Hexagon Metrology Ab

David W Payette

Wilhelmus Weekers

Jens Hupkau

John Langlais

A machine, such as a coordinate measuring machine, having a component or element movable with respect to a support structure along rails or guideways, wherein the rails have a coefficient of thermal expansion that is different from that of the support structure to which they are attached. Differential thermal expansion and contraction of the rails with respect to the support structure may be accommodated without binding or distortion of the rails by coupling each guideway to the support structure at two different points. Typically, the coupling at the first point is rigid and prevents any movement of the rail with respect to the support structure. The second coupling includes a flexible component that permits movement of the rail with respect to the support structure in a direction of movement of the element or component. This flexible component may be a leaf spring. In another embodiment, the first coupling may also be flexible. A method is also disclosed for accommodating differential thermal expansion and contraction of the rail with respect to the support structure by providing first and second couplings between the rail and support structure wherein at least the second coupling includes a flexible component that permits movement of the rail with respect to the support structure in a direction generally parallel to the direction of movement of the machine element.

Temperature compensation system for a coordinate measuring machine

A machine, such as a coordinate measuring machine, having an element and a structure movable with respect to each other along rails, wherein the rails have a different coefficient of thermal expansion than the structure to which they are attached. In one embodiment, a bar is disposed on the structure opposite the rails. This bar has a coefficient of thermal expansion, a stiffness, a spacing from the neutral axis of the structure, and a cross-sectional dimension such that the bar balances any thermal stresses in the structure caused by differential expansion or contraction of the structure and the rails with temperature changes to minimize any bending of the structure. In one embodiment, two rails are disposed on a beam, and a carriage travels on the two rails. For each rail, there is an associated bar disposed on an opposite surface of the beam. In another aspect, a pin extends into an elongated slot on a slide associated with the structure to allow the structure to expand and contact. In yet another aspect, a movable element, such as a carriage, is coupled to an associated slide riding along the rails by a leaf spring to accommodate expansion and contraction of the element.

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East Greenwich, RI, United States of America

David W Payette