Holes/pockets on non-planar surfaces

[eex23]

Hello,

What is the best practice for placing holes, pockets on non-planar surfaces? Take a look at the attached prt (nx7 file). There we have standard rail (type R65) profiles: one stright and one bended (radius about 210 meters). Both rails have constant length (up to 25 meters). How to place hole or pocket on the neck of the stright rail is clear, but how to do this for bended rail?. In our workshop we firstly drill stright rail, and then bend it. Is it possible to do smth similar in nx: make stright solid and fit it to curve? If no, so how to place holes and how to position them correctly for the bendend rail?

Thanks.

 

[MickyV007]

Have a look at attached example, this maybe be a good example for what you try to do.

Best regards,

Michaël.

NX4+TC9 / NX6+TC8Unified / NX7.5 native

 

[JohnRBaker]

First a question; why are you working in 'History Free' mode?

Look at the attached file (it's your part with an added hole and a pocket in the curved rail).

For the hole, use the new (introduced in NX 5.0) Hole feature and you can create holes normal to the face of a model (that in fact is the default behavior). As for the pocket, create a Point at the location where you wish to create the pocket, create a Datum Plane through the Point and tangent to the face of the model. Now use the Datum Plane to create a Sketch of your pocket profile, then Extrude the Sketch and Subtract.

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

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

 

[teookie]

Regarding the datum->sketch->extrude method, what if he wants the walls of the pocket to be normal to the local part of the curve? The method you describe makes all pocket walls parallel.

 

[JohnRBaker]

You've got a point, although in this particular case it would only be the vertical sidewalls of the pocket which need to be set normal to the curve of the rail as the horizontal sidewalls would still be straight.

That being said, in this particular model the included-angle of two vertical sidewalls, if they had been created normal to the curve of the rail, would be less than 0.03 degrees. And considering the manufacturing techniques available when working with rolled structural shapes like standard gauge rail, I suspect that coming within a tolerance that small would have been considered more than acceptable.

However, in keeping with the intent of this exercise, providing a general purpose approach which would work in both this and other similar situations, I have modified my original model changing the angles of the vertical sidewalls of the pocket so that they are now more nearly normal to the curve of the rail.

As for the hole, while there will be some effect of curvature there as well, I suspect that again, considering the tolerances involved in drilling holes in standard gauge rails, I think it's safe if we left it as is ;-)

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

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

 

[eex23]

Thanks John for suggestions.

actually we do not work in history-free mode just here i posted simplified example of finished part.
question about hole. how to position it? e.g. I want to be the hole 1000mm from start of the rail, and 78.5mm from bottom of the railpad.

 

[JohnRBaker]

It appeared that the hole was on the edge shared by the two faces which makes up the vertical part of the rail. If that's correct, create an Associative Point on the edge using the 'Point On Curve/Edge' method. However, before you do that, create an Expression representing the length of the rail if you don't already have one (if you don't, you can create an Associtive Measure to get the value, either in the Expression system or or using Analysis -> Measure Distance using the 'length' option). Once you have the length as an Expression then it just a matter of determining, using expressions, the parametric location (percentage) which represents 1000mm and using that in the Point On Curve Parameter Expression.

John R. Baker, P.E.
Product 'Evangelist'
Product Design Solutions
Siemens PLM Software Inc.
Industry Sector
Cypress, CA

http://www.siemens.com/plm

http://www.plmworld.org/museum/

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