S BAN CnC vlfl Dd Dd'c

KHOA HOC VA CdNG NGHE MO CNM

LUA CHON MAT BANG CHIEU THICH HOP KHI T H A N H LAP BAN DO MO TRONG CnC vlfl CO Dd Dd'c L 6 N

S

an dd md la tu lipu dd hpa, tren dd md ta hien trang hp thdng khai thac, dilu kipn va thanh phan t h i nlm cua via khoang san, cac thdng tfn ve dja chat cau tgo va kiln tgo. Ban dd md la phuang tien CO ban phyc vy mpi hoat dpng chuy§n mdn ky tfiu$t va quan ly tf-ong suot qua trinh tCr tham dd. xSy dyng, khai thac va k i t thCic md. Ban dd md vdi cac tiidng tin dupc cap nhat day du, tmng thye va chinh xac ddng vai trd quan trpng cho mpi hoat dpng san xuat md dung ky thuat, hipu qua va an toan.

Be tiian Quang Ninh cd dilu kipn dja chat phCrc tap. Hau hit cac via than trong c:ac md ham Id Idn cua Viet Nam nhu Vang Danh. Ha Lam, Mdng Duong, Khe Cham... d i u cd dp ddc Idn. Cho d i n nay, khi thanh lap cac loai ban dd dja chat, khai thac cac cdng ty md diu chpn mat phlng chilu nlm ngang. Ddi vdi cac via ddc va he thdng dudng Id trong via ddc, khi chilu len mat phlng nlm ngang cac thanh phan hinh hpc cua chung se bj biln dang. Trong cac trudng hpp gdc doc cua via rat Idn, cac hp thdng dudng Id d cic mCre dan ch6o len nhau, ban dd tra nen tiiilu mach lac, sai sd Idn va rat khd sCr dung k l ca cho cac can bp chuy§n mdn ky thuat va cac can bp quan ly. Trong cac tnidng hpp dd can tiianh lap ban dd via va hp thdng dudng Id trong ca m^t chilu dung ho^c chilu nghidng. Tuy vao cac dieu kipn t h i nlm cua via can lya chpn mat phlng chieu hpp ly bao dam cho ban do dupc xay dyng chinh xac, tmng thye.

1. Li^a chpn mat phang c h i l u thich hp'p thanh lap ban dd cho cac via ddc

Kit qua nghi§n cu-u [1, 2, 3, 4] cho thiy ring: ddi vdi cac via cd gdc ddc a S40° m$t chilu dCrng song song vdi dudng phuang via cho sy biln dang it nhat.

Tnidng hpp tdt nhat la su' dyng m$t phlng chieu nghieng di qua dudng phuang va gdc ddc tmng binh.

Can luu y ring: khi xay dyng ban dd tren m§t chilu dCrng hay m$t chieu nghidng deu phai dya vao kit qua sd lipu trie dia do ve tCr cac mgng ludi dilm khdng c h l ham Id. Ngoai ra, tpa dp cac dilm nay cung dugc tfnh chuyin trong mpt he tpa dp phy.

He tpa dp thanh lap ban do tren m§t phlng thing dung dupe xay dyng sao cho:

PGS.TS. VO CHI My Tru&ng D^i hgc Mo-Dja chat

• Tpa dp X', Y' cua t i t ca cac d i l m trong pham vi ranh gidi md deu mang dau duang. Mudn vay, can tfnh tfin hp trye X', Y', Z' gia tri a dpc theo trye X va gia trj b dpc theo trye Y

• Mat phlng chilu chCra trye X', Z' song song vdi dudng phuang cua via (y). Dieu kien nay thoa man khi quay he trye X', Y', Z' sao cho gdc phuang vj trye X' trong hp trye X, Y, Z dat gia trj bing phuang vj dudng phuang (y).

Trong trudng hpp thanh l$p ban dd tren mat chilu nghieng, he trye X', Y', Z' phai nghieng so vdi trye X' sao cho tren m^t chilu X", Z" chua cac thanh phan t h i n l m cua via dung bing cac thanh phan t h i n l m da xac djnh tr§n ban do dja chat.

Neu cac thanh phan t h i n l m cua via dai dipn bing phuang vj dudng phuang y va gdc ddc 9, thi tren m^t chieu X", Z" cung chCra cac d?i lupng y va 9.

H.1. Nguydn ly xay dung m^t phang chiiu dirng va chieu nghieng cho cac via ddc.

Tpa dp cua mdt d i l m A bat ky trong he trye X, Y, Z se dugc tinh chuyen sang he trye X', Y', Z' nhu sau: X'A=(YA-b).siny+(XA-a)cos y;

Y'A=(YA-b).cosY-(XA-a)sinY;Z'A=ZA.

Ban dd tren mat phlng chilu dung se dugc thanh lap tu cac tpa dp X', Z'. Tga dp cua mdt diem

CdNG NGHIEP MO Sd 2 - 2008

CNM KHOA HOC VA CdNG

N G H £ M 6 A bat ky trong hp tnjc X', Y'. Z' se dugc tinh

chuyen sang hp true X", Y", Z" theo cdng thCrc:

X"A=XA; Y"A=Y'A.sinY-Z'A.cos y;

Z"A=-Y'A.cosY+Z'A.cosy. Hoac:

X"A=(YA-b).sinY-(XA-a).cosY;

Y"A=[(YA-b).cosY-(XA-a).sin Y)].sin9-ZA.cos9;

Z"A=-[(YA-b).cosY-(XA-a).sinY)].cos9+ZASin 0.

Ban do tren mat phlng chilu nghieng se dugc thanh lap tCr cac tpa dp X", Z".

H.2. Nguyen ly thanh l$p bim dd md trong m$tphing chieu dung. Trudng hgp dudng phuong it bien doi,

X'

H.3. Nguyen ly thanh l$p bin dd md trong m^tphing chieu dimg. Tru&ng hgp dudng phuong bien ddi m^nh.

Trong thye t l , nhieu via khoang san cd dudng phugng thay doi, vipc lya chpn m§t phlng chilu can dya vao sy biln doi cua dudng phuong. Hinh H.2 minh hpa tardng hgp via cd phugng vj dudng phuang thay doi tir YI ^^n Y2 • Gdc quay cua hp trye Y dugc nhgn bing gia trj trung binh cua cac gdc phuang vj dudng phuang neu tai mpt dilm b i t ky cua via hipu (Yi-^)^9max- Tai dSy: 9 max - Bp ddc Idn nhit cua via. Trong trudng hgp dudng phuang bien doi mgnh (H.3), c i n phai tflp nh$n cac m^t phlng chilu rieng bipt cho tung canh. Tn,ic

Z'l cua he trye phy se la dudng ngoat cua ban dd, se bao gdm hai phan. Tren mat chilu Z', X' t h i hien mpt canh via, tren mat chilu Z'l, X ' r t h i hien canh via thCr hai. Nhan gdc hp tga tga do phy X", Y", Z" n l m tren trye X', do vay cd the tinh chuyin tga dp theo he true X',Y',Z' hoac trye tflp theo he trye X.Y.Z. Hinh H.4 trinh bay nguyen ly xay dung ban dd than quang cd gdc nghieng biln ddi.

90-Y

X X

^y' y / A ^

< I y

Y YV

\t

1

1 Y"'—V"

^ ^ ^ „

^ t y

H.4. Nguyen ly thanh lap bin dd trong m§t chieu nghieng.

H.5. Hinh chieu c^nh dudng chuyen da giic tren m§t phing dirng.

Qua tfinh do ve he tiidng dudng Id tfiong cac via doc cung cd nhCrng diem luu y rieng.Trong tfiidng hgp cac diem dudng chuyin da giac ham Id bd tfi tiBn ndc Id, cgnh dudng chuyin tfien hinh chilu dCrng se dich chuyin mpt dai lugng (hinh H.5). Cac gia tfi hoanh dp se dupc hipu ehlnh tfien m$t phlng dung tiieo cdng tiiCrc:

io=(l.sinp). (1) Trong dd: 3 - Gdc nghieng canh dudng chuyen da

giac h i m Id.

2. Kit lu|in

Ddi vdi cac via khoang san cd dp ddc Idn, c i n (Xem tiip trang 8)

CdNG NGHIlP MO Sd 2 - 2008

CNM

KHOA HOC VA CdNG NGH£ MO

Neu luc cang trong day bang Idn thi chieu dai chuyen tie'p cung phai Idn theo. Ke't qua nay phu hdp vdi thuc te lam viec cua bang tai d'ng.

Tren day la ke't qua xac dmh bang ly thuyet. Khi tfnh toan thie't ke bang tai d'ng nen lay chieu dai chuyen tie'p tang them mdt IUpng tU 20 % den 30 % de ke de'n cac sai so do ly thuyet. do che tao, lap dat va ke den dieu kien van hanh cua bang tai d'ng (co gian do nhiet dp, che dp van hanh bat thudng khi khdi ddng va phanh ham...). Mat khae, d vj tri gan ket thue cupn bang, chung ta eung khdng the cung mdt luc eudn ca hai mep bang ma phai eudn thCf tu lan lupt tUng mep bang. Do dd, nen chpn chieu dai chuyen tiep theo cdng thCfc sau:

ktmin=(0,&^0,65).D 4+{n+(pf

[ £ ] - - [£]- ^+2

(15)

2. Ket luan

Cac cdng thCfc da dUdc xac lap b tren eung cap cho ngudi ky sU thiet ke cd sd de tf'nh toan thiet ke, lua chpn thdng so hinh hpc hpp ly cho tram nhan/dd tai eCia bang tai d'ng va tuye'n bang. Vdi yeu cau ve nang suat van chuyen, dCf lieu ban dau va dac tfnh ky tfiuat cCia cac loai day bang cd sin, ta ed the xac djnh dupc chieu dai can thiet doan chuyen tiep cudn-md bang. Hoac ngUdc lai, ta cd the chpn tnidc cac gia tri hinh hpc neu tren va tU dd tfnh toan xac djnh ra loai day bang cd dp gian dai tUdng dd'i cho phep phu hpp.n

TAI LIEU THAM KHAO

1. Nguyen Van Khang. May va td hdp thie't bj van tai md. Nha xua't ban Khoa hoc va Ky thuat. Ha Ndi. 2005.

2. Nguyen Van Khang va nhu'ng ngudi khac.

Nghien cCfu, thie't ke bang tai d'ng de van chuyen vat lieu rdi, tdi vun. De tai cap bd ma sd B-94-18- 6a-37'. Trudng Dai hpc Md-Dja Chat. Ha Ndi. 1995.

3. Nguyen Xuan Luu. Ly thuyet dan hdi. Nha xua't ban Giao thdng Van tai. Ha Ndi. 2004.

4. Le van Minh, Nguyen Van Vupng. SCfc ben vat lieu. Tap I. Nha xua't ban Giao due. Ha Ndi. 1995.

5. HCfa Ngpc Sdn. Nghien eCfu xac dinh mdt sd thdng sd cd ban cCia bang tai d'ng dung eho van tai md Viet Nam. Luan van Thae sy Khoa hpe Ky thuat. frudng Dai hpc Md-Dia chat. Ha Ndi. 2006.

Ngudi bien tap: Dao Die Tao

SUMMARY

The paper suggests study results of method estimating transition length for pipe conveyor according to allowing relative slackening level of conveyor belt. These study results are able to give a help in calculating and, choosing likely geometry parameters for load-unload station.

Lim CHON MAT BANG CHIEU...

(Tiep theo trang 18)

phai tfianh lap tfiem ban dd tren hinh chieu du-ng va hoac hinh chidu nghieng. Viec lua chpn cac mat phlng chieu phu thupc vao cac yeu td the nlm cua via ma dai dien la phu'ang vj dudng phuang y va gdc ddc cua via 9. Cd them cac loai ban dd tf-ong mat chieu du'ng va mat chieu nghieng, hien trang vfa va hp tfldng dudng Id khai thac trong via duac t h i hien day du han, rd rang han, ho trg cho cac bd phan chuyen mdn nghiep vu ky thuat tdt han, bao dam eho cac hoat dpng san xuat md duac hieu qua va an toan. Vdi sy trp giup cua cac phan mem dd hpa hi^n nay. cdng tac thanh lap cac loai ban dd md cho cac via ddc tf-en cac m$t chilu du'ng va chilu nghieng dupe tu dpng hda bao dam nhanh chdng va chinh xac.O

TAI LIEU THAM K H A O

1. Nguyin Dinh B6, Vd Chi My, Nguyin Xuan Thgy. Trie dja md. NXB GTVT. Ha Npi. 1999.

2. Nguyin Xuan Thuy. Hinh hpe md. NXB GTVT, Ha Npi. 2002.

3. Alderspn J. S. Applieatfon of computer graphics to mine surveying and planning.

Nottingham, UK. 1982.

4. Rajnich R. Siembab J. Sosna A. Mapy gornicze, Wyd. "Slask". Katowice. 1986.

Ngu&i bien tap: Dao Dac Tao

SUMMARY

For the highly-inclined seams, mapping on projection horizontal plane is able to deform measures components of seam. To fidelity,

\ accurately and visibly reflect measure's component : of seam and gallery system in highly-inclined

! seams, need to build map kinds addition in inclination vertical iDrojecting plane or inclined projection with likely plane of projections.

CdNG N G H I £ P MO Sd 2 - 2008