史增錄,唐學(xué)鵬,甄 軍,鄢金山,張學(xué)軍,靳 偉
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釘齒式殘膜撿拾機(jī)構(gòu)運(yùn)動(dòng)仿真分析及性能試驗(yàn)
史增錄1,唐學(xué)鵬1,甄 軍2,鄢金山1,張學(xué)軍1※,靳 偉1
(1. 新疆農(nóng)業(yè)大學(xué)機(jī)電工程學(xué)院,烏魯木齊 830052; 2. 新疆農(nóng)業(yè)大學(xué)交通與物流工程學(xué)院,烏魯木齊 830052)
由于釘齒式殘膜撿拾機(jī)構(gòu)是被動(dòng)式的動(dòng)力驅(qū)動(dòng),且釘齒的運(yùn)動(dòng)受滾筒等多個(gè)動(dòng)參考系的影響,造成釘齒運(yùn)動(dòng)過程的理論計(jì)算難度大、分析依據(jù)不足等問題。通過開展釘齒式殘膜撿拾機(jī)構(gòu)工作原理和動(dòng)力學(xué)的分析,應(yīng)用ADAMS完成運(yùn)動(dòng)學(xué)分析,獲得釘齒相對地面的運(yùn)動(dòng)軌跡、齒尖的位移、速度變化曲線,完成樣機(jī)的試制和田間試驗(yàn)。通過分析,釘齒式殘膜撿拾機(jī)以5km/h的速度作業(yè)時(shí),滾筒轉(zhuǎn)速為50.04 r/min,大于滾筒的臨界轉(zhuǎn)速44.61 r/min,且釘齒相對地面的軌跡為余擺線;釘齒入土?xí)r合速度的方向與垂直方向夾角為18.1°,出土?xí)r合速度的方向和垂直方向基本重合,有利于釘齒的扎入土壤及順利挑膜,滿足設(shè)計(jì)要求;相鄰釘齒齒尖上的標(biāo)記點(diǎn)MARKER_76和MARKER_77在入土、出土?xí)r撿拾區(qū)長分別為51.44和50.08 mm,同水平位置相鄰余擺線間的距離為59.4 mm,大于最大撿拾區(qū)長51.44 mm。田間試驗(yàn)表明,釘齒式殘膜撿拾機(jī)構(gòu)的拾凈率達(dá)71.7%,纏膜率為1.52%,滿足耕層殘膜撿拾作業(yè)的性能要求。該研究可為優(yōu)化作業(yè)參數(shù)、研發(fā)相關(guān)裝備提供參考。
機(jī)械化;計(jì)算機(jī)仿真;優(yōu)化;釘齒;耕層殘膜;動(dòng)力學(xué)
地膜覆蓋種植技術(shù)因其顯著的土壤增溫、保濕、維持土壤結(jié)構(gòu)、防止害蟲侵襲的作用,已在蔬菜、瓜果、棉花、花生、玉米等作物種植上廣泛應(yīng)用[1-2]。中國使用的地膜是聚乙烯烴類有機(jī)高分子化合物,在自然條件下極難降解,在土壤中可存在200~400 a。地膜使用后由于日照風(fēng)化而容易破碎,耕整地作業(yè)后,大量殘膜和作物根茬、土壤混合在一起被埋在耕層中,加大了殘膜回收的難度。經(jīng)過多年的耕作,積累在耕層的殘膜不斷增加,可造成土壤品質(zhì)下降、作物減產(chǎn)[3-6],也給農(nóng)業(yè)生態(tài)環(huán)境造成嚴(yán)重的“白色污染”。因此,治理農(nóng)田殘膜污染已成為亟待解決的難題,治理耕層殘膜污染問題更是迫在眉睫。
按工作原理分類,殘膜回收機(jī)械可分為彈齒式、釘齒式、夾持式、鏈齒式、伸縮桿齒式等[6-9]。但能夠回收耕層內(nèi)殘膜的機(jī)具較少,目前研究耕層殘膜回收機(jī)械的主要有張學(xué)軍團(tuán)隊(duì)研發(fā)的鏈齒式耕層殘膜回收機(jī),可回收150~200 mm深的耕層殘膜[10-11],該機(jī)具的作業(yè)阻力和動(dòng)力消耗較大;張攀峰等研究的旋耕釘齒式的耕層殘膜回收機(jī),可回收耕層150 mm深度的殘膜[12-13],但釘齒上易堆積殘膜,卸膜效果不理想;靳偉等研究了自動(dòng)卸膜式殘膜回收機(jī),其作業(yè)深度為80 mm[14],未達(dá)到耕層殘膜回收的作業(yè)深度。
釘齒式殘膜撿拾機(jī)構(gòu)是為解決新疆南疆地區(qū)使用的扎膜輥撿拾和卸膜切換操作不方便的問題而研發(fā)的,適用于春播前、耕整后土壤松軟、土塊較小的農(nóng)田條件。通過凸輪機(jī)構(gòu)實(shí)現(xiàn)邊扎膜、邊卸膜的作業(yè)過程,能夠撿拾耕層深度為100 mm的殘膜。釘齒是殘膜撿拾機(jī)的重要作業(yè)部件,其性能優(yōu)劣決定了撿拾機(jī)的作業(yè)可靠性、撿拾率等關(guān)鍵指標(biāo)。釘齒式殘膜撿拾機(jī)的動(dòng)力驅(qū)動(dòng)是拖拉機(jī)的牽引力,依靠釘齒扎入土壤的反作用力驅(qū)動(dòng)滾筒轉(zhuǎn)動(dòng),釘齒的運(yùn)動(dòng)不僅受滾筒的約束,還要受推桿、卸膜板等動(dòng)參考物的影響,增加了理論分析的難度。
以理論研究的方法進(jìn)行釘齒式殘膜撿拾機(jī)構(gòu)的釘齒運(yùn)動(dòng)軌跡、速度等的理論計(jì)算難度大、實(shí)際測量的可操作性差,限制了釘齒撿拾殘膜過程的理論分析及結(jié)構(gòu)參數(shù)優(yōu)化[15-17]。為此,利用虛擬仿真技術(shù)進(jìn)行釘齒式殘膜撿拾機(jī)構(gòu)的仿真,在滾子和凸輪之間添加接觸約束,模擬真實(shí)的運(yùn)動(dòng)過程,開展釘齒式撿拾機(jī)構(gòu)的運(yùn)動(dòng)過程分析,是研究被動(dòng)驅(qū)動(dòng)式殘膜撿拾機(jī)構(gòu)的有效方法。
為提高釘齒式殘膜撿拾機(jī)構(gòu)的撿拾率,增加釘齒的數(shù)量,以增加釘齒扎膜的次數(shù)是關(guān)鍵。研制的釘齒式殘膜撿拾機(jī)構(gòu)滾筒直徑為530 mm,釘齒軸向排布距離為75 mm,圓周間的排布距離為120 mm。釘齒式殘膜撿拾機(jī)的結(jié)構(gòu)如圖1所示。
1.懸掛機(jī)構(gòu) 2.釘齒 3.卸膜板 4.推桿 5.滾筒 6.端蓋 7.凸輪 8.刷膜輥 9.機(jī)架 10.集膜箱
釘齒式殘膜撿拾機(jī)的機(jī)構(gòu)簡圖如圖2所示。滾筒和端蓋固定。釘齒一端與滾筒鉸接,釘齒穿在卸膜板上,卸膜板可繞釘齒轉(zhuǎn)動(dòng),作業(yè)時(shí)滾筒在土壤對釘齒的反作用下逆時(shí)針轉(zhuǎn)動(dòng)。卸膜板兩端和推桿鉸接,推桿的一端和端蓋上的鉸接桿連接,推桿的中間孔和卸膜板鉸接,另一端安裝滾子軸承,滾子軸承安裝在凸輪滑槽內(nèi)轉(zhuǎn)動(dòng),凸輪與機(jī)架固定。滾子軸承沿著凸輪軌跡帶動(dòng)推桿運(yùn)動(dòng),運(yùn)動(dòng)到最低點(diǎn)時(shí),推桿拉回卸膜板,釘齒伸出卸膜板的長度最長。滾子軸承運(yùn)動(dòng)至最高點(diǎn)時(shí),推桿向上推動(dòng)卸膜板,卸膜板相對釘齒向外運(yùn)動(dòng),同時(shí)在液壓馬達(dá)的作用下,刷膜輥順時(shí)針反向轉(zhuǎn)動(dòng)將殘膜梳刷到集膜箱中,完成邊扎膜邊卸膜的作業(yè)過程。
1.滾筒 2.卸膜板 3.釘齒 4.端蓋 5.鉸接桿 6.推桿 7.滾子軸承 8.凸輪
1.Roller 2.Unloaded plate 3.Nail tooth 4.End cap 5.Hinge bar 6.Handspike 7. Roller bearing 8.Cam
注:為滾筒的轉(zhuǎn)動(dòng)角速度,rad·s-1;為機(jī)具的前進(jìn)速度,m·s-1。
Note:is angular velocity of roller, rad·s-1;is forward speed of machinery, m·s-1.
圖2 釘齒式殘膜撿拾機(jī)的機(jī)構(gòu)簡圖
Fig.2 Schematic diagram of nail tooth type mechanism for collecting plastic residue
凸輪是驅(qū)動(dòng)撿拾機(jī)構(gòu)的釘齒伸出、縮回的關(guān)鍵部件。凸輪輪廓線設(shè)計(jì)如圖3所示,建立坐標(biāo)系,在反轉(zhuǎn)運(yùn)動(dòng)中,當(dāng)推桿相對于凸輪轉(zhuǎn)過時(shí),推桿處于111位置,則1點(diǎn)的坐標(biāo)如式(1)所示,式(1)是凸輪的理論輪廓線坐標(biāo)。
注:δ為反轉(zhuǎn)運(yùn)動(dòng)時(shí)凸輪的轉(zhuǎn)角,rad;α為推桿在A1C1位置時(shí)的角位移,rad;β為推桿的位置角,rad;a為推桿距回轉(zhuǎn)中心的長度,mm;L為推桿A1C1的長度,mm;θ為理論輪廓線法線和水平線的夾角,rad;r0為理論輪廓線的最小半徑,mm;rr為滾子的半徑,mm。
凸輪的理論輪廓線和工作輪廓線在法向方向的距離應(yīng)等于滾子半徑r,因此在理論輪廓線上任意一點(diǎn)上,只要沿理論輪廓線在該點(diǎn)的法線方向取長度為r,即可得工作輪廓線上的相應(yīng)點(diǎn),由此可得1的工作輪廓線方程,如式(2)所示。
為確保安裝在推桿上的滾子軸承和凸輪保持接觸,設(shè)計(jì)了溝槽式凸輪結(jié)構(gòu),如圖4所示。
圖4 凸輪結(jié)構(gòu)示意圖
殘膜撿拾機(jī)構(gòu)作業(yè)過程中,在凸輪作用下釘齒相對卸膜板伸出時(shí)釘齒入土撿拾扎膜,等釘齒運(yùn)動(dòng)到刷膜輥位置時(shí),在凸輪作業(yè)下釘齒相對卸膜板縮回,在卸膜板和刷膜輥共同作用下,殘膜被卸入集膜箱,實(shí)現(xiàn)殘膜撿拾機(jī)構(gòu)在入土?xí)r撿拾殘膜,在卸膜位置時(shí)自動(dòng)卸膜。卸膜過程如圖5所示。
注:ω1為刷膜輥的轉(zhuǎn)動(dòng)角速度,rad·s-1。
刷膜輥能順利將殘膜從釘齒上卸下的條件為,刷膜輥葉片的速度大于釘齒齒尖的速度,如式(3)所示。
式中為滾筒中心到釘齒齒尖的長度,mm;為刷膜輥直徑,mm。
刷膜輥的轉(zhuǎn)動(dòng)角速度1為
經(jīng)計(jì)算,刷膜輥的轉(zhuǎn)速應(yīng)不低于225 r/min??紤]刷膜過程中卸膜的阻力較小,選用BM1-160的液壓馬達(dá),其連續(xù)運(yùn)轉(zhuǎn)時(shí)的轉(zhuǎn)速達(dá)370 r/min。
釘齒式殘膜撿拾機(jī)構(gòu)作業(yè)時(shí),釘齒的運(yùn)動(dòng)是由機(jī)具的前進(jìn)運(yùn)動(dòng)、滾筒的轉(zhuǎn)動(dòng)、推桿限制釘齒擺動(dòng)和卸膜板相對釘齒的移動(dòng),形成的合成運(yùn)動(dòng)。殘膜撿拾機(jī)構(gòu)的運(yùn)動(dòng)簡圖如圖6所示。進(jìn)行釘齒運(yùn)動(dòng)的理論計(jì)算時(shí),需建立以滾筒為中心的坐標(biāo)系為定參考系,同時(shí)建立釘齒繞滾筒擺動(dòng)的動(dòng)參考系、推桿相對滾筒擺動(dòng)的動(dòng)參考系以及卸膜板相對滾筒的動(dòng)參考系。若計(jì)算釘齒上某一動(dòng)點(diǎn)的運(yùn)動(dòng),需利用坐標(biāo)變換的原理建立絕對、相對和牽連運(yùn)動(dòng)之間的關(guān)系,不僅分析過程復(fù)雜,且計(jì)算難度也大[18-23]。
圖6 殘膜撿拾機(jī)構(gòu)的運(yùn)動(dòng)簡圖
釘齒式殘膜撿拾機(jī)構(gòu)作業(yè)時(shí),殘膜被釘齒挑起時(shí)受力情況如圖7所示。
撿拾機(jī)構(gòu)的實(shí)際受力不僅包括殘膜的重力、釘齒對殘膜的摩擦力以及運(yùn)動(dòng)時(shí)離心慣性力,還有土壤、根茬對殘膜的粘壓力和風(fēng)的阻力等。但釘齒式殘膜撿拾機(jī)構(gòu)是回收100 mm耕層內(nèi)的陳年舊膜,殘膜的強(qiáng)度很低,決定釘齒是否能克服土壤、根茬對殘膜粘壓力的關(guān)鍵,是殘膜的強(qiáng)度能否承受釘齒對殘膜的作用力,且土壤、根茬對殘膜的粘壓力和風(fēng)的阻力是隨機(jī)力,力的大小、方向無法確定。因此,在撿拾機(jī)構(gòu)的動(dòng)力學(xué)分析中未將土壤、根茬對殘膜的粘壓力和風(fēng)的阻力考慮到受力分析中。
注:ε為釘齒與垂直線的夾角,rad;η為離心慣性力和法向力方向的夾角,rad;P為離心慣性力,N;N為殘膜法向力,N;G為殘膜的重力,N;F為摩擦力,N;Gt為殘膜重力的切向力,N;Gn為殘膜重力的法向力,N。
根據(jù)圖4可知,釘齒對殘膜作用的法向力為
式中為殘膜的質(zhì)量,g;為被撿殘膜重心的瞬時(shí)半徑,m;為重力加速度,m/s2。
為使殘膜能夠被釘齒挑起的必要條件為
式中為釘齒和殘膜的摩擦系數(shù)。
式(9)簡化可得
經(jīng)計(jì)算,得≥4.67 rad/s,對應(yīng)的滾筒轉(zhuǎn)速為44.61 rad/s,該值是釘齒能夠順利挑起殘膜的臨界角速度。當(dāng)小于4.67 rad/s時(shí),釘齒撿拾的殘膜可能會(huì)沿釘齒滑落,降低撿拾殘膜的作用。由于釘齒式殘膜撿拾機(jī)構(gòu)是被動(dòng)驅(qū)動(dòng)的方式,依靠釘齒扎入土壤所受的作用力和卸膜板所受土壤的摩擦力帶動(dòng)滾筒轉(zhuǎn)動(dòng)。因此,作業(yè)速度的大小影響滾筒轉(zhuǎn)動(dòng)的角速度的大小,也決定著撿拾機(jī)構(gòu)的殘膜撿拾性能。為保證撿拾機(jī)構(gòu)的撿拾性能,將殘膜撿拾機(jī)構(gòu)被動(dòng)驅(qū)動(dòng)的方式變?yōu)橹鲃?dòng)驅(qū)動(dòng)的方式,可提高釘齒撿拾殘膜的可靠性。
用Solidworks軟件建立釘齒式殘膜撿拾機(jī)構(gòu)的三維參數(shù)化模型,并完成裝配。將三維模型另存為Parasolid(.X_T)格式。將Parasolid(.X_T)格式文件導(dǎo)入到ADAMS軟件中,生成ADAMS環(huán)境下的模型[24-25]。
利用ADAMS中的工具箱操作,在大地、機(jī)架、釘齒、推桿、凸輪、拐臂、滾筒之間添加適當(dāng)?shù)募s束。為準(zhǔn)確的模擬殘膜撿拾機(jī)構(gòu)在工作中的實(shí)際運(yùn)動(dòng)情況,對其各部件均按實(shí)際情況添加部件的材料屬性。為提高仿真計(jì)算的速度,只保留了相鄰的2個(gè)釘齒,刪掉其他的釘齒、擺桿、刷膜輥、集膜箱等部件。
釘齒式殘膜撿拾機(jī)構(gòu)以5 km/h的速度作業(yè)時(shí),滾筒轉(zhuǎn)速為50.04 r/min。經(jīng)計(jì)算,添加在機(jī)架上的平移驅(qū)動(dòng)速度為1 388.89 mm/s,作用在滾筒上的旋轉(zhuǎn)驅(qū)動(dòng)的角速度值為300.45 °/s。
進(jìn)行ADAMS的求解計(jì)算時(shí),設(shè)置仿真的時(shí)間為1.8 s、步長為300步。
為方便分析釘齒齒尖運(yùn)動(dòng),在相鄰釘齒的齒尖上分別創(chuàng)建了MARKER_76和MARKER_77 2個(gè)標(biāo)記點(diǎn)。仿真結(jié)束后,從后處理器輸出一系列仿真結(jié)果。圖8是相鄰釘齒齒尖的運(yùn)動(dòng)變化曲線,其中圖8a是釘齒齒尖相對地面的運(yùn)動(dòng)軌跡曲線,圖8b是釘齒齒尖在垂直方向的位移變化曲線,圖8c是釘齒齒尖在水平方向的位移變化曲線,圖9是相鄰釘齒齒尖的速度的變化曲線。
圖8 相鄰釘齒齒尖的位移變化曲線
圖9 相鄰釘齒齒尖的速度變化曲線
根據(jù)圖8a所示釘齒齒尖的運(yùn)動(dòng)軌跡線,結(jié)合殘膜撿拾機(jī)構(gòu)的作業(yè)深度,確定從釘齒齒尖最低點(diǎn)的位移向上100 mm為撿拾區(qū),當(dāng)撿拾滾筒運(yùn)動(dòng)1.8 s時(shí),釘齒齒尖的標(biāo)記點(diǎn)MARKER_76和MARKER_77分別2次入土和出土。為確保釘齒入土、出土的數(shù)據(jù)準(zhǔn)確性,去掉第一次入土、出土的數(shù)據(jù),以MARKER_76和MARKER_77第二次入土、出土的數(shù)據(jù)為依據(jù),進(jìn)行分析。
圖9所示的MARKER_76和MARKER_77的速度變化曲線存在一定幅度的波動(dòng)。通過對殘膜撿拾機(jī)構(gòu)的運(yùn)動(dòng)原理和施加約束等的分析,主要原因是推桿一端和滾筒端蓋鉸接,推桿另一端和凸輪用接觸命令進(jìn)行約束,推桿在凸輪的軌道內(nèi)運(yùn)動(dòng)時(shí),在上、下軌道面的切換過程中存在一定的沖擊力,造成了釘齒速度變化的波動(dòng)。
在ADAMS/Postprocessor中利用軌跡點(diǎn)跟蹤功能,完成圖8a所示曲線數(shù)據(jù)的采集[24]。通過對釘齒齒尖的運(yùn)動(dòng)軌跡分析,以釘齒入土100 mm為理論耕層深度,確定MARKER_76和MARKER_77分別在入土、出土?xí)r的垂直方向位移。結(jié)合圖8b所示的曲線變化,確定MARKER_76和MARKER_77分別在入土、出土?xí)r對應(yīng)的時(shí)間。根據(jù)圖9所示,獲得MARKER_76和MARKER_77在入土、出土?xí)r的水平方向速度和垂直方向速度;根據(jù)圖8c所示的釘齒齒尖水平方向位移的變化曲線,取得入土和出土?xí)r的水平位移,通過計(jì)算可獲得單個(gè)釘齒的作業(yè)撿拾區(qū)長度,具體數(shù)據(jù)如表1所示。
通過仿真分析,釘齒運(yùn)動(dòng)時(shí)齒尖相對地面的軌跡是余擺線,依靠余擺線從最低點(diǎn)向上100 mm的區(qū)域?yàn)闅埬焓皡^(qū)域。圖8a所示的釘齒軌跡線滿足設(shè)計(jì)的預(yù)期要求,可完成設(shè)計(jì)的撿拾動(dòng)作。
根據(jù)釘齒相對地面的軌跡線,利用圖解法完成釘齒入土和出土?xí)r的速度分析圖,如圖10所示。MARKER_76的入土合速度為1 103.69 mm/s,出土合速度為1 254.10 mm/s;MARKER_77入土合速度為1 081.03 mm/s,出土合速度為1 249.89 mm/s。釘齒入土合速度方向和垂直方向的夾角為18.1°,出土的合速度和垂直方向基本重合。
根據(jù)圖8c所示的釘齒在水平方向位移變化曲線,釘齒在100 mm深的耕層作業(yè)時(shí),MARKER_76在入土、出土的撿拾區(qū)長為51.44 mm;MARKER_77入土、出土的撿拾區(qū)長為50.08 mm;結(jié)合圖8a所示,在MARKER_76 和MARKER_77的余擺線從下往上100 mm深耕層位置,相鄰兩余擺線間的距離為59.4 mm,大于釘齒的最大撿拾區(qū)長51.44 mm。
表1 相鄰釘齒齒尖的運(yùn)動(dòng)參數(shù) Table 1 Motion parameter of tooth tips of adjacent nail teeth
圖10 相鄰釘齒齒尖入土、出土速度分析
為了驗(yàn)證所設(shè)計(jì)樣機(jī)的作業(yè)性能指標(biāo),試制了整機(jī)物理樣機(jī)。2017年4月,在新疆阿克蘇6團(tuán)試驗(yàn)田進(jìn)行了田間耕層殘膜撿拾機(jī)構(gòu)的作業(yè)性能試驗(yàn)[26-31],如圖11所示。試驗(yàn)田選擇耕后(播前)較平坦的棉花地,配套鐵牛754型拖拉機(jī)為動(dòng)力,作業(yè)速度為5 km/h,撿拾滾筒的轉(zhuǎn)度為50 r/min。
圖11 釘齒式殘膜撿拾機(jī)的田間試驗(yàn)
殘膜撿拾機(jī)構(gòu)作業(yè)性能試驗(yàn)時(shí),作業(yè)前在測區(qū)內(nèi)進(jìn)行作業(yè)前的測點(diǎn)采樣,測點(diǎn)采樣采用五點(diǎn)法,每個(gè)測點(diǎn)面積為1 m2,按耕層深度為100 mm取樣。去除塵土和水分后,稱取樣殘膜的質(zhì)量,求其平均值獲得作業(yè)前耕層殘膜質(zhì)量;作業(yè)后在同一測區(qū)不同的測點(diǎn)位置進(jìn)行作業(yè)后的測點(diǎn)采樣,按照同樣的方法獲得作業(yè)后耕層殘膜質(zhì)量。按式(11)計(jì)算耕層的拾凈率。
式中為拾凈率,%;為作業(yè)后的耕層殘膜質(zhì)量,g;0為作業(yè)前耕層殘膜質(zhì)量,g。
殘膜撿拾機(jī)構(gòu)的纏膜率計(jì)算根據(jù)式(12)計(jì)算。
式中為纏膜率,%;1為測區(qū)內(nèi)纏繞在殘膜機(jī)上的殘膜質(zhì)量,g;2為測區(qū)內(nèi)收集在集膜箱內(nèi)的殘膜質(zhì)量,g。
按照標(biāo)準(zhǔn)GB/T 25412-2010《殘地膜回收機(jī)》的試驗(yàn)要求,進(jìn)行殘膜撿拾作業(yè)試驗(yàn)指標(biāo)的測定,田間測試結(jié)果如表2所示。
表2 殘膜撿拾機(jī)構(gòu)作業(yè)性能 Table 2 Performance of mechanism for collecting plastic residue
1)通過對撿拾機(jī)構(gòu)的分析,釘齒可挑起殘膜的滾筒臨界轉(zhuǎn)速為44.61 r/min。為保證釘齒能將殘膜順利挑起,則滾筒的轉(zhuǎn)速不能低于44.61 r/min。
2)通過ADAMS軟件對殘膜撿拾機(jī)構(gòu)作業(yè)過程的仿真,相鄰釘齒入土合速度分別為1 103.69和1 081.03 mm/s,合速度的方向與垂直方向的夾角為18.1o,作業(yè)時(shí)釘齒入土的阻力較??;相鄰釘齒的出土合速度分別為1 254.10和1 249.89 mm/s,合速度方向基本和垂直方向平行,釘齒可順利將殘膜挑起。由此可見,采用凸輪機(jī)構(gòu)實(shí)現(xiàn)釘齒式殘膜撿拾機(jī)構(gòu)邊扎膜、邊卸膜的原理是可行的。
3)仿真結(jié)果表明,釘齒在100 mm深的耕層作業(yè)時(shí),相鄰釘齒齒尖上的標(biāo)記點(diǎn)MARKER_76和MARKER_77在入土、出土?xí)r的撿拾區(qū)長分別為51.44和50.08 mm,以余擺線最低點(diǎn)向上100 mm的位置,MARKER_76和MARKER_77的余擺線間的距離為59.4 mm,大于釘齒的最大撿拾區(qū)長51.44 mm。通過增大釘齒式殘膜撿拾機(jī)構(gòu)的釘齒撿拾區(qū)長度,減少相鄰兩余擺線間的距離,可提高耕層拾凈率。
4)通過分析、仿真和田間試驗(yàn)研究發(fā)現(xiàn),釘齒式殘膜撿拾機(jī)構(gòu)通過改變被動(dòng)驅(qū)動(dòng)方式為主動(dòng)驅(qū)動(dòng)方式及優(yōu)化相鄰釘齒余擺線間的距離,可進(jìn)一步提高該機(jī)構(gòu)的殘膜拾凈率。
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Performance test and motion simulation analysis of nail tooth type mechanism for collecting plastic residue
Shi Zenglu1, Tang Xuepeng1, Zhen Jun2, Yan Jinshan1, Zhang Xuejun1※, Jin Wei1
(1.,,830052,; 2.,,830052,)
The problem of residual film pollution is serious in the fields of Xinjiang,and the mechanical recycling of residual film is the main recycling method.However, few mechanism can be used to recover the plastic residue of the plough layer. The nail tooth type mechanism for collecting plastic residue can recover the plastic residue from the plough layer. Nail tooth type mechanism for collecting plastic residue is composed of roller, unloaded plate, nail tooth, end cap, handspike and cam, etc. When the mechanism for collecting plastic residue is operated, the nail tooth pick-up and tie the plastic residue when the nail tooth reach the position of film-brushing roller relative to the film-removing plate, the nail tooth retract relative to the film-removing plate under the cam operation, and the film-removing plate when the nail tooth reach the position of film-removing roller under the cam operation. Under the joint action of the plastic residue brushing roller, the plastic residue is unloaded into the film collecting box, to realize the function of side pick up and unloading. Through the virtual simulation technology, the trajectory of the nail tooth and the speed of the nail tooth are obtained. The nail tooth type mechanism for collecting plastic residue is a passive driving method, in which the cam, handspike, unloading plate and the nail tooth interact and the nail tooth is driven by the force of the nail tooth penetrating into the soil. The constraint between roller bearing and cam cannot simply be given a point-line constraint pair, but according to the actual situation, the contact constraint between roller and cam is added, which can better simulate the real motion. For nail tooth type mechanism for collecting plastic residue is passive power drive, and nail tooth movement is influenced by roller, and other moving reference frame, the nail tooth movement process of the theoretical calculation is difficult, lack of theoretical basis to carry out the nail tooth type mechanism collecting plastic residue working principle and dynamics analysis. By use of ADAMS, we completed kinematics analysis, and obtained the nail tooth relative to the movement of the ground, and the tooth curves of displacement and velocity. We also completed the prototype trial-manufacture and field experiment. Through analysis, When the nail tooth type mechanism for collecting plastic residue operates at a speed of 5 km/h, the rotational speed of the drum is 50.04 r/min, greater than the critical speed of roller 44.61 r/min, and nail tooth relative to the ground track for trochoid, nail tooth into the soil when the resultant velocity direction and vertical direction Angle was 18.1°. The out-earth combined speed paralleled the vertical direction, which is advantageous to the nail tooth into the soil and the smoothly picked plastic residue, meeting the design requirements. Marking points MARKER_76 and MARKER_77 on the tips of adjacent nail teeth were respectively 51.44 and 50.08 mm in length of collecting area when they were put into soil and excavated. The distance between adjacent cycloid lines at the same horizontal position was 59.4 mm, greater than the maximum picking area of 51.44 mm. Field experiments showed that the net collected rat of the deep layer of nail tooth type mechanism for collecting plastic residue was 71.7% and the wrapping rate was 1.52%, which can meet the performance requirements of the tillage residual film scavenging operation. The analysis results provide references for optimizing operation parameters and developing related equipment.
mechanization; computer simulation; optimization; nail tooth; plastic residue of plough layer; dynamics
史增錄,唐學(xué)鵬,甄 軍,鄢金山,張學(xué)軍,靳 偉. 釘齒式殘膜撿拾機(jī)構(gòu)運(yùn)動(dòng)仿真分析及性能試驗(yàn)[J]. 農(nóng)業(yè)工程學(xué)報(bào),2019,35(4):64-71. doi:10.11975/j.issn.1002-6819.2019.04.008 http://www.tcsae.org
Shi Zenglu, Tang Xuepeng, Zhen Jun, Yan Jinshan, Zhang Xuejun, Jin Wei. Performance test and motion simulation analysis of nail tooth type mechanism for collecting plastic residue[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2019, 35(4): 64-71. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2019.04.008 http://www.tcsae.org
2018-08-07
2019-01-27
獲國家重點(diǎn)研發(fā)計(jì)劃課題(2017YFD0701102);國家自然基金項(xiàng)目(51665057);新疆維吾爾自治區(qū)高校科研計(jì)劃(XJEDU2017T005)
史增錄,實(shí)驗(yàn)師,主要從事農(nóng)業(yè)工程技術(shù)與裝備研究。 Email:shizlfd@qq.com
張學(xué)軍,教授,博士,主要從事農(nóng)業(yè)工程技術(shù)與裝備研究。Email:zhaxjau@sina.com
10.11975/j.issn.1002-6819.2019.04.008
S224.9
A
1002-6819(2019)-04-0064-08