THOERY OF MECHANISMS AND MACHINES Module-06 The Big Picture Instructed by: Dr. Anupam Saxena Associate Professor Department of Mechanical Engineering Indian Institute of Technology Kanpur FB 361 Prepared by: Abhishek Sharma Final Year Dual Degree Student Department of Mechanical Engineering Indian Institute of Technology Kanpur FB369

M05- Recap Velocity & Acceleration Analysis Basics Velocity Analysis using IC method Graphical Velocity Analysis Graphical Acceleration Analysis Assignment # Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 2

The Big Picture What is our aim in this course? What are we teaching you? Where will it lead to? What skills will it help you acquire? Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 3

What Does it Take to Build a MECHANISM Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 4 Synthesis?

TYPE SYNTHESIS What will you use in your mechanism? Most suitable for your application? Rotation to rotation/translation/combination or other way round? Shafts very far or very close? Rotate in same or opposite direction? Multiple shafts? Curvilinear output? Specific displacement-time/velocity-time curves? Energy Storage? Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 5 LinkagesGearsBelt-Pulley Chain- Sprocket Cam- Follower FlywheelsCompliance

Linkages Rotation to translation/rotation (partial/full)/specific output curves or other way round? Specific force output to input characteristic? Specific motions? You need to be equipped with tools enabling you to analyse kinematics & dynamics of linkages. That’s what we’ve been teaching you! Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 6

Gears SpurHelicalBevel Worm Gear Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 7

Gear Trains SimpleComplexEpicyclic Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 8

Belt Pulley Open BeltCross Belt Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 9 Flat Belt V Grooved Multi-Grooved Timing Belts Parallel/Non-parallel Shafts Double/Multiple Shafts

Chain-Sprocket Drive Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 10

Cams Radial Face WedgeCylindricaletc Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 11

Flywheels Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 12

Compliant Mechanisms Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 13

NUMBER SYNTHESIS Once you’ve chosen what to use in your mechanism, you choose how many of them do you need? A number rotating shafts with different ratios, direction of rotation, reduction ratio etc. help you choose the number. Number of gears if you want to rotate two shafts in same direction with 1:4 output to input speed reduction? If you need something which only a double rocker mechanism can do, how would you drive the double rocker continuously? Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 14

TOPOLOGY SYNTHESIS Once you’ve found the numbers and types, in what sequence, positions and orientations will you arrange them to reach the desired result? This is usually done along with the number synthesis. Remember Remember the 5 th of November, The Gunpowder Treason and Plot. I know of no reason why this very treason should ever be forgot :P “Mechanism design is iterative. You do all these analyses once, don’t reach the result, you do them again in a different sequence maybe with different choices. But you keep doing it TILL YOU REACH THE RESULT” PS. Watch V for Vendetta :P Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 15

DIMENSIONAL SYNTHESIS Type? Check Numbers? Check Topology? Check Once we’re done with all the above, we need to work out the dimensions. Scale of operation? Output forces and moments? Specific motion or path? For linkages, we categorize them into the following: Path generation Motion generation Function generation Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 16

Path Generation You’re given a specific path to be traced. Design a mechanism a point on which traces that very path! Example- Someone did this when he was asked to trace a straight line: Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 17

Motion Generation What if along with the path, you’re given specific orientations to maintain while traversing a path or pass through certain locations? Example: Put my luggage in the luggage box? Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 18

Function Generation Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 19

DIMENSIONAL SYNTHESIS See you in next class. Collect your Assignment #1 from the front row. Cheating is sin, next time we find an answer copied, whole assignment would be graded to zero Dr. Anupam Saxena, Abhishek Sharma IIT Kanpur 20 Our Next Stop