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gear train engineering 3
- Thread starter bsmet95
- Start date
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bsmet95,
You need to provide more information about your gears.
What are the number of cycles at that load?
What is the pitch line velocity and contact ratio? Dynamic loads will increase your stresses.
Do the gear teeth experience reverse bending?
What application are these gears used in? If high reliability is required, you will need to apply a suitable FoS.
How accurate is the mesh geometry of your gears under load? And is that load well distributed across the gear face?
65 KSI bending is pretty high, even for premium, high quality gear steels like vacuum melt 9310. 9310 is only good for about 55KSI in bending if you have reversing loads. If you don't have reversing loads, you might push it to 60KSI.
As for Hz stress, the endurance limit for carburized 9310 is around 185KSI. At 225KSI, your number of load cycles is probably less than 10^7.
Here's some info on carburized 9310 VAR:
You need to provide more information about your gears.
What are the number of cycles at that load?
What is the pitch line velocity and contact ratio? Dynamic loads will increase your stresses.
Do the gear teeth experience reverse bending?
What application are these gears used in? If high reliability is required, you will need to apply a suitable FoS.
How accurate is the mesh geometry of your gears under load? And is that load well distributed across the gear face?
65 KSI bending is pretty high, even for premium, high quality gear steels like vacuum melt 9310. 9310 is only good for about 55KSI in bending if you have reversing loads. If you don't have reversing loads, you might push it to 60KSI.
As for Hz stress, the endurance limit for carburized 9310 is around 185KSI. At 225KSI, your number of load cycles is probably less than 10^7.
Here's some info on carburized 9310 VAR:
carburized
Mechanical
You could use 9310H, aircraft quality steel grade 2. It has excellent properties. When carburized to Rc 60-65, and groung, depecits very good strength properties which you need. Also keep in mind, if gear is in revers bending you need to use 80% of the stress.
Designmechman
Mechanical
- Sep 6, 2007
- 10
Thanks for that, what i gathered is that its too simple (the gear trains solution). What i would like to know is calculating Epicyclic Ratio of 1:1500. I looked on the net but couldnt even understand how its all done.
1) There is an input shaft horizontal 40mm dia with spiral spring mounted on it. This is to connect to epicyclic gears.
2) There is an output shaft vertical which has a spinning disc on top 15cm dia.
3) Gear ratio of input to output must be 1:1500
Please hwlp me calculate the number of teeth and whatever is necessary like diameters of all gears etc. Remember the spinning disc on top, is 15cm dia, so cant have the gears too big in dia.
Once this is done i will model it all in solidworks.
Work deadline for this is in two days, please help!!!!
1) There is an input shaft horizontal 40mm dia with spiral spring mounted on it. This is to connect to epicyclic gears.
2) There is an output shaft vertical which has a spinning disc on top 15cm dia.
3) Gear ratio of input to output must be 1:1500
Please hwlp me calculate the number of teeth and whatever is necessary like diameters of all gears etc. Remember the spinning disc on top, is 15cm dia, so cant have the gears too big in dia.
Once this is done i will model it all in solidworks.
Work deadline for this is in two days, please help!!!!
Designmechman,
To estimate involute gear tooth size and face width, you will need to provide much more information.
What type of gears do you want? Parallel shaft axes, perpendicular shaft axes, offset perpendicular shaft axes, etc.
You have given the desired gear ratio, but how much power or torque is to be transmitted? And at what input or output speed? Is efficiency important?
How many hours or load cycles, and at what duty cycle, must these gears operate for?
What type of environment do these gears operate in? Grease lube, splash oil lube, pressure/recirculating oil lube, etc.
And most importantly, if I design these gears for you, what's in it for me?![[2thumbsup]](/data/assets/smilies/2thumbsup.gif "[2thumbsup] [2thumbsup]")
To estimate involute gear tooth size and face width, you will need to provide much more information.
What type of gears do you want? Parallel shaft axes, perpendicular shaft axes, offset perpendicular shaft axes, etc.
You have given the desired gear ratio, but how much power or torque is to be transmitted? And at what input or output speed? Is efficiency important?
How many hours or load cycles, and at what duty cycle, must these gears operate for?
What type of environment do these gears operate in? Grease lube, splash oil lube, pressure/recirculating oil lube, etc.
And most importantly, if I design these gears for you, what's in it for me?
Designmechman
Mechanical
- Sep 6, 2007
- 10
Thanks for the reply and an informative brief on what considerations need to be considered. To be honest I dont know much about the information you gave but I hope the following helps.
Torque on input shaft which is 40mm dia is 10.2 Nm which is horizontal going into gearing system. Then output speed on spinning disc is to be 3000RPM for as long as possible. Effiency is estimated at 20-30%. Also energy from the spring to rotate input shaft is 835J, this must be enough to overcome gear losses as well as rotor inertia as well as aerodynamic drag.
I think it will use a perpendicular shaft axes.
By the way whats the formula to calculate aerdynamic drag and rotor inertia of a spinning disc 15cm dia and 2 cm thick??
Thanks
Torque on input shaft which is 40mm dia is 10.2 Nm which is horizontal going into gearing system. Then output speed on spinning disc is to be 3000RPM for as long as possible. Effiency is estimated at 20-30%. Also energy from the spring to rotate input shaft is 835J, this must be enough to overcome gear losses as well as rotor inertia as well as aerodynamic drag.
I think it will use a perpendicular shaft axes.
By the way whats the formula to calculate aerdynamic drag and rotor inertia of a spinning disc 15cm dia and 2 cm thick??
Thanks
As tbuelna says, "what's in it for me?".
To calculate a complete gear train is long in the time, not only when doing the calculus. It has a very important time to prepare yourself for doing it. You haven't done a normal question, you have asked to do our job for free.
If you are doing the calculus and you have a question, please ask for it and you are going to have an answer. But if you want a complete calculus for free, you are saying that our job has no importance.
To calculate a complete gear train is long in the time, not only when doing the calculus. It has a very important time to prepare yourself for doing it. You haven't done a normal question, you have asked to do our job for free.
If you are doing the calculus and you have a question, please ask for it and you are going to have an answer. But if you want a complete calculus for free, you are saying that our job has no importance.
Designmechman
Mechanical
- Sep 6, 2007
- 10
Quick question: I have a spwound spiral spring sitting on a shaft and when it unwinds it delivers 10.2Nm Torque input. This torque goes through gearing system and eventually rotates a disc at the top. Because the spring releases energy so fast the speed is not controlled. How can i control the speed of unwinding to get a constant rpm at the rotor of say 3000RPM??? All the solutions have to be mechanical and no electric parts
Thanks
Thanks
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