Rotating sensor for new possibilities on Leitz Infinity coordinate measuring machine

摘要

A rotatory mount is being designed at CERN to determine the position of the axis of a 0.1 mm in diameter stretched wire with a sub-micron accuracy. As part of its role as world-wide leader in high energy particle physics, CERN is studying how to build a Compact Linear Collider (CLIC). One of the biggest challenges of this electron-positron collider is the alignment required for all the components acting on the beam: thousands of components will have to be assembled and aligned at the micrometre level. PACMAN, a study on Particle Accelerator Components Metrology and Alignment to the Nanometre scale, is a Marie-Sklodowska Curie Program supported by the European Commission (FP7 Program) whose aim is to develop and build a pre-alignment bench on which components are assembled and aligned to the required accuracy in one single step using a stretched wire as a reference [1]. During the process of this measurement, the axis of a stretched wire is aligned with respect to the reference axis of the components. The Cu-Be wire with a diameter of 0.1 mm considered for this project has been evaluated and its quality led to the conclusion that a form measuring sensor should be used to increase the precision of the measurement. The challenge is to measure the form error of this wire with 0.1 μm accuracy and its position with 0.5 μm precision on a Coordinate Measuring Machine (CMM). To do so, a rotary mount equipped with a non-contact sensor is designed with an opening in the radial direction. This paper introduces the requirements: no magnetic fields created, high accuracy on the positioning, low error motion, open on the side; and it describes and discusses the technical solutions: from the material to use to the bearings, including the kind of sensor.