Cc nguyn nhn c th gy rung: 1/. Cc rung ng do lc tc ng:

Do mt cn bng trng tm (mt cn bng tnh, mt cn bng ng) Do lp lch trc(disalignment). Do cong trc. Do tip xc bnh rng. Do c st R to - Sta to. Do lc in t. Do kch thch ngoi.

2/. Cc rung ng t do:

Do xoy du, xo trn du hoc hi Do h hng gi trc. Do cng hng R to, cng hng ca cu trc bn ngoi. Do cng hng m hc, kch thch kh ng hc, thy ng hc.

Nguyn nhn: 1/. Do kt cu khng ng nht khi ch to Rotor. 2/. Do Rotor b bin dng sau mt thi gian hot ng. 3/. Do Rotor b nt v mt vi b phn. 4/. Rotor b cong trc sau khi khng hot ng trong mt thi gian di. 5/. Cc thnh phn lp ghp ca Rotor b x dch Cc dng mt cn bng: 1/. Mt cn bng tnh: nu trng tm ca Rtor khng trng vi trc ca R tor. i vi cc rotor ngn, c th xem nh c thm mt khi lng di d ti mt v tr no ngoi mt Rotor. i vi cc Rotor di, c th xem nh c 2 khi lng di d nm cng

hng 2 u rotor. Mt cn bng tnh c th gy ra rung ng trn 2 gi trc 2 u Rotor. Hai gi trc ny s rung ng ng pha vi nhau. 2/. Mt cn bng moment: Trng tm ca Rotor vn trng vi trc quay, nhng moment qun tnh li khng trng vi trc. Mt cn bng moment thng ch xy ra vi cc rotor di. C th xem nh c 2 khi lng di d hai u Rotor, nhng nm i xng vi nhau 180 . Khi rotor quay, hai u trc khi s ngoy ngc hng vi nhau, to thnh cc rung ng lch pha nhau 180 . 3/. Mt cn bng ng: Nu Rtor va b mt cn bng tnh va b mt cn bng moment, th n b mt cn bng ng. Mt cn bng ng xem nh Rtor c 2 khi lng di d c ln khc nhau 2 u, v gc lch nhau bng mt gc khc 0 , khc 180 V th khi Rotor quay s lm 2 gi trc rung ng vi bin v gc pha khc nhau. Cch x l: Ch yu l cn bng li Rotor. QT s trnh by cc cch cn bng sau khi trnh by ht nhng nguyn l. 1/. i vi mt cn bng tnh: ngi ta ch cn cn bng tnh li ng c a trng tm v trc quay. Phng php cn bng tnh thng c thc hin trong xng ch to. Nhng i khi cng c thc hin ti hin trng bng phng php tng t phng php cn bng ng. 2/. i vi mt cn bng moment v mt cn bng ng: Bt buc phi thc hin cn bng ng. Cc thnh phn li Rotor khi ch to c cn bng tnh chnh xc

ti xng. Cc chi tit khi lp vo Rotor, th d nh cc cnh Tuabin v cnh my nn c cn chnh xc, v dng cc phn mm chuyn dng phn phi u cc cnh trong vng trn. V th cc cnh u phi c nh s, v km theo mt s v tr lp rp trn vng trn. Sau khi lp rp ton b, Rotor li c cn bng ng ln cui trong bung chn khng. V th rung ca rotor rt thp. Tuy nhin, khi ra hin trng, nu c xut hin mt cn bng bt thng, ngi ta s phi cn bng ng li ti hin trng. Ngoi ra cc Rotor b bin dng theo kiu cong trc, hoc x dch cc v tr lp ghp, s c x l bng mt phng php c bit, l cho quay vi tc cao hn tc cng hng cp 1 gip cho trc c t ng nn thng tr li. Thng, bin php ny c lm ti hin trng, v hot ng cc diu kin v p sut nhit lm vic. Do phng php ny gi l phng php sy nn trc. Dng phng php sy nn trc, ban u phi cn bng ng trc gim rung xung mc thp nht m mnh c th thc hin c. Tt nhin rt kh c th a v mc tt. Sau chy sy. Khi trc c dn a v trng thi tt, rung s gim dn, n mt mc no . Khi y th cc gia trng dng cn bng ng lp trc s tr thnh ngyn nhn gy rung. V rung s tng ln tr li. Khi phi tho bt gia trng ra, v tip tc chy sy nn trc. Vic sy nn trc coi nh kt thc khi tt c cc gia trng lp trc c tho ra ht v rung ca my tr v trng thi tt. y l mt s hnh minh ha. Gi s trc ca chng ta (khi trn mu cam) b thay i v tr trng tm.

S thay i chng ta c tng tng nh l c mt khi lng di d lp vo nh hnh v (khi mu en).

Khi trc quay trong trc (phn mu xanh) tc thp, th trc s o theo chiu hng vng pha c khi lng di d ra ngoi. Nh vy khi ch d quay n v tr no th v tr s nhn c tr s rung cao nht. Ngi ta s t cm bin rung mt v tr c nh. Khi khi qut ngang qua v tr cm bin rung, tn hiu ra s c nh dng.

Ngc li, khi trc quay trong trc tc cao, th trc s o theo hng ko pha c khi lng di d vo tm quay. Nh vy khi ch quay n v tr no th v tr s nhn c tr s rung thp nht nht. Khi khi qut ngang qua v tr cm bin rung, tn hiu ra s c nh m. Hin tng nhn bit mt cn bng trng tm (mt cn bng tnh): 1/. rung c dng sng hnh sine, thnh phn c bn chim a s, thnh phn ha tn rt t.

2/. Gc pha rung 2 u bng nhau. Ngha l rung 2 u ng pha vi nhau. 3/. Gc pha rung thay i theo tc . tc cng hng, rung ln nht, v gc pha lch 90 so vi tc thp. Cao hn tc ny, gc pha tin dn n 180 so vi gc pha tc thp. Hin tng nhn bit mt cn bng moment: 1/. rung c dng sng hnh sine, thnh phn c bn chim a s, thnh phn ha tn rt t. 2/. Gc pha rung 2 u lch nhau 180 . Ngha l rung 2 u ngc pha vi nhau. 3/. Gc pha rung thay i theo quy lut ging nh mt cn bng trng tm. Nguyn nhn rung th 2: Mt ng trc gia 2 thit b quay. (misalignment). Hai thit b quay ni trc vi nhau th d nh ng c - bm, turbine my pht, My Diesel - my pht in... cn phi c yu cu ni ng trc vi nhau. Tuy nhin khi ch to, mt s thit b gia cng khng hon ton chnh xc, nn c kh nng khi lp rp vi nhau s b mt ng trc. Mt ng trc c th chia lm 3 loi: 1/. Mt ng trc song song. Th d trc ca ci ny cao hn ci kia, hoc mt trc nm sang pha bn phi ca trc khc. Ngha l 2 tm trc khng trng nhau v trc vn song song vi nhau. Mt ng trc song song thng gy rung 2 gi trc gia, tc 2 gi trc hai bn khp ni, thng gi l b trc s 2 v s 3. Do khng ng trc nn rung s c 2 thnh phn ngc chiu nhau. S tng tc qua li gia 2 gi trc s lm cho rung s tng ln cc i 2 ln trong mt chu k. Ph tn s c thnh phn ha tn bc 2 cao.

2/. Mt ng trc do lch gc. Ti khp ni, tm trc c th trng vi nhau, nhng hai trc khng nm trn ng thng, m hp thnh vi nhau thnh mt gc. rung cng tp trung 2 gi trc gia. Nhng do lch gc, khi quay c th lm thay i un ca trc theo chu k. rung cng c nhiu ha tn, v ngoi ra cn sinh ra rung dc trc (o song song vi trc). 3/. Mt ng trc hn hp, va lch tm trc, va c gc: Hn hp ca 2 loi mt ng trc trn. Cc nguyn nhn c th gy ra mt ng trc: a/. Bn thn thit b khi lp t cha c cn chnh tt. b/. Khi trng thi tnh, trc hi b vng xung. Nu cn chnh theo trng thi ny th khi quay, trc dui thng tr li s gy mt ng trc. V th khi cn chnh thng phi cn chnh theo mt gc nh b li (cn h ming). c/. Khi trng thi ngui, cc trc c th ngang hng vi nhau. Nhng khi nng ln th mt gi ca gi trc no s gin n nhiu hn cc gi khc, v lm cho gi cao hn. khi t ng trc s chuyn sang mt ng trc. V th khi cn chnh ban u, phi cn chnh b tr cao thp. d/. Nu 2 trc khng ni trc tip vi nhau m ni qua trung gian b i tc. Ta phi cn chnh ng trc gia 3 thit b: Trc 1 vi b i tc, v b i tc vi trc 2. Tuy nhin khi c lc ko, do lc tng tc ca cc bnh rng, mt trong 2 trc hoc c 2 h trc s b y lch i so vi v tr ban u, gy ra mt ng trc. V th khi cn chnh ban u phi b tr s di chuyn ny. Cc tr s b tr ca cc phn b, c, d thng c nh ch to cung cp. e/. Sau mt thi gian vn hnh, cc gi trc b mn khng u, cc bnh

rng cng b mn i hoc h ra. V tr lp t cc gi trc c th b x dch... gy mt ng trc. X l rung khi mt ng trc: cn tm li, vi iu kin mi trng tt.

Nguyn nhn rung th ba: cong trc. Mt rotor trc di rt d c kh nng b cong trc. Cc nguyn nhn gy cong trc c th nh sau: 1/. Khi Rotor khng quay, trng lng ca bn thn n lm cho trc hi b vng xung. Nhng khi quay sang v tr khc, th bin dng do vng s khng cn, v n li vng theo v tr mi. Nu trc b gi mt v tr c nh mt thi gian qu lu, vng s khng phc hi tr li c. 2/. Khi Rotor ca cc my lm vic trong mi trng nhit cao, s gin n khng ng u cc kha i nhau cng c th gy ra cong trc. Th d nh lc my mi ngng. Khng kh bn trong xy lanh turbine rt nng. Nu rotor ng yn th phn trn s nng hn phn di. Do phn trc pha trn cng gin n di hn phn trc pha di. Kt qu l trc b cong ln. Tuy nhin cong ny ch l tm thi, khi nhit tr li u hoc khi quay trc, th s b mt i. V th cc rotor trc di thng lun c lp t mt b phn quay trc, chng cong trc. Khi trc b cong, n s tc ng nh mt cn bng trng tm. Ngi ta c th x l bng cch cn bng ng b vo. Khi trng tm s c ko v trc, v rung gim xung. Tuy nhin trong trng hp ny li ny sinh ra mt vn khc. Khi

Rotor vi tc cao, n s c khuynh hng dui thng tr ra. V th khi nhng khi gia trng dng cn bng ng li tr thnh nguyn nhn gy rung. T , s lm cho rung tng tr li t t, nhng vi gc pha lch 180 so vi rung ban u. V th li phi cn bng li. Phng php x l cong trc thng c gi l "sy nn trc", s gm nhiu bc xen k: cn bng - chy tc cao - cn bng... Nu cc rung khng vt qu tiu chun th c th kt hp cc ln chy nn trc vi pht in. Nguyn nhn rung th t: hng b trc. Cc my pht in ln thng s dng cc b trc trt. Cc b trc ny rt d b tn thng do cc nguyn nhn sau: 1/. Thiu p lc du bi trn: do hiu sut bm du chnh, bm du ph gim, tn s my gim ko theo tc bm du gim. Cng c th do v x mt s im no trong h thng. Mt trong nhng nguy c gy thiu p lc du l mc du trong bn du khng , bm b lt kh. 2/. Du bi trn gim cht lng: do vn hnh qu lu nm, do khng kim tra thng xuyn nhit du qu cao. 3/. Nc ln trong du: thng do cc b lm mt du b thng,nc trong b lm mt ha trn vi du. 4/. Mt kim loi xut hin trong du: mt s b phn no b mi mn, sinh ra mt kim loi. nu mt kim loi ny theo du lt vo b trc s gy hng b trc. 5/. Do cn tm khng ng, hoc mt cn bng, dn n rung cao. rung cao s ph hng b trc. rung s pht trin phc tp.