How to model a variable helical sweep cut that matches a CNC tool path?

[IE_1]

Hi All,

I'm resurrecting an old thread as I am curious if PTC have resolved this modelleing limitation in later releases. I did try to message the moderator to reactivate the old thread but was informed it is best to start a new one: 

Re: How to model a helical sweep cut that matches ... - PTC Community

Does anyone know if this is now possible in later relases? I am currently using 7 but no updates here. 

FYI my part does not have a standard helical pitch, I have datum curves generated by co ordinates, so it would not be possible to use the volume helical sweep which I beleive was a new feature added to V 7 to tackle this issue for set pitches. 

[KenFarley]

The closest I've come to modeling something like this was building a DZUS (Southco) fastener. It's very similar in that it's defined by a sweeping slot that allows for the spiralling passage of a wire along the axis of the fastener until it gets to a locking slot. Do a quick search on DZUS and you'll see the geometry. The only way I could get a model that did what I wanted was to construct equation driven curves for the swept portion of the cut. I used the curves to build surfaces, then used the surfaces to build a volume which was cut from the solid body of the fastener. The inlet and locking slots are modeled as simple protrusions.

I'd post a model, but we use Creo 9 and you state you're using 7, so that would be unhelpful.

Stated as sequence of steps, what I did is:
(1) Build the equation driven curves that define the spiralling surfaces. Cylindrical equations make this relatively simple.

(2) Construct surfaces using the curves, as well as surfaces at ends and inner/outer diameters of the slot.

(3) Make a closed volume using these surfaces.

(4) Use the closed volume to cut out the slot.

(5) Add simpler protrusions at the ends of the slot.

Hopefully this makes some sort of sense. The hardest part was the building of the equation driven curves so they represented the geometry that results when a cylinder is swept along the curve.

[IE_1]

Thank you for your solution, if I have understood your approach correctly you have effectively created a quilt (from equation datum curves) of each cut surface, solidified and subtracted from the main body as opposed to a VSS.

I was hoping in a later release of CREO it would be possible to mimic a cut perpendicular to the 4th axis as in solidworks, quite a simple job in there. 

Currently the part is modelled in a fashion with a note stating 3D data not to be used for manufacturing, instead using a table for the points through 360 degrees for the machinist. I was hoping as I have now picked this up I could improve on the approach and make the 3D model truly representative but I am not sure this is possible.

[KenFarley]

Yes, I used a method that builds the actual geometry of the path I needed, since variable section sweep does not yield correct geometry.

Modeling a true tool path is particularly difficult if one is trying to represent the results of using a flat bottomed end mill. I haven't seen the latest Creo solid body sweep, but likely it results in some sort of segmented result? If the feature type actually exists at all, that is.