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畢業(yè)設(shè)計(jì)（論文）
任務(wù)書(shū)
題 目: 裁斷機(jī)設(shè)計(jì)
立式
院系名稱
學(xué)生姓名
指導(dǎo)教師
起止日期
任務(wù)書(shū)填寫(xiě)要求
1．畢業(yè)設(shè)計(jì)（論文）任務(wù)書(shū)由指導(dǎo)教師根據(jù)各課題的具體情況填寫(xiě)，經(jīng)學(xué)生所在系（教研室）負(fù)責(zé)人審查、學(xué)院（部）領(lǐng)導(dǎo)簽字后生效。此任務(wù)書(shū)應(yīng)在畢業(yè)設(shè)計(jì)（論文）開(kāi)始前一周內(nèi)填好并發(fā)給學(xué)生。
2．任務(wù)書(shū)內(nèi)容必須用黑墨水筆工整書(shū)寫(xiě)或按教務(wù)處統(tǒng)一設(shè)計(jì)的電子文檔標(biāo)準(zhǔn)格式（可從教務(wù)處網(wǎng)頁(yè)上下載）打印，不得隨便涂改或潦草書(shū)寫(xiě)，禁止打印在其它紙上后剪貼。
3．任務(wù)書(shū)內(nèi)填寫(xiě)的內(nèi)容，必須和學(xué)生畢業(yè)設(shè)計(jì)（論文）完成的情況相一致，若有變更，應(yīng)當(dāng)經(jīng)過(guò)所在專業(yè)及學(xué)院（部）主管領(lǐng)導(dǎo)審批后方可重新填寫(xiě)。
4．任務(wù)書(shū)內(nèi)有關(guān)“學(xué)院（部）”、“專業(yè)”等名稱的填寫(xiě)，應(yīng)寫(xiě)中文全稱，不能寫(xiě)數(shù)字代碼。學(xué)生的“學(xué)號(hào)”要寫(xiě)全號(hào)（2003級(jí)本科為11位數(shù)、2004級(jí)?？茷?0位）。
5．任務(wù)書(shū)內(nèi)“主要參考文獻(xiàn)”的填寫(xiě)，應(yīng)按照國(guó)標(biāo)GB 7714—87《文后參考文獻(xiàn)著錄規(guī)則》的要求書(shū)寫(xiě)，不能有隨意性。
6．有關(guān)日期的填寫(xiě)，應(yīng)當(dāng)按照國(guó)標(biāo)GB/T 7408—94《數(shù)據(jù)元和交換格式、信息交換、日期和時(shí)間表示法》規(guī)定的要求，一律用阿拉伯?dāng)?shù)字書(shū)寫(xiě)。如“2007年3月15日”或“2007-03-15”。
畢業(yè)設(shè)計(jì)（論文）任務(wù)書(shū)
1．本畢業(yè)設(shè)計(jì)（論文）課題應(yīng)達(dá)到的目的：
（1）培養(yǎng)學(xué)生綜合運(yùn)用所學(xué)知識(shí)，發(fā)現(xiàn)、提出、分析和解決實(shí)際問(wèn)題，鍛煉學(xué)生實(shí)踐能力，結(jié)合實(shí)際獨(dú)立完成課題的工作能力。
（2）對(duì)學(xué)生的知識(shí)面,掌握知識(shí)的深度,運(yùn)用理論結(jié)合實(shí)際去處理問(wèn)題的能力,實(shí)驗(yàn)?zāi)芰?外語(yǔ)水平,計(jì)算機(jī)運(yùn)用水平,書(shū)面及口頭表達(dá)能力進(jìn)行考核。
2．本畢業(yè)設(shè)計(jì)（論文）課題任務(wù)的內(nèi)容和要求（包括原始數(shù)據(jù)、技術(shù)要求、工作要求等）：
裁斷機(jī)是用來(lái)切割壓制好的桶型砂帶，切割砂帶的目的是為了滿足用戶對(duì)砂帶寬度的要求。設(shè)備應(yīng)操作方便、省力、容易掌握和不易發(fā)生故障和操作錯(cuò)誤。這樣不僅可以減少工人的疲勞、保證工人和機(jī)床的安全，還能提高生產(chǎn)效率。在滿足以上條件的情況下，設(shè)備的結(jié)構(gòu)應(yīng)盡量簡(jiǎn)單，工藝性要好，容易制造和裝配，維修方便等。所以，在設(shè)計(jì)時(shí)主體結(jié)構(gòu)一般采用焊接的形式。
設(shè)計(jì)思路是運(yùn)用刀具的旋轉(zhuǎn)切割砂帶，而刀具的旋轉(zhuǎn)是被動(dòng)跟著主軸的旋轉(zhuǎn)。它們之間的相對(duì)運(yùn)動(dòng)是通過(guò)刀具對(duì)主軸落刀的壓力來(lái)實(shí)現(xiàn)的。砂筒在切割前撐緊，只有這樣砂帶才能被切割下來(lái)。其中砂筒的張緊和刀具的落下由汽缸活塞的運(yùn)動(dòng)來(lái)實(shí)現(xiàn)，主軸的轉(zhuǎn)動(dòng)由電機(jī)帶動(dòng)。
要求選擇合理的設(shè)計(jì)方案、計(jì)算主要參數(shù)；電氣與氣動(dòng)系統(tǒng)設(shè)計(jì)；整機(jī)機(jī)械結(jié)構(gòu)設(shè)計(jì)。
原始參數(shù)
分條寬度： 10～250mm
分條長(zhǎng)度： 380～1000mm
落刀壓力： 200Kgf（可調(diào)）
砂帶漲緊力：120Kgf（可調(diào)）
配套功率 ： 1.5KW（帶制動(dòng)控制）
氣源壓力： 1.2MPa
畢業(yè)設(shè)計(jì)（論文）任務(wù)書(shū)
3．對(duì)本畢業(yè)設(shè)計(jì)（論文）課題成果的要求〔包括畢業(yè)設(shè)計(jì)論文、圖表、實(shí)物樣品等〕：
（1）開(kāi)題報(bào)告，不少于10000字。
（2）方案論證報(bào)告。
（3）畢業(yè)設(shè)計(jì)說(shuō)明書(shū)，不少于5000字（不包括計(jì)算公式和圖表）。
（4）總裝配圖一張A0，若干零件圖折合A0圖紙兩張；裝配圖計(jì)算機(jī)繪圖。
（5）英文翻譯、光盤(pán)一張。
4．主要參考文獻(xiàn)：
趙松年 機(jī)電一體化機(jī)械設(shè)計(jì) 機(jī)械工業(yè)出版社 1996
魏俊民 機(jī)電一體化系統(tǒng)設(shè)計(jì) 中國(guó)防止出版社 1998
梁景凱 機(jī)電一體化技術(shù)與系統(tǒng) 機(jī)械工業(yè)出版社 1999
張建民 機(jī)電一體化系統(tǒng)設(shè)計(jì) 高等教育出版社 2001
李華 機(jī)械制造技術(shù) 高等教育出版社
左健民 液壓與氣動(dòng)傳動(dòng) 機(jī)械工業(yè)出版社
顧維邦 金屬切削機(jī)床概論 機(jī)械工業(yè)出版社 1992
陸劍中 金屬切削原理與刀具 機(jī)械工業(yè)出版社 1984
Bradley D A. Mechatronics：Electronics in products and processesLondon : Chpman and Hall, 1991
Dinsdale Hunt V . Mechatronics-Japan’s Newest Threat. New York: Chapman and Hall,1991
畢業(yè)設(shè)計(jì)（論文）任務(wù)書(shū)
5．本畢業(yè)設(shè)計(jì)（論文）課題工作進(jìn)度計(jì)劃：
起 迄 日 期
工 作 內(nèi) 容
2007年
開(kāi)題報(bào)告
月 日~ 月 日
第一周至第二周完成方案論證；第三周至第七周完成設(shè)計(jì)、計(jì)算和繪圖任務(wù)
月 日~ 月 日
第八周和第九周完成外文文獻(xiàn)譯文和畢業(yè)論文
月 日~ 月 日
論文答辯
所在系（教研室）審查意見(jiàn)：
負(fù)責(zé)人：
年 月 日
院（部）學(xué)術(shù)委員會(huì)意見(jiàn)：
負(fù)責(zé)人：
年 月 日
畢業(yè)設(shè)計(jì)(論文)外文資料翻譯
設(shè)計(jì)題目: 裁斷機(jī)設(shè)計(jì)（立式）
外文題目: 機(jī)械設(shè)計(jì)（方案設(shè)計(jì)過(guò)程的分析）
院系名稱： 機(jī)電工程學(xué)院 專業(yè)班級(jí)：
學(xué)生姓名：
指導(dǎo)教師：
起止日期：
附 件： 1.外文資料翻譯譯文；2.外文原文。
指導(dǎo)教師評(píng)語(yǔ)：
簽名： 年 月 日
附件1：外文資料翻譯譯文
機(jī)械設(shè)計(jì)
機(jī)械設(shè)計(jì)是指機(jī)械裝置和機(jī)械系統(tǒng)——機(jī)器、產(chǎn)品、結(jié)構(gòu)、設(shè)備及儀器的設(shè)計(jì)。大部分機(jī)械設(shè)計(jì)需要利用數(shù)學(xué)、材料科學(xué)和工程力學(xué)知識(shí)。
我們對(duì)整個(gè)設(shè)計(jì)過(guò)程感興趣。它是怎樣開(kāi)始的？工程師是不是僅僅坐在鋪著白紙的桌旁就可以開(kāi)始設(shè)計(jì)了呢？當(dāng)他記下一些設(shè)想后，下一步應(yīng)該做些什么？什么因素會(huì)影響或者控制著應(yīng)該作出的決定？最后，這一設(shè)計(jì)過(guò)程是如何結(jié)束的呢？
有時(shí)，雖然并不總是如此，工程師認(rèn)識(shí)到一種需要并且決定對(duì)此做一些工作時(shí)，設(shè)計(jì)就開(kāi)始了。認(rèn)識(shí)到這種需要，并且語(yǔ)言將其清楚地?cái)⑹龀鰜?lái)，常常是一種高度創(chuàng)造性的工作。因?yàn)檫@種需要可能只是一個(gè)模糊的不滿，一種不舒服的感覺(jué)，或者是感覺(jué)到了某些東西是不正確的。
這種需要往往不是很明顯的。例如，對(duì)食品包裝機(jī)械進(jìn)行改進(jìn)的需要，可能是由于噪音過(guò)大、包裝和重量的變化、包裝質(zhì)量的微小的但是能夠察覺(jué)得出來(lái)的變化等表現(xiàn)出來(lái)的。
敘述某種需要和隨后要解決的問(wèn)題之間有著明顯的區(qū)別。要解決的問(wèn)題是比較具體的。如果需要干凈的空氣，要解決的問(wèn)題可能是降低發(fā)電廠煙囪的排塵量，或者是降低汽車排出的有害氣體。
確定問(wèn)題階段應(yīng)該制訂設(shè)計(jì)對(duì)象所有的設(shè)計(jì)要求。這些設(shè)計(jì)要求包括輸入量、輸出量特性、設(shè)計(jì)對(duì)象所占據(jù)的空間尺寸以及對(duì)這些參量的所有制約因素。我們可以把設(shè)計(jì)對(duì)象看作是黑箱中的某種東西。在這種情況下，我們必須具體確定黑箱的輸入和輸出，以及它們的特性和制約因素。這些設(shè)計(jì)要求將規(guī)定生產(chǎn)成本、產(chǎn)量、預(yù)期壽命、工作范圍、操作溫度和可靠性。
還存在著許多由于設(shè)計(jì)人員所處的特定環(huán)境或者由于問(wèn)題本身的性質(zhì)所產(chǎn)生的隱含設(shè)計(jì)要求。某個(gè)工廠中可利用的制造工藝和設(shè)備會(huì)對(duì)設(shè)計(jì)人員的工作有所限制，因而成為隱含的設(shè)計(jì)要求的一部分。例如，一個(gè)小工廠中可能沒(méi)有冷加工機(jī)械設(shè)備。因此，設(shè)計(jì)人員就必須選擇這個(gè)工廠中能夠進(jìn)行的其他的金屬加工方法。工人的技術(shù)水平和市場(chǎng)上的競(jìng)爭(zhēng)情況也是隱含的設(shè)計(jì)要求的組成部分。
在確定了要解決的問(wèn)題，并且形成了一系列的書(shū)面的和隱含的設(shè)計(jì)要求之后，設(shè)計(jì)工作的下一階段是進(jìn)行綜合以獲得最優(yōu)的結(jié)果。因?yàn)橹挥型ㄟ^(guò)對(duì)所設(shè)計(jì)的系統(tǒng)進(jìn)行分析，才能確定其性能是否滿足設(shè)計(jì)要求。因此，不進(jìn)行分析和優(yōu)化就不能進(jìn)行綜合。
設(shè)計(jì)工作是一個(gè)反復(fù)進(jìn)行的過(guò)程。在這個(gè)過(guò)程中，我們要經(jīng)歷幾個(gè)階段，在對(duì)結(jié)果進(jìn)行評(píng)價(jià)后，再返回到前面的階段。因此，我們可以先綜合系統(tǒng)中的幾個(gè)零件，對(duì)它們進(jìn)行分析和優(yōu)化，然后再進(jìn)行綜合，看它們對(duì)系統(tǒng)的其他部分有什么影響。分析和優(yōu)化都要求我們建立或者作出系統(tǒng)的抽象模型，以便對(duì)此進(jìn)行數(shù)學(xué)分析。我們將這些模型稱為數(shù)學(xué)模型。在建立數(shù)學(xué)模型時(shí)，我們希望能夠找到一個(gè)可以很好地模擬實(shí)際物理系統(tǒng)的數(shù)學(xué)模型。
評(píng)價(jià)是整個(gè)設(shè)計(jì)過(guò)程中的一個(gè)重要階段。評(píng)價(jià)是一個(gè)成功的設(shè)計(jì)的最后檢驗(yàn)，通常包括樣機(jī)的實(shí)驗(yàn)室試驗(yàn)。在此階段我們希望弄清楚設(shè)計(jì)能否真正滿足所有的要求。它是否可靠？在與類似的產(chǎn)品的競(jìng)爭(zhēng)中它能否獲勝？制造和使用這種產(chǎn)品是否經(jīng)濟(jì)？它是否易于維護(hù)和調(diào)整？能否從它的銷售或作用中獲得利潤(rùn)？
與其他人就設(shè)計(jì)方案進(jìn)行交流和磋商是設(shè)計(jì)過(guò)程的最后和關(guān)鍵階段。毫無(wú)疑問(wèn)，有許多偉大的設(shè)計(jì)、發(fā)明或創(chuàng)造之所以沒(méi)有為人類所利用，就是因?yàn)閯?chuàng)造者不善于或者不愿意向其他人介紹自己的成果。提出方案是一種說(shuō)服別人的工作。當(dāng)一個(gè)工程師向經(jīng)營(yíng)、管理部門(mén)或者其主管人員提出自己的新方案時(shí)，就是希望向他們說(shuō)明或者證明自己的方案是比較好的。只有成功地完成這項(xiàng)工作，為得出這個(gè)方案所花費(fèi)的大量時(shí)間和精力才不會(huì)被浪費(fèi)掉。
人們基本上只有三種表達(dá)自己思想的方式，即文字材料、口頭表述和繪圖。因此，一個(gè)優(yōu)秀的工程師除了掌握技術(shù)之外，還應(yīng)該精通這三種表達(dá)方式。如果一個(gè)技術(shù)能力很強(qiáng)的人在上述三種表達(dá)方式中的某一種的能力較差，他就會(huì)遇到很大的困難。如果上述三種能力都較差，那將永遠(yuǎn)沒(méi)有人知道他是一個(gè)多么能干的人！
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)滿足人類需求的應(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為設(shè)計(jì)人員或者設(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)新性，還必須在機(jī)械制圖、運(yùn)動(dòng)學(xué)、動(dòng)力學(xué)、工程材料、材料力學(xué)和機(jī)械制造工藝等方面具有深厚的基礎(chǔ)知識(shí)。
如前面所述，機(jī)械設(shè)計(jì)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(shí)本身是并不一定能給人類帶來(lái)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(shí)到在一個(gè)特定產(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)分析和制訂產(chǎn)品的制造工藝的一個(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。另一方面，應(yīng)該認(rèn)真精確地進(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)，就恢復(fù)采用原來(lái)的方法。因此，設(shè)計(jì)人員必須要有耐心，因?yàn)樗ㄙM(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)，要求摒棄許多陳舊的，為人們所熟知的方法。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(jì)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(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辦法。
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)生了許多不切合實(shí)際的想法，也會(huì)在設(shè)計(jì)的早期，艱險(xiǎn)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(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)題是，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）所要設(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)銷路？是否可以盈利？
只有時(shí)間才能對(duì)上述問(wèn)題給出正確的答案。但是，產(chǎn)品的設(shè)計(jì)、制造和銷售只能在對(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。總是存在著更好的方法來(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。
附件2：外文原文（復(fù)印件）
Mechanical Design
Shigley J E. Mechanical Engineering Design. New York: McGraw-Hill, 2001
Mechanical design means the design of things and systems of a mechanical nature—machines, products, structures, devices, and instruments. For the most part mechanical design utilizes mathematics, the materials sciences, and the engineering-mechanics sciences.
The total design process is of interest to us. How does it begin? Does the engineer simply sit down at his desk with a blank sheet of paper? And, as he jots down some ideas, what happens next? What factors influence or control the decisions which have to be made? Finally, then, how does this design process end?
Sometimes, but not always, design begins when an engineer recognizes a need and decides to do something about it. Recognition of the need and phrasing it in so many words often constitute a highly creative act because the need may be only a vague discontent, a feeling of uneasiness, or a sensing that something is not right.
The need is usually not evident at all. For example, the need to do something about a food-packaging machine may be indicated by the noise level, by the variation in package weight, and by slight but perceptible variations in the quality of the packaging or wrap.
There is a distinct difference between the statement of the need and the identification of the problem which follows this statement. The problem is more specific. If the end is for cleaner air, the problem might be that of reducing the dust discharge from power-plant stacks, or reducing the quantity of irritants from automotive exhausts.
Definition of the problem must include all the specifications for the thing that is to be designed. The specifications are the input and output quantities, the characteristics and dimensions of the space the thing must occupy and all the limitations on these quantities. In this case we must specify the inputs and outputs of the box together with their characteristics and limitations. The specifications define the cost, the number to be manufactured, the expected life, the range, the operating temperature, and t he reliability.
There are many implied specifications which result either from the designer’s particular environment or from the nature of the problem itself. The manufacturing processes which are available, together with the facilities of a certain plant, constitute restrictions on a designer’s freedom, and hence are a part of the implied specifications. A small plant, for instance, may not own cold-working machinery. Knowing this, the designer selects other metal-processing methods which can be performed in the plant. The labor skills available and the competitive situation also constitute implied specifications.
After the problem has been defined and a set of written and implied specifications has been obtained, the next step in design is the synthesis of an optimum solution. Now synthesis cannot take place without both analysis and optimization because the system under design must be analyzed to determine whether the performance complies with the specifications.
The design is an iterative process in which we proceed through several steps, evaluate the results, and then return to an earlier phase of the procedure. Thus we may synthesize several components of a system, analyze and optimize them, and return to synthesis to see what effect this has on the remaining parts of the system. Both analysis and optimization require that we construct or devise abstract of the system which will admit some form of mathematical analysis. We call these models mathematical models. In creating them it is our hope that we can find one which will simulate the physical system very well.
Evaluation is a significant phase of the total design process. Evaluation is the final proof of a successful design, which usually involves the testing of a prototype in the laboratory. Here we wish to discover if the design really satisfies the need or needs. Is it reliable? Will it compete successfully with similar products? Is it economical to manufacture and to use? Is it easily maintained and abjusted? Can a profit be made from its sale or use?
Communicating the design to others if the final, vital step in the design process. Undoubtedly many great designs, inventions, and creative works have been lost to mankind simply because the originators were unable or unwilling to explain their accomplishments to others. Presentation is a selling job. The engineer, when presenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that this solution is a better one. Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted.
Basically, there are only t here means of communication available to us. These are the written, the oral, and the graphical forms. Therefore the successful engineer will be technically competent and versatile in all three forms of communication. A technically competent person who lacks ability in any one of these forms is severely handicapped. If ability in all three forms is lacking, on one will ever know how competent that person is!
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 from 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.
Machine 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 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. Machine design is basically a creative activity. However, in addition to being innovative, a design engineer must also have a soild background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, strength of materials and manufacturing processes.
As stated previously, the purpose of machine design is to produce a product which will serve a need for man. Inventions, discoveries 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.
Good designs require trying new ideas and being willing to take a certain amount of risk, knowing that if the new idea does 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 mew, untried ideas should be incorporated.
New designs generally have“bugs”or unforeseen problems which must be worked out before the superior characteristics of the new designs can be enjoyed. Thus there is a chance for a superior product, but only at higher risk. It should be emphasized that, if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change.
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.
Psychologists frequently talk about trying to fit people to the machines they operate. It is essentially the responsibility of the design engineer to strive to fit machines to people. This is not an easy task, since there is really no average person for which certain operating dimensions and procedures are optimum.
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?
Only time will provide the true answers to the preceding questions, but the product should be designed, manufactured and marketed 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 telegramming of a part so that is 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 if and the designer should constantly strive towards finding that better way.
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