Apparatus for dimensional testing of nominally cylindrical workpieces

Claim 1

Apparatus for testing errors of concentricity and form of a nominally cylindrical workpiece, independently of the workpiece diameter, and for checking, at the same time, that the diameter of the workpiece is within predetermined limits of tolerance, said apparatus comprising: a. workpiece support means permitting rotation of the workpiece about a longitudinal axis; b. a base fixed with respect to said workpiece support means; c. a forked support; d. a first pair of ligaments mounting said forked support on said base and constituting with the base and the support a first articulated parallelogram permitting lateral displacement of said forked support relative to said base; e. two adjustable feelers adapted to come into contact with the outer surface of the workpiece at diametrically opposed points, one of said feelers being carried by one of the arms of the forked support; f. a block carrying the other of said feelers; g. a second pair of ligaments supporting said block from the other arm of said forked support and constituting with the block and the support a second articulated parallelogram permitting lateral displacement of the block relative to the support; h. a first transducer, sensitive to the workpiece diameter, carried by the forked support and providing a signal related to the position of said block with respect to said forked support; i. mounting means fixed relative to said base; j. a second transducer, sensitive to workpiece eccentricity, carried by said mounting means and providing a signal related to the position with respect to said mounting means of a reference point which is the center point of one of said second pair of ligaments, and k. means for connecting said transducers to a signal processing instrument for evaluating the signals provided by said transducers and providing an indication of whether or not said signals are within acceptable limits.