topic Re: "rolling" a sheet in Creo in 3D Part & Assembly Design

"rolling" a sheet in Creo

ptc-4401544 — Tue, 10 Jan 2012 18:16:54 GMT

Hi there,I've been a Creo Parametric user for around a year now and I've run into a problem that's stumped everyone around me...I'm designing a sheet that will be rolled up into a cylinder. This sheet has irregular markings on the top and bottom edges, and I need to

Re: "rolling" a sheet in Creo

Patriot_1776 — Tue, 10 Jan 2012 18:21:49 GMT

Toroidial bend is probably your best option.

Re: "rolling" a sheet in Creo

ptc-4401544 — Tue, 10 Jan 2012 19:56:43 GMT

I was thinking about that, but I'm not too familiar with toroidial bends. Is it even possible to bend it over itself multiple times? Basically, the sheet will form a thick cylinder with multiple layers after being rolled up. How would I go about doing this?

Re: "rolling" a sheet in Creo

BrianMartin — Tue, 10 Jan 2012 22:50:40 GMT

Hi Pum (or Pum Sang)...

I encountered this exact same problem when working for a battery company. They had very long, thin sheets of metal that needed to be rolled into a tight coil. There are some methods you can use to "roll" your sheet, but all of them have some problems you'll need to be aware of.

For this kind of thing, I think a spinal bend is a better choice than a toroidal bend. A toroidal bend will do a nice job of rolling the sheet but it won't keep rolling it back on itself like a spinal bend can. I think you're going to be stuck though when the solid geometry begins to self-intersect. I'll do a quick example and upload it for you to take a look at. If all else fails, you can make your object as a surface and see if that gives you the information you're looking for.

Fair warning... the tighter you try to wrap the sheet, the more difficult it's going to be to get what you want. I'll try to explain that in the next email. For the time being, play with spinal bend. I'll make the object and try to take some screen shots for you.

take care..

-Brian

Re: "rolling" a sheet in Creo

Patriot_1776 — Wed, 11 Jan 2012 00:14:14 GMT

Pum: Are you rolling it into a cylinder, or into a spiral of Archimedes?

Re: "rolling" a sheet in Creo

ptc-4401544 — Wed, 11 Jan 2012 01:20:51 GMT

Hi, I am rolling it into a cylinder.

Re: "rolling" a sheet in Creo

ptc-4401544 — Wed, 11 Jan 2012 01:25:38 GMT

Hi Brian,

Thanks for the reply! It's a very similar application to the battery (I believe we are thinking about the same parts). It would help me SO much if you could give me some guidance on the matter.

By surface model, do you mean simply extruding a cylinder? I have done that already for quick measurements, but it does not provide me with all the information (for instance, where various features on the flat sheet end up when rolled into a cylinder).

Yes, I will definitely look into spinal bends; hopefully it will give me the jump start I need. I look forward to your next replay. Thank you.

Re: "rolling" a sheet in Creo

BrianMartin — Wed, 11 Jan 2012 06:09:36 GMT

Wow Frank...

With the words "spiral of Archimedes", you completely opened a can of worms. That set me off in a direction on this problem for Pum that took me hours off course. But ... that research lead me to a solution to a problem I've been working on for about 6 weeks. I feel like I've cracked the DaVinci Code. But more on that in another thread.

For now... yes, we're trying to roll this thing into a spiral of Archimedes. I know Pum said "cylinder" but I'm certain we're interested doing a virtual version of a roll of paper towels which is cylindrical... but also a very tight spiral as you've noted.

Thanks!

-Brian

Re: "rolling" a sheet in Creo

BrianMartin — Wed, 11 Jan 2012 06:34:44 GMT

Hi Pum...

When I mentioned using a surface model, I didn't mean simply extruding a cylinder. I meant using a surface to create the complex geometry of the coil rather than a solid. Surfaces regenerate quickly and are much more robust than solids. Sometimes you can create a piece of geometry as a surface even when creating it as a solid would fail.

In this case, I went back and tried several different techniques to generate the "roll up" you were looking for. I was surprised to find I actually couldn't use ANY of them to create the proper geometry. First, I tried the spinal bend. I was fairly certain I had used this previously and it worked just fine. However, I generated a spiral to represent the coiled geometry and then tried to bend a long flat strip using it. Although I've made many spinal bends that turned back upon themselves, this totally failed. As soon as the coil made more than one turn, the solid crashed. I had some ideas which may salvage this idea but didn't have a chance to try them yet.

For the second method, I used a combination of a Flatten Quilt and a Bend Solid. I began with a tight coil and then flattened it into a long flat strip. I realize this isn't what you were trying to do. You already HAVE the strip, now you need to roll it up. I was merely trying to find a technique that actually worked. I had some decent success with this technique but as the length of the coil increased (and therefore the straight length also increased), the technique failed. I set the model accuracy as tight as I could (.0001) but still couldn't get a realistic roll up. It's strange to note that, for a moment, the screen displayed the CORRECT geometry... then removed it and put up the error message saying the geometry could not be constructed. Some tweaking and more investigation might isolate the problem with this approach.

I'm pretty sure the biggest problem is the very first coil at the very core of the cylinder. This turn is so tight as the cylinder radius decreases to zero, I believe THIS is causing the problem with the second technique.

I also tried modeling the coil and generating the roll up using a Variable Section Sweep, a regular Sweep, a swept surface, a datum ribbon, and a Warp Bend. None of these attempts produced anything worth noting.

So then to recap... I haven't been able to do exactly what you need yet. However, I did get a representation of a long, flat strip to wrap around a very tight, very realistic coil. I used a WRAP do to this. I started with a long, flat strip. I made several holes and created some protrusions along the edges (like gears and sawtooth shapes). Then, I generated a Curve by Equation using a Cylindrical coordinate system. This creates a very nice coil (a spiral of Archimedes) with a diameter and a given number of "wraps". In the final part we'd set these values by relation and drive them from the long, flat strip. Next, I used the curve generated from the equation to create a coiled surface. Finally, I created the WRAP feature by selecting the coil and creating a sketch to mimic the outline (and all edges) of the strip.

I need to generate some screen grabs because I realize this sounds complex. It actually isn't very difficult at all but it's going to take some time to document. I'll continue this thread tomorrow. I just wanted to post some progress and some ideas if you're still working on this independently.

Thanks and take care...

-Brian

Re: "rolling" a sheet in Creo

Patriot_1776 — Wed, 11 Jan 2012 16:43:30 GMT

Cool! I often get off on tangents like that......with the same result. Too bad we don't have the opportunity to work together......yet.

What was the problem you solved, and how?

As a NASA Engineer once told me: ""Thinking out of the box" does not describe you.....you're not even on the same planet!" I liked working with Paul.

P.S. So, do I get a beer for helping you solve your problem?

Re: "rolling" a sheet in Creo

BrianMartin — Wed, 11 Jan 2012 17:02:24 GMT

Actually you helped me solve a problem for Dalbeer Singh... and as soon as I finish writing it up, I'll post it.

These threads are getting all crossed up. Topics are crossing between discussions. We need to start some new threads. Or... maybe I just need to start that blog I've been trying to avoid. I just know I'm going to get sucked into it and I'm trying to resist.

Re: "rolling" a sheet in Creo

Patriot_1776 — Wed, 11 Jan 2012 17:25:08 GMT

But......I thought we were never supposed to cross the threads????

Who ya gonna call?

Ok, so he owes us beers!

Re: "rolling" a sheet in Creo

ptc-4401544 — Wed, 11 Jan 2012 19:48:34 GMT

Wow, that is quite a reply. You, sir, are extremely organized and far too helpful for your own good. I truly appreciate the help you are giving me on this matter and I am not lying when I say that I'm not only relying on you for a quick answer. I am trying out everything I can think of as well and learning a lot from it. Your guidance is invaluable and I can't thank you enough.

If it helps, this is an attempt to CAD a jelly roll of a battery (probably exactly what you were thinking of).

Re: "rolling" a sheet in Creo

BrianMartin — Wed, 11 Jan 2012 19:52:47 GMT

Aha! YES! Exactly what I was thinking of.... a jelly roll for a Li-Ion battery. I sincerely hope you're not working for the same company I used to work for... egad yuck!

For my demonstration model, I made a long flat strip with some terminal tabs sticking out the top and bottom. The roll-up should show how the tabs align in the cylindrical state.

I have some images to share and I'm trying to document what I'm doing but I keep getting sidetracked. Stay tuned!

Thanks!

-Brian

Re: "rolling" a sheet in Creo

Patriot_1776 — Wed, 11 Jan 2012 20:53:01 GMT

Is this something like what you want? I whipped this up in about 10min. It doesn't have notches, but you can see in it's developed length, it has a smooth taper from the tabs to a full radius.

Re: "rolling" a sheet in Creo

ptc-4401544 — Wed, 11 Jan 2012 21:27:27 GMT

It is quite similar. However, I'm wondering what that helical tab in the middle is for. What I need is basically a piece of paper laid down, then rolled up along one of the edges. It needs to be done quite tightly with minimal clearance. But yes, the shape is most certainly there and looks like a good start.

Re: "rolling" a sheet in Creo

Patriot_1776 — Wed, 11 Jan 2012 21:49:59 GMT

I did that just for fun to see what can be done with a particular technique I have. If you need both a flat and a coiled version, you can do one part as an instance of the other, in your case it sounds like the coiled version would be the instance of the flat version. That part took a total of 7 features excluding the initial datum planes and CS. So, it's actually a pretty simple technique.

Re: "rolling" a sheet in Creo

BrianMartin — Wed, 11 Jan 2012 21:57:36 GMT

Yeah Frank... it's the exact technique I've been trying to document since yesterday. Thanks for letting the cat out of the bag!

The giveaway to how you did it is in the center. Looks alot like a wrap!

Re: "rolling" a sheet in Creo

Patriot_1776 — Wed, 11 Jan 2012 23:22:32 GMT

Hah! Sorry for stealing your thunder bro. Well, all this spiral talk got me thinking, and since I'd wrapped all those spring trajectories I'd sent you around a cylinder, combined with all that talk about "jelly-rolls", I got to thinking about how I'd never tried it on a spiral of Archimedes and all, and, bada-boom, bada-BING! I was pretty happy, I got the example done in like 10 min. I've never had a use for it, but, I can imagine now people could. He threw me when he said "cylinder", which to me meant exactly that, not a spiral of Archimedes.

Cool! I'll be eager to see the write up, and glad I could help!

P.S. They still owe us some beers though!

Edit test

Note: Editing the reply changes the date of the "original" reply, which confused the hell out of me, especially when you changed your reply above to detail the method. I was like, whaaaa????? Most forums give a separate "edit" date/time, not changing the original. Ok, for a minute I thought you'd designed a time machine instead of simply a large marshmallow-man killer raygun.....

P.P.S. One issue Pro/E has is that the surface must be at least a little bigger than the developed curve you're trying to wrap. If it "falls off", it'll fail usually. This might be the problem you mentioned.

Re: "rolling" a sheet in Creo

BrianMartin — Thu, 12 Jan 2012 13:45:47 GMT

I was just giving you grief. The only technique that seemed to work without issue to wrap this thing was the one I got from you. So I thought it was funny to chastise you for using your own technique to solve the problem.

It gets tougher when you tighten the spiral... and this is what Pum needs for the battery. It's funny that the application is exactly the same. When I worked at Saft America (battery company), we tried numerous methods to create both a rolled-up "jellyroll" and a flat with fully developed length. We could never get the "roll" tight enough to be realistic. We're talking a very tight roll with ultra thin layers of two metal sheets being rolled together.

The goal was to be able to automate the final welding operation required to complete the battery... which used to be this intensive manual process.

Anyway... I'll keep working on the documentation.

Take care...

-Brian