Method of and apparatus for measuring the geometric characteristics of nominally cylindrical guiding structures

Claim 1

A method of measuring geometrical characteristics of a guiding structure comprising a body with a nominally cylindrical external surface and a central element nominally coaxial with the body, said method comprising the steps of: placing the structure in to a V-section groove; rotating the structure through by 360° in the groove and generating a curve described by a point of a central element of said structure on a plane perpendicular to a longitudinal direction of the groove; detecting the curve described by said point of said central element of the structure on said plane perpendicular to the longitudinal direction of the groove; storing coordinates of the points of the curve with respect to a system of coordinate axes; and numerically analysing the curve to obtain from such coordinates the desired geometrical characteristics.

Claim 2

A method of measuring geometrical characteristics of a guiding structure comprising a body with a nominally cylindrical external surface and a central element nominally coaxial with the body, said method comprising the steps of: placing the structure in to a V-section groove; rotating the structure through by 360° in the groove and generating a curve described by a point of a central element of said structure on a plane perpendicular to a longitudinal direction of the groove; detecting the curve described by said point of said central element of the structure on said plane perpendicular to the longitudinal direction of the groove; storing coordinates of the points of the curve with respect to a system of coordinate axes; and numerically analysing the curve to obtain from such coordinates the desired geometrical characteristics.

Claim 8

A method of measuring geometrical characteristics of a guiding structure comprising a body with a nominally cylindrical external surface and a central element nominally coaxial with the body, said method comprising the steps of: placing the structure in to a v-section groove; rotating the structure through by 360° in the groove and generating a curve described by a point of a central element of said structure on a plane perpendicular to a longitudinal direction of the groove; detecting the curve described by said point of said central element of the structure on said plane perpendicular to the longitudinal direction of the groove; storing coordinates of the points of the curve with respect to a system of coordinate axes; and numerically analysing the curve to obtain from such coordinates the desired geometrical characteristics, wherein the geometrical characteristics are eccentricity of the central element with respect to the external surface and non-circularity of said external surface, and wherein, to obtain the eccentricity, the numerical analysis of the curve comprises the steps of: calculating, for each point of the curve, the sum of the coordinates of the point itself; determining the maximum and the minimum of such a sum; and calculating the difference between the maximum and the minimum, the eccentricity being proportional to such a difference.

Claim 9

A method of measuring geometrical characteristics of a guiding structure comprising a body with a nominally cylindrical external surface and a central element nominally coaxial with the body, said method comprising the steps of: placing the structure in to a v-section groove; rotating the structure through by 360° in the groove and generating a curve described by a point of a central element of said structure on a plane perpendicular to a longitudinal direction of the groove; detecting the curve described by said point of said central element of the structure on said plane perpendicular to the longitudinal direction of the groove; storing coordinates of the points of the curve with respect to a system of coordinate axes; and numerically analysing the curve to obtain from such coordinates the desired geometrical characteristics, wherein the geometrical characteristics are eccentricity of the central element with respect to the external surface and non-circularity of said external surface, and wherein, to obtain the eccentricity, the numerical analysis of the curve comprises the steps of: calculating, for each point of the curve, the sum of the coordinates of the point itself; determining the maximum and the minimum of such a sum; and calculating the difference between the maximum and the minimum, the eccentricity being proportional to such a difference.

Claim 10

A method of measuring geometrical characteristics of a guiding structure comprising a body with a nominally cylindrical external surface and a central element nominally coaxial with the body, said method comprising the steps of: placing the structure in to a V-section groove; rotating the structure through by 360° in the groove and generating a curve described by a point of a central element of said structure on a plane perpendicular to a longitudinal direction of the groove; detecting the curve described by said point of said central element of the structure on said plane perpendicular to the longitudinal direction of the groove; storing coordinates of the points of the curve with respect to a system of coordinate axes; and numerically analysing the curve to obtain from such coordinates the desired geometrical characteristics, wherein the geometrical characteristics are eccentricity of the central element with respect to the external surface and non-circularity of said external surface, and wherein, to obtain the non-circularity, the numerical analysis of the curve comprises the steps of: determining the barycenter of the curve; calculating the mean value of the square of the distances of the curve points from the barycenter, the non-circularity being obtained from such a mean value, from the eccentricity and from the semimajor axis in accordance with the relation: ##EQU8## where δ is the non-circularity, defined as the ratio of the difference between a maximum and a minimum diameter of the structure to the nominal or the maximum diameter, <ρ 2 > is said mean value, d is the eccentricity and R is half the nominal or the maximum diameter.

Claim 11

A method of measuring geometrical characteristics of a guiding structure comprising a body with a nominally cylindrical external surface and a central element nominally coaxial with the body, said method comprising the steps of: placing the structure in to a V-section groove; rotating the structure through by 360° in the groove and generating a curve described by a point of a central element of said structure on a plane perpendicular to a longitudinal direction of the groove; detecting the curve described by said point of said central element of the structure on said plane perpendicular to the longitudinal direction of the groove; storing coordinates of the points of the curve with respect to a system of coordinate axes; and numerically analysing the curve to obtain from such coordinates the desired geometrical characteristics, wherein the geometrical characteristics are eccentricity of the central element with respect to the external surface and non-circularity of said external surface, and wherein, to obtain the non-circularity, the numerical analysis of the curve comprises the steps of: determining the barycenter of the curve; calculating the mean value of the square of the distances of the curve points from the barycenter, the non-circularity being obtained from such a mean value, from the eccentricity and from the semimajor axis in accordance with the relation: ##EQU8## where δ is the non-circularity, defined as the ratio of the difference between a maximum and a minimum diameter of the structure to the nominal or the maximum diameter, <ρ 2 > is said mean value, d is the eccentricity and R is half the nominal or the maximum diameter.

Claim 12

An apparatus for measuring the geometrical characteristics of a nominally-cylindrical guiding structures, to be characterized and comprising a body with a nominally cylindrical external surface and a central element nominally coaxial with the external surface comprising: a support with a V-section groove to hold a structure to be characterized; a source to illuminate said central element of the structure; means for rotating the structure in the groove; means for collecting a light beam outgoing from said central element and generating a curve, and for detecting the curve described by said element on a plane perpendicular to a direction of elongation of the groove because of the rotation by 360° of the structure; and a measuring and computing system, connected to the means for detecting to memorize the coordinates of the points of the curve with respect to a system of coordinate axes and to obtain from such coordinates the desired characteristics.

Claim 13

An apparatus for measuring the geometrical characteristics of a nominally-cylindrical guiding structures, to be characterized and comprising a body with a nominally cylindrical external surface and a central element nominally coaxial with the external surface comprising: a support with a V-section groove to hold a structure to be characterized; a source to illuminate said central element of the structure; means for rotating the structure in the groove; means for collecting a light beam outgoing from said central element and generating a curve, and for detecting the curve described by said element on a plane perpendicular to a direction of elongation of the groove because of the rotation by 360° of the structure; and a measuring and computing system, connected to the means for detecting to memorize the coordinates of the points of the curve with respect to a system of coordinate axes and to obtain from such coordinates the desired characteristics.