Rotating a Horizontal slide Engine 2

[Toptracks]

Hi,
I have created a model in NX6 and want to add movement. I have a simple crank shaft, connecting rod and hozizontal slide assembly, that has been assemblied with touch align constraints. The engine will not rotate when I try to turn the crank shaft, can anyone help me on this? I did try to force movement by setting a distance on the horizontal slide, this does force the model to move correctly.

 

[JohnRBaker]

Without the model it would be impossible to determine exactly what's happening.

That being said, there is one thing to remember; for something to able to move is MUST have at least one degree of freedom. Fully constrained Components are by definition CONSTRAINED, i.e. they cannot move.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[kapmnit123]

Hi,
A quick check for the constraints can be dragging one of your components through assembly constraints and see how the assembly reacts (i am attaching a video herewith.)This will give you a rough idea about the remaining degree of freedom in your assembly mechanism.In later releases (however we have a dedicated tool for displaying dof "SHOW DEGREES OF FREEDOM ").
Best Regards
Kapil Sharma

 

[Toptracks]

Many Thanks for your advice, the attachment was useful as I spotted that you were moving the assembly by adding a constraint and moving it with Touch Align, This worked for my assembly. Before your advice I was trying to move the crankshaft by rotation, using the move icon.

Also I spotted that you had fixed the base using the "Fix constraint.

 

[Toptracks]

Just when I thourght I had cracked the horizonal mill engine I have come to another stop.

I have now added to the engine and put a simple eccentric onto the engine, When I complete a sub assembly all works well (First attached file). In this example I fixed the shaft, and then moved the rod back and forth, the correct movement was observed.

When I came to inset this into the full assembly, I cannot get the correct movement. The full assembly has the base fixed.

Any help would be welcome.

 

[JohnRBaker]

You may need to override the Assembly Constraints of the Sub-Assembly at the top level of the Assembly. Click this ling and you will see several threads where overriding assembly constraints has been discussed:

http://www.eng-tips.com/search.cfm?...raint&t=&h=&searchSite=1&searchArea=1&d=1&s=2

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[Toptracks]

John,

Many thanks, your advice regarding over riding assembly constraints was spot on. I have now completed my assembly and plan to record motion in the sequence part of the programme. Do you have a reference guide for this as the programme seems to have a mind of its own.

I would like to record in slow motion and fast motion for 20 / 30 seconds, not sure if this is possible?

 

[JohnRBaker]

If you're using Assembly Sequencing to 'play your model', there is a 'Speed' option. It's not a specific speed, just a 1-10 speed ratio setting to control the 'frame rate' of the playback. And if you were running NX 7.5 or newer version of NX there is also a built-in movie capture option which will capture the motion frame-by-frame which can be plyed back using whatever .avi player that you wish which may provide option playback speeds.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[Toost]

What is the purpose with this exercise? Do you want to animate to illustrate the function or do you want to analyse ?
If you want to analyse, NX has a "Motion simulation" application where one can set things like speed etc and analyse kinematic properties.
If you want to illustrate then maybe the Assembly Sequencing is enough.

Regards,
Tomas