虛擬制造技術(shù)與數(shù)字化工藝

1、虛擬制造技術(shù)與數(shù)字化工藝 本文介紹了虛擬制造的背景和它的定義，討論了虛擬制造的流派、相關(guān)技術(shù)、應(yīng)用領(lǐng)域它在數(shù)字化工藝中的研究與應(yīng)用。隨著全球競爭的增加，為了縮短產(chǎn)品的上市時(shí)間，在八十年代相繼提出了fms（fexible manufacturing system）、cims(computer integrated manufacturing system)、ce(conturrent engineering)等新的概念，對它們的研究與應(yīng)用，提高了產(chǎn)品的質(zhì)量和生產(chǎn)效率。隨著網(wǎng)絡(luò)和生產(chǎn)技術(shù)的發(fā)展，在九十年代提出了敏捷制造am（agile manufacturing）、精良制造lm（lean manu

2、facturing）、分布式制造（distributed manufacturing）和虛擬企業(yè)ve（virtual enterprise）等新的研究領(lǐng)域，目前設(shè)計(jì)技術(shù)研究主要集中在詳細(xì)設(shè)計(jì)階段，cad系統(tǒng)雖然提供了表示和操作復(fù)雜零件 的方法，但是它不能表示概念設(shè)計(jì)階段的信息，在這種情況下，產(chǎn)生了虛擬制造vm（virtual manufacturing）。虛擬制造建立了計(jì)算機(jī)化的制造活動這樣一個(gè)關(guān)鍵概念，它概括了對真實(shí)制造世界的對象和活動的建模與仿真研究的各個(gè)方面。虛擬制造的基礎(chǔ)是用計(jì)算機(jī)支持的技術(shù)對所有必要的制造活動進(jìn)行徹底的建模與仿真，其中建立計(jì)算機(jī)化的工藝過程，即：數(shù)字化加工過程是虛擬制

3、造研究的核心基礎(chǔ)工作之一。虛擬制造的定義 在lawrence associates的virtual manufacturing user workshop報(bào)告中，vm被定義為：它是一個(gè)集成的、綜合的可運(yùn)行制造環(huán)境，用來提高各個(gè)層次的決策和控制。各部分的語義說明如下：環(huán)境 通過協(xié)同地提供分析工具、仿真工具、應(yīng)用工具、控制工具、模型（產(chǎn)品、過程和資源）、設(shè)備以及組織方法的集合，用以支持構(gòu)造和使用分布式制造仿真。層次 是指從產(chǎn)品的概念設(shè)計(jì)到回收利用、從車間到執(zhí)行位置、從物質(zhì)的轉(zhuǎn)換到信息的傳遞等各個(gè)方面?？刂?預(yù)測效果的真實(shí)性。提高 增加它的精度和可靠性。運(yùn)行 用環(huán)境來構(gòu)造和操作特定的制造仿真決策 是

4、指改變（可視化、組織、定義和選擇）后的影響。 綜合 指真實(shí)的和仿真的對象、活動和過程的混合狀態(tài)。上述關(guān)于vm的定義沒有充分強(qiáng)調(diào)vm在預(yù)測過程、成本和質(zhì)量方面的能力，而且它沒有說明vm預(yù)測的可靠性和精度，因此它還存在下面的缺點(diǎn)：該定義限制了它處理的范圍，并且提高了工程和制造之間的交互性。雖然它的最理想的定義達(dá)到了對vm最全面的描述，但是，根據(jù)不同用戶的對象、技術(shù)背景和水平，vm應(yīng)該有不同的定義。vm的定義應(yīng)與特定用戶的經(jīng)驗(yàn)基礎(chǔ)相聯(lián)系，這里的制造應(yīng)該是廣義的、企業(yè)范圍的“大”制造。因?yàn)樵谲囬g之外的重要活動也包含在建模、數(shù)據(jù)和仿真中。vm的定義必須與特定用戶的經(jīng)驗(yàn)和要求相聯(lián)系，因此，vm不可能只有一

5、種定義，對于每一個(gè)人來說，vm并不是完全相同的，所以應(yīng)了解它與其他相關(guān)概念的區(qū)別。給出一個(gè)象vm這樣覆蓋面廣的定義，是非常困難的。vm的定義不可能包含它的每一個(gè)方面。因此，為了更好地解釋vm，下面對vm的內(nèi)涵進(jìn)行說明：通過基于建模的途徑和利用仿真，vm主要是為了提高加工過程的質(zhì)量。vm最重要的作用是為實(shí)施ippd(integrated product process development)提供一個(gè)工具，特別是用于預(yù)測產(chǎn)品成本和控制功能。vm的基本目的是基于計(jì)算機(jī)模擬產(chǎn)品的開發(fā)環(huán)境，使得設(shè)計(jì)者在真正的加工之前就能夠模擬地制造產(chǎn)品。這里的“產(chǎn)品開發(fā)”包括了與產(chǎn)品相關(guān)的所有活動，不僅包括技術(shù)上的和

6、商業(yè)上的，而且包含了產(chǎn)品的設(shè)計(jì)和生產(chǎn)。但是，vm并不仿真所有的這些方面。vm是基于模型的制造，使用的工具反過來影響這些模型。最初始的工具是仿真，利用仿真可以降低制造成本，而且可以檢查真實(shí)空間和虛擬空間的許多參數(shù)。從全局的觀點(diǎn)來講，在一個(gè)ippd環(huán)境下，通過在計(jì)算機(jī)中完成“制造”，vm提供了對部分或全部設(shè)計(jì)過程的評價(jià)方法。1.vm的流派 vm的研究都與特定的應(yīng)用環(huán)境和對象相聯(lián)系，在vm的研究過程中，由于應(yīng)用的不同要求，各有不同的側(cè)重點(diǎn)，因此出現(xiàn)了三個(gè)不同的流派，它們是以設(shè)計(jì)為中心的vm、以生產(chǎn)為中心的vm和以控制為中心的vm。1.1 以設(shè)計(jì)為中心的vm 以設(shè)計(jì)為中心的vm是通過加制造信息到ipp

7、d的過程和在計(jì)算機(jī)中進(jìn)行“制造”，仿真多種制造方案和產(chǎn)生許多“軟”的模型。因此它的短期目標(biāo)是：為了達(dá)到特殊的制造目的(例如為了裝配進(jìn)行設(shè)計(jì)、精良操作或柔性等)，vm用以制造為基礎(chǔ)的仿真來優(yōu)化產(chǎn)品的設(shè)計(jì)和生產(chǎn)過程。它的長期目標(biāo)為：vm在不同的層次上用仿真過程來評估生產(chǎn)情況，并且反饋給設(shè)計(jì)和生產(chǎn)控制。1.2以生產(chǎn)為中心的vm以生產(chǎn)為中心的vm是通過加仿真能力到生產(chǎn)過程模型，達(dá)到方便和快捷地評價(jià)多種加工過程的目的。它的短期目標(biāo)是：vm是基于生產(chǎn)的ippd的轉(zhuǎn)換，用以優(yōu)化制造過程和物理層。它的長期目標(biāo)是：為了實(shí)現(xiàn)新工藝和流程的更高的可信度，vm是增加生產(chǎn)仿真到其它集成和分析技術(shù)。1.3 以控制為中心的

8、vm以控制為中心的vm是通過增加仿真到控制模型和實(shí)際的生產(chǎn)過程，來實(shí)現(xiàn)優(yōu)化的真實(shí)仿真。 1.4 三類vm之間的關(guān)系雖然三種vm的定義不相同，但是它們都涉及到虛擬產(chǎn)品生命周期中不同的方面，因此，它們具有下面的特點(diǎn)：以設(shè)計(jì)為中心的vm為設(shè)計(jì)者提供了一個(gè)設(shè)計(jì)產(chǎn)品和評估可制造性的環(huán)境，它的結(jié)果包括產(chǎn)品建模、成本預(yù)測等，所以，在設(shè)計(jì)中的潛在問題能夠被發(fā)現(xiàn)，同時(shí)它的一些指標(biāo)(例如成本等)也能被預(yù)測。為了生產(chǎn)出合格的產(chǎn)品而不做實(shí)際的樣品，以生產(chǎn)為中心的vm為工藝計(jì)劃和生產(chǎn)計(jì)劃的生成、工藝資源的要求以及對這些計(jì)劃的評價(jià)提供了一個(gè)環(huán)境，它能夠更精確地提供成本信息和產(chǎn)品的供給計(jì)劃。2. vm與其它相關(guān)技術(shù)之間的區(qū)

9、別當(dāng)前在先進(jìn)制造技術(shù)的研究過程中，產(chǎn)生了許多新的概念，如ippd、虛擬企業(yè)ve（virtual enterprise）、建模與仿真m&s(modeling and simulation)等。因此，為了更詳細(xì)說明vm的內(nèi)涵，需要了解vm與其它相關(guān)概念之間的關(guān)系。2.1 vm與ippd ippd是一種交錯(cuò)功能協(xié)調(diào)機(jī)理，它使得與設(shè)計(jì)和制造相關(guān)的信息可以在產(chǎn)品設(shè)計(jì)過程的各模塊間流動。vm仿真制造、生產(chǎn)和裝配過程，因此它必須有與上面信息的接口，但是vm并不是各模塊的集合，也不能使信息在模塊間流動。它們的關(guān)系如圖1所示。圖1 產(chǎn)品開發(fā)過程按照ippd的觀點(diǎn)，vm增加了ippd的過程，它提供了一種方法將制造

10、知識綜合到產(chǎn)品開發(fā)的早期階段。因此，它在ippd中的作用是重要的。首先它允許ippd直接通過模擬加工過程來設(shè)計(jì)、分析和制造產(chǎn)品，而不用關(guān)心實(shí)際的加工。其次，它允許ippd在原型系統(tǒng)中任意層次上增加過程。ippd的優(yōu)勢并不在于過程中模塊的多少，因?yàn)閹讉€(gè)最好的單個(gè)模型組合到一起并不是最好的。利用vm，ippd可以逆向分析加工過程，而不用重構(gòu)加工過程。按照并行工程ce(concurrent engineering)的觀點(diǎn)，vm增加了上面提到的能力外，它共享的基礎(chǔ)結(jié)構(gòu)比ce所需要的更可靠。2.2 vm與m&s(modeling and simulation) vm依靠m&s技術(shù)模擬制造、生產(chǎn)和裝配過程

11、，使設(shè)計(jì)者可以在計(jì)算機(jī)中“制造”產(chǎn)品。m&s是vm的基礎(chǔ)。vm是m&s的應(yīng)用，但是它擴(kuò)展了傳統(tǒng)的m&s技術(shù)。在傳統(tǒng)上，m&s建模的目的僅僅是為了仿真和相關(guān)的分析。而在vm中，使用主要部分已存在的模型，而不是優(yōu)化的仿真。因?yàn)樵趘m中，由于其他的原因，模型是動態(tài)的，隨著仿真環(huán)境的改變，它是變化的。2.3 vm與ve(virtual enterprise) 虛擬企業(yè)是敏捷制造的基本的動態(tài)組織形態(tài)，是指為了贏得某一機(jī)遇性市場競爭，圍繞某種新產(chǎn)品開發(fā)，通過選用不同組織或公司的優(yōu)勢資源，綜合成單一的靠網(wǎng)絡(luò)通訊聯(lián)系的階段性經(jīng)營實(shí)體。動態(tài)聯(lián)盟具有集成性和時(shí)效性兩大特點(diǎn)。它實(shí)質(zhì)上是不同組織或企業(yè)間的動態(tài)集成，隨

12、市場機(jī)遇的存亡而聚散。在具體表現(xiàn)上，結(jié)盟的可以是同一個(gè)大公司的不同組織部門，也可以是不同國家的不同公司。在ve中伙伴能夠共享生產(chǎn)、工藝和產(chǎn)品的信息，這些信息以數(shù)據(jù)的形式表示，能夠分布到不同的計(jì)算環(huán)境中。ve與vm沒有很強(qiáng)的相互依靠關(guān)系。在信息的集成和共享領(lǐng)域，ve主要強(qiáng)調(diào)網(wǎng)絡(luò)，而vm主要強(qiáng)調(diào)產(chǎn)品的設(shè)計(jì)，而且在設(shè)計(jì)階段vm的重點(diǎn)是仿真產(chǎn)品的生命周期中的各個(gè)活動。 2.4 vm與vp(virtual prototyping) 虛擬原型(virtual prototype)是相對物理原型，具有一定功能的基于計(jì)算機(jī)的仿真系統(tǒng)。它主要用于測試和評價(jià)多種設(shè)計(jì)的指定特性。vp是使用虛擬原型的過程。目前，它主

13、要用于縮短產(chǎn)品的開發(fā)時(shí)間和降低成本。在vp中，計(jì)算機(jī)輔助設(shè)計(jì)信息直接被傳送到產(chǎn)品模型，而不用構(gòu)造物理原型來檢驗(yàn)設(shè)計(jì)的有效性和進(jìn)行優(yōu)化設(shè)計(jì)。如果虛擬原型是通過模擬工藝計(jì)劃來構(gòu)造的，那么vp就是用vm來產(chǎn)生的，在大部分情況下，vp比物理原型具有更大的優(yōu)點(diǎn)，在虛擬產(chǎn)品周期中，vp是一個(gè)必需的組成部分。所以，vp的發(fā)展將增強(qiáng)vm的能力，反過來，vm為vp提供了一個(gè)應(yīng)用環(huán)境。2.5 vm與am(agile manufacturing) 敏捷制造作為一個(gè)新概念，其基本思想是通過將高素質(zhì)的員工、動態(tài)靈活的組織機(jī)構(gòu)、企業(yè)內(nèi)及企業(yè)間的靈活管理以及柔性的先進(jìn)生產(chǎn)技術(shù)進(jìn)行全面集成，使企業(yè)能夠?qū)Τ掷m(xù)變化、不可預(yù)測的市

14、場要求作出快速反應(yīng)，由此獲得長期的經(jīng)濟(jì)效益。由此可見，敏捷制造強(qiáng)調(diào)人、組織、管理和技術(shù)的高度集成，強(qiáng)調(diào)企業(yè)面向市場的敏捷性(agility)。在一個(gè)企業(yè)的組織管理中，它的敏捷性可以用四個(gè)主要變量表示，即通訊連同性(communication connectedness)、跨組織參與性(interorganization participation)、生產(chǎn)的靈活性(production flexibility)和雇員的使能性(employee empowerment)。vm是敏捷制造的一種實(shí)現(xiàn)手段，是制造企業(yè)增強(qiáng)產(chǎn)品開發(fā)敏捷性、快速滿足市場多元化需求的有效途徑。 3. vm在數(shù)字化工藝中的應(yīng)用

15、3.1 數(shù)字化工藝的概念對切削加工而言，早在本世紀(jì)初切削的工藝模型就引起研究者的關(guān)注，但一直到本世紀(jì)40 60年代，在切削機(jī)理方面的幾項(xiàng)突破使切削研究有可能建立在材料的物理層面上，到本世紀(jì)80年代以后，隨著計(jì)算技術(shù)和測量技術(shù)的進(jìn)展，大量的工作集中在工藝過程的分析、建模與仿真，他們對不同的工藝過程（車、銑、鉆、鑄、沖壓等）的不同方面（力模型、熱模型、誤差模型、材料變形模型等）及不同的加工材料（金屬、復(fù)合材料等）做了大量的工作，取得了豐碩的成果，一些結(jié)果已應(yīng)用于工業(yè)界，獲得了滿意的效果。然而，這些研究成果仍未大面積的推廣應(yīng)用，原因在于研究的不系統(tǒng)性。傳統(tǒng)上，工藝的設(shè)計(jì)與校驗(yàn)典型地通過制造一個(gè)實(shí)物原

16、型來完成，而基于工藝的可制造性評估則根據(jù)加工的成本和時(shí)間來確定加工的難度，加工時(shí)間和成本由零件材料、加工特征和加工參數(shù)的手冊值決定，虛擬制造技術(shù)在多方面改進(jìn)了傳統(tǒng)的工藝設(shè)計(jì)和校驗(yàn)：通過“數(shù)字化加工過程”，不需要制造昂貴的實(shí)物原型就可在計(jì)算機(jī)上校驗(yàn)工藝設(shè)計(jì)；通過“數(shù)字化加工過程”不僅可精確地估計(jì)制造時(shí)間和成本，還可估計(jì)其它重要參數(shù)，如：零件質(zhì)量；通過“數(shù)字化加工過程”可以更直觀地“觀察”加工過程，如磨削過程中單個(gè)磨粒的微觀表現(xiàn)，切削中的應(yīng)力與熱流，卡具的變形。這些有助于我們更精確和更有創(chuàng)造性地設(shè)計(jì)加工過程。 “數(shù)字化加工過程”包含二層含義：一是刀具路徑仿真，即建立工件/工具/機(jī)床的實(shí)體模型，刀具

17、沿著由工藝確定的軌跡切削，一些不適當(dāng)?shù)牡毒哕壽E(刀具/夾具干涉)很容易地被發(fā)現(xiàn)；二是評估是否在加工工藝中說明的工藝參數(shù)是合適的，如大的切深會產(chǎn)生顫震，毀壞刀具、工件，高的進(jìn)給率導(dǎo)致不可接受的表面粗糙度，研究者已經(jīng)在刀具路徑校驗(yàn)方面做了大量工作，也有大量工作是有關(guān)加工過程的物理效應(yīng)模型，在虛擬加工過程中將表達(dá)切削的物理效應(yīng)的模型和表達(dá)切削幾何的實(shí)體模形結(jié)合起來，完整地表達(dá)切削。在虛擬制造環(huán)境下，物理模型與實(shí)體模型的規(guī)范描述和系統(tǒng)集成將不僅能評估現(xiàn)有的工藝過程，而且能為新工藝的創(chuàng)新與設(shè)計(jì)提供有力手段。3.2 數(shù)字化加工過程的系統(tǒng)結(jié)構(gòu)。工藝過程數(shù)字原型是真實(shí)工藝過程在虛擬世界（計(jì)算機(jī)）的影射，模型反

18、映的是工藝過程一個(gè)側(cè)面的特性，因此工藝過程數(shù)字原型是反映工藝過程各個(gè)側(cè)面特性的模型及其相互關(guān)系的集合。一般基本工藝過程可抽象地表達(dá)如圖2。圖2 單元工藝在上圖，基本的加工過程可表達(dá)為：輸入為毛坯，利用設(shè)備在工藝信息的指揮下加工出產(chǎn)品和產(chǎn)生廢棄物；在右圖，與加工過程相關(guān)的物理實(shí)體是工具（刀具與卡具，有時(shí)也包括機(jī)床）和工件，而所有與工藝過程相關(guān)的物理效應(yīng)主要都發(fā)生在這些實(shí)體上，因此，我們可以基于工件、刀具和卡具產(chǎn)品模型來構(gòu)造規(guī)范化的數(shù)字化加工過程結(jié)構(gòu)，即將加工過程處理作為一個(gè)四維的過程，即：空間三維和時(shí)間維。任意一個(gè)工藝過程效應(yīng)都發(fā)生在特定的位置和時(shí)間，因此任意一個(gè)工藝過程效應(yīng)都可看作一個(gè)四維空間

19、點(diǎn)上的屬性，這樣的處理使不同的模型之間建立了一種統(tǒng)一、規(guī)范而直接的對應(yīng)關(guān)系，從而有利于較好描述具有多種物理效應(yīng)和復(fù)雜耦合關(guān)系的工藝過程，建立結(jié)構(gòu)化的加工過程數(shù)字原型，加工過程數(shù)字原型的結(jié)構(gòu)如下圖所示，分四層： 圖3 數(shù)字化加工過程的系統(tǒng)結(jié)構(gòu) 第一層為幾何實(shí)體層，建立與工藝過程相關(guān)的物理實(shí)體的幾何模型；第二層為運(yùn)動學(xué)模型層，基于第一層模型和運(yùn)動軌跡信息，建立幾個(gè)幾何實(shí)體之間相互運(yùn)動的關(guān)系；第三層為物理模型層；基于第二層中幾何實(shí)體之間的相互關(guān)系（時(shí)間軸上和位置上的）和工藝信息（材料、加工條件）建立物理效應(yīng)模型（斷裂、變形、力），這些物理效應(yīng)彼此相互作用，構(gòu)成了復(fù)雜的網(wǎng)絡(luò)關(guān)系；在輸出層，按特定的順序

20、搜集、排列第三層的輸出，獲得完整的工藝特性結(jié)果，如：按空間搜集所有留在毛坯上的材料，即為加工后工件形狀。3.3 工件表面誤差的分析實(shí)驗(yàn) 圖4為棒銑刀加工表面的一個(gè)試驗(yàn)結(jié)果，圖中比較了加工表面誤差，理論與實(shí)驗(yàn)結(jié)果很一致。圖4 棒銑刀加工表面誤差比較主要參考文獻(xiàn)1. zheng l.， liang s.y.， “identification of cutter axis.tilt in end milling*”transaction of asme， journal of manufacturing science and engineering， 1998.22. zheng l.， lian

21、g s.y.， “analysis of end milling forces with cutter axis tilt”transaction of namri/sme，vol.23，1995 p137-1423. zheng l.，chiou y.s.， liang s.y.， “three dimensional cutting force analysis in end milling ”，int. j of manufacturing science， 1995，37(10)4. beverly a. beckert， venturing into virtual product

22、development， modern manufacturing， september 19965. paul dvorak， engineering puts virtual reality to work， modern manufacturing， october 19976. edward lin， inoannis minis， dana s. nau and william regli， contribution to virtual manufacturing background research ， may19957. virtual manufacturing user

23、workshop， dod joint directors of laboratories， 25-26 oct. 1994 virtual manufacturing technology and digital technologyzheng li, xu ping , lu , jia qiu ,xu2006-2-2 this introduced virtual manufacturing background and its definition, discussed virtual manufacturing styles, relevant technology, applica

24、tions in the field of digital technology, research and application.with increasing global competition, in order to shorten the products listed time in the 1980s have made ltd. (fexible manufacturing system), cims (computer integrated manufacturing system), ce (conturrent engineering), new concepts,

25、and applications of their research to improve product quality and production efficiency. with the development of technology and production networks in the 1990s by creating a strong am (agile manufacturing), sophisticated manufacturing lm (lean manufacturing), distributed manufacturing (distributed

26、manufacturing) and the virtual enterprise ve (virtual enterprise), a new field of study, the current study focused on the technical design stage of detailed design, cad systems, while providing that the method and operation of complex components, but it can not express the concept design stage of in

27、formation, in such circumstances, have tried to create a virtual (virtual manufacturing).virtual manufacturing establishment of a computerized manufacturing activities such a key concept, which summarizes the world of real objects and manufacturing activities of the various aspects of modelling and

28、simulation studies，virtual manufacturing is based on the use of computer technology to support all the activities necessary to create a thorough modelling and simulation, in which a computerized processes, namely : digital plus the study process is to create virtual one of the core foundations.virtu

29、al manufacturing definitionlawrence associates in the virtual manufacturing user workshop report, the vm is defined as : it is a master, integrated operational manufacturing environment to enhance all levels of decision-making and control. semantic description of the various components are as follow

30、s : environment through concerted provide analytical tools, simulation tools, application tools, control tools, models (product, process and resource), equipment and the organization of the assembly methods, to support the construction and use of distributed manufacturing simulation. levels refers t

31、o the concept of products from design to recycling, from the workshop to implement location, material from the conversion to the transmission of information fields. control forecast results authenticity improved increase its accuracy and reliability. operation environment for the construction and op

32、eration of a specific manufacturing simulation decision-making mean change (visualization, organization, definition and choice) impact. integrated that the real and simulated objects, activities and processes cocktailon the above definition does not adequately emphasized tried tried in the forecast

33、process, cost and quality capabilities, but it does not indicate the reliability and accuracy of forecasts vm, there are also shortcomings : the definition limits its scope to deal with, and enhance the engineering and manufacturing world between. although it tried to achieve the best definition of

34、the most comprehensive description, but according to different user groups, technical background and level should be tried different definitions. vm should be defined with specific user experience associated with the manufacture here should be broad, enterprise-wide big manufacturing. because in add

35、ition to the workshop is included in the modelling of important activities, data and simulation.the definition must be tried with the experience and requirements of specific user linked, and therefore can not be tried only one definition for each individual, vm is not exactly the same, it should und

36、erstand the difference between it and other related concepts. such as vm provides an extensive coverage of the definition is very difficult. vm definition can not include every aspect of it. therefore, in order to better explain tried and tried by the content of a note : ways and through the use of

37、simulation-based modelling, tried mainly to enhance processing quality. vm is the most important role for the implementation of ippd (integrated produce process development) to provide a tool, particularly for products projected cost and control function.vm basic aim of computer-based simulation pro

38、duct development environment, allowing designers in the real processing can be simulated prior to manufacture products. here, product development includes all activities relating to products, including not only the technical and commercial, and includes product design and production. however, the si

39、mulation does not tried all these aspects. vm model is based on the manufacture and use of tools in turn affect these models. simulation tools are most initial use of simulation can reduce manufacturing costs, but can also check the real space and virtual space of many parameters.speaking from the o

40、verall perspective, in a ippd environment through the computer to complete the manufacture and tried to provide some or all of the design process for the evaluation methodologies.1. the school of vmvm research with specific application environment and associated targets in vm research process, becau

41、se of the different applications, each with a different focus, resulting in three different styles, they are designed to center tried, for the production-centred and tried to control the center tried to1.1 to design for the center of vm.tried to design for the center through the manufacturing proces

42、s and the information in the computer to ippd, create, a simulation of manufacturing programmes and many soft models. therefore its short-term objectives are : to create a special purpose (for example, to assemble a design, sophisticated operation or soft), tried to create-based simulation to optimi

43、ze the product design and production process. its long-term goal : vm in different levels to assess the production process using simulation, and feedback to the design and production control. 1.2 to the production center of vmproduction centred tried to increase simulation capacity by the production

44、 process models, and to facilitate quick assessment of multiple processing purposes. its short-term objectives are : vm is based on the production ippd conversion to optimize the manufacturing process and the physical layer. its long-term goal is : new processes and procedures in order to achieve hi

45、gher credibility, tried to increase production simulation to other integration and analysis technologies 1.3 to the control center of vmto the control center through increased tried to control simulation models and the actual production process, to achieve the true simulation1.4 the relationship bet

46、ween the three categories vmalthough the definition of the three tried different, but they all relate to different virtual product life cycle, therefore, they have the following characteristics : centred tried to design for designers with a design and evaluation can manufacture products of the envir

47、onment, including the results of its product modelling, cost projections, therefore, the potential problems in the design can be found, while some of its indicators (such as cost, etc.) can also be predicted. qualified to produce products without doing the actual samples for the production centred t

48、ried to craft plans and the generation of production plans, processes and resources required for the evaluation of these plans provided a environment, it can provide a more accurate cost information and products supply.2. vm distinction between technical and other relatedcurrently in advanced manufa

49、cturing technology research process generated many new concepts, such as ippd, virtual enterprise ve (virtual enterprise), modelling and simulation m&s (modeling and simulation). therefore, in order to explain in more detail the content tried, and tried to understand other related concepts relations

50、.2.1 vm and ippdippd is a cross functional coordination mechanisms, and it makes design and manufacturing-related information in the product design process modules mobile. vm simulation manufacturing, production and assembly process, it must interface with the above information, but the vm is not th

51、e module assembly, or in which information flows between the modules. as shown in figure 1 of their relationship. figure 1 product development processin accordance with the views of ippd, tried to increase the ippd process, which provides a comprehensive approach to creating knowledge in the early s

52、tages of product development. therefore, it is important in the role of the ippd. first it allows ippd directly through simulation processes for the design, analysis and manufacture of products, instead of the actual processing concern. secondly, it allows the prototype system ippd arbitrary levels

53、increase process. ippd advantage does not lie in the number of course modules, as several of the best individual model portfolio together is not the best. vm,ippd can use reverse analysis processes, instead reconstructs processing. in parallel works ce (concurrent engineering) perspective, tried to

54、increase the above-mentioned capabilities, sharing infrastructure it needs more reliable than the ce.2.2 vm and m&s(modeling and simulation)m&s tried to rely on simulation technology manufacturing, production and assembly process so that designers can in the computer to create products. m&s was trie

55、d foundation. vm is m&s applications, but it extended the traditional m&s technology. traditionally, the aim was merely to m&s modelling simulation and related analysis. in vm, the use of the main part of the model has been in existence, rather than optimizing the simulation. because in the vm, beca

56、use of other reasons, the models are dynamic, changing with the simulation environment, it is changing.2.3 vm and ve(virtual enterprise)virtual enterprise is the ability to create basic dynamic organization patterns refers to the opportunity to win a competition of the market, centering on some new

57、product development, through the choice of different organizations or companies resources, integrated into a single network communications rely on the interim operating entity. dynamics of integration and timeliness union two characteristics. it is essentially a different dynamic between the organiz

58、ation or enterprise integration, with the market opportunities and assemble and part survival. in specific performance, allied with a large company can be different organizational departments, and can also be of different companies in different countries. ve partners can share in the production, technical and product information, the information in the form of data that can be distributed to different computing environment. ve and tried not strong interdependent relationships. in the area of information integration a