AVS 59th Annual International Symposium and Exhibition
    Vacuum Technology Wednesday Sessions
       Session VT+AS+SS-WeM

Paper VT+AS+SS-WeM1
Manufacturing and Welding Processes for TPS Large Aluminum Bending-Chambers and 14 m Vacuum Cells

Wednesday, October 31, 2012, 8:00 am, Room 14

Session: Surface Analysis and Vacuum Manufacturing for Accelerators
Presenter: C.L. Chen, NSRRC, Taiwan, Republic of China
Authors: C.L. Chen, NSRRC, Taiwan, Republic of China
C.C. Chang, NSRRC, Taiwan, Republic of China
C.K. Chan, NSRRC, Taiwan, Republic of China
Y.C. Yang, NSRRC, Taiwan, Republic of China
T.Y. Lee, NSRRC, Taiwan, Republic of China
G.Y. Hsiung, NSRRC, Taiwan, Republic of China
J.R. Chen, NSRRC, Taiwan, Republic of China
Correspondent: Click to Email
A unique manufacturing and welding technique has been developed for building the 3 GeV Taiwan Photon Source (TPS) large aluminum bending chambers and 14-meter vacuum cells. There are total 48 bending chambers, which are about 3.8 meters long each. Combined with an appropriate manufacturing processes, such as with a precise CNC machine, lubrication with pure alcohol and cleaning with ozonated water, the aluminum chambers have an oil-free interior surface finished for an ultra-high vacuum environment before aluminum welding. Ozonated water has a high oxidation potential and can remove most organic contaminations. It is used to effectively clean aluminum chambers’ surfaces, and provides with the lowest outgassing yield.After the bending chambers are cleaned with ozonated water, the chambers are moved to a welding room for following welding processes. A novel automatic gas-tungsten arc-welding (GTAW) system has been established at NSRRC for welding the aluminum bending chambers. This welding system has a XY stage that is built and configured to provide high-performance positioning along multiple welding axes. The automatic welding system comprises six welding torches to implement simultaneously two longitudinal side welds of a bending chamber, and is innovative in using computer-based software to control the welding movements and the welding parameters of the six-torch output. In traditional manual welding, the key success factors focus on elimination as much as possible the distortions of structural assemblies. The six-torch welding and a clamp-free approach together address the issue of reducing distortion and minimizing residual stresses with a novel one-step welding process. In addition, on-site welding sequence is introduced for assembling two straight and two bending chambers into one 14-meter vacuum cell. From the beginning of CNC machining to the end of vacuum cell assembly, deformations through all process sequences are measured and controlled under 300 μm. In this paper, both the manufacturing sequences, vacuum data and statistical analysis of deformation control are presented in detail.