中雙鏈刮板輸送機(jī)設(shè)計(jì)【8張CAD圖紙+PDF圖】

喜歡就充值下載吧。。資源目錄里展示的文件全都有，，請(qǐng)放心下載，，有疑問(wèn)咨詢QQ:414951605或者1304139763 ======================== 喜歡就充值下載吧。。資源目錄里展示的文件全都有，，請(qǐng)放心下載，，有疑問(wèn)咨詢QQ:414951605或者1304139763 ======================== 中文翻譯 應(yīng)用熱工 三維制動(dòng)器瞬態(tài)溫度場(chǎng)的緊急制動(dòng) 為了準(zhǔn)確掌握在葫蘆的緊急制動(dòng)蹄片的溫度場(chǎng)的變化規(guī)律，制動(dòng)時(shí)，三維（3- D）的瞬態(tài)溫度場(chǎng)的理論模型，根據(jù)熱傳導(dǎo)，能量轉(zhuǎn)換和分布規(guī)律的理論，以及礦山提升機(jī)運(yùn)行的緊急情況制動(dòng)。一種溫度場(chǎng)的解析推導(dǎo)了采用積分變換法。此外，溫度模擬實(shí)驗(yàn)場(chǎng)進(jìn)行了溫度場(chǎng)和溫度梯度和內(nèi)部的變化規(guī)律獲得。同時(shí)，通過(guò)模擬葫蘆的緊急制動(dòng)條件下，實(shí)驗(yàn)測(cè)量制動(dòng)蹄的溫度，同時(shí)進(jìn)行。結(jié)果發(fā)現(xiàn)，通過(guò)比較模擬結(jié)果與實(shí)驗(yàn)數(shù)據(jù)，即三維瞬態(tài)溫度場(chǎng)模型的制動(dòng)蹄片是有效和實(shí)用，和分析解決方案解決了積分變換方法是正確的。 1、 簡(jiǎn)介 提升機(jī)的緊急制動(dòng)是一個(gè)轉(zhuǎn)變過(guò)程機(jī)械能轉(zhuǎn)化為對(duì)制動(dòng)摩擦熱能量。該礦山提升機(jī)緊急制動(dòng)過(guò)程中具有以下特點(diǎn)高速，重載，而這種情況更糟糕的是比剎車條件的車輛，火車等[1-3,6,10,11]。以前對(duì)剎車片的溫度場(chǎng)的重點(diǎn)工作[1-4,10,12,13]。特別是，由于制動(dòng)蹄是固定的過(guò)程中緊急制動(dòng)，所以有更強(qiáng)烈的溫度上升制動(dòng)器蹄片。制動(dòng)蹄片是一種復(fù)合材料，以及溫度上升，從摩擦產(chǎn)生的熱能是最重要的因素影響制動(dòng)器蹄片摩擦磨損性能同制動(dòng)安全性能[5-10]。因此，有必要調(diào)查關(guān)于制動(dòng)器蹄片的溫度場(chǎng)來(lái)調(diào)查剎車片的。 制動(dòng)器蹄片的溫度場(chǎng)目前的理論模型基于一維或二。 Afferrante[11]建立了一個(gè)二維（2- D）的多層模型來(lái)估計(jì)瞬態(tài)演化在多盤離合器溫度擾動(dòng)和在操作過(guò)程中剎車。納吉[12]建立了一維數(shù)學(xué)模型來(lái)描述一個(gè)制動(dòng)熱行為系統(tǒng)。 Yevtushenko和Ivanyk[13]推導(dǎo)了瞬態(tài)溫度場(chǎng)的一軸對(duì)稱熱傳導(dǎo)問(wèn)題2三維坐標(biāo)。這是困難的這些模式，以反映制動(dòng)器蹄片真實(shí)溫度場(chǎng)的三維幾何圖形。 解決的方法剎車片的三維瞬態(tài)溫度場(chǎng)集中有限元法[1-3,14-17]，近似集成的方法[4,18]，格林函數(shù)法[12]和Laplace變換方法[9,13]等，前三者方法是數(shù)值求解方法和低是相對(duì)的準(zhǔn)確性。例如，有限元方法可以解決復(fù)雜熱傳導(dǎo)問(wèn)題，但計(jì)算精度解決方案是比較低，這是影響網(wǎng)密度，步長(zhǎng)等。雖然拉普拉斯變換解決方法是分析方法，它是難以解決的方程復(fù)雜邊界的熱傳導(dǎo)。因此，所謂的解析解積分變換方法通過(guò)[19]，因?yàn)樗墙鉀Q問(wèn)題的合適非均質(zhì)瞬態(tài)熱傳導(dǎo)。為了掌握制動(dòng)器蹄片的溫度變化規(guī)律在葫蘆的緊急制動(dòng)領(lǐng)域，提高安全可靠性制動(dòng)，一個(gè)3- D的制動(dòng)器蹄片瞬態(tài)溫度場(chǎng)研究了在積分變換方法的基礎(chǔ)上，和有效性證明了數(shù)值模擬和實(shí)驗(yàn)研究。 2、 理論分析 2、1理論模式 圖1顯示了葫蘆的制動(dòng)摩擦副示意圖。為了分析制動(dòng)器蹄片的三維溫度場(chǎng)，圓柱坐標(biāo)（r，，z）是通過(guò)結(jié)構(gòu)來(lái)描述幾何如圖所示。 2，其中R是剎車點(diǎn)之間的距離和制動(dòng)盤的旋轉(zhuǎn)軸; 為圓心角;這三者之間的制動(dòng)蹄摩擦點(diǎn)和表面的距離。至于幾何結(jié)構(gòu)參數(shù)和圖2所示。它看到，顯然，這是制動(dòng)器蹄片的溫度T是函數(shù)的圓柱坐標(biāo)（r，，z）和時(shí)間（t）。根據(jù)熱理論傳導(dǎo)，三維瞬態(tài)熱傳導(dǎo)微分方程是獲得如下： （1） 其中a是熱擴(kuò)散，；是熱導(dǎo)率；為密度；是比熱容量。 2.2、邊界條件 2.2.1、熱流量及其分布系數(shù) 這是在緊急制動(dòng)產(chǎn)生的摩擦熱難要在短時(shí)間內(nèi)發(fā)出，因此它幾乎完全吸收剎車對(duì)。由于制動(dòng)器蹄片是固定的，摩擦溫度多面大幅上升，這最終會(huì)影響其摩擦學(xué)更嚴(yán)重的行為。為了掌握真實(shí)該制動(dòng)器蹄片溫度場(chǎng)在緊急制動(dòng)時(shí)，熱流量及其分布系數(shù)摩擦表面必須確定準(zhǔn)確。根據(jù)操作緊急制動(dòng)，條件假設(shè)制動(dòng)速度光盤隨時(shí)間呈線性，熱流量，得到公式 （2） 其中q為熱摩擦表面流動(dòng); P是比壓之間的制動(dòng)對(duì); 的和是最初的線性和角速度在制動(dòng)盤; l是剎車副之間的摩擦系數(shù); 是整個(gè)制動(dòng)時(shí)間，k是熱分布流系數(shù)。假設(shè)摩擦熱量轉(zhuǎn)移到完全制動(dòng)運(yùn)動(dòng)鞋和制動(dòng)盤，分布的熱流量系數(shù)根據(jù)得到的一維熱傳導(dǎo)分析。圖。 3顯示了聯(lián)系兩個(gè)半平面示意圖。在一維瞬態(tài)熱傳導(dǎo)的條件，對(duì)摩擦表面（z = 0處）的溫度上升，得到公式 （3） 其中q為在平面吸收一半熱流。和熱流量是從Eq獲得的 （4） 假設(shè)兩個(gè)半飛機(jī)具有相同的溫度上升，對(duì)摩擦表面，然后在熱流量比進(jìn)入兩個(gè)半平面可表示為 其中下標(biāo)S和D意味著制動(dòng)器蹄片和制動(dòng)盤，分別。根據(jù)Eq。（5），分配系數(shù)熱流根據(jù)這個(gè)公式獲得進(jìn)入制動(dòng)器蹄片。 2.2.2、在邊界系數(shù)對(duì)流換熱 至于側(cè)面和頂面制動(dòng)器蹄片，得到他們的對(duì)流換熱系數(shù)，分別按自然對(duì)流換熱邊界條件直立板和橫板 圖1-制動(dòng)摩擦副示意圖 圖2、三維幾何模型的制動(dòng)器蹄片。 圖3、兩個(gè)半平面示意圖 其中下標(biāo)L和U代表側(cè)面和頂部表面，h分別為對(duì)流換熱系數(shù)在邊界上，DT是之間的溫差邊界和環(huán)境，L是較短維邊界。 2.2.3、初始和邊界條件 制動(dòng)器蹄片之間的接觸和制動(dòng)盤表面受到不斷熱流在緊急制動(dòng)過(guò)程qs的。 制動(dòng)蹄片的邊界都用空氣的自然對(duì)流。邊界和初始條件可以表示為 其中是制動(dòng)器蹄片在t=0的初始溫度。 2.3。積分變換求解方法 積分變換的方法有兩個(gè)解決問(wèn)題的步驟。首先，只有作出適當(dāng)?shù)姆e分變換空間 變量，熱傳導(dǎo)原方程可以簡(jiǎn)化由于考慮到時(shí)間與常微分方程變量t然后，通過(guò)采取逆變換關(guān)于解常微分方程的解析解在關(guān)于空間和時(shí)間變量溫度場(chǎng)可以得到的。積分變換方法應(yīng)用于求解方程。 （1）邊界條件方程。（8）。用積分變換有關(guān)空間變量（r，，z）的反過(guò)來(lái)，他們可能會(huì)偏微分方程是''消滅“。編寫公式來(lái)表示的運(yùn)作采取逆變換與積分變換方面到Z，這些被定義為 其中是的積分變化，是特征函數(shù)。 提交Eq，獲得以下方程： 以同樣的方式，逆變換與積分變換關(guān)于和r分別定義 最后，根據(jù)上面的積分變換，方程1）（8）可以簡(jiǎn)化為如下： 解決方案可以獲得通過(guò)解式。(16)。以反變換關(guān)于根據(jù)Eqs。(九)、(12)和(14),的解析制動(dòng)器的三維瞬態(tài)溫度場(chǎng)分布 3.仿真和實(shí)驗(yàn) 圖4顯示了一半的制動(dòng)器剖面樣品。線c、d的中心線,底線的橫截面上的分別。樣品的尺寸是:一個(gè)= 137.5 mm,b = = 1 / 6毫米,半162.5 rad,l = 6毫米。閘瓦的材料和盤式制動(dòng)器是石棉和16Mn,分別。他們的參數(shù)和條件的緊急制動(dòng)見(jiàn)表1。 假設(shè)摩擦系數(shù)和制動(dòng)襯墊比壓在緊急制動(dòng)過(guò)程是不變的?；谝陨戏治瞿Ｐ?模擬閘瓦的三維溫度場(chǎng)進(jìn)行與到…= 7.23 s。溫度的變化規(guī)律 圖4 把剖面的一半剎車蹄的樣品 表1剎車副的基本參數(shù)和緊急制動(dòng)條件 與內(nèi)部溫度梯度場(chǎng)進(jìn)行了分析。什么是顯示在無(wú)花果里都是片面的。5 - 9的仿真結(jié)果相符合。 什么是顯示在圖5是閘瓦的三維溫度場(chǎng)當(dāng)時(shí)間7.23 s。它被認(rèn)為是從圖5的最高溫度是396.534閘瓦制動(dòng),其K后最低溫度和熱是能量293歐幾里得主要集中 圖5 三維溫度場(chǎng)的剎車蹄(t = 7.23 s) 圖6 溫度的改變對(duì)摩擦表面與時(shí)間t 圖7 溫度的改變對(duì)線d用時(shí)間t 圖8 溫度梯度的變化與時(shí)間線c t 圖9 溫度的改變不同深度隨時(shí)間的線c t 層上的摩擦表面的熱影響層(命名),既體現(xiàn)了熱diffusibility閘瓦的很差。為了靈便的溫度變化規(guī)律的摩擦表面,在緊急制動(dòng)過(guò)程的摩擦表面的變化的溫度與時(shí)間t進(jìn)行了模擬。什么是在圖6中顯示,揭示了摩擦表面的溫度,然后增加首先減小的趨勢(shì)。這是因?yàn)?高速度的盤式制動(dòng)器是在開(kāi)始的時(shí)候,結(jié)果造成大heat-flow而對(duì)流換熱系數(shù)低邊界上的那一刻,所以溫度增加;后期的制動(dòng)的heatflow量減少的速度,而對(duì)流換熱系數(shù)高,由于溫差較大的差異,從而導(dǎo)致減少邊界溫度。無(wú)花果。6、7,反映了溫度變化規(guī)律進(jìn)行了徑向尺寸:在外面的溫度高于閘瓦里面,并且外面的溫度變化較大。 圖8論證了溫度梯度的變化規(guī)律的方向沿z。最高溫度梯度的摩擦層是由3.739 105 K / m與方向會(huì)急驟下降沿z。最低價(jià)值只是4.597 1011 K / m。在開(kāi)始的時(shí)候,溫度梯度的熱影響層是最高,而溫度接近周圍的溫度。象剎車的推移,溫度梯度漸次降低,直到最后。圖9所示的是變化的溫度不同深度隨時(shí)間的線c t。溫度會(huì)急驟下降隨著z,、邊界條件等影響有窩內(nèi)部溫度。溫度增高但z P0.0006米。一旦z是由0.002米,制動(dòng)過(guò)程中溫度的差別小于3 k .這表明,熱能集中在熱影響層,其厚度是關(guān)于0.002米。 為了證明的解析模型,實(shí)驗(yàn)進(jìn)行了摩擦試驗(yàn)機(jī),如圖10。實(shí)驗(yàn)原理如下:當(dāng)剎車開(kāi)始,兩種制動(dòng)蹄制動(dòng)圓盤也要被推遲到一定壓力p和溫度點(diǎn)e在摩擦表面熱電偶測(cè)量。因?yàn)樵嚇雍穸忍?而且摩擦試驗(yàn)機(jī)的結(jié)構(gòu)是有限的,很難固定熱電偶在剎車蹄。因此,熱電偶是固定的直接對(duì)盤式制動(dòng)器是封閉,點(diǎn)e列圖。10。圖11顯示的溫度變化規(guī)律的兩種情況下點(diǎn)在e的緊急制動(dòng)。 從圖11,觀察點(diǎn)e增加時(shí)的溫度,在第一,然后減少,最高溫度低于,通過(guò)仿真實(shí)驗(yàn)數(shù)據(jù)也落后。在圖11a,模擬溫度達(dá)到最大427.14凱西在3.6 s而來(lái)的實(shí)驗(yàn)數(shù)據(jù)和最大435.65凱西在3.8秒。在圖11b,仿真結(jié)果達(dá)到最大469.55凱西在4.5 s而來(lái)到479.68實(shí)驗(yàn)數(shù)據(jù)K在5秒。它被認(rèn)為是從圖11,通過(guò)實(shí)驗(yàn)測(cè)量溫度低于仿真結(jié)果,在第一,然后它相反的。這是因?yàn)闊犭娕急旧淼哪芰课諢崃块l瓦在開(kāi)始,然后將其釋放到剎車蹄當(dāng)溫度下降。對(duì)比實(shí)驗(yàn)數(shù)據(jù)和仿真結(jié)果表明,仿真結(jié)果表明,兩者吻合較好,誤差的實(shí)驗(yàn),他們的最高溫度是1.99% 圖10 圖解的摩擦測(cè)試儀。 圖11a 溫度的變化規(guī)律與時(shí)刻t的e點(diǎn)(p = 1.38 = 0 - 1兆帕,證明米/秒)。 圖11b 溫度的變化規(guī)律與時(shí)刻t的e點(diǎn)(p = 1.5895%兆帕,證明=長(zhǎng)1 - 2.5米/秒)。 和2.16%,分別。這表明,解析解的三維瞬態(tài)溫度場(chǎng)是正確的。 4.結(jié)論 (1)的理論模型建立了三維瞬態(tài)溫度場(chǎng)的理論根據(jù)熱傳導(dǎo)及緊急制動(dòng)條件的礦山提升機(jī)。這個(gè)積分變換方法應(yīng)用于解決的理論模型,并對(duì)溫度場(chǎng)的解析解,推導(dǎo)出。這表明,積分變換方法是有效解決這一問(wèn)題的三維瞬態(tài)溫度場(chǎng)。 (2)基于解析解的理論模型,并采用數(shù)值分析模擬溫度分布的變化規(guī)律下緊急制動(dòng)狀態(tài)。仿真結(jié)果表明:摩擦表面溫度的增加降低;首先,然后在開(kāi)始的溫度梯度的熱影響層的最高,其次是溫度增加迅速,正如制動(dòng)過(guò)程正在進(jìn)行中,溫度梯度溫度的增加呈減少趨勢(shì);窩;邊界條件影響了內(nèi)部溫度上升;熱能量都集中在熱影響層,其厚度約2毫米。 (3) 實(shí)驗(yàn)數(shù)據(jù)與仿真結(jié)果吻合良好,誤差對(duì)他們的最高溫度是大約2%,這證明了積分變換方法的正確性求解理論模型的三維瞬態(tài)溫度場(chǎng)。解析模型能夠反映出的變化規(guī)律閘瓦的三維瞬態(tài)溫度場(chǎng)在緊急剎車。 出處 本項(xiàng)目是支持的重點(diǎn)工程,中國(guó)教育部(批準(zhǔn)號(hào):)資助107054)和程序?yàn)樾率兰o(jì)優(yōu)秀人才(批準(zhǔn)號(hào):)資助的大學(xué)。NCET-04-0488)。 參考 [1] y .楊、江康鈺周、數(shù)值模擬研究的三維熱應(yīng)力場(chǎng)與復(fù)雜邊界問(wèn)題,《工程熱27(3)(2007)487-489。 [2] l . j .的歌,Z.Y.李郭的研究;(3)快速有限元的仿真模型,對(duì)車輛制動(dòng)熱分析系統(tǒng)仿真學(xué)報(bào),17(12)(2005)。2877 2869-2872。 [3] 邱智賢高,X.Z.林、瞬態(tài)溫度場(chǎng)分析剎車在引入非完全軸對(duì)稱三維模型、期刊的材料加工技術(shù)129(1 - 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3.該題目由該同學(xué)單獨(dú)完成，經(jīng)由嚴(yán)謹(jǐn)?shù)臄?shù)學(xué)計(jì)算，具有較高的工作量； 4.選題完全符合專業(yè)培養(yǎng)目標(biāo)，屬于機(jī)械設(shè)計(jì)制造工藝的一種,對(duì)即將畢業(yè)的學(xué)生的再學(xué)習(xí)有著較好的指引作用, 不僅僅局限在機(jī)械基礎(chǔ)知識(shí)上，更涉及了有關(guān)材料學(xué)、力學(xué)等多學(xué)科知識(shí)，使我們對(duì)交叉學(xué)科有了一定的涉足，綜合訓(xùn)練的要求也得到充分的體現(xiàn)。 二、開(kāi)題報(bào)告完成情況： 開(kāi)題報(bào)告已完成 三、階段性成果： 1.開(kāi)題報(bào)告和實(shí)習(xí)報(bào)告已完成； 2.英文摘要完成； 3.部分零件圖已完成 四、存在主要問(wèn)題： 1. 專業(yè)基礎(chǔ)知識(shí)學(xué)習(xí)不夠深入； 2.設(shè)計(jì)經(jīng)驗(yàn)欠缺； 3.參考資料收集有限； 4.設(shè)計(jì)思路不是很清晰； 5..繪圖軟件操作不是很熟 五、指導(dǎo)教師對(duì)學(xué)生在畢業(yè)實(shí)習(xí)中，勞動(dòng)、學(xué)習(xí)紀(jì)律及畢業(yè)設(shè)計(jì)（論文）進(jìn)展等方面的評(píng)語(yǔ) 指導(dǎo)教師： （簽名） 年 月 日 3 本科畢業(yè)設(shè)計(jì)（論文）開(kāi)題報(bào)告 題目名稱 刮板輸送機(jī) 學(xué)生姓名 專業(yè)班級(jí) 學(xué)號(hào) 一、 選題的目的和意義： 刮板輸送機(jī)作為煤礦工作面運(yùn)輸設(shè)備，不僅擔(dān)負(fù)著運(yùn)煤的作用，而且作為采煤機(jī)的運(yùn)行軌道、液壓支架的推移支點(diǎn)、還要懸掛工作面設(shè)備的電纜、水管等。所以，刮板輸送機(jī)的可靠、穩(wěn)定、高效運(yùn)行將直接影響著礦井的生產(chǎn)能力和煤礦企業(yè)的經(jīng)濟(jì)效益。 刮板輸送機(jī)主要供采煤工作面使用。它要求機(jī)身高度小，便于裝載；運(yùn)輸能力滿足使用地點(diǎn)的生產(chǎn)需要；結(jié)構(gòu)堅(jiān)固，能抵抗壓、砸和碰撞；變更運(yùn)輸距離時(shí)，加長(zhǎng)和縮短方便；能夠不拆卸用機(jī)械移置。 單鏈刮板輸送機(jī)結(jié)構(gòu)簡(jiǎn)單，沒(méi)有鏈子受力不均現(xiàn)象，裝載面積大，彎曲性能好。當(dāng)采用特殊的導(dǎo)向裝置時(shí)，可以轉(zhuǎn)彎90°，它的拐彎部分代替了順槽轉(zhuǎn)載機(jī)，可以直接將工作面的煤炭卸到順槽可伸縮膠帶輸送機(jī)上，減少了輸送環(huán)節(jié)，實(shí)現(xiàn)了一機(jī)多用。也就是說(shuō)，刮板輸送機(jī)在生產(chǎn)中占有非常重要的地位，而單鏈刮板輸送機(jī)又有著結(jié)構(gòu)簡(jiǎn)單、裝載面積大、彎曲性能好等優(yōu)點(diǎn)，在實(shí)際生產(chǎn)中有著十分優(yōu)越的性質(zhì)，所以通過(guò)本次設(shè)計(jì)，完成單鏈刮板輸送機(jī)的結(jié)構(gòu)設(shè)計(jì)具有很大的實(shí)用意義。 二、 國(guó)內(nèi)外研究綜述： 我國(guó)綜采機(jī)械化的應(yīng)用始于20世紀(jì)70年代末，經(jīng)過(guò)20多年的發(fā)展，目前我國(guó)中、小功率刮板輸送機(jī)已具備成型技術(shù)，并有成熟的制造能力，完全能夠滿足國(guó)內(nèi)市場(chǎng)的需求。大功率刮板輸送機(jī)通過(guò)成套引進(jìn)國(guó)外的裝備和技術(shù)，成功地進(jìn)行了國(guó)產(chǎn)化研制工作，并相繼推出了一些產(chǎn)品。從總體水平上看，我國(guó)刮板輸送機(jī)發(fā)展現(xiàn)狀與國(guó)外相比還存在一些差距，主要表現(xiàn)在：基礎(chǔ)研究薄弱，缺少?gòu)?qiáng)有力的理論支持，計(jì)算少，靠經(jīng)驗(yàn)取值多，缺乏專門的開(kāi)發(fā)分析軟件；受基礎(chǔ)工業(yè)水平的制約，國(guó)產(chǎn)輸送機(jī)制造質(zhì)量不穩(wěn)定，元部件的可靠性還有待提高；大功率刮板輸送機(jī)的關(guān)鍵部件仍需進(jìn)口，有待進(jìn)一步研發(fā)并國(guó)產(chǎn)化；安全性和可靠性的不穩(wěn)定，直接制約了煤礦的生產(chǎn)效率，從而不能從根本上降低使用成本；煤礦管理水平落后，資金不足，礦工不按操作規(guī)程操作等，也間接增加了輸送機(jī)發(fā)生故障的機(jī)會(huì)，從而不能最大限度地發(fā)揮設(shè)備的設(shè)計(jì)能力。 自世界上第一臺(tái)刮板輸送機(jī)誕生以來(lái)，經(jīng)歷了半個(gè)多世紀(jì)的不斷研究、試驗(yàn)、改進(jìn)，刮板輸送機(jī)已成為煤礦運(yùn)輸?shù)闹饕O(shè)備。目前世界上生產(chǎn)刮板輸送機(jī)的國(guó)家主要有德國(guó)、美國(guó)、英國(guó)、澳大利亞、日本等，機(jī)型從輕型、中型到重型、超重型，裝機(jī)功率已發(fā)展到3×700kW。保護(hù)形式有：彈性聯(lián)軸器、限矩型液力耦合器、雙速電機(jī)、調(diào)速型液力耦合器、軟啟動(dòng)(CST可控傳動(dòng)裝置、閥控調(diào)速型液力耦合器、交流電機(jī)變頻調(diào)速技術(shù)三種軟啟動(dòng)裝置)等等。 三、 畢業(yè)設(shè)計(jì)（論文）所用的主要技術(shù)與方法： 1， 畢業(yè)設(shè)計(jì)所用方法：類比設(shè)計(jì)、優(yōu)化設(shè)計(jì)、經(jīng)驗(yàn)設(shè)計(jì)以及數(shù)據(jù)計(jì)算等方法。在資料和信息獲取過(guò)程進(jìn)行了實(shí)地考察和調(diào)研。 2， 在繪圖過(guò)程中運(yùn)用計(jì)算機(jī)繪圖。 3， 在外型設(shè)計(jì)中運(yùn)用運(yùn)用人機(jī)工程學(xué)方法 四、 主要參考文獻(xiàn)與資料獲得情況： 金曉穎．刮板輸送機(jī)的發(fā)展趨勢(shì)．中州煤炭，2007，(4)：43-45 韓幼祥．刮板輸送機(jī)的改進(jìn)．煤礦機(jī)械，2005，(6)：106-107 孫幼蘭，廖建勇．國(guó)外工作面刮板輸送機(jī)發(fā)展動(dòng)向．煤礦機(jī)械，1990，（10）：1-4 薛金河，張秀全，李精草．刮板輸送機(jī)發(fā)展概況．煤礦機(jī)械，2002．（1）：4-5 王琳．刮板輸送機(jī)的優(yōu)化設(shè)計(jì)．煤礦機(jī)械，2007，28(10)：19-21 張超軍，張志民，王宏洋．刮板輸送機(jī)中部槽的耐磨處理．煤礦機(jī)械，2007，28(6)：109-110 羅慶吉，石國(guó)祥．綜采工作面刮板輸送機(jī)的現(xiàn)狀和發(fā)展趨勢(shì)．煤礦機(jī)電，2000．（5）：54-57 五、 畢業(yè)設(shè)計(jì)（論文）進(jìn)度安排（按周說(shuō)明） 第4～5周 調(diào)研、查資料、完成畢業(yè)實(shí)習(xí)報(bào)告 第6～8周 總體方案確定、系統(tǒng)總體設(shè)計(jì) 第9～12周 詳細(xì)設(shè)計(jì) 第13～14周 編制設(shè)計(jì)說(shuō)明書(shū)，準(zhǔn)備答辯 六、 指導(dǎo)教師審批意見(jiàn)： 指導(dǎo)教師： （簽名） 年 月 日 4 Three-dimensional transient temperature field of brake shoe during hoistsemergency brakingZhen-cai Zhu, Yu-xing Peng*, Zhi-yuan Shi, Guo-an ChenCollege of Mechanical and Electrical Engineering, China University of Mining and Technology, Xuzhou 221116, Chinaa r t i c l ei n f oArticle history:Received 22 November 2007Accepted 27 April 2008Available online 6 May 2008Keywords:Brake shoeThree-dimensionalTransient temperature fieldIntegral-transform methodEmergency brakingHoista b s t r a c tIn order to exactly master the change rules of brake shoes temperature field during hoists emergencybraking, the theoretical model of three-dimensional (3-D) transient temperature field was establishedaccording to the theory of heat conduction, the law of energy transformation and distribution, and theoperating condition of mining hoists emergency braking. An analytic solution of temperature field wasdeduced by adopting integral-transform method. Furthermore, simulation experiments of temperaturefield were carried out and the variation regularities of temperature field and internal temperature gradi-ent were obtained. At the same time, by simulating hoists emergency braking condition, the experimentsfor measuring brake shoes temperature were also conducted. It is found, by comparing simulation resultswith experimental data, that the 3-D transient temperature field model of brake shoe is valid and prac-tical, and analytic solution solved by integral-transform method is correct.? 2008 Elsevier Ltd. All rights reserved.1. IntroductionThe hoists emergency braking is a process of transformingmechanical energy into frictional heat energy of brake pair. Theemergency braking process of mining hoist has the characteristicof high speed and heavy load, and this situation is worse than brak-ing condition of vehicle, train and so on 13,6,10,11. The previouswork focused on the brake pads temperature field 14,10,12,13.Especially, because the brake shoe is fixed during the process ofemergency braking, so there is more intense temperature rise inbrake shoe. The brake shoe is kind of composite material, and thetemperature rise resulting from frictional heat energy is the mostimportant factor affecting tribological behavior of brake shoe andthe braking safety performance 510. Therefore, it is necessaryto investigate the brake shoes temperature field with respect toinvestigating brake pads.Current theoretical models of brake shoes temperature field arebased on one dimension or two. Afferrante 11 built a two-dimen-sional (2-D) multilayered model to estimate the transient evolu-tion of temperature perturbations in multi-disk clutches andbrakes during operation. Naji 12 established one-dimensionalmathematical model to describe the thermal behavior of a brakesystem. Yevtushenko and Ivanyk 13 deduced the transient tem-perature field for an axi-symmetrical heat conductivity problemwith 2-D coordinates. It is difficult for these models to reflect thereal temperature field of brake shoe with 3-D geometry.The methods solving brake pads 3-D transient temperaturefield concentrated on finite element method 13,1417, approx-imate integration method 4,18, Greens function method 12 andLaplace transformation method 9,13, etc. The former threemethods are numerical solution methods and are of low relativeaccuracy. For example, finite element method can solve the com-plicate heat conduction problem, but the accuracy of computa-tional solution is relatively low, which is affected by meshdensity, step length and so on. Though the Laplace transformationmethod is an analytic solution method, it is difficult to solve theequation of heat conduction with complicated boundaries. There-fore, the analytic solution called integral-transform method isadopted 19, because it is suitable for solving the problem ofnon-homogeneous transient heat conduction.In order to master the change rules of brake shoes temperaturefieldduringhoistsemergencybrakingandimprovethesafereliabil-ity of braking, a 3-D transient temperature field of the brake shoewas studied based on integral-transform method, and the validityis proved by numerical simulation and experimental research.2. Theoretical analysis2.1. Theoretical modelFig. 1 shows the schematic of hoists braking friction pair. In or-der to analyze brake shoes 3-D temperature field, the cylindricalcoordinates (r,u,z) is adopted to describe the geometric structureshown in Fig. 2, where r is the distance between a point of brakeshoe and the rotation axis of brake disc; u is the central angle; z1359-4311/$ - see front matter ? 2008 Elsevier Ltd. All rights reserved.doi:10.1016/j.applthermaleng.2008.04.022* Corresponding author. Tel.: +86 13805209649; fax: +86 516 83590708.E-mail address: (Y.-x. Peng).Applied Thermal Engineering 29 (2009) 932937Contents lists available at ScienceDirectApplied Thermal Engineeringjournal homepage: the distance between a point of brake shoe and the friction sur-face. As for the geometric structure and parameters shown in Fig. 2,its seen that a 6 r 6 b, 0 6 u 6 u0, 0 6 z 6 l. It is clear that thebrake shoes temperature T is the function of the cylindrical coor-dinates (r,u,z) and the time (t). According to the theory of heatconduction, the differential equation of 3-D transient heat conduc-tion is gained as follows:o2Tor21roTor1r2o2Tou2o2Toz21aoTot;1whereais the thermal diffusivity,a= k /(q? c); k is the thermal con-ductivity;qis the density; c is the specific heat capacity.2.2. Boundary condition2.2.1. Heat-flow and its distribution coefficientIt is difficult for friction heat generated during emergency brak-ing to emanate in a short time, so it is almost totally absorbed bybrake pair. As the brake shoe is fixed, the temperature of the fric-tion surface rises much sharply, and this eventually affects its tri-bological behavior more seriously. In order to master the realtemperature field of the brake shoe during emergency braking,the heat-flow and its distribution coefficient of friction surfacemust be determined with accuracy. According to the operatingcondition of emergency braking, suppose that the velocity of brakedisc decreased linearly with time, the heat-flow is obtained withthe formqsr;t k ?l? p ? v0? 1 ? t=t0 k ?l? p ? w0? r:1 ? t=t0;2where q is the heat-flow of friction surface; p is the specific pressurebetweenbrakepair;v0andw0istheinitiallinearandangularvelocityof the brake disc;listhe frictioncoefficient betweenbrakepair; t0isthe whole braking time, k is the distribution coefficient of heat-flow.Suppose the frictional heat is totally transferred to the brakeshoe and brake disk, and the distribution coefficient of heat-flowis obtained according to the analysis of one-dimensional heat con-duction. Fig. 3 shows the contact schematic of two half-planes.Under the condition of one-dimensional transient heat conduc-tion, the temperature rise of friction surface (z = 0) is obtained withthe formDT qkffiffiffiffippffiffiffiffiffiffiffiffi4atpqffiffiffiffiffiffiffiffiffiffiffiffipqckpffiffiffiffiffi4tp;3where q is the heat-flow absorbed by half-plane. And the heat-flowis gained from Eq. (3)q ffiffiffiffiffiffiffiffiffiffiffiffipqckpDT=ffiffiffiffiffi4tp:4Suppose the two half-planes has the same temperature rise onthe friction surface, and then the ratio of heat-flow entering thetwo half-planes is given asqsqdffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffipqscskspDT=ffiffiffiffiffi4tpffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffipqdcdkdpDT=ffiffiffiffiffi4tpffiffiffiffiffiffiffiffiffiffiffiffiffiqscskspffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiqdcdkdp;5where the subscript s and d mean the brake shoe and brake disc,respectively. According to Eq. (5), the distribution coefficient ofheat-flow entering brake shoe is obtained with the formk qsqaqsqs qd 1 ?qdqs qd 1 ?1qsqd 1 1 ?11 qscsksqdcdkd?12:62.2.2. Coefficient of convective heat transfer on the boundaryWith regard to the lateral surface and the top surface of thebrake shoe, their coefficients of convective heat transfer are ob-tained, respectively, according to the natural heat convectionboundary condition of upright plate and horizontal platehl 1:42DTl=Ll14;7ahu 0:59DTu=Lu14;7bFig. 1. Schematic of hoists braking friction pair.Fig. 2. 3-D geometrical model of brake shoe.Fig. 3. Contact schematic of two half-planes.Z.-c. Zhu et al./Applied Thermal Engineering 29 (2009) 932937933where the subscript l and u represent the lateral surface and the topsurface, respectively; h is the coefficient of convective heat transferon the boundary,DT is the temperature difference between theboundary and the ambient, L is the shorter dimension of theboundary.2.2.3. Initial and boundary conditionContact surface between brake shoe and brake disc is subjectedto continuous heat-flow qsduring emergency braking process.Brake shoes boundaries are of natural convection with the air.The boundary and initial condition can be represented by? koTor h1T h1T0 f1t;r a; t P 0; 0 6u6u0;0 6 z 6 l;8akoTor h2T h2T0 f2t;r b; t P 0; 0 6u6u0;0 6 z 6 l;8b? koToz h3T qs h3T0 f3t;z 0; t P 0;0 6u6u0; a 6 r 6 b;8ckoToz h4T h4T0 f4t;z l; t P 0; 0 6u6u0;a 6 r 6 b;8d? k1roTou h5T h5T0 f5t;u 0; t P 0; 0 6 z 6 l;a 6 r 6 b;8ek1roTou h6T h6T0 f6t;uu0; t P 0; 0 6 z 6 l;a 6 r 6 b;8fTr;u;z;t T0;t 0; a 6 r 6 b; 0 6u6u0;0 6 z 6 l;8gwhere T0is the initial temperature of the brake shoe at t = 0.2.3. Integral-transform solving methodIntegral-transform method has two steps for solving the prob-lem. Firstly, only by making suitable integral-transform for spacevariable, the original equation of heat conduction could be simpli-fied as the ordinary differential equation with regard to the timevariable t. Then, by taking inverse transform with regard to thesolution of the ordinary differential equation, the analytic solutionof the temperature field with regard to the space and time vari-ables could be obtained.Integral-transform method is applied to solve Eq. (1) withboundary condition Eq. (8). By integral-transform with regard tothe space variables (z,u,r) in turn, their partial differential couldbe eliminated”. Writing formulas to represent the operation oftaking the inverse transform and the integral-transform with re-gard to z, these are defined byTr;u;z;t X1m1Zbm;zNbmTr;u;bm;t;9Tr;u;bm;t Zl0Zbm;z0 ? Tr;u;z0;tdz0;10where Tr;u;bm;t is the integral-transform of T(r,u,z,t) withregardtoz;Z(bm,z)isthecharacteristicfunction,Z(bm,z) =cosbm(l ? z); bmis the characteristic value, bmtanbml = H3, andH3h3k; N(bm) is the norm,1Nbm 2b2mH23lb2mH23H3.Submit Eq. (10) into Eqs. (1) and (8), the following equations isobtained:o2Tor21roTor1r2o2Tou2f3kcosl ? bm ? b2m? Tr;u;bm;t1aoTr;u;bm;tot;11a?koTor h1T ?f1t;r a; t P 0; 0 6u6u0;11bkoTor h2T ?f2t;r b; t P 0; 0 6u6u0;11c?k1roTou h5T ?f5t;u 0; t P 0; a 6 r 6 b;11dk1roTou h6T ?f6t;uu0; t P 0; a 6 r 6 b;11eTr;u;bm;t Zl0Zbm;z0 ? T0dz0;t 0;a 6 r 6 b; 0 6u6u0:11fIn the same way, the inverse transform and the integral-transformwith regard to u and r are defined byTr;u;bm;t X1n1Uvn;uNvneTr;vn;bm;t;12eTr;vn;bm;t Zu00u0?Uvn;u0 ? Tr;u0;bm;tdu0;13whereeTr;vn;bm;t is the integral-transform of Tr;u;bm;t with re-gard to u;U(vn,u) is the characteristic function,U(vn,u) = vn? cosvnu +H5? sinvnu; vnis the characteristic value, tanvnu0vnH5H6v2n?H5H6H5h5k;H6h6k; N(vn) is the norm,1Nvn2 v2nH25?u0H6v2nH26?H5hi?1.eTr;vn;bm;t X1i1Rvci;rNcieTvci;vn;bm;t;14eTvci;vn;bm;t ZbaRvci;r0 ?eTr0;vn;bm;tdr0;15whereeTvci;vn;bm;t is the integral-transform ofeTr;vn;bm;t withregard to r; Rv(ci,r) is the characteristic function, Rv(ci,r) = Sv?Jv(ci? r) ? Vv? Yv(ci? r), Jv(ci? r) and Yv(ci? r) are the Bessel functionsof the first and second kind with order v, whereSvci?Y0vci?bH2?Yvci?b;Uvci?J0vci?a?H1?Jvci?a;Vvci?J0vci?bH2?Jvci?b;Wvci?Y0vci?a?H1?Yvci?a;ciis the characteristic value which satisfies the equation Uv? Sv?Wv? Vv= 0; N(ci) is the norm,1Ncip22c2iU2vB2?U2v?B1?V2v, where B1 H21c2i1 ? v=cia2? and B2 H22c2i1 ? v=cib2?.Finally, according to the above integral-transform, Eqs. (1) and(8) can be simplified as follows:deTvdtab2mc2ieTv Aci;vn;bm;t;t 0;16aeTvci;vn;bm;t eTv0;t 0;16bwhere A(ci,vn,bm,t) = g1+ g2+ g3,934Z.-c. Zhu et al./Applied Thermal Engineering 29 (2009) 932937g1a?b ? Rvci;bk?e?f2a ? Rvci;ak?e?f1?;g2Zbavk?f5? r2? Rvci;rdr Zbav ? cosvnu0 H5? sinvnu0k?f6? r2? Rvci;rdr;g3Zbaf3k? cosl ? bm ? sinvnbmH5v1 ? cosvnbm? r? Rvci;rdr:The solutioneTvci;vn;bm;t can be gained by solving the Eq. (16). Bytaking the inverse transform with regard toeTvci;vn;bm;t accordingto Eqs. (9), (12) and (14), the analytic solution of brake shoes 3-Dtransient temperature field is obtainedTr;u;z;t X1m1X1n1X1i1Zbm;zNbmUvn;uNvnRvci;rNcie?ab2mc2it?eTv0Zt0e?ab2mt0Aci;vn;bm;tdt02435:173. Simulation and experimentFig. 4 shows the half section view of brake shoe sample. Line cand d are the center line and bottom line of the cross section,respectively. The sample dimension is: a = 137.5 mm, b = 162.5 mm,u0= 1/6 rad, l = 6 mm. The material of brake shoe and brake discare asbestos-free and 16Mn, respectively. Their parameters andthe condition of emergency braking are shown in Table 1.Suppose that the friction coefficient and the specific pressureare constant during emergency braking process. Based on theabove analytic model, simulation of brake shoes 3-D temperaturefield is carried out with t0= 7.23 s. The change rules of temperaturefield and internal temperature gradient are analyzed. Whatsshown in Figs. 59 are partial simulation results.What is shown in Fig. 5 is brake shoes 3-D temperature fieldwhen time is 7.23 s. It is seen from Fig. 5 that the highest temper-ature of the brake shoe is 396.534 K after braking, and its lowesttemperature is 293 K. And the heat energy is mainly concentratedFig. 4. Half section view of brake shoes sample.Table 1Basic parameters of brake pair and the emergency braking conditionq(kg m?3)c(J kg?1K?1)k(W m?1K?1)T0(K)v0(m s?1)p(MPa)lBrake shoe220625300.295293101.380.4Brake disc786647353.212.51.58Fig. 5. 3-D temperature field of brake shoe (t = 7.23 s).Fig. 6. The change of temperature on friction surface with time t.Fig. 7. The change of temperature on line d with time t.Z.-c. Zhu et al./Applied Thermal Engineering 29 (2009) 932937935on the layer of friction surface (named thermal effect layer), whichindicates the thermal diffusibility of the brake shoe is poor. In or-der to mater the temperature change rules of friction surface dur-ing emergency braking process, the variation of friction surfacestemperature with time t is simulated. What is shown in Fig. 6 re-veals that the temperature of friction surface increases firstly, thendecreases. This is because that the speed of brake disc is high in thebeginning and this results in large heat-flow while the coefficientof convective heat transfer is low on the boundary at the moment,so the temperature increases; at the late stage of brake the heat-flow decreases with the speed while the coefficient of convectiveheat transfer is high due to large difference in temperature onthe boundary, which leads to decreasing in temperature. Figs. 6and 7 reflect the temperature change rules in the radial dimension:the temperature at the outside of brake shoe is higher than that in-side, and the outside temperature changes more greatly.Fig. 8 demonstrates the change rules of the temperature gradi-ent along the direction z. The highest temperature gradient of thefriction layer is up to 3.739 ? 105K/m and decreases sharply alongthe direction z. The lowest value is only 4.597 ? 10?11K/m. In thebeginning the temperature gradient of thermal effect layer is thehighest while the temperature is close to the surrounding temper-ature. As the brake goes on, the temperature gradient decreasesgradually until the end. Fig. 9 shows the change of temperatureat different depth on the line c with time t. The temperature de-creases sharply with the increasing z, and the boundary conditionhas litter influence on the inner temperature. The temperature in-creases all the time when z P 0.0006 m. Once the z is up to0.002 m, the difference in temperature during brake is less than3 K. It indicates that the heat energy focuses on the thermal effectlayer, and its thickness is about 0.002 m.In order to prove the analytic model, experiments were carriedout on the friction tester in Fig. 10. The experimental principle is asfollows: when the brake begins, two brake shoes are pushed tobrake the disc with certain pressure p and the temperature of pointe on the friction surface is measured by thermocouple. Because thespecimen thickness is too thin and the structure of the friction tes-ter is limited, it is difficult to fix the thermocouple in the brakeshoe. Therefore, the thermocouple is fixed directly on the brakedisc which is closed to point e shown in Fig. 10. Fig. 11 showsthe temperatures change rules at point e under two situations ofemergency braking.From Fig. 11, it is observed that the temperature at point e in-creases at first, then decreases; the highest temperature by simula-tion is lower than and also lags behind the experimental data. InFig. 11a, the simulation temperature reaches the maximum427.14 K at 3.6 s while the experimental data comes up to themaximum 435.65 K at 3.8 s. In Fig. 11b, the simulation resultreaches the maximum 469.55 K at 4.5 s while the experimentaldata comes up to 479.68 K at 5 s. It is seen from Fig. 11, the temper-ature measured by experiment is lower than simulation results atfirst, then it inverses. This is because the thermocouple itself ab-sorbs heat energy from the brake shoe in the beginning, then re-leases to the brake shoe when the temperature decreases.Comparison between the experimental data and the simulation re-sults indicates that the simulation shows good agreement with theexperiment, and the errors of their highest temperature are 1.99%Fig. 8. The change of temperature gradient on line c with time t.Fig. 9. The change of temperature at different depth on the line c with time t.Fig. 10. Schematic of friction tester.Fig. 11a. Temperatures change rules at point e with time t (p = 1.38 MPa, v0= 1-0 m/s).936Z.-c. Zhu et al./Applied Thermal Engineering 29 (2009) 932937and 2.16%, respectively. It indicates that the analytic solution of 3-D transient temperature field is correct.4. Conclusion(1) The theoretical model of 3-D transient temperature field wasestablished according to the theory of heat conduction andthe emergency braking condition of mining hoist. The inte-gral-transform method was applied to solve the theoreticalmodel, and the analytic solution of temperature field wasdeduced. It indicates that integral-transform method iseffective to solve the problem of 3-D transient temperaturefield with regard to cylindrical coordinates.(2) Based on the analytic solution of the theoretical model, thenumerical analysis was adopted to simulate the change rulesof temperature distribution under the emergency brakingcondition. Simulation results showed: the temperature offriction surface increased firstly and then decreased; in thebeginning the temperature gradient of thermal effect layerwas the highest, the temperature increased swiftly; as thebrakingprocessgoingon,thetemperaturegradientdecreased while the temperature increased; the boundarycondition had litter influence on the internal temperaturerise; the heat energy was concentrated on the thermal effectlayer and its thickness is about 2 mm.(3) The experimental data has good agreement with the simula-tion results, and the errors of their highest temperature areabout 2%, which prove the correctness of the integral-trans-form method solving the theoretical model of 3-D transienttemperature field. The analytical model can reflect thechange rules of brake shoes 3-D transient temperature fieldduring emergency braking.AcknowledgementsThis project is supported by the Key Project of Chinese Ministryof Education (Grant No. 107054) and Program for New CenturyExcellent Talents in University (Grant No. NCET-04-0488).References1 Y. Yang, J.M. Zhou, Numer