Systems and methods for measurement of geometrical parameters of threaded joints

摘要

Thread parameters for a threaded object are determined. Spatial reference systems (X, Y, Z) and (X′, Y′, Z′) are respectively identified for a position sensor and the threaded object. A transformation matrix describing a quadratic form representing the threaded object in (X, Y, Z) may be determined to relate the reference systems. For example, a sensor trajectory on the threaded object may be determined, along with measurement points on the threaded object. The measurement points may be selected so the matrix, evaluated on these values, has maximum rank. Position data at measurement points in the second reference system may be transformed into the first reference system, yielding first results. After coating the threaded object, position data at the measurement points may be acquired again and transformed into the first reference system, yielding second results. Comparisons between the first and second results may provide thickness of the coating and quality verification.

主权项

1. A method of measuring thread parameters of a threaded object coated by at least one layer of coating material, comprising:
obtaining a shape of the threaded object including a nose; identifying a first spatial reference system for the threaded object comprising first co-ordinate axes X′, Y′, Z′; identifying a second spatial reference system comprising second co-ordinate axes X, Y, Z; determining at least one trajectory on the threaded object in the second spatial reference system, the trajectory including selected measurement points; obtaining first position data for the threaded object at the predefined measurement points of the at least one trajectory in the second spatial reference system; converting the first position data for the threaded object from the second spatial reference system to the first spatial reference system to yield first measurement results; coating at least a portion of the threaded object with a selected coating; obtaining second position data for the coated, threaded object at the predefined measurement points of the at least one trajectory in the second spatial reference system; converting the second position data for the coated, threaded object from the second spatial reference system to the first spatial reference system to yield second measurement results; and determining the thickness of the coating from a comparison of the first and second measurement results.