On the accuracy of port assembly at Wendelstein 7-X Max-Planck-Institut für Plasmaphysik, EURATOM Association On the accuracy of port assembly at Wendelstein 7-X Torsten Bräuer and metrology team torsten.braeuer@ipp.mpg.de Introduction Wendelstein 7-X use 254 ports; 2/3 for diagnostic, 1/3 for supply purpose; Size of ports varies between 1.2 ... 2.1m in length, 0.1 ... 1 m in diameter and 6 ... 15 mm in wall thickness Ports bridge the cryo-vacuum and have to be thermal insulated General assembly tolerance: 4 ... 8.5 mm (in global cosy) Reduced tolerances down to 2 mm in cases of higher accuracy requirements Position of vacuum vessel openings are taken as they are (after final vessel assembly) Assembly of ports takes place in 4 steps Port preparation: length, contour, cabling, sensors ... Thermal insulation: external company (MAN DT) Installation of port: adjustment, tack welding Final welding: controlled by metrology, final checks of weld seam I. III. II. Scan of VV opening 2D contour plot is used to wrap around port and perform port cutting Final cut of port Ports and VV of a half module; outer vessel dismantled; ports are shown with over length The accuracy of port length and contour is approx. 1 … 1.5 mm Port assembly in horizontal and vertical direction using a sliding table device; orientation of movement vector is adjusted by sighting method; flange position is adjusted by laser-tracker after dismantling of sliding table Lateral and axial assembly deviation of port flanges; each point represents one port and its deviation; assembly sequence: module 5, 1, 4, 2; in module 3 no ports assembled up to now; tolerance overstepping are accepted one base of technical arguments. AEV ports at module separation plan 5/1 Both ports are used for magnetic flux surface measurements Axis of both ports should be precise in a plan Modified assembly procedure Installation and tack welding as usual; usual tolerances Repeated measurement of actual axis position of both ports Determination of correction values for welding and control welding process by laser-tracker Result: axis of both ports are inside a virtual plan within an accuracy of < 1 mm Accuracy fits with requirements of diagnostic Metrology support; measurement of port flange using T-probe of laser-tracker (left); measurement of pipe axis (right); laser-tracker looks into port and performs a scan of pipe wall Conclusion 176 out of 254 ports are assembled at moment Most ports are inside tolerance without correction measures Only few ports exceeds tolerances, but actual position is accepted on base of technical arguments 3D metrology turned out to be an important factor to achieve position accuracy More accurate results than in case of only sighting methods Controlling of welding process is possible measurement accuracy of typically 0.3 … 0.6 mm is appropriated to all port adjustment and welding control processes use of laser-trackers is mainly limited by sighting conditions Other limitations like air condition, vibrations and bright light sources can be reduced in their influence to an acceptable level Only a good harmony of adjustment, welding and metrology procedures allows assembly processes with reduced tolerances down to 2 mm AEK-V2 port in module 2 2 ports of AEK-V2 type, used for NBI heating Inner cross section should be as large as possible to avoid beam interaction with port wall Outer surface of port is very closed to surrounding coils Port is separated in 2 parts main port body is assembled as usual; pocket is assembled from VV site Port is scanned before installation and a collision check is performed Installation of temporary reference point system for permanent micrometer gauges measurements during welding of pocket Control of main port body welding process by laser-tracker Result: in critical collision areas the port geometry deviates not more than 2 mm compared to reference Accuracy requirements on position and contour are achieved 27th SOFT, Liege, 24. – 28.9.2012