Phan Van Nghi vd Dig Tap chi KHOA HOC & CONG NGHE 176(16): 25-30
MOT SO VAN DE KHI THIET KE, CHE TAG MAY EP - BONG BAO CAY NGO SAU BAM VA TRQN, C 6 N G SUAT 01 TAN/H
Phan van Nghi', Nguyin Thii Binh', Le Quang Duy', Cao Thanh Long' 'Trudng Dgi hgc Ky thudt Cong nghiep - DH Thdi Nguyen
^Dgi hoc Thdi Nguyen TOM T A T
B^i bdo nay trinh bay cdch thiic thiet kl may ep - dong bao hSn hgp than, la cay ngo sau bSm va trpn CO cong su^t 01 tdn/h de phii hpp vdi qui mo trang trai, gia trgi tgi cac tinh trung du, miln niii phia Bac. Cac vin de ve cau tnic va cdc thfing sfl dflng hpc mdy ciing nhu kha nang cong nghS ciia may dugc tinh toan, thiet kl tren co sd cdc mdy ep lam viec theo nguyen ly ep vit dim. Cdc van dl dgng lire hpc may dupe tinh todn theo cac phucmg phdp co hpc truyen thong. Ket qua van hanh thu nghiem khi ep - dong bao thii hon 10 tin nguyen li#u cho thiy mdy lam viec ddm bao c6ng suat thiet ke va phii hgp vdi chi tieu "Sudt tieu hao nang lugng" dl ra.
Tfr khoa: A/a^ ip - ddng bao; u ure cdy ngd; thitc dn cho dai gia sue vi mua ddng GIOI THIEU
Nhieu nghien cuu chi ra ring, thuc an xa ly tuoTig cho gia sue nhai lai chti yeu la co xanh, nhung nang suat va san lugng co xanh Igi thay doi theo thdi tifit, dgc bi^t la trong vu Ddng d mien mii cac tinh viing Tay Bac. Do vay, viec giai quyet du thii'c an xa cho gia siic nhai Igl trong vu Ddng tai cac tinh trong vting la het sue can thiet va cd y nghta quyet dinh trong viec phat trien dn dinh nganh chan nudi cac gia siic an cd nay [ 1 ].
Cac ngudn thtic an nay chii yeu la than, la cay ngfl, sin, mia, ram ra, v.v.. Trong dd, than cay ngfl sau thu hoach bap co ham lugng dinh duang cao va cd san lugng Idn [2].
Hien cd hai phuang phap u than cay ngd dugc ap dung: (i) Phuong phap ii thii cflng thuc hien dan gian nhung cho nang suat va chat lugng u khdng cao; (ii) Phucmg phap su dung hfl u cdng nghiep cho nang suit va chat lugng li cao nhung chi phi Idn, chi phu hpp vdi chan nudi cong nghiep. Ca hai phuong phap li tren diu chua phil hgp vdi mfl hinh chan nudi gia trai va trang trai nhd [2, 3],
Nhdm tac gia de xuat mdt phuang phap u urea than, la cay ngfl nhu sau: Hda tan urea, mufli va ri mgt dudng vao nude theo ty le nhat dinh. Sau dd, tudi nhd gipt dung dich
Tel. 0977 599357, Email: [email protected] v,
nay vao cay ngd da dugc bam theo qui each va trpn deu. Thuc an sau khi trdn dugc ep, nen, day ca ban khdng khi ra ngoai va dugc ddng goi trong bao kin khi. Bang each nay, cay ngd sau bam dugc cho vao may ep de vii'a ep CO ban khdng khi ra ngoai, viia khdng lam anh hudng den ket cau xa cua thuc an cung nhu giu' Igi dugc cac phu gia trong hdn hgp, Sau khi ep, hdn hgp duoc may ddn vao tiii ni Idng va dugc hiit chan khdng, han mieng tiil de dam bao lupng khi tdi da cdn lai trong ttii trong pham vi cho phep va hfln hgp khdng bj anh huoTig bdi moi trudng ben ngoai trong qua trinh bao quan.
Trong bai bao nay, nhdm tac gia chu ylu tap trung nghien cii'u thiet ke may ep hfln hgp th^n cay ngd vao bao cho qua trinh hiit chan khflng, han mieng bao va ii urea bao quan hfln hgp thiic Sn lau dai.
May ep va dong bao theo qui trinh neu tren can dam bao cac yeu cau sau:
+ Nang suat: Tdi thieu la 1 tan/h, tuong ducmg vdi 40 bao 25 kg.
+ Van hanh, sii dung may: May phai dugc thiet ke thuan tien cho ngudi van hanh, sii dung va bao dudng,
+ Khfli lupng rieng hfln hgp thii'c an: Khoang 300 kg/m^ sau ep,
+ Lugng khi con Igi trong hfln hgp: Nhd han 5% tdng the tich hdn hgp,
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Phan Vdn Nghj vd Dig Tap chi KHOA HQC & CONG NGHE 176(16): ^ 3 - J O + Kich thudc bao: Phil hgp vdi cac kich thudc
bao sin cd tren thi trudng,
+ Dp kin kbit bao: Bao sau khi ddng phai dam bao khflng dl khflng khi Ipt vao bao trong khoang thdi gian 6 din 9 thang,
+ Suit tieu hao nang lugng (lugng dien nang may tieu thu de san xuat 01 tan san pham): <
lOkW/tSn.
THIET KE M A Y EP - DONG BAO Chpn md hinh nguySn ly may
Cac du lieu dau vao ctia may bao gflm: Logi nguyen lieu la than, la cay ngd sau trpn vdi dp am khoang 25 din 30 %, khoi lugng rieng tir 150 den 180 kg/m"\ nang suat cap lieu tdi thieu la 1 tan/h.
Cac bfl phgn quan trpng ciia may bao gflm:
Bp phgn cap lieu, bp phan ep, bp phgn dinh lupng, bd phan ddng bao.
Lw3 chon phtfong phdp cdp lieu:
Hien nay, doi vdi loai lieu thd, rdi nhu hfln hgp than cay ngd va cac phy gia sau trpn, cd the su dung nhieu phuang phap cap lieu.
Nhom tac gia chpn phuong phap cap lieu theo day chuyen cho tfl hpp may n^y vl nd gan nhu khflng phat sinh them chi phi thiit bj va nhan cdng. Nhu vay, hfln hgp sau trdn se dugc xa thang xuong may ep - ddng bao.
Lua chgn phuang phdp ep hon hgp thdn cdy ngo vd phy gia:
Hi?n nay, cd nhilu phuong phap ep hfln hgp thuc an b5ng miy: Sir dyng may ep thuy luc, bang vit me - dai oc, ep bang may ep true khuyu, ep biing vit dim. May ep b5ng vit dim cho phep qua trinh ep lien tyc, cho chat lupng san phdm dflng deu, de bfl tri theo day chuyen. Tuy nhien, cac canh vit ciia may de bi mai mdn va cdng suat tieu hao dien nang Idn. Day chinh la hai van dl ca ban nhom tac gia phai giai quylt khi thiit kl may ep nay.
Qua cac phan tich tren, nhdm tac gia lua chpn phuang phap diing vit diin dl ep va ddng bao hfln hgp ihiic an vk phy gia sau trgn. Cflng dogn sti dung may ep vi't dim chti yeu dl diy 26
ca ban khdng khi ra khdi hdn hpp nhSm dam bao ket cau xa ciia than cay ngd, dam bao cac phu gia khdng bj mit mM khi ep va giam tieu hao dien nang so vdi qua trinh ep chgt (diy gan nhu hoan toan khdng khi ra khoi hfln hgp). Su dung may hut chan khdng kit hpp han kin miSng tiii de hut lugng khi con lai trong hon hgp va de dam bao thdc an khong bi anh huong bdi mdi trudng ben ngoai trong qua trinh li bao quan.
Lgu chgn phuong phdp dinh lugng:
Trong mpt gid, may ep va ddng bao phai tgo ra it nhat 40 bao vdi khfli lupng khoang 25 kg/bao, De dam bao mdi bao cd khoi lugng khoang 25 kg, can cd bp phgn dinh lupng sau ep.
Vdi cac bao thiic an chan nudi, dp chinh xac vl khdi lugng khflng y6u cau cao nhung yeu cau dan gian, nhdm nghien ciiru su dung phuang phap djnh lirpng bing thi tich khoi hfln hgp sau ep de thi8t ke bp phan djnh lupng cua may.
Vdi m§i khoi luang m can dinh lugng, cd:
_ n.D\L.r
(kg) (I)
(m) (2)
Can dting, coi hdn hop thuc an sau ep ia hlnh try vdi dudng kinh D (m); L (m) la chieu dai hinh try; y (kg/m^) la khdi lugng rieng banh lieu sau ep.
DS tgo ra duoc khfli lupng m (kg), mdi bao se chiia dogn hdn hpp sau ep cd chieu dai L theo:
Cdng thuc (2) dugc su dyng de xac dinh vj tri cQ' hgn tren may ep.
Lua chgn phuang phdp ddng bao:
Khoi hfln hgp sau ^p can duoc bao quan kin khi de dam bao qua trinh li urea dupe dien ra binh thudng cung nhu thuSn tien cho qua trinh bao quan, van chuyen, su dyng. Vdi yeu cau dd, mipng bao phai dam bao dp kin khit va ben lau.
Hien nay, thudng sti dyng cac kieu ddng bao sau: Ddng hop, ddng bao bang thanh k^p,
Phan Van Nghj vd Big Tap chi KHOA HQC & C6NG NGHE 176(16): 25-30 ddng bao bang chi may, ddng bao bang quan,
ddng bao bang han nhiet mieng bao. Trong do, han nhiet la phuang phap cho dp kin khit va nang suat cao, tuy nhien vat lieu lam bao cSn lim tti nhua PE. Vdi yeu cau cao ve dp kin khit bao sau ddng va nang suat dong bao, nhdm nghiSn cdu lua chpn kieu ddng bao bang han nhiet.
Kich thuoc bao can thda man cac cdng thuc sau:
A> va / / > ^ ^ - i - A L (cm) (3) 2 A .y
Vdi A va H (cm) lan lugt la chieu rdng va chieu cao cua bao d trgng thai xep hoan toan.
Cdn AL la chieu cao phan them so vdi chieu cao ciia khoi hon hgp ep de cd the ddng bao de dang.
Hlnh 1. Kich thuac bao gdi cho hdn mieng bao Thiet ke phan ep hon hpp thirc an Thiet ke dgng hgc mdy:
Qua trinh ep hdn hgp thuc an sau trgn thanh khdi va dun vao bao chiia dugc thuc hien theo nguyen ly the hien tren hinh 2.
Hinh 2. Sa do nguyin ly may ip vU dun Hdn hgp thtic an dugc dau ra cua may trfln cap vao pheu va dugc vit ep di chuyen va 6p chat vl phia khudn dl tgo ra lien tuc khoi hon hgp hinh tru co dudng kinh D. Bao dugc cdng nhan Iflng vao khudn ep va qua trinh ep dun se day hon hgp vao bao va day bao ra vj tri hiit chan khdng. Bao chiia hfln hgp se dugc cdng nhan thuc hien qua trinh hut chan khdng va han mieng bao tren may hut chan khdng chuySn dung (cd san tren thi trudng).
v l mat ddng hgc bd phan ep dim: Truyen dgng dugc dSn dgng tu dgng ca qua hop giam
toe va truyen den true vit ep. So do dpng hpc ciia phiin ep duoc the hien tren hinh 3.
(M)
nv
1 2^1---''3
'^mk
Iv
Hlnh 3. So do cdu trite dgng hoc phan ep Thong s6 dpng hpc quan trpng nhat cua phan ep chinh la toe do quay ciia true vit ep (Uv), duoc xac djnh nhu sau: riy = nj^..iy Va n„ P
Vai:
47D,.'.S, •ii.-r-l' (4) [4]
+ P: Nang suat ep, P - 1000 lig/h + Dv: Duong Itinh ngoai cua vit ep, chon Dy
= 390 mm
+ Sib: Buoc trung binh ciia vit ep
S. = -^ vdi S| la cac budc thay dfli trSn 4
tryc vit 6p. True vit ep dugc thiet ke vdi budc giam din theo chieu tien ve khudn ep de tao dp nen cho hdn hgp, lay S,b=l90 mm;
+ y: Khdi lugng rieng ciia hdn hpp trudc ep, Y=160kg/m^
+ (p: H? sd cung cap ciia may, lay cp=0,288;
+ Chpn dpng ca dien cd ndc= 1450 vg/ph;
Tir (4) cd nv=39 vg/ph va:
• -"y ^ 39 _ 1 ' ' " " , / . ~ 1450 ~ 3 7 '
Vdi gia trj he so dieu chinh nay, chia truyen dOng giam toe thanh 2 phan: Giam tdc qua hpp giam toe vdi ty sd truyen (chpn hpp giam tflc tieu chuan) va sir dyng bp truyen dai nfli tir dpng ca din hop giam tflc vdi ty sd
.- ^ \. 1 giam toe la .
1,17 Tinh loan lita chgn dong ca:
Ddng CO dugc Iga chgn phai dam bao cdng suat cho tryc vit ep de vit ep nen va day khoi 27
Phan Van Nghi va Big Tgp chf KHOA HOC & CONG NGHE hdn hgp thuc an tir xi lanh, qua cfln ep, khudn
ep va dfln vao bao chua. Nhu vay, cdng suat nay phai th^ng dugc cdng suat can do cac thanh phin luc can tao nen, bao gdm; Luc can nen (do budc vit thay ddi); luc ma sat giffa hon hgp lieu va tryc vit ep, Idng xi lanh, long cdn 6p va khufln ep.
Mfl men xoan tren true vit ep xac dinh bdi cdng thuc: M^= F^s.R [4].
Trong dd: Fms la luc ma sat giifa hdn hgp va vit ep, N; R la ban kinh chan true vit, mm (Ldy R= 100 mm);
Fms = Pmaji-f-F voi Pmax la ap suat lon nhat tac dyng len khudn (P„ax = 0,2 MN/m^ theo so lieu thuc nghiem); f la he so ma sat giua hfln hgp thuc an va vit ep (f=0.65 tti so lieu thuc nghiem); F la dien tich mat cit ngang khudn ep:
„ n.£>' 3,14.370' ,n-7A^^^ , 2, F = = ~ = 107466,5 (mm )
4 4 (Chpn dudng kinh khufln ep la D=370 mm), Vgy: F^, = 0,2.0,65.107466,5 ~ 13970 N Va:Mx =13970.0,1 = 1397 Nm Mgt khac : M^ = 2^^^ Nm [5]
Vdi: N la cdng suat can thiet tren true vit ep, kW; Uy la sfl vdng quay ciia tryc vit ep, nv=39 vg/ph.
^ . , . M^.ny 1397.39 . _ Do vay: N = —'—^ = = 5,7.
9550 9550 Cdng suat cua dpng co dien xac djnh theo cdng thtic sau: A^^ = — (kW) [5] N
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Vdi: T] la hieu suat dan ddng tir dpng co din true vit ep, lay TI=0,85.
Cac thdng sd ciia true vit ep dugc the hien tren hinh 4.
Do vay: A''^^^. ^ 5,7 ' 0,85 ^6,7 (kW).
Nhu vay, chgn ddng ca truyin din cho tryc vit ep la ddng co dien khdng ddng bp 3 pha cd cflng suat 7,5 kW, tflc dp quay 1450 vong/phiit.
Thiet ki phan vit ep:
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Hinh 4. Cdc thdng sd cua true vit ip Cac thdng sd cua vit ep la budc vi't, gdc nang dudng ren vit, dudng kinh dinh va ducmg kinh chan true vi't ciing nhu chieu day canh vit. Trong dd, budc vit va goc nang dudng ren cua true vit la hai thdng sd quan trpng nhSt + Buac vit vd goc ndng ditdng ren cda triic vit ep: De tryc vit cd the nen dugc vgt lieu, co the che tao budc vit giam dan tir ciia tiep liSu den khudn ep hoac che tao budc vit khong doi nhung thay dfli chieu sau ranh vi't nho dan v^
phia khudn ep. Nhdm nghien ciiu lira chpn phucmg an giam dan budc vit va su dung giai phip lap ghep tirng nica budc vit co budc khac nhau len true vit de thuan tien cho viec che tao.
De ep sa bfl hfln hgp thtic an la thSn, la cay ngd va phy gia, lua chgn tryc vit ep gom 4 budc vit giam dan la S|, S2, S3 va S^. Trong do, budc vit dau tien Sj dugc xac djnh dira vao dudng kinh dinh Dy va goc nang dudng ren p. De tryc vit ep dim lieu di mdt each lien tyc thi gdc nang p phai tihd han gdc ma sat 6 cua vgt lieu vdi true vit (0=arctan(f)=arctan(O.65)=33°) [4], Voi dudng kinh dinh true vit dugc chgn la Dv=390 mm, lay S,= 220,82=200, S3=180, S4=160 mm.
Nhu vgy, cd 8 nira budc vit dugc thiet ke tuong t\r nhu mia budc vit dau tien dugc the hien tren hinh 5.
Hinh 5. Cdc thdng so cua nua buac vit S,
Phan Van Nghj vd Dtg Tap chi KHOA HQC & CONG NGHE 176(16): 25-30 Cac canh vit sau thiet kl duac kiem bin bSng
each md phdng ting suat va chuyen vj biing phan mim Catia V5, dugc thi hien tren hlnh 6.
«
Hinh 6. (fng sudl tren cdnh vit Thiel ke xi lanh buong ip:
Xi lanh buong ep cd dang ca ban la ong try bao lay true vit, lim nhiem vu chiia hdn hgp thiic an can ep va ket hpp voi tryc vit ep de day ep thiic an vao khudn ep. De hon hgp dugc vit ep day di ma khdng dinh vao canh vit, trong Idng xi lanh can thiet ke cac gan dgc nhu hinh ve 7. Do tinh chat ctia cac dgng lieu nay la he so npi ma sat giiia cac thanh phan lieu vdi nhau lufln Idn hon he sfl ma sit gifla lieu vdi kim loai lam true vit ep nen khi true vit quay, ddng Ii6u khflng bi quay theo ma nd t^' vao cac ranh tren xi lanh va trupt, ep ve phia khudn ep. KSt cau va kich thudc ciia phan xi lanh budng ep duoc the hien tren hinh 7.
Hlnh 7. Xi lanh buong ep Thtit ki con ep:
Nhiem vu ciia cfln ep la tang them dp ep chat cho khdi hdn hpp thtic an sau khi nd da dugc nen chat mdt phan tu cac canh vit. Cac lire tac dyng I6n khoi hdn hgp tir be mat cfln ep vdi gdc cfln a duoc the hien tren hinh 8.
Hinh 8 Luc lac dung lu con ep len hdn hgp N la ap luc phip tuyen cua mat cdn tac dung len hdn hgp N tao ra thanh phan can dpc tryc
(6) Qi len khoi hdn hpp va can chung theo phuong chuySn d0ng dpc true tgo ra su nen Sp len khoi hdn hgp:
Q = A'^.sina = p.iS'.sina (5) Vdi p (N/mm^) la ap luc don vi cua khoi hfln
hop len be mat cua cdn ep va S la dien tich xung quanh trong Idng cfln ep.
Ngoai ra, khdi hdn hgp cdn chiu luc can dgc tryc Q2 do lyc ma sat Fms cua thanh con tac dung len khdi hdn hgp:
Qj = F„,^.. c o s (X = N.f. c o s CC
= p.S.f .cos ce
Nhu vay, tflng luc phan cfln ep tac dyng len khoi hdn hgp theo chilu tryc va ep khdi hfln hgp dugc xac djnh:
Q^Q\+Qi = p-S.isma + f.co?,a) D + d ^ , . . „ . (7)
^ .p.n.L.(sma:-i-/.cosff) Vdi D, d va L lan lugt la dudng ki'nh dau Idn, dudng kinh dau nhd va chieu dai cfln ep.
Bang cac thuc nghiem thay ddi cac gia tri gdc cdn a va xac djnh dp nen chat ciia hdn hgp diu ra, ket qua gdc cfln va cac thdng sfl hgp ly Ciia cdn ep nhu sau: Gdc cdn a=2°, chieu dai doan cdn ep L=450.
K H A O NGHIEM M A Y E P - D 6 N G BAO May ep - dong bao da thiet ke va che tgo dugc tien hanh chgy thii ep va ddng bao han 10 tan cay ngfl sau bam, trgn vdi cac ket qua cu the nhu sau:
- Nang suit: Dat tii-1,2-1,3 tin/h;
- Cuong dg dong dien Idn nhat tren mpt pha vao dflng ca dSn: ln,a« < I2A (tuong duang vdi suat tieu hao nang lugng < 10 kW/tan) - Cac canh vit va gSn dgc trong long xi lanh d trgng thai binh thudng, dam bao cac yeu cau ky thugt de ra.
KET QUA VA T H A O L U A N
Tir qua trinh van hanh khao nghipm cho thay:
Cimg vdi may trdn, may hiit chan khdng, may ep - ddng bao da tao thanh 01 day chuyen hoan chinh dat nang suat 01 tan/h, hogt dpng 29
Phan VSn Nghi vafi/g Tgp chi KHOA HQC & C 6 N G NGHE 176(16): 25-30 dn dinh va co dfl tin cay cao. DS.y chuyen da
dgt cac chi tieu ky thuat de ra.
Tuy nhien, d l giam gia thinh h? thdng han nira, nhdm nghien cdu se tap trung vao viec giam them cflng s u i t tieu thu dien cua may ep - d d n g bao.
Cac van d l v l anh huflng ciia budc vit Sp, he so ma sat giiia hdn hpp lipu va tryc vit ep, gdc cfln ep den nang suat ep, dp nen san pham dau ra se ducrc trinh bay trong cac bai bao va cong trinh khoa hpc tiep theo.
Ldi CAM ON
Nhdm tac gia xin giri Idi cam sau sac den Van phdng Chucmg trinh Khoa hpc va Cdng nghe trpng diem cap N h a nude giai doan 2013- 2018 "Khoa hpc va Cdng nghe phyc vy phat triln bin viing viing Tay Bac", ma so:
KHCN-TB/13-18, DH Quoc gia Ha Ndi, DH Thai NguySn va DNTN Thai Long da tai trg kinh phi va tao mpi dieu kien tflt nhat de nghien ciiu dugc hoan thanh.
TAI LIEU T H A M K H A O 1. Biii Quang Tuan, Nguyen Xuan Trgch, Do Diic Lyc (2008), "Anh hudng ctia m6t s6 yeu t l dSn vi$c sii dung rem vk than cSy ngfi lam thiic an cho trau bo tgi cac tinh phia Bac", Tgp chi khoa hgc vd phdt triin, tSp VI, sfi 1, tr.47-51.
2. Nguyen Hung Quang, Mai Anh Khoa, Phan Dinh Tham, Stephen Ives (2014), "Assessment of the utilization ofthe natural grass and agriculture by-products in cattle production in Son La - Vietnam", NIAS — Journal of Animal Science and Technology. Vol.46 - February, pp 30-38.
3. Nguyin Thu Phucmg (2009), Ddnh gid kha ndng sinh trudng vd dnh hudng cua cdy ngd u chua den ndng sudl, chdl lupng stta ciia ddn bo siia nudi lai huyin Ddng Triiu tinh Qudng Ninh.
Luin v3n thac sT khoa hpc n6ng nghifip, chuySn ngdnh chan nuoi dfing vSt, ma so 60.62.40, tnrimg DH Nong Lam, DH Thai Nguyen.
4. Ho Le Vien (2003), Cdc mdy gia cdng vdt lieu ran vd deo. tap 2, Nxb Khoa hoc va KJ thuat.
5. Trinh Chit, Le Van Uyin (2006), Tinh todn thiit ki hi ddn ddng ca khi. tgp I, Nxb Giao due.
A B S T R A C T
D E S I G N AND M A N U F A C T U R E O F A P R E S S E D - P A C K A G I N G M A C H I N E W I T H C A P A C I T Y O F 01 T O N / H F O R C O R N S T A L K S
A F T E R C U T T I N G A N D M I X I N G
Phan Van Nghi", Nguyen Thai Binh', Le Quang Duy', Cao Thanh Long^
' University of Technology - TNU ' Thai Nguyen University This paper presents how to design a pressed - packaging machine after cutting and mixing of com stalks with a capacity of 01 ton/h to ill farm size in the midland and mountainous provinces in the North of Vietnam. The problems of kinematics, parameters of motions and technological capabilities of the machine are calculated, designed on the basis of screw pressing machines.
Machine dynamics problems are calculated according to traditional mechanical methods. The test results of more than 10 tons of raw materials indicate that the machine has been working at its designed capacity and in line with the indicator " Specific energy consumption rate".
Key words; Pressed — packaging machines, bagging machines, corn urea composting, feed for catties in the winter
Ngdynlign bdi: 01/11/2017; Ngdypltdn biin: 23/11/2017; Ngdy duyitdang: 05/01/2018 Tet: 0977 599357, Email: pha,mghiQ>inul edu v,
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