Bai Bao - Gia Cong Sieu Am

8/8/2019 Bai Bao - Gia Cong Sieu Am

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VHD: PGS.TS Trng Ngc Thc

VTH: Th Cng

SHV: 09085204001

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B Gio Dc V o ToTrng i Hc SPKT TP. H Ch Minh

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B Gio Dc V o ToTrng i Hc S Phm K Thut TP. H Ch Minh

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Bi tiu lun mn hc CC PHNG PHP GIA CNG TIN TIN:

GGIAIA CCNGNG TTINHINH BBNGNG SSIUIU MM(UULTRASONICLTRASONIC MMACHININGACHINING US USMM)

GVHD: PGS. TS Trng Ngc ThcHVTH: Th CngMSHV: 09085204001

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Gia cng tinh bngGia cng tinh bng Siu mSiu m

Summary

long with the appearance of many new materials that the hardness continuously

improved to meet the production demands, many new methods of finish

machining including ULTRASONICTRASONIC MMACHININGCHINING USM USM have beeninvented to replace the traditional method of machining can not be processed.

A

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Ni dung ca phng php:Ni dung ca phng php:

Sng m l sng c hc lan truyn c trong mi trng

rn, lng, kh nh cc phn t vt cht lm nhim v truynsng. to ra sng m cn c ngun m. Ngun m lmt mi trng n hi c th to ra v truyn dao ngvo mi trng tip xc vi n.

Gia cng bng siu m cc vt th rn ch yu l ng dngs tn sc ca siu m, thc cht l li dng s c st chc ca mi trng hai pha to nn mt tc dng th haikhc.

Nguyn l gia cngNguyn l gia cng::

Dao ng c tn s 18 25 kHz c pht t ngun tn scao 5 truyn n b chuyn i 4 hnh bn di. Ti y daong in bin thnh dao ng c cng tn s, bin daong trong khong 5 10m. Bin dao ng ny nh,khng ln cho vic gia cng kim loi (t 0,025 0,075mm). gii quyt vn ny, dao ng trc khi n udng c c cho qua b bin tc (thanh truyn sng) cgn cng vo b mt ngoi ca b chuyn i. B bin tcc lm bng vt liu c bn mi cao v gim thiu s

mt mt nng lng. Dung dch ht mi c lun chuynlin tc gia u dng c v b mt chi tit. Khe h gia udng c v b mt gia cng t 0,02 0,1 mm. Trong qutrnh gia cng, s rung ng ca u dng c s gia tc chocc ht mi tc cao v truyn lc cn thit cho hotng ct gt. Cc ht mi ny p vo b mt gia cng lmv cc phn t vt liu cng gin. Kt qu l cc phn t liti ca chi tit b bong ra v c ti i bi dng ht mi.

Cc ht mi s n mn bmt gia cng mt cch lin

tc v chp li hnh dngca dng c ln b mt chitit.

Trong qu trnh gia cng,dng c c tnh tin dnti b mt gia cng vi tc

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Cc ht mi s n mn bmt gia cng mt cch lintc v chp li hnh dngca dng c ln b mt chi

tit.

Trong qu trnh gia cng,dng c c tnh tin dnti b mt gia cng vi tco khng i nh vo umy. Tc tnh tin cadng c rt b, gi tr lnnht vo khong 0,1mm/s.Bn my c kh nng dch

chuyn theo hai phngnm ngang thng gcnhau. Khi chi tit gia cngc nh c th thc hinc l thng hoc lkhng thng, l nh hnhhoc cong, ct rnh, ctt, Nu cung cp cho

phi hoc dng c thmmt chuyn ng ph th

c th thc hin c ccnguyn cng phay, mi,tin, ct t, ct ren,

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Thit b v dng c:1. Thit b:

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2. Dng c:

Thng dng c c nhiu hnh dng v kch thc khc nhau ty theo yu cu. Sdng nhiu nht vn l dng c c bin dng ging nh bin dng ca chi tit giacng, kch thc ca n b chi ph bi kch thc ca ht mi c s dng. V d

nu s dng ht mi 600 vi dng c c dng knh 11,98mm th s gia cng ra l ckch thc 120,005mm. Chiu di ca dng c phi ngn v dng c nng s hp thunng lng rung ng, gim hiu sut gia cng. Dng c di gy qu ng sut chodng c v mi hn ng. Dng c thng c chiu di 25 mm, kch thc ca n

bng kch thc ca l tr i hai ln kch thc ht mi. T s gia chiu di vng knh dng c khng c ln hn 20. Trng lng dng c cn t n mc

b nht c th khng hp thu nng lng siu m.

Vt liu lm dng c cn c tnh bn v do. Thp ccbon thp v thp khng g png tt cc yu cu ny. Vt liu lm dng c thng l thp 45, thp dng c Y8A,

Y10A, thp hp kim 40X, 60G, ...

3. u ni:

Giao tip gia thanh truyn sng v dng c c mt b phn gi l u ni. u nic ch to c bit sao cho c th lp c cc dng c vo thanh truyn sng. uni dng c khng n thun ch c ren vn vo, m cn nh bng v bi trnmt lp m mng khp cc b mt tip xc c th truyn ht dao ng. Trongmng m s sinh ra ng sut ko v cn gy ra hin tng xm thc.

4. Thanh truyn sng:

Thanh truyn sng l b phn truyn dao ng t u t gio cho dng c. Thanhtruyn sng c nhiu kiu hnh dng bn ngoi khc nhau, ph bin l dng ngcong hoc trc bc m u nh ca n pha u lp dng c. Vi dng kt cu nhth lm cho m lng tng v pha u dng c v ta c th khuch i dao ng cat gio ln n 100 ln, bin dao ng t n gi tr gia cng kim loi c.im c bit y l bin dao ng hai u thit b rt chnh lch v lnguyn nhn sinh ra ng sut c hc ln.

5. B chuyn i Tranducer:

B chuyn i dng bin i nng lng in thnh cc dao ng siu m. Hinnay c hai loi c s dng rng ri l b chuyn i p in v b chuyn i tgio. Gm c cc b chuyn i sau:

B chuyn i p in. B chuyn i t gio.

1. Hn hp dung dch ht mi:

Hn hp dung dch ht mi bao gm cc ht mi mn, sc trn trong cht lng l nchoc benzen, du nhn, glyxerin. Hn hp dung dch ht mi c lun chuyn n

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vng gia cng nh h thng bm v b phn lm mt. Cht lng chim 3060% thtch ht mi. Cht lng trong hn hp ny ng vai tr l mi trng truyn m giadng c v chi tit gia cng, chuyn nng lng t dng c vo chi tit, mang phoi rakhi vng gia cng. Ngoi ra n cn c tc dng ti nhit t vng gia cng ra ngoi,ngn khng cho dung dch si trong khe h gia chi tit v dng c, trnh hin tngxm thc nhit cao, nng cao nng sut gia cng.

Cc thng s cng ngh:1. Nng sut bc vt liu MRR ( Material Removal Rate):

Nng sut bc vt liu khi gia cng siu m l th tch vt liu (phoi) c ly itrong mt n v thi gian (mm3/pht), c tnh bng cng thc sau:

MRR = 5,9 f (s/H) R0.5y0.5

Trong :f - Tn s dao ng, Hz;H - bn chng t gy b mt chi tit gia cng, HB;s - ng sut tnh trn dng c , kg/mm2;R - Bn knh trung bnh ca ht mi, mm;

y - Bin dao ng, mm.

Cc yu t nh hng n nng sut gia cng:

Bin v tn s dao ng. Tnh cht c l ca vt liu cn gia cng. Ph ti tnh gia dng c v vt liu cn gia cng. Loi bt mi v nng nh tng ca bt mi. Cch cho nh tng vo bt. Tit din dng c. Vt liu lm dng c v mn ca n. su ca l.

1. Dung dch v ht mi:

Dung dch v ht mi cng l mt vn quan trng v n l tc nhn trc tip giacng vt liu. Trong iu kin nh nhau nu dng ht mi l B 4C th nng sut tcao nht. Ngoi ra cht lng dng huyn ph cng rt quan trng. C th dng chtlng l nc, du ma dt, du ha, cn, du my, du gai, glyxrin, ...Trong , dngnc t nng sut cao nht.

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Dung dch ht mi c nh hng rt ln n chnh xc v nhm b mt. Bngthng k cho thy iu .

nh hng ca dung dch ht mi n chnh xc v nhm b mt

2. Cht lng b mt gia cng:Khi gia cng hp kim cng v thp trn b mt c hin tng cng ngui v xuthin ng sut d nn nhng mc rt b. Khi gia cng vt liu phi kim loi v gin cao xut hin mng vt nt t vi. Chiu sau vt nt ln n bn ln chiucao nhp nh.

nhm b mt gia cng c th t Ra = 12,5 0,2m. nhm b mt phthuc vo:

S lng v kch thc ht mi. Tnh cht c l ca vt liu gia cng. Bin dao ng ca dng c. nhm dng c. Cht lng cha bt mi.

1. chnh xc gia cng:

Khi gia cng bng siu m cc chi tit bng vt liu cng, rn dn, chnh xc cachi tit ph thuc vo nhiu yu t, c th chia lm hai nhm nh sau:

Nhng yu t ph thuc vo thit b v chnh xc iu chnh my:+ chnh xc ca thit b ph thuc ch yu vo sai s trong chuyn ng

theo hng tin ca dng c v s iu chnh u dao ng so vi bnmy.

+ S n khp v ng trc ca cc b phn ca u t gio to dao ng,b phn ni, dng c.

+ chnh xc ca cc c cu dng iu chnh chi tit.

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+ chnh xc v tr tng i gia dng c v chi tit gia cng. Trc khigia cng, phi kim tra chnh xc ca my v tt c dng c ph tr nutrn nhm gim n mc ti thiu cc sai s.

Cc yu t ph thuc vo c tnh cng ngh:+ Kch c ht mi.+ S n nh ca khe h gia dng c v vt gia cng.+ mn ca dng cu.+ Hnh dng hnh hc ca dng cu.

+ su gia cng.

1. So snh b mt chi tit gia cng bng siu m so vi gia cng bng tia Laser:

Mt s cng ngh gia cng bng siu m:

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1. Khoan:

Gia cng bng siu m c ng dng rngri nhiu lnh vc khc nhau, nhng khoanl ph bin nht. N thch hp cho gia cngl trn hay khng trn, c hay khng c iukhin. N c dng gia cng hnh dng

phc tp i hi chnh xc cao, c th giacng l nh 0,1 mm. Chiu su l b hn chdo dng c b mn, t s mnh ca dngc v do s kh khn ca qu trnh cp dungdch ht mi vo vng gia cng.

Nguyn l:

Khoan siu m cng da trn c s ng dngtc dng c xt v gt gia ca sng siu m.Thit b khoan gm c u t gio dao ngvi tn s 20-30 kHz v b cu ni c nivi u dao ng. Dao ng c truynsang cu ni qua dng c v n vt cnkhoan nh hnh bn:

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2. Mi mt phng bng siu m:

Khc vi khoan l, khi mi mt phngth chi tit gia cng c th chuyn ngdi dng c.

Trong trng hp phi mi nhng chcht kh mi trn nhng vt gia cng

bng vt liu rn gin (nh s) hochp kim cng th mi trn mt phng

bng siu m c tm quan trng rt ln,v khng c phng php gia cng nokhc c nng sut c th chp nhnc. Nhng c tnh cng ngh khikhoan cng c gi tr khi mi mt phng, y cn lu tc chuyn ng cavt gia cng nh hng n nng sut, cht lng b mt v chnh xc.

3. Hn bng siu m:

Nguyn l:Dng c hn (3) - cc m thanh p vo vt hn (2). Vt cn hn c t

trn e (1). Dao ng siu m t dng c gy nn hin tng bin dng do trn bmt tip xc ca vt hn. By gi cc b phn cn gn kt c p tc thi vi nhau.

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Tc ng tc thi ca lc tnh v ng gy ra s chy ti vng cn hn m khng sdng vt liu b sung vo mi hn. Qu trnh ny c s dng trong cng nghip lin kt plastic hoc kim lai.

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u nhc im v phm vi ng dng ca phng php:1. u im:

Gia cng bt k vt liu no bt chp tnh truyn dn (nhit, in) ca n. Gia cng siu m c p dng gia cng cc vt liu phi kim lai, nha,

vt liu bn dn nh Silicon, Germanium, Gia cng siu m khng to ra cc b mt d thng (bin cng, nt t vi, )

do ho, nhit, in bi v gia cng khng thc hin bng tc ng ho, nhit,in m bng c hc.

C th gia cng chnh xc cc l trn hoc khng trn trn cc vt liu rtcng, rn, dn, nht l vt liu ceramic, thy tinh, ,

t li ng sut d v c trng gia cng khng nhit ca n. Cho php gia cng c nhng vt liu v cng cng, rn, dn. Cho php gia cng c nhng vt liu phi kim loi. Khng gy ra hin tng nt t vi b mt. Khng gy ra tai nn lao ng.

1. Nhc im:

Dng c mn nhanh. Nng sut thp khi gia cng vt liu t hp kim cng v thp ti, bng1/201/50 nng sut khi gia cng thy tinh, thch anh, ... Bn cnh dng cmn nhiu hn.

Din tch gia cng b hn ch. C th tng tit din gia cng bng cch nngcao cng sut ra ca u t gio v din tch pht sng ca n. i vi cc ut gio hin nay th vic tng cng sut ca n i hi phi gii quyt nhngvn m hc phc tp. Ch c th gia cng l v hc khng su lm, gii hn hp l l 2540 mm.Tng su th gim nhiu nng sut, do lm tng vai tr ca qu trnh migt ph, v lm xu i nhiu vic a bt mi vo vng lm vic cng nh

vic ly i sn phm mi mn ca dng c.

Khi s dng siu m b sung cho cc cng ngh truyn thng gia cng vt liucng v kh gia cng, th cn phi ch n nhng nhc im nu trn.

Ngoi ra lm vic vi nhng thit b gia cng bng siu m tn s tng i thp(


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Gia cng khng ct gt: hn, lm sch kim loi, lp ghp bng p, ha ng, giatng s khuch tn.

ng dng trong vic lp rp chi tit: lp rp cc chi tit ti cn c lc ln.Nh dao ng siu m, to nn gia tc v s bin thin kch thc c chu k i vi

vt cn p, lm cho vic lp rp d dng hn. S lp rp c thc hin bng daong ca mt hoc c hai vt v th lc p gim nhiu.

Mt s mu gia cng bng siu m:

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Trin vng pht trin ca phng php:Trin vng pht trin ca phng php:

Nhu cu pht trin cng nghip ngy cng i hi gia cng cc vt liu bn dn, gmhp kim cng v nhiu vt liu siu cng rn, dn khc. Do vy i hi phi pht trinloi thit b gia cng bng siu m.

Cc thit b gia cng siu m hin nay cha tht s hon thin, cn phi nghin cupht trin cc vn v ng hc, u t gio, cc gii php ni mi phc tp. Hinnay, ngi ta ang nghin cu pht trin cc mch in a mch, cc u t gio v bni c th gia cng trn b mt ln, t tn tht.

Bng cc phi hp gia cng siu m, gia cng n mn in v gia cng in ho vinhau, gia cng cc vt liu c kh nng dn in, ngi ta c th tng nng sut v

gim hao mn dng c.

Nghin cu pht trin nhng loi thit b mi da trn nguyn tc phi hp gia cngsiu m cc phng php gia cng truyn thng.

Ti liu tham kho:Ti liu tham kho:

[1] http://hoicodien.org/forum/showthread.php?t=1695[2] http://meslab.org/mes/

[3] http://www.maykhaccnc.com/tin-tuc/134-mai-sieu-am.html[4] Nguyn ng Tc, Siu m v ng dng

[5] Hong Quang Vinh, My d khuyt tt vn nng[6] Nguyn Nghi, My d c[7] B T Lnh thng tin lin lc, Mt s vn v k thut thng tin[8] Robert S. Carrow, Fundamentals and applications of ultrasound, McGraw Hill,

USA

Ht

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