Belt-Drive and Chain-Drive Design Exam for Mechanical Engineering Students, Exams of Computer Aided Design (CAD)

Download Belt-Drive and Chain-Drive Design Exam for Mechanical Engineering Students and more Exams Computer Aided Design (CAD) in PDF only on Docsity! Cork Institute of Technology Bachelor of Engineering in Mechanical Engineering – Stage 2 (EMECH_7_Y2) Summer 2008 CAD & DESIGN (Paper 2 – Design Written) Time: 2 Hours Answer Question 1 or 2 (40 marks) and two other questions (30 marks each) Examiners: Dr. R.K. McMullan Mr. A. Bateman Dr. P. Delassus (1) Make an annotated sketch of a typical belt-drive, and clearly identify the Arc of Contact (1 Mark) Regarding belt-drives, briefly discuss the following: • Ease of installation • Service life / failure mode • Operating environment • Speed and torque limitations • Service life / failure mode • Versatility (9 Marks) A two-cylinder compressor is driven by a 38hp 1.25litre direct-injection diesel engine for up to twelve hours per day. The engine runs at 800rpm and drives the compressor at 355rpm. The assembled drive system must fit in an enclosure of 1.31m or less; however the centers of the motor and compressor shafts must be at least 70cm apart. Design a belt-drive for this application, using the tables provided. Clearly specify: • Service Factor • Sheave diameters • Belt-length correction factor • Belt Cross-section • Belt length and number • Arc-of-contact correction factor • Speed Ratio • Basic kW rating • Number of belts required (30 Marks) (2) Regarding chain-drives: • Explain the term Roller Chain • Sketch the elements that make up this type of chain • Indicate how the lubrication regime is selected • Explain how chain-drives are designed to fail. Why is this so? (10 Marks) A single-cylinder 160cc 5.5H.P. engine, rotating at 400rpm, is used to drive a cement mixer for up to 6 hours each day. A chain-drive is required to step the speed down to 80rpm, before a worm-drive gearbox produces the required speed on the drum. The engine and gearbox shafts are spaced 300mm apart. The overall size of the chain-drive must not exceed 55cm. Design a chain-drive for the above application, using the tables provided. Clearly specify: • Service Factor • Chain size and pitch • Driven sprocket • Design Power • Number of strands • Lubrication method • Speed Ratio • Drive sprocket • Chain length (30 Marks) (3) Regarding the design process: a) Explain how and why any design process is an iterative one. b) Highlight some similarities and differences between a Prescriptive and Descriptive approach to the design process. c) Does a heuristic approach limit conceptual design? d) Comment on the importance in establishing function in a design study. e) What is the relationship, if any, between Design and Invention (15 Marks) Make a Functional Analysis of a fully-featured domestic burglar-alarm. (7 Marks) Make a full Black-Box analysis of the machine. Sketch its proposed functional flowchart. (8 Marks) (4) Describe four standard methods of attaching a pulley to a shaft, in order to transfer torque to/from it. Sketch each method, and list relative strengths and weaknesses for each. (8 Marks) Sketch a hub/shaft/key assembly, and list the four possible failure mechanisms. What is the preferred mode of failure and why? (5 Marks) A hub φ80mm 84mm long is mounted onto a φ50mm shaft using a hollow circular pin that passes diametrically through both. The acceptable working shear-stress in the pin material is 230MPa and the torque to be transmitted is 180Nm. If the internal diameter of the pin is 40% of the external diameter, what size pin must be used? (17 Marks) (5) Give the definition of a Threaded Fastener. Describe its construction. Make an annotated sketch of a standard ISO metric thread. (5 Marks) For threaded fasteners in general: • Discuss what influences the selection of threaded fastener material. • What is the preferred mode of failure and why? • Explain what is meant by strength-grade or property-class • Sketch a σ-torque relationship for a threaded fastener. On it identify the preferred pre-load stress in relationship to the proof, yield and ultimate stress (10 Marks) What is the difference in torque required to correctly assemble a M10×1.5 10.9 threaded fastener if the threads are a) plain dry or b) lubricated with Molybdenum disulphide? (15 Marks) kKW-RATINGS (Pn) CROSS SECTION Cc (2213.5 mm) kW per belt at 180° arc of contact Pitch diam. E Pi 6 RPM OF SMALLER SHEAVE sheave rato mm 50 100 200 300 409 00 600-720 800 $80 1000 1100 1200 1200 1450 1600 1800 2000 096 082 at 174 202 228 253 275 304 312 923 342 955 367 376 390 375 037 083 146 179 209 297 262 284 314 324 339 354 386 380 389 303 388 038 0.88 150 1.85 216 245 271 294 325 334 35: 386 378 392 402 407 £00 039 068 155 191 224 253 279 304 325 945 382 377 391 408 4.16 420 416 040 070 180 1.97 290 261 288 313 346 355 374 390 403 418 428 434 427 100045 O79 137 188 223 276 314 351 385 431 445 471 495 516 542 562 577 581 180 120 043 082 146 200 250 295 337 376 412 461 476 50% 529 551 579 601 618 621 150 045 087 151 208 258 305 547 389 425 476 492 520 546 570 599 620 638 642 2300 05! 089 155 213 266 314 553 400 459 402 Sos 597 504 587 619 640 658 662 O54 096 169 293 293 349 400 449 493 556 575 610 843 672 7.09 726 765 7.73 085 009 174 24: 303 360 414 464 512 575 595 632 665 626 T24 765 788 795 150 060 1.05 186 258 324 385 442 495 545 614 695 675 7.10 743 780 B17 848 854 182 266 334 307 455 512 563 694 655 695 733 785 810 009 B68 876 IV 8 g B 1.00 064 (1.46 207 288 364 434 $00 563 621 7.01 7.26 7.73 B17 884 9.05 942 964 972 105067 120 213 299 276 450 518 583 643 726 751 802 B46 883 927 964 1001 10.08 069 124 221 308 389 464 525 602 665 751 780 B24 B68 315 964 10.01 1038 1045 O71 128 228 318 402 4280 553 622 6887 773 802 854 905 942 99: 1028 1067 1075 . O74 192 295 328 414 495 571 642 702 802 824 883 927 972 1030 1067 1ST 11.1 10007 198 247 347 259 $26 6.08 Gea 758 105 O79 142 255 358 655 845 629 7.09 7.20 120-082 147 264 B71 470 563 G51 732 3.10 150 084 152 272 383 485 581 671 758 839 300 087 157 282 395 S00 600 693 780 a6) 942 994 1038 1089 1133 1163 1163 9.72 1080 10.75 14.93 1170 1207 12.07 1008 1067 11.17 11.70 1214 1246 12.44 3038 1097 1141 1207 1251 1288. 12.69 3075 1193 11.78 1244 1295 1325 12.25 100 O89 163 293 4.13 526 620 729 224 919 1050 1067 11.26 11.92 105 092-168 «904 528 S43 652 7:58 854 942 1067 1087 11.63 12.22 280 120 (096 176 314 442 S82 674 780 876 272 1097 1133 1207 1286 13.86 1428 1450 14.28 150 099 180 325 457 580 696 302 913 1001 11.23 1170 1244 1317 1428 1472 1801 14.72 22300 102 85-384 GTI $93 718 B32 GAZ 1098 11.70 1207 1288 1947 14.13 14.72 1531-1546 15.16 1295 1240 1962 19.32 13.40 1366 14.06 13.86 100-105-191 347 489 624 751 B68 972 1082 1714 1251 1992 1391 1450 1509 1598 15:28] 14.65 105 1081.97 359 5.08 645 7.73 9.91 1008 11.19 1259 1295 13.76 1443 1501 1568 1590 1590 ]15.16 MS 120 142-205-871 525 668 802 927 1045 1166 1286 1249 1420 1696 1546 16.12 1641 16.47 [1575 180 146 211 363 542 G89 824 957 1082 1192 1940 1384 1465 15.98 1597 1663 17.00 17.00 ]1827 300 1.19 218 295 559 7.12 B54 994 1119 1296 1284 1428 1516 1590 1656 17.15 17.52 1752 }1671 liv 1001.21 22 408 576 105 1.26 «232 422 S97 365 1200-190 «238 496 617 450 128 287 450 837 300 198 255 464 658 1420 1465 1548 1612 1663 17.08 17.15] 1663 1465 15.16 15.97 1683 17.18 1768 17.81] 17.15 15.16 1568 1656 17.22 1781 1693 1840] 17.82 1868 16.19 1708 17.81 1833 1884 18.92} 19.08 16.19 171 1759 1833 1892 1950 1958] 1892 IV TEE wa ndanes ma roconmonaea pind Tovcanicay balanced saves aro ocormanaca LENGTH CORRECTION FACTOR (C2) BELT NO. Si 68 «6090105112120 196 «158162 «180-210 240-270 300-930-360 420 Pitchienaih 1800 1792 2097 2951 2742 010 8118 a519 W07e 4100 4607 5900 6761 6025, TeBs a4A7 9200 10705 c 080 085 089 0.81 0.94 095 097 0.99 102 103 105 108 1.11 1.14 116 119 121 1.26 kKW-RATINGS (PN) cross section D (32x19 KW per belt at 180° arc of contact mm) PM OF SMALLER SHEAVE so 100 «160 «200 250 PSG OSD 50D SSO GOO 720 BO SOD 1108 1200 134° 2820 317 3.06 467 554 SOF 656 742 7.65 6.10 861 942 10.08 1082 10.87 11.26 11.93 186 241 329 409 484 659 GIG 679 736 788 839 B91 9.72 10.38 11.99 11.33 11.63 11.70 143 249 809 424 500 572 699 702 756 817 G68 920 1001 1075 1156 1178 1207 12.14 17 2S7 O51 457 S17 S91 660 728 TEE 846 891 949 1098 11.11 1200 1214 1284 1251 153° 264 362 451 633 609 681 751 810 668 6.27 G72 1075 1141 1236 1251 1288 1295 187 295 408 513 610 699 786 878 O49 1050 1.97 1163 1985 1501 1531 1582 1597 174 30S 422 531 682 727 817 905 986 1067 185 325 451 S67 67S 780 878 964 1052 1199 12: 181 396 465 586 696 802 905 996 1082 1170 1251 1.00 2.05 366 5.10 645 773 BS 1008 11S 1214 43.17 105 2.42 878 528 688 802 920 1048 1156 1269 1369 385 1.20 2:19 391 S46 GOO B26 M57 1062 1200 1308 14:13 150 226 404 5.84 71D 654 G86 1119 1206 1947 1457 soo 233447 5.82 735 883 10.16 1144 1268 1399 15.01 1825 247 445 6.24 795 949 1057 1251 18.84 1516 1654 17.59 1869 2068 2237 2429 26.78 2547 26.69 255 489 645 924 986 1141 1286 14.26 1568 1700 1818 19.26 21.94 25.18 28.10 25.69 2555 2668 264 475 668 846 10.16 1178 1392 1487 1619 1752 1877 2002 2208 23.92 2598 26.57 2716 2753 272 491 689 B76 1052 1214 1375 1531 16.71 IAB 1843 2068 2289 2473 2679 2731 2804 DeAi 282 S07 7.12 905 1082 1259 1420 1882 1722 1868 20.02 2127 2563 2547 B7S7 28.26 2802 28.28 100 293.«5317S1 957 11st 1992 1509 16.76 1885 1987 2127 7260 2502 27.01 2945 26.59 90.10 30.10 105 903 -$50 7.73 986 11,92 13.76 1568 17.37 1606 2055 2208 2340 25.63 27.89 B010 90.64 3121 3121 450 420 3.14 867 B02 1016 12.22 1428 1619 17.74 1065 2127 2282 2421 2872 2BAS S113 31.65 3224 32.16 HSC 924 «S87 G24 1052 1266 1472 1671 1847 2031 2201 2548 25.02 2760 2973 3216 3268 39.27 3827 40 334 G05 B54 1069 1303 15.18 17.15 19.14 2090 2260 74.29 25.76 2648 5076 3319 3B7t 8420 3450 400 839 647 B78 1149 15.40 1559 1768 19.65 2142 29.26 24.92 2695 2307 31.21 Gas 93.71 S398] 5949 105 380638 905 1156 1A84 1612 1825 2031 2223 BACT 2876 FSB 30.10 3238 3452 24.96 36.11) 2487 600 120 © 362 659 927 1192 1443 1671 1864 20.08 2296 2488 26.64 26.26 91.19 3341 35.70 9614 36.96) 35.84 150 378 681 964 1236 14.87 i722 1950 2171 2aT? ZED 24S 2915 3209 3452 B8A0 9724 37.54) 37.02 seo 385 02 984 1265 1.9 1781 2009 2097 2AS1 BeAr 734 0 3210 3655 9700 8042 3871] 0820 100-383 7.18 1018 16.76 1625 2068 22.90 3684 9761 97.69) 97.99 tos 407 743 1052 1627 1884 2136 23.7 3709 3893 39.16] 9871 seo 120 «421 7.85 1088 16.78 1950 2208 24.88 3835 4033 40.48] 40.04 150 434 795 11.28 W738? 20.1e 2289 2539 3960 4158 4173] 41.29 2300 447 87 1168 4788 2083 2263 2620 2085 4261 49.08] 4264 400-455 6.99 1192 1846 1893 2127 2407 2672 2915 S149 3349 3540 38.42 a048| 4146 105 472 «BEI 1222 1875 18.92 2201 2195 27.60 9018 9259 a467 2665 99.74 41.95] 4291 680 420 «488 8.91 1266 1627 1068 2282 2576 2863 31.21 93.64 3588 9783 41.14 43.95] 4431 803 9.20 1317 18.78 20.17 2348 26.64 2051 3224 24.74 87.02 3008 4247 44.684 4565 Boson §20 9.87 1347 1797 2.90 2421 2145 9047 2927 584 3820 G02 4279 46.15) 47.25 E ff eresinaicates min recommended pich clam. LENGTH CORRECTION FACTOR (C2) T "oyraricaty balanced sneover ore recomended BELT NO. 120 128 144 188 173 aD «185-210 240-270 800380 860-380 4e0 4B S40 GOD Filch lente 187 3340 8747 4102 4483 4861 S042 5423 8185 6047 709 BA71 9233 G99 10757 12281 13605 15929 a 086 087 090 0.92 0.99 084 096 0.99 100 10 105 107 108 441 192 1.16 118 120 Triple strand 1000 300) 200 100 70: 8 07 0s 03 02 oF 07 0.05 0.03 kW 700: 500: 300. 200: 100. 70 30 07, 05 03: 02: oy 0.07- 9.03" 02. Ss ERVICE FACTOR Tyect Souced Fone Impact smeorh Sore impact jpvivgszere, gonarai machine foos, compressors, generat Je’ machoos. gonate! [mach ol Larpoimose: [es ot purge, gets Iinachines with soverte of ftarge ompact loads ROLLER CHAIN PROVISIONAL SELECTION TABLE Doubie Singio stand stand RW 400) 300} 200] 0.0 3 § 7 10 20 30 5070100 200 500 30070 1000 2000 10 3 5000 1 3000, 7000