automating weld of fitting to a small shell
automating weld of fitting to a small shell
(OP)
We want to automate the process of welding internally threaded fittings of 3/4" to 1.5" OD to shells of 9" to 12" dia and of 1/8" thickness using MIG. The material of both the fittings and shell is mild steel. Any help/info/tips in this regard will be helpful. Is this even worth pursuing? Thanks in advance.





RE: automating weld of fitting to a small shell
You could probably discuss Mig applications with Ed Craig from www.weldreality.com
You may wish to consider application of friction welding instead of Mig for very high production rates.
Regards,
http://www.welding-advisers.com/
RE: automating weld of fitting to a small shell
Automating a MIG process means you need some means of cleaning the nozzle and cutting off the stick out along with motion of the gun. A robot would be what I would recommend along with the part feeding/removal mechanisms. The fittings will need to be radiused and orientated properly to assure good fitup.
I would actually recommend not MIG but a stud welding process and drilling the through hole after welding. It is much eastier to automate and faster.
RE: automating weld of fitting to a small shell
robotics may be the best aplication.
genb
RE: automating weld of fitting to a small shell
I am in the process of automating similar work.
GenB
RE: automating weld of fitting to a small shell
There may be enough experience out there regarding this problem, which by its nature seems commonplace enough.
BillPSU, very perceptive indeed, this is a pneumatic application at 150 psi. Sounds like you have been down this street, have you guys done this automation?
RE: automating weld of fitting to a small shell
Have you looked at an auto-GTAW welding process? There are many small TIG torches that can be fixtured to an arm for automation and accurate tracking. I don't see where you need high deposition welding processes to justify using MIG.
RE: automating weld of fitting to a small shell
- emboss flats in the shells to put the weld in a single plane.
- pierce the shells at the same time.
- machine a step in the proximal face of the fitting, so it would be partially self- fixturing.
- add a relief groove in the o.d. of the fitting, so the weld would be between a flange and a shell of similar thickness.
Mike Halloran
Pembroke Pines, FL, USA
RE: automating weld of fitting to a small shell
you program it to do the exact weld,
if you want to spend the money on a robot,
or if you want to outsource as well,
let us know and i will post a web site to follow.
genblr
RE: automating weld of fitting to a small shell
RE: automating weld of fitting to a small shell
I used to work for a custom machine builder that specialized in automated welding for just this sort of thing. We did everything from integrating purchased articulated arm robots to custom built specialized robots.
I've seen what you describe accomplished for the fittings on hydraulic cylinders with both fixed automation and an articulated arm robot. The right solution certainly depends on the desired throughput.
The fixed automation application revolved the torch around a verical axis, while riding up and down on a cam to maintain the correct height. The operator tacked the part on the cylinder and monitored the weld.
At the other end of the spectrum, you could feed fitting parts automatically with a vibratory bowl feeder and automatically place and weld them.
RE: automating weld of fitting to a small shell
You can monitor current and displacement during the process and maintaining the equipment is cheaper and more trouble-free than MIG. If you're interested, try looking at companies like Impuls (Germany) or Banner (US).
RE: automating weld of fitting to a small shell
You will have to watch the burn back to make sure there is no crater at the start or stop. You will see weld distortion inside the barrel of the cylinder and the area around the weld will shrink. We were using .25" wall tubing 4" OD. We saw so much shrink we honed/skived-burnished after welding. We couldn't install the piston past the port if pre-honed material was used.
RE: automating weld of fitting to a small shell
To respond to some of the suggestions:
- We are looking at MIG because this seems to be the preferred route for welding automation of this kind, and I am told the higher deposition rate can give a bigger weld size thus countering the lack of precision somewhat inherent in this type of welding and its tracking.
- Our own experience with Capacitive Discharge welding for weld studs has a mixed opinion. In a volume process, operators can tend to overlook critical settings, and factors like plant electrical load variations are beyond control which also affect the issue. The application is critical from the standpoint of high pressure pneumatics.
- There is a school of thought in-house which wants to do fixed automation as a first step. If any one can recommend a few good companies in this regard, then I will truly appreciate it. Thanks again for a wonderful discussion.
RE: automating weld of fitting to a small shell
Investigate vacuum furnace brazing.