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Tính Toán Thiết Kế Hệ Thống Truyền Động Và Lựa Chọn Hệ Thống Dẫn Hướng
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TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
MC LC
MC LC ....................................................................................................................................................... 1
Li m u ................................................................................................................................................... 2
CHNG I: TNG QUAN V KT CU V H THNG DN NG CA MY CNC ................................... 3
A. KHI NIM V MY CNC ................................................................................................................. 3
B. KT CU MY CNC: .......................................................................................................................... 4
I. PHN CHP HNH ....................................................................................................................... 4
II. KT CU PHN IU KHIN ....................................................................................................... 8
CHNG II: TNH TON CHN THIT B DN NG H BN MY CNC .............................................. 11
KT CU B TRUYN VITME AI C BI ................................................................................... 11
I. TNH TON LA CHN CM TRC VIT ME BI TRC Y ............................................................... 13
1. Cc thng s u vo .................................................................................................................. 13
2. Bc vt me(l) .............................................................................................................................. 13
3. Lc ct chnh ca my() ........................................................................................................ 13
4. Tnh ton la chn trc vt , ln cho bn my di chuyn theo trc Y ................................. 14
II. TNH TON LA CHN CM VT ME BI TRC Z .......................................................................... 27
1. Cc thng s u vo ................................................................................................................. 27
2. Bc vt me (l) ........................................................................................................................... 28
3. Lc ct chnh ca my ............................................................................................................... 28
4. Tnh ton la chn trc vt , ln cho bn my di chuyn theo trc Z ................................. 29
III. TNH TON RAY DN HNG .................................................................................................. 42
1. C s tnh ton ........................................................................................................................... 43
2. Tnh ton ray dn hng bn Y ................................................................................................ 53
3. Tnh ton ray dn hng bn Z ................................................................................................... 59
Kt lun ....................................................................................................................................................... 65
Ti liu tham kho ..................................................................................................................................... 66
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
Li m u
Trong giai on pht trin i ln theo hng hin i ha, cng nghip ha sn xut ca t nc ta hin nay, th vic s dng cc loi my mc hin i thay th sc lao ng ca con ngi l xu hng tt yu tng nng xut lao ng, to c nhiu sn phm cht lng cao phc v cuc sng, gii phng sc lao ng con ngi.
Trong cng nghip to ra cc sn phm c cht lng tt, bn cao, mu m p v m bo tiu chun, phc v nhu cu cuc sng, pht trin kinh t th cn phi c h thng sn xut t ng bao gm nhiu loi my mc cng nghip hin i khc nhau.
My CNC (computer numerical controlled) l nhng cng c gia cng kim loi tinh t c th to ra nhng chi tit phc tp theo yu cu ca cng ngh hin i. Pht trin nhanh chng vi nhng tin b trong my tnh, ta c th bt gp CNC di dng my tin, my phay, my ct laze, my ct tia nc c ht mi, my t rp v nhiu cng c cng nghip khc. Thut ng CNC lin quan n mt nhm my mc ln s dng logic my tnh iu khin cc chuyn ng v thc hin qu trnh gia cng kim loi. Bi vit ny s tho lun hai loi my ph bin nht trn th trng hin nay l my tin v my phay.
S tin b trong my tnh v tr thng minh nhn to s lm cho nhng chic my CNC tng lai nhanh hn v d vn hnh hn. Tt nhin, gi ca nhng chic my nh vy chc chn s khng r v c th vt qu tm vi ca nhiu cng ty. Tuy nhin, n s a gi ca nhng my CNC c bn thc hin nhng chuyn ng 3 trc ban u xung mt mc nht nh.
Cc loi my CNC s c mt tng lai bng n mnh m. Mt tng ang c pht trin l mt chic my c trc chnh c treo ln bi su thanh ging vt me bi lng vo nhau. Chuyn ng ca trc chnh c iu khin bi mt my tnh phc tp c kh nng thc hin hng triu php tnh m bo ng mc chi tit chnh xc
n ny trnh by v qu trnh tnh ton thit k h thng dn hng cho gia cng di s di chuyn ca 3 trc chnh.
Nhim v chnh:
Tnh chn : Vt me bi ,cm , ng c , ray dn hng.
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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CHNG I: TNG QUAN V KT CU V H THNG DN NG CA MY CNC
A. KHI NIM V MY CNC
CNC vit tt cho Computer(ized) Numerical(ly) Control(led) (iu khin bng my tnh)
cp n vic iu khin bng my tnh cc my mc khc vi mc ch sn xut( c tnh lp li) cc
b phn kim kh( hay cc vt liu khc) phc tp, bng cch s dng cc chng trnh vit bng k
hiu chuyn bit theo tiu chun EIA-274-D, thng gi m G. CNC c pht trin cui thp nin
1940 u thp nin 1950 trong phng th nghim Servomechanism ca trng MIT.
S xut hin ca cc my CNC nhanh chng thay i vic sn xut cng nghip. Cc ng
cong c thc hin d dng nh ng thng, cc cu trc phc tp 3 chiu cng d dng thc
hin, v mt lng ln cc thao tc do con ngi thc hin c gim thiu. Vic gia tng t ng
ha trong qu trnh sn xut vi my CNC to nn s pht trin ng k v chnh xc v cht lng.
K thut t ng ca CNC gim thiu cc sai st v gip ngi thao tc c thi gian cho cc cng vic
khc. Ngoi ra cn cho php linh hot trong thao tc cc sn phm v thi gian cn thit cho thay
i my mc sn xut cc linh kin khc. Trong mi trng sn xut, mt lot cc my CNC kt
hp thnh mt t hp, gi l cell, c th lm nhiu thao tc trn mt b phn. My CNC ngy nay
c iu khin trc tip t cc bn v do phn mm CAM, v th mt b phn hay lp rp c th
trc tip t thit k sang sn xut m khng cn cc bn v in ca tng chi tit. C th ni CNC l cc
phn on ca cc h thng robot cng nghip, tc l chng c thit k thc hin nhiu thao
cc sn xut (trong tm gii hn).
Cc loi my tin CNC ph bin hin nay gm c:
My tin CNC
My phay CNC
My khoan tia la in CNC
My ct dy, n dp CNC
u im ca my CNC:
So vi cc my cng c thng dng, my CNC c nhiu u vit hn, th hin cc im sau:
Gia cng c nhiu chi tit phc tp hn.
Quy hoch thi gian sn xut tt hn.
Thi gian lu thng ngn hn do tp trung nguyn cng cao hn v gim thi gian
ph.
Tnh linh hot cao hn.
ln lot ti u nh hn.
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
Bn phm
iu khin
Chi ph kim tra gim.
Chi ph do ph phm gim.
Hot ng lin tc nhiu ca sn xut.
Gim s nhn cng.
Hiu sut cao.
Tng nng lc sn xut.
B. KT CU MY CNC:
Gm 2 phn chnh l:
+ Phn chp hnh: my, thn my, bn my, bn xoay, trc vt me bi, tch dng c, cm trc
chnh v bng dn hng.
+ Phn iu khin: cc loi ng c, cc h thng iu khin v my tnh trung tm.
M hnh khi qut ca mt my CNC:
I. PHN CHP HNH
PHN IU KHIN PHN CHP HNH
Chng trnh iu khin Phi
Cc c cu iu khin Gia cng kim loi
Tn hiu Mn hnh Chi tit gia cng
-Chuyn ng
-Vn tc
-V tr
-Bo li
-DK tay
-DK t ng
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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1. Thn my v my
Thng c ch to bng cc chi tit gang v gang c bn nn cao gp 10 ln so vi thp v
u c kim tra sau khi c m bo khng c khuyt tt c.
Bn trong thn my cha h thng iu khin, ng c ca trc chnh v rt nhiu h thng
khc.
Yu cu:
- Phi c cng vng cao.
- Phi c cc thit b chng rung ng.
- Phi c n nh nhit.
Mc ch:
- Phi m bo chnh xc gia cng.
- my ton b my to s n nh v cn bng cho my.
2. Bn my:
Bn my l ni g t chi tit gia cng hay g. Nh c s chuyn ng linh hot v chnh
xc ca bn my m kh nng gia cng ca my CNC c tng ln rt cao, c kh nng gia cng
c nhng chi tit c bin dng phc tp.
a s trn cc my CNC hay trung tm gia cng hin i th bn my u l dng bn my xoay
c, n c ngha nh trc th 4, th 5 ca my. N lm tng tnh vn nng cho my CNC.
Yu cu ca bn my:
Phi c n nh, cng vng, c iu khin chuyn ng mt cch chnh xc.
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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3. Cm trc chnh:
L ni lp dng c, chuyn ng quay ca trc chnh s sinh ra lc ct ct gt phi trong
qu trnh gia cng.
- Ngun ng lc iu khin trc chnh: Trc chnh c iu khin bi cc ng c. Thng
s dng ng c Servo theo ch vng lp kn, bng cng ngh s to ra tc iu khin
chnh xc v hiu qu cao di ch ti nng.
H thng iu khin chnh xc gc gia phn quay v phn tnh ca ng c trc chnh tng
momen xon v gia tc nhanh. H thng iu khin ny cho php ngi s dng c th tng tc
ca trc chnh ln rt nhanh.
- Cc dng iu khin trc chnh.
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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4. Bng dn hng
H thng thanh trt dn hng c nhim v dn
hng cho cc chuyn ng ca ban theo X,Y v chuyn
ng theo trc Z ca trc chnh.
Yu cu ca h thng thanh trt trt phi thng,
c kh nng ti cao cng vng tt, khng c hin
tng dnh, trn khi trt.
5. Trc vit me, ai c
Trong my cng c iu khin s ngi ta thng
s dng hai dng vit me c bn l: vt me ai c
thng v vt me ai c bi:
Vt me ai c thng: l loi vt me v ai c c dng tip xc mt
Vt me ai c bi: l loi m vt me v ai c c dng tip xc ln.
6. tch dng c
Dng tch cha nhiu dao phc v cho qu trnh gia cng. Nh c tch dao m my CNC c
th thc hin c nhiu nguyn cng ct gt khc nhau lin tip vi nhiu loi dao ct khc nhau.
Do qu trnh gia cng nhanh hn v mang tnh t ng ho cao.
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
C 3 dng chnh:
7. Cc xch ng ca my
Tt c cc ng chuyn ng n tng c cu chp hnh ca my cng c iu khin s u
dng nhng ngun ng lc ring bit, bi vy cc xch ng hc ch cn 2 loi c bn sau:
- Xch ng hc tc ct gt
- Xch ng hc ca chuyn ng chy dao
Vic tnh ton thit k, ch to c thc hin theo modun ho.
Thng thng cc xch ct gt bt u t mt ng c c tc thay i v cp, dn ng trc
chnh thng qua mt hp tc c t 2 n 3 cp , nhm khuch i cc momen ct t tr s cn
thit trn c s tc ban u ca ng c.
II. KT CU PHN IU KHIN
1. Cc cm iu khin chnh trn my CNC
- Cm iu khin my MCU(Machine Control Unit)
Cm iu khin c hnh thnh trn c s thit b iu khin in t, thit b vo ra v cc
thit b s. N c coi l tri tim ca my cng c iu khin s CNC.
Lnh CNC thc hin bn trong b iu khin s thng bo cho m t chuyn ng quay ng s
vng cn thit trc vit me bi quay ng s vng quay tng ng ko theo chuyn ng thng
ca bn my v dao.
Thit b phn hi u kia ca vit me bi cho php kim sot kt thc lnh ng khi s vng
quay cn thit c thc hin.
- Cm dn ng(Driving Unit)
Cm dn ng l tp hp nhng ng c, sensor phn hi, phn t iu khin, khuch i v cc
h dn ng. Trong , ng c v cc sensor phn hi l thnh phn c trng cho my cng c
iu khin s CNC:
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Cm iu khin c nhim v lin kt cc chc nng thc hin iu khin my, cc chc nng
bao gm:
+ S liu vo (Data input)
+X l s liu (Data procesing)
+ S liu ra (Data output)
+Ghp ni vo (Machine I/O interface)
+Phn cng iu khin: gm 6 thnh phn c bn
My tnh CPU
B nh RAM, ROM
H thng BUS
iu khin trnh t PMC
iu khin SERVO
B phn ghp ni
2. Cc loi ng c trn my CNC
a. ng c mt chiu:
- u im: + Momen khi ng ln, d iu khin tc v chiu, gi thnh r.
- Nhc im: + Di tc iu khin hp.
+ Phi c mch ngun ring.
b. ng c xoay chiu:
- u im: + Cp ngun trc tip t in li xoay chiu.
+ a dng v phong ph v chng loi, gi thnh r.
- Nhc im: + Phi c mch cch ly gia phn iu khin v phn chp hnh m bo
an ton, momen khi ng nh.
+ Mch iu khin tc phc tp.
c. ng c bc:
- u im: + iu khin v tr, tc chnh xc, khng
cn mch phn hi.
+ Thng c s dng trong cc h thng my CNC.
- Nhc im: + Gi thnh cao, momen xon nh, momen
my nh.
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
d. ng c servo:
ng c servo c thit k cho nhng h thng hi tip
vng kn. Tn hiu ra ca ng c c ni vi mt mch iu
khin. Khi ng c quay, vn tc v v tr s c hi tip v
mch iu khin ny. Nu c bt k l do no ngn cn chuyn
ng quay ca ng c, c cu hi tip s nhn thy tn hiu ra
cha t c v tr mong mun. Mch iu khin tip tc chnh
sai lch cho ng c t c im chnh xc.
Loi ng c ny c mt s c im chung nh sau:
- Momen qun tnh nh.
- c im ng hc tt.
- Thng c tch hp sn cm bin o tc hay gc quay.
- C di tn s cng tc rng 0400 Hz.
H thng c kh trong my phay CNC 3 trc
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
CHNG II: TNH TON CHN THIT B DN NG H BN MY CNC
Cc thit b dn ng c mt vai tr quan trng trong my CNC, l nhn t chnh m bo s vn
hnh v gia cng chnh xc ca my. Vic tnh ton la chn cc thit b dn ng l mt cng vic
bt buc v phc tp vi nhiu cng thc cn thit lp. V vy, thun tin cho cng vic la ch
thit b dn ng, trong chng ny chng ta i xy dng cng thc tnh ton v chng trnh tnh
chn cc thit b dn ng.
Ni dung chng ny gm c:
Tnh chn vt me.
Tnh chn block, thanh ray dn hng.
Cc tnh ton c thc hin theo catalog ca hng PMI.
KT CU B TRUYN VITME AI C BI
a) Kt cu chung:
B truyn vitme ai c thng c dng trong chuyn ng chy dao ca my cng c NC,
CNC v dng trong cc my cng c chnh nh my mi, my doa tc v cc loi my khc. i
khi cn dng trong my tin, my t hp, dng trong truyn dn di ng x, tr v cc my cng c
hng nng. Ngoi ra cn dng trong b truyn chnh ca cc loi my c chuyn ng tnh tin kh
hi nh my bo ging, my chut.
Cc u im:
- Khc phc r khp ren, chu lc ko vi kt cu m bo cng vng chiu trc cao.
- Tn tht do ma st b, hiu sut b truyn t ti 0,9 so vi vt me ai c trt l 0,2 0,4.
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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- Gn nh c lp hon ton vi lc ma st (bin i theo tc ), ma st tnh rt b nn chuyn
ng m.
Hnh 2.2. Kt cu s b ca vt me ai c bi
Kt cu b truyn vt me - ai c bi hnh trn bao gm trc vt me, ai c, dng bi
chuyn ng trong vt me - ai c v ng hi bi m bo dng bi tun hon lin tc.
b) Cc dng profil ren ca vitme v ai c:
Dng ch nht (hnh b), dng hnh thang (hnh c), dng na cung trn v dng
rnh (dng cung nhn). Dng ch nht v dng prfin ren hnh thang c kh nng ti
thp, ch dng khi my c kh nng chu ti trng chiu trc b v cng vng khng
cao.
Dng na cung trn (hnh d) c s dng ph bin nht, bn knh rnh r2 gn
bng bn knh vin bi R1 s gim ti a ng sut tip xc, c th chn r2/r1=0,950,97,
gi tr r2/r1 s lm tn tht do ma st 1 cch r rt. Ti gc tip xc b th b truyn c
cng vng b v kh nng ti b, lc hng knh s ln. Do tng gc tip xc th kh
nng o v cng vng truyn ng tng v h thp tn tht do ma st v vy khe h
ng knh d phi chn gc tip xc t 45. d = 4.(r2 r1 ).(1 cos ) .
Hnh 2.3. Cc dng profin ren vt me v bi
Dng rnh cung nhn (a) c nhiu u im hn loi cung trn, n cn cho php
truyn ng khng r hoc chn c di ca ng knh vin bi. Cn dng na
trn mun kh r v to di u dng thm ai c th hai iu chnh .
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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I. TNH TON LA CHN CM TRC VIT ME BI TRC Y
1. Cc thng s u vo
- Loi my CNC : Phay - Ch ct th nghim ti a SVT :
Phay mt u Dao c 8 li (z=8), ng knh D= 80mm Tiu chun quc gia : JIS Vt liu SUS440C Grade 4040 Vn tc : v= 100m/ph Chiu su ct : t= 0,8mm Lng chy dao pht : F=900mm/ph
- Khi lng ln nht ca chi tit : M=400KG => W=400kgf=4000N
- Trng lng bn g trc Y : Wy=2300N
- Vn tc chy ln nht khi khng gia cng : V1=18m/ph - Vn tc chy ln nht khi gia cng : V2 = 12m/ph
- Gia tc hot ng ln nht ca h thng : a=0,5g=5m/s2 - Thi gian hot ng : Lt= 25000h ( khong 8,6 nm) - Tc vng ng c : Nmax = 2000rpm - chnh xc v tr khng ti : 0,03/1000mm - chnh xc lp : 0,005mm - lch truyn ng : 0,02mm
- H s ma st trn b mt : =0,1
2. Bc vt me(l)
l Vmax
Nmax =
1
Nmax=
18000
2000= 9mm
Chn l = 10mm
3. Lc ct chnh ca my()
tm lc ct chnh ca my ta s dng cng c trn website www.coroguide.com . Tnh ton v chn thng s u vo in vo cng c :
- Feed per cutting edge (Fz)- Lng chy dao rng + Tc quay ca ng c quay dao :
n= 1000v
=
1000.100
.80=397,89 ( vng/ph)
+ Lng chy dao vng :
S=
=
900
397,89=2,3 (mm/vng )
+ Lng chy dao rng : Fz=S/8 = 0,28 (mm/rng ) ( Theo cng thc trong cun S tay CN-CTM tp 2-trang 26 ) - Working engagement (ae) & working engagement start (aei)
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Chn ae & aei sao cho : ae + aei = Dc = 80mm Ta chn : ae = 80mm , aei =0 - Mayjor cutting adge angle (K) : thng chn K= 60
Sau khi tnh ton ,la chn kt hp vi cc thng s cho ta in vo bng ca cng c ta c kt qu nh trong hnh :
Mc= 71Nm . => Fm = 2.Mc/Dc= 2.71/0,08 = 1775N = 177,5 kgf
4. Tnh ton la chn trc vt , ln cho bn my di chuyn theo trc Y 4.1. iu kin lm vic v cc thng s c tnh chn
iu kin lm vic - Lc chng trt : Fa = .( M + Wy) = 0,1. ( 4000+2300) = 630N = 63 kgf
Cc thng s c tnh chn : Loi bi Cp chnh xc lch v tr v nhit M men ng c
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
4.2. Chn trc vt bi
4.2.1. Tnh ton lc dc trc
Cc thnh phn trong cng thc :
+ Lc ct chnh ca my : Fm = 1775N = 177,5 kgf
+ Lc ct theo phng z ( phng thng ng ) : Fmz = 0
+ H s ma st ln : 0,1
+ Khi lng tng cng : m= M + Wy =630 kg
+ Lc chng khng ti : f = 63kgf = 630 N
+ Gia tc trng trng : g= 10 m/s2
Tnh cc lc dc trc o Tng tc (v pha sau): Fa1 = mg + ma + f = 0,1.630.10 + 630.5 + 630 = 4410 N =
441 kgf o Chy u (v pha sau): Fa2 = mg + f = 0,1.630.10 + 630 = 1260 N = 126 kgf
o Gia cng (v pha trc): Fa3 = Fm + (mg + Fmz) + f = 1775 + 0,1.(630.10 + 0 ) + 630 = 3035 N = 303,5 kgf
o Gim tc (v pha trc): Fa4 = mg - ma + f = 0,1.630.10 630.5 + 630 = -1890N = 189 kgf
Lc dc trc ln nht khi khng gia cng : F1max = 4410 N = 441 kgf Lc dc trc ln nht khi gia cng : F2max = 3035 N = 303,5 kgf
Lc dc trc trung bnh :
=
. . .
=
. . + .
. + .
Trong :
F1max, F2max: Lc dc trc ln nht khi khng gia cng v gia cng
N1max, N2max: Tc quay ln nht ca trc khi khng gia cng v gia cng
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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T1, T2: Thi gian my hot ng ch khng ti v c ti
Bng lc dc trc v phn trm tng ng:
Axial load
(kgf)
Rotation speed
(rpm)
Time Ratio
(sec or %)
F1max = 4410 N 1800 30
F2max = 3035 N 1200 70
= 44103 1800 0,3 + 30353 1200 0,7
1800 0,3 + 1200 0,7
3
= 3698 = 369,8
( Trong phn tnh lc dc trung bnh ny ta ly Fi 2 trng hp khi khng gia cng v khi gia cng . Vi cc t l thi gian ln lt 30% & 70% , ta xt trong giai on n nh ca my nn Ni l nh nhau ti cc thi im .)
4.2.2. Tnh ton ti trng (Co, Ca)
Ti trng tnh :
Cc cng thc tnh tng ng:
C0 = fs . Famax
Trong :
C0: ti trng tnh
fs: h s bn tnh, vi my cng c fs = 1,5 3 (chn fs = 2)
Famax: lc dc trc ln nht tc dng ln vitme
C0x = 2.4410 = 8820 N
Ti trng ng :
Vi l = 10 mm => Vn tc quay danh ngha l :
Nm = V1/l = 18000/10 = 1800 ( vng/ph)
Ca = (60 Nm Lt)1 3 Fma fw 10-2
= (60 * 1800 * 25000)1/3 * 369,8 * 1.2 * 10-2
= 6179 kgf.
4.2.3. Chn kiu bi
Nu cng cn c u tin nhiu nht, hao ph chuyn ng khng qu quan trng , theo cc thng so kch thc s c chn l :
+ bi loi lu chuyn : bi bn ngoi + Kiu : FDWC
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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+ S dng lu chuyn : B 3
4.2.4. Chn bn knh trc vit
L= tng chiu di di chuyn max + chiu di ai c, bi/2 + chiu di vng thot = 1000 + 100 + 200 = 1300mm
Kiu bi l lp cht c hai u -> f = 21,9
Chn tc quay cho ng c khong 80% so vi tc quay gii hn nn ta c :
n=80%. Nmax = 80%. 2000 = 1600 vng/ph.
Bn knh trc vt :
dr = 2
. 107 =
1600.13002
21,9. 107 = 12,35mm
4.2.5. Chn series
T cc tnh ton trn ta chn series :
Loi trc vit me : 45-10B3-FDWC
ng knh trc : 45 mm
Bc vt : 10mm
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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4.2.6. Chiu di trc vitme
Chiu di trc vt me sau khi chn trc :
L= tng chiu di dch chuyn + chiu di ai c + chiu di vng thot = 1000 + 243 + 200 = 1443mm => 1450mm
4.2.7. Kim tra s b
+ Tui th lm vic :
Lt = (Ca
Fmy .fw)
3
. 106 . 1
60 .Nm
= (7760
369,8 .1,2)
3 .106 .
1
60 .1800
= 28255 h > 25000h
+ Tc quay cho php:
n = f . dr
L2 .107 = 21.9 .
45
14502 . 107 = 4687 vg/ph.
4.2.8. Chn chnh xc di
chnh xc c tr yu cu l : 0,03/1000mm
Chn cp chnh xc vi lch & bin dng tch lu l :
Cp chnh xc : C4
E = 0,025/1250mm
E = 0,018mm
4.2.9. dch do thay i nhit ( mc iu chnh 3 )
+ dch do nhit:
L = . . = 12 .10-6 . 3 .1450 = 0,05mm.
+ Bn knh li ren ca trc vt-me:
dr = 45 +1,4 6,35 = 38,05 mm ( tra trn catalog PMI )
+ Lc gy ra:
F = L . Ks = L .E ..dr
2
4L =
0,05.2,1.104..38,052
4.1450 = 823kgf
4.3. Chn ng c cho bn Y : - Tc vng ln nht : 2000 vng/pht - Thi gian cn thit t tc ln nht 0,9s (t chn da trn th dch
chuyn hnh v)
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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4.3.1. Momen qun tnh khi
Trn trc vit-me:
2 =
8 4 =
7,8 103
8 4,54 145 = 182(. 2)
Trn phn dch chuyn
2 = (
2)
2
= 630 (1
2)
2
= 16 (. 2)
Trn phn ghp ni
2 =
4
32=
7,8 103 (3) (1,7)4
32
=7,8 103 (3.4,5) (1,7.4,5)4
32= 35,4 (. 2)
D l ng knh trc vt, l chiu di ni trc Tng m men qun tnh
2 =
2 + 2 +
2 = 182 + 16 + 35,4 = 233,4(. 2)
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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4.3.2. M men pht ng
Thi gian dnh cho qu trnh c gia tc l rt ngn, do y ta ch tnh ton cho giai on chy u ( chim phn ln thi gian gia cng )
M men t trc :
= 0
2= 0,3
147 1
2= 7(. )
Trong = 0,3 ; 0 = /3 = 441/3 = 147kgf M men do lc ma st
=
2 =
441 1
2 0,9= 78(. )
Do , momen pht ng cn thit bng tng momen t trc v momen cn thit khi gia cng:
= + = 78 + 7 = 85(. )
4.3.3. Chn ng c
Chn ng c servo iu khin qu o chuyn ng theo trc Oy
Cc d liu cho tnh chn ng c :
Chn vit-me c bc h = 10mm
H s ma st trt gia thp v gang ta chn =0,12
Gia tc trng trng g = 10 m/s2
Khi lng ca phn u dch chuyn l m = 630 kg
Gc nghing ca trc = 0 .
T s truyn gim tc i = 1. (Do chn phng n ng c ni trc tip vi vit-me khng qua hp gim tc )
Hiu sut ca my chn = 0,9.
Lc ct ln nht Fm = 1775N = 177,5 kgf
Tc quay ln nht ca ng c 2000 vg/ph Tnh m men ma st :
=....
2... =
630.10.0,12.0,01.cos (0)
2..1.0,9 = 1,3N.m
Tnh tnh m men chng trng lc ca kt cu
=
2 = 0
V c cu nm ngang nn = 0 hay = 0 Tnh vn tc di Vi ng knh trc vt c chn l 45mm,ta c :
=
60 1000=
45 2000
60 1000= 4,7
Tnh m men my
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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=
2 . =
0,01 1775
2 1 0,9 4,7= 0,7 .
Tnh m men tnh = + + = 1,3 + 0 + 0.7 = 2 .
Tnh tc quay ca motor :
=
=
4,7.1
0,01= 470 ( )
Da vo m men tnh ca ng c v tc ca motor, t chn loi ng c AM 1400C ca hng ANILAM www.anilam.com c momen khi ng l 13 N.m v tc quay ln nht l 2000rpm nh hnh di :
iu kin : nmotor nnoml Mmotor Mstat
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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4.3.4. Kim tra thi gian cn thit t c vn tc cc i
Thi gian cn thit t c vn tc cc i l :
ta =J
TM TL
2N
60 f
Trong : J l tng m men qun tnh. (Momen tnh ton + momen cho bi ng c Rotor Inertia J )
TM = 2. , ( > 1)
TL l m men quay f l h s an ton ( chn theo kiu lp ) Thay s vo ta c :
ta =(233,4+43).104
2.1185.10.102
2.2000
60 1,2 = 0,5 < 0,9s => tho mn
4.3.5. Tnh ton ng sut tc dng ln trc vt
=
=
2
4=
4410 4
38,052= 3,88 (
2) = 3,88 106(
2)
= = 85. = 8500.
=4
32=
38,054
32= 2057874
=
=
8500 22,5
205787= 0,93 (
2) = 0,93 106(
2)
= 2 + 22
= 3,99 106(
2)
4.4. Tnh ti trng ti hn ca trc vit
= 2
2=
4
2 103 = 20,3.
38,054
14502 103 = 20239 = 441
=> Do vy , trc vit-me m bo an ton
4.5. Tnh chn cm ln, khp ni
4.5.1. Cm ln
a. Chn ln
Trong c cu bn Y ti trng ch yu tc ng ln 2 ray dn hng, do m lc tc dng theo phng vung ln c cu trc vit me l khng ng k hay ni cch khc khi tnh ton n ln trc vitme ch n lc dc trc tc dng ln trc vit me. Tuy nhin trong qu trnh hot ng xy ra hin tng rung trong c cu, do yu t nh tm cng quan trng, do vy
=> chn chn 1 dy cho trng hp ny
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Tnh ton kh nng ti ng:
= . 1
Tnh ton kh nng ti tnh:
0 = 0. 1
Trong :
m = 3 i vi bi m=10/3 vi a.
L: tui th ca ln c tnh theo cng thc:
= 60. 106. . = 60. 106. 1800.25000 = 2700( )
Q: ti trng ng ca ln c tnh:
= (. . + . ). .
Q0: ti trng tnh ca ln c tnh:
0 = (0. . + 0. ). .
K = 1,1 (chu va p nh, chu ti ngn hn v ti 125% so vi ti trng tnh ton: my ct kim loi, ng c cng sut nh v trung bnh)
Kt = 1 (nhit
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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RA = RB = RC = RD = m.g/4 = 630.10/4 = 1575 N
Da vo ng knh trc vitme v tc quay ca ng c ta chn s b thng s ca ln m 7308 BEP theo hng SKF (www.skf.com ) nh sau :
Kh nng ti ng: Cr = 46,2 kN
Kh nng ti tnh: Cor = 30,5 kN
Ni lc dc trc Fsi ca 4 l nh nhau:
Fsi = e.Ri =1.14.1575 = 1795,5 N
Lc dc trc tc dng ln cc bi:
- vi A: = + /2 = 1795,5 + 3698/2 = 54
suy ra: FaA = 1795,5 N
- vi B: = + /2 = 1795,5 + 3698/2 = 3644
suy ra: FaB = 3644 N
vi C: = + /2 = 1795,5 + 3698/2 = 54
suy ra: FaC = 1795.5 N
- vi D: = + /2 = 1795,5 + 3698/2 = 3644
suy ra: FaD = 3644 N
Fa = max( FaA, FaB, FaC, FaD ) = 3644 N
Kim tra :
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Mt khc :
.
=3644
1575= 2,3 > 1,14
T bng :
Chn : X = 0,35 v Y = 0,57
Tnh ti trng ng:
= (0,35.1575 + 0,57.3644). 1,1.1 = 2891,163
Kh nng ti ng:
= 2891.163 270013 = 40259 < = 46,2
Tnh ti trng tnh:
Xc nh h s X0 , Y0 :
Suy ra: X0 = 0,5 ; Y0 = 0,26
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Tnh ti trng tnh:
0 = 0,5.1575 + 0,26.3644 = 1734,9
Kh nng ti tnh:
0 = 1734,9 270013 = 24158 < 0 = 30,5
Vy la chn bi ph hp vi kh nng ti
b. Chn gi
Do yu cu ca c cu cng vi s tham kho cc ngun ti liu v chn gi em chn 2 gi u l loi gi c nh nhm hn ch s di chuyn dc trc theo tiu chun ca hng SKF.
Vi c s la chn da trn ng knh trc vitme v ti trng dc trc l chnh, em xin chn gi mang m FSNL 511-609. ( y c mt cht tng ng gia vng bi t la v vng bi chn nn gi cng c s tng thch vi vng bi chn nh tnh ton).
4.5.2. Chn khp ni
C rt nhiu loi khp ni ta la chn cho bi ton ny nhng trn c s tham kho ti liu
v thc nghim t cc hng sn xut em xin chn loi khp ni l loi khp ni trc loi trc b ch thp c m .
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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( tham kho cun Tnh ton thit k h dn ng c kh L Vn Uyn tp 2 trang 55 ).
C th chn thng s cho loi khp ni trc ch thp ny cn c theo ng knh trc vitme v theo gi tr m men khi ng ca ng c. ( xem thm mc thng s ca ng c AM-1400C).
Trn c s em chn thng s cho khp ni nh sau :
II. TNH TON LA CHN CM VT ME BI TRC Z
1. Cc thng s u vo
- Loi my CNC : Phay - Ch ct th nghim ti a SVT :
Phay mt u Dao c 8 li (z=8), ng knh D= 80mm Tiu chun quc gia : JIS Vt liu SUS440C
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Grade 4040 Vn tc : v= 100m/ph Chiu su ct : t= 0,8mm Lng chy dao pht : F=900mm/ph
- Khi lng ln nht ca chi tit : M=400KG => W=400kgf=4000N
- Trng lng bn g trc Z : Wz=1550N - Vn tc chy ln nht khi khng gia cng : V1=18m/ph - Vn tc chy ln nht khi gia cng : V2 = 12m/ph
- Gia tc hot ng ln nht ca h thng : a=0,5g=5m/s2 - Thi gian hot ng : Lt= 25000h ( khong 8,6 nm) - Tc vng ng c : Nmax = 2000rpm - chnh xc v tr khng ti : 0,03/1000mm - chnh xc lp : 0,005mm - lch truyn ng : 0,02mm - H s ma st trn b mt : =0,1
2. Bc vt me (l)
l Vmax
Nmax =
1
Nmax=
18000
2000= 9mm
Chn l = 10mm
3. Lc ct chnh ca my
tm lc ct chnh ca my ta s dng cng c trn website www.coroguide.com . Tnh ton v chn thng s u vo in vo cng c :
- Feed per cutting edge (Fz)- Lng chy dao rng + Tc quay ca ng c quay dao :
n= 1000v
=
1000.100
.80=397,89 ( vng/ph)
+ Lng chy dao vng :
S=
=
900
397,89=2,3 (mm/vng )
+ Lng chy dao rng : Fz=S/8 = 0,28 (mm/rng ) ( Theo cng thc trong cun S tay CN-CTM tp 2-trang 26 ) - Working engagement (ae) & working engagement start (aei)
Chn ae & aei sao cho : ae + aei = Dc = 80mm Ta chn : ae = 80mm , aei =0 - Mayjor cutting adge angle (K) : thng chn K= 60
Sau khi tnh ton ,la chn kt hp vi cc thng s cho ta in vo bng ca cng c ta c kt qu nh trong hnh :
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Mc= 71Nm . => Fm = 2.Mc/Dc= 2.71/0,08 = 1775N = 177,5 kgf
4. Tnh ton la chn trc vt , ln cho bn my di chuyn theo trc Z
4.1. iu kin lm vic v cc thng s c tnh chn iu kin lm vic
- Lc chng trt : Fa = . Wz = 0,1. 1550 = 155N = 15,5 kgf
Cc thng s c tnh chn : Loi bi Cp chnh xc lch v tr v nhit M men ng c
4.2. Chn trc vt bi :
4.2.1.Tnh ton lc dc trc
Cc thnh phn trong cng thc :
+ Lc ct chnh ca my : Fm = 1775N = 177,5 kgf
+ Lc ct theo phng z ( phng thng ng ) : Fmz = 0
+ H s ma st ln : 0,1
+ Khi lng tng cng : m= Wz =155 kg
+ Lc chng khng ti : f = Fa= 15,5 kgf = 155 N
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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+ Gia tc trng trng : g= 10 m/s2
Tnh cc lc dc trc o Tng tc (i ln ): Fa1 = mg + ma = 155.10 + 155.5 = 2325 N = 232,5 kgf o Chy u (i ln): Fa2 = mg = 155.10 = 1550 N = 155,5kgf
o Gia cng (i ln): Fa3 = Fmz + Fm + mg = 0+ 0,1.1775 + 155.10 = 1727,5N = 172,75 kgf
o Gim tc (i ln): Fa4 = mg - ma = 155.10 155.5 =775N = 77,5 kgf Lc dc trc ln nht khi khng gia cng : F1max = 2325 N = 232,5kgf Lc dc trc ln nht khi gia cng : F2max = 1727,5 N = 172,75 kgf
Lc dc trc trung bnh :
=
. . .
=
. . + .
. + .
Trong :
F1max, F2max: Lc dc trc ln nht khi khng gia cng v gia cng
N1max, N2max: Tc quay ln nht ca trc khi khng gia cng v gia cng
T1, T2: Thi gian my hot ng ch khng ti v c ti
Bng lc dc trc v phn trm tng ng:
Axial load
(kgf)
Rotation speed
(rpm)
Time Ratio
(sec or %)
F1max = 2325 N 1800 30
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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F2max = 1727,5 N 1200 70
= 2325318000,3+1727,5312000,7
18000,3+12000,7
3= 2004,7 = 200,47
( Trong phn tnh lc dc trung bnh ny ta ly Fi 2 trng hp khi khng gia cng v khi gia cng . Vi cc t l thi gian ln lt 30% & 70% , ta xt trong giai on n nh ca my nn Ni l nh nhau ti cc thi im .)
4.2.2. Tnh ton ti trng (Co, Ca)
Ti trng tnh :
Cc cng thc tnh tng ng:
C0 = fs . Famax
Trong :
C0: ti trng tnh
fs: h s bn tnh, vi my cng c fs = 1,5 3 (chn fs = 2)
Famax: lc dc trc ln nht tc dng ln vitme
C0 = 2.2325 = 4650 N
Ti trng ng :
Vi l = 10 mm => Vn tc quay danh ngha l :
Nm = V1/l = 18000/10 = 1800 ( vng/ph)
Ca = (60. Nm. Lt)1 3 .Fma . fw .10-2= (60 .1800 . 25000)1/3 .200,47 .1,2 .10-2 =
3349,8 kgf.
4.2.3. Chn kiu bi
Nu cng cn c u tin nhiu nht, hao ph chuyn ng khng qu quan trng , theo cc thng so kch thc s c chn l :
+ bi loi lu chuyn : bi bn ngoi + Kiu : FDWC + S dng lu chuyn : B 2
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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4.2.4. Chn bn knh trc vit
L= tng chiu di di chuyn max + chiu di ai c, bi/2 + chiu di vng thot = 1000 + 100 + 200 = 1300mm
Kiu bi l lp cht c hai u -> f = 21,9
Chn tc quay cho ng c khong 80% so vi tc quay gii hn nn ta c :
n=80%. Nmax = 80%. 2000 = 1600 vng/ph.
Bn knh trc vt :
dr = 2
. 107 =
1600.13002
21,9. 107 = 12,35mm
4.2.5. Chn series
T cc tnh ton trn ta chn series :
Loi trc vit me : 40-10B2-FDWC
ng knh trc : 40 mm
Bc vt : 10mm
4.2.6. Chiu di trc vitme
Chiu di trc vt me sau khi chn trc :
L= tng chiu di dch chuyn + chiu di ai c + chiu di vng thot = 1000 + 141 + 200 = 1341mm => 1350mm
4.2.7. Kim tra s b
+ Tui th lm vic :
Lt = (Ca
Fmz .fw)
3
. 106 . 1
60 .Nm= (
3349,8
200,47 .1,2)
3
. 106 . 1
60 .1800
=25100 h > 25000 h
+ Tc quay cho php:
n = f . dr
L2 . 107 = 21,9 .
40
13502 . 107 = 4807 vg/ph.
4.2.8. Chn chnh xc di
chnh xc c tr yu cu l : 0,03/1000mm
Chn cp chnh xc vi lch & bin dng tch lu l :
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Cp chnh xc : C4
E = 0,025/1250mm
E = 0,018mm
4.2.9. dch do thay i nhit ( mc iu chnh 3 )
+ dch do nhit:
L = . . = 12 . 10-6 . 3 .1350 = 0,049mm.
+ Bn knh li ren ca trc vt-me:
dr = 40 + 1,4 6,35 = 35,05mm.
+ Lc gy ra:
F = L .Ks = L .E . .dr
2
4L =
0.049.2,1.104..35,052
4.1350 = 735kgf
4.3. Chn ng c cho bn Z : - Tc vng ln nht : 2000 vng/pht - Thi gian cn thit t tc ln nht 0,9s (t chn da trn th iu
kin dch chuyn hnh v )
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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4.3.1. Momen qun tnh khi
Trn trc vit-me:
2 =
8 4 =
7,8 103
8 44 135 = 105,86(. 2)
Trn phn dch chuyn
2 = (
2)
2
= 155 (1
2)
2
= 7,85(. 2)
Trn phn ghp ni
2 =
4
32=
7,8 103 (3) (1,7)4
32
=7,8 103 (3.4) (1,7.4)4
32= 19,65 (. 2)
D l ng knh trc vt, l chiu di ni trc Tng m men qun tnh
2 =
2 + 2 +
2 = 105,86 + 7,85 + 19,65 = 133,36(. 2)
4.3.2. M men pht ng
Thi gian dnh cho qu trnh c gia tc l rt ngn, do y ta ch tnh ton cho giai on chy u ( chim phn ln thi gian gia cng )
M men t trc :
= 0
2= 0,3
77,5 1
2= 3,7(. )
Trong = 0,3 ; 0 = /3 = 232,5/3 = 77,5kgf
M men do lc ma st
=
2 =
232,5 1
2 0,9= 41,1(. )
Do , momen pht ng cn thit bng tng momen t trc v momen cn thit khi gia cng:
= + = 3,7 + 41,1 = 44,8(. )
4.3.3. Chn ng c
Chn ng c servo iu khin qu o chuyn ng theo trc Oy
Cc d liu cho tnh chn ng c :
Chn vit-me c bc h = 10mm
H s ma st trt gia thp v gang ta chn =0,12
Gia tc trng trng g = 10 m/s2
Khi lng ca phn u dch chuyn l m = 155 kg
Gc nghing ca trc = 90 .
T s truyn gim tc i = 1. (Do chn phng n ng c ni trc tip vi vit-me khng qua hp gim tc )
Hiu sut ca my chn = 0,9.
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Lc ct ln nht Fm = 1775N = 177,5 kgf
Tc vng ln nht ca ng c 2000 vg/ph Tnh m men ma st :
=....
2... = 0
Tnh tnh m men chng trng lc ca kt cu
=
2 =
155.10.0,12.0,01.90
210,9 = 0,33 Nm
Tnh vn tc di
Vi ng knh trc vt c chn l 40mm, ta c:
=
601000=
402000
601000 = 4,2 (m/s)
Tnh m men my
Mmach =hFm
2i=
0,011775
210,9 = 3,14 Nm
Tnh m men tnh = + + = 0 + 0,33 + 3,14 = 3,47 .
Tnh tc quay ca motor :
=
=
4,2
0,01 = 420 (vg/ph)
Da vo m men tnh ca ng c v tc ca motor, t chn loi ng c AMW 1400C ca hng ANILAM www.anilam.com c momen khi ng l 13 N.m v tc quay ln nht l 2000rpm nh hnh di :
iu kin : nmotor nnoml
Mmotor Mstat
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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4.3.4. Kim tra thi gian cn thit t c vn tc cc i
Thi gian cn thit t c vn tc cc i l :
ta =J
TM TL
2N
60 f
Trong : J l tng m men qun tnh.(Momen tnh ton + momen cho bi ng c Rotor Inertia J )
TM = 2. , ( > 1) ( l m men danh nh -
TL l m men quay
f l h s an ton ( chn theo kiu lp ) Thay s vo ta c :
ta =(133,36 + 43). 104
2.11 44,810.102
2. 2000
60 1,2 = 0,25 < 0,9s
=> Tho mn iu kin
4.3.5. Tnh ton ng sut tc dng ln trc vt
=
=
2
4=
2325 4
35,052= 2,4 (
2) = 2,4 106(
2)
= = 44,8 . = 4480 .
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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=4
32=
35,054
32= 148167 4
=
=
4480 20
148167= 0,6 (
2) = 0,6 106(
2)
= 2 + 22
= 2,47 106(
2)
4.4. Tnh ti trng ti hn ca trc vit
= 2
2=
4
2 103 = 155
35,054
1,352 103 = 128356 > = 177,5 (n v
dr v L tnh theo n v mm ) Do trc vitme m bo an ton.
4.5. Tnh chn cm ln, khp ni
4.5.1. Cm ln
a. Chn ln
Trong c cu bn Z lc dc trc ng vai tr ch yu gy tc ng ln ln, lc hng tm vung gc vi cm trc vitme trong c cu l kh nh, tuy nhin khi hot ng vi vn tc ln d xy ra rung ng, nn yu t nh tm cn c cho c cu.
=> chn chn 1 dy cho trng hp ny
Tnh ton kh nng ti ng:
= . 1
Tnh ton kh nng ti tnh:
0 = 0. 1
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Trong :
m = 3 i vi bi m=10/3 vi a.
L: tui th ca ln c tnh theo cng thc:
= 60. 106. . = 60. 106. 1800.25000 = 2700( )
( y em ly n = Nmax = 1800 vg/ph tnh mc ti a)
Q: ti trng ng ca ln c tnh:
= (. . + . ). .
Q0: ti trng tnh ca ln c tnh:
0 = (0. . + 0. ). .
K = 1,1 (chu va p nh, chu ti ngn hn v ti 125% so vi ti trng tnh ton: my ct kim loi, ng c cng sut nh v trung bnh)
Kt = 1 (nhit
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Kh nng ti ng: Cr = 39 kN
Kh nng ti tnh: Cor = 24,5 kN
Ni lc dc trc Fsi ca 4 l nh nhau:
| Fsi |= Ri = 775 N
Lc dc trc tc dng ln cc bi:
- vi A: = + /2 = 775 + 2004,7/2 = 227,35
suy ra: FaA = 775 N
- vi B: = + /2 = 775 + 2004,7/2 = 1777,35
suy ra: FaB = 1777,35 N
vi C: = + /2 = 775 + 2004,7/2 = 227,35
suy ra: FaC = 775N
- vi D: = + /2 = 775 + 2004,7/2 = 1777,35
suy ra: FaD = 1777,35 N
Fa = max( FaA, FaB, FaC, FaD ) = 1777,35N
Kim tra :
Mt khc :
.
=1777,35
775= 2,3 > 1,14
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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T bng :
Chn : X = 0,35 v Y = 0,57
Tnh ti trng ng:
= (0,35.775 + 0,57.1777,35). 1,1.1 = 1413
Kh nng ti ng:
= 2891.163 270013 = 14952 < = 39
Tnh ti trng tnh:
Xc nh h s X0 , Y0 :
Suy ra: X0 = 0,5 ; Y0 = 0,26
Tnh ti trng tnh:
0 = 0,5.775 + 0,26.1777,35 = 849,6
Kh nng ti tnh:
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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0 = 1438,6 270013 = 11830 < 0 = 24,5
Vy la chn bi ph hp vi kh nng ti
b. Chn gi
Cng nh bn Y, gi bn Z cng l hai gi c nh . V trn c s lc dc trc v ng knh trc vitme bn Z em xin chn series SNL 509. ( y c mt cht tng ng gia vng bi t la v vng bi chn nn gi cng c s tng thch vi vng bi chn nh tnh ton).
4.5.2. Chn khp ni
C rt nhiu loi khp ni ta la chn cho bi ton ny nhng trn c s tham kho ti liu
v thc nghim t cc hng sn xut em xin chn loi khp ni l loi khp ni trc loi trc b ch thp c m .
( tham kho cun Tnh ton thit k h dn ng c kh L Vn Uyn tp 2 trang 55 ).
C th chn thng s cho loi khp ni trc ch thp ny cn c theo ng knh trc vitme v theo gi tr m men khi ng ca ng c. ( xem thm mc thng s ca ng c AM-1400C).
Trn c s em chn thng s cho khp ni nh sau :
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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III. TNH TON RAY DN HNG
Hnh dng ca ray dn hng
c c mt m hnh ph hp nht cho cc iu kin dch chuyn ca h thng ray dn
hng th kh nng chu ti v tui th ca m hnh phi c ch trng nht .
xc nh, kim nghim kh nng ti trng tnh danh ngha, ti trng tng ng th vic
nh gi qua gi tr Co (ti trng ng nh mc) l kh quan v chnh xc hn c.
Tui th c th thu c bng cch tnh ton trn c s l thuyt bng cng thc thc nghim
da trn vic nh gi thng qua ti trng ng danh ngha.
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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1. C s tnh ton
1.1. H s ti tnh C0 Ti trng tnh nh mc C0 c t theo gii hn ti trng tnh cho php.
S bin dng tp trung khng i s tng gia knh dn v bi ln khi ray dn hng nhn ti
trng tha hay chu va p din rng. Nu ln ca bin dng vt qu gii hn cho php, n s
cn tr s di trt ca ray dn hng.
1.2. Momen tnh cho php M0 Mmen tnh cho php M0 c t theo gii hn ca mmen tnh.
Khi 1 mmen tc dng vo ray dn hng, cc v tr bi ln cui cng s chu p lc ln nht gia
cc p lc phn b trn ton b bi ln ca h thng .
1.3. H s an ton tnh sf
Cng thc tnh: 0 0or s sC M
f fP M
Trong :
0C : ti trng tnh nh mc(N)
P : ti trng lm vic tnh ton(N)
0M : momen tnh cho php(Nm)
M : momen tnh ton(Nm)
Cc gi tr tham kho ca sf cho
cc my cng nghip thng thng v
my cng c cho trong bng bn di:
S phn b ti trng
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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1.4. H s ti trng ng nh mc C Thm ch khi cc ray dn hng nh nhau c sn xut theo cng mt cch v chu tc dng
di iu kin nh nhau, tui bn dch v cng khc nhau. Vy nn, tui bn dch v c s dng
nh mt ch tiu xc nh tui bn ca h thng ray dn hng. Ti trng nh mc ng C c s
dng tnh ton tui bn dch v khi h thng ray dn hng chu ti. Ti trng nh mc ng C
c xc nh nh mt ti trng c hng v ln khi nhm cc ray dn hng lm vic cng
iu kin, tui bn trung bnh cu ray dn hng l 50 km( nu b phn ln l bi ).
1.5. Tnh ton tui bn danh ngha L Tui bn danh ngha ca ray dn hng chu nh hng ca ti trng lm vic thc t . Tui bn
danh ngha c th c tnh ton da trn ti trng ng nh mc v
ti trng lm vic thc t .
Tui bn ca h thng ray chu nh hng ln ca h s mi trng nh cng
vng ca ng ray , nhit mi trng , iu kin chuyn ng .V vy,nhng thng
s ny c trong tnh ton tui bn danh ngha .
Cng thc tnh ng vi
Loi xch bi:
3
w
50H Tf f C
Lf P
Loi xch cun:
10
3
w
100H Tf f C
Lf P
Trong
Hf : h s cng vng
Tf : h s nhit
wf : h s ti trn
C : h s ti trng ng (N)
P : ti trng lm vic (N)
m bo kh nng ti ti u ca h thng ray, cng vng ca ng ray phi trong
khong HRC58-64. Nu cng di khong ni trn, ti cho php v tui bn danh ngha s gim.
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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V l do ny, ti trng ng nh mc v ti trng tnh nh mc s c nhn vi h s cng vng
trong tnh ton. Bng di y l th cng vng m bo HRC ln hn 58, do 1.0Hf
Vi h s nhit Tf : Khi nhit iu khin ln hn 100 C, tui bn danh ngha s
gim bt. Do ti trng ng v tnh nh mc s c nhn vi h s nhit trong
tnh ton. Xem hnh bn di. Nhiu phn ca ray c lm t nha v cao su, nn nhit
phi di 100 C l tt nht. Cc yu cu c bit phi lin h vi nh sn xut .
H s ti trng wf : Mc d ti trng lm vic ca ray c xt trong tnh ton, nhng ti
trng thc t hu ht u cao hn khi tnh ton. l do rung ng v va p khi my chuyn ng.
Rung ng xy ra khi iu khin tc cao, va p xy ra khi my khi ng li v dng my.
Do , xt n tc chuyn ng v rung ng, ti trng ng nh mc phi c chia cho h
s ti trng theo bng bn cnh
1.6. Tnh ton tui bn dch v theo thi gian. Khi tui bn danh ngha c xt n , tui b dch v c tnh ton theo nhng thng s c
c khi chiu di hnh trnh v vng quay l khng i.
3
1
10
2 60h
s
LL
l n
Trong :
L : tui bn danh ngha
sl : chiu di hnh trnh
1n : tc vng (min-1)
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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1.7. H s ma st Ray dn hng c iu khin nh chuyn ng ca nhng vin bi ln gia ray v phn di
trt. Lc cn ma st c tnh ton
da trn ti trng lm vic v lc cn
cht. Ni chung, h s ma st s khc
nhau gia cc s ri khc nhau. H s ma
st ca sri MSA v MSB trong khong
0.002 ti 0.003.
F P f
Trong
- : h s ma st ng
P : ti trng lm vic
f : sc chu vng m
1.8. Tnh ton ti trng lm vic Mt s v d v cng thc tnh ti trng lm vic c cho trong bng sau:
iu kin
lm vic S lc Cng thc tnh
H bn my
nm ngang,
chuyn ng
u hoc
khng ti
3 41
1 2
3 42
1 2
3 43
1 2
3 44
1 2
4 2 2
4 2 2
4 2 2
4 2 2
Fl FlFP
l l
Fl FlFP
l l
Fl FlFP
l l
Fl FlFP
l l
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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H bn my
nm ngang nh
ra ngoi, chuyn
ng u hoc
khng ti
3 41
1 2
3 42
1 2
3 43
1 2
3 44
1 2
4 2 2
4 2 2
4 2 2
4 2 2
Fl FlFP
l l
Fl FlFP
l l
Fl FlFP
l l
Fl FlFP
l l
H bn my
thng ng,
chuyn ng
u hoc khng
ti
31 2 3 4
1
41 2 3 4
1
2
2T T T T
FlP P P P
l
FlP P P P
l
H bn my
ng, di chuyn
ngang chuyn
ng u hoc
khng ti
41 2 3 4
2
31 2
1
33 4
1
2
4 2
4 2
T T
T T
FlP P P P
l
FlFP P
l
FlFP P
l
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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H bn my
ngang, c t
phi
Tng tc:
1 31 4
1
1 32 3
1
1 41 2 3 4
1
4 2
4 2
2T T T T
ma lmgP P
l
ma lmgP P
l
ma lP P P P
l
Chy u:
1 2 3 44
T T T T
mgP P P P
Gim tc:
3 31 4
1
3 32 3
1
3 41 2 3 4
1
4 2
4 2
2T T T T
ma lmgP P
l
ma lmgP P
l
ma lP P P P
l
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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H bn my
ng, c t
phi
Tng tc:
3
1 4 2 3
1
1 4
1 2 3 4
1
2
2T T T T
m g a lP P P P
l
m g a lP P P P
l
Chy u:
31 4 2 3
1
41 2 3 4
1
2
2T T T T
mglP P P P
l
mglP P P P
l
Gim tc:
3
1 4 2 3
1
1 4
1 2 3 4
1
2
2T T T T
m g a lP P P P
l
m g a lP P P P
l
1.9. Tnh ton ti trng tng ng H thng ray dn hng c th chu ti v m men theo c 4 hng ca ti trng hng tm, ti
trng o chiu hng tm, ti trng mt bn ng thi. Khi hn mt ti trng tc dng ln h
thng ray ng thi, mi ti trng khc s hng vo tm hoc mt bn tng ng, cho vic tnh
ton tui bn dch v v h s an ton tnh. Cng thc tnh ton c ch ra di y :
E R TP P P
Trong :
EP : ti trng tng ng
RP : ti trng hng tm tc dng mt trn
TP : ti trng tc dng ln mt bn
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Momen tc dng c tnh theo cng thc:
0E R T
R
MP P P C
M
Trong :
0C : ti trng tnh nh mc
M : momen tnh ton
RM : momen tnh cho php2.1.10. Tnh ton ti trng trung bnh
Cng thc tnh ti trng trung bnh:
331
1.
n
m n n
n
P P LL
Trong :
nP : ti trng bin thin
nL : khong dch chuyn di tc
dng ca nP
L : tng chiu di dch chuyn
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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Quy trnh tnh ton ray dn hng
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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S t lc v ch chuyn ng bn Y
S t lc v ch chuyn ng bn Z
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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2. Tnh ton ray dn hng bn Y
La chn kch c ray dn hng nn ging nh vi ng knh vitme bi : + Chiu cao cm ray dn v ng knh ca vit me tng i nhau
+ c bit l cc h s ti trng ng, h s ti trng tnh ph hp vi tnh ton trong phn tnh ton ti trng chn trc vit me.
y la chn loi MSA LA v s n gin trong s lp ghp, s thng dng trn th trng, cng vng m bo tin cy v mt phn bi gi ca n cng khng qu cao.
Mt s thng tin cho MSA LA Type : MSA c cc dy bng c thit k gc tip xc l 45 , cho php n chu mt ti trng dng trn, hay o ngc hng xuyn tm hay hng bn. Do , n c th c p dng trong bt k hng no ci t. Hn na MSA c th t c cn bng ti trc tn cng trong 4 chiu trong khi vn gia kh nng gim ma st n mc thp. Loi ny c bit ph hp vi chnh xc cao v cng cao trong khi hot ng. Thit k tuyn du bi trn lm cho cht bi trn phn b u trong vng tun hon. Do , bi trn ti u c th t c trong bt k hng ci t no v iu ny thc y vic thc hin trong hot ng mt cch chnh xc, ti u tui th v tin cy cao.
+ S dng ray dn hng c series: MSA35LA2SSF0 + R100020/20 P II c :
H s ti ng: C = 63,6 kN.
H s ti tnh: C0 = 100,6 kN.
V cc thng s khc nh hnh di:
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
54
NGUYN VN THUN MSSV : 20110841
+ Cc thng s u vo:
Khi lng phi: m1 = 400 kg. Khi lng cm bn Y: m2 = 230 kg. Vn tc chy ln nht khi khng gia cng: v = 18 m/ph = 0,3 m/s. Gia tc: a = a1 = a3 = 5 m/s2 Hnh trnh dch chuyn : LS = Ly = 1000mm Cc giai on:
t1 = t3 = v
a = 0,06s X1 = X3 =
v2
2a =
0.32
2.5.103 = 9mm.
X2 = Ly 2X1 = 1000 9.2 = 982mm t2 = X2
v =
982.103
0.3 = 3,3s
Cc on di chuyn: ( Coi phi t chnh gia bn my, tm phi trng vi tm bn my)
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
55
NGUYN VN THUN MSSV : 20110841
Khong cch gia hai con chy cng ray: l1 = 350mm. Khong cch gia hai con chy khc ray: l2 = 300mm. Khong cch t tm phi ti tm bn my theo phng vung gc
vi ray dn: l3 = 0. Khong cch t tm phi ti tm bn my theo phng song song
vi ray dn: l4 = 0. cao t tm trc vt-me ti mt bn my: l5 = 150mm. cao t tm trc vt-me ti phi: l6 = 300mm.
2.1. Tnh ton cc lc ring r
2.1.1. Chuyn ng u, lc hng knh Pn
P1 = m1g
4
m1gl3
2l1+
m1gl4
2l2+
m2g
4 = 1575 N
P2 = m1g
4+
m1gl3
2l1+
m1gl4
2l2+
m2g
4 = 1575 N
P3 = m1g
4+
m1gl3
2l1
m1gl4
2l2+
m2g
4 = 1575 N
P4 = m1g
4
m1gl3
2l1
m1gl4
2l2+
m2g
4 = 1575 N
2.1.2. Chuyn ng tng tc sang tri, lc Pnla1
P1la1 = P1 m1a1l6
2l1
m2a1l5
2l1 = 471,4 N
P2la1 = P2 + m1a1l6
2l1+
m2a1l5
2l1 = 2678,6 N
P3la1 = P3 + m1a1l6
2l1+
m2a1l5
2l1 = 2678,6 N
P4la1 = P4 m1a1l6
2l1
m2a1l5
2l1 = 471,4 N
Ti ph Ptnla1:
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
Pt1la1 = m1a1l4
2l1 = 0
Pt2la1 = m1a1l4
2l1 = 0
Pt3la1 = m1a1l4
2l1 = 0
Pt4la1 = m1a1l4
2l1 = 0
2.1.3. Chuyn ng gim tc sang tri Pnla3
P1la3 = P1 + m1a3l6
2l1+
m2a3l5
2l1 = 2678,6 N
P2la3 = P2 m1a3l6
2l1
m2a3l5
2l1 = 471,4N
P3la3 = P3 m1a3l6
2l1
m2a3l5
2l1 = 471,4 N
P4la3 = P4 + m1a3l6
2l1+
m2a3l5
2l1 = 2678,6 N
Ti ph Ptnla3:
Pt1la3 = m1a3l4
2l1 = 0
Pt2la3 = m1a3l4
2l1 = 0
Pt3la3 = m1a3l4
2l1 = 0
Pt4la3 = m1a3l4
2l1 = 0
2.1.4. Chuyn ng tng tc sang phi, lc Pnra1
P1ra1 = P1 + m1a1l6
2l1+
m2a1l5
2l1 = 2678,6 N
P2ra1 = P2 m1a1l6
2l1
m2a1l5
2l1 = 471,4 N
P3ra1 = P3 m1a1l6
2l1
m2a1l5
2l1 = 471,4 N
P4ra1 = P4 + m1a1l6
2l1+
m2a1l5
2l1 = 2678,6 N
Ti ph Ptnra1:
Pt1ra1 = m1a1l4
2l1 = 0
Pt2ra1 = m1a1l4
2l1 = 0
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
57
NGUYN VN THUN MSSV : 20110841
Pt3ra1 = m1a1l4
2l1 = 0
Pt4ra1 = m1a1l4
2l1 = 0
2.1.5. Chuyn ng gim tc sang phi Pnra3
P1ra3 = P1 m1a3l6
2l1
m2a3l5
2l1 = 471,4 N
P2ra3 = P2 + m1a3l6
2l1+
m2a3l5
2l1 = 2678,6 N
P3ra3 = P3 +m1a3l6
2l1+
m2a3l5
2l1 = 2678,6 N
P4ra3 = P4 m1a3l6
2l1
m2a3l5
2l1 = 471,4 N
Ti ph Ptnra3:
Pt1ra3 = m1a3l4
2l1 = 0
Pt2ra3 = m1a3l4
2l1 = 0
Pt3ra3 = m1a3l4
2l1 = 0
Pt4ra3 = m1a3l4
2l1 = 0
2.2. Tnh ton ti tng ng
2.2.1. Khi chuyn ng u
PE1 = P1 = 1575N
PE2 = P2 = 1575 N
PE3 = P3 = 1575 N
PE4 = P4 = 1575 N
2.2.2. Khi tng tc sang tri
PE1la1 =|P1la1| + |Pt1la1| = 471,4N
PE2la1 =|P2la1| + |Pt2la1| = 2678,6 N
PE3la1 =|P3la1| + |Pt3la1| = 2678,6 N
PE4la1 =|P4la1| + |Pt4la1| = 471,4 N
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
2.2.3. Khi gim tc sang tri
PE1la3 =|P1la3| + |Pt1la3| = 2678,6 N
PE2la3 =|P2la3| + |Pt2la3| = 471,4 N
PE3la3 =|P3la3| + |Pt3la3| = 471,4 N
PE4la3 =|P4la3| + |Pt4la3| = 2678,6 N
2.2.4. Khi tng tc sang phi
PE1ra1 =|P1la1| + |Pt1la1| = 2678,6 N
PE2ra1 =|P2la1| + |Pt2la1| = 471,4 N
PE3ra1 =|P3la1| + |Pt3la1| = 471,4 N
PE4ra1 =|P4la1| + |Pt4la1| = 2678,6 N
2.2.5. Khi gim tc sang phi
PE1ra3 =|P1la3| + |Pt1la3| = 2678,6 N
PE2ra3 =|P2la3| + |Pt2la3| = 471,4 N
PE3ra3 =|P3la3| + |Pt3la3| = 471,4 N
PE4ra3 =|P4la3| + |Pt4la3| = 2678,6 N
2.3. Tnh ton h s tnh
fs = C0
PE2la1 =
100,6.103
2678,6 = 37.6
iu kin an ton
2.4. Tnh ton ti trung bnh Pmn
Pm1 = PE1la1
3X1+ PE13 X2+ PE1la3
3X3+PE1ra13X1+PE1
3 X2+ PE1ra33X3
2ls
3 = 1600,1 N
Pm2 = PE2la1
3X1+ PE23 X2+ PE2la3
3X3+PE2ra13X1+PE2
3 X2+ PE2ra33X3
2ls
3 = 1600,1 N
Pm3 = PE3la1
3X1+ PE33 X2+ PE3la3
3X3+PE3ra13X1+PE3
3 X2+ PE3ra33X3
2ls
3
= 1600,1 N
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
Pm4 = PE4la1
3X1+ PE43 X2+ PE4la3
3X3+PE4ra13X1+PE4
3 X2+ PE4ra33X3
2ls
3
= 1600,1 N
2.5. Tnh ton tui th danh ngha Ln Ly h s ti trng fw = 1.5
L1 = (C
fw .Pm1)
3 .50 = 930307 km
L2 = (C
fw .Pm2)
3 . 50 = 930307 km
L3 = (C
fw .Pm3)
3 . 50 = 930307 km
L4 = (C
fw .Pm4)
3 .50 = 930307 km
3. Tnh ton ray dn hng bn Z
Tng t nh vi tnh ton ca bn Y ch c iu khc l phn tnh ton bn Z s c mt s cng thc khc vi bn Y v chuyn ng ca bn Z l chuyn ng thng ng (gm ln v xung ).
+ S dng ray dn hng c series: MSA25LA2SSF0 + R100020/20 P II c :
H s ti ng: C = 34,4 kN.
H s ti tnh: C0 = 56,6 kN.
V cc thng s khc nh hnh di:
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
60
NGUYN VN THUN MSSV : 20110841
+ Cc thng s u vo:
Khi lng phi trn bn Z: m1 = 0 kg. Khi lng cm bn Z : m = 155 kg. Vn tc chy ln nht khi khng gia cng: v = 18 m/ph = 0,3 m/s. Gia tc: a = a1 = a3 = 5 m/s2 Hnh trnh dch chuyn : LS = Lz = 1000mm Cc giai on:
t1 = t3 = v
a = 0,06s X1 = X3 =
v2
2a =
0.32
2.5.103 = 9mm.
X2 = Ly 2X1 = 1000 9.2 = 982mm t2 = X2v
= 982.103
0.3 = 3,3s
Cc on di chuyn: ( Coi cm bn my Z lm ti trng chnh, tm l tm bn my)
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
61
NGUYN VN THUN MSSV : 20110841
Khong cch gia hai con chy cng ray: l1 = 350mm. Khong cch gia hai con chy khc ray: l2 = 300mm. Khong cch t tm cm bn my ti tm vitme theo phng vung
gc vi ray dn: l3 = 100mm. Khong cch t tm phi ti tm bn my theo phng song song
vi ray dn: l4 = 0.
3.1. Tnh ton cc lc ring r
3.1.1. Chuyn ng u, lc hng knh Pn
P1 = P2 = P3 = P4 =mgl3
2l1= 221,4
3.1.2. Chuyn ng tng tc i xung , lc Pnda1
P1da1 = P1 + m1a1l3
2l1 = 332,1 N
P2da1 = P2 m1a1l3
2l1 = 110,7 N
P3da1 = P3 m1a1l3
2l1 = 110,7 N
P4da1 = P4 + m1a1l3
2l1 = 332,1 N
Ti ph Ptnda1:
Pt1da1 = m1a1l4
2l1 = 0
Pt2da1 = m1a1l4
2l1 = 0
Pt3da1 = m1a1l4
2l1 = 0
Pt4da1 = m1a1l4
2l1 = 0
3.1.3. Chuyn ng gim tc i xung Pnda3
P1da3 = P1 m1a3l3
2l1 = 110,7 N
P2da3 = P2 + m1a3l3
2l1 = 332,1
P3da3 = P3 + m1a3l3
2l1 = 332,1 N
P4da3 = P4 m1a3l3
2l1 = 110,7 N
Ti ph Ptnda3:
Pt1da3 = m1a3l4
2l1 = 0
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
Pt2da3 = m1a3l4
2l1 = 0
Pt3da3 = m1a3l4
2l1 = 0
Pt4da3 = m1a3l4
2l1 = 0
3.1.4. Chuyn ng gim tc i ln, lc Pnua3
P1ua3 = P1 + m1a3l3
2l1 = 332,1 N
P2ua3 = P2 m1a3l3
2l1 = 110,7 N
P3ua3 = P3 m1a3l3
2l1 = 110,7 N
P4ua3 = P4 + m1a3l3
2l1 = 332,1 N
Ti ph Ptnua3:
Pt1ua3 = m1a3l4
2l1 = 0
Pt2ua3 = m1a3l4
2l1 = 0
Pt3ua3 = m1a3l4
2l1 = 0
Pt4ua3 = m1a3l4
2l1 = 0
3.1.5. Chuyn ng tng tc i ln Pnua1
P1ua1 = P1 m1a1l3
2l1 = 110,7 N
P2ua1 = P2 + m1a1l3
2l1 = 332,1 N
P3ua1 = P3 +m1a1l3
2l1 = 332,1 N
P4ua1 = P4 m1a1l3
2l1 = 110,7 N
Ti ph Ptnua1:
Pt1ua1 = m1a1l4
2l1 = 0
Pt2ua1 = m1a1l4
2l1 = 0
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
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NGUYN VN THUN MSSV : 20110841
Pt3ua1 = m1a1l4
2l1 = 0
Pt4ua1 = m1a1l4
2l1 = 0
3.2. Tnh ton ti tng ng
3.2.1. Khi chuyn ng u
PE1 = P1 = 221,4N
PE2 = P2 = 221,4 N
PE3 = P3 = 221,4 N
PE4 = P4 = 221,4 N
3.2.2. Khi tng tc i xung
PE1da1 =|P1a1| + |Pt1da1| = 332,1N
PE2da1 =|P2da1| + |Pt2da1| = 110,7 N
PE3da1 =|P3da1| + |Pt3da1| = 110,7 N
PE4da1 =|P4da1| + |Pt4da1| = 332,1 N
3.2.3. Khi gim tc i xung
PE1da3 =|P1da3| + |Pt1da3| = 110,7 N
PE2da3 =|P2da3| + |Pt2da3| = 332,1 N
PE3la3 =|P3da3| + |Pt3da3| = 332,1 N
PE4da3 =|P4da3| + |Pt4da3| = 110,7 N
3.2.4. Khi tng tc i ln
PE1ua1 =|P1ua1| + |Pt1ua1| = 110,7 N
PE2ua1 =|P2ua1| + |Pt2ua1| = 332,1 N
PE3ua1 =|P3ua1| + |Pt3ua1| = 332,1 N
PE4ua1 =|P4ua1| + |Pt4ua1| = 110,7 N
3.2.5. Khi gim tc i ln
PE1ua3 =|P1ua3| + |Pt1ua3| = 332,1 N
PE2ra3 =|P2ua3| + |Pt2ua3| = 110,7 N
PE3ra3 =|P3ua3| + |Pt3ua3| = 110,7 N
PE4ra3 =|P4ua3| + |Pt4ua3| = 332,1 N
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
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NGUYN VN THUN MSSV : 20110841
3.3. Tnh ton h s tnh
fs = C0
PE1da1=
56,6.103
332,1 = 170
iu kin an ton
3.4. Tnh ton ti trung bnh Pmn
Pm1 = PE1da1
3X1+ PE13 X2+ PE1da3
3X3+PE1ua13X1+PE1
3 X2+ PE1ua33X3
2ls
3 = 222,4 N
Pm2 = PE2da1
3X1+ PE23 X2+ PE2da3
3X3+PE2ua13X1+PE2
3 X2+ PE2ua33X3
2ls
3 = 222,4 N
Pm3 = PE3da1
3X1+ PE33 X2+ PE3da3
3X3+PE3ua13X1+PE3
3 X2+ PE3ua33X3
2ls
3 = 222,4 N
Pm4 = PE4da1
3X1+ PE43 X2+ PE4da3
3X3+PE4ua13X1+PE4
3 X2+ PE4ua33X3
2ls
3 = 222,4 N
3.5. Tnh ton tui th danh ngha Ln
Ly h s ti trng fw = 1.5
L1 = (C
fw .Pm1)
3 .50 = 54823557 km
L2 = (C
fw .Pm2)
3 . 50 = 54823557 km
L3 = (C
fw .Pm3)
3 . 50 = 54823557 km
L4 = (C
fw .Pm4)
3 .50 = 54823557 km
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
65
NGUYN VN THUN MSSV : 20110841
Kt lun
Bi ton : Tnh ton thit k h thng dn hng dng cho my phay CNC 3 trc.
Da vo bi ton ta tnh chn c cc chi tit ,b phn dng trong cc my CNC.
1. Vt me bi trc chnh Y v Z vi chiu di lm vic cho trc ta xc nh c ng knh cho php ph hp vi vn tc yu cu ca my v h s ti trng ng di yu cu ca ti trng cho php.
2. xc nh c loi cn thit cho 2 trc vi h s ti trng tnh ton c.
3. ng c c cng sut v momen xon momen khi ng ph hp vi qu trnh tng tc, gim tc v giai on lm vic ca my.
4. Chn c ray dn hng
Cc thng s tnh chn c :
STT Tn gi Thng s Ghi ch 1 Vt me bi trc Y 40-10B2-FDWC Hng PMI 2 Vt me bi trc Z 45-10B3-FDWC Hng PMI 3 bi 1 dy trc Y 7406B Hng SKF 4 bi 1 dy trc Z 7407B Hng SKF 5 ng c trc Y AM 1400C Hng
Anilam 6 ng c trc Z AM 1400C Hng
Anilam 7 Ray dn trc Y MSA 25LA Hng PMI 8 Ray dn trc Z MSA 35LA Hng PMI
TRNG H BCH KHOA H NI n mn hc : Thit k h thng c kh
ti : Tnh ton thit k h thng truyn ng v la chn h thng dn hng dng cho my phay CNC
GVHD : TS. Nguyn Tin ng
66
NGUYN VN THUN MSSV : 20110841
Ti liu tham kho
1. PMI ballscrews catalog, Precision motion industries, INC
2. PMI linear guideway, Precision motion industries, INC
3. Ballscrews technical information, Hiwin motion control and system technology
4. Linear guideway technical information, Hiwin motion control and system technology
5. Machine tools for high performance machining, L.N.Lpez de Lacalle, A.Lamikiz
6. Website ca cc hng : www.pmi-amt.com, www.Hiwin.com, www.skf.com,
www.alibaba.com, www.anilam.com, ..
7. Tnh ton thit k h dn ng c kh (tp 1, tp 2) - Trnh Cht L Vn Uyn NXB Gio
dc.
9. S tay Cng ngh ch to my - tp 1,2,3 - GS N Nguyn c Lc - XB Khoa hc v K thut.
10. Gio trnh dung sai lp ghp v k thut o lng - Pgs.Ts.Ninh c Tn