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Unformatted text preview: Manufacturing Methods MAE 4500 Fall, 2006 Homework #4 1. A 1015 steel disc of 8.0 in. diameter and 1.0 in. in height is forged cold in a press of v=300 ipm. No lubricant is used. Calculate: (a) the starting workpiece length, if bar diameter is 5.0 in., (b) the flow stress at the end of the stroke, (c) the average die pressure, (d) the forging force. (e) What decrease in die pressure and forging force would occur if mineral oil is used as a lubricant? Solution: a) From consistency of volume ) . 8 ( 4 p 2 (1) = 4 (5.0) 2 h therefore h= 2.56 in b) = ln( f o h h ) = ln( 2.56 1 ) = 0.94 in/in From Table 8-2 : K = 620 MPa, n=0.18 K= 620 MPa = 89.92 kpsi f = K n = 89.92 (0.94) 0.18 = 88.92 kpsi c) d h = 8 1 = 8 From Fig. 9-6, Q a =2.1 for sticking condition (experimental) p a = Q a f = 2.1(88.92) = 186.73 kpsi d) P p = p a A 1 = 186.73 ( 4 (8) 2 ) = 9386.17 Kips e) Using mineral oil as a lubricant, from Table 8-4, = 0.1 From Fig. 9-6, Q a = 1.3 p a = Q a f = 1.3(88.92) = 115.6 kpsi P a = p a A 1 = 115.6 ( 4 (8) 2 ) = 5810.7 Kips Decrease in pressure = 186.73-115.6 = 71.13 kpsi Decrease in Force = 9386.17-5810.7 = 3575.47 Kips 2. A 2017 aluminum alloy slab of 300 mm thickness and 1000 mm width is hot rolled at 500 C and 100 m/min on a mill equipped with 800 mm diameter rolls, using a lubricant that gives a coefficient of friction of 0.2. It is proposed that a reduction of 30 mm be taken in the first pass. a Make a sketch of the process, b Check whether the reduction is feasible. c. Calculate the roll force for the allowable reduction. d. Calculate the net power requirement. e. repeat above calculations (a to d) for the final cold rolling pass to reduce the thickness from 1.2 mm to 0.6 mm with a roll speed of 500 m/min and a suitable lubricant....
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This note was uploaded on 04/30/2008 for the course MAE 4500 taught by Professor El-gizawy during the Fall '06 term at Missouri (Mizzou).
- Fall '06