NGHIEN ciiu - TRAO D 6 |
Cac dang hif hong cua canh trdn
trong thiet bi tron be tong hai true ngang khi tron be tong dam lan
1. flat van tii
Hien nay, tren the gidi cung nhif d Viet Nam, cdng nghe be tdng dam Idn da dUde tfng dung rdng rai trong viec thi cdng cdc cdng trinh be tdng cd khd'i tich Idn, hinh dang khdng phtfc tap nhU dap thuy ldi, thuy dien, mat du'dng nhU cdng trinh thuy dien Sdn La, thuy dien Ban Chat (Lai Chau), thuy dien Ddng Nai,...
Dac diem cua loai be tdng dam Ian la be tdng cd dp sut thap (tifdng ddi khd), kieh thUde cd hat vat lieu Idn, be tdng dam ian (BTDL) so vdi be tdng thdng thudng cd sd lupng cdc thanh phan cdt lieu nhieu hdn (5-8 thanh phan), vdi loai da cd kich thUde khdc nhau (ttf 5-150 mm) va ed them nhieu loai phu gia khac nhau.
Cdng nghe thi cdng cua be tdng dam Idn la thi cdng mpt khd'i lUdng be tdng Idn (vai ngan khd'i trong 1 ca san xuat) trong mpt thdi gian lien tuc nen thiet bj san xua't be tdng dam lan ddi hdi phai boat dpng dn djnh vdi cUdng dp rat eao.
Loai cdi trdn hai true ngang dvldc stf dung nhieu nhat trong san xua't be tdng diim lan, dd la loai thiet bj ed hai true va tren dd cd bdtri cac canh trpn lam nhiem vu trpn deu hdn hdp vat lieu (cdt, dd, xi mdng, phu gia) de tao ra be tdng diim lan. Do tinh chat va dae diem cua be tdng dam lan nen cac cdnh trdn lam viec trong dieu kien he't stfc khdc liet de gay hif hdng cdnh trdn nen ddi hdi viec nghien ctfu danh gia chinh xdc cdc da- . ng hu hdng ciia cdnh trpn va nguyen nhan gay hU hdng
van la van de can phiii di sau va danh gia them de ttf dd cd cdc bien phdp cdng nghe khiic phuc nham nang cao tudi thp cua thiet bj, giam gid thanh san pham.
Z. Cfii trOn hai true ngang vii cac dang iiif hong
(*) TS. NGUYEN DtTC MINH - ThS. TRAN NHl/ HIEU nhao trdn manh va phtfc tap (Hinh 2), cd the trdn difdc cac loai be tdng vdi cdt lieu cd Idn, cdc loai hdn hdp vat lieu deo va cac loai be tdng cd dp sut thap.
Hinh I: Ket ciiu toi iron be king cU3ng bOfc hai triic ngang Than thung tnin (2) cd dang hinh inang, hai true trpn (I) dupe bd tri trong Ihiing trpn nhU (Hinh 1), hai true trpn quay ngUde chieu nhau, cac canh (4) trdn dUde lap tren cac true iron va dUde ga nghieng gdc vdi true trdn.
Cdi Iron hai true ngang tao ra nhtfng chuyen dpng
Hinh 2: Quy dao chuyen dong phiic tap ctia vat lieu vii khu vifc nhao trpn
Trong cdi trpn hai triic ngang cdc cdnh trdn dUdc gd nghieng gdc vdi true trpn nen ddng vat lieu se dUdc cac canh trpn quet va nang len, chuyen dpng ngUdc chieu nhau dan xen vao nhau ttfng ldp theo sudt chieu dai thung trpn, viec chuyen ddng hdn loan cua cdc ddng vat lieu se cd tac diing nhao trpn td't tao nen sif ddng deu ciia be tdng. O day cdc hat vat lieu se chuyen diing va trUdt tren be mat cua canh triin tao nen ma sat tru'dt lam mai mdn be mat ciia canh trdn, ddng thdi vdi viec bd' tri cdc cdnh trdn so le nhau va dpc theo sudt chieu dai true trdn ed tac dung lam cho cac hat vat lieu chuyen ddng lien tuc, tang chat lUdng eiia be tdng tuy nhien cung lam cho cac canh trpn phiii ehju cae Itfc va dap theo ehu ki lien tuc tai trpng tac ddng thay ddi se dan den cac canh trdn nhanh bi hU hdng. Khu vifc ehju mai mdn nhieu nhat la khu vifc nhao trdn khde liet ndm gitfa hai true trpn, phan bj mai mdn cdn lai chii yeu la d phia mat dUdi cua thung trdn (Hinh 3).
(*) Vien May va Dting cii Cong nghiep
TAP CHi Cd KHi VIET NAM • V. 1 o - rii.in.t; S n.liii l'»'"
El
NGHIEN ClTU- T R A O D d l
Hinh 3: Pham vi chiu mai mon tren than cdi Trong qud trinh trdn be tdng, cdnh trpn se phai chiu tdng hdp cdc life rat phtfc tap (Hinh 4)
:
:' .-...r-V-X J .
/ . • » . • • • ' - : - . » ' ' f •-•
-» 1 " ^ ^^ ^ - « » w '-
•
1 ^W
J'
•, /
Hinh 4: Cac life can len canh tron
Theo Hinh 4 thi cdnh trpn se bi hif hdng do ehju I sd cac Itfc chinh nhif sau:
- Life W| la Itfc can ma sdt do chuyen ddng gitfa hdn hdp va thanh cua thung trdn
- Life W^ la life ma sat cua hdn hpp sinh ra dp life Q, tdc dung vudng gdc vdi canh trdn ddt nghieng 1 gdc d so vdi hifdng trpn (Hinh 5).
t ^ -
3 .." J
1 . . . ' •
, • • 1 ' . ' : ^
t
• ' . . • • • • • • . . - ? : x :
- • • • • - • • - 1 L /
Hinh 5: Sd dd chiu life ciia canh tron
- Ltfc W^ la Itfc can ti le vdi tfng suat eat cua hdn hdp tdc diing len canh phia tren cua canh trdn.
- Ltfc Wj la ltfc can ma sdt do trpng lUpng cua hdn hdp sinh ra d phia tren cua cdnh.
- Ltfc W la ltfc can nang do trpng lu'dng cua hdn hdp sinh ra d phia tren ciia canh.
- Ltfc Wg la ltfc can ma sat tren be mat cdnh trpn dat nghieng mpt gdc Ct eua cdnh.
Do tinh chat cua be tdng dam lan va ket eau bd tri cua canh trpn eung nhU dieu kien lam viec va ehju lUe tdc dpng Clia nd, ed the ndi dang hU hdng ehii yeu cua canh trdn la mdn bong trdc be mat canh va hien tifdng eong gay canh trdn.
Ve hien tUdng mdn cua canh trpn la stf ket hdp gitfa mdn hod hoc va mdn cd hoc.
- Mdn hoa hpc: Hien tifdng nay la do trong qua trinh lam viec, cdnh trpn se tiep xuc vdi cac chat long, phu gia hod chat, dan den dn mdn. Thdng thifdng trong cdng nghe be tdng thi stf an mdn nay la khdng dang ke so vdi mdn cd hpc vi be mat cdnh trpn tiep xuc vdi khdi lifdng Idn hat mai (cat, da), khi dd cdc hat mai se tnfdt Ien nhau va tnfdt di.
- Mdn cd hpc: La dang mdn do cac tac dung cd hpc cua hat vat lieu tnfdt Ien be mat canh trdn trong qua trinh trdn. Cac ltfc ma sdt sinh ra tren canh trpn se tdc ddng lam cho be mat canh trpn bj bong trdc din de'n phd huy be mat nhanh ehdng. Mpt so' hien tifdng phd huy be mat nhif:
-I- Stf phd buy be mat do mdn trdc
Ttf sd do Hinh 4, do dp Itfc Q, cua vat lieu tac dung vudng gdc vdi cdnh trdn se sinh ra ma sdt tru'dt (Fms) tren be mat cdnh trdn, ma sat nay se phd hdng mdi lien ket gitfa cdc phan ttf kim loai tren be mat cdnh trpn, do tdc dpng cua tai trpng Idn (dp suat cue bp cao) ma be mat cdnh trdn bj bien dang deo manh gay hien tifdng bong trdc ldp be mat.
-1- Stf pha buy be mat do nhiet
Do anh hu'dng cua ma sat tnfdt lam nhiet dp tren be mat cdnh trdn tdng ddng ke hinh thanh cdc mdi lien ket cue bd, gay bien dang deo rdi phd hong mdi lien ke't ay (qua tai nhiet).
Ngoai cdc dang hif hdng do mdn thi cdn cac dang hU hdng khdc cong gay dd la do dtfdi tdc dpng cua cdc Itfc W|, W_|, tai trpng thay ddi lien tuc trong qua tnnh trpn life va dap Idn sinh ra cdc vet ntft te vi, cdc vet ntft nay la nguyen nhan gay ntft gay cdnh trpn.
3. Ket luan
Qua nghien ctfu mdt sd' dang hif hong cua canh trpn trong cdi trpn be tdng hai true ngang tdc gia difa ra mdt sd bien phdp nham cai thien difdc chat lifdng giam hU hdng eua canh trpn nhif:
- Tdi lfu cdc thdng sd'hinh hpc cho cdnh trdn nhU: gdc nang cdnh, bien dang profin cua cdnh, gdc nghieng,...
- Bd' tri vi tri cdc cdnh hdp If nham giam cdc ltfc va dap trifc tiep len be mat cdnh.
- Stf dung cac vat heu cd tinh chiu mai mdn va chiu va dap cao hdn. •
Tai Mu tham khao:
11] Bao cao Khoa hoc CT2500 ngay 29-11-2005, Vien may va Dung cu cong nghiep.
[2] TS. Nguyen Thieu Xuan, PGS.TS. Tran Van Tuan, KS. Nguyin Thi Thanh Mai, ThS. Nguyen Kiem Anh (2000), May san xuat vat lieu va cau kien xay difng, NXB. Xay Diing, Ha Noi.
[3] Pham Duy HiJu, Ngo Xuan Quang (2001), V|t lieu xay dung, NXB. Giao thong Van tai. Ha Npi.
[4] Trinh Chat, Le Van Uyen (1998). Tinh to4n thiei ke he din dong cd khi (tap 1, 2), NXB. Gi^o dtjc, HS Noi.
15] Ho Le Vien (2003), Cac may gia cong vat lieu riSn vi deo (tap 1, 2), NXB. Khoa hoc FG thuat. Hi Npi.
[6] Tran VSn Djch (1994), Cong nghe che tao miy, NXB.
Khoa hpc va Giao dijc. Ha Noi.
[7] TS. Tran Quang Quy, TS. Nguyen Van Vjnh, TS.
Nguyen Binh (2001), May va thiet bi sdn xuai vat li?u xay difng, NXB. Giao th6ng Van tJi, Hi Npi.
^ TAP CHi C d KHi VIET NAM • ^'' 1 o - "iliang S nSm 2009
