Design of tapered shaft friction coupling 1

[kyleShropshire]

I'm designing a wheel that can be moved along a machined tube.
I have chosen an 8deg taper between my split collar and clamp plates but that was just a guess.
Are there any guidelines on split friction clamps that might reduce the number of design iterations I have to build and test?
Specifically regarding the taper angle and any heat treatment the split ring might need to allow sliding on the tube without lubricant.

Clamp must resist 12kNM wheel torque without slipping.

I have x16 M16 SHCS at 75%Proof to accommodate the joint C factor of 1.
I started with the tapered wedge calcs and radial bearing moment of friction from Gieck Technical Formulae 9th to determine the amount of friction-moment required to resist the wheel torque.

 

[TugboatEng]

I can't help with the numbers but do you plant to be able to disassemble this without cutting the wheel off?

 

[kyleShropshire]

Yes, it should disassemble when the bolts are removed.

 

[TugboatEng]

Per your drawing it will not be. Removing the bolts does not release the taper. You will need some method to drive the wedges apart.

 

[kyleShropshire]

I can thread some of the clearance holes so 2-4 M20 bolts will push it apart.

 

[TugboatEng]

As a rule of thumb, it's going to take the same amount of force to separate the taper as it took to make it. Many systems have ports and grooves that allow you to hydraulically expand the coupling so it can be separated.

 

[DAVIDSTECKER]

Have you looked at the "Morse Taper" used in machine tools?

 

[MintJulep]

Why reinvent the wheel.

QD and Taper-Loxk bushings and hubs exist for exactly this.

 

[TugboatEng]

Did you see the fastener size in the picture, M16? OP's application is quite large. I don't think there's an off-the-shelf product for this.

 

[MintJulep]

Fenner Cone Clamping elements

https://fptgroup.com/en/products/shaft-fixings/fenlock-cone-clamping-elements/

Up to 900 mm (35 in) diameter.

 

[GregLocock]

Biggest I could find was 125 mm!

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[TugboatEng]

Ok, now apply this to OP's design... Whooptie Doo you can find a tapered sleeve coupling. Does mounting a flange on a shaft solve OP's problem? OP's design is neat and compact but needs some refinement. That is all.

 

[MintJulep]

Whooptie Doo you can find a tapered sleeve coupling.

Yep, might be my strongest talent.

I don't know what the OP's root problem it, neither do you.

The OP recognizes the need to worry about design details and possibly test his design. I've suggested commercially available couplings that might be useful, at lower cost, or lower risk or faster than the design his own option. The OP is free to use that suggestion or not.

The OP's design looks really difficult to accurately align axially, but they haven't stated any alignment requirement.

 

[Jboggs]

Have you checked

http://www.ringfeder.com/?

They have been around a long time and a wide range of products.

 

[Scuka]

Any reason why you're trying to design this from scratch instead of using one of countless commercially available taper lock bushings?

 

[kyleShropshire]

This application requires a specific type of titanium to avoid contaminating the part that touches the wheels.

I will contact ringfeder and see if we can work out a way to use their design and still meet the material requirements.

 

[SwinnyGG]

Or just change your taper to 12° or more and it will be self releasing when bolt tension is released.

0°-8° = self locking

>12° = self releasing

8°-12° = somewhere in between

The higher the angle is, the less lubrication will be needed to protect the surfaces from galling during assembly.

 

[kyleShropshire]

There is a high probability of impact loading so I am attempting to keep a shallow angle to avoid excessive bolt loading. I realize there is no way you would know since I forgot to include that in my original post.

 

[LittleInch]

What is clamping what here?

The inner ring is constrained by the bolt from rotating separate to the two clamp shells no?

But is free to move axially?

When you tighten up the bolts how do you know what you're clamping? Could be the shaft or the middle ring.

Would need some very fine machining to do both to any degree of accuracy.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[SwinnyGG]

There is a high probability of impact loading

In what direction? the direction the wheel is rotating? If so, impact loading does not affect bolt tension. The load is going to be carried by the friction between the faces of the coupling.

Radially normal to the wheel? Similar story.