1745_溝槽凸輪機(jī)構(gòu)的設(shè)計(jì)和運(yùn)動(dòng)仿真,溝槽,凸輪,機(jī)構(gòu),設(shè)計(jì),以及,運(yùn)動(dòng),仿真 摘 要在當(dāng)今經(jīng)濟(jì)全球化、市場(chǎng)競(jìng)爭(zhēng)日趨激烈的時(shí)代，新產(chǎn)品的開(kāi)發(fā)時(shí)間成為企業(yè)能否在激烈的市場(chǎng)競(jìng)爭(zhēng)中取勝的關(guān)鍵因素。傳統(tǒng)的產(chǎn)品設(shè)計(jì)過(guò)程中重復(fù)計(jì)算、重復(fù)建模等工作量很大，一直困擾著產(chǎn)品開(kāi)發(fā)人員，嚴(yán)重影響了產(chǎn)品的設(shè)計(jì)質(zhì)量和效率。這種現(xiàn)象在凸輪的設(shè)計(jì)中尤為突顯。針對(duì)這一問(wèn)題，本課題利用 Pro/E 軟件中的運(yùn)動(dòng)仿真模塊對(duì)凸輪機(jī)構(gòu)運(yùn)動(dòng)進(jìn)行模擬仿真。本論文的主要研究?jī)?nèi)容有：1、溝槽凸輪設(shè)計(jì)2、溝槽凸輪機(jī)構(gòu)的零部件的實(shí)體建模3、溝槽凸輪機(jī)構(gòu)的運(yùn)動(dòng)仿真關(guān)鍵詞：溝槽凸輪 實(shí)體建模 運(yùn)動(dòng)仿真 ABSTRACTIn the competitive era of economic globalization and increasingly markets, the development time for new product become a key factor to win in the fierce competition market. The traditional product design process of double counting, such as repeated heavy workload and modeling have troubled the product development staff, a serious impact on product design quality and efficienct. This phenomenon is particularly on the design of cam highlights. Address with this problem, the subject of using the movement simulation module of Pro / E software on the cam movement simulation.In this paper, the main research contents are as follows:1. Designing the groove cam2. Modeling the mechanism parts of groove cam 3. Motion simulating of the groove cam mechanism Key Words: Cam groove, Modeling, Motion Simulation目 錄緒 論 ..................................................................11.1 本文研究的背景 ....................................................11.1.1 我國(guó)凸輪機(jī)構(gòu)的研究現(xiàn)狀 ........................................11.1.2 我國(guó)凸輪機(jī)構(gòu) CAD/CAM 的研究現(xiàn)狀 ................................11.1.3 國(guó)外凸輪機(jī)構(gòu)及其 CAD/CAM 的研究現(xiàn)狀 ............................21.1.4 我國(guó)凸輪 CAD 系統(tǒng)存在的問(wèn)題 ....................................21.2 本文研究的主要內(nèi)容 ................................................21.3 本文意義 ..........................................................31.4 本章小結(jié) ..........................................................32 凸輪機(jī)構(gòu)設(shè)計(jì)分析 .....................................................42.1 從動(dòng)件運(yùn)動(dòng)規(guī)律的選取 ..............................................42.1.1 從動(dòng)件常用的基本運(yùn)動(dòng)規(guī)律 ......................................42.1.2 從動(dòng)件運(yùn)動(dòng)規(guī)律的選取原則 ......................................42.2 凸輪機(jī)構(gòu)基本尺寸的設(shè)計(jì) ............................................52.2.1 凸輪機(jī)構(gòu)壓力角和基圓半徑 ......................................52.2.2 凸輪機(jī)構(gòu)的偏距 ................................................62.2.3 凸輪滾子半徑 ..................................................62.3 凸輪輪廓設(shè)計(jì) ......................................................72.4 機(jī)構(gòu)簡(jiǎn)介 ..........................................................82.5 本章小結(jié) ..........................................................93 凸輪機(jī)構(gòu)的實(shí)體建模與裝配 ............................................103.1 Pro/E 軟件簡(jiǎn)介 ...................................................103.2 零部件的實(shí)體建模 .................................................103.3 裝配原理簡(jiǎn)介與裝配模型的建立 .....................................123.3.1 Pro/E 仿真裝配原理介紹 ........................................123.3.2 裝配模型建立 .................................................143.4 本章小結(jié) .........................................................174 凸輪機(jī)構(gòu)的運(yùn)動(dòng)仿真 ..................................................184.1 計(jì)算機(jī)仿真概述 ...................................................184.1.1 計(jì)算機(jī)仿真的基本概念及特點(diǎn) ...................................184.1.2 計(jì)算機(jī)仿真技術(shù)在制造業(yè)中的應(yīng)用 ...............................184.2 Pro/E 運(yùn)動(dòng)仿真簡(jiǎn)介 ...............................................194.2.1 Pro/E 運(yùn)動(dòng)仿真的特點(diǎn) ..........................................194.2.2 Pro/E 運(yùn)動(dòng)仿真的基本術(shù)語(yǔ) ......................................204.2.3 Pro/E 運(yùn)動(dòng)仿真的步驟 ..........................................214.3 凸輪機(jī)構(gòu)的運(yùn)動(dòng)仿真 ...............................................214.3.1 設(shè)置機(jī)構(gòu)環(huán)境 .................................................214.3.2 分析 .........................................................254.4 本章小結(jié) .........................................................29結(jié) 論 .................................................................30致 謝 .................................................................31參考文獻(xiàn) ...............................................................320 緒 論1.1 本文研究的背景1.1.1 我國(guó)凸輪機(jī)構(gòu)的研究現(xiàn)狀凸輪機(jī)構(gòu)是典型的常用機(jī)構(gòu)之一。凸輪機(jī)構(gòu)是能使從動(dòng)件按照給定的運(yùn)動(dòng)規(guī)律運(yùn)動(dòng)的高副機(jī)構(gòu)，可以實(shí)現(xiàn)任意給定的位移、速度、加速度等運(yùn)動(dòng)規(guī)律，而且與其它機(jī)構(gòu)配合可以實(shí)現(xiàn)復(fù)雜的運(yùn)動(dòng)要求。工程中，幾乎所有簡(jiǎn)單的、復(fù)雜的重復(fù)性機(jī)械動(dòng)作都可由凸輪機(jī)構(gòu)或者包括凸輪機(jī)構(gòu)的組合機(jī)構(gòu)來(lái)實(shí)現(xiàn)。又由于凸輪機(jī)構(gòu)具有平穩(wěn)性好，重復(fù)精度高，運(yùn)動(dòng)特性良好，機(jī)構(gòu)的構(gòu)件少，體積小，剛性大，周期控制簡(jiǎn)單，可靠性好，壽命長(zhǎng)等優(yōu)點(diǎn)，因而是現(xiàn)代工業(yè)生產(chǎn)設(shè)備中不可缺少的機(jī)構(gòu)之一，被廣泛用于各種自動(dòng)機(jī)中。例如，自動(dòng)包裝機(jī)、自動(dòng)成型機(jī)、自動(dòng)裝配機(jī)、自動(dòng)機(jī)床、紡織機(jī)械、農(nóng)用機(jī)械、印刷機(jī)械加工中心環(huán)刀機(jī)構(gòu)、高速壓力機(jī)械等。我國(guó)以前對(duì)凸輪機(jī)構(gòu)深入系統(tǒng)地研究較少，僅在內(nèi)燃機(jī)配氣凸輪機(jī)構(gòu)有較深入研究。1990 年以來(lái)，有關(guān)凸輪機(jī)構(gòu)的應(yīng)用研究取得了一大批成果，許多己應(yīng)用于生產(chǎn)。陜西科技大學(xué)完成的(高速高精度間歇轉(zhuǎn)位凸輪分度機(jī)構(gòu)CAD/CAM)， 1995 年獲陜西省科技進(jìn)步二等獎(jiǎng)：開(kāi)發(fā)的 “凸輪分度機(jī)構(gòu)傳動(dòng)裝置”獲中國(guó)輕工總會(huì)優(yōu)秀新產(chǎn)品一等獎(jiǎng)；加工弧面凸輪的“XK5001 雙回轉(zhuǎn)坐標(biāo)數(shù)控銑床”獲實(shí)用新型專(zhuān)利。天津大學(xué)關(guān)于分度凸輪機(jī)構(gòu)的研究，得到了國(guó)家自然科學(xué)基金的支持；研究開(kāi)發(fā)的兩片式平行分度凸輪機(jī)構(gòu)達(dá)到了國(guó)內(nèi)領(lǐng)先水平。此外，上海交通大學(xué)、大連輕工業(yè)學(xué)院、合肥工業(yè)大學(xué)和山東大學(xué)(山東工業(yè)大學(xué)) 等在理論應(yīng)用研究方面都取得了很多具有國(guó)際或國(guó)內(nèi)先進(jìn)水平的科研成果。盡管我國(guó)對(duì)凸輪機(jī)構(gòu)的應(yīng)用和研究也有多年的歷史，對(duì)凸輪機(jī)構(gòu)的設(shè)計(jì)、運(yùn)動(dòng)規(guī)律、輪廓線、動(dòng)力學(xué)、優(yōu)化設(shè)計(jì)等方面的研究都取得了很多科研成果。但是，與先進(jìn)國(guó)家相比，我國(guó)對(duì)凸輪機(jī)構(gòu)的設(shè)計(jì)和制造上都還存在較大的差距，尤其在制造方面。在國(guó)外核心技術(shù)也只是集中在少數(shù)的幾家公司和科研機(jī)構(gòu)中，而且由于技術(shù)保密等因素，具有一定參考價(jià)值的相關(guān)資料很少公開(kāi)發(fā)表。這樣就在無(wú)形中制約著我國(guó)凸輪機(jī)構(gòu)設(shè)計(jì)和制造水平的提高，造成高速、高精度的凸輪機(jī)構(gòu)必須依賴(lài)進(jìn)口的被動(dòng)局面。1.1.2 我國(guó)凸輪機(jī)構(gòu) CAD/CAM 的研究現(xiàn)狀我國(guó)凸輪機(jī)構(gòu)運(yùn)動(dòng)學(xué)的理論研究己經(jīng)達(dá)到了較高的水平，為凸輪機(jī)構(gòu)設(shè)計(jì)奠定了堅(jiān)實(shí)的理論基礎(chǔ)。當(dāng)今，凸輪機(jī)構(gòu)設(shè)計(jì)己廣泛采用解析法并借助于計(jì)算機(jī)來(lái)完成，數(shù)控機(jī)床用于凸輪加工也有很長(zhǎng)的歷史。我國(guó)發(fā)表的凸輪機(jī)構(gòu)CAD/CAM 方面的文獻(xiàn)較多。但這些凸輪的 CAD/CAM 系統(tǒng)核心技術(shù)僅被某些1 企業(yè)所有，并未在市場(chǎng)上以商品軟件的形式出現(xiàn)。迄今為止我國(guó)凸輪機(jī)構(gòu)CAD/CAM 技術(shù)仍未得到有效的推廣應(yīng)用。另外，由于凸輪專(zhuān)用軟件開(kāi)發(fā)更新的速度慢，遠(yuǎn)遠(yuǎn)跟不上當(dāng)今計(jì)算機(jī)軟、硬件的發(fā)展速度，使得現(xiàn)有凸輪機(jī)構(gòu)CAD/CAM 軟件己大為落后，不能完全適應(yīng)廣大設(shè)計(jì)人員的要求。1.1.3 國(guó)外凸輪機(jī)構(gòu)及其 CAD/CAM 的研究現(xiàn)狀自上世紀(jì)三十年代以來(lái)，人們就開(kāi)始了對(duì)凸輪機(jī)構(gòu)的研究，并且研究工作隨著新技術(shù)、新方法的產(chǎn)生和應(yīng)用在不斷深化。60 年代后，對(duì)凸輪的研究逐步成熟起來(lái)，出現(xiàn)了較完整的運(yùn)動(dòng)規(guī)律的設(shè)計(jì)，在梯薩爾的著作中就采用了多項(xiàng)式運(yùn)動(dòng)規(guī)律。對(duì)凸輪機(jī)構(gòu)的研究不斷向縱深方向發(fā)展，開(kāi)始對(duì)凸輪進(jìn)行有限元分析及非線性問(wèn)題的研究，同時(shí)，歐美各國(guó)學(xué)者對(duì)高速凸輪的研究也有新的突破，許多學(xué)者發(fā)表了關(guān)于凸輪機(jī)構(gòu)的優(yōu)化設(shè)計(jì)、凸輪振動(dòng)、動(dòng)態(tài)響應(yīng)等方面的論文。日木在凸輪機(jī)構(gòu)方面的研究也有巨大貢獻(xiàn)。在機(jī)構(gòu)設(shè)計(jì)方面，致力于尋求凸輪機(jī)構(gòu)的精確解和使凸輪曲線多樣化，以適應(yīng)新的要求。并加強(qiáng)了對(duì)凸輪機(jī)構(gòu)動(dòng)力學(xué)和振動(dòng)方面的研究和標(biāo)準(zhǔn)化研究，發(fā)展成批生產(chǎn)的標(biāo)準(zhǔn)凸輪機(jī)構(gòu)，在此基礎(chǔ)上進(jìn)一步拓展凸輪機(jī)構(gòu) CAD/CAM 系統(tǒng)。美國(guó)、日木等國(guó)家的一些凸輪制造企業(yè)開(kāi)發(fā)了供木企業(yè)使用的凸輪 CAD/CAM 系統(tǒng)，有的還形成了商業(yè)化軟件，如日木 SUNCALL 公司開(kāi)發(fā)的 HYMOCAM 系統(tǒng)等。1.1.4 我國(guó)凸輪 CAD 系統(tǒng)存在的問(wèn)題通過(guò)調(diào)研以及查閱大量文獻(xiàn)資料，我國(guó)現(xiàn)有的凸輪 CAD 系統(tǒng)存在如下問(wèn)題：(1)多數(shù)是在 AutoCAD 基礎(chǔ)上進(jìn)行二次開(kāi)發(fā)而成的，不具有三維建模功能；(2)沒(méi)有商品化的凸輪 CAD 系統(tǒng)出現(xiàn)；(3)現(xiàn)有的基于 Pro/ENGINEER 的凸輪 CAD 系統(tǒng)中，融入先進(jìn)的數(shù)據(jù)庫(kù)管理技術(shù)的還沒(méi)有主要原因是由于 Pro/TOOLKIT 開(kāi)發(fā)界面的功能很弱，而且根木沒(méi)有連接數(shù)據(jù)庫(kù)的功能；(4)由于凸輪專(zhuān)用軟件開(kāi)發(fā)更新的速度慢，遠(yuǎn)遠(yuǎn)跟不上當(dāng)今計(jì)算機(jī)硬件的發(fā)展速度，使得現(xiàn)有的平面凸輪機(jī)構(gòu) CAD 應(yīng)用軟件已大為落后，不能適應(yīng)實(shí)際生產(chǎn)的需要；(5)集成化、智能化和網(wǎng)絡(luò)化很不完善。1.2 本文研究的主要內(nèi)容本文研究的主要內(nèi)容是關(guān)于溝槽凸輪機(jī)構(gòu)的運(yùn)動(dòng)仿真。首先介紹了溝槽凸輪的設(shè)計(jì)，然后在 Pro/E 軟件中實(shí)現(xiàn)其實(shí)體建模和裝配，最后才對(duì)裝配好的溝槽凸輪機(jī)構(gòu)進(jìn)行運(yùn)動(dòng)仿真，并對(duì)仿真結(jié)果進(jìn)行了分析。2 1.3 本文意義對(duì)凸輪機(jī)構(gòu)進(jìn)行運(yùn)動(dòng)仿真，可以根據(jù)仿真結(jié)果以及碰撞干涉檢查，對(duì)設(shè)計(jì)的零件進(jìn)行結(jié)構(gòu)等方面的修改，大大簡(jiǎn)化機(jī)構(gòu)的設(shè)計(jì)開(kāi)發(fā)過(guò)程，縮短開(kāi)發(fā)周期，減少開(kāi)發(fā)費(fèi)用，同時(shí)提高產(chǎn)品質(zhì)量。1.4 本章小結(jié)首先本章對(duì)課題的研究背景進(jìn)行了詳細(xì)的介紹，然后又對(duì)本文的研究?jī)?nèi)容和本文意義進(jìn)行介紹。3 2 凸輪機(jī)構(gòu)設(shè)計(jì)分析2.1 從動(dòng)件運(yùn)動(dòng)規(guī)律的選取運(yùn)動(dòng)規(guī)律設(shè)計(jì)包括對(duì)所設(shè)計(jì)的凸輪機(jī)構(gòu)輸出件的運(yùn)動(dòng)提出的所有給定要求。例如，推程、回程運(yùn)動(dòng)角、遠(yuǎn)休止角、近休止角、行程以及推程、回程的運(yùn)動(dòng)規(guī)律曲線形狀，都屬于運(yùn)動(dòng)規(guī)律設(shè)計(jì)。所謂凸輪曲線并不是凸輪輪廓的形狀曲線，而是凸輪驅(qū)動(dòng)從動(dòng)件的運(yùn)動(dòng)曲線。研究凸輪曲線的目的在于用最短時(shí)間、最圓滑、無(wú)振動(dòng)、耗能少的方式來(lái)驅(qū)動(dòng)從動(dòng)件。凸輪曲線特性?xún)?yōu)良與否直接影響凸輪機(jī)構(gòu)的精度、效率和壽命。從動(dòng)件的運(yùn)動(dòng)情況，是由凸輪輪廓曲線的形狀決定的。一定輪廓曲線形狀的凸輪，能夠使從動(dòng)件產(chǎn)生一定規(guī)律的運(yùn)動(dòng)；反過(guò)來(lái)實(shí)現(xiàn)從動(dòng)件不同的運(yùn)動(dòng)規(guī)律，要求凸輪具有不同現(xiàn)狀的輪廓曲線，即凸輪的輪廓曲線與從動(dòng)件所實(shí)現(xiàn)的運(yùn)動(dòng)規(guī)律之間存在著確定的依從關(guān)系。因此，凸輪機(jī)構(gòu)設(shè)計(jì)的關(guān)鍵一步，是根據(jù)工作要求和使用場(chǎng)合，選擇或設(shè)計(jì)從動(dòng)件的運(yùn)動(dòng)規(guī)律。在設(shè)計(jì)凸輪機(jī)構(gòu)基木尺寸和凸輪輪廓之前，必須根據(jù)凸輪機(jī)構(gòu)的工作性能要求選擇從動(dòng)件的運(yùn)動(dòng)規(guī)律方程式，選擇不同的從動(dòng)件運(yùn)動(dòng)規(guī)律將直接影響凸輪機(jī)構(gòu)的基本尺寸設(shè)計(jì)、輪廓設(shè)計(jì)及凸輪機(jī)構(gòu)的運(yùn)動(dòng)性能等。2.1.1 從動(dòng)件常用的基本運(yùn)動(dòng)規(guī)律幾種常見(jiàn)的基木運(yùn)動(dòng)規(guī)律有三角函數(shù)運(yùn)動(dòng)規(guī)律(簡(jiǎn)諧運(yùn)動(dòng)規(guī)律、擺線運(yùn)動(dòng)規(guī)律及雙諧運(yùn)動(dòng)規(guī)律等)；簡(jiǎn)單多項(xiàng)式運(yùn)動(dòng)規(guī)律；等速運(yùn)動(dòng)規(guī)律(一次項(xiàng)運(yùn)動(dòng)規(guī)律)、等加等減速運(yùn)動(dòng)規(guī)律(二次項(xiàng)運(yùn)動(dòng)規(guī)律)等。2.1.2 從動(dòng)件運(yùn)動(dòng)規(guī)律的選取原則從動(dòng)件運(yùn)動(dòng)規(guī)律的選擇或設(shè)計(jì)，涉及到許多因素。除了需要滿(mǎn)足機(jī)械的具體工作要求外，還應(yīng)使凸輪機(jī)構(gòu)具有良好的動(dòng)力特性，同時(shí)又要考慮所設(shè)計(jì)的凸輪廓線便于加工，這些因素又往往是互相制約的。因此在選擇或設(shè)計(jì)運(yùn)動(dòng)規(guī)律時(shí)，必須根據(jù)使用場(chǎng)合、工作條件等分清主次，綜合考慮。下面是一些常用運(yùn)動(dòng)規(guī)律的適用場(chǎng)合：(l)等速運(yùn)動(dòng)規(guī)律在很多情況下能滿(mǎn)足凸輪機(jī)構(gòu)推程的工作要求，但是在從動(dòng)件行程的開(kāi)始和終止位置存在剛性沖擊，是運(yùn)動(dòng)特性最差的曲線，所以等速運(yùn)動(dòng)規(guī)律很少單獨(dú)使用，且不適用于中、高速。(2)等加速等減速運(yùn)動(dòng)規(guī)律的速度曲線連續(xù)，在所有曲線中其最大加速度值為最小，但在從動(dòng)件行程的開(kāi)始、終止和由正加速度變?yōu)樨?fù)加速度的中間位置，加速度的有限值突變將導(dǎo)致柔性沖擊，因而不能在中、高速場(chǎng)合使用。(3)余弦加速度運(yùn)動(dòng)規(guī)律消除了行程中間位置的加速度突變，且易于計(jì)算和加工，在中速時(shí)也能獲得合理的從動(dòng)件的運(yùn)動(dòng)。但當(dāng)這種運(yùn)動(dòng)規(guī)律用于升—停—回—停運(yùn)動(dòng)時(shí)，在行程的起始和終止位置因加速度突變而仍有柔性沖擊。當(dāng)4 這種規(guī)律用于升—回—升型運(yùn)動(dòng)時(shí)，則加速度曲線連續(xù)，沒(méi)有柔性沖擊。(4)正弦加速度運(yùn)動(dòng)規(guī)律用于升—?！亍＿\(yùn)動(dòng)時(shí)，從動(dòng)件在行程的起始和終止位置加速度無(wú)突變，因而無(wú)柔性沖擊，有利于機(jī)構(gòu)運(yùn)轉(zhuǎn)平穩(wěn)。但它用于升—?！亍＿\(yùn)動(dòng)時(shí)，在推程與回程的連接點(diǎn)處，躍度從有限的正值變?yōu)樨?fù)值，因而加速度曲線不連續(xù)。這種曲線要求機(jī)械加工的準(zhǔn)確性高于其他曲線。正弦加速度運(yùn)動(dòng)規(guī)律廣泛用于中速凸輪機(jī)構(gòu)，但不適于高速場(chǎng)合。2.2 凸輪機(jī)構(gòu)基本尺寸的設(shè)計(jì)凸輪機(jī)構(gòu)的基本尺寸對(duì)凸輪機(jī)構(gòu)的結(jié)構(gòu)、傳力性能都有重要的影響。凸輪機(jī)構(gòu)的基本參數(shù)選擇的不恰當(dāng)，則可能造成壓力角過(guò)大或產(chǎn)生運(yùn)動(dòng)失真現(xiàn)象。凸輪機(jī)構(gòu)的基本尺寸之間互相影響、互相制約，所以如何合理地設(shè)計(jì)這些基本尺寸，也是凸輪機(jī)構(gòu)設(shè)計(jì)中要解決的重要問(wèn)題。凸輪機(jī)構(gòu)基本尺寸的設(shè)計(jì)問(wèn)題是在給定從動(dòng)件運(yùn)動(dòng)規(guī)律和許用壓力角的條件下尋求一組適用的尺寸，從而使設(shè)計(jì)的凸輪機(jī)構(gòu)性能佳、壽命長(zhǎng)。溝槽凸輪機(jī)構(gòu)主要設(shè)計(jì)參數(shù)有：基圓半徑和偏距，滾子半徑，擺桿長(zhǎng)度等。為提高凸輪機(jī)構(gòu)傳力效果，希望機(jī)構(gòu)在推程中壓力角盡量小。一般來(lái)講，這些參數(shù)的選擇，除應(yīng)保證使從動(dòng)件能夠準(zhǔn)確地實(shí)現(xiàn)預(yù)期的運(yùn)動(dòng)規(guī)律外，還應(yīng)當(dāng)使機(jī)構(gòu)具有良好的受力狀況和緊湊的尺寸。2.2.1 凸輪機(jī)構(gòu)壓力角和基圓半徑凸輪壓力角是從動(dòng)件運(yùn)動(dòng)(速度)方向與傳動(dòng)軸線方向之間的夾角。壓力角是衡量凸輪機(jī)構(gòu)傳力特性好壞的一個(gè)重要參數(shù)。從減小推力、避免自鎖，使機(jī)構(gòu)具有良好的受力狀況來(lái)看，壓力角應(yīng)越小越好。同時(shí)設(shè)計(jì)凸輪機(jī)構(gòu)時(shí)，除了使機(jī)構(gòu)具有良好的受力狀況外，還希望機(jī)構(gòu)結(jié)構(gòu)緊湊。在實(shí)現(xiàn)相同運(yùn)動(dòng)規(guī)律的情況下，基圓半徑越大，凸輪的尺寸也越大。因此，要獲得輕便緊湊的凸輪機(jī)構(gòu)，就應(yīng)當(dāng)使基圓半徑盡可能地小。而基圓半徑 r 及偏距 e 與凸輪壓力角 有如下0 ?關(guān)系：tan = = (2—1)?0seds???20ers?當(dāng)凸輪逆時(shí)針轉(zhuǎn)動(dòng)、從動(dòng)件偏于凸輪軸心左側(cè)或當(dāng)凸輪順時(shí)針轉(zhuǎn)動(dòng)，從動(dòng)件偏于凸輪軸心右側(cè)時(shí)，壓力角的計(jì)算公式：tan = (2—2)?20ersds???5 由計(jì)算公式可知壓力角和基圓半徑兩者是互相制約的，在一般情況下，為了保證設(shè)計(jì)的凸輪機(jī)構(gòu)既有較好的傳力特性又具有較緊湊的尺寸，設(shè)計(jì)時(shí)兩者應(yīng)同時(shí)考慮。為了保證凸輪機(jī)構(gòu)順利工作，規(guī)定了壓力角的許用值 ，在使???的前提下，選取盡可能小的基圓半徑。推薦推程的許用壓力角為：移????max動(dòng)推桿 =30 ~38 ；當(dāng)要求凸輪尺寸盡可能小時(shí)可取 =45 ；擺動(dòng)推桿0 0=40 ~45 ；回程時(shí)，由于推桿通常受力較小而無(wú)自鎖問(wèn)題，故許用壓力角可以取大一點(diǎn)，通常取 =70 ~80 。???0在實(shí)際工作中，一般都是先根據(jù)具體情況預(yù)選一個(gè)凸輪的基圓半徑，待凸輪輪廓曲線設(shè)計(jì)完成后，在檢查其最大壓力角是否滿(mǎn)足 。????max2.2.2 凸輪機(jī)構(gòu)的偏距由式(2 —1)和式 (2—2)可看出，凸輪的轉(zhuǎn)動(dòng)方向和從動(dòng)件的偏置方向不同，增大偏距。壓力角的變化就不同。若推程壓力角減小，則回程壓力角將增大，即通過(guò)增加偏距來(lái)減小推程壓力角，是以增大回程壓力角為代價(jià)的。在設(shè)計(jì)凸輪機(jī)構(gòu)時(shí)，如果壓力角超過(guò)了許用值、而機(jī)械的結(jié)構(gòu)空間又不允許增大基圓半徑，則可通過(guò)選取從動(dòng)件適當(dāng)?shù)钠梅较騺?lái)獲取較小的推程壓力角。即在移動(dòng)滾子從動(dòng)件盤(pán)形凸輪機(jī)構(gòu)的情況下，選擇從動(dòng)件偏置的主要目的是為了減小機(jī)構(gòu)推程時(shí)的壓力角。從動(dòng)件偏置方向選擇的原則是：若凸輪逆時(shí)針回轉(zhuǎn)，則應(yīng)使從動(dòng)件軸線偏于凸輪軸心右側(cè)；若凸輪順時(shí)針回轉(zhuǎn)，則應(yīng)使從動(dòng)件軸線偏于凸輪軸心左側(cè)。2.2.3 凸輪滾子半徑當(dāng)凸輪廓線為內(nèi)凹廓線時(shí)，實(shí)際廓線的曲率半徑 、理論廓線的曲率半徑a?、滾子半徑 r 三者之間有如下的關(guān)系： = +r 。而當(dāng)凸輪廓線為外凸廓線? ar時(shí)，實(shí)際廓線的曲率半徑 、理論廓線的曲率半徑 、滾子半徑 r 三者之間的a?關(guān)系是 = ﹣r ，當(dāng) =r 時(shí)，則 =0，即實(shí)際廓線將出現(xiàn)尖點(diǎn)，由于尖點(diǎn)處ara極易磨損，故不能實(shí)用；若 鍵選擇 “xf1_位移” 、 “xf2_速度”和“xf3_ 加速度 ”，鉤選“分別繪制測(cè)量圖形（Graph measures separately） ”項(xiàng)，在“結(jié)果集（Result Set） ”欄中選中AnalysisDefinition1，如圖 4—15 所示。然后單擊該對(duì)話框中的 （圖形）工具，系統(tǒng)彈出“圖形工具（Graph tool） ”窗口，如圖 4—16 所示，在該窗口中顯示了凸輪機(jī)構(gòu)從動(dòng)件的位移曲線、速度曲線和加速度曲線。圖 4—16 從動(dòng)件實(shí)際運(yùn)動(dòng)規(guī)律28 從圖 4—16 所示可知：凸輪是逆時(shí)針?lè)较蛐D(zhuǎn)，經(jīng)回程到近程休止，再經(jīng)推程到遠(yuǎn)程休止，如此循環(huán)運(yùn)動(dòng)?；爻踢^(guò)程中位移逐漸減少，直到達(dá)到近程休止，近程休止內(nèi)位移不變，推程過(guò)程中位移逐漸增大，直到達(dá)到遠(yuǎn)程休止，遠(yuǎn)程休止內(nèi)位移不變。速度在回程過(guò)程中先減少后增大，在近程休止內(nèi)速度不變，推程過(guò)程中速度先增大后減小，在遠(yuǎn)程休止內(nèi)速度不變。加速度在回程先減小后增大然后又減小，在推程過(guò)程中加速度先增大后減小然后有增大。由圖形曲線可知從動(dòng)件的實(shí)際運(yùn)動(dòng)規(guī)律和修正正弦規(guī)律一致。在“測(cè)量結(jié)果（Measure Results） ”對(duì)話框中的“圖形類(lèi)型（Graph Type） ”欄中選擇“測(cè)量與時(shí)間（Measure vs. Time） ”，在“測(cè)量（Measure） ”欄中按著鍵選擇 “xf4_行程” 和“xf5_速度” ，鉤選“分別繪制測(cè)量圖形（Graph measures separately） ”項(xiàng)，在“結(jié)果集（Result Set） ”欄中選中AnalysisDefinition1，如圖 4—17 所示。圖 4—17 “測(cè)量結(jié)果”對(duì)話框然后單擊該對(duì)話框中的 （圖形）工具，系統(tǒng)彈出“圖形工具（Graph tool） ”窗口，如圖 4—18 所示，在該窗口中顯示了凸輪連桿機(jī)構(gòu)執(zhí)行端的Ｙ向行程和速度。圖 4—18 執(zhí)行端 Y 向位移和速度曲線29 從圖 4—18 可知：凸輪連桿機(jī)構(gòu)執(zhí)行端的 Y 向位移、速度曲線和從動(dòng)件的位移、速度曲線一樣。這說(shuō)明此凸輪機(jī)構(gòu)能夠精確輸出本文所要求的運(yùn)動(dòng)規(guī)律。4.4 本章小結(jié)本章首先介紹了下計(jì)算機(jī)的仿真技術(shù)，然后較詳細(xì)的介紹了 Pro/E 軟件中的運(yùn)動(dòng)仿真模塊，最后詳細(xì)的介紹了凸輪機(jī)構(gòu)的運(yùn)動(dòng)仿真過(guò)程，并對(duì)結(jié)果進(jìn)行了分析。30 結(jié) 論經(jīng)過(guò)幾個(gè)多月的忙碌后，終于完成了本設(shè)計(jì)課題的各項(xiàng)任務(wù)。經(jīng)過(guò)這次畢業(yè)設(shè)計(jì)，增強(qiáng)了我的自學(xué)能力和收集使用資料的能力，同時(shí)全面系統(tǒng)地鞏固和總結(jié)大學(xué)四年來(lái)所學(xué)的專(zhuān)業(yè)知識(shí)。通過(guò)這次畢業(yè)設(shè)計(jì)，我更好的把四年來(lái)所學(xué)的知識(shí)進(jìn)行了綜合、鞏固，加深了對(duì)所學(xué)專(zhuān)業(yè)知識(shí)的理解，同時(shí)還接觸了一些在原來(lái)知識(shí)基礎(chǔ)上更為深層的知識(shí)。當(dāng)然，也使我體味到設(shè)計(jì)工作是一項(xiàng)艱苦任務(wù)，必須具備吃苦耐勞的精神?？傊?，這次畢業(yè)設(shè)計(jì)使我受益匪淺，為我將來(lái)工作打好了良好的基礎(chǔ)。在這次畢業(yè)設(shè)計(jì)的過(guò)程當(dāng)中，我的指導(dǎo)老師一直給予的細(xì)心指導(dǎo)，還有其它老師和同學(xué)在提供幫助，在此表示衷心的感謝。由于本人知識(shí)面較窄，加上時(shí)間比較倉(cāng)促缺乏實(shí)踐經(jīng)驗(yàn)，設(shè)計(jì)中難免出現(xiàn)錯(cuò)誤或不足之處，還望各位老師和同學(xué)批評(píng)指正，不勝感激。31 致 謝本文是在指導(dǎo)老師精心指導(dǎo)和大力支持下完成的。指導(dǎo)老師以其嚴(yán)謹(jǐn)求實(shí)的治學(xué)態(tài)度、高度的敬業(yè)精神、兢兢業(yè)業(yè)、孜孜以求的工作作風(fēng)和大膽創(chuàng)新的進(jìn)取精神對(duì)我產(chǎn)生重要影響。他淵博的知識(shí)、開(kāi)闊的視野和敏銳的思維給了我深深的啟迪。同時(shí)，在此次畢業(yè)設(shè)計(jì)過(guò)程中我也學(xué)到了許多生活方面的知識(shí)。另外，我還要特別感謝其它師對(duì)我論文寫(xiě)作的指導(dǎo)，他們?yōu)槲彝瓿蛇@篇論文提供了巨大的幫助。感謝同學(xué)對(duì)我的無(wú)私幫助，使我得以順利完成論文。最后，再次對(duì)關(guān)心、幫助我的老師和同學(xué)表示衷心地感謝。32 參考文獻(xiàn)[1] Xing Yingjie. Recording and processing of planar cure using clothoids(Ind Report)—recording of cam profile with clothoidal interpolation, Tokyo: Seimitsu kogaku kaishi 61 ＆ Aug 1995 JSPE, 1995, 1092∽1100[2] Watanabe Katsuin, Exact analysis of plate cam mechanisms having errorin kinermatic constants. Nippon Kihai Gakkai ronbunshuc Hen, 1993[3] 石永剛，徐振華．凸輪機(jī)構(gòu)，上海：上海科學(xué)技術(shù)出版社.[4] 申永勝．機(jī)械原理教程，北京：清華大學(xué)出版社．[5] 石永剛．凸輪設(shè)計(jì)與應(yīng)用創(chuàng)新，北京：機(jī)械工業(yè)出版社.[6] 劉會(huì)英，楊志強(qiáng)，張勤明．機(jī)械原理，北京：機(jī)械工業(yè)出版社．[7] 袁劍雄，李晨霞，潘承怡.機(jī)械結(jié)構(gòu)設(shè)計(jì)禁計(jì)，北京：機(jī)械工業(yè)出版社 .[8] 劉昌祺，牧野洋（日） ，曹西京.凸輪機(jī)構(gòu)設(shè)計(jì)，北京：機(jī)械工業(yè)出版社 .[9] 譚雪松，張青，賴(lài)春林．機(jī)械工程師 Pro/ENGINEER Wildhre 中文版 機(jī)械設(shè)計(jì)，北京：人民郵電出版社.[10] 葛正浩，楊芙蓮．Pro/E 機(jī)構(gòu)設(shè)計(jì)與運(yùn)動(dòng)仿真，北京：化學(xué)工業(yè)出版社 .畢業(yè)設(shè)計(jì)（論文）任務(wù)書(shū)I、畢業(yè)設(shè)計(jì)(論文) 題目：溝槽凸輪機(jī)構(gòu)的設(shè)計(jì)和運(yùn)動(dòng)仿真II、畢 業(yè)設(shè)計(jì)(論文)使用的原始資料(數(shù)據(jù))及設(shè)計(jì)技術(shù)要求：設(shè)計(jì)技術(shù)要求：1.凸輪機(jī)構(gòu)設(shè)計(jì)2.凸輪機(jī)構(gòu)的實(shí)體建模與裝配3.凸輪機(jī)構(gòu)的運(yùn)動(dòng)仿真III、畢 業(yè)設(shè)計(jì)(論文)工作內(nèi)容及完成 時(shí)間：1. 開(kāi)題報(bào)告、查閱資料、外文翻譯（6000 字符) 第 1 周－第 3 周2. 凸輪機(jī)構(gòu)設(shè)計(jì) 第 4 周－第 6 周3. 凸輪機(jī)構(gòu)的實(shí)體建模與裝配 第 7 周－第 10 周4. 凸輪機(jī)構(gòu)的運(yùn)動(dòng)仿真 第 11 周－第 13 周5. 撰寫(xiě)畢業(yè)論文 第 14 周－第 16 周6. 答辯準(zhǔn)備及畢業(yè)答辯 第 17 周Ⅳ 、主 要參考資料：[1] 石永剛．凸輪設(shè)計(jì)與應(yīng)用創(chuàng)新，北京：機(jī)械工 業(yè)出版社.[2] 石永剛，徐振華．凸輪機(jī)構(gòu)，上海：上?？茖W(xué)技術(shù)出版社.[3] 劉昌祺，牧野洋（日），曹西京.凸輪機(jī)構(gòu)設(shè)計(jì)，北京：機(jī)械工業(yè)出版社[4]譚雪松，張青，賴(lài)春林．機(jī)械工程 師 Pro/ENGINEER Wildhre 中文版 機(jī)械設(shè)計(jì)，北京：人民郵電出版社.[5]葛正浩，楊芙蓮．Pro/E 機(jī)構(gòu)設(shè)計(jì)與運(yùn)動(dòng)仿真，北京：化學(xué)工業(yè)出版社.[6] Xing Yingjie. Recording and processing of planar cure using clothoids(Ind Report)—recording of cam profile with clothoidal interpolation, Tokyo: Seimitsu kogaku kaishi 61 ＆ Aug 1995 JSPE, 1995, 1092－1100[7] Watanabe Katsuin, Exact analysis of plate cam mechanisms having errorin kinermatic constants. Nippon Kihai Gakkai ronbunshuc Hen, 1993航空與機(jī)械工程 學(xué)院 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 專(zhuān)業(yè)類(lèi) 0681051 班學(xué)生（簽名）： 胡裕填寫(xiě)日期： 2011 年 01 月 03 日指導(dǎo)教師（簽名）： 于斐助理指導(dǎo)教師(并指出所負(fù)責(zé)的部分)：機(jī)械制造工程 系（室）主任（簽名）：姚坤弟附注:任 務(wù)書(shū)應(yīng)該附在已完成的畢業(yè)設(shè)計(jì)說(shuō)明書(shū)首頁(yè)。 畢業(yè)設(shè)計(jì)（論文）外文翻譯題目 機(jī)械設(shè)計(jì)理論 專(zhuān)業(yè)名稱(chēng) 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 班級(jí)學(xué)號(hào) 068105116 學(xué)號(hào)姓名 胡 裕 指導(dǎo)老師 于 斐 填 表 日 期 2011 年 3 月 25 日機(jī)械設(shè)計(jì)理論機(jī)械設(shè)計(jì)是一門(mén)通過(guò)設(shè)計(jì)新產(chǎn)品或者改進(jìn)老產(chǎn)品來(lái)滿(mǎn)足人類(lèi)需求的應(yīng)用技術(shù)科學(xué)。它涉及工程技術(shù)的各個(gè)領(lǐng)域，主要研究產(chǎn)品的尺寸、形狀和詳細(xì)結(jié)構(gòu)的基本構(gòu)思，還要研究產(chǎn)品在制造、銷(xiāo)售和使用等方面的問(wèn)題。進(jìn)行各種機(jī)械設(shè)計(jì)工作的人員通常被稱(chēng)為設(shè)計(jì)人員或者機(jī)械設(shè)計(jì)工程師。機(jī)械設(shè)計(jì)是一項(xiàng)創(chuàng)造性的工作。設(shè)計(jì)工程師不僅在工作上要有創(chuàng)造性，還必須在機(jī)械制圖、運(yùn)動(dòng)學(xué)、工程材料、材料力學(xué)和機(jī)械制造工藝學(xué)等方面具有深厚的基礎(chǔ)知識(shí)。 如前所訴，機(jī)械設(shè)計(jì)的目的是生產(chǎn)能夠滿(mǎn)足人類(lèi)需求的產(chǎn)品。發(fā)明、發(fā)現(xiàn)和科技知識(shí)本身并不一定能給人類(lèi)帶來(lái)好處，只有當(dāng)它們被應(yīng)用在產(chǎn)品上才能產(chǎn)生效益。因而，應(yīng)該認(rèn)識(shí)到在一個(gè)特定的產(chǎn)品進(jìn)行設(shè)計(jì)之前，必須先確定人們是否需要這種產(chǎn)品。應(yīng)當(dāng)把機(jī)械設(shè)計(jì)看成是機(jī)械設(shè)計(jì)人員運(yùn)用創(chuàng)造性的才能進(jìn)行產(chǎn)品設(shè)計(jì)、系統(tǒng)分析和制定產(chǎn)品的制造工藝學(xué)的一個(gè)良機(jī)。掌握工程基礎(chǔ)知識(shí)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(gè)好的設(shè)計(jì)中做出所需的全部決定的。另一方面，應(yīng)該認(rèn)真精確的進(jìn)行所有運(yùn)算。例如，即使將一個(gè)小數(shù)點(diǎn)的位置放錯(cuò)，也會(huì)使正確的設(shè)計(jì)變成錯(cuò)誤的。一個(gè)好的設(shè)計(jì)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(xiǎn)，當(dāng)新的方法不適用時(shí)，就使用原來(lái)的方法。因此，設(shè)計(jì)人員必須要有耐心，因?yàn)?所花費(fèi)的時(shí)間和努力并不能保證帶來(lái)成功。一個(gè)全新的設(shè)計(jì)，要求屏棄許多陳舊的，為人們所熟知的方法。由于許多人墨守成規(guī)，這樣做并不是一件容易的事。一位機(jī)械設(shè)計(jì)師應(yīng)該不斷地探索改進(jìn)現(xiàn)有的產(chǎn)品的方法，在此過(guò)程中應(yīng)該認(rèn)真選擇原有的、經(jīng)過(guò)驗(yàn)證的設(shè)計(jì)原理，將其與未經(jīng)過(guò)驗(yàn)證的新觀念結(jié)合起來(lái)。新設(shè)計(jì)本身會(huì)有許多缺陷和未能預(yù)料的問(wèn)題發(fā)生，只有當(dāng)這些缺陷和問(wèn)題被解決之后，才能體現(xiàn)出新產(chǎn)品的優(yōu)越性。因此，一個(gè)性能優(yōu)越的產(chǎn)品誕生的同時(shí)，也伴隨著較高的風(fēng)險(xiǎn)。應(yīng)該強(qiáng)調(diào)的是，如果設(shè)計(jì)本身不要求采用全新的方法，就沒(méi)有必要僅僅為了變革的目的而采用新方法。在設(shè)計(jì)的初始階段，應(yīng)該允許設(shè)計(jì)人員充分發(fā)揮創(chuàng)造性，不受各種約束。即使產(chǎn)生了許多不切實(shí)際的想法，也會(huì)在設(shè)計(jì)的早期，即繪制圖紙之前被改正掉。只有這樣，才不致于堵塞創(chuàng)新的思路。通常，要提出幾套設(shè)計(jì)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。 心理學(xué)家經(jīng)常談?wù)撊绾问谷藗冞m應(yīng)他們所操作的機(jī)器。設(shè)計(jì)人員的基本職責(zé)是努力使機(jī)器來(lái)適應(yīng)人們。這并不是一項(xiàng)容易的工作，因?yàn)閷?shí)際上并不存在著一個(gè)對(duì)所有人來(lái)說(shuō)都是最優(yōu)的操作范圍和操作過(guò)程。另一個(gè)重要問(wèn)題，設(shè)計(jì)工程師必須能夠同其他有關(guān)人員進(jìn)行交流和磋商。在開(kāi)始階段，設(shè)計(jì)人員必須就初步設(shè)計(jì)同管理人員進(jìn)行交流和磋商，并得到批準(zhǔn)。這一般是通過(guò)口頭討論，草圖和文字材料進(jìn)行的。為了進(jìn)行有效的交流 ，需要解決下列問(wèn)題：（1） 所設(shè)計(jì)的這個(gè)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(lèi)產(chǎn)品相比有無(wú)競(jìng)爭(zhēng)能力？（3） 生產(chǎn)這種產(chǎn)品是否經(jīng)濟(jì)？（4） 產(chǎn)品的維修是否方便？（5） 產(chǎn)品有無(wú)銷(xiāo)路？是否可以盈利？ 只有時(shí)間能對(duì)上述問(wèn)題給出正確答案。但是， 產(chǎn)品的設(shè)計(jì)、制造和銷(xiāo)售只能在對(duì)上述問(wèn)題的初步肯定答案的基礎(chǔ)上進(jìn)行。設(shè)計(jì)工程師還應(yīng)該通過(guò)零件圖和裝配圖，與制造部門(mén)一起對(duì)最終設(shè)計(jì)方案進(jìn)行磋商。通常 ，在制造過(guò)程中會(huì)出現(xiàn)某個(gè)問(wèn)題?？赡軙?huì)要求對(duì)某個(gè)零件尺寸或公差作一些更改，使零件的生產(chǎn)變得容易。但是，工程上的更改必須要經(jīng)過(guò)設(shè)計(jì)人員批準(zhǔn)，以保證不會(huì)損傷產(chǎn)品的功能。有時(shí)，在產(chǎn)品的裝配時(shí)或者裝箱外運(yùn)前的試驗(yàn)中才發(fā)現(xiàn)設(shè)計(jì)中的某種缺陷。這些事例恰好說(shuō)明了設(shè)計(jì)是一個(gè)動(dòng)態(tài)過(guò)程?？偸谴嬖谥玫姆椒▉?lái)完成設(shè)計(jì)工作，設(shè)計(jì)人員應(yīng)該不斷努力，尋找這些更好的方法。近些年來(lái)，工程材料的選擇已經(jīng)顯得重要。此外，選擇過(guò)程應(yīng)該是一個(gè)對(duì)材料的連續(xù)不斷的重新評(píng)價(jià)過(guò)程。新材料不斷出現(xiàn)，而一些原有的材料的能夠獲得的數(shù)量可能會(huì)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(huì)對(duì)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(huì)要求使用不同的材料。來(lái)自國(guó)內(nèi)和國(guó)際競(jìng)爭(zhēng)、對(duì)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(huì)促使人們對(duì)材料進(jìn)行重新評(píng)價(jià)。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(lài)關(guān)系已經(jīng)被人們認(rèn)識(shí)得更清楚。因此，為了能在合理的成本和確保質(zhì)量的前提下獲得滿(mǎn)意的結(jié)果，設(shè)計(jì)工程師的制造工程師都必須認(rèn)真仔細(xì)地選擇、確定和使用材料。制造任何產(chǎn)品的第一步工作都是設(shè)計(jì)。設(shè)計(jì)通?？梢苑譃閹讉€(gè)明確的階段：（a）初步設(shè)計(jì)；（ b）功能設(shè)計(jì)；（ c）生產(chǎn)設(shè)計(jì)。在初步設(shè)計(jì)階段，設(shè)計(jì)者著重考慮產(chǎn)品應(yīng)該具有的功能。通常要設(shè)想和考慮幾個(gè)方案，然后決定這種思想是否可行；如果可行，則應(yīng)該對(duì)其中一個(gè)或幾個(gè)方案作進(jìn)一步的改進(jìn)。在此階段，關(guān)于材料選擇唯一要考慮的問(wèn)題是：是否有性能符合要求的材料可供選擇；如果沒(méi)有的話，是否有較大的把握在成本和時(shí)間都允許的限度內(nèi)研制出一種新材料。在功能設(shè)計(jì)和工程設(shè)計(jì)階段，要做出一個(gè)切實(shí)可行的設(shè)計(jì)。在這個(gè)階段要繪制出相當(dāng)完整的圖紙，選擇并確定各種零件的材料。通常要制造出樣機(jī)或者實(shí)物模型，并對(duì)其進(jìn)行試驗(yàn)，評(píng)價(jià)產(chǎn)品的功能、可靠性、外觀和維修保養(yǎng)性等。雖然這種試驗(yàn)可能會(huì)表明，在產(chǎn)品進(jìn)入到生產(chǎn)階段之前，應(yīng)該更換某些材料，但是，絕對(duì)不能將這一點(diǎn)作為不認(rèn)真選擇材料的借口。應(yīng)該結(jié)合產(chǎn)品的功能，認(rèn)真仔細(xì)地考慮產(chǎn)品的外觀、成本和可靠性。一個(gè)很有成就的公司在制造所有的樣機(jī)時(shí)，所選用的材料應(yīng)該和其生產(chǎn)中使用的材料相同，并盡可能使用同樣的制造技術(shù)。這樣對(duì)公司是很有好處的。功能完備的樣機(jī)如果不能根據(jù)預(yù)期的銷(xiāo)售量經(jīng)濟(jì)地制造出來(lái)，或者是樣機(jī)與正式生產(chǎn)的裝置在質(zhì)量和可靠性方面有很大不同，則這種樣機(jī)就沒(méi)有多大的價(jià)值。設(shè)計(jì)工程師最好能在這一階段完全完成材料的分析、選擇和確定工作，而不是將其留到生產(chǎn)設(shè)計(jì)階段去做。因?yàn)?，在生產(chǎn)設(shè)計(jì)階段材料的更換是由其他人進(jìn)行的，這些人對(duì)產(chǎn)品的所有功能的了解不如設(shè)計(jì)工程師。 在生產(chǎn)設(shè)計(jì)階段中，與材料有關(guān)的主要問(wèn)題是應(yīng)該把材料完全確定下來(lái)，使它們與現(xiàn)有的設(shè)備相適應(yīng)，能夠利用現(xiàn)有設(shè)備經(jīng)濟(jì)地進(jìn)行加工，而且材料的數(shù)量能夠比較容易保證供應(yīng)。在制造過(guò)程中，不可避免地會(huì)出現(xiàn)對(duì)使用中的材料做一些更改的情況。經(jīng)驗(yàn)表明，可采用某些便宜材料作為替代品。然而，在大多數(shù)情況下，在進(jìn)行生產(chǎn)以后改換材料要比在開(kāi)始生產(chǎn)前改換材料所花費(fèi)的代價(jià)要高。在設(shè)計(jì)階段做好材料選擇工作，可以避免多數(shù)這樣的情況。在生產(chǎn)制造開(kāi)始后出現(xiàn)了可供使用的新材料是更換材料的最常見(jiàn)的原因。當(dāng)然，這些新材料可能降低成本、改進(jìn)產(chǎn)品的性能。但是，必須對(duì)新材料進(jìn)行認(rèn)真的評(píng)價(jià)，以確保其所有性能都滿(mǎn)足要求。應(yīng)當(dāng)記住，新材料的性能和可靠性很少像現(xiàn)有材料那樣為人們所了解。大部分的產(chǎn)品失效和產(chǎn)品責(zé)任事故案件是由于在選用新材料作為替代材料之前，沒(méi)有真正了解它們的長(zhǎng)期使用性能而引起的。產(chǎn)品的責(zé)任訴訟迫使設(shè)計(jì)人員和公司在選擇材料時(shí)，采用最好的程序。在材料過(guò)程中，五個(gè)最常見(jiàn)的問(wèn)題為：（a）不了解或者不會(huì)使用關(guān)于材料應(yīng)用方面的最新最好的信息資料；(b)未能預(yù)見(jiàn)和考慮擦黑年品可能的合理用途（如有可能，設(shè)計(jì)人員還應(yīng)進(jìn)一步預(yù)測(cè)和考慮由于產(chǎn)品使用方法不當(dāng)造成的后果。在近年來(lái)的許多產(chǎn)品責(zé)任訴訟案件中，由于錯(cuò)誤地使用產(chǎn)品而受到傷害的原告控告生產(chǎn)廠家，并且贏得判決） ；(c)所使用的材料的數(shù)據(jù)不全或是有些數(shù)據(jù)不確定，尤其是當(dāng)其長(zhǎng)期性能數(shù)據(jù)是如此的時(shí)候；(d)質(zhì)量控制方法不適當(dāng)和未經(jīng)驗(yàn)證；(e)由一些完全不稱(chēng)職的人員選擇材料。通過(guò)對(duì)上述五個(gè)問(wèn)題的分析，可以得出這些問(wèn)題是沒(méi)有充分理由存在的結(jié)論。對(duì)這些問(wèn)題的研究分析可以為避免這些問(wèn)題的出現(xiàn)指明方向。盡管采用最好的材料選擇方法也不能避免發(fā)生產(chǎn)品責(zé)任訴訟，設(shè)計(jì)人員和工業(yè)界按照適當(dāng)?shù)某绦蜻M(jìn)行材料選擇，可以大大減少訴訟的數(shù)量。從以上的討論可以看出，選擇材料的人們應(yīng)該對(duì)材料的性質(zhì)，特點(diǎn)和加工方法有一個(gè)全面而基本的了解。Machine design theoryThe machine design is through designs the new product or improves the old product to meet the human need the application technical science. It involves the project technology each domain, mainly studies the product the size, the shape and the detailed structure basic idea, but also must study the product the personnel which in aspect the and so on manufacture, sale and use question.Carries on each kind of machine design work to be usually called designs the personnel or machine design engineer. The machine design is a creative work. Project engineer not only must have the creativity in the work, but also must in aspect and so on mechanical drawing, kinematics, engineerig material, materials mechanics and machine manufacture technology has the deep elementary knowledge. If front sues, the machine design goal is the production can meet the human need the product. The invention, the discovery and technical knowledge itself certainly not necessarily can bring the advantage to the humanity, only has when they are applied can produce on the product the benefit. Thus, should realize to carries on before the design in a specific product, must first determine whether the people do need this kind of productMust regard as the machine design is the machine design personnel carries on using creative ability the product design, the system analysis and a formulation product manufacture technology good opportunity. Grasps the project elementary knowledge to have to memorize some data and the formula is more important than. The merely service data and the formula is insufficient to the completely decision which makes in a good design needs. On the other hand, should be earnest precisely carries on all operations. For example, even if places wrong a decimal point position, also can cause the correct design to turn wrongly.A good design personnel should dare to propose the new idea, moreover is willing to undertake the certain risk, when the new method is not suitable, use original method. Therefore, designs the personnel to have to have to have the patience, because spends the time and the endeavor certainly cannot guarantee brings successfully. A brand-new design, the request screen abandons obsoletely many, knows very well the method for the people. Because many person of conservativeness, does this certainly is not an easy matter. A mechanical designer should unceasingly explore the improvement existing product the method, should earnestly choose originally, the process confirmation principle of design in this process, with has not unified it after the confirmation new idea. Newly designs itself can have the question occurrence which many flaws and has not been able to expect, only has after these flaws and the question are solved, can manifest new goods come into the market the product superiority. Therefore, a performance superior product is born at the same time, also is following a higher risk. Should emphasize, if designs itself does not request to use the brand-new method, is not unnecessary merely for the goal which transform to use the new method. In the design preliminary stage, should allow to design the personnel fully to display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mentality. Usually, must propose several sets of design proposals, then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts. How does the psychologist frequently discuss causes the machine which the people adapts them to operate. Designs personnel''s basic responsibility is diligently causes the machine to adapt the people. This certainly is not an easy work, because certainly does not have to all people to say in fact all is the most superior operating area and the operating process. Another important question, project engineer must be able to carry on the exchange and the consultation with other concerned personnel. In the initial stage, designs the personnel to have to carry on the exchange and the consultation on the preliminary design with the administrative personnel, and is approved. This generally is through the oral discussion, the schematic diagram and the writing material carries on. In order to carry on the effective exchange, needs to solve the following problem: (1) designs whether this product truly does need for the people? Whether there is competitive ability (2) does this product compare with other companies'' existing similar products? (3) produces this kind of product is whether economical? (4) product service is whether convenient? (5) product whether there is sale? Whether may gain?Only has the time to be able to produce the correct answer to above question. But, the product design, the manufacture and the sale only can in carry on to the above question preliminary affirmation answer foundation in. Project engineer also should through the detail drawing and the assembly drawing, carries on the consultation together with the branch of manufacture to the finally design proposal.Usually, can have some problem in the manufacture process. Possibly can request to some components size or the common difference makes some changes, causes the components the production to change easily. But, in the project change must have to pass through designs the personnel to authorize, guaranteed cannot damage the product the function. Sometimes, when in front of product assembly or in the packing foreign shipment experiment only then discovers in the design some kind of flaw. These instances exactly showed the design is a dynamic process. Always has a better method to complete the design work, designs the personnel to be supposed unceasingly diligently, seeks these better method. Recent year, the engineerig material choice already appeared importantly. In addition, the choice process should be to the material continuously the unceasing again appraisal process. The new material unceasingly appears, but some original materials can obtain the quantity possibly can reduce. The environmental pollution, material recycling aspect and so on use, worker''s health and security frequently can attach the new limiting condition to the choice of material. In order to reduce the weight or saves the energy, possibly can request the use different material. Comes from domestic and international competition, to product service maintenance convenience request enhancement and customer''s aspect the and so on feedback pressure, can urge the people to carry on to the material reappraises. Because the material does not select when created the product responsibility lawsuit, has already had the profound influence. In addition, the material and between the material processing interdependence is already known by the people clearly. Therefore, in order to can and guarantees the quality in the reasonable cost under the premise to obtain satisfaction the result, project engineer makes engineers all to have earnestly carefully to choose, the determination and the use material. Makes any product the first step of work all is designs. Designs usually may divide into several explicit stages: (a) preliminary design; (b) functional design; (c) production design. In the preliminary design stage, the designer emphatically considered the product should have function. Usually must conceive and consider several plans, then decided this kind of thought is whether feasible; If is feasible, then should makes the further improvement to or several plans. In this stage, the question which only must consider about the choice of material is: Whether has the performance to conform to the request material to be possible to supply the choice; If no, whether has a bigger assurance all permits in the cost and the time in the limit develops one kind of new material.In the functional design and the engineering design stage, needs to make a practical feasible design. Must draw up the quite complete blueprint in this stage, chooses and determines each kind of components the material. Usually must make the prototype or the working model, and carries on the experiment to it, the appraisal product function, the reliability, the outward appearance and the service maintenance and so on. Although this kind of experiment possibly can indicate, enters in the product to the production base in front of, should replace certain materials, but, absolutely cannot this point take not earnestly chooses the material the excuse. Should unify the product the function, earnestly carefully considers the product the outward appearance, the cost and the reliability. Has the achievement very much the company when manufacture all prototypes, selects the material should the material which uses with its production in be same, and uses the similar manufacture technology as far as possible. Like this has the advantage very much to the company. The function complete prototype if cannot act according to the anticipated sales volume economically to make, or is prototypical and the official production installment has in the quality and the reliable aspect is very greatly different, then this kind of prototype does not have the great value. Project engineer is best can completely complete the material in this stage the analysis, the choice and the determination work, but is not remains it to the production design stage does. Because, is carries on in the production design stage material replacement by other people, these people are inferior to project engineer to the product all functions understanding. I n the production design stage, is should completely determine with the material related main question the material, causes them to adapt with the existing equipment, can use the existing equipment economically to carry on the processing, moreover the material quantity can quite be easy to guarantee the supply. In the manufacture process, inevitably can appear to uses the material to make some changes the situation. The experience indicated that, may use certain cheap materials to take the substitute. However, in the majority situation, in will carry on the production later to change the material to have in to start before the production to change the price which the material will spend to have to be higher than. Completes the choice of material work in the design stage, may avoid the most such situations. Started after the production manufacture to appear has been possible to supply the use the new material is replaces the material the most common reason. Certainly, these new materials possibly reduce the cost, the improvement product performance. But, must carry on the earnest appraisal to the new material, guarantees its all performance all to answer the purpose. Must remember that, the new material performance and the reliable very few pictures materials on hand such understood for the people. The majority of products expiration and the product accident caused by negligence case is because in selects the new material to take in front of substitution material, not truly understood their long-term operational performance causes. The product responsibility lawsuit forces designs the personnel and the company when the choice material, uses the best procedure. In the material process, five most common questions are: (a) did not understand or cannot use about the material application aspect most newly the best information paper; (b) has not been able to foresee and to consider the dusk year possible reasonable use (for example to have the possibility, designs the personnel also to be supposed further to forecast and the consideration because product application method not when creates consequence. In recent years many products responsibilities lawsuit case, because wrongly uses the plaintiff which the product receives the injury to accuse produces the factory, and wins the decision); (c) uses the material data not entire perhaps some data are indefinite, works as its long-term performance data is the like this time in particular; (d) the quality control method is not suitable and not after the confirmation; (e) the personnel which completely is not competent for the post by some chooses the material. Through to the above five questions analysis, may obtain these questions is does not have the sufficient reason existence the conclusion. May for avoid these questions to these questions research analyses the appearance indicating the direction. Although uses the best choice of material method not to be able to avoid having the product responsibility lawsuit, designs the personnel and the industry carries on the choice of material according to the suitable procedure, may greatly reduce the lawsuit the quantity. May see from the above discussion, the choice material people should to the material nature, the characteristic and the processing method have comprehensive and the basic understanding.