Patent ID: 7047658

Claim:
An apparatus for dimensional and form deviation checking of a crankpin of a crankshaft during orbital rotations about a main rotation axis on a numerical control grinding machine, the grinding machine having a grinding-wheel slide carrying a grinding wheel and a worktable defining said main rotation axis, said apparatus comprising: a gauging head with a Vee-shaped reference device adapted to engage the crankpin to be checked, a single movable feeler adapted to touch a surface of the crankpin to be checked, and a transducer adapted to provide signals indicative of the position of the single movable feeler with respect to the Vee-shaped reference device; a support device, with mutually movable coupling elements, that movably supports the gauging head; an angular detection unit for detecting an angular position of the crankshaft; a control device to control automatic displacements of the gauging head from a rest position to a checking position, and vice-versa; and processing and display devices, connected to the gauging head, adapted to receive and process said signals provided by the transducer to obtain values indicative of the profile of the crankpin to be checked, wherein said processing and display devices are further connected to the angular detection unit and are adapted to obtain and store values corresponding to the signals provided by the transducer at predetermined spaced out angular positions during the rotation of the crankshaft, and to compensate the values of the signals provided by the transducer for alterations caused both by the movements of the coupling elements and the gauging head as the gauging head follows the crankpin in its orbital rotations in the checking condition, and by the contact between the Vee-shaped reference device and the surface of the crankpin to be checked, the processing and display devices being adapted to compensate for alterations caused by said movements of the coupling elements and the gauging head at least on the basis of geometric features of the support device.