蜂蜜離心機設計
蜂蜜離心機設計,蜂蜜離心機設計,蜂蜜,離心機,設計
目錄
緒論 2
1. 選題目的 2
2. 國內離心分離研究發(fā)展 2
3. 主要差距 3
4. 國外離心分離技術的發(fā)展 3
5. 發(fā)展趨勢 4
第一章 離心機的概述 6
1.1 離心機 6
1.2 離心機原理 7
1.3 離心機的分類 7
1.3.1、按分離因素Fr值分 7
1.3.2、按操作方式分 8
1.3.3、按卸渣方式分 8
1.3.4、按工藝用途 9
1.3.5、按安裝的方式分 9
1.3.6、按國家標準與市場使用份額分 9
第二章 蜂蜜離心機設計步驟 10
2.1 主要參數 10
2.2 蜂蜜離心機總體方案: 10
2.2.1 設已知條件 10
2.2.2 確定各軸轉速 11
2.2.3 功率計算 11
2.2.4 計算各軸的輸入轉矩 11
2.3 輸出部分設計 13
第三章 離心機各部件設計 14
3.1 驅動部分機構設計: 14
3.2 機架部分結構設計: 14
3.3 軸支撐座結構設計: 15
3.4 旋轉支架的設計: 15
3.5 腳座部分結構設計: 16
3 .6 傳動部分結構設計: 16
第四章 全文總結 19
參考文獻 20
致謝 21
緒論
1. 選題目的
養(yǎng)蜂即蜜蜂養(yǎng)殖是人工飼養(yǎng)蜂蜜而取其產品包括蜂蜜、蜂王漿、蜂膠、花粉、蜂蠟等產品的事業(yè),包括在廣義的畜產內,所以廣義地說蜜蜂也是家畜。蜂蜜養(yǎng)殖的歷史有數千年之久,蜂蜜的利用是從漁獵時代開始的。然而蜂蜜是昆蟲蜂蜜從開花植物的花中采得的花蜜在蜂巢中釀制的蜜。蜂蜜從植物的花中采取含水量約為80%的花蜜或分泌物,存入自己第二個胃中,在體內轉化酶的作用下經過30分鐘的發(fā)酵,回到蜂巢中吐出,蜂巢內溫度經常保持在35℃左右,經過一段時間,水份蒸發(fā),成為水分含量少于20%的蜂蜜,存貯到巢洞中,用蜂蠟密封。這個時候人類便撥開蜂蠟,收獲蜜蜂的勞動果實蜂蜜,可是怎樣收取小小蜂蜜留下的點點產物呢,人工取用的話,很麻煩,提取的不徹底,而且弄臟手啊,衣服什么的,效率也極低,于是我們便需要發(fā)明一種取蜜機器——蜂蜜離心機,這樣可以更有效率的并徹底地將蜂蜜利用離心力甩出來。
2. 國內離心分離研究發(fā)展
我國離心機行業(yè)尚屬正在發(fā)展中,總體水平不高。隨著社會進步,人們對環(huán)保.能源以及裝備對品質的影響有了新的認識。同時國外技術交流和合作以及成套項目的引進、消化與吸收,促進了我國離心分離技術的迅速發(fā)展。
1)已基本形成了一種科研、設計和制造的體。
2)成立了分離領域的學術組織。
3)在基礎理論與應用方面進行了研究。
4)目前已能生產三足、上懸、活塞、螺旋、離心力卸料、震動、進動卸料、刮刀及虹刮刀、翻袋及旁濾等離心機;分離機則有蝶式、室式及管式。上述產品不僅遍及全國且遠銷國外,且技術特性有所提高。
5)為滿足特殊工藝要求(防污染、密閉、防爆燈),一些新的離心機亦先后問世。內旋轉子過濾離心機的研制,立式密閉螺旋機及復試機等已投產。
6)自控技術與CAD技術的應用。
7)各種相關標準的制定。
8)同國外著名離心機廠商的技術合作。
3. 主要差距
盡管我國的離心分離設備有了很大的進展,但從整體而言,與世界先進國家相比,差距甚大,主要表現在:
1)規(guī)模、品種少,系列化程度差。特別缺少集幾種結構形式,集幾種推動力于一體的復合式離心機。
2) 技術參數低。國外離心分離機械產品的參數普遍高于我國,并繼續(xù)向高參數、大容量方向發(fā)展,以臥螺離心機為例,最近研制的機型為國內最大的,其轉鼓直徑亦僅720mm,長徑比最大為L/d-4,分離因數亦較低,而國外轉鼓最大直徑已達2.1m,長徑比L/d-6,處理能力大雨200m3/h,可用于二相或三相分離,還發(fā)展了雙向擠壓型、沉降、過濾復合機型。目前,較先進的機型都采用計算機控制,會隨著物料特性和參數的變化自動調節(jié)其相應的工況。
3) 產品進展緩慢。而國外,由于采用模塊化的組合結構,特別是采用了大規(guī)模定制設計的心手段,故能滿足用戶的個性化需求,并加快了產品的更新換代速度,甚至還儲備所謂“冷凍產品”,以隨時適應市場競爭的需求
4) 其他方面。在產品的可靠性、穩(wěn)定性、自控技術、加工工藝、新材料的使用、配套產品的品質,以及理論研究等方面,均存在不少的差距。
4. 國外離心分離技術的發(fā)展
受新技術推動及相關產業(yè)發(fā)展的影響,國外離心分離技術的進展主要體現在以下幾個方面:
1) 加強理論研究,選擇最佳設計方案
2) 瑞典Alfa-laval公司,在碟片流道研究中發(fā)現,碟片間隙橫斷面上的速度分布取決于一個無量綱數“λ”,而工業(yè)離心機的“λ”通常在5~28之間。隨著“λ”值的增加,碟片的轉速增加,薄層減少,可提高雷諾數并緩和渦流。通過對碟片間隔件和分布孔的巧妙設計,進料量可增加20%。此外,還對相分離技術進行了研究。
近年來,研究人員為選擇最佳方案,采用流場分離法、有限元模擬法、大梯度密度梯級法、反模態(tài)分析法等,對離心機的工作性能和關鍵零件進行研究,為設計優(yōu)良性能的離心機提供了理論依據。并對待內洗滌的臥螺離心機中堰池深度以及臥螺離心機技術參數之間的關系等進行了最佳化研究。
2) 技術參數的提高和新機型的問世
為提高產品的純度,及滿足能源和環(huán)保的要求,高參數已成為國外的發(fā)展特點。由于生物工程需要分離極細的顆粒,如細菌、霉及胰島素等,故最新蝶式機已可處理0.1um微粒,且分離因數可達5000.如德國Westfalia公司的CSA160機型和瑞典Alfa-laval公司的BTAX510機型均屬此例,隨著工藝要求的提高,新機型不斷問世。美國Dorr-Oliver公司的BH-46型蝶式機,轉鼓內徑已達1.2m,轉鼓重量為4.5t,用2個功率為220kW的電機驅動,最大生產能力為450m3/h,當量沉降面積已達250,000m2,為蝶式機之最。
瑞典Alfa-laval公司用于生物技術的BTUX510型蝶式機,具有自動調節(jié)的渦流噴嘴。利用噴嘴進料黏度和濃度的關系,可提供供恒定的固相濃度,與進料速度和固體含量的變化無關。
而具有1000分離因數的臥螺離心機,可從某種長度上彌補管式分離機的不足。
BTNX3560-A機型的特點是先進的旋轉動態(tài)設計:主軸承改為彈性安裝,可延長壽命,降低機器噪音和震動。德國Krauss-Maffei公司最新研制的SZ型活塞,尺寸雖小,卻更能有效進行固相分離。還有德國Flottweg公司用于處理難分離物料的雙錐體臥螺離心機等。
3)新材料的應用
為了提高分離機械的性能、強度、剛度、耐磨性和抗腐蝕性,一些新型材料不斷涌現,如,工程塑料,硬質合金以及性能優(yōu)良的耐磨耐蝕不銹鋼材料。
法國曾研制一種用硬質陶瓷制造的轉子,英國也曾研制由合成樹脂構成的連續(xù)纖維復合材料轉子。
但是在蝶式機中,由于需要高強度和一定的耐腐性能,雙相組織的不銹鋼廣泛采用。最近,俄國研制成功一種雙相鋼04X25H5M2(即10Cr25Ni5Mo2),有足夠的強度和塑形。德國的Wischnouskii等研制的分離機轉鼓新材料,具有強度高、塑形和耐腐蝕性好的特點。為彌補耐蝕和強度之間的矛盾,一些先進的制造商普遍采用了轉鼓的自強技術。
5. 發(fā)展趨勢
1)強化動態(tài)監(jiān)測和自動化。隨著自動控制和傳感技術的發(fā)展,許多先進的自控手段被引入,并對離心機運行中的各項參數,如溫度、流量、速度、振幅和噪音等進行全方位的監(jiān)測,并通過傳感器將收集信息輸入計算機,經系統(tǒng)處理后,可及時了解各種參數的變化以及采取相應的措施。由此出現了無人操作的蝶式分離機。
2)各種組合機和專用機的開發(fā)。Alfa-laval公司在蝶式分離機上組合螺旋輸送器形成復合蝶式機;Krauss-Msffei公司的柱錐復合活塞機、虹吸刮刀離心機;Sharpies公司的沉降過濾復合螺旋離心機等。此外為提高離心機的分離性能和尋找最佳操作工況,Westfalia公司的蝶式分離機品種之多已是世界之最。設計方面的進展:隨著計算機技術的發(fā)展,CAD技術與模塊化設計已普遍使用。目前,全球市場競爭的愈加激烈,制造業(yè)面臨著提高客戶價值的巨大挑戰(zhàn)。20世紀90年代以來,“大規(guī)模定制”在制造業(yè)逐步興起。即“以近似于大批量生產的效率生產商品和提供服務以滿足客戶的個性化需要”。由于設計在產品生命周期中的重要性,面向大規(guī)模定制的設計(DFMC)已成為設計方面的新動向。
第一章 離心機的概述
1.1 離心機
離心機是利用離心力,分離液體與固體顆粒或液體與液體的混合物中各組分的機械。離心機主要用于將懸浮液中的固體顆粒與液體分開;或將乳濁液中兩種密度不同,又互不相溶的液體分開(例如從牛奶中分離出奶油);它也可用于排除濕固體中的液體,例如用洗衣機甩干濕衣服;特殊的超速管式分離機還可分離不同密度的氣體混合物;利用不同密度或粒度的固體顆粒在液體中沉降速度不同的特點,有的沉降離心機還可對固體顆粒按密度或粒度進行分級。
離心機大量應用于化工、石油、食品、制藥、選礦、煤炭、水處理和船舶等部門。
中國古代,人們用繩索的一端系住陶罐,手握繩索的另一端,旋轉甩動陶罐,產生離心力擠壓出陶罐中蜂蜜,這就是離心分離原理的早期應用。
工業(yè)離心機誕生于歐洲,比如19世紀中葉,先后出現紡織品脫水用的三足式離心機,和制糖廠分離結晶砂糖用的上懸式離心機。這些最早的離心機都是間歇操作和人工排渣的。?由于卸渣機構的改進,20世紀30年代出現了連續(xù)操作的離心機,間歇操作離心機也因實現了自動控制而得到發(fā)展。?
工業(yè)用離心機按結構和分離要求,可分為過濾離心機、沉降離心機和分離機三類。
離心機有一個繞本身軸線高速旋轉的圓筒,稱為轉鼓,通常由電動機驅動。懸浮液(或乳濁液)加入轉鼓后,被迅速帶動與轉鼓同速旋轉,在離心力作用下各組分分離,并分別排出。通常,轉鼓轉速越高,分離效果也越好。??
離心分離機的作用原理有離心過濾和離心沉降兩種。離心過濾是使懸浮液在離心力場下產生的離心壓力,作用在過濾介質上,使液體通過過濾介質成為濾液,而固體顆粒被截留在過濾介質表面,從而實現液-固分離;離心沉降是利用懸浮液(或乳濁液)密度不同的各組分在離心力場中迅速沉降分層的原理,實現液-固(或液-液)分離。?
還有一類實驗分析用的分離機,可進行液體澄清和固體顆粒富集,或液-液分離,這類分離機有常壓、真空、冷凍條件下操作的不同結構型式。?
衡量離心分離機分離性能的重要指標是分離因數。它表示被分離物料在轉鼓內所受的離心力與其重力的比值,分離因數越大,通常分離也越迅速,分離效果越好。工業(yè)用離心分離機的分離因數一般為100~20000,超速管式分離機的分離因數可高達62000,分析用超速分離機的分離因數最高達610000。決定離心分離機處理能力的另一因素是轉鼓的工作面積,工作面積大處理能力也大。
?選擇離心機須根據懸浮液(或乳濁液)中固體顆粒的大小和濃度、固體與液體(或兩種液體)的密度差、液體粘度、濾渣(或沉渣)的特性,以及分離的要求等進行綜合分析,滿足對濾渣(沉渣)含濕量和濾液(分離液)澄清度的要求,初步選擇采用哪一類離心分離機。然后按處理量和對操作的自動化要求,確定離心機的類型和規(guī)格,最后經實際試驗驗證。?
?通常,對于含有粒度大于0.01毫米顆粒的懸浮液,可選用過濾離心機;對于懸浮液中顆粒細小或可壓縮變形的,則宜選用沉降離心機;對于懸浮液含固體量低、顆粒微小和對液體澄清度要求高時,應選用分離機。
1.2 離心機原理
當含有細小顆粒的懸浮液靜置不動時,由于重力場的作用使得懸浮的顆粒逐漸下沉。粒子越重,下沉越快,反之密度比液體小的粒子就會上浮。微粒在重力場下移動的速度與微粒的大小、形態(tài)和密度有關,并且又與重力場的強度及液體的粘度有關。象紅血球大小的顆粒,直徑為數微米,就可以在通常重力作用下觀察到它們的沉降過程。此外,物質在介質中沉降時還伴隨有擴散現象。擴散是無條件的絕對的。擴散與物質的質量成反比,顆粒越小擴散越嚴重。而沉降是相對的,有條件的,要受到外力才能運動。沉降與物體重量成正比,顆粒越大沉降越快。對小于幾微米的微粒如病毒或蛋白質等,它們在溶液中成膠體或半膠體狀態(tài),僅僅利用重力是不可能觀察到沉降過程的。因為顆粒越小沉降越慢,而擴散現象則越嚴重。所以需要利用離心機產生強大的離心力,才能迫使這些微粒克服擴散產生沉降運動。離心就是利用離心機轉子高速旋轉產生的強大的離心力,加快液體中顆粒的沉降速度,把樣品中不同沉降系數和浮力密度的物質分離開。
1.3 離心機的分類
1.3.1、按分離因素Fr值分
可將離心機分為以下幾種型式:
1、常速離心機
Fr≤3500(一般為600~1200),這種離心機的轉速較低,直徑較大。
2、高速離心機
Fr=3500~50000,這種離心機的轉速較高,一般轉鼓直徑較小,而長度較長。
3、超高速離心機
Fr>50000,由于轉速很高(50000r/min以上),所以轉鼓做成細長管式。分離因素Fr是指物料在離心力場中所受的離心力,與物料在重力場中所受到的重力之比值。
1.3.2、按操作方式分
可將離心機分為以下型式:
1、間隙式離心機
其加料、分離、洗滌和卸渣等過程都是間隙操作,并采用人工、重力或機械方法卸渣,如三足式和上懸式離心機。
2、連續(xù)式離心機
其進料、分離、洗滌和卸渣等過程,有間隙自動進行和連續(xù)自動進行兩種。
1.3.3、按卸渣方式分
可將離心機分為一下型式:
1、刮刀卸料離心機
工序間接,操作自動。
2、活塞推料離心機
工序半連續(xù),操作自動。
3、螺旋卸料離心機
工序連續(xù),操作自動。
4、離心力卸料離心機
工序連續(xù),操作自動。
5、振動卸料離心機
工序連續(xù),操作自動。
6、顛動卸料離心機
工序連續(xù),操作自動。
1.3.4、按工藝用途
可將離心機分為:過濾式離心機、沉降式離心機。
1.3.5、按安裝的方式分
還可將離心機分為立式、臥式、傾斜式、上懸式和三足式等。
1.3.6、按國家標準與市場使用份額分
離心機可以分為以下四種
1、三足式離心機
2、臥式螺旋離心機
3、碟片式分離機
4、管式分離機
第二章 蜂蜜離心機設計步驟
2.1主要參數
試設計養(yǎng)蜂農民用于從蜂窩中取蜜的離心機。蜂巢建筑在一個240mm×420mm×25mm的木質的框架上,兩邊都有蜂巢,蜂巢口向外。整個蜂巢板的厚度為50mm,木質邊框的內外邊距離差為20mm。取蜜的方法是將蜂巢置于一個回轉框架上,;利用離心力將蜂巢內的蜜甩出,然后甩另一邊。一次裝上5快蜂巢板。方式不限。
主要參數
蜂蜜板240mm×420mm×25mm
蜂巢板的厚度為50mm木質邊框的內外邊距離差為20mm
2.2 蜂蜜離心機總體方案:
此方案本著操作方便有效,成本低廉,零部件制作工藝簡單的原則制定的,其總體由以下幾個部分組成.
A 動力部分:選擇純手動方式,由一個手搖把手人工控制離心機轉速.
B 傳動部分:應為要改變旋轉運動的方向,并傳動可靠有力,傳動比較大 ,故選用常用的直齒錐齒輪傳動方式.
C 機架部分:此部分結構對整個機器起著支撐作用,是機器的整體框架,其中包括了旋轉軸的固定,原料定位裝置等等.
D 出料部分:由一個大容量桶子容納整個機器結構部分,蜂蜜由離心桶桶底小孔流下,累積于大桶桶底儲存,最后由人工控制水龍頭的開關來提取蜂蜜.
2.3動力部分
2.3.1 設已知條件
?人工用力為f=60N
?人搖手柄的轉速為n1=60r/min 蜂蜜板每塊m=2kg
?傳動比為i=2.4
2.3.2 確定各軸轉速
a 確定輸入軸計算轉速
由已經條件可知輸入軸的計算轉速就是人工搖動手柄的轉速,我們設人工搖動手柄的轉速為
n1=60r/min
b 確定輸出軸的轉速
輸出軸是經過一對直齒錐齒輪傳動輸出的,且已定轉動比i=2.4所以得
n2=i×n1=60×2.4=144r/min
2.3.3 功率計算
手搖柄的輸入功率
p1=FV=F×2×3.14×r/T=60×2×3.14×245/1×1000=92w
輸出功率
P2=p1×η=92×0.96=88w
2.3.4 計算各軸的輸入轉矩
T1=9550×92/60×1000=14.64(N.m)
T2=9550×88/144×1000=5.8(N.m)
(a)模數的確定:
其中: μ—傳動比; μ=2.4;
Nd—輸入功率; Nd=92W;
Ψm—齒寬系數;
[σ]—齒輪傳動許允應力;
nj—齒輪計算轉速。
[σ] =KNσlim/S , 取 σlim=600MPa,安全系數S=1
由應力循環(huán)次數選取KN=0.9
[σ]=0.9×600/1=540MPa
帶入數值求得模數 m1=3
計算基本設計參數為
d1=mz1=3×60=180mm
d2=mz2=25×3=75mm
μ =Z2/Z1=d2/d1=cotδ1=tanδ2=2.4
R為錐距,算得R=234mm
dm1/d1=dm2/d2=1-0.5b/R =0.83 (dm1 dm2 平均分度圓直徑)
令Ψm=b/R,稱為錐齒輪傳動的齒寬系數,通常取Ψm=0.25~0.35,最常用的值為Ψm=1/3
于是
dm1=d1(1-0.5Ψm)=150mm
dm2=d2(1-0.5Ψm)=62.5mm
由圖10-33可找出當量直齒圓柱圓錐齒輪的分度圓半徑rv與平均分度圓直徑dm的關系式為
Rv1=dm1/2cosδ1=97.5mm
Rv2=dm2/2cosδ2=97.5mm
現以mm表示當量直齒圓柱齒輪的模數,亦即錐齒輪平均分度圓上輪齒的模數(簡稱平均模數),則當量齒數zv為
zv1= dv1/mm=z1/cosδ1=78
zv2= dv2/mm=z2/cosδ2=78
當量齒輪的齒數比
uv=zv2/zv1=u2=5.76
顯然,為使錐齒輪不致發(fā)生根切,應使當量齒數不小于直齒圓柱齒輪的根切齒數。另外,由式(d)極易得出平均模數mm和大端模數m的關系為
mm=m(1-0.5Ψm)
2.3 輸出部分設計
離心機是利用離心力,分離液體與固體顆?;蛞后w與液體的混合物中各組分的機械。離心機主要用于將固體顆粒與液體分開;蜂蜜離心機即利用離心力將蜂蜜與蜜蜂板分離。
離心力場特點及分離因數
離心力場 FC=mω2R=2×5×1442×0.25=51.84KN
重力場 G=mg=10×10=100
分離因數 Fr=FC/G=ω2R/g=518.4
第三章 離心機各部件設計
3.1 驅動部分機構設計:
本機器采用手動方式操作,靠人搖動啟動把手來使蜂蜜板旋轉,人可以根據蜂蜜板上蜂蜜量的多少,粘度的高低,自行調整旋轉速度(離心力的大小)簡捷有效,節(jié)能環(huán)保.結構如圖3-1所示:
圖3-1
3.2機架部分結構設計:
A 原料定位裝置:依照課題要求;一次裝5塊蜂巢板,由蜂蜜板尺寸大小240mm×420mm×25mm可設計一個五工位立式旋轉盤。蜂蜜板的定位采用類似于雙V型塊加水平面定位方式,五個T型塊統(tǒng)一均布固定在初級圓桶圓周上,在旋轉的過程中能保持卡緊不動,裝料取料采用抽插方式進行,最重要的是定位裝置結構簡單,制造成本低,制作周期短。結構如下圖所示:
圖3-2-1
B 主裝配板的設計:主裝配板為系統(tǒng)多部件裝配的基板,本身強度非常重要,形狀呈現為U狀板 ,支撐板上開有十六個安裝孔.上面主要安裝有輸入軸兩軸承座,輸出軸軸端蓋,和固定本身于儲料桶表面 ,結構如下所示:
圖3-2-2
3.3 軸支撐座結構設計:
旋轉軸的支撐座選擇固定在一塊大的支撐板上,板上有輸入軸的兩個軸承座和輸出軸的一端,大的支撐板兩端選擇固定在大的儲存蜂蜜的桶子圓周上,結構如下所示:
圖3-3
3.4旋轉支架的設計:
機器中間旋轉支架采用一個圓形套筒,圓周上均布五個小圓柱桿組成,套筒內圓開有多個鍵槽,方便與輸出軸連接以傳遞足夠大的扭矩,離心機旋轉無精度要求,小圓柱桿直接焊接在套筒之上,工藝簡單.小圓柱桿與原料定位元件連接采用螺母連接,在圓柱桿的另一端開一定大小的螺紋孔即可.結構圖如下:
圖3-4
3.5腳座部分結構設計:
基本原理:三點決定一個平面,所以在圓周上均布三個腳支座,腳支座與存儲料桶采用焊接的方式連接,結實可靠,三維結構圖如下:
圖3-5
3 .6傳動部分結構設計:
A 輸入軸設計:輸入軸由四段階梯軸組成,靠近把手端部有個小凸起,以便插入手搖把手里轉動機器,第一段軸用于軸左端軸承座安裝,軸承的軸向定位左邊靠C 環(huán)扣,C環(huán)扣為標準間,根據型號可直接從廠商購買到.右邊靠軸階梯定位,第二段軸為輸入軸最大直徑段,作用是給左右兩軸承座里的軸承提供軸向定位。很明顯,第三段軸是輸入軸右端軸承座的安裝段,軸承右端同時也采用C 環(huán)扣軸向定位,操作簡單,c 環(huán)扣槽加工方便。第四段軸用于安裝齒輪盤,用于與輸出軸上的齒輪嚙合,傳遞動力,齒輪盤的連接采用花鍵連接,連接可靠,傳遞扭矩大,由于齒輪盤帶法蘭盤,可在軸套圓周上開四個小的螺紋孔,安裝徑向定位零件,螺絲頂絲徑向加緊防止齒輪盤軸向竄動。注意:在軸上零件安裝的過程中,先不把軸承座固定到機架上去,先將其和輸入軸裝配起來然后一起裝入機架的支撐塊上去,否則無法裝配。
圖3-6-1
B 齒輪設計:齒輪設計最基本原則,最小齒數大于等于17,不然會出現過切現象。本機器使用的是與往常減速齒輪不同的增速齒輪,輸入軸上要求齒數多,輸出軸上齒數小,有一個明確的傳動比,假設傳動比為2.5,即手轉動一圈,蜂蜜板轉動三圈。
C輸出軸設計:與輸出軸相關聯的零件有 主支撐板(用于輸出軸定心)及軸端軸向定位板,嚙合齒輪盤(傳遞動力),與機架固連的旋轉支架(帶動蜂蜜板旋轉),機器最底下的軸固定板(用于軸向定位)和軸兩端的滾珠軸承(用于徑向定位)。設計首先考慮裝配的可行性與方便性,個零件的定位要求,輸出軸結構上設計成六段階梯軸,從安裝后的位置由上到下分別用于安裝:
a 端部滾動軸承:(靠自鎖螺母和周端定位,只定位內圈即可,無軸向負載)。
b 小齒輪盤:(平鍵徑向定位,考慮到齒輪主要是受徑向負載,在軸圓周上對稱開四個鍵槽增強負載容量,軸向采用C環(huán)扣和軸軸肩定位)。
c 中間旋轉支架:與軸的安裝主要靠套筒內部開鍵槽,同樣道理,應在軸圓周上對稱開四個鍵槽配合使用以帶動蜂蜜板負載,軸向運動的話一方面由于本身重力因素不會上下浮動,另外為保險起見可在套筒四周開螺紋孔,在螺紋孔里面旋入頂絲,防止套筒軸向移動。與套筒相連的小圓柱桿與定位裝置的連接采用自鎖螺母連接,在圓柱桿和蜂蜜板定位板上鉆合適的螺栓孔即可,裝配時,應先將支架裝于輸出軸上然后再用螺栓固定在定位板上。
d 光桿:此軸段僅靠兩端軸肩對相應的旋轉支架其軸向定位作用。
e 底部旋轉支架:底部旋轉支架與中間旋轉支架類似,只是有兩個方面需要加強:1旋轉支架的支架數量要增加至10條,成倍增加并統(tǒng)一焊接在圓形環(huán)上面用于承受機器多個零部件的重量(蜂蜜原料板,定位T型板,初級圓桶等)2軸向定位需要加強,因為其下端是直徑較小的軸桿部分,由于重力原因往下掉,為此,特定制一定長度的村套來頂住底部旋轉支架,村套的另一端靠滾動軸承壓住。
f 端部滾動軸承:此軸承靠以上所述的村套以及最底下的軸固定板頂住實現軸向定位。
g儲料部分機構設計:在初級圓桶外面再套裝一層料桶,當蜂蜜從原料板上甩出時,首先毫無疑問的是甩在初圓料筒上,積少成多,由于自身重力原因會往下,初級料筒桶底有許多個小通孔,用于進一步刷選蜂蜜(因為有可能非蜂蜜,蜂巢渣子被甩出),小通孔只允許一定大小的物質通過,當然蜂蜜是液體,能很順暢的流入儲料桶里面,儲料桶桶底安裝有便于出料的水龍頭儲料,當一次甩料完畢,可打開龍頭開關,提取全部蜂蜜。
圖3-6-2
第四章 全文總結
本設計方案中心意思明確,結構切實有效,且無大成本零組件,成本意識非常好,巧妙的應用了直齒圓錐齒輪機構傳動,和蜂蜜原料板定位機構,不過也還有諸多地方需要改善,
(比如:手動驅動人工勞動強度大,卸料龍頭開關應放置在儲料桶底部,手搖把手高度是否適宜人機操作,整個機器沒防塵罩,長期敞開在外容易受污染, 并且嚙合齒輪直接在蜂蜜儲料桶的上方,潤滑油,金屬摩擦介質容易掉入儲料桶里面,蜂蜜質量不能得到有效保證.機器運輸僅靠儲料桶上的環(huán)勾會有困難等等.) 好質量的產品是一代又一代人努力的結晶,相信通過以后不斷的學習,能造出更好的機器.
參考文獻
1、 刑邦圣主編.機械制圖.北京:中國礦業(yè)大學出版社2007
2、 紀名剛主編.機械設計.北京:高等教育出版社2003
3、 蘇建修主編.機械制造基礎.北京:機械工業(yè)出版社2007
4、 熊詩波主編.機械工程測試技術基礎.北京:機械工業(yè)出版社2006
5、 張建民主編.機電一體化系統(tǒng)設計.北京:高等教育出版社2006
6、 機械設計手冊編委會.機械設計手冊.第二卷.北京:機械工業(yè)出版社2004
7、 王紹俊主編.機械制造工藝手冊.哈爾濱工業(yè)大學出版社1984
8、 王永華主編.現代電器控制及PLC應用技術.北京航空航天大學出版社2008
9、 徐茂功主編.公差配合與技術測量.北京.機械工業(yè)出版社2008
10、宋寶玉主編.機械設計課程設計指導書.北京.高等教育出版社2009
11、孫啟財、金鼎五 主編. 離心機原理結構與設計計算.機械工業(yè)出版社1987
致謝
在這次畢業(yè)設計的完成過程中,得到朱中喜老師和同學的幫助與鼓勵,使我能夠順利地完成畢業(yè)設計,我在此對他們表示衷心的感謝。
首先,我誠摯地感謝朱中喜導師。導師學識淵博、治學嚴謹,平易近人,不辭辛苦的幫助我完成論文設計。在本次畢業(yè)設計的過程中,老師給予了我許許多多的關懷與指導。本論文從選題到老師指導我思路,不斷的修改到最后成文,無不傾注著老師的心血。在此論文完成之際,我再一次向他致以最誠摯的謝意。同時,我要感謝我們學院多年來給我們授課的各位老師,正是由于他們的傳道、授業(yè)、解惑,讓我學到了許多知識,充實了自己知識面,并從他們身上學到了如何求知治學、如何為人處事,立足社會。我也要感謝我的母校,是他提供了良好的學習氛圍和優(yōu)質生活環(huán)境,讓我的大學生活豐富多姿,讓我在以后的日子里深深懷念,有著一份感恩的情懷,回報社會。非常感謝10級機械班的同學們,我們一起學習、一起討論,共同進步,平日里大家關于畢業(yè)設計的討論給了我很多啟發(fā),我再次深表謝意;最后,向我的親愛的家人表示深深的謝意,他們給予我的愛、理解、關心和支持是我不斷前進的動力。
愿所有的老師、同學們、朋友們事業(yè)有成,幸福美滿!
22
1 Optimized Kinematics of Mechanical Presses with Noncircular Gears E. Dodge ( l ) , M. Hinderance Received on January 8, 1997 Abstract: The quality of parts manufactured using metal forming operations depends to a large degree on the kinematics of the press ram. Non-circular Geary to obtain those stroke-time behaviorisms we aim at as an optimum for the various metal forming ope with a rotational-angle- dependent speed ratio in the press drive mechanism offer a new WA rations in terms of manufacturing. The paper explains the principle using a prototype press which was built by the Institute for Metal Forming and Metal Forming Machine Tools at Hanover University. It will present the kinematics as well as the forces and torques that occur in the prototype. Furthermore, the paper demonstrates using one example of deep drawing and one of forging that the press drive mechanism with non-circular gears may be used advantageously for virtually all metal forming operations. Keywords: Press, Gear, Kinematics 1 introductive Increasing demands on quality in all areas of manufacturing engineering, in sheet metal forming as well as in forging, go hand in hand with the necessity to make production economical. Increasing market orientation requires that both technological and economic requirements be met. The improvement of quality, productivity and output by means of innovative solutions is one of the keys to maintaining and extending ones market position.In the production of parts by metal forming, we need to distinguish between the period required for the actual forming process and the times needed to handle the part. With some forming processes we have to add time for necessary additional work such as cooling or lubrication of the dies. This yields two methods of optimization, according to the two aspects of quality and output. In order to satisfy both aspects, the task is to design the kinematics taking into account the requirements of the process during forming; also to be considered is the time required for changing the part as well as for auxiliary operations in line with the priority of a short cycle time. 2 Pressing Machine Requirements One manufacturing cycle, which corresponds to one stroke of the press goes through three stages: loading,forming and removing the part. Instead of the loading and removal stages we often find feeding the sheet, especially in sheer cutting. For this, the press ram must have a minimum 2 height for a certain time. During the forming period the ram should have a particular velocity curve,which will be gone into below. The transitions between the periods should take place as quickly as possible to ensure short cycle time. The requirement of a short cycle time is for business reasons, to ensure low parts costs via high output. For this reason stroke numbers of about 24/min for the deep drawing of large automotive body sheets and 1200/min for automatic punching machines are standard practice.Increasing the number of strokes in order to reduce cycle times without design changes to the pressing machine results in increasing strain rates, however. This has a clear effect on the forming process, which makes it necessary to consider the parameters which determine the process and are effected by it. In deep drawing operations, the velocity of impact when striking the sheet should be as low as possible to avoid the impact. On the one hand, velocity during forming must be sufficient for lubrication. On the other hand, we have to consider the rise in the yield stress corresponding to an increase in the strain rate which creates greater forces and which may cause fractures at the transition from the punch radius to the side wall of the part. In forging, short pressure dwell time is desirable. As the pressure dwell time drops the die surface temperature goes down and as a result the thermal wear This is counteracted by the enhanced mechanical wear due to the greater forming force, but the increase due to the strain rate is compensated by lower yield stress because of the lower cooling of the part. The optimal short pressure dwell can nowadays be determined quantitatively using the finite element method 3. In addition to cost avoidance due to reduction in wear, short pressure dwell time is also an important technological requirement for the precision forging of near net shape parts, which has a promising future. The requirements of high part quality and high output will only be met by a machine technology which takes into account the demands of the metal forming process in equal measure to the goal of decreasing work production costs. Previous press designs have not simultaneously met these technological and economical requirements to a sufficient extent, or they are very costly to design and manufacture, such as presses with link drives 6. This makes it necessary to look for innovative solutions for the design of the press. Its design should be largely standardized and modularized in order to reduce costs 6. 3 Fig 1. Prototype press 3 Press Drive with Noncircular Gears 3.1 Principle The use of non-circular gears in the drive of mechanical crank presses offers a new way of meeting the technological and economic demands on the kinematics of the press ram. A pair of non-circular gears with a constant center distance is thus powered by the electric motor, or by the fly wheel, and drives the crank mechanism itself.The uniform drive speed is transmitted cyclically and non-uniformly to the eccentric shaft by the pair of noncircular gears. If the non-circular gear wheels are suitably designed, the non-uniform drive of the driven gear leads to the desired stroke- time behaviour of the ram. Investigations at the Institute for Metal Forming and Metal Forming Machine Tools (IFUM) of Hanover University have shown that in this simple manner all the relevant uninterrupted motions of the ram can be achieved for various forming processes 2. Apart from, the advantages of the new drive, which result from the kinematics and the shortened cycle time, the drive concept is distinguished by the following favorable Propertius. Because it is a mechanical press, high reliability and low maintenance may be expected. In companion to linkage presses the number of parts and bearings is clearly reduced. Above all, a basic press type can be varied without further design changes by installing different pairs of gears, designed according to the demands of the customer. Unlike link drives, bearing locations and installations do not change within one load class as a result of different kinematics. Thus the above mentioned requirement of popularization and standardization is taken into account Reductions in time and costs are possible for the design and press manufacture. 4 3.2 Prototype At the Institute for Metal Forming and Metal Forming Machine Tools (IFUM) a C-frame press has been remodeled and a pair of non-circular gears was installed. The previous back gears were replaced by a planetary gear set for this purpose. The work carried out shows that remodeling of existing presses for the new drive is possible. The state of the press at the end of the modelli is shown in figure 1. The press is designed for a nominal ram force of 1,000 N and 200 N of the die cushion. The center distance of the non-circular gears is 600 mm. The pair of non-circular gears has an average transmission ratio of 1.Each gear wheel has 59 gear teeth, straight-toothed,module 10 mm (fiacre 2). The face width is 150 mm. The gears have involute gear teeth. We assume a non-circular base curve for the design of the flank geometry. As a result the tooth geometry of a non-circular gear varies along the circumference. In spite of this, it can be derived from the well- known trapezium rack, however 4, 51. An algorithm for the computation, which takes the addendum and addendum into account exactly, has been developed. Fig. 2 View of the gears from the rear The press is designed for deep drawing of flat parts in single stroke operation mode. The maximum ram stroke is 180 mm, the number of strokes 32/min. At a stroke of 140 mm the ram velocity almost remains constant 71 mammals from 60 mm before lower dead center until lower dead center, see figure 3. Thus the velocity corresponds to the working velocity of hydraulic 5 presses. The velocity of incidence of a crank mechanism with the same number of strokes would be 220 mammals, in comparison. In order to keep the same average velocity with a crank press, the number of strokes would have to be halved. The short cycle time of the jodelled machine results from the fast upward motion. Because the press is run in single stroke operation mode, no particular requirements were made concerning handling time during design. The drive mechanism of the prototype with non-circular gears has in addition a favorable effect on the ram forces and the driving torques (failure 4). For a crank press the nominal force is normally available at 30 rotation of the crank shaft before the lower dead center. This corresponds to a section under nominal force of only 7 5% relative to the stroke. To reach the nominal force of 1,000 N, the drive has to supply a torque of 45 kam at the crank shaft. The prototype only requires 30 kam on account of the additional transmission of the non-circular gears. They are transmitted to a cyclic. non-uniform crank shaft torque, resulting in a nominal force range from 60 to the lower dead center. This corresponds to 27.5% of the stroke. We always find similar conditions if the pair of non-circular gears is stepped down in the operating range of the press. This will almost always be the case with sheet metal forming and stamping. It is thus possible to design some machine parts in a weaker form and to save costs this way. 4 Further Design Examples Using the examples of two stroke-time behaviorisms the design is illustrated in the following. A range of parts is assumed which are to be manufactured by the press. For this purpose the ram velocity requirements and the forming section of the assumed stroke need to be quantified.Furthermore, the time needed for the handling of the part needs to be determined, and also the minimum height which the ram has to assume during the handling. From this, we design the sequence of movements, and we describe it mathematically. At the IFUM, a software program developed by the institute is used. From this mathematical description of the stroke-time behaviour we can calculate the speed ratio of the non- circular gears needed.From this we obtain the outcurves of the gears l, 2, 7. In a first example the ram velocity in deep drawing is supposed to be constant during the sheet metal forming at least over 100 mm before the lower dead center and it is supposed to be about 400mm/s. Let the number of strokes be fixed at 30/min. Above 450mm section of stroke, let the time for the handling of the part be the same as for a comparable crank press with 25 strokes per minute. figure 5 shows the stroke-time behaviour , which is attained by the sketched pair of gears. The gear wheels are represented by their outcurves. The conventional cosine curve at 25/min is given for comparison. In addition to the reduction of cycle time by 20%, the ram 6 velocity of impact onto the sheet is also considerably reduced.110 mm before the lower dead center, the velocity of impact is 700 mammals when using the crank mechanism and only 410 mm/s when operated with non-circular gears. A second example shows a drive mechanism as is used for forging. In figure 6, stroke-time behaviour of a conventional forging crank press is compared with the kinematics of the press with non-circular gears illustrated in the picture.The cycle time of the crank press is 0.7 s, the number of strokes is 85/min and the nominal force is 20 MN.Its pressure dwell time is 86 ms with a forming section of 50 mm. The pressure dwell of the press depicted with non-circular gears decreases by 67% to 28 ms. It thus reaches the magnitude familiar from hammers. By increasing the number of strokes by a factor of 1.5, the cycle time decreases by 33% to 46 ms. In spite of this,the handling time remains the same compared to conventional crank press on account of the kinematics of the non-circular gears. In order to achieve these kinematics in this case, a conventional circular gear may be used as driving gear, arranged eccentrically. This reduces the costs for gear manufacture.These examples show that different kinematics can be achieved by using non-circular gears in press drives At the same time the potential of this drive with respect to the realization of the desired kinematics becomes clear as does the reduction of cycle times in production. By varying the examples it is also possible to increase the velocity after impact in deep drawing operations if :his sequence of motions is advantageous for the range of pans to be produced on the press, for reasons of lubrication, for example. 5 Conclusions The requirements of high productivity, reduced costs and the guarantee of high product quality to which all manufacturing companies are exposed, applies particularly to companies in the field of metal working. This situation leads us to reconsider the press drive mechanism in use up to now. The new drive for crank presses with non-circular gears described here allows us to optimize the kinematics of simple mechanical presses. This means that the cycle time is shortened to achieve high productivity and the kinematics follows the requirements of the forming process.The design effort needed is low. In contrast to presses with link drives, other kinematics can be achieved during the construction of the press by using other gears without changing bearing locations This allows the popularization and standardization of presses. 6 Acknowledge The authors would like to express their appreciation to the German Machine Tool Builders Association (VDW), located in Frankfurter, for its financial assistance and to some members for their active support. 7 7 References I Bernard, J., 1992, Optimization of Mechanism Timing Using Noncircular Gearing, Mechanical Design and Synthesis, Vol. 46, p. 565-570. 2 Dodge, E., Hinderance, M., 1996, Fertigungsgerechte Kinematographs Burch Undergraduate. VDI-Z Special Antimechanist 1/96, p. 74-77. 31 Dodge, E., Neagle, H., 1994, FE-Simulation of the Precision Forging Process of Bevel Gears, Annals of the CIRP, Vol. 43, p. 241-244. 4 Hinderance, M., Beta, V., 1996, Arundel Nonreader- an differentiates Elementariness, Construction, Vol. 48, p. 256-262. 5 Lit vin, F. L.: 1994, Gear geometry and applied theory,PTR Prentice Hall, Angleworm Cliffs (NJ, U.S.A.). 6 Nietzsche, D., 1992, Forerunning an Grof3raumstufenpressen;Lichtenstein fur die Auftragsvergabe. In:Bearbaiting 92, Int. Congress 27 -28.0ct.1992,VDI-Be richt, Vol. 946, p.231- 253. 7 Agawam. K., Yokemate, Y., Kosice, T., 1973, Studies on the Noncircular Planetary Gear Mechanisms with Nonuniform Motion, Bulletin of the JSME, Vol. 16. p. 1433-1442.
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