Reducing the Dynamic Errors of Coordinate Measuring Machines

Coordinate measuring machines (CMMs) are already widely utilized as measuring tools in the modern manufacturing industry. Fast and accurate probing is the current trend for the next generation of CMMs. However, measuring velocity of CMM applications are limited by dynamic errors that occur in CMMs. In this paper, the dynamic errors of coordinate measuring machines are analyzed theoretically and experimentally. The limited stiffness of air bearings were found to cause dynamic errors due to the existence of Abbe's offsets. The characteristics of the air bearings used on CMMs were modeled by the finite element analysis (FEA). The load capacity and stiffness of the air bearings were computed. Using this model, the dynamic errors of the CMM were reduced through revising the air bearing design. To verify the effectiveness of this approach, the performance of the air bearings was tested both statically and dynamically. The results show that the dynamic errors can be significantly reduced.

[1]  Ivan Iordanoff,et al.  Analysis of an Aerodynamic Compliant Foil Thrust Bearing: Method for a Rapid Design , 1999 .

[2]  K. J. Stout,et al.  Theoretical analysis of two configurations of aerostatic flat pad bearings using pocketed orifice restrictors , 1993 .

[3]  Hooshang Heshmat,et al.  Analysis of Gas Lubricated Foil Thrust Bearings Using Coupled Finite Element and Finite Difference Methods , 2000 .

[4]  Phj Piet Schellekens,et al.  Design of a High-Precision 3D-Coordinate Measuring Machine , 1998 .

[5]  Chuck Zhang,et al.  Prediction and Compensation of Dynamic Errors for Coordinate Measuring Machines , 2002 .

[6]  Justus Bjorn Post,et al.  A tolerancing procedure for inherently compensated, rectangular aerostatic thrust bearings , 2000 .

[7]  J. B. Bryan,et al.  The Abbé principle revisited: An updated interpretation , 1979 .

[8]  Kyosuke Ono,et al.  Fundamental Study on Damping Characteristics of Externally Pressurized Porous Gas Bearing. (Analysis of Annular Thrust Bearing with Orifice and Capillary Models). , 1994 .

[9]  J. Lin.  Surface roughness effect on the dynamic stiffness and damping characteristics of compensated hydrostatic thrust bearings , 2000 .

[10]  Mohamed Fourka,et al.  Comparison between externally pressurized gas thrust bearings with different orifice and porous feeding systems , 1997 .

[11]  Ralph C. Veale,et al.  Error Compensation of Coordinate Measuring Machines , 1985 .

[12]  D. A. Boffey,et al.  Experimental investigation into the performance of an aerostatic industrial thrust bearing , 1985 .

[13]  Phj Piet Schellekens,et al.  Assessment of Dynamic Errors of CMMs for Fast Probing , 1995 .

[14]  C. M. Rodkiewicz,et al.  On the Design of Thrust Bearings Using a CFD Technique , 1997 .

[15]  W. G. Weekers,et al.  Compensation for dynamic errors of coordinate measuring machines , 1997 .

[16]  Qingping Yang,et al.  Dynamic error characteristics of touch trigger probes fitted to coordinate measuring machines , 1998, IEEE Trans. Instrum. Meas..

[17]  Sadek Z. Kassab,et al.  Effects of operating conditions and supply hole diameter on the performance of a rectangular aerostatic bearing , 1997 .