How is tube end rolling done?

When I used to work in a heat exchanger repair shop, they had special tools to do this. These tools had rollers that would expand inside of the tube and you put inward pressure. We used to run these tools with air powered drills. The harder you pushed, the more pressure it put on the roolers. Never did any as big as you need, most everything was 1.25 and below. Some exchangers had several thousand tube to be rolled. Some times, they were also TIG welded after rolling. If you hunted up a boiler repair shop or an heat exchanger service they might let you look at their tools. BTW, the rollers were hardened like roller bearings with a hardened long taper cone inside to provide the outwart thrust. The tool needed to be dipped in a thick lube often or it would overheat in a hurry

"Jeff Taylor" > I'd like to roll the ends of some aluminum tube over toward the inside.

Jeff; I do this all of the time on my large spinning lathe. It can easily be done on a metal lathe with a chuck and spindle hole large enough for your tubing. The best way to grip the tubing is with a collet. For a large diameter tubing I'd machine my own collet type holder to place in the 3 jaw metal lathe chuck. You can make this out of heavy walled steel tubing with a slit in one side.

It can be done using nothing more than a good sized planishing spinning tool. For quantities, I would most likely use a scissor action roller tool with the correct radius roller. This is less tiring. To just turn in the end you do not need a mandrel inside the tubing - just lube it and fold it over. The end does need to be cut perfectly square or trimmed before the spinning begins. Take your time with the process and go at the speed the metal dictates or you will crimp it. I usually do it at 1200 to 1700 rpm on the lathe. If you make your own simple roller tool (as is used in Japan), be certain to keep the roller bearings lubed. Jim