Constant load probe system for coordinate measurement machines

Abstract

An arrangement for applying a constant load on the probe of a coordinate measurement machine to eliminate errors caused by operator hand pressure when the probe is manually moved into engagement with a part being measured. In coordinate measurement machines, a carriage movable in the Y axis direction bridges the part being measured. A probe on the carriage is movable in the X axis direction thereby permitting probe movement in any quadrant in X-Y axis directions. To eliminate measurement errors in the Y axis direction, a constant load is applied to the probe by a pair of spring motors mounted on opposite ends of the machine. These spring motors are connected by spring motor cables to the carriage. When the back cable is attached to the carriage, the applied force urges it in the +Y axis direction, and the front cable when attached, urges the probe in the -Y axis direction. To apply a constant load on the probe in the X axis direction, spring motors are mounted on opposite ends of the carriage. Cables from these motors are selectively connected to the probe housing to respectively urge the probe in the +X or - X axis directions. By connecting appropriate spring motor cables to the carriage and probe housing, constant loads are applied to the probe which urges it in the X-Y axis directions in any one of four quadrants.