Abstract: steel bar straight thread sleeve is a kind of accessories used in building steel bar connection. It has the technical characteristics of high connection strength, stable and reliable connection quality, convenient construction, fast connection speed and environmental protection construction.
The use of steel bar connecting Sleeving in construction industry can greatly reduce the use of materials, and the operation is simple and not limited by the type of steel bar composition. It can be prefabricated in advance without occupying the construction period. Then, what specifications should be followed for the straight thread sleeve connection of reinforcement?
The joint strength meets the requirements of class I joint performance in the industrial standard jgj107-2010 general technical specification for mechanical connection of reinforcement.
The tensile strength of the joint shall not be less than 1.10 times of the actual tensile strength of the connected reinforcement or the standard tensile strength of the reinforcement. Good fatigue resistance. The joint has passed 2 million fatigue strength tests specified in the industry standard. Save materials.
Taking the reinforcement connecting Sleeving with a diameter of 40mm as an example, the mass of the extruded Sleeving is 4kg and the straight thread Sleeving is 1.1kg. The quality of straight thread Sleeving is 25% of that of extrusion sleeve, but the performance of joint is comparable to that of extrusion joint.
The reinforcement wire head processing is industrialized, which does not occupy the construction period.
On site connection and assembly, with short occupation time. The processing of steel wire head is simple.
The rib stripping and thread rolling processes can be completed by one-time clamping of reinforcement, with fast processing speed and high thread forming accuracy. Wide range of application.
There is no weldability requirement for reinforcement, which is applicable to the same and different diameter connection of HRB335 and HRB400 reinforcement with diameter of 14 ~ 50mm in any direction.
Reinforcement wire head processing and joint site construction are safe and reliable without noise pollution, open fire and smoke. energy conservation.
The power of the equipment is only 3 ~ 4kw, and there is no need for special distribution facilities and special wires.
Good low temperature resistance. Pass the – 400C low temperature test. All weather construction.
It is not affected by wind, rain, snow and other climatic conditions.
1). When connecting reinforcement, the specification of reinforcement and sleeve must be consistent, and the screw threads of reinforcement and sleeve shall be clean and intact.
2). When embedded joints are used, the position, specification and quantity of connecting sleeves shall meet the design requirements. The reinforcement with connecting sleeve shall be fixed firmly, and the exposed end of the connecting Sleeving shall be provided with protective cover.
3). The rolling straight thread joint shall be constructed with pipe wrench and torque wrench, and the two steel wire heads shall be pressed against each other in the middle of the sleeve. The tightening torque of the joint shall comply with the provisions of Table 4. The accuracy of torque wrench is ± 5%.
The reinforcement shall be provided with factory certificate and mechanical property inspection report, and all inspection results shall comply with the provisions of current specifications and design requirements.
The connecting sleeve shall be provided with factory certificate, generally low-alloy steel or high-quality carbon structural steel.
The standard value of tensile bearing capacity shall be greater than or equal to 1.20 times of the standard value of tensile bearing capacity of the connected reinforcement. The sleeve length shall be twice the diameter of the reinforcement.
The sleeve shall be provided with a protective cover, and the specification of the sleeve shall be indicated on the protective cover. The sleeve shall be protected from corrosion and contamination during transportation and storage
The following problems shall be comprehensively considered during reinforcement turnover:
1) The thickness of concrete protective layer of rolled straight thread joint shall meet the minimum thickness requirements of stressed reinforcement protective layer in the current national standard code for design of concrete structures, and shall not be less than 15nmm.
2) The positions of rolled straight thread joints of stressed reinforcement shall be staggered from each other. In the section from the center of any joint to the length of 35 times the diameter of the reinforcement, the cross-sectional area of the stressed reinforcement with joint accounts for the proportion of the reinforcement.
All operators engaged in the processing and connection of equal strength rib stripping and rolling straight thread thread head must undergo strict professional and technical training, pass the examination of the competent department and obtain the corresponding job certificate before they can work.
It is strictly prohibited for unlicensed personnel to leave or replace their posts.
The main machines used for equal strength rib stripping and rolling straight thread include grinding wheel cutting machine, straight thread forming machine, torque wrench, etc.
Process flow: blanking and flattening → rib stripping and thread rolling → thread head inspection → connection with sleeve → joint inspection → completion.
When rolling straight thread joint is applied in the project, the technical cooperation unit shall provide effective type inspection report. Before and during the reinforcement connection operation, the joint connection process inspection shall be carried out for each batch of mobilized reinforcement.
The process inspection shall meet the requirements of reinforcement connection joints of each specification, and there shall be no less than three specimens; The tensile strength test shall be conducted for the base metal of the reinforcement of the joint test piece.
According to the basic service conditions of straight thread sleeve, the commonly used sleeve models are divided into standard type, reducing type, positive and negative screw thread type, flared type
There are several types of reducing positive and negative screw thread type and lock nut type, and the sleeves of special models shall meet the relevant design requirements.