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Distinguished Contributor
tdswanson
Posts: 143
Registered: ‎03-07-2012
Message 1 of 11 (484 Views)
Accepted Solution

How to Functionally Constrain a "Split Wedge" Assembly?

484 Views, 10 Replies
12-07-2012 06:27 AM

Hey everyone:

 

I'm working on a simple assembly that's got some moving parts and I'm having a hard time getting the constraints to work right.

 

It's a simple "wedge" assembly where the wedge is constrained to a single axis with a return spring keeping it biased one way.  The are two blocks that are pulled tight against the taper of the wedge with springs that keep them pressed against the taper.  When the wedge moves in they split, when it moves out, they contract.  Simple, right?

 

For the life of me, I can't seem to constrain the parts correctly to the taper so it behaves correctly.  The design is proprietary, so I've made up a "lite" version of it and attached it here.

 

Can anyone help?  Thanks!

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Distinguished Mentor
rdyson
Posts: 894
Registered: ‎04-11-2005
Message 2 of 11 (481 Views)

Re: How to Functionally Constrain a "Split Wedge" Assembly?

12-07-2012 07:13 AM in reply to: tdswanson

Your wedge fits exactly with the blocks. They will not move with respect to movement of the wedge.

I don't understand you intent.

Distinguished Contributor
tdswanson
Posts: 143
Registered: ‎03-07-2012
Message 3 of 11 (477 Views)

Re: How to Functionally Constrain a "Split Wedge" Assembly?

12-07-2012 07:26 AM in reply to: rdyson

I've attached a revised copy with the tapered face of the blocks constrained (via Tangent) to the taper of the wedge.  However, this seems to work in reverse of reality. 

 

When the wedge is lifted UP, the block moves out.  In reality as the wedge is lifted UP, that block is going to slide in.  Obviously it's not in this assembly model, but imagine a spring on the external face of the block that's keeping the two tapered faces together. 

 

Thus when the wedge goes UP, the block should slide towards the Y axis.

 

Is this clearer?

 

Thanks!

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rdyson
Posts: 894
Registered: ‎04-11-2005
Message 4 of 11 (474 Views)

Re: How to Functionally Constrain a "Split Wedge" Assembly?

12-07-2012 07:35 AM in reply to: tdswanson

Sorry, I still have no idea what you'er expecting to happen.

*Expert Elite*
JDMather
Posts: 26,616
Registered: ‎04-20-2006
Message 5 of 11 (469 Views)

Re: How to Functionally Constrain a "Split Wedge" Assembly?

12-07-2012 07:53 AM in reply to: tdswanson

Remove the Tangent constraint.

Add the two Split*.ipt parts to Contact Set.

Activate Contact Solver

 

or

go into Environments>Dynamic Simulation and add a joint for the contact.

Please mark this response as "Accept as Solution" if it answers your question.
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Distinguished Contributor
tdswanson
Posts: 143
Registered: ‎03-07-2012
Message 6 of 11 (463 Views)

Re: How to Functionally Constrain a "Split Wedge" Assembly?

12-07-2012 08:26 AM in reply to: JDMather

OK, so that seems like it's pretty much it.  I've added a shoulder screw that'll hopefully clear things up a bit.  (see attachment).

 

I added the blocks and the wedge to a contact set, activated contact solver, then drug them in until they touched.
  As I drag the wedge down, the blocks split, but they don't contract when the wedge returns UP.

 

So I added a planar constraint with motion limits and used the original offset as a resting position.  This works to drag it around with contact solver active, but I can't drive the constraint on the travel of the wedge for a simulation.  It errors out.

 

Is there another way to drive the motion a few times?

 

Also - I don't have "Dynamic Simulation" on my Environments tab.  Was this a separate purchase item?

 

Thanks very much for looking this over with me!

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JDMather
Posts: 26,616
Registered: ‎04-20-2006
Message 7 of 11 (458 Views)

Re: How to Functionally Constrain a "Split Wedge" Assembly?

12-07-2012 09:07 AM in reply to: tdswanson

tdswanson wrote:

 

Also - I don't have "Dynamic Simulation" on my Environments tab.  Was this a separate purchase item?

 



Must have Inventor Professional to have the Dynamic SImulation.

You can fudge this with Inventor Studio motions, but I think if you really need to simulate something here you are going to need D.S.

Please mark this response as "Accept as Solution" if it answers your question.
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Distinguished Contributor
Mark.Downes
Posts: 116
Registered: ‎11-18-2010
Message 8 of 11 (401 Views)

Re: How to Functionally Constrain a "Split Wedge" Assembly?

12-10-2012 03:32 AM in reply to: tdswanson

Hi,

 

I use this kind of assembly a lot with jigs and fixtures, if I have this correct to what you want; it’s a simple split face on the conical faces and a coincident mate of the edges (see attached).

 

Hope this helps

 

Cheers

 

Mark

Inventor 2013

 

Distinguished Contributor
tdswanson
Posts: 143
Registered: ‎03-07-2012
Message 9 of 11 (373 Views)

Re: How to Functionally Constrain a "Split Wedge" Assembly?

12-10-2012 12:10 PM in reply to: Mark.Downes

Mark:

 

I split the faces on the block and on the wedge.  And I can constrain one of the split lines to the other split line, but then nothing can move.  Am I missing something?

 

Thanks!

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Mark.Downes
Posts: 116
Registered: ‎11-18-2010
Message 10 of 11 (355 Views)

Re: How to Functionally Constrain a "Split Wedge" Assembly?

12-11-2012 12:04 AM in reply to: tdswanson

Mornin,

 

The olny thing i can think of why its not working for you is you may have too many Mates.

It works for the model i uploaded from your asembly!

 

Give that one a go, If i think back i took of the active contact solver (and mates).

 

cheers

Mark

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