Patent ID: 6023850
Filing Date: 2000-02-15
Classification: G01B

Abstract:
A ball cube in the form of a cuboid structure, said cuboid structure having balls in its corners, said ball cube being a reference object for the determination of the parametric errors of the axes of motion of coordinate measuring machines and machine tools by measuring the coordinates of the ball centers with the machine to be checked, the errors calculated from these ball measurements being: roll, yaw, pitch, column tilt, errors of squareness, and errors of position, said ball cube being characterised in that:at least in seven of the eight corners of said cuboid structure balls being firmly mounted,the balls being fixed to said cuboid structure by fasteners through the balls in cuboid-diagonal directions, thus leaving most of the balls' surfaces undisturbed for probing,the balls being fixed at such distances away from the cuboid's corners in cuboid-diagonal direction, that each ball can be probed with at least three different probe styli whose shafts are orthogonal to each other and normal to different sides of the ball cube, and that with each such probe stylus probing points can be collected which are distributed over a hemisphere of the respective ball, without colliding with the cuboid structure or with fasteners of the balls,the center coordinates of the balls of the ball cube being known by calibration with reference to a standard of length.