Patent ID: 7401412

Claim:
A Cartesian gantry system for mounting on a rigid base comprising: a) spaced and parallel linear Y-translation stages comprising linear bearings with associated linear motors, the linear bearings defining the Y-direction and constraining the motion of Y-carriages riding on the linear bearings, b) a bridge for supporting a linear X-translation stage comprising a linear bearing with an associated linear motor, the linear bearing defining the X-direction, being perpendicular to the linear bearings associated with Y-translation stages and constraining the motion of an X-carriage riding on the linear bearing, said bridge secured at each end to a Y-translation carriage by a bridge extension plate extending over a Y-carriage, c) an expansion joint between the bridge and a Y-carriage at only one end of the bridge comprising: i) a bridge extension plate integral with the bridge having a lower surface parallel to the X- and Y-directions and extending over the Y-carriage and support flanges connected to and extending perpendicular to the bridge extension plates at each end of the bridge having parallel edge surfaces parallel to the X-direction, ii) a flexure plate having upper and lower surfaces parallel to the X- and Y-directions, at least portions of the upper and lower surfaces of said flexure plate abutting the bridge extension plate and the Y-carriage, said flexure plate having sections aligned in the X-direction, a central section, two outer sections spaced from the central section in the Y-direction, and two flexure sections joining the central and outer sections, respectively, enabling small relative X-direction movement of the central and outer sections by elastic deformation of the flexure sections, iii) fasteners securing the central section of the flexure plate to one of the bridge plate or the Y-carriage and fasteners securing the outer sections of the flexure plate to the other of the bridge plate or the Y-carriage, and iv) bolster flanges connected to and extending from the Y-carriages at each end of the bridge having edge surfaces parallel to the X-direction and parallel and adjacent to the edge surfaces of the support flanges associated with the bridge.