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Cam Profile on Cylinder

C

Cheesewhiz

New member
I want to create a cam profile on a cylinder, i have a rod witha pin through it that moves up and down in the cylinder, I can't get the pin to always be tangent to the cam profile on the cylinder .. I really need to revolve a cut (3mm end mill) through a trajectory and have the cut always perpendicular to the axis of the cylinder


The picture is my best attempt, i uesd a sketch then wraped it around the cylinder then projected it to the outer cylinder and created boundary surfaces, as you can see from picture the pin is not always tangent to this surface, it hits the ID cam surface first


View attachment 490
 
Here is someting else i was trying, using the variable section sweep, with graph and trajpar ... Ok the picture is the cylinder, the small cylinder in the middle is 3mm, the problem is i need to sketch my section on the PIN_OFFSET plane, where it sweeps 360 around the cylinder where the PIN_OFFSET plane is always tangent to the 3mm cylinder, which it won't let me do, the sketch plane it gives me always goes through the axis of the cylinder.View attachment 491
 
Is there a way to do this in mechanism, i heard of being able to create a envelope surface or solid, where pro/e creates a solid blob showing the envelope of motion. does anyone know how to do this? I can picture how this part would would be machined, it just seems something like this should be possible in Pro/e
 
I think this will do it:
Create the outer cylinder. Go to sheet metal, use the inner surface as driving surface. Create a rip, and unbend the cylinder. Create a smt-class cut solid, sketch the cam curve and cut. When you are done, use unbend all to get it back to a cylinder. Now the cam curve is perpendicular to the axis of the cylinder.
 
If I properly understand your problem, this should solve it: Construct the desired cam profile on a plane, using the pin axis as the driver (pin centerline). Then wrap (decal) this cam profile onto the cylinder. Construct a short surface radially inward, which can be accomplished with a projection normal to the cylinder surface. Then, create an offset surface. This last surface should be offset an amount equal to the pin radius, in the direction that will yield the path of the of the actual cam on the pin. This offset surface will necessarily representa surface tangent to the pin if you movedthe pinalong the original cam profile, and, due to the constant offset, it will be parallel to the first surface at all locations alongthe pin axis. In other words, it will be the surfacegenerated by the outer cylinder of the pin as the pin axis translates along the first surface, with the pin axis always intersecting the longitudinal axis of the cylinder. Now, use the offset surface to cut the cylinder. What remains should be the proper cam profile. I hope this helps.


ThreeSigma
 
I would like to thank Cheesewhiz and Laplander for their kind remarks in response to a solution I posted a few days ago. I use Pro/E for business purposes, but I get tremendous satisfaction from solving problems with it. I have also been extraordinarily frustrated when I couldn't get it to do what I thought it should do (sometimes my fault), and have found this forum to be of value to me in the past. The appreciation that has been shown for my posted solution has had a very surprising, positive impact on me, and will inspire me to participate more often. I'm delighted to find others who are so excited to solve a problem. Thanks to all of you.


ThreeSigma
 
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