8/2/2019 DO GA

1/6

TNH TON CH CT CHO NGUYN CNG KHOT

DOA.

1. Chiu su ct khot th t = 3,6 mm

2. Lng chy dao: S = 2 mm/vg3. Tc ct:

V = vyxmq

V kStT

DC

..

.

Trong : Cv v cc h s tra bng (5-29)[2]:

Cv = 105,0 ; q = 0,4 ; x = 0,15; y = 0,45; m = 0,4

T Chu k bn tra bng ( 5-30) [2]. T = 100

kv H s iu chnh chung cho tc ct tnh n iu kin thc t:

kv = kMV.kuv.knv

- kMV H s ph thuc vo vt liu gia cng tra bng (5-1)[2].

kMV = 1

- kuv H s ph thuc vo vt liu dng c ct tra bng (5-6)[2].

kuv = 0,83

- knv H s ph thuc vo chiu su ct tra bng (5-5)[2]. knv = 1.

kv = 1.0,82.1 = 0,83

Vi D = 172 mm

)/(40,6583,0.2.6,3.100

172.10545,015,04,0

4,0

phmV =

S vng quay tnh ton : phvgD

Vn /(09,121

172.

40,65.1000

.

.1000===

Chn s vng quay theo my: nm = 125 (vg/ph)

Vn tc thc t : )/(54,671000

172..125phmV ==

4. Momen xon Mx (N.m) v lc chiu trc Po (N)

- Momen xon: Mx = 10.CM.Dq.tx.Sy.kp

Cc thng s tra bng (5-32)[2]. CM = 0,196 ; q = 0,85; x = 0,8; y = 0,7;

kp = 1. Mx = 10.0,196.1720,85.3,60,8.20,7.1 = 705 (N.m)

8/2/2019 DO GA

2/6

- Lc chiu trc: Po = 10.Cp.Dq.tx.Sy.kp

Cc thng s tra bng (5-32)[2]. Cp = 46 ; q = 0; x = 1; y = 0,4; kp = 1.

Po = 10.46.1720.3,61.20,4.1 = 2185 (N)

5. Cng sut ct Ne (kW)

04,99750

125.705

9750===

nMN xe

Vy Ne < Nm = 10 (kW)

TNH TON THIT K G KHOT DOA

Ta bit rng g l ni chi tit c g t v kp cht chi tit trong sut

qu trnh gia cng c. N c tc dng m rng kh nng cho my ct gt, ng

thi rt ngn thi gian gia cng chi tit to iu kin tng nng sut trong khi

cht lng ca sn phm li ng u theo yu cu k thut ra.

I. Phn tch s v kt cu g.

1. Phn tch nh v :

- Mt y chi tit t ln phin t c nh khng ch 3 bc t do.

- Vnh trong ca l np Bulong c nh v 1 bc t do nh cht chm.- Vnh trong ca l np Bulong c nh v 2 bc t do nh cht tr ngn.

2. Kt cu g:

Thn g c ch to bng gang c phay rnh bt bulong ln trn

bn my, pha di y c lp then dn hng, trn g c khoan cc l

n bt vt ca phin t, cht nh v, bulong ca c cu kp cht. Ngoi

ra cn khoan cc l bt bulong ca g khoan ln thn g.II. Tnh lc kp cho c cu:

Chi tit c gia cng ln lt cc l vi lng d t = 8.3 mm

y ta ch tnh lc kp cho c cu trong trng hp khot th: P o =

2185 (N)

Trong qu trnh ct gt cc thnh phn ca momen ct nh hng n v

tr ca chi tit l:

8/2/2019 DO GA

3/6

- N lm cho chi tit lt ti im A. Mun chi tit khng b lt ti A th

momen mt ca lc kp phi cn bng vi momen ct.

Ta c phng trnh tnh cn bng:

121 )..(...

2RffWRKMd x +=

dRff

RKMW x

.).(

...2

121 +=

Trong f : H s ma st. Ly f1 = f2 = 0,25

d : ng knh dao: d = 0,172 m

R1 : Khong cch t v tr kp n im A : R = 0,83 mR : Khong cch t tm dao n im A:

R = 593,0265,053.0 22 =+ m

- k : H s an ton v c xc nh:

H s an ton k c tnh nh sau: k = k0.k1.k2.k3.k4.k5.k6

Vi: - k0 : H s an ton ly cho mi trng hp k0 =1,5

- k1 : H s an ton k n lng d khng u khi khoan k1 = 1- k2 : H s an ton k n dao cn lm tng lc ct k2 = 1,15

- k3 : H s an ton k n lc ct khng lien tc k3 = 1

- k4 : H s an ton k n ngun sinh lc, ta dng ngun sinh lc bng tay

nn ly k4 = 1,3

- k5 : H s an ton k n v tr tay quay khi kp ly k5 = 1

-k6 : H s an ton khi tnh n tnh cht tip xc ly k6 = 1,5

Vy h s an ton : k = 1,5.1.1,15.1.1,3.1.1,5 = 3,364

Momen xon trong qu trnh khoan l: Mx = 705 ( Nm )

Lc chiu trc trong qu trnh khoan l : P0 = 2185 ( N )

)(19700172,0.83,0.1

2.593,0.364,3.705NW ==

- Lc chiu trc Po lm cho chi tit b x dch v vy trnh xa dch thlc kp v trng lng phi ln hn Po

8/2/2019 DO GA

4/6

Ta c: W + G = Po => W = Po G = 2185 -224.10 < 0 Vy lc chiu trc

khng lm x dch chi tit.

Nn ta ch xt n W khi chng lt

- Tra bng (8 30) [2] chn thanh kp trt kiu IV

- Chn chiu di thanh kp L = 200 mm, khong cch t bulng ti m kp

l = 100 mm. Ta c s lc xit bulng sau:

L

W

Q l

Ta c phng trnh:

W/4.L = .Q.l..4

.

l

LWQ =

Trong : = 0,95 : H s gim lc kp do ma st

Chn 2=lL

=> )(1036824.95,019700

.

.N

l

LWQ ===

ng knh bulong :

[ ].4 1Wdo =

Trong : [ ] MPa80= v W1 =W/4 = 4925 N

[ ]mm

Wdo 85,880.

4925.4

.

4===

Ly theo chun d = 10 mm

Kim nghim Bulong theo bn ct:

HdQc ...

= [ ]c

8/2/2019 DO GA

5/6

Trong : [ ] Mpac 80= .

: T s chiu di ct ren v bc ren = 0,8;

d : ng knh bulong d = 10

Q : Lc tc dng vo bulong

H : Chiu cao ai c, chn H = 10 mm;

Vy 4110.8,0.10.14,3

10368==c MPa [ ] 80=c MPa

Vy Bulong tha mn.

III. TNH TAN SAI S G:

Sai s ch to g c tnh theo cng thc;

[ ]

=++++=

2

1

5

122222gdctldmkcg

Trong : - k : Sai s kp cht phi, trong trng hp ny lc kp cng vi

phng thc hin ly: )(8,14 mk = .

- m : Sai s do mn g N = 110 l s chi tit cn gia cng.

)(2110.2,0 mm ==

- ld : Sai s do lp t g. )(10 mld =

- c : Sai s chun, trng hp nh v nh bn v 0=c .

Sai s g t cho php: [ ] )(675

mgd == .

Vy sai s ch to g:

)(45,6408,1410267 2222 mct =

Yu cu k thut g:

- khng song song gia phin t v bn my mm100/06,0 chiu di

- khng vung gc gia tm cht tr, cht trm v b mt g

mm100/06,0 chiu di.

- Chiu di B ca cht trm phi vung gc vi ng ni tm gia cht

tr v cht trm.

- nhm g Ra 2,5m.- Cht t phi c nhit luyn t cng > 40 50 HRC

8/2/2019 DO GA

6/6