Products are widely used in different fields such as petroleum, chemical, electric power,
refrigeration, food, medicine, etc.
Tube expander development background
The tube expanding machine is mainly used for the connection between the heat exchange tube and the tube sheet. In the past, the heat exchange tube and the tube sheet mainly have several methods such as expansion joint, welding and expansion welding, and the expansion joint method can be divided into mechanical expansion joint and hydraulic expansion. Several methods, such as connection, rubber expansion and explosion expansion.
Domestic enterprises generally adopt the mechanical expansion method, which is labor intensive and has low work efficiency.
When the heat exchanger of the tube plate exceeds 100mm can not achieve full thickness expansion, and the actual expansion rate, pull-off force and sealing pressure are not directly related, the operator mainly determines the expansion tightness according to experience, and the quality of the expansion joint is artificial. The influence of factors is relatively large. And the lubricating medium used in the expansion joint will penetrate into the gap between the pipe and the tube sheet, which will adversely affect the subsequent welding quality.
In response to the above problems, Krips et al. developed hydraulic expansion technology in the late 1970s.
The technology has formed two differences, one is the O-ring method, and the other is the liquid bag expansion technology. The O-ring method is provided with an O-ring at each end of the mandrel to seal the expansion medium. The expansion pressure is directly applied to the surface of the heat exchange tube through the central hole of the mandrel, so that the heat exchange tube is plastically deformed and the tube sheet connected. Developed by Krips et al. is an O-ring method.
Due to the poor dimensional accuracy of the domestic heat exchange tubes, the wall thickness deviation of the tubes can reach ± 10%. The foreign O-ring expansion joint technology cannot expand the domestic heat exchange tubes, and the cost of importing foreign high-precision heat exchange tubes is too High, thus limiting the promotion of the technology in the country. The liquid bag type hydraulic expansion technology uses an elastic hydraulic bag to isolate the expansion tube medium from the heat exchange tube, and the expansion tube pressure acts on the inner wall of the heat exchange tube through the liquid bag, thereby avoiding the O-ring expansion joint technology in the expansion process. Pollution.
The domestic liquid bag type hydraulic expansion technology is aimed at the large deviation of the size of domestic heat exchange tubes. It absorbs foreign technology and continuously innovates and develops a new generation of hydraulic tube expander suitable for China's national conditions. It has been used in petrochemical, electric power, boiler, nuclear power and refrigeration. It has been widely used in the manufacture of heat exchangers in other fields.