Sheet Metal - single line cuts

[gp13]

We have a lot of parts that have long cuts where the lines are about a tenth of an inch apart. The problem is when the laser goes over the first long cut, and then back along the second line, there is a lot of splatter, the metal gets too hot, and best case scenario is the laser stops cutting (worst case is the lense gets ruined).

To circumvent this problem, after we create our DXF for a given part, we open the DXF and delete the bottom (longer) line and then corner the two vertical lines with the top (shorter) line. The end result works great, but the process is very tedious, and must be done every time you change the part. I am always trying to eliminate parts of the design process that require modification to anything after the part has been created, and this is a big one for us.

I was curious if anyone else out there has ever run across this type of issue, or if anyone knows a good work around. I've tried making the two edges meet in the flat, but that creates two overlapping lines on the DXF. While that is easier to modify in the DXF, it doesn't really fix the problem.

The attached JPG shows the part in the flat state, and the DXF after I modified it. Also, I'm currently on 2009.

Thanks in advance,

Matt

 

[DiegoLGraves]

Matt, we'd put the line connecting the two end cutouts on layer "open" (works with NCexpress and Ncell), and the two openings on both sides on layer 0. But that sounds similar to what you already are doing. We haven't found any better workaround, either in exporting from the part file or saving the flat pattern from the drawing.

At the laser however, if you can cut with nitrogen rather than oxygen you will probably get better results.

regards, Diego

 

[gp13]

Thanks for the response Diego,

We actually do cut using nitrogen as far as I know. Layering presents the same problems (and opens up an entire other issue we have as well) since you have to create the DXF first, then go into the DXF and edit the lines since you can't change the layers of edges in the drawing. I have tried hiding the edges, and drawing over them, which kind of works but is very susceptible to problems since the lines are still there if the part is modified.

Preferably, I want to eliminate modifying the DXF if at all possible. I figure that's highly unlikely, so the next best thing would be to have some sort of error catcher if the DXF remains unmodified. For example, when I made the part so the flange flattened flush to the edge, it created 2 overlapping lines which I hoped the laser software wouldn't be able to cut. Unfortunately, it doesn't catch them since it can actually form a path to cut both lines continuously.

 

[ShaggyPE]

Can you eliminate the clearance along that edge... so when you look at the flat pattern, the two edges are in fact one? The drawback would be that your formed part (model) wouldn't be exactly accurate.

-Dustin
Professional Engineer
Pretty good with SolidWorks

 

[gp13]

I tried that, but on the DXF it has 2 overlapping lines, not one line that takes place of both. That means the laser will go over the the same cut twice, which is not the intended result. Initially, I figured that would cause an error in SolidWorks when you were looking at the flat pattern, but to my surprise there wasn't one.

 

[ShaggyPE]

With the overlapping lines... Is it possible that there is a command or macro that could eliminate that. Seems like a band-aid for a band-aid though.

-Dustin
Professional Engineer
Pretty good with SolidWorks

 

[gp13]

Double band-aids could be a solution. As long as it works and requires minimal user input, then I'm all for it. The only problem is that would have to be done on the drawing (that's where we get our DXFs from) and I just don't know how to consistently and automatically hide that edge. Any thoughts?

 

[applejack2]

what program are you using to view/manipulate DXFs? If Autocad, then you should be able to find a macro/add-on that will remove duplicate lines.

for example

http://cadecorner.blogspot.com/2007/12/delete-duplicates.html

 

[gp13]

We just use SolidWorks for that since it's only done when necessary. Any solution for this ideally would be in the SolidWorks drawing file, because I do not want to have to touch the DXFs once they are created.

Would the lines in question even be considered duplicate though? Duplicate to me would mean they are the same length and in the exact same location. These lines overlap, but are not duplicate because the one I want to use is longer than the one I would need to delete.