Tuyen tap bao cao khoa hpc Hdi nghi Khoa hpc ky thuat Do ludng toan qudc lan thuf IV Hd Ngi, 11 - 2005
>DO, PHAN TICH RUNG DONG VA VAN DE CHAN DOAN MAY
Le Duy Minh, Nguyin Viet Diin, Nguyin Vdn Ddc, Phan Dinh Hdu Viin Ca hgc Hd Ndi
Abstract:
Vibration is the main cause of excessive wear of bearings, shaft cracking and loose fasteners. But vibration is also the best indicator of overall mechanical condition of
machinnery. Methods of measurement and analysis of vibration to assess vibration level and identify the most important defects of rotating machinery (such as unbalance, shaft bending and misalignment, resonance) are presented with some study cases in this report.
I. V ^ DE RUNG 6 N C O A MAY VA THI^T BI
Rung ddng phdt sinh til cdc thiet bi co khi ndi chung la khdng cd lpi. Rung ddng la nguydn nhdn chinh thudng gdy nen su mdn qud mflc cua d, su nflt gdy, su rdi Idng ra cua cac mdi ldp ghep, su hu hdng cac ro le didn, rdi loan chfle ndng cac mach didn v.v. Rung ddng cdn la nguydn nhdn cua tie'ng dn gdy khd chiu cho con ngudi.
Tuy nhidn khdng phai loai rung ddng nao va mflc dd rung ddng nao cung gdy hai.
Vd'n dl ddt ra la lam thi nao dl phdn tich va chi ra dupe loai rung ddng nao la "lanh" va loai rung ddng nao la cd hai. Cac loai rung ddng gdy ndn cac hu hdng la loai phai dupe nhdn dang va loai bd. Nhimg loai rung ddng cd hai dd la dd'u hidu xud'l hidn tai trpng dang kl gdy ndn su mai mdn tai diem tdc ddng (d gdi, ranh dSn budng,..) hodc gdy nflt gdy cho ket cdu. Nguyen nhdn cua cac rung ddng dd cd thi la md't cdn bang nghidm trpng, la su khdng ddng true, la su cdng hudng hoac la cac va quet v.v...
Cac loai rung ddng "lanh" thudng lidn quan den nguyen li cdu tao va chfle ndng lam vide binh thudng cua may, thiet bi. Cac hieu flng "lanh" ed thi la tie'ng ro ro cua ddng co, rung ddng do xa van, do hidu fltig khi canh ddng vupt qua cac canh tinh theo chu ki, tidng rung dn chay rd'i giai rdng cua chdt long. Thdng thudng cac hidu flng nay khdng Idn, nhung nd cung gdy ndn su khd chiu cho nhung ngudi xung quanh.
Trong thuc td, khi chung ta di tren cac phuong tien giao thdng hoac vdn hanh mdt thie't bi nao dd, cac dd'u hieu rung dn bdt thudng la nhung trieu chflng cua cac hu bdng cd thd xiy ra vdi chung.
Cac tieu cbl danh gia chd't lupng san phdm trudc ddy ndi chung thidu chi tieu vl dai lupng rung ddng. Trong khi dd nmg ddng thudng quan hd true tiip den tudi thp phuc vu cua may, ma chflng ta cd thi kilm chflng trdn hai co sd:
- Tudi thp phuc vu cua may thil't bi mdi cd mflc rung ddng thdp se keo ddi.
- Mflc rung ddng cua may tang len nhanh la thdi dilm may dang tie'n ddn trang thai phai dflng do sir c6 hfl hdng may.
Kinh nghiem vdn hanh khai thac bom, may nen, quat, tua bin (mdy quay) nhieu nam cua cdc nganh nang lupng, khai thdc ddu khi da chi ra hidu qua to Idn cua chi do bao dudng may vd thilt bj cd du bdo trudc, vi viec bao dudng dupe thuc hien nhanh hon vd
121
chinh xdc hon, khdng phai mua cac chi tiet thay the khdng cdn thiet, giam mflc tieu thu nang lupng.
Tai sao la thdng sd rung ddng? Bdi vi rung ddng la chi thi tdt nhdt cua trang thai co khi tdng thd cua may, va cung Id chi thi sdm nhdt ciia su phat trien cac hu hdng. Ngoai ra cdn cac chi thi khac nfla, nhu nhiet dd, dp sudt, ddng chay va thanh phdn cua ddu bdi tran.
Bang Bl dudi ddy chi ra cdc thdng sd bd sung dupe sfl dung vd gid tri ciia chflng trong mdi tuong quan vdi rung ddng d l chi thi vd danh gia tdng t h i trang thai ky thudt cua may thiet bi.
Tuy nhien trong trudng hpp, ndu phai chon lua mdt thdng sd d l chi thi, thi thdng sd chi thi tdt nhdt Id rung ddng. Theo cac tiiu chudn ISO cflng nhu API thi cac dai lupng vl nhidt va dp suat ddu bdi tron ctia may dupe cho dudi dang mdt gia tri mflc cho phep, vi cac thdng sd ndy la cac thdng sd bidn ddi tuong dd'i chdm so vdi stf thay ddi frang thdi cua thilt bi.
Bdng BI: Bang thdng sd dupe dung chi thi trang thai ky thu$t ciia may
Kiiu hu hong Mdt can bdng htch true Hong d bi Hong 6 truot Hong bdnh rang Bi ra long co khi 6n Nfltgly
Thdng sd duoc sfl dung ldm chi thi Nhidt
dd
X X X
dp sudt
X
Dong chay
X
Thanh phdn ddu
X X X
Rung ddng
X X X X X X X X
II. CAC PHUONG PHAP DO VA PHAN TICH RUNG DONG 2.1. Cau hinh co ban cua he thdng do rung ddng
N g u o n c a p
1 Tin hi^u
D S u d o Ddu d o gia tdc, van tdc, c h u y i n
i
\ko
Bp bie'n ddi t u o n g t h i c h Khud'eh dai, L p c , Tich
phan, vi phan cdng B p Imi trij- & p h d n tich
1
m tru, phan ticti, rii thi
in Hinh HI: So do cau hinh cor ban cua mpt he thong do rung dfing
Ngdy nay, cdc nha san xudt hang ddu the gifii nhu Bently (My), Schenk (CHLB Dflc), B&K (Dan Mach), Phillip (Ha Lan), DEWETRON (do),v.v vd cac hiep hfli tifiu chudn qufic t i nhfl ISO, API, cung da thfi'ng nhdt dupe cdu hinh co ban cua mfit he thfing do vd phdn
122
tich rung ddng nhu trdn hinh HI, cdu hinh co ban nay bao gdm cdc ddu do, ngudn cdp, bd bidn ddi tuong thich (bd khuylcb dai), thiet bi vd phdn mim luu tru, phdn tich, hiin thi tin hidu rung ddng. Mdt he thdng do cd thi cd nhilu kenh do, mdi kdnh do thudng bdt ddu tfl mdt loai ddu do nhdt dinh (ddu do gia tdc, ddu do vdn td'c, ddu do chuyen vi).
2.2. Cac loai dau do rung dpng
Ddu do rung ddng la thilt bi chuyin ddi tin hieu rung ddng sang cac dang tin hidu khdc dd dang luu trfl va xfl^ ly hon (didn ap). Ddu do rung ddng cd nhieu loai, thudng dupe phdn theo dai lupng rung ddng do dupe true tiip chua qua cdc phep biln ddi vi, tich phdn (gia tdc, vdn tdc, chuyin vi), theo phuong phap do (tidp xuc hay khdng tie'p xflc) hoac theo nguydn ly lam vide cua chflng. Cac he thdng do rung ddng trong cdng nghiep cflng nhfl trong phdng thi nghiem cd ba loai ddu do thudng gap dd la ddu do gia td'c ti^p xflc kiiu gdm dp dien (piezoelectric accelerometer), ddu do vdn tdc tid'p xflc cam flng didn tfl (velocity transducer) vd ddu do chuyin vi khdng tidp xuc kieu ddng diln xoay (eddy current proximity probe).
Ddu do gia tdc tiip xflc kiiu gdm dp dien ldm viec dua tren hieu flng dp dien. Mdt sd vdt lidu nhu thach anh, gdm dp dien, BaTiOj, mudi Xecnhet khi phai chiu dp luc len bl mat thay ddi thi se sinh ra lupng diln tich biln thien theo quy ludt cua dp luc. Nhung vdt lieu cd tinh chdt nhu vdy cd thi dupe sii dung dl chuyin tin hidu rung ddng (dp luc) thanh tin hieu dien (dien tich).
Ddu do dupe gdn true tidp len vi tri cdn do. Toan bd vd ddu do va khdi lupng M ddng vai tro vdt ndng rung ddng theo dilm gdn ddu do, phdn tfl dp dien lam tfl vdt lieu dp dien, dupe ma bac hai mat, ddng vai trd nhu mdt Id xo chiu tdc ddng cua vdt ndng M. Trong qud tnnh dao ddng, lupng dien tich tren hai ban mdt phdn tfl dp dien ludn ty Id tuyin tinh vdi dp luc tdc dung len nd, tflc la ty le thudn vdi gia tdc dao ddng (F = Ma).
Ddu do vdn tdc tiip xflc lam viec dua tren hien tupng cam flng diln tfl. Vd ddu do, nam chdm va he Id xo-giam chdn dao ddng cung vdi diem gdn ddu do khiln cho tfl thdng mdc vdng qua cudn ddy biln thien theo thdi gian. Sud't dien ddng cam flng xudt hidn trdn cudn ddy ty le thudn vdi cudng dd tit trudng (B), vdi chilu ddi hieu dung cua cudn ddy nam trong tfl trudng (1) va vdi vdn tdc tuong ddi gifla cudn ddy vd tfl trudng (v), cfing la vdn tdc rung ddng cua dilm gan ddu do.
Ddu do khoang cdch khdng tiip xflc kiln ddng xoay hoat ddng dua trin hien tucftig cam flng dien tfl. Ngudn cdp ddng xoay chieu AC tdn sd cao (I MHz) qua cudn so cdp tao ra tfl thdng bid'n thien qua khe hd trdn bl mat dd'i tupng do tai dilm do. Tfl thdng bid'n thiln nay se lam cam flng ddng didn xoay trdn bl mat dd'i tflpng do, bidn dd cua ddng xoay sinh ra ty le nghich vdi dd Idn khe hd gifla cua cudn so cdp cua ddu do va bl mdt ddi tupng do.
Ddng didn xoay nay lai sinh ra tfl trudng bidn thien, Idm xudt hidn sudt dien ddng cam flng trdn cudn ddy thfl cdp eua ddu do. Nhu vdy, sudt didn ddng tai ddu ra se ty Id nghich vdi khoang cdch gifla ddu do va dilm do trdn ddi tupng do.
Ddc tinh cua ddu do Id cac thdng sd cho bidt kha nang vd pham vi boat ddng cua mdi ddu do, bao gdm dd nhay, ddc tuydn tinh, dd di pha v.v... Mdt ddu do tdt thudng cd dd nhay cao vd khdng ddi trong dai tdn sd lam vide, tin bilu ra dn dinh theo thdi gian, khdng bi anh hudng cua cac ylu td ngoai canh nhu nhiet dd, dd dm, tfl trudng,...
2.3. So dd cac h^ thong do rung dong co ban trong cong nghiep
Dl thu thdp ddy du thdng tin vl rung ddng phuc vu cho vide danh gid trang thai ky thudt cua thidt bi, cac nha chd tao cung nhu cdc nha cung cdp cdc he thidt bi do va phdn tich rung ddng thudng de xud't cdc so dd do mng ddng theo quan dilm ridng cua minh va chu yd'u tfl khia canh thuong mai. Tuy nhien trong thuc t l ngudi mua thidt bi cd quyin ydu cdu hd thd'ng do rung ddng phfl hop vdi nhu cdu vdn hdnh cflng nhfl kha ndng tdi chinh cua
123
minh. Cic hang san xudt thiit hi do rang dfing cfing nghifip B&K (Dan Mach), Schenck (CHLB Dflc), Phillip (Hd Lan), VIBRO-METER (Thuy Si), Bently Nevada (My) di xudt nhiiu So do bfi Irl cac ddu do rung dfing khdc nhau cho cac thiit bi cfing nghifip cfing sud't Ifin quan trong nhfl turbin, mdy phdt, dfing co, mdy nin, v.v. Trfin hinh H2. la so dfi bfi ttf cdc ddu do rang cia Tfi hpp Turbin khi-Hfip sfi-May phdt cua Nhd mdy nhifit difin Cdn Tho cia Hang chi tao Turbin EOT (Anh). Ddu do gia tfi'c rang dupe gdn Ifin phdn tinh cdc gfi'i A, C, F, G theo phuong thdng dflng (phuong cfi mflc rang dfing Ifin). Vfii so dfi bfi tri nhfl vdy vi CO ban ngflfii ta kiim sodt dflpc trang thai rang dflng cia tflng hfi thfing vd cua tflng cum thiit bi. Ddu do tai vi tri A, C se cho biet trang thdi rung dflng cia cum may nin (COM), turbin cfing sudt (PT). Ddu do tai cac vi tri C, F cho biit trang thdi rang dflng cua hfip so (GEAR) vd anh hufing rang dfing qua lai gitta cum mdy nin-turbin vd mdy phat (GENERATOR).
p=10K(^Ctrf
COM 5100 RPM
FT
IVlr=10.500KG
INLET 28 DEGC
EXHAUST 550 DEG
IVbB=2500KG
GENERATOR WATTS: 35.0MW SPEED: 30(XDRPIVI
M3=14.0CKKG
Hinh 2: So do vi tri cae diem do rung dpng tren td hpp Turbin khi - Hop so - May phdt Nha mdy dien Can Tho
III. VAN DE CHAN DOAN MAY BANG RUNG DONG
Trong thfle ti cfing nghifip cfi rdt nhiiu loai mdy quay vd cdc tfi hpp mdy quay tfl don gidn den phflc tap. Tfl ngufin dfing luc so cap nhfl: dfing co difizen, dfing co difin, tua bin thuy luc, tua bin hoi nflfic, tua bin khf, dfing co gifi din cdc mdy cfing tac nhu bom, mdy nen, mdy phdt difin, quat, v.v. vfii cdc thie't hi trang gian nhu hfip sfi', khfip li hpp. Tfi hpp cdc ngufin dfing luc vfii cac may cfing tdc khac nhau se cho ra nhiiu tfi hpp mdy quay dcfn gian cfi, phflc tap cfi. Su sai lech trong ldp ghip, su hu hong khiim khuyit mfit chi tiit cdu thanh ndo dfi cia mdy diu ddn din su gia tang dfi rung cia mdy. Qua thuc t i vdn hanh va khai thdc mdy quay ngflfii ta cung dd tfing ke't dupe cdc loai hfl hong khd phfi biin fi mdy, dfi Id: mdt cdn bang khfli lupng, Ifich true, hong vfing bi, ro long 6, ro long CO khf, dao dfing mdng ddu, va qufit, v.v.
Mfii loai hfl hong cua mdy thufing cfi cae dac tnmg rang dfing cua minh, ede dac trung dfi cfi thi dupe thi dupe thi hifin trong miin thfii gian (tfn hieu thfii gian), hoac trong miin tdn sfi (phfi tin hieu), tfl mfii each thi hifin, chflng ta cfi thi nhan dflpc cac thfing tin vi cdc hfl hong, vd dfi Id CO so di chdn doan tinh trang ky thuat cia mdy, thiit bi. Trfin cdc hinh tfl H3. din hinh H8. la cdc dac trung rang dfing flng vfii cdc loai hfl hong thflfirng gap trfin cac mdy quay.
Ddc trung rang dfing do mdt can bdng trong miin thfii gian la hinh sin don, pho tin hieu chi cfi mflt thanh phdn tdn sfi, pha cia cdc tin hifiu Mnh sin cho biit kiiu mdt cdn bdng tinh hay mdt cdn bdng dfing (tfn hi6u thfii gian do tii 2 gfii cia rfi to cung pha Id mdt cdn
124
bang tmh, ngflpc pha la mdt can bdng dfing). Cfin hifin tflpng Ifich true thi dflpc ddc tnmg bfii dfi thi phfi cfi vdi ba thdnh phan, thanh phdn hfii 2 (cfi tdn sfi gdp dfii tdn sfi quay cia mdy) cfi bifin dp Ifin nhd't, tfn hifiu thfii gian khfing cfin Id hinh sin don nua ma la tfing cia cdc hinh sin cfi chu k^ khdc nhau hinh H5, Hfi. Cdc trufing hpp ra long 6 hay xdt 6 cQng cfi cdc dac trung rifing xem hinh H7, H8.
IV. MOT tJNQ DUNG THUC TE
Tren hinh H2 la tfn hieu rang dpng do dupe tfl cac gfi'i A, C, F, G cia tfi hpp turbin- hfip sfi-mdy phdt ciia Nha mdy nhiet difin Cdn Tho (xem hinh H2.). Tdn sfi lam viec cia turbin la 85Hz (5100v/p), tdn sfi quay cia mdy phdt la SOHz (3000v/p). Tren co sfi dfi chflng ta cfi thi nhdn thdy rdng phdn turbin mdt cdn bdng khd Ifin, va thfing tin tfl tin hieu thfii gian (sau khi lpc va gian) do trfin gfii A, C hinh HIO. cho thdy day la dang mdt can bang dfing vi pha mng dfing gdn nhu ngupc pha nhau. Rung dfing tfl phdn turbin da lan trayin ca sang phdn may phat vi ttfin phfi rang dfing cua gfii F, G xudt hifin ca thanh phdn tdn sfi 85Hz. Vd thdnh phdn lOOHz trfin dfi thi pho cflng cho thdy hien tupng Ifich ttije gifla phdn turbin vd mdy phat cung da xudt hien. Rung dfing gfii A, C la ttfin, va gfii F, G Id dufii mflc cho phip theo tifiu chudn IS02372.
V. Kfi'T LUAN
Hinh 4: Pho tin hieu do md't CB
Kj^^ffia
Hinh 5: Tin hieu thdi gian do lech true Hinh 6: Phd tin hieu do lech true
IfJ
Ifi ;:;; u
r
u X ^
\ I WSLcv • V a v * y ^
1 1
1
i 1
h /J 1 1
^1
1 ! 1 !
.,-.L4..i...
JljiiAj ,
•
..«
" • • | — "
— 4 — H
)
1 ] h-M-J^—
Hinh 7: Pho tin hidu do ro long o Hinh 8: Pho tin hidu do xdt o
Bdo cdo da tnnh bdy ky thudt do vd phuong phdp phdn tfch tin hieu rang dfing de chdn dodn trang thdi ky thudt cia may. Viec dp dung phuong phap phdn tfch tfn hifiu rang dfing trfin cho to hpp Turbin khi-Hfip sfi-Mdy phdt Nhd mdy dien Cdn Tho cho kit qua phu hpp vdi thuc trang ky thudt cia tfi may (he thfing kiim sodt lufin canh bao mflc rang dflng cia Turbin vflpt qud mflc cho phep, Nha may dang cfi kfi hoach can bdng lai rfi to).
Vien Co hpc dang triin khai cfing nghfi ndy fi Viet Nam va rdt mong nhdn dflpc su hpp tdc cua cdc dong nghiep tfl cdc nganh lien quan.
Hinh H9: Tin hieu thfii gian tren eac go'i A, C, F, G (tfl trdn xuong)
Hinh HIO: Pho tin hieu tren eac gfii A, C, F, G (tfl trfen xufi'ng)
Hinh Mil: Tin hieu thfii gian (da Ipc gian) tren cac gfi'i A, C (tren xuong) Tdi lieu tham khdo:
[I] Victor Wowk. Machinery Vibration. McGraw-Hill, Boston, 1991
[2]Robert C. Eisenmann, Sr., P.E. Machinery Malfunction Diagnosis and Correction.
Prentice-Hall, Inc. London, 1997.
[31 Bdo cao ket qud thuc Men di tdi cdp Vien KH&CN Viet Nam 2003-2004 ve "Phdt triin phdn mim nhdn dgng vd qudn li Irgng thdi ky thugt thiei hi thdng qua cdc ddc trung rung dn vd nhiet dd "
126
