Geneva mechanism ppt

GENEVA MECHANISM PRESENTATION

1. Geneva Mechanism Presented by NAMAN ME-A ROLL NO. 1213397

2. CONTENTS Introduction Classification of Geneva Mechanism Working of Geneva Mechanism Advantages of Geneva Mechanism Disadvantages of Geneva Mechanism Application and Uses Future scope conclusion

3. INTRODUCTION The Geneva drive or Maltese cross is a gear mechanism that translates a continuous rotation into an intermittent rotary motion. The rotating drive wheel has a pin that reaches into a slot of the driven wheel advancing it by one step. The drive wheel also has a raised circular blocking disc that locks the driven wheel in position between steps. `

4. CLASSIFICATION OF GENEVA MECHANISM` EXTERNAL GENEVA MECHANISM In this type of mechanism, the Geneva cross is connected with cam drive externally which is the most popular and can withstand higher mechanical stresses. The driver grooves lock the driven wheel pins during dwell. During movement, the driver pin mates with the driven-wheel slot.

5. INTERNAL GENEVA MECHANISM In this type of mechanism, the Geneva cross and cam drive are connected internally in the closed box. The driver and driven wheel rotate in same direction. The duration of dwell is more than 180º of driver rotation.

6. SPHERICAL GENEVA MECHANISM In this type of mechanism, the Geneva cross is in spherical shape and cam drive are connected in externally, which is extremely rare . The driver and driven wheel are on perpendicular shafts. The duration of dwell is exactly 180° of driver rotation.

7. Working of Geneva Mechanism In the most common arrangement, the driven wheel has four slots and thus advances by one step of 90 degrees for each rotation of the drive wheel. If the driven wheel has n slots, it advances by 360°/n per full rotation of the drive wheel . Genevas are also combined with variety of other mechanism , such as four bar linkages , clutch-brake combinations , non –circular gears etc to modify the motion curves and dwell motion ratios obtained from pure Geneva.

8. Advantages of Geneva Mechanism Geneva mechanism may be the simplest and least Expensive of all intermittent motion mechanisms. They come in a wide variety of sizes, ranging from those used in instruments, to those used in machine tools to index spindle carriers weighing several tons. They have good motion curves characteristics compared to ratchets, but exhibit more “jerk” or instantaneous change in acceleration, than better cam systems.

9. Disadvantages of GenevaMechanism The Geneva is not a versatile mechanism and produce jerk. The ratio of dwell period to motion is also established once the no of dwells per revolution has been selected. All Geneva acceleration curves start and end with finite acceleration & deceleration.

10. Applications and uses It is applicable in the production industries and in automobile industries for mass production . Modern film projectors may also use an electronically controlled indexing mechanism or stepper motor, which allows for fast-forwarding the film. Geneva wheels having the form of the driven wheel were also used in mechanical watches, but not in a drive, rather to limit the tension of the spring, such that it would operate only in the range where its elastic force is nearly linear . Indexing tables in assembly lines, tool changers for CNC machines , and so on.

11. FUTURE SCOPE Design optimization of a Geneva mechanism for internal combustion engine application. Bottle Indexing and Filling Mechanism. It Can be used in Pen Changed Mechanism in Plotters . It has a great scope in automated sampling industries .

12. Conclusion Geneva drive indexing mechanism converts the continuous motion of the driver wheel into intermittent rotary motion of the gear. Cam with pin arrangement integrated with Geneva drive. Input shaft having driver wheel at one end and cam drive at the other end. Geneva drive and gears are mounted on the output shaft. By cam with Geneva drive arrangement the continuous motion of the driver wheel converts into intermittent motion of gear and chain arrangement. Due to gear rotation the conveyor belt moves and thus mechanism proves its significance.