advice on actuators 1

[damienmorton]

I'm looking for an electrically powered actuator for use with something like a stamping operation.

It should have the following characteristics:

Needs to travel 10mm in 1s, precision of movement not so important, but should have a soft "landing" at the end of its travel.

Needs to apply a precise amount of force, up to 150N.

Needs to be durable for repeated movement: 10mm forward in 1s, 150N for 1s, 10mm back in 1s, 1s delay, repeat.

Anyone have any suggestions?

 

[damienmorton]

Er, that should 1500N of force applied

 

[Skogsgurra]

A small geared electric motor with a 15 RPM output shaft. Add a cam with the desired movement pattern that actuates either a linear plunge or a hinged arm plus tool. Cam can be laser or water cut and ground to desired finish.

Of course, you can start looking for pneumatic, hydraulic, electromagnetic actuators, but if you want to control timing, a classical cam is easy and reliable. And motor life will be infinite since it will be running continuously - no start/stop fifteen times per minute.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[damienmorton]

The actuator has to be electric - its going to be operating in a retail environment, so as close to solid-state as possible. I had hoped there might be an actual solid state system out there somewhere, a solenoid perhaps, or magnetic clamps, but all of that seems pretty expensive.

I see your cam suggestion. Could put a roller on the bottom of the plunge to reduce friction. Another way might be a sliding wedge. Yet another way is an actual lever.

Motor cant operate continuously as the timing of the cycles needs to be controllable. The numbers I gave were approximate, to estimate duty cycle.

Question is : how best to precisely control the force applied.

As far as I can tell, the only way to do this properly is to build a certain amount of elasticity into the system, and to get feedback from a load cell. This gives a position to force relationship, with calibration by load cell.

In the end, the problem appears to be one of "gearing" - transforming low force large movements into high force small movements, and of "elasticity" or storing up force into some kind accumulator.

I had been looking at using a Haydon Kerk 57000 non-captive stepper motor - and using a very low lead screw to get the "gearing". A polyurethane spring gives the system elasticity.

 

[damienmorton]

Oh - and by the way - the glass is neither half full, nor half empty ... its too big.

 

[Skogsgurra]

I sometimes drink out of the bottle..

The speed can be controlled if you use a VFD to supply the motor. given the ability of modern vector controlled VFDs, you can easily control speed very precisely and with reaction time in the 10 - 20 milliseconds range. The polyurethane spring sounds like a good idea.

Why does it have to be solid state? A VFD IS solid state, BTW. And they are extremely affordable if you compare with steppers and their controllers.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[damienmorton]

By solid state - I meant really solid state - was initially looking at various materials that expand/contract under electric or magnetic fields. PZT or GMR materials, for example. See

http://www.adaptamat.com/technology/

Ill read up on VFD controllers.

 

[ornerynorsk]

It might pay to have a look at some of the novelty coin presses which turn a penny into a souvenir.

Many of the older installations are manually driven with appropriate reduction gearing, but I have seen electric versions, as well.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.