to manufacture an internally stiffened plate made from sheet steel 4

[hmalfs]

Hello all,

I am trying to manufacture a ribbed plate that is reinforced inside with stiffeners. I can weld the stiffeners to one plate, but then I want to weld the other plate, and I can't access the reinforcement. The stiffeners have low thickness, like 2-3 mm. I´m attaching a picture of a FEM model done in ANSYS using shell elements. I want to add a plate to the bottom, similar to the one on the top, and know how can I weld the added plate to the reinforcement. Or is there any better way of manufacturing this??


regards,
Hugo

 

[btrueblood]

Fold a tab on the stiffeners, and put holes thru the second plate, attach stiffener to plate via plug welds, or fasteners. Or braze the assembly, provided you have a big enough furnace.

 

[Compositepro]

Furnace braze the assembly. Sheets of brazing metal are placed between the plates and melted in a furnace to fuse the whole assembly together.

 

[Tmoose]

Do you want/need each stiffener to remain full section as it passes thru the prependicular stiffeners on its way to the other edge?

 

[MikeHalloran]

I find it odd that you would use parallelogram stiffeners, instead of fully triangulating the grillage. Maybe it doesn't matter with your loading.

Also take a look at the 'decks' manufactured for Skylab, milled from solid metal, using something resembling a keyseat cutter to remove large triangular cavities from the middle of the billet, leaving behind somewhat smaller triangular openings in one face.





Mike Halloran
Pembroke Pines, FL, USA

 

[MintJulep]

Laser welding, maybe.

But I agree with furnace braze.

 

[prex]

With laser cutting you can cut slots in the second plate and also have the ribs protrude inside the slots, then you can weld from outside.

prex
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[hmalfs]

Hi,

Thanks for all the replies.


To CompositePro:

I would like to know more about Furnace braze. Can you post a document about its fundaments, with schemes??


To Tmoose:

Yes, all the stiffeners are full-section


To MikeHalloran:

Can you post the link?? I can't find it on google


MintJulep

I agree with laser welding. The problem is that we can't really see the welding joints to do a good through-thickness welding. Any suggestions on making it more effective??


prex

The problem is that if I cut the slots on the second plate, I will have many separated triangles, not only one part. Do you suggest cutting the 2nd plate in triangles and then weld the triangles by through-thickness laser welding??


thanks,
Hugo

 

[MintJulep]

I was thinking of shooting the laser at the "show" sides of the top and bottom plates.

 

[Tmoose]

"Yes, all the stiffeners are full-section"

So you are also going to weld a bunch of short rectangles to a few long rectangles to form the grill?

 

[Tmoose]

"Yes, all the stiffeners are full-section"

So you are also going to weld a bunch of short rectangles to a few long rectangles to form the homogenous ice cube tray grill? Either before attaching it to the sheet, or at the same time.

 

[hendersdc]

As prex said you could cut slots in the plates and plug weld from the outside. If you have tabs on the ribs that mate up with the slots it will make everything much easier to locate for welding. Attached is a quick example of two slotted plates with nesting ribs. I used 90 degrees as the angle between ribs becasue it was much easier to model up quickly.

Doug

 

[Tmoose]

What is the spacing between the stiffeners?

 

[tbuelna]

hmalfs-

As others noted, thanks to the modern miracle of CNC water jet machines, it would be easy to design your skins and webs so that they are fully self-fixturing using tabs and slots. The webs could be cut with alternating slots half-way thru their width at each intersection, so they would be self-aligning and could be fillet welded. And the skins could have slots cut into them that mated with tabs on the webs that only slightly protruded into the slots. This would allow plug welding between the skins and webs. Much cheaper than furnace brazing.

 

[KENAT]

Another vote for looking at the tab & slot approach.

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