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"rolling" a sheet in Creo

ptc-4401544
1-Newbie

"rolling" a sheet in Creo

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 see how they line up when this sheet is rolled up into a cylinder. I have the sheet ready, but I cannot figure out how to "roll" it up virtually. Is this even possible?

Thanks in advance!

59 REPLIES 59

Toroidial bend is probably your best option.

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?

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

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.

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

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).

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

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

Hi, I am rolling it into a cylinder.

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

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?

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.

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

Who ya gonna call?

Ok, so he owes us beers!

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.

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.

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.

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!

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.

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

Hah! Beating me up with my own technique.....irony?

Yeah, I'd imagine that with rounding errors wrapping thin sheets where, essentially, the solid created touches itself (in a bad way.....CADsturbation??) as it wraps around could cause failures. If it's layered, perhaps make it a family table where the insulating layer (instance) and the "plate" layer 9instance) don't exist at the same time in the .prt file, but do only at assembly? That way, the solid isn't touching itself (or it'll grow hairy palms and go blind..). Without seeing the actual geometry he wants to create, I'm just guessing, but......

I also, before I created any geometry, set my accuracy to absolute and to the most accurate setting.

Best of luck!

Hi, Pum.

Just out of curiosity, have you tried using the Flatten Quilt feature to create the geometry that you are going for? If you create (extrude) the coiled "roll" as a surface, then flatten it. From there you can thicken the flattened quilt and create other geometry features like cuts, and then re-bend back to the original shape using the Bend Solid feature ("Flatten Quilt Deformation" in Creo). I have used this technique in the real-world with great success. You can even create Reps of the "flat" and "coiled" versions of the part if you want to go that far.

Might be worth a shot....

Best of luck!

Hi Evan...

This was one of the first techniques I tried. Unfortunately even with the accuracy set as tight as possible, the flatten quit/bend solid techqniue couldn't handle the roll-up Pum was trying to create.

It does work very well for all sorts of bent geometry if you're careful to build features while maintaining contacts with the flattened quilt. However I think in this case the tightness of the roll kills it.

The system shows a representation of what the solid should look like... but it shows it only for a fraction of a second before the failure message pops up. I've tried shrinking the coil and lessening the complexity of the geometry but it still crashes. I have to GREATLY simply the geometry before it finally succeeds.

Take a look at Pum's example model and the images Frank S. posted. If you have time, maybe you can try it with flatten quilt just to get another set of eyes on it. Maybe I missed something and you'd have better luck?

Thanks!

-Brian

Haha, somehow I missed that entire reply of yours. I may play around with it further and see if I can find a solution. I imagine there MUST be a way to get it to work. I have found that sometimes it's just a matter of what order you do things in, instead of what things you do. In the real-world case I had mentioned, the geometry was pretty complex and the only way I got the failures resolved was to do everything with surfaces and then thicken at the very end.

I'll let you know if I get anywhere though.

Wow quite a lively discussion you have going on there.

Just a quick question, since you both seem to know a lot about this.... Do you have any idea how I could make a model bendable? In this case, I'm trying to "bend" a tab on the jelly roll around some features, but I can't think of an easy way to do this. Since this tab is so thin, it will be bent in many different ways so I would very much like a dynamic way of just dragging and bending with a mouse. Does such a feature exist?

Whoops! I answered this in your other thread. If you want to bend and twist sort of "on the fly", you're definitely talking about a Warp feature. This feature has several subfeatures that allow you to play with the model as if it were virtual putty.

The problem is that it doesn't necessarily bend in a real-world manner. The model doesn't behave with real world physics or anything... it just moves and twists with the mouse. You'll have to be careful to apply the bends and keep the tab geometry realistic.

If we can see what you're doing, it's easier to help. There's also some rarely used features in sheet metal and a practically UNKNOWN feature in regular Pro/E that can help with bended tabs. One of my all-time favorite forgotten Pro/E features is the EAR. The Ear can do some pretty cool things with tabs.

Once we see a picture I'm sure we can help more.

Thanks!

-Brian

Fold.bmp

Sorry, I should have been more precise in my question. I have two problems. This is my first.

I need to "fold" the circular ridge onto the rounded cap (basically crimp the cap into place with the circular ridge). I could do this manually, but I'm sure there must be an easier way.

Hi Pum...

If you aren't super concerned with how completely real-world the result is, you can definitely do this with a Warp applied just to the very end of the cylindrical lip. It would look pretty nice. I can try one for you... oh yeah but first I have to finish the OTHER documentation!

I'm so behind!

You might also be able to use the Toroidal Bend feature to do it but I am not sure. I need to take a harder look.

Thanks!

-Brian

Hi Brian,

^^ Wow... If you don't mind me asking, what do you do for a living? You really know your stuff. I'm a senior undergraduate studying MechE, but I feel like I have so much to learn...

Did you take any formal classes or did you self-learn everything?

Hi Pum...

I feel like I've been doing battle with the software today. Everything I try seems to have some oddball twist that makes the problem harder than it should be. First, let's deal with the folded edge you need to crimp the rounded cap into place.

Now that I'm writing this, I wonder if I've even done what you need. If you truly needed to FOLD the edge (what's known as a HEM edge in sheet metal), I completely went in another direction. Ugh. We'll cover that in a minute. Here's what I came up with...

Slide1.PNG

Slide2.PNG

First I suggested using a Warp feature to create this geometry. Many of the Warp Tools have a "Marquee" which allows you to select an area of your model to affect with the tools. For instance, you can twist an entire model using the Warp Twist tool... or you could twist just a small area of the model selected using the marquee. I saw at least 3 or 4 of the warp tools that would probably work.

I tried the main Warp tool (which is confusingly also called "Warp"). This could produce a quick estimate of the geometry shown above. However, this tool lacks a marquee feature so it kept wanting to modify the entire model and there was no way to stop it. I had to eliminate this tool.

Next I tried the Warp Sculpt tool. This produced good results... and makes a very realistic crimp. The downside is that required an intensely manual manipulation process to achieve these results. The effort required to produce the effect was not worth the time spent. I had to eliminate this tool, too.

Next up, the Warp Spine tool. This allowed me to pick the rim of the tube and manipulate the edge by pulling it inward to the center of the tube while "crimping". Very nice... and it did have a marquee control to limit the crimp zone. However the tool could not be automated. It, too, required heavy manual manipulation and wasn't worth the time spent. I eliminated this tool, too.

I briefly tried the Warp Stretch tool but this did not provide a control to shrink the rim inward (as if it were rolled or bent around the inner cap). Therefore this was the wrong tool for the job and was eliminated.

Finally, I tried the Warp Bend tool which was my original idea for this feature. No matter which way I manipulated the marquee, I couldn't get the right options to fold the edge the way I hoped. Ironically, if I wanted to roll a flat sheet into a tube with a bent edge, I could DO that. I couldn't bend the edge of an already formed cylinder, though. Amazingly, I had to eliminate this tool, too.

By this point I was pretty frustrated. I wanted a simple, easy, parametrically controlled solution. I wanted a solution that could easily be used in a family table OR as a flexible feature. Either of these would provide you with a method of showing the edge before AND after the fold. I assumed you'd need this for drawing and documentation purposes.

As it turns out, there is one pretty easily solution which creates the entire fold in two features. With a simple table or flexible feature, you can show the cylinder before and after the fold. This seemed ideal so I went with it. To achieve the effect, I used a Solidify with Surface Replace option.

Surface Replace has always been (in my opinion) one of the coolest features Pro/E had. It's been around for at least 20 years. What makes this feature unique is that is can both ADD and REMOVE material from the model simultaneously.

I began with a simple cylinder. Next, I added a revolved surface representing the folded/crimped geometry. Note that this was a surface, not a regular revolved solid. The edges of the new surface touched the edges of the cylinder (this is a requirement for a surface replacement to succeed). Finally, I created a Solidify feature with the Replace option turned on. Most people use Solidify to turn a surface into a solid extrusion to add material or a solid cut to remove it. The fact that there's a replace option at all often goes unnoticed. By using this option, I was able to trim off the last .25" or so of the straight cylinder and replace it with an equal amount of folded/crimped cylinder all at one time.

Before I go through the slides to demonstrate each step, I figured I'd see if this is even close to what you wanted. If its not going to be of any benefit, it's probably not worth the effort to make the slides. It's still cool... but I want to do something to help you with your problem, not just post tons of slides that don't really offer anything useful.

Let me know if the images above are close... or if you needed something different.

Thanks!

-Brian

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