Thc tp k thut

Thc tp k thut

Kho st, nghin cu quy trnh v cc yu cu k thut ca cng ngh phun sn

I. Tm hiu chung v cng ngh phun sn1. Phun sn l g?Phun sn l k thut sn y mt thit b s phun mt lp ph (sn, mc, vecni, vv) qua khng kh ln mt b mt. Sn va tc dng to thnh mt lp ph bo v sn phm, ng thi trang tr, lm p.Phng php phun sn c s dng khp mi ni, trong nhiu lnh vc v cho nhiu loi vt liu khc nhau: g, kim loi, nha, Vic la chn phng php phun sn ph thuc vo yu cu k thut sn phn cn phun sn.Phun sn c th thc hin bng tay hoc t ng.2. Phng php to lp ph phun sn- Conventional Air Spray (Phun khng kh thng thng)- HVLP (High Volume Low Pressure)- Airless Sprayers (Phun chn khng)- Air-Assisted Airless (Phun chn khng c tr lc bng kh)- Electrostatic Spray (Phun tnh in)

a. Phun khng kh thng thngQu trnh xy ra khi sn c phun ln mt i tng qua sng phun p lc khng kh. Khi sng c kch hot, dng sn ha trn vi dng kh nn v c phun ra ngoi ra mt vi phun.Do mt loi cc hnh dng, kch thc vi phun m m ca sn phun ra a dng. Hnh dng ca phi v tnh thng nht b mt sn mong mun l nhng yu t quan trong khi la chn vi phun. C 3 loi vi phun ph bin nht l: hnh nn y , hnh nn rng, hnh dng phng.

Trong qu trnh phun sn bng tay, yu cu ngi cm sng phun phi c tay ngh cao m bo v mt lp ph c ng u.Trong qu trnh phun sn t ng, sng c gn vo 1 gi c nh, dng sn c cung cp lin tc. Cc i tng c sn thng t trn cc con ln hoc mt bn xoay m bo sn ph u cc mt.u im: Cht lng sng ph siu mn ng dng rng lnNhc im: S dng nhiu kh To ra nhiu m sn khng bm vo i tng sn Hiu qu thp

b. HVLP (High Volume Low Pressure)Pht trin t h thng thng thng, nhng s dng mt lng ln th tch khng kh p sut thp phun sn ra vi tc thp.Theo nh ngha, HVLP c mc p sut m ha khong 10 psi~0.7bar hoc t hn.H thng phun HVLP c s dng trong cng nghip t , hng hi, kin trc, sn ni tht hon thin, bc tranh phong cnh p v cc ngnh cng nghip m phm .u im: Hiu sut truyn cao 65% - 75% C th phun vo nhng hc, k nh Ph hp vi cc tiu chun an ton mi trng Tit kim snNhc im: Cht lng phun sn khng c tt nh phun khng kh thng Mt s h thng HVLP s tn kmc. Airless Sprayers (Phun chn khng)Sn c to ra nh p lc nn ca nguyn liu p lc rt cao ca bm, p lc lm vic dao ng t 1200-3600 psi.Hiu sut truyn cao hn phun thng thng.ng dng in hnh l cc ng dng ca lp ph bo v trn tu , cu , xe xy dng , tu ho, hoc container, cng nh ni tht v ngoi tht sn v trang tr, v cc ng dng ca lp ph bo v la .My phun sn p lc c th l in , xng du hoc kh nn iu khin.u im: Tc phun nhanh Hn ch ti thiu lng sn bay ra ngoi Tiu th t khng kh Phun c khong rng trong thi gian ngn.Nhc im: Vi phun c xu hng mn nhanh do p lc thy lc u phun qu ln Bm thy lc c kh nng nguy him i hi bo tr hng ud. Air-Assisted Airless (Phun chn khng c tr lc bng kh)Phng php Air-Assisted Airless l s kt hp hon ho cng ngh gia phng php Airless v phng php Airspray c im ca phng php ny va tit kim c nguyn liu sn va cho b mt sn hon ho.ng dng in hnh trong sn xut ni tht.u im: Tit kim nguyn liu hn 50% so vi phun khng kh thng t hao mn v tui th bm lu hn so vi Airless Gim tn tht v m snNhc im: Tun th nghim nht cc yu cu k thut Cht lng sng khng tt bng phun thng e. Electrostalic Spray (Phun tnh in)Sn tnh in cn c gi l sn kh v tnh cht ph dng bt ca n v khi s dng n s c tch mt in tch (+) khi i qua mt thit b c gi l sng sn tnh in, ng thi vt sn cng s c tch mt in tch (-) to ra hiu ng bm dnh gia bt sn v vt sn. Sn Tnh in l cng ngh khng nhng cho ta nhng u im v kinh t m cn p ng c v vn mi trng cho hin ti v tng lai v tnh cht khng c cht dung mi ca n. Do v vn nhim mi trng trong khng kh v trong nc hon ton khng c nh sn nc.ng dng sn tnh in ch yu cho cc sn phm bng kim loi: st thp, nhm, inox,u im: 99% sn c s dng trit (bt sn d trong qu trnh phun sn c thu hi s dng li) Tui th thnh phm lu di bng cao Khng b n mn bi ha cht hoc b nh hng ca tc nhn ha hc hay thi tit. Khng s dng dung mi: khng gy nhim mi trng D dng t ng ho tit kim c chi ph nhn cngNhc im: Hn ch hnh dng sn phn c th ph in p cao c th nguy him

II. Tm hiu v cc loi sng phun sn1. Sng sn l g?Sng phun sn l mt cng c s dng kh nn to ra nhng ht sn nh hoc cc vt liu phun khc v phun ln mt b mt nht nh.Khng kh v vt liu sn vo khu sng qua ng ring bit v c ha trn vi nhau trong mt m hnh c kim sot (nh lng m sng, tc phun,).2. Phn loi sng phun snSng phun c th xp loi bng nhiu cch khc nhau. Mt l bi v tr ca bnh cha sn. Hnh 1 - cho thy sng sn vi mt bnh cha km theo. Hnh 2 - minh ha mt khu sng s dng vt liu t mt thng cha xa qua cc ng dn.Cc kiu h thng cung cp nguyn liu cng c th l mt cch phn loi sng, vi vt liu c gi li bi p lc a pressure feed gun (hnh 2) hoc s dng nguyn l ht vt liu cung cp vo khu sng (hnh 1). Sng cng c th phn loi mt trong hai kiu: External or internal mix, bleeder or non- bleeder types.

Hnh 1

Hnh 23. Suction Feed Gun l g?Mt thit k sng phun trong mt dng kh nn to ra chn khng m khng kh, do to ra hin tng ht. Nh hnh 3, Sng ph hp vi vic thay i nhiu mu sc v lng vt liu nh, chng hn nh trong qu trnh sa cha.

Hnh 34. Pressure Feed Gun l g?Trong thit k ny, cc u lng ngang bng vi mt ca np khng kh, nh hnh 4, v khng to ra chn khng. Cht lng c a ra bi p lc trn cc vt liu trong h thng. H thng ny thng c s dng khi cn phun mt lng ln nguyn liu, khi vt liu qu nng ht t mt bnh cha, hoc khi ng dng nhanh l yu cu.

Hnh 4

5. Gravity Feed Gun l g?Thit k s dng trng lc ca dng chy vt liu t cc cha gn pha trn sng v chy vo trong sng.Cc ny c mt l thng hi pha trn cng v phi lun m. Cc thng c gii hn mc 600cc do yu t trng lng v cn bng.L tng cho nhng ng dng nh nh ch sa cha, hon thin chi tit hoc phun kt thc trong mt khng gian hn ch.

Hnh 5

6. External Mix GunLoi ny th hin trong hnh, hn hp ca kh v cht lng c hnh thnh bn ngoi np khng kh, n c th c s dng cho ng dng hu nh tt c cc loi vt liu, v l mong mun cho phun sn kh nhanh. N cng c s dng khi mong mun mt kt thc c cht lng cao.

7. Internal Mix GunLoi sng ny hn hp khng kh v vt liu bn trong np khng kh trc khi b y ra.

8. Airbrushy l loi rt nh, trng lng nh, s dng cho nhng chi tit p. Dung tch bnh cha t 15cc-30cc.N c s dng ch yu cho cc tc phn ngh thut.

9. Sng phun sn t ngy l loi sng c thit k s dng trn my mc t ng v cc robot.N khng c nm hoc c iu khin bn ngoi bi v n cn phi c kim sot hot ng t xa thng qua bng iu khin hoc van in t. Do , cc thit lp c chnh xc s cung cp chnh xc cng mt hiu sut.Sng t ng c sn trong cc loi sng thng thng, HVLP, v cc loi ph hp.

III. Phn php, tiu chun nh gi lp ph sn m bo c c lp ph sn tt cn t c nhiu tiu chun nh: phi c bm dnh tt, c cng nht nh, chu c ma st, mi mn, chu nh hng kh hu, chu nhit v m, c bng, chu cc tc ng ha hc,Di y, em gii thit phng php o chiu dy lp ph v kim tra bm dnh b mt.1. o chiu dy lp phThit b o dy mng mng l mt trong nhng cng c quan trng nht c s dng trong ngnh cng nghip sn. T l chp nhn chung gia chiu dy lp ph kh v chiu dy lp ph t hu ht cc lp ph l:

Cc li trong chiu dy mng mng lm tn hao v c thi gian, vt liu v tin bac. Nu mng qu mng, kh nng bo v khng m bo, thi gian dn dn s mt. Nu mng qu dy, l nh nt, bong d dng xy ra v cn nh hng n chi ph vt liu.Do , o dy lp ph chnh xc ti a ha cht lng v gim thiu chi ph vt liu.C nhiu phng php kim tra nh cn ph hy lp ph hoc khng cn phi ph hy lp ph. y, gii thiu phng php kim tra cn ph hy lp ph, s dng thit b byko-cut ca hng BYK: nh hnh di,

Thit b ny thit k di ng s dng trong phng th nghim hoc trong cc qu trnh kim tra. C mt knh hin vi hin th c r lp ph.Cc bc tin hnh: V 1 ng en ln v mt nh hng ct:

Chn cng c ct chnh xc bng cch xoay li ct:

p dng lc ct ct qua cc mng sn ln b mt:

Bt n LED chiu sng cho lp ct:

Xc nh ng ct qua knh hin vi:

Nhn v phn tch kt qu: Ngm thng thc t l do cc lp ph m s vch cho mi lp ph Tnh ton dy lp ph bng s dng bng chuyn i nh bng trong hnh:

2. Kim tra bm dnhTrong thc t, c 3 cch khc nhau kim tra bm dnh ca sn v lp ph trn b mt cht nn. Cross-Cut Test Scrape Adhesion Pull-Off TestTrong , phng php Cross-Cut Test l mt phng php n gin v dng thc hin cho php nh gi bm dnh ca lp n hoc h thng nhiu lp ph.Cc bc tin hnh: Vn s dng thit b byko-cut trn To mt m hnh dng mt li vi li ct thch hp, ct n lp nn:

Dng bn chi chi 5 ln theo hng cho gc:

Hoc c th dng bng dnh dn ri bc ra Kim tra khu vc bng knh hin vi tch hp trn thit b Phn loi kt qu bm dnh bng cch s dng cc tiu ch ca tiu chun ISO 2409 hoc ASTM D 3359

ISO Class: 0 / ASTM Class: 5BCc cnh ca cc ng ct hon ton trn tru, khng c hnh vung ca li b bong ra

ISO Class: 1 / ASTM Class: 4 BCc mnh nh ti cc nt giao ca cc ng ct b tch ra. Khong 5% b nh hng.

ISO Class.: 2 / ASTM Class.: 3 BLp ph b bong ra dc theo cc ng ct v ti giao ca cc cc ng ct. Mt in tch ln hn 5% v nh hn 15% b nh hng.

ISO Class.: 3 / ASTM Class.: 2 BLp ph b bong dc theo cc cnh v 1 phn cc ng vung b bong hon ton. Phn din tch b bong t khong 15%-35%.

ISO Class.: 4 / ASTM Class.: 1 BLp ph b bong 1 phn cc hnh vung hoc b bong hon ton. Phn din tch b bong t khong 35%-65%. ISO Class: 5 / ASTM Class: 0BMc bong vt qu mc 4.20