Advantages: 1.Bar-break feature guarantees fully ductile elongation. 2.No reduction of the bar cross-section area. Working principle: 1.We use GQ50 rebar cutting machine to splice up the end of the rebar. 2.We use Upset Forging Parallel Thread Machine to forge the end of rebar. 3.We use Parallel Thread Cutting Machine to thread the ends of the rebar which have been forged. 4.An upsetting coupler is used to link the two ends of rebar in parallel thread. Assembly benefit: 1.No torque wrench required. 2.Assembly validated by visual inspection. 3.Manufacturing of couplers under strict quality plans. 4.Standard ISO Parallel Metric Thread design.