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Modelling advice - cylindrical pv nozzle

Newbie

Modelling advice - cylindrical pv nozzle

Hello,

Just wondering if anyone had any advice as to how to go about modelling the cylindrical pressure vessel with nozzle shown below. It is changing in all 3 dimensions, so some kind of mixture of revolve and sweep seems logical. It is for a project so I will figure it out, just wondering if anyone has any helpful advice to save me getting lost.

Thanks

 

Cylindrical PV Nozzle.JPG

13 REPLIES 13

Re: Modelling advice - cylindrical pv nozzle

Hello, I have made progress but have encountered some issues (which I think are related to the 'blended sweep' function in Creo 2.0).

I have several screenshots here: Pressure_Vessel_Nozzle by rhamill95 | Photobucket   [Photobucket link]. The picture titles give some detail as to what they are.

So far I have successfully created what I am fairly confident are the correct section geometries (was given details of these). I then inserted both sketches into one part file and created a 90 deg sketch (quarter circle) to be swept around. I have then used a 'swept blend' of surface one (with the curved wall) to the other around the line. I have also tried using the rotational blend feature which as expected gives the same result.

Swept_blend_standard.JPG

The problem I am having is that wall thickness is not uniform when it is swept. Therefore the pressure vessel would not have a constant wall thickness (as shown below) and I cannot extrude the main cylindrical body through. How can I get fix this issue and produce the geometry as shown in the original question? I have tried playing with the 'tangency' options as shown in the pictures in the link. Thanks for your help and I would really appreciate any replies!

Swept_blend_front_thickness_(1st_section_free)_with_cylinder.JPG

Re: Modelling advice - cylindrical pv nozzle

Your first picture looks like a half cylinder with a nozzle bonded into it.

The second post shows two sections both of which show the nozzle 'thickness' to be quite different than the main 'pressure vessel' geometry.

For constant thickness walls, I would recommend you use the offset or the shell tools. Perhaps break up the problem into modeling the overall vessel and the nozzle somewhat separately.

Re: Modelling advice - cylindrical pv nozzle

Thanks for the response!

The nozzle is incorporated into the cylinder. (I.e. the nozzle wall is thicker in parts however it then runs down into the cylinder so that it merges into the cylinder). The picture included at the end of my second post shows that it is almost right but if zoomed in on, the cylinder wall does not match the nozzle wall as it should. I hope that makes sense as it is difficult to explain!

Re: Modelling advice - cylindrical pv nozzle

It's not my field of modeling. Anyway i made a quilt and then thickened (3mm). After this only one point wasn't 3 mm (thickness analysis). Someone expert of this can give a check.

Cattura.PNG

Re: Modelling advice - cylindrical pv nozzle

If you could post the model we could take a look into it!

Try to see if my model (Creo 3) is suitable for you.

Re: Modelling advice - cylindrical pv nozzle

Blending tangencies like this is no easy task.

The only way I've been able to do this is to use a VSSweep and manage the tangency within the sketch and equations (or graph).

Better yet (below), with curve driven rounds, you could do the merge generically and manage the blending with specialized rounds.

How is this part going to be fabricated?

Re: Modelling advice - cylindrical pv nozzle

Thanks for your response! I had considered that initially however the model is not actually of uniform thickness (the nozzel thickness varies)! I am not sure if I have permission to upload my model but will find out and see. I am aiming for something like Antonius Dirriwachter has posted, so am hoping he can try to explain how he managed to achieve it and hopefully others can learn from this! Thanks, Robert

Re: Modelling advice - cylindrical pv nozzle

Thanks very much for your response! Yes, it took me quite a few days just playing with the model to realise the complexity involved! You seem to be talking about exactly what I require and was unable to figure out how to "manage the tangency" properly. Curve driven rounds also seems like a great solution and your picture seems to have the problem solved exactly like what I am aiming for! Can I ask you to explain how you achieved this? I am trying to learn the method rather than just use an uploaded model etc! I would really appreciate your help! Thanks, Robert

Re: Modelling advice - cylindrical pv nozzle

The first part of the tree is simply getting the base geometry:

half pipe

nozzle feature

trim half pipe

trim nozzle feature

...then each round is treated individually (DTM4 is not required)

line for projection onto nozzle feature outside

project the line sketch onto the nozzle outer surface

Round using curve as a guide

Line for projection onto nozzle feature inside

project the line sketch onto the nozzle inner surface

round using curve as a guide