Structure design and analysis of tracking frame for horizontal telescope

The structure design scheme of U-type tracking frame was put forward for a 700 mm aperture horizontal telescope. The double row dense ball bearings were used for azimuth shafting, and the bearing was designed as double row of axial thrust steel balls and double row of radial steel balls. The dense of the ball could ensure the high rotation accuracy of the shafting. First, the pitching shafting was designed as a structure with one end fixed and one end floating to compensate the effect of mechanical error and thermal deformation on the rotation accuracy. Then, the finite element model of tracking frame was established, and the first order resonance frequency could reach to 47.6 Hz, which showed that it had good modal characteristics. Finally, the electronic level and digital autocollimator were used to measure the pitch axis and azimuth axis respectively. The shaking of azimuth axis shafting was better than 1.3″, and the shaking of pitching axis shafting was better than 1.8″. The test results show that the designed telescope tracking frame structure has high stiffness and high rotation accuracy, which provides some reference value for the structure design of similar tracking frames.