ENB215-T1-S2-2010

ENB215-T1-S2-2010 - Surname Given Name/s III-II.-...

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Unformatted text preview: Surname Given Name/s III-II.- Examination Paper SEMESTER: SECOND SEMESTER EXAMINATIONS 2010 I UNIT: EN8215 FUNDAMENTALS OF MECHANICAL DESIGN - THEORY 1 DURATION OF EXAMINATION: PERUSAL: 10 MINUTES WORKING: 2 HOURS EXAMINATION MATERIAL SUPPLIED BY THE UNIVERSITY: EXAMINATION BOOKLETS METRIC SERIES OF PREFERRED NUMBERS - ONE (1) PAGE ATTACHED DRAWING SHEET (ONE (1) PAGE) EXTRACTS FROM AUSTRALIAN STANDARD AS 1654.2 - 1995 ISO SYSTEM OF LIMITS AND FITS ISO 286-2 : 1988, AND ROLLING BEARING CATALOGUES EXAMINATION MATERIAL SUPPLIED BY THE STUDENT: WRITING IMPLEMENTS CALCULATORS - ANY TYPE PRINTED TEACHING AND LEARNING RESOURCES AVAILABLE FROM THE BLACK BOARD SITE FOR ENBZI5 ARE PERMITTED (THIS MATERIAL MAY BE ANNOTATED) INSTRUCTIONS TO STUDENTS: Students are prohibited from having mobile phones or any other device capable of communicating information (either verbal or written) in their possessions during the examination NOTES MAY BE MADE QNLX ON THE EXAMINATION PAPER DURING PERUSAL TIME ALL TWELVE (12) QUESTIONS ARE TO BE ATTEMPTED WRITE ONLY IN DARK BLUE OR BLACK INK OR BIRO PENCILS ARE ONLY TO BE USED TO DRAW DIAGRAMS PLEASE ENTER YOUR NAME AND YOUR STUDENT NUMBER ON THE FRONT OF YOUR DRAWING SHEET AND ENCLOSE WITHIN YOUR EXAMINATION BOOKLET UPON COMPLETION MARKS FOR EACH QUESTION ARE AS INDICATED Queensland University of Technology GUT GUT Gardens Point Kelvin Grove Gear-shaft assembly. A gear-shaft assembly for an output shaft of a gearbox is shown in Fig. 1 below. It transmits 4 kW of power. The speed 11 of the shaft is 250 r.p.m. The helical gear has 67 teeth with the module of 3 mm and helix angle of [3 = 15°. The gear-shaft assembly rests on two bearings. The radial force F, and the axial force Fa lie in the horizontal plane and ' the tangential force F, acts in the vertical plane. Power P is transmitted from the gear to the output end of the shaft where a coupling is installed. Assume the endurance limit for the shaft material 0} = 390 MPa, and the safety factor Sr = 2.5. In this gearbox a standard I pressure angle of a = 20° is used, and the helix angle is \y = 15°. Helical Gear Bearing Fig. 1 Gear—shaft assembly For the given data determine the following: QUESTION 1 Pitch circle diameter of the gear, torque on the shaft, tangential, axial and radial forces on the gear. (6 marks) QUESTION 2 Support reactions on the shaft in the vertical and in the horizontal planes. QUESTION 3 (7 marks) Plot shear force Vv and bending moment Mv diagrams for the vertical plane. QUESTION 4 (6 marks) Plot shear force Vh and bending moment Mh diagrams for the horizontal plane. QUESTION 5 (6 marks) Plot twisting moments T diagram for the output shaft. (5 marks) ENB215T1.102 Cont/... QUESTION 6 Determine the resultant bending moment Mb at different sections of the shaft as: Mb=~l[(Mv)2+(Mi)2] (6 marks) QUESTION 7 Identify the critical section on the shaft. (6 marks) QUESTION 8 Determine minimum shaft diameter D for the critical section and using the metric table of preferred numbers (attached) assume preliminary diameters for all shaft shoulders. Make a hand sketch of the shaft with major dimensions. Use the following formula: D3 = (104'Sf/ 6e)-Ks-K"I(M b2 + T 2) (films) Where: 6. is in MPa, MI, and T in N-m. Assume stress-raising factor K = 1.8, and size factor Ks = 1.4. 11 k QUESTION9 ( mar S) Select bearings for each end of the shaft (use tables attached). Consider possible kinds of bearings that can be used and recommend the most suitable for this case. Assume the bearing life for 8-hour shift use in general industry. (1 1 marks) QUESTION 10 Using bearings dimensions finalise the shaft diameters and make a hand sketch of the gear-shalt assembly giving diametral and linear dimensions. Remember to consult the metric table of preferred numbers. (8 marks) QUESTION 11 Suggest suitable fit for the joint of the gear with the shaft. Take values of deviations from tables provided and calculate clearances (interferences). Make a hand sketch of the fit showing tolerance zones and relevant parameters (dimensions, deviations, tolerances, clearances / interferences). (8 marks) QUESTION 12 Using the A4 drawing sheet attached to the exam paper produce in pencil the part drawing of the shaft. Select the scaling factor, fill the title block and put major dimensions (longitudinal dimensions and shoulder diameters) and the fit selected. Do not put surface roughness. (20 marks) Totalmark:[6+7+6+6+5+6+6+11+11+8+8+20=100] The total exam mark is weighted 50% of the final mark for ENBZI 5 unit. ENB215T1.102 END OF PAPER (i) f Preferred Numbers 1c Series 0 Metr Sizes 10 to 100 mm Sizes 100 to 1000 mm Sizes 100 to 1000 mm Sizes 1 to 10 mm rd 5 5 o 0 7 9 0 00 00 0 46 28 8 77 88 9 o 9 8 2 6 67 O 2 8 4 4 m m w m 334 4 7 8 d $282828 82828282828 5555 001122 34455667788 1234 1111111111111111111 2222 5 0 0 7 1 3 1 2 2 t 50 0 0 0 0 O 0 0 O 0 0 0 1 1 1 1 1 1 1 1 1 1 2 2 .m 3 3579136 46 4 6 8 1111222 33 :43 6 M7M8 82 2 2 8 34 6 7 7 5 5o 05 3 45 77 .m 3 35.7.9. 6.28.2 2 5. 5. 111.1 2334 5 7 9 1. 32 8.5. 1 12 23 7 Ll $2 1. 2 3 a 0 7 3 =50 2 2 Ohm m. m _ _ _ _ - - — — — — — — — — - — — — - _ — _ — E3!"- _ 20 — _ _ — — 20 _ — 850 — _ _ EH. — — — — — - _ _ — — 0 0 0 2 8 2 3 3 5 50 — 280 _ __ _ _ __ _ - mu — — — Im _ _ — _ — — — _ 32 92 Choice _ _ 105 _ _ _ 1 15 — _ 125 _ - _ 135 _ - - 145 _ — _ 155 — _ — 165 — — 0 3 ChOIce EE- — — _ — _ _II_ — — _ _ — _ _ - - _ — — - — _ E. — _ _ _ _ Choice 1 ENB215T1.102 ...
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This note was uploaded on 11/03/2011 for the course EN 40 taught by Professor Mcgregor during the Three '10 term at Queensland Tech.

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ENB215-T1-S2-2010 - Surname Given Name/s III-II.-...

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