Fixed bolt head 1

[edward995]

My client request a hexagon bolt with the length up to 1 to 2 meter. Currently I am doing this with welding a nut on it. The clamp load is acceptable but welding did take lot of time and some water flow out from the head after galvanizing.


I have found a solution from alfa lava company, any idea how to do this method. Have tried using stamping but result nut cracking

https://www.youtube.com/watch?v=ndDK9vAckSE&t=18s

 

[dik]

It's normally not a good idea to weld a nut to threaded rod. Do you have some other means of attachment? I assume this is a 'one off' type of fastener. Can you thread it an inch, put the nut on and then peen the end?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[desertfox]

Hi Edward

Well I watched the video however all I could see on the fastenings of the plates were nuts screwed on each end of a stud but certainly not a fixed head.
I wouldn’t advise welding nuts onto screwed rod because it alters the strength of both the rod and nut.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[dik]

I had a project about 10 years back using anchor rods with a heavy hex head. The fabricator threaded both ends as he should and for the anchor end, he had someone put the anchor rod in a large vice, just to support the nut and 'whacked' it with about a 5# sledge hammer... did a real job of peening the ends... those suckers would never come off...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[edward995]

@deserfox
This is the explain of this bolt.
The fixed bolt head makes assembly fast and safe since it prevents the nut from loosening during opening and closing of the heat exchanger. The bolt head is fixed through mechanical deformation of the threaded bar with the bolt head in place, preventing it from rotating.

I have tried stamping on side of the nut to make the deformation of thread but nut crack.

 

[desertfox]

Hi Edward

Well I didn’t see any mechanical fixing of the nut to the rods in the video sorry. I would be tempted to do what dik suggested, put the nut on the thread and mechanically damage the end of the thread were the nut is to prevent it coming loose.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[dik]

The guy had maybe a hundred or so of the anchor rods... I was just surprised at the size of the hammer... I would have thought a 24oz ballpeen or something of that ilk... I remember nothing about it, other than the hammer.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[rb1957]

why not just use a double nut ?

if it about holding whilst tightening ... add some flats on the shank ?

another day in paradise, or is paradise one day closer ?

 

[TugboatEng]

Desertfox, the two indentations in the end of the rod are the deformation. It's a better method because it swells the rod inside of the threads which prevents motion in any direction vs peening tbe rod which only prevents loosening.

With all of that said, the video example is for heat exchangers and A-L is trying to use a common design that can operate over a wide range of temperature. If your temperature stays below 300°F, Loctite would be a better solution.

 

[mfgenggear]

edward995

as the video depicts, they are dimpling the threaded rod with a center punch, and not the nut. this is a viable method to prevent the nut from loosing.
I suggest run a test to verify the correct size of the punch it self and the size of the indention. and record that data. specify a size and edge distance.
a off the shelf punch may work or one may have to made by the factory. do you have model shop, or machine shop. have some experience machinist help with this matter.
now after thinking about it if the rod protrudes out then that's an other issue. and is a harder to deform. but doable. the threads have to be deformed at the faying surfaces.
again run test and record. slight changes might be required.
also like Tugboat said, Loctite is a much easier and faster method, and easier to disassemble for repairs.

 

[dik]

That's why you only thread a bit of the end, so it doesn't advance...

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[rb1957]

you were worried about the effects of welding the nut, but you're ok beating the snot out of it ?

ah, loctite and duct tape ... all you really need (at Possum Lodge).
and a hammer (doubles as a "Scottish" screwdriver).

another day in paradise, or is paradise one day closer ?

 

[dik]

I often use Loctite Red... great stuff... and I'd prefer hammerin' the snot out of the end to welding, any day... The guy was fixing the nut with a single blow... it was so surprising, I've retained the picture for nearly half a century.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[mfgenggear]

my preference medium strength Loctite instead of high strength, but it's a small matter. for my personnel use it's easier to disassemble if necessary for repairs.

 

[dik]

I like the 'real' stuff... it is problematic, however, if you have to loosen it.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[TugboatEng]

The permanent Loctite has a release temperature. A nut on a rod should be simple enough to heat up before unscrewing.

 

[mfgenggear]

tugboat true but sometimes there objects obstructing that are made of plastic. were it gets touchy, but agree were it's metal no issues it can be heated with torch.

 

[MintJulep]

This seems like a good application for brazing.

 

[TugboatEng]

And Loctite should be kept away from certain plastics. Particularly polycarbonate. I learned the hard way.

 

[edward995]

The temperature may go to 150 degree. Have tried Loctite 263 but no effective. The screw do not need to unscrew.