Apparatus for the in-process dimensional checking of orbitally rotating crankpins

Apparatus for checking a crankpin, orbitally rotating about a geometrical axis, in the course of the machining in a numerical control grinding machine including a worktable, defining said geometrical axis, and a grinding-wheel slide carrying a grinding-wheel, with

• a Vee-shaped reference device for cooperating with the crankpin to be checked,
• a measuring device movable with the Vee-shaped reference device,
• a support device for supporting the Vee-shaped reference device and the measuring device, the support device having
• a support element fixed to the grinding-wheel slide,
• a first coupling element coupled to the support element so as to rotate about an axis of rotation parallel to said geometrical axis,
• a second coupling element carrying the Vee-shaped reference device and coupled to the first coupling element so as to rotate with respect to it about a second axis of rotation parallel to said geometrical axis,
• a control device for controlling automatic displacements of the apparatus from a rest position to a checking condition, and vice versa, and
• a guiding mechanism, associated with the Vee-shaped reference device for guiding the arrangement of the latter on the crankpin towards said checking condition of the apparatus, and including a limiting device with an elongate rigid element arranged along a direction substantially parallel to the first coupling element and adapted to cooperate with elements connected to the grinding-wheel slide and the second coupling element, the limiting device including at least one pair of mechanical abutting surfaces adapted to engage with each other and limit movements of the Vee-shaped reference device during said automatic displacements towards the checking condition, wherein said elongate rigid element is rotatably mounted with respect to both the support element and the second coupling element.