Planetary Gear

AIM:-To create 3-D model of planetary gears and perform motion analysis,plot anular velocity of the part that is given input motion.

GOVERNING EQUATIONS:-

             m=p/N

             where m is module  units:-mm/tooth.

                        N is number of teeth.

                       p is the pitch diamter.

        CALCULATING THE PLANETARY GEAR TEETH WHEN SUN GEAR ANF RING GEAR TEETH              IS GIVEN:-

                  R=2P+S

                 where R =Number of ring gear teeths.

                            P=Number of planet gear teeths.

                           S=Number of sun gear teeths.

THEORY AND EXPLANATION:-Gears aremainly used to transmit rotatry motion from one shaft to other shaft such that the ratio of angular velocity remains constant.Gears have an involute profile .Every gears when meshed the pitch point is constant on the line of action.This is known as law of gearing .The diametrical pitch of the mating gears must be equal then only gears mesh and transmit power smoothly without any vibrations and misalignments.Planetary gears consists of ring gear ,planet gears ,sun gears.Planet gears are mounted on a movable arm  which itself may rotate relative to the sun gear.Planetary gear trains provide high power density in comparison to standard parallel axis gear trains. They provide a reduction in volume, multiple kinematic combinations.The load in a planetary gear train is shared among multiple planets; therefore, torque capability is greatly increased. The more planets in the system, the greater the load ability and the higher the torque density. Disadvantages include high bearing loads, constant lubrication requirements, inaccessibility, and design complexity.

OBJECTIVES OF THE PROJECT:-

1. Creating the planetary assembly model.
2. Plotting various graph like angular velocity , contact forces etc.
3. Giving the input to one of the gears and obtaining the motion  acoordingly by constarining the other gears.
4. Calculating the planet gear teeth and pitch diameters of the gears.

BODY OF THE CONTENT:-

Importing the gears from design library:-

1. Click on design library which is on the right side of the SOLIDWORKS desktop.
2. Select toolbox .
3. Select ANSI metri,then choose power transmission.
4. Right click on the desired gear and create the part files of the corresponding gears so that cab be later for assembling.
5. Selected spur gear having module=2.5mm,number of teeth =14 which is used as the sun gear.
6. Selected spur gear having module=2.5mm,number of teeth =16 which is used as the planet gear.
7. Selected  internal spur gear having module=2.5mm,number of teeth =46 which is used as the ring gear.

Creating 3-D model of the carrier:-

1. Open part file and coose front plane to sketch.
2. Sketch the carriage using circle command whose diamter is equal to the nominal diamter of the planet gears.
3. Use circular pattern command to repeat the sketch to required number .
4. Use 3 point arc and make it tangent to the outer circle ,repeat the pattern using circulat pattern ,exit the sketch.
5.  Use extrude command and extrude it to 10mm the entire region ,deselecting the holes.
6. Then use extrude command to extrude the 4 holes to 50mm so as to mount planet gears .
7. Extrude the centre circle to 200mm on opposite direction to the previous ones.
8. Apply fillet of 2mm radius on either sides of the carriage.
9. Use chamfer on the longest extruded part of 2mm, anlgle =45degrees.
10. This enables us to create 3-D model of carriage.

CALCULATION OF PLANET GEAR TEETH:-

R=2P+S

where R=number of ring gear teeth

           P=planet gear teeth

          S=sun gear teeth 

CALCULATION OF PITCH CIRCLE DIAMTER:-

module=pitch diameter/number of teeth.

 

ASSEMLY OF THE PLANETARY GEAR:-

2. Import all the individual part model and using mate constrain the individual components so that when assemblied is under motion study it yields expected end result.   

MOTION ANALYSIS:-

1. Now select the SOLIDWORKSMotion and start the motion study.
2. Now select the motor option and apply it to one of the gear as given in the task .
3. Now choose solid contact and make solid contact between all the components so that motion can be transmitted .
4. Now selelct frames/sec and use precise contact so that we come to know about the mechanism in detail and understand it accurately.
5. Now select results and plots to obtain contact foreces ,angular velocity of the ouput component.
6. After the motion analysis the results must be exported to excel sheets.
7. The above steps are repeated according to the input given tp various gears and obtaining the output.

PLOTS :-

• The above plot is obtained when the input is given to sun gear and carriage is fixed.
• In this case the planetary gears rotates about their own axis at a rate determined by the number of the teeth in each gear due to gear ratio.

•  The above plot is obtained when input is given to sun gear and ring gear is fixed.
• SO in this configuration of gears the speed ratio obtained is loweer than the above case due to decrease in gear ratio.

 

• The above plot is obtained when input is given to ring gear and sun gear is fixed.
• In this configuration of gears the speed ratio obtained is maximum of the above two cases due to increase in gear ratio.

 CONCLUSION:-

1. Createed the 3-D part models and assembled them.
2. Performed the motion analysis.
3. Obtained the grapgs of angular velocity for the ouput part.
4. Compared the plots .