×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Creating a sweep or blend with laws

Creating a sweep or blend with laws

Creating a sweep or blend with laws

(OP)
I will start by saying I am a somewhat experienced CATIA user and have a number of years experience under my belt at this point. However this one has been stumping me for some time now and would really help me with my job if I can figure it out.

So basically what I am trying to due is:

Say we have two tubes one is square and one is round. Both tubes have a length of line of 200mm.

Lets say there is a 100mm gap between the tubes, Now I want to connect the two tubes with a transition area however I want the transition to stay at a length of line of 200 mm throughout. I could add a tolerance to it say +-2mm on the length of line.

Yes I know I can create a blend between the two but a blend will not hold a length of line through it. There has got to be a way to accomplish this any ideas would be appreciated. The best I have come up with so far is to create a multi-section surface and break the transition into many sections that I then manually shape until I have exactly what is needed... This is a very time consuming process.

RE: Creating a sweep or blend with laws

could you explain "length of line" please

RE: Creating a sweep or blend with laws

(OP)
Sorry, Length of line is just the circumference. If you were to take a string and wrap it around the part at any possible point. In a perfect part the string should be 200mm in length.

RE: Creating a sweep or blend with laws

Thanks for the explanation. Unfortunately, I don't have a solution for you, but I do have a similar need.

I recently had to model a volute shape, but I was interested in controlling the cross-section area (linear decrease of area (air-flow) as the volute rotated around. Like you, I had to manually draw several cross-sections (sketches, in order to make a multi-section surface.

I hope I'm proven wrong, but I don't think there is a Law to control the Circumference (perimeter) or the Area.

RE: Creating a sweep or blend with laws

(OP)
I can not see the picture for some reason... It is showing as a broken picture.

RE: Creating a sweep or blend with laws

(OP)
Thank you, That does not appear to be what I am looking for.

See the picture I attached for better explanation than my original post. All of the various sections through the transition I want to read 200mm.

jackk, Yes I believe we are on the same page with this. If you ever figure it out please let me know haha. With everything that can be done in CATIA there has just got to be a way to do it...

RE: Creating a sweep or blend with laws

Fernando:

Looks like you broke the circle up into 4 arcs, added some lines between the sections and then made 4 Fill surfaces. How does that control the circumference as the tube transistions? Am I missing something? I also think it would be much easier to just make a Multi-Section Surface or Multi-Section Solid, with almost the same result.

On4now4:

In your fist post, you said you made a Multi-Section Surface and then adjusted the section cuts. I'm curious how close the Multi-Section Surface sections were to the target "length of line"?

RE: Creating a sweep or blend with laws

(OP)
Attached is a picture of a real example of one that I did. As you can see in the picture I was able to keep it within about 0.6mm which in this case was okay because I was looking for a bit of expansion anyway. I have done it a little tighter it is just that much more time consuming the more precise I need it.

You can see in this example how most of it was modeled with splines that are used as guides in a multi-section surface rather than tweaking sections with sketches like you described. By just changing the tension on the splines I was able to shape to what I needed. Sometimes you can not get around sketches though. Sometimes a combination is required...

RE: Creating a sweep or blend with laws

Same approach like in first post (as Jackk described), with a last intersection to control along the 100 mm gap, all within 0.2 mm tolerance for length of the intersection curve (and with a little patient to play with scaling values can be better). Part is done in r21.

Regards
Fernando

https://picasaweb.google.com/102257836106335725208
https://picasaweb.google.com/103462806772634246699...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources