cric telescopic - costy - final- eng!
TRANSCRIPT
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8/2/2019 Cric Telescopic - Costy - Final- EnG!
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1.ESTABLISHING THE LOADS THAT STRESS THE ELEMENTS
OF THE TELESCOPIC LIFTING JACK
Fig 1.1
2. MAIN SCREW CALCULUS
2.1 Choosing the materialIt is choosen OL 37 STAS 300
2.2 Design calculus
Load calculation cQ , Npo
][17820162001.1max NQQc === 1.1..05.1= NQ 16200max =
Inner diameter of the thread 3d , mm
][30.2150
17820443 mm
Qd
ac
c=
=
=
][80....60 MPaac =
1
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8/2/2019 Cric Telescopic - Costy - Final- EnG!
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Choosing the standard thread
It is choosen trapezoidal thread Tr 28x5 SR ISO 2904, with the main
dimmensions as shown in Fig 2.1 and Table 2.1
Fig 2.1
Tabelul 2.1
Nominal
Diameter
Pitch Medium
Diameter
Exterior
Diameter
Interior Diameter Angle
mmd, mmp, mmDd ,22 = mmD ,4 mmd ,3 mmD ,1,
28 5 25.5 28.5 22.5 23 30
2.3 Checking the self-locking condition
The threads pitching angle
=
=
= 57.35.25
5
2
2
arctgd
Parctg
Apparent friction angle
=== 53.6
2
30cos
11,0
2cos
' arctgarctg
12,0...11,0= for steel
Self-locking condition'
2