Intermediate frequency hot bending method for steel pipe

Abstract

The invention belongs to the field of water conservancy and hydropower engineering, and provides an intermediate frequency hot bending method for a steel pipe. A special bending jig frame is adopted in the method, fulcrums at two ends support the steel pipe, the steel pipe is symmetrically heated by adopting two pieces of intermediate frequency induction heating system equipment, pressure is applied to the steel pipe in the middle by using a hydraulic jack mechanism, the inner arc of the steel pipe is heated and pressed, the steel of the pipe wall is shrunk and deformed, and a catenary arch axis of design requirement is formed by technical means. The method makes the field hot bending of the ultra-long big-diameter high-strength steel pipe possible, fills the international and national blank, and brings huge economic benefit; intermediate frequency pipe bending machine purchasing and reforming costs can be saved, a large amount of big member transport cost can be saved, the pipe bending efficiency can be improved, and the processing cost is reduced; and the adopted intermediate frequency heating reduces the performance influence on the parent metal of the steel pipe, and simultaneously solves the catenary hot bending problem that X70 pipeline steel is applied to a bridge engineering arch rib.

Description

technical field [0001] The invention belongs to the field of water conservancy and hydropower engineering, and in particular relates to a medium-frequency bending method for steel pipes. Background technique [0002] In domestic bridge projects, the flame heating pipe bending process is generally adopted, such as the Lujiasi Bridge in Putuo District, Zhoushan City, etc. There are many defects in pyrotechnic pipe bending technology, mainly manifested as slow heating speed, uneven heating, high gas consumption cost, poor working environment, especially easy to affect the performance of steel pipe base material. [0003] Recently, the technology of medium-frequency heating pipe bending has also appeared. For example, Liaoyang Pipe Fittings Research Institute successfully designed and manufactured DN2000×150×9000mm large-diameter medium-frequency pipe bending machine in Daqing, and successfully made hot-simmered bending 1016×18mm elbow, the bending radius is 4D, and the ratio ...

AI Technical Summary

Problems solved by technology

After a lot of research and experiments, the applicant has proved that X70 pipeline steel can be used in construction steel structure engineering, and the mechanical properties of X70 pipeline steel are far superior to Q345 structural steel, while the price is lower than Q345 structural steel, but the site of X70 pipeline steel Intermediate frequency bending is a major technical problem