Method and apparatus for measuring a three dimensional cam profile

摘要

A measuring tool, apparatus and method for measuring the profile of a cam surface is described. The measuring apparatus comprises a measuring tool (120) faced toward the cam surface (11a). The measuring tool (120) includes a contact element (122) having a flat measuring surface (122b) slidably engaged with the cam surface (11a) and a holder (124) for supporting the contact element (122) pivotally about a pivot axis (F), which extends perpendicular to the cam axis (A). The measuring surface (122b) includes the pivot axis (F) and has a portion that constantly contacts the cam surface (11a). The measuring tool (120) moves along a moving axis during rotation of the cam and the position of the measuring tool (120) along the moving axis indicates the radius of the cam surface at a location where the measuring surface (122b) contacts the cam surface. Moreover, a rotary drive means is provided for rotating the cam about its axis to angularly vary the part of the cam surface that the measuring surface (122b) contacts. Moving means serve for moving the cam axially to axially vary the part of the cam surface that the measuring surface (122b) contacts and measuring means for measuring the position of the measuring tool (120) along its moving axis in association with the angular and axial positions of the part of the cam surface that the measuring surface (122b) contacts. This apparatus is particularly advantageous for measuring a cam surface (11a) which has a profile that varies continuously in the direction of the cam axis (A) and is arched outwardly in the direction of the cam axis (A).