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Laser and Plasma Cutting of Bolt Holes


Introduction

Modern thermal cutting equipment with enhanced computer control can be used to cut intricate shapes. Laser and plasma torch equipment is available that provide increased cutting speed and better surface finish than older gas torch equipment. Automated computer numerical control equipment can be used to cut part contours, bolt holes, copes, slots, and beveled parts all in one continuous process. These modern processes can substantially reduce fabrication time and consequently bridge costs.  The construction specification has requirements for the surface finish of the cut edges, the tolerance on hole size, and hole taper. These existing geometric limits can be used to as a basis for acceptance of the holes made by these modern thermal cutting methods. The structural performance of the member containing connections with thermal cut holes is uncertain.

Research Needs

The fatigue and tensile strength of connections made with thermal cut holes needs to be determined. The influence of cutting parameters upon performance needs to be determined so process controls or qualification procedures to set proper limits can be set. For fracture critical and non fracture critical members, the crucial variables influencing structural performance needs to be determined. In addition, the interaction of the process variables with plate strength and chemistry needs to be evaluated. Previous research should be summarized and a research plan developed for additional study.

 Expected Benefits

The introduction of new modern computer controlled thermal cutting of holes in bridge connections. Lower fabrication costs with defined process control will provide safe and economical steel bridge structures.

 

Estimated Cost and Time

$400,000-2 years


Sponsoring Committee:AKC70, Fabrication and Inspection of Metal Structures
Source Info:Karl Frank
Date Posted:05/31/2012
Date Modified:05/05/2013
Index Terms:Metal cutting, Cutting tools, Lasers, Plasma arc cutting, Bridge design, Steel bridges, Control systems, Structural connection,
Cosponsoring Committees: 
Subjects    
Materials
Bridges and other structures

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