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湖南科技大學2011屆畢業(yè)設(shè)計(論文)開題報告
題 目
柴油機汽缸蓋的工藝規(guī)程及夾具設(shè)計
作者姓名
向睿
學號
1103010411
所學專業(yè)
機械設(shè)計制造及其自動化
意義:?我國作為一個煤炭生產(chǎn)大國,同時作為煤炭消耗大國,煤炭資源只有及其重要礦用絞車與膠帶輸送機作為煤礦機械,礦用絞車主要用于煤礦提升與下放物料等,膠輸送機是煤礦最理想的高效連續(xù)運輸設(shè)備,所以礦用絞車和膠帶輸送機的安全運作對煤礦的生產(chǎn)有及其重要的影響。?本次設(shè)計從實際出發(fā),以煤礦上山運輸系統(tǒng)的選型為主要研究課題。綜合皮帶機參數(shù) 及運動學,動力學要求,從膠帶輸送機與礦用絞車整體選型到各主要部件串車、鋼絲繩、機架結(jié)構(gòu)、自動調(diào)偏裝置、清掃裝置、膠帶、電動機、減速器、拉緊裝置等具體選型設(shè)計??梢哉f這次 課題設(shè)計將用到大量的機電專業(yè)專業(yè)知識,特別是機械學,電工電子學,液壓傳 動、礦山機械學。通過本次設(shè)計,我們將全面系統(tǒng)的溫習之前學習的專業(yè)知識并 加以在實際工程中應(yīng)用,學習分析、解決具有一定復(fù)雜程度的工程實際問題,同 時強化自己計算、繪圖等的能力。這些就是本次課題研究的目的和意義。
現(xiàn)狀: 就國外煤礦機械來說,國外有性能比較高的煤礦機械,但價格昂貴,對國內(nèi)各中小型煤礦并不適用。而對國內(nèi)煤礦機械來說,國內(nèi)煤礦機械呈現(xiàn)多元化現(xiàn)象,發(fā)展也比較快,出現(xiàn)許多種類的煤礦機械,研究出了多種新技術(shù),提高了生產(chǎn)安全性與效率。
問題:國內(nèi)與外國相比還是有不小的差距,差距分為兩方面,一方面為精度,就比如膠帶輸送機,當單機功率大于500KW時,可控GST軟起動比起國內(nèi)無級液力調(diào)速裝置顯示出優(yōu)越性。第二方面為技術(shù)性能,國內(nèi)最高性能煤礦機械已經(jīng)不能滿足高產(chǎn)高效礦井的需要。除這兩方面與國外的差距,國內(nèi)煤礦機械還存在設(shè)備完好率差,有重大事故隱患,制動裝置可靠性差,機械運行質(zhì)量較差,效率低等問題。
1、 研究目標、內(nèi)容和擬解決的關(guān)鍵問題(根據(jù)任務(wù)要求進一步具體化)
2、 特色與創(chuàng)新之處
3、 擬采取的研究方法、步驟、技術(shù)路線
4、 擬使用的主要設(shè)計、分析軟件及儀器設(shè)備
6、參考文獻
注:
1、開題報告是本科生畢業(yè)設(shè)計(論文)的一個重要組成部分。學生應(yīng)根據(jù)畢業(yè)設(shè)計(論文)任務(wù)書的要求和文獻調(diào)研結(jié)果,在開始撰寫論文之前寫出開題報告。
2、參考文獻按下列格式(A為期刊,B為專著)
A:[序號]、作者(外文姓前名后,名縮寫,不加縮寫點,3人以上作者只寫前3人,后用“等”代替。)、題名、期刊名(外文可縮寫,不加縮寫點)年份、卷號(期號):起止頁碼。
B:[序號]、作者、書名、版次、(初版不寫)、出版地、出版單位、出版時間、頁碼。
3、表中各項可加附頁。
3
Of a main selection H ITACH IB & W 6S50HU diesel, the overall performance of this diesel engine is relatively good, but the design of the cylinder head sealing structure there are some flaws. Such defects caused by the use of the machine after a certain period of time, the cylinder head sealing performance significantly decreased, require frequent maintenance lifting cylinder cylinder head to eliminate leakage failure, affect the safety of ships.
1 Fault Overview
This type of diesel engine exhaust, intake manifold, fuel injectors, cylinder head gaskets and other sealing surface with no sealing process, each of these parts are required to carry out maintenance grinding.
1) The main technical parameters of diesel engines. Models, H ITACH IB & W 6S50HU (4-stroke single acting turbo); cylinder diameter, 500 mm; stroke, 540 mm; maximum working pressure, 9. 10MPa; the mean effective pressure, 1. 36MPa; speed, 465 r / m in; power, 3 309 kW.
?2) the structure of the cylinder head seal. Between the cylinder head on cylinder contact surfaces form a planar contact seals. Jacket cooling water through the cooling water jacket leading to the cylinder head. Since there is no gasket, so each time lifting cylinder overhaul, cylinder liners must grind the shoulder and the contact surface of the cylinder head, in order to achieve no gasket sealing requirements. If the contact surface deformation or other mechanical damage, according to the specification requirements, you must use a special tool, respectively, cylinder liners and cylinder head shoulders touching the bottom of the stairs were fine grinding, grinding normally takes about 8 h.
3) Analysis of reducing the sealing performance reasons.
(1) due to multiple causes grinding cylinder head and cylinder liner shoulder contact surfaces to increase, reduce the sealing performance. Technical information provided by the manufacturer show that the type of diesel engine overhaul cycle of lifting cylinder 5 000 h, but according to our inspection of the turbine wheel logs, chief engineer work related records logbook, as well as some long worked in the ship access to the crew, the show since the factory ship, the host for the first time lifting cylinder overhaul when you need to contact surface is polished cylinder seal can not be achieved or 5 000 h operating time. Increase the number of grinding diesel engine overhaul, resulting in contact with the bottom of the cylinder head and cylinder liners stepped shoulder wear increases, the contact with the cylinder liners stepped shoulder to increase the contact surface of the cylinder head sealing performance is getting worse, the most severe cases The diesel engine running 300 h after the need to re-grind the sealing surface. (2) Cylinder head cooling water system is imperfect. Intermediate cooling water jacket design is thin, poor anti resilience performance, Fig. 1 A, S, P, F, respectively jacket cooling water inlet and outlet, and P is the location of the exhaust port is located in the lower portion of the cylinder head is formed local temperature, resulting in local stress increase, it is this generation of local stress so that water jacket into definite warpage. Such warpage will make cylinder liners and cylinder head contact surface unevenness, which caused uneven cylinder head or cylinder liner localized corrosion of high temperature and pressure of the gas, so often the contact surface to be milled. Position after observation of this type of machine, the first is the emergence of air leaks in 1/4 circumference P! F position on.
2 improvements
1) installation of the gasket.
????In the contact surface between the cylinder sleeve and the cylinder head gasket join by adding shims to fill the gap between the cylinder head and cylinder in order to achieve a good seal. At the same time, the use of gasket sealing structure can also improve the performance of the contact between the contact surfaces to some extent, counteract deformation due to the warpage caused by temperature differences.
2) the appropriate choice of material production gasket.
????The maximum combustion pressure of diesel type 9. 1MPa, under the common load conditions, the combustion pressure is 8. 2MPa, under such pressure conditions,
3) increase the cooling water temperature fresh water.
According diesel specification requirements, freshwater cooling water temperature should be controlled within the range of 65 to 70 degrees Celsius, the inspection engine room logs, found the machine in use, the actual cooling fresh water temperature 55 to 60 degrees Celsius, increasing the cooling fresh water temperature, reducing 1/4 stress.
3 Conclusions
After installing the gasket after the host has continuous operation type 4 500 h, the case due to the poor sealing performance cylinder head hanging cylinder in advance did not occur, saving the cost of ship repair. Since there is no gas erosion-corrosion, good sealing surface, eliminating the grinding process, saving maintenance time.
某輪主機選用H ITACH IB&W 6S50HU 柴油機,這種柴油機的總體性能比較優(yōu)秀, 但是其汽缸蓋密封結(jié)構(gòu)的設(shè)計存在一定缺陷。這種缺陷造成機器使用到一定的時間后, 汽缸蓋的密封性能明顯下降,需要頻繁的吊缸檢修以消除汽缸蓋漏氣的故障, 影響船舶安全。
1 故障概述
該類型柴油機的排氣管、進氣管、噴油器、汽缸蓋等密封面采用無墊片密封工藝, 每次檢修均需對上述部位進行精磨。
1) 柴油機的主要技術(shù)參數(shù)。機型, H ITACH IB&W 6S50HU ( 4沖程單作用渦輪增壓) ; 汽缸直徑, 500 mm; 行程, 540 mm;最大工作壓力, 9. 10MPa; 平均有效壓力, 1. 36MPa; 轉(zhuǎn)速, 465 r/m in; 功率, 3 309 kW。
2) 汽缸蓋的密封結(jié)構(gòu)。主機汽缸套與汽缸蓋之間接觸面采用平面接觸式密封形式。缸套冷卻水經(jīng)過冷卻水套通往汽缸蓋。由于沒有墊片, 因此在每次吊缸檢修的時候,必須研磨汽缸套凸肩與汽缸蓋的接觸面, 以達到無墊片密封要求。如果接觸面變形或其它機械性損傷, 根據(jù)說明書要求, 必須使用專用工具, 分別對汽缸套凸肩和汽缸蓋底部接觸的臺階進行精磨, 正常情況下精磨時間約需8 h。
3) 密封性能降低的原因分析。
( 1) 由于多次研磨造成汽缸蓋與汽缸套凸肩接觸面加大, 密封性能降低。廠家提供的技術(shù)資料表明, 該類型的柴油機吊缸檢修周期為5 000 h, 但根據(jù)我們查閱的該輪輪機日志、輪機長工作記錄簿中的相關(guān)記錄, 以及對一些在該船長期工作過的船員的訪問, 表明自該船出廠后, 主機進行第一次吊缸檢修的時候就需要對接觸面進行研磨, 否則汽缸的密封性無法達到5 000 h的工作時間。柴油機檢修時研磨次數(shù)的增加, 造成汽缸蓋底部接觸臺階和汽缸套凸肩磨損量增大, 汽缸蓋的接觸臺階與汽缸套凸肩接觸面加大, 密封性能越來越差, 最嚴重的時候, 該柴油機運轉(zhuǎn)300 h后就需要重新研磨密封面。( 2) 汽缸蓋冷卻水系統(tǒng)設(shè)計的不完善。中間冷卻水套設(shè)計比較單薄 , 抗應(yīng)變力性能差, 圖1中的A、S、P、F分別是缸套冷卻水的進出水口, 而P 的位置正好位于汽缸蓋排氣口的下部, 形成局部的溫差, 造成局部應(yīng)力加大, 正是這種局部應(yīng)力的產(chǎn)生使得水套發(fā)生一定的翹曲現(xiàn)象。這種?翹曲 現(xiàn)象也會使得汽缸套與汽缸蓋的接觸面不均勻, 這種不均勻?qū)е缕咨w或汽缸套的局部被高溫高壓的燃氣腐蝕, 因此經(jīng)常要研磨接觸面。經(jīng)過對該類型機器的觀察, 最先出現(xiàn)漏氣現(xiàn)象的位置就是在P! F位置的1 /4圓周上。?