Xây dựng mô hình tính toán độ mất cân bằng của đầu đạn súng bộ binh

Trudng hgp neu khdi tam eua dau dan lech ra khdi true dan, true dan trimg vdi true ndng sung thi; Khi dan chuyen dgng trong ndng, dau dan hi cudng ep chuyen ddng, true quay trung vdi tru

NGHIEN C O U - T R A O D O I

XAY DUNG MO HINH T I N H TOAN O p MAT CAN BANG

CUA DAU DAN SUNG BO BINH

A NUMERICAL MODEL OF BULLET-HEAD UNBALANCE

Nguyen Thanh Dien Hge vien Ky thuat Quan su TOM TAT

Bdi bdo dua ra mo hinh tinh todn do mdt cdn bdng eUa ddu dan siing bg binh dua tren

phuang phdp md phdng Monte Carlo Ap dung mo hinh vira xdc lap de khdo sdt dnh huong cua cdc

sai sd gia cong cung nhu quy trinh cong nghe sdn xudt ddu dgn din do mdt cdn bdng cua no Tinh

todn CM thi duac dp dung cho ddu dgn 7,62x39mm

Tir kh6a: Mdt cdn bdng, cdn bdng dgng, ddu dgn, ngdu nhien

ABSTRACT

The paper presents a numerical model for simulating the unbalance of bullet head The

model is based on the Monte — Carlo method and applied to investigate the influences of manufacture

errors and technological factors on the bullet unbalance The analyzing results for 7,62x39mm bullets

is shown as an example

Keywords: Unbalance; Dynamic balance, equilibrium, bullet head, randomness

1 DAT VAN DE va anh hudng Idn den do can bing cua dau dan

Den luat minh, dd mat can bing cua diu dan lai

Khi thilt kl va san xuit diu d^n, ngudi |^ ^^i trong nh&ng nguyen nhan quan trong gay

ta ludn mong mudn cac phan tu ciia dau dan la „ i,;s„- .• -* ^ • * • •

, , ^ ra men tuong tan mat duone dan va cang quan

cac v^t CO cung true quay, hue doi xung hmh , ; , , ,

!,«„ ,A 4R 1, T u-" ^ ' <_• L • trgng hon doi vai cac sung bo binh do chung CO

hoc va dgng hoc, Tuy nhien, trong qua trinh gia * • , cdng, chi tao luon ludn tdn tai sai sd giira kich "^oi Jugng tuong ddi giua dan va sung Idn Dieu

thudc thilt kl so vdi kich thudc thue t l (hay ^^ ^^^ ^^^ su can thilt phai xay dung md hinh

cdn ggi la dung sai) Sai s6 gia cdng eae phin tinh toan do mat can bang cua dau dan, trong do

tir ciia dau dan la dai lugng ngau nhien sinh ra md ta dugc moi quan he giiia dung sai chi tao

mdt each khach quan trong qua trinh san xuit diu dan va do mit can bing cua nd

NGHIEN CUfU-TRAO D 6 I

2 ANH HlTONG CUA DQ MAT CAN BANG

DAU D^N DEN CAC THAM SO CHUYEN

DQNG CUA NO

Khi dau dan hi mat can bang se gay anh

hudng den chuyen ddng ciia dan Trudng hgp

neu khdi tam eua dau dan lech ra khdi true dan,

true dan trimg vdi true ndng sung thi; Khi dan

chuyen dgng trong ndng, dau dan hi cudng ep

chuyen ddng, true quay trung vdi true ndng

Sling, khdi tam G ciia dan chuyen ddng xung

quanh true ndng sung gay luc ly tam ep thanh

ndng lech ve mgt phia tao dao dgng ciia ndng

Sling va lam giam do ehinh xac cua phat ban;

Khi dau dan rdi khdi ndng, dau dan cd xu hudng

chuyen chuyen ddng quay trd ve khdi tam cua

dan, dan quay quanh khdi tam lam dan bi lac va

lech khdi quy dao theo thiet ke, tang lire can eiia

dan so vdi binh thudng dan den tim ban giam

va tang tan mat Khi dan rdi khdi ndng, van con

van tdc theo phuang tiep tuyen do viec cudng

ep khdi tam chuyen ddng quanh true ndng siing,

dan ed xu hudng chuyen ddng ra xa so vdi quy

dao ban dau theo thiet ke

Theo [7, tr 133], do lech quy dao cua dau

dan cd the duge tinh theo cdng thuc:

Trong do:

o: Do lech ciia dau dan hay con ggi la

ban kinh tan mat, inch;

V: Van tdc ban dau cua dan, ft/s;

t: Budc xoan cua ranh ndng, inch;

TOF: thdi gian bay cua dau dan (0,1 s d

khoang each 100 yard);

6: Do lech tam, inch

Trudng hop diu dan mat can bang do khoi lugng ciia diu dan khdng phan bd ddi xung qua true dan thi trgng tam dan van nam tren true dan theo thiet ke, nhung do su phan bd khdng ddi ximg nen cd nhiing phan khoi lugng "du thira" nam lech ra khdi true dan Nhu hinh 2 la trudng hgp gay ra anh hudng Idn nhat, hai phan khdi lugng du thira nam lech nhau mdt gdc 1800 tren phan vd dau dan Khi dan chuyen dgng trong ndng, khoi lugng nay gay ra hien tugng dao ngoay tang ap luc cua dau dan len thanh nong Khi dau dan rdi khoi ndng, hien tugng dao ngoay tang len do khdng bi can trd cua thanh ndng Hien tugng nay lam giam tam ban va tang tan mat cua phat ban [1], [2]

Hinh I: Tdm dan khdng trimg vai true dan

Hmh 2 Mdt cdn bdng do khdi lugng phdn ho

khong doi xung

Mat can bang dau dan la mdt trong nhimg yeu td anh hudng rat Idn den tan mat cua dan Khi giam do mat can bang dau dan thi do chinh xac phat ban dugc tang len De nang cao

do chum, can phai chii y den cac bien phap cong nghe nham giam toi da do mat can bang ciia dau dan Tuy nhien, dieu nay dan den su can thiet phai nang cao tinh cong nghe trong san xuat, khdng cd lgi ve mat kinh te

3 MO HINH XAC DINH DO MAT CAN BANG CUA DAU DAN

Dung sai do lech tam eua dau dan dugc xac dinh tir cac dung sai da xac dinh trudc do cd phan bd ngau nhien trong gidi han true hinh hgc cua cac phan tu theo mat ngoai va bl mat trong than vd dau dan, vat nhoi, dai dan va cae phin tu khac lap rap vdi than vd, vdi cac phin tu ciia diu

dan: 6c dau, ngoi dan, ^

ISSN 0866 - 7056

TAP CHf CO KHf VIET NAM, Sd 3 nam 2015

www.cokhivietnam.vn

NGHIEN CIJfU-TRAOD6l

Do gia tri cua dung sai so vdi cac kieh

thudc diu dan la nhd, nen dau dan cd the dugc

bilu diln nhu tren hinh 3 theo cac phan hi co do

can bang Idn (true ddi xung ddng hge triing vdi

dudng tru) va cac phan tii cd do khdng can bang

nhd Phin khdng can bang dugc tap trung vao

2 khii lugng phu dat tren cae mat phang vudng

gdc vdi dudng tru dau dan, mdt di qua chinh

giira dai dan, mdt di qua ehinh giiia dai dinh tam

va chiing each true dan mdt khoang bang ban

kinh dau dan (mgt nua cd dan)

Nhu vay, trong trudng hgp nay do khdng

can bang ddng cd the dugc dae tnmg bdi 2 khdi

khdng can bang tuang ung DI, D2 va gdc xen

giiia ehung a

Trong do: £>, = m, —\D.^ = m^ —

m^,m-^- Khdi lugng khdng can bing;

Cac dai lugng can bang khIi lugng va

hudng tac dung ciia nd dugc xac dmh bang thuc

nghiem tren cac thiet hi chuyen dung

:^'=^-sai sd vi tri cae be mat xay ra trong qua trmh gia cdng cong nghe khi san xuat chi tao diu dan Mdt sd lugng Idn nghien cuu cho thiy sai s6 vi tri cac be mat trdn xoay (dac trung cho qua trinh che tao dau dan) phan bd theo quy luat Role-Reix, edn trong trudng hgp khdng cd cac thanh phan sai sd uu the - sai sd vi tri cdc be mat phSn

bd theo quy luat Rale

Cac dai lugng ngau nhien D,, D^ va a

ciing cd the xac dinh trong mdi Ian thuc hi?n tdng hgp cac qua trinh bang phuong phap thu nghiem tinh bang each cdng cae khdi khong can bang thanh phan xuat hien do dich ehuyen (do lech) true cac be mat trdn xoay cua dau dan: D^ = X - ' ^ x ' Trong dd D^^^- Khdi khdng can bang d=taat phang quy ddi thd x xuit hien do dich chuyen true mat phang thu i cua ehi tiet thii j Cach tiep can nay cho phep tinh eae thong

sd khdng can bang dgng va khi dd cho phep tinh den cac diem dac biet cong nghS san xuat dau dan bang each tinh den mdi quan he giiia gia hi

do lech vdi hudng tac dung ddi vdi b l mat dugc gia cdng bang mgt thilt bj N I U bilu diln bl mat cac chi tilt trong dang hinh ndn hoac hinh tt^ trong sd nay ke ca chiing dugc lam gin diing vao cac be mat dinh hmh, thi ban kinh hien thdi cua b l mat ehi tilt r(x) va do dich chuyin ciia

nd C^(x) dugc xac dinh bing eae ham tuyIn tinh

trong dang:r = a|X-l-a2;^ = a3X + a4, con cac khdi khdng can bing thanh phin eiia cae phin hi nay se dugc xac dinh bing da thuc bac 5 do ong N.V Mogilnhicovui tim ra:

D,,=Oo[aiH

Hinh 3 Sa dd tinh todn do cdn bdng khdi lugng

vd huong tdc dung cua chung

Gia tri nglu nhien cua eae thong sd

khdng can bing dgng D,, D^ va a phu thudc vao

+ 04+x,_Jbj+b, + bj+b5)] (2) Trong dd:

_7r.p,.k„(2.^-3)

cj, = 0 , 2 a f a J x

NGHIEN ClJU-TRAOOCi

O2=0,25.[2a,.a,.a3+af.a4.(x^-x^)

7,62x39mm Can phai su dung mdt sd gia thiet:

- Coi vat lieu cua cae phan tu dau dan la đng nhat;

CT4 -0,5.a2.a4.^x^ "X^J; - Qua trinh dap ao ehi vao ldi thep chi cd b2=-0,25af.a3.(x^-xM; ao chi bi bien dang theo be mat trong ciia khudn

"' h '

"'- h

h

Vai: kn = 1

kn = -l

pi:

•"„

' " h

- Doi vai be mat ngoai;

- Doi vai be mat trong;

- Mat do v£it lieu cua chi tiet ttiii i;

b, =-—PaiEjEj +ajâ(xj -x^„)J; - Qua trinh tdng lip diu dan chiiu day

cua vd dau dan khdng thay đi ma chi ed be mat

P / \"t ngoai cua no bien dang theo be mat trong cua b4=-0,5.|^a2.a3+2a,.d2.d^(x,,-XH)J; khudn dap cdn ao ehi bi biln dang chi dl diln

b =-ậa (x -X )• day khdng gian ben trong vd, ldi thep khdng bi

bien dang

r , - r „

Theo phuang phap tinh da neu d tren va quy trinh san xuat dau dan 7,62x39 mm [5], tien hanh chia cac be mat dan siing theo nhimg mat nhd Phan hinh cac phan tu dau dan dugc thuc hien theo nguyen tac: mdi be mat tru hoac be mat cdn dugc chia thanh I phan hinh, cac be mat cong (phan dau cua ao chi va vd dau dan) duge phan chia thanh cac phan hinh co chieu dai du nhd de cd the coi mdi phan hinh đ la mgt mat cdn Cu the:

Xjj, Â, r , r^ va ^^, ^^ - Toa do, ban kinh,

do lech tren thia dien ban diu va cu6i cung cua " L5i thep dugc phan chia thanh hai phan

bl mat trdn xoay dugc bilu diln dudi dang hinh hinh la phan tru va phan con;

ndn, hinh tru;

- Ao chi: Mat ngoai dugc phan chia thanh X,, x^ - Toa do be mat quy đi cac khdi 9 phan hinh; Mat trong dugc chia thanh 2 phan khdng can bang ^^"^ ^h^° ™^* ngoai cua ldi thep

YIU td quan trgng khi xac dinh khdi - Vo diu dan: Mat ngoai dugc phan chia khdng can bing la dae trung (diu hieu) phu thanh 15 phan hinh; Mat trong duge phan chia thudc cua do dao (lech) cac bl mat Dae trung thanh 10 phan hinh trong đ 9 phan hinh theo bl nay phu thugc vao trinh tu cdng nghe san xuit mat ngoai cua ao chi va I phan hinh d phan ldm chi tao than vd diu dan day dan

Dudi day se trinh bay each xac dinh do Sii dung dii lieu dau vao tir [5], cac mat mit can bing ciia diu d?n siing tieu lien AK phang can bang tinh toan nhu hinh 4 ^

ISSN 0866 - 7056

TAP CHf CO KHf VIET NAM, Sd 3 nam 2015

www.cokhivietnam.vn

NGHIEN ClJfU - TRAO DOI

Lap trinh tinh toan cac dai lugng mat can

bang theo cdng thuc (2) rdi tdng hgp lai, trong

do sir dung phuang phap md phdng Monte Carlo

de md phdng ngau nhien gia tri dung sai cac be

mat Ket qua tinh toan vdi n = 1000 vien, nhan

dugc: ky vgng toan Dj = 0,0624g.mm; D, ^

0,0083g.mm;a=174,6°

Hinh 4 Vi tri cdc mat phdng tinh mdt cdn bdng

De kiem chiing tinh dung dan cua md

hinh tinh toan do mat can bang cua dau dan

da thiet lap d tren, can thiet phai tien hanh thi

nghiem de so sanh ket qua tinh toan ly thuyet

vdi thuc nghiem Thi nghiem xac dinh do mat

can bing ddng cua diu dan siing 7,62x39mm dugc tiln hanh tren may do mat can bing CEM cua Vien Ten Iiia, Vien Khoa hgc va Cdng nghe Quan sy Tien hanh do 30 mlu diu dan, mdi miu

do 3 lin Kit qua do dugc ghi lai va sau khi sir ly

sd lieu nhan dugc: ky vgng toan D, - 0,0609g mm; D^ - 0,0072g.mm; a= 172,4°

So sanh kit qua tinh toan ly thuylt vdi thuc nghiem thiy ring do khdng can bing ddng ciia diu dan khac nhau khdng nhieu

4 KET LUAN 1) Bai bao da xay dung dugc md hinh

md phong tinh toan dd mat can bang ddng ciia diu dan can cu theo quy trinh cdng nghe va dung sai chi tao cac chi tilt thanh phan va tdng lap dau dan

2) Da tiln hanh thuc nghiem do dac dugc

do mat can bang ddng cua mdt sd mau dau dan 7,62mmx39 (K56) Kit qua so bd ban dau da cho thay su pbii hgp giiia md hinh ly thuyet va thue nghiem.•

Ngay nhan bai: 11/02/2015

Ngay phan bien: 20/3/2015

Tai lieu tham khao:

[1] Le Minh Thai, Hieu qud bdn, NXB Quan dpi nhan dan, 2002

[2] Mai Quang Huy, Anh hudng ciia kit cdu dan phdo den chi so lan mdt, Luan an Tien sT, Hgc vien Ky

thuat Quan su, 2005

[3] Le Cung, Nguyin ly mdy, Trudng Dai hgc Bach Khoa Da N5ng, 2007

[4].NinhDiicT6n, Di/ng 5a//dp g/iep vd ky thudt do luang,'NXB Giao due, 2006

[5] Ting cue CNQP, Cong ty CKHC - 13, Quy trinh sdn xuat ddu dan 7,62x39 mm, Z113 2012

[6] Fapojibfl P, Born, Oaicropbi TOTHOCTH BHHTOBKH, MautecTep, KoHHeKTUKyx, CUIA