
4. Rolling. A series of cold rolling operations is to be used to reduce the thickness...
Q3. ( 25 points) A rolling mill used to reduce a sheet strip by 3 mm in thickness. The sheet has 2.5 cm thickness and 30 cm in width. The rolling speed is 0.83 rev/sec. The sheet material flow stress is given by a = 275€0.15. A compression test was conducted to find the coefficient of friction and revealed that the coefficient of friction is 0.12. Check if the friction is adequate for the rolling operation. If it is calculate...
A strip 300 mm wide and 25 mm thick is rolled to a final thickness of 21 mm with ∅500 mm rolls running at 60 RPM. K = 275 MPa and n=0.2. Using two passes of draft = 2 mm (i.e. t1=23 mm and t2=21 mm) , the class found that the rolling forces were 936 and 1220 kN respectively, and that the power requirement was 171 kW (based on the 2nd pass). It is hypothesized that since the flow...
A U-channel of 85-15 brass will be shape formed, but first must be flat rolled to a thickness of 0.9 mm. The strip has a width of 25 mm and an initial thickness of ho=1.5 mm. A preliminary process design suggests a 40% reduction in a single pass on a rolling mill with 150 mm-diameter rolls. If the roll surface speed is 1 m/s, and the coefficient of friction is μ=0.1, calculate the rolling force and power requirements. Repeat the...
Q.6 Rolling A 28+Y mm thick, 275+X mm wide metal strip is fed through a two – high rolling mill; each roll has a radius of 240+Z mm having a rotational speed of 48+Z rpm. The strip thickness is to be reduced to 24+Y mm in one pass. The strength coefficient of the work material is 270 MPa and strain-hardening exponent is 0.12. Determine: a- The minimum coefficient of friction between the strip and roll surface μ (Use dmax =...
coefficient of low carbon steel: 0.7 (static)
0.6 (kinetic)
Also need help with this second homework problem related to metal forming: 2. Given the following for hot rolling a low-carbon steel plate, calculate the number of rolling passes if the maximum load on the roll in each pass is not to exceed 28,400 lb/in^2: - Diameter of the roll: 20 inches (500 mm) - Stock width: 48 inches (1020 mm) - Initial thickness: 1.5 inch (37.5 mm) - Final thickness:...
26. A 42.o-mm-thick plate made of low carbon steel is to be reduced to 34.0 mm in one pass in a rolling operation. As the thickness is reduced, the plate widens by 4%. The yield strength of the steel plate is 174 MPa and the tensile strength is 290 MPa. The entrance speed of the plate is 15.0 m/min. The roll radius is 325 mm and the rotational speed is 49.0 rev/min. Determine the minimum required coefficient of friction that...
Problem 2 (20 pts): Determine the range of acceptable initial thicknesses for a cold rolled plate with a final thickness of 0.5 cm having at least 65,000 psi tensile strength, 60,000 psi yield strength, and 5% elongation. [Hint: Assume a constant or infinite width.] 1 100 90 80 -70 60 100,000 90,000 a) Illustrate how you use the chart for this problem (4 pts) 70,0001-ensile strength 60,000 50,000 40,00아 Yield strength50 -40 30 20 10 30,000 20,000 10,000 % Elongation...
NE Steel tubes (k =35 W/m2.K) of 400-mm inner diameter and 30-mm wall thickness are used to route superheated steam from the boller to the turbine in a power plant. Safety and economic concerns make it practical to add a 200-mm layer of Insulation (k =0.1 W/mK) to each tube, which is wrapped in a thin sheet of aluminum with an emissivity e =0.15. The air (with a convective coefficient h =5 W/m2K) and wail temperatures of the plant are...
#1. To reduce nitrogen oxide emissions from a diesel engine, one commonly used strategy is exhaust gas recirculation (EGR). In a stack-type EGR cooler, exhaust gases flow through tubes with a rectangular cross-section (4 mm x 6 mm). In each tube, the mass flow rate of exhaust gases is 0.0001 kg/s; the gases enter at 140°C while the inner surface of each tube is maintained at 80°C due to water being circulated as a coolant. The length of the tube...
QUESTION 9 To maintain a constant speed, the force provided by a car's engine must equal the drag force plus the force of friction of the road (the rolling resistance). What is the drag force at 57.2 MPH for a Hummer H27 (Drag area for Hummer is 2.44 m2 and look up Table 5.2, chap-5 for the drag coefficient) Express your answer in N with 3 significant figures. QUESTION 10 Calculate the terminal velocity a spherical rain drop, diameter 4.06...