Method and device for measuring cone geometry

摘要

Before an measuring operation a calibration is made for the distance (D1) between the measuring points of two coaxial touch sensors (3a,3b) in their initial position as well as the distance (D2) of a third touch sensor (3c) in its zero position with respect to the measuring axis (4a) of the two other sensors. . Method for measuring cone external diameters: (a) precise and reproducible placement of the piece (1) to be measured, on a table (2) installed between two coaxially opposite sensors (3a,3b). The table and sensors has a three dimensional (x,y,z) relative movement with very high precision; iterate relative movement between table and sensors in direction (y) each time accompanied by determination of the external cone secant in the plane parallel to the table surface, by bringing the sensors into touch contact with the cone. Or determine according to the type of sensor the position of the cone surface so as to find the touch points in a first position along the secondary direction (z). The maximum position measured for the secant, between the two sensors at the start of the procedure corresponds to the cone primary external diameter (d1); move a third sensor (3c) along the secondary direction (z) until it is in contact with a reference plane (5). The position of this plane allows determination of the distance (z1) between the plane and the first position along the secondary direction (z) or the primary diameter (d1) to be measured; relative movement of the cone support table (2) and measuring axis (4a) along the secondary direction (z) so as to measure cone diameter in a second position in this direction; measurement of the secondary diameter (d2) by the two sensors, this diameter corresponds to the maximum distance between the two sensors (3a,3b) when they touch the cone surface; determination of the distance (z-2) between the reference (5) and the second position along the direction (z) where the diameter (d2) has been measured, using the third sensor (3c), and; calculate the parameters which give the cone angle (A = arctan ((d1 - d2) divided by (2 x (z2 - z1))) )and the relative position of the important geometric part like the cone external surface with respect to a gauge plane (6) from known or measured parameters during fabrication (d1,d2,z1,z2,H).