distortion query

Any ideas which way these panels set back to back will distort?? We have two points of view on this one. When separated will the plate end up concave or convex? A Mcdonalds hot apple pie is riding on this. We big time gamblers here.:')) Randy

formatting link

Reply to
Randy Zimmerman
Loading thread data ...

The side that gets welded first will have the "dish".

Looking at it, the order of welding will probably have more effect that the shape of the object. Will you really gain anything by doing them back to back?

If I were doing them, I would try and get two welders going on them, one either side.

Wayne

Reply to
Wayne Bengtsson

"Randy Zimmerman" wrote in news:l1Yxb.518673$pl3.39875@pd7tw3no:

Nice fabricant. What is it for?

Your welding the two panels back to back,(temp) and having two weldor's weld at once, on opposite sides? I guess you guys are figuring the shrink tension from the welded side will be cancelled, as the pressure would be forced equally between the two panels sandwiched together, forcing against each other, therefore canceling the tensions in each? But one of you has thoughts that as it cools, and has fought out the tension, it could reverse as it could go past the balance point during cooling, and start bowing out instead, since they can not go past "each other", the remaining forces will start moving in the direction that they can, outward? Am I getting it right?

Kruppt

Kruppt

Reply to
Kruppt

I am siding with you Roy. I am expecting there to be a space between the plates when welding is done. We shall see next week. The units, ten in all, are large fenders for taking the impact of a docking ferry. Randy

Reply to
Randy Zimmerman

I'm resuming that all those cross pannels are 'U' shaped brake items that will be welded to a flat pannel for a top (4 big feet are on the bottom. And that you have two of them top to top for welding.

In any case, I'd say it will be convex toward the camera and concave on the finished top surface. If I take a vertical center plane through the weldment, most of the weld is on the far side, it will shrink that way.

Please share in your just rewards. Don't call if you lose the bet.

Cheers.

Randy Zimmerman wrote:

Reply to
Roy J

"Randy Zimmerman" wrote in news:hG7yb.522016$pl3.308608@pd7tw3no:

Those four pizza disks are the mounting points?

It'd be nice if they were set up to drop into pockets instead (looks like) being bolted up. Or first anyway. #8^)

Reply to
Greg M

The whole assembly hangs on large chain criss crossed to be flexible. It isn't a swiss watch but one likes to make a nice looking product. I figure the neutral axis is about an inch or so above the plate in the stiffeners. The two vertical ribs are skookum to say the least. They are 5/8 plate strips welded into a channel before mounting on the plate. I set them back to back with 3/4 inch spacers at each end. My foreman figured I had set too much of a prebend and I was thinking I should have put in one inch spacers. We came out almost dead on so I didn't get my pie and I didn't have to pay. This time Roy, I am alone in the shop. I joked that I could almost taste that pie. When you think about it it would be easy for the drawing office to indicate neutral axis on the print. It would help when deciding where to locate your lifting hooks/lugs as well as give you a hint of how the shrinkage forces will act in a leverarm. We only need little 1/4 inch fillets. That will limit distortion in any case. Randy

Reply to
Randy Zimmerman

Reply to
Roy J

I think I would tone down my first guess on the amount of long way (vertical in the pix) cupping. The heavy sheet and the relatively small (key word is relatively!) stiffeners puts the neutral axis closer to the plate than when I first looked at it.

1/4" fillets will calm it down also.

Looking at it in the cold harsh morning light, I'll bet you get a fair amount of cupping from side to side also.

I love the ladder, do you get to flip it flat to weld or do you have to do overhead fillets while working on a ladder? I used to work in a similar shop (much younger days LOL!), I am reminded why I'm glad I don't anymore.

Cheers.

Randy Zimmerman wrote:

Reply to
Roy J

I also figure that most of the warping will be transverse. The formed edges of the plate are very effective restraints. Those plates were plasma cut. I have never worked with such heavy plate plazma cut. The idea of standing the pair up is so that two welders can go at it at the same time. It will be then picked up and turned 180 degrees to stand vertical again. I have long ago steered clear of shops that only have forklifts. I built the units on the floor. I was going to do it on horses but it is a pain hammer tacking the stiffeners tight to the plate. A good pair of knee pad allows me to be mobile on my knees and keep my back straight. That ladder is our deluxe model. I expect the welders will weld clips on and plank themselves up on the side. We are using metal core which is not intended as a positonal wire. Randy

"Roy J" wrote in message news:Amoyb.23$ snipped-for-privacy@news.uswest.net...

Reply to
Randy Zimmerman

I posted a pic on the drop box with the panels separated. The bloody thing didn't move at all. Absolutely no transverse bowing in either direction. The top and bottom took about an eighth of an inch for 18 inches at each end. The middle was flat. You can see the straightedge sitting on the panel. It was a truce again neither of us had to pay up. That is a nice thing to have happen. The second pair were being welded today.

formatting link

Reply to
Randy Zimmerman

Reply to
Roy J

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.