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Achievable alignment accuracy and surface hardness of a large welded azimuth track

2006; SPIE; Volume: 6273; Linguagem: Inglês

10.1117/12.669805

1996-756X

David R. Smith,

Radio Astronomy Observations and Technology

In the design of high precision wheel-on-track systems for large telescopes, the azimuth track presents a significant challenge. Generally, the track must be aligned very accurately to provide good pointing performance and must have high hardness to withstand the contact stresses. It is also advantageous, in terms of both performance and stress, to have a continuous rolling surface with no gaps. Such a surface can be achieved by using a welded track, but it is challenging to maintain alignment and surface hardness during the welding process. For future designs, it is useful to understand what practical limits have been reached during previous installations. The azimuth track for the Large Millimeter-wave Telescope (LMT/GTM) serves as an excellent example of this type of system. It is 39.6m diameter and has been installed, aligned, and welded on site. As of early 2005, it has been supporting the weight of the alidade, and some initial rotations of the structure have taken place. The achieved alignment accuracy and hardness performance are presented, together with lessons learned during the installation, welding, and initial use of the track.