The steel bar processing plant has a semi-automatic processing line for coarse and fine steel bars. Steel bars are cold drawn, derusted, cut, welded and bent into semi-finished products. Small steel bars such as column hoop and negative bending moment steel bar can be processed in the steel shed, while the operation of thick straight steel bar can be processed outside the shed.
1. Requirements for reinforcement materials
(1) When the reinforcement comes into the site, the Materials and Equipment Department will show the reinforcement quality certificate or test report, and conduct re-inspection as required. The quality certificate and reinspection report shall be made in triplicate, submitted to the person in charge of engineering support for verification and then sent to the reference room for filing.
(2) The inspection results of longitudinal reinforcement of frame structure shall be verified by the person in charge of engineering technology, and meet the following requirements: the ratio of measured reinforcement strength to measured yield strength (strength yield ratio) shall not be less than 1.25.
(3) Although the steel bar is qualified through re-inspection, it is in doubt during processing (such as brittle fracture, poor welding performance or obvious abnormal mechanical properties, etc.). ), chemical composition analysis should be carried out. Materials and Equipment Department shall take samples as required and send them to the laboratory designated by the supervision company for testing. (4) When the quality of hot rolled steel bars is in doubt or the grade is unknown, tensile and cold bending tests must be carried out, and this kind of steel bar is not allowed to be used until the test results are determined, but this kind of steel bar should not be used in the important parts of the main load-bearing structure.
2. Stacking and storage of steel bars
(1) After the reinforcement comes into the site, it shall be piled up by the construction team in strict accordance with the batch and specifications, and the materials and specifications shall not be confused. When stacking, the lower part should be padded with wood square, 5 ~ 10 cm away from the ground.
(2) Date of entry, certificate number, material, specification, quantity, number of parts used, inventory quantity, etc. The inspection of reinforcement shall be recorded by the construction team and the quality inspection registration account.
(3) The shift shall hang obvious signs near the material pile, indicating: entry date, material (steel grade), specification, quantity, etc.
(4) The remaining steel bars after processing shall be returned to their original places by the team according to the steel grade and specifications, or piled up separately, and the method and content shall also be identified when piled up separately.
3. Rebar substitution
Without the visa of the relevant personnel, the steel bar substitution certificate shall not be substituted.
Reinforcement substitution of important structures shall be signed by the design unit, otherwise it shall not be substituted.
4. Reinforcement batching
(1) The following matters should be paid attention to in steel bar batching: be familiar with the drawings carefully, make clear the drawings description, records of self-examination and joint examination, notice of design change, material substitution, etc. Find out the component parts, number of components, material specifications, etc. Familiar with the structure, strictly control the thickness of protective layer (referring to the protective layer of main reinforcement), meet the requirements of binding and installation, and do not cause construction difficulties. (2) The blanking length of steel bars is divided into the following two situations according to the form of steel bars: 1) Calculation of blanking length of straight steel bars.
Blanking length = member length-protective layers at both ends+hook length (round rebar). 2) Calculation of stirrup blanking length
Blanking length = stirrup circumference+hook increase length-bending elongation value stirrup quantity = main reinforcement length/stirrup spacing+1
3) After the batching calculation is completed, the batching member should fill in the batching list as the basis for processing steel bars.
5. Steel processing
The rebar processing shall be operated by the rebar operation team, and the rebar processing shall be started after the quality verification by the engineering technical director. (1) Cold-drawn straightening of steel bars
Hot-rolled disc steel bars with vertical warping of 6 ~ 12mm are straightened by JJM3.3t winch cold drawing method, and coarse vertical warping steel bars with vertical warping greater than 12mm are straightened manually. When straightening steel bars by cold drawing method, the cold drawing rate of grade I steel bars should be controlled within 4%. Before cold drawing, the operator shall conduct a comprehensive inspection of the hoist, cold-drawn trolley, track, fixture and steel wire rope, and operate it only after it is normal. During the cold control, people and vehicles are not allowed to stand 3 ~ 4m near the cold control line, otherwise isolation measures must be taken.
(2) Steel bar cutting 1) Steel bar cutting adopts GJ5-40 cutting machine, and the number of broken materials at a time shall not exceed the allowed number of cutting machines.
2) Preparation before steel bar cutting
Operators who process steel bars should check whether the grade, warping, size and quantity of steel bars are wrong according to the batching card, and then cut them off. According to the length of raw materials, the steel bars of the same specification are matched according to different lengths, and the long material is cut first and then the short material is cut to reduce waste. Before the blanking personnel operate, in order to ensure the accuracy of the size, the intuitive measurement method is adopted to cut a piece first. After verification, a large number of materials can be cut, and the allowable deviation of steel bar cutting is 5 mm; The cut steel bars shall be piled up according to the specifications, and the ingredient card (5cm×8cm're) shall be hung at one end of the steel bar and placed in an obviously accessible place.
3) Precautions for steel bar cutting
Before cutting steel bars, the operator must first check whether the blades of the cutting machine are installed correctly and firmly, and whether the lubricating oil is sufficient. Cutting steel bars can only be carried out after the cutting machine works normally. When cutting fine steel bars, the overlapping amount of the cutter blades (the longitudinal distance between the moving knife method and the fixed knife method along the running direction) is about 2mm. When cutting thick steel bars, the overlap of knife cutting should be appropriately reduced, and the longitudinal gap should be 0.5 ~1mm. The steel bar must be cut off after straightening, and the operator must hold the steel bar tightly and put it into use when the moving parts retreat. Short steel bars within 30cm should not be cut by cutting machine. When the cutting machine is started, steel bars shall not be put in, and steel bars exceeding the performance of the cutting machine shall not be processed. (3) Bending and forming
1) The bending of steel bars is processed by hand and bent. Before using manual bending, the molding operator should select the appropriate wrench and chassis according to the straightness of the bending steel bar. Only when bending with a bending machine, it is necessary to select the appropriate bending center and adjust the spacing of baffles according to the straightness of the steel bar, and then on the operating platform, the operator will mark the paragraphs of the formed steel bar according to the size of the batching plate. The bending machine adopts GJ7-40 type, and the finished steel bars are neatly stacked by the construction team according to the material number. Do not throw them around at will to avoid deformation. The batching board (5cm×8cm're) will be hung at one end of the steel bar and placed in a conspicuous place.
2) Matters needing attention in bending forming of bending machine:
Before operation, the operator should check whether all parts of the machine are normal, whether the electrical switch is flexible, and work can only be carried out after the machine runs normally. Long steel bars with a bending angle greater than 90 degrees should be bent outward, and collaborators are not allowed to stand during the bending stroke. When using GJ7-40 bending machine to change the direction of the workbench, it should be turned from forward to stop and then to reverse, and not from forward to reverse or from reverse to forward.
3) The hook length and bending radius of reinforcement shall meet the design requirements. If the design is not clear, it should meet the requirements of GB50204-92. It should be emphasized that the hook form and length at the stirrup joint should meet the specification requirements.
(4) Connection of longitudinal steel bars UN2- 150 butt welding machine and mechanical thread connection technology are adopted for the welding of longitudinal steel bars. 1) General regulations for flash butt welding: the joints of butt welded steel bars should not be placed at the parts with high stress, and the distance from the bend of steel bars should not be less than 10d(d is the diameter of steel bars), and the joints should not be placed on the same steel bar. Before the rebar is formally welded, or before the welder and rebar specifications are changed, welding shall be carried out, and two groups of specimens (3 pieces/group, one group of mechanical properties test and one group of cold bending test) shall be made. After passing the test, a large number of steel bars can be welded. For steel bars with seismic requirements, the joint should not be located in the stirrup encryption area at the beam end and column end.