【文章內容簡介】 徑中心距齒寬因模數(shù)取標準值時，齒數(shù)已重新確定并圓整則重合度系數(shù)齒間載荷分配系數(shù)齒向載荷分布系數(shù)載荷系數(shù)齒形系數(shù)應力修正系數(shù)彎曲疲勞極限彎曲最小安全系數(shù)彎曲壽命系數(shù)尺寸系數(shù)許用彎曲應力驗算 　　　　　　外嚙合直齒圓柱齒輪傳動計算結果(表中) (mm) 名稱符號計算公式小齒輪大齒輪模數(shù)m4齒數(shù)z變位系數(shù)x嚙合角 分度圓直徑d節(jié)圓直徑中心距a實際中心距中心距變動系數(shù)y齒頂高降低系數(shù)齒頂高齒根高齒頂圓直徑齒根圓直徑齒輪寬度B6零件的選擇1鍵的選擇本設計選用的鍵有鍵A2260GB109680,鍵A25100 GB109680,本設計選用的軸承有軸承GB29764 7210，軸承GB29764 7214，軸承GB29764 7216。本設計選用的螺釘有螺釘GB7085M320,螺釘GB7085M420。花鍵的主要失效形式是工作面被壓潰（靜聯(lián)接）或工作面過度磨損（動聯(lián)接）。因此，靜聯(lián)接按工作面的擠壓應力進行強度計算，動聯(lián)接按照工作面上的壓力進行條件性的強度計算。動聯(lián)接花鍵強度條件： （） （） 查表，則計算轉距為： （）  平鍵校核（以電機軸上的平鍵為例，鍵A1060）由文獻[1]平鍵聯(lián)接的強度校核公式可知： (64)式中 T —傳遞的轉矩，D —軸的直徑，m L —鍵的長度，mm L=60—許用應力，=40則有 =所以 =40MPa，所用平鍵合格。 9. 螺釘校核45號鋼的 () () () () 因為,所以強度合格結論經(jīng)過三個月的畢業(yè)設計，現(xiàn)在順利完成了畢業(yè)設計的全部內容。通過此次畢業(yè)設計的訓練深刻體會到工程技術人員的艱辛，同時領會到將理論知識運用到實踐中，是大學四年來知識的全面升華。通過前期的查閱，了解擠出機相關的知識，最終篩選出與單螺桿相關的擠出機文獻資料。之后在參考相關文獻和老師的指導下，完成了初步方案的初步設計。在確定方案后的設計過程中，盡可能將所設計的結構和參數(shù)最優(yōu)化。隨著一次次的改圖和方案的更改，我對螺旋壓力機有了越加深刻的認識，最后完成的排氣擠出機的設計可以實現(xiàn)預定的目的。在這次設計過程中，我認為螺桿的設計是重中之重，關鍵就是螺桿的區(qū)別，通過對排氣螺桿的進一步改進，螺旋壓力機在技術方面還會有更大的發(fā)展，而且對排氣螺桿的改進還可以使整臺機器的污染量下降，對提高環(huán)境質量有很大的提高。畢業(yè)設計在最大程度上綜合了大學所學的知識。基礎課是為專業(yè)知識的鋪墊，為整個的理論計算提供了依據(jù)，是整個設計的基礎。我認為畢業(yè)設計是將基礎知識應用到專業(yè)知識，將專業(yè)知識應用到具體工程實踐的過程。 結束語此次畢業(yè)設計是繼課程設計之后，最重要的一次設計?；ㄙM將近半個學期的時間，終于完成了此次設計所要完成的任務。在此期間，碰到的問題不計其數(shù)，花了大量時間閱讀外文資料和期刊，還有在網(wǎng)上搜索資料，將設計中的問題逐漸減小。這次畢業(yè)設計對我們大學期間所學的知識，也是一次徹底的考察。將以前學的機械基礎知識應用到我們的畢業(yè)設計，再一次鞏固了專業(yè)知識，鍛煉了我們獨立思考問題，解決問題和團隊合作的能力，同時也使我們基本掌握了設計的流程。經(jīng)歷了從查閱資料到設計計算再到結構設計和軟件分析，對于我們學機械的是必須要掌握的，尤其是想從事科學研發(fā)方面的工作的更加重要。還有畢業(yè)設計使我們基本熟練掌握了OFFICE辦公軟件，AUTOCAD制圖軟件，等，這些為即將走上工作崗位的我們，提前做好了鋪墊。參考文獻 《材料力學》 《鍛壓手冊》 《工程制圖學與計算機繪圖》 《機構學》 《機械設計》 《機械設計手冊》 《機械原理》 《機械制造技術》 《計算機繪圖技術》 《理論力學》1 《螺旋壓力機》1 《模具制造工藝學》1 《曲柄壓力機》1 《生物燃料》15 《壓力加工與現(xiàn)代先進加工技術》10外文翻譯英文原文：Biofuel use and its emission of noxious gases in rural ChinaWang Xiaohua
, Feng ZhenminCollege of Engineering, Nanjing Agricultural University, Nanjing 210031, People’s Republic of ChinaReceived 11 August 2003。 accepted 30 September 2003AbstractThis article discusses biomass resources and its consumption in China’s farming area. In 2000, the annual yield of cropstraw was about 6900 Mt, of which 54% could be used as a source of energy. The reasonable supply of firewood was about 150 Mt. The total consumption of biofuel in China’s rural area was 219 Mtce, among which cropstraw and firewood accounted for 44 and 56%, respectively. The proportion of the available heat from mercial energy over the total available heat consumed in the countryside was , and biofuel consumption decreases % annually. China is at a transition point from a period of nonmercial energy to a period of mercial energy being the main source of energy. This article discusses the e?ect of the discharge of noxious gases caused by the consumption of biofuel.Keywords: Biofuel。 Biomass resource。 Noxious gases。 Rural development。 Rural environment。 China1. IntroductionDuring the course of global economic sustainable development, human beings are confronted with immense pressures in population, resources and the environment. The exploitation and utilization of energy is concerned with several factors: Developing countries are faced with the challenge of economic development, especially in the rural area. The energy problem in the rural area is mon in most developing countries. The core of the problem is how to coordinate development energy, society, economy and the environment. Biofuel has been a source of energy which human beings have used since ancient times. It has played an important role during the historical development of human society, and has accounted for more than 15% of China’s energy consumption in recent years. From the environmental point of view, it is part of the essence that poses the ecosystem and will not cause greenhouse warming [1,2].As a very important part of the national energy system, energy supply and consumption in the rural area has a great influence on the development of the rural society, economy and ecological environment. China is a large developing agricultural country, with its rural area largely populated. These areas used to be scarcely supplied with modities and the consumption of mercial energy per capita was low. Nonmercial energy was the main source of energy consumption, which was mainly local biofuel. The increase in population and the sterility of soil gave prominence to the contradiction between the demand and supply of energy, which led to the overconsumption of the local biomass resources and the direct threat to the environment [3–5].With the rapid development of the rural economy and the improvement of peasants’ living conditions, the energy consumption structure of the rural area is undergoing great changes. The demand for mercial energy is rapidly increasing, especially in some rural areas with good economy and modities which consume the main part of the available energy. This led to the superabundance of the original biomass energy source. The improper disposition of the superabundant biomass polluted the atmosphere, waters, and the ecological environment [6–8].Confronted with the pressures from both economical development in the rural area and environmental pr