Steel structure plant mainly refers to the main load-bearing components are composed of steel. Including steel columns, steel beams, steel structure foundation, steel roof truss (of course, the span of the factory is relatively large, basically now are steel structure roof truss), steel roof, pay attention to the wall of steel structure can also be maintained by brick wall. Due to the increase of China's steel production, many have begun to use steel structure plants, which can also be divided into light and heavy steel structure plants. Industrial and civil construction facilities made of steel are called steel structures. Steel structure plant features: 1, steel structure building light weight, high strength, large span. 2, steel structure construction period is short, reduce the investment cost accordingly. 3. Steel structure building has high fire resistance and strong corrosion resistance. 4, steel structure building is easy to move, recycling pollution-free.
Construction technology of steel structure
Scope of application: It is suitable for the processing process of building steel structure, including the selection of process flow, lofting, marking, cutting, correction, molding, edge processing, tube ball processing, hole making, friction surface processing, end processing, component assembly, round tube component processing and steel component pre-assembly
1 Material Requirements
1.1.1 The steel, welding materials, coating materials and fasteners used in the steel structure shall have quality certificates and must meet the design requirements and current standards.
1.1.2 The raw materials entering the factory shall, in addition to the ex-factory quality certificate of the manufacturer, carry out on-site witness sampling, sample delivery, inspection and acceptance under the witness of Party A and the supervisor in accordance with the contract requirements and relevant current standards, and make inspection records. And provide inspection report to Party A and supervisor.
1.1.3 In the process of processing, if the defects of raw materials are found, they must be studied and processed by inspectors and competent technicians.
1.1.4 Material substitution shall be submitted by the manufacturing unit in advance with the application form (technical approval sheet) attached with the material certificate, submitted to Party A and the supervisor for approval, and confirmed by the design unit before substitution.
1.1.5 It is strictly prohibited to use the electrode with peeling or rusted core, damp caked or melted flux and rusty wire. The surface of the stud used for stud welding shall not have defects such as cracks, striations, dents and burrs that affect the use of the stud.
1.1.6 Welding materials should be centrally managed, a dedicated warehouse should be established, and the warehouse should be dry and well-ventilated.
1.1.7 Bolts should be stored in a dry and ventilated room. The acceptance of high-strength bolts shall be carried out according to the requirements of the current national standard "Design, Construction and Acceptance Procedures for high-strength Bolt Connection of Steel Structure" JGJ82, and the use of corroded, stained, damp, bruised and mixed batch high-strength bolts is strictly prohibited.
1.1.8 The paint shall meet the design requirements and be stored in a special warehouse. Expired, deteriorated, caked and ineffective paint shall not be used.
2 Main machinery
Steel structure
Hai Luo steel structure
1.2.1 Main equipment
Steel structure production long tool.
3 Operating Conditions
1.3.1 The detailed construction drawing shall be completed and approved by the original designer.
1.3.2 Various technical preparations such as construction organization design, construction scheme and operation instructions have been prepared.
1.3.3 Various process evaluation tests, process performance tests and material purchase plans have been completed.
1.3.4 Main materials have entered the factory.
1.3.5 All kinds of mechanical equipment debugging acceptance.
1.3.6 All production workers have received pre-construction training and obtained the corresponding qualification certificate.
4 Operation process
1.4.1 Process flow
1.4.2 Operation process
1 Lofting, marking material
1) Familiar with the construction drawings, find any questions, should contact the relevant technical departments to solve.
2) Ready to do sample, sample rod materials, generally can be used thin iron sheet and flat steel.
3) Lofting requires steel ruler must be checked and reviewed by the metrological department, and can be used after passing.
4) The material and specifications of the raw materials must be understood before the number of materials, and the quality of the raw materials must be checked. Different specifications, different materials of parts should be divided into different numbers. And according to the principle of first big and then small in turn.
5) The sample rod should be painted to indicate the processing number, component number and specification, and mark the diameter of the upper hole, the working line, the bending line and other processing symbols.
6) Lofting and marking should reserve shrinkage (including on-site welding shrinkage) and machining allowance required by cutting and milling end:
Milling end allowance: generally add 3-4mm per side after cutting, and 4-5mm per side after gas cutting.
Cutting margin: automatic gas cutting slit width is 3mm, manual gas cutting slit width is 4mm.
The welding shrinkage is given by the process according to the structural characteristics of the member.
7) The main force members and members that need to be bent should be taken in the direction specified by the process when marking the material, and there should be no sample impact points and scars on the outside of the bending parts.
8) The marking material should be conducive to cutting and ensuring the quality of parts.
9) The remaining materials after the marking shall be identified, including the number, specification, material and batch number of the remaining materials, so as to facilitate the reuse of the remaining materials.
2 Cutting
The steel after the blanking line must be cut according to its desired shape and size.
1) The following points should be noted when cutting:
(1) When many parts are arranged on a steel plate and there are several intersecting shear lines, a reasonable cutting procedure should be arranged in advance before cutting.
(2) The bending deformation of the material after shearing must be corrected; The shear surface is rough or has burrs, and must be trimmed and polished.
(3) In the shearing process, the metal near the incision is squeezed and bent due to the shearing force, and the interface position of the important structural parts and welds must be milling, planing or grinding wheel.
2) Sawing machinery construction should pay attention to the following construction points:
(1) The section steel should be straightened before sawing.
(2) For single-piece sawing components, first draw the marking line, and then cut the line. The components processed in batches can be pre-installed with positioning baffles for processing.
(3) Important components with high machining accuracy requirements should be considered to reserve appropriate machining allowance for face finishing milling after sawing.
(4) When sawing, attention should be paid to the control of the perpendicularity of the cutting section.
3) In the gas cutting operation should pay attention to the following process points:
(1) Before gas cutting, the equipment and tools of the entire gas cutting system must be checked to ensure normal operation and safety.
(2) The correct process parameters should be selected when gas cutting. When cutting, the shape of the oxygen jet (wind line) should be adjusted to achieve and maintain a clear outline, long wind line and high shooting force.
(3) Before gas cutting, the dirt, oil, floating rust and other debris on the surface of the steel should be removed, and a certain space should be left below to facilitate the blowing out of the slag.
(4) When gas cutting, tempering must be prevented.
(5) In order to prevent gas cutting deformation, the operation should start from the short side; Should cut the small parts first, then cut the large parts; The more complex ones should be cut first and the simpler ones later.
3 Correction and molding
1) Correction
(1) Cold correction of finished products, generally using mechanical forces such as flange leveler, straightener, hydraulic press, press and so on.
(2) Flame correction, heating methods are point heating, linear heating and triangular heating.
The thermal correction heating temperature of low carbon steel and ordinary low alloy steel is generally 600 ~ 900 ° C, and 800 ~ 900 ° C is the ideal temperature for thermoplastic deformation, but not more than 900 ° C.
Medium carbon steel will crack due to deformation, so medium carbon steel is generally not corrected by flame.
Ordinary low-alloy steel should be cooled slowly after heating correction.
Process flow
2) Molding
(1) hot processing: low carbon steel is generally in 1000 ~ 1100 ° C, hot processing termination temperature should not be lower than 700 ° C. The heating temperature is 500 ~ 550ºC. The steel is brittle, it is strictly prohibited to hammer and bend, otherwise it is easy to break the steel.
(2) Cold processing: Steel is processed at room temperature, most of which are carried out using mechanical equipment and special tools.
4 Edge machining (including end milling)
1) Commonly used edge processing methods are: edge cutting, planing, milling, carbon arc gouging, gas cutting and bevel machining.
2) For gas-cut parts, when the influence zone needs to be eliminated for edge processing, the minimum processing allowance is 2.0mm.
3) The depth of the machining edge should be able to ensure that the surface defects are removed, but not less than 2.0mm, the surface should not be damaged and cracked after processing, and the grinding traces should follow the edge when the grinding wheel is processed.
4) The edge of carbon structural steel parts, after manual cutting, the surface should be cleaned, and there should be no roughness of more than 1.0mm.
5) The supporting side of the end of the member requires the planing top tight and the section accuracy of the end of the member is higher, no matter what method of cutting and what kind of steel is made of, it is necessary to planing or milling.
6) The edge of the construction drawing with special requirements or provisions for welding needs to be planed, and the shear edge of the general plate or steel does not need to be planed.
7) After mechanical automatic cutting and air arc cutting of the edge of the part, the flatness of the cutting surface can not exceed 1.0mm. The free edge of the main stress member requires a processing allowance of planing or milling after gas cutting, at least 2mm on each side, and there should be no burrs and other defects.
8) After the column end milling, the top tight contact surface should be more than 75% of the area close to the 0.3mm feeler, the stuffing area should not be greater than 25%, and the edge gap should not be greater than 0.5mm.
9) The choice of milling and milling amount should be determined according to the workpiece material and processing requirements, and a reasonable choice is the guarantee of processing quality.
10) The end processing of the component should be carried out after the correction is qualified.
11) Necessary measures should be taken according to the form of the component to ensure that the milling end is perpendicular to the axis.
Five-hole system
1) The production methods of high-strength bolts (large hexagonal head bolts, torsional shear bolts, etc.), semi-round head rivet self-tapping screws and other holes are: drilling, milling, punching, reaming or countersinking.
2) Component drilling is preferred, and punching is allowed when it is proved that the quality, thickness and aperture of some materials will not cause brittleness after punching.
All ordinary structural steels with a thickness of less than 5mm are allowed to be punched, and minor structures with a thickness of less than 12mm are allowed to be punched. The punching hole shall not be followed by welding (groove shape), unless it is proved that the material retains considerable toughness after punching, then welding construction may be performed. Under normal circumstances, when drilling a larger hole to be punched, the hole must be 3mm smaller than the specified diameter.
3) Before drilling, one is to grind the drill, and the other is to reasonably choose the chip allowance.
4) The bolt hole made should be positive cylindrical shape and perpendicular to the steel surface at the location, the inclination should be less than 1/20, the hole perimeter should be free of burrs, cracks, flares or bumps, and the cutting should be cleared.
5) The diameter of the bolt hole made of refining or reaming is equal to the diameter of the bolt rod. The hole should have the accuracy of H12 after drilling or assembly, and the surface roughness of the hole wall Ra is less than 12.5μm.
6 Friction surface processing
1) The processing of high-strength bolted friction surface can be done by sandblasting, shot blasting and grinding with grinder. (Note: The grinding direction of the grinder should be perpendicular to the force direction of the component, and the grinding range should not be less than 4 times the diameter of the bolt.)
2) The treated friction surface should take anti-oil and damage protection measures.
3) The manufacturer and the installation unit shall respectively conduct anti-slip coefficient tests with steel structure manufacturing batches. The manufacturing batch can be divided into divisions (sub-parts) of the specified engineering quantity for each 2000t batch, and those less than 2000t can be regarded as a batch. When two or more surface treatment processes are selected, each treatment process should be inspected separately, with three groups of specimens per batch.
4) The specimens for the anti-slip coefficient test shall be processed by the manufacturer, and the specimens and the steel structural members represented shall be made of the same material, in the same batch, with the same friction surface treatment process and the same surface state, and the same batch of high-strength bolt connection pairs with the same performance grade shall be applied and stored under the same environmental conditions.
5) The thickness of the specimen steel plate should be determined according to the representative plate thickness in the steel structure engineering. The surface of the specimen plate should be smooth, free of oil, and the edge of the hole and plate should be free of flash and burr.
6) The manufacturer shall conduct the anti-slip coefficient test while the steel structure is being manufactured and issue a report. The test report shall state the test methods and results.
7) Components with the same material and treatment method for retesting anti-slip coefficient should be made according to the requirements of the current national standard "Design, construction and Acceptance procedures for high-strength bolted connection of Steel Structures" JGJ82 or the provisions of the design document, and the components should be handed over at the same time.
7 Tube ball processing
1) Rod production process: purchase steel pipe → inspection material, specifications, surface quality (anti-corrosion treatment) → cutting, beveling → spot welding with cone head or seal plate assembly → welding → Inspection → pre-anti-corrosion treatment → anti-corrosion treatment.
2) Bolt ball manufacturing process: steel bar (or ingot) for pressure processing or round steel for machining → forging blank → normalizing treatment → processing positioning thread hole (M20) and its surface → processing each thread hole and plane → processing worker number and ball number → anti-corrosion pretreatment → anti-corrosion treatment.
3) Cone head and sealing plate production process: finished steel blanking → die forging → normalizing → mechanical processing.
4) Welding ball joint grid manufacturing process: purchase steel pipe → inspection material, specifications, surface quality → lofting → cutting → hollow ball production → assembly → anti-corrosion treatment.
5) Welding hollow ball production process: blanking (with copying cutter) → pressing (heating) molding → machine tool or automatic gas cutting groove → welding → weld non-destructive inspection → anti-corrosion treatment → packaging.
8 Assembly
1) Before assembly, the staff must be familiar with the construction drawings and related technical requirements of the components, and review the quality of the parts to be assembled according to the requirements of the construction drawings.
2) Due to the insufficient size of raw materials, or technical requirements to splice parts, generally must be spliced before assembly.
3) The following requirements must be followed when using mold assembly:
(1) The selected site must be smooth and have sufficient strength.
(2) When arranging the assembly mold, the prerelease welding shrinkage and other various processing allowances must be considered according to the characteristics of the steel structure members.
(3) After assembling the first batch of components, it must be comprehensively inspected by the quality inspection department, and it can continue to assemble after passing the inspection.
(4) The components must be assembled in strict accordance with the process regulations during the assembly process, and when there are hidden welds, they must be welded first, and can be covered after passing the inspection. When there are complex assembly parts that are not easy to weld, the method of welding while assembling can also be used to complete the assembly work.
(5) In order to reduce deformation and assembly sequence, the method of first assembly into components and then assembly into components can be adopted.
4) The selection of the assembly method of steel structure components must be based on the structural characteristics and technical requirements of the components, combined with the processing capacity of the manufacturer, mechanical equipment, etc., to choose the method that can effectively control the quality of assembly and high production efficiency.
5) Typical structure assembly
(1) Welding H-beam construction technology
Process flow
Cutting → assembly → welding → correction → secondary cutting → hole making → welding other parts → correction and grinding
(2) Processing technology of box section components
(3) The processing technology of the rigid cross column
(4) General pipe rolling process flow chart
1) The number of pre-assembly shall be according to the design requirements and technical documents.
2) The selection principle of pre-assembly assembly parts: as far as possible, the main stress frame, the joint connection structure is complex, and the component tolerance is close to the limit and is representative of the composite components.
3) Pre-assembly should be carried out on a solid and stable platform tire frame. Its bearing point levelness:
A≤300 ~ 1000m2 Tolerance ≤2mm
A≤1000 to 5000m2 Tolerance < 3mm
(1) In the pre-assembly, all components should be controlled according to the construction drawings, and the center of gravity line of each bar should converge at the center of the node, and be completely in a free state, and no external force is allowed to be forced to fix. The supporting points of a single member, regardless of column, beam or support, should not be less than two supporting points.
(2) The control basis of pre-assembled components, and the center line should be clearly marked and relatively consistent with the platform baseline and ground baseline. The control basis should be consistent with the design requirements, and if the pre-assembly basis position needs to be changed, it should be approved by the process design.
(3) All components that need to be pre-assembled shall be single components that must be accepted by special inspectors and meet quality standards after production. The same single member should be interchangeable without affecting the overall geometry.
(4) During the whole process of preassembling the tire frame, the components shall not be modified or cut by means of flame or machinery, or the use of heavy weights for ballast, collision or hammering
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