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Hello, I'm new to the board, but count myself lucky that it exists.I have been practicing T-joint welds with mild steel tubing (.062) and am having trouble getting the puddle to flow into the joint recess. I am forehanding the weld. The puddle is sometimes U-shaped or crescent shaped with the opening in the direction of travel. The puddle sticks to the walls on either side of the contact point, but not the actual point of the joint (see diagram). Only after flooding the puddle will it close, then the U returns when I advance the puddle. I cleaned the metal with acetone. Any suggestions would be greatly appreciated.I thought the problem might be that I was not getting enough heat to the inner joint so I also tried backhanding the weld, which got rid of the U, but the puddle was harder to advance. Perhaps I need a larger tip and softer flame?Thanks,Louis Attached Images
Reply:Can you repost the pic?, it doesn't show upStangnetShop Full Of Stuff. Joey
Reply:Sounds like you are using a torch. My welding book says that the torch flame must be placed close to the corner on T-welds where the pieces meet and since it is difficult to get ambient air into the small space, that the flame should be set slightly oxidizing. It will be neutral in use. The flame should be held as close as possible without the inner cone touching the work and the puddle should be formed before adding filler rod.Get it hot and hit it hard...
Reply:I have to reinstall the photoeditor this weekend and will post the diagram then or provide a link. HW, thanks for the tips. The flame I was using was neutral, but just barely. I'll try running it slightly oxidizing. It sounds like the book is recommending a backhand technique if the inner cone is just at the joint. My backhand sucks. I'll post the outcome afterwards. Thanks again.
Reply:"Modern Welding" by Althouse - Turnquist - Bowditch is a great all around text but has a lot of good info on oxy-fuel technique. My copy is from 1984 so don't know if still in print but worth picking up if you can find it.Get it hot and hit it hard...
Reply:Here is a picture of the weld that shows penetration on the walls but not where the two metals join. This is a forehand weld. I tried the slightly oxidizing flame with both a backhand and forehand without success (the crescent puddle on the forehand and lousy puddle control and penetration on the backhand). I'm not sure what I am doing wrong...any suggestions would be greatly appreciated.http://www.metalbone.net/forge/tjoint3.jpg Attached Images
Reply:Indeed there is a trick to fuse the corner. The flame should be aimed at 45 degrees to the joint however the flame should heat the joint at a point about 1/16th short of the vertex. By twisting your wrist you should be able to tilt the torch straight on or forehand in varying degrees. When you add the rod from the front the molten metal should fuse the vertical and horizontal surfaces. The back side of the puddle will fill and tie in to the surfaces by natural surface tension. The puddle under the torch will be depressed into the corner. Once you get the torch in that sweet spot you can just add rod to the puddle and the liquid will form the weld bead under and behind the torch. The first few attempts likely will give you a concave bead profile until you visualize how much more welding rod is needed to fill the bead.
Reply:Lotechman, I appreciate the technique advice, thank you . I'll post the results.
Reply:I mentioned it in passing but the wrist twisting is the key. You use your wrist to point the torch more directly into the puddle or foward to heard the leading edge of the puddle.
Reply:Try turning the assembly (in a vise or supported) where thejoin is on the bottom. Now you can work in the join by pretendingit is a piece of flat stock. Watch your torch angle and filler rodangle and see what the weld looks like. If it's improved, try andremember all the angles, set the assembly up 90 degrees andhave at it. Best of luck to you.
Reply:That weld on the side looks great! Large flames in corners and tee joints are kind of tough because they tend to roll back towards you, heat the walls, and consume a lot of filler without giving you time to get 'into' the tee tight enough. Maybe just a teeny bit smaller flame and focus more on the base metal. Let the base melt as much of the filler as the flame. On something like that crescent in the last practice pic, try heating and playing around with just the base metal and the leading edge of the puddle and see if you can't pull it down in there. Nothing to loose by playing around to find the sweet spot. Once it happens for you it will rarely be a problem again. (Windy conditions will do it every time tho)"The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Hello,thanks for the advice. I gave it a try using you advice and just wasn't able to get the hang of it on that try (I'll keep trying). I oscillated the flame between the front and middle of the puddle to try to get the metal in the joint melted and the puddle to flow, but everytime I tried this, "POP" and the puddle would be gone. I rotated the torch from about a 90 degree angle forward (front end of the puddle) but still the crescent shaped puddle remained a crescent. I was trying to use the flame to force the puddle to the inner joint without success, just the classic OA Pop.I didn't think that the tip was close enough to the puddle to clog it and cause the popping, but perhaps it was the puddle closing on top of an air pocket in the inner joint that caused the pops.Also, I had the piece angled between two pieces of fire brick to get as close to a flat position as possible.Back to the drawing board for now, gotta find that sweet spot...
Reply:The "POP" comes from getting too close as you have found out. It appears you are righthanded - have you tried started on the left and welding backhand? It should be easier to start the puddle and may help with the popping.Get it hot and hit it hard...
Reply:I've run across the same problems. To eliminate the POP, I used a smaller tip size and increased the flame size; really crank it up. Also, I find a shallow angle heats a corner better.All the other suggestions sound good too.-A |
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发表于 2021-9-1 01:02:25