Barrel Cam Modeling
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
Barrel Cam Modeling
I'm looking for ideas on how to properly model the slot in a barrel cam. I have attempted multipe techniques and I'm starting to spin my wheels. I have an idea that what I want to do can probably be done with the variable section sweep, but that feature is definitely not my area of expertise.
I've worked through the "wave washer" suggested technique on PTC's site (http://www.ptc.com/appserver/wcms/standards/freefull_cskdb.jsp?&im_dbkey=88651&icg_dbkey=900). The problem with this exampl is that the part is not a constant thickness (whereas my cam slot needs to be). To get a constant thickness, I changed the sketch profile to a single line, which created a single wavy surface, and then thickened it. Problem is, the sides are no longer vertical. To get around that, I lengthend the VSS section to include some extra on each end, then extruded inner and outer cylinder surfaces, merged everything together, and solidified. This succeeded in creating a constant thickness washer with straight sides.(See attached PDF.)
Problem is, thistechnique does not transfer well to the cam. The centersurface won't offset nearly as far as it would need to. Creating inner and outer curves and building boundary blends didn't work either.
Tom
This thread is inactive and closed by the PTC Community Management Team. If you would like to provide a reply and re-open this thread, please notify the moderator and reference the thread. You may also use "Start a topic" button to ask a new question. Please be sure to include what version of the PTC product you are using so another community member knowledgeable about your version may be able to assist.
- Labels:
-
Data Exchange
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
Tom U.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
The Swept Solid function allows an actual solid shape (say a milling cutter) to be swept and cut from another solid. A Cut-Sweep only cuts a sketched profile which gives a slightly different result.
files.solidworks.com/supportfiles/Whats_new/2008/English/whatsnew.pdf
[cid:image001.png@01CD0D01.232491E0]
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
Could you do the washer as flat, do one section of the wave as a cut, then pattern the wave cut? I would think this would work.....
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
[cid:image001.jpg@01CD0D7F.340D0A90]
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
[cid:image002.png@01CD0D80.D39A1D40]
Brandon Lenk
Senior Designer
TEAM Industries-Bagley
(218) 694-4128
-<">mailto:->
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
Toroidal Bend.
I'm fairly sure the geometry isn't 100% accurate; but it looks about
right, and since the milling guys program it from the flat pattern
anyway, it makes it easier to include that information in the drawing.
Jonathan
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
This first one shows how a roller will gouge the slot surface. The roller should only be in contact on the red line. This is what is created using a VSS, Toroid bend, graph with trajpar, etc.
[Description: cid:image009.jpg@01CD0D85.38920EC0]
This picture shows slots that were created by offsetting one through the center of the path. These are correct! I just can't use this approach for the real cam profile (surfaces become self-intersecting at the offset values needed.)
[Description: cid:image010.jpg@01CD0D85.38920EC0]
If there is a way to alter the VSS to allow the blue rectangle to tip as it sweeps around so it's parallel with the red line, we'd be perfect!
[Description: cid:image001.jpg@01CD0D8B.09C2A9A0]
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
[cid:image004.png@01CD0D9F.8BD2EDB0]
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
Another idea could be to start creating a VSS surface with the current flat trajectory making an edge being you cam edge. Then use that edge as trajectory for the VSS that makes the solid cut holding the sketch normal to the its trajectory.
Best Regards,
Bjarne Frandsen
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
* Using a variable section sweep seems to be the best solution so far.
* The primary trajectory needs to be the cam profile wrapped or projected around the cylinder.
* There needs to be a second trajectory for use as the X-trajectory (under Horizontal/Vertical control)
[cid:image002.jpg@01CD0E68.1CEDDA30] [cid:image004.png@01CD0E60.C36703D0]
I am still struggling with how to correctly model the surfaces in the areas when the offset combined with the rotation will generate a sharp corner. The picture shown above is with the slot 45mm thick. It needs to be 40mm thick. Here is what it looks like when it's the correct thickness.
[cid:image005.png@01CD0E64.0025FB20] [cid:image008.jpg@01CD0E68.1CEDDA30]
I am presently attempting to build the top and bottom slot surface independently to see if I can overcome this issue. Thanks for all the suggestions so far.
Tom U.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
Tom U.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
I think I found a nice solution for this Barrel Cam Modeling making it in 3 features. I am not an expert in mechanism design, so I might have overlooked something, but anyway here is my suggestion:
Use VSS to create a surface perpendicular to the cylinder. The height from the base can be driven be the CAM graph (10.00 is the start value). Dimension the surface to the depth need for the CAM (5.00) and let the other end be free of the cylinder (1.00).
[cid:image002.png@01CD0E9A.373A9130]
This give a Quilt surface like this:
[cid:image003.png@01CD0E9A.373A9130]
Thicken the Quilt and define it as a Cut:
[cid:image004.png@01CD0E9A.EC9088A0][cid:image005.png@01CD0E9B.437BA9B0]
This gives a Dihedral Angle at the bottom of the groove close to 90 degrees.
[cid:image006.png@01CD0E9B.B08C0AE0]
And a constant groove width:
[cid:image007.png@01CD0E9C.912CC5D0]
/Bjarne
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
leverages "approximate" copies for the origin & x-vector of the VSS to
reduce potential self intersecting geometry.
I had also include a "Full Round" in the model to help illustrate the cam's
performance. For those of you who are playing with this leveraging a round
on the internal edges will help you visualize if the results are as needed.
You will find that creating a simple edge round (with correct results)
should yield parallel internal tangent edges of the round throughout the cam
surface. It should also allow you to create a full round as illustrated in
this example. Switch the full round OFF and set the value to about 4 and you
should see what I am talking about on the inside surface of the cam
(WF5 & features suppressed to reduce file size).
Hope this helps others,
Tim McLellan
Mobius Innovation and Development, Inc.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
While I've been pondering this problem I've been trying to set up a
mechanism to be able to see the motion of the pin following the groove,
but Pro/E will not allow a cam follower connection. Does anyone know how
to go about setting it up so a pin will follow the groove for a motion
study?
Doug Barton
Mechanical Designer
Parker Hannifin Canada
Electronic Controls Division
1305 Clarence Avenue
Winnipeg, MB R3T 1T4 Canada
direct 204 453 3339 x309
fax 204 452 7156
-
www.parker.com/ecd
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
[cid:image003.jpg@01CD0E74.AB30F500]
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
facetted (i.e. surface, STL...)
Tim McLellan
Mobius Innovation and Development, Inc.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
What I said was Pro/E would not allow it (in this case). I believe this
is because the cam surface is curved in two directions which makes it
invalid. Although I also tried just the profile curve instead of the
surface and that didn't work either.
From Help
The question was, is there a method other than a cam follower connection
to get the pin to follow the cam profile.
Doug Barton
Mechanical Designer
Parker Hannifin Canada
Electronic Controls Division
1305 Clarence Avenue
Winnipeg, MB R3T 1T4 Canada
direct 204 453 3339 x309
fax 204 452 7156
-
www.parker.com/ecd
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
VSS created with curve on end of cylinder and pre-determined track curve:
[cid:image008.png@01CD0E77.56626B00]
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
Here's an image of an assembly of parts. The pins are just assembled
point on curve.
Doug Barton
Mechanical Designer
Parker Hannifin Canada
Electronic Controls Division
1305 Clarence Avenue
Winnipeg, MB R3T 1T4 Canada
direct 204 453 3339 x309
fax 204 452 7156
-
www.parker.com/ecd
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
Here is your part.
Changes include:
· Converted profile to GRAPH feature. Scaled dimensions to simplify
the VSS for 360° rather than using the arc length as you had defined. This
simplifies the CAM path and allows for easy modification. Also, modified
splines and converted complete sketcher/graph to spline (one entity in
sketcher graph).
· VSS paths use new GRAPH and sweep as I had illustrated yesterday
(origin & X-vector to control orientation). Note: both VSS use same graph
to drive the path over 360°
· VSS is extended outside of outer surface and inside of inner
surface then merged.
Hope this helps everyone.
Tim McLellan
Mobius Innovation and Development, Inc.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
the cutting tool in the assembly.
Please download the latest example which includes Tom's part updated and an
assembly where you can simulate the tool cutting (mechanism).
Have a great weekend,
Tim McLellan
Mobius Innovation and Development, Inc.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
[cid:image001.png@01CD10EF.4AB88FD0]
[cid:image002.png@01CD10EF.C4458150]
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator
I created an angled offset axis and revolved the profile around it.
But I think this may not be what you are calling a barrel cam.
In Reply to Tom Uminn:
I'm looking for ideas on how to properly model the slot in a barrel cam. I have attempted multipe techniques and I'm starting to spin my wheels. I have an idea that what I want to do can probably be done with the variable section sweep, but that feature is definitely not my area of expertise.
I've worked through the "wave washer" suggested technique on PTC's site (http://www.ptc.com/appserver/wcms/standards/freefull_cskdb.jsp?&im_dbkey=88651&icg_dbkey=900). The problem with this exampl is that the part is not a constant thickness (whereas my cam slot needs to be). To get a constant thickness, I changed the sketch profile to a single line, which created a single wavy surface, and then thickened it. Problem is, the sides are no longer vertical. To get around that, I lengthend the VSS section to include some extra on each end, then extruded inner and outer cylinder surfaces, merged everything together, and solidified. This succeeded in creating a constant thickness washer with straight sides.(See attached PDF.)
Problem is, thistechnique does not transfer well to the cam. The centersurface won't offset nearly as far as it would need to. Creating inner and outer curves and building boundary blends didn't work either.
Tom
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator