×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

Twisted sweep

Twisted sweep

Twisted sweep

(OP)
Hi,

i hope you can help me with the following problem. You would have a oil dipstick, which would be general 3D curve spine. And you would need to create twisted section on it. In proe, you would do it the way, that you would simply draw a line in the sketch and constrain it with angle. And than you would do it as variable parameter for example angle = sin t...where t would be 0 to 1 of the curve. Do you have any suggestion how to do it in UG?

Thanks
Vit

RE: Twisted sweep

(OP)
Nx 4,02

RE: Twisted sweep

Vit,

Sweep the section along using the line as a guide curve and a tolerance of zero. Use and angular law method with a linear type and the values 0 to 360*(number of turns).

Best regards

Hudson

RE: Twisted sweep

Assuming that you have NX 5, attached is an example using exactly the procedure that your described.

There are 3 elements in the model, a Yellow line that acts as both the primary path of a Swept Body and as the base line for the Law Curve controlling the angle of the twist.  A Red sketch curve representing the location and angle of the twist.  And a profile sketch of the shape being swept.

The function you use is Swept Surface, using a single trajectory curve and using an angular Law for the Orientation and using a Law Curve to control the angle.

Note that this approach can be used with virtually versions of UG/NX going back 10 or 12 years.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/

RE: Twisted sweep

(OP)
Hudson,

to be honest... I dont know, how and when I should use the law method...Well, maybe I have found it...I tried to use swept and it seems to work clown

Thank you very much...
Vit

RE: Twisted sweep

(OP)
I wonder, if you can also control the other dimensions. Lets say length of the line?

Thanks
Vit
 

RE: Twisted sweep

(OP)
thank you John for the model... As already sad, can you also control the length?that would be very beneficial.

Regards
Vit

RE: Twisted sweep

The length is controlled by the length of the trajectory curve, in this case the first line.  To make it easier to understand, link the overall length of the Sketch to be same as the length of the trajectory.  For a example of this, see the improved attached file.  Open the part and then open the Part Navigator and expand the section titled 'User Expressions'.  From these expressions (double click the expression to edit it) you can now control the overall Length, the angle of Twist, and the start and end points of the Twisted section.

Have fun.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/

RE: Twisted sweep

(OP)
I dont know, if you understand it right...I thought to change the length exactly the way, you are changing the angle...for example length going from 50 to 100 along the curve...
Thanks
Vit  

RE: Twisted sweep

The length of the Sweep is NOT controlled by the Law Curve Sketch, only where the twisted section starts and stops and what the angle of the twist is going to be.  But since these are NOT automatically linked, that's why I suggested that you FORCE the sketch to be the same 'length' as the trajectory curve since that helps to keep it logical.  

That being said, there are those who prefer to make the Law Curve Sketch 100 units long and then they can treat the Start and Stop points of the twisted section as a PERCENTAGE of the final length of the sweep.  You can make it work anyway that you wish.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/

RE: Twisted sweep

(OP)
you still didnt catch, what I thought...I dont talk about the spine itself...lets imagine, that you have section created by line defined by angle and length...and you want to change the angle and also the length of the section line as it goes along the spine...

Regards
Vit

RE: Twisted sweep

(OP)
OK, if you look to the attached file and edit the sketch, there are two driving dimensions...angle and length of the line...I would like to change these two dimensions along the curve with some function...as i said, in proe, you would just do t= 0..1  and l=l*t and alfa = sin t for example...
Regards
Vit

RE: Twisted sweep

Now I have a better idea of what you're trying to do.

OK, we can do what you want, but not by directly controlling the expressions in the sketch but rather by controlling such aspects of the Sweep feature as Angle (we will use and Forumla Law) and Scale (we will use the 'Perimeter Law' which in this case can be considered the 'Length' of the line).

See the attached model where I've took your model and set the Angle to be equal to the value of the height of a Sine Wave and the scale I've used a cubic function from 54mm to 100mm.  Note that from the User Expressions item in the Part Navigator, you can control the 'Amplitude' of the Sine Wave and the 'Period' (no of cycles).  You can also edit the start and end length of the line as well.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/

RE: Twisted sweep

(OP)
Thanks John,

can you do the scale when the swept feature has already been created?

RE: Twisted sweep

You can go in and edit the Scale definition.  The default is constant, but you can edit it, like any other aspect of the feature, after the fact.

John R. Baker, P.E.
Product 'Evangelist'
NX Design
Siemens PLM Software Inc.
Cypress, CA
http://www.siemens.com/plm
http://www.plmworld.org/museum/

RE: Twisted sweep

(OP)
John,
yes, you can edit it, but I wasnt able to add the scale definition once it had been created without...but no problem..
i have attached the file in nx 4 version...I tried to create expression to control the scale...by adding two equations
t and ft...but the problem is, that the scale is still constant and what is even more strange is, that the line is smaller than the line, that I chose for the swept profile...I would like to be able to control the size of the profile along the curve with equation...for example ft = sin(t)+1...
Thanks
Vit

RE: Twisted sweep

Vit,

Sorry I couldn't get back to you sooner with and example so it looks like John has done most of the work already.

I may be ignorant of dipsticks but if you check my examples I was of the opinion that it should probably be twisted along the axis of the metal strip. Therefore I varied John's example in a couple of ways.

The second way that I varied the construction was to describe the twist law using a bridge curve rather than a sketch. I did this for no other reason than to try it out really proving you could be something a bit different.

Lastly in the attached is a second example of a bent dipstick. This is loosely based on the file which you attached. In that file you used a line which was NOT normal to the plane of the sketched section that you're sweeping. To me this was not likely to represent a desirable solution, and if indeed you need to follow such a line you would simple re-orient the other geometry to align with that as a new sweep guide and twist axis, the two in this case being the same thing.

Whereas in my example I have provided a curved dipstick with a twist the arc being constructed normal to the axis of rotation which just uses a line.

John,

If I may tack onto the end of the post for Vit here. As usual your construction is superior to what I briefly described earlier and I thought it a good example. I tell you what though it is not easy to figure out how a sweep has been built. The dialog when you create it presents one set of inputs and the edit parameters has something completely different. I hope in upcoming versions that this will be addressed sooner rather than later. I find sweep a very powerful but perhaps underutilized construction method, that is frequently poorly understood and probably languishes thus for being somewhat difficult to understand more for the presentation than the actual content.

Cheers

Hudson

RE: Twisted sweep

(OP)
Hudson,

thank you for the examples... Unfortunately, its not exactly what I wanted...I dont have a problem with using a curve to control the angle along the curve...the only thing is, if for example height of 100mm means 100degrees...but it seems to be...the problem what I had was, that I tried to control this by the expression, which doesnt seem to work...it seemed like the parameter t is still constant rather than changing with the position on the spine...so i would like to see, how you have to set up the set of expressions for the t parameter to work...i think, that UG basicaly wants t and ft(t)

RE: Twisted sweep

Vit,

I think it is just a vertical and horizontal scale height in the Z axis maps the range over which the twist occurs so that the straight portions of the law curve induce no twist and you can use two arcs, a bridge curve (as I did) or even a straight line in between to control how tightly the twist occurs in the section of sweep directly opposite. On the horizontal scale in the Y axis 1mm of arc length is gives you one degree of rotation.

You can experiment with different law curves if you like just to help you to better understand the results.

Hope this helps

Cheers

Hudson

RE: Twisted sweep

(OP)
Hudson,

and could you help me with the equations?

Vit

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! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close