Thin section Tapered roller bearing 2

[MarcBassett]

Does any such thing as a thin section tapered roller bearing exist? We have tried using angular contact bearings, and they are failing under the the loading, both radial and axial, that they see. Size wise, I'm looking at an ID of 1.5", OD 1.75", thickness of about .125 to .25". If something doesn't exist, is it possible to make it.

 

[MarcBassett]

Oh, and it would need to be capable of spinning up to about 260Hz (~16000RPM), for about a minute.

 

[israelkk]

You can try full complement bearings (without cage) this will allow many more balls in the bearing allowing higer loads. I am not sure about the ~16000RPM but since it is for 1 minute its probably OK. You can call the bearing manufacturer such as Barden and ask if they can supply the same bearing as full complement, usually it is no probelem.

Are the running and starting torque values important?

How much is the load compared to the C and Co of the bearing?

What is the failure criteria?

 

[diamondjim]

I would think you need to consider
a bushing or jewel bearing. The
16,000 rpm requires a cage or some sort
of separator. What kind of lube is
being used? If you can conceive of it,
it can be made. No load requirement?

 

[strokersix]

Does it have to be a rolling element bearing? What type of lubricant is possible?

 

[MarcBassett]

As far as loading is concerned, the bearings must survive being shot out of a gun. This means about 20000 G loading at gun launch in the axial direction, as well as a load due to buffeting inside the barrel on the order of about 1000G. These loads, however, only act on the bearings during gun launch, before the nose section (~1lb) has a chance to spin relative to the rest of the projectile. The original idea was to have a spring compress and have the two pieces bottom out on one another, changing the load path from through the bearings to through the shoulder contact point. After several shots with this configuration, we were unable to acheive relative spinning of the nose section.

 

[MarcBassett]

Ok, just asked around to get some more clarification on the loading. It appears we plan to design the bearings to handle a load of up to about 400 lbs. This is the force that it takes to compress the spring mentioned above to flat to allow the two pieces to bottom out on one another. Radial loading would not necessarily be that high. The friction between the two contacting pieces during gun launch would keep the loading down to nearly zero. However, if the two pieces come apart at all due to bending of the nose piece or anything else, the bearings would need to be able to support as much as possible. So, the design factors appear to be, in order of importance: size, axial loading, and then the highest radial loading that is available that fits the other two.

 

[Hippo41]

You need to be talking to either KAYDON or Timken Aerospace.

Lester Milton
Telford, Shropshire, UK