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Preventing Distortion on Flat Plate

General welding questions that dont fit in TIG, MIG, Stick, or Certification etc.

Re: Preventing Distortion on Flat Plate

Postby Olivero » Thu Apr 20, 2017 1:46 pm

Well.....

Weld it and beat the piss out of it? That's what I do :D

The idea of leaving a gap between the plate and pipe is good, I have done it that way.

You can minimize it by welding a little bit at a time. I have warped 3/8" flat bar just by welding on and on and on without stopping, then I beat the piss out of it.
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Re: Preventing Distortion on Flat Plate

Postby PeteM » Thu Apr 20, 2017 2:17 pm

Olivero wrote:
Weld it and beat the piss out of it? That's what I do :D



.


Reminds me of some botched up keel plates I used to get some times when the sub-arc seam welder was out of whack.

Supposed to be relatively flat. Actually shaped like a pringle!
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Re: Preventing Distortion on Flat Plate

Postby cjarnutowski » Thu Apr 20, 2017 2:55 pm

Wow, first of all thanks to Jody for cultivating a very helpful community.

I have an OA torch. The plate is HR A36. We can safely assume the loading condition is static, these are columns to support conference tables which will be bolted to the floor at the plate. Not sure if I mistakenly stated the wall thickness of the tube as 1/4", but it is in fact 1/8" wall. There is no tolerance, the reason I want to prevent distortion is to make leveling the columns easier.

Nonetheless I am taking this as a learning experience. Would anyone mind giving me a quick overview on flame straightening in this situation?

My concern with preload is that I'm trying to bend the plate in 2 axis, essentially cupping the plate in the opposite direction. Seems difficult to achieve with just clamps.

Thanks!! Chris
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Re: Preventing Distortion on Flat Plate

Postby motox » Thu Apr 20, 2017 4:18 pm

why don't you go ahead and weld one and see how much it cups.
then you will have a better idea what to do to correct the cupping.

or just beat the piss out of it when it done, can't go wrong there.....
there is always a bigger hammer...
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Re: Preventing Distortion on Flat Plate

Postby exnailpounder » Thu Apr 20, 2017 4:23 pm

Arclight Ironworks wrote:
cjarnutowski wrote:....I am welding a 3"x.25" round tube to a 24"x24"x.25" plate, dead center. The material is steel and the process is TIG. I was hoping to hear some of your tricks for preventing the plate from "cupping" up toward the post on the side of the weld...


What can you tell use about the intended use of this welded item? Static, dynamic, cyclical loading? Access to oxy-propane or oxy-acet torch?

Option #1. Micro tack the 1/4in round tube to the surface of the 1/4in assembly plate. 4ea 1/2" long tacks at cardinal positions on the clock. Cut 2ea 3/32" TIG filler wires into 24" lengths. Set aside. If available, sever another section of 2ft x 2ft x 1/4in steel plate as fixturing for your 1/4in assembly plate.

Stack up, from bottom to top. 1/4in fixture plate + 3/32" TIG filler at third-points on the surface of the 1/4in fixture plate + 1/4in assembly plate. Clamp the fixture plate to the assembly plate, bi-diretionally. This sandwiched arrangement "preloads" the system and introduces a micro-camber. Note, a fixturing plate is not req'd and you can easily camber the assembly plate directly to your welding table.

Weld the unit in quarters (e.g. 12 to 3 o'clock, then 6 to 9, then 6 to 3, and finally 12 to 9). Allow unit to cool, completely. Unclamp the assembly plate from the fixturing plate (or weld table). Inspect and FlameStraightening, as required, via oxygen-pro/acet torch by applying heat to the BOTTOM of the 1/4in plate.

Option #2. Disregard the 1/4in fixture plate approach. PreHeat the tube and entire assembly plate to 150F. Tack, followed by weldout a la the above technique. Allow the unit to cool. Inspect and FlameStraighten.

Unsure if you are experienced with oxy-fuel and FlameStraightening. We could walk you through the baseline technique if you have access to the equipment.

Understand that you cannot PREVENT heat from doing it's thing. Ever. Even placing a Battleship or M1 Abrams Tanks on the system as fixturing will not prevent warping. Minimize, yes. Eliminate, no. Atoms within the Elements are of star dust. Strong and Agile like the HoneyBadger.

Approach heat as a "tool". Apply to your advantage to affect the geometry during weldout and minimize distortion. In this situation, TIME between welds and attack approach are your allies.

Do all this :lol:
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Re: Preventing Distortion on Flat Plate

Postby Arclight Ironworks » Thu Apr 20, 2017 6:10 pm

@ cjarnutowski - you have an OA rig. Good. Oxy-Acet bests an Oxy-Pro rig for flame straightening because the highest flame temp is CLOSER to the torch's tip and you can deliver a tight/tight heat intensity without diffusing the flame over a larger surface area as with Oxy-Pro. Thermodynamics in action.

Watch/study the below video. Use a large cutting tip, straight edge, and apply heat along a given line at a steady rate. Use a spray bottle with water to quench the heated area after a run. If you need additional runs, apply heat ONLY after the plate is cool/cool to the naked hand. Flame straightening is art and science blended. Patience and practice mastering this technique will serve you well in the future.

http://www.youtube.com/watch?v=0BI6itb9IpA#action=share
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Re: Preventing Distortion on Flat Plate

Postby exnailpounder » Thu Apr 20, 2017 6:48 pm

O boy..somebody trying to sell something again... :lol:
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Re: Preventing Distortion on Flat Plate

Postby Otto Nobedder » Thu Apr 20, 2017 8:08 pm

exnailpounder wrote:O boy..somebody trying to sell something again... :lol:


The video ends with an ad, but the information is sound. I use to do structural steel, and cambering beams was a task I got pretty good at. Now that I work primarily in SS pipe and plate, I've become quite good at pre-loading or pre-fitting a joint to allow for the shrinkage.

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Re: Preventing Distortion on Flat Plate

Postby clavius » Thu Apr 20, 2017 10:01 pm

This has been posted before, and while it seems hokey, the principles are sound and still apply:

https://www.youtube.com/watch?v=2vuGlcbDwKY

Besides, I really like that evil Mr Distortion guy. May or may not address exactly what you are working on, but there is some good basic info here if you watch it and pay attention.
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Re: Preventing Distortion on Flat Plate

Postby Olivero » Thu Apr 20, 2017 11:01 pm

Well. You could also do some stitch welds on the plate to the table, then when done, cut it off and grind the welds down. I have heard of that working really well.
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