machining cut in Pro E

[janwan]

I would like to create machine cut in Pro E that would mimic ball-- end cutter. I need to make "kind of helical sweep", just like on a lead screw but my "screw" does not have circular cross section but triangular and it is not straight but full donut. I created this geometry but it is very expensive to make .
I think I can do equivalent part when I create ball-cutter groove on the top of the donut then I would flip it upside down and create second half of the "coil". This would allow for "straight pull" and make my part less expensive.
I am attaching small sketch to illustrate the groove I am trying to make.
Any help greatly appreciated

 

[aafuni]

Just make a curve for the path, then use a sweep to sweep the profile of the ball end mill.

 

[janwan]

This is exactly what I did and created very expensive part that can be made only with 5 (some vendors claim 6) axis machining.
With 3 axis only, the problem is transition (intersection) of upper and lower halves

 

[aafuni]

Is this a Pro/E question or a machining question? Are you asking if the cut can be machined in 2 steps?

 

[janwan]

It looks like it can be both.
I was hoping to create single sweep. Imagine sweeping volume not a 2D section (like a ball cutter) tangent to the curve but perpendicular to the projection (in the direction of the cutter)of the curve. This would mimic real machining (3 axis). Can it be done in Pro E (sweeping volumes)
I guess I will have to do some cleaning around transitions if there is no other way.

 

[Hobbles]

I don't understand why a sweep-cut along a curve would not accomplish this. Your sweep volume would be the 2D profile of the ball end mill cut you want along the curve you specify.

What do you mean by upper and lower halves?

 

[janwan]

Hobbles
Unfortunately it does not do the job. Imagine the plane that is perpendicular to the axis of toroid and cuts it, say through the center of the section, that was used to create revolved feature (see pdf file attached) Just like you cut your donut or bagel to put some smear on it . Now if you look from the top you see upper half if you look from the bottom you see lower half.

In order to create this coil I created two sketched lines that looks like a V (if you look in the direction of the toroid axis) and projected them on surface of the toroid. One line is projected on the upper half the second one on the lower half. Now if you use sweep cut and your cross section is circle you will not get a groove (that I need). You need to create section that looks like a groove. The problem is sharp point of the V lines. Two sections do not match they are rotated with respect to each other. If you create sections that are parallel to each other
you will create under cut and will not be able to use conventional 3 axis machining tools.
If I understand this correctly the only way to do it is to sweep volume tangent to the curve and perpendicular to the sketched line.

If you know other way please let me know.

 

[aafuni]

What are you using for the sweep? If you use a varriable section sweep you can set the section plane control to normal to a projection. This will limit the profile from moving in an additional axis, simulating a 3-axis machine.

If I am understanding you right though, it would seem like you may be best with a 3-axis mill with the part on a rotary table, or on a small VTL or such. If you just make a sketch, and put a path on your model and talk to your shops you should be able to have it done pretty readily.

 

[janwan]

aafuni,
This exactly my plan, create path on CAD model and send it to my model shop. There is one problem I am facing. When I project the sketched lines they are ending up on the other side of the surface and I am not sure how to trim it. I know how to trim the cut but I could not figure how to trim the curve (projected lines) yet. I always thought projecting line on the curve surface will be like seeing shadow. In my case the projected line is also on the "dark side of the moon". I think I will have to split surface so the line ends up on the visible side of the moon".
Thanks