Processing and connection technology of threaded connecting reinforcement

At present, in building construction, rebar thread connection mainly includes cone thread connection and straight thread connection. Straight thread connection is divided into rib stripping and rolling straight thread connection, direct rolling straight thread connection and upsetting straight thread connection. Because ordinary cone thread connection cannot reach the actual strength of rebar base material, It is difficult to ensure the dimensional accuracy of screw head thread for direct rolling straight thread connection. Considering the requirements of PC structure on reinforcement connection performance (according to Article 3.2.2 of technical specification for application of reinforcement sleeve grouting connection JGJ 355-2015), “the tensile strength of reinforcement sleeve grouting connection joint shall not be less than the standard value of tensile strength of connecting reinforcement, and the reinforcement outside the joint shall be broken in case of damage” That is, for the half grouting joint, it is not allowed to pull out the steel wire head from the sleeve, and it is not allowed to break at the root of the thread). The thread connection applied to PC structure mainly adopts rib stripping rolling straight thread connection and upsetting straight thread connection with more reliable connection performance.

1. Rib stripping and rolling straight thread connection

Connection process of rib stripping and rolling straight thread: rib stripping and turning shall be carried out on the end of reinforcement, rounding treatment shall be carried out, and then the connecting thread head shall be processed by rolling and connected with the threaded end of grouting sleeve.
For the thread processed by rib stripping and rolling, the base circle raw material of the reinforcement is basically not cut, and the reinforcement produces work hardening through rolling, which improves the strength of the raw material, so as to realize the purpose of equal strength connection of the reinforcement.
The processing technology has the advantages of simple operation, few processing procedures, stable and reliable joints and convenient construction; Good thread profile, high precision, no false thread, reliable and stable connection quality, which can reach the performance index of class I joint specified in JGJ 107.

2.Upsetting straight thread connection

Connection process of upsetting straight thread: first upsetting and strengthening the reinforcement end, and then machining the connecting thread head at the upsetting part by turning and threading, and connecting it with the threaded end of the grouting sleeve. Due to the increase of the diameter of the rear end of steel bar upsetting, sufficient cold work strengthening is obtained, and the connection strength after thread turning is reliably guaranteed. It can reach the performance index of class I joint specified in JGJ 107.

Note: due to the higher requirements for the connection performance of reinforcement, or the hard skin and soft core, it is impossible to roll through rib stripping alone

Rebar thread processing and connection process