problem solution_ch15 - Chapter 15 Problem 2 A1 1 2-in...

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Unformatted text preview: Chapter 15, Problem 2 A1 1 2-in. diameter, double thread Acme screw is to be used in an application similar to that of Figure 15.6. Determine ( a ) The screw lead, mean diameter, and helix angle. ( b ) The starting torques for lifting and lowering the load. ( c ) The efficiency, if collar friction is negligible. ( d ) The force F to be exerted by an operator, for a = 15 in. Given: f = 0 . 1 , f c = 0 . 08 , d c = 2 in., W = 1 . 5 kips ( a ) L np in = = = 2 0 25 0 5 ( . ) . . Table 15.3: 1 4 p p = = , .25 d d i p = − = − = 2 15 0125 1375 . . . n m . Fig.15.4a: α = 14 5 . o o d L m 6 . 6 ; tan ) 375 . 1 ( 5 . = = = λ λ π π tan cos tan cos . (tan . ); . α λ α α n o n o = = = 6 6 14 5 14 41 ( b ) For starting, we have f f c = = = = 4 3 4 3 01 013 0 08 011 ( . ) . , ( . ) . 2 tan cos tan cos 2 c c n n m d Wf f f Wd u T + = − + λ α λ α . 1012 2 ) 2 )( 11 . ( 1500 6 . 6 tan ) 13 . ( ) 41 . 14 (cos 6 . 6 tan ) 41 . 14 (cos 13 . 2 ) 375 . 1 ( 1500 in lb o o o o ⋅ = + = + − + . 769 2 ) 2 )( 11 . ( 1500 6 . 6 tan ) 13 . ( ) 41 . 14 (cos 6 . 6 tan ) 41 . 14 (cos 13 . 2 ) 375 . 1 ( 1500 in lb T o o o o d ⋅ = + = + + − ( c ) % 46 46 . 6 . 6 cot ) 13 . ( 41 . 14 cos 6 . 6 tan ) 13 . ( 14 . 14 cos cot cos tan cos = = = = + − + − o o o o n n f f e λ α λ α ( d ) lb F a T u 5 . 67 15 1012 = = = Chapter 15, Problem 10 A 50-mm diameter square-thread screw having a pitch of 8 mm carries a tensile load of 15 kN. Determine (a) The axial stress in the screw. The axial stress in the screw....
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This note was uploaded on 03/24/2010 for the course ME 031 taught by Professor Kim during the Winter '10 term at Korea Advanced Institute of Science and Technology.

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problem solution_ch15 - Chapter 15 Problem 2 A1 1 2-in...

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