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[Martin (Admin)]

One for the heavy engineering Mayhemrs!

Don't ask me why but I've noticed some fancy shapes 'welded' on Lorry mounted Hiab type cranes recently,  I'm taking it that they are strengthening 'doublers'.

My question is, how are the doublers attached, welds, bonded to the main frame of the  crane?  There appears to be no welding around the edges?!? And if they are 'edge welded, how does that produce enough strength in the middle of the plate?

[imsinking]

Some form of RESISTANCE welding ?
OR using the mother of all spot welders . . . . .
Bill

[Crossie]

 Modern high power production migwelding machines can produce a very smooth fillet weld around the edge of the plate, which  does add torsional stiffness to the part of the beam which it covers, and increases the bearing surface area of the various pins and adds tensile and compressive strength to the beam face between them. On older machinery the various pins usually had individual bosses welded onto the beam face which when the machine was 'well worn' could easily(!!) be ground off and a new one made up and welded on- - I've done quite a few on old jcbs and farm tractors over the years.

                                            Trevor

[JayDee]

Hello,

YEARS ago, I worked on a "Spot Welder" that could weld together one inch thick steel plates!!.
We used it to weld two pieces of steel into a "V " shape, which was then placed under a press to break the weld - - to inspect it for faults.
Very adjustable, it could also weld 1/16th alloy sheet.
I think it was sent to the Ford Motor Company at Liverpool.
No idea what they used it on !!!!!.

John 

[Plastic - RIP]

Looks to me like the whole arm plate is CNC milled from solid. No welds. All a product of stress analysis programs.

[NFMike]

It's edge welded I think. If you enlarge the picture and look at the crescent shape piece below the Euro star circle, along the bottom edge you can clearly see the fillet. There's also a bodgy looking fill where it joins the larger part.

[imsinking]

It's edge welded I think. If you enlarge the picture and look at the crescent shape piece below the Euro star circle, along the bottom edge you can clearly see the fillet. There's also a bodgy looking fill where it joins the larger part.

You beat me to it , enlarged it in P/Shop & you can see the corner spill where the robot has run wide , and the dodgy joint   
Bill

[derekwarner]

I am sure Plague is correct  [CNC lap weld profile]..... with the doubler plate ..... Derek

[NFMike]

You beat me to it , enlarged it in P/Shop ...

That's a bit heavy - I just pinch zoomed on my tablet. I guess using the zoom in a PC browser would do it.   

[NFMike]

And if they are 'edge welded, how does that produce enough strength in the middle of the plate

It's a beam basically, so they don't need 100% attachment.
A not very accurate, but fairly simple example: Imagine an I beam across a gap with a load in the middle, but it's not strong enough. You add a second beam alongside it and weld it to the first one in a couple of places. Double the strength but without the parts being joined along the whole length.

[Vts99]

Other option would be to cut openings on main plate like small ovals in specific locations then weld onto the doubler plate . From outside looks like it's just sitting there but will add extra strength

[warspite]

Puddle welds - where holes in one plate allow the weld to attach the item in the centre of the plate as well as the edge, stops the centre bowing out when weld heats the plate up.

[Martin (Admin)]

Original photo.
Click to see full size, then click again!

[Vts99]

Definitely looks like what the member above and I said about welding aka puddle welds . These  could also be filled and smoothed before painting also so would be invisible once complete

[Mark T]

These are Machine edge welds that are so smooth they look seamless and thats because they are.  Look at JCB, Caterpillar or the like and they all look similar.  Machine welding removes human errors which also removes fail points as a general rule.  It works amazingly well and looks great too.

[ballastanksian]

You are all wrong, the middle of the plates have sticky back plastic holding them together before a man welds the edges. (He was distracted by the tea lady when welding the last bit. (Honest:O)