In terms of structural characteristics, the inner wall threads at both ends of the reducer sleeve have different specifications, corresponding to two diameters of steel bars respectively (e.g., one end is suitable for 25mm steel bars, and the other end for 20mm steel bars). The thread precision reaches grade 6H, ensuring tight engagement with the straight threads rolled on the end of the steel bars. The overall sleeve adopts a stepped transition design, and the length of both ends is set according to the corresponding steel bar diameter (usually 1.5-2 times the respective diameter). The material is high-strength carbon structural steel or alloy structural steel. After quenching and tempering, it can bear the load transmitted by steel bars of different diameters, ensuring that the tensile strength of the joint is not lower than the base material strength of the smaller diameter steel bar.

During construction, it is necessary to first process straight threads on the steel bars of different diameters at both ends, then screw them into the two ends of the sleeve respectively, and apply the specified pre-tightening torque with a torque wrench (e.g., when connecting 25mm and 20mm steel bars, operate according to the torque standards of the corresponding diameters respectively) until the end of the steel bar reaches the specified position in the sleeve. The core advantages of this connection method are: first, flexible adaptation to diameter variation needs, solving the problem that steel bars of different diameters cannot be directly butted, and avoiding material waste caused by diameter variation in traditional binding lap joints; second, stable mechanical performance, ensuring that the joint does not become a weak link when bearing tension and shear force through equal-strength design; third, high construction convenience, no additional welding or 弯钩 treatment is required, the operation process is consistent with the standard type sleeve, the connection time of a single joint is about 1-2 minutes, and the applicable diameter difference is usually within one specification level (such as 22mm and 18mm, 32mm and 28mm, etc.), and products with larger diameter differences can also be customized for special needs.

Reducer type straight thread sleeves are mainly used in beam-column joints of high-rise buildings, transfer floor structures, connections between bridge piers and cap beams, etc. In scenarios where it is necessary to adjust the diameter of steel bars to adapt to load changes, their reliability and economy are significantly better than traditional connection methods, making them the core component for realizing mechanical connection of variable-diameter steel bars in modern building structures.