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機(jī)械工程的內(nèi)容
機(jī)械工程的服務(wù)領(lǐng)域廣闊而多面,凡是使用機(jī)械、工具,以至能源和材料生產(chǎn)的部門,都需要機(jī)械工程的服務(wù)。概括說來,現(xiàn)代機(jī)械工程有五大服務(wù)領(lǐng)域:研制和提供能量轉(zhuǎn)換機(jī)械、研制和提供用以生產(chǎn)各種產(chǎn)品的機(jī)械、研制和提供從事各種服務(wù)的機(jī)械、研制和提供家庭和個(gè)人生活中應(yīng)用的機(jī)械、研制和提供各種機(jī)械武器。
? 不論服務(wù)于哪一領(lǐng)域,機(jī)械工程的工作內(nèi)容基本相同,主要有:
建立和發(fā)展機(jī)械工程的工程理論基礎(chǔ)。例如,研究力和運(yùn)動(dòng)的工程力學(xué)和流體力學(xué);研究金屬和非金屬材料的性能,及其應(yīng)用的工程材料學(xué);研究熱能的產(chǎn)生、傳導(dǎo)和轉(zhuǎn)換的熱力學(xué);研究各類有獨(dú)立功能的機(jī)械元件的工作原理、結(jié)構(gòu)、設(shè)計(jì)和計(jì)算的機(jī)械原理和機(jī)械零件學(xué);研究金屬和非金屬的成形和切削加工的金屬工藝學(xué)和非金屬工藝學(xué)等等。
? 研究、設(shè)計(jì)和發(fā)展新的機(jī)械產(chǎn)品,不斷改進(jìn)現(xiàn)有機(jī)械產(chǎn)品和生產(chǎn)新一代機(jī)械產(chǎn)品,以適應(yīng)當(dāng)前和將來的需要。
機(jī)械產(chǎn)品的生產(chǎn),包括:生產(chǎn)設(shè)施的規(guī)劃和實(shí)現(xiàn);生產(chǎn)計(jì)劃的制訂和生產(chǎn)調(diào)度;編制和貫徹制造工藝;設(shè)計(jì)和制造工具、模具;確定勞動(dòng)定額和材料定額;組織加工、裝配、試車和包裝發(fā)運(yùn);對(duì)產(chǎn)品質(zhì)量進(jìn)行有效的控制。機(jī)械制造企業(yè)的經(jīng)營和管理。機(jī)械一般是由許多各有獨(dú)特的成形、加工過程的精密零件組裝而成的復(fù)雜的制品。生產(chǎn)批量有單件和小批,也有中批、大批,直至大量生產(chǎn)。銷售對(duì)象遍及全部產(chǎn)業(yè)和個(gè)人、家庭。而且銷售量在社會(huì)經(jīng)濟(jì)狀況的影響下,可能出現(xiàn)很大的波動(dòng)。因此,機(jī)械制造企業(yè)的管理和經(jīng)營特別復(fù)雜,企業(yè)的生產(chǎn)管理、規(guī)劃和經(jīng)營等的研究也多是肇始于機(jī)械工業(yè)。
? 機(jī)械產(chǎn)品的應(yīng)用。這方面包括選擇、訂購、驗(yàn)收、安裝、調(diào)整、操作、維護(hù)、修理和改造各產(chǎn)業(yè)所使用的機(jī)械和成套機(jī)械裝備,以保證機(jī)械產(chǎn)品在長期使用中的可靠性和經(jīng)濟(jì)性。
機(jī)械產(chǎn)品的應(yīng)用。這方面包括選擇、訂購、驗(yàn)收、安裝、調(diào)整、操作、維護(hù)、修理和改造各產(chǎn)業(yè)所使用的機(jī)械和成套機(jī)械裝備,以保證機(jī)械產(chǎn)品在長期使用中的可靠性和經(jīng)濟(jì)性。
研究機(jī)械產(chǎn)品在制造過程中,尤其是在使用中所產(chǎn)生的環(huán)境污染,和自然資源過度耗費(fèi)方面的問題,及其處理措施。這是現(xiàn)代機(jī)械工程的一項(xiàng)特別重要的任務(wù),而且其重要性與日俱增。
機(jī)械工程分類
機(jī)械的種類繁多,可以按幾個(gè)不同方面分為各種類別,如:按功能可分為動(dòng)力機(jī)械、物料搬運(yùn)機(jī)械、粉碎機(jī)械等;按服務(wù)的產(chǎn)業(yè)可分為農(nóng)業(yè)機(jī)械、礦山機(jī)械、紡織機(jī)械等;按工作原理可分為熱力機(jī)械、流體機(jī)械、仿生機(jī)械等。另外,機(jī)械在其研究、開發(fā)、設(shè)計(jì)、制造、運(yùn)用等過程中都要經(jīng)過幾個(gè)工作性質(zhì)不同的階段。按這些不同階段,機(jī)械工程又可劃分為互相銜接、互相配合的幾個(gè)分支系統(tǒng),如機(jī)械科研、機(jī)械設(shè)計(jì)、機(jī)械制造、機(jī)械運(yùn)用和維修等。
這些按不同方面分成的多種分支學(xué)科系統(tǒng)互相交叉,互相重疊,從而使機(jī)械工程可能分化成上百個(gè)分支學(xué)科。例如,按功能分的動(dòng)力機(jī)械,它與按工作原理分的熱力機(jī)械、流體機(jī)械、透平機(jī)械、往復(fù)機(jī)械、蒸汽動(dòng)力機(jī)械、核動(dòng)力裝置、內(nèi)燃機(jī)、燃?xì)廨啓C(jī),以及與按行業(yè)分的中心電站設(shè)備、工業(yè)動(dòng)力裝置、鐵路機(jī)車、船舶輪機(jī)工程、汽車工程等都有復(fù)雜的交叉和重疊關(guān)系。船用汽輪機(jī)是動(dòng)力機(jī)械,也是熱力機(jī)械、流體機(jī)械和透平機(jī)械,它屬于船舶動(dòng)力裝置、蒸汽動(dòng)力裝置,可能也屬于核動(dòng)力裝置等等。
機(jī)械工程的發(fā)展歷程
人類成為“現(xiàn)代人”的標(biāo)志就是制造工具。石器時(shí)代的各種石斧、石錘和木質(zhì)、皮質(zhì)的簡單粗糙的工具是后來出現(xiàn)的機(jī)械的先驅(qū)。從制造簡單工具演進(jìn)到制造由多個(gè)零件、部件組成的現(xiàn)代機(jī)械,經(jīng)歷了漫長的過程。
幾千年前,人類已創(chuàng)制了用于谷物脫殼和粉碎的臼和磨,用來提水的桔槔和轆轤,裝有輪子的車,航行于江河的船及槳、櫓、舵等。所用的動(dòng)力,從人自身的體力,發(fā)展到利用畜力、水力和風(fēng)力。所用材料從天然的石、木、土、皮革,發(fā)展到人造材料。最早的人造材料是陶瓷,制造陶瓷器皿的陶車,已是具有動(dòng)力、傳動(dòng)和工作三個(gè)部分的完整機(jī)械。
人類從石器時(shí)代進(jìn)入青銅時(shí)代,再進(jìn)而到鐵器時(shí)代,用以吹旺爐火的鼓風(fēng)器的發(fā)展起了重要作用。有足夠強(qiáng)大的鼓風(fēng)器,才能使冶金爐獲得足夠高的爐溫,才能從礦石中煉得金屬。在中國,公元前1000~前900年就已有了冶鑄用的鼓風(fēng)器,并逐漸從人力鼓風(fēng)發(fā)展到畜力和水力鼓風(fēng)。
15~16世紀(jì)以前,機(jī)械工程發(fā)展緩慢。但在以千年計(jì)的實(shí)踐中,在機(jī)械發(fā)展方面還是積累了相當(dāng)多的經(jīng)驗(yàn)和技術(shù)知識(shí),成為后來機(jī)械工程發(fā)展的重要潛力。17世紀(jì)以后,資本主義在英、法和西歐諸國出現(xiàn),商品生產(chǎn)開始成為社會(huì)的中心問題。
18世紀(jì)后期,蒸汽機(jī)的應(yīng)用從采礦業(yè)推廣到紡織、面粉、冶金等行業(yè)。制作機(jī)械的主要材料逐漸從木材改用更為堅(jiān)韌,但難以用手工加工的金屬。機(jī)械制造工業(yè)開始形成,并在幾十年中成為一個(gè)重要產(chǎn)業(yè)。
機(jī)械工程通過不斷擴(kuò)大的實(shí)踐,從分散性的、主要依賴匠師們個(gè)人才智和手藝的一種技藝,逐漸發(fā)展成為一門有理論指導(dǎo)的、系統(tǒng)的和獨(dú)立的工程技術(shù)。機(jī)械工程是促成18~19世紀(jì)的工業(yè)革命,以及資本主義機(jī)械大生產(chǎn)的主要技術(shù)因素。
動(dòng)力是發(fā)展生產(chǎn)的重要因素。17世紀(jì)后期,隨著各種機(jī)械的改進(jìn)和發(fā)展,隨著煤和金屬礦石的需要量的逐年增加,人們感到依靠人力和畜力不能將生產(chǎn)提高到一個(gè)新的階段。
在英國,紡織、磨粉等產(chǎn)業(yè)越來越多地將工場設(shè)在河邊,利用水輪來驅(qū)動(dòng)工作機(jī)械。但當(dāng)時(shí)的煤礦、錫礦、銅礦等礦井中的地下水,仍只能用大量畜力來提升和排除。在這樣的生產(chǎn)需要下,18世紀(jì)初出現(xiàn)了紐科門的大氣式蒸汽機(jī),用以驅(qū)動(dòng)礦井排水泵。但是這種蒸汽機(jī)的燃料消耗率很高,基本上只應(yīng)用于煤礦。
1765年,瓦特發(fā)明了有分開的冷凝器的蒸汽機(jī),降低了燃料消耗率。1781年瓦特又創(chuàng)制出提供回轉(zhuǎn)動(dòng)力的蒸汽機(jī),擴(kuò)大了蒸汽機(jī)的應(yīng)用范圍。蒸汽機(jī)的發(fā)明和發(fā)展,使礦業(yè)和工業(yè)生產(chǎn)、鐵路和航運(yùn)都得以機(jī)械動(dòng)力化。蒸汽機(jī)幾乎是19世紀(jì)唯一的動(dòng)力源,但蒸汽機(jī)及其鍋爐、凝汽器、冷卻水系統(tǒng)等體積龐大、笨重,應(yīng)用很不方便。
19世紀(jì)末,電力供應(yīng)系統(tǒng)和電動(dòng)機(jī)開始發(fā)展和推廣。20世紀(jì)初,電動(dòng)機(jī)已在工業(yè)生產(chǎn)中取代了蒸汽機(jī),成為驅(qū)動(dòng)各種工作機(jī)械的基本動(dòng)力。生產(chǎn)的機(jī)械化已離不開電氣化,而電氣化則通過機(jī)械化才對(duì)生產(chǎn)發(fā)揮作用。
發(fā)電站初期應(yīng)用蒸汽機(jī)為原動(dòng)力。20世紀(jì)初期,出現(xiàn)了高效率、高轉(zhuǎn)速、大功率的汽輪機(jī),也出現(xiàn)了適應(yīng)各種水利資源的水輪機(jī),促進(jìn)了電力供應(yīng)系統(tǒng)的蓬勃發(fā)展。
19世紀(jì)后期發(fā)明的內(nèi)燃機(jī)經(jīng)過逐年改進(jìn),成為輕而小、效率高、易于操縱、并可隨時(shí)啟動(dòng)的原動(dòng)機(jī)。它先被用以驅(qū)動(dòng)沒有電力供應(yīng)的陸上工作機(jī)械,以后又用于汽車、移動(dòng)機(jī)械和輪船,到20世紀(jì)中期開始用于鐵路機(jī)車。蒸汽機(jī)在汽輪機(jī)和內(nèi)燃機(jī)的排擠下,已不再是重要的動(dòng)力機(jī)械。內(nèi)燃機(jī)和以后發(fā)明的燃?xì)廨啓C(jī)、噴氣發(fā)動(dòng)機(jī)的發(fā)展,是飛機(jī)、航天器等成功發(fā)展的基礎(chǔ)技術(shù)因素之一。
工業(yè)革命以前,機(jī)械大都是木結(jié)構(gòu)的,由木工用手工制成。金屬(主要是銅、鐵)僅用以制造儀器、鎖、鐘表、泵和木結(jié)構(gòu)機(jī)械上的小型零件。金屬加工主要靠機(jī)匠的精工細(xì)作,以達(dá)到需要的精度。蒸汽機(jī)動(dòng)力裝置的推廣,以及隨之出現(xiàn)的礦山、冶金、輪船、機(jī)車等大型機(jī)械的發(fā)展,需要成形加工和切削加工的金屬零件越來越多,越來越大,要求的精度也越來越高。應(yīng)用的金屬材料從銅、鐵發(fā)展到以鋼為主。
機(jī)械加工包括鍛造、鍛壓、鈑金工、焊接、熱處理等技術(shù)及其裝備,以及切削加工技術(shù)和機(jī)床、刀具、量具等,得到迅速發(fā)展,保證了各產(chǎn)業(yè)發(fā)展生產(chǎn)所需的機(jī)械裝備的供應(yīng)。
社會(huì)經(jīng)濟(jì)的發(fā)展,對(duì)機(jī)械產(chǎn)品的需求猛增。生產(chǎn)批量的增大和精密加工技術(shù)的進(jìn)展,促進(jìn)了大量生產(chǎn)方法的形成,如零件互換性生產(chǎn)、專業(yè)分工和協(xié)作、流水加工線和流水裝配線等。
簡單的互換性零件和專業(yè)分工協(xié)作生產(chǎn),在古代就已出現(xiàn)。在機(jī)械工程中,互換性最早體現(xiàn)在莫茨利于1797年利用其創(chuàng)制的螺紋車床所生產(chǎn)的螺栓和螺帽。同時(shí)期,美國工程師惠特尼用互換性生產(chǎn)方法生產(chǎn)火槍,顯示了互換性的可行性和優(yōu)越性。這種生產(chǎn)方法在美國逐漸推廣,形成了所謂“美國生產(chǎn)方法”。
20世紀(jì)初期,福特在汽車制造上又創(chuàng)造了流水裝配線。大量生產(chǎn)技術(shù)加上泰勒在19世紀(jì)末創(chuàng)立的科學(xué)管理方法,使汽車和其他大批量生產(chǎn)的機(jī)械產(chǎn)品的生產(chǎn)效率很快達(dá)到了過去無法想象的高度。
20世紀(jì)中、后期,機(jī)械加工的主要特點(diǎn)是:不斷提高機(jī)床的加工速度和精度,減少對(duì)手工技藝的依賴;提高成形加工、切削加工和裝配的機(jī)械化和自動(dòng)化程度;利用數(shù)控機(jī)床、加工中心、成組技術(shù)等,發(fā)展柔性加工系統(tǒng),使中小批量、多品種生產(chǎn)的生產(chǎn)效率提高到近于大量生產(chǎn)的水平;研究和改進(jìn)難加工的新型金屬和非金屬材料的成形和切削加工技術(shù)。
18世紀(jì)以前,機(jī)械匠師全憑經(jīng)驗(yàn)、直覺和手藝進(jìn)行機(jī)械制作,與科學(xué)幾乎不發(fā)生聯(lián)系。到18~19世紀(jì),在新興的資本主義經(jīng)濟(jì)的促進(jìn)下,掌握科學(xué)知識(shí)的人士開始注意生產(chǎn),而直接進(jìn)行生產(chǎn)的匠師則開始學(xué)習(xí)科學(xué)文化知識(shí),他們之間的交流和互相啟發(fā)取得很大的成果。在這個(gè)過程中,逐漸形成一整套圍繞機(jī)械工程的基礎(chǔ)理論。
動(dòng)力機(jī)械最先與當(dāng)時(shí)的先進(jìn)科學(xué)相結(jié)合。蒸汽機(jī)的發(fā)明人薩弗里、瓦特,應(yīng)用了物理學(xué)家帕潘和布萊克的理論;在蒸汽機(jī)實(shí)踐的基礎(chǔ)上,物理學(xué)家卡諾、蘭金和開爾文建立起一門新的科學(xué)——熱力學(xué)。內(nèi)燃機(jī)的理論基礎(chǔ)是法國的羅沙在1862年創(chuàng)立的;1876年奧托應(yīng)用羅沙的理論,徹底改進(jìn)了他原來創(chuàng)造的粗陋笨重、噪聲大、熱效率低的內(nèi)燃機(jī)而奠定了內(nèi)燃機(jī)的地位。其他如汽輪機(jī)、燃?xì)廨啓C(jī)、水輪機(jī)等都在理論指導(dǎo)下得到發(fā)展,而理論也在實(shí)踐中得到改進(jìn)和提高。
早在公元前,中國已在指南車上應(yīng)用復(fù)雜的齒輪系統(tǒng),在被中香爐中應(yīng)用了能永保水平位置的十字轉(zhuǎn)架等機(jī)件。古希臘已有圓柱齒輪、圓錐齒輪和蝸桿傳動(dòng)的記載。但是,關(guān)于齒輪傳動(dòng)瞬時(shí)速比與齒形的關(guān)系和齒形曲線的選擇,直到17世紀(jì)之后方有理論闡述。
手搖把和踏板機(jī)構(gòu)是曲柄連桿機(jī)構(gòu)的先驅(qū),在各文明古國都有悠久歷史,但是曲柄連桿機(jī)構(gòu)的形式、運(yùn)動(dòng)和動(dòng)力的確切分析和綜合,則是近代機(jī)構(gòu)學(xué)的成就。機(jī)構(gòu)學(xué)作為一個(gè)專門學(xué)科,遲至19世紀(jì)初才首次列入高等工程學(xué)院(巴黎的工藝學(xué)院)的課程。通過理論研究,人們方能精確地分析各種機(jī)構(gòu),包括復(fù)雜的空間連桿機(jī)構(gòu)的運(yùn)動(dòng),并進(jìn)而能按需要綜合出新的機(jī)構(gòu)。
機(jī)械工程的工作對(duì)象是動(dòng)態(tài)的機(jī)械,它的工作情況會(huì)發(fā)生很大的變化。這種變化有時(shí)是隨機(jī)而不可預(yù)見;實(shí)際應(yīng)用的材料也不完全均勻,可能存有各種缺陷;加工精度有一定的偏差,等等。
與以靜態(tài)結(jié)構(gòu)為工作對(duì)象的土木工程相比,機(jī)械工程中各種問題更難以用理論精確解決。因此,早期的機(jī)械工程只運(yùn)用簡單的理論概念,結(jié)合實(shí)踐經(jīng)驗(yàn)進(jìn)行工作。設(shè)計(jì)計(jì)算多依靠經(jīng)驗(yàn)公式;為保證安全,都偏于保守,結(jié)果制成的機(jī)械笨重而龐大,成本高,生產(chǎn)率低,能量消耗很大。
從18世紀(jì)起,新理論的不斷誕生,以及數(shù)學(xué)方法的發(fā)展,使設(shè)計(jì)計(jì)算的精確度不斷的提高。進(jìn)入20世紀(jì),出現(xiàn)各種實(shí)驗(yàn)應(yīng)力分析方法,人們已能用實(shí)驗(yàn)方法測出模型和實(shí)物上各部位的應(yīng)力。20世紀(jì)后半葉,有限元法和電子計(jì)算機(jī)的廣泛應(yīng)用,使得對(duì)復(fù)雜的機(jī)械及其零。構(gòu)件進(jìn)行力、力矩、應(yīng)力等的分析和計(jì)算成為可能。對(duì)于掌握有充分的實(shí)踐或?qū)嶒?yàn)資料的
機(jī)械或其元件,已經(jīng)可以運(yùn)用統(tǒng)計(jì)技術(shù),按照要求的可靠度,科學(xué)地進(jìn)行機(jī)械設(shè)計(jì)。
機(jī)械工程的發(fā)展展望
機(jī)械工程以增加生產(chǎn)、提高勞動(dòng)生產(chǎn)率、提高生產(chǎn)的經(jīng)濟(jì)性為目標(biāo)來研制和發(fā)展新的機(jī)械產(chǎn)品。在未來的時(shí)代,新產(chǎn)品的研制將以降低資源消耗,發(fā)展?jié)崈舻脑偕茉?,治理、減輕以至消除環(huán)境污染作為超經(jīng)濟(jì)的目標(biāo)任務(wù)。
機(jī)械可以完成人用雙手和雙目,以及雙足、雙耳直接完成和不能直接完成的工作,而且完成得更快、更好。現(xiàn)代機(jī)械工程創(chuàng)造出越來越精巧和越來越復(fù)雜的機(jī)械和機(jī)械裝置,使過去的許多幻想成為現(xiàn)實(shí)。
人類現(xiàn)在已能上游天空和宇宙,下潛大洋深層,遠(yuǎn)窺百億光年,近察細(xì)胞和分子。新興的電子計(jì)算機(jī)硬、軟件科學(xué)使人類開始有了加強(qiáng),并部分代替人腦的科技手段,這就是人工智能。這一新的發(fā)展已經(jīng)顯示出巨大的影響,而在未來年代它還將不斷地創(chuàng)造出人們無法想象的奇跡。
人類智慧的增長并不減少雙手的作用,相反地卻要求手作更多、更精巧、更復(fù)雜的工作,從而更促進(jìn)手的功能。手的實(shí)踐反過來又促進(jìn)人腦的智慧。在人類的整個(gè)進(jìn)化過程中,以及在每個(gè)人的成長過程中,腦與手是互相促進(jìn)和平行進(jìn)化的。
人工智能與機(jī)械工程之間的關(guān)系近似于腦與手之間的關(guān)系,其區(qū)別僅在于人工智能的硬件還需要利用機(jī)械制造出來。過去,各種機(jī)械離不開人的操作和控制,其反應(yīng)速度和操作精度受到進(jìn)化很慢的人腦和神經(jīng)系統(tǒng)的限制,人工智能將會(huì)消除了這個(gè)限制。計(jì)算機(jī)科學(xué)與機(jī)械工程之間的互相促進(jìn),平行前進(jìn),將使機(jī)械工程在更高的層次上開始新的一輪大發(fā)展。
19世紀(jì)時(shí),機(jī)械工程的知識(shí)總量還很有限,在歐洲的大學(xué)院校中它一般還與土木工程綜合為一個(gè)學(xué)科,被稱為民用工程,19世紀(jì)下半葉才逐漸成為一個(gè)獨(dú)立學(xué)科。進(jìn)入20世紀(jì),隨著機(jī)械工程技術(shù)的發(fā)展和知識(shí)總量的增長,機(jī)械工程開始分解,陸續(xù)出現(xiàn)了專業(yè)化的分支學(xué)科。這種分解的趨勢在20世紀(jì)中期,即在第二次世界大戰(zhàn)結(jié)束的前后期間達(dá)到了最高峰。
由于機(jī)械工程的知識(shí)總量已擴(kuò)大到遠(yuǎn)非個(gè)人所能全部掌握,一定的專業(yè)化是必不可少的。但是過度的專業(yè)化造成知識(shí)過分分割,視野狹窄,不能統(tǒng)觀和統(tǒng)籌稍大規(guī)模的工程的全貌和全局,并且縮小技術(shù)交流的范圍,阻礙新技術(shù)的出現(xiàn)和技術(shù)整體的進(jìn)步,對(duì)外界條件變化的適應(yīng)能力很差。封閉性專業(yè)的專家們掌握的知識(shí)過狹,考慮問題過專,在協(xié)同工作時(shí)配合協(xié)調(diào)困難,也不利于繼續(xù)自學(xué)提高。因此自20世紀(jì)中、后期開始,又出現(xiàn)了綜合的趨勢。人們更多地注意了基礎(chǔ)理論,拓寬專業(yè)領(lǐng)域,合并分化過細(xì)的專業(yè)。
綜合-專業(yè)分化-再綜合的反復(fù)循環(huán),是知識(shí)發(fā)展的合理的和必經(jīng)的過程。不同專業(yè)的專家們各具有精湛的專業(yè)知識(shí),又具有足夠的綜合知識(shí)來認(rèn)識(shí)、理解其他學(xué)科的問題和工程整體的面貌,才能形成互相協(xié)同工作的有力集體。
綜合與專業(yè)是多層次的。在機(jī)械工程內(nèi)部有綜合與專業(yè)的矛盾;在全面的工程技術(shù)中也同樣有綜合和專業(yè)問題。在人類的全部知識(shí)中,包括社會(huì)科學(xué)、自然科學(xué)和工程技術(shù),也有處于更高一層、更宏觀的綜合與專業(yè)問題。
The content of mechanical engineering
Mechanical engineering services and multi-faceted, who use machinery, tools, and energy and material production department of mechanical engineering, need the service. The summary mentions, modern machinery engineering has five services: development and provide energy conversion, and provide for mechanical manufacturing all kinds of products and machinery, provide various services in the machinery, the development and provide family and personal life, the development and the application of the machines provide various mechanical weapons.
Regardless of what a field service to the working content of mechanical engineering, basic and same, mainly include:
The establishment and development of mechanical engineering construction and theoretical basis. For example, research force and motion and fluid mechanics, engineering mechanics, Metallic and non-metallic materials to study the performance, and its application in engineering materials, The heat conduction, research and conversion of thermodynamics, All kinds of mechanical components are independent of the function of the working principle, structure, design and calculation of mechanical principle and mechanical parts; Study of metallic and nonmetallic machining and forming technology of metal and technology, etc.
Research, design and development of new products and continuously improving existing machine mechanical products and new generation of mechanical products, in order to adapt to the current and future needs.
Mechanical products production, including: the planning and production facilities, Production plan and production scheduling, Prepare and implement manufacturing process, Design and manufacturing tools, moulds, Determine the quota and material quota, Organization processing, assembling and commissioning and package delivery, For product quality effectively control. Mechanical manufacturing enterprise operation and management. Mechanical general is composed of many each have unique shape, processing precision parts assembled into a complex products. Production batch have single piece and small batch, also have a large batch, until production. Throughout the entire industry and sales target individual, family. And sales in the social and economic situations, may appear under the influence of the big wave. Therefore, mechanical manufacturing enterprise management and operation of enterprises, especially complex production management, planning and management of research are also began in machinery industry.
The application of mechanical products. This includes selection, order, acceptance, installation, adjustment and operation, maintenance, repair and transformation of the industry by use of machinery and complete sets of equipment, to ensure the long-term use of mechanical products in the reliability and efficiency.
The application of mechanical products. This includes selection, order, acceptance, installation, adjustment and operation, maintenance, repair and transformation of the industry by use of machinery and complete sets of equipment, to ensure the long-term use of mechanical products in the reliability and efficiency.
Research in the manufacturing process of mechanical products, especially in the use of the natural resources and environmental pollution, excessive consumption issues, and treatment measures. This is a modern mechanical engineering is particularly important task, and its importance.
Mechanical engineering classification
Mechanical variety, can according to several different ways into various categories, such as: the function can be divided into mechanical power, material handling machinery, machine etc, According to the service industry could be divided into agricultural machinery, mining machinery, textile machinery, etc. According to the principle of work can be divided into the thermal fluid machinery, mechanical, bionic machine, etc. In addition, machinery in the research, development, design, manufacture, application process to work through several stages of nature. According to the different stage, mechanical engineering and can be divided into each other, with several branches system, such as mechanical research, mechanical design, mechanical manufacturing, mechanical using and maintenance, etc.
According to the different aspects of the various branches of system is divided into each other, thus overlap, mechanical engineering may be differentiated into hundreds of branches. For example, according to the function of dynamic mechanical, it points with the working principle of mechanical, thermal fluid machinery, turbine machinery, reciprocating machinery, steam power machinery, nuclear power plant, internal combustion engines, gas turbine, according to industry and the center of power equipment, industrial power plant, locomotives, ship, automobile engineering Marine engineering are complex and overlapping relation. Marine steam turbine power machinery, also is the thermal fluid machinery, mechanical and turbine machinery, it belongs to the Marine power plant, steam power plant, may also belongs to the nuclear power plant etc.
The development of mechanical engineering
Humans become "modern" sign is manufacturing tools. The Stone Age, all sorts of this stone hammers and wood, leather simple tools is rough pioneer of the machinery. From a simple tool to make manufacturing by multiple parts, components of modern machinery, experienced a long process.
Thousands of years ago, humanity has created a shell and crushed grain used to carry mortar and grinding, the JieGao engineer-in-chief with wheels, with the car, the ship sailing in rivers, buildings, and the rudder. The power from the physical, one's own development, using animal, hydraulic and wind. Materials from the natural stone, wood, clay, leather, synthetic materials development. The earliest artificial material is made of pottery and porcelain, is already has the pottery, transmission and three parts of the complete machine work.
Humans from the Stone Age to the Bronze Age, and then to the iron age, to flourish of drum wind blows of the development plays an important role. Have strong enough, the drum wind to get a high enough metallurgical furnace temperature, can have refined metal from ore in. In China, the former 900 years to use the drum for metallurgy, and gradually from the human drum wind to work and hydraulic drum wind.
15-16 centuries ago, mechanical engineering development is slow. But in practice, the millennium project in machinery development and has accumulated much experience and technical knowledge, became the mechanical engineering development potential. Since the 17th century, capitalism in the English, French and European countries, commodity production began to become the center of social problems.
In the 18th century, the application of steam from mining to textiles, flour, metallurgy, etc. The main material of production machines from wood to use more tough, but with manual processing of metal. Mechanical manufacturing industry, and began to form in the decades to become an important industry.
Mechanical engineering through expanding from the practice, the dispersion, mainly depends on the needs of individual talents and craft a skill, gradually develop a theoretical guidance, system and independent engineering technology. Mechanical engineering is 18-19 century and the industrial revolution, the capitalist mechanical production main technological factors.
Power is an important factor of the development of production. In the 17th century, along with the development and improvement of machinery, metal ore with coal and the requirements of increased year by year, people feel rely on human and animal will not produce to a new stage.
In Britain, textile, grinding industries are increasingly using workshop in the river, will work to drive hydraulic machinery. But when the coal mine, the copper ore, etc, with lots of groundwater is only to ascend and excluded. Animal In this production needs, 18 century appeared newcomen atmospheric type steam, mine drainage pumps to drive. But the steam engine fuel consumption, high, basically applies only to mine.
In 1765, watt invented the steam engine have separate condenser, reduce the fuel consumption. 1781 watt and create the steam engine, turning provide motivation of steam expanding the scope of application. The steam engine invented and development, mining and industrial production, railways and shipping to mechanical power. The steam engine was almost in the 19th century, but the only power and steam boiler, condenser, cooling water system huge volume, bulky, application is not easy.
19 century, the power supply system, and the development and popularization of motor start. At the beginning of the 20th century, the motor in industrial production has replaced the steam, become the basic mechanical drive all kinds of work. Production mechanization, already from electrification of electrified by mechanization production function.
Power for the initial application of the steam engine. In the early 20th century, high efficiency, high speed, high steam turbine, also appeared to water resources of the turbine power supply system, promote the vigorous development.
The invention of the late 19th century, has improved combustion through light and small, high efficiency, easy manipulation, and can always start the engine. It is used to drive to work without power supply of land, and mechanical for automobile, mobile machinery and ships, until the middle of 20th century began for locomotives. Steam turbine engine in the crowd, and are no longer important power machinery. After the invention of internal combustion engine and gas turbine, jet engines, is the development of aircraft, such successful development foundation spacecraft technical factor.
Before the industrial revolution, mostly of wood, mechanical hand made by the carpenter. Metal (mainly copper, iron) only to manufacture equipment, lock, clocks, pump and mechanical parts of the small wood. Metal processing of the machine mainly by seiko spy, achieves the need of precision. Steam power plant, and the promotion of the mining, metallurgical appears, ships, large machinery development of locomotive, forming and cutting processing of metal parts, growing more and more and more is also high accuracy requirements. The application of metal materials from copper and iron development to steel.
Mechanical processing including forging, forging, sheet metal work, welding, and heat treatment technology and equipment, and machining technology and machine tools, measuring tools, etc, is rapidly developing, ensuring each industry development for production equipment supply.
The development of social economy, the demand of mechanical products explosion. Production batch of increase and precision machining technology development, promote the formation of large production methods, such as division of professional production and interchangeability parts and collaboration, water processing line and assembly line etc.
Simple interchangeable parts and division of professional production, in ancient collaboration has appeared. In mechanical engineering, the interchangeability embodied in mo for 1797 Bates USES its created by threading lathe of bolts and nuts production. At the same time, the American engineers with interchangeable manufacturing production methods, Whitney, shows the feasibility and superiority of interchangeable. The production methods, in the United States has formed the so-called "American production methods".
In the early 20th century, ford car manufacturing and created the assembly line. Mass production technology in the 19th century and Taylor was that the scientific management method, automobile and other mass production machinery production efficiency quickly reached the height of past cannot imagine.
In the late 20th century, the main characteristics, mechanical processing, continuously improve the machine is processing speed and accuracy, reducing the dependence of craftsmanship, Improve machining and forming, cutting and assembly of mechanization and automation, Using CNC processing center, the group technology, etc, to develop flexible manufacturing systems, small volume and multiple varieties of production efficiency is to improve the level of production, Study hard and improve the processing of metallic and non-metallic materials, new forming and machining technology.
18 centuries ago, mechanical artisan, intuition and experience in mechanical manufacture craft, and almost no scientific association. To 18-19 century, in the emerging of capitalist economy, promote the scientific knowledge of master production, and people start paying attention to direct production needs to start to learn scientific and cultural knowledge, communication between them and made great achievements in mutual inspiration. In this process, and gradually formed a set of basic theory on mechanical engineering.
Mechanical power with the advanced scientific combination. The steam engine invented Avery, pizza, applied physicist watt pat Penn and black theory, Based on the practice in the steam engine, physicists cano, LanJinHe kelvin established a new science - thermodynamics. Engine is based on the theory of France in 1862 LuoSha founded, In 1876, the application of theory LuoSha otto thoroughly improve he had created the rough heavy, noise, low efficiency of internal combustion and laid the position. Other such as steam turbine, gas turbine, etc. In theory, and under the guidance of the theory in practice and improvement.
In early BC, China has applied the car in guide in complex system of gear was applied to the burner and level of the place turn, etc. Ancient Greece had cylindrical gears, bevel gears and worm transmission. However, the instantaneous speed on gear tooth shape and the relationship of tooth profile curve and the 17th century, until after a theory.
The agency's hand and pedal pioneers of crank rod system in the ancient civilization has a long history, but in the form of crank ro