What kind of (industrial) electric motor will do this?

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88keys

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Aug 24, 2012
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https://www.youtube.com/watch?v=urMVoDi0NDg

I did the best I could to make a visual demonstration with blender.

Basically what this does is that it operates at two different speeds. Slow for 1/2 revolution and fast for the other 1/2 revolution. This creates a jerking motion which is used to help scrap easily slide on chutes.

I'm not sure if there are any made specifically like this or whether they are modified to do this somehow.
 

IronWing

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Jul 20, 2001
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Wouldn't a simple off-center cam give this effect with the motor spinning at a constant speed?
 

Red Squirrel

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May 24, 2003
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www.anyf.ca
Stepper motor? Though a stepper motor of industrial size would probably cost quite a lot of money...

Could it be done through gearing? Motor runs same speed, but runs a special set of gears and other physical movement parts that outputs a varying speed.
 

yottabit

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Jun 5, 2008
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Wouldn't a simple off-center cam give this effect with the motor spinning at a constant speed?

This. At the heart of that thing I'd think you'd want a constant speed AC motor single or 3 phase depending on power requirements.

Then any combination of offset crank, cams, or linkages to achieve the desired motion output

https://www.cs.cmu.edu/~rapidproto/mechanisms/chpt5.html

Starting from the motion output you want at the conveyor is you can work backwards to figure out the design of the cam or linkages you would need. This is called mechanism or cam synthesis and it's not very easy in general. But your application seems pretty simple

One of the simplest mechanism to visualize is a face-groove cam. Follower tracks inside the groove. Modify the profile of the groove to achieve desired motion of the follower linkage.
cam3.jpg


If you're looking for an "off the shelf" solution then you'd probably want to talk to an industrial automation/motion control company or distributor. For instance random google search dug up these guys who I'm sure could help: http://www.camcoindex.com/CAMS.HTM

As others have mentioned you could use a servo motor to emulate the output motion directly. But I don't think that would be a practical solution. Usually those type of things are good for intermittent motion and quick response times and based on your video I'm guessing that you're after continuous motion or a 100% duty cycle in other words

EDIT: Also, the whole mechanism you are describing is similar in purpose to what I would call a shaker feeder. Those usually work by having a sprung chute, with an eccentric weight mounted to it, and an AC motor mounted off the device that would spin that eccentric weight. The shaking of the chute forces things to slide off of it. To learn more about those I'd look into "bulk material handling"
 
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Rubycon

Madame President
Aug 10, 2005
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If simplicity will do, a mechanical drive will work.
If you need to modulate variables then you will want to do this electrically through a drive such as a cycloconverter. How big is it? Twenty megawatt cycloconverter drives are expensive. ;)

You can also use an arrangement of hydro pumps and actuators (similar to EHA). You can use a straight piston too if acoustics isn't a concern.

Conche mixers used this principle.

And "machines for pleasure" often employ the principle for quick in, slow out or reversal for, you know, extended drip times. :biggrin:
 

88keys

Golden Member
Aug 24, 2012
1,854
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This. At the heart of that thing I'd think you'd want a constant speed AC motor single or 3 phase depending on power requirements.

Then any combination of offset crank, cams, or linkages to achieve the desired motion output

https://www.cs.cmu.edu/~rapidproto/mechanisms/chpt5.html

Starting from the motion output you want at the conveyor is you can work backwards to figure out the design of the cam or linkages you would need. This is called mechanism or cam synthesis and it's not very easy in general. But your application seems pretty simple

One of the simplest mechanism to visualize is a face-groove cam. Follower tracks inside the groove. Modify the profile of the groove to achieve desired motion of the follower linkage.
cam3.jpg


If you're looking for an "off the shelf" solution then you'd probably want to talk to an industrial automation/motion control company or distributor. For instance random google search dug up these guys who I'm sure could help: http://www.camcoindex.com/CAMS.HTM

As others have mentioned you could use a servo motor to emulate the output motion directly. But I don't think that would be a practical solution. Usually those type of things are good for intermittent motion and quick response times and based on your video I'm guessing that you're after continuous motion or a 100% duty cycle in other words

EDIT: Also, the whole mechanism you are describing is similar in purpose to what I would call a shaker feeder. Those usually work by having a sprung chute, with an eccentric weight mounted to it, and an AC motor mounted off the device that would spin that eccentric weight. The shaking of the chute forces things to slide off of it. To learn more about those I'd look into "bulk material handling"


Thanks. This is probably what was used. I was touring a plant and I saw a motor like I described used to shake scrap off of chutes. They wouldn't allow me to take any pictures or video so I did my best to reconstruct it from memory.
 
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