TA201 ME Project 2006-07 / II Merry-Go-Round Amit Verma - Y5060 Chintalagiri Shashank – Y5157 Kritika Bharghava – Y5235 Kritika Kashyap – Y5236 Rahul Kumar – Y5343 Acknowledgement We are grateful to Our Tutor, Dr . Sarkar and our guides in the TA Lab for their irreplaceable help and valuable guidance . We greatly admire his patience and understanding in helping us out whenever any difficulty came in our way. We also thank the other guides in the ME lab who provided help and assistance as and when needed. Last but not the least, we thank our instructor, Dr. V K Jain for providing us with such a wonderful platform to give our ideas a shape . Objective To make a working model of a merry-go-round with rides having two motions. One motion of chairs about their own axis and another vertically up and down motion of the horses. Motivation Joy rides have always tempted the young and the old alike. When given the opportunity to make our very own machine which used power transfer mechanisms, the Merry-go-round popped into our minds, ideal for our needs with its repetitive motions – rotations along its primary axis and the reciprocating movements of the 'horses' in the vertical direction which is also tied in to the primary motion of the Merry-go-Round. In addition, we also added a couple of rotating chairs, which rotated about their own axis while revolving around the center of the machine. Introduction and Mechanism Description A 40 toothed bevel gear along with a 20 toothed pinion fixed with the handle is the basic element that is responsible for the rotation of the main shaft and also responsible for all other motions in the model, directly or indirectly. Above this is another assembly of a fixed bevel gear of 40 teeth and two pinions of 20 teeth each. These pinions have horizontal shafts passing through them which are attached to angles. these angles in turn are connected to a plate on which the chairs which rotate about their own axis are mounted.this assembly is responsible for the rotation of chairs . The mechanism to move the horses up and down was inspired by a crankshaft. The rotating motion of the shaft which is powered by the rotation of the platform about a fixed gear is converted to oscillatory translatory motion by means of a link system composed of two free to rotate joints. MANUFACTURING PROCESSES USED The following manufacturing process were used: Lathe It was used for the following operations: 1) To manufacture gears. 2) To file the shafts. 3) To reduce the cross section of the shafts as per the needs. Milling: We use milling machine for the purpose of teeth cutting of gears. Drilling: It was used to drill holes of various sizes in: 1) Base for fixing the shafts. 2) Shafts. 3) Gears. Tools Used During Manufacturing Tools used on Lathe 1. Single Point Cutting Tool on Lathe Machine 2. Three & Four Jaws Chuck 3. Dog Plate 4. Center Drill 5. Spanner Drilling tools 1. Drill chuck with key 2. Drills (in mm): 3.0, 3.3, 4.5, 5.2, 6.5, 7.0, 8.0, 12.5, 12.7 Miscellaneous Tools 1. Spanner Set 2. Screw driver 3. Heck Saw 4. Dog Carrier 5. Vernier Caliper 6. Steel Scale (12”) 7. C Clamp 8. Hammer 9. Center punch 10. Round File 12” 11. Bastard Files (Smooth & Coarse) 12. Knife Edge files 13. Tap set (¼”, 3/16”) with handle 14. Marker 15. Pliers , Vice etc. Cost Estimation Sr. Heads of Expenses Cost per Unit Number of Net Cost No. (Rs.) Units (Rs.) 1. Mild Steel 35/kg 13.75 kg 481.25 2. Electricity Cost-Lathe 50/hr 15 hrs 750 3. Electricity Cost- 75/hr 5 hrs 375 Milling 4. Electricity Cost- 40/hr 2 hrs 80 Drilling 5. Electricity Cost- 30/hr 1hr 30 Cutting 6. Nuts and Bolts 60/kg 0.15 kg 9 7. Unskilled labor 95/day=11.875/hr* 5 men x 7labs 1246.875 x 3 hrs/lab =105hrs 8. Skilled Labor 150/day=18.75/hr* 6 hrs 112.5 Total 3084.625 *1 day taken as 8 hrs/day of labor Overhead expenses: 5% of Total Cost = Rs.154.23 Final Cost : Rs. 3238.85 Approximate Cost of the Project: Rs. 3300/- MANUFACTURING DIFFICULTIES • Dimensional accuracy: - Moments when we needed two holes with a common constraint, it was necessary to make them properly aligned so as to fulfill that constraint. This was the time when we faced difficulty in maintaining dimensional accuracy. For example while drilling two holes on different angles to make the shafts pass through them and rotate smoothly. • Link Mechanism: - In order to rotate freely it was important to have some gap between the various parts of the link mechanism, but it was also necessary to joint the mechanism with other parts. Screws available in the lab was not serving this purpose in our design so we used rivets and washers for this. • Welding: - According to our design one gear was to be welded with the base part. It was difficult to weld that gear because teeth of other gears were susceptible to be spoiled by the extra molten metal coming out from the welding region. We overcame from this difficulty by covering them by wet clothes, but while welding central passage for main shaft got misaligned. We drilled that passage and extra material came out and it became proper. • Machine availability: - Non-availability of a particular machine at the time when it was required affected manufacturing time. We could not do parallel machining of independent parts. All parts were serially processed and assembled and total time in finishing our project increased reasonably.
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