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密 級 分類號 編 號 成 績 本科生畢業(yè)設(shè)計 (論文) 外 文 翻 譯 原 文 標(biāo) 題 Current mechanical design and development trend 譯 文 標(biāo) 題 當(dāng)前機械設(shè)計概述及發(fā)展趨勢 作者所在系別 機電工程學(xué)院 作者所在專業(yè) 機械設(shè)計制造及自動化 作者所在班級 B13113 作 者 姓 名 于婷婷 作 者 學(xué) 號 20134011329 指導(dǎo)教師姓名 丁紅軍 指導(dǎo)教師職稱 講師 完 成 時 間 2017 年 3 月 北華航天工業(yè)學(xué)院教務(wù)處制 譯文標(biāo)題 當(dāng)前機械設(shè)計概述及發(fā)展趨勢 原文標(biāo)題 Mechanical design and development trend 作 者 Richard GBudynas& J Keith Niabell 譯 名 理查德G巴基納斯.J基斯.尼斯比特 國 籍 美國 原文出處 Mechanical Engineering Design 當(dāng)前機械設(shè)計概述及發(fā)展趨勢 制造任何產(chǎn)品的第一步工作都是設(shè)計。機械設(shè)計是一門通過設(shè)計新產(chǎn)品或者改進(jìn)老產(chǎn)品來滿足人類需求的應(yīng)用技術(shù)科學(xué)。它是一個廣闊的工程技術(shù)領(lǐng)域，不僅要研究產(chǎn)品在尺寸、形狀和詳細(xì)結(jié)構(gòu)等方面的基本構(gòu)思，還要考慮產(chǎn)品在制造、銷售和使用等方面的有關(guān)問題。 進(jìn)行各種機械設(shè)計工作的人員通常被稱為設(shè)計人員或者設(shè)計工程師。機械設(shè)計是一項創(chuàng)造性的工作。設(shè)計工程師不僅在工作上要有創(chuàng)新性，還必須在機械制圖、運動學(xué)、動力學(xué)、工程材料、材料力學(xué)和機械制造工藝等方面具有深厚的基礎(chǔ)知 識。 以材料的選擇為例。近些年來，工程材料的選擇已經(jīng)顯得非常重要。此外，選擇過程應(yīng)該是一個對材料的連續(xù)不斷的重新評價過程。新材料不斷出現(xiàn)，而一些原有的材料的可以被利用的數(shù)量可能會減少。環(huán)境污染、材料的回收利用、工人的健康及安全等方面經(jīng)常會對材料選擇附加新的限制條件。為了減輕重量或者節(jié)約能源，可能會要求使用不同的材料。來自國內(nèi)和國際的競爭、對產(chǎn)品維修保養(yǎng)方便性要求的提高和顧客的反饋等方面的壓力，都會促使人們對材料進(jìn)行重新評價。由于材料選用不當(dāng)造成的產(chǎn)品責(zé)任訴訟，已經(jīng)產(chǎn)生了深刻的影響。此外，材料與材料加工之間的相互依賴關(guān)系已經(jīng)被人們認(rèn)識得更清楚。新的加工方法的出現(xiàn)，通常會促使人們對被加工材料進(jìn)行重新評價。因此，為了能在合理的成本和確保質(zhì)量的前提下獲得滿意的結(jié)果，設(shè)計工程師和制造工程師都必須認(rèn)真仔細(xì)地選擇、確定和使用材料。 在機械加工方面，銑削和磨削加工是設(shè)計人員經(jīng)常要考慮的機械加工方法。除了車削和鉆削，銑削無疑是應(yīng)用最廣泛的金屬切削方法。銑削非常適合于而且也易于應(yīng)用在任何數(shù)量的零件的經(jīng)濟生產(chǎn)中。在產(chǎn)品制造過程中，許許多多種類的銑削加工是值得設(shè)計人員認(rèn)真考慮和選擇的。 磨削是一種應(yīng)用最廣泛的零件精加工方法，用來獲得非常小的公差和非常低的表面粗糙度。目前，幾乎存在著適合于各種磨削工序的磨床。零件的設(shè)計特征在很大程度上決定了需要采用的磨床的種類。當(dāng)加工成本太高時，就值得對零件進(jìn)行重新設(shè)計，使其能夠通過采用即便宜又具有高生產(chǎn)率的磨削方法加工出來。例如，在有可能的時候，可以通過對零件的適當(dāng)設(shè)計，盡量用無心磨削加工，以獲取經(jīng)濟效益。 盡管通常認(rèn)為磨削適用于精加工工序，對那些適合于采用磨削來完成粗、精加工工序的工件，也經(jīng)常采用磨削方法完成全部加工作，而不采用車削或其他加工方法，因此，許多種類的鍛件和其他零件，可以采用磨削的的方法完成其從毛坯到成品的全部加工，這可以顯著地節(jié)約時間和費用。此外，對特種加工工藝的運用，也將使設(shè)計工作變得更大膽和具有創(chuàng)新性。在目前采用的常規(guī)工藝中，材料的去除是依賴于電動機和硬的刀具材料進(jìn)行的，諸如鋸斷、鉆孔和拉削。常規(guī)的成型加工時利用電動機、液壓和重力所提供的能量進(jìn)行的。同樣，材料連接的常規(guī)做法是采用諸如燃燒的氣體和電弧等熱能進(jìn)行的。與之相比，特種加工工藝采用按照以前的標(biāo)準(zhǔn)來說不是常規(guī)的能源?，F(xiàn)在材料的去除可以利用電化學(xué)反應(yīng)、高溫等離子、高速液體和磨料射流。過去非常難進(jìn)行成型加工的材料，現(xiàn)在可以利用大功率的電火花所產(chǎn)生的磁場，爆炸和沖擊潑進(jìn)行成型加工。采用高頻聲波和電子束可以使材料的聯(lián)接能力有很大的提高。 在過去的50年間，人們發(fā)明了20多種特種加工工藝，并且將其成功的應(yīng)用于生產(chǎn)之中。這么多特種加工工藝存在的原因與許多種常規(guī)加工工藝存在的原因是一樣的。每一種工藝都有它自己的特點和局限性。因而，不存在一種對任何只在環(huán)境來說都是最好的工藝方法。 采用特種加工工藝或者可以通過增加重復(fù)精度，減少已損壞工件在加工過程中的損傷，或者減少對工件性能的有害影響來減少采用原來加工工藝產(chǎn)生的廢品數(shù)量。 如前面所述，機械設(shè)計的目的是生產(chǎn)能夠滿足人類需求的產(chǎn)品。發(fā)明、發(fā)現(xiàn)和科學(xué)知識本身并不一定能給人帶來益處，只有當(dāng)它們被用在產(chǎn)品上才能產(chǎn)生效益。因而，應(yīng)該認(rèn)識到在一個特定產(chǎn)品進(jìn)行設(shè)計之前，必須先確定人們是否需要這種產(chǎn)品。 應(yīng)當(dāng)把機械設(shè)計看成是設(shè)計人員運用創(chuàng)造性的才能進(jìn)行產(chǎn)品設(shè)計、系統(tǒng)分析和制訂產(chǎn)品的制造工藝的一個良機。掌握工程基礎(chǔ)知識要比熟記一些數(shù)據(jù)和公式更為重要。僅僅使用數(shù)據(jù)和公式是不足以在一個好的設(shè)計中做出所需的全部決定。另一方面，應(yīng)該認(rèn)真精確的進(jìn)行所有運算。 一個好的設(shè)計人員應(yīng)該勇于提出新的想法，而且愿意承擔(dān)一定的風(fēng)險，當(dāng)新的方法不適用時，就恢復(fù)采用原來的方法。因此，設(shè)計人員必須要有耐心，因為所花費的時間和努力并不能保證成功。一個全新的設(shè)計，要求拋棄許多陳舊的，為人們所知的方法。由于許多人易于墨守成規(guī)，這樣做并不是一件容易的事情。一位設(shè)計工程師應(yīng)該不斷地探索改進(jìn)現(xiàn)有產(chǎn)品的辦法，在此過程中應(yīng)該認(rèn)真選擇原有的、經(jīng)過驗證的設(shè)計原理，將其與未經(jīng)過驗證的新觀念結(jié)合起來。 在設(shè)計的初始階段，應(yīng)該允許設(shè)計人員不受各種約束，充分發(fā)揮創(chuàng)造性。即使產(chǎn)生了許多不切實際的想法，也會在設(shè)計的早期，即繪制生產(chǎn)圖紙之前被改正掉。只有這樣，才不至于堵塞創(chuàng)新的思路。通常要提出幾套設(shè)計方案，然后加以比較。很有可能在最后選定的方案中，采用了某些未被接受的方案中的一些想法。 另一個應(yīng)該認(rèn)識到的重要問題是，設(shè)計工程師必須能夠同其他有關(guān)人員進(jìn)行交流和溝通。在開始階段，設(shè)計人員必須就初步設(shè)計同管理人員進(jìn)行交流和溝通，并得到批準(zhǔn)。這一般式通過口頭討論，草圖和文字材料進(jìn)行的。為了有效地進(jìn)行交流，需要解決一些問題：（1）所要設(shè)計的這個產(chǎn)品是否真正為人們所需要（2）此產(chǎn)品與其他公司的現(xiàn)有同類產(chǎn)品相比有無競爭力（3）生產(chǎn)這種產(chǎn)品是否經(jīng)濟（4）產(chǎn)品的維修是否方便（5）產(chǎn)品有無銷路是否可以盈利。 另外，對于許多產(chǎn)品的制造管理人員來說，機電一體化具有如下一些優(yōu)點：(1) 主要設(shè)備的利用率提高，機電一體化系統(tǒng)中的一組機器的總產(chǎn)量，通?？梢赃_(dá)到同類型機器單獨工作環(huán)境下產(chǎn)量的三倍。(2) 減少了主要設(shè)備的費用，機電一體化系統(tǒng)中，因為設(shè)備的利用率高，所以用更少的機床就可以完成傳統(tǒng)生產(chǎn)系統(tǒng)中的工作量。(3) 減少了直接勞動力費用，由于每一臺機器都完全在計算機控制下運行，所以就不需要進(jìn)行全程監(jiān)視。(4) 減少了在制工件的庫存和時間差距，機電一體化系統(tǒng)與傳統(tǒng)車間相比，在制工件數(shù)明顯減少。(5) 對改變生產(chǎn)需求的響應(yīng)，一個機電一體化系統(tǒng)固有的靈活性使其能生產(chǎn)不同的產(chǎn)品，這些不同的產(chǎn)品是由于市場需求的改變或工藝設(shè)計的變化而提出的。(6) 有維持生產(chǎn)的能力，當(dāng)一臺或多臺機床出故障時，設(shè)計許多機電一體化系統(tǒng)來合理地降低加工精度等級。(7) 提高產(chǎn)品質(zhì)量。有時候，與一個還沒有組成協(xié)作系統(tǒng)的機床比較時，機電一體化系統(tǒng)的一個優(yōu)點被忽視了，那就是它能改善產(chǎn)品的質(zhì)量。(8) 操作的靈活性，操作的靈活性使生產(chǎn)力明顯提高。(9) 生產(chǎn)能力的靈活性，由于對可利用的占地面積，做了正確的計劃，一個機電一體化系統(tǒng)最初可為低產(chǎn)量而設(shè)計，也可以提供需要的附加生產(chǎn)力。 只有時間才能對上述問題給出正確的答案。但是，產(chǎn)品的設(shè)計、制造和銷售只能在對上述問題的初步肯定答案的基礎(chǔ)上進(jìn)行。設(shè)計工程師還應(yīng)該通過零件圖和裝配圖，與制造部門一起對最終設(shè)計方案進(jìn)行溝通。 通常，在制造過程中會出現(xiàn)某個問題?？赡軙髮δ硞€零件尺寸或公差做一些改進(jìn)，使零件更容易生產(chǎn)。但是，工程上的更改必須要經(jīng)過設(shè)計人員批準(zhǔn)，以保證不會損傷產(chǎn)品的功能。有時，在產(chǎn)品的裝配時或者裝箱外運前的實驗中才發(fā)現(xiàn)設(shè)計中的某種缺陷。這些事例恰好說明了設(shè)計室一個動態(tài)過程?？偸谴嬖谥玫姆椒▉硗瓿稍O(shè)計工作，設(shè)計人員應(yīng)該不斷努力，尋找這些更好的方法。 一個有能力的工程師不應(yīng)該害怕再提出自己的方案時遭到失敗的可能性。事實上，偶然失敗是肯定會發(fā)生的，因為每一個真正有創(chuàng)意的設(shè)想似乎總是有失敗或者批評伴隨著它。從一次失敗中可以學(xué)到很多東西，只有不怕遭受失敗的人們才能夠取得最大的收獲。總之不把方案提交出來，才是真正的失敗。 隨著科學(xué)技術(shù)的發(fā)展，產(chǎn)品功能要求的增加，特別是產(chǎn)品的復(fù)雜性增加，更新?lián)Q代速度加快致使壽命期縮短，對產(chǎn)品的設(shè)計，尤其是機械產(chǎn)品方案的設(shè)計要求越來越高。 現(xiàn)代設(shè)計的特點是面向市場和用戶的設(shè)計，現(xiàn)代設(shè)計不僅要實現(xiàn)產(chǎn)品的基本功能，更應(yīng)體現(xiàn)人性化和環(huán)境保護(hù)的設(shè)計理念。下面就機械產(chǎn)品的現(xiàn)代設(shè)計方法以及機械設(shè)計技術(shù)的發(fā)展趨勢加以論述。 一、機械產(chǎn)品的現(xiàn)代設(shè)計方法 1、智能化 智能化設(shè)計方法的主要特點是：根據(jù)設(shè)計方法學(xué)理論，借助于三維圖形軟件、智能化設(shè)計軟件和虛擬現(xiàn)實技術(shù)，以及多媒體等工具進(jìn)行產(chǎn)品的開發(fā)設(shè)計、表達(dá)產(chǎn)品的構(gòu)思、描述產(chǎn)品的結(jié)構(gòu)。 2、系統(tǒng)化 系統(tǒng)化設(shè)計方法的主要特點是：將設(shè)計看成由若干個設(shè)計要素組成的一個系統(tǒng)，每個設(shè)計要素既具有獨立性又存在著有機的聯(lián)系，并具有層次性，所有的設(shè)計要素結(jié)合后，即可實現(xiàn)設(shè)計系統(tǒng)所需完成的任務(wù)。 3、模塊化 模塊化設(shè)計方法的主要特點是：視具有某種功能的實現(xiàn)為一個結(jié)構(gòu)模塊，通過結(jié)構(gòu)模塊的組合，實現(xiàn)產(chǎn)品的方案設(shè)計。 4、基于產(chǎn)品特征知識 基于產(chǎn)品特征知識設(shè)計方法的主要特點是：用計算機能夠識別的語言描述產(chǎn)品的特征及其設(shè)計領(lǐng)域?qū)＜业闹R和經(jīng)驗，建立相應(yīng)的知識庫及推理機，再利用已存儲的領(lǐng)域知識和建立的推理機實現(xiàn)產(chǎn)品的方案設(shè)計。 二、機械設(shè)計技術(shù)的發(fā)展趨勢 1、優(yōu)良性能設(shè)計技術(shù) 優(yōu)良性能設(shè)計是以提高機械產(chǎn)品綜合性能為目的的設(shè)計技術(shù)，在對機械及其零件進(jìn)行材料、結(jié)構(gòu)和尺寸設(shè)計的前提下，運用摩擦學(xué)及斷裂力學(xué)等一系列科研成果，從個體設(shè)計到系統(tǒng)設(shè)計，并從深度和廣度上拓展此項設(shè)計技術(shù)的內(nèi)涵和外延。優(yōu)良性能設(shè)計技術(shù)包括以下幾種設(shè)計技術(shù)：可靠性設(shè)計、系統(tǒng)動態(tài)設(shè)計、防疲勞斷裂設(shè)計、摩擦學(xué)設(shè)計、防腐蝕設(shè)計、狀態(tài)監(jiān)測補償與控制技術(shù)等等。這是綜合眾多學(xué)科成果以提高產(chǎn)品優(yōu)良性能為出發(fā)點的一門應(yīng)用工程技術(shù)。它研究的問題是：產(chǎn)品和系統(tǒng)的故障原因、消除和預(yù)防等問題；對結(jié)構(gòu)動態(tài)特性，如固有頻率、振型、動態(tài)響應(yīng)、運動穩(wěn)定性等進(jìn)行分析、評價與設(shè)計，以謀求結(jié)構(gòu)系統(tǒng)在工作過程中受到各種預(yù)期可能的瞬變載荷及環(huán)境作用時，仍然保持良好的動態(tài)性能與工作狀態(tài)，并具有足夠的穩(wěn)定性；產(chǎn)品的防腐蝕結(jié)構(gòu)、強度及方法設(shè)計，材料的選擇及其加工制造工藝的制訂，設(shè)備預(yù)期壽命概率和可靠性分析等；對機械產(chǎn)品在運行狀態(tài)下各種參數(shù)進(jìn)行定量檢測和分析，從而作出故障產(chǎn)生原因和部位的正確判斷等等問題。 2、競爭優(yōu)勢創(chuàng)建設(shè)計技術(shù) 競爭機制和供求關(guān)系是市場經(jīng)濟的兩大特點，在市場經(jīng)濟體制下要求生產(chǎn)設(shè)計人員要用新觀點、新原理和新功能來設(shè)計不斷滿足顧客需要的新產(chǎn)品，使企業(yè)在激烈競爭中始終處于不敗之地。 競爭優(yōu)勢創(chuàng)建設(shè)計技術(shù)包括以下幾種設(shè)計技術(shù)：產(chǎn)品創(chuàng)新設(shè)計、降低成本設(shè)計、快速設(shè)計、仿真與虛擬設(shè)計、智能設(shè)計、廣義優(yōu)化設(shè)計、造型色彩設(shè)計。它研究的問題是：產(chǎn)品的不斷更新；在保證功能和質(zhì)量的前提下，通過降低成本來提高產(chǎn)品經(jīng)濟性以加強競爭優(yōu)勢；縮短產(chǎn)品開發(fā)周期使產(chǎn)品投放市場的時間來提高產(chǎn)品競爭力；利用計算機仿真技術(shù)和計算機虛擬現(xiàn)實系統(tǒng)建立實際或聯(lián)想的系統(tǒng)模型，并在不同條件下，對模型進(jìn)行動態(tài)運行；使用智能 ICAD系統(tǒng)既具有數(shù)值計算和圖形處理能力，又具有知識處理能力，對設(shè)計的全過程提供智能化的計算機支持；構(gòu)思與表達(dá)由計算機輔助設(shè)計效果圖及電子模型和由快速成型方式完成精確效果模型。 3、全壽命周期設(shè)計技術(shù) 設(shè)計產(chǎn)品時不僅要考慮產(chǎn)品的功能和結(jié)構(gòu)，而且要設(shè)計產(chǎn)品的全壽命周期，即要設(shè)計產(chǎn)品的規(guī)劃、設(shè)計、制造、營銷、運行、使用、維修保養(yǎng)，直到回收再處置的全過程。全壽命周期設(shè)計意味著：在設(shè)計階段就要考慮到產(chǎn)品生命歷程的所有環(huán)節(jié)，以求產(chǎn)品全壽命周期設(shè)計的綜合優(yōu)化。 全壽命周期設(shè)計技術(shù)包括以下三種設(shè)計技術(shù)：并行設(shè)計、面向制造的新技術(shù)、產(chǎn)品數(shù)據(jù)管理技術(shù)。它研究的問題是：在產(chǎn)品開發(fā)的初始階段，即規(guī)劃和設(shè)計階段，就以并行的方式綜合考慮其生命周期中所有后續(xù)階段，包括工藝規(guī)劃、制造、裝配、試驗、檢驗、營銷、運輸、使用、維修、保養(yǎng)，直至回收處置等環(huán)節(jié)，降低產(chǎn)品成本，提高產(chǎn)品質(zhì)量；根據(jù)制造方法全面評價和及時改進(jìn)產(chǎn)品設(shè)計，可以得到綜合目標(biāo)較優(yōu)的設(shè)計方案，并可爭取產(chǎn)品設(shè)計和制造的一次成功；管理在產(chǎn)品生命鏈各環(huán)節(jié)中產(chǎn)生的或者所需要的大量數(shù)據(jù)和信息，包括工程規(guī)范、文檔、圖紙、CAE/CAD/CAM 文件、產(chǎn)品結(jié)構(gòu)模型、產(chǎn)品設(shè)計結(jié)果、產(chǎn)品訂單、供應(yīng)商狀況以及產(chǎn)品工作流程等，做到將正確的數(shù)據(jù)或信息在適當(dāng)時間傳遞到正確的位置或傳遞給相應(yīng)的人，這是產(chǎn)品全壽命周期數(shù)據(jù)管理技術(shù)研究的根本內(nèi)容。 4、綠色產(chǎn)品設(shè)計技術(shù) 綠色產(chǎn)品設(shè)計技術(shù)是在產(chǎn)品生命周期中，按符合環(huán)境保護(hù)、資源利用率最高、能源消耗最低的要求進(jìn)行設(shè)計的技術(shù)。 它包括以下幾種技術(shù)：面向環(huán)境設(shè)計、面向能源設(shè)計、面向材料設(shè)計、人機工程設(shè)計等。它研究的問題是：在產(chǎn)品整個生命周期內(nèi)，考慮產(chǎn)品的環(huán)境屬性即可拆性、可回收性、可維護(hù)性、可重復(fù)利用性和人身健康及安全性等，并將其作為設(shè)計目標(biāo)，使產(chǎn)品滿足環(huán)境目標(biāo)的要求；用對環(huán)境影響最小和資源消耗最少的能源供給方式來支持產(chǎn)品的整個生命周期，并以最小的代價來獲得能量的可靠回收和重新利用；合理選用材料，在產(chǎn)品整個壽命周期中的每一階段，以材料對環(huán)境的影響有效利用作為控制目標(biāo)；依據(jù)人的心理和生理特征，利用科學(xué)技術(shù)成果和數(shù)據(jù)設(shè)計技術(shù)系統(tǒng)，使之符合人的使用要求，改善環(huán)境和優(yōu)化人機系統(tǒng)，隨之達(dá)到最佳配合，以最小的勞動代價換取最大的經(jīng)濟成果。 隨著微電子技術(shù)、信息技術(shù)、網(wǎng)絡(luò)技術(shù)等迅猛發(fā)展，現(xiàn)代設(shè)計技術(shù)不斷與機械設(shè)計技術(shù)相結(jié)合。計算機技術(shù)的發(fā)展，給現(xiàn)代機械設(shè)計注入了新的生機和活力，機械設(shè)計逐漸向數(shù)字化、網(wǎng)絡(luò)化方向發(fā)展。不同專業(yè)的技術(shù)人員可以不受地域的限制，實現(xiàn)信息的交流和共享，進(jìn)而快速開發(fā)出所需產(chǎn)品，提高產(chǎn)品設(shè)計的一次成功率。 Mechanical design and development trend The first step in the manufacture of any product is design. Mechanical design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs. It is a vast field of engineering technology which not only concerns itself with the original conception of the product in terms of its size, shape and construction details, but also considers the various factors involved in the manufacture ，marketing and use of the product. People who perform the various functions of machine design are typically called designers, or design engineers. Mechanical design is a creative activity. However, in addition to being innovative, a design engineer must also have a solid background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, strength of materials and manufacturing processes. Here we take the selection of materials as an example. During recent years the selection of engineering materials has assumed great importance. Moreover, the process should be one of continual reevaluation. New materials often become available and there may be a decreasing availability of others. Concerns regarding environment pollution, recycling and worker health and safety often impose new constraints. The desire for weight reduction or energy savings may dictate the use of different materials. Pressures from domestic and international competition, increased serviceability requirements, and customer feedback may all promote materials reevaluation. The extent of product liability actions, often the result of improper material use, has had a marked impact. In addition, the interdependence between material and their processing has become better recognized. The development of new processes often forces reevaluation of the material being processed. Therefore, it is imperative that design and manufacturing engineers exercise considerable care in selecting, specifying, and utilizing materials if they are to achieve satisfactory results at reasonable cost and still assure quality. In mechanics processing，milling and grinding are always under the consideration of the designers. With the exceptions of turning and drilling, milling is undoubtedly the most widely used method of removing metal. Well suited and readily adapted to the economical production of any quantity of parts, the almost unlimited versatility of the milling process merits the attention and consideration of designers seriously concerned with the manufacture of their product. Grinding is one of the most widely used methods of finishing parts to extremely close tolerances and low surface roughness. Currently, there are grinders for almost every type of grinding operation. Particular design features of a part dictate to a large degree the type of grinding machine required. Where processing costs are excessive, parts redesigned to utilize a less expensive, higher output grinding method may be well worthwhile. For example, wherever possible the production economy of center less grinding should be taken advantage of by proper design consideration. Although grinding is usually considered a finishing operation, it is often employed as a complete machining process on work which can be ground down form rough condition without being turned or otherwise machined. Thus many types of forgings and other parts are finished completely with the grinding wheel at appreciable savings of time and expense. Besides, the application of nontraditional manufacturing processes will bring more bold and innovative design. The conventional manufacturing processes in use today for material removal primarily rely on electric motors and hard tool materials to perform tasks such as sawing, drilling, and broaching. Conventional forming operations are performed with the energy from electric motors, hydraulics, and gravity. Likewise, material joining is conventionally accomplished with thermal energy sources such as burning gases and electric arcs. In contrast, nontraditional manufacturing processes harness energy sources considered unconventional by yesterday’s standards. Material removal can now be accomplished with electrochemical reactions, high-velocity jets of liquids and abrasives. Materials that in the past have been extremely difficult to form, are now formed with magnetic fields, explosives, and the shock waves from powerful electric sparks.. Material-joining capabilities have been expanded with the use of high-frequency sound waves and beams of electrons. In the past 50 years, over 20 different nontraditional manufacturing processes have been invented and successfully implemented into production. The reason there are such a large number of nontraditional processes is the same reason there are such a large number of conventional processes ; each process has its own characteristic attributes and limitations, hence no one process is best for all manufacturing situations. In other cases, nontraditional processes are used to reduce the number of rejects experienced by the old manufacturing method by increasing repeatability, reducing in-process breakage of fragile work pieces, or by minimizing detrimental effects on work piece properties. As stated previously, the purpose of mechanical design is to produce a product which will serve a need for man. Inventions, discovery and scientific knowledge by themselves do not necessarily benefit people; only if they are incorporated into a designed product will a benefit be derived. It should be recognized, therefore, that a human need must be identified before a particular product is designed. Mechanical design should be considered to be an opportunity to use innovative talents to envision a design of a product, to analyze the system and then make sound judgments on how the product is to be manufactured. It is important to understand the fundamentals of engineering rather than memorize mere facts and equations. There are no facts or equations which alone can be used to provide all the correct decisions required to produce a good design. On the other hand, any calculations made must be done with the utmost care and precision. Good design require trying new ideas and being willing to take a certain amount of risk, knowing that if the new idea not work the existing method can be reinstated. Thus a designer must have patience, since there is no assurance of success for the time and effort expended. Creating a completely new design generally requires that many old and well-established methods be thrust aside. This is not easy since many people cling to familiar ideas, techniques and attitudes. A design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what new, untried ideas should be incorporated. During the beginning stages of design, creativity should be allowed to flourish without a great number of constraints. Even though many impractical ideas may arise, it is usually easy to eliminate them in the early stages of design before firm details are required by manufacturing. In this way, innovative ideas are not inhibited. Quite often, more than one design is developed, up to the point where they can be compared against each other. It is entirely possible that the design which is ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall promise. Another important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they are to be incorporated. Initially, the designer must communicate a preliminary design to get management approval. This is usually done by verbal discussions in conjunction with drawing layouts and written material. To communicate effectively, the following questions must be answered :(1) Does the design really serve a human need(2) Will it be competitive with existing products of rival companies(3) Is it economical to produce(4) Can it be readily maintained(5)Will it sell and make a profit. Besides, for the producers and administrative personnel of the products, mechatronics has many advantages as follows:(1) High Capital Equipment Utilization Typically, the throughput for a set of machines in a mechatronics system will be up to three times that for the same machines in a stand-alone job shop environment. (2) Reduced Capital Equipment Costs, the high utilization of equipment results in the need for fewer machines in the mechatronic system to do the same work as in a conventional system. (3) Reduced Direct Labor Costs ,Since each machine is completely under computer control, full-time oversight is not required. (4) Reduced Work-in-Process Inventory and Lead Time , The reduction of work-in-process in a is quite dramatic when compared to a job-shop environment. (5) Responsiveness to Changing Production Requirements ,A mechatronic system has the inherent flexibility to manufacture different products as the demands of the marketplace change or as engineering design changes are introduced.(6) Ability to Maintain Production , Many mechatronic systems are designed to degrade rationally when one or more machines fail. (7) High Product Quality , Sometimes, an over looked advantage of a mechatronic system especially when compared to machines that have not been federated into a cooperative system, is improved product quality. (8) Operational Flexibility, Operational flexibility offers a significant of productivity. (9) Capacity Flexibility, With reasonable planning for available floor, a mechatronic system initially can be designed for low production, and provide necessary additional productivity as well. Only time will provide the true answers to the preceding questions, but the product should be designed, manufactured and marked only with initial affirmative answers. The design engineer also must communicate the finalized design to manufacturing through the use of detail and assembly drawings. Quite often, a problem will occur during the manufacturing cycle. It may be that a change is required in the dimensioning or tolerance of part so that it can be more readily produced. This falls in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected. In other cases, a deficiency in the design may appear during assembly or testing just prior to shipping. These realities simply bear out the fact that design is a living process. There is always a better way to do it and the designer should constantly strive towards finding that better way. The competent engineer should not be afraid of the possibility of not succeeding in a presentation. In fact, occasional failure should be expected because failure or criticism seems to accompany every really creative idea. There is a great deal to be learned form a failure and the greatest gains are obtained by those willing to risk defeat. In the final analysis, the real failure would lie in deciding not to make the presentation at all. With the development of science and technology, increase product functional requirements, especially the increasing complexity of products, upgrading speed in life is shortened, the design of products, especially for mechanical product design scheme is more and more high. The characteristics of modern design is the design for the market and users, not only to achieve the basic functions of modern design products, should embody the humanized design concept and environmental protection. The development trend of the modern design method of machinery and mechanical design technology are discussed. 一,Modern design method of mechanical products 1, Intelligent The main characteristics of intelligent design method is: according to the design theory, with the help of 3D graphics software, intelligent design software and virtual reality technology, design and development of products and multimedia tools such as the expression of the product concept, structure description of the product. 2, Systematic The main characteristics of the design method of the system is: the design as a system composed of several design elements, each design elements of both independent and are closely related to, and has the hierarchy, with all the design elements, design system can achieve the required tasks. 3, Modular The main features of the modular design method are as follows: the realization of a certain function as a structural module, through the combination of structural modules, to achieve product design 4, Based on product feature knowledge The main characteristics of the product design method based on the characteristics of knowledge are: using computer to describe the characteristics and design experts in the field of product knowledge and experience to identify the language knowledge base and establish the corresponding reasoningmachine to use the storage areas have established knowledge and reasoning machine design and Realization of product solutions. 二, The development trend of mechanical design technology 1, Excellent performance design technology Excellent performance design is a design technology to improve the comprehensive performance of mechanical products, the materials of machinery and parts, structure and size of the design under the premise of the tribology and fracture mechanics and a series of research results, from the individual design to system design, and expand the connotation and extension of this design technology in depth and breadth the. Excellent performance design technology includes the foll