萬星宇,舒彩霞,2,3,徐 陽,袁佳誠,李海同,廖慶喜,2,3
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油菜聯合收獲機分離清選差速圓筒篩設計與試驗
萬星宇1,舒彩霞1,2,3,徐 陽1,袁佳誠1,李海同1,廖慶喜1,2,3※
(1. 華中農業大學工學院,武漢 430070;2. 南方糧油作物協同創新中心,長沙 410128;3. 農業農村部長江中下游農業裝備重點實驗室,武漢 430070)
為減少油菜聯合收獲機旋風分離清選系統負載和提高清選性能,該文設計了一種與旋風分離清選裝置配合使用、可對油菜脫出物進行初步篩分的差速圓筒篩。分析計算了篩網與助流裝置轉速范圍,開展了基于EDEM的性能指標正交試驗,以篩分損失率與篩下物清潔率為指標,以篩網轉速、助流裝置轉速和助流裝置投影面齒數為影響因素,得出了最佳參數組合,并開展了臺架及田間驗證試驗。仿真結果表明:最佳參數組合為篩網轉速35 r/min,助流裝置轉速80 r/min,助流裝置投影面鋸齒數6個。臺架驗證試驗表明:整機喂入量3 kg/s、脫出物喂入量為1 kg/s條件下,差速圓筒篩與旋風分離清選裝置配合使用,清選系統油菜籽粒總損失率為4.83%,其中篩分損失率為3.97%,清潔率為85.7%,風機轉速可降低36.9%。田間試驗表明:清選系統損失率平均值為5.9 %,籽粒清潔率平均值為84.4%,平均功耗為3.48 kW,差速圓筒篩作業順暢。該研究可減少旋風分離清選負載,為油菜聯合收獲機清選系統的結構改進和優化提供參考。
農業機械;設計;試驗;油菜;清選;旋風分離;圓筒篩;EDEM
現階段油菜機械化收獲主要有分段收獲和聯合收獲兩種方式[1-4],聯合收獲一次性完成全部作業環節,生產效率高,其中清選系統是油菜聯合收獲機的關鍵部件,常用油菜聯合收獲機多為稻麥收獲機改裝,清選裝置多采用風機與振動篩配合使用,通過增大割臺深度、調節撥禾輪位置及傳動比、增加主動分禾器、更換篩網等措施以適應田間油菜植株高大、分枝多且相互纏繞、成熟度不一致等因素導致的喂入量波動、油菜脫出物組分糅雜等復雜工況,常用往復式振動篩在處理含水率較高的油菜脫出物時,在無清篩裝置的條件下物料運移過程中易出現油菜脫出物堵塞篩網即“糊篩”現象,導致物料透篩率降低,造成籽粒損失增大、清潔率降低等問題,在簡化結構、減少損失、降低振動等方面有待優化[5-9]。旋風分離采用氣流清選原理,結構相對簡單,工作狀態相對平穩、噪音低,多應用于糧食加工、工業除塵等領域[10-12],已有學者將旋風分離引入谷物聯合收獲機中[13-17]。旋風分離清選系統主要利用谷物脫出物各組分懸浮速度差異分離籽粒與雜余[18-20],但油菜脫出物成分復雜,清選負載較大,對油菜脫出物的適應性有待提高,增加初步篩選裝置分離脫出物中尺寸較大的粗長雜余是減少旋風分離清選系統負載的解決方法之一。圓筒篩為回轉運動篩,工作平穩,在糧食分級、精選等領域應用較為廣泛[21-24],在谷物聯合收獲機中鮮有研究,其原因之一在于圓筒篩主要利用物料機械物理特性差異和離心力分離各物料組分,為增加物料流速以提高作業效率,圓筒篩多為傾斜配置[25-27],但傳統機械傳動方式安裝復雜。本文為解決油菜聯合收獲機旋風分離清選系統負載較大的問題,設計了一種與旋風分離清選系統配合使用的差速圓筒篩,在圓筒篩內增加物料助流裝置以提高作業質量,降低“糊篩”影響,初步篩分油菜脫出物中的粗長雜余,減少旋風分離清選系統的負載,提高旋風分離清選系統對油菜脫出物的適應性。
本研究清選系統適應多種油菜聯合收獲機,基于自制4LYZ-1.8型油菜聯合收獲機開展研究,其結構如圖1所示,主要包括分體組合式割臺、集成式縱軸流脫粒分離裝置、清選系統等部分。已割油菜在分體組合式割臺撥禾輪作用下進入脫粒分離裝置,脫粒分離后的油菜脫出物由篩下物輸送攪龍提升至后續清選系統中。整機參數如表1所示。

1. 分體組合式割臺 2. 復合式推運器 3. 集成式縱軸流脫粒分離裝置 4. 底盤 5.篩下物提升攪龍 6. 差速圓筒篩 7. 拋揚機 8. 糧倉 9. 旋風分離筒 10. 吸雜管道 11. 風機 12. 液壓油箱 13. 駕駛室

表1 油菜聯合收獲機主要技術參數
清選系統主要由差速圓筒篩與旋風分離清選裝置組成,差速圓筒篩主要包括喂入攪龍、圓筒篩網、篩網內部的助流裝置、罩殼等組成,旋風分離清選系統主要包括拋揚機、旋風分離筒、吸雜管道、離心風機、籽粒提升攪龍等。清選系統作業對象為油菜脫出物,主要包括油菜籽粒、粗長雜余(短莖稈及莢殼)及輕雜余。差速圓筒篩主要功能是完成油菜脫出物的初步篩分,喂入攪龍將脫出物喂入圓筒篩網內,篩網與助流裝置差速轉動、轉向相反,助流裝置擾動物料并促進物料向排草口移動,粗長雜余被排出機外,透過篩網的油菜籽粒及輕雜余則進入拋揚機,在拋揚機作用下以一定速度進入旋風分離筒,在旋風分離筒內負壓氣流作用下分離油菜籽粒及輕雜余,輕雜余經由吸雜管道及離心風機排出,油菜籽粒由旋風分離筒出糧口下落進入提升攪龍被提升至糧倉中,完成清選作業,清選系統作業流程如圖2所示。

1. 喂料口 2. 罩殼 3. 圓筒篩 4. 助流裝置 5.排草口 6. 粗長雜余 7. 拋揚機 8. 旋風分離筒 9. 吸雜管道 10. 離心風機 11. 輕雜余 12. 出糧口 13. 油菜籽粒
差速圓筒篩作為清選系統的初選裝置,其結構如圖3所示,主要包括圓筒篩、助流裝置、罩殼及傳動裝置。圓筒篩為平面篩環形彎折定型,助流裝置為鋸齒形螺旋結構且安裝于圓筒篩內部,二者同軸轉動;液壓馬達為助流裝置提供動力,通過過渡傳動軸齒輪傳動將動力傳遞給圓筒篩,由齒輪傳動完成換向功能,實現圓筒篩與助流裝置同軸轉動、轉向相反的差速運動以促進物料流動;助流裝置主體為鋸齒形螺旋葉片,其軸向投影具有若干均分鋸齒,通過轉動過程中葉片的高度變化,實現對緊貼篩網物料的間斷輸送以及對遠離篩面物料的連續輸送即實現分層輸送,增加緊貼篩網處物料的篩分時間,促進遠離篩網物料的軸向流動使物料到達前方篩分區域,增加篩分效率。差速圓筒篩篩分效果與篩網有效篩分面積、篩網轉速、篩網類型、篩孔布局、助流裝置轉速等有關。

1. 液壓馬達 2. 下罩殼 3. 助流裝置 4. 過渡傳動軸 5. 上罩殼 6. 圓筒篩 7. 喂料口 8. 篩下物出口 9. 排草口
物料進入圓筒篩后在篩面摩擦力作用下沿篩面上升至一定高度,然后在重力作用下下落至篩面底部,為周期性運動,物料運動過程中可接觸篩網部分的面積即篩網有效篩分面積,有效篩分面積越大,篩網可承擔的物料喂入量越大。有效篩分面積與篩網直徑、篩網長度、篩網轉速等參數有關。在有效篩分面積內為保證油菜籽粒能及時透過篩網、減少篩分損失,以油菜籽粒為對象分析其在篩網內運動范圍最低點與最高點的臨界受力狀態,如圖4所示。
最低平衡點處油菜籽粒受力分析可知:

計算得


1. 圓筒篩 2. 油菜籽粒
1. Cylinder sieve 2. Rapeseed
注:為油菜籽粒質量,g;為平衡狀態最低點的油菜籽粒與圓心的連線和垂直中心線之間的夾角,rad;1為最低點處摩擦力,N;為圓筒篩角速度,rad×s-1;為圓筒篩內徑,mm;1為最低點處支撐力,N;為油菜籽粒與篩網的摩擦系數,油菜籽粒與篩網摩擦角為15°[28],故tan=0.27;為平衡狀態最高點的油菜籽粒與圓心的連線和垂直中心線之間的夾角,rad;2為最高點處摩擦力,N;2為最高點處支撐力,N;為透篩油菜籽粒與圓心的連線和垂直中心線之間的夾角,rad,?[,p-];3為甩出摩擦力,N;3為甩出時篩面支撐力,N;1為有效篩分面積,m2。
Note:is the rapeseed mass, g;is the angle between the lines between rapeseed at lowest point and circle center and the vertical center line in force balance state, rad;1is the friction at the lowest point, N;is the angular velocity of cylinder sieve, rad×s-1;is the internal diameter of cylinder sieve, mm;1is the supporting force at the lowest point, N;is thefriction coefficient between rapeseed and the sieve. The friction anglebetween rapeseed and sieve is 15°[28], sotan=0.27;is the angle between the lines between rapeseed at highest point and circle center and the vertical center line in force balance state, rad;2is friction at the highest point, N;2is the supporting force at highest point, N;is the angle between the lines between rapeseed going through sieve holes and circle center with the vertical center line,?[,p-], rad;3is the friction when the rapeseed goes through sieve holes, N;3is the supporting force when the rapeseed goes through sieve holes, N;1is the effective screening area, m2.
圖4 臨界位置處油菜籽粒受力分析
Fig.4 Stress analysis of a rapeseed at the critical location
最高平衡點處受力分析可知:

計算得

為保證油菜籽粒能夠穿過篩孔,油菜籽粒在篩孔內受力應滿足

計算得

為防止油菜籽粒由頂部排出,需大于0,取0即油菜籽粒位于篩網垂直方向頂端時,油菜籽粒所受重力需大于離心力使油菜籽粒回落至篩網內部,即

計算得

1為截面內有效篩分弧長,有效篩分面積1滿足

式中為篩網長度,mm。由式(9)可知,有效篩分面積與圓筒篩直徑、長度與轉速有關。
圓筒篩面為平面篩網環形彎折成型,不考慮材料拉伸和壓縮,篩孔在平面上的投影為橢圓形,如圖5所示。

注:l0為折彎后篩孔最小弧長,mm;d為折彎前平面篩孔直徑,mm;i為單個篩孔在折彎后對應的圓弧角,rad;dk為折彎后篩孔投影短軸長,mm。
長軸長度為彎折前篩孔直徑,則短軸長度滿足:

為保證油菜籽粒順利透過篩孔,短軸長度需滿足:
d>0(11)
式中0為油菜籽粒直徑,取2 mm[29]。
根據農業機械設計手冊可知,篩網單位面積可承擔的脫出物喂入量q為1.5~2.5 kg/(s?m2),油菜籽粒較小,q可取2.5 kg/(s?m2)[30],有效篩分面積需滿足:

式中Q為脫出物喂入量,割臺喂入量為3 kg/s時測得脫出物喂入量為1 kg/s。計算得1≥0.4 m2。
考慮到整機安裝空間,取篩網內徑=500 mm,代入式(6)與式(8)可得圓筒篩轉動角速度范圍為:
3.25 rad/s< 6.26 rad/s
轉換為轉速
31.1 r/min< n<59.8 r/min
由式(2)與式(4)可知:

解得

將=0.27代入解得
+=1.04 rad (15)
計算得1= 0.525 m,則≥0.76 m,設計取整數= 800 mm,實際有效篩分面積1=0.42 m2,篩網總面積=1.256 m2。
由篩孔短軸計算得>3.9 mm,考慮通用性,選擇=5 mm。
篩網面積一定條件下,篩孔數量與篩孔面積有效系數有關,越大篩孔數越多,常規篩面中正三角形排布篩孔的面積有效系數較大,如圖6所示,設篩網孔距為0,為保證篩網整體剛度,取0=3 mm,篩孔按正三角形排布的篩面面積有效系數為:

計算得=0.35。
注:0為篩孔間距,mm。
Note:0is the spacing of the sieve holes, mm.
圖6 篩孔排布
Fig.6 Arrangement of sieve holes
設篩面橫截面處篩孔數量相等,則篩孔總數量滿足

計算得=2.24×104。
物料助流裝置為螺旋鋸齒形結構,安裝在圓筒篩內部,與圓筒篩同軸反向轉動,以鋸齒齒根圓為分界線,鋸齒部分對緊貼篩面的物料進行間斷輸送,可將油菜脫出物打散,保證篩分時間,鋸齒齒根圓以下葉片部分為連續輸送,可持續輸送遠離篩面的物料,緊貼篩網部分與遠離篩網部分物料輸送速度不同,即實現分層輸送,為提高篩面利用率,分層輸送設計為均分物料層,結構圖與軸向投影視圖如圖7所示。

注:Df為助流裝置葉片內徑,mm;D1為鋸齒葉片齒根圓直徑,mm;D2為齒頂圓直徑,mm;a為連續葉片外圓與篩網間隙,mm;b為鋸齒齒頂與篩網間隙,mm;H為物料流動層高度,mm;ωz為助流裝置角速度,rad×s-1;t為葉片螺距,mm。
為保證脫出物充分的篩分時間,物料軸向運動速度不宜太快,設物料軸向平均輸送速度v=0.25 m/s[27],則單位時間內物料流動層高度滿足:

式中0為脫出物密度,取粗長莖稈密度80 kg/m3計算,計算得=119 mm,取120 mm。
助流裝置葉片內徑即葉片中心軸直徑滿足:

計算得D<260 mm,在葉片外徑一定情況下,葉片內徑越小,葉片高度即葉片作用面積越大,針對喂入量波動現象,宜取較小的葉片內徑以增強助流裝置對物料喂入量適應性和對物料的促流作用,同時考慮實際加工對管料的通用性,取D=50 mm。
為實現分層輸送,連續葉片外圓直徑保證均分物料層,物料層厚度由式(18)計算為120 mm,則1380 mm,連續葉片外圓與篩網間隙為=(–1)/2= 60 mm,葉片與篩網之間的間隙一般為5~10 mm[30],油菜籽粒易破損,為減少對油菜籽粒的碾壓,篩網間隙可取較大值,故鋸齒齒頂與篩網間隙取=10 mm,則齒頂圓直徑2480 mm。
助流裝置輸送能力需要大于粗長雜余的喂入量[18],鋸齒形葉片按照螺旋葉片輸送能力計算需大于脫出物喂入量,同時為減少油菜籽粒篩分損失,助流裝置葉片鋸齒底徑以下部分的連續螺旋輸送量需小于油菜脫出物喂入量:

式中1為助流裝置模擬螺旋葉片連續輸送的輸送量,kg/s;2為助流裝置鋸齒以下部分螺旋葉片連續輸送的輸送量,kg/s;為充滿系數,取0.3[30];為葉片螺距,考慮葉片通用性,取螺旋輸送常用螺距200 mm[30];為助流裝置轉速,r/min;為物料密度,取80 kg/m3[30];為傾斜輸送系數,水平輸送取1[30]。計算得:
76.2 r/min≤≤244.6 r/min
鋸齒按圓周均勻分布,其數量z與鋸齒間隙角滿足:

鋸齒數量過少會降低助流裝置輸送能力,過多則會增加油菜籽粒篩分損失,以助流裝置投影面鋸齒數為因素,后續取投影面均按鋸齒數為2、4、6三個水平開展相關試驗。
清選系統作業對象包括油菜籽粒、粗長雜余(短莖稈及莢殼)及輕雜余,測量脫粒分離裝置篩下物成分可知,割臺喂入量為3 kg/s時,脫粒分離裝置脫出物輸出量為1 kg/s,油菜脫出物中油菜籽粒、粗長雜余及輕雜余質量之比為1∶1.5∶0.5。
差速圓筒篩作為清選系統的關鍵部件,其性能直接影響籽粒清潔率與損失率,因此,采用EDEM建立差速圓筒篩的仿真模型,以油菜脫出物成分含量最高的油菜籽粒、粗長雜余及輕雜余為研究對象,開展正交試驗分析運行參數與結構參數變化對差速圓筒篩篩下物油菜籽粒清潔率與排草口篩分損失率的影響,得出最佳參數組合。
3.1.1 變量參數設置
差速圓筒篩篩分過程的實質是通過篩面及助流裝置與顆粒之間以及顆粒與顆粒之間的接觸、碰撞促使顆粒運動、透篩。為描述碰撞過程,本文采用Hert-Mindlin無滑移模型。各物料顆粒的力學特性參數及和其他物體的接觸系數[19]設置見表2和表3。

表2 物料力學參數

表3 接觸系數
3.1.2 顆粒模型
為保證差速圓筒篩作業過程的真實模擬,參照相關文獻及對油菜脫出物中油菜籽粒、粗長雜余及輕雜余相關參數測定,建立顆粒模型,如圖8所示,其中油菜籽粒為球形,直徑2 mm;粗長雜余為長圓柱形,外徑8 mm,長度60 mm[31];輕雜余為長方體,選取油菜脫出物中輕雜余,主要為破碎莢殼薄片,外形近似為長方體,開展三軸尺寸測量取平均值并取整,仿真中取長4 mm,寬 3 mm,高1 mm。

圖8 顆粒模型
3.1.3 差速圓筒篩仿真模型
利用Pro/E軟件在合理簡化、保留主要工作部件的基礎上,按照理論計算得出的結構參數1:1建模,對差速圓筒篩進行三維建模,主要包括罩殼、圓筒篩、助流裝置等部件,如圖9所示。顆粒工廠位于模型喂料口內,按照脫出物總質量及各成分比例設定油菜籽粒、粗長雜余和輕雜余生成總質量分別為0.3、0.45和0.15 kg,各顆粒同時產生,產生方式均為動態,顆粒產生時間為1 s,時間步長設定為Rayleigh時間步長的20%,即10–5s,數據記錄間隔0.01 s,為保證顆粒完整輸送,將圓筒篩與助流裝置運動模擬時間總長設為10 s。

1. 喂料口 2. 罩殼 3. 助流裝置 4. 圓筒篩 5. 排草口 6. 出糧口
上文理論分析已確定篩網類型、篩孔排列、篩網內徑、篩面長度等結構參數,對篩網轉速、助流裝置轉速等運行參數范圍進行了分析,故仿真過程中以助流裝置轉速、篩網轉速及助流裝置投影面鋸齒數為影響因素,以差速圓筒篩出糧口油菜籽粒清潔率與排草口篩分損失率為評價指標,開展三因素三水平正交試驗,因素水平如表4所示。仿真結束后統計排草口與出糧口物料總質量與油菜籽粒總質量,計算清潔率與損失率:

式中Y為油菜籽粒清潔率,%;1為出糧口油菜籽粒質量,kg;0為出糧口物料總質量,kg;Y為篩分損失率,%;2為排草口油菜籽粒質量,kg。

表4 因素水平
正交試驗設計及試驗結果如表5所示,采用綜合評分法分析[13],實際生產中需優先保證損失率低,其次保證清潔率高,擬定清潔率權重為0.35,損失率權重為0.65,以加權后的綜合分作為評價標準,得分越高效果越好。
綜合分=清潔率隸屬度′0.35–損失率隸屬度′0.65 (23)
正交試驗仿真結果表明:最佳參數組合為助流裝置轉速80 r/min,圓筒篩轉速35 r/min及助流裝置投影面鋸齒數為6個,影響差速圓筒篩效果的因素主次為助流裝置轉速、篩網轉速及助流裝置投影面鋸齒數;最佳參數組合條件下,仿真得出差速圓筒篩篩分損失率為2.54%,清潔率為83.58%,差速圓筒篩中篩網轉速過高時,物料在離心力作用下緊貼篩面,導致糊篩,減少油菜籽粒透篩概率,造成篩分損失率增大;助流裝置轉速較高則促進物料流動能力提高,物料輸送過快,油菜籽粒來不及透過篩網亦會造成篩分損失率提高;同理,若助流裝置投影面齒數過少,對物料流動的促進作用也會增強,導致篩分損失率增加,符合圓筒篩相關研究結果[27]。差速圓筒篩篩網轉速需在滿足透篩率要求的前提下采用較低轉速,助流裝置需在滿足物流輸送能力條件下采用較低轉速及較多鋸齒數。

表5 正交試驗結果
為驗證差速圓筒篩效果,依據仿真結果試制差速圓筒篩,與旋風分離清選系統配合使用開展臺架試驗,試驗臺主要由差速圓筒篩、拋揚機、旋風分離筒、離心風機、吸雜管道、糧倉、支架及配套液壓傳動系統組成,如圖10所示。差速圓筒篩中篩網由電機帶動,助流裝置由液壓系統驅動,轉速轉向均可調。試驗物料為油菜脫出物,油菜品種為華油雜62,油菜脫出物主要包括油菜籽粒、輕雜余及粗長雜余,粗長雜余包括短莖稈及莢殼(長度在20 mm以上),籽粒千粒質量為4.2 g,油菜籽粒、粗長雜余及輕雜余按質量比1∶1.5∶0.5混合均勻。
臺架試驗擬開展功能性驗證與對照試驗,功能性驗證差速圓筒篩與旋風分離清選組合的清選形式的可行性,對照試驗為對比差速圓筒篩與旋風分離清選組合作業和旋風分離清選單獨作業效果,分析增加差速圓筒篩以減少旋風分離清選負載;對照驗證中設置差速圓筒篩與旋風分離組合作業工況為試驗組,為先篩分后風選的清選形式;僅旋風分離清選裝置工作為對照組,為風選清選形式;2組試驗在清選效果即清潔率穩定在85%~90%,損失率穩定在5%~6%范圍內時,以離心風機轉速表征旋風分離清選裝置負載并作為對照試驗評價指標。

1. 差速圓筒篩 2. 籽粒提升攪龍 3. 旋風分離筒 4. 拋揚機 5. 吸雜管道 6. 篩下物提升攪龍 7. 風機 8. 調速裝置 9. 電機 10. 液壓馬達
功能性驗證試驗時將物料由篩下物提升攪龍喂入,差速圓筒篩與旋風分離清選裝置配合使用,以仿真結果最佳參數組合啟動清選系統,收集差速圓筒篩排草口、旋風分離筒出糧口及離心風機出口處物料并稱質量,篩分其中油菜籽粒并稱質量,計算油菜籽粒總損失率與清潔率分別為4.83%與85.7%,其中排草口處篩分損失率為3.97%。
對照試驗組按最佳參數組合設定差速圓筒篩相關參數,僅調節風機轉速,采用功能性驗證試驗的取樣方法多次試驗直至清潔率、損失率與對照組范圍相同后,記錄離心風機轉速。對照試驗結果表明:在相同清潔率與油菜籽粒總損失率范圍內,旋風分離清選系統風機轉速可由無差速圓筒篩前的2 300 r/min降至1 450 r/min,轉速降低36.9%,有效減少旋風分離清選負載。
2017年5月于華中農業大學試驗田開展田間試驗,如圖11所示。試驗對象為機直播華油雜62號油菜,平均種植密度為40株/m2,油菜籽粒、莖稈及莢殼含水率分別為23.47%、20.9% 和33.98%。試驗選取株高、密度等植株性狀一致性較好的區域進行田間試驗,在選定試驗區內劃分5個10 m的滿割幅區域作為測試區,機具在測試區內滿割幅作業,每次試驗前清理差速圓筒篩、拋揚機、糧倉內物料,單次試驗保證割茬高度一致,試驗過程中保持工況不變,前進速度2.9~3.6 km/h,作業效率為0.52~0.65 hm2/h。每次試驗后收集差速圓筒篩排草口、旋風分離筒出糧口、風機出口處物料并稱質量,篩分并稱量出各自出口物料內的油菜籽粒質量,計算得出差速圓筒篩篩分損失率、出糧口油菜籽粒清潔率和風機損失率,記錄清選系統液壓管路油壓與流量,計算清選系統功耗。因油菜成熟度不一致,田間溝壑較多、行走速度不穩定等因素導致整機喂入量波動,清選系統損失率平均值為5.9%,油菜籽粒清潔率平均值為84.4%,清選系統平均功耗為3.48 kW,差速圓筒篩作業順暢。

圖11 清選系統田間試驗
1)設計了一種與旋風分離清選系統配合使用的差速圓筒篩,對油菜脫出物進行初步篩分,可有效減少油菜聯合收獲機旋風分離清選系統負載并提高清選性能,滿足油菜聯合收獲清選需要。
2)基于EDEM仿真正交試驗結果表明:影響差速圓筒篩篩分效果的因素主次為助流裝置轉速、篩網轉速和助流裝置投影面鋸齒數,最佳參數組合為助流裝置轉速80 r/min、篩網轉速35 r/min及助流裝置投影面鋸齒數6個。
3)臺架及田間驗證試驗結果表明:在最佳參數組合條件下,差速圓筒篩與旋風分離清選系統配合使用時系統籽粒總損失率與清潔率分別為4.83%與85.7%,離心風機轉速可降低36.9%,減少旋風分離負載;田間試驗表明清選系統籽粒總損失率平均值為5.9%,油菜籽粒清潔率平均值為84.4%,清選系統平均功耗為3.48 kW,差速圓筒篩作業順暢。
差速圓筒篩助流裝置輸送物料過程中對物料的喂入量波動的適應性有待進一步探討。
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Design and experiment on cylinder sieve with different rotational speed in cleaning system for rape combine harvesters
Wan Xingyu1, Shu Caixia1,2,3, Xu Yang1, Yuan Jiacheng1, Li Haitong1, Liao Qingxi1,2,3※
(1.430070,; 2.410128,; 3.430070,)
Combine harvesters and windrowers were conventional machines for rape harvesting. Rape combine harvesters could simultaneously complete cutting, threshing, separation and cleaning at high production efficiencies. Cleaning systems played an important role in rape combine harvesters. The conventional rape combine harvesters were modified based on grain combine harvesters. The majority of cleaning system of combine harvesters was vibrating screen working with fan. Some changes like increasing the depth of header, adjusting reel position and transmission ratio, increasing active divider and so on were made to adapt to the rape plant in the field and there were still some problems like blocking of screen and the structure remained to be optimized. In conclusion, there were some problems like excessive vibration and relatively complicated structures due to vibration sieves in traditional combine harvesters. Cyclone separation was based on the principle of airflow cleaning. It was widely applied to grain processing, industrial dust removal and other fields. It could be used in rape combine harvesters taking the advantages of simple structures. However, short stems and pods made it hard for cyclone separation cleaning system to make the seeds clean. Adding a cylinder sieve was a solution to reduce the burden of cyclone separation cleaning system. The main limitation of the development of cylinder sieve was its relatively low efficiency. To reduce the burden of cyclone separation cleaning system and improve the efficiency of preliminary screening, a kind of cylinder sieve with promoting device in different rotational speed for rape combine harvesters based on EDEM was designed and relative experiments were carried out. As the primary process to separate the stems for the cleaning system, the cylinder sieve with promoting device in different rotational speed was mainly consist of the cylinder sieve, promoting device, the cover shell and the transmission device. The sieve was bent and shaped based on annular plane screen. The promoting device was mounted inside the cylinder sieve. Both of them were rotating around the same center axis. The hydraulic motor to provide power to the promoting device and to the cylinder sieve though the transition gear on transmission shaft. The rotation direction of cylinder sieve was changed by the gear transmission to realize the different rotational speed and direction of cylinder sieve and promoting device. Analysis and calculation of the rotational speed range of promoting device and cylinder sieve were carried out. Orthogonal experiments based on EDEM was obtained. The loss ratio and cleaning ratio of cylinder sieve was taken as the indexes while the rotational speed of sieve and the rotational speed and tooth number of promoting device were the factors. The optimal parameter combination was obtained. Test-bed and field experiments were carried out to verify the results of simulation. The simulation results show that the optimum combination of the parameters was 35 r/min and 80 r/min of rotational speed of sieve and promoting device respectively and 6 of the saw teeth in the projection plane of the promoting device. In addition, the loss ratio and cleaning ratio of cyclone separation cleaning system working with the cylinder sieve were 4.83% and 85.7% respectively while the rotational speed of the fan could be reduced by 36.9% under the condition of best combination of parameters. Field experiments were carried out in the experimental field of Huazhong Agricultural University in May 2017. The materials of experiments were rape planted by direct rapeseed planter. The average planting density was 40 plants/m2, and the water content of rapeseed, stems and pod shells were 23.47%, 20.9% and 33.98%, respectively. The working speed of 4LYZ-1.8 type rape combine harvester was 2.9-3.6 km/h and the working efficiency was 0.52-0.65 hm2/h. The average loss rate of rapeseed was 5.9% and the average cleaning rate of rapeseed was 84.4%. The average power consumption of the cleaning system was 3.48 kW. This research provided a reference for the improvement and optimization of cleaning system for rape combined harvesters.
agricultural machinery; design; experiments; rape; cleaning; cyclone separation; cylinder sieve; EDEM
萬星宇,舒彩霞,徐 陽,袁佳誠,李海同,廖慶喜.油菜聯合收獲機分離清選差速圓筒篩設計與試驗[J]. 農業工程學報,2018,34(14):27-35.doi:10.11975/j.issn.1002-6819.2018.14.004 http://www.tcsae.org
Wan Xingyu, Shu Caixia, Xu Yang, Yuan Jiacheng, Li Haitong, Liao Qingxi.Design and experiment on cylinder sieve with different rotational speed in cleaning system for rape combine harvesters[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(14): 27-35. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2018.14.004 http://www.tcsae.org
2018-01-08
2018-03-04
國家重點研發計劃項目(2017YFD0700405A);農業農村部科研杰出人才與創新團隊項目
萬星宇,男,湖北鐘祥人,博士生,研究方向為現代農業裝備設計與測控。Email:821786261@qq.com
廖慶喜,男,湖北江陵人,教授,博士生導師,主要從事油菜機械化生產技術與裝備等方面的研究。Email:liaoqx@mail.hzau.edu.cn
10.11975/j.issn.1002-6819.2018.14.004
S225.99
A
1002-6819(2018)-14-0027-09