1. Plate Stock Cutting
The NC thermal cutter that our specialists use for nesting, is designed to to cut plate with the thickness from 6 to 100 mm with the accuracy of ±1 mm. This equipment is used to cut metal strips that will later become welded I-beam flanges and webs, as well as parts with complex geometry (flanges, column baseplates, gussets etc.). Depending on the metal thickness, the cutting speed can reach 1 meter per minute.
Some parts with a rectangular or a square shape are manufactured with the use of parallel shears.
2. Edge Milling
In case of high-thickness plate, edges must be prepared for welding in order to comply with the welding technology. For this purpose, the part’s edges are chamfered at a given angle.
This can be done either at a special edge milling machine or manually with specialized hand tools. The angle accuracy is monitored with a bevel gage.
3. Beam Assembly
The crane places prepared workpieces (strips) on the input conveyor of the assembly mill, and assembly mill roller kits are used to position and fix those. Then the assembly mill performs the centering and swaging of workpieces in accordance with the initial parameters of webs and flanges, and the beam is tack-welded along its length.
The assembly process:
- Assembly of the T-shaped section: the I-beam web is tack-welded to the bottom flange of the I-beam at an angle of 90 °.
- The assembled T-section is canted at 180 ° with a crane and returns to the run-in table of the assembly mill.
- The other I-beam flange is tack-welded then.
4. Welding of Circumferential Seams
When girth seams are welded, the beam is placed on the cradle of of the gantry welding unit at an angle of 45 degrees (gravity fillet weld). This technology enables good penetration and smooth transition of the weld to the base metal. The gantry welding unit has two sets of welding heads that can be moved horizontally or vertically, producing welds simultaneously with the movement of the gantry along the rails.
The welding heads are equipped with a laser weld position tracking system. In addition, the unit is equipped with a welding flux feeding, filtering, and removal system. In the process of girth welding, the tacks melt, becoming one with the weld.
5. Elimination of flange shrinkage distortion
The girth welding inevitably leads to a defect in the beam flange geometry (so-called shrinkage distortion), which appears as a result of uneven heating of the metal piece along the flange width.
The beam straightening machine is designed to eliminate such defects by passing the product through a system of rollers with the use of elastic properties of the metal. This straightening method prevents damage to the finished beams, does not affect the girth seams, and prevents weld cracking.
6. Steel structure assembly and seal welding
In addition to welded I-beams, hot-rolled I-beams, channels, angles, as well as round pipes and hollow sections, are also frequently used in steel structure manufacturing.
Hot-rolled products are processed at band saw machines designed to cut elements not only at a straight but also at any given angle.
Structures are assembled in accordance with the requirements of the drawings for a particular element. After the assembly on tacks and the geometry control, the elements are transferred to the final gas-shielded semi-automatic seal welding.
7. Cleaning and Painting
After seal welding, the structures must be cleaned from weld spatter and flowed metal and shotblast-cleaned. The shotblast machine is equipment used for cleaning steel structures prior to painting.
The machine emits a powerful jet of abrasive steel shots aimed at the surface of the structure at different angles, removing rust, scales, and various contaminations. After the structural elements have passed through the shotblast chamber, the result is a clean rough metal surface with excellent adhesion to the paint finish.
Upon completion of cleaning, degreasing, and dust removal, the structures must be primed and painted in accordance with the Customer’s wishes and the requirements of design documents. Various options for the protection of metal structures against corrosion are presented: from the application of a priming layer to the high-quality painting with the use of modern anti-corrosion protection systems.