Motor Vehicle Manufacturing Technology (October 1997)

Real-Time Active Balancing for High-Speed Machining

Sponsor: BalaDyne Corporation

• Project Performance Period: 10/1/1997 - 9/30/2000
• Total project (est.): $2,936,487.00
• Requested ATP funds: $1,984,113.00

High-speed machining processes--in which spindles rotate at 40,000 revolutions per minute or more--promise dramatic improvements in machining productivity and precision, leading to improved surface finishes and simplified designs that could greatly reduce the weight and cost of automobiles and other products. But many of these promises remain unfulfilled because of practical limits on machining speed. Even minor imbalance or misalignment of tools and tool holders at high rotational speeds can result in excessive vibration, which causes bearing damage, broken tools, and poor surface finish. Balance problems are currently handled off-line in an ad hoc manner. Balance Dynamics proposes to develop real-time vibration control technology for high-speed machine tools used in automobile manufacturing and for rotating machinery in other applications, such as high-speed turbomachinery and aircraft turbine engines. The proposed technology would enable real-time on-line precision mass balancing after automatic tool exchanges and during changes in operating conditions, so as to provide upstream vibration control quickly (within 1 second) in multiple locations as needed. There are several technical challenges. One is to devise a way to estimate, analyze, and control the structural dynamics in rotating high-speed machinery. The University of Michigan will provide support in this area. A machinery fault warning and diagnosis system will be designed. In addition, a mass balance actuator device needs to be designed that can tolerate high temperatures, high centrifugal forces, and rapid angular acceleration. Methods for attaching the balancing system to rotating machinery will be developed. New bearing technology also will be needed. The proposed real-time active balancing system would enable companies to reduce downtime and safety hazards, extend bearing and machinery life, and increase the quality and precision of parts for automobiles and other products. Benefits to the U.S. economy are estimated at hundreds of millions of dollars annually, including reductions of up to 90 percent in auto part machining time and $125 million in annual savings realized through reductions in in-flight shutdown of aircraft engines.

For project information:

Wayne L. Winzenz, (313) 996-5750
wwinzenz@baladyne.com

ATP Project Manager

Richard Bartholomew, (301) 975-4786
richard.bartholomew@nist.gov