Welding on rectangular tube used for machine chassis
Welding on rectangular tube used for machine chassis
(OP)
I'm looking for some referance information for welding on Rectangular tubes that are used to make a machine chassis. I've found some information on "C" channel used for the same purpose but nothing on rectangualr tubes. One specific question I have revolves around the effects of welding pads along the radius of the tubes rather then on the face. In "C" channel I know you should avoid it but I wonder if the same applies for tubbing.






RE: Welding on rectangular tube used for machine chassis
RE: Welding on rectangular tube used for machine chassis
RE: Welding on rectangular tube used for machine chassis
RE: Welding on rectangular tube used for machine chassis
RE: Welding on rectangular tube used for machine chassis
RE: Welding on rectangular tube used for machine chassis
Your understanding of the whole machine chassis (machine base frame) design problem is somewhat suspect. And, the way you asked your original question and then respond to Ron and Cpro doesn't add to the confidence level. You claim to have an original design which was tested and certified and apparently worked for its intended purpose. That is your defense, "the proof is in the pudding" so to speak. To call it a real design, you should have: analysis and design calculations, including weld sizing, secondary stress effects, etc., fab. drawings and the like. The only difference in the whole design process when using two different shapes for the members is that each shape may have a few of its own characteristics which must be accounted for in the design. Then you claim it was tested and certified for its specific load and purpose. What better position could you have to defend. Cobbled together and a real engineered design are two different things, and cobbled together is tough to defend as good engineering. Then, if someone else chopped up your design and turned it into something it was never designed to be, and it doesn't work, you certainly don't have to defend that. Let the guy with the ax defend his own work. Your's supposedly worked.
As to your question about 'welding pads along the radius of the tubes,' are 'pads' the reinforcing plates that transfer the machine load to the frame and the frame load to the foundation? These pads must be thick enough so they are not a bending problem, either in themselves or as they transmit load to the shell of the tubing. They should be wide enough with respect to the width of the tube face they are attached to so as not to induce excessive bending in the tube face, and so as to transmit their loads directly into the tube webs. They should probably not be as wide as the tube, because the longitudinal weld btwn. the plate and the corner radius of the tube is very difficult to make. The root pass on the longitudinal weld is almost always of inferior quality, particularly when considering vibration and fatigue. Make the pads just slightly larger than the flat width of the tube so that you are assured the welding process you are using will provide proper penetration at the root of the weld. Then provide a fillet and a weld reinforcement out onto the radius to transmit the load into the webs. Do not weld around the corner at the end of the longitudinal weld, stop the weld short and back-weld to fill the termination. Welding around the corner will likely cause undercutting on the pad.
RE: Welding on rectangular tube used for machine chassis
In addition, you are confusing parameters. As dhengr noted, you have both structural and thermal affects. The thermal affects are negligible. The structural effects can be, as long as you accommodate the machine vibration and cyclic affects.
RE: Welding on rectangular tube used for machine chassis
RE: Welding on rectangular tube used for machine chassis
It is not permitted to weld the crossing corners when one tube is in crossing contact with another, in that case, only the flats of one can be can be welded to the flats of the other.
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Welding on rectangular tube used for machine chassis
RE: Welding on rectangular tube used for machine chassis
RE: Welding on rectangular tube used for machine chassis
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Welding on rectangular tube used for machine chassis
RE: Welding on rectangular tube used for machine chassis
"Design of Weldments" by Omer W. Blodgett
This is a very inexpensive ($15.00) reference book that covers the gambit of welded fabrication, especially for machines.
https
RE: Welding on rectangular tube used for machine chassis
Thank you