SClENCETECHNOLOGYl
S-i- l ^ . - f J -
^ - 9XAC D!NH MOI QUAN HE GIUfA GOC SAU CHfNH VA GOC SAU PHU VCFI N A N G SUAT CAT KHI TIEN
EXAMINING THE RELATIONSHIP BETWEEN MAIN CLEARANCE ANGLE AND AUXILIARY CLEARANCE ANGLE ANDTHE CUTTING EFFICIENCYWHEN PROCESSING
Pham Van Bong
Tom tSt
Dung cu cat kim loai dong vai tro vo ciing quan trpng trong linh vircgia cong cd khi. Cac thong so hlnh hoc cua dung cu cat (cac goc) co anh hu'dng ldn den tinh chat c3t gpt, kha nang boc tach vat lieu ra khm chi ti^t gia c6ng, co nghia la Inh hudng ldn den nang suat ck. Bai bao de cap den viec nghien cdu mm quan h@ giSa goc sau chinh v^ goc sau phu cua dao den nang suit cat khi gia cdng vat lieu tren may tien CNC Til khoa: Nang suat c i t thi/c, chieu sau cAt thuc, moi quan he, gdc sau chinh, gdc sau phu.
Abstract
Metal cutting tools place a great role in the field of machinery processing. Geological parameters of cutting tools (angles) can greatly affect the cutting quality and ability of removing material ^ m the workpiece. In other words, such geological parameters have enormous effects on cutting efficiency. The artide refers to the study ofthe relationship betv/een main dearance angle and auxiliary dearance angle and the cutting efliciency when processing on CNC lathes.
Keywords: real cut efliciency, real depth of cut, relationship, main clearance angle, auxiliary clearance angle.
TS. Pham Van Bdng TnfcFng &ai hoc Cong nghiep Ha Noi Email: [email protected]
I.DATVAND€
Trong q u i trinh c i t phat sinh c i c lue nhU: lUc cat ehinh P^, lUc hudng true P^ luc hudng kinh P^. Khi lUe P^ P,, P^
Idn se t i e dpng vao dao gay udn dao, uon chi tiet gia cdng tren mat phang n i m ngang hoac mat phang diing.
Bleu dd lam cho vj tri mui dao bj thay doi, tUe la k h o i n g cich t U t i m chi tiet den mui dao thay doi, nang suat eat gpt sebi i n h hudng.
Qua cac nghien cUu cho thiy, gdc sau chinh (a) va gdc sau phy (a,) cd anh
Ngaynhanbai: 17/01/2014 Ngaydiap nhan dang: 16/05/2014
hudng Idn den n i n g suat cat, nhung i n h hudng nhu the nao thi chua cd nghien cUu nao cdng bd cu the m i ehi de cap mdt each chung chung. De lam rd van de nay can p h i i nghien eUu, thuc nghiem tim ra mdi quan he giUa gdc sau ehinh va gdc sau phu ciia dao den n i n g suat cat.
2. NGHIDN CQU M 6 | QUAN H £ GlffA G 6 C S A U C H I ' N H V A G 6 C SAU PHU DEN N A N G S U A T C A T
2.1. Nang suat c^t
Nang suat c i t gpt Q la the tich kim
loai bj bdc di trong mdt dan vi thdi gian (mmVph). Vdi phuong p h i p tien thi nang suit cat gpt duoc xae dinh b i n g edng thUc:
Q = A.v = s.t.v(mmVph)[1] (1) Trong do:
A-s.t la dien tich tiet dien Ic^ cit (mm') v: la van tdc cat (m/ph) s: la lupng chay dao (mm/vdng) t: la chieu sau e l t (mm) Chieu sau cat dupc xac djnh theo ly thuyet.Tuynhien khi eit thuc, chieu sau c i t theo 1^ thuyet cd the khdng chinh xae do nhieu nguyen n h i n t i c ddng trong dd ed suanh hudng ciia gdc dao, ciia dp cUng vat lieu gia cong... Vi vay, nang suat cat thUc Q^^ cd the xac djnh nhUsau:
Qt. = v.s,t„ (2) Trong dd, chieu sau eat thuc t,^ dupc
xac dinh b i n g edng thUe:
t,, = t.At (3) At la he sd xet den sU i n h hudng
ciia gde sau ehinh v i gde sau phu ciia dao den ehieu sau cat thuc.
Ta da biet, neu bd qua anh hudng ciia eic yeu to khac, thi chieu s i u c i t thuc t^ phu thupe vao lue eat. B i e biet khi gia cdng vat lieu eUng, do lUc cat P^
P^ P^, Idn nen da t i c ddng vao dao mpt lUc ldn hon khi gia cdng vat lieu thdng thudng [3]. Bieu do cd the g i y ra c i c van de sau:
- Luc Pj Idn cd the gay udn dao tren
So22.2014•TapchiKHOAHOC&CONGNGHE 7
ia!r«TJ!rtHc6NG NGHE
mat phing ngang. Ket q u i dd l i m eho khoing each tU tam v i t gia cong den mui dao thay ddi. Co nghia la ehieu siu eat thUe da bi thay doi so vdi tien vat lieu thdng thudng.
' Luc P Idn cd xu hudng day dao ra xa v i t gia cong (dao bj djch chuyen hoac vat gia cong bi udn ngang). Cung CO nghTa l i chieu s i u c i t thue da thay ddi.
- Luc P^ ldn g i y uon dao tren mat phang dUng l i m cho khoing cich tU t i m vat gia cdng den mui dao thay doi. Cd nghTa la ehieu sau eat thue da bj thay ddi so vdi tien vat lieu thdng thudng.
Theo cae nghidn eUu duoe trinh bay trong g i i o trinh nguyen ly gia cdng vat lieu [3] thi cic thanh phan lUc c i t phu thudc vao nhieu y^u td nhung trong dd sU i n h hudng eua gde sau chinh a va gdc sau phu a, la rat Idn. Bleu do cung ed nghia la:
Q,^ = f(v,s,t,a,a,) (4) Trong pham vi nghien cUu eua bai b i o chi tap trung l i m rd su i n h hudng ciia gde sau ehinh va gdc sau phu den nang suat c i t thUe Q^ thdng qua viec xac dinh sU thay ddi ciia chieu siu e i t thue nen ta col van tdc eat va lUpng tien dao l i h i n g sd. Nhu vay de xic dinh nang suat c i t thUe eo xet den anh hudng ciia gdc sau chi'nh v i gdc sau phu ciia dao ehi ein xac djnh At.
Mdi quan he giUa hesdeatthUcvdi gdc sau chinh v i gdc sau phu l i :
At = f(a,a,) (5) Gii thiet mdi quan he do l i mdt
ham phi tuyen cd dang:
At-C.a''.a,*^ (6) Be xac djnh mdi quan he theo
phuong trinh (6) ta thue hien thi nghiem eit vdi cic gdc ciia dao khac nhau. Vdi moi thi nghiem sau khi cit, do dudng kinh chi tiet gia cdng ta se xac dinh dupc g i i tri t,^ eiJa thi nghiem dd. Sau khi cd ket q u i thi nghiem. tien h i n h xU ly sd lieu de tim phuong trinh bieu dien mdi quan he giUa At vdi cae
gdc sau chinh va gde sau phu ciia dao. Bang I.Cacgiatrithilcnghiem tU do cd the tinh dupc n i n g suit cat
thue khi tien vat lieu cUng tren m i y tien ed xet den sU anh hUdng ciia gdc sau chinh va goc sau phu ciia dao.
2.2. He thong thUc nghiem
• Mo hinh tbinghiim (hinh 1):
Bang 2. Quy hoach thi/c nghiem khi tinh chieu sau c3t thilc Cac yeu t 5 Mile tren Hilifcdudi Mciasis Khoang bi^n thien
Xi=ln(a) 2,48490665 1,386294361 2,079441542 1,386294361
Xj = ln(a,) * 2,079441542 i J 0,693147181 " w 1,609437912 1,098612289
n
1 2 3 4 5 6
Bien ma hoa Xl
-1 +1 -1 +1 0 0
Xj
-1 -1 +1 +1 0 0
Bien thtfc nghiem a 4 12 4 12 8 8
Qi
2 2 8 8 5 5
Chieu sau cat ly thuyet t(mm)
Chieu sau cat thirc tft (mm)
"C
Hinhl.Mo hinh thi nghiem
- Mdy: Qua trinh thi nghiem dupe thuc hien t r i n m i y Tien SJ410x1000G eiia hang ECOCA do Bai Loan sin xuat.
• Dung cu cdt:
Than dao PDJNR2020K15 ciia h i n g MITSUBISHI sin xuat.
- Minh dao: Ky hieu m i n h dao:
BNMG 15 04 08 - MR 2015 do hang SANDVIK sin xuat. Cae gdc sau chinh va gdc sau phu ciia dao dung eho thi
nghiem dupc mai dat ddng gdc dp tr^n m i y m i l chuyen diing (hlnh 2).
Theo quy hoach thUc nghiem [2], ta chpn mien nghien eUu thuc nghiem v6i cic gdc sau chinh a va gde sau phu a, la:
a^^ = 12'';a^,„ = 4°
a,m„ ^ 8"; a,^,„ = 2"
Cac yeu t d thuc nghiem la:
MUc tren: x"'=ln(a|^J;
MUccasd:x™= 1/2{ln(a|^^J+ln(a, J ) MUc dudi: x^"" =ln(Q,^,J; Khoing bien thien: p. =1/2(ln(a,^j -' ln(a,^„))
Ket q u i tinh theo b i n g 1.
Vdi 2 bien dau vao, ta se tien hanh 6 thi nghiem trong dd cd 2 thi nghiem d trung tam (mUe cO sd) theo bing quy hoaeh thuc nghiem (bing 2):
Hinh 2 Thiet bl mai dao
J, Tap dit KHOA HpC&CONG NGHE. So 2 2 . 2 0 1 4
SClENCETECHNOLOGYl
Bang 3. Ket qu^ tinh chieu sau cat thi/c
TI 1 2 3 4 5 6
Bien ma hoa Xl -1 +1 -1 +1 0 0
X!
-1 -1 +1 +1 0 0
6ien thuc nghiem u 4 12 4 12 8 8
ai 2 2 8 8 5 5
Chieu sau cat ly thuyet t (mm)
1 1 1 1 1 1
Chieu sau cat thuc ty, (mm) 0.745S 0,7745 0,944 0,965 0,929 0,908
B^ng 4. Ket qua tinh he SO at
TT 1 2 3 4 5 6
Bien thuc nghiem a 4 12 4 12 8 8
Ui 2 2 8 8 5 5
Chieu sau cat ly thuyet t (mm)
Chieu sau cat thuc tm (mm) 0,7435 0,7745 0,944 0,965 0,929 0,908
HesoAf
0,7435 0,7745 0,944 0,965 0,929 0,908
• Phoi dung trong thUc nghiem:
Phdi thep C45,1-160,037,5 tdi the tich dat dp eUng 45-50HRC.
TrUde khi t h i nghiem tien hanh mai 6 phdi t h i nghiem dat kich thUdc a>37±0,005
• Che dp cdt:
Dieu kien thUe nghiem gia cdng thd nen chpn che dp cat nhu sau:
V = 80 (m/ph); t - 1mm; S 0,15(mm/vg)
• Thiit bi do kich thUdc dUdng kinh sau gia cdng:
May do quang hpc Nikon Profile Projector V-12B do ehinh xac dat dupe den phan nghin.
2.3. K^t qud thi nghiem Sau khi c i t , sU dung thiet bi do quang hpc do dudng kinh chi tiet va xic dinh chieu s i u cat thiic (bing 3).
2.4. XuT ly ket qud
TU k^t qua tren xac dinh g i i trj he sd A t = t ^ / t ( b i n g 4 ) .
TU phUdng trinh At = C o " , o/^
Logarit hai ve ta dUOc:
ln(At) = ln(C) + a,ln(a) + ajn(a,}
Oatln(At) = y;ln{C) = a^
ln(a) = x,;ln(a,)=x,
PhUdng trinh hdi quy mdi cd dang:
y = a^ + a,x, + a / , [2] (7)
Ta thay nang suit eat thUe chl bang 92,8%.
3. KET LUAN
Qua thuc nghiem vdi md hinh nhat dinh da cho ket q u i tinh nang suit eat thue ed xet 6in anh hudng eiia goc sau chinh va gdc sau phu ciia dao. Ket q u i nay phu hop vdi cac nghien cUu ly thuyet va cd dp tin cay tren 92%.
Tuy nhien no van eP han che bdi chua xet den sU anh hUdng ciia mdt sd yeu to khae nhU: sU dn dinh eiia he thdng cong nghe, ehe dd lam mat khi tien....
Do do khi sU dung can tham khio ve mpt sd yeu td lien quan.
Phin bien khoa hoc: GS.TS. Tran Van Oich
SU dung phan mem MatLab [4] de xU ly sd lieu thue nghiem ta duge:
At = e-"-*"''. aO'""'5.a,<*''*«* (8)
* Nhan xet:
Gde a va a, deu anh hUdng den At.
trong dd gdc a, cd i n h hudng nhieu hdn gdc a. Mdi quan he nay phu hpp vdi eic nghien eUu ly thuyet.
NhUvay khi tinh nang suit eat thUe cho trudng hop tien v i t lieu eUng ta cd the sUdung cdng thUc (2) de tinh.
Vidu:T'mh n i n g suit c i t khi tien v i t lieu cUng vdi trUdng hop a - 10°; a, - 6°;
V = 70(m/ph); S - 0,2(mm/vg); t = 1(mm)
+ Ning suat c i t ly thuyet:
Q^^^^,=V.S.t=70.0,2.1 =14(mmVph}
+ Nang suat cat thuc khi tien phoi da nhiet luyen:
Tacd:
A t = e " " ' " ^ ^ Q0.0J185_Q^O1685
At - 0,928
Ap dyng cdng thUe (3) ta tinh 6ugc chieu sau cat thue:
t,, = t. At - 1.0,928 = 0,928mm Ap dung cdng thUc (2) ta cd nang suit cat thuc:
Q,h=V.S.t,^ = 70.0,2.0,928
= 12,995(mmVph)
TAILIEUTHAMKHAO
[1]. Nguyen Trong Binh, Toi u'u hoa qua trinh gia cong cat got, NXB Giao due, Ha Npi, 2003
[2], Tran Van fljch, Nghien cu'u do chinh xac gia cong bang thuc nghiem, NXB Khoa hoc va ky thuat.
Ha Npi, 2003.
[3]. Banh Tien Long, Tran The Luc, Tran Sy Tuy, Nguyen ly gia cong vat lieu, NXB Khoa hpc va ky thuat, 2001.
[4j. Hoang PhUong, MatLab giai trinh do hpa, NXBTre,TPH6ChiMinh.2000,
So 2 2 . 2 0 1 4 • Tap chi KHOA HOC & CONG NGHE 9
