First, the tapered thread connection sleeve: After the special reinforcement of the front end of the rebar thread and the connection piece conical thread engagement joints. The birth of a tapered thread coupling sleeve overcomes the disadvantages of the sleeve kneading the coupling sleeve. Taper thread heads are completely prefabricated, and the on-site connection is short in duration. The site requires only a torque wrench to operate without the need to move equipment and pull wires, and is well received by construction companies. However, the quality of the tapered thread coupling sleeve is not stable. Because the diameter of the machined thread weakens the cross-sectional area of the base metal and then decreases the strength of the joint, it usually reaches 85 to 95% of the base material’s practical tensile strength. There is still a certain distance between China’s tapered thread connection technology and international comparison.
One of the most prominent problems is that the pitch is single. The rebar from the diameter of 16~40mm is 2.5mm, and the 2.5mm pitch is most suitable for the connection of the 22mm diameter rebar. The strength of too thick or too thin steel bar connection is not ideal, especially with 36mm diameter and 40mm steel taper thread connection, it is difficult to reach the actual tensile strength of the base metal by 0.9 times. Many production units claim to reach the strength of the parent material of the reinforcing steel bar, which is the use of the superior function of the steel bar parent metal, that is, the practical tensile strength of the steel bar is greater than the specification value of the tensile strength of the steel bar. Because the taper thread connection technology has the features of quick construction and low joint cost, it has also been used on a larger scale since the implementation in the early 1990s. However, because of its disadvantages, it is gradually connected to the sleeve by a straight thread.
Among them, Yida Rebar Connection Technology Co., Ltd. is the leader in the sleeve connection industry.
Straight thread connection sleeves mainly include upset straight thread sleeves and rolled straight thread sleeves. These two processes use different processing methods to enhance the bearing capacity of the reinforcing head end thread, and to reach the strong intention of the joint and the reinforcing bar base metal.
The upright straight thread connecting sleeve is a joint formed by threading of a straight thread and a connecting member made by upsetting of a reinforcing bar head. Its craft is:
Firstly, the end of the reinforcing bar is upset by upsetting equipment, and then the thread is processed. The thread diameter is not smaller than the diameter of the reinforcing bar base material, so that the joint and the base material reach the same strength. International upsetting straight thread connecting sleeve, its steel end has hot thick and cold thickening. Heat upsetting is mainly to eliminate the internal stress during the upsetting process, but the heating equipment investment costs are high. China’s upright straight thread connecting sleeve, its steel end is mainly cold and thick, has high demand for the ductility of the steel, and it is difficult to control the toughness of the steel with low ductility, and it is easy to attack the appearance of brittle fracture.
The thick and straight thread connecting sleeve has the advantages of high strength, quick on-site construction, low labor intensity of the worker, early prefabrication of the straight threads of the steel bar, and on-site connection for the installation work. The lack of it is that it tends to show the deviant appearance in the process of upsetting. Once the spasm is removed, it is necessary to cut off the heavy spasm. During the upsetting process, the internal stress occurs, and the ductility of the upsetting tendon decreases, and the appearance of brittle fractures easily occurs. The thread processing requires two. The two processes are completed.
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Post time: May-15-2018