RRS Page 1

After observing the difficulties surrounding the removal of more than 32,000 rivets during the McArdle Bridge rehabilitation in Boston MA, it was evident that a faster and more economical method of removing rivets from aging steel structures was needed. HyDrill, Inc. was originally formed to conceptualize, develop, and commercialize such a system. Using sample steel from the work site, initial test confirmed that an abrasive waterjet cutting method could easily accomplish the task. Cutting is performed without vibration, impact, or transfer of heat to the structure. As illustrated below, only the area of kerf, about 0.030” directly under the cutting tool, is affected during the removal process.

To validate the commercial feasibility of using waterjet for rivet removal, a specialty-cutting fixture was designed and built to determine the optimal speed, angle of attack, and other pertinent variables required to perform reliable cutting. An open air-testing environment allowed tool operation to be conducted under all ambient conditions. Stacked and laminated steels with ply thicknesses from ¼” to ½” revealed no differences when compared to data obtained from the cutting of solid stock. More convenient cut-to-length carbon steel round stock was used to develop the cutting parameters. Thousands of cutting cycles were required to produce speed & feed data models that would eventually culminate into a quickset operator interface capable of automating the cutting process.