加入VIP 上传考博资料 您的流量 增加流量 考博报班 每日签到
   
主题 : 东大机械洋卷2
级别: 初级博友
显示用户信息 
楼主  发表于: 2007-11-14   

东大机械洋卷2

(1)       The center distance separability of a pair of involute spur cylindrical gears implies that a change in center distance does not affect the     . Sp2<rI  
(9phRo)>  
A. radii of the pitch circles     B. transmission ratio     C. working pressure angle *MG*]\D  
eL`}j9  
(2)       The main failure form of the closed gear drives with soft tooth surfaces is the       . lQ]8PR t8  
T[<deQ  
A. pitting of tooth surfaces     B. breaking of gear tooth N Qdz]o  
Z +vT76g3  
C. wear of tooth surfaces     D. agglutination of tooth surfaces E;vF :?|  
ALOS >Bi&  
(3)       The tooth form factor in calculation of the bending fatigue strength of tooth root is independent of the       . ?e. Ge0&  
! /qQ:k-.  
A. tooth number   B. modification coefficient   C. module |RA|nu   
>B~vE2^tQ~  
D. helix angle of helical gear D J:N  
Hx|<NS0}_  
(4)       The contact fatigue strength of tooth surfaces can be improved by way of     . 0YApaL+jt  
Ol@ssm  
A. adding module with not changing the diameter of reference circle xyvG+K&  
M `=bJO:  
B. increasing the diameter of reference circle 9td[^EB#(h  
j/Dc';,d.(  
C. adding tooth number with not changing the diameter of reference circle @8;0p  
-{=c T?"+  
D. decreasing the diameter of reference circle D rMG{Yiu  
s&gzv=v  
(5)       In design of cylindrical gear drives, b1 = b2 +(5~10)mm is recommended on purpose to       . (Where b1, b2 are the face widths of tooth of the smaller gear and the large gear respectively.) ~ZN]2}  
1/l;4~p7'  
A. equalize strengths of the two gears         B. smooth the gear drive jb5nL`(j$  
|rhCQ"H  
C. improve the contact strength of the smaller gear 8!!iwmH{  
Tam\,j  
D. compensate possible mounting error and ensure the length of contact line Vjc*D]  
eKT'd#o2R  
(6)       For a pair of involute spur cylindrical gears, if z1 < z2 , b1 > b2 , then     . }p <p(  
4NN81~v 4  
A.     B.     C.     D. )HFl 0[vT  
zq?Iwyo  
(7)       In a worm gear drive, the helix directions of the teeth of worm and worm gear are     the same. 1,/L&_=_A  
' >F_y t9  
A. certainly       B. not always       C. certainly not ! 54(K6a[  
R'.YE;leBG  
(8)       Because of       , the general worm gear drives are not suitable for large power transmission. :6 \?{xD  
POouO/r$  
A. the larger transmission ratios   B. the lower efficiency and the greater friction loss (_Ld^ ^|  
'B$ bGQ  
C. the lower strength of worm gear   D. the slower rotating velocity of worm gear 02EbmP  
u\]aUP e  
(9)       In a belt drive, if v1, v2 are the pitch circle velocities of the driving pulley and the driven pulley respectively, v is the belt velocity, then       . N-+`[8@(P<  
5nhc|E)C  
A.   B.   C.   D. "E><:_,\  
9m:qQ1[\  
(10)   In a belt drive, if the smaller sheave is a driver, then the maximum stress of belt is located at the position of going     . ];|;")#=  
`T;M=S^y*E  
A. into the driving sheave       B. into the driven sheave =}G `i**  
g[W`4  
C. out of the driving sheave       D. out of the driven sheave I2b\[d  
l*l(QvN_  
(11)   In a V-belt drive, if the wedge angle of V-belt is 40°,then the groove angle of V-belt sheaves should be     40°. D-zqu~f`  
4eOQP  
A. greater than     B. equal to     C. less than     D. not less than 7;_./c_@  
I&} Md73  
(12)   When the centerline of the two sheaves for a belt drive is horizontal, in order to increase the loading capacity, the preferred arrangement is with the       on top. kdWk{ZT^  
o~Im5j],*  
A. slack side   B. tight side bB^SD] }C  
JQ*CF(9  
(13)   In order to     , the larger sprocket should normally have no more than 120 teeth. CPI7&jqu  
'WUevPmt  
A. reduce moving nonuniformity of a chain drive iCouGd}  
,UdTUw~F  
B. ensure the strength of the sprocket teeth     C. limit the transmission ratio 27;t,Oq}  
P2n b&lVdu  
D. reduce the possibility that the chain falls off from the sprockets due to wear out of the Dl3Df u8  
]i=\5FH e  
chain [hf#$Dl |  
/lQGFLZL  
(14)   In order to reduce velocity nonuniformity of a chain drive, we should take       . #du!tx ( _  
]JeA29   
A. the less z1 and the larger p     B. the more z1 and the larger p i%+p\eeq*  
8"a[W3b  
C. the less z1 and the smaller p     D. the more z1 and the smaller p bP`.teO\  
D]9I-|  
(Where z1 is the tooth number of the smaller sprocket, p is the chain pitch) |wKC9O@%  
RZ!-,|"cwL  
(15)   In design of a chain drive, the pitch number of the chain should be     . ,X&lVv#  
r/E;tm [\  
A. even number   B. odd number   C. prime number 2 $^n@<uZ@  
IYq)p /  
D. integral multiple of the tooth number of the smaller sprocket :XK.A   
Uhc2`r#q  
uL^Qtmm>M  
ocCC63J  
2. (6 points) Shown in the figure is the simplified fatigue limit stress diagram of an element. p/B&R@%  
zg!;g`Z@S  
If the maximum working stress of the element is 180MPa, the minimum working stress is -80MPa. Find the angle q between the abscissa and the line connecting the working stress point to the origin. Kb~s'cTxIO  
he0KzwBF  
CPVR  
7hq*+e  
+A 6xY  
'dYjbQ}~;  
3. (9 points) Shown in the figure is the translating follower velocity curve of a plate cam mechanism. i DV.L  
(MiEXU~ v  
(1)   Draw acceleration curve of the follower schematically. jN:!V t  
4oT1<n`r+  
(2)   Indicate the positions where the impulses exist, and determine the types of the impulses (rigid impulse or soft impulse). V-U,3=C  
$v?+X20  
(3)   For the position F, determine whether the inertia force exists on the follower and whether the impulse exists. $d M: 5y  
nS0K&MH6B  
`Q V}je  
N.OC _H&  
]%jlaXb  
[L 0`B9TD~  
f?T6Ne'  
">]v'h(s  
N"MuAUB:K  
S?Q4u!FC  
Bi9 b"*LN  
W8j)2nKD  
4. (8 points) Shown in the figure is a pair of external spur involute gears. } )O ^xF ~  
<Y9vc:S  
  The driving gear 1 rotates clockwise with angular velocity while the driven gear 2 rotates counterclockwise with angular velocity . , are the radii of the base circles. , are the radii of the addendum circles. , are the radii of the pitch circles. Label the theoretical line of action , the actual line of action , the working pressure angle and the pressure angles on the addendum circles , . dg/OjiD[P  
s0"S;{_#  
D4[1CQ@}4D  
6Clxe Lk  
ri&B%AAc  
6%Ap/zvCZ>  
5. (10 points) For the elastic sliding and the slipping of belt drives, state briefly: Mw2?U>h1  
u"r~5  
(1)   the causes of producing the elastic sliding and the slipping. |i'V\" hW  
qy=4zOOD#  
(2)   influence of the elastic sliding and the slipping on belt drives. U^SJWYi<Y  
{s!DRc]ln  
(3)   Can the elastic sliding and the slipping be avoided? Why? zK893)  
`9rwu:3i  
< U`lh  
8X`iMFa.P  
CrC1&F\dq  
<w UDcF  
h}fz`ti U  
|r5 np  
An cmSi  
8B;wn<O  
r# MJ  
f$$l,wo  
]2\|<.  
3Z#k9c_b  
lR[[]Yn  
KB49~7XjQ@  
d:* ,HzG  
j*@^O`^v  
}eh<F^  
-b+VzVJZ  
<6g{vNA  
8P5yaS_  
jY'svD~  
p`:hY`P  
{/ `iZzPg  
zhtNL_  
m` ^o<V&  
8&?Kg>M  
RGFanP  
a^_\#,}  
.lnyn|MVb  
FJo  ?~  
6. (10 points) A transmission system is as shown in the figure. 3D L7   
Bfe#,  
The links 1, 5 are worms. The links 2, 6 are worm gears. The links 3, 4 are helical gears. The links 7, 8 are bevel gears. The worm 1 is a driver. The rotation direction of the bevel gear 8 is as shown in the figure. The directions of the two axial forces acting on each middle axis are opposite. Xkc y~e  
D/QSC]"  
(1)   Label the rotating direction of the worm 1. ("07t/||  
\6o%gpUkD  
(2)   Label the helix directions of the teeth of the helical gears 3, 4 and the worm gears 2, 6. B1)gudP`  
?O3E.!Q|  
Kn-cwz5  
zOJ4I^^  
rTTde^^_  
_8x:%$   
{Q9?Q?  
~q]@Jp  
 v?Dc3  
;e,_F/@`  
7. (12 points) A planar cam-linkage mechanism is as shown in the figure with the working resistant force Q acting on the slider 4. tt5t(+5j  
SFhi]48&V  
  The magnitude of friction angle j (corresponding to the sliding pair and the higher pair) and the dashed friction circles (corresponding to all the revolute pairs) are as shown in the figure. The eccentric cam 1 is a driver and rotates clockwise. The masses of all the links are neglected. ; kPx@C   
5cj]Y)I-~  
(1)   Label the action lines of the resultant forces of all the pairs for the position shown. $ 9bIUJ  
m?3!   
(2)   Label the rotation angle d of the cam 1 during which the point C moves from its highest position to the position shown in the figure. Give the graphing steps and all the graphical lines. %siBCjvo=  
38ac~1HjE  
2to~=/.  
"^M/iv(  
\dvzL(,  
bO8>w9MF  
G<1)N T\u  
>]b>gc?3  
9*fA:*T  
=NJ:%kvF  
8. (15 points) In the gear-linkage mechanism shown in the figure, the link 1 is a driver and rotates clockwise; the gear 4 is an output link. pXn(#n<  
#63)I9>  
(1)   Calculate the DOF of the mechanism and give the detailed calculating process. DX3xWdnr  
Q\H1=8  
(2)   List the calculating expressions for finding the angular velocity ratios and for the position shown, using the method of instant centers. Determine the rotating directions of and . >~%!#,C(|U  
=Sjr*)<@j  
(3)   Replace the higher pair with lower pairs for the position shown. aTi2=HL=S  
kT7x !7C  
(4)   Disconnect the Assur groups from the mechanism and draw up their outlines. Determine the grade of each Assur group and the grade of the mechanism. 96a2G,c >V  
%K9pnq/T^  
k&JB,d-mJ%  
R\i8O^[  
o<1a]M|  
ajr);xd  
#:q$sKQ_$  
wl^7.IR  
W#|30RU.G  
" pZvV0'  
dWR-}>  
nky%Eb[\  
So6ZNh9  
 _%r+?I  
st7\k]J\  
ejF GeR  
^-wdIu~p?  
0c -.h  
?'xwr )v  
XJ$mRh0`K  
{4C/ZA{|l  
sY- ] Q  
a+-X\qN  
6@rebe!&=  
l-v(~u7  
`F(ghC  
9. (15 points) An offset crank-slider mechanism is as shown in the figure. ',_E;(  
%&Fsk]T%:  
If the stroke of the slider 3 is H =500mm, the coefficient of travel speed variation is K =1.4, the ratio of the length of the crank AB to the length of the coupler BC is l = a/b =1/3. `)aIFAW  
t| cL!  
(1)   Find a, b, e (the offset). qN=l$_UD  
7u=R5  
(2)   If the working stroke of the mechanism is the slower stroke during which the slider 3 moves from its left limiting position to its right limiting position, determine the rotation direction of the crank 1. -qJ%31Mr#  
j@o \d%.'!  
(3)   Find the minimum transmission angle gmin of the mechanism, and indicate the corresponding position of the crank 1.
评价一下你浏览此帖子的感受

精彩

感动

搞笑

开心

愤怒

无聊

灌水

  
描述
快速回复

验证问题:
免费考博论坛网址是什么? 正确答案:freekaobo.com
按"Ctrl+Enter"直接提交