Thermal UpsettingBy Dennis Hanson

Welding StudentLake Washington Institute of Technology

Introduction

Thermal Upsetting is the official term to cover:• Flame/heat bending• Flame/heat straightening

History

• First documented by Joseph Holt, Seattle blacksmith• Was more of an art than a science until

recently• Is still very much an art

Why its important

Save time and money (and time IS money…)• Accomplish jobs that are not possible in any other way• Salvage projects that would otherwise be scrapped• Keep jobs on track by using equipment on hand

Uses• For…

• Straightening• Damaged structures• Damaged equipment• Out of spec parts/weldments

• Bending • Ship building• Bridge Building• Truck trailers and railroad cars• Whatever!

• On…• steel• nickel• copper• brass• aluminum• titanium

Crane straightened by Casper, Phillips & Assoc.

in Panama

Heat Sources

• Flame• OF welding torch• OF cutting torch• OF Rosebud• Other gas torch

• Welding• Induction heater• Laser• Friction (shrinking disk)

How it works - Intro• There is a lot of bad information

about thermal upsetting on the internet.• Thermal upsetting depends on

the heated metal being restrained in some way.• It’s all about thickening or

lengthening the metal in one direction and shortening it in another direction.

How it works – Bar experiment

How it works – Bar experiment

How it works – Bar experiment

101 mm - No Change

101 mm - No Change

100.78 mm – Shrank a little bit

in length and increased 0.12 mm in width99.94 mm –

Shrank 1.06 mm and increased 0.7

mm in width

Heating patterns

• Heating patterns are critical to getting the results you want

• Developed by Holt and still in use today• There are heating patterns already

developed for standard stock like angle iron, I-beams, channel, etc.

• The key to heating patterns is that they use the weldment itself to restrain the heated metal so that it thickens and then contracts in the direction you need.

• We will look at angle iron as an example

Heating patterns – Angle Iron

• “Easy Way” vs. “Hard Way• What has to give when you bend angle iron?• So what heating pattern do you use?• Let’s use a piece of cardboard to think about this…

Heating patterns – Angle Iron

Angle iron is straight Mark a triangle Bend after heat

treating

Resources and References Used• Find this slide deck at http://www.firedupwelding.com/Blog.html• Induction Heating: http://www.efd-induction.com/en/Applications/Straightening.aspx• Holt Steel: http://www.holtsteel.com/about_us• U.S. Coast Guard whitepaper: www.dtic.mil/cgi-bin/GetTRDoc?AD=AD0710521• Dan R. Dalton, Inc.: http://danrdaltoninc.com/?page_id=6• Casper Phillips: http://www.casperphillips.com/flame_bending_and_straightening.htm• Flame On Inc.: http://www.flameoninc.com/process.html• ISI International Straightening: http://steelstraightening.com/about/• Ohio DOT: http://www.dot.state.oh.us/engineering/OTEC/2010%20Presentations/51B-Mesler.pdf• Federal Highway Administration: http://www.fhwa.dot.gov/bridge/steel/01.cfm• Flame Straightening Technology For Welders, by John P. Stewart (in the LWIT library)• The Linde Group: http://

www.holox.com/international/web/lg/us/likelgus30.nsf/docbyalias/ind_mv_auto5

Conclusion

What’s in your toolbox?