# Roller expension mechanism

1. Jan 6, 2010

### dsesmg

Hi, I am trying to make a conveyor that has a roller expension mechanism.
Please take a look at this drawing.
http://www.flickr.com/photos/46279408@N06/4251882419/sizes/o/ [Broken]
As the drawing shows, you can imagin two supporting beam on each side of rollers as rollers will need to be fixed or assembled to something. I don't know where do they need to be attached for the expension mechanism. But anyway, I need those rollers to be gradually expended as they rotate just like a conveyor and I also need each individual roller to be spined as it moves. How can I possibly do this?

Last edited by a moderator: May 4, 2017
2. Jan 6, 2010

### pantaz

I'm having great trouble understanding your questions.

Please define "expension". Perhaps you mean "extension"? (The only http://www.merriam-webster.com/dictionary/expended" [Broken] makes no sense in your usage.)

Tell me if I'm interpreting you correctly: As the rollers spin, you want to extend the overall length of the conveyor?

How much extension is required? You might try a chain or belt drive with a movable idler gear taking up the slack.

Is this a design exercise or a practical device you are building? What are the general dimensions and loads?

Last edited by a moderator: May 4, 2017
3. Jan 6, 2010

### dsesmg

Hi, thanks a lot.
I am sorry. I spelled it wrong. Expand is correct.
I am wondering how the pitch of those rollers could be expanded while the individual rollers spin during the rotation of the conveyor.
I am thinking the length of the conveyor would be 2m long. I am not trying to expand the length of the conveyor. I am trying to gradually expand the pitch of rollers.
The minimum expand pitch on the conveyor(the begining point of the expend mechanism) is 10mm and the maximum expand pitch is 150mm.
http://www.flickr.com/photos/46279408@N06/4252103031/sizes/o/ [Broken]
The viewing perspective is from the top of the conveyor.
I am an engineer wannabe. Please teach me.

Last edited by a moderator: May 4, 2017
4. Jan 8, 2010

### dsesmg

This is a very intersting engineering example.

5. Jan 9, 2010

### dsesmg

Hi, guys.
I am eager to find out the roller expansion mechanism.
How can I gradually expand the pitch of each rollers on this conveyor?
http://www.flickr.com/photos/46279408@N06/4259069696/sizes/o/ [Broken]

Last edited by a moderator: May 4, 2017
6. Jan 9, 2010

7. Jan 9, 2010

### tyroman

I'm at a loss... why couldn't you simply mount the rollers directly to the frame in the pitch you depict (the 14 rollers across the top) and then use your motor to drive a conveyor belt which is supported by the rollers?

See attached sketch;

.

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8. Jan 9, 2010

### pantaz

As I understand it, he wants to start with all rollers spaced at 10mm on-center, then gradually expand the spacing to 150mm on-center for all rollers[/].

9. Jan 9, 2010

### pantaz

Mount the rollers on individual axles, like a bicycle wheel.

Well, the frame of the conveyor could be fixed, but the length of conveyance would increase as the pitch increases.

As for the actual mechanism, I'm thinking along the lines of a drawer slide type of device. Look at a http://www.google.com/search?q=full-extension+ball-bearing+slide" to see what I mean. Not that you could use an actual drawer slide, but the principal of operation.

Last edited by a moderator: Apr 24, 2017
10. Jan 10, 2010

### Danger

I like the way that your mind works, Pantaz, but I think that your approach would be at best a jumping-off point. That would be 2m worth of incrementally telescoping elements (which have to be perfectly synchronized from side to side to eliminate bearing wear and/or axle shearing). I have my doubts, but I can't think of anything better.
This is one of the most difficult challenges that I've ever encountered. (The worst was trying to teach a snake to tap-dance, and I eventually gave up.)
Even worse if the OP wants this to be a smooth linear change rather than stepped.

11. Jan 10, 2010

### dsesmg

Thank you very much, pantaz, tyroman, Danger.
I feel like I found an oasis in the desert.
Yes, this is a very challenging subject.
http://www.flickr.com/photos/46279408@N06/4262254146/sizes/l/ [Broken]
The measurement is shown just to indicate that the rollers are expanding.
I've been thinking of connecting those rollers all together by chains like that so that there is a variable spacing from 0mm(min) to let say 150mm(max).
Between the space of each rollers, there must be some mechanism that could seperate or regulate the roller pitch. I am sure there must be some method of doing that. I also asked my friends. They said they have seen such mechanism used in some toys.
They don't remember it though as it has been a long time since they played with it.

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12. Jan 10, 2010

### Danger

I hate to say this, pal, but that last picture makes no sense to me. There's something in the rest of your post, though, that sort of tickled a back corner of my brain. I've so far had only a dozen or so beers and a couple of shots of Scotch. Leave me dwell upon the matter over a couple of more brewskies.

edit: Okay... it has something to do with varying diameter toothed wheels driving some sort of chain to regulate the system. I don't think that it can actually work, but I'll think on it a bit.

edit #2: I can't see how to do it with chains, but varying sizes of cogs that grab the axles of the rollers might do it. That's only one more beer and I'm on another Scotch, though, so it's not definitive.

Last edited: Jan 10, 2010
13. Jan 10, 2010

### tyroman

Guess I still don't get it...

First:
In your post #3 you say;
"I am an engineer wannabe. Please teach me."
Your first lesson has to be in communication of the basic design criteria in clear, unambiguous language. You have been asked to do this in pantaz's post #2;
"How much extension is required?" and
"Is this a design exercise or a practical device you are building? What are the general dimensions and loads?"
"What is the purpose/application you envision for this device?"

Second:
In your latest sketch from post #11;
http://www.flickr.com/photos/46279408@N06/4262254146/sizes/l/ [Broken]
you show seven rollers with the distance from the first roller to the last equal to
3184.76mm
If the final spacing (after all 'chains' are extended) will be 721.86mm between each roller, then the total distance from the first roller to the last will be equal to
4331.16mm
However; in the sketch contained in your post #3;
http://www.flickr.com/photos/46279408@N06/4252103031/sizes/o/ [Broken]
you show a 'Support beam' length of 2000.00mm ...
If the final spacing between each roller is to be 721.86mm, how do you propose to support the additional 2331.16mm length of the fully expanded conveyor?

Third:
In the same sketch from post #11 you show the following incremental extensions between rollers (numbering rollers from left to right);
roller 3 is 067.68mm further from rolller 2 than roller 2 is from roller 1
roller 4 is 057.34mm further from rolller 3 than roller 3 is from roller 2
roller 5 is 032.62mm further from rolller 4 than roller 4 is from roller 3
roller 6 is 105.92mm further from rolller 5 than roller 5 is from roller 4
roller 7 is 088.50mm further from rolller 6 than roller 6 is from roller 5
This series of increments is not linear, it is not log based. In short; it seems arbitrary... Can you define what your target is?

Fourth:
You have defined the maximum expanded distance between two rollers to be;
150.00mm >>> post #3
220.26mm >>> post #5
721.86mm >>> post #11
What is the actual distance?

These are valid issues which you should nail down in your efforts to communicate. Nothing is more frustrating to an engineer than a design criteria which is ill-defined, internally inconsistent or a "moving target".

.

Last edited by a moderator: May 4, 2017
14. Jan 10, 2010

### pantaz

You should probably make two drawings, one showing the rollers fully compressed, another showing them fully extended.

You will not be able to maintain slack between rollers -- you will need idler gears/rollers for that configuration.

Pantograph? It would be a little bulky, but it could work.

Last edited by a moderator: May 4, 2017