夾具類(lèi)集成和信息輔助夾具設(shè)計(jì)與制造外文翻譯、中英文翻譯、外文文獻(xiàn)翻譯

附錄  附錄 1：外文翻譯  集成 和 信息 輔助 夾具設(shè)計(jì)與制造  F. MERVYN, A. SENTHIL KUMAR* and A. Y. C NEE 雖然大量的研究已 應(yīng)用于 開(kāi)發(fā)計(jì)算機(jī)輔助夾具設(shè)計(jì)系統(tǒng)， 但 夾具設(shè)計(jì)制造領(lǐng)域和其他領(lǐng)域 之間的信息交換并 沒(méi)有徹底處理。本文針對(duì)這一差距 ， 在夾具設(shè)計(jì)中 通過(guò) 應(yīng)用 適當(dāng)?shù)男畔⒛?型 研究 計(jì)算機(jī)輔助夾具設(shè)計(jì)系統(tǒng)和集成支持制造業(yè)。 夾具設(shè)計(jì)的模型 主要是 介紹有關(guān) 夾具設(shè)計(jì)， 以及 其他設(shè)計(jì)和制造活動(dòng)。 對(duì)應(yīng)用 在XML 的信息模型和信息交流 中的 一個(gè)基于 XML 的消息傳遞模型的方法進(jìn)行了討論 。  關(guān)鍵詞： 夾具設(shè) 計(jì)，綜合設(shè)計(jì)和制造 ；信息建模 ； 1.介紹  在一個(gè)旨在降低產(chǎn)品交貨時(shí)間和成本以及提高產(chǎn)品質(zhì)量 的過(guò)程中 ，企業(yè)尋求各種工程所涉及的一體化進(jìn)程設(shè)計(jì)和制造產(chǎn)品。適當(dāng)?shù)恼蠈⒃试S在一個(gè)產(chǎn)品實(shí)現(xiàn)涉及領(lǐng)域作出的決定 適用于 其他領(lǐng)域的需要，導(dǎo)致整體的最優(yōu)解設(shè)計(jì)和制造產(chǎn)品。計(jì)算機(jī)輔助系統(tǒng)發(fā)揮了關(guān)鍵作用 在于 協(xié)助不同領(lǐng)域開(kāi)展工作。開(kāi)發(fā)集成設(shè)計(jì)和制造系統(tǒng)的 一個(gè) 關(guān)鍵成功因素在于能在各種電腦輔助系統(tǒng)的信息 進(jìn)行 交流。夾具設(shè)計(jì)領(lǐng)域的發(fā)展已出現(xiàn)大量的電腦輔助系統(tǒng) 的應(yīng)用 。在制造過(guò)程設(shè)備服務(wù)于持有目的工件和保持一個(gè)安全方面的一致關(guān)系的工具。已通過(guò)各 種辦法發(fā)展半自動(dòng)化，自動(dòng)化夾具設(shè)計(jì)系統(tǒng)。張畢（ 2001）努力提出的這些 最新成果 。盡管 通過(guò) 大量的研究， 適應(yīng)各 域之間的信息和其他制造業(yè)領(lǐng)域 的 交流 ，但是 需求并沒(méi)有得到徹底處理。適當(dāng)?shù)膴A具設(shè)計(jì)信息模型描述知識(shí)和技術(shù)規(guī)格將有助于大大提高產(chǎn)品質(zhì)量和縮短產(chǎn)品交貨時(shí)間。本文的目的是要為解決通過(guò)對(duì)相應(yīng)的信息化輔助模式的夾具設(shè)計(jì)系統(tǒng)， 并 支持集成設(shè)計(jì)和制造。該這項(xiàng)工作的范圍只限于加工裝置  本文組織如下：第 2 條的有關(guān)研究進(jìn)行討論在發(fā)展生產(chǎn)的信息模型 ；第 3 條提出了一個(gè)活動(dòng)模型夾具設(shè)計(jì) ；第 4 給出了不同的夾具設(shè)計(jì)信息模式，以支持集成設(shè)計(jì) 和制造，而第 5 條提出了一個(gè)使用 XML 的例子，實(shí)現(xiàn)了信息模型。 第 6 節(jié)介紹交流信息的夾具設(shè)計(jì)方法為基礎(chǔ)上的信息模型和第 7 條最后的文件。  2.相關(guān)研究      制造業(yè)的信息交流的重要性已經(jīng) 發(fā)展了 發(fā)展各種信息模型為代表的加工過(guò)程。國(guó)際標(biāo)準(zhǔn)化組織 10303 部分（國(guó)際標(biāo)準(zhǔn)化組織， 1997）是一個(gè)應(yīng)用協(xié)議的存儲(chǔ)和交換（美聯(lián)社）進(jìn)程之間的數(shù)控加工零件計(jì)劃的資料不同的計(jì)算機(jī)輔助工藝規(guī)劃（ CAPP 系統(tǒng)）系統(tǒng)。對(duì) AP 213 的范圍包括規(guī)劃信息的數(shù)控加工計(jì)劃，生產(chǎn)任務(wù)的指示利用數(shù)控機(jī)床的一部分，數(shù)控編程和過(guò)程檢驗(yàn)資料。 Wysk 等。  （ 1995年）制定了工藝方案和正式代表模式聯(lián)營(yíng)工廠(chǎng)資源模型。他們的工作范圍是就如何處理計(jì)劃可以用在車(chē)間控制環(huán)境，從而提供整合工藝規(guī)劃和生產(chǎn)之間的執(zhí)行。性等。  （ 1998）開(kāi)發(fā)了一個(gè)信息模型的 CAPP 系統(tǒng) 。 采用面向?qū)ο蟮慕：推⒎址匠?發(fā)展 數(shù)據(jù)技術(shù)。該模型包括零件信息模型，計(jì)劃信息模型的過(guò)程和生產(chǎn)資源信息模型。該工藝方案模型包含制造業(yè)活動(dòng)的資料，例如程序，設(shè)置和制造業(yè)務(wù)。在制造工程工具包（ METK）項(xiàng)目，標(biāo)準(zhǔn)和技術(shù)研究所（ NIST）的在美國(guó)開(kāi)發(fā)的一個(gè)過(guò)程計(jì)劃（李 1999 年）作為信息模型在整合過(guò)程中的規(guī)劃和 NC 驗(yàn)證的應(yīng)用程序的手段 ， 這個(gè)過(guò)程計(jì)劃規(guī)定對(duì)每個(gè)產(chǎn)品的流程順序指示。  Ryou 和 Jerard（ 2001）最近開(kāi)發(fā)的基于 XML 的一個(gè)代表性數(shù)值稱(chēng)為控制標(biāo)記語(yǔ)言（ NCML 之）作為一個(gè)有利的技術(shù)，允許買(mǎi)家和自定義加工零件賣(mài)方通過(guò)互聯(lián)網(wǎng)進(jìn)行電子商貿(mào)。在代表性，資料工件，設(shè)置，工具和信息寬容是提供讓用戶(hù)判斷一個(gè)零件的可制造。很明顯從文獻(xiàn)回顧，信息的加工過(guò)程發(fā)展模式要么不提供或只提供信息裝置固定裝置的信息作為車(chē)間執(zhí)行系統(tǒng)資源。原因這是因?yàn)樵诩稍O(shè)計(jì)和制造設(shè)備的作用已被忽視，不經(jīng)過(guò)深入的探討。 通過(guò) 模式的發(fā)展，活動(dòng)模型通常是 先發(fā)展?；顒?dòng)模式設(shè)置在其中的 作用 是不同的域之間的交換方面設(shè)計(jì)和制造，從而確定捕獲的信息類(lèi)型在信息模型。這些活動(dòng)的模型的一些審查中可以找到（ 1996）。活動(dòng)模式發(fā)展至今，裝置只能被視為一個(gè)制造系統(tǒng)的資源。對(duì)裝置的影響一個(gè)產(chǎn)品的設(shè)計(jì)仍沒(méi)有得到處理。在確定一個(gè)產(chǎn)品 的 關(guān)鍵作用，準(zhǔn)確度也高，一個(gè)制造系統(tǒng)的靈活性 、 夾具的能力，有效的產(chǎn)品，因此應(yīng)在設(shè)計(jì)關(guān)注一個(gè)產(chǎn)品。本文針對(duì)這在當(dāng)前制造業(yè)信息化差距模型提出一個(gè)模型，夾具設(shè)計(jì)活動(dòng)的需要考慮作用在產(chǎn)品設(shè)計(jì)和制造設(shè)備。適當(dāng)?shù)膴A具設(shè)計(jì)信息模型，然后發(fā)展到支持集成的設(shè)計(jì)和制造業(yè)。該 信息模型的開(kāi)發(fā)利用作為一個(gè) XML 的文件格式和交換信息的基礎(chǔ)上的做法。  3.夾具設(shè)計(jì)活動(dòng)模型  擬議的夾具設(shè)計(jì)活動(dòng)的模型如圖 1 所示。  該活動(dòng)已使用 IDEF0 方法描述，并且只有在一個(gè)描述抽象的層面，使信息模型是獨(dú)立的執(zhí)行這些活動(dòng)的。在圖 1 可以看出，一為綜合設(shè)計(jì)夾具設(shè)計(jì)系統(tǒng)與制造執(zhí)行兩個(gè)主要活動(dòng)，格 A1 -夾具概念設(shè)計(jì)和 A2 -詳細(xì)夾具設(shè)計(jì)。  夾具設(shè)計(jì)活動(dòng)的概念是一個(gè)規(guī)劃過(guò)程的一部分活動(dòng)，在那里他們討論了需要概念工藝規(guī)劃的活動(dòng)，支持產(chǎn)品設(shè)計(jì)的概念確定生產(chǎn)過(guò)程，選擇資源和設(shè)備，從制造成本估算的概念活動(dòng)輸出發(fā)送反饋到產(chǎn) 品概念設(shè)計(jì)活動(dòng)。作為活動(dòng)的一部分概念工藝規(guī)劃，通過(guò)對(duì)活動(dòng)支持的困難分析概念產(chǎn)品設(shè)計(jì)夾具設(shè)計(jì)的概念?yuàn)A具在該產(chǎn)品的特點(diǎn)，估計(jì)該產(chǎn)品的加工成本所采取的固定裝置和夾具的制造時(shí)間。到投入活動(dòng)是概念產(chǎn)品設(shè)計(jì)，產(chǎn)品的數(shù)量的估計(jì)是生產(chǎn)和當(dāng)前夾具清單。該任務(wù)的概念?yuàn)A具設(shè)計(jì)活動(dòng)有：   1.確定要使用夾具的類(lèi)型為基礎(chǔ)的估計(jì)量該產(chǎn)品被制造。   2.在加工過(guò)程中的部分限制的基礎(chǔ)上確定的困難概念產(chǎn)品的幾何形狀。   3.估計(jì)的時(shí)間和新設(shè)備的設(shè)計(jì)和制造成本如果目前的庫(kù)存設(shè)備不能使用。  夾具的概念設(shè)計(jì)活動(dòng)的 關(guān)鍵 是信息模型 和 概念設(shè)計(jì) 的 反饋。這 將提供產(chǎn)品信息模型與問(wèn)題反饋設(shè)計(jì)，并提供了夾具上一個(gè)度量產(chǎn)品設(shè)計(jì)人員比較關(guān)注的不同的初始設(shè)計(jì)。   圖 1.夾具設(shè)計(jì)活動(dòng)模型。  夾具的概念設(shè)計(jì)活動(dòng)的輸出是信息模型 與 概念設(shè)計(jì)反饋。這將提供產(chǎn)品信息模型 與 問(wèn)題 的 反饋設(shè)計(jì)，并提供了一個(gè)度量產(chǎn)品設(shè)計(jì)人員比較關(guān)注的夾具上有不同的初始設(shè)計(jì)。      該夾具的詳細(xì)設(shè)計(jì)活動(dòng)的投入是固定的類(lèi)型從概念?yuàn)A具設(shè)計(jì)活動(dòng)的信息，中間部分模型將被加工和夾具庫(kù)存信息。中間部分模型零件的幾何 關(guān)系 設(shè)置。作為一個(gè)例子，圖 2 顯示了一個(gè)部分，需要 3 設(shè)置機(jī)器的特點(diǎn)。中間部分是固定式模式，在每個(gè)安裝圖 中顯示。中間部分模型可以得出一旦制造業(yè)序列測(cè)定。應(yīng)當(dāng)指出，該夾具設(shè)計(jì)活動(dòng)作為輸入接收 信息控制 整個(gè)零件模型。該 圖 提供了對(duì)現(xiàn)有夾具元件所需資料，以便夾具設(shè)計(jì)中使用。                              圖 2.例如部分，中間部分的模型。  夾具的詳細(xì)設(shè)計(jì)活動(dòng)的任務(wù)是：     1.設(shè)計(jì)為每個(gè)安裝夾具。這包括進(jìn)行夾具布局夾具的設(shè)計(jì)和配置設(shè)計(jì)。     2.評(píng)估所設(shè)計(jì)的夾具以及如何履行其職能的準(zhǔn)確定位，限制和支持工件     3. 生成的鋪地板的固定裝置處理必要的指示。這包括在夾緊工件和正確的到達(dá)的每 個(gè)夾緊力應(yīng)驅(qū)動(dòng)。順序夾具的詳細(xì)設(shè)計(jì)活動(dòng)的輸出是信息模型，中間部分模型反饋，夾具配置和組裝工件裝載指示。  中間部分模型提供反饋信息反饋的過(guò)程以及如何規(guī)劃師每個(gè)零件模型之間的中間可以設(shè)置固定式。反饋將使這個(gè)進(jìn)程規(guī)劃 達(dá)到 夾具最佳工藝方案。  夾具裝配模型的配置信息有兩個(gè)目的。首先，它提供有關(guān)的信息工具的夾具裝配路徑規(guī)劃配置。這些信息可以被用來(lái)生成夾具裝配的檢查刀具路徑之間的干擾和夾具元件。其次，它使車(chē)間人員構(gòu)建基于組件的夾具提供信息。  工件裝載指示信息模型提供車(chē)間工件如何 適用于 于人員的指示和 信號(hào) 燈。  4.夾具設(shè)計(jì)信 息模型      本節(jié)描述了各種夾具設(shè)計(jì)信息模型的細(xì)節(jié)將要生成的夾具設(shè)計(jì)活動(dòng)。該信息模型已使用 XML 實(shí)現(xiàn)。兩種方法可以用來(lái)表示數(shù)據(jù)時(shí)使用 XML，第一是使用一個(gè)文檔類(lèi)型定義（ DTD），第二個(gè)是使用一個(gè) XML 架構(gòu)。在這項(xiàng)工作中，我們代表的數(shù)據(jù)使用一個(gè) DTD。一個(gè) DTD 定義該元素可以出現(xiàn)在一個(gè) XML 文件和辦法，使他們能夠出現(xiàn)。對(duì)每個(gè) DTD 的結(jié)構(gòu)信息模型解釋了部分。這些文件是由一個(gè)開(kāi)發(fā)計(jì)算機(jī)輔助夾具設(shè)計(jì)產(chǎn)生系統(tǒng)（默文等 ， 2003）。  4.1 概念設(shè)計(jì) 和 反饋  該概念設(shè)計(jì)反饋 XML 文件的 DTD 列于  圖 3 是由四個(gè)組的信息了：  （一）產(chǎn)品設(shè)計(jì)的評(píng)價(jià)是進(jìn)行了身份，  （二）固定式的使用，  （三）該概念設(shè)計(jì)的幾何評(píng)價(jià)，并  （四）預(yù)計(jì)成本和時(shí)間，制造燈具。                        圖 3.概念設(shè)計(jì)反饋 DTD 的 XML 文件。      在該夾具類(lèi)型的基礎(chǔ)上加以確定的估計(jì)量產(chǎn)品被生產(chǎn)。該夾具類(lèi)型要么是 '專(zhuān)用 '或 '彈性 '。一般來(lái)說(shuō)，一個(gè)專(zhuān)一個(gè)靈活的夾具用于小批量的生產(chǎn)。用夾具用于大批量的生產(chǎn)和幾何直觀的評(píng)價(jià)應(yīng)該是對(duì)產(chǎn)品設(shè)計(jì)人員認(rèn)識(shí)上的夾具設(shè)計(jì)產(chǎn)品的幾何效應(yīng)。有關(guān)資料也應(yīng)可解釋為電腦自動(dòng)化環(huán)境中使用。為了要做到這一點(diǎn)，幾何評(píng) 價(jià)已經(jīng)被映射到該產(chǎn)品的特點(diǎn)設(shè)計(jì)。每個(gè)產(chǎn)品的功能，被加工有三個(gè)屬性， '定位 '，克制 '和 '支持 '。這些屬性是一個(gè)代表的職責(zé)夾具。因此，他們描述的能力，夾具加工過(guò)程中的一部分功能。雖然有幾個(gè)功能可以在一次裝夾加工，這個(gè)映射已經(jīng)被采納，使產(chǎn)品設(shè)計(jì)師能夠輕松地認(rèn)識(shí)到這一問(wèn)題的該產(chǎn)品的幾何形狀。三個(gè)屬性的每個(gè)有兩個(gè)子屬性， '存在人臉 '和 '臉 '獲取。這兩個(gè)屬性的集體描述能否完成特定功能的燈具。面對(duì)存在的屬性指的是尋找緩解面臨的定位，夾緊工件和支持在加工的功能。此屬性將一個(gè)整數(shù)的數(shù)值范圍從 1 至 5，1 個(gè)非常容易和非常困難的 5。輔助功能屬性的臉指的是在公司目前的庫(kù)存夾具能夠訪(fǎng)問(wèn)夾具的臉。這可能是一兩個(gè)值， '標(biāo)準(zhǔn) '或 '特殊 '。如果臉難以進(jìn)入，一個(gè)可能需要特殊的夾具和值將是 '特殊 '。標(biāo)準(zhǔn)裝置是可以買(mǎi)現(xiàn)成的，現(xiàn)成的或現(xiàn)有的裝置元素在可用于裝夾部分用于公司。這個(gè)屬性允許產(chǎn)品設(shè)計(jì)人員了解有關(guān)產(chǎn)品的成本影響幾何夾具及采取的制造夾具的時(shí)間。例如，如果類(lèi)型的夾具 '是一個(gè)靈活的夾具，但面臨的無(wú)障礙特殊，它意味著由于該產(chǎn)品幾何，專(zhuān)用夾具需要一個(gè)靈活的，雖然夾具的基礎(chǔ)上更適合需要的產(chǎn)品數(shù)量。這將使產(chǎn)品設(shè)計(jì)師，了解了產(chǎn)品的增加導(dǎo)致時(shí)間和成本。  在成本和 時(shí)間估算屬性有三個(gè)子屬性，估計(jì)費(fèi)用制造夾具，預(yù)計(jì)需時(shí)多久制造的，可以在一夾具加工工件夾具蔚，數(shù)量。這些屬性使產(chǎn)品設(shè)計(jì)師 1 夾具的成本和效果的估計(jì)的夾具在產(chǎn)品交貨時(shí)間?？傮w而言，這一信息模型提供了難易程度反饋夾具概念設(shè)計(jì)。該 fixturability 據(jù)分析映射以該產(chǎn)品的模型功能允許直觀地了解產(chǎn)品設(shè)計(jì)師其特點(diǎn)將構(gòu)成裝夾加工過(guò)程中的問(wèn)題。產(chǎn)品設(shè)計(jì)人員可以使用這些信息來(lái)作出評(píng)估的概念設(shè)計(jì)或改變之間關(guān)于 fixturability 關(guān)注的幾個(gè)概念設(shè)計(jì)。  4.2 中間部分模型 fixturability 反饋      該模型的中間 部分的 XML 文件的 DTD fixturability 反饋需要的   結(jié)構(gòu)如圖 4 所示。       圖 4.中間部分模型 fixturability 反饋 DTD 的 XML 文件 。  在這個(gè)信息模型中，模型的中間部分評(píng)價(jià)是基于三個(gè)屬性， '定位 '， '克制 '和 '支持 '。如前面提到的，這些屬性是一個(gè)固定的職能的代表。不過(guò)，相對(duì)的概念產(chǎn)品設(shè)計(jì)評(píng)價(jià)，中間部分模型的詳細(xì)信息可在這個(gè)階段。因此，在履行職能的能力上更徹底的代表性在此提供的信息模型。對(duì)位置屬性的孔來(lái)定位和信息的一部分建立一個(gè)基準(zhǔn)誤差估計(jì)。每個(gè)定位孔上有定位元素限制?；鶞?zhǔn)誤差 估計(jì)屬性從工件位置的理想位置提供的信息可能偏差。這一信息是提供 6 個(gè)自由度，翻譯從 X -， y 軸和 z 軸和旋轉(zhuǎn)攻方的 X， Y 型和 Z -軸。屬性的限制和支持也包含的信息用于工件夾緊和支持。屬性的限制有進(jìn)一步的約束分析屬性。此屬性描述的能力夾具以制止在加工過(guò)程中工件的議案。這可能需要一兩個(gè)值，限制或無(wú)限制。類(lèi)似屬性的約束分析，支持屬性具有變形分析子屬性。此屬性介紹了夾具在機(jī)械加工能力，以支持和工件防止變形。此屬性將一個(gè)整數(shù)的值從 1 至 5， 1 對(duì)應(yīng)非常差和 5 對(duì)應(yīng)非常好?；鶞?zhǔn)誤差估計(jì)，約束分析和變形分析屬性提供反饋的進(jìn)程以及如 何規(guī)劃每個(gè)可以是固定的中間部分模型。   附錄 2：英文原文  Fixture design information support for integrated design and manufacturing F. MERVYN, A. SENTHIL KUMAR* and A. Y. C NEE Although a vast amount of research has been conducted on developing computer-aided fixture design systems, the need for information exchange between the fixture design domain and other manufacturing domains has not been thoroughly dealt with. This paper addresses this gap in fixture design research through the development of appropriate information models for computer-aided fixture design systems to support integrated design and manufacturing. A fixture design activity model is presented that relates fixture design to other design and manufacturing activities. The implementation of the information models in XML and the exchange of the information models based on an XML messaging approach are also discussed. Keywords: Fixture design； Integrated design and manufacturing； Information modelling； XML 1. Introduction In an aim to reduce product lead-time and cost as well as improve product quality, enterprises seek the integration of the various engineering processes involved in the design and manufacture of a product. Proper integration will allow the different domains involved in the realization of a product to make decisions taking into account the requirements of other domains, resulting in overall optimal solutions for the design and manufacture of a product. Computer-aided systems play a key role today in aiding the different domains carry out their tasks. A crucial factor in the success of developing integrated design and manufacturing systems lies in the ability to exchange information among the various computer-aided systems. The fixture design domain has seen a vast amount of research in developing computer-aided systems. Fixtures are devices that serve the purpose of holding a workpiece securely and maintaining a consistent relationship with respect to the tools during a manufacturing process (Nee et al. 1995). Various approaches have been adopted in developing interactive, semi-automated and automated fixture design systems. Bi and Zhang (2001) present a recent review of these efforts. Despite the vast amount of research, the need for information exchange between the fixture *Corresponding author. Email: .sg International Journal of Production Research ISSN 00207543 print/ISSN 1366588X online   2006 Taylor & Francis http:/www.tandf.co.uk/journals DOI: 10.1080/00207540500465303 design domain and other manufacturing domains has not been thoroughly dealt with (Mervyn et al. 2003a). Appropriate information models describing fixture design knowledge and specifications could help to significantly improve product quality and reduce product lead-time. The aim of this paper is to take a step towards addressing this need through the development of appropriate information models for computeraided fixture design systems to support integrated design and manufacturing. The scope of this work is limited to machining fixtures. This paper is organized as follows: section 2 discusses the related research carried out in developing manufacturing information models； section 3 presents an activity model for fixture design； section 4 presents the different fixture design information models to support integrated design and manufacturing, while section 5 presents an example of the information models implemented using XML. Section 6 describes the exchange of the fixture design information models based on a messaging approach and section 7 concludes the paper. 2. Related research The importance of information exchange in manufacturing has seen the development of various information models for representing the machining process. ISO 10303 Part 213 (ISO, 1997) is a STEP application protocol (AP) for storing and exchanging process plan information for numerically controlled machined parts between dissimilar computer-aided process planning (CAPP) systems. The scope of AP 213 includes planning information of NC process plans, task instructions to manufacture a part using NC machines, NC programming and in-process inspection information. Wysk et al. (1995) developed a formal representation schema for process plans and an associated factory resource model. The scope of their work was on how process plans can be used in a shop floor control environment, thus providing integration between process planning and production execution. Xing et al. (1998) developed an information model for CAPP by using object-oriented modelling and the PDES/ STEP data techniques. The model consists of the part information model, the process plan information model and the production resource information model. The process plan model contains information on manufacturing activities such as processes, setups and manufacturing operations. The manufacturing engineering toolkit (METK) project at the National Institute of Standards and Technology (NIST) in the USA developed an information model for a process plan (Lee 1999) as a means of integrating process planning and NC validation applications. The process plan provides instructions on the sequence of processes for each product. Ryou and Jerard (2001) recently developed a representation based on XML called numerical control markup language (NCML) as an enabling technology to permit buyers and sellers of custom machined parts to conduct e-commerce via the Internet. In the representation, information regarding workpiece, setups, tool information and tolerance is provided to allow users to judge the manufacturability of a part. From the literature review, it was evident that the machining process information models developed either do not provide information on fixtures or only provide information on fixtures as a resource for shop floor execution systems. The reason for this is that the role of fixtures in integrated design and manufacturing has been overlooked and not thoroughly explored. In the development of standard 2 F. Mervyn et al. information models, an activity model is normally developed first. Activity models set the context in which information is exchanged between the different domains in design and manufacturing, and thus determine the type of information captured in information models. A review of some of these activity models can be found in Feng (1996). In the activity models developed thus far, fixtures have only been considered as a resource for manufacturing systems. The effect of fixtures on the design of a product has not been dealt with. Fixtures play a key role in determining the accuracy of a product and also, the flexibility of a manufacturing system. The ability to effectively fixture a product should therefore be a concern in the design of a product. This paper addresses this gap in current manufacturing information models by presenting a fixture design activity model that takes into account the role of fixtures in product design and manufacturing. Appropriate fixture design information models are then developed to support integrated design and manufacturing. The information models are developed using XML as a file format and exchanged based on a messaging approach. 3. Fixture design activity model The proposed fixture design activity model is as shown in figure 1. The activities have been described using IDEF0 and are only described at an abstract level so that the information models are independent of the implementation of these activities. As seen in figure 1, a fixture design system for integrated design and manufacturing performs two main activities, A1Conceptual Fixture Design and A2Detailed Fixture Design. The conceptual fixture design activity is part of a conceptual process planning activity, described in Feng and Zhang (1999), where they discuss the need for a conceptual process planning activity that supports conceptual product design by determining the manufacturing processes, selecting resources and equipment, and estimating manufacturing costs roughly. The output from the conceptual process Figure 1. Fixture design activity model. planning activity is sent as feedback to the conceptual product design activity. As part of the conceptual process planning activity, the conceptual fixture design activity supports conceptual product design through an analysis of the difficulties in fixturing the product during the machining of the product features, estimation of the cost of the fixtures and the time taken to manufacture the fixture. The inputs to the activity are the conceptual product design, the estimated quantity of the product to be manufactured and the current fixture inventory. The tasks of the conceptual fixture design activity are: . Determine the type of fixture to be used based on the estimated quantity of the product to be manufactured. . Determine difficulties in restraining a part during machining based on the conceptual product geometry. . Estimate the time and cost of designing and manufacturing new fixtures if the current inventory of fixtures cannot be used. The output of the conceptual fixture design activity is the information model, conceptual design fixturability feedback. This information model will provide product designers with feedback on fixturability problems and also provides a metric for product designers to compare different initial designs in terms of fixturing concerns. The inputs to the detailed fixture design activity are the type of fixture information from the conceptual fixture design activity, the intermediate part model, the faces of the intermediate part model that will be machined and the fixture inventory information. The intermediate part model is the geometry of the part in between setups. As an example, figure 2 shows a part that requires three setups to machine the features. The intermediate part models to be fixtured at each setup are shown in the figure. The intermediate part model can be derived once the manufacturing sequences are determined. It should be noted that the conceptual fixture design activity receives the entire part model as an input. The fixture Figure 2. Example part and intermediate part models. inventory provides the necessary information on the available fixture elements to be used in fixture design. The tasks of the detailed fixture design activity are: . Design the fixture for each setup. This includes carrying out fixture layout design and fixture configuration design. . Evaluate how well the designed fixture fulfils its functions of accurately locating, restraining and supporting a workpiece. . Generate the necessary instructions for shop floor handling of fixtures. This includes arriving at a proper sequence for clamping the workpiece and the force that each clamp should be actuated with. The outputs of the detailed fixture design activity are the information models, intermediate part model fixturability feedback, fixture assembly configuration and workpiece loading instructions. The intermediate part model fixturability feedback information model provides feedback to the process planner on how well each intermediate part model between setups can be fixtured. The feedback will allow the process planner to arrive at the optimal process plan taking into account fixturing considerations. The fixture assembly configuration information model serves two purposes. Firstly, it provides tool path planners with information on the fixture assembly configuration. This information can then be used to generate the fixture assembly for checking of interference between the tool path and fixture elements. Secondly, it allows shop floor personnel to construct the fixture assemblies based on the provided information. The workpiece loading instructions information model provides shop floor personnel instructions on how the workpiece should be located and restrained on the fixture. 4. Fixture design information models This section describes the details of the various fixture design information models to be generated by the fixture design activities. The information models have been implemented using XML. Two approaches can be used when representing data using XML； the first is to use a document type definition (DTD) and the second is to use an XML schema. In this work, we represent the data using a DTD. A DTD defines the elements that can appear in an XML document and the way in which they can appear. The structure of the DTD of each information model is explained in this section. These files are to be generated by a developed computer-aided fixture design system (Mervyn et al. 2003b). 4.1 Conceptual design fixturability feedback The DTD of the conceptual design fixturability feedback XML file is shown in figure 3 and is made up of four groups of information: (i) the identity of the product design that the evaluation is carried out for, (ii) the type of fixture to be used, (iii) the geometric evaluation of the conceptual design, and (iv) the estimated cost and time to manufacture the fixture. Figure 3. DTD of conceptual design fixturability feedback XML file. The type of fixture is to be determined based on the estimated quantity of products to be manufactured. The type of fixture could either be dedicated  or flexible . Generally, a dedicated fixture is used for high volume production and a flexible fixture is used for low volume production. The geometric evaluation should be intuitive to the product designer to understand the effect of the product geometry on the fixture design. The information should also be computer interpretable for use in an automated environment. In order to do this, the geometric evaluation has been mapped to the features of the product design. Each feature of the product to be machined has three attributes, location , restraint  and support . These attributes are representative of the functions of a fixture. They thus describe the ability to fixture the part during the machining of the feature. Although several features can be machined in a single setup, this mapping has been adopted to allow the product designer to easily recognize the problem with the product geometry. Each of the three attributes has two sub-attributes, presence of faces  and accessibility of faces . These two attributes collectively describe the ability to fulfil the particular function of the fixture. The presence of faces attribute refers to the ease of finding faces for locating, clamping and supporting the workpiece during the machining of the feature. This attribute takes an integer value ranging from 1 to 5, 1 for very easy and 5 for very difficult. The accessibility of faces attribute refers to the ability of a fixture in the company s current inventory to access the fixturing face. This could be one of two values, standard  or special . If a face is difficult to access, a special fixture might be required and the value would be special . Standard fixtures are elements that could be bought off-the-shelf or existing fixtures in the company that can be used for fixturing the part. This attribute allows the product designer to understand the effect of the product geometry on the cost of the fixture and the time taken to manufacture the fixture. For example, if the type of fixture  is a flexible fixture, but the accessibility of faces is special, it would mean that due to the product geometry, a dedicated fixture is required although a flexible fixture is more suitable based on the product quantity required. This would allow the product designer to understand the increase in the product lead-time and cost. The cost and time estimation attribute has three sub-attributes, the estimated cost to manufacture the fixture, the estimated time taken to manufacture the fixture and Figure 4. DTD of intermediate part model fixturability feedback XML file. the number of workpieces that can be machined in one fixture. These attributes give the product designer an estimate of the cost of the fixture and the effect of the fixture on the product lead-time. Overall, this information model provides feedback on the ease or difficulty of fixturing the conceptual design. The mapping of the fixturability analysis according to features of the product model allows a product designer to i