Design of a New Soil-Tuber Separation Device on Potato Harvesters

Size: px

Start display at page:

Download "Design of a New Soil-Tuber Separation Device on Potato Harvesters"

James Walker
5 years ago
Views:

1 Dsign of a Nw Soil-Tubr Saration Dvic on Potato Harvstrs Gaili Gao *, Dongxing Zhang, and Jun Liu Collg of Enginring, China Agricultural Univrsity, Bijing 83, P.R. China ggl965@6.com, ggl@cau.du.cn Abstract. A nw soil-tubr saration dvic on otato harvstrs has bn dvlod. It mainly comriss a linar motor, a rctangular scrn, a fram, four suorting srings and four damrs. It is th first tim to roos that th soil-tubr saration dvic is drivn by th linar motor. Forcs acting on th rctangular scrn ar found. A diffrntial quation for dscribing th forcs is st u. An quation for valuating xciting forc of th linar motor has bn drivd from th solution to th diffrntial quation. An quation of th factors affcting on th dvic rsonanc has also bn obtaind. Additionally, an quation for valuating th dformd magnitud of th daming srings in th damrs has bn drivd. And finally a motion simulation xrimnt for th rctangular scrn on a otato harvstr has bn don with th Matlab/Simulink modul. Th xrimnt xrssd that th mthod is fasibl. Kywords: Potato harvstr, Soil-tubr saration, Saration dvic, dynamics analysis. Introduction Many mthods wr usd to sarat soil from otatos. Howvr, fild sarating oration causd most damag to otatos. Curl (978) invntd a tubr harvstr having a rimary bd and a scondary bd. Th scondary bd is ncomassd by a dvining chain []. Hyd t al. (983) suggstd this ty of tubr harvstr could b quid with a systm for controlling th dth of matrial on th rimary chain by automatically adjusting chain sd. Th systm rovids uniform flow of matrial from th rimary to th scondary chain ovr a wid varity of fild conditions and ground sds []. Anothr similar otato harvstr was dscribd by Wl (989). It comriss a scrning convyor blt and an lvator disosd aftr th scrning convyor blt. Th lvator is formd from a doubl convyor having an intrnally rotating bar-ty convyor blt with narrow onings and an xtrnally rotating bar-ty convyor blt with wid onings [3]. In ordr to imrov soil limination, shaking of th convyor chain (bd) in a vrtical or horizontal dirction was alid to * Corrsonding author. D. Li, Y. Liu, and Y. Chn (Eds.): CCTA, Part III, IFIP AICT 346,. 64 6,. IFIP Intrnational Fdration for Information Procssing

2 Dsign of a Nw Soil-Tubr Saration Dvic on Potato Harvstrs 65 th otato harvstrs (Woodruff t al., 984) [4]. In addition, a rssur blt mchanism orating on th surfac of th rimary convyor was roosd (Misnr t al., 989) [5]. Howvr, du to friction btwn chain (bd) or soil and otatos, th otatos wr gratly damagd. A siml mchanical sarator was dvlod by Fllr t al.(985). Th machin utilizs th diffrnc in th rstitution cofficint btwn otatos and soil clods.both otatos and clods ar drod from a fd convyor onto a rvolving stl rollr whr th rsulting trajctoris caus th otatos to nd u at a mor rmot location than th clods. Th sarator can not b usd to sarat stons from th otatos [6]. Gan-Mor t al.(986) usd a aroriat lastic lat for rducing th rstitution cofficint of stons without changing that of th otatos or clods so that th stons wr saratd [7]. Howvr, th imact btwn th stl rollr or lat and otatos causd damag to otatos. Bouillon (983) roosd anothr otato harvsting aaratus. Its sarator has thr rimary cylindrical cags, followd by thr scondary cylindrical cags and thn thr rubbr-coatd cylindrical cags. Th sarator can rmov most of th dirt and brak u th dirt clods [8]. Howvr, much of mchanical injury was causd by th convyor quimnt. In addition, grat owr rquird to driv th sarator was consumd. Misnr and McLod (989) also tstd a mchanism which consists of a combination of disc-shad clod rollrs and cylindrical brushs. Th mchanism ssntially liminatd th loos soil and, on th avrag, 6% of th stons and 47% of th clods [9]. Th objctiv of this rsarch is to dvlo a nw soil-tubr saration dvic on otato harvstrs. Th dvic can rduc otato damag, rduc th owr rquird to sarat soil from otatos, and imrov th saration fficincy. Scific work is dividd into thr arts: () Modl of soil-tubr saration dvic. () Dynamics analysis for soil-tubr saration dvic. (3) A motion simulation xrimnt for a rctangular scrn. Modl of Soil-Tubr Saration Dvic A modl of a soil-tubr saration dvic on a otato harvstr is shown in Fig.. Th dvic mainly comriss a linar motor, a rctangular scrn, a fram, four suorting srings (two of th suorting srings arn t shown in Fig. ), and four damrs. Th rctangular scrn consists of quidistantly sacd bars at th cntr and a conncting lat on ach sid of th bars. Th fram has four insid slidways and two bottom suorting lats. Th motionlss art of th linar motor is hld onto th fram by conncting comonnts (th conncting comonnts arn t shown in Fig. ). Th motion art of th linar motor is attachd to th conncting lats of th rctangular scrn by anothr conncting comonnts (th conncting comonnts arn t shown in Fig. ). Th rctangular scrn is connctd to th suorting lats of th fram by th four suorting srings. Th fram is quid with th four damrs ach of which has a sring, a guid, and a sring covr (th sring covr isn t shown in Fig. ).

3 66 G. Gao, D. Zhang, and J. Liu Th angl btwn th datum lan of th dvic and th lvl is β. Whn th dvic works th rctangular scrn drivn by th motion art of th linar motor vibrats u and down in inclind dirction along th four slidways of th fram and th four guids of th damrs.. β OHYHO (a) (b) Fig.. A modl of a soil-tubr saration dvic: (a) front viw; (b) K dirction viw xct th linar motor.-linar motor; -rctangular scrn; 3- suorting srings; 4-fram; 5-damrs; 6 -damrs. Arrow dnots dirction of travl. 3 Dynamics Analysis for Soil-Tubr Saration Dvic 3. Evaluation of Exciting Forc Th forcs xrtd on th rctangular scrn in vibrating dirction ar (Fig. ): xciting forc of th linar motor acting on th to of th rctangular scrn, F ; suorting forc of th suorting srings acting on th bottom of th rctangular scrn, N ; daming du to surfac friction from th motion of th rctangular scrn, ; and comonnt of gravitational forc of th rctangular scrn that includs th tubr and soil on it, mg cos β. mgsinβ U HFW DQJXO DU VFU HHQ N F ' F mg cos β x O mg cos β β β mg Fig.. Forcs acting on a rctangular scrn in vibrating dirction

4 Dsign of a Nw Soil-Tubr Saration Dvic on Potato Harvstrs 67 Using vibrating dirction as x axis and utting th stagnation oint O at quilibrium osition (Fig. ), th suorting forc in th x dirction may b dscribd as follows: N = ik( x + λs ). () Whr i is numbr of th suorting srings, K is stiffnss of th suorting srings ( N m ), λsis th dformd magnitud of th suorting srings at quilibrium osition( m ), x is th distanc of th rctangular scrn from th quilibrium osition ( m ). Th xciting forc is dfind by: F = F sinωt. () Whr F is amlitud of th xciting forc ( N ),ω is angular frquncy of th rad s ), t is th xciting tim ( s ). xciting forc ( Th daming may b xrssd as follows []:. (3) F = γ x Whr γ is daming cofficint ( N s m ). Basd on Nwton s law of motion th diffrntial quation for dscribing th forcs acting on th rctangular scrn is: F + mg β N F = m x Whr m is mass ( kg ), g is acclration of gravity ( m cos. (4) ), β is th angl btwn th datum lan of th dvic and th lvl ( dg.). At quilibrium osition mg cos β = i K λs. (5) Substituting quation (),(),(3),and(5) into quation (4) and rarranging trms givs: If w dfin s m x + γ x + i K x = F sinω t i K F n = γ, = and q = m m m thn quation (6) bcoms:. (6). (7) x + n x + A articular solution to quation (7) is: whr x = q sinω t x ( t) = B sin ( ω t ψ ). (8) B q =. (9) ( ω ) + 4n ω

5 68 G. Gao, D. Zhang, and J. Liu and nω ψ = ω tg. () Rarranging quation (9) yilds: If w dfin q B = ω + q F ω B = =, λ = and ζ = i K thn quation () bcoms: B ( λ ) + ( ζ λ) n n ω. () B =. () = ikb λ + F ζ λ. (3) or ( ) ( ) If w dfin θ = B B thn quation () bcoms: θ =. (4) ( λ ) + ( ζ λ) Diffrntiating quation (4) with rsct to λ and stting th drivativ qual to zro, w obtain: λ = ζ. (5) or ω = n. n <<. = i K m ω. (6) Equation (6) is th rquirmnt of occurring rsonanc for th dvic.

6 Dsign of a Nw Soil-Tubr Saration Dvic on Potato Harvstrs 69 Basd on daming thory th daming cofficint is []: γ = 4. (7) πω B i K m Substituting quation (7) into =, = ζ =, rarranging trms givs: n ζ = γ m F π ω B ikm and n. (8) Substituting quation (5)and(8) into quation (3) yilds: 4 F = ω 4 ( π ω) mb ( π B) ikm F. (9) Equation (9) is usd to valuat th amlitud of th xciting forc. Equation (), (6) and (9) is alid to valuat th magnitud of th xciting forc. 3. Analysis of Daming Th forcs xrtd on th rctangular scrn at th lan rndicular to th vibrating dirction ar (Fig. 3): comosit rssur forc of th two 5-damrs, N ; comosit rssur forc of th two 6-damrs, N ; racting forcs of th fram, N and N ; and comonnt of gravitational forc of th rctangular scrn that includs th tubr and soil on it, mg sin β. N N mg sin β U HFW DQJXO DU VFU HHQ ' N ' N Fig. 3. Forcs acting on a rctangular scrn at th lan rndicular to th vibrating dirction

7 6 G. Gao, D. Zhang, and J. Liu Th comosit rssur forc of th two 5-damrs is dtrmind as: N =. () k x Whr k is stiffnss of th sring in th 5-damr ( magnitud of th sring in th 5-damr ( m ). Th comosit rssur forc of th two 6-damrs is dtrmind as: k x N m ), x is th dformd N =. () Whr k is stiffnss of th sring in th 6-damr ( N m ), x is th dformd magnitud of th sring in th 6-damr ( m ). Th racting forcs may b xrssd as:. () N = Th daming may also b valuatd by: k x. (3) N = N + mg sin β F = N μ μ. (4) + μ N + μ N + N Whr μ is friction cofficint btwn th 5-damr or th 6-damr and th rctangular scrn. It is also th friction cofficint btwn th slidways of th fram and th rctangular scrn. Substituting quation (),(),(),and(3) into quation (4) and rarranging trms givs: From quations (5). (5) F = 4 μ ( k x + k x ) + μ mg sin β k x μ m g sin β + k x =. (6) 4μ Equation (6) is alid to valuat th dformd magnitud of th daming srings in th four damrs. 4 Rsults and Discussion A motion simulation xrimnt for th rctangular scrn on a otato harvstr has bn don with th Matlab/Simulink modul. Th aramtrs of th xrimnt ar: () i = 4, m = 3kg, B =.5m, ω = π rad / s, = 8 N. () i = 4, m = 5kg, B =.5m, ω = π rad / s, = 8 N. (3) i = 4, m = 8 kg, B =.5m, ω = π rad / s, = 8 N.

Dsign of a Nw Soil-Tubr Saration Dvic on Potato Harvstrs 6 Th xciting forc F was calculatd in quation (), (6) and (9). Th simulation rsult was as shown in Fig.4.

8 Dsign of a Nw Soil-Tubr Saration Dvic on Potato Harvstrs 6 Th xciting forc F was calculatd in quation (), (6) and (9). Th simulation rsult was as shown in Fig.4. W could s that th motion trail of th rctangular scrn is corrct. Fig. 4. Dislacmnt-tim curv for th rctangular scrn on a otato harvstr In ractic, th stiffnss k, k and th dformd magnitud x, x of th srings in th damrs could b adjustd. Thrfor th aroriat daming could b obtaind in quation (5). Th motion simulation xrimnt xrssd that th mthod is fasibl. 5 Conclusions () A nw soil-tubr saration dvic on otato harvstrs has bn dvlod. It is th first tim to roos that th soil-tubr saration dvic is drivn by th linar motor. () Forcs acting on th rctangular scrn ar found. A diffrntial quation for dscribing th forcs is st u. An quation for valuating xciting forc of th linar motor has bn drivd from th solution to th diffrntial quation. An quation of th factors affcting on th dvic rsonanc has also bn obtaind. Additionally, an quation for valuating th dformd magnitud of th daming srings in th damrs has bn drivd. (3) A motion simulation xrimnt for th rctangular scrn on a otato harvstr has bn don with th Matlab/Simulink modul. Th xrimnt xrssd that th mthod is fasibl.

9 6 G. Gao, D. Zhang, and J. Liu Rfrncs. Curl, R.B.: Potato harvstr. U.S.Patnt, No.4667 (978). Hyd, G.M., Thornton, R.E., Woodruff, D.W.: Potato harvstr rformanc with automatic chain-load control. Transactions of th ASAE 6, 9 (983) 3. Wl, J.: Potato harvstr. U.S.Patnt, No (989) 4. Woodruff, D.W., Hyd, G.M., Thornton, R.E.: A rliminary analysis of a high-frquncy soil riddling dvic for us on otato harvstrs. Transactions of th ASAE 7, (984) 5. Misnr, G.C., McLod, C.D., McMillan, L.P.: Imrovd dsign for soil saration and vin rmoval mchanisms on a otato harvstr. Al. Eng. Agric. 5, 5 56 (989) 6. Fllr, R., Margolin, E., Zacharin, A., Pastrnak, H.: Dvlomnt of a clod sarator for otato acking houss. Transactions of th ASAE 8, 9 3 (985) 7. Gan-Mor, S., Zacharin, A., Gaili, N., Fllr, R., Margolin, E.: Absorbing ston imact to nabl saration from otatos. Transactions of th ASAE 9, (986) 8. Bouillon, A.M.: Potato harvsting aaratus. U.S.Patnt, No (983) 9. Misnr, G.C., McLod, C.D.: A rsourc fficint aroach to otato-ston-clod saration. AMA Agric. Mch. Asia Afr. Lat. Am., (989). Zhang, Y.: Mchanical Vibration. Tsinghua Univrsity Prss, Bijing (7)

Design of a New Soil-Tuber Separation Device. on Potato Harvesters

Design of a New Soil-Tuber Separation Device on Potato Harvesters Gaili Gao*, Dongxing Zhang, Jun Liu College of Engineering, China Agricultural University, Beijing 83, P.R.China. *Corresponding author,