ISSUES IN THE MECHANICAL ENGINEERING DESIGN OF HIGH-PRECISION KINEMATIC COUPLINGS

摘要

A three V-groove (Maxwell-type) kinematic mount design configuration constrains all degrees of freedom of the apparatus mounted onto it, thus allowing its high-precision positioning and repositioning. The analysis of this mechanical assembly comprises force and moment balances, as well as expressions for stress-strain and error motion calculations. For determined loading conditions and the geometry of the mount, the resulting loads across each groove-ball interface imply, however, the necessity to consider the complex nonlinear Hertz theory of point contacts between elastically deforming solids. The available analytical approaches to the calculation of the conditions at the ball- V groove contacts are hence recalled in this work with the aim of establishing the respective limits of applicability. The obtained results are validated experimentally. A structured calculation procedure is then used to assess the stability of a kinematic mount employed to support a large mechanical component at a particle accelerator facility, depending on the value and orientation of the external loads acting on the studied assembly. Stability conditions for different design configurations are consecutively established.