we are manufacturing wagon out of mild steel. The main girder beams are fabricated I section 660mm deep with web 10 mm thk. & flanges 320 mm wide. We have to camber the section by 20mm. Please suggest what methods can be adopted to achive camber other than heating.
With best regards,
jayaprakash
Most beams that need camber are cambered by flame or on rolling equipment. Also, if you are fabricating the beam, what about making the weld on one flange bigger than the weld on the other flange. The additional shrinkage forces generated by the larger weld should give you camber. It would take some practice to get it right though, or it may be possible to calculate it if you have some of the Lincoln electric design books, they give methods to calculate distortion from welding.
Hi, Mr. Roberts
Thanks for your suggestion on alternative method for cambering. I would like to know if it is advisable to flame heat wagon underframe structure made out of micro alloy steel with 540 N/mm2 min. UTS to correct welding distortion.
regards,
jayaprakash
I don't think you would have a problem unless you are using quenched and tempered materail, or possibly TMCP material.
Research has been done by Richard Advent for the Federal Highways in the US. They have published research on the effects of heat straightening and guidelines on how to straighten damaged girders. So I am sure that the same techniques can be used in reverse to camber girders.
Regards,
Sean
If you prestress the lower flange in tension during fabrication of the beam, then release it after, the result should be upward camber. Careful engineering should predict the amount fairly accurately.
Bill
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