1. Processing of bolt holes for connecting plates and gusset plates. The bolt holes are processed using a tire mold drilling machine. The center line of the connecting plate must be drawn as a drilling positioning reference and a main beam assembly reference.

2. Steel rust removal: Steel must be shot blasted and rust removed to ensure that the surface is free of rust, oil stains and dirt. Primer should be applied promptly after rust removal. Painting on the friction surface of high-strength bolts is strictly prohibited. Various profiles are also subjected to rust removal treatment. Anti-corrosion in time after rust removal. The steel can also be shot blasted and rust removed after assembly and welding.

3. Truss welding After the truss is successfully assembled, use CO2 shielded welding to weld it. The components should be padded flat before welding to prevent thermal deformation. The welding sequence is that the two welding machines are symmetrical, in the same direction, and in the same specification, or welded in the welding sequence of 1, 2, 3, and 4. Its specifications are based on parameters determined by process tests.
4. Numbering and cutting
1) For various shaped parts such as ribs and gusset plates, a CNC cutting machine is used to cut and blank them.
2) The main beam adopts a segmented manufacturing process.
3) All types of cutting parts need to be audited on the material line before cutting, and can only be cut and blanked if they are qualified.
4) For long components, manual cutting and automatic cutting machine cutting are adopted. Angle steel is cut and blanked by a combined blanking machine.
5. Truss deformation correction and stress relief. If the truss after welding is inspected for deformation out of tolerance, use flame method to correct it, and perform flame stress relief treatment at the same time.
6. CO2 gas shielded welding is used for welding and orthopedic welding. The welding wire is HO8Mn2SiA with a diameter of 1.2MM. The welding sequence is simultaneous and in the same direction on both sides. The welding specifications must be consistent. After welding, use oxyacetylene flame to correct the welding deformation, and perform flame stress relief treatment at the same time. Then inspect various indicators according to the requirements of the inspection record sheet. When using manual arc welding, the welding current should be moderate.
7. H-shaped steel assembly, welding, correction and welding. The H-shaped steel is assembled on the assembly machine, welded on the gantry welding machine, and corrected on the flange straightening machine. The welding wire is HO8A or H08Mn2Si, and the flux is HJ431.
8. Paint and mark. Apply primer and topcoat according to the design requirements, and then use a leaky plate to repaint the mark number on the designated position on the left end of the main beam. The mark color is white. At the same time, bolt the component mark on the bolt hole of the end plate of the beam. After passing the iron plate, it will be shipped to the site according to the production plan.
9. Truss assembly
1) When assembling gusset plates and connecting plates, ensure that the datum line is aligned with the center of the beam. The assembly should be performed by experienced workers to ensure accuracy.
2) Before assembling the truss, check the size, shape and shrinkage and placement of each piece. After passing the inspection, use a grinding wheel to clean the weld area. The cleaning range is 4 times the width of the weld.
3) Mark out the component position lines on the steel platform as a backer and assemble according to the lines. Positioning spot welding uses manual arc welding. Welders must have a work permit.