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Automatic ball bar for a coordinate measuring machine

United States Patent

5,647,136
July 15, 1997
View the Complete Patent at the US Patent & Trademark Office
Fermi National Accelerator Laboratory - Visit the Office of Research and Technology Applications Website
An automatic ball bar for a coordinate measuring machine determines the accuracy of a coordinate measuring machine having at least one servo drive. The apparatus comprises a first and second gauge ball connected by a telescoping rigid member. The rigid member includes a switch such that inward radial movement of the second gauge ball relative to the first gauge ball causes activation of the switch. The first gauge ball is secured in a first magnetic socket assembly in order to maintain the first gauge ball at a fixed location with respect to the coordinate measuring machine. A second magnetic socket assembly secures the second gauge ball to the arm or probe holder of the coordinate measuring machine. The second gauge ball is then directed by the coordinate measuring machine to move radially inward from a point just beyond the length of the ball bar until the switch is activated. Upon switch activation, the position of the coordinate measuring machine is determined and compared to known ball bar length such that the accuracy of the coordinate measuring machine can be determined.
Jostlein; Hans (Naperville, IL)
Universities Research Association, Inc. (Washington, DC)
08/ 500,336
July 10, 1995
This invention was made with Government support under Government Contract No. DE-AC02-76CH03000 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.