蘋果自動去皮機(jī)機(jī)械設(shè)計(jì)及仿真-水果去皮機(jī)-含去核切瓣功能【三維PROE】【含9張CAD圖紙和文檔資料】
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蘋果自動去皮機(jī)摘要 現(xiàn)階段我國蘋果的生產(chǎn)相對較好,但是在加工方面和西方國家相比就有相當(dāng)大的差距,在加工自動化方面更是落后。我國現(xiàn)在水果罐頭行業(yè)的發(fā)展相對比較樂觀,并且消費(fèi)者對水果罐頭的需求越來越大。水果罐頭需求大,當(dāng)然少不了蘋果罐頭,但我國現(xiàn)有的蘋果去皮設(shè)備中存在著不少問題,比如大型設(shè)備體積龐大,加工過程蘋果容易受污染,且不適合小型企業(yè)加工,另外有一部分設(shè)備需要靠人工將蘋果逐個插到固定針上,這樣很容易造成工人受傷事故。 本文設(shè)計(jì)的蘋果自動去皮機(jī)主要適用于小型蘋果罐頭加工企業(yè),不再需要人工將蘋果逐個插到固定針上,而是采用自動檢測系統(tǒng),通過氣缸將蘋果插到固定針上。有手靠近蘋果托盤是機(jī)器將不動作,這樣就減少了不必要的人員事故。本設(shè)計(jì)內(nèi)容主要包括蘋果自動去皮機(jī)總體設(shè)計(jì)、零件設(shè)計(jì)、零件尺寸設(shè)計(jì)及計(jì)算、標(biāo)準(zhǔn)件的選擇、重要部分強(qiáng)度校核等。并且還繪制了所需零件的所有CAD圖和PROE整裝圖。關(guān)鍵詞:水果罐頭,蘋果自動去皮機(jī),設(shè)計(jì)AbstractAt the present stage, apple production in China is relatively good. But there is still a considerable gap in the aspect of processing compared with western countries, especially more backward in terms of process automation. In our country the development of canned fruit industry is recently boom recently, at the same time the demand for canned fruit is growing with more and more consumers loving them. Canned fruit is in great demand, so it is canned apple. However, there are still many troubles in our existing apple peeling devices, such as the large volume of large scale equipment, apple being vulnerable to pollution in the process procedure, as well as unsuitable for small business processing. Another drawback is that some devices depend on artificial to insert apple one by one into fixing pins, which is easy to cause injury accidents.Apple peeling machine automatically in this artical is mainly targeted at small apple canned food processing enterprises. Instead of depending on artificial to insert apples one by one into fixing pins, the design brings to automatic test system and apples are inserted into fixing pins through the cylinder. We can find out one advantage is that the machine doesnt work if workers hands close to apple tray so as to reduce the unnecessary accidents and improve the security. The design mainly includes the overall design of automatic apple peeling machine, detailing design, the design and calculation of component size, the choice of the standard component, and the intensity check to important part. Whats more, all CDA chart and PROE diagram of all necessary components are drawed well.Keywords: canned fruit, apple automatic peeling machine, designII目錄摘要IAbstractII1 緒論11.1 本設(shè)計(jì)研究的目的與意義11.2 現(xiàn)階段國內(nèi)蘋果去皮方式11.3 蘋果自動去皮機(jī)的研究狀況及存在問題21.3.1 蘋果自動去皮機(jī)的研究狀況21.3.2 蘋果自動去皮機(jī)存在問題21.4 本設(shè)計(jì)研究內(nèi)容、方法及方向31.4.1 本設(shè)計(jì)研究內(nèi)容31.4.2 本設(shè)計(jì)采用的方法31.4.3 本設(shè)計(jì)未來發(fā)展方向32 蘋果自動去皮機(jī)總體方案設(shè)計(jì)42.1 蘋果自動去皮機(jī)方案確定42.2 蘋果自動去皮機(jī)工作原理及結(jié)構(gòu)組成42.2.1 蘋果自動去皮機(jī)工作原理42.2.2 蘋果自動去皮機(jī)結(jié)構(gòu)組成42.3 蘋果自動去皮機(jī)工作流程43 蘋果自動去皮機(jī)運(yùn)動機(jī)構(gòu)確定63.1 送料機(jī)構(gòu)的確定63.1.1 送料機(jī)構(gòu)方案設(shè)計(jì)63.1.2 送料機(jī)構(gòu)組件的確定63.2 工作臺轉(zhuǎn)動機(jī)構(gòu)的確定83.2.1 直齒圓錐齒輪的設(shè)計(jì)93.2.2 直齒圓柱齒輪的設(shè)計(jì)123.3 蘋果自動去皮機(jī)去皮及蘋果固定裝置193.3.1 刀架的設(shè)計(jì)193.3.2 刀片的設(shè)計(jì)193.3.2 蘋果固定裝置204電機(jī)的選擇214.1 確定電機(jī)類型214.2 步進(jìn)電機(jī)參數(shù)215 軸設(shè)計(jì)校核及軸承的選擇255.1 短軸的設(shè)計(jì)255.2 短軸的校核265.3 軸承的選擇296 蘋果自動去皮機(jī)仿真圖30結(jié)束語31參考文獻(xiàn)32致 謝331 緒論1.1 本設(shè)計(jì)研究的目的與意義 由于水果罐頭行業(yè)發(fā)展快速,且水果罐頭行業(yè)發(fā)展前景相對較樂觀,故不少小型水果罐頭企業(yè)如雨后春筍般出現(xiàn),企業(yè)要加工過罐頭首要問題就是加工設(shè)備,對生產(chǎn)蘋果罐頭的企業(yè)而言,蘋果自動去皮設(shè)備是重中之重,相對大型罐頭企業(yè)應(yīng)用的大型流水線型的生產(chǎn)方式,對小型加工企業(yè)并不適合,因此廣大加工廠家就迫切需要有一種小型蘋果自動去皮設(shè)備的出現(xiàn),且該設(shè)備生產(chǎn)效率要高,安全性高。本設(shè)計(jì)就是響應(yīng)廣大廠家的要求,設(shè)計(jì)出能夠很好適用于小型罐頭加工企業(yè)。該設(shè)計(jì)產(chǎn)品還具有以下優(yōu)點(diǎn):1)能自動檢測員工是否在手放于蘋果固定針下,能防止員工誤操作造成人工事故;2)該產(chǎn)品生產(chǎn)效率高,將蘋果果肉損耗減少到最低;3)該產(chǎn)品還能對其他水果去皮,如梨。該產(chǎn)品的出現(xiàn)對小型水果罐頭加工過廠家有著很大的幫助,對國內(nèi)整個水果罐頭行業(yè)的發(fā)展有個積極的推到作用。1.2 現(xiàn)階段國內(nèi)蘋果去皮方式1)手工去皮 手工去皮有以下優(yōu)點(diǎn):蘋果去皮徹底;果肉損耗小。但是手工去皮有不少缺點(diǎn),如去皮效率低、人工去皮成本高、人工勞動強(qiáng)度大。因此手工去皮的方法并不適合于企業(yè)加工。圖1-1 手搖去皮機(jī)2)半機(jī)械去皮 半機(jī)械去皮又可以分成兩類:一是手搖式去皮機(jī),二是機(jī)械帶動式去皮機(jī). (1)手搖式去皮機(jī)特點(diǎn): 由人工將水果(如蘋果、梨子等)插在不銹鋼制的三叉上,插時花蒂對準(zhǔn)中心線。搖動手柄使主齒輪傳動,并傳動三叉齒輪而使果實(shí)一起動。主動輪另一端的傘齒輪傳動去皮傘齒輪而使果實(shí)去皮。去皮結(jié)束后,手動將蘋果拔掉。該種方式去皮效率低,勞動強(qiáng)度大,不適合于生產(chǎn)使用,但適合于普通家庭及個人使用。 (2)機(jī)械帶動式去皮機(jī)特點(diǎn): 機(jī)械帶動式去皮機(jī)與手搖去皮最大的區(qū)別在于動力來源。加工方式與手搖式相同,這種方式相對于手搖式效率有所提高,但仍然不適合于生產(chǎn)使用。1.3 蘋果自動去皮機(jī)的研究狀況及存在問題1.3.1 蘋果自動去皮機(jī)的研究狀況 現(xiàn)階段國內(nèi)外蘋果自動去皮機(jī)送果方式分為單果和多果。 (1)單果自動去皮機(jī) 該種蘋果自動去皮機(jī)一次只能加工一個蘋果,首先人工在蘋果放置于蘋果托盤上,由托盤自動將蘋果置于插針上,再完成去皮的過程。該蘋果去皮機(jī)體積小,移動方便,而且加工效率較高。該種去皮方式是目前企業(yè)比較流行的去皮機(jī)種,特別是在小型企業(yè)中占一大部分份額。 (2)多果自動去皮機(jī) 多果自動去皮機(jī)工作原理是首先由人工將蘋果以蘋果梗垂直于水平面的方向放置于蘋果槽內(nèi),氣缸推桿伸出帶動升降板及其上的電動機(jī)、插針等一同向下移動,直到將蘋果插于插針,之后氣缸推桿回縮,將蘋果提升至月帔刀高度,電動機(jī)帶動插針、蘋果一起旋轉(zhuǎn),直到完成蘋果削皮工作,最后由人工將蘋果卸下。該類去皮機(jī)每臺機(jī)器至少一人、甚至兩人負(fù)責(zé)放果和卸果,該去皮機(jī)效率相對來說不高,在目前的罐頭行業(yè)中使用也較少。1.3.2 蘋果自動去皮機(jī)存在問題 不同種類的去皮機(jī)有不同的優(yōu)缺點(diǎn),同樣都存在或多或少的問題,如人搖去皮機(jī),操作人員的體力勞動強(qiáng)度大,效率很低;電機(jī)帶動的去皮機(jī)則減少了操作人員的體力勞動,但是在操作過程中在安裝蘋果時存在安全隱患,如果操作不當(dāng)則會導(dǎo)致人身事故;多果自動去皮機(jī)則在效率上比之前的都要高,但操作機(jī)器時需要多個人員,成本高。上述自動去皮機(jī)想要提高生產(chǎn)效率就要加強(qiáng)操作者的熟練程度,對新手來說是一較大的挑戰(zhàn)。1.4 本設(shè)計(jì)研究內(nèi)容、方法及方向1.4.1 本設(shè)計(jì)研究內(nèi)容 本設(shè)計(jì)研究的主要內(nèi)容是既安全又高效的蘋果自動去皮機(jī),其中主要部分是蘋果去皮。該機(jī)器還包括切瓣和去核功能。本論文的主要思路為蘋果自動去皮機(jī)整機(jī)分析設(shè)計(jì)、各部分機(jī)構(gòu)的設(shè)計(jì)及計(jì)算、主要部件的強(qiáng)度校核和干涉實(shí)驗(yàn)等。1.4.2 本設(shè)計(jì)采用的方法 經(jīng)過查閱目前蘋果自動去皮機(jī)的相關(guān)資料,互聯(lián)網(wǎng)查看蘋果去皮機(jī)工作視頻,綜合比較各種蘋果去皮機(jī)的優(yōu)缺點(diǎn),廠家對產(chǎn)品的要求,類比之后設(shè)計(jì)了該蘋果自動去皮機(jī)。1.4.3 本設(shè)計(jì)未來發(fā)展方向 因本設(shè)計(jì)集合了目前不同種類蘋果自動去皮機(jī)的優(yōu)點(diǎn),但仍然會有局限性,如不適合大型企業(yè)加工,不是采用全自動方式而是需要人工放果。該去皮機(jī)的發(fā)展方向是提高生產(chǎn)效率,盡量減輕人工勞動量,提高蘋果果肉損失率。2 蘋果自動去皮機(jī)總體方案設(shè)計(jì)2.1 蘋果自動去皮機(jī)方案確定 經(jīng)過比較市場上現(xiàn)有的蘋果去皮設(shè)備,還有該設(shè)計(jì)去皮機(jī)主要用途,確定設(shè)計(jì)一款小型的蘋果自動去皮機(jī)。市場上大型的生產(chǎn)設(shè)備就是一整天生產(chǎn)線,從蘋果的挑選,然后洗滌,再去皮去核,這種大型的設(shè)備可以減少人工,降低工人勞動量,但是這種不適合于小型企業(yè)的發(fā)展,因設(shè)備成本高,管理生產(chǎn)線對員工要求也高,還有就是設(shè)備需要維修時維修費(fèi)用高。另外目前市場上也有小型的蘋果去皮設(shè)備,機(jī)器可以完成去皮和去核兩個過程的工作。這種設(shè)備能滿足一般小型企業(yè)的生產(chǎn)要求,且價格也在小型企業(yè)的接受范圍之內(nèi)。本文設(shè)計(jì)的就是適合于小型企業(yè)的蘋果自動去皮機(jī)。采用PLC及步進(jìn)電機(jī)控制整個轉(zhuǎn)臺的間歇運(yùn)動,插果則采用氣缸,另外該去皮機(jī)能夠檢測是否有蘋果置于托盤上,和操作人的手是否離開工作臺,只有蘋果托盤上有蘋果且操作員手離開托盤設(shè)備才工作,這樣能夠很好確保操作員的人身安全,降低生產(chǎn)事故。2.2 蘋果自動去皮機(jī)工作原理及結(jié)構(gòu)組成2.2.1 蘋果自動去皮機(jī)工作原理 首先操作員將挑選并洗滌好的蘋果置于氣缸軸上的托盤上,傳感器檢測到信號后傳給PLC控制中心,同時還有個紅外檢測操作員手的設(shè)備,當(dāng)檢測到人手離開時,該信號也會傳給控制中心,控制中心的接到兩信號之后,大約1s后氣缸動作,將蘋果插入蘋果固定架上,之后步進(jìn)電機(jī)工作,蘋果固定架上電機(jī)工作,完成整個去皮過程,下一個工作周期開始,新的蘋果插入蘋果固定架時,之前一個蘋果在同樣氣缸的工作下完成切瓣、去核工作。就完成了一個蘋果從去皮到切半的過程。2.2.2 蘋果自動去皮機(jī)結(jié)構(gòu)組成 該蘋果自動去皮機(jī)主要包括送料裝置氣缸和蘋果托盤;去皮裝置刀架、刀片及轉(zhuǎn)動齒輪;蘋果旋轉(zhuǎn)裝置小型電機(jī);動力裝置步進(jìn)電機(jī)。另外附屬裝置轉(zhuǎn)動平臺及軸承。2.3 蘋果自動去皮機(jī)工作流程 整個設(shè)備的正確運(yùn)行是在控制中心PLC程序的控制下完成的,程序指令控制著設(shè)備的每一步操作,其工作流程圖如下:圖2-1 蘋果自動去皮機(jī)工作流程圖3 蘋果自動去皮機(jī)運(yùn)動機(jī)構(gòu)確定3.1 送料機(jī)構(gòu)的確定3.1.1 送料機(jī)構(gòu)方案設(shè)計(jì)傳統(tǒng)方式的送料方式是人工將蘋果插入蘋果固定針上,然后在轉(zhuǎn)盤帶動下轉(zhuǎn)動一定的位置,再進(jìn)行去皮操作。傳統(tǒng)方式效率低且蘋果不容易插入固定針上,操作時需要操作員使用較大力氣,這樣操作人員體力勞動強(qiáng)度就較大。本設(shè)計(jì)的送料方式則采用氣壓裝置,氣壓頂桿上有一個蘋果托盤,操作員只需要將蘋果置于托盤中即可。托盤中裝有光電傳感器,能檢測到托盤中是否放置蘋果。沒有則氣缸不會工作。另外再托盤的正上方裝有紅外檢測裝置,能夠檢測操作人員的手是否離開托盤,從而可以防止人身事故的發(fā)生,提高了產(chǎn)品的安全性。設(shè)計(jì)簡圖如下:蘋果托盤氣缸圖3-1 送料裝置簡圖3.1.2 送料機(jī)構(gòu)組件的確定1) 確定氣缸型號圖3-2 氣缸型號代碼圖3-3 氣缸規(guī)格圖3-4 氣缸行程選擇氣缸主要參數(shù)是行程,因?yàn)橐獙⑻O果送往一定的高度,初步確定氣缸型號為,該氣缸帶有感應(yīng)磁石,可以用霍爾傳感器來控制氣缸行程。從而更好的實(shí)現(xiàn)自動化控制。2) 氣缸的控制設(shè)計(jì)中沒有對氣缸其他設(shè)備進(jìn)行確定,如氣壓泵,管道等。本設(shè)計(jì)中的蘋果自動去皮機(jī)氣缸控制采用PLC來控制與氣缸連接的雙電磁鐵直動式換向閥,PLC通過采集光電傳感器和紅外檢測裝置的信號來控制氣缸的整個工作。另外通過霍爾傳感器來反饋氣缸動作桿的位置,從而能夠準(zhǔn)確的將蘋果送至工作臺上的蘋果固定針上。圖3-5 雙電磁鐵直動式換向閥3) 蘋果托盤蘋果托盤的形狀類似于生活中小孩子吃飯用的不銹鋼碗,在也有不同的是在托盤底部有一個短小的鋼針用來固定蘋果,防止蘋果在氣缸上升的過程中掉落或者側(cè)翻。大概形狀如下:圖3-6 蘋果托盤該托盤采用不銹鋼制作而成,底部通過焊接頂桿與氣缸頂桿相連,從而實(shí)現(xiàn)托盤的上下運(yùn)動,完成將蘋果送至固定針上的動作。3.2 工作臺轉(zhuǎn)動機(jī)構(gòu)的確定 工作臺轉(zhuǎn)動時有兩個運(yùn)動,一是工作臺自身的轉(zhuǎn)動,二是刀架固定桿的轉(zhuǎn)動。且刀架固定桿轉(zhuǎn)動比較特殊,兩個刀架固定桿位置對稱,但是運(yùn)動方向卻相反,因此采用直齒圓錐齒輪來實(shí)現(xiàn)該運(yùn)動,工作臺的轉(zhuǎn)動則采用直齒圓柱齒輪。3.2.1 直齒圓錐齒輪的設(shè)計(jì) 直齒錐齒輪加工多為刨齒,不宜采用硬齒面。材料選用40Cr,調(diào)質(zhì)處理,硬度為241HB286HB,取平均硬度為260HB。計(jì)算步驟如下(查圖、表均來自于機(jī)械設(shè)計(jì)第四版 邱宣懷主編):1)齒面接觸疲勞強(qiáng)度計(jì)算齒數(shù)z取z=24,由表12.6得精度等級選精度為8級精度查表12.9得使用壽命=1.0查圖12.9得動載系數(shù)=1.1齒間載荷分配系數(shù) (表12.19) (式12.6) (式12.10)齒向載荷分布系數(shù),查表12.20及注3得載荷系數(shù)查表12.12得彈性系數(shù),查圖12.16得節(jié)點(diǎn)區(qū)域系數(shù),查圖12.17c得接觸疲勞極限,查表12.14得接觸最小安全系數(shù)為:設(shè)計(jì)時不考慮機(jī)器壽命因素得接觸壽命系數(shù)許用接觸應(yīng)力 (式12.11)齒輪大端分度圓直徑,取齒寬系數(shù)2) 確定傳動主要尺寸大端模數(shù)查機(jī)械原理第七版附表5-6 錐齒輪模數(shù)(摘自GB12368-90)取實(shí)際大端分度圓直徑為錐距齒寬取3) 齒根彎曲疲勞強(qiáng)度計(jì)算查圖12.30得齒形系數(shù),查圖12.31得應(yīng)力修正系數(shù)得重合度系數(shù) (式12.18)齒間載荷分配系數(shù)載荷系數(shù)查圖12.33c得彎曲疲勞極限,查表12.14得彎曲最小安全系數(shù),不考慮壽命因素得彎曲壽命系數(shù),查圖12.25得尺寸系數(shù)為:許用彎曲應(yīng)力 (式12.19)驗(yàn)算因此該齒輪滿足強(qiáng)度要求。傳動方式如圖圖3-7 錐齒輪傳動3.2.2 直齒圓柱齒輪的設(shè)計(jì) 因傳動尺寸無嚴(yán)格限制,無嚴(yán)重過載,固小齒輪選用材料為,調(diào)質(zhì)處理,硬度為241HB286HB,平均取為260HB,大齒輪選用材料為45鋼,調(diào)質(zhì)處理,硬度為229HB286HB,平均取為240HB。計(jì)算步驟如下(查表、圖來自于機(jī)械設(shè)計(jì)第四版 邱宣懷主編):1) 齒面接觸疲勞強(qiáng)度計(jì)算1.初步計(jì)算查表12.13得齒寬系數(shù)查圖12.17c得接觸疲勞強(qiáng)度初步計(jì)算的許用接觸應(yīng)力查表12.16取初步計(jì)算的小齒輪直徑 (式12.14)取初步齒寬取2. 校核計(jì)算查表12.6得精度等級選8級精度齒數(shù)和模數(shù)初步齒數(shù)查(機(jī)械原理第七版 鄭文緯 吳克堅(jiān) 主編)附表5-6 錐齒輪模數(shù)(摘自GB12368-90)得,則查表12.9得使用系數(shù),查圖12.9得動載系數(shù)齒間載荷分配系數(shù)由表12.10,先求 (式12.6) (式12.10)查表12.11得齒向載荷分布系數(shù)載荷系數(shù)查表12.12得彈性系數(shù),查圖12.16得節(jié)點(diǎn)區(qū)域系數(shù),接觸最小安全系數(shù)接觸壽命系數(shù)許用接觸應(yīng)力驗(yàn)算 (式12.8)計(jì)算結(jié)果表明,接觸疲勞強(qiáng)度較為合適,齒輪尺寸無需調(diào)整。3. 確定傳動主要尺寸實(shí)際分度圓直徑,因模數(shù)取標(biāo)準(zhǔn)時,齒輪已重新確定,但并未圓整,故分度圓直徑不會改變,即中心距齒寬取2) 齒根彎曲疲勞強(qiáng)度驗(yàn)算重合度系數(shù)齒間載荷分配系數(shù)查圖12.14得齒向載荷分布系數(shù)載荷系數(shù)查圖12.21得齒形系數(shù),查圖12.22應(yīng)力修正系數(shù),查圖12.23c彎曲疲勞極限,查表12.14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(yīng)力驗(yàn)算 (式12.16)經(jīng)驗(yàn)算強(qiáng)度合格。傳動方式如圖:圖3-8 直齒輪傳動3.3 蘋果自動去皮機(jī)去皮及蘋果固定裝置3.3.1 刀架的設(shè)計(jì)蘋果自動去皮機(jī)刀架工作時主要是自身的轉(zhuǎn)動,其次還有跟著工作臺一起轉(zhuǎn)動。蘋果固定在固定針上時,蘋果以較快的速度旋轉(zhuǎn),此時刀架上的刀片貼著蘋果,這樣就達(dá)到了去皮的效果。刀架在去皮的過程中還有上下運(yùn)動的一個過程,這樣才能保證將蘋果的皮去干凈,如果刀架不能隨著蘋果的轉(zhuǎn)動而上下運(yùn)動的話,那只會在一個部位進(jìn)行切削。這樣就達(dá)不到去皮的作用。每將一個去皮后,刀架的位置都是在蘋果的底部位置,因此需要用彈簧來將刀架復(fù)位才能進(jìn)行下一次的蘋果去皮。刀架在運(yùn)動時不能與蘋果托盤及蘋果固定針發(fā)生干涉現(xiàn)象,另外也不能與蘋果切瓣、去核裝置發(fā)生干涉現(xiàn)象,需要調(diào)節(jié)安裝在刀架上的兩個彈簧,從而達(dá)到比較理想的效果。刀架的效果圖如下:圖3-9 刀架位置簡圖刀架會隨著蘋果的轉(zhuǎn)動而上下擺動,因此設(shè)計(jì)了可以調(diào)節(jié)的裝置,并配上彈簧。彈簧能夠是刀片離開蘋果時能恢復(fù)初始位置,且保持穩(wěn)定。3.3.2 刀片的設(shè)計(jì)刀片在蘋果去皮過程中有著非常重要的作用,且刀片角度對蘋果去皮效果相當(dāng)明顯。刀片角度不合適時,會切掉很大部分的蘋果果肉,這樣就浪費(fèi)原材料。刀片固定在刀架上,角度能夠調(diào)節(jié),合適的角度需要在實(shí)驗(yàn)中得到。在給蘋果去皮的過程中,不斷的調(diào)節(jié)刀片角度,知道去皮效果達(dá)到理想值時固定刀片。一般蘋果首先需要經(jīng)過粗略的挑選,因?yàn)橛行┨O果形狀不適合固定角度刀片的切削,去皮時刀片對蘋果大小要求不高,主要是形狀要規(guī)則,不能有大的凸起或者凹陷。刀片的形狀跟平常家用的手動去皮器具相同,平常家用的去皮器是依靠人來掌握去皮的厚度,速度也是由操作人控制,熟練的人很快就能將蘋果削好,且切皮完整。該蘋果自動去皮機(jī)要達(dá)到的效果是切皮完整且厚度均勻。圖3-10 家用去皮工具3.3.2 蘋果固定裝置 蘋果由氣缸送至蘋果固定針上,然后在電機(jī)的帶動下,蘋果以一定速度旋轉(zhuǎn),刀片貼緊蘋果,通過相互運(yùn)動,從而達(dá)到去皮的作用。固定針需要在旋轉(zhuǎn)時提供一定的摩擦力,防止不能使蘋果轉(zhuǎn)動的情況發(fā)生。因此在設(shè)計(jì)時在蘋果固定針周圍刻一些花紋,用來增加蘋果與固定針之間的作用力。固定針簡圖如下:圖3-11 蘋果固定針簡圖4 電機(jī)的選擇4.1 確定電機(jī)類型 電機(jī)是整個設(shè)備的動力來源,該蘋果自動去皮機(jī)工作臺的運(yùn)動直接由電機(jī)控制,工作臺運(yùn)動包括間歇運(yùn)動,連續(xù)圓周運(yùn)動,還有停止。因此對電動機(jī)的啟動慣性,停止慣性要求非常高。而且電機(jī)的運(yùn)動要容易控制。由于本蘋果自動去皮機(jī)采用PLC進(jìn)行控制,所以電機(jī)選用步進(jìn)電機(jī)。步進(jìn)電機(jī)是將電脈沖信號轉(zhuǎn)變?yōu)榻俏灰苹蚓€位移的開環(huán)控制元件。在非超載的情況下,電機(jī)的轉(zhuǎn)速、停止的位置只取決于脈沖信號的頻率和脈沖數(shù),而不受負(fù)載變化的影響,即給電機(jī)加一個脈沖信號,電機(jī)則轉(zhuǎn)過一個步距角。 步進(jìn)電機(jī)是一種將電脈沖轉(zhuǎn)化為角位移的執(zhí)行機(jī)構(gòu)。通俗一點(diǎn)講:當(dāng)步進(jìn)驅(qū)動器接收到一個脈沖信號,它就驅(qū)動步進(jìn)電機(jī)按設(shè)定的方向轉(zhuǎn)動一個固定的角度(即步進(jìn)角)。您可以通過控制脈沖個數(shù)來控制角位移量,從而達(dá)到準(zhǔn)確定位的目的;同時您可以通過控制脈沖頻率來控制電機(jī)轉(zhuǎn)動的速度和加速度,從而達(dá)到調(diào)速的目的。 圖4-1 步進(jìn)電機(jī)4.2 步進(jìn)電機(jī)參數(shù)1)步進(jìn)電機(jī)基本參數(shù)(1) 電機(jī)固有步距角(2) 步進(jìn)電機(jī)的相數(shù)(3) 轉(zhuǎn)矩2) 確定蘋果自動去皮機(jī)工作臺步進(jìn)電機(jī)參數(shù)經(jīng)過查閱相關(guān)資料后確定工作臺電機(jī)選用110系列電機(jī),110系列電機(jī)參數(shù)如下:表4-1 110系列步進(jìn)電機(jī)參數(shù)110系列電機(jī)絕緣電阻: 500VDC 100MW Min軸向間隙: 0.10.3mm徑向跳動: 0.02mm Max溫 升: 65K Max絕緣強(qiáng)度: 550V 50Hz 1Minute環(huán)境溫度: -20C+55C絕緣等級: B型號步距角()保持轉(zhuǎn)矩(Nm)靜態(tài)相電流(A)相電阻 (W)相電感 (mH)轉(zhuǎn)動慣量(g.cm.s2)重量(Kg)110BH2A100-504 1.812.75.00.951555005.0110BH2A150-654 216.51.1518.9110008.4110BH2A165-604 266.00.6514130009.5110BH2A200-654 306.51.722.51620011.7型號長度:L110BH2A100-504 100mm110BH2A150-654 150mm110BH2A165-604 165mm110BH2A200-654 200mm選用110系列電機(jī)中110BH2A200-654這一型號電機(jī),該電機(jī)步距角1.8,保持轉(zhuǎn)矩30NM。長度L為150mm.3) 確定蘋果去皮旋轉(zhuǎn)電機(jī)蘋果在固定針上隨著工作臺旋轉(zhuǎn)時,自身也會快速的旋轉(zhuǎn)。速度比工作臺的轉(zhuǎn)動速度快好幾倍,但是也要能夠及時停止,工作。因此對電機(jī)的運(yùn)動狀態(tài)要求也較高。最終也確定選用步進(jìn)電機(jī)。由于蘋果轉(zhuǎn)動時需要的力比較小,所以對步進(jìn)電機(jī)保持轉(zhuǎn)矩要求相對較低。查閱步進(jìn)電機(jī)手冊確定選用以下系列電機(jī)。表4-2 57系列步進(jìn)電機(jī)參數(shù)57系列電機(jī)絕緣電阻: 500VDC 100MW Min軸向間隙: 0.10.3mm徑向跳動: 0.02mm Max溫 升: 65K Max絕緣強(qiáng)度: 550V 50Hz 1Minute環(huán)境溫度: -20C+55C絕緣等級: B型號步距角()保持轉(zhuǎn)矩(Nm)靜態(tài)相電流(A)相電阻 (W)相電感 (mH)轉(zhuǎn)動慣量(g.cm.s2)重量(Kg)57BH2A41-1481.80.51.41.41.41350.457BH2A56-28812.80.751.23000.757BH2A76-2881.472.812.14801.057BH2A76-304231.35.04801.0單位:mmL: 57BH2A41-148=41L: 57BH2A56-288=56L: 57BH2A76-288=76L: 57BH2A76-304=76確定選用型號為57BH2A76-304的步進(jìn)電機(jī),其步距角為1.8,保持轉(zhuǎn)矩2NM,機(jī)身長度L為76mm.5 軸設(shè)計(jì)校核及軸承的選擇5.1 短軸的設(shè)計(jì)1) 短軸最小直徑的確定選取軸的材料為45鋼(調(diào)質(zhì)),查資料得:軸的最小直徑材料相關(guān)系數(shù)表16.2 軸強(qiáng)度計(jì)算公式的系數(shù)軸的材料Q235,20Q255,Q275,354540Cr,38SiMnMo等12152025303540455216014813512511811210610298資料來源:機(jī)械設(shè)計(jì)(第四版) 邱宣懷 主編求得輸入軸的最小直徑考慮軸要開鍵槽所以2) 短軸的結(jié)構(gòu)設(shè)計(jì)采用以下軸上零件的裝配方案:由于該軸最左端安裝刀架,因此設(shè)計(jì)了的螺紋,便于固定刀架。安裝齒輪處的軸段的直徑齒輪采用軸肩和螺栓進(jìn)行定位。圓錐齒輪的周向定位采用平鍵連接,由機(jī)械制圖(第五版)附錄附表15和附表16查得平鍵截面:鍵槽用鍵槽銑刀加工,長為24mm,同時為保證齒輪與軸配合有良好的對中性,故選擇齒輪輪轂與軸的配合為;滾動軸承與軸的周向定位是由過渡配合來保證的,此處選軸的尺寸公差為。取軸端倒角為5.2 短軸的校核1)軸受力圖2)水平面(xy平面)受力圖3)水平彎矩圖4)垂直(xz平面)受力圖5)垂直面彎矩圖6)合成彎矩圖7) 轉(zhuǎn)矩圖8) 當(dāng)量彎矩圖9) 軸強(qiáng)度校核 = = 故軸安全。5.3 軸承的選擇 1)短軸上軸承的選擇因軸承同時受有徑向力和軸向力,但由于此錐齒輪轉(zhuǎn)速很慢,所以軸向力可以忽略,主要就是徑向力,故選用深溝球軸承,參照工作要求并根據(jù),由機(jī)械設(shè)計(jì)(第四版)附錄 常用滾動軸承尺寸和主要性能參數(shù)附錄表18.1 深溝球軸承 GB/T 276中初步選取軸承代號6304,其尺寸為,采用軸肩進(jìn)行軸向定位,取中間一段軸直徑。2) 長軸上軸承的選擇由于工作筒全部有安裝在長軸上一個軸承承擔(dān),所以該軸承承受的軸向力較大,深溝球軸承雖然可以承受小部分的軸向力,但是考慮壽命及經(jīng)濟(jì)因素,確定使用推力球軸承,該種軸承只能受單向軸向載荷。由機(jī)械設(shè)計(jì)(第四版)附錄 常用滾動軸承尺寸和主要性能參數(shù)附錄表18.5 推力球軸承 GB/T 1292確定選用軸承代號為7204C,其尺寸為。6 蘋果自動去皮機(jī)仿真圖圖6-1圖6-2結(jié)束語 經(jīng)過一個多月的設(shè)計(jì)和查閱相關(guān)資料,終于完成了蘋果自動去皮機(jī)的設(shè)計(jì)。從畢業(yè)選題開始到最終確定畢業(yè)設(shè)計(jì)題目,到開始方案設(shè)計(jì),再到設(shè)計(jì)文章的完成,每一步都是自己對未知事物的探索和挑戰(zhàn)。在大學(xué)期間能獨(dú)立完成一個這么大的項(xiàng)目,對自己也是一個很大的挑戰(zhàn),設(shè)計(jì)過程中,查閱了大學(xué)期間專業(yè)課書籍,對大學(xué)所學(xué)的知識專業(yè)知識從頭到尾重新整理了一遍。另外在設(shè)計(jì)過程中也查閱了機(jī)械手冊及其他手冊,學(xué)會了如何利用身邊的工具書進(jìn)行設(shè)計(jì)參數(shù)的選擇。雖然設(shè)計(jì)過程中出現(xiàn)了一些小問題,但是在老師和同學(xué)的幫助下,很多問題都迎刃而解。 經(jīng)過這次畢業(yè)設(shè)計(jì)使我受益頗多,我感受到要做好一件事就要真正的用心,只有自己用心之做了,不管結(jié)果怎么樣,在做的過程中才是自己真正增長知識的過程,只有經(jīng)歷這樣的過程自己才能夠真正的成長。相信這次的畢業(yè)設(shè)計(jì)對我以后的工作及人生會有很大的幫助,使我終身受益。參考文獻(xiàn)1 劉鴻文主編.材料力學(xué)M.第五版.北京:高等教育出版社,2011.12 邱宣懷主編.機(jī)械設(shè)計(jì)第四版M.北京:高等教育出版社,2011.73 成大先主編.機(jī)械設(shè)計(jì)手冊.第1卷M.第五版.北京:化學(xué)工業(yè)出版社,2007.114 成大先主編.機(jī)械設(shè)計(jì)手冊.第5卷M.第五版.北京:化學(xué)工業(yè)出版社,2007.115 何銘新,錢可強(qiáng)主編.機(jī)械制圖.第五版M.北京:高等教育出版社.2004.16 鄭文緯,吳克堅(jiān)主編.機(jī)械原理.第七版M.北京:高等教育出版社7 陳于萍,周兆元主編.互換性測量技術(shù)基礎(chǔ).第2版M.北京:機(jī)械工業(yè)出版社.2005 何銘新,錢可強(qiáng)主編.機(jī)械制圖.第五版M.北京:高等教育出版社.2005.108 汝元功,唐照民主編.機(jī)械設(shè)計(jì)手冊M.北京:高等教育出版社.19959 鄭文緯,吳克堅(jiān)主編.機(jī)械原理.高等教育出版社1997年7月10 汝元功,唐照民主編.機(jī)械設(shè)計(jì)手冊.高等教育出版社1995年12月11 哈爾濱工業(yè)大學(xué)理論力學(xué)教研室主編.理論力學(xué)I.高等教育出版社2009年7月12 簡明機(jī)械零件設(shè)計(jì)實(shí)用手冊。機(jī)械工業(yè)出版社,199913 機(jī)械設(shè)計(jì)課程設(shè)計(jì),第3版。機(jī)械工業(yè)出版社,200014 機(jī)械設(shè)計(jì)綜合課程設(shè)計(jì)。機(jī)械工業(yè)出版社,200315 機(jī)械零件。高等教育出版社,198716 機(jī)械設(shè)計(jì)課程設(shè)計(jì)。華中理工大學(xué)出版社,199517 齒輪手冊。機(jī)械工業(yè)出版社,1990致 謝 這次畢業(yè)設(shè)計(jì)說明書、裝配圖及其PROE立體圖的完成,首先要感謝我的指導(dǎo)老師在畢業(yè)設(shè)計(jì)裝配圖及其說明書編制過程中,給予了精心的指導(dǎo),并講解了各項(xiàng)專業(yè)要領(lǐng),提出了寶貴的專業(yè)意見,蘋果自動去皮機(jī)設(shè)計(jì)過程中,也要感謝曾經(jīng)的科任教師,是他們的之前的精心指導(dǎo)和教學(xué)才使我的畢業(yè)設(shè)計(jì)能夠按期完成,另外還要感謝同學(xué)的無私幫助。同時要感謝百忙之中參加畢業(yè)答辯的評審老師。祝老師們身體健康、事事順利,同學(xué)們前程似錦。謝謝。34畢業(yè)設(shè)計(jì)(論文)任務(wù)書設(shè)計(jì)(論文)課題名稱蘋果自動去皮機(jī)機(jī)械設(shè)計(jì)學(xué)生姓名院(系)工學(xué)院專 業(yè)機(jī)制指導(dǎo)教師職 稱講師學(xué) 歷博士畢業(yè)設(shè)計(jì)(論文)要求:1 設(shè)計(jì)要自己獨(dú)立完成,不得抄襲,要具有一定的實(shí)用性;2 通過查閱資料,擴(kuò)充知識面,進(jìn)一步熟練AutoCAD ,Proe軟件制圖;3 自學(xué)習(xí)蘋果自動去皮機(jī)方向的相關(guān)知識;4 初步完成對蘋果自動去皮機(jī)工作原理,整體框架的設(shè)計(jì);5 繪制蘋果自動去皮機(jī)的裝配圖和非標(biāo)準(zhǔn)件的零件圖;6 寫畢業(yè)任務(wù)說明書。畢業(yè)設(shè)計(jì)(論文)內(nèi)容與技術(shù)參數(shù):1 完成對蘋果自動去皮機(jī)整體方案的設(shè)計(jì),完成相應(yīng)的零件圖紙,裝配圖紙折合A0號圖紙1.5張以上。并需要用AutoCAD和Proe繪制。2 編寫相應(yīng)的說明書,字?jǐn)?shù)不少于4000字,必須是打印稿,并提供電子文檔。說明書必須包括蘋果自動去皮機(jī)總體方案的設(shè)計(jì),蘋果自動去皮機(jī)運(yùn)動機(jī)構(gòu)的確定,電機(jī)的選擇,軸的設(shè)計(jì)和軸承的選擇。畢業(yè)設(shè)計(jì)(論文)工作計(jì)劃:2.20-2.24畢業(yè)設(shè)計(jì)實(shí)習(xí),包括去工廠對蘋果自動去皮機(jī)的參觀和學(xué)習(xí)。2.25-3.5 調(diào)研,收集資料3.6-3.17 繪制蘋果自動去皮機(jī)結(jié)構(gòu)草圖,并討論之3.18-3.25中期考核3.26-4.10 繪制蘋果自動去皮機(jī)的裝配圖4.11-5.5 繪制蘋果自動去皮機(jī)相應(yīng)的非標(biāo)準(zhǔn)零件圖5.5-5.10撰寫設(shè)計(jì)指導(dǎo)書接受任務(wù)日期 2013 年 12 月 20 日 要求完成日期 2013 年 5 月 14 日學(xué) 生 簽 名 2013 年 5月 14日指導(dǎo)教師簽名 2013年 5月 14日院長(主任)簽名 2013年 5月 14日翻譯部分英文原文Gear mechanismsGear mechanisms are used for transmitting motion and power from one shaft to another by means of the positive contact of successively engaging teeth. In about 2,600B.C., Chinese are known to have used a chariot incorporating a complex series of gears like those illustrated in Fig.2.7. Aristotle, in the fourth century B .C .wrote of gears as if they were commonplace. In the fifteenth century A.D., Leonardo da Vinci designed a multitude of devices incorporating many kinds of gears. In comparison with belt and chain drives ,gear drives are more compact ,can operate at high speeds, and can be used where precise timing is desired. The transmission efficiency of gears is as high as 98 percent. On the other hand, gears are usually more costly and require more attention to lubrication, cleanliness, shaft alignment, etc., and usually operate in a closed case with provision for proper lubrication.Gear mechanisms can be divided into planar gear mechanisms and spatial gear mechanisms. Planar gear mechanisms are used to transmit motion and spatial gear mechanisms. Planar gear mechanisms are used to transmit motion and power between parallel shafts ,and spatial gear mechanisms between nonparallel shafts.Types of gears(1) Spur gears. The spur gear has a cylindrical pitch surface and has straight teeth parallel to its axis as shown in Fig. 2.8. They are used to transmit motion and power between parallel shafts. The tooth surfaces of spur gears contact on a straight line parallel to the axes of gears. This implies that tooth profiles go into and out of contact along the whole facewidth at the same time. This will therefore result in the sudden loading and sudden unloading on teeth as profiles go into and out of contact. As aresult, vibration and noise are produced.(2) Helical gears. These gears have their tooth elements at an angle or helix to the axis of the gear(Fig.2.9). The tooth surfaces of two engaging helical gears inn planar gear mechanisms contact on a straight line inclined to the axes of the gears. The length of the contact line changes gradually from zero to maximum and then from maximum to zero. The loading and unloading of the teeth become gradual and smooth. Helical gears may be used to transmit motion and power between parallel shaftsFig. 2.9(a)or shafts at an angle to each otherFig. 2.9(d). A herringbone gear Fig. 2.9(c) is equivalent to a right-hand and a left-hand helical gear placed side by side. Because of the angle of the tooth, helical gears create considerable side thrust on the shaft. A herringbone gear corrects this thrust by neutralizing it , allowing the use of a small thrust bearing instead of a large one and perhaps eliminating one altogether. Often a central groove is made around the gear for ease in machining.(3) Bevel gars. The teeth of a bevel gear are distributed on the frustum of a cone. The corresponding pitch cylinder in cylindrical gears becomes pitch cone. The dimensions of teeth on different transverse planes are different. For convenience, parameters and dimensions at the large end are taken to be standard values. Bevel gears are used to connect shafts which are not parallel to each other. Usually the shafts are 90 deg. to each other, but may be more or less than 90 deg. The two mating gears may have the same number of teeth for the purpose of changing direction of motion only, or they may have a different number of teeth for the purpose of changing both speed and direction. The tooth elements may be straight or spiral, so that we have plain and spiral bevel gears. Hypoid comes from the word hyperboloid and indicates the surface on which the tooth face lies. Hypoid gears are similar to bevel gears, but the two shafts do not intersect. The teeth are curved, and because of the nonintersection of the shafts, bearings can be placed on each side of each gear. The principal use of thid type of gear is in automobile rear ends for the purpose of lowering the drive shaft, and thus the car floor.(4) Worm and worm gears. Worm gear drives are used to transmit motion and ower between non-intersecting and non-parallel shafts, usually crossing at a right angle, especially where it is desired to obtain high gear reduction in a limited space. Worms are a kind of screw, usually right handed for convenience of cutting, or left handed it necessary. According to the enveloping type, worms can be divided into single and double enveloping. Worms are usually drivers to reduce the speed. If not self-locking, a worm gear can also be the driver in a so called back-driving mechanism to increase the speed. Two things characterize worm gearing (a) large velocity ratios, and (b) high sliding velocities. The latter means that heat generation and power transmission efficiency are of greater concern than with other types of gears.(5) Racks. A rack is a gear with an infinite radius, or a gear with its perimeter stretched out into a straight line. It is used to change reciprocating motion to rotary motion or vice versa. A lathe rack and pinion is good example of this mechanism.Geometry of gear toothThe basic requirement of gear-tooth geometry is the provision of angular velocity rations that are exactly constant. Of course, manufacturing inaccuracies and tooth deflections well cause slight deviations in velocity ratio; but acceptable tooth profiles are based on theoretical curves that meet this criterion.The action of a pair of gear teeth satisfying this requirement is termed conjugate gear-tooth action, and is illustrated in Fig. 2.12. The basic law of conjugate gear-tooth action states that as the gears rotate, the common normal to the surfaces at the point of contact must always intersect the line of centers at the same point P called the pitch point.The law of conjugate gear-tooth can be satisfied by various tooth shapes, but the only one of current importance is the involute, or, more precisely, the involute of the circle. (Its last important competitor was the cycloidal shape, used in the gears of Model T Ford transmissions.) An involute (of the circle) is the curve generated by any point on a taut thread as it unwinds from a circle, called the base circle. The generation of two involutes is shown in Fig. 2.13. The dotted lines show how these could correspond to the outer portion of the right sides of adjacent gear teeth. Correspondingly, involutes generated by unwinding a thread wrapped counterclockwise around the base circle would for the outer portions of the left sides of the teeth. Note that at every point, the involute is perpendicular to the taut thread, since the involute is a circular arc with everincreasing radius, and a radius is always perpendicular to its circular arc. It is important to note that an involute can be developed as far as desired outside the base circle, but an involute cannot exist inside its base circle.Let us now develop a mating pair of involute gear teeth in three steps: friction drive, belt drive, and finally, involute gear-tooth drive. Figure 2.14 shows two pitch circles. Imagine that they represent two cylinders pressed together. If slippage does not occur, rotation of one cylinder (pitch circle) will cause rotation of the other at an angular velocity ratio inversely proportional to their diameters. In any pair of mating gears, the smaller of the two is called the pinion and the larger one the gear. (The term “gear” is used in a general sense to indicate either of the members, and also in a specific sense to indicate the larger of the two.) Using subscripts p and g to denote pinion and gear, respectively.In order to transmit more torque than is possible with friction drive alone, we now add a belt drive running between pulleys representing the base circles, as in Fig 2.15. If the pinion is turned counterclockwise a few degrees, the belt will cause the gear to rotate in accordance with correct velocity ratio. In gear parlance, angle is called the pressure angle. From similar triangles, the base circles have the same ratio as the pitch; thus, the velocity ratio provided by the friction and belt drives are the same.In Fig. 2.16 the belt is cut at point c, and the two ends are used to generate involute profiles de and fg for the pinion and gear, respectively. It should now be clear why is called the pressure angle: neglecting sliding friction, the force of one involute tooth pushing against the other is always at an angle equal to the pressure angle. A comparison of Fig. 2.16 and Fig.2.12 shows that the involute profiles do indeed satisfy the fundamental law of conjugate gear-tooth action. Incidentally, the involute is the only geometric profile satisfying this law that maintains a constant pressure angle as the gears rotate. Note especially that conjugate involute action can take place only outside of both base circles.Nomenclature of spur gear The nomenclature of spur gear (Fig .2.17) is mostly applicable to all other type of gears.The diameter of each of the original rolling cylinders of two mating gears is called the pitch diameter, and the cylinders sectional outline is called the pitch circle. The pitch circles are tangent to each other at pitch point. The circle from which the involute is generated is called the base circle. The circle where the tops of the teeth lie is called the dedendum circle. Similarly, the circle where the roots of the teeth lie is called the dedendum circle. Between the addendum circle and the dedendum circle, there is an important circle which is called the reference circle. Parameters on the reference circle are standardized. The module m of a gear is introduced on the reference circle as a basic parameter, which is defined as m=p/. Sizes of the teeth and gear are proportional to the module m.The addendum is the radial distance from the reference circle to the addendum circle. The dedendum is the radial distance from the reference circle to the dedendum circle. Clearance is the difference between addendum and dedendum in mating gears. Clearance prevents binding caused by any possible eccentricity.The circular pitch p is the distance between corresponding side of neighboring teeth, measured along the reference circle. The base pitch is similar to the circular pitch is measured along the base circle instead of along the reference circle. It can easily be seen that the base radius equals the reference radius times the cosine of the pressure angle. Since, for a given angle, the ratio between any subtended arc and its radius is constant, it is also true that the base pitch equals the circular pitch times the cosine of the pressure angle. The pressure angle is the angle between the normal and the circumferential velocity of the point on a specific circle. The pressure angle on the reference circle is also standardized. It is most commonly 20(sometimes 15).The line of centers is a line passing through the centers of two mating gears. The center distance (measured along the line of centers) equals the sum of the pitch radii of pinion and gear.Tooth thickness is the width of the tooth, measured along the reference circle, is also referred to as tooth thickness. Width of space is the distance between facing side of adjacent teeth, measured along the reference circle. Tooth thickness plus width of space equals the circular pitch. Backlash is the width of space minus the tooth thickness. Face width measures tooth width in an axial direction.The face of the tooth is the active surface of the tooth outside the pitch cylinder. The flank of the tooth is the active surface inside the pitch cylinder. The fillet is the rounded corner at the base of the tooth. The working depth is the sum of the addendum of a gear and the addendum of its mating gear.In order to mate properly, gears running together must have: (a) the same module; (b) the same pressure angle; (c) the same addendum and dedendum. The last requirement is valid for standard gears only. Rolling-Contactbearings The rolling-contact bearing consists of niier and outer rings sepatated by a number of rolling elements in the form of balls ,which are held in separators or retainers, and roller bearings have mainly cyinndrical, conical , or barrelcage.The needles are retainde by integral flanges on the outer race, Bearigs with rolling contact have no skopstick effect,low statting torqeu and running friction,and unlike as in journal bearings. The coefficient of friction varies little with load or opeed.Probably the outstanding of a rolling-contant beating over a sliding bearing is its low statting friction.The srdinary sliding bearing starts from rest with practically metal to metal contact and has a high coefficient of friction as compared with that between rolling members.This teature is of particular important in the case of beatings whcch vust carry the same laode at test as when tunning,for example.less than one-thirtieth as much force is required to start a raliroad freight car equopped with roller beatings as with plain journal bearings.However.most journal bearing can only carry relatively light loads while starting and do not become heavily loaded until the speed is high enough for a hydrodynamic film to be built up.At this time the friction id that in the luvricant ,and in a properly designed journal bearing the viscous friction will be in the same order of magnitude ad that for a that for a rolling-conanct bearing.中文譯文齒輪機(jī)構(gòu)齒輪機(jī)構(gòu)用來傳遞運(yùn)動和動力,通過連續(xù)嚙合輪齒的正確接觸,從一根軸傳動到另一根軸。大約公元前2600年,中國人就能夠使用一系列戰(zhàn)車而聞名復(fù)雜的齒輪機(jī)構(gòu)而構(gòu)成的。公元前4世紀(jì),亞里士多德寫的齒輪好象推動的是平凡的。在公元15世紀(jì),Leonardo da Vinci 設(shè)計(jì)了能與許多種類的齒輪樞結(jié)合的大量裝置。與皮帶和鏈傳動相比較,齒輪傳動裝置更加緊湊,能高速運(yùn)行,也能夠被運(yùn)用在要求準(zhǔn)確定時的場合。齒輪傳動的傳動效率高達(dá)98。另一方面,齒輪傳動機(jī)構(gòu)成本高,而且要求注意潤滑、清潔度、軸的對中等等,經(jīng)常用在提供準(zhǔn)確箱體潤滑的閉式情況下。齒輪機(jī)構(gòu)能被分為平面齒輪機(jī)構(gòu)和空間齒輪機(jī)構(gòu)。平面齒輪機(jī)構(gòu)被用于傳遞運(yùn)動和動力,而平行軸間的運(yùn)動和動力空間齒輪機(jī)構(gòu)用于傳遞不平行軸間的運(yùn)動和動力。齒輪的分類:1、 直齒輪 直齒輪有節(jié)輪表面和平行于輪的軸線的直齒輪,如圖2.8所示。它們用于傳遞兩平行軸間的運(yùn)動和動力。兩配合的直接齒面嚙合在一條平行于其軸線的直線上,這意味著整個齒寬在同一時刻嚙合脫開,這樣在齒面上導(dǎo)致加載或卸載,當(dāng)齒輪嚙合或脫開時,結(jié)果推動和噪聲就產(chǎn)生了。(1) 斜齒輪 這種齒輪的輪齒有一位角度或與其軸線旋轉(zhuǎn)一定角度在平面齒輪機(jī)構(gòu)中相互嚙合,斜齒輪齒面相嚙合于一條傾斜于軸承的直線上,嚙合線的長度從0逐漸變化到最大再從最大變化到0,輪齒的加載和卸載變得平穩(wěn)均勻的運(yùn)動和動力。人字齒輪相當(dāng)于右旋齒輪和左旋齒輪并在一起,因?yàn)檩嘄X存在一定角度,斜齒輪產(chǎn)生相當(dāng)大的軸間推力,人字齒輪通過相互抵消糾正了這一推力,允許其使用以推力軸承代替大推力軸承,或不同推力軸承,為了加工方便經(jīng)常沿著齒輪加工一個中心槽。(2) 傘狀齒輪 傘狀齒輪是依據(jù)平截頭圓錐體分配的。圓柱齒輪的節(jié)圓柱成為分圓錐,齒輪的齒的橫剖面的尺寸是不同的。為了方便起見,錐齒輪的大頭端部的參數(shù)和尺寸作為標(biāo)準(zhǔn)值。習(xí)慣上錐齒輪相互作用的軸彼此不是平行的,通常兩軸線彼此成為90度,有時會比90度或多或少。兩個相互嚙合的齒輪僅僅為了變向或許有一樣的齒數(shù),又或者為了改變速度和方向而齒數(shù)不同。錐齒輪可能是直齒的也可能是螺旋形齒輪,以便我們有簡單的和螺旋形的齒輪。準(zhǔn)雙曲面來自于雙曲面和齒面的放置的表面。準(zhǔn)雙曲面的齒輪屬于錐齒輪,但是兩軸不能橫斷,因?yàn)檩S的材料,它的齒是曲線的,軸承可以位于各齒輪的各個側(cè)面。這種齒輪主要用在汽車后方末端是為了降低傳動軸并且用在汽車踏板處。(3) 蝸輪蝸桿齒輪 蝸輪傳動慣于傳遞動力和功率,它的軸既不相交也不平行,通常都是垂直的,尤其是要求獲得高的齒輪減速在一定的極限運(yùn)算范圍內(nèi)。蝸桿是螺旋的,通常為了方便起見都是順時針方向的,如果需要的話也可是左旋方向的。按照類型,可以是單螺旋的也可以是雙螺旋的,螺桿通常用來降低速度的,即使不自動鎖住,螺桿也能夠被驅(qū)動,所以稱作回力驅(qū)動機(jī)構(gòu),為了提高速度。下面是蝸輪蝸桿傳動裝置的兩個特點(diǎn):(a)有很高的傳動速度(b)后者意思指和其它種類的齒輪相比中心有高的發(fā)熱性和電力傳輸效率。齒輪輪齒形狀輪齒幾何形狀的基本要求提供一個準(zhǔn)確不變的角速度,當(dāng)然制造端差和輪齒變形將會在速度比上產(chǎn)生微小的偏差,然而可接受的齒形依據(jù)基于滿足這一判劇的理論曲線得出的。滿足這要求的一對配合齒輪的運(yùn)動被稱為共軛齒輪傳動。如圖2.12所示,共軛齒輪傳動的基本定律論述為當(dāng)齒輪轉(zhuǎn)動時,接觸點(diǎn)表面的公法線總是與中心線交于一點(diǎn)P,這點(diǎn)叫節(jié)點(diǎn)。共軛齒輪傳動原則能被各種齒形適應(yīng),目前最重要的一種是漸開線齒輪更精確地說一個圓的漸開線(與它相近的重要的競爭者是擺線齒輪,它被用在福特汽車廠模式中)是條曲線,當(dāng)從一個基圓滿開時,張緊線上每一點(diǎn)所形成的,兩條漸近線輪齒右外形相對應(yīng),相應(yīng)地,通過逆時針方向展開預(yù)先在右基圓上的線所產(chǎn)生的漸開線會形成輪齒左邊的外形,該點(diǎn)在每一點(diǎn)上,漸開線始終垂直于這條張緊線,因?yàn)闈u開線理一條半徑不斷增加的圓弧,值得注意的是漸開線能夠在基圓外部產(chǎn)生并繪制,而不能在基圓里面。用以下三個步驟研究一對相配合的齒輪:摩擦傳動,帶傳動和漸開線齒輪傳動。如圖2.14所示兩個節(jié)圓,假設(shè)他們是兩個壓在一起的圓柱,如果不發(fā)生打滑,一個圓柱的旋轉(zhuǎn)會引起另一個圓柱以一定角速度旋轉(zhuǎn),且這個速比反比于他們的直徑比,任何一對相嚙合的齒輪,兩個中較小的叫小齒輪,較大的叫大齒輪,用下標(biāo)p和g分別指明。為了使傳動的扭矩比摩擦傳動產(chǎn)生的扭矩大,要附加一個帶有基圓的皮帶辦的皮帶驅(qū)動裝置。如圖2.15所示,如圖,小齒輪逆時針旋轉(zhuǎn)一個小角度,皮帶將帶動大齒輪以相應(yīng)的速比旋轉(zhuǎn),在齒輪傳動中,角度為壓力角,人相似三角形得,把基圓具有相同速度的點(diǎn)稱為節(jié)點(diǎn)。如圖2.16中皮帶在c點(diǎn)被切斷,兩端分別形成了大齒輪和大齒輪上的漸開線齒形DE和FG,現(xiàn)在應(yīng)該清楚了為什么稱為壓力角,忽略滑動摩擦,一個齒輪作用于另一個齒輪的力總是形成一個與壓力角相同的角度。圖2.16和2.12的比較表明了漸開線齒輪強(qiáng)調(diào)滿足共軛齒輪傳動的基本原則,附帶的漸開線齒輪只是幾何形狀滿足當(dāng)齒輪旋轉(zhuǎn)時壓力角多產(chǎn)生這一原則,特別注意共軛漸開線齒輪傳動只能發(fā)生在兩基圓外面,從而摩擦傳動和皮帶傳動所提供的速度三角開相同。直齒輪的專用術(shù)語直齒輪的術(shù)語大部分可用于其它種類的齒輪。兩個相配合的齒輪的每個最初的圓柱直徑被稱為中徑,并且圓柱體的橫截面外形被稱為節(jié)圓,兩個節(jié)圓相切于節(jié)點(diǎn)。產(chǎn)生漸開線的圓稱為基圓。位于齒的頂部的圓稱為齒頂圓,同樣的,位于齒的根部的圓稱為齒根圓,在齒頂圓和齒根圓之間的重要的圓稱為分度圓,分度圓的參數(shù)是標(biāo)準(zhǔn)化了的。用在齒輪分度圓的模數(shù)作為基本參數(shù),m=p/,齒和齒輪的尺寸正比于模數(shù)m。齒頂是指由分度圓到齒頂圓的徑向距離,齒根是指由分度圓到齒根圓的徑向距離。相互嚙合的齒輪的齒頂和齒根之間的間隙是有差異的,此間隙的存在是為了防止兩齒輪相互嚙合引起偏心。周節(jié)p是指相鄰齒的相應(yīng)邊之間的距離,它是沿分度圓測量的。類似于周節(jié)的基節(jié)沿分度圓測量代替分度圓。很容易看出來基圓半徑等于分度圓半徑乘上壓力角的余弦,因?yàn)閷τ诮o定的角度,任一相對的弧和半徑之比為常數(shù),它確實(shí)是基圓節(jié)距等于圓的節(jié)距乘上壓力角的余弦。壓力角是一確定的圓上法線和圓周速度相交點(diǎn)所在的角。在分度圓上的壓力角是標(biāo)準(zhǔn)化的,它通常是20(有時15)。中心線是指通過相互嚙合齒輪的中心線的那條線。中心距(沿中心線測量)等于小齒輪和大齒輪節(jié)圓半徑的和。齒厚是指齒的寬度,是沿著分度圓測量的這段距離稱之為齒厚。齒間寬是沿著分度圓測量相鄰齒相對邊之間的距離,齒厚加上齒間寬等于節(jié)距,齒側(cè)是齒間寬減去齒厚的距離。齒面寬是沿軸線上測量出齒的寬度。齒頂面是在節(jié)圓作用之外的齒的作用面,齒根面是在節(jié)圓之內(nèi)的作用面。齒根圓角是齒的根部處的圓角,工作深度是大齒輪齒頂高與其相嚙合的齒輪的齒頂高之和。為了正確嚙合,齒輪共同運(yùn)轉(zhuǎn)的準(zhǔn)則是:(a)具有相同的模數(shù);(b)有相同的壓力角;(c)有相同的齒頂高和相同的齒根高。最后的一條準(zhǔn)則只適用于標(biāo)準(zhǔn)齒輪。滾動軸承 滾動軸承包含了內(nèi)外尾圈,他由許多滾動元件分開,如滾珠,圓柱或圓錐滾子,或者滾針。滾珠軸承具有球狀滾動元件,他被保持在隔圈和保持架之間,棍子軸承主要由圓柱的,圓錐的,鼓形的磙子代替。球行的滾針軸承通常即設(shè)內(nèi)滾道也設(shè)保持架。滾針被外圈滾道上構(gòu)成整體的必須法點(diǎn)固定。 具有滾動軸承的滾道軸,不具有滑動粘著效應(yīng),低啟動扭矩和速度摩擦力,不像滑動軸承,摩擦系數(shù)遂在和和速度變化不大,滾動接觸軸承優(yōu)于滑動軸承的有點(diǎn)是他的啟動扭矩,普通滑動軸承從靜止開始實(shí)際上伴隨著金屬的接觸,和滾動元件之間的摩擦具有高摩擦系數(shù),在軸承帶恒定負(fù)荷啟動的情況下,這個特點(diǎn)相當(dāng)重要。
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