Need some ideas from y'all. My boss is looking for the best way to coil Stainless tubing 1/8" to 1/2" to use in heat exchanger applications. He doesn't want to spend the dough or use the space needed for a big coiling machine, just something small and manual to make 4-6" coils. Keep in mind this is heavy wall stuff 0.35 to 0.65 so a coffee can doesn't work so well. Thanks in advanced guys.
I was watching something last night where the tube was filled with water, then frozen. They bent it when frozen and it didnt kink.
I've never tried it, but I hear that you can fill it with sand first to avoid kinking. Im just thinkin it'd be a bastard to get the sand out.
if you have a lathe and some balls, weld a loop onto a pice of bar the sice of coil you want, stick the tube thru it, set the lathe on AS SLOW AS IT GOES, we had one that was like 20 RPM, and turn it on, guide the long end to keep the coil even.... we did this in a machine shop i worked in for some farmers project...
Know an ole timer who is a retired boiler man ( pipe fitter), he swears by the sand method around a pc of pipe the diameter you want.
i wouldn't bet anything that the water method would work with stainless... doesn't work for shite on carbon steel, even... sand method (dry the sand in the oven, ~250f for 20 minutes) works really well on light gauge stuff... heavy gauge stuff we'd setup the lathe on low RPMs like said above, let the new guy handle it. usually the new guy wouldn't complain much if he got hurt, for fear of non-acceptance from the other guys.
If you do it right,nobody gets hurt. If it's that dangerous,you are doing something wrong. ----- We used to wind some low volume coil springs that way, when I worked at the spring company.No problems.
0.65 is bigger than 1/2". I'm assuming that you're talking about 0.065"wall thickness? I'm gonna have to brainstorm on this one for a bit. What kind of thermal transfer are you guys doing, if I can ask?
whoops sorry, Yes 0.065 wall. As for what kind of thermal transfer, I don't know really, this is some thing a customer wants us to do for them. Most of the time it would be 0.035 wall stuff but a possibility of thicker wall tubing. To let y'all know more about what I have going on, we are a fitting distributor who for 50 years just sold fittings and tubing. This year big brother (Swagelok) let all their distributors start to integrate fittings for our customers. So I'm in the middle of stetting up the new Assemblies department. It's cool because I get a new shop, but I doubt the powers that be are going to pony up for a lathe to coil tubing, Lux had suggested a ring roller and that may work, but I just wanted to see if any one else had any suggestions. Thanks and keep em coming.
If you are going to be doing it over and over, it wouldn't be hard to set up a rotating drum with a long handled wheel to get the needed torque. Think mid-evil drawbridge rope puller thing spinning a length of desired diameter pipe. If you only need 4 loops, it would be a no brainer and 1/16 the cost of a lathe. Bet you could save on new guys too.
For tube to kink, it has to have room to spread sideways, so if you can have it saddled into a groove about the same width as the tubing, it can't really flatten out. It seems like you could make something like machining a U-shaped spiral groove in a steel mandrel, with the depth and width of the groove being the same as the OD of the tubing. Then clamp the tube at one end of the spiral and start twisting with a big hand crank and have a greased block or a rotating wheel holding the tubing into the spiral groove while you crank away. The tubing will spring back open a little when you're done, so it should be easy to roll it off one end of the mandrel afterwards. I wonder if a large diameter piece of ACME threaded rod might make a good mandrel for the small diameter tubing (if it fits down nicely into the openings in the threads).
Take a piece of heavy wall tubing or pipe the size of the I.D.you want your coil.Using heat if you need to Coil a piece of 1/2 inch square stock around the armature tube use a second piece as a sliding spacer so your coils are spaced the proper width for your tubing weld the Square stock to the armature every few inches with small beads.you can drop the armature over a second piece of pipe for an axle clamp your tube to the armature and coil it into the gaps between the square stock to form your coils.You can do this for your 1/8th tubing the same way by making an armature to fit it in a like manner.The walls formed by the square stock will stop your coil stock from flattening.You can mount round rod handles to 1 end of the armature to turn it or what ever you want but keep in mind you are turning this by hand don't use square stock or something like rebar as a turning aid,You will find out real quick that for 1 or 2 pieces this is fine but will cause a lot of discomfort if running multiple pieces.Mount your axle tube however it suits you either attach a plate and bolt it to a bench,lock it into a vice however you want.
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