Pitch angle thread

[gjplive]

Hello

I have an impeller connected to a shaft (threaded)
if I want to disconnect the impeller ,it stuck to the shaft, because of the torsion the impeller produced.
Now I want a new connection, and want to increase the pitch of the thread, so the impeller won’t stuck again if you disconnect it.
Anyone an idea how to calculate this pitch?
I think it could be calculated by a formula without the forces on the shaft in it..
I just need a pitch angle
it doesn't need to be a standard..

Greetings Gj

 

[drawoh]

gjplive,

Read up on self locking worm gears. This should be written up in your machine design textbook, along with the required math.

The whole point of screw threads is that the pitch angle is self locking. I think you need a few way to connect your impeller. Does your current design have adequate wrenching flats?

JHG

 

[MRSSPOCK]

Can you please make the question more simple. It is confusing how you ask it.

 

[FreddyZ]

Perhaps a tapered shaft would do what you need, as used on small engine flywheel to crankshaft connections. Typically keyed with a Woodruff or half moon key.

 

[MintJulep]

Use a 90 degree pitch angle and call it a spline?

 

[Tmoose]

Were you able to remove the impeller by some means? Was the interface corroded, or the threads galled? I'd say that might be a mis-application or installation problem.

Is this a commercially available pump? Was it rebuilt with bootleg or otherwise non-OEM parts?
What are the manufacturer's instructions for removing the impeller? They may have tools available to allow applying sufficient torque or even some impact necessary to remove the impeller that has been subjected to normal operation.

Taper fits sometimes require impact or shock to remove.

 

[MikeHalloran]

Before breaking out the impact wrench, try turning the impeller the _other_ way.

Left hand threads are not uncommon.



Mike Halloran
Pembroke Pines, FL, USA