Sheet metal project from Hell

Jim Canale

My boss wants me to model a supplier's sheet metal housing (the back tray for an LCD module), and make modifications to it.   This is far beyond my current skill set.  I was wondering if anyone here could give me some guidance?

The metal is only .016 thick, and and besides flanges on all four sides, it has cutouts, threaded and unthreaded dimples, retention snaps, etc.    It even has a "S" jog in the metal if you look very closely at the edge of the tray, over to the left.   The "S" jog raises the height of the panel a mere .008" along one edge.      I'm not sure if I should start by modeling this as a solid block, and cut out everything inside, or whether I should do some or part of this with the sheet metal tools.   Ultimately, after I have modeled the piece, I will have to edit it, to add to the height, in such a manner that the retention snaps will still hold the front and back halves together.  I'll attach a few pictures so you can see what I am up against.   

Not having much experience with sheet metal, my first question would be...   If you add or subtract solids to a sheet metal "base flange", how does that affect the ability of the unfold tool to obtain a correct blank?   Secondly, is there any way to "stretch" the metal to form the dimples and retention snaps?    And what about the "S" curve?     The yellow film is just a plastic overlay, which will be removed as I make my measurements. 

I am concerned about putting an enormous amount of time into this, and then not being able to finish the edit, or extract the unfolded blank.  

Thanks for taking the time to read my post.

Jim

Richard Webb

Manufacturing will require tooling up a stamp, not just making bends with a metal brake, so I don't believe that going to the sheet metal tools and expecting to be able to unfold it to a manufacturable shape will be successful. Will your company be forming the sheet metal or will it be farmed out to a firm that specializes in sheet metal?

If the latter, I would (and have, for items I've drawn for the company here) just concentrate on getting the final shape right. Something like, start with a rectangle that captures the footprint, extrude it to the height, and then shell it to get the basic shape. Make the cutouts and fillet all edges/corners that need it. (You could probably go this far with the sheet metal tools if you're comfortable with them.) The interior "S" shapes are just extrusions that you build and then add to the base tray. The raised portion (with the seven dimples) could be done in several ways; maybe imprint and raise a face for the bump up, imprint below that and push up for the right thickness, then fillet the resulting edges. Poke holes where the "domes" go; the domes themselves are just truncated cones that have been shelled, combined with the basic tray, and then filleted.

Jim Canale

 Richard,

Thanks for replying.  No, we have no capability to manufacture this in house.    I was hoping that beginning the drawing with BricsCAD's  sheet metal tools might speed things up. 

You said,

  "The raised portion (with the seven dimples) could be done in several ways; maybe imprint and raise a face for the bump up, imprint below that and push up for the right thickness, then fillet the resulting edges."

Can you elaborate?  I can't find a tool called "imprint".  Is there a way to raise just a portion of a face?

Richard Webb

It's under Models | 3D Solid Editing | Imprint, and also on the 3D Solids Editing toolbar (it's the thing that looks like a cube with a line on its surface). Drop a rectangle (in this case) on the surface and "imprint" it. You can then use direct modeling (the quad cursor is helpful here) to extrude just that portion of the face within the imprinted area.

You could perhaps do it using the sheet metal tools, but it looks like the example has a continuous "S" curve rather than two discrete flanges so you would be running two bends right on top of each other. Might have to play with the parameters to get the sheet metal tool to be completely happy in those circumstances.

Jim Canale

 Thanks again Richard.  No mention of the command in the"Help" menu.  And if I try and enter "imprint" or "_imprint" on the command line, it's not recognized either.  I will experiment with the command and get back to you.  Right now I am dealing with another bug that crept into my installation.