Xác định độ tin cậy trên cơ sở mòn của chày dưới khuôn ép gạch ceramics của nhà máy gạch mikado thái bình

NGHIEN cuu-TRAODOI X a c dinh t i n cay t r e n cd sd m o n cua chay diidi khuon ep gach ceramics cua Nha may Gach mikado Thai Binh (*) NGUYEN DINH MAN TOM TAT Hien nay, Nha may gach Mikado Thai Binh dang san xua't gach Ceramics tren day chuyen tLf dong cua Italia va dang apdung tieu chuan ISO 9001-2000 quan lyva kiem dinh chat lu'ong san pham.Trong day chuyen do, khuon ep la mot nhufng cum chi tiet rat quan trong, lam viec moi tru'dng an mon, ap life cao, ma sat va mon manh Bo khuon ep gom co cac chi tiet Chay tren, Chay du'di va Vanh khuon, do, Chay dUcfi la chi tiet quan nhat cua khuon, quyet dinh chat lUdng san pham gach cua Nha may Nguyen nhan hong cua no chu ye'u la mon Bai bao gidi thieu ke't qua nghien cu'u tin cay tren co sd mon cua Chay dUdi; dong thdi xac dinh chu ky thay the cua nd theo yeu cau ve tin cay cua ngu'di sCrdung I MO DAU Trong cac da\- chu\ en san xuat hien dai, dp tin cay (DTC) cd y nghia vd cimg quan trpng Neu mpt chi tiet hoac thiet bi nao da\ chuyen cd DTC thap ha\ xa\' hong hdc thi se lam dinh tre ca day chuyen san xuat Hien na} a Viet Nam da cd vai chuc nha may- san xuat gach Ceramics, cac da}- chu}-en san xuat chu yeu nhap til- Italia, Trung Qudc Trong cac da}- chuyen dd, khudn ep la mdt nhirng cum chi tiet rat quan trpng, lam viec mdi trudng an mdn, ap luc cao, ma sat va mdn manh Bd khudn ep bao gdm Chay tren, Cha}dudi va Vanh khudn Chay dudi la chi tiet rat ha} xa} hu hong, thudng xu}-en phai thay the, ga\anh huong xau den qua trinh san xuat Mpt nhiing ngu}-en nhan ga}- su hong la be mat canh ngoai bi mdn nhanh lam giam tudi thp cua Chay So \ di nhu-ng khudn cp nhap ngoai, nhirng khudn san xuat nudc hien na\ cd tudi thp va dd tin ca\- (*) Tnro-ng Cao dang Kmh te - Ki thuat Dai hoc Thai Nguyen TAP CHI c a KHI VIET NAM V tuong ddi thap ngmen nhan hdng chu yeu la mdn Mdn khudn ep ndi chung chii yeu la mdn cao xudc ket hpp vdi mdn hoa hpc Hien nay, Nha may gach Mikado (Thai Binh) dang san xuat loai gach tren da} chu}-en tu ddng cua Italia va dang ap dung tieu chuan ISO 9001 - 2000 quan ly va kiem dinh chat luang san pham Vi vay, DTC cua cac chi tiet va cac thiet bi day chuyen cang trd nen quan trpng De nang cao sire canh tranh, hien tai, Nha may dang su dung khudn ep san xuat nudc (nhu khuon cua Cdng t} Kim Thinh, Cdng ty Lien doanh San xuat Khudn ep FOSHAN, ) Cho den nay, d Viet Nam van chua cd cdng trinh nao nghien ciru ve DTC ciia khudn ep gach Ceramics dua tren co sd mdn dupc cdng bo Vi va}-, viec nghien ciru DTC tren co sd mdn cua Chay dudi khudn ep gach Ceramics cd y nghia khdng nhd ve gia tri khoa hpc va thuc tien Cac ket qua cdng bo da giiip cho Nha ma}- xac dinh duac chu ky thay the cua Cha}- dudi khudn ep gach Ceramics theo yeu cau ve DTC cua ngudi su dung, ddng thdi, nha che tao khuon hoan toan cd the biet duac chat lupng khudn cua minh de cd bien phap de nang cao dp tin cay cua khudn S6 - Tliang nam 2011 NGHIEN cuu-TRAODOI II NOI DUNG VA PHLTONG PHAP NGHIEN ClTU 2.1 Do mon Chdy dudi tgi ca sd sdn xudt Chay dudi cd hinh dang nhu hinh Vi tri Chay tren, Chay dudi va Vanh a trang thai ep nhu hinh Qua khao sat thuc te mdt sd luang ldn Cha} dudi khudn ep da hdng mdn tai cac nha may san xuat gach Ceramics, nhu Nha may gach men Mikdo (Thai Binh), Cdng ty Cd phan Prime (Thai Nguyen), Nha ma} Gach dp lat Viet - Y (Thai Nguyen), thay rang, Cha} dudi mdn nhieu nhat tren be mat ben va d vi tri lan can cac gde cua Chay dudi phai chiu ma sat rat ldn ngu} en lieu bi ep cac khe hd giira Chay va vanh khudn tai cac gde nguyen lieu bi ep chat hon nen ma sat ldn hon cac vi tri khae Hat la: Do to chirc vat lieu tai cac vi tri lan can cac goc kem ben -virng hon cac vi tri khae da}- la ngu}-en nhan chinh lam cho khudn mdn nhieu tai cac \'i tri lan can cac gde Ba Id: Do sai sd lap dat, Cha}- dupc dat lech long khudn, khe hd ban dau gira Chay va cac Vanh khudn khdng thong nhat, lam viec tai nhirng vi tri cd khe hd nhd se mdn nhanh hon Mac du da}- chi la nguyen nhan chii quan, nhung qua khao sat thuc te, cd rat nhieu Chay dudi hdng bdi nguyen nhan (nghia la bdn gde Cha}' se cd mdt gde nao dd cd lupng mdn ldn nhat) 2.1.1 Xac djnh vj tri mon Qua nghien ciru ket cau cua Chay dudi va khao sat thuc te hien tupng mdn cua nd d nhieu co sd san xuat gach Ceramics nhu da trinh bay d tren, tac gia lira chpn phuong an mdn tai diem M nhu hinh 2: M each gde Chay 10mm va each mep tren ciia Chay 1mm 10 M M Hmh Hinh anh Chay duoi Hinh 2: Vi tri mon ciia Chay dudi L Tdm dim tren, Clidy tren, Chdydu&i, Tdm dem dudi, Vanh khudn Hinh Vi tri Chay tren, Cha>- duoi va Vanh a trang thai ep Hinh Hinh anh -vTing mon nhieu nhat tren be mat ben cua Chay dudi \ a \ i tri "M" Co the giai thich dieu nhu sau: Mat Id: Mac dii ngu} en lieu duoc xe cap lieu rai deu nhung ep, luc ep ldn, lam cho nguyen lieu xd ve cac gde nhieu hon Ben canh do, thuc hien qua trinh day vien gach khoi hdc khudn thi Cha} 2.1.2 Sadd De luong mdn Cha}' dudi tai vi tri nhu da xac dinh, chon so dd mdn nhu hinh TAP CHI c a KHI VIET NAM V So - Thang nam 2011 13= NGHIEN CUU - TRAO DOI 10 2.1.3 Dung CIA Dong ho so; Mituto}-o Dp chinh xac; 0,01 mm Chay dirai M Hinh So ga dat ga dung cu A= ^ D - KXXXM D — [>0q c=wm Hinh 4: So do mon Chay ducfi 2.1.4 Do ga dung cu Mdt yeu cau dat qua trinh la phai luong mdn cua diem M theo thdi gian Dieu dd cd nghia la, tat ca cac lan do, vi tri ciia dau phai ludn ludn triing vdi diem M Hinh Hinh chieu true ciia de ga dung cu De thuc hien dupc dieu dd, tac gia da xay dung so dd ga dat nhu hinh va che tao bd ga ddng hd so nhu sau (hinh 6); Cac mat dinh vi cua dd ga la A, B va C Tuong img cd cac mat dinh vi cua Chi}- dudi lan lupt la A , B'va C" Trong dd; Mat A -A khdng che bac tu do; Mat B - B" khdng che bac tu do; Vau C - C" khdng che bac tu Cac mat dinh \ i A , B"va C'cua Chay phang va khdng mdn De kep chat dd ga tac gia chpn phuang an kep chat bang luc tir Phuong an don gian, kep chat chac chan tiet kiem thdi gian va de thao tac Hmh 7: Hinh anh he thong ga va dung cu 2.1.5 So lircmg Chay khao sat Sd lupng Cha}- n dupc chpn de khao sat phai hop ly Neu la}- n cang ldn thi cdng viec khao sat, udc lupng cang hieu qua cang dang tin ca}- Nhung n cang ldn thi cang tdn kem cang mat nhieu thdi gian va cdng sire Vi va}' can chpn sd lupng Cha}- la it nhat nhung van dam bao dupe dp chinh xac mong mudn Vi sai lech chuan o chua biet, nen sd lupng mau dugc chpn theo cdng thirc s a u [ l ] [6]; TAP CHI c a KHI VIET NAM V (1) n>u-p.s7sTrong dd; • u„- chi tieu tin cay img vdi xac suat tin cay cho trudc [3 • s- la mdt sd dii be dupc chpn trudc cho vdi xac suat dp tin ca} p thoa man xac suat P|U- ii] < s, d day; So 5-Thang nam2011 w U- trung binh cua mau \\- \x - ky vpng cua dai lupng ngau nhien • S phuong sai mau Nd dupc xac dinh bing each NGHIEN CUU - TRAO DOI lay so bd mdt mau cd so luong m > 30 de khao sat mdn, thdi diem mdn; sau chay may 460 gid; phuong sai mau s- dupc xac dinh theo cdng thirc; (2)S^ 2.1.9 Gidi han khao sat -Z(u,-U)^ m - i=i Khao sat lugng mdn cua Chay dudi dieu kien lam viec thuc te; Luc ep P = 1800 tan; Sd lan ep; llan/ phut Trong dd; w u- lugng mdn cua mau thir thir i wU- gia tri trung binh cua lugng mdn; (3) U = (u,+ u + u,+ + u ) /m ^ ' _ ^ phuang an lupng mdn tai thdi diem; Tai thdi diem gid va sau thdi gian lam viec 230 gid, 460 gid 690 gid va 920 gid (khoang each giiia hai lan lien tiep la khoang 10 ngay) Tai thdi diem gid lugng mdn U = m^ w m - sd lugng mau khao sat so bd; lay m = 32 Theo ket qua khao sat so bd ta cd; U= 0,09mm, s ^ 0,0013mm2 San pham gach Ceramics cd kich thudc 250mm x 250mm x 7,5 mm Mdi lan ep dugc 10 vien 21.10 Kit qua mon Chdy dudi tgi ca sd sdn xuat Sau xac dinh ket qua tir cac sd lieu trung gian va khir cac sai sd thd, ta cd bang sd lieu nhu sau (bang 1) De khao sat mdn cua Chay dudi khudn ep gach Ceramics chpn xac suat dp tin cay (3 = 0,95, tuong irng 2.2 Phu-oTig phap xac djnh DTC ciia Chay dirdi cdM^= 1,96 Chpne = 0,012mm.Tacd; n> 1,96-.0,0013 tren cff sff mdn [3] / 0,012- = 34,68 Chpn n = 35, nghia la sd lupng Chay Sau da cd sd lieu thdng ke ve lupng mdn ciia dudi dupc chpn de mdn la 35 chiec Chay dudi khudn ep tai thdi diem, tien hanh xac dinh 2.1.6 Cac birdc DTC Clia nd theo trinh tu budc sau day; Budc 1: Lam sach cac be mat dinh vi, be mat Bang 1: Ket qua mon ciia Chay dudi tren Chay va dd ga Budc 2: Ap dd ga len mat dinh vi ciia Chay va kep chat dd ga bang luc tir (d day chpn phuong an kep chat ga bang nam cham vTnh ciru) Budc 3: Lap ddng hd so len dd ga va tien hanh dieu chinh ddng hd so (theo quy dinh ve hudng dan su dung), sau dd, tien hanh kep chat ddng hd so vao dd ga that each chac chan Budc 4: Ghi sd lieu va xac dinh ket qua tir cac sd lieu trung gian 2.1.7 Xac djnh lircmg mdn gidi han (U^^) Qua mdn cua 150 Chay dudi khudn ep da bi Nha may loai mdn (tai diem nhu da xac dinh d muc 2.1.1), thay rang, lupng mdn ciia cac Chay dudi dao ddng khoang tir 0,2 -^ 0,24mm Do vay, cd the xac dinh dugc lugng mdn gidi han cua Chay dudi la; U ^ = 0,2mm Dieu cd nghia la, lugng mdn tai vi tri > 0,2 mm thi Chay dudi bi loai bd 2.1.8 Thoi dilm khao sat Khi xac dinh tin cay tren co sd mdn, ve ngu} en tic cang nhieu thdi diem thi tin cay cang dugc dam bao Tuy nhien, cang nhieu thdi diem thi cang tdn kem kinh te va mat nhieu thdi gian Can cir vao lupng mdn gidi han va thdi gian lam viec cua khudn theo khu\ en cao ciia nha san xuat, can cir vao thdi gian lam viec thuc te cua Cha}- tai nha may (23 gid/ ngay), chpn t : ;?o ai4- t = 4*0 nW 0.056 0.080 0,152 0.190 0 0.040 0.093 i 0.0S7 0,150 0,1410 0.197 0.040 0.185 i 0.056 0.050 0.100 0.100 0,145 0.102 0.055 0.093 0,140 0,140 0.190 0.188 i : 0,192 0,105 i i e 0 t = 630 olfr t= 8:o ol*' i t- 014' : 0.060 0.093 0,145 0.042 0.095 0,150 0.045 0.095 0,140 10 11 0 0.053 0.047 0.098 095 0,136 0,200 0,188 ; i 140 0,185 12 0.050 0.112 0.200 i 13 0.050 0.098 0,160 0,150 0.200 i 14 0.052 0,150 0.180 ; 15 0.047 0.105 0.080 0,135 0.105 i IS 0 0.052 0.056 0,110 0,080 0,145 0.200 i i 0.046 0,089 0,152 0,130 0.19S 0,185 i i 17 18 13 0.050 0,090 0.050 0,100 146 0,147 0,200 20 0,182 i 21 0.050 0,100 0.14i: 0,190 i 22 23 0.053 0,200 i 0.055 0,085 0,115 0.156 0,140 0,180 ; 24 0 0.043 0.056 0,090 0,140 0,195 ; 25 0,100 0.146 200 i 26 0,065 0,095 0.140 0,200 : 27 0.060 0,105 0.145 0,187 i 28 0.058 093 0.149 0,190 : 23 0.052 0.100 140 0.190 i 30 0.062 0,095 130 0.200 \ 31 0.046 0.04S 0.1.58 0.150 : 0,090 0,117 0.190 32 0,200 ; 33 0,082 094 0.140 0,182 i 34 0.046 0,120 0.139 0,200 i 35 0.047 0,095 0.140 0,180 : Budc 1- Tuyen tinh hoa cac the hien mdn Budc 2- Xac dinh thdi gian hdng mdn (tudi thp mdn) cua Chay dudi ' TAP CHi C a K H i VIET NAM V S6 - Thang nam 2011 NGHIEN CUU - TRAO DOI Budc 3- Xac djnh ham mat dp phan phdi tudi thg mdn f(t) Budc 4- Xac dinh DTC cua Chay dudi khudn ep; Biet ham mat phan phdi f(t) hoac dd thi cua nd ta hoan toan xac dinh dugc DTC cua Chay dudi tai thdi diem bat ky t^^: (4)R(t,J= Jf(t)dt=i |f-(^)^^ '* Can cir vao ham tin cay R(t) ve dugc thi dp tin cay theo thdi gian cua Cha}- dudi 2.3 Ket qua DTC cua Chay dirdi tren cff sff mon Can cir vao lugng mdn tai thdi diem cua Chay dudi (bang 1), su dung phan mem chuyen dung de thuc hien budc nhu da neu a muc 2.2 cho ket qua sau; - Ham mat dd phan phdi tudi thp mdn f(t) va dd thi ciia nd nhu hinh - Ham DTC cua Chay dudi R(t) va dd thi cua nd nhu hinh t(gid) 870 R(t) 875 0.9987 t(gid) 905 R(t) 0.9655 0.9977 910 0.9498 880 0.9961 915 0.9290 885 0.9935 920 0.9021 890 0.9904 925 0.8757 895 0.9849 930 0.8362 900 0.9768 935 0.789 Tir bang 2, ngudi sir dung hoan toan cd the xac dinh dugc chu ky thay the cua Chay dudi theo yeu cau DTC dat trudc, cirng nhu xac dinh dupc DTC cua Chay dudi theo thdi gian lam viec cua nd Vi du; Mudn xac suat lam viec tin cay cua Chay dudi dat 99,87% thi chu ky thay the cua Chay la T = 870 gid Vdi chu ky thay the se cd 0,13% Chay dudi bi hdng mdn thdi gian ay III KET LUAN 1- Can cir vao ham tin cay da dugc xac dinh, hoan ' toan xac dinh dugc DTC cua Chay dudi tai mdt thdi diem y So thj ham mat phan phoi Gauss 0.01387 C D97C ^.0097089 1337 900 950 1000 1050 fi'ti=0,01354,e-°°™s^S-('-S59orar Bang 2: Bang tia DTC theo thoi gian cua Cha>- duoi t(gid) Hinh 8: Ham mat dp phan phoi tuoi tho mon va d6 thi f(t) Qo th{ ham tin cay 87143 2- Tuy theo yeu cau ve DTC ciia ngudi sir dung, dinh dupc chu ky thay the cua Chay dudi Chpn diing thai diem thay the cd tac dung rat ldn viec dam yeu cau ky' thuat cua Id gach dugc san xuat, ddng thdi ngudi sit dung hoan toan chu ddng ve thdi gian thay the Chay dudi va cd ke hoach chuan bi day du sd lugng chay du trir 3- Tren co sd DTC da xac dinh dupc cua Chay dudi, nha che tao khudn hoan toan cd the biet dugc chat lugng khudn cua minh, qua dd cd bien phap de nang cao dp tin cay cua khudn • Tai lieu tham khao: 900 950 1000 44386 1050 t(gid) Ham tin cay R(t)=1-'l>[(t-959 079)/29.4634] Hinh 9: Ham tm cay cua Cha> dudi R(t) va tlu ham R(t) Tir ham dp tin ca}-; (5) R(t) = l- 0[(t-959,079)/29,4634] {O day: 0[ ] id hdm Laplace, t Id thdi gian ldm viec cua chay dudi den hie hong mdn) cd the xac dinh dugc DTC cua Cha} dudi sau moi thdi gian lam viec nhat dinli (bang 2) TAP CHi CaKHi VIET NAM V [1] Bill Cong Cuong, Biii Minh Tri (1997), Gido trinh xdc sudt vd thdng /ce img dung, NXB Giao thong Van tai, Ha Noi [2] Phan Van Khoi (2001), Ca sa ddnh gid tin cdy, NXB Khoa hoc va Ki thuat, Ha Noi, [3], Nguyen Dinh Man {2005),Luan dn tiin silathugl [4] Buohni Alessandro (1999), Reliability Engineering Theory and Practice, Springer, Berlin [5] Birolini Alessandro (2003), Reliability Engineering, Sprmger-Veriag, Beriin Heidelbeg [6], Dot>- L.A.(1985,I989), Reliability to the Technologies, Industnal Press, New York [7].SingiresuS.Rao(1992),i?e/ra/);-%6aserfc^e57g?!,SchoolTechnology Engineering University- Purdure University, Mc.Graw, Hill USA [8] Shigley J E and Mischke C R (1989), Mechanical Engineering Design, Mc Graw - Hill, New york So - Thang nam 2011 ... NAM V (1) n>u-p.s7sTrong dd; • u„- chi tieu tin cay img vdi xac suat tin cay cho trudc [3 • s- la mdt sd dii be dupc chpn trudc cho vdi xac suat dp tin ca} p thoa man xac suat P|U- ii] < s, d... cao dp tin cay cua khudn • Tai lieu tham khao: 900 950 1000 44386 1050 t(gid) Ham tin cay R(t)=1-''l>[(t-959 079)/29.4634] Hinh 9: Ham tm cay cua Cha> dudi R(t) va tlu ham R(t) Tir ham dp tin ca}-;... thi Chay dudi bi loai bd 2.1.8 Thoi dilm khao sat Khi xac dinh tin cay tren co sd mdn, ve ngu} en tic cang nhieu thdi diem thi tin cay cang dugc dam bao Tuy nhien, cang nhieu thdi diem thi cang