Traceable measurement of large gears with micron accuracy: a mandatory basis for reliable wind energy systems

The production of highly accurate components of renewable energy systems such as Wind Energy Systems (WES) or Tidal Power Generators (TPG) puts mandatory constraints in the verification procedures related to 3-D geometry for the tolerance of size, form, waviness and roughness. More information concerning geometric flank deviations, the case hardening and surface roughness properties are requested. This paper focuses on the calibration and measurement of large gears used in gearboxes of WES and TPG. One major issue ensuring traceability of these measurements is the lack of appropriate gear measurement standards. One large ring gear measurement standard was developed recently by the Physikalisch-Technische Bundesanstalt (PTB). In this contribution, the ring gear and its calibration on a large coordinate measurement machine (CMM) are described. Tactile measurement results are presented and put into context with calibration values from PTB. Furthermore, optical measurement results using a new interferometric point sensor, developed by Hexagon, are presented

New potential for the Leitz Infinity Coordinate Measuring Machine

The following study is realised within the frame of the PACMAN project: a study on Particle Accelerator Components Metrology and Alignment to the Nanometre scale, which is a Marie Curie program supported by the European commission and hosted by CERN (European Organisation for Nuclear Research). The aim of this program is to develop and build a pre-alignment bench on which each component is aligned to the required level in one single step using a stretched wire. During the operation, the centre of the stretched wire is aligned with the magnetic axis of the magnet. Then, the position of the wire is measured to the highest possible accuracy using a 3D Coordinate Measuring Machine (CMM) Leitz PMM-C Infinity from HEXAGON Metrology. The research described in this paper is two-fold: on one hand we apply a strong magnetic field to the head of the CMM and evaluate its influence on the measurement accuracy; on the other hand we measure the positio

Form measurement of a 0.1 mm diameter wire with a chromatic confocal sensor, with associated uncertainty evaluation

The accurate characterisation of a copper–beryllium wire with a diameter of 0.1 mm is one of the steps to increase the precision of future accelerators' pre-alignment. Novelties in measuring the wire properties were found in order to overcome the difficulties brought by its small size. This paper focuses on an implementation of a chromatic-confocal sensor leading to a sub-micrometric uncertainty on the form measurements. Hence, this text reveals a high-accuracy metrology technique applicable to objects with small diameters: it details the methodology, describes a validation by comparison with a reference and specifies the uncertainty budget of this technique

Evaluation of the performance variation of porous air pads on discontinuous surfaces

A new high accuracy position measurement system has been developed. It measures the position of a 0.1 mm diameter copper-beryllium wire that informs alignment of energy beams in advanced particle accelerators. This new measurement system employs air pads to provide precision and friction free rotation of a sensor. To enable the measuring system to be positioned over the wire, a slot is required in the measuring device rotor. To optimise the design of this measuring system it was necessary to understand the performance of the air pads as they pass over the gaps (slots) in the rotor. This paper describes modelling and experiments that were performed to gain understanding of air pad performance when encountering such a surface gap. Particularly, an analytical model of the variation of load of a 20 mm × 40 mm porous air pad during the passing of a 1.5 mm wide slotted surface. Subsequent experimentation revealed that the general behaviour of the load variation had been captured effectively. The results of this analysis reveal that air pads of this size can reliably pass above an opening of this size with about 14% reduction in force. The results and the methodology presented in this paper can be used as an effective basis for future designs and studie

Genome-wide Association Study of Alcohol Dependence

Identification of genes contributing to alcohol dependence will improve our understanding of the mechanisms underlying this disorder

Association of the OPRM1 Variant rs1799971 (A118G) with Non-Specific Liability to Substance Dependence in a Collaborative de novo Meta-Analysis of European-Ancestry Cohorts

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