10_ch 17 Mechanical Design budynas_SM_ch17

10_ch 17 Mechanical Design budynas_SM_ch17 - F 1 = ab from...

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Chapter 17 429 An approximate comparison of non-metal and metal belts is presented in the table below. Non-metal Metal γ , lbf/in 3 0.04 0.280 b ,in 5.00 1.000 t ,in 0.20 0.005 The ratio w/w m is w w m = 12(0 . 04)(5)(0 . 2) 12(0 . 28)(1)(0 . 005) ˙= 29 The second contribution to F c is the belt peripheral velocity which tends to be low in metal belts used in instrument, printer, plotter and similar drives. The velocity ratio squared influences any F c / ( F c ) m ratio. It is common for engineers to treat F c as negligible compared to other tensions in the belting problem. However, when developing a computer code, one should include F c . 17-13 Eq. (17-8): ± F = F 1 F 2 = ( F 1 F c ) exp( f θ ) 1 exp( f θ ) Assuming negligible centrifugal force and setting
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Unformatted text preview: F 1 = ab from step 3, b min = F a exp( f ) exp( f ) 1 (1) Also, H d = H nom K s n d = ( F ) V 33 000 F = 33 000 H nom K s n d V Substituting into (1), b min = 1 a 33 000 H d V exp( f ) exp( f ) 1 Ans . 17-14 The decision set for the friction metal at-belt drive is: A priori decisions Function: H nom = 1 hp , n = 1750 rev/min , V R = 2 , C = 15 in , K s = 1 . 2 , N p = 10 6 belt passes. Design factor: n d = 1 . 05 Belt material and properties: 301 / 302 stainless steel Table 17-8: S y = 175 000 psi, E = 28 Mpsi, = . 285...
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This note was uploaded on 12/13/2011 for the course EML 3013 taught by Professor Shingley during the Fall '11 term at UNF.

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