Need a torsion spring 100 NM at 45 degrees

[dteich]

Application is to protect an installation from abuse. The driveshaft will be connected to the external arm through a torsion spring. At 45 deg rotation of the arm we need at least 100 NM resistance. It would be great if we could allow 120 degrees arm rotation without killing the spring, at least for 50 times.

Space is somewhat limited -- maybe 12" length limit. Diameter has to be limited to 2" because the pivot point is close to the ground

Looking for a solution or suggestions.

 

[israelkk]

If you need 10 NM at 45 degree roation then at 120 degrees it will give 267 NM? is this what you mean?
How many spring you need?

 

[dteich]

Hi Israel,
We will need a few hundred in the first year, then hopefully more. It is a volume, low cost product.
Does the quantity affect the conceptual solution?

 

[dteich]

... as far s the torque at 120 degrees, I think that you mean that the torque will be 26.7NM. Right? If so, that is indeed my expectation.

 

[israelkk]

In your initial post you wrote 100 NM at 45 degree. The 10 NM in my post is a typo error instead of 100 NM. Therefore, at 120 degree the torque is 267 NM.

 

[dteich]

yes you are right. I need the 100 NM torque. Any solutions?

 

[israelkk]

Is the 120 degree a must or you can be satisfied with maximum 45 degrees and 100 NM?

 

[dteich]

Lets start with a 90 degree limit. If this is a problem, lets start with 45 deg and then I can see if I can double up.

 

[israelkk]

Low cost it will not be in such volumes that will be probably manufactured by hand tools. Secondly, the large torque at small space require special secondary operations after initial spring manufacture. It will require some NRE process to find the correct initial spring configuration before the secondary operation to assure final spring properties after the secondary operations.

It seems that the 120 degree is possible with the above mentioned points.

You didn't mention any environment (temp, corrosive, etc) requirements.

 

[dteich]

The spring is a non-critical component, in a typical outdoor environment. Not corrosive, just -20C to +70C It will not be an issue of the torque changes 10%. The spring will see no action except when the barrier that it drives is attacked.

 

[israelkk]

As you probably understood it is a non-standard custom designed spring. I don't believe you can find a standard off the shelf such a spring. To approach a spring designer or manufacturer you need to be able to clearly define the spring requirements, specifications and probably how it will be used/installed. Not all spring designers or manufacturer will be able to come with the solution. The design process is quite tricky and need some specific experience and expertise which is not common in the design process and manufacture of torsion spring design.

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