[b] Taper Connections for Mechanical/Structural Applications [/b]

[delachea]

I am looking for information and/or direction to literature on recommendations of using taper connections for pipe or round tubing to be used for structural applications. For example, I would like to use tapered connections to support a pipe at each end – just as a beam fixed at both ends. Would Taper Morse insure tight joints that can carry bending moment? Information desired is regarding the feasibility in using taper connections for any structural applications. Does this type of connection would insure long term joint integrity and sustain shear and bending moment?

 

[arto]

You might want a threaded taper pin like the AN-386 with a castlenut & cotter pin. Reid Products makes them:

http://www.reidproducts.com/an_series.htm#AN386

The pin might be plenty strong, but check for tearout in the pipe

 

[delachea]

Thanks Arto. Take a look at the drawing... You might better understand what I am looking for:

http://users.polymic.com/alex/transfer/taper.JPG

 

[GregLocock]

The joint will tend to work itself loose over time if the load varies, or, probably, even if the load remains constant. The addition of the taper itends to spring the joint apart (this is how you can get a taper out of a blind hole if you only have a hammer).

The only saving grace is if the taper or the socket are relatively elastic then you may be able to assemble it with enough force to keep it locked up.


Cheers

Greg Locock

 

[delachea]

Thanks Greg,
What do you think would happen then if I secure the connection on each side with a bolt in the axis? Don't you think if anough torque is applied I can keep the connection able to resist moments?

 

[GregLocock]

That will be fine. The moment capacity of the joint will be very slightly less than that of the cylindrical joint, but I think an axially bolted taper will be a much better, stiffer joint. Do try and get some compliance into the socket or taper, it will help with the load sharing.

Incidentally please don't try and use html in the thread title, it doesn't work, it's rude, and it looks messy.

Cheers

Greg Locock

 

[arto]

Looking at the sketch, a couple of things come to mind:
-You need a way to positively retain the end plates. Friction alone it probably not enough. [If the taper angle tangent is greater than the friction coefficient, it'll slip.] A co-axial thread is a good way {like on the AN-386]

- check for Hertzian contact stresses to make sure it doesn't "bell-mouth."

- you can't have more than one of these between two parts - only one will be tight due to tolerances.

 

[delachea]

Thanks Arto,
However, I am not sure I understand well how you would use the part 'AN-386'. I think a standard bolt would do the job..

http://users.polymic.com/alex/transfer/abm1.JPG

http://users.polymic.com/alex/transfer/abm2.JPG

http://users.polymic.com/alex/transfer/abm3.JPG

Cheers,
Alex

 

[arto]

make the end LIKE an AN-386 pin - weld on or machine

 

[arto]

Note- the AN-386 #'s are basically Brown & Sharp Taper numbers with a pull-up thread on the end.
[Why reinvent the wheel? Great-Grandpa's tax $$ probably paid for the design - Grandpa probably flew it! ;-) [The dwg's date is 1943]

The official spec has been superceded to NASM386, but you can get the prior gov't dwg @:

http://assist.daps.dla.mil/online/start/

if you're registered there.

 

[delachea]

Thank you very much Arto for this valuable info!!!! I'll register right now to ASSIST as well!
Cheers,
Alex