3-3.Che Tao Banh Rang Tren May CNC

Trng i hc S phm K thut Tp. H Ch Minh

3.8. Cng ngh gia cng bnh rng trn my CNC Hin nay, hu ht cc my phay ln rng, xc rng bao hnh u c iu khin bng k thut s CNC. c bit, vic gia cng bnh rng cn bng CNC s thun li hn so vi cc my truyn thng. 1. S dng h thng c in t sn xut bnh rng cn rng cong vi my phay CNC ba trc: Hnh 9.144 cho thy mt trong nhng loi my c bit c s dng sn xut bnh rng cn rng cong. Tuy nhin, c cu ng hc ca chng vn l k tha t my phay CNC cng nghip. Mt quy trnh sn xut mi ca bnh rng cn rng cong bng cch s dng my phay ba trc giao din vi mt m-un PLC m hot ng nh mt bn phn . V tc sn xut, r rng l phng php ny s thp hn ca my cng c c bit. Khc hn mc sn xut, phng php ny l thun li trong vic sau y: + Cc phng php thng thng i hi u t ln cho vic thu thp cc loi my mc thit b c bit v dao ct dnh ring cho mt lp rt hn ch ca cc bnh rng trong iu kin ca loi bnh rng, kch c, v hnh hc. + Bng phng php ny, nhiu loi bnh rng c th c sn xut vi my phay CNC ba trc. + Phng php ny kinh t hn so vi s dng cng c my c bit. Vic gia cng tt c cc loi bnh rng H Hnh 9.144 My v dao c c th c thc hin trong tt c cc kch c bitcho sn xut bnh rng cn v gia cng vn vt tri cho rng hu ht cc rng cong. bnh rng c chnh xc rt cao. S phay nh hnh l mt trong nhng quy trnh gia cng ph bin nht c s dng sn xut cc loi bnh rng. Dao ct c hnh dng ging nh rnh gia cc rng. Cc dao ct tiu chun thng c s dng vic ct bnh rng bng dao nh hnh. Ti Hoa K, c n tm kch thc cho mi bc rng knh (t l s rng trn ng knh bnh rng) v s ct bnh rng c s rng ch nh trong bng tiu chun. sn xut bnh rng cn rng cong vi my phay CNC 3-trc, bng cch pht trin mt h thng phn mm CAD/CAM bao gm m hnh ha hnh hc v m-un m phng ha. Cc phn mm SolidWorks c s dng cho vic to m hnh CAD v Visual Nastran c s dng m phng qu trnh sn xut bnh rng. Nh cu hnh ca my cng c l c lin quan, r rng mt chuyn ng quay ca phi th cn thit cho NC gia cng bnh rng cn rng cong. Da trn nhng phn tch mc gia cng trn my, t nht bn trc iu khin c yu cu cho NC gia cng bnh rng cn rng

H Vit Bnh


cong bi mt thit lp. V vy, mt bn quay c giao din vi ba trc my phay l bt buc. Dao ct nh hnh c cho n xuyn n khu vc trung tm ca phi bnh rng n su rng mong mun, sau qua mt rng, trong khi bn quay quay phi xung quanh tm ca n, c c chiu rng rng yu cu. Khi mt rnh rng c hon thnh, dao ny c rt ra, phi bnh rng c phn bng cch s dng mt u phn , v rnh rng tip theo c ct. V c bn, phng php ny l mt phng php n gin v linh hot ca vic gia cng bnh rng cn rng cong. Cc thit b v dao ct yu cu tng i n gin, v my phay CNC 3-trc tiu chun c s dng. Tuy nhin, s bo qun ng c yu cu trn mt phn lng n dao m phi l mt gi tr nh trong mi bc ngn chn bt k h hng. H thng c in t cha bn phn chnh: + PLC (chng trnh b iu khin logic): mt trong nhng thit b in t, c th c gi l "B iu khin trnh t". N s dng b vi x l ni b thc hin cc php tnh ca chui cc hot ng theo tnh trng v gi tr ca cc tn hiu u vo ca Encoder v cm bin. + Bin tn: c s dng vn hnh mt ng c 3-pha v hot ng nh mt thit b trung gian gia PLC v ng c AC. N c u vo khc nhau c th c dng xoay ng c AC theo chiu thun/chiu ngc. + Encoder xoay: mt h thng phn hi m xc nh v tr ca trc hoc o lng s vng quay ca phi t trn trc. + Cm bin khng tip xc, n pht ra mt tn hiu u ra nu c mt vt bng kim loi (nh dao ct nh) vo t trng dao ng ca n. Hai b cm bin khng tip xc c t trn h thng, ni xc nh bt u v kt thc ca ng dn cng c. S dng s bc thang, chng trnh ngn ng ph bin, vn hnh PLC trong h thng c in t. Cc hot ng ca PLC da trn s bc thang nh sau: - Bc 1: c cc tn hiu u vo bn ngoi nh tnh trng ca cc b cm ng hoc encoder quay. - Bc 2: Tnh ton tn hiu u ra, theo gi tr ca cc tn hiu u vo bc 1 v gi cho AC (b bin i) chy ng c AC theo chiu thun/chiu ngc hoc chuyn ng c cho mt gc c bit (bc ren) s dng encoder xoay. Th tc ca ton b h thng c thc hin trong nm giai on: - Giai on 1: Dao nh hnh ti cm bin khng tip xc u tin v s gi mt tn hiu vo PLC. Nh n c cp trc , PLC gi ra mt tn hiu u ra vo AC chy ng c theo chiu thun. Giai on 2: My ct cc phi lun phin. - Giai on 3: Dao ti cm bin khng tip xc th hai v s gi tn hiu th hai n PLC. PLC gi mt lnh ngng n b bin i. - Giai on 4: My rt phi ngng li v tr li n ni u tin ca n. ng thi, PLC s dng cc gi tr o ca encoder xoay quay phi theo hng ngc li cho n khi n t n v tr u tin. - Giai on 5: Giai on 1 n giai on 4 tip tc cho n khi rnh gia 2 rng u tin c ct. PLC m s cho mi mt trong bn giai on trn y cho n n t ti s

H Vit Bnh


lng c xc nh trc ca trnh t gia cng. Sau , n gi i mt tn hiu vo AC phn phi bnh rng mt bc rng knh v tt c cc giai on nu trn s c lp i lp li mt ln na. Th tc trn s dng cn bn ging nh trn mt my phay vn nng, ngoi tr, sau khi thit lp, cc hot ng khc hon ton c t ng. Cu hnh gia cng c hin th trong hnh 9.145.

Hnh 9.145 cu n rng thng:n khai ca bnh rng nn rng thng: Qu trnh ct rng v ng c AC s dng nh mt u phn . Trn y l qu trnh sn xut bnh rng cn rng cong s dng my phay CNC ba trc da trn phng php phay nh hnh. V c bn, hnh thc ct s dng mt phng php n gin v linh hot ca gia cng ca bnh rng. Cc thit b v dao ct yu cu l tng i n gin v r tin, v tiu chun my phay CNC c s dng. So vi cc phng php ct bnh rng quy c, trong dnh ring cho my cng c c yu cu, phng php trnh by c th d dng c sa i sn xut bt k loi v kch thc ca bnh rng cn rng cong hoc bt k cc loi bnh rng. 2. My CNC mi bnh rng cn: a. Qu trnh mi: My ny to ra mt qu trnh vi s phn tng t, bnh mi cn mi ch mt mt bn hoc hai mt bn mt cch ng thi trn mi rnh gia hai rng trong ch xon. C th s dng mi hnh chu cn bn trong. Cc rng hay rnh gia hai rng m t mt chuyn ng ln cho n khi bin dng rng c to ra hon ton. Bn knh ca mi xc nh cong dc theo du vt ng rng v chuyn ng con ln cong hn su rng. Chuyn ng ln bao gm 2 thnh phn: chuyn ng ln ca mi. My gia cng bnh rng cn bng phng php bao hnh c hitherto phi hp nhng di chuyn ny bi nhng bnh rng. Trong my mi bnh rng cn m t y, s phi hp ny th tm c bng cch iu khin in t v hai b truyn ng bin tc, m tc c th phi hp hai chuyn ng ln th ng b t chnh xc cao.

H Vit Bnh


S truyn ng trc mi s dng ng c in 3 pha cng sut ln vi b iu khin tn s. Ngoi ra, bnh lch tm c lp vo trc mi gi c truyn ng vi tc cao bi mt ng c 3 pha khc vi b iu khin tn s tng s nh gi ca s di chuyn vt liu. My cho php bnh rng cn rng cong v bnh rng hypoid vi im chun gc cn khong t 0 n 90 . Bnh rng cn c gia cng bi cc qu trnh khc nhau, c th c mi trn my ny. V vy, khng ch c bnh rng c sn xut bng nhng cng c ca hnh dng cung trn c th c mi, m cn nhng rng vi du vt rng ca bin dng epitrochoid do sn xut bi mt qu trnh phn lin tc. Ngay c bnh rng vi du vt rng ca ng thn khai to ra bi dao phay ln hnh nn v mt qu trnh phn lin tc cng c th c mi trn my ny. Khi my c trang b vi mt g hiu chnh, mi xt nhm hoc, nu thch hp, mi CBN (Cubic Boor Nitrate) c th c s dng. b. M t my: Bnh rng cn rng cong v bnh rng hypoid c th c mi ln ln n mt ng knh ti a l 800 mm. My ny bao gm ba thnh phn c bn: mt gi lc con ln trong trc mi c gn vo, cc trc chnh lm vic v mt g hiu chnh. Ba thnh phn c bn c th hin trong hnh chiu bng ca my trong hnh 9.146.

Hnh 9.146 My mi bnh rng CNC W800 a. Trc chnh (work spindle); b. g hiu chnh (truing attachment); c. Trc mi (grinding spindle); d. Gi lc con ln (roll cradle); e. Bn xe dao (cross-slide). Gi lc con ln c ta trong bc lt v c truyn ng bi 1 bnh vt. Gi lc con ln c mt bn xe dao ci t cc my tm sai, tc l dch chuyn ca trc mi t trc ca gi lc con ln. Bn xe dao c gn theo nhng cch con ln ti trc v c dn ng bi mt vt bi v ng c DC. Cc v tr c o trc tip bi mt h thng o tuyn tnh. Gn trn bn xe dao l cc trc mi v ng c ca n cng vi mt ng c mnh hn cho s xoay lch tm gn trn gi trc mi. Chuyn ng lch tm ny thm mt thi gian ngn lm gim mi t phi ti tng khong mt, s lm mt lin tc c a n cc khu lin h gia chng. Trc chnh lm cho con ln v phn chuyn ng phi. Trc ny cng chy trong nhng vng bi, c t ti u lm vic. u lm vic c kt cu cng c th c iu chnh theo chiu dc trn ct ca n cung cp lch cn thit cho bnh vt. B u lm vic c t trn mt bn dao, c th c thit lp ph hp vi kch thc lp trc. Trc chnh c dn ng bi mt ng c servo v mt bnh vt. My trang b ngun nng lng

H Vit Bnh


thy lc cho kp phi. Gc cn chun c thit lp bi vic xoay u lm vic v trung tm ca my v c hin th k thut s. g hiu chnh c t trn mt b ring bit m c dao ng vo v tr lm vic bng mt xi lanh thy lc. v tr khng lm vic, g hiu chnh c v tr bn ngoi khu vc ca my, n khng can thip vi nhng hot ng ca my v cn tr vic xem xt ca cc nh iu hnh. g hiu chnh c th c quay v mt trc trung tm, cc h thng iu chnh khc nhau c th c s dng. Chuyn ng xoay ny c thc hin bi mt ng c servo v c tch hp vi CNC. c. S iu chnh mi: Nguyn tc ca qu trnh iu chnh c th hin trong hnh. 9.147. C mi v con ln iu chnh c dn ng. Hng quay c th c chn trc tc bin ca chng c th trong cng mt hng hay ngc hng. T l tc quay ca mi v con ln iu chnh cng c th c a dng. Phm vi sa i bin dng c th c thc hin do hnh thc ca cc con ln iu chnh c th c thu thp t cc minh ho. Vic mn mi c b p bi h thng iu khin my. Trong trng hp cc bin dng phc tp th tuy nhin n l tt nht khai thc ng tch hp lin tc CNC cho s iu chnh (hnh 9.147). Trong trng hp ny, mt bnh u kim cng c t trn g hiu chnh. Hnh dng ca mi c sn xut bng cch kim sot ng dn lin tc ca g hiu chnh. Cng trong trng hp ny, gc xin cng c th c iu chnh. H thng iu khin c th lm ra bin dng mi khc nhau, gc chn ren v rnh trn gc khc nhau. Hnh dng ca bin dng ny c th c thay i bng nhng phng tin ca h thng iu khin cho cc mc ch ca vic thay i vt n khp b p cho lch ca cc bnh rng o trong iu kin hot ng hoc lch trong kch thc lp.

Hnh 9.147 S iu chnh bng phng tin ca mt bin dng con ln v kim sot s iu chnh lin tc a. mi (grinding wheel); b1. Con ln iu chnh kim cng (diamond truing roller); b2. Bnh iu chnh (truing wheel). Nh vy c th thay i hnh dng ca mi n gin v d dng trong sut qu trnh mi sa i bin dng rng trn mt rng. iu ny cng lm cho n c th sn xut sa i v t th nghim m khng cn phi sn xut con ln mu ring cho tng bin dng. Mt khi bin dng c sn sng, n c th c sao chp chnh xc bi h thng kim sot.

H Vit Bnh


d. Mi cc bin dng rng khc nhau: Cc bin dng rng khc nhau c s dng trong sn xut bnh rng cn rng cong. Ngoi cc dng hnh trn, cc dng rng khc nh epitrochoids v ng thn khai ang s dng. Rng c dng cung trn c th c sn xut rt n gin bi qu trnh m t. N c th c chng minh ton hc, s khc nhau gia epitrochoids v cung trn th khng ng k. Ngoi thit k kh khc nghit, s khc bit gia epitrochoids v cung trn trong dung sai cho php ca mi. V tr trung tm ca mi tng i vi bnh rng o trong trng hp nh vy, tuy nhin, c s khc cho mt bn phi v mt bn tri ca rng. N c th c nhn thy t hnh 9.148 m ngay c trong trng hp nh vy c th mi cc rng bnh rng.

Hnh 9.148 Mi cc bin dng rng khc nhau. a. Bnh rng o; b. Tm ca mi cho phn lm; c. Bn knh mi cho phn lm; d. Tm ca mi cho phn li; e. Bn knh mi cho phn li; e. Khong cch gia mi trung tm; . Khong cch gia gc con ln thit lp CNC cho php c hai mt bn phi v tri c mi trong mt thit lp bng cch s dng cc v tr trung tm khc nhau ca mi. lch ca mi t trung tm gi lc l phi c thay i bi ln e gia mi mt phi v tri, c th c thc hin rt chnh xc vi s tr gip ca CNC. Mt khc bit v tr gc ca gia gi lc l con ln v phi cng l cn thit v c th c t c chnh xc cao bi s kim sot. iu ny cng cho php dy rng c mang vo kch thc yu cu rt n gin m khng thay i vt n khp. Th nghim lm vic ch ra rng ngay c vi nhng rng dng thn khai c sn xut bi dao phay ln hnh nn cng c th c mi trn my ny. e. Lp trnh ca my: CNC cho php chng trnh c nhp theo nhng cch khc nhau. Lp trnh shopfloor th c th s dng, trong c bit hu ch cho s sa i. Tt c phng php khc ca cch nhp chng trnh th c th do s giao din chun, v d: bi mt bng c l hoc nhp trc tip t mt my tnh trung tm. Phng php th hai th c bit thch hp cho mt my mi bnh rng, bi v cc my c thit lp d liu c th c tnh ton v truyn trc tip cho my tnh trong tnh ton phc tp ca d liu rng v bin dng ca vt n khp,

H Vit Bnh


ti u ha bng my tnh v thc hin trn my sn xut bnh rng c ng ca vi kt qu loi b ca bin dng trong sut cng, vic mi c thc hin nh l mt hot ng sau khi kt thc cng. Cc my tnh trong trng hp ny c s dng khng ch cho pht trin cc m hnh lin lc trong giai on thit k, m cn cho truyn trc tip vo my d liu m truyn t cc tnh ton hnh hc ca phi bi vic mi. Nu cc iu kin hot ng ca cc bnh rng cn lm nhng sa i cn thit, sau d liu c th c nhp trc tip vo h thng iu khin my. Khi kt qu kh quan thu c, m i vo xem xt vic o lch trn bnh rng, sau sa i d liu c th c truyn li cho cc my tnh bi h thng iu khin my. Tc dng l thuyt ca nhng sa i thc hin trn v tr ca cc vt n khp v cc iu kin n khp c th c iu tra bi cc my tnh v cc d liu c th c lu tr cho cc ch lp li. iu ny m bo vic lp li v cc vt n khp c thnh lp trc . 3. Phng php thit lp ng chy dao gia cng cho my phay vn nng CNC ba trc. ng dng vo lp trnh gia cng b mt rng thn khai ca bnh rng nn rng thng: Hin nay, cc my phay CNC ngy cng c s dng rng ri trong gia cng c kh v cho php gia cng cc b mt kh phc tp vi chnh xc cao. Vic gia cng cc b mt phc tp trn my CNC vn nng s dng phng php SSM (sculptured surface machining), bng cch thc hin cc ng chy dao bm theo b mt gia cng. gia cng cc b mt thn khai ca bnh rng, ngi ta thng s dng cc my CNC cng nh dng c ct chuyn dng. Vic s dng thit b chuyn dng cho php t chnh xc v nng sut cao. Tuy nhin, my mc v dng c ct chuyn dng kh t tin, vic trang b thit b nhng khng s dng ht nng sut, s gy lng ph ln. Vi nhng xng sa cha nh, ch trang b my phay vn nng CNC 3 trc hoc 3 trc v vn nng sut gia cng khng phi l ch tiu hng u th phng php SSM t ra c hiu qu trong gia cng b mt thn khai, nht l trong cc bnh rng c moun ln.

Hnh 9.149 ng chy dao gia cng b mt thn khai

Ngoi ra, phng php SMM s dng trong gia cng b mt thn khai ca bnh rng cng c mt s u im: s dng cc loi dao c vn nng, r tin; c th gia cng c cc b mt thn khai trong mt di kch thc v chng loi rng ri; c th gia cng c b mt thn khai ca bnh rng c ng knh ln n rt ln, bnh rng phi tiu chun, bnh rng c ti u ha ng cong chn rng nhm tng bn un ca rng gia cng b mt thn khai, cn thc hin cc ng chy dao ph hp. Hin nay, cc phn mm CAD/CAM/CNC nh Pro/Engineering, Catia, Hypermill... u cho php thit lp t ng cc ng chy dao. Tuy nhin, cc ng chy dao c sn i khi cha tht s ph hp vi yu cu ca cng ngh. Do vy, vic nghin cu phng php thit lp cc ng chy dao ph hp, nhm gia cng cc b mt phc tp, ng dng c th vo vic gia cng b mt thn khai ca bnh rng, thng qua vic lp chng trnh theo tham s trn m lnh G-Code, cng cn c quan tm nghin cu.

H Vit Bnh


a. Phng php thit lp ng chy dao theo ngn ng G-Code gia cng bnh rng nn rng thng: thit lp ng chy dao gia cng mt b mt phc tp, trc ht cn nghin cu hnh hc b mt, t xy dng phng trnh ng chy dao bm theo b mt gia cng. y ch nghin cu vic thit lp ng chy dao gia cng tinh b mt thn khai cu trong bnh rng nn rng thng. * M hnh bnh rng nn rng thng v phng trnh gia cng b mt rng: Phng trnh gia cng b mt rng thn khai trong bnh rng nn rng thng, hay phng trnh cc ng chy dao, da trn phng trnh ng thn khai vng trn. Hnh 9.149 m t cc ng chy dao ph hp gia cng mt rng ca bnh rng nn rng thng. O2 j O O Z

O

Y O0 O0

Bnh rng tng ng th jf

ACf

X rj rCrrr rc FF j mx a Fj x

2 j

O2max

y

refmax rebmax re max rea max

vit c phng trnh gia cng, ta m hnh ha bnh rng nn rng thng bng Hnh 9.150 M hnh bnh rng nn rng thng tp hp cc bnh rng tr trn rng thng tng ng c b rng l Fm (hnh 9.150). Mun ca bnh rng tng ng th j, c tm l O2j:mej = ( AC F j ). DC AC .Z . cos

Trong : dC: ng knh vng chia ngoi ca bnh rng nn. AC: chiu di nn ngoi. Fj: khong cch t bnh rng tng ng, c tm l O2max v c mun ln nht, n bnh rng tng ng ang xt. Z: s rng ca bnh rng nn. Cc thng s khc ca bnh rng tng ng th j:rej = rj cos rebj = rej . cos

H Vit Bnh


refj = reaj 2, 25.m j ; reaj = rej + m j (2) Trong : rj: bn knh vng chia ca bnh rng nn ti v tr ng vi bnh rng tng ng th j. rej, rebj, reaj v refj ln lt l bn knh vng chia, vng c s, vng nh v vng chn rng ca bnh rng tng ng th j.

: gc nn chia.: gc p lc ( = 20o). mj: moun ca bnh rng nn xt trn mt nn ph th j. * Phng trnh gia cng cho bin dng rng thn khai: tin hnh gia cng b mt thn khai bng phng php SSM, ta s dng dao phay ngn u cu (ball mill) c bn knh Re. Phng trnh tham s ca bin dng thn khai pha phi ca bnh rng tr rng thng tng ng th j, hay ta ( xM , yM) ca mt im M bt k trn bin dng ny xt trong mt phng O2jxy, c th vit nh sau (hnh 9.151): xM = rexj cos(inv x ) yM (3) Vi: rexj = rebj / cos xv: inv x = tg x x y N rebj O2j x M rexj x xM xM r rx I yM r ng thn khai phi Re = rexj cos(inv x )

Dao phay ngn u cu ry yM

Vng c s

x

Hnh 9.151 V tr dng c ct trn ng thn khai phi. Nu k n bn knh dao Re, phng trnh (3) tr thnh:

H Vit Bnh


x

Mr

= rexj .cos(inv x ) + Re .sin( x + inv x ) = rexj .cos(inv x ) Re .sin( x + inv x )

yMr (4)

Trong : x l tham s vi: x [0, max ] rexj [rebj , reaj ] max = arccos(reb max / rea max ) Ta trn trc Z ca im M (hnh 9.152): Z Mr = [h0 + h j ] + [(rexj refj ) sin ] Trong : h0 = 2, 2 5m j .sin v h j = (Fmax Fj ) cos f / cos f Vi: f: gc nn chn, f: gc chn rng (hnh 9-150). Tm li, phng trnh gia cng cho bin dng thn khai pha phi c dng: X Mr = rexj cos . cos(inv x ) + Re cos .sin( x + inv x ) Y Mr = rexj cos . cos(inv x ) + Re cos .sin( x + inv x ) ZMr = -[ho + hj]+[(rexj + rerj)sin ] Bng cch tng t, ta xy dng c phng trnh gia cng cho bin dng thn khai pha tri. Bng cch s dng php quay h ta quanh trc Z vi cc gc bng 2 / Z, ta s xy dng c phng trnh gia cng cho cc b mt rng k tip ca bnh rng. Dao phay ngn u cu Gc chng trnh gia Z cng O0 h0 ZM M hj

Fmax

X

Re

Fj

f

f

refj rexjH Vit Bnh 10

Hnh 9.152 S tnh ta Z ca im M.


* Thut ton thit lp chng trnh gia cng theo m G-Code: Trn c s cc phng trnh gia cng vit cho bin dng rng phi v tri, ta xy dng thut ton thit lp t ng chng trnh gia cng trn m G-Code, s dng cho my phay CNC BAZ-15 Heideinen nh trn hnh 9.153. Nhp thng s ca bnh rng nn: moun m, s rng Z,; Nhp ch ct Tnh cc thng s khc: dC, AC, , Fmax, f, repmax, reamax, Xut cc lnh G-Code khi u chng trnh gia cng i = 1; Fj = 0; xr = min; xr = max Gii phng trnh bin dng thn khai pha phi, xut lnh chy dao gia cng bin dng bn phi: G01 X(XMr) Y(YMr) Z(ZMr) xr > xr > xr = xr + x max NO YES Xut lnh chy dao gia cng vng nh rng G03 X(raxj) Y(rayj) Z(razj) R(Re) Gii phng trnh bin dng thn khai pha tri, xut lnh chy dao gia cng bin dng bn tri: G01 X(XMl) Y(YMl) Z(ZMl) xr > xl < xl = xl + x

min NO YES Xut lnh chy dao gia cng vng chn rng G03 X(rfxj) Y(rfyj) Z(rfzj) R(Re) i>=Z YES F>Fj m ax

NO

Quay h ta quanh trc Z gia cng rng k tip ; i = i +1 Fj=Fj+Fj

YES

NO

Dng chng trnh G28, M30 Hnh 9.153 S thut ton lp chng trnh gia cng.

11 H Vit Bnh


Da trn phng php v s thut ton nu trn, xy dng c phn mm Bnh rng nn cho php thit lp chng trnh gia cng theo m G-Code tng thch vi my phay 3 trc CNC BAZ-15 Heidenhen, nhm gia cng tinh b mt thn khai ca mt bnh rng nn c thng s bt k. Phn mm c vit trn ngn ng Visual Basic. Cc menu thao tc chnh trn giao din ca phn mm (hnh 9.154) gm: + Nhp d liu: Nhp cc thng s ca b truyn bnh rng nn rng thng nh mun m, s rng Z1, Z2... Nhp cc thng s v ch ct. + Xut d liu: Tnh ton cc thng s khc ca bnh rng nn rng thng v xut chng trnh gia cng di dng m lnh Gcode. kim nghim chng trnh gia cng v ng chy dao c chn, tin hnh gia cng mt bnh rng nn rng thng trn my phay 3 trc CNC BAZ-15 Heidenhen vi thng s nh sau: m =10, Z = 14. Vic gia cng th bnh rng, s dng cc ng chy dao ca phn mm Pro/Engineer. Sau , tin hnh kim tra mt s thng s ca bnh rng trn my o ba chiu CMM. thun li cho vic gia cng, vt liu bnh rng c chn l nhm c. Kt qu v sai s ca mt vi thng s nh bc rng o trn vng chia v profin rng xt trn mt nn ph ngoi cho trn hnh 9.158 v hnh 9.159. Hnh 9.154 Giao din phn mmBnh rng nn

Hnh 9.155 Xut chng trnh gia cng

Hnh 9.156 Bnh rng nn rng thng sau khi gia cng

Hnh 9.157 Kim tra bnh rng trn my o ba chiu CMM

12 H Vit Bnh


Qua phn tch cc s liu o thu thp c, chi tit gia cng c sai s v bc v sai lch profin rng l rt b, tng ng vi cp chnh xc 5. iu ny phn no khng nh chnh xc bnh rng khi gia cng bng phng php SSM vi ng chy dao va thit lp. Da trn phng php v thut ton trn, tin hnh xy dng c phn mm Bnh rng nn. Phn mm ny cho php xut chng trnh gia cng tinh b mt thn khai ca bnh rng nn rng thng, c thng s ty chn, theo m lnh G-Code tng thch vi my phay CNC BAZ-15 Heideinen, theo ng chy dao men theo bin dng thn khai. Vi bin dng thn khai bn phi ng chy dao i t chn n nh, vi bin dng thn khai bn tri ng chy dao i t nh n chn, cc ng chy dao di chuyn t mt u ln v mt u nh ca bnh rng.

Sai s bc rng ( m)

14 12 10 8 6 4 2 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Rng 6

Sai s profin ( m)

Hnh 9.158 Sai s bc trn bin dng rng tri

5 4 3 2 1

Hon ton c th 0 16 pht trin thut ton 17 18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 -1 v phn mm ni trn lp chng trnh -2 gia cng t ng cho -3 bnh rng nn rng -4 cong, rng nghing im o trn profin trn my phay CNC vn nng 3 trc c bn Hnh 9.159 Sai s cc im o trn profin quay. C th kt hp b mt rng phi vi vic s dng phng trnh ng cong chn rng nhm lp trnh gia cng cc ng cong chn rng c ti u ha.

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13 H Vit Bnh

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3-3.Che Tao Banh Rang Tren May CNC