Linear actuator: large force 100kN, small step of the thread, gearbelt

[thuaniam]

Hi brothers,

I need an electrical-mechanical linear actuator for control of a nearly static load. The head of actuator applies force to a concrete specimen through a steel spring which is much softer than the stiffness of the specimen. The target control is the displacement on the concrete specimen and it requires very high accuracy in term of displacement error. I need linear actuator with the following requirements:
- Type: Electrical-mechanical actuator
- Static load capacity: about 80kN or more
- Step of the thread: as small as possible.
- Stroke: about 50 mm
- Driven by gearbelt mechanism with ratio about 2:1 or more.
- Other preferred points: compact size, light weight, low noise when running

Could you recommend some suitable options?

Thank in advance,

Van

 

[IRstuff]

How big is the specimen? How much volume are you allowed.

TTFN
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[thuaniam]

Hello IRstuff !

Here is more information:
The specimen is a concrete bar with dimension of 100 x 100 x 1000 (mm). The axial load on the specimen can be both tension and compression but this is a static load, therefore a gap in the thread will not cause serious error in control. However, small gap in ball bearing is preferred because actuator may change its direction during control. I intend to use a step motor to control. The spring between specimen and the actuator is used to convert the large increment of the head of actuator to a very low increment of displacement on the specimen. Based on the step of the thread, the step angle of the motor and the stiffness of the specimen, I will specify the steel spring with an appropriate stiffness.

To the size of the actuator: small size ones will be preferred but it is not critical because I can arrange an appropriate supporting frame.

Thank you.

Van

 

[imcjoek]

You lost me at the spring bit.

Have you looked at

http://joycedayton.com/

?
Have you considered hydraulics?

 

[Jboggs]

I like the idea of "jack" type mechanisms like Joyce/Dayton mentioned above, or maybe Nook Industries or Duff-Norton.
You might also look at

http://www.racointernational.com/.

I've used their products successfully in the past on high load projects.

 

[IRstuff]

"The spring between specimen and the actuator is used to convert the large increment of the head of actuator to a very low increment of displacement on the specimen."

Sorry, this is not making much sense; how is the spring doing this? You talk about accuracy, but you don't offer a specification.

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[MintJulep]

" convert the large increment of the head of actuator to a very low increment of displacement on the specimen."

This describes a lever. Not a spring.

 

[GregLocock]

I think he's using the deflection of the jack to compress the spring, to apply an adjustable /desired/ force on the specimen. This seems a rather roundabout method but I'll assume there are good reasons. Normally you'd just use a hydraulic jack, where the 'spring' is supplied by the compressibility of the fluid and expansion of the barrel etc.





Cheers

Greg Locock


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

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[mikekilroy]

Could you recommend some suitable options?

No one can, sorry.

You want some force but give no spec for speed or time to do it in. Hence, with proper gearing, a 1 oz-in stepper motor can produce this 100kn force - in 17 years if you have the time. Or a 500HP motor can do it in maybe 1 second.

So do you need the 1 oz-in $ 3.oo stepper or the $ 12,000.00 motor?

Google, work, power, energy and see what all you are missing.

Sorta need to give the rest of the specs to get there from here.

http://www.KilroyWasHere<dot>com

 

[thuaniam]

Dear all,

Thank you for all comments. I have found some good options for my applications.

Van

 

[tbuelna]

Since you need your device to produce both tension and compression forces on your concrete test specimen, the design problem becomes rather complicated. For example, what type of spring do you propose to use that will work both in tension and compression?