THUT TON MT PHNG QUT ( SWEEP PLANE) TRONG NHN DNG VA CHAM VI PHI
TRN MY CNC 5 TRC
1. GII THIU CHUNG V THUT TON Do
kh nng gia cng hiu qu cc chi tit c hnh dng phc tp v t chnh xc
cao v kch thc, cc my CNC 5 trc ngy cng ph bin trong lnh vc gia cng.
So vi cc my 3 trc, my CNC 5 trc c thm hai trc quay, v vy gia cng
trn my 5 trc c rt nhiu u im so vi gia cng trn cc my 3 trc truyn
thng, v d nh gia cng c cc b mt phc tp, nng sut ct cao hn, gim thi
gian gia cng v nng cao cht lng b mt gia cng
Tuy
nhin do c thm hai bc t do, nn va chm rt d xy ra trong qu trnh
gia cng trn my CNC 5 trc. Vic xc nh cc va chm trong qu trnh gia cng
trn my CNC 5 trc c ngha thc tin ln, nhm trnh cc tai nn ng tic (nh
gy dao, hng phi, hng hc cc b phn my, v.v...) c th xy ra trong qu
trnh gia cng.
C th nhn thy 2 loi va chm: Va
chm cc b: gia dao c v phi Va chm ton cc: Gia giao c ( hoc cn
dao) v phi ( hoc cc thnh phn ca my) Gia phi v cc thnh phn ca my Gia
cc b phn khc ca my vi nhau
C
nhiu phng php nhn dng va chm, tuy nhin hu ht trong s chng ch gii
quyt vn va chm phn cui cng ca thnh phm, m s thay i ca bin dng phi
trong sut qu trnh gia cng li khng c cp n.
Nh vy, trong bi bo ny pht trin mt phng php nhn dng va chm mi trn
my CNC 5 trc m s thay i bin dng ca phi, tng ng vi phn vt liu b ct b
i, s c cp n. C 2 bc cn bn: Bc
th nht: Bin dng ngoi ca my v phi s c xp x bi cc hnh cu ( dng hnh
cy). Tin hnh kim tra va chm bng cch kim tra xem c nhng hnh cu no
giao nhau. Nu c, chuyn sang bc th 2
Bc th nht
Bc
th hai: nhng hnh cu c s giao thoa, nhn dng va chm s c tin hnh
bng vic s dng thut ton mt phng qut (swep plane) Chng sau s c phn nh
bi cc mt phng song song vi nhau. Tip sau, s xc nh c cc a gic, l ghp
bi cc ng giao nhau gia cc mt phng song song ny vi dao c v phi. Vic
nhn dng va chm sau l vic kim tra giao gia nhng ng a gic. Nu c vi
giao im gia nhng a gic ny, s va chm thc s s xy ra.
Thut ton
M hnh y ton b my
Gi lp ct b vt liu
Cp nht bin dng
M hnh i tng khng gian
Nhn dng va chm cc b
Nhn dng va chm ton cc
Nhng phn ca my c th nhn dng
Xc nh hng quay ca dao c
No
No
No
Yes
Yes
Yes
Tool & workpiece
Phn tch bin dng
No
No
No
Yes
Yes
No
Tool & workpiece
Ranh gii th tch
No
No
No
Yes
Yes
Yes
Tool & workpiece
Mt phng qut (sweep plane)
Yes
Yes
Yes
Yes
Yes
Yes
Tool & workpiece
Cc kiu va chmX-Axis Y -axis Z -axis A -axis B -axis Phi g Dao
c
X-Axis Y -axisZ -axis A -axis B -axis x x x x x x x x x
Phi g Cng c
xx x
xx x x
Tham chiu v tr v hng ct trn my CNC 5 trc.
Tng quan v thut ton Trc
tin, tt c nhng thnh phn ca my c ct ra thnh nhng mt phng song
song nm ngang, m da theo v tr ca chng so vi thn my Phi c ct theo cc
mt phng song song thng ng Sau , mi thnh phn ny li c xp x bi cc hnh
cu ( dng cy )
tnh ton bin dng ngoi ca phi, mt file M-plane c tnh ton da trn v
tr ca dao ct. File M-plane cha ng tt c cc thng tin cn thit v giao
ca nhng mt phng song song (sweep plane) vi cong c ct. Vi mi bc
chuyn ng ca v tr dao ct, giao thoa ca cc mt ct ca cng c vi cc mt ct
ca phi s li c tnh ton. Tt c nhng mt ct ca nhng phn chuyn ng u song
song vi cc phn khc v thut ton kim tra giao thoa cc mt song song c
thc hin da vo phng php Polygon Clipper.
Thut ton mt phng qut Sweep plane Thut
ton ny m rng cho nhn dng va chm gia cc thnh phn nh dao c, phi,
khung my, cc phn chuyn ng trn my CNC 5 trc. Thut ton ny ch cho thc
hin kim tra trn mt phi trng. Thut ton c hiu l cc i tng 3D c ct bi
cc mt phng song song nhau, gi l Sweep plane, trong cha ng nhng ng
giao ( cc lt ct ) 2D. Trong mi mt phng qut, nu c 2 hoc nhiu hn cc
lt ct chng cho ln nhau, s c 2 hoc nhiu va chm khc nhau xy ra.
NI SUY CHUYN NG QUT GIA 2 BLOCK G-CODELIN TIP
1. Trong chng trnh NC, tnh ton khong cch gia 2 block lin tip: X,
Y, Z, A, B, 2. Tnh ton s lng bc ni suy (ny) theo trc Y. Gi tr ny
phi tng xng vi khong cch ca cc lt ct, v vy m:
3. Tnh ton s lng bc ni suy trc x , n c lin quan ti c trc Y do
:
4. Tnh ton s bc ni suy trn trc B. Trc B l trc quay v n b di
chuyn bi trc Y v trc X. Trong mi bc dch chuyn, trc B quay mt
lng
5. Tnh ton cho trc A
6. Tnh ton cho trc z
7. Tnh ton s bc ni suy ti a cho tt c cc trc 8. Tnh ton gi tr ni
suy ca cc trc da trn s bc ni suy:
kim tra giao gia nhng mt song song, ta dng thut ton a gic ct.
kim tra giao gia nhng mt khng song song
Khi trc A quay, cc lt ct ca phi, g v trc A khng song song vi mt
ct tham chiu.
S giao trong trng hp ny c kim tra bi vic chiu mt ct ln 3 mt phng
,
