1. The welding of the frame must ensure symmetry, balance, and verticality, and be made according to the size requirements of the drawing.

1. During welding, there should be no defects such as false welding, pores, slag, cracks, welding tumors, burn-through, arc pits, bite edges, welding abrasions, and unsoldered welding on the welding surface. The welding should be uniform and beautiful.； 

2. The surface cannot be uneven after welding.； 

3. The surface of the fuselage must be polished and smoothed to clean up welding slag；

4. The welding slag must be cleaned up after welding, and the surface must be polished flat and smooth.；

5. The production of the guide belt groove must be consistent with the opening and closing hinges, the surface is flat, and there can be no high or low, one opening and one closing phenomenon.

2. The bending of sheet metal parts must be made according to the requirements of the drawings. Those with arcs must be smooth, the bending surface must be flat, no irregularities can occur, and the dimensional symmetry, parallelism, and verticality must be guaranteed.

3. Post-welding treatment

1. After the welding is over, the slag splashes on the surface of the weld should be cleaned, the dimensions and appearance quality of the welds should be checked, and the welds should be trimmed when they are uneven.

2. The shape of the weld should be smooth and uniform, and the transition between the weld and the weld, the weld and the base metal should be smooth.

3. For some closed structures, components with multiple welds and long welds, methods such as hammering and vibration should be used to eliminate residual stress after welding. If the parts have heat treatment requirements, heat treatment should be used to eliminate stress.