(1) Gantry deformation can be eliminated by the correction method.

When the bending deformation is small, it is allowed to use the cold correction method with a static load. When the bending deformation is too large and difficult to correct by cold pressing, it can be fixed by heating. During heating, the heating area shall be reduced as much as possible. The heating temperature generally does not exceed 700 ℃, and it shall be cooled slowly to avoid increasing brittleness.

(2) Repair of gantry cracks. If cracks are found during the inspection, they shall be repaired.

1) Before repair, the gantry shall be corrected to maintain the inherent straightness of the gantry.

2) Grind the crack until the metallic lustre is exposed, carefully check to determine the crack boundary, and drill ¢ 5 – ¢ 8mm limit hole at the extension of 10mm.

3) Grind the weld bead groove with the grinding wheel at the crack.

4) When filling welding, it is best to use DC reverse polarity arc welding. The arc shall be as short as possible, the electrode diameter shall be 4mm, and the current shall be about 210-240a. During welding, the welding rod shall incline to the moving direction of 20 ° – 30 °. The filling and welding work starts from drilling through the hole to the other end of the crack, and the welding repair is also carried out on the reverse side. The weld height shall not exceed 1-2mm of the substrate plane. The ambient temperature during welding shall be above 0 ℃.