P.N. Yemelyanov, S.E. Ped?, I.E. Kholin

The article describes results of participation of State Engineering Center of MSTU «Stankin» with «Measuring instruments for engineering research and design institute» in design of sub-micron accuracy coordinate-measuring machine (SMACMM). The aim was to develop a domestic precision CMM replacing imported foreign analogues and eliminating critical dependence of imported double-purpose measuring devices. SMACMM has bridge configuration and measuring limits of 400400200 mm along X, Y and Z axes. The basic measurement error along axes is no more than 0,25+L/1000 micron, where L - measured distance, mm. These characteristics are guaranteed by following design solutions. Coordinate displacements are driven by direct drives based on linear synchronous motors with nonferrous armature and built-in cooling system. Coordinate displacements transducers are based on optical scales. The CMM uses closed aerostatic coordinate displacements guides. Guides - air-gap variation is measured by pneumo-inductive measuring system providing measuring results correction. Vibration resistance of SMACMM frame is assured by aerostatic isolating pads. Frame is thermostated by heat-insulating housing and thermo-stabilization system. In addition thermic errors are compensated by measuring the actual temperature of air within measuring area, the measured part and CMM and calculating error corrections. Among others, the software development task has been solved. Original measurement programing language was designed. The specific property of SMACMM software is a geometric parameters measurements precision increasing component. Precision is increased by calculating and introducing corrections of several errors, including coordinate displacements errors, axes position errors, air-gap variation errors, thermic errors.