喜歡這套資料就充值下載吧。資源目錄里展示的都可在線預(yù)覽哦。下載后都有，請放心下載，文件全都包含在內(nèi)，有疑問咨詢QQ:1064457796
花生脫殼機的設(shè)計
摘要
本文首先花生脫殼機的脫殼原理，應(yīng)用現(xiàn)狀及現(xiàn)在市場上應(yīng)用的個脫殼機存在的問題進行調(diào)研分析，針對其問題進行了分析。根據(jù)設(shè)計要求及花生脫殼機的功能要求，確定了花生脫殼機的總體方案的設(shè)計，以封閉式滾筒脫殼機為研究對象，對脫殼機的關(guān)鍵脫殼部件、進料機構(gòu)、振動篩分選機構(gòu)和偏心輪機構(gòu)等部分進行詳細設(shè)計與三維建模分析。最后對本次設(shè)計心得體會與成果進行的總結(jié)。
關(guān)鍵詞：花生脫殼機、滾筒、半籠柵、結(jié)構(gòu)設(shè)計
目錄
摘要 1
目錄 2
1.緒論 4
1.1本課題研究的背景及意義 4
1.2 花生脫殼機的脫殼原理 4
1.3 花生脫殼機的應(yīng)用現(xiàn)狀與未來發(fā)展趨勢 5
1.3.1 花生脫殼機的應(yīng)用現(xiàn)狀介紹 5
1.3.2 未來發(fā)展趨勢 6
2. 花生脫殼機的整體結(jié)構(gòu)方案與工作原理 8
2.1本設(shè)計中的脫殼原理 8
2.2花生脫殼機的總體結(jié)構(gòu) 8
2.3 殼仁分離裝置 10
3. 花生脫殼機關(guān)鍵部件的結(jié)構(gòu)設(shè)計 11
3.1脫殼部件的設(shè)計 11
3.1.1滾筒半徑及轉(zhuǎn)速初定 11
3.1.2脫殼機所需功率計算與電機選型 13
3.1.3傳動裝置的傳動參數(shù)計算 14
3.1.4電機與脫殼轉(zhuǎn)子軸之間的V帶傳動設(shè)計 15
3.1.5滾筒材料的選擇 19
3.2轉(zhuǎn)軸的設(shè)計與校核 19
3.2.1初步確定軸的最小直徑 19
3.2.2擬定軸上零件的裝配方案與尺寸確定 20
3.2.3.主軸的強度校核 21
3.2.4軸承的校核 23
3.3比重分選篩動力系統(tǒng)設(shè)計 24
3.3.1比重分選篩裝置設(shè)計 24
3.3.2偏心輪轉(zhuǎn)軸設(shè)計 25
3.3.3偏心軸的V帶傳動設(shè)計 26
4. 花生脫殼機的各部件設(shè)計與三維建模 27
4.1 關(guān)鍵組件的設(shè)計與三維建模 27
4.1.1半柵籠 27
4.1.2風(fēng)扇組件設(shè)計 28
4.1.3箱體 28
4.1.4料斗 29
4.1.5振動篩的箱體 30
4.1.5篩網(wǎng) 31
4.1.6機架 31
4.2 脫殼機的三維建模與裝置檢查 32
圖4.10 脫殼機三維模型的主視圖 33
5.結(jié)論 34
致謝 35
參考文獻 36
1.緒論
1.1本課題研究的背景及意義
花生是人們生活中重要的實物及食用油品的來源，花生需求量在增大，花生種植面積與產(chǎn)量也在增加。因此，這就要求對花生種植、收割及脫殼等機械裝置的發(fā)展與應(yīng)用滿足其生產(chǎn)需求。目前，采用機械自動脫殼設(shè)備的生產(chǎn)效率是遠遠高于人工手動效率，且降低農(nóng)民的工作強度，節(jié)省時間和生產(chǎn)成本[1]。
針對花生脫殼的質(zhì)量要求，需要綜合分析其各影響因素，如脫殼設(shè)備的轉(zhuǎn)動特性、脫殼工藝流程和脫殼加工對象的形狀、干燥情況等物理特性。常用的脫殼設(shè)備主要由脫殼機外殼、轉(zhuǎn)子、篩分等部件，這里需要綜合考慮外形結(jié)構(gòu)形式、關(guān)鍵零部件材質(zhì)、幾何特征參數(shù)、各部件之間的配合參數(shù)以及動力學(xué)運動參數(shù)。目前，市場上出現(xiàn)的花生脫殼機設(shè)備種類型號繁多，結(jié)構(gòu)功能也是也有特點，但是多數(shù)的花生脫殼機還是或多或少的存在一些缺點，或不完善，比如脫殼性能不穩(wěn)定、花生的破損率高等問題 [2]。
因此，本課題的研究目的是針對現(xiàn)有花生脫殼設(shè)備的應(yīng)用與發(fā)展現(xiàn)狀，分析各類脫殼機的脫殼原理、結(jié)構(gòu)組成及存在的問題進行優(yōu)化改進。
1.2 花生脫殼機的脫殼原理
花生脫殼機的工作原理就是通過高速旋轉(zhuǎn)的沖擊機體將花生仁與殼進行分離，在保證花生仁的完整性前提下，對花生仁進行篩分清。因此，采用最優(yōu)的脫殼原理是解決脫殼機現(xiàn)存問題。花生脫殼機的種類非常多，常用的脫殼機工作原理主要有以下幾種：
（1）打擊法
打擊法脫殼（離心式脫殼）是利用高速回轉(zhuǎn)的轉(zhuǎn)子部件給花生莢果強大的離心力作用，使得花生殼受到劇烈沖擊力破裂，花生殼受撞擊變形裂開，花生仁就從花生殼裂縫中脫落出來。離心式脫殼機脫殼方法對花生莢果的含水率有嚴格要求，且與脫殼轉(zhuǎn)子的轉(zhuǎn)速及加料量有密切聯(lián)系。
2）擠壓法
擠壓法脫殼工作原理的利用具有一定量間距的兩個轉(zhuǎn)速相同，方向相反的滾筒擠壓花生莢果，在擠壓力作用下花生被壓破裂與花生仁分離達到脫殼。通過擠壓原理脫殼的影響因素主要是兩滾筒之間的間隙值，能否使莢果被夾住并順利進入間隙達到擠壓的目的。
（3）碾搓法
碾搓法脫殼的工作原理是利用一個固定磨片與一個運動磨片使得花生莢果在兩者之間通過，在定圓盤和擁有轉(zhuǎn)動離心力的動圓盤之間碾搓，受到碾搓作用撕碎花生殼，從而實現(xiàn)花生殼與花生仁分離的目的，如圖1.1所示。影響脫殼機效果的因素也是花生莢果含水率、圓盤表面幾何結(jié)構(gòu)和其轉(zhuǎn)速等。
圖1.1碾搓法的工作原理
（4）剪切法
剪切法脫殼的工作原理是固定刀架與高速運轉(zhuǎn)刀板之間的相對運動將花生莢果切裂打開，實現(xiàn)花生仁與殼分離。為增加脫殼機的使用范圍，可根據(jù)花生莢果顆粒大小來調(diào)節(jié)刀架與刀板之間的間距，這種脫殼原理設(shè)備脫殼時與花生莢果接觸面小，漏剝重剝的出現(xiàn)比較小，因此，脫凈率相對較高。
1.3 花生脫殼機的應(yīng)用現(xiàn)狀與未來發(fā)展趨勢
1.3.1 花生脫殼機的應(yīng)用現(xiàn)狀介紹
目前，市場上的花生脫殼設(shè)備的種類繁多，在設(shè)備結(jié)構(gòu)組成、型號特點、功率大小等都是各具特點的，其采用的脫殼原理也是從單一到多種方式相結(jié)合的，基本上可以滿足各類花生脫殼加工、分選、復(fù)脫、分級等多種工序。
圖1.2所示為國內(nèi)成熟的兩款花生脫殼機。
目前，已在使用的花生脫殼機是各具特色的花生脫殼機，均是20世紀七八十年代引進、改造出來的產(chǎn)品，也就是具有一定脫殼效率，基本上能夠滿足勞動者對花生脫殼要求。對于小型家用脫殼機械多數(shù)的應(yīng)用于廣大農(nóng)村，脫殼機的脫殼效率較低，性能不是非常穩(wěn)定度，存在花生仁的損傷率大等問題。
（A）
（B）
圖1.3典型的花生脫殼機
對于那些要求比較的花生種子脫殼，其對破損率有嚴格要求，現(xiàn)有的脫殼機械也比較難滿足的。因此，針對現(xiàn)有花生脫殼設(shè)備的應(yīng)用與發(fā)展現(xiàn)狀，分析各類脫殼機的脫殼原理、結(jié)構(gòu)組成及存在的問題進行優(yōu)化改進。
1.3.2 未來發(fā)展趨勢
進入21世紀，隨著工業(yè)技術(shù)的飛速發(fā)展，我國花生生產(chǎn)加工機械化進入了新發(fā)展階段，為花生種植、收獲、加工、等機械化提供發(fā)展條件?；ㄉ摎C設(shè)備的研發(fā)與優(yōu)化重點集中在如下方面：
1）提高花生脫殼機械的通用性和兼容性，使用過程中僅僅變換脫殼機主要的執(zhí)行工作部件，就能滿足不能種類、不同粒度的物料的脫殼加工。
2）即通過對脫殼機的脫殼原理與關(guān)鍵部件的結(jié)構(gòu)、材料應(yīng)用進行重點攻關(guān)，提高機械脫殼率，降低破損率。
3） 提高脫殼設(shè)備的脫殼自動控制與自動化方向。通過機電一體化技術(shù)的應(yīng)用，開發(fā)設(shè)計出具有自動喂料、自動定位脫殼裝置，保證均勻喂料，實現(xiàn)機組自動化操作，提高作業(yè)精確性和作業(yè)速度。
2. 花生脫殼機的整體結(jié)構(gòu)方案與工作原理
2.1本設(shè)計中的脫殼原理
經(jīng)過對市場上現(xiàn)有的花生脫殼機進行調(diào)研分析，確定本次課題設(shè)計一款封閉木質(zhì)滾筒式花生剝殼機。即剝殼部件是在一個圓筒上鑲上若干齒形筋條，下部與半圓形型柵條式凹板配合，且滾筒外徑與半籠柵圓周進行控制在30-38mm，如圖1-1所示。
工作時，花生莢果在重力作用下，進入到脫殼機構(gòu)箱體內(nèi)，在高速回轉(zhuǎn)滾筒的離心力作用下由進口向出口端運動，此時，花生莢果在滾筒和柵條凹板的揉搓、擠壓、摩擦綜合效應(yīng)下，完成強制裂縫、脫殼。
圖 2-1 脫殼原理示意圖
在脫殼時，與柵條縫尺寸相同或小于柵條間隙的花生顆粒就直接從柵縫中分離出來，這就造成一次性脫殼率較低。為保證脫殼率要求，可以通過更換柵條凹板部件來改變滾筒與凹板之間的間隙，或者將半籠型凹板的柵條間隙，針對與普通花生顆粒，柵條間隙去9mm-13mm。另外，脫殼機需要配置花生仁和未脫果分離的裝置。
2.2花生脫殼機的總體結(jié)構(gòu)
根據(jù)前面的剝殼原理可知，花生脫殼的過程是：物料首先從進料斗進入到剝殼箱之內(nèi)，經(jīng)過滾筒及柵格，從下箱的出口流出，為實現(xiàn)花生殼與仁的分離，需要設(shè)置比重分選篩裝置，最后花生仁在重力作用下進入到收集斗中。
滾筒式脫殼機構(gòu)是本設(shè)計中最為重要的機構(gòu)，我將在本文第三章中重點進行設(shè)計。因花生進度到剝殼箱內(nèi)之后，花生經(jīng)過高速回轉(zhuǎn)的滾筒與柵條之間的撞擊和擠壓作用，花生莢果被強制裂縫、剝殼，然后經(jīng)過位于剝殼箱底部的柵格，柵格直接設(shè)計成一個側(cè)面封閉的半籠柵，它是通過螺栓固定安裝在剝殼箱的下半箱之內(nèi)。
如果花生在下落過程中沒有與輥筒外圓周的齒輪發(fā)生接觸碰撞，或者是發(fā)生接觸了花生僅出現(xiàn)裂紋但是沒有完全殼、仁分離，此時，這部分花生將直接落入到半籠柵格上，在下一個轉(zhuǎn)子旋轉(zhuǎn)周期上輥筒旋轉(zhuǎn)外徑與柵格頂部間的間距因不足以容納一個完整花生果，因此花生果將再次受到輥筒齒型的擠壓而被壓碎。
圖2-2 滾筒式破碎機結(jié)構(gòu)組成原理圖
如圖2.2所示，封閉式滾筒脫殼機主要由進料機構(gòu)、剝殼機構(gòu)、分選機構(gòu)和機架支承機構(gòu)等部分組成。脫殼機的驅(qū)動源采用一個電機提供動力，經(jīng)帶傳動道滾筒脫殼裝置；比重分選的篩分裝置采用偏心輪機構(gòu)，動力直接由滾筒主軸經(jīng)帶傳動到分選篩分裝置主軸。
為保證脫殼整機的各部件安裝要求，本機設(shè)計采用矩形鋼管型材焊接的機架，起到支承、定位、連接作用，驅(qū)動電機安裝在機架下部。
2.3 殼仁分離裝置
殼仁分離裝置的實現(xiàn)分離的基本原理是利用花生殼、花生仁的重量及受力面積的不同，重量稍重的不被風(fēng)吹走，而重量較輕的花生殼將被風(fēng)機吹來的氣流帶入到花生殼收集通道，用氣流對其進行分離。重量稍重的不被氣流吹走，直接下落到花生仁收集通道，落入比重分選篩上，然后比重分選篩運行。
3. 花生脫殼機關(guān)鍵部件的結(jié)構(gòu)設(shè)計
3.1脫殼部件的設(shè)計
3.1.1滾筒半徑及轉(zhuǎn)速初定
本磁設(shè)計的是封閉式滾筒式脫殼機構(gòu)，脫殼執(zhí)行裝置由一個圓筒型滾筒外部設(shè)置了齒輪打擊齒，下部與半圓形柵條凹板配合組成，如圖3.1所示。
1.打擊齒 2.半籠柵
圖3.1 脫殼裝置組成
為保證高速回轉(zhuǎn)的滾筒與半圓柵條的撞擊、擠壓、揉搓作用下實現(xiàn)對花生的強制脫殼，這里需要設(shè)置合理的間隙，進籠側(cè)入口的間隙值一般取30-50mm，出籠側(cè)出口的間隙一般取10-15mm。
滾筒的幾何形狀、尺寸及結(jié)構(gòu)形式需要與花生的尺寸箱匹配，同時轉(zhuǎn)子轉(zhuǎn)速和轉(zhuǎn)軸部件的邊界轉(zhuǎn)速需要避免出現(xiàn)頻率相近而使得脫殼機產(chǎn)生共振，造成脫殼設(shè)備產(chǎn)生附加振動及較大的噪音。
滾筒的半徑與轉(zhuǎn)速確定依據(jù)為：滾筒旋轉(zhuǎn)必須確保能將進入的花生殼撞碎，經(jīng)過查閱相關(guān)資料，當花生莢果與鋼性物體的相對速度約為3.5時，可以保證花生殼破碎而且可以保證花生仁的損壞率在98%以下。如圖3-2所示，花生下落點位置在之間，因此最小碰撞半徑為計算半徑：
整理得：
取半徑R=170mm，則由
因此本次設(shè)計的脫殼滾筒幾何尺寸與轉(zhuǎn)速初選為：R=170mm，n=395r/min
圖3.2 滾筒截面圖
確定滾筒圓周的齒輪的幾何參數(shù)，如圖3.3所示，經(jīng)過統(tǒng)計測量數(shù)據(jù)，花生莢果長為39.41mm，寬度尺寸為13.8mm，厚度尺寸為14.5mm。為保證滾筒在高速回轉(zhuǎn)中與半籠柵之間的能順利擠殼花生殼，且不損壞花生仁，這里滾筒齒輪的結(jié)合形狀如圖3.4所示，開口35mm，角度為60度。
圖3.3 花生外形參數(shù) 圖3.4 齒型槽幾何參數(shù)
3.1.2脫殼機所需功率計算與電機選型
根據(jù)功率計算公式：，需要先計算滾筒所需的功率；
滾筒在高速回轉(zhuǎn)過程中對花生做功包含兩部分，動能與勢能之和，
上式：：滾筒改變花生的動能；
：滾筒改變花生的勢能
上式中 ：花生果的初動能（J）；
花生果的末動能（J）；
花生果的初速度(m/s)；
花生果地末速度(m/s)；
這里設(shè)定花生脫殼機的額定單位脫殼產(chǎn)量為30kg/min，折合每秒產(chǎn)量為0.5kg/s?；ㄉ佑|滾筒齒槽板時的初速度設(shè)為1m/s，方向近似向下，當滾筒旋轉(zhuǎn)一定角度后，花生離開滾筒的速度擬定達到15m/s，方向向左，脫離齒槽板時相對初位置高度降低了170mm。
代入計算得到：P=67W
同時，需要計算滾筒與花生在柵格中擠壓所需要的能量，所需功率P遠小于500W。電機通過帶傳動到滾筒主軸，這里需要確定帶傳動與脫殼裝置之間的傳遞總效率。初設(shè)滾動軸承效率為、V帶傳動的效率為，則可以計算出總效率為
圖3.5 滾筒轉(zhuǎn)動示意圖（理論狀態(tài)下）
考慮到本脫殼機的風(fēng)扇及重力篩分裝置的偏心輪裝置的動力源都是利用主軸驅(qū)動電機，這里需要充分預(yù)留一定功力，因此這里初選電動機的功率為1.5kW。
根據(jù)前面計算所需的電機功率及滾筒的轉(zhuǎn)速，可選用的電機型號有兩種 ：Y90L-4型和Y100L-6型，他們參數(shù)詳細見下表。
表3-1 驅(qū)動電機的參數(shù)
方案號
電機型號
額定功率kw
同步轉(zhuǎn)速r/min
滿載轉(zhuǎn)速r/min
總傳動比 i
1
Y100L-6
1．5
1000
940
2.38
2
Y90L-4
1．5
1500
1400
3.65
比較上述兩款電機，方案2傳動比稍微大點，但是電機價格低，適合于家用機械設(shè)備。Y90L-4型電機的中心高H為90mm，外伸軸徑為24mm，軸的外伸長度為50mm。
3.1.3傳動裝置的傳動參數(shù)計算
滾筒式花生去殼機的滾筒轉(zhuǎn)速已確定為，這里直接選用V帶傳動，保證傳動結(jié)構(gòu)簡單，安裝方案，設(shè)備的制造成本低。下面來計算系統(tǒng)的傳動比：
滾筒軸的轉(zhuǎn)速：
滾筒軸轉(zhuǎn)速為：
傳動比：
軸的輸入功率：
軸的轉(zhuǎn)矩：
上式中： 為滾筒軸的轉(zhuǎn)矩(N.m)；
為滾筒軸的輸入功率(kw)；
3.1.4電機與脫殼轉(zhuǎn)子軸之間的V帶傳動設(shè)計
電機型號：Y90L-4
額定功率：1.5kw
電機轉(zhuǎn)速：
傳動比：=3.65
假設(shè)脫殼機的工作時間：t<10h/天
1.確定計算功率
式中 為計算功率（kw）；
為電機的額定功率kw；
為工作系數(shù)，由文獻[13]表14.1-12查得；
則
2.選擇V帶帶型：
根據(jù)、查文獻[13]，查帶型參數(shù)，確定帶型為A型；
3.確定帶輪基準直徑
查文獻[13]，確定帶傳動的主動輪基準直徑，取，
計算得到從動輪基準直徑為：
按文獻[13]將從動基準直徑圓整：
驗算傳動帶的速度情況：
因此，所選帶的速度合適。
4．確定帶傳動的中心距a和傳動帶的基準長度：
則
這里初取中心距：
查文獻[13]由表14.1－7選擇帶的基準長度
計算實際中心距a
5．驗算主動輪上的包角
計算主動輪包角合適：
上式中 為包角系數(shù)，??；
為長度系數(shù)，?。?
為單根V帶的基本額定功率（KW）；??；
為單根V帶的額定功率的增量（KW），；
代入數(shù)值，計算：
取z=2
7.計算預(yù)緊力
查文獻[13]表14.1－14得:：
8．計算作用在軸上的壓軸力
式中 ——帶的根數(shù)；
——單根帶的預(yù)緊力 N；
——主動輪的包角 ( °)；
代入數(shù)值計算得：
9.V帶輪的結(jié)構(gòu)尺寸計算及選用
帶輪材料選用HT200；
根據(jù)基準直徑的大小選用不同的帶輪類型，小徑帶輪采用實心式，大徑帶輪采用輪輻式，主要結(jié)構(gòu)尺寸如表3-2。
3-2電機與比重分選篩間傳動帶輪參數(shù)表 單位：mm
尺寸類型
小帶輪
大帶輪
90
330
基準寬度
30
30
基準線上槽深
3.75
3.75
基準線下槽深
19
19
槽間距e
15±0.3
15±0.3
第一槽對稱面至端面距離f
輪緣厚d
12
12
帶輪寬B
60
40
外徑
120
343
輪槽角
極限偏差
孔徑
25
25
輪轂長
50
42
80
輪輻厚
10
20
16
350
具體結(jié)構(gòu)設(shè)計見零件圖：
圖3.6 小帶輪三維 圖3.7 大帶輪三維
3.1.5滾筒材料的選擇
根據(jù)花生需要的力與花生脫殼機械轉(zhuǎn)速結(jié)合，減少花生莢果堆積過多時擠壓力變大將花生仁擠破致其損傷，套筒的形式還可以轉(zhuǎn)動，當花生莢果堆積或者有雜質(zhì)時，可以減少花生仁損傷和機器損傷。
采用木質(zhì)材料作為擊打部件還有硬度大的特點，可以使花生脫殼機轉(zhuǎn)速無需過大就能使花生殼破裂達到脫殼的目的；由于其表面較光滑，揉搓力并不明顯。橡膠表面粗糙度相對較高，對花生莢果的摩擦力較大，利于花生莢果脫殼。主要運用的是擊打、擠壓、碾搓的脫殼原理。
圖3.8 滾筒的三維
3.2轉(zhuǎn)軸的設(shè)計與校核
3.2.1初步確定軸的最小直徑
根據(jù)前面計算軸的轉(zhuǎn)速：
轉(zhuǎn)子軸的輸入功率
得
軸的轉(zhuǎn)矩：
上式中： 為滾筒軸的轉(zhuǎn)矩(N.m)；
為滾筒軸的輸入功率(kw)；
先按經(jīng)驗公式算出軸的最小直徑，選取軸的材料為45鋼，調(diào)質(zhì)處理。查機械設(shè)計手冊選取，得
得
為方便平鍵的設(shè)置，這里選確定軸最小直徑25mm。
圖3.9 轉(zhuǎn)軸結(jié)構(gòu)圖
3.2.2擬定軸上零件的裝配方案與尺寸確定
轉(zhuǎn)軸上各零部件裝配關(guān)系如圖3.10所示：
圖3.10 轉(zhuǎn)軸的裝配示意圖
（1） 軸直徑最小值取，長度30mm，保證V帶輪的軸向定位，1-2軸左端采用軸肩定位，右端采用擋圈加螺母鎖緊定位，擋圈只壓在帶輪上而不壓在軸端面；
（2） 第二段為軸承檔位，直徑，長度取為；第三段為滾筒安裝檔位，直徑，長度取為；
（3）選擇深溝球軸承 該軸承既可以承受徑向力，也可以承受一定的軸向力，選取深溝球軸承6206；滾動軸承與轉(zhuǎn)軸的軸向定位軸肩與軸承座來保證的，本設(shè)計中軸直徑尺寸公差為。
表3.2 軸承技術(shù)參數(shù)
（4）V帶輪與軸的周向定位采用平鍵聯(lián)接；
3.2.3.主軸的強度校核
(1)滾筒軸空間受力如圖3.11所示。
圖3.11 軸空間受力圖
(2)滾筒軸的水平面上的受力分析和彎矩如圖3.12所示。
圖3.12水平面受力圖
作出水平面內(nèi)的彎矩如圖3.13所示：
圖3.13 主軸水平面彎矩圖
(3)垂直平面內(nèi)的受力分析和彎矩如圖3.14。
圖3.14 垂直平面的受力分析
作出垂直平面內(nèi)的彎矩如圖3-12。
圖3.15 主軸垂直面彎矩圖
(4)合成彎矩如圖3-13。
圖3-13 合成彎矩圖
(5)校核軸的強度。
，
，，
，
由于>23.74MPa,故主軸合格。
3.2.4軸承的校核
滾筒轉(zhuǎn)軸的軸承選擇用深溝球軸承，型號6206；
由軸的校核可知：
，，，
徑向力
軸向力
，
，
取沖擊載荷系數(shù) ，
則
由于， 則按軸承2計算
顯然， ，故軸承壽命很充裕。
3.3比重分選篩動力系統(tǒng)設(shè)計
3.3.1比重分選篩裝置設(shè)計
本設(shè)計中采用了平面型振動篩，驅(qū)動方式采用偏心輪機構(gòu)直接與振動篩下部的橫梁接觸驅(qū)動，在重力作用下，振動篩向下復(fù)位，其結(jié)構(gòu)如圖3.14所示。
圖3.14 篩選裝置
本設(shè)計采用大型的平面篩，其與圓筒篩相比，其具有更大的有效篩理面積。通過帶傳動將滾筒軸上的動能傳遞到偏心輪軸，將回轉(zhuǎn)運動轉(zhuǎn)變成篩體的往復(fù)振動，實現(xiàn)平面篩在垂直方向上作往復(fù)運動的振動。
此花生脫殼機中所采用的是偏心輪機構(gòu)以作為比重分選篩的執(zhí)行機構(gòu)，篩箱水平全振幅等于偏心距的2倍。
圖3.15比重分選篩原理圖
要求偏心輪的偏心距與兩支點之間的距離之比小于1/10，則可利用均勻旋轉(zhuǎn)的偏心輪促使振動篩子上任何一點都按簡諧運動規(guī)律沿自己的軌跡運動。
3.3.2偏心輪轉(zhuǎn)軸設(shè)計
這里輸出動力的主動輪是滾筒轉(zhuǎn)軸，其轉(zhuǎn)速為；
從動軸偏心軸，初步確定其轉(zhuǎn)速為；
軸的輸入功率：
軸的輸入轉(zhuǎn)矩：
1.初步確定軸的最小直徑
選取軸材料為45鋼，調(diào)質(zhì)處理。計算軸的最小直徑，取，
這里取軸的最小徑為25mm。
圖3.16 偏心輪軸
2.擬定軸上零件的裝配方案
圖3.17 偏心軸裝配方案
3.3.3偏心軸的V帶傳動設(shè)計
對于滾筒轉(zhuǎn)軸與偏心軸之間的帶傳動設(shè)計，因前面已經(jīng)做 V帶傳動的設(shè)計，這里不做重復(fù)計算，盡在下表列出相關(guān)參數(shù)。
表3-7偏心軸與滾筒轉(zhuǎn)子軸間的V帶輪參數(shù) 單位：mm
尺寸類型
小帶輪
大帶輪
90
330
基準寬度
30
30
基準線上槽深
3.75
3.75
基準線下槽深
19
19
槽間距e
15±0.3
15±0.3
第一槽對稱面至端面距離f
輪緣厚d
12
12
帶輪寬B
60
40
外徑
120
343
輪槽角
極限偏差
孔徑
25
25
輪轂長
50
42
80
輪輻厚
10
20
16
350
4. 花生脫殼機的各部件設(shè)計與三維建模
4.1 關(guān)鍵組件的設(shè)計與三維建模
4.1.1半柵籠
半柵籠的主要作用是與滾筒配合，實現(xiàn)對進入料斗內(nèi)的花生擠壓、撞擊，同時，柵條可以對已被剝殼花生與未被剝殼花生進行分離，即“小個通過，大個不過”。半柵籠的柵條間隙控制在13mm，每個柵格間隙只能通過一?；ㄉ剩虼?，對于已被脫殼的花生可以穿過柵格，未被脫殼或已擠裂紋但沒有殼、仁分離花生莢果因為體積太大，無法通過柵格，將被阻擋在剝殼箱內(nèi)，繼續(xù)進行剝殼直到其外殼破碎。半籠柵的三維結(jié)構(gòu)如圖4.1所示。
圖4.1 半籠柵的三維
半籠柵兩側(cè)面通過兩塊擋板對兩端進行固定的，組成半圓柵籠，擋板材料為Q235，柵條材料選用20鋼。柵條采用截面圓棒料，長度為635mm，為了防銹處理，需要對半籠柵表面整體進行滲碳處理，熱處理硬度HRC56-62。半柵籠的柵條間隙控制在10mm，每個柵格間隙只能通過一粒已脫殼的花生仁，而未剝殼的剛不能通過，可以對半柵籠的安裝采用浮動安裝，降低花生仁的破碎率，半柵籠內(nèi)徑為。
4.1.2風(fēng)扇組件設(shè)計
風(fēng)扇的作用是提高風(fēng)能將花生殼與仁進行分離，因為花生殼、花生仁的重量不同，且花生殼的受力面積大，通過風(fēng)扇作用，可以將重量較輕的花生殼將被風(fēng)機吹來的氣流帶入到花生殼收集處，用氣流對其進行分離。重量稍重的不被氣流吹走，直接下落到花生仁收集通道，落入比重分選篩上，然后比重分選篩運行。
如圖4.2、4.3所示，風(fēng)扇組件由軸承座、帶輪、風(fēng)扇葉片及外罩組成。
圖4.2 風(fēng)扇轉(zhuǎn)子三維
圖4.3 風(fēng)扇外罩三維
4.1.3箱體
箱體構(gòu)成一個封閉的剝殼環(huán)境，它對滾筒轉(zhuǎn)子及半籠柵等構(gòu)起到支承。箱體尺寸直接根據(jù)滾筒轉(zhuǎn)軸部件的尺寸來決定的，如圖4.4所示，下箱體的三維模型圖，側(cè)面通過四個側(cè)耳與機架進行固定連接 。
為了便于脫殼機滾筒部件的安裝和拆卸，這里將箱體做成剖分式的，分為上箱蓋和下箱體兩部分組成，剖分面設(shè)置在轉(zhuǎn)軸所在的中心線所在平面。上箱蓋和下箱體采用四個螺栓聯(lián)接，用圓錐銷定位。箱體材料選用Q235，焊接而成。
圖4.4 下箱體的三維
4.1.4料斗
漏斗采用斜錐式漏斗，漏斗直接與上箱體焊接為一體，三維結(jié)構(gòu)如圖4.5所示。前面已估算當喂料速率在30kg/min 時，這樣可以保證留在脫殼箱體的花生莢果較，莢果進入箱體之內(nèi)的阻滯作用?。皇沟们v果與滾筒的擠壓得以充分脫殼，花生莢果與旋轉(zhuǎn)滾筒齒型槽的接觸機會多，脫殼效率也高。
如果進一步增加喂入量，則直接造成脫殼箱體內(nèi)的物料量增加，花生莢果之間的擠壓摩擦也增大，因脫殼室內(nèi)存留物料過多，花生仁、殼在阻礙作用下 ，不能及時排出脫殼室 ，導(dǎo)致果仁破碎率和損傷率增加 。
圖4.5 料斗三維
4.1.5振動篩的箱體
振動篩的箱體是振動篩分的框架部件，它與篩網(wǎng)配合，將篩選出的花生仁收集。箱體下部橫梁直接與偏心輪接觸，通過帶傳動將滾筒軸上的動能傳遞到偏心輪軸，將回轉(zhuǎn)運動轉(zhuǎn)變成篩體的往復(fù)振動，實現(xiàn)平面篩在垂直方向上作往復(fù)運動的振動。振動篩箱體與機架通過銷釘相聯(lián)，通過偏心輪與機架相聯(lián)從而產(chǎn)生比重分選篩的振動效果。箱體的材料選用Q235，板材焊接成型。具體結(jié)構(gòu)如圖4.6所示。
圖4.6 振動篩箱體
4.1.5篩網(wǎng)
本設(shè)計采用大型的平面篩，其與圓筒篩相比，其具有更大的有效篩理面積。通過帶傳動將滾筒軸上的動能傳遞到偏心輪軸，將回轉(zhuǎn)運動轉(zhuǎn)變成篩體的往復(fù)振動，實現(xiàn)平面篩在垂直方向上作往復(fù)運動的振動。
根據(jù)粒度的不同，篩面的材料和安裝方式也是存在差異的。針對花生仁粒度小于15 mm，篩面直接選擇中等硬度的篩面。軟質(zhì)篩網(wǎng)的安裝多采用張緊鉤式的，篩網(wǎng)的兩端固定有張緊鉤。
篩網(wǎng)的材料為鋼絲編織篩網(wǎng)，篩分效果最好，花生因自重較小故對它的損壞較小，使用壽命較長。篩網(wǎng)部件如圖4.7所示。
圖4.7 篩網(wǎng)
4.1.6機架
花生脫殼機的機架采用截面為50*50mm矩形鋼管焊接而成，機架的作用的支承與定位滾筒部件，連接箱體、料斗、偏心輪軸等部件的作用，并將電機安裝在機架里面，各部件的聯(lián)接采用普通螺栓聯(lián)接。如圖4.8所示。
圖4.8 脫殼機的機架三維
4.2 脫殼機的三維建模與裝置檢查
滾筒式花生脫殼機的三維裝配圖如圖4.9所示。
圖4.9 滾筒式花生脫殼機的三維裝配
花生脫殼機的設(shè)計采用自下而上的建模設(shè)計方案，首先根據(jù)脫殼產(chǎn)量初步確定滾筒直徑及長度，確定滾筒轉(zhuǎn)速，在此基礎(chǔ)上對各關(guān)鍵的轉(zhuǎn)軸部件、 半籠柵、箱體、機架和風(fēng)機等部件單獨建模設(shè)計，然后在對各組件裝配起來。
圖4.10為脫殼機三維模型的主視圖，將完成虛擬裝配的三維模型進行干涉檢查分析，平面剖切分析，分析各零部件中不合理結(jié)構(gòu)，通過干涉檢查發(fā)現(xiàn)各零部件尺寸不正確的地方。另外，也可以通過運動仿真分析，演示脫殼機各部件的動態(tài)過程。
圖4.10 脫殼機三維模型的主視圖
5.結(jié)論
本文首先花生脫殼機的脫殼原理，應(yīng)用現(xiàn)狀及現(xiàn)在市場上應(yīng)用的個脫殼機存在的問題進行調(diào)研分析，針對其問題進行了分析。根據(jù)設(shè)計要求及花生脫殼機的功能要求，確定了花生脫殼機的總體方案的設(shè)計，以封閉式滾筒脫殼機為研究對象，對脫殼機的關(guān)鍵脫殼部件、進料機構(gòu)、振動篩分選機構(gòu)和偏心輪機構(gòu)等部分進行詳細設(shè)計與三維建模分析。最后對本次設(shè)計心得體會與成果進行的總結(jié)。
在設(shè)計過程中，從分析課題，搜集相關(guān)材料，閱讀并綜述相關(guān)資料以及設(shè)計計算等過程有了清晰的思路。我通過查閱大量有關(guān)資料，與同學(xué)交流經(jīng)驗，向老師請教，使自己培養(yǎng)了我獨立工作的能力，樹立了對自己工作能力的信心，相信會對今后的學(xué)習(xí)工作生活有非常重要的影響。
致謝
在本論文完成的最后，我要衷心的感謝我的指導(dǎo)老師，感謝老師對我的悉心指導(dǎo)和幫助。感謝同組同學(xué)對我的論文提供的幫助。感謝這些年來父母對我的養(yǎng)育之恩，是他們?yōu)槲业慕】党砷L提供了良好的條件。
參考文獻
[5] 楊帥,鄒智慧.多自由度工業(yè)機器人運動控制系統(tǒng)的研究[J].制造業(yè)自動化,2013,
[1] 高學(xué)梅, 胡志超, 謝煥雄, 等. 打擊揉搓式花生脫殼機脫殼性能影響因素探析[J]. 花生學(xué)報, 2011, 40(3): 30~34.
[2] 朱立學(xué), 羅錫文, 劉少達. 軋輥-軋板式銀杏脫殼機的優(yōu)化設(shè)計與試驗[J]. 農(nóng)業(yè)工程學(xué)報, 2008, 24(8): 139~142.
[3] 吉平, 陳杰. 沙棘籽脫殼方法及裝置的試驗研究[J]. 農(nóng)業(yè)工程學(xué)報, 1999, 15(4): 258~263.
[4] 高夢祥, 郭康權(quán), 楊中平, 等. 玉米秸稈的力學(xué)特性試驗研究[J].農(nóng)業(yè)機械學(xué)報, 2003, 34(4): 47~49, 52.
[5] 王延耀, 張巖. 氣爆式花生脫殼性能的試驗研究[J]. 農(nóng)業(yè)工程學(xué)報, 1998, 14(1): 222~227.
[6] 國家發(fā)展和改革委員會. 花生剝殼機 試驗方法 (JB/T 5688.2― 2007)[S]. 北京: 機械工業(yè)出版
［1］ 高學(xué)梅， 胡志超， 謝煥雄， 等． 打擊揉搓式花生脫殼機脫殼性能影響因素探析［J］ ． 花生學(xué)報， 2011 ， 40(3 ) : 30 － 34．
［2］ 喻 杰， 包秀輝． 常用花生脫殼機的分析研究［J］ ． 農(nóng)業(yè)科技與裝備， 2009(1 ) : 114 － 115， 118．
［3］ 劉明國 ， 杜 鑫， 程獻麗， 等． 花生脫殼機械化對遼寧省花生產(chǎn)業(yè)的影響［J］ ． 農(nóng)機化研究， 2010， 32(10) : 222 － 225．
［4］ 李建東， 尚書旗， 李西振， 等． 我國花生脫殼機械研究應(yīng)用現(xiàn)狀及進展［J］ ． 花生學(xué)報， 2006， 35(4) : 23 － 27．
［5］ 李建東． 花生脫殼裝置的試驗研究［D］ ． 青島: 青島農(nóng)業(yè)大學(xué)，2007: 3 － 5．
［6］ 李心平， 馬福麗， 高連興． 花生脫殼裝置的結(jié)構(gòu)技術(shù)剖析［J］ ． 農(nóng)機化研究， 2010(3 ) : 18 － 20．
［7］ 謝煥雄， 彭寶良， 張會娟， 等． 我國花生脫殼技術(shù)與設(shè)備概況及發(fā)展［J］ ． 江蘇農(nóng)業(yè)科學(xué)， 2010(6) : 581 － 582．
［8］ 劉紅力． 花生脫殼特性與損傷機理研究［D］ ． 沈陽 : 沈陽農(nóng)業(yè)大學(xué)， 2007: 18 － 22．
［9］ 楊國新， 王定標． 基于 SolidWorks 的機械零部件虛擬裝配體設(shè)計技術(shù)［J］ ． 煤礦機械， 2007，
Int J Adv Manuf Technol (2005) 25: 551–559
DOI 10.1007/s00170-003-1843-3
ORIGINAL ARTICLE
S.H. Masood · B. Abbas · E. Shayan · A. Kara
An investigation into design and manufacturing of mechanical conveyors systems
for food processing
Received: 29 March 2003 / Accepted: 21 June 2003 / Published online: 23 June 2004
? Springer-Verlag London Limited 2004
Abstract This paper presents the results of a research investi-
gation undertaken to develop methodologies and techniques that
will reduce the cost and time of the design, manufacturing and
assembly of mechanical conveyor systems used in the food and
beverage industry. The improved methodology for design and
production of conveyor components is based on the minimisa-
tion of materials, parts and costs, using the rules of design for
manufacture and design for assembly. Results obtained on a test
conveyor system verify the bene?ts of using the improved tech-
niques. The overall material cost was reduced by 19% and the
overall assembly cost was reduced by 20% compared to conven-
tional methods.
Keywords Assembly · Cost reduction · Design · DFA · DFM ·
Mechanical conveyor
1 Introduction
Conveyor systems used in the food and beverage industry are
highly automated custom made structures consisting of a large
number of parts and designed to carry products such as food
cartons, drink bottles and cans in fast production and assembly
lines. Most of the processing and packaging of food and drink in-
volve continuous operations where cartons, bottles or cans are re-
quired to move at a controlled speed for ?lling or assembly oper-
ations. Their operations require highly ef?cient and reliable me-
chanical conveyors, which range from overhead types to ?oor-
mounted types of chain, roller or belt driven conveyor systems.
In recent years, immense pressure from clients for low cost
but ef?cient mechanical conveyor systems has pushed con-
veyor manufacturers to review their current design and assembly
methods and look at an alternative means to manufacture more
economical and reliable conveyors for their clients. At present,
S.H. Masood (u) · B. Abbas · E. Shayan · A. Kara
Industrial Research Institute Swinburne,
Swinburne University of Technology,
Hawthorn, Melbourne 3122, Australia
E-mail: smasood@swin.edu.au
most material handling devices, both hardware and software, are
highly specialised, in?exible and costly to con?gure, install and
maintain [1]. Conveyors are ?xed in terms of their locations and
the conveyor belts according to their synchronised speeds, mak-
ing any changeover of the conveyor system very dif?cult and ex-
pensive. In today’s radically changing industrial markets, there is
a need to implement a new manufacturing strategy, a new system
operational concept and a new system control software and hard-
ware development concept, that can be applied to the design of
a new generation of open, ?exible material handling systems [2].
Ho and Ranky [3] proposed a new modular and recon?gurable
2D and 3D conveyor system, which encompasses an open re-
con?gurable software architecture based on the CIM-OSA (open
system architecture) model. It is noted that the research in the
area of improvement of conveyor systems used in beverage in-
dustry is very limited. Most of the published research is directed
towards improving the operations of conveyor systems and inte-
gration of system to highly sophisticated software and hardware.
This paper presents a research investigation aimed at im-
proving the current techniques and practices used in the de-
sign, manufacturing and assembly of ?oor mounted type chain
driven mechanical conveyors in order to reduce the manufactur-
ing lead time and cost for such conveyors. Applying the con-
cept of concurrent engineering and the principles of design for
manufacturing and design for assembly [4, 5], several critical
conveyor parts were investigated for their functionality, material
suitability, strength criterion, cost and ease of assembly in the
overall conveyor system. The critical parts were modi?ed and
redesigned with new shape and geometry, and some with new
materials. The improved design methods and the functionality of
new conveyor parts were veri?ed and tested on a new test con-
veyor system designed, manufactured and assembled using the
new improved parts.
2 Design for manufacturing and assembly (DFMA)
In recent years, research in the area of design for manufacturing
and assembly has become very useful for industries that are con-
552
sidering improving their facilities and manufacturing methodol-
ogy. However, there has not been enough work done in the area
of design for conveyor components, especially related to the is-
sue of increasing numbers of drawing data and re-engineering
of the process of conveyor design based on traditional methods.
·
·
·
·
·
Emphasise standardisation
Use the simplest possible operations
Use operations of known capability
Minimise setups and interventions
Undertake engineering changes in batches
A vast amount of papers have been published that have investi-
gated issues related to DFMA and applied to various methodolo-
gies to achieve results that proved economical, ef?cient and cost
effective for the companies under investigation.
The main classi?cations of DFMA knowledge can be iden-
ti?ed as (1) General guidelines, (2) Company-speci?c best prac-
tice or (3) Process and or resource-speci?c constraints. General
guidelines refer to generally applicable rules-of-thumb, relat-
ing to a manufacturing domain of which the designer should
be aware. The following list has been compiled for DFM
guidelines [6].
These design guidelines should be thought of as “optimal
suggestions”. They typically will result in a high-quality, low-
cost, and manufacturable design. Occasionally compromises
must be made, of course. In these cases, if a guideline goes
against a marketing or performance requirement, the next best
alternative should be selected [7].
Company-speci?c best practice refers to the in-house design
rules a company develops, usually over a long period of time, and
which the designer is expected to adhere to. These design rules
are identi?ed by the company as contributing to improved quality
and ef?ciency by recognising the overall relationships between
·
·
·
·
·
·
·
·
·
·
·
·
·
·
·
·
·
Design for a minimum number of parts
Develop a modular design
Minimise part variations
Design parts to be multifunctional
Design parts for multiuse
Design parts for ease of fabrication
Avoid separate fasteners
Maximise compliance: design for ease of assembly
Minimise handling: design for handling presentation
Evaluate assembly methods
Eliminate adjustments
Avoid ?exible components: they are dif?cult to handle
Use parts of known capability
Allow for maximum intolerance of parts
Use known and proven vendors and suppliers
Use parts at derated values with no marginal overstress
Minimise subassemblies
particular processes and design decisions. Companies use such
guidelines as part of the training given to designers of products
requiring signi?cant amounts of manual assembly or mainte-
nance. Note that most of the methodologies are good at either
being quick and easy to start or being more formal and quanti-
tative. For example, guidelines by Boothroyd and Dewhurst [8]
on DFA are considered as being quantitative and systematic.
Whereas the DFM guidelines, which are merely rules of thumb
derived from experienced professionals, are more qualitative and
less formal [9].
3 Conventional conveyor system design
Design and manufacturing of conveyor systems is a very com-
plex and time-consuming process. As every conveyor system is
a custom-made product, each project varies from every other
project in terms of size, product and layout. The system design
Fig. 1. Layout of conveyor sys-
tem for labelling plasic bottles
553
is based on client requirements and product speci?cations. More-
over, the system layout has to ?t in the space provided by the
company. The process of designing a layout for a conveyor sys-
tem involve revisions and could take from days to months or in
some instances years. One with the minimum cost and maximum
client suitability is most likely to get approval.
Figure 1 shows a schematic layout of a typical conveyor
system installed in a production line used for labelling of
plastic bottles. Different sections of the conveyor system are
identi?ed by speci?c technical names, which are commonly
used in similar industrial application. The “singlizer” sec-
tion enables the product to form into one lane from multiple
lanes. The “slowdown table” reduces the speed of product
once it exits from ?ller, labeller, etc. The “mass ?ow” sec-
tion is used to keep up with high-speed process, e.g., ?ller,
labeller, etc. The “transfer table” transfers the direction of prod-
uct ?ow. The purpose of these different conveyor sections is
thus to control the product ?ow through different processing
machines.
A typical mechanical conveyor system used in food and bev-
erage applications consists of over two hundred mechanical and
electrical parts depending on the size of the system. Some of
the common but essential components that could be standard-
ised and accumulated into families of the conveyor system are
side frames, spacer bars, end plates, cover plates, inside bend
plates, outside bend plates, bend tracks and shafts (drive, tail and
slave). The size and quantity of these parts vary according to the
length of conveyor sections and number of tracks correspond-
ing to the width and types of chains required. The problems and
shortcomings in the current design, manufacturing and assembly
of mechanical conveyors are varied, but include:
4 Areas of improvement
In order to identify the areas of cost reduction in material and
labour, a cost analysis of all main conveyor parts was conducted
to estimate the percentage of cost of each part in relation to the
total cost of all such parts. The purpose of this analysis was to
identify the critical parts, which are mainly responsible for in-
creasing the cost of the conveyor and thereby investigate means
for reducing the cost of such parts.
Table 1 shows the cost analysis of a 50-section conveyor sys-
tem. The analysis reveals that 12 out of 15 parts constitute 79%
of the total material cost of the conveyor system, where further
improvements in design to reduce the cost is possible. Out of
these, seven parts were identi?ed as critical parts (shown by an
asterisk in Table 1) constituting maximum number of compo-
nents in quantity and comprising over 71% of overall material
cost. Among these, three components (leg set, side frame and
support channel) were found to account for 50% of the total
conveyor material cost. A detailed analysis of each of these 12
parts was carried out considering the principles of concurrent en-
gineering, design for manufacture and design for assembly, and
a new improved design was developed for each case [10]. De-
tails of design improvement of some selected major component
are presented below.
5 Redesign of leg set assembly
In a conveyor system, the legs are mounted on the side frame to
keep the entire conveyor system off the ?oor. The existing design
of conveyor legs work, but they are costly to manufacture, they
·
·
·
·
Over design of some parts
High cost of some components
Long hours involved in assembly/maintenance
Use of non-standard parts
have stability problems, and cause delays in deliveries. The delay
is usually caused by some of the parts not arriving from over-
seas suppliers on time. The most critical speci?cations required
for the conveyor legs are:
Table 1. Conveyor critical parts based on parts cost analysis
Product description
Leg set?
Side frame?
Support channel?
Bend tracks
Rt. roller shaft?
Tail shaft
Spacer bar?
Support wear strip?
Support side wear strip?
End plate
Cover plate
Bend plates
Torque arm bracket
Slot cover
Inside bend plate
Qty
68
80
400
8
139
39
135
400
132
39
39
8
18
97
8
Material used
Plastic leg + SS tube
2.5 mm SS
C channel SS
Plastic
20 dia. SS shaft
35 dia. Stainless steel
50X50X6 SS
40 × 10 mm plastic
Plastic
2.5 mm/SS
1.6 mm S/S
2.5 mm/SS
6 mm S/S plate
Stainless steel
2.5 mm/SS
Cost (%)
20.22
16.07
15.00
14.36
6.70
6.27
5.43
5.36
3.01
1.88
1.57
1.29
1.21
0.97
0.66
Improvement possible (Yes/No)
Yes
Yes
Yes
No
Yes
No
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Total
?Critical
parts
100.00
554
·
·
·
·
Strength to carry conveyor load
Stability
Ease of assembly
Ease of ?exibility (for adjusting height)
1 and part 3 in Fig. 2) was not rigid enough. The connections
for these parts are only a single 6 mm bolt. At times, when the
conveyor system was carrying full product loads, it was observed
that the conveyor legs were unstable and caused mechanical vi-
bration. One of the main reasons for this was due to a single bolt
Figure 2 indicates all the parts for the existing design of
the conveyor leg. The indicated numbers are the part numbers
described in Table 2, which also shows a breakdown of cost an-
alysis complete with the labour time required to assemble a com-
plete set of legs. The existing leg setup consists of plastic leg
brackets ordered from overseas, stainless steel leg tubes, which
are cut into speci?ed sizes, leg tube plastic adjustments, which
are clipped onto the leg tube at the bottom as shown in Fig. 2.
Lugs, which are cut in square sizes, drilled and welded to the leg
tube to bolt the angle cross bracing and backing plate to support
leg brackets bolts. The # of parts in Table 2 signi?es the number
of components in each part number and the quantity is the con-
sumption of each part in the leg design. Companies have used
this design for many years but one of the common complaints
reported by the clients was of the instability of legs.
From an initial investigation, it became clear that the connec-
tion between the stainless steel tube and plastic legs bracket (part
Fig. 2. Existing leg design assembly with part
names shown in Table 1
Table 2. Cost analysis for old leg design assembly
connection at each end of the lugs in part 3 and part 7. The sta-
bility of the conveyor is considered critical matter and requires
recti?cation immediately to satisfy customer expectations.
Considering the problems of the existing conveyor leg de-
sign and the client’s preferences, a new design for the conveyor
leg was developed. Generally the stability and the strength of
the legs were considered as the primary criteria for improve-
ment in the new design proposal but other considerations were
the simplicity of design, minimisation of overseas parts and ease
of assembly at the point of commissioning. Figure 3 shows, the
new design of the conveyor’s leg assembly, and Table 3 gives a
description and the cost of each part.
Figure 3 shows that the new design consists of only ?ve main
parts for the conveyor’s leg compared to eight main parts in the
old design. In the old design, the plastic leg bracket, the leg
tube plastic adjustment and the leg tube were the most expensive
items accounting for 72% of the cost of leg assembly. In the new
Part no.
1
5, 6
4
7
2
3
8
Part description
Plastic leg bracket
Leg tube plastic adjustment
Lug
Angle cross bracing
Backing plate
Leg tube
Bolts
# of parts
2
4
2
1
2
2
6
Qty
2
2
2
1
2
2
6
Cost
$ 30.00
$ 28.00
$ 4.00
$ 5.00
$ 4.00
$ 25.00
$ 3.00
Source
Overseas
Overseas
In-house
In-house
In-house
In-house
In-house
Total assembly cost (welding)
$ 15.00
In-house
Total
19
17
$ 114.00
555
Fig. 3. New design for leg assembly with part
names in Table 3
Table 3. Cost analysis for new design leg assembly
Part no.
1
3
4
5
2
Part description
Stainless steel angle (50 × 50 × 3 mm)
Leg plastic adjustment
Cross brassing
Bolts
Backing plate
# of parts
2
2
1
8
2
Qty
2
2
1
4
2
Cost
$ 24.00
$ 10.00
$ 7.00
$ 4.00
$ 4.00
Source
In-house
Overseas
In-house
In-house
In-house
Total assembly cost
$ 10.00
In-house
Total
design, those parts have been replaced by a stainless steel angle
and a new plastic leg adjustment reducing the cost of leg assem-
bly by almost 50%. Thus the total numbers of parts in the leg
have been reduced from 19 to 15 and the total cost per leg setup
15
·
·
·
·
11
Size of side frame (depth)
Strength of the material
Ease for assembly
Ease for manufacturing
$ 59.00
has been reduced by $ 55 in the new design.
The new conveyor leg design, when tested, was found to be
more secure and stable than the old design. The elimination of
part number 1 and 5 from old conveyor design has made the new
design more stable and rigid. In addition, the width of the cross
bracing has also been increased with two bolts mount instead of
one in old design. This has provided the entire conveyor leg setup
an additional strength.
6 Redesign of the side frames
The side frame is the primary support of a conveyor system
that provides physical strength to conveyors and almost all the
parts are mounted on it. The side frame is also expected to have
a rigid strength to provide support to all the loads carried on
the conveyor. It also accommodates all the associated conveyor
components for the assembly. The critical considerations of side
frame design are:
Figure 4 shows the side frame dimension and parameters.
The side frame used in existing design appears to be of rea-
sonable depth in size (dimension H in Fig. 4). From the initial
investigation, it was found that the distance between spacer bar
holes and return shaft (dimensions G and F in Fig. 4) could be
reduced, as there was some unnecessary gap between those two
components. The important point to check before rede?ning the
design parameters was to make sure that after bringing those two
closer, the return chains would not catch the spacer bar while the
conveyor is running. The model of the new side frame design was
drawn on CAD to ensure all the speci?cations are sound and the
parts are placed in the position to check the clearances and the
?ts. Using the principle of design for manufacturing the new side
frame design was made symmetrical so that it applies to all types
of side frames. This change is expected to reduce the size of side
frame signi?cantly for all sizes of chains.
Table 4 shows a comparison of dimensions in the old design
and the new design of side frames for the same chain type. It
556
Fig. 4. Side frame dimensions
Table 4. New and old side frame dimension parameters
Old design
Chain type
3.25 LF/SS
STR/LBP/MAG
A
31
B
92
C
71
D
196
E
65
F
105
G
211
H
241
I
136
J
58
K
85
L
196
TAB
22
83
62
187
56
96
202
232
127
New design
Chain type
3.25 LF/SS
STR/LBP/MAG/TAB
A
31
B
100
C
73
D
173
E
67
F
107
G
167
H
199
I
92
J
58
K
85
L
152
is noted that the overall size (depth) of the conveyor has been
reduced from 241 mm to 199 mm (dimension H), which gives
a saving of 42 mm of stainless steel on every side frame manu-
factured. Thus, from a stainless steel sheet 1500 × 3000 mm, the
old design parameter