TyMoore - 6/10/2006 8:28 PMWhat about splatter of liquid metal from the work area? Do you need to design a spacesuit 'overall' and bib that protects it from molten splatter? Or do you weld in a vacuum version of a 'glove box?' What about a welding visor for space suits—do you need one externally, or will you just end up needing a specially designed space suit just for welding operations?
Well, if nobody else will comment, I guess I will. This is an excellent thread. Unlike the fun zoomy stuff, boring mundane crap like running a good bead is what will be required to exploit space resources in a real way. Sadly, most welding techniques are not well suited to space travel. (Do YOU want to fly with an acetylene tank? Think carefully....)I can think of only two welding techniques that are well suited for vacuum and microgravity/low gravity conditions. The first is electron beam welding:http://www.weldingengineer.com/1%20Electron%20Beam.htm....
I found an interesting idea that has not been thought of for welding in space - Newtons second law.A hot gas welding apparatus used in space will have a micro-nozzle, facing the exact opposite direcrtion of the arch vector, which will provide a constant counter thrust. Otherwise, the welder and the gun will simply fly away from the work area into space.
Another good point about laser welding--there are currently some interesting contendors right now for this job such as the water cooled Sony SLD432S4 and the SLD433S4 laser diode arrays. These are laser modules about the same size as a pack of cigarettes that are capable of 1KW of light output using 46vdc@53A, check it out at:http://www.sony.net/Products/SC-HP/cx_news/vol42/featuring_laser.htmlSeveral of these modules, optically linked and properly phased could easily provide the raw power to cut through steel plate--and robotic and optical systems exist today that could easily lend themselves space operations.
Quote from: space_man on 04/21/2009 03:28 pmI found an interesting idea that has not been thought of for welding in space - Newtons second law.A hot gas welding apparatus used in space will have a micro-nozzle, facing the exact opposite direcrtion of the arch vector, which will provide a constant counter thrust. Otherwise, the welder and the gun will simply fly away from the work area into space.Its been thought of, and is why oxy-acetylene welding is not viable in space.
You kinda left out ARC, Mig and Tig welding, all of which are fine in vacuum. In fact they should work better in space.
Quote from: mlorrey on 04/22/2009 12:30 amQuote from: space_man on 04/21/2009 03:28 pmI found an interesting idea that has not been thought of for welding in space - Newtons second law.A hot gas welding apparatus used in space will have a micro-nozzle, facing the exact opposite direcrtion of the arch vector, which will provide a constant counter thrust. Otherwise, the welder and the gun will simply fly away from the work area into space.Its been thought of, and is why oxy-acetylene welding is not viable in space.Uh, no. Figure out how much thrust it actually generates. Hint: If you weld on earth, you have to hold the torch up against gravity, and turning it on and lighting it doesn't significantly reduce this effort.Astronauts on EVA are affected by all kinds of forces, that's why they use tethers, hand rails, foot restraints etc. A few ounces of thrust from a torch would be nothing compared to things they already do routinely... like bashing stuff with hammers.None of this is to say that that combustion based welding would be a good choice.QuoteYou kinda left out ARC, Mig and Tig welding, all of which are fine in vacuum. In fact they should work better in space.In theory. Practice tends to be complicated. The Russians performed a number of experiments in this area, from early Soyuz through Mir. http://eagar.mit.edu/EagarPapers/Eagar136.pdf covers some of this.
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Quote from: mlorrey link=topic=4710.msg395455#msg395455that links not workingOdd, it was working last night but the page seems to be down now.
Quote from: hop on 04/26/2009 12:42 amQuote from: mlorrey link=topic=4710.msg395455#msg395455that links not workingOdd, it was working last night but the page seems to be down now. The link worked for me right now.
So much of what has been discussed on this website involves propulsion, energy production systems, life support, and radiation mitigation, however little has been said (atleast that I can find) about basic industrial processes which will be useful in the space environment. Periodically I would like to explore various industrial processes which may prove useful in space.Among these is arc welding which has so far been explored a little by the Russians onboard one of the Salyut space stations back in early seventies, I think. Apparently they tried some GTAW (gaseous tungsten arc welding) and Electron beam welding experiments: the amassed enough information to publish a book which I have been unable to locate. Several small Shuttle Getaway Specials were performed to look at arc welding in the space environment, but results have been difficult to come by. What issues could we expect to confront in welding in space or vacuum; zero g or low-g situations? Obviously because of the vacuum it would seem straight 'stick' welding might be the most favorable form of welding—however, how difficult is it to 'strike and arc' in hard vacuum? To ignite an arc, will some carrier gas like argon with a tad bit of neon be necessary to establish an arc, or can simply 'slapping' the electrode against the 'work' be enough to vaporize enough metal to establish an arc? Welder design: conventional earth bound industrial arc welders (such as a Lincoln or Miller portable welder) typically either use a 20 hp gasoline or diesel engine to drive a specially wound generator to provide the 10 KW of 20-30vac at 300-400 amps for the welding arc. Air is used to cool the windings in the generator. Obviously in space something different must be used: assuming of course we have enough 'station' power available, what would the design of the unit look like? Might it use a solid state inverter, transformer setup to convert high voltage DC to low voltage AC for welding? Or would it be better to use a dynamotor to convert DC into low voltage AC using a motor generator setup? To minimize or neutralize transient torques from startup, spin down and operational transients of a space arc welder, will it then be necessary to use two mechanically coupled but counter rotating motor/generator units, to minimize torque transients? What about cooling? Using a pressurized case with something like nitrogen blown through the electrical and mechanical parts, and then chilled by a vapor compression freon loop coupled to an external radiator could do the job, certainly, but how big of a radiator do you need? Could you do the same cooling job passively using an ammonia “heat pipe” and condensing radiator?What about splatter of liquid metal from the work area? Do you need to design a spacesuit 'overall' and bib that protects it from molten splatter? Or do you weld in a vacuum version of a 'glove box?' What about a welding visor for space suits—do you need one externally, or will you just end up needing a specially designed space suit just for welding operations?These are just some of the questions I'd like to explore:Is welding practical in space? Are there alternatives? What kinds of special safety precautions would astronaut welders need to follow on orbital or lunar welding operations? Does the lack of gravity and air make a huge difference in the theory and operation of arc welding?What kinds of systems are needed to make welding practical in zero-g and vacuum? Will welding be practical in the low CO2 pressure of Mars' atmosphere? And here's another one: will the welds hold up well to atomic oxygen bombardment from low earth orbit positions, or will special coatings like gold need to be applied?What do you think?
I found an interesting idea that has not been thought of for welding in space - Newtons second law.A hot gas welding apparatus used in space will have a micro-nozzle, facing the exact opposite direcrtion of the arch vector, which will provide a constant counter thrust. Otherwise, the welder and the gun will simply fly away from the work area into space. Agreed, if using oxy/acet, which is fast becoming obsolete. A mig torch can be held in place thus canceling reverse thrust, the problem would be the necessity of a shielding gas which could act as a thruster and could not be used in a vacuum as far as i am aware. The environment around the the joint would have to have some sort of atmosphere or the wire or electrode would have to have some sort of flux within it. which they do. I find it hard to believe that welding in a vacuum has not been experimented with. So I agree partially, physics and vacuum first must be addressed.
You kinda left out ARC, Mig and Tig welding, all of which are fine in vacuum. In fact they should work better in space. The only unique equipment you are going to need is a magnetic device to grab slag spall, otherwise you create a lot of space junk issues.
Quote from: mlorrey on 04/22/2009 12:25 amYou kinda left out ARC, Mig and Tig welding, all of which are fine in vacuum. In fact they should work better in space. The only unique equipment you are going to need is a magnetic device to grab slag spall, otherwise you create a lot of space junk issues.It's not the vacuum so much as it is the lack of gravity to control sputter. And what about non magnetic materials?