Reinforcement mechanical connection technology is a new reinforcement connection technology, known as the “third generation reinforcement joint” after binding and electric welding. It has the advantages of joint strength higher than the base metal of steel cold extrusion reinforcement, speed 5 times faster than electric welding, no pollution, saving 20% of steel, etc. At present, the types of mechanical connection joints commonly used in the market are as follows:

Sleeve extrusion joint

A joint formed by plastic deformation of the steel sleeve of the connector through extrusion force and close engagement with the ribbed reinforcement. There are two forms, radial extrusion connection and axial extrusion connection. The axial extrusion connection has not been popularized due to inconvenient on-site construction and unstable joint quality; The radial extrusion connection technology has been popularized and used in a large area. Now the sleeve extrusion connection joints used in engineering are radial extrusion connections. Because of its excellent quality, sleeve extrusion joint has been widely used in Construction Engineering in China since the early 1990s.

Taper threaded joint

The joint is formed by the engagement of the special conical thread at the end of the reinforcement and the conical thread of the connector. The birth of taper thread connection technology overcomes the shortcomings of sleeve extrusion connection technology. The taper thread screw head is completely prefabricated in advance, and the on-site connection occupies a short construction period. It only needs a torque wrench to operate on site without moving equipment and pulling wires, which is highly praised by all construction units. However, the quality of taper thread joint is not stable enough. Because the machining thread weakens the cross-sectional area of the base metal, the joint strength is reduced, which can only reach 85 ~ 95% of the actual tensile strength of the base metal. There is still a certain gap between China’s conical thread connection technology and foreign countries. The most prominent problem is the single screw pitch. The screw pitch used for reinforcement with diameter of 16 ~ 40mm is 2.5mm, while the 2.5mm screw pitch is most suitable for the connection of reinforcement with diameter of 22mm. The connection strength of too thick or too thin reinforcement is not ideal, especially the conical thread connection of reinforcement with diameter of 36mm and 40mm, It is difficult to reach 0.9 times of the actual tensile strength of the base metal. Many production units claim to achieve the standard strength of steel bar base metal by using the super performance of steel bar base metal, that is, the actual tensile strength of steel bar is greater than the standard value of tensile strength of steel bar. Because the conical thread connection technology has the characteristics of fast construction speed and low joint cost, it has also been popularized and used in a large range since it was popularized in the early 1990s. However, due to the large defects, it has been gradually replaced by the straight thread connection joint.

Straight threaded joint

Straight thread equal strength straight thread connection joint is the latest international trend of reinforcement connection in the 1990s. The joint quality is stable and reliable, and the connection strength is high, which is comparable to the sleeve extrusion connection joint, and has the characteristics of convenient and fast construction of conical thread joint. Therefore, the emergence of straight thread connection technology has brought a qualitative leap to reinforcement connection technology. At present, China’s straight thread connection technology presents a scene of a hundred flowers in full bloom, and there are many forms of straight thread connection. Straight thread connection joints mainly include upsetting straight thread connection joints and rolling straight thread connection joints. The two processes adopt different processing methods to enhance the bearing capacity of the thread at the end of the reinforcement and achieve the purpose of equal strength between the joint and the base metal of the reinforcement.

Mechanical connection technology of WL double screw sleeve reinforcement

The joint of WL double screw sleeve reinforcement mechanical connection technology is composed of four connecting pieces: 1. Inner screw sleeve 2. Outer screw sleeve and lock nut, which are combined with externally threaded reinforcement.

This technology is developed by Beijing Wulongxing Technology Development Co., Ltd. and a new generation of reinforcement mechanical connection technology. It can completely change the traditional way that the mechanical connection of reinforcement needs to be connected one by one, and can become the overall connection of building parts (building components) and reinforcement parts (reinforcement cage, reinforcement mesh, etc.), which can greatly improve the construction speed of reinforcement engineering, and change the traditional manual operations such as reinforcement positioning and binding that need to be completed on site “Reinforcement processing and distribution center” completes the mechanized, automatic and intelligent processing of reinforcement, the mechanical prefabrication and molding of reinforcement parts and the overall installation and connection on the construction site. It will completely change the construction state of reinforcement engineering and is the core technology in the industrialization of reinforcement engineering.