Prefabricated steel structures are widely used in modern architecture. Their processing flow starts from raw materials and goes through multiple key links. Quality control at each link is of crucial importance, directly affecting the quality and performance of the final product. The following will detail the processing flow and key points of quality control.
I. Quality Control of Raw Materials
1. Strict Supplier Screening
Select raw - material suppliers with good reputations, rich industry experience, and reliable quality - assurance systems. Conduct on - site inspections of suppliers, evaluating their production equipment, technical levels, quality - management processes, etc., to ensure that they can stably provide steel that meets national standards and project design requirements.
2. Comprehensive Raw - material Inspection
After the steel arrives, conduct an appearance inspection first. Check whether there are defects on the surface such as cracks, blisters, scabs, and folds. At the same time, verify whether the specifications and dimensions of the steel are in line with the design requirements.
II. Quality Control of Laser Cutting
1. Preparation before Cutting
Before the cutting operation, re - check the material and specifications of the steel to ensure they are consistent with the processing requirements. Meanwhile, debug the laser - cutting equipment. Check whether components such as the laser generator, optical path system, cutting head, and transmission device are operating normally. Set appropriate cutting parameters, such as laser power, cutting speed, and gas pressure.
2. Monitoring during Cutting
During the cutting process, closely observe the cutting situation to ensure that the cutting path is accurate and there is no deviation. Control the cutting quality to ensure that the cut surface is flat and smooth, without obvious slag and burrs, and the verticality deviation of the cut is within the allowable range. For thick - plate cutting, pay special attention to preventing the cut from being wider at the top and narrower at the bottom or vice versa, ensuring a uniform cut quality.
III. Quality Control of Fabricating H - shaped Steel
1. Precise Component Positioning
When fabricating H - shaped steel, ensure the accurate positioning of the web and flange plates. Use professional fabricating equipment and fixtures to guarantee the perpendicularity between the web and flange plates and the flatness of the flange plates.
2. Reliable Temporary Fixing
During the fabricating process, temporarily fix each component. The fixing points should be evenly distributed and have sufficient fixing strength to prevent displacement during subsequent handling or welding, ensuring the overall shape and dimensional accuracy of the H - shaped steel.
IV. Quality Control of Automatic Submerged Arc Welding
1. Optimization of Welding Parameters
According to the material, plate thickness, and welding position of the H - shaped steel, select suitable welding materials (welding wires, fluxes), and precisely adjust welding parameters such as welding current, voltage, welding speed, and wire - feeding speed. Determine the optimal combination of welding parameters through welding procedure qualification tests to ensure the quality and performance of the weld.
2. Supervision during Welding
During the welding process, closely monitor the welding situation to ensure a stable welding arc and good weld formation. Prevent welding defects such as pores, slag inclusions, cracks, and lack of penetration. At the same time, control welding deformation. Adopt reasonable welding sequences and anti - deformation measures, such as symmetric welding and sectional back - step welding, to minimize the amount of welding deformation. After welding, inspect the appearance of the weld. The weld surface should be smooth and uniform, without obvious undercuts, depressions, etc.
V. Quality Control of H - shaped Steel Straightening
1. Selection of Straightening Method
According to the deformation of the H - shaped steel, select an appropriate straightening method, such as mechanical straightening (using a straightening machine to apply external force for straightening) or flame straightening (using the stress generated by local heating and cooling to correct the deformation of the steel). For minor deformations, mechanical straightening is preferred; for parts with large deformations or complex shapes, flame straightening can be used, but strictly control the heating temperature and cooling rate to prevent adverse effects on the steel properties.
2. Achievement of Precision Detection Standards
After straightening, use professional detection tools (such as rulers, levels, theodolites, etc.) to detect the straightness and flatness of the H - shaped steel. Ensure that the straightened H - shaped steel meets the design dimensions and shape requirements, providing qualified components for subsequent processes.
VI. Quality Control of Welding Small Components
1. Matching of Welding Processes
For different types and sizes of small components, select appropriate welding processes and equipment, such as manual arc welding and gas - shielded welding. Determine welding parameters according to the material and welding requirements of the small components and conduct welding procedure qualification to ensure welding quality.
2. Stringent Quality Inspection
After welding, conduct an appearance inspection of the welds of the small components to ensure that the weld surface quality meets the requirements. At the same time, conduct non - destructive testing on the welds according to a certain proportion to check whether there are internal defects. For welds that bear large loads or are in important parts, 100% non - destructive testing should be carried out to ensure reliable welding quality.
VII. Quality Control of Shot Blasting and Sandblasting
1. Adequate Equipment Debugging
Before shot blasting and sandblasting, fully debug the equipment to ensure that parameters such as the ejection speed, flow rate, and angle of the projectiles or sand grains meet the requirements. Check the sealing performance of the equipment to prevent the leakage of projectiles or sand grains. At the same time, ensure that the ventilation and dust - removal system operates normally to improve the working environment.
2. Achievement of Treatment Effect Standards
During the shot - blasting and sand - blasting process, control the treatment time and intensity to ensure that impurities such as rust, scale, and oil on the steel surface are thoroughly removed, reaching the specified rust - removal grade. The treated steel surface should present a uniform metallic luster, and the roughness should meet the requirements for subsequent painting to enhance the adhesion of the paint.
VIII. Quality Control of Painting
1. Correct Paint Selection
According to the usage environment and design requirements of the prefabricated steel structure, select the appropriate paint type and model to ensure that it has good anti - corrosion, anti - rust, and weather - resistance properties. At the same time, check the quality certification documents of the paint, including the production date, shelf - life, and performance indicators, to ensure the qualified quality of the paint.
2. Standard Painting Process
Before painting, ensure that the steel surface is clean and dry, free of dust, oil, and other impurities. Adopt an appropriate painting method and control the painting thickness and uniformity. During the painting process, maintain an appropriate ambient temperature and humidity to avoid defects such as sagging, orange peel, and missed spraying. After painting, cure it according to the regulations to ensure that the paint is fully dried and cured, forming a good protective coating.
IX. Quality Control of Roof and Wall Panel Production
1. Assurance of Dimensional Accuracy
During the production of roof and wall panels, strictly control the dimensional accuracy of the panels, ensuring that size deviations such as length, width, and thickness meet the design requirements. Use high - precision processing equipment and molds for processing operations such as cutting, bending, and punching of the panels to ensure the accuracy of the panel shape and dimensions.
2. Surface Quality Control
Pay attention to the surface quality of roof and wall panels to prevent defects such as scratches, deformation, and unevenness. Clean the surface of the processed panels to remove burrs, iron filings, and other impurities. At the same time, check the coating quality to ensure that the coating is complete and uniform, without peeling, cracking, etc.
X. Quality Control of Packaging and Shipping
1. Reasonable Packaging
According to the shape, size, and quantity of prefabricated steel - structure components, select appropriate packaging materials and packaging methods. For small components, cartons, wooden boxes, etc. can be used for packaging; for large components, use pallets, bundling, etc. for packaging. The packaging should be firm and reliable to prevent damage such as collision and deformation during transportation.
2. Safe Transportation
Select a logistics partner with a good reputation and transportation capacity to ensure safe and reliable transportation. Before shipping, inspect the transport vehicle to ensure that the vehicle is in good condition and has corresponding protective measures. During transportation, track and monitor the goods, and handle possible problems in a timely manner to ensure that the prefabricated steel - structure components are delivered to the destination on time and in good condition.