NGHIEN CljrU-TRA0D6i
PHU'aNG PHAP TINH CHON CONG S U A T DONG CO RUNG KHLC U'NG S U A T DU*
METHODS FOR CALCULATING AND SELECTING ENGINE POWER FOR RESIDUAL STRESS REDUCTION VIBRATION
Hoang Trung Phuorng, Biii Manh Cirdng Hpc vifn Ky thuat Quan sy
TOM TAT
Bdi bdo trinh bdy kit qud nghien euu de xudt phuang phdp tinh chgn cong sudt dgng ca cho phdn tu gdy rung (ddu rung), iing dung trong cong nghe khu ung sudt du bdng rung dgng. Kit qud nghiin euu tinh todn ly thuyet theo cdc phuang phdp khdc nhau duac so sdnh vdi cdc kit qud thuc nghiim tren ddu rung da thiit ki vd chi tgo. Cdc kit qud nghien euu gdp phdn quan trgng trong thuc tiin ky thuat khi tinh todn thiit ki cdc ddu rung iing dung trong cong nghe rung khu ung sudt du.
Tir khda: Cong sudt dgng ca rung khu ung sudt du; Phuangphdp tinh todn cdng sudt.
ABSTRACT
This paper presents the study results to suggest methods for calculating and selecting engine power for the vibration element (vibrating tip) applied in the technology of reducing residual stresses by vibration. The research resuhs of the theoretical calculations according to different methods are compared with experimental results on the vibrating tip that has been designed and manufactured. These findings contribute importantly to the engineering practice when calculating and designing vibrating tips applied in the technology of residual stress reduction vibration.
Keywords: Engine power for residual stress reduction vibration; Method of calculating
capacity. "^
ISSN 0866-7056
T ^ CHI CO KHi VIET NAJVl. Sd 11 nam 2015 www.coldiivietnam.vn
N G H l t N Cljru-TRAQD(!)I
l.DATVANDE
Khii ling suit du trong chi tidt va kdt ciu bing rung dpng la mdt ky thuat tuang ddi mdi, da va dang dugc nhieu nude trdn the gidi cd nen cdng nghifp ca khi tidn tidn quan tam nghidn Cliu trong nhfing nam gin day, do nhimg uu didm ndi trgi ciia nd ma cac phuang phap truydn thdng khdc khdng cd dugc nhu: Cd thd khii ling suit du cho cac chi tidt han va diic cd khdi lugng, kich thudc ldn ma phuang phap li truydn thdng khd cd thd thyc hidn dugc, chi phi va tieu hao nang Iugng thap, dan gian trong thyc hifn...
Phuang phap nay, sir dung dpng ca rung gdm cac qua n ^ g Ifch tam dd tgo dao ddng cudng biic d tan sd thich hgp cho kdt cau can khii iing suat du, vd ca ban dpng ca rung khu iing suat du cd kdt cau gan gidng vdi ddng ca gay rung dung lam dam rung, ban rung, sang rung, hiia may...
trong nganh Xay dyng, tuy nhidn, nd phai lam vifc d van tdc cao hon nhidu cd thd ddn 120 Hz.
Vifc tinh chpn cdng suit cho ddng ca rung khii ting suat du hifn nay vln con la bi quydt cdng nghf ciia cac hang va it dugc cdng bd rpng rai.
Bdn cgnh dd, cac phuang phap tinh chpn cong suat ddng ca rung trong cdc trudng hpp dung cho dam rung, ban rung, sang rung, biia may...
lai rat da dgng va khac nhau, didu nay gay khd khan cho cac ky su va cac nha thidt kd dpng ca rung khii iing suit du. Trong didu kifn nhu vay, nghidn ciiu de xuat phuang phap tinh chpn cdng suit ddng CO rung khOr iing suit thuc sy cin thidt trong ling dyng thyc tien ky thuat khi tinh toan, thidt kd cac dpng ca rung umg dung trong cdng nghf khu ling suit du nhd dao ddng.
2. CAC PHU'ONG PHAP TINH CHON CONG SUAT D O N G CO RUNG
Tinh chpn cdng suat ddng ca rung khii ling suat du noi chung cd thd thyc hifn dya theo mdt so phuang phap sau:
- Phuang phap dya vao md men xoan, dau true:
Phuang phap nay gidng nhu phuang phap tinh chpn cdng suat dpng ca diing trong hf thdng din dOng bSng tai. Ddng co rung gdm cac qua Ifch tam dugc lip tryc tidp vao true ddng ca, do dd khi lam vifc d che dp binh dn (w^ const), ta coi md men quay ciia roto chi phi chi dd thing md men tinh ldn nhat T ddi vdi true quay do trpng lupng ciia tit cac khdi lech tam gay ra:
T = M^.g(Nm) (1) C day, g - Gia tdc trpng trudng, cdn M^,- Tdng md men tinh khdi Iugng ciia tit ca cac khdi Ifch tam so vdi tryc quay:
M^ = z.mg.r^(Nm) (2) Vdi z - Sd lugng qua Ifch tam; mg - Khdi
lugng ciia I qua Ifch tam; rg - Khoang each tir khdi tam ddn tryc quay.
Thay (2) vao phuang trinh (I) ta nh$n dugc:
T = M^.g = ztngrgg(Nm) (3) Vay, cdng suit can thiet cua ddng ca P^
phai thda man (1,2,3).
F,>P = Tco M^go) znigrggo)
(kW) (4)
1000 1000 1000 Tu bidu thiic (4), ta thiy ndu cho trudc cdng suat cua dpng co P , va cac thdng so cua qua nang (z/m^/rj,), ta hoan toan cd thd xac dinh dugc vgn tdc quay ldn nhit cua dpng ca la:
CO = 1000- zm^r^g
(5)
ISSN 0866 - 7056
TAP CHi CO KHi VIET NAM, Sd 11 nam 2015 www.coldiivietnam.vn
NGHIEN CljrU-TRAODOl
Vdi CO - Van tdc gdc ciia roto (rad/s).
- Chgn cdng suat ddng ca rung khu ung
suat du theo cac phuong phap diing tren dam khdi tam ddn tryc quay, rung, sang nmg, ban rung...
Vdi z - Sd lugng qua Ifch tam; mg - Khdi lugng cua I qua lech tam; rg - Khoang each tu
Vdi kdt cau tuong ty, dpng ca nmg dugc dimg kha phd bidn trong nganh xay dyng iing dyng trdn cac dam rung, ban nmg...Muc dich chii ydu lam ch^t be tdng, dat da... dd cd thd tinh chpn cdng suat ddng ca rung khu iing suat du gidng nhu ddng co rung dung trong cac trudng hgp nay ta phai coi khoi lugng chi tidt can rung khii ling suat du ddng vai trd nhu tdng khdi Iugng ciia ban rung va khdi bd tdng can rung.
Khi dd, cong simt dpng ca rung khOr iing suat du dugc xac dinh theo bidu thiic (4,5):
Tu cac bidu thiic (6), (7), (8) va (9), ta thay ndu cho trudc cdng suat ciia ddng co/^^va cac thdng sd ciia qua nang (z/m^.Tg) ta cd thd xac dinh dugc van tdc quay ldn nhat cua ddng co
p.+p.
Voi: T\ = 0,95 + 0,96 - Hieu suat tao dao dgng Ciia dpng ca rung; ConPj,P^- Ldn lugt la cong suit dao dgng va cdng suat ton hao truyen dgng, duac xac dinh ISn lugt theo cac bieu thiic (7)va(1.8)[5]: '
(7)
(8) Trong do: n - H$ so ma sat lan |i = 0,005...0,008;f7„- Bien dp dao dpng cua chi ti£t; d - Duong kinh ngSng true dgng co (d=20 mm); F^ - Lyc cu5ng buc dao dOng (quan tinh ly tam) do dku rung t^o ra, xac dinh theo bieu thiic (1.9).
F„=zm/oft>'(Nm) (9) 47]P^,
2nigrg(Ug + 2nd) (rad/s) (10)
(6)
- Chgn cong suh dgng cff rung khu mtg sudt die theo phirffng phdp CepaeeeBM [4] de xudng.
Dgng CO rung khii iing suat du phai lam vifc trong didu kifn khac nghift, quay nhanh, chiu tai hudng kinh ldn va la yen td chu ydu, md men tai nhd, ndn vifc tinh chgn cdng suat ddng ca ndu theo phuong phap truyen thdng la dya vao md men tai diu tryc ddng co la chu yeu, bd qua tdn thit ma sat d va tdn hao tii thdng, cy thd cdng suat ddng co dupc xac dinh theo phuang trinh (4), thi kdt qua nhan dugc se khdng tin cay, bdi vdi didu kifn lam vifc quay nhanh va chiu tai hudng kinh ldn thi ma sat d la rat ldn. Do vay, ddi vdi ddng ca rung khii iing suat du vifc tinh chpn cdng suit dpng co can cd sy thay ddi so vdi phuang phap truydn thdng, trong dd, phai ke den dugc eac ydu td tdn hao ma sat d va tii thdng.
Tinh cdng suit cin thidt cua ddng co P^^ (kW), theo cdng thiic do giao su CeprecBB.II dd xudng:
P^=(U5..1,3)-^^ti(kW) (11) Trong dd,/- Tan sd quay ciia qua nang lech tam (Hz), d - Dudng kinh ngong tryc {d^20 mm), \i- He sd ma sat lan cua d dd, ddi vdi d bi*^
ISSN 0866 - 7056
TAP CHf CO KHi VlfiT NAM, Sd II nam 2015 www.cokhivietnam.vn
NGHIEN CIJfU-TRAOOCi
p = 0,004^0.006. Fg- Luc quan tinh ly tam (N), dugc xac dinh theo cong thiic (9).
lip trdn 2 d i u true ddng ca, khdi lugng cua mdM> I cap qua nang mj^ 3,045kg; Khoang each hi khdi 1
tam ddn tryc quay r^ ^ 28,I35mm. i
P^=(h25.U)-
Thay (9) vao ( I I ) ta thu dugc:
FJd I9.5.1(f ii = (l2Ui}-
2!tl9,51IJ' T//(kW) (12) Tii bidu thiic (4), ta thiy ndu cho trudc cdng suit ciia dgng c a P , va cac thdng sd cua qua ngng ( z ; Mg; r^) ta cd the xac dinh dugc van tdc quay ldn nhat cua ddng ca la:
27119,5.10'P^, , ,,.
G) = 3 '-^— (rad/s) (l,25..1,3)zm,rgd^
(13)
3. K E T QUA THlTC N G H I | : M
Dd nghidn ciiu va kidm tra miic do chinh xac cua cac phuong phap tinh chpn cdng suat dpng CO rung khii iing suit du dugc trinh bay d trdn, nhom nghien ciiu da thidt kd, chd tgo ddng CO rung (hinh I) vdi cac tham sd sau: Cdng suat ddng ca: P^^ = 0,75 kW, so qua nang z ^ 4 dugc
Hinh 1. Ddng ca rung khic img sudt du
Tidn hanh nghidn ciiu thii nghifm didu khidn tdc dp ddng co qua bidn tin. Qua Uinh thu nghifm dugc tidn hanh nhu sau: Dgng co dugc ga chic chin trdn gia do (hmh 2) va duac didu khidn tdc dp quay qua bidn tan tu 10 v/ph ddn gia tri Idn nhit ma dpng co cd the dat dugc, kdt qua thu nghifm va tinh toan ly thuydt tdc dp ldn nhit ma ddng ca cd the dat dugc theo cac phuong phap d trdn dugc trinh bay trong bang I. Trong dd, luu y ring khi tinh chpn cdng suat dpng ca rung khii iing simt du theo cac phuong phap dung trdn d i m rung, sang rung, ban mng...
gia thiet rang khdi Iugng chi tidt rung la 7000 kg, bidn dp dao ddng 0,5 mm, p. = 0,004, •x]- 0,95.
J /. Vdn toe quay ldn nhdt ciia dgng ca co the dgt dugc (rad/s):
Ket qua thirc nghiem
351,68
Ket qua tinh toan ly thuydt Phirong
phap dua vao mdmen
xoin d i u true 443,94
Sai so
%
26,2
Theo cac phuong phap diing tren d i m rung, sang rung, ban rung...
29,32
Sai so
-91
Phuang phap CepreeBB.n
319,86 Sai so
-9,1
ISSN 0866 - 7056
TAP CHi CO KHi VlfiT NAM, Sd U nam 2015 www.cokhivietnam.vn
NGHIEN CUrU-TRAOeOl
Hinh 2. Dgng co rung khu img sudt du tren gja
Dua va bang 1, ta thay khi tinh chgn ddng co rung khii ung suat du theo phuang phap truyen thdng la dya vao md men xoan dau tryc ddng c a cho sai sd so vdi thyc nghifm ldn han 20%, cdn tinh theo cac phucmg phap nhu dung trdn d i m nmg, sang rung, ban rung... thi khdng du co sd va sd lifu phii hgp dd tinh toan va cudi cung phii hgp hon ca la tinh chpn cdng simt dpng co nmg, khu iing suat du theo phuong phap do giao su CepreeBB.n de xudng.
4. K E T LUAN
c a c kdt qua thuc nghiem va tinh toan ly thuydt cdng suat ddng co rung khii iing suat du dugc trinh bay trong bai bao thyc sy cd y nghta thyc tien, khi thiet ke ddng co rung ung dyng trong cdng nghe khii ung suat du nhd dao ddng, nd da dinh hudng lua chpn phuong phap tinh cdng simt ddng CO rung khu iing simt du mpt each hgp ly.
Kdt qua nghien euu cho thay, ddng co rung khii iing suat du phai lam vifc trong dieu kifn khic nhift, quay nhanli, chiu tai hudng kinh ldn va la yeu td chii ydu, md men tai nhd ndn vifc tinh chpn cdng suat dgng ca neu theo phuong phap truydn thdng la dya vao md men tai dau true dpng CO la chu ydu, bd qua tdn thit ma sat d va tdn hao tir thdng do sii dyng bidn tan, thi kdt qua nhgn dupc sd khdng tin cay. Cdn khi van dyng cac phuong phap nhu dimg tren d i m rung, sang rung, ban rung... thi khdng dii co sd va sd lifu phu hpp dd tmh, trong trudng hgp imy thich hgp hon ca la sii dyng phuang ph£q) tinh do giao su CeprecBB.H de xudng.*t*
Ngay nhan bai: 12/10/2015 Ngay phan bifn: 05/11/2015 Tai lieu t h a m k h a o :
[1]. Trinh Chit, Le Van Uydn, Tinh todn thiit ki hi dan ddng ca khi tgpl, tdp2. NXB. Giao due, 2002.
[3]. Nguydn Trpng Hiep, Chi tiit mdy, tap 1, tap 2 , NXB. Giao due, 1994.
[2], Nguydn Van Lim, Nguyen Trpng Hiep, Thiet ke chi tiet mdy, NXB. Giao due, 1993.
[4], Ceprees B.II. CTpoHrejibHue MaumHW H odopynosaHMe, M.: Bucm. UIK., 1987. -376c.
[5].noco6He no TexHOJiorHH ^wpMoeaHiw acejiesoSeroHHbix HSflejmH.Opaeua TpygoBoro Kpacnoro SHaMCHH HjyiHO HCCJieflOBarejibCKHH HHcnrryr GeroHa H3Kejie3o6eT0Ha. yxBepMcneHO npincasoM HHHaCB Foccxpofl CCCP OT 7 HKuia 1986 r. Ks 38. MocKBa CTpomnflar 1988.
ISSN 0866 - 7056
TAP CHI CO KHI VIET NAM, Sd I i nam 2015 www.cokhivietnam.vn
