Position sensing apparatus

摘要

A probe for sensing the position of a workpiece comprises a housing adapted to be secured to a coordinate measuring machine. A stylus projecting from the housing is engageable with the workpiece for sensing the position thereof. The stylus is secured to a moveable member supported within the housing by three bellows having mutually perpendicular axes and each secured to the moveable member and the housing in position therebetween. Since a bellows is inherently stiff in torsion about its axis but is flexible axially and transversely, the bellows cooperate to constrain the stylus for parallel motion. More particularly, any one first bellows can expand or contract to accommodate movement of the stylus in the direction of the axis of that the first bellows, a second one of the bellows prevents tilting of the stylus by virtue of its torsional stiffness. At the same time both the second and third bellows flex transversely to accommodate the expansion or contraction of the first bellows. The stylus is biased into a rest position determined by the condition of the bellows when the stylus is free. Displacement of the stylus (152) is determinable by inductive proximity sensors.