Importance

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Abstract

A computer (21) processes the time between ultrasonic echoes received at a transducer (19) indicative of the outer radius and wall thickness of a workpiece (10) by subtracting (69) the weighted average (80-90) wall thickness from the weighted average outer radius to generate an internal radius for a large number of points around a spiral slice of the workpiece. The internal radii and angles are converted (69) to x and y coordinates. The centroid (X, Y) of each slice of data indicating workpiece cavity internal radii is determined (71) as twice the summation of the x coordinates and twice the summation of the y coordinates of all of the datum points of the slice. The least squares fit (73) of the X coordinates of the centroids of all of the slices and the least squares fit (74) of the Y coordinates of the centroids of all of the slices are then used to determine the average axis of the cavity of the workpiece. The X and Y coordinates of the end points of the average axis of the cavity are then converted (75) to polar coordinates to permit offsetting the end points of the workpiece commensurate amounts, whereby further machining will cause the internal cavity of the workpiece to end up more nearly centrally located, on average.

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First Claim