METHOD AND APPARATUS FOR MEASURING THREAD PARAMETERS Russian patent published in 2013 - IPC G01B11/24 

FIELD: physics.

SUBSTANCE: method is realised by a measurement device (1) having at least one optical sensor (5', 5") for reading the shape of the threaded object, having a nose part and which determines a first spatial coordinate system (X', Y', Z'). The measurement device (1) determines a second spatial coordinate system (X, Y, Z) and has computer means for storing an algorithm for calculating a first matrix which describes the quadratic form representing the threaded object in the second spatial coordinate system (X, Y, Z), thus providing the relationship between the first and the second spatial coordinate systems. The method involves: a) determining the path of the optical sensor (5', 5") along measurement points which are selected such that the matrix calculated on these values has maximum rank; b) performing a first scanning operation using the optical sensor (5', 5") along said path and reading data of the measurement points; c) calculating an axes transformation matrix for the first spatial coordinate system to the second spatial coordinate system in order to determine the position of the threaded object with respect to the second spatial coordinate system; d) using the axes transformation matrix to convert all data obtained from the second spatial coordinate system to the first spatial coordinate system.

EFFECT: obtaining reproducible and accurate measurements independent of coaxiality between a threaded tube and the measurement device.

19 cl, 21 dwg