王 征,王吉奎,2,唐永飛,羅勇軍
帶式殘膜揉搓打包機(jī)設(shè)計(jì)與試驗(yàn)
王 征1,王吉奎1,2※,唐永飛1,羅勇軍1
(1. 石河子大學(xué)機(jī)械電氣工程學(xué)院,石河子 832003; 2. 農(nóng)業(yè)農(nóng)村部西北農(nóng)業(yè)裝備重點(diǎn)實(shí)驗(yàn)室,石河子 832003)
針對國內(nèi)現(xiàn)有殘膜回收機(jī)械作業(yè)時(shí)不能打包,回收的殘膜松散,導(dǎo)致殘膜轉(zhuǎn)運(yùn)和存放不方便、易隨風(fēng)飄散造成二次污染等問題,研究設(shè)計(jì)了一種帶式殘膜揉搓打包機(jī)。該打包機(jī)主要由揉搓機(jī)構(gòu)、浮動式喂入機(jī)構(gòu)、傳動系統(tǒng)和液壓系統(tǒng)等部分組成。該揉搓機(jī)構(gòu)是帶式殘膜揉搓打包機(jī)的核心部件,在張緊機(jī)構(gòu)和浮動式喂入機(jī)構(gòu)輔助下,將回收的殘膜揉搓打包。通過對主要工作部件的設(shè)計(jì),確定了揉搓機(jī)構(gòu)和浮動式喂入機(jī)構(gòu)的結(jié)構(gòu)尺寸參數(shù),并對殘膜包的形成過程進(jìn)行分析,確定了影響打包質(zhì)量的主要因素為打包室方位角和打包帶表面形態(tài)。田間試驗(yàn)表明:在打包帶適度張緊的條件下,打包室方位角為-5.0°~2.5°,打包帶表面為波紋面,打包帶線速度為2.0 m/s時(shí),殘膜成包率為100%,殘膜包密度在88.5~92.1 kg/m3之間;在回收殘膜含雜相同的情況下,殘膜包密度與打包帶線速度有關(guān),打包帶線速度越大,殘膜包密度越大,但打包帶線速度超過2.5 m/s以后,殘膜包密度增加趨勢減緩。帶式殘膜揉搓打包機(jī)結(jié)構(gòu)簡單、使用方便、滿足殘膜打包技術(shù)的要求,研究結(jié)果對新型殘膜打包機(jī)的研制提供參考。
農(nóng)業(yè)機(jī)械;設(shè)計(jì);殘膜;打包機(jī);揉搓機(jī)構(gòu);浮動式喂入機(jī)構(gòu)
中國使用鋪膜種植技術(shù)已有近40 a時(shí)間,鋪膜種植面積和地膜使用量均居世界第一,但使用后的地膜一直沒能及時(shí)有效回收,常年在田間積累,給農(nóng)業(yè)生態(tài)環(huán)境造成嚴(yán)重的“白色污染”[1-5]。機(jī)械化回收地膜是解決農(nóng)田地膜污染的有效手段,目前已有多種類型殘膜回收機(jī),部分殘膜回收機(jī)已達(dá)到較高的殘膜回收率[6-10]。然而,現(xiàn)有機(jī)型回收的殘膜堆集松散、占用空間大、給后續(xù)殘膜裝卸、拉運(yùn)和存放造成不便,且松散的殘膜易隨風(fēng)飄散,造成二次污染[11-15]。若將殘膜及時(shí)打包,則回收的殘膜包裹密實(shí)、體積小、且不易松散,可為回收殘膜的后續(xù)處理帶來較大便利[16-21]。因此,在作業(yè)過程中對殘膜邊回收邊打包,有助于殘膜污染的綜合治理,是機(jī)械化回收殘膜的發(fā)展方向。
國外使用的地膜厚度較大,殘膜強(qiáng)度較高,回收時(shí)大多采用簡單纏繞的方式將殘膜打成膜輥[22-24]。國內(nèi)郭笑歡等研制了全膜雙壟溝廢膜撿拾打捆機(jī),該機(jī)采用鋼輥打包(捆)裝置將殘膜打包[25];張海春等在4JLM-1800(A)型殘膜回收機(jī)的基礎(chǔ)上加裝鋼輥打包(捆)裝置,研制成棉田地膜回收打包一體機(jī)[26];張愛民等研究了一種能夠?qū)埬ず透缫黄鸹厥詹⒋蚶Φ拿尢餁埐鐝U膜收集打捆機(jī)[27];赫鵬亮等研究設(shè)計(jì)了一種殘膜液壓打包成型系統(tǒng)[17];新疆農(nóng)墾科學(xué)院機(jī)械裝備研究所研制了一款CMJY-1500型農(nóng)田殘膜撿拾打包聯(lián)合作業(yè)機(jī),可同時(shí)完成殘膜撿拾、清理與壓縮打包作業(yè)[6]。
現(xiàn)有殘膜打包機(jī)借鑒已有秸稈或牧草打包(捆)技術(shù),存在機(jī)具結(jié)構(gòu)復(fù)雜、造價(jià)高、與現(xiàn)有殘膜回收機(jī)配套性差等問題。針對國內(nèi)殘膜回收打包作業(yè)要求,本文利用殘膜易揉搓成輥這一特性,設(shè)計(jì)了一種帶式殘膜揉搓打包機(jī),分析了殘膜包形成過程,并進(jìn)行了田間性能試驗(yàn)。
帶式殘膜揉搓打包機(jī)由揉搓機(jī)構(gòu)、浮動式喂入機(jī)構(gòu)、傳動系統(tǒng)、連接板、側(cè)板和液壓油缸組成,其結(jié)構(gòu)示意圖如圖1所示。其中揉搓機(jī)構(gòu)由前后2組打包帶、支撐輥、張緊機(jī)構(gòu)和側(cè)板組成,2組打包帶分別繞在對應(yīng)的上支撐輥、下支撐輥和張緊輥上。張緊機(jī)構(gòu)將打包帶張緊后,在2個(gè)打包帶之間形成一個(gè)V型槽,該V型槽即是打包室。打包室上端開口寬度大,為打包機(jī)進(jìn)料口,下端開口寬度小(作業(yè)狀態(tài)),為打包機(jī)出料口。浮動式喂入機(jī)構(gòu)主要由喂入輥、U型支撐架、帶滑槽座軸承和壓緊彈簧組成,喂入輥壓在與上支撐輥相接觸的后打包帶上側(cè)。液壓油缸設(shè)在前、后兩側(cè)側(cè)板之間。
1.拉桿 2.前打包帶 3.上支撐輥 4.傳動系統(tǒng) 5.連接板 6.喂入輥 7.U型支撐架 8.壓板 9.螺桿 10.壓緊彈簧 11.帶滑槽座軸承 12.后打包帶 13.液壓油缸 14.張緊輥 15.張緊支架 16.張緊裝置 17.側(cè)板 18.打包室 19.下支撐輥 20.支撐桿 21.擋板
作業(yè)時(shí),在傳動系統(tǒng)帶動下,前后打包帶繞上、下支撐輥和張緊輥逆時(shí)針轉(zhuǎn)動,喂入輥在后打包帶摩擦力作用下順時(shí)針轉(zhuǎn)動。回收的殘膜落到喂入輥或后打包帶上側(cè),隨著后打包帶和喂入輥的轉(zhuǎn)動,殘膜被夾持在喂入輥和后打包帶之間,由打包機(jī)進(jìn)料口進(jìn)入打包室,沿后打包帶下落到打包室底部。在工作狀態(tài)下,打包機(jī)出料口開口寬度較小,殘膜被擋在打包室底部,在重力作用下夾在2個(gè)打包帶之間。由于打包室兩側(cè)打包帶運(yùn)動方向相反,在摩擦作用下,前側(cè)打包帶帶動殘膜向上運(yùn)動,后側(cè)打包帶帶動殘膜向下運(yùn)動,殘膜受到兩側(cè)打包帶的揉搓作用,并旋轉(zhuǎn)形成圓柱形殘膜包芯。隨著打包作業(yè)的進(jìn)行,喂入打包室的殘膜不斷纏繞在包芯上,包芯直徑不斷增大,最終形成殘膜包。在此過程中,殘膜包直徑的增大使打包帶的張緊度變大,從而使打包帶對殘膜包的擠壓揉搓作用增強(qiáng),殘膜包的密度也隨之增大。當(dāng)殘膜包的直徑達(dá)到設(shè)定值時(shí),打包帶停止轉(zhuǎn)動,通過操作液壓系統(tǒng),使打包機(jī)出料口張開,在重力作用下,殘膜包從打包室內(nèi)掉落,完成一次打包。
帶式殘膜揉搓打包機(jī)主要技術(shù)參數(shù)如表1所示。
表1 帶式殘膜揉搓打包機(jī)主要技術(shù)參數(shù)
揉搓機(jī)構(gòu)是帶式殘膜揉搓打包機(jī)的核心部件,作業(yè)時(shí),進(jìn)入打包室的殘膜在揉搓機(jī)構(gòu)作用下形成殘膜包。該機(jī)構(gòu)由前打包帶、后打包帶、上支撐輥、下支撐輥、側(cè)板和張緊機(jī)構(gòu)組成,張緊機(jī)構(gòu)上有張緊輥。為方便與現(xiàn)有殘膜回收機(jī)配套和殘膜包的搬運(yùn),打包機(jī)形成的最大殘膜包直徑=0.5 m。
2.1.1 打包室結(jié)構(gòu)參數(shù)的確定
打包室是形成殘膜包的空間,作業(yè)過程中,殘膜進(jìn)入打包室后在兩側(cè)打包帶的作用下旋轉(zhuǎn),形成圓柱狀包芯。包芯在打包帶的作用下繼續(xù)旋轉(zhuǎn),由于殘膜具有粘附性,隨后進(jìn)入打包室的殘膜不斷纏繞在旋轉(zhuǎn)包芯上,形成殘膜包。因此,包芯的形成是實(shí)現(xiàn)揉搓打包的關(guān)鍵環(huán)節(jié),而殘膜的受力情況對包芯的形成有直接影響。
開始作業(yè)時(shí),殘膜由進(jìn)料口進(jìn)入V型打包室并堆積在其底部,此時(shí)喂入打包室的殘膜質(zhì)量與體積較小,兩側(cè)打包帶形變可以忽略不計(jì),殘膜在打包室底部受力如圖2所示。
根據(jù)圖2,殘膜在水平和豎直方向的受力為
由式(1)可得打包帶對殘膜的壓力為
殘膜受到的轉(zhuǎn)動力矩為
式中為殘膜受到的轉(zhuǎn)動力矩,N/m;為殘膜包芯至打包帶的距離,m。
將式(2)代入式(3)可得:
殘膜受到的轉(zhuǎn)動力矩越大,堆積在打包室底部的殘膜越容易轉(zhuǎn)動形成殘膜包芯。由式(4)可知,殘膜受到的轉(zhuǎn)動力矩與打包室方位角、打包室夾角以及打包帶表面形態(tài)有關(guān)。由(4)式分別對和求偏導(dǎo)數(shù)。通過分析可知當(dāng)其他參數(shù)一定時(shí),力矩隨和的減小而增大,且的變化對力矩值影響最大。因此,為增大力矩,首先考慮減小打包室方位角。為方便實(shí)際操作,選取打包室方位角=0°(通過橫向轉(zhuǎn)動打包機(jī)即可改變打包室方位角的大?。?,即打包室內(nèi)前打包帶呈豎直狀態(tài)。
當(dāng)打包室方位角=0°時(shí),由(4)式對求偏導(dǎo)數(shù),通過分析可知轉(zhuǎn)動力矩隨摩擦系數(shù)值增大而增大。故可通過改變打包帶表面形態(tài)來增大力矩。
1.前打包帶 2.上支撐輥 3.張緊輥 4.后打包帶 5.下支撐輥 6.殘膜
注:為水平方向;為豎直方向;1為前打包帶對殘膜的支持力,N;2為后打包帶對殘膜的支持力,N;1為前打包帶與殘膜間的摩擦力,N;2為后打包帶與殘膜間的摩擦力,N;為打包室方位角,(°);為打包室夾角,(°);為殘膜的重力,N;1為打包室上端前后打包帶間隙;2為打包室底部前后打包帶間隙;為后打包帶與水平方向的夾角,(°);為打包帶線速度,m?s-1。
1.Front balling belt 2.Upper supporting roller 3. Tensioning roller 4.Back balling belt 5. Lower supporting roller 6.Residual film
Note:is the horizontal direction;is the vertical direction;1is the supporting force of the front balling belt to the residual film, N;2is the supporting force of the back balling belt to the residual film, N;1is the friction force between the front balling belt and the residual film, N;2is the friction force between the back balling belt and the residual film, N;is the azimuth of the balling room, (°);is the angle of the balling room, (°);is the gravity of the residual film, N;1is the gap between the front and back of the upper end of the balling room;2is the gap between the front and back of the bottom of the balling room r;is the angle between the back balling belt and the horizontal direction, (°) ;is the linear speed of the balling belt, m?s-1.
圖2 殘膜在打包室底部的受力示意圖
Fig.2 Schematic diagram of residual film force at the bottom of the baling room
由于殘膜包芯的密實(shí)度與打包帶對包芯的壓力有關(guān)。由式(2)可知,打包帶對殘膜的壓力隨打包室方位角、打包室夾角的減小而增大。因此,為增大殘膜包芯的密實(shí)度,打包室方位角和打包室夾角的取值應(yīng)較小。在打包室方位角確定的情況下,打包室夾角的取值與打包機(jī)進(jìn)料口寬度大小有關(guān)。為防止殘膜在喂入過程中堵塞打包機(jī)進(jìn)料口,結(jié)合殘膜物料層的厚度,取進(jìn)料口寬度1=150 mm(打包室上端前、后打包帶間隙),則打包室夾角=15°。為防止殘膜從打包室底部掉落和前后打包帶磨損,作業(yè)狀態(tài)下打包機(jī)出料口寬度2=2 mm(打包室底部前、后打包帶間隙)。
為防止落在后打包帶上的殘膜掉落,后打包帶與水平方向的夾角應(yīng)小于殘膜與打包帶表面的摩擦角,通過試驗(yàn)殘膜與光面打包帶間的摩擦角在35°~45°之間,殘膜與波紋面打包帶的摩擦角在40°~50°之間??紤]到實(shí)際作業(yè)過程中殘膜會受到氣流作用力的影響,結(jié)合試驗(yàn),取后打包帶與水平方向的夾角=25°。
2.1.2 張緊機(jī)構(gòu)
張緊機(jī)構(gòu)的作用是使打包帶保持一定的張緊度,一方面防止打包帶打滑,另一方面使殘膜包持續(xù)受壓,保證殘膜包的密實(shí)度。本設(shè)計(jì)采用彈性張緊機(jī)構(gòu),該機(jī)構(gòu)由張緊輥和設(shè)在張緊輥兩側(cè)的張緊輥支架、張緊彈簧、擋板、銷軸、導(dǎo)桿和張緊螺母等組成,其結(jié)構(gòu)如圖3所示。張緊輥支架一端鉸接在打包機(jī)側(cè)板下端,另一端通過帶座球面軸承聯(lián)接在張緊輥軸端,張緊彈簧設(shè)在張緊支架的中部,通過調(diào)整張緊螺母位置來調(diào)節(jié)彈簧的壓縮量,進(jìn)而調(diào)節(jié)打包帶的張緊度。
1.銷子 2.擋板 3.導(dǎo)桿 4.張緊彈簧 5.張緊螺母 6.耳板 7.張緊輥 8.張緊支架 9.銷軸
打包帶在上支撐輥與打包帶間的摩擦力作用下轉(zhuǎn)動,該摩擦力大小與打包帶的張緊度有關(guān),因此,作業(yè)前張緊彈簧應(yīng)有一定的預(yù)壓縮量,使打包帶適度張緊,確保上支撐輥能帶動打包帶轉(zhuǎn)動。隨著打包作業(yè)的進(jìn)行,殘膜包直徑逐漸增大,打包帶受殘膜包的擠壓而變形,導(dǎo)致打包帶對殘膜包的包角增大,打包室兩側(cè)的打包帶長度增加,從而使張緊輥向打包室靠攏,隨之帶動張緊支架壓縮彈簧。經(jīng)試驗(yàn)分析,形成直徑=500 mm的圓柱形殘膜包,打包室內(nèi)前、后打包帶的長度變形量各約為200 mm,張緊彈簧的長度依據(jù)打包前、后張緊支架的擺動量和彈簧的安裝位置確定。彈簧的彈簧系數(shù)越大,打包帶的張緊度越大,打包帶作用于殘膜包的壓力就越大,形成的殘膜包越密實(shí)。但打包帶受到的張緊力越大,作業(yè)中打包帶受到的磨損越大,影響打包帶的使用壽命。根據(jù)打包機(jī)整體結(jié)構(gòu)尺寸和田間試驗(yàn)效果,本文設(shè)計(jì)選用碳素彈簧鋼絲Ⅰ類C級彈簧[28],自由長度為250 mm,中徑為25 mm,線直徑為5 mm,彈簧總?cè)?shù)為25圈,有效圈數(shù)為20圈,當(dāng)彈簧壓縮量為20~35 mm時(shí),作業(yè)過程中打包帶未出現(xiàn)打滑現(xiàn)象,機(jī)具作業(yè)效果較好。
一般情況下,殘膜回收分為起膜、收膜和脫膜3個(gè)過程,其中脫膜是將收起的殘膜從殘膜回收裝置上脫取下來。試驗(yàn)中發(fā)現(xiàn),脫下的殘膜受脫膜裝置和氣流等因素的影響,下落位置不確定,殘膜有可能在進(jìn)料口發(fā)生堵塞。另外,若殘膜被連片收起且殘膜片較長,當(dāng)殘膜前段進(jìn)入打包室并繞在殘膜包上而殘膜片后段仍在殘膜回收裝置上未被脫下來時(shí),由于打包帶線速度較快,進(jìn)入打包機(jī)的殘膜會拉拽未脫下的殘膜,在反向作用力下,殘膜包直徑較小時(shí)會被拽出打包室,影響打包效果。浮動式喂入機(jī)構(gòu)的作用是使脫下的殘膜強(qiáng)制有序喂入打包室,確保打包作業(yè)可靠。
因后打包帶轉(zhuǎn)動時(shí)將殘膜帶入打包室,故將浮動式喂入機(jī)構(gòu)設(shè)在與上支撐輥相接觸的后打包帶上側(cè)。該機(jī)構(gòu)主要由喂入輥、U型支撐架、壓緊彈簧、帶滑槽座的軸承和壓板組成,其結(jié)構(gòu)如圖4所示。U型支撐架設(shè)在打包機(jī)兩側(cè)連接板上,喂入輥軸端通過帶滑槽座軸承安裝在U型支撐架內(nèi),軸承座上側(cè)有壓緊彈簧,壓板設(shè)在壓緊彈簧上端。在壓緊彈簧和重力作用下,喂入輥緊貼在后打包帶上。上支撐輥為主動輥,轉(zhuǎn)動時(shí)帶動后打包帶運(yùn)動,進(jìn)而帶動喂入輥轉(zhuǎn)動,喂入輥轉(zhuǎn)動可在后打包帶上側(cè)上下浮動。
1.喂入輥 2.U型支撐架 3.螺桿 4.壓板 5.壓緊彈簧 6.帶滑槽座軸承
殘膜夾在打包帶與喂入輥之間進(jìn)入打包室,故殘膜喂入速度與打包帶線速度相等。因回收的殘膜下落位置不確定,殘膜可能掉落在進(jìn)料口前打包帶上,隨著前打包帶的轉(zhuǎn)動,殘膜夾在前打包帶與擋板之間,導(dǎo)致殘膜不能順利喂入打包室,造成堵塞。為此,可增大喂入輥的直徑,使其在豎直方向遮住打包室入口,掉落在進(jìn)料口處的殘膜落在喂入輥上,并隨著喂入輥的轉(zhuǎn)動及時(shí)進(jìn)入打包室。參照打包機(jī)進(jìn)料口寬度和打包帶寬度,取喂入輥直徑=330 mm,喂入輥長度=2 000 mm。
殘膜包芯形成后,包芯只有在打包帶的揉搓作用下轉(zhuǎn)動時(shí),喂入打包室的殘膜才能不斷纏繞在殘膜包芯上,最終形成殘膜包。通過殘膜包形成過程分析,確定影響殘膜包轉(zhuǎn)動的條件。開始作業(yè)時(shí),殘膜包芯從打包室底部開始形成,初始直徑小,殘膜包芯的回轉(zhuǎn)中心靠近打包室下側(cè),隨著殘膜包芯直徑逐漸增大,殘膜包芯回轉(zhuǎn)中心由打包室底部向上移動,當(dāng)包芯的中心與打包室中心重合時(shí),殘膜包直徑達(dá)到最大值。若打包帶勻速運(yùn)動(一般情況下,配套殘膜回收機(jī)的作業(yè)速度為6.0 km/h,考慮到殘膜有一定彈性,確定打包帶線速度為殘膜回收機(jī)作業(yè)速度的1.2倍),打包室方位角=0°,殘膜包為圓柱形且不考慮打包帶變形時(shí),殘膜包芯的受力分析如圖5所示。
由受力分析可知,前、后打包帶對殘膜包芯的支持力3、4和殘膜包的重力相對殘膜包芯回轉(zhuǎn)中心點(diǎn)的力矩均為0。若殘膜包芯在打包帶表面做純滾動,打包帶與殘膜包芯間的摩擦力為靜摩擦力;若殘膜包芯在打包帶表面有滑動,則打包帶與殘膜包芯間的摩擦力為滑動摩擦力。因滑動摩擦力小于最大靜摩擦力,結(jié)合殘膜包實(shí)際受力情況,取殘膜包芯與打包帶間的摩擦力為滑動摩擦力。
1.前打包帶 2.后打包帶 3.殘膜包芯
注:3為前打包帶對殘膜包芯的支持力,N;4為后打包帶對殘膜包芯的支持力,N;3為前打包帶對殘膜包芯的滾動阻力,N;4為后打包帶對殘膜包芯的滾動阻力,N;為殘膜包芯回轉(zhuǎn)中心;1′為前打包帶與殘膜包芯間的滑動摩擦力,N;2′為后打包帶與殘膜包芯間的滑動摩擦力,N。
1. Front balling belt 2. Back balling belt 3. Residual film core
Note:3is the supporting force of the front balling belt to the residual film core, N;4is the supporting force of the back balling belt to the residual film core, N;3is the rolling resistance of the front balling belt to the residual film core, N;4is the rolling resistance of the back balling belt to the residual film core, N;is the rotation center of the residual film core;1′ is the sliding friction force of the front balling belt to the residual film core, N;2′ is the sliding friction force of the back balling belt to the residual film core, N.
圖5 殘膜包芯受力示意圖
Fig. 5 Stress diagram of residual film core
由受力分析得殘膜包芯受到的轉(zhuǎn)動力矩1為
由殘膜包芯在水平和豎直方向上受力分析可得:
由式(6)可得打包室內(nèi)兩側(cè)打包帶對殘膜包芯的壓力為
將式(7)代入式(5)得殘膜包芯受到的轉(zhuǎn)動力矩:
因殘膜包芯與打包帶間的滑動摩擦系數(shù)大于滾動阻力系數(shù)[29],即1。由式(8)可知,在前后打包帶的揉搓作用下殘膜包芯受到的轉(zhuǎn)動力矩1﹥0,即殘膜包芯可以在打包帶的作用下旋轉(zhuǎn)。由此可知在打包室方位角=0°,殘膜包芯受到的轉(zhuǎn)動力矩1﹥0時(shí),可以實(shí)現(xiàn)殘膜揉搓打包作業(yè)。
另外,由于殘膜柔軟,殘膜包芯受壓易變形,處于V型打包室的殘膜包芯不可能是圓柱形(近似楔形),殘膜包芯在打包帶上的滾動阻力增大,使殘膜包轉(zhuǎn)動力矩減小,影響殘膜包芯轉(zhuǎn)動。為確保殘膜包芯轉(zhuǎn)動,需增大殘膜包芯的轉(zhuǎn)動力矩,分析式(8)可知,在打包室方位角一定時(shí),改變打包帶的表面形態(tài)可以增大力矩1,提高打包作業(yè)可靠性。
于2019年10月在新疆石河子市143團(tuán)收獲后的棉田進(jìn)行帶式殘膜揉搓打包機(jī)田間作業(yè)性能試驗(yàn),該打包機(jī)與夾指鏈?zhǔn)綒埬せ厥諜C(jī)[12]配套使用。試驗(yàn)棉田為機(jī)采棉的種植模式(660 mm(寬)+100 mm(窄)),地面較為平整,滴灌帶已回收,土壤松軟,地表土壤含水率為11.23%,單次作業(yè)6行(1膜6行種植模式),地膜的厚度為0.008 mm,幅寬為2 050 mm,秸稈高度在700~900 mm,棉株密度為4.5~5.5萬株/hm2??紤]到機(jī)具作業(yè)效率和實(shí)際經(jīng)濟(jì)效益,機(jī)組的作業(yè)速度為6.0 km/h,配套動力由約翰迪爾904拖拉機(jī)提供。試驗(yàn)場景如圖6所示。
圖6 田間試驗(yàn)
受田間試驗(yàn)環(huán)境和時(shí)間的限制,本試驗(yàn)采用單因素試驗(yàn)方法。根據(jù)前文分析和預(yù)試驗(yàn)結(jié)果,選取打包室方位角、打包帶表面形態(tài)和打包帶線速度為試驗(yàn)因素,殘膜成包率和殘膜包密度為試驗(yàn)指標(biāo)。試驗(yàn)過程參考《GB/T 14290-1993 圓草捆打捆機(jī)試驗(yàn)方法》進(jìn)行[30]。
打包帶的工作表面分為光面和波紋面,材質(zhì)為PVC,其與殘膜間的摩擦系數(shù)分別為0.78和1.1;打包室方位角的取值范圍為?5°~5°;打包帶線速度取值范圍為1.0~3.0 m/s(通過更換傳動鏈輪,改變打包機(jī)的傳動比實(shí)現(xiàn)),適度張緊打包帶,使支撐輥能帶動打包帶轉(zhuǎn)動。依據(jù)前期試驗(yàn)結(jié)果,試驗(yàn)時(shí)固定其中2個(gè)因素,改變第3個(gè)因素的取值水平,每個(gè)水平連續(xù)打包5個(gè),采用精密電子秤測其質(zhì)量,采用米尺測其長度和直徑,結(jié)果取平均值。
殘膜成包率由下式計(jì)算:
式中c為殘膜成包率,%;c為每個(gè)水平內(nèi)累計(jì)形成殘膜包數(shù);a為每個(gè)水平內(nèi)累計(jì)散包數(shù)。
殘膜包的密度由下式計(jì)算:
式中為殘膜包的密度,kg/m3;為殘膜包的長度,m;為殘膜包的直徑,m。為殘膜包的質(zhì)量,kg。
根據(jù)預(yù)試驗(yàn),殘膜包直徑越大,殘膜包越密實(shí)。對于不規(guī)則的圓柱形殘膜包,殘膜包兩端較小,對試驗(yàn)結(jié)果影響較小,因此將其向殘膜包中部折疊,分別取殘膜包直徑最大處和處理后的殘膜包長度作為密度試驗(yàn)值。
打包帶線速度為2 m/s、打包室方位角為0°時(shí),分別采用光面打包帶和波紋打包帶面,試驗(yàn)得到殘膜包10個(gè),散包0個(gè),殘膜成包率為100%;更換打包帶前后殘膜包的密度變化不大,在88.5~91.2 kg/m3之間,殘膜包密度試驗(yàn)結(jié)果如表2所示。
打包帶線速度為2 m/s、分別采用光面打包帶和波紋面打包帶、改變打包室方位角,當(dāng)打包室方位角在?5°~2.5°測試時(shí),得到殘膜包40個(gè),散包0個(gè),殘膜成包率為100%;當(dāng)打包室方位角大于2.5°時(shí),出現(xiàn)散包以及不打包現(xiàn)象。這是由于打包室方位角增大,殘膜所受的轉(zhuǎn)動力矩減小,導(dǎo)致作業(yè)時(shí)出現(xiàn)散包或者不打包;殘膜包的密度變化范圍在89.2~92.1 kg/m3之間,殘膜成包率及殘膜包密度試驗(yàn)結(jié)果如表3所示。
打包室方位角為0°、分別采用光面打包帶和波紋面打包帶、改變打包帶線速度,試驗(yàn)得到殘膜包50個(gè),散包0個(gè),殘膜成包率為100%。在其他因素不變的情況下,殘膜包密度隨打包帶線速度的增大而增大;當(dāng)線速度大于2.5 m/s后,殘膜包密度增加趨勢減緩。殘膜包密度試驗(yàn)結(jié)果如表4所示。
由試驗(yàn)結(jié)果可知,影響殘膜成包率的主要因素是打包室方位角,在此試驗(yàn)的條件下,當(dāng)打包室方位角在?5.0°~2.5°時(shí),成包率為100%。在打包帶初始張緊度一定的情況下,殘膜包的密度與打包帶的線速度有關(guān),線速度越大,殘膜包密度越大,但增大到一定值后增幅減小。田間試驗(yàn)表明:當(dāng)機(jī)具作業(yè)速度為6.0 km/h、打包室方位角=0°、打包帶線速度為2 m/s、采用波紋面打包帶時(shí),帶式殘膜揉搓打包機(jī)的殘膜成包率為100%,殘膜包密度在88.5~92.1 kg/m3之間,滿足打包機(jī)的田間作業(yè)性能要求。機(jī)具在田間連續(xù)作業(yè)過程中性能良好,浮動式喂入機(jī)構(gòu)可確保殘膜有序喂入打包室,未出現(xiàn)不打包現(xiàn)象。張緊機(jī)構(gòu)可保證殘膜包的密實(shí)度,并減少打包帶的磨損,各部件功能與作業(yè)效果均達(dá)到了設(shè)計(jì)的預(yù)期。
因田間情況比較復(fù)雜,測試時(shí)受風(fēng)力作用的影響,樣機(jī)工作過程中有少量殘膜飄掛在脫膜裝置和打包機(jī)外殼上,導(dǎo)致殘膜不能喂入打包機(jī),影響了殘膜的打包效果。本次試驗(yàn)只在現(xiàn)有的結(jié)構(gòu)參數(shù)下對樣機(jī)進(jìn)行了性能驗(yàn)證試驗(yàn),未深入探究打包機(jī)在不同結(jié)構(gòu)與作業(yè)參數(shù)組合下的作業(yè)效果,因此在后續(xù)的研究中還需進(jìn)行打包機(jī)結(jié)構(gòu)與作業(yè)參數(shù)的優(yōu)化試驗(yàn),進(jìn)一步提高帶式殘膜揉搓打包機(jī)及整機(jī)的作業(yè)效果。
1)在打包帶張緊、前后打包帶線速度相同的情況下,影響帶式殘膜揉搓打包機(jī)成包率的主要因素是打包室方位角,其次是打包帶表面形態(tài)。為保證試驗(yàn)結(jié)果可靠,打包室方位角為0°,打包帶選用波紋面打包帶。
2)殘膜包密度與打包帶的張緊度、打包室夾角和打包帶的線速度有關(guān),打包帶的張緊度越大、打包室夾角越小、打包帶線速度越大,則殘膜包密度越大。
3)田間試驗(yàn)表明,當(dāng)機(jī)具作業(yè)速度為6.0 km/h、打包室方位角為0°、打包帶線速度為2 m/s、采用波紋面打包帶時(shí),帶式殘膜揉搓打包機(jī)的殘膜成包率為100%,形成的殘膜包密度在88.5~92.1 kg/m3之間。
帶式殘膜揉搓打包機(jī)與現(xiàn)有殘膜回收機(jī)配套使用,在邊收膜邊打包的作業(yè)模式下,機(jī)具各部件運(yùn)轉(zhuǎn)良好,工作平穩(wěn),未發(fā)生堵塞、纏繞問題,殘膜打包效果良好,滿足對回收殘膜打包的田間作業(yè)要求。
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Design and test of the belt-type residual film rubbing and baling machine
Wang Zheng1, Wang Jikui1,2※, Tang Yongfei1, Luo Yongjun1
(1.832003,;2.832003,)
There are some problems existing in the domestic residual film recycling machinery, such as unable to bale, recovered film was loose, which leads to inconvenient transportation and storage, and easy to drift with the wind, resulting in secondary pollution and so on. In order to solve these problems, the belt-type residual film rubbing and baling machine was designed. The machine mainly consisted of rubbing mechanism, floating feeding mechanism, transmission system and hydraulic system, etc. The rubbing mechanism mainly consisted of front and back baling belts, support rollers, side plates and tensioning mechanism, etc. The baling belts rotated counterclockwise around the upper and lower support rollers, and the tension roller under the driving of the transmission system. The floating feeding mechanism mainly consisted of feeding roller, U-shaped support frame, bearing with sliding seat, and compression spring, etc. It was fixed to the upper end of the connecting plate, and the feeding roller rotated clockwise under the frictional force of the back baling belt. Through the design of the rubbing mechanism and the force analysis of the residual film, the structural dimension parameters of the baling room were determined, which contained the azimuth of the baling room was 0°, the angle of the baling room was 15°, the gap between the front and back of the upper end of the baling room was 15 mm, the gap between the front and back of the bottom of the baling roomwas 2 mm, the angle between the back baling belt and the horizontal direction was 25°, and the baling belt used PVC conveyor belt. The function of tension mechanism was to make the baling belt keep a certain degree of tension, so as to prevent the belt from slipping, keep the residual film bale baling under continuous pressure, and ensure the compactness of the residual film bale. Through the mechanical analysis of the formation of the residual film bale, the mechanical equation of the residual film core in the baling room was obtained, and then the rotational torque equation of the residual film core was derived. Finally, the field test of the baling machine was carried out. The results showed that the main factors affecting the baling quality were the azimuth of the baling room and the surface morphology of baling belt. The filed test showed that under the conditions of moderate tension of the baling belt, the azimuth angle of the baling room was -5° to 2.5°, the surface of balling belt was corrugated and the linear speed of the baling belt was 2.0 m/s, and the baling rate of the residual film was 100%, the density variation range of the residual film bale was 88.5 to 92.1 kg/m3. When the recovered residual film contained the same impurities, the density of the residual film bale was related to the linear speed of the baling belt, and the higher the linear speed, the higher the density of the residual film bale. However, when the linear speed exceeds 2.5 m/s, the increasing trend of the density slowed down. The research could provide reference for the development of a new type residual film baling machine.
agricultural machinery; design; residual film; baling machine; rubbing mechanism; floating feeding mechanism
王 征,王吉奎,唐永飛,等. 帶式殘膜揉搓打包機(jī)設(shè)計(jì)與試驗(yàn)[J]. 農(nóng)業(yè)工程學(xué)報(bào),2020,36(19):11-18.doi:10.11975/j.issn.1002-6819.2020.19.002 http://www.tcsae.org
Wang Zheng, Wang Jikui, Tang Yongfei, et al. Design and test of the belt-type residual film rubbing and baling machine[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2020, 36(19): 11-18. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2020.19.002 http://www.tcsae.org
2020-05-05
2020-07-20
國家自然科學(xué)基金資助項(xiàng)目(51465050);石河子大學(xué)成果轉(zhuǎn)化與技術(shù)推廣計(jì)劃項(xiàng)目(CGZH201907)
王征,研究方向?yàn)檗r(nóng)業(yè)機(jī)械裝備創(chuàng)新與性能設(shè)計(jì)。Email:761065289@qq.com
王吉奎,博士,教授,主要從事農(nóng)業(yè)機(jī)械化工程研究。Email:shzwjk@126.com
10.11975/j.issn.1002-6819.2020.19.002
S223.5
A
1002-6819(2020)-19-0011-08