High speed linear actuator required

[khonfahm]

Hi all,

I'm basically after a linear actuator on steroids.

Here are the required specs:

0-80mm stroke, 1040N Force, 0-10m/s speed.

I have found a few products that would almost be suitable:

http://www.tacrockford.com/product/...motors/oswald-lins-cylindrical-linear-motors/

But they do no meet the requirements of opening at 10m/s...

Background of use of product:

I work for an electrical switchgear company. We are basically looking at developing some new linear switches, and require a mechanism that can be used to test some new concepts.

I've been searching and contacting companies for the last two weeks have pretty much just gone around in circles.

Do you have any advice on how I can approach this problem?

Thank you in advance.

 

[MikeHalloran]

Uh, yeah.

Before you get all lathered up about electromechanical stuff, review the kinetics that Mike Kilroy outlined above.

Don't forget the time that it will take to build current and force against the inductance of the forcing device. You probably lose at least a millisecond there, but you need to work it out for yourself.

Or rent a systems guy.



Mike Halloran
Pembroke Pines, FL, USA

 

[itsmoked]

Consider the very common use of energy stored in a mass. It's extremely calculable because it follows simple kinematic equations. The standard in metal strength testing is a simple pendulum weight. You can precisely set the speed and force available by simply changing the height the pendulum is "cocked to".

The same technique is used for glass testing. A large weight lifted on a cable. The weight is dropped from an exact height and swings down in an arc to hit the glass. The weight, cable length, and height completely specifies the speed and energy at impact. You could do the same having the hammer strike a rod to impart your linear motion.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[mikekilroy]

Having never built a switchgear tester, I have no idea the requirements other what has been stated here.

Having said that, I HAVE turned off breakers and switches, and it never seemed to me I had to do it in 8 msec.

So, is it possible this may NOT be a requirement after all? Please tell us why this is required for the test; mind you, I am not saying is not required, but it is hard to understand why it would be important.

Keith's idea of hitting a nail with a hammer device sounds intriguing too.... reminds me of the hydraulic lifters in a car pushing valve up and down (sure it is on nice smooth cam but maybe something in the idea would help too..)

 

[ScottyUK]

Mike,

There's a world of difference between the speed you operate the handle and the speed at which the internal mechanism actually travels. Most breakers use stored energy in springs to provide the high speed operation, as distinct from 'dependent manual operation' types in which the contact movement is governed by the skill of the user. DMO switches have a long history of disruptive failures, often resulting in an arcing fault. DMO gear is virtually extinct these days, and that is a wholly positive step.

 

[mikekilroy]

Scotty, thanks for the info. Guess then what I don't understand is why anyone would need to test the stored energy motion part separate from the spring-energy-release part. 'Course I don't mfgr these devices so am pretty dumb on them. But what is wrong with using the scheme that does the internal flip? Obviously there is a reason, I am just really curious what it is. What exactly is being tested?

 

[khonfahm]

Scotty, thanks for explaining to Mike the difference between the operators speed and the actual mechanisms speed.

Mike - The critical component of most switchgear is the interrupting device. Some switchgear manufacturers just buy this part off the shelf. I need to test these different off the shelf solutions, and I need a device that can accommodate for varying lengths and open and close the switch to it's required specifications.

I think the simplest way to explain it is by using an analogy of a car. Right now, I want to test a 4 cylinder, a v6 and a v8 engine. I haven't decided what's best for my car yet. I need a chassis that can accommodate for all of these. Once, I have actually chosen my engine... then i will design the specific body for it.


" why anyone would need to test the stored energy motion part separate from the spring-energy-release part." ... Most of these mechanisms are very specific, and work for one specific case. Currently I need to evaluate a whole series of devices. This is a little CAD file I made earlier to show the internals of the switch.

8.333m/s - This is the time it takes for 1/2 a 60hz cycle.

 

[khonfahm]

I need to be able to open and close the switch in 1/2 a 60hz cycle (8.333m/s). If the contact seperation distance is 80 mm.. this means 10 m/s average speed + Some ridiculous acceleration/deceleration....

 

[davidbeach]

Close that fast may not be possible. Opening that fast happens when "blow open" contacts are used. The blow open contact uses the magnetic forces of high current fault to blow the contacts open before anything else even begins to operate. Anything other than magnetic response to high fault currents is likely to take longer than a half cycle.