Large welding frame + machining are a common product in large mechanical parts at present. In the processing of large welded frame plus machining, we should know not only the machining requirements of the frame, but also need to know the fabrication requirements of the large welded frame. So what are the technical requirements for large welded frame?

1. The position of the weld seam should avoid the stress concentration area and should be easy to weld.

2.  The welding groove of welding steel structure should be processed according to the requirements of drawings. When the drawings are not specified, the groove style and size should be processed according to these principles: guaranteeing welding quality, less filling metal, convenient operation, reducing welding stress and deformation, etc.

3. Before assembling, the oil, paint, scale, rust, burr and galvanized layer on the surface of the welding joint and its vicinity should be cleaned up to reveal the metallic luster.
4. When the gap of the welding interface is too large, we should try to trim it to the required size, and strictly avoid adding stuffing in the gap.
5. The welding rods, wires and flux used in welding of large welding frame should be stored in dry, well ventilated place with temperature greater than 5 C and relative air humidity less than 60%.
6. In the process of welding frame fabrication, the workpiece should be positioned and fixed firmly in order to prevent deformation and additional stress from occurring during welding heating.
7. In addition to the cold-drawn butt welds specified in the design drawings, the other welds are forbidden to use strong external force to correct the welding seams position, and the thermal expansion method is not allowed in correction welding seams position of two pair’s parts in order to avoid additional stress.
8. In order to ensure the quality of the welding of the frame, the working places should be windproof, rain proof, snow proof and cold proof.
9. If preheating and post-weld heat treatment are required for welding parts, the preheating and post-weld heat treatment equipment, temperature measuring instruments and heat insulation protective equipment should be prepared before welding.
10. When welding on the welding plane, make sure that the longitudinal weld and the transverse weld (especially the transverse one) can shrink freely. If welding butt weld, the welding direction should point to the free end.
11. The welds with larger shrinkage should be welded first when fabrication steel frame. If there are butt welds and fillet welds in the structure, the butt welds with larger shrinkage should be welded first.
12. When fabrication steel frame, the transverse short weld should be welded first.
13. When the frame is welded, the weld with high stress should be welded firstly to make the internal stress distribution reasonable.
14. When welding the frame with large deformation, the reinforcing bars can be used reasonably according to the actual situation.
15. The multi-component composite welding parts should be assembled and welded step by step, and then the total  assembly and welding process should be carried out after correcting the deformation.
16. After the steel fabrication is completed, the internal and external surfaces or parts surface of the steel frame should be corrected and cleaned.
17. After welding, the surface of the steel frame should be shot blasting to improve the fatigue strength of the frame.

Above 17 points are the technical requirements of large frame welding processing. Steel frame Manufacturers and steel structure manufacturers should pay attention to these technical requirements when carrying out large frame welding processing, in order to better improve the quality of frame fabrication and welding.