to the component ofan injection mould.) Besides the primary task of shaping theproduct, an injection mould has also to fulfil a number oftasks such as the distribution of melt, cooling the moltenmaterial, ejection of the moulded product, transmitting motion,guiding, and aligning the mould halves. The functional partsto fulfil these tasks are usually similar in structure and geometricalshape for different injection moulds. Their structuresand geometrical shapes are independent of the plastic mouldedproducts, but their sizes can be changed according to theplastic products. Therefore, it can be concluded that an injectionmould is actually a mechanical assembly that consists ofproduct-dependent parts and product-independent parts. Figure1 shows the assembly structure of an injection mould. The design of a product-dependent part is based on extractingthe geometry from the plastic product. In recent years,CAD/CAM technology has been successfully used to helpmould designers to design the product-dependent parts. The automatic generation of the geometrical shape for a productdependentpart from the plastic product has also attracted alot of research interest [1,2]. However, little work has beencarried out on the assembly modelling of injection moulds,although it is as important as the design of product-dependentparts. The mould industry is facing the following two difficultieswhen use a CAD system to design product-independentparts and the whole assembly of an injection mould. First,there are usually around one hundred product-independent partsin a mould set, and these parts are associated with each otherwith different kinds of constraints. It is time-consuming forthe designer to orient and position the components in anassembly. Secondly, while mould designers, most of the time,think on the level of real-world objects, such as screws, plates,and pins, the CAD system uses a totally different level ofgeometrical objects. As a result, high-level object-oriented ideashave to be translated to low-level CAD entities such as lines,surfaces, or solids. Therefore, it is necessary to develop anautomatic assembly modelling system for injection moulds tosolve these two problems. In this paper, we address the followingtwo key issues for automatic assembly modelling: representinga product-independent part and a mould assembly ina computer; and determining the position and orientation of acomponent part in an assembly. This paper gives a brief review of related research inassembly modelling, and presents an integrated representationfor the injection mould assembly. A simplified geometric symbolicmethod is proposed to determine the position and orientationof a part in the mould assembly. An example of automaticassembly modelling of an injection mould is illustrated. 2.Related Research Assembly modelling has been the subject of research in diversefields, such as, kinematics, AI, and geometric modelling. Libardiet al. [3] compiled a research review of assembly modelling.They reported that many researchers had used graphstructures to model assembly topology. In this graph scheme,the components are represented by nodes, and transformationmatrices are attached to arcs. However, the transformation matrices are not coupled together, which seriously affects the transformation procedure, i.e. if a subassembly is moved, all its constituent parts do not move correspondingly. Lee and Gossard [4] developed a system that supported a hierarchical assembly data structure containing more basic information about assemblies such as “mating feature” between the components. The transformation matrices are derived automatically from the associations of virtual links, but this hierarchical topology model represents only “part-of” relations effectively. Automatically inferring the configuration of components in an assembly means that designers can avoid specifying the transformation matrices directly. Moreover, the position of a component will change whenever the size and position of its reference component are modified. There exist three techniques to infer the position and orientation of a component in the assembly: iterative numerical technique, symbolic algebraic technique, and symbolic geometric technique. Lee and Gossard [5] proposed an iterative numerical technique to compute the location and orientation of each component from the spatial relationships. Their method consists of three steps: generation of the constraint equations, reducing the number of equations, and solving the equations. There are 16 equations for “against” condition, 18 equations for “fit” condition, 6 property equations for each matrix, and 2 additional equations for a rotational part. Usually the number of equations exceeds the number of variables, so a method must be devised to remove the redundant equations. The Newton–Raphson iteration algorithm is used to solve the equations. This technique has two disadvantages:first, the solution is heavily dependent on the initial solution; secondly, the iterative numerical technique cannot distinguish between different roots in the solution space. Therefore, it is possible, in a purely spatial relationship problem, that a mathematically valid, but physically unfeasible, solution can be obtained. Ambler and Popplestone [6] suggested a method of computing the required rotation and translation for each component to satisfy the spatial relationships between the components in an assembly. Six variables (three translations and three rotations) for each component are solved to be consistent with the spatial relationships. This method requires a vast amount of programming and computation to rewrite related equations in a solvable format. Also, it does not guarantee a solution every time, especially when the equation cannot be rewritten in solvable forms. Kramer [7] developed a symbolic geometric approach for determining the positions and orientations of rigid bodies that satisfy a set of geometric constraints. Reasoning about the geometric bodies is performed symbolically by generating a sequence of actions to satisfy each constraint incrementally, which results in the reduction of the object’s available degrees of freedom (DOF). The fundamental reference entity used by Kramer is called a “marker”, that is a point and two orthogonal axes. Seven constraints (coincident, in-line, in-plane, parallelFz, offsetFz, offsetFx and helical) between markers are defined. For a problem involving a single object and constraints between markers on that body, and markers which have invariant attributes, action analysis [7] is used to obtain a solution. Action analysis decides the final configuration of a geometric object, step by step. At each step in solving the object configuration, degrees of freedom analysis decides what action will satisfy one of the body’s as yet unsatisfied constraints, given the available degrees of freedom. It then calculates how that action further reduces the body’s degrees of freedom. At the end of each step, one appropriate action is added to the metaphorical assembly plan. According to Shah and Rogers [8], Kramer’s work represents the most significant development for assembly modelling. This symbolic geometric approach can locate all solutions to constraint conditions, and is computationally attractive compared to an iterative technique, but to implement this method, a large amount of programming is required. Although many researchers have been actively involved in assembly modelling, little literature has been reported on feature based assembly modelling for injection mould design. Kruth et al. [9] developed a design support system for an injection mould. Their system supported the assembly design for injection moulds through high-level functional mould objects (components and features). Because their system was based on AutoCAD, it could only accommodate wire-frame and simple solid models. 3. Representation of Injection Mould Assemblies The two key issues of automated assembly modelling for injection moulds are, representing a mould assembly in computers, and determining the position and orientation of a product- independent part in the assembly. In this section, we present an object-oriented and feature-based representation for assemblies of injection moulds. The representation of assemblies in a computer involves structural and spatial relationships between individual parts. Such a representation must support the construction of an assembly from all the given parts, changes in the relative positioning of parts, and manipulation of the assembly as a whole. Moreover, the representations of assemblies must meet The following requirements from designers: 1. It should be possible to have high-level objects ready to use while mould designers think on the level of realworld objects. 2. The representation of assemblies should encapsulate operational functions to automate routine processes such as pocketing and interference checks. To meet these requirements, a feature-based and object-oriented hierarchical model is proposed to represent injection moulds. An assembly may be divided into subassemblies, which in turn consists of subassemblies and/or individual components. Thus, a hierarchical model is most appropriate for representing the structural relations between components. A hierarchy implies a definite assembly sequence. In addition, a hierarchical model can provide an explicit representation of the dependency of the position of one part on another. Feature-based design [10] allows designers to work at a somewhat higher level of abstraction than that possible with the direct use of solid modellers. Geometric features are instanced, sized, and located quickly by the user by specifying a minimum set of parameters, while the feature modeller works out the details. Also, it is easy to make design changes because of the associativities between geometric entities maintained in the data structure of feature modellers. Without features, designers have to be concerned with all the details of geometric construction procedures required by solid modellers, and design changes have to be strictly specified for every entity affected by the change. Moreover, the feature-based representation will provide high-level assembly objects for designers to use. For example, while mould designers think on the level of a realworld object, e.g. a counterbore hole, a feature object of a counterbore hole will be ready in the computer for use. Object-oriented modelling [11,12] is a new way of thinking about problems using models organised around real-world concepts. The fundamental entity is the object, which combines both data structures and behaviour in a single entity. Objectoriented models are useful for understanding problems and designing programs and databases. In addition, the objectoriented representation of assemblies makes it easy for a “child” object to inherit information from its “parent”. References [1]. K. H. Shin and K. Lee, “Design of side cores of injection moulds from automatic detection of interference faces”, Journal of Design and Manufacturing, 3(3), pp. 225–236, December 1993. [2]. Y. F. Zhang, K. S. Lee, Y. Wang, J. Y. H. Fuh and A. Y. C. Nee, “Automatic slider core creation for designing slider/lifter of injection moulds”, CIRP International Conference and Exhibition on Design and Production of Dies and Moulds, pp. 33–38, Turkey, 19–21 June 1997. [3]. E. C. Libardi, J. R. Dixon and M. K. Simmon, “Computer environments for design of mechanical assemblies: A research review”, Engineering with Computers, 3(3), pp. 121–136, 1988. [4]. K. Lee and D. C. Gossard, “A hierarchical data structure for representing assemblies”, Computer-Aided Design, 17(1), pp. 15– 19, January 1985. [5]. K. Lee and D. Gossard, “Inference of position of components in an assembly”, Computer-Aided Design, 17(1), pp. 20–24, January 1985. [6]. A. P. Ambler and R. J. Popplestone, “Inferring the positions of bodies from specified spatial relationships”, Artificial Intelligence, 6, pp. 157–174, 1975. [7]. G. Kramer, Solving Geometric Constraint Systems: A Case Study in Kinematics, MIT Press, Cambridge, MA, 1992. [8]. J. J. Shah and M. T. Rogers, “Assembly modelling as an extension of feature-based design”, Research in Engineering Design, 5(3&4), pp. 218–237, 1993. [9]. J. P. Kruth, R. Willems and D. Lecluse, “A design support system using high level mould objects”, CIRP International Conference and Exhibition on Design and Production of Dies and Moulds, pp. 39–44, Turkey, 19–21 June, 1997. [10]. J. J. Shah, “Assessment of feature technology”, Computer-Aided Design, 23(5), pp. 331–343, June 1991. [11]. S. R. Gorti, A. Gupta, G. J. Kim, R. D. Sriram and A. Wong, “An objection-oriented representation for product