design of fasteners and welded joints.pptx

8/16/2019 DESIGN OF FASTENERS AND WELDED JOINTS.pptx

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DESIGN OF FASTENERS AND WELDED JOINTS

Unit-3

LECTURE-2


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For supporting the travelling crane in a workshop, the brackets are fxed on steel columns asshown in Fig. 11.35. he maximum load that comes on the bracket is 1! k" acting verticall# ata distance o$ %&& mm $rom the $ace o$ the column. he vertical $ace o$ the bracket is securedto a column b# $our bolts, in two rows 'two in each row( at a distance o$ 5& mm $rom the loweedge o$ the bracket. )etermine the si*e o$ the bolts i$ the permissible value o$ the tensilestress $or the bolt material is +% a. lso fnd the cross-section o$ the arm o$ the bracke

which is rectangular. t and b / hickness and deptho$ arm o$ the bracketrespectivel#.0 ection modulus,

know that direct shear load on each bolt,

ince the bolts are subected to shear load as well astensile load, there$ore e4uivalent tensile load,

ize of the bolt know that the e4uivalent tensile load '2te(,

From psg!t!boo" #$%2'coarse series(, thestandard core diameter is 11.5% mm and thecorresponding si*e o$ the bolt is 1%.

C&o

ss-se'tio( of the !&) of the b&!'"et

0 aximum bendingmoment on the bracket,

/ 1! 6 1&3 6 %&& / %.+ 6 1& "-mm

2e know that the bending 'tensile( stress '7t(

ssuming depth o$ arm o$ the bracket* b + 2#,)), we have

Gie( 8 2 / 1! k" / 1! 6 1&3 " 9 : / %&& mm 9:1 / 5& mm 9 :! / 3;5 mm 9 7t / +% a / +%

"


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5. bracket hown in Fig. ;.1.1, is fxed to a steel column b# using % bolts. load o$ %&k" acts on the bracket at a distance o$ && mm $rom the $ace o$ thecolumn. he permissible tensile stress $or the bolt and bracket material is ;& NImm!. =$ the thickness o$ arm o$ the bracket is !& rom. determine8 'i( the si*e o$the bolts9 and 'ii( the width o$ the arm o$ bracket at the fxed ends.

>iven

Find

'i( he si*e o$ the bolts9'ii( he width o$ the arm o$ bracket at the fxed ends.

l!

l! /5&&mm

3


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d/?

%&&&&

%&&&&

;&

%


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5


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Fo&) .SGDD .!ge No$ #$%2* the bolt sele'te/0,

+21#%$#N

' + 22$22

+ 23$%#

4

3

/!5i)6) be(i(g )o)e(t o( the b&!'"et

b + 02,$1

Res6lt7i8 The size of the bolts+/2,7ii8 The 9ith of the !&) of b&!'"et !t the :5e e(s$+ 02,$1))


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;


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.OWER SCREW

he power screws 'also known as translation screws( are used to convertrotar# motion into translator# motion.

For example, in the case o$ the lead screw o$ lathe, the rotar# motion is

available but the tool has to be advanced in the direction o$ the cut againstthe cutting resistance o$ the material.

=n case o$ screw ack, a small $orce applied in the hori*ontal plane is usedto raise or lower a large load. ower screws are also used in vices, testingmachines, presses,etc.

#pes o$ crew hreads used $or ower crews 1. 4uare thread.!. cme or trape*oidal thread.3. @uttress thread.

design of fasteners and welded joints.pptx

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