The advantages of the direct rolling straight threaded rebar coupler are: the thread processing is simple, the equipment investment is small, the disadvantage is that the thread accuracy is poor, and the false thread phenomenon exists. Due to the uneven thickness of the steel bars, large tolerances, and inconsistent thread diameters, the on-site construction is difficult, and the coupler and the thread head are inconsistent with the tightness, and some joints may be pulled off. Due to the change of the steel bar diameter and the influence of the transverse and longitudinal ribs, the service life of the rolling wheel is reduced, the additional cost of the joint is increased, and the vulnerable parts of the construction site are frequently replaced.

Rolling ribs and rolling straight threaded reabar coupler: This kind of connection joint uses special extrusion equipment to pre-flatten the transverse and longitudinal ribs of the steel bars, and then roll the threads, the purpose is to reduce the effect of ribs on the accuracy of formed threads.

Its characteristic is that the precision of forming thread is improved to a certain extent relative to direct rolling, but the influence of inconsistent steel bar diameter on the precision of forming thread is still not fundamentally solved, and thread processing requires two processes and two sets of equipment to complete.