Recommended thread profile...

[blckwtr]

What is the best recommendation for a thread with these characteristics?
* Axial translation
* High axial loads
* Material AISI 4140 18-22 HRc
* Grease/lubricant TBA
* Diameter 44 mm

 

[unclesyd]

How are you going to apply the load?

Are you pushing or pulling?

What is the magnitude of the load?

Without more information I would say look at the Acme thread profile.

 

[blckwtr]

It is going to work as a transport screw, meaning the screw has a spline on one end to prevent it from rotating, the nut applies the load. So the screw is moving axially with a "spring" between the nut and bolt.

* The load is around 44 000 lbf.
* Nominal diameter on the thread is 44 mm

 

[hydtools]

Ball screw.
For example:

http://emcorsolutions.com/ball_screw_manufacture.htm

Ted

 

[blckwtr]

No ball screw
* It doesn't fit
* Just need a suitable thread profile

* What is the best thread profile for axial loads?

 

[jbeckhou]

On some of the drilling jars we design which use a spline to prevent rotation, we use Acme-10 TPI-4G. Calculations should be done to choose the correct thread for your design.

Petrotrim Services

 

[TVP]

It sounds like you want some type of lead screw (not a ball screw), possibly a high helix version. Take a look at the Rondo and Speedy product lines here:

http://www.gewinde.ch/eng/produkte_02.aspx

There are other manufacturers of lead screws as well, such Nook Industries, Roton, Thomson BSA, etc. that have information on their websites.

 

[blckwtr]

We use Acme and Stub Acme for most of our connections, since it is flexible with regards to size, pitch etc., and you even have a self centering thread called centralizing Acme Screw Thread, also you can specify number of starts etc. etc.

Since I have entered this forum to ask experts on the area, I hoped to receive some answers which could either confirm or invalidate if Acme or Stub Acme is the best recommended practice when it comes to axial translation with high loads and not just a connection, or if some other type of thread is more suitable, like trapezoidal?!

Best Regards

Tommy

 

[unclesyd]

Checkout both these sites as each one has some good information on leadscrews. The Precision brochure has some information on different thread forms.
It's up to you and maybe a little help from the leadscrew people as to the type threads and pitch and so on. I would have all the physical attributes required, like speed, input torque, and advance, etc, and give them a call.

http://www.precisionscrewthread.com/leadscrw.html

http://www.keystonethreaded.com/index.html

 

[hydtools]

It appears the experts are saying there is no one best recommended practice.
Acme, stub acme, trapezoidal, ball screw, and even buttress.
You get to chose based on space, speed, load, unidirectional or bidirectional, vertical, horizontal, lubricated, dry, positional accuracy, manufacturing capacity, maintenance.

Ted