11exam2a-KEY - Name: ‘— UFID Number: EML 4321 Student...

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Unformatted text preview: Name: ‘— UFID Number: EML 4321 Student Number: EML 4321: Manufacturing “ EXAM 2 —- 25 Feb 11 There are 8 questions for a total of 100 points. The time limit of 55 minutes will be strictly enforced. It is your responsibility to complete this long exam within that time frame. ' Please work efficiently and accurately. Choose the best or closest answer. Open book, open notes. (However, waste time with written materials at your own risk!) Calculators are the only type of electronic devices which may be used. the correct answer when alternative answers are given. Please remember to show your work when appropriate@ KM PertoX 1. (20 pts.) Mark whether the following statements are true or false. T@ Redundant work should be maximized to achieve metal forming efficiency. @F Sticking friction is more common in hot working than in cold working. I T@ A cylindrical workpiece being upset is in plane strain. @F Barrelling is more common in hot forging than in cold forging. T@ The entire material cross—section is yielded before springback occurs in bending. TCF) Most plastic polymers are thixotripic. @F Electrical discharge machining is slower than milling. @F Reamed holes can have smaller tolerances than drilled holes. @ F The spindle in a drilling machine should have stronger thrust (axial) bearings than in a high-speed milling machine. @ F In our modeling of the temperature field in a chip, the width of the chip (b) does not affect the temperature field. 2. (11 pts.) A two-meter-Wide sheet of steel is being reduced from 2.0 mm to 1.5 mm thickness between 600 mm diameter rolls. The yield strength is 200 MPa and the. interstand tension is 70 MPa. How much power is required to turn o_ne_ roll at 1000 rpm? E330 - L. 9007(— : 2513M) ,. (go >2r5/VLM/ 5 3. ( 11 pts.) Consider the indenting of a two-meter-wide plate as shown below. If the material has a yield strength of 120 MPa and L = 29 mm, what is the force (N) required on- each indenter if . .. a.h=29mm —> L b.h=145mm c.-h=350mm ‘1 FzFA h ESHO F=éQrY “ff—LA F520 :9 {—2}? @r=/,/5’ lids-79C???— a‘e F; @V-Y L b I at F- : mg (no gazxmymo m> : 8 M N b‘ F: 233‘ ((zo>(2_o(>(2_ooo> :fllL/fl/(j ' c. F?— 3(120)(2°()(zwo> =2a?%M/ 4. (6 pts.) Consider the rolling operation below. If vr is the tangential velocity of the outer edge of the rolls and v5 is the velocity of the sheet, indicate whether “=”, “<”, or “>” should be placed in the spaces below between the two velocities for points A, B, and C. pointA vr > Vs \fr pointB Vr 2‘: Vs pointC vr < vS M 5. ( 15 pts.) Three holes, each 1.6 inches in diameter, are punched into 0.1046” thick sheet of a material with a tensile strength of 45,000 psi. What force (tons) is needed? (Note: Use the industry standard formula, not Tlusty’s, for full credit.) L: h¥fi_$~0( :Bfiy‘fi"; (in 2 I‘AM F: (9,7 L-é (en‘s) , r427 (Katya/0% M) (45,000 lbs/IV) T :2 49,700 [195 (moo lbs) 1. 2% Q T 7 6. ( 11 pts.) A 17 mm diameter, two-flute drill is to drill a hole in a thick plate of 1020. The ~ feed per edge is 0.7 mm. What is the maximum torque (N -m) required to turn the drill? T7.I=;> (020/029 Ks 2,2100 AZ ham1 4: a 7% Efiflmwmwz‘ E=K5A=21002%23?5Wz= 124%” __ ACZflM ,E’L’r :53’/ [1M .ledve,=V/i:[email protected] 7‘-/ ’qusn/U/oao M T: (2 @2783) (53.: NsM/eo/793V626 MM 7. (4 pts.) For a particular turning operation, Fn = 0.25 Pt and the shear angle is 20°. If it is 5140, but KS = 2500 N/mmz, what is the chip shear temperature (°C) (before friction) if the workpiece is 40°C before cutting? A] p » o TW=~>5WO=>FC"3‘7W f/QZO _ a '_ o {3 =25“: =5” ’ 5:35;:2fim’015'i/fi/ é 8 8. ( 15 pts.) A half-immersion milling operation is being conducted with a 20 mm diameter tool cutting 3 mm deep with a feed of 0.6 m/min. The material is 1020. w _. ‘5 T2! -:> (max/:7 Kg?” 5;; a. What is the metal removal rate (cm3/min)? b. What is the mean power (kW)? CL (2 ‘2 araagc A M3 = (20 m4) C3 Mm>00<6 (sz'fl’l) :- /‘2> CMZ’R‘A 1a. @ngQ :2 2/00 = (9.603 Aa/ W‘s 130m Mm ku/ (14,43 11/! 64‘ go 36C. mac“) ...
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This note was uploaded on 09/06/2011 for the course EML 4321 taught by Professor Staff during the Spring '08 term at University of Florida.

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11exam2a-KEY - Name: ‘— UFID Number: EML 4321 Student...

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