Pinch weld seam

[Screwdriver]

I am playing with some motorcycle fuel tanks and want to know a little bit about the pinch weld process that forms the seal.

How is it made (any links)? What are the common mistakes people make when welding near them? is it a bit like a forge weld or is there some adhesive/bond inside the seam that can be damaged by excessive heat etc?

 

[500e]

Are you talking about plug \ spot welding?

 

[Dcal]

It' a continuous form of spot welding where the weld is made between two rollers that rotate, clamping the material tightly together and resistance welding at the same time.

Not a very DIY friendly process.

The closest weld for home use is probably melting the two edges together with tig or oxy acetylene.

https://www.kuka.com/en-gb/products/process-technologies/2016/07/roller-seam-welding

 

[Screwdriver]

It' a continuous form of spot welding where the weld is made between two rollers that rotate, clamping the material tightly together and resistance welding at the same time.

Not a very DIY friendly process.

The closest weld for home use is probably melting the two edges together with tig or oxy acetylene.

https://www.kuka.com/en-gb/products/process-technologies/2016/07/roller-seam-welding

Cool thanks, just wanted to know if it was a regular type of weld, metal to metal fusion with no "filler".

 

[Robotstar5]

Called seam welding, they used it to stick the main parts of Mini's together. The welding controller kept pulsing through a set of wheels as the flange was pulled through them.

 

[Windy Miller]

Called seam welding, they used it to stick the main parts of Mini's together. The welding controller kept pulsing through a set of wheels as the flange was pulled through them.

Well. That’s very interesting! Never knew that

 

[Paul.]

I worked at a place in the 80s that made fuel tanks amongst other things, we had a seam welder, when it was running it used to dim the lights in the workshop, I asked what size fuses it used and was told 1/4" UNF.

 

[Robotstar5]

Well. That’s very interesting! Never knew that

The main welds were the 4 vertical ones at each corner of the passenger compartment, then they cover the joint with a "U" shape trim.

Another useless fact: there is a hole in the dash (where the wiring etc. comes through) and a corresponding hole behind the rear seat, this was used originally for a "spit" to go through so the bodyshell could be rolled through the primer paint tank.

 

[eLuSiVeMiTe]

The main welds were the 4 vertical ones at each corner of the passenger compartment, then they cover the joint with a "U" shape trim.

And people think it's a good idea to deseam minis for looks.

 

[Robotstar5]

And people think it's a good idea to deseam minis for looks.

The seams were to make assembly easier, you can de-seam by removing 4" sections so you end up with a castellated profile and weld the gaps, then remove the rest of the 4" sections and weld the rest, bodyshell will be just as strong.

 

[Windy Miller]

The main welds were the 4 vertical ones at each corner of the passenger compartment, then they cover the joint with a "U" shape trim.

Another useless fact: there is a hole in the dash (where the wiring etc. comes through) and a corresponding hole behind the rear seat, this was used originally for a "spit" to go through so the bodyshell could be rolled through the primer paint tank.

Ah ha! I have often wondered what that hole was for!

 

[Robotstar5]

Ah ha! I have often wondered what that hole was for!

Found it, the Rotodip process.

 

[bert]

They also have 4 slinging shoes that most people think are jacking points. They were there only to hold the shell to the production line. Once off the line they were redundant.

 

[500e]

Thanks for that @Robotstar5 A really interesting link
Another read for those interested in old cars

https://www.bridgwatermuseum.org.uk/index_htm_files/bridgwatermotorcar.pdf

 

[awemawson]

Rather like the Triumph sports cars, the panel seams were external, welded then covered in a chrome strip to enhance the early rusting properties!

I always thought they looked like Cornish Pasties