ME364 exam 2 solutions - Exam #2 (April 28, 2008) YEDITEPE...

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Unformatted text preview: Exam #2 (April 28, 2008) YEDITEPE UNIVERSITY Mechanical Engineering Department ME 364 MANUFACTURING TECHNIQUES H — “.1 SPRING Semester M \ Duration: 2H0urs @1. @ CLOSED BOOK, CLOSED NOTES Metalworking processes are clasified, according to process temperature as: (a). flinwac/th. ................. .. (b). Co/a’...(4/o.ckr}n_9 ................ .. and according to the amount of deformaion as: (c).3u/k..dg76pm2‘z.ba ........ .. (d). SAeefi...m.e72/. firth/hf . List some advantages and limitations of cold working: (a).fiagqus....hfi raffleJJ...¢z,q.a(.Jlltth-fé ................................ .. (b).blm.€nflb.nq /. . exam“. . fl.an ............................................. .. (c)..k5.‘D.’Ja//..;.pafi73.....Wq...b@.SAW/uédflé; ........................... .. (dykéguzms’.....mO,c..foa/¢c.. ................... .. (e). III-Wes. . . . . .mfixfizfla? - -/~ea/ac.«:.r. . . éomflim- 6/54”!qu mgncfi‘c f/O/efl‘fefi 3. List the processes utilized to make the part in (e) from the stock in (a). (a) (e5) (e) (a). . .. WSZIQCé .... .. (b). .firwamégx fluszbfl ...... .. (c). .Qna/amflflmion ...... .. (d). . . .acflidzbn. rot/95%}; (e). ........................... .. La) (b) 4. (a). In .-.v. e ...... .. forging, the quality of forging depends on the skill of the operator. Three-piece assembly shown in the figure below can be manufactured as one piece by employing the following main processes: 5. Fill in the following questions with INCREASE or DECREASE. (a). Increasing hydrostatic pressure around a work piece of metal during forming does not vary flow stress much, but .... .. the true strain of fracture. (b). In extrusion, shear resistance ......... .. linearly with semicone angle. (c). In extrusion, friction losses .. with semicone angle. The flow stress for cold work is given by a = K8” : (d). Cold working results in .. in the value of K. (e). Cold working result in me. In the value of n. 6. (a). When upsetting a rectangular workpiece, material always flow in the direction of . 845. f. #195. {4172/}.ch . . . (b). When designing a part for forging, considerations should be given to: .57m0.v.7.% . . . aY‘é/nkfl . f/Da) . . 4 [/QMflQfJ‘ . . .. Mag. .............. .. gonna/:5 ........................ .. chat/7’5} Mic/meg ofueéJ/ a2. 7. The cylindrical cast iron part with a cavity shown in the figure below is to be produced by sand casting. You are required to calculate the dimensions of a pattern to produce the part using face A-A as a parting line and having the axis of work piece vertical. Calculate the dimensions of the pattern including the machining, shrinkage, and drag allowances. Draw the final dimensions of the pattern. Use the following allowances: Machining allowance = 3 mm/side Draft allowance = 3 mm/m Shrinkage allowance = 1 mm/m Surfaces marked \l are to be machined. b v‘ v 3 t if... - , MM (910 L. W1 0‘ t» a ) y e ' 8. (a). What is the difference between machining allowance and dimensional tolerance ? MaCWm‘n allOwG/tctc fanm-(g3 HQ amoaA-i‘ of MerisQ 375 be Wing fin,“ max surface. Dix/enscoan Hem/ice m4sz Hie lzmzhhf W °¥ oitmengion after JrAé (Mousse:- (b). Why are steels more difficult to cast than cast irons? What is the consequence ofthis? Nel‘it‘ng Tcmfemmm cg Sffie( is .ktf'Aef MM 65°34 ref/Li’th wufa,) had/(hf W'f MDHC/W WW4 ) I’WOH GN qu'en‘aflndaw mecr-Hcs ) shrink“ an: (c). What are hot spots in casting? What is their significance in metal casting? What can be done aboutthem? bW/{lf ant/hf / mftw of [bu/er 600(1)?!) ADJZS EC ("4‘ WritiTomsh‘v 0AA sit/7th mix/7‘9 C044 dwl" (d). Whay are risers not useful in die casting as compared to sand casting ? Qatar—s etc was! [A W c4995» to mafia Ju/P— Haida/7’90 Loafing, motif/t man‘an‘ég wfa be at/zzf/aé/e 04 hov‘ 6179973.]? die wfi/‘y/ “so/{W mqfi/{d ,5 11-424 12: e Una/er Pva/c)PQ/r¢ [5 WOW afi‘ér Coo/ea/Uf’zg 7%57‘ W 76¢ Mar. 9. Describe the factor that inuence the magnitude of the roll force, F, as shown on the figure on the right. ’ RID/(6r did/W073) . Ro/l-sywp confide/f /&Ad,7cg . 60.1440“ oFae’ F: L'Q/o L‘flc Rikvit‘f) Torque - knew" . .de/mom Jafl(éos/¥> ' 10. Calculate the roll force, torque and the power required for a 304 stainless steel strip 150 mm wide and 8 mm thick and rolled to a thickness of 6 mm. The roll radius is 180 mm and rolls rotate at 200 rpm. 3o4—57‘mb/wtfa/ g - g“ .52 4. 3. G _ ltd-=18me k—F ko:gmm 2:0.23 125:6». fie) gator/Hi (are) _ pass”. ‘1(o.Zs)‘='717Mfi(53rW‘) Tat? = my?” = sir/ma )U=Zao 7"“ F: Ltd-H:leISDx§IS=M€3on6N P T3!" #1; ': lfiéxxtocx 0-315 _-, I331“. N.m oust-r —; 2‘1?” 1 2x133“I ,4 27Tme 6° = 581,069 (A) 2-5th KMJ @ ll. (a). Why is the intermediate shape of a part important in forging operations? /r\7émtc-.(tZ/7é 47%;» filo/Drove uni/4m” 7&0“) 07/ Wide/JAE, M @4127 27” rec/aw max [6’05 #63»th . (b). How would you tell whether a certain part is forged or cast? Explain features that you would investigate. /Q//‘7(5 Acwc. 3000/ JuF/gce .QW7- ’57 0M1 find @a/C/ 1e mnth/e Z6”) Deck/Ale and /” W5 v§60firvruj (c). What are the differences between open-die and impression-die forging? I?» o/en a’x'e fi/f/x‘r/ [WW/5‘06 [5 M74 Zflfizeen 7%: {/H 1/65. ,7/ 2t emf/e, Amt raga/m matan were“ . fl Mfr/Mm- aét'e mag/721 #@ Me Sth 3]; aye [at/57" ,A‘gciérca 6 (d). What is “flash”? Where is it important? Why does it matter ?‘ F/‘MA ('5 hams“; tofi't/vz/lc dire Cory/ofig,$D/ne 9% mack/{due flow: DLLW 4N /5 MHF/MA h‘w firearm: an! firs/W Magma Mam/Ice flawta,xNNc»Mwa%sM1mehflfiy%w Mfi;%uh 12. Calculate the forging force at the end of the stroke for a solid, cylindirical workpiece made of annealed 70-30 brass that is 100 mm high and 150 mm in diameter and is to be reduced in height by 25%. Coefficient of friction is estimated to be 0.25. Sketch the shape with dimensions before #313 and after forging. ~.——-—/ 5“” 9”“ m H°=IDO~~ - . Ram”. W H1 fiwbgmw Mint red. H74 ——"——~ H1: Hum-Q'Y'v 15M», ‘ tum “new bww stews 4% 76% \IO -: U‘ ) ’12 H‘) a TIP—'2“; 4 4f‘ :LIS‘DZ Dz loo = ~11 :932 2=Lm,0'29 5’ K f“ i575“ M” W 490 \i : 300 x 0.130”: WMRL. J52: “Wm—"e WQM ‘93 a» 20% 210211011 ———*i; =HFH6U 3x? 6 -: l.34?‘xl0 L6 18¢“- 13. (a). What is the difference between extrusion and drawing? 7:“ @W5;M/mqj:nr«£ air /)u54e¢/ #M #Lol/E. .Dw abath matriaz I} fut/£4 7%“ #2»:- (b). What is a “dead metal zone”? Mei! [A m Comeer W 63124 dot» A01" move/{imflar 74> 5725(na1432n140w {If ado.”an OF 5A“? 36696: or {If/U- (c). What type of defects occur in extrusion: Syfice GflCL‘J/Plfl “774 My, dc. Drawin : - g fér mac/49;», 55am; (flay/$41M sawed, Into/Me SW42, wQV/ft‘ja/c/C 14. Calculate the force required in extruding a workpiece made of Aluminum at 400 ° . Billet diameter is 200 mm and extrusion ratio is 3%. How did you account for frictional loss and die angle ? How would you evaluate your result? AQ 111092 P we he“ (A9.) 59:2090‘4» [ha-3:30 £4250 M?“ (R 6V") At 2 2 ’gikéy‘go :"f’xsvflwo a: : S.ZAZ.A\OQ L) w ‘5342. +0“. +fl‘jG’V‘ i4 acc * CW W“ “l? “43$” oi/tcawéw K k“ RAM. & 180 160 140 120 True stress (psi x 103) . Aluminum 1100—O 2024—T4 6061~O 6061—T6 70757—0 Brass .2 70—30, annealed 85—15, cold-rolled Cobalt-based alloy, heat-treated 2070 Copper, annealed Steel Low-C annealed 4135 annealed 4135 cold-rolled 4340 annealed ~ 304 stainless, annealed 410 stainless, annealed K (MPa) 180 690 205 410 400 909 '5—80 ,———~, 315 530 1015 1100 640 1275 960 0.20 0.16 0.20 0.05 0.17 0.49 0.34 0.50 0.54 0.26 0.17 0.14 0.15 0.45 0.10 8650 Steel 1112 CR Steel 0.2 0.4 400 03 O O) O l\) O Extrusion constant, kc (103 psi) A O 0.6 0.8 True strain (8) 600 304 Stainless steel 70—30 Brass, as received 1020 Steel 4130 Steel 2024-0 Al 1100-O Al 1.0 1.2 1.4 1.6 °C 800 1000 1200 a- 1500 2000 Temperature (°F) 70—30 Brass, annealed Copper, annealed 2024-T36 Al 1.8 1 400 2500 1 200 1 000 800 Pa 600 E V 400 200 0 2.0 ...
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This note was uploaded on 11/17/2009 for the course MECHANICAL ME 364 taught by Professor Prof.dr.abdülkerimkar during the Spring '08 term at Yeditepe Üniversitesi.

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ME364 exam 2 solutions - Exam #2 (April 28, 2008) YEDITEPE...

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