Brown & Sharpe Manufacturing Co.

Other

Yuzhong Dai

Thomas Charlton, Jr

Vitaly I Pesikov

Walter L Beckwith, Jr

Raymond J Guertin

Disclosed are methods and apparatuses for varying stiffness and/or damping characteristics of a vibration isolation system based on the machine's control signal which indicates the motion status of at least one movable component of a machine supported by the vibration isolation system. The motion status of the movable component can be monitored via parameters such as the electrical power being injected into the motor of the movable component. More stiffness and/or damping are provided to absorb shocks generated while the movable component accelerates or decelerates and less stiffness and/or damping are provided while the movable component moves at a nominally constant speed or stands still. The stiffness and/or damping characteristics of a vibration isolation system are varied by controlling one or more of the following: 1) the gas flow rate between two gas chambers, 2) the strength of a magnetic field applied to a magnetorheological fluid or ferrofluid, and 3) the strength of an electric field applied to an electrorheological fluid.

Proactive shock absorption and vibration isolation

A multi-probe system for dimensional metrology. This system utilizes a probe base that is attachable to a coordinate measuring machine and that includes a plurality of probes mounted at spaced-apart locations on the base. The probes are interconnected with the coordinate measuring machine and generate measurement signals based upon interaction with a workpiece. By providing a plurality of probes on a single assembly, multiple measurements can be made on a workpiece in a single measurement cycle.

Multi-probe system for dimensional metrology

Devices for verifying the dimensional accuracy of a measuring instrument are provided. In one embodiment, a verification block has a substantially planar surface and a known nonplanar surface adjacent thereto. During verification, a probe attached to the CMM moves along the nonplanar surface while simultaneously contacting the planar surface and measures the features of the nonplanar surface. Any difference between the measured features and the known features of the nonplanar surface is an indication of inaccuracies in the CMM. Other embodiments of the invention include structures which compare CMM measured readings with known readings by an encoder as it moves along a linear scale. In another embodiment, the measured readings are compared to readings provided by opto-electric switches. In still another embodiment, a cam is rotatably mounted to the end of the probe of the CMM and moves the probe along the z axis as the cam moves along a surface. A predicted period based on the known cam geometry is compared to the period of motion measured by the CMM. Any difference between the measured period and the actual period is an indication of inaccuracies in the CMM.

Accuracy verification devices for coordinate measuring machines

A coordinate measuring machine includes a support structure, an articulated arm having a first end pivotally connected to the support structure and a second end that is movable in a horizontal plane. A Z-ram assembly is mounted to the second end of the articulated arm. The Z-ram assembly includes a Z-ram housing and a probe that is vertically movable with respect to the Z-ram housing. The probe is movable within a measurement volume defined by the articulated arm and the Z-ram assembly. The coordinate measuring machine further includes a measuring assembly for determining coordinates of the probe in the measurement volume. The articulated arm preferably includes first and second arm assemblies that have a parallelogram configuration to prevent substantial rotation of the Z-ram assembly as the articulated arm is moved in the horizontal plane. The angles of the articulated arm are preferably measured using a sensor which includes a pattern of parallel, straight grating lines.

Coordinate measuring machine having articulated arm

A device for measuring an angle between pivotally connected, intersecting sides of a parallelogram includes a grating having a pattern of parallel, straight grating lines formed on a substrate, and a read head. The grating is mounted in a fixed position with respect to a first side of the parallelogram. The read head includes a sensor positioned for sensing displacement of the grating lines in response to an angular change between the intersecting sides of the parallelogram and generating a scale reading. The read head is mounted in a fixed position with respect to a second side of the parallelogram that is parallel to the first side. In one embodiment, the grating includes a single pattern of grating lines and is used to measure an angular change relative to a reference angle. In a second embodiment, the grating includes first and second grating patterns and is used to measure an absolute value of the angle between the intersecting sides of the parallelogram. The precision angle measuring device is particularly useful in coordinate measuring machines, but is not limited to such use.

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Coventry, RI, United States of America

Yuzhong Dai