Straight thread connection strength such as joint reinforced cohesion in the 90 s of the 20th century is the world's latest trend, joint quality stable reliable, high cohesive strength, equivalent to that of sleeve kneading bridging joints, and also has the taper thread joint construction convenience, speed characteristics, thus presented to steel straight thread connecting skills cohesion skills brought qualitative prance. At present, there are many kinds of straight thread connection methods in our country.
Straight thread connector mainly includes upsetting straight thread connector and rolling straight thread connector. These two processes choose different processing methods, enhance the bearing capacity of the steel end thread, to reach the joint and reinforcement base material and other strong intention.
Upsetting straight thread joint: a joint formed by the occlusion of the straight thread and the connector threads made by upsetting the steel end. The process is:
First, the steel bar end is upset by upsetting equipment, and then the thread is processed. The thread diameter is not less than the diameter of the steel bar base material, so that the joint and base material reach equal strength. Foreign straight thread upsetting joint, its steel end has hot upsetting and cold upsetting. The main purpose of hot upsetting is to eliminate the internal stress during upsetting, but the cost of heating equipment is high. In our country, the steel bar end of straight thread upsetting joint is mainly cold upsetting, which has high demand for ductility of steel bar. For steel bar with low ductility, upsetting quality is difficult to control, and it is easy to appear as brittle fracture appearance.
The advantages of upsetting straight thread joint are high strength, fast site construction speed, low labor intensity of workers, steel straight thread head all prefabricated in advance, site connection for installation. The deficiency lies in the upsetting process is easy to appear upsetting appearance, once upsetting it is necessary to cut off the re-upsetting; During the upsetting process, the internal stress occurs, some ductility of steel upsetting decreases, and it is easy to make brittle broken appearance. The screw thread processing needs two processes and two sets of equipment to complete.
Rolling straight thread connector: a joint formed by the bite of straight thread and connector threads made by directly rolling or squeezing (rolling) the rib at the steel end or after stripping the rib.
Three, sleeve kneading joint: after kneading force to make the joint plastic deformation of steel sleeve and ribbed steel tightly occluded joint. There are two methods, radial kneading connection and axial kneading connection. Because the axial kneading joint site construction is not convenient and the joint quality is not stable, it has not been implemented; The radial kneading skills and joints have been widely applied. Now the sleeve kneading joints used in the project are radial kneading joints. Because of its excellent quality, sleeve kneading connectors have been widely used in construction engineering in China from the early 1990s to now.
Post time: Jan-05-2022