NGHIEN CUU - TRAO DOI Nghien cuu m o t N H A M V A so giai p h a p N A N G T U O I C O O T H O thiet k e v a k e t K H A N A N G C U A M A Y B cau L A M O M V I E C B U N (*) NGUYEN NGOC M I N H buong xoan tbi g i i tri toi thieu, nhung phai dam bao su luu thong cac hat cung van chuyen Khi giam khoang each giam den gid tri tdi thieu, hieu suat tdng duac tir 5% den 8%, mdn giam duac gdn hai lan T6M TAT: Bai bao dUa mot so bien phap thiet ke va bien phap ket cau doi vbi may bom van chuyen bun Ket qua nghien cufu dupe ap dung thiet ke may bom bun, nham thiet ke che tao may bom bun dam bao cac tfnh nang hoat dong, nang cao tuoi tho * Tinh chpn gdc dat canh P i > P toi uu Gdc dat canh tai loi vao banh cong tic Pic: Doi vdi miy bom bun, gdc Pic anh huong lbn den su mai mon mep vao cua canh Gdc Pic neu nho se lam ting k h i nang va dap Xu hudng l i lam ting Pic Tuy nhien, phii luu y de phdng hien tupng xim thuc Pic qui lbn Dp lbn cua Pic dupe xic dinh theo kha nang chong m i i mdn tai mep vao cua la canh I DAT VAN DE May bom bun lam viec moi truong hon hop hai pha ran long, cd tinh mai mon, tinh chat moi truong Goc dat canh tai loi binh cong tic: Doi vbi may lam viec anh hudng rat Idn den cac chi tieu lam viec bom bun, gdc P2C dupe xic dinh theo kha nang chong ciia may Viec nghien cuu, dua cac giai phap thiet ke toi uu va giai phap giam thieu mai mdn qua trinh mai mdn cua mep l i canh binh cong tie, dp lbn cua hoat dong cua bom bun ddng vai trd quyet dinh den cac P dupe de nghi: lay P c=(16° - 22°) Theo t i i lieu [6] kha nang lam viec cung nhu tuoi tho ciia bom bun - Doi vbi may bom cb lbn N>100 kW, thuong dung II CAC GIAI PHAP THIET KE VA de bom hat r§n cd d^ > 10 mm, p > 3000 kg/m , C > K E T C A U N H A M N A N G C A O K H A 20% nen chpn p, = 30 * 40° - Doi vbi may bom co tnmg binh lOOkW > N > NANG L A M VIEC V A TUOI T H O CUA 50kW, diing de bom hat ran co kich thuoc d tir 5mm MAY BOM BUN CAT den 10mm, p = 2000 kg/m , C < 30% nen chon Gidi phap thiet ke P, = - ° 2C hr v ta hr Hau het cac may bom ly tarn bom ddng hon hop ran-ldng duoc thiet ke che tao tren co so may bom ly tim bom nude sach va cb hieu chinh them ve mot so thong so ket cau va vat lieu de bom dong hon hop ran-lbng Tuy nhien, thiet ke bom hat ran, bom bun, yeu to quan nhat de la viec phai vua dam bao kha nang lam viec, kha nang thoat ciia bo phan dan ddng (binh xe cong tic, buong xoan) v i dam bao kha nang chong mon cua cac chi tiet de tri tudi tho lau dai cua bom Dudi day la mpt so gai phap nham thba man yeu cau * Hoin thien bp phan dan dong cua may bom bun bang each giim khe hb giua banh cong tie v i mui (*) Khoa Co khi, Truong Dai hoc Thuy Loi v - Doi vbi miy bom co nho N < 50kW, diing de bom hat ran cd kich thuoc d^ < 5mm, p < 3000 kg/ m , C < 20% nen chpn p, = 25 4- 30° hr v - Theo L.C Givotopsky, de nghi lay chieu day la canh theo cong thiic = (0,1 -f- 0,13^ c * Lua chpn chieu day canh dan h c Tuoi tho cua binh cong tic bom bun phu thuoc vio chieu diy canh dan Vbi banh cong tic bom bun chieu diy canh dan, phai duoc tinh toan cu the Khi chieu diy canh dan lbn thi quy dao hat se va dap vio canh sbm hon so vbi binh cong tic co chieu day nhd Vay, khong nen chpn canh co chieu diy qua lbn, doi vdi moi loai may bom, can chpn chieu day canh phii hpp vbi ddng chay hai pha TAP CHI CO KHI VIET NAM ••• S6 - Thing nam 2011 P H I NGHIEN CUU - TRAO DOI Theo tai lieu [6] - Doi voi may bom co lbn N> 100 kW, thuong diing de bom hat ran co d > 10 mm, p ^ 3000 kg/m , C > 20% nen chon = (25 den 30) mm Tuy vay, nd co nhupc diem la de bi gay, vo va dap co hpc manh * Sir dung vat lieu kim loai te hr v C - Doi vbi may bom co trung binh lOOkW > N > 50kW diing de bom hat ran co kich thuoc d^ tii 5mm den 10mm p = 2000 kg/ml C < 30% nen chon = (15 den 25) mm ; : hr v nuoc ta cung nhu cac nuoc tren the gibi co xu hudng su dung rong rai vat lieu hpp kim de che tao cac chi tiet cua may bom vi no cd nhung uu diem sau: - De tao dp bong be mat nen ma sat nho C - Doi vbi may bom co nho N < 50kW, dung de bom hat ran co kich thuoc d^ < 5mm, p < 3000 kg/ m l C < 20% nen chon = (10 den 15) mm - De tao phoi va gia cong chi tiet - Tuoi tho chi tiet cao - Chiu va dap co hpc rat tot tir cac xung ngoai luc hr v C - Theo L.C Givotopsky, de nghi lay chieu day la canh theo cong thiic = (0,1 0,13jD c h * Chpn so lupng canh dan phii hpp Khi so canh dan tang thi mang dan cua dong chay bi thu hep, toe dp ddng chay tang, kha nang va dap cua hat ran se tang len Theo kinh nghiem, doi vdi may bom bun, khong nen chpn so canh dan qua nhieu ma nen chpn tir den canh tiry theo tinh chat cua pha ran Neu pha ran cd co hat Idn thi chpn so canh it va ngupc lai - Co the che tao theo cac yeu cau khac ve dp cung cung nhu dp ben mon cua chi tiet Viec su dung vat lieu kim loai che tao cac chi tiet cua may bom bun thuong co hai dang sau: - Phii len be mat chitietmpt ldp hpp kim chong mdn: Su dung phuong phap nham lam giam chi phi nguyen lieu dat tien ciing nhu xir ly nhanh chong sau cac chi tiet bi mai mon, ngudi ta phu len be mat lam viec cua chi tiet may bom bun mpt ldp hpp kim co kha nang chong mai mon va chiu an mon hoa hpc cao * Chieu rong banh cong tac b Phuong phap van dam bao dp cung be mat va kha Chieu rong banh cong tac ciia may bom birn b anh nang chong mon cao Cac hpp kim thuong su dung nhu huong den kha nang chong xam thuc, chong mai mdn, thoat C-Mn; C-Cr; C-Cr-B va kha nang tao cot ap cua may De cac hat ran de luu thong, - Sir dung hpp kim chong mon: dia trudc va dTa sau cua banh cong tac cd kha nang chong Be tang dp ciing va dp chiu mon va dap co hpc ciia mai mon, hau het cac tac gia deu thong nhat lay chieu rong hat ran, ngubi ta tang lupng Cr, tang Ni, W, Mo Ngoai cua banh cong tac bang tir loi vao den loi ra, de chong gion vat lieu, ngudi ta dung them Cu Gidi phap lua chgn vat lieu che tao cac chi tiet Gidi phap giam su mdi mdn xuat hien xam thuc may bom bun c c Vat lieu che tao cac chi tiet cua may bom bun la yeu to quan trpng de tang dp ben mon cua chiing Hien nay, o nuoc ta ciing nhu tren the gibi da rat chu y den viec ap dung cac vat lieu chong mdn cao de che tao cac chi tiet cua may bom bun Thong thuong cd mpt so loai vat lieu va phuong phap ap dung sau • Bpc cao su cho banh cong tac va buong xoan • Diing vat lieu phi kim loai Cac loai vat lieu phi kim loai nhu nilon, nhua gom la loai vat lieu dang dupe img dung de che tao cac chi tiet cua may bom bun vi nd cb mpt so cac uu diem sau: - Chiu an mon tac dong hoa hpc cua nude ban - Dat dp bong be mat cao nen ma sat nho - Chiu dupe mai mon cac hat cp xat va truot vao be mat vat lieu - Cac cm tiet cau tao co trpng lupng nho, dp ben cao Cac hien tupng xam thuc cung thuong xuat hien cac may bom bun, tang manh dp mai mon cac chitietcua cac may bom bun Dac biet, hien tupng xam thuc anh hudng Idn den dp mai mon cua canh banh xe cong tac Hien tupng xam thuc la hien tupng boc hoi cua chat long dubi ap suat thap hon ap suat hoi bao hda Khi ap suat chat long giam nho hon ap suat hoi bao hda thi chat long boc hoi tao cac bong hoi va Cac bong hoi va chuyen tbi vung ap suat cao se ngung tu dot ngpt, gay dao dong luu lupng va ap suat lbn pha huy be mat kim loai Hien tupng xam thuc xay dong hanh ciing vbi su rung dong manh cua toan bp bom bun Xam thuc xay lam giam kha nang hut cua bom cung nhu hieu suat lam viec ciia may Hien tuong xam thuc gay su an mdn xam thuc vat lieu rat manh Tang chieu cao hut cua may bom bun cd the lam tang kha nang xuat hien xam thuc Khi dp chan khong 6ng hut tang thi kha nang xuat hien xam thuc cung tang F F I TAP CHI CO KHI VIET NAM ••• S6 - Thing nam 2011 NGHIEN CUU • TRAO DOI Vat lieu lieu co xop va be mat khong nhan bi pha huy xam thuc nhanh Cac vat lieu deo dai nhu dong, thep hop kim va be mat nhan it bi pha huy xam thuc Do la cac vat lieu ben chong xam thuc thuong duoc su dung kin cua khe hb nho cic dem cao su tu bit kin Bit kin huong t i m cb uu diem nhat dinh vi chat luong lam viec ciia no khong phu thuoc vao dp chinh xac lap rap binh xe cong tic va dp chinh xac gia cong binh xe Giai phip cum dieu chinh cua binh xe cong tic Chat luong gia cong be mat co anh huong lbn den cudng dp mai mdn xam thuc Moi vet nham la nhung noi vbi buong xoan cb y nghia lbn Tren hinh trinh biy phat nguyen cua su mire chong xam thuc Be mat cb giai phip cum dieu chinh binh xe cong tic diing v i khong diing Dau vao cua buong xoan can phai rong nham cao lam tang nhanh su mai mon xam thuc bang chieu rong cua dau ciia banh xe cong tacva sau Gidi phap tri cac khe hd giua cac chi tiet mo rpng dieu hoa Day la van de quan nham tang them tuoi tho lam viec ciia may bom bun Nhung khe ho la : III KET LUAN + Khe hb giua cac dia ciia banh cong tac va cac dia Bii bio da de xuat mpt so bien phip thiet ke va ket thep tir phia cao ap va tir phia hut cau de dam bao cac tinh nang hoat dong ciia bom bun va nang cao tuoi tho cua bom X / / / _ - Hoan thien bp phan dan ddng ciia miy bom bun bang cich giam khe hb giua banh cong tic va mui buong xoan tbi gia tri toi thieu nhung phai dam bao su luu thong cic hat ciing van chuyen b b - Tinh chpn gdc dat canh ' toi uu - Lua chpn chieu day canh din s - Chpn so lupng canh dan phii hpp Hinh 1: Hai kieu bit kin ciia khe nha clem cao su Dem cao su Dia truac banh cong tac Duong nuoc vao boi tron + Khe hb giua banh xe cdng tac va dudng ong hut + Cac khe hb trudc dem bit kin Viec tri cac khe hb thudng duoc giai quyet bang su tao ddng nguoe cua nuoc sach - Lira chpn vat lieu che tao cac chi tiet miy bom bun nhu: Bpc cao su cho binh cong tie va buong xoan, diing v i t lieu tot de che tao banh cong tie - Tang chieu cao hut ciia miy bom bun, ciing nhu sir dung kim loai cd dp bong cao de giam kha nang bi mon, phi huy xam thuc Do hb phu thudc truetiepvao ket cau, chat luong che tao may bom, qua hinh lap rap, dong thdi, phu thuoc vao su - Duy tri khe hb giua cac chi tiet bang dem, va boi dieu chinh qua trinh van hanh Do hb phu thuoc tron bang dong nuoc sach de giam dp mon cua cic chi vao yeu to tinh toan Vi vay, cot nuoc va luu luong can thiet tiet hoat dong • de lam kin cd the phai dieu chmh lam viec T a i lieu t h a m khao: Solid-Liquid Two Phase Flow, Siimer M Peker & S,en S Helvaci, Department of Chemical Engineering, Ege University, I zmir, Turkey 2008 Bross, S., Addie, G.R., (2001), "Prediction of Impeller Nose Wear Behaviour in Centrifugal Slurry Pumps," 4th International Conference on Mulitphase Flow, New Orleans, LA, USA Visintainer, R.J., Addie, G R., Pagalthivarthi, K.V., and Hinh 2: Giai phap cum dieu chinh Schiele, O.H., (1992), "Prediction of Centrifugal Slurry Pump Wear" a) loai diing; b) loai khong diing Dem bit kin khe hb giua banh cong tac va nap International Conference on Pumps and System, Beijing, China McGraw-Hill,"Slurrysystemshandbook",BalraE.Abulnaga2002 trudc tren hinh Khe hb giua mat bit ciia banh cong Le Danh Lien, Nguyen Van Bay, Do Huy Cuong "Nghien tac va dudng ong hut duoc bit kin nho vdng kim loai ciru thiet ke may bam van chuyen hat ran" Tuyen tap cong trinh hoi (cd the bang cao su), no cb the duoc ep sat bang cac bu nghi Ca hpc Thuy lan thii Vm, Da Ning, 2003 long dac biet Mot loat ket cau cua cum duoc tao VuNam Ngan, "Nghren ciru su mon hong ciia cac may bom de dat duoc su bit kin tot nhat khe hb giua banh xe cong mo Viet Nam tren ca sa dong hai pha Phuong hudng nang cao tic va duong ong hut Tren hinh trinh biy hai kieu bit ben mon ciia chung" Luan an PTS.KHKT, Ha Noi 1996 v TAP CHI CCV KHI VIET NAM ••• So - Thing nam 2011 E D ... bun nhu: Bpc cao su cho binh cong tie va buong xoan, diing v i t lieu tot de che tao banh cong tie - Tang chieu cao hut ciia miy bom bun, ciing nhu sir dung kim loai cd dp bong cao de giam kha... den viec ap dung cac vat lieu chong mdn cao de che tao cac chi tiet cua may bom bun Thong thuong cd mpt so loai vat lieu va phuong phap ap dung sau • Bpc cao su cho banh cong tac va buong xoan... nude ban - Dat dp bong be mat cao nen ma sat nho - Chiu dupe mai mon cac hat cp xat va truot vao be mat vat lieu - Cac cm tiet cau tao co trpng lupng nho, dp ben cao Cac hien tupng xam thuc cung